Hydrometallurgical recovery of metals from ironcontaining materials and other process streams

Abstract

Disclosed herein are processes for extracting and / or recovering iron and other metals and metal-containing compounds from a material comprising iron (e.g., bauxite residue and other iron-containing tailings and / or waste / process streams).

Description

Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)HYDROMETALLURGICAL RECOVERY OF METALS FROM IRON- CONTAINING MATERIALS AND OTHER PROCESS STREAMS1. BACKGROUND

[0001] Many industrial processes, such as alumina and aluminum production, generate substantial amounts of waste materials that can be hazardous and have detrimental environmental impacts. Most industrial production of alumina and aluminum centers around the Bayer process, an established approach involving pressure leaching of bauxite ore with sodium hydroxide solution. This process produces bauxite residue, also known as red mud, as a waste byproduct. The worldwide annual rate of bauxite residue generation is approximately 120 million tons, with most bauxite residue being stockpiled,

[0002] However, waste streams from industrial processes can also serve as a source for recycling and recovery of compounds and materials. For example, bauxite residue is an iron-rich material from w hich iron and other metals and metal-containing compounds, including rare-earth metals, titanium, additional aluminum, and compounds thereof, are available for extraction and / or recovery. Industrial Bayer processes also produce a sodium oxalate and gaseous carbon w aste streams that can serve as a source for repurposing, recycling, and / or recovering compounds.

[0003] Conventional approaches of processing bauxite residue to recover metals and metalcontaining compounds require high temperatures and specialized light sources. Such conventional approaches also do not provide for comprehensive repurposing, recycling, and / or recovery of other w aste streams from industrial production of alumina or aluminum, or from other processes couple to the Bayer process. Thus, there is a need for the development of processes that address these issues.2. SUMMARY

[0004] Disclosed herein are processes for extracting and / or recovering iron and other metals from materials composing iron. The material comprising iron can comprise any amount of iron. The iron may be present as a minor component or in low amount / concentration, as a major component or in high amount / concentration, or any lower, higher, or intermediate amount / concentration. The material comprising iron can be a bauxite residue (also known as red mud) comprising iron -containing tailings from an alumina / aluminum metal production process. Materials comprising iron also include iron-containing tailings from industrial processes, electric arc furnace dusts (e.g., electric arc furnace dusts containing iron and zincAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)(Zn)), gothites, jarosites, titanium materials, scandium materials, titanium-scandium materials, low grade iron ores, zinc refinery’ residues (e.g,, zinc refinery residues comprising zinc, gallium, and / or germanium), waste permanent rare-earth magnets, neodymium iron boron (NdFeB) magnets, and mill scales. Materials comprising iron for extraction and / or recovery of iron and other metals can also be derived from the tailings of other process streams or industrial processes and / or mining activities.

[0005] Extraction and / or recovery of metals can comprise a series of leaching and precipitation events comprising complexation chemistry, pH manipulations, and temperature manipulations. Iron extraction and / or recovery can involve formation of ferric oxalate upon leaching with oxalic acid. This leaching step can also complex and / or dissolve other metals, including aluminum, titanium, zinc, gallium, and germanium, into solution, which can allow for their separation in subsequent processes. The residue produced from this leaching event can also be utilized as the feed source for the extraction and / or recovery of mixed rare-earth metal oxide (mREO) products.

[0006] Leached materials generated during the processes can be recycled for reuse and to mitigate and / or repurpose waste / process streams. Sodium oxalate and other oxalate-containing tailings from any number of sources, including any of the processes and / or embodiments thereof disclosed herein, as well as waste / process streams from a Bayer Process, can be recycled for the recovery of oxalic acid for reuse in any of the processes and / or embodiments thereof disclosed herein (or any other suitable process). Gaseous carbon waste / process streams, such as carbon monoxide (CO) and carbon dioxide (CO2) waste / process streams, which may be generated during any of the processes and / or embodiments thereof disclosed herein, during a Bayer process, during a process associated with the Bayer process (e.g., from a thermal power plant), or any other process can also be recycled for the recovery of oxalic acid for reuse in any of the processes and / or embodiments thereof disclosed herein (or any other suitable process).

[0007] Accordingly, in a first aspect, the present disclosure provides a process 100 for extracting and / or recovering iron from a material comprising iron, the process comprising: leaching the material comprising iron with an oxalate-based leaching agent to produce a mixture comprising a first leachate and a first leach residue, wherein the first leachate comprises ferric oxalate; contacting the first leachate with an iron-containing reagent to produce ferrous oxalate (i.e., from the ferric oxalate); isolating the ferrous oxalate from the contacted first leachate; and converting the ferrous oxalate to iron.Attomey Ref: 43300-65026 / WO (0001-WO-NPV01)

[0008] In some embodiments, the process 100 for extracting and / or recovering iron from a material comprising iron comprises: leaching the material comprising iron with an oxalatebased leaching agent comprising oxalic acid to produce a mixture comprising a first leachate and a first leach residue, wherein the first leachate comprises ferric oxalate; contacting the first leachate with an iron-containing reagent comprising elemental iron to produce ferrous oxalate (i.e., from the ferric oxalate); isolating the ferrous oxalate from the contacted first leachate; and converting the ferrous oxalate to iron (e.g., by heating the ferrous oxalate to produce iron).

[0009] In a second aspect, the present disclosure provides a process 200 for extracting and / or recovering a metal or metal -containing compound (e.g., including, but not limited to, a rare- earth metal and / or rare-earth metal -containing compound) of a first leach residue (e.g., the first leach residue from the process 100 and / or embodiments thereof), the process comprising: contacting the first leach residue with a carbonate-based reagent, a bicarbonate-based reagent, or a combination thereof to produce a mixture comprising a second leachate and a second leach residue; contacting the second leachate with an acid (e.g., a mineral acid) to produce a mixture comprising a first precipitate and a second supernatant; isolating the second supernatant from the first precipitate; and contacting the second supernatant with a hydroxide-based reagent.

[0010] In some embodiments, the process 200 comprises: contacting the first leach residue with a carbonate-based reagent comprising sodium carbonate, a bicarbonate-based reagent comprising sodium bicarbonate, or a combination thereof to produce a mixture comprising a second leachate and a second leach residue; contacting the second leachate with an acid (e.g., a mineral acid) comprising sulfuric acid to produce a mixture comprising a first precipitate and a second supernatant; isolating the second supernatant from the first precipitate; and contacting the second supernatant with a hydroxide-based reagent comprising sodium hydroxide.

[0011] In a third aspect, the present disclosure provides a process 300 for extracting and / or recovering a metal or metal -containing compound (e.g., including, but not limited to, a rare-earth metal and / or rare-earth metal-containing compound) of a first leach residue (e.g., the first leach residue from the process 100 and / or embodiments thereof), the process comprising: contacting the first leach residue with an acid (e.g., a mineral acid); leaching the acid-contacted first leach residue with a solution comprising water to produce a mixture comprising a third leachate and a third leach residue, wherein the third leachate comprises a metal sulfate (e.g., a rare-earth metal sulfate); contacting the third leachate with an oxalate-Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)based reagent to produce a metal oxalate (e.g., a rare-earth metal oxalate) from the metal sulfate; and roasting the metal oxalate to produce a metal oxide (e.g., a rare-earth metal oxide).

[0012] In some embodiments, the process 300 comprises: contacting the first leach residue with an acid (e.g., a mineral acid) comprising sulfuric acid; leaching the sulfuric acid-contacted first leach residue with water to produce a mixture comprising a third leachate and a third leach residue, wherein the third leachate comprises a metal sulfate comprising a rare-earth metal sulfate; contacting the third leachate with an oxalate-based reagent comprising oxalic acid to produce a metal oxalate comprising a rare-earth metal oxalate from the metal sulfate comprising a rare-earth metal sulfate; and roasting the metal oxalate comprising a rare-earth metal oxalate to produce a metal oxide comprising a rare-earth metal oxide.

[0013] In a fourth aspect, the present disclosure provides a process 400 for extracting and / or recovering a metal or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof from a first supernatant (e.g., the first supernatant from the process 100 and / or embodiments thereof), the process comprising: contacting the first supernatant with an acid (e.g., mineral acid); heating the acid-contacted first supernatant to produce a mixture comprising a second precipitate and a third supernatant; isolating the third supernatant from the second precipitate; and contacting the third supernatant with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof.

[0014] In some embodiments, the process 400 comprises: contacting the first supernatant with an acid (e.g., a mineral acid) comprising sulfuric acid; heating the sulfuric acid-contacted first supernatant to produce a mixture comprising a second precipitate and a third supernatant; isolating the third supernatant from the second precipitate; and contacting the third supernatant with a hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, a metal oxide-based reagent comprising calcium oxide, or a combination thereof.

[0015] In a fifth aspect, the present disclosure provides a process 500 for recycling and / or recovering oxalic acid from one or more sources of oxalate (e.g,, oxalate-containing tailings), the process comprising: contacting the one or more sources of oxalate with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof to produce a mixture comprising a metal oxalate; and contacting the metal oxalate with an acid (e.g., mineral acid) to produce a mixture comprising oxalic acid.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0016] In some embodiments, the process 500 comprises: contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with a hydroxide-based reagent comprising calcium hydroxide, a metal oxide-based reagent comprising calcium oxide, or a combination thereof to produce a mixture comprising a calcium oxalate; and contacting the calcium oxalate with an acid (e.g., mineral acid) comprising sulfuric acid to produce a mixture comprising oxalic acid.

[0017] In a sixth aspect, the present disclosure provides a process 600 for extracting and / or recovering metals or metal-containing compounds comprising iron, aluminum, titanium, or a combination thereof from iron oxides, aluminum oxides, titanium oxides, or a combination thereof from a third leach residue (e.g., the third leach residue from the process 300 and / or embodiments thereof), the process comprising: contacting the third leach residue with an acid (e.g., mineral acid); and contacting the acid-contacted third leach residue with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof to produce a mixture comprising iron hydroxides (e.g., ferric hydroxide).

[0018] In some embodiments, the process 600 comprises: contacting the third leach residue with an acid (e.g., mineral acid) comprising sulfuric acid; and contacting the sulfuric acid- contacted third leach residue with a hydroxide-based reagent comprising calcium hydroxide, a metal oxide-based reagent comprising calcium oxide, or a combination thereof to produce a mixture comprising ferric hydroxide.

[0019] In a seventh aspect, the present disclosure provides a process 700 for extracting and / or recovering a metal or metal-containing compound comprising gallium, germanium, or the combination thereof from a first solvent extract (e.g., the first solvent extract from the process 400 and / or embodiments thereof), the process comprising: contacting the sample with an acid (e.g., mineral acid) to produce a mixture comprising a third precipitate and a sixth supernatant; isolating the sixth supernatant from the third precipitate; and contacting the sixth supernatant with a hydroxide-based reagent to produce a mixture comprising a fourth precipitate and a fifth spent solution.

[0020] In some embodiments, the process 700 comprises: contacting the sample with an acid (e.g,, mineral acid) comprising sulfuric acid to produce a mixture comprising a third precipitate and a sixth supernatant; isolating the sixth supernatant from the third precipitate; and contacting the sixth supernatant with a hydroxide-based reagent comprising sodium hydroxide to produce a mixture comprising a fourth precipitate and a fifth spent solution.

[0021] In an eighth aspect, the present disclosure provides a process 800 for recovering oxalic acid from a sample (e.g., a gas comprising CO (g)), the process comprising: convertingAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)the CO (g) present in the sample to an oxalic acid diester; dehydrating the oxalic acid diester; purifying the oxalic acid diester; and hydrolyzing the oxalic acid diester to oxalic acid.

[0022] In an ninth aspect, the present disclosure provides a product extracted, recovered, and / or prepared according to any of the processes and / or embodiments thereof (or combination of processes and / or embodiments thereof) disclosed herein. In some embodiments, a product extracted, recovered, and / or prepared according to one or more of the processes disclosed herein. In some embodiments, iron extracted, recovered, and / or prepared according to the process 100 and / or embodiments thereof. In some embodiments, iron extracted, recovered, and / or prepared from bauxite residue according to the process 100 and / or embodiments thereof. In some embodiments, a metal and / or metal-containing compound extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof. In some embodiments, a rare-earth metal and / or rare-earth metalcontaining compound extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof. In some embodiments, a rare-earth metal oxide extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof, In some embodiments, titania extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof. In some embodiments, a metal and / or metal-containing compound extracted, recovered, and / or prepared according to the process 300 and / or embodiments thereof. In some embodiments, a rare-earth metal and / or rare-earth metalcontaining compound extracted, recovered, and / or prepared according to the process 300 and / or embodiments thereof. In some embodiments, a rare-earth metal oxide extracted, recovered, and / or prepared according to the process 300 and / or embodiments thereof. In some embodiments, a metal and / or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or the combination thereof extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, aluminum hydroxide extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, zinc hydroxide extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, zinc carbonate extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, titania extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, oxalic acid recycled, extracted, recovered, and / or prepared according to the process 500 and / or embodiments thereof. In some embodiments, oxalic acid recycled, extracted, recovered, and / or prepared from one or more sources of oxalate according to the process 500Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)and / or embodiments thereof. In some embodiments, oxalic acid recycled, extracted, recovered, and / or prepared from sodium oxalate tailings from a Bayer process according to the process 500 and / or embodiments thereof. In some embodiments, oxalic acid in the form of a solution (e.g., aqueous solution) recycled, extracted, recovered, and / or prepared according to the process 500 and / or embodiments thereof. In some embodiments, a metal and / or metal-containing compound comprising iron, aluminum, titanium, or a combination thereof extracted, recovered, and / or prepared according to the process 600 and / or embodiments thereof. In some embodiments, iron hydroxides (e.g., ferric hydroxide) extracted, recovered, and / or prepared according to the process 600 and / or embodiments thereof. In some embodiments, a metal and / or metal -containing compound comprising gallium, germanium, or the combination thereof extracted, recovered, and / or prepared according to the process 700 and / or embodiments thereof. In some embodiments, gallium hydroxide extracted, recovered, and / or prepared according to the process 700 and / or embodiments thereof. In some embodiments, germanium hydroxide extracted, recovered, and / or prepared according to the process 700 and / or embodiments thereof. In some embodiments, oxalic acid recycled, extracted, recovered, and / or prepared according to the process 800 and / or embodiments thereof.3. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other features, aspects, and advantages of the present disclosure will become better understood with regard to the following description, and accompanying drawings.

[0024] FIG. 1 depicts a flow chart of an embodiment of the process 100.

[0025] FIG. 2 depicts a flow chart of an embodiment of the process 200.

[0026] FIG. 3 depicts a flow chart of an embodiment of tire process 200.

[0027] FIG. 4 depicts a flow chart of an embodiment of the process 300.

[0028] FIG. 5 depicts a flow chart of an embodiment of the process 300.

[0029] FIG. 6 depicts a flow chart of an embodiment of the process 400.

[0030] FIG. 7 depicts a flow chart of an embodiment of the process 400,

[0031] FIG. 8 depicts a flow chart of an embodiment of the process 500,

[0032] FIG. 9 depicts a flow chart of an embodiment of the process 500.

[0033] FIG. 10 depicts a flow chart of an embodiment of the process 600.

[0034] FIG. 11 depicts a flow chart of an embodiment of the process 600.

[0035] FIG. 12 depicts a flow chart of an embodiment of the process 700.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0036] FIG. 13 depicts a flow chart of an embodiment of the process 700.

[0037] FIG. 14 depicts a flow chart of an embodiment of the process 800.

[0038] FIG. 15 depicts a flow chart of an embodiment of a recycling scheme implementing aspects of the disclosed processes.4. DETAILED DESCRIPTION4.1. General Overview

[0039] Disclosed herein are processes (e.g., hydrometallurgical processes) for extracting and / or recovering iron (e.g., metallic iron, iron powder, and other forms of iron), iron oxides (e.g., Wüstite (FeO)), iron hydroxides (e.g., ferric hydroxide), and other metals and metal¬ containing compounds, including, but not limited to, rare-earth metals, rare-earth metal oxides, mixed rare-earth metal oxides (mREOs), titanium, titanium oxides (e.g., titania (TiO2)), aluminum, aluminum hydroxides (e.g., Al(OH)3), aluminum oxides (e.g., alumina (Al2O3)), gallium, gallium hydroxides (e.g., Ga(OH)3), gallium oxides, germanium, germanium hydroxides (e.g., Ge(OH)4), and germanium oxides. It will be understood by persons skilled in the relevant art that metals and metal -containing compounds (e.g., rare-earth metal containing compounds) also encompass mixed metals and mixed metal¬ containing compounds (e.g., mixed rare-earth metal containing compounds). As a non-binding and non-limiting example, rare-earth metal oxalates, rare-earth metal sulfates, and rare-earth metal oxides are understood to also encompass mixed rare-earth metal oxalates, mixed rare-earth metal sulfates, and mixed rare-earth metal oxides, respectively. As such, it will be understood by persons skilled in the relevant art that reference to or recitation of metals and metal-containing compounds, whether collectively or with respect to specific individual metals, also encompasses the corresponding mixed metals and mixed metal¬ containing compounds. Non-limiting exemplary sources / samples (e.g., industrial waste / process streams) from which iron and other metals and metal-containing compounds can be extracted and / or recovered, and which can serve as samples or input sources for the processes and / or embodiments thereof disclosed herein, include but are not limited to: bauxite residue, iron-containing tailings from industrial processes, electric arc furnace dusts (e.g,, electric arc furnace dusts containing iron and zinc (Zn)), gothites, jarosites, titanium materials, scandium materials, titanium-scandium materials, low grade iron ores, zinc refinery residues (e.g., zinc refinery residues comprising zinc, gallium, and / or germanium), waste permanent rare-earth magnets, NdFeB magnets, and mill scales.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0040] Also disclosed are processes for recycling and / or repurposing of sodium oxalate and other oxalate-containing tailings from any number of sources, as well as recycling and / or repurposing of gaseous waste / process streams comprising carbon monoxide (CO) and / or carbon dioxide (CO2), for extraction and / or recovery of oxalic acid. Oxalic acid extracted and / or recovered from these processes can be employed as the input source of oxalic acid for any of the processes and / or embodiments thereof disclosed herein (as well as any other processes). Non-limiting exemplary samples, sources, tailings, and waste / process streams from which oxalic acid can be extracted and / or recovered include: oxalate-containing tailings from one or more of the processes and / or embodiments thereof disclosed herein, any other process that produces oxalates and / or oxalate-containing tailings (e.g., sodium oxalate tailings from a Bayer process), and gaseous w'aste / process streams comprising carbon monoxide (CO) and / or carbon dioxide (CO2), including those from one or more of the processes and / or embodiments thereof disclosed herein, from thermal power plants, from steam methane reforming plants, and any other process that produces gaseous waste / process streams comprising carbon monoxide (CO) and / or carbon dioxide (CO2).

[0041] In some embodiments of the processes disclosed herein, the process can include leaching a material comprising iron (e.g., bauxite residue, tailing(s), waste / process stream(s), and source(s) comprising iron) with oxalic acid to generate an iron-rich leachate and a leach residue. The process can be a hydrothermal extraction process. Iron can be removed from the leachate in the form of ferrous oxalate. Ferrous oxalate can then be converted to iron (e.g., metallic iron, iron powder, pig iron, or another form of iron) in a low pC>2 and / or inert environment (e.g., a nitrogen (N2) environment), producing carbon gases (e.g., CO, CO2, O2, and / or other gases) which can be repurposed and / or recycled for recovery oxalic acid that can be utilized in additional leaching activities (e.g., subsequent cycles of the processes and / or embodiments thereof disclosed herein). Metals remaining in the leachate after separation of the ferrous oxalate can be recovered as metals and / or metal-containing compounds (e.g., metal complex products). The leach residue can also be processed for extraction and / or recovery of additional metals, including, but not limited to, rare-earth metals or rare-earth metal containing compounds (e g, mREOs).

[0042] In some embodiments of the processes disclosed herein, the process can be carried out under relatively mild temperatures (i.e., at temperatures lower than those of pyrometallurgical processes), without the use of specialized radiation sources (i.e., without ultraviolet or infrared irradiation from devices designed to produce ultraviolet or infrared radiation), and / orAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)without the need to dry the input sample(s) or source(s) of material comprising iron (e.g., the bauxite residue) from which metals and / or metal -containing compounds will be recovered.4.2. Processes for Extraction and / or Recovery of Iron from Materials Comprising Iron (e.g., Bauxite Residue)

[0043] As shown in FIG. 1, an aspect of the disclosure provides for a process 100 for extracting and / or recovering iron from a material comprising iron (e.g., iron-containing tailings from an industrial process, or any other suitable sample, including those disclosed herein), the process comprising: leaching the material comprising iron with an oxalate-based leaching agent to produce a mixture comprising a first leachate and a first leach residue, wherein the first leachate comprises ferric oxalate; contacting the first leachate with an iron-containing reagent to produce ferrous oxalate (i.e., from the ferric oxalate); isolating the ferrous oxalate from the contacted first leachate; and converting the ferrous oxalate to iron.

[0044] In some embodiments, the material comprising iron can include iron-containing tailings from industrial processes, electric arc furnace dusts (e.g., electric arc furnace dusts containing iron and zinc (Zn)), gothites, jarosites, titanium materials, scandium materials, titanium-scandium materials, low grade iron ores, zinc refinery residues (e.g., zinc refinery residues comprising zinc, gallium, and / or germanium), waste permanent rare-earth magnets, neodymium iron boron (NdFeB) magnets, and mill scales. In some embodiments, the material comprising iron comprises iron-containing tailings from an industrial process. In some embodiments, the material comprising iron comprises electric arc furnace dusts (e.g., electric arc furnace dusts containing iron and zinc). In some embodiments, the material comprising iron comprises gothites. In some embodiments, the material comprising iron comprises jarosites. In some embodiments, the material comprising iron comprises titanium materials (e.g., titanium materials which contain any amount of iron). In some embodiments, the material comprising iron comprises scandium materials (e.g., scandium materials which contain any amount of iron). In some embodiments, tire material comprising iron comprises titanium-scandium materials (e.g., titanium-scandium materials which contain any amount of iron). In some embodiments, the material comprising iron comprises low grade iron ores. In some embodiments, the material comprising iron comprises zinc refinery residues (e.g., zinc refinery residues comprising zinc, gallium, and / or germanium, and any amount of iron). In some embodiments, the material comprising iron comprises waste permanent rare-earth magnets. In some embodiments, the material comprising iron comprises neodymium iron boron (NdFeB) magnets. In some embodiments, the material comprising iron comprises millAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)scales. In some embodiments, the material comprising iron is selected from: bauxite residue, electric arc furnace dusts, gothites, jarosites, titanium-scandium wastes, low grade iron ores, zinc refinery residues, waste permanent rare-earth magnets, NdFeB magnets, mill scales, and a combination thereof.

[0045] In some embodiments, the material comprising iron is from a Bayer process. In some embodiments, the material comprising iron comprises bauxite residue. In some embodiments, the bauxite residue comprises raw bauxite residue from a Bayer process. In some embodiments, the raw bauxite residue is in the form of a slurry. In some embodiments, the raw bauxite residue slurry is used directly for the process 100 and / or embodiments thereof. In some embodiments, the bauxite residue from the Bayer process (e.g., the raw bauxite residue slurry) can be further treated (e.g., hydration, any other suitable treatment) prior to processing according to the process 100 and / or embodiments thereof.

[0046] In some embodiments, the oxalate-based leaching agent comprises oxalic acid, an oxalate salt, or a combination thereof. In some embodiments, the oxalate-based leaching agent is in the form of a solution. In some embodiments, the oxalate-based leaching agent is in the form of an aqueous solution. In some embodiments, the oxalate-based leaching agent comprises oxalic acid. In some embodiments, the oxalate-based leaching agent is oxalic acid. In some embodiments, the oxalic acid leaching agent is in the form of a solution. In some embodiments, the oxalic acid leaching agent is in the form of an aqueous solution.

[0047] In some embodiments, iron-containing reagent comprises elemental iron. In some embodiments, the elemental iron is selected from: iron powder, iron flakes, iron turnings, or a combination thereof. In some embodiments, the elemental iron comprises iron powder. In some embodiments, the elemental iron comprises iron flakes. In some embodiments, the elemental iron comprises iron turnings. In some embodiments, the elemental iron comprises a combination of iron powder, iron flakes, and iron turnings. In some embodiments, the elemental iron comprises a combination of iron powder and iron flakes. In some embodiments, the elemental iron comprises a combination of iron powder and iron turnings. In some embodiments, the elemental iron comprises a combination of iron flakes and iron turnings. In some embodiments, the elemental iron comprises at least one of: iron powder, iron flakes, and iron turnings. The iron-containing reagent and / or elemental iron may be any other suitable iron-containing reagent known to those of ordinary skill in the art.

[0048] In some embodiments, a pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range betweenAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)from about 0 to about 5, from about 0.5 to about 5, from about 1 to about 5, from about 1.5 to about 5, from about 2 to about 5, from about 2.5 to about 5, from about 3 to about 5, from about 3.5 to about 5, from about 4 to about 5, from about 4.5 to about 5, from about 0 to about 4.5, from about 0.5 to about 4.5, from about 1 to about 4.5, from about 1.5 to about 4.5, from about 2 to about 4.5, from about 2.5 to about 4.5, from about 3 to about 4.5, from about 3.5 to about 4.5, from about 4 to about 4.5, from about 0 to about 4, from about 0.5 to about 4, from about 1 to about 4, from about 1.5 to about 4, from about 2 to about 4, from about 2.5 to about 4, from about 3 to about 4, from about 3.5 to about 4, from about 0 to about 3.5, from about 0.5 to about 3.5, from about 1 to about 3.5, from about 1.5 to about 3.5, from about 2 to about 3.5, from about 2.5 to about 3.5, from about 3 to about 3.5, from about 0 to about 3, from about 0.5 to about 3, from about 1 to about 3, from about 1.5 to about 3, from about 2 to about 3, from about 2.5 to about 3, from about 0 to about 2.5, from about 0.5 to about 2.5, from about 1 to about 2.5, from about 1.5 to about 2.5, from about 2 to about 2.5, from about 0 to about 2, from about 0.5 to about 2, from about 1 to about 2, from about 1.5 to about 2, from about 0 to about 1.5, from about 0.5 to about 1.5, from about 1 to about 1.5, from about 0 to about 1, from about 0.5 to about 1, from about 0 to about 0.5, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 1 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 1.5 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 2 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 2.5 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 2.5, In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 2.5. In some embodiments, the pH during the leaching of the material comprising iron residue step is maintained in a range between from about 1 to about 2.5. hi some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 1.5 to about 2.5. In some embodiments, the pH during the leaching of the materialAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)comprising iron step is maintained in the range between from about 2 to about 2.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 2. In some embodiments, tire pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 1 to about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 1.5 to about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 1.5, In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 1.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 1 to about 1.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 1. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 1.

[0049] in some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 0, at about 0.1, at about 0.2, at about 0.3, at about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, about 3, about 3.1, about 3.2, about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, about 3.9, about 4, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9, about 5, lower than 0, greater than 5, or any other suitable pH. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 0. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 0.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 1. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 1.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 2.5 In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 3.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0050] In some embodiments, the pH or pH range during steps of the processes and / or embodiments thereof disclosed herein are maintained by addition of acids (e.g., organic acids, inorganic acids) or bases (e.g., organic bases, inorganic bases). In some embodiments, the pH or pH range during the leaching of the material comprising iron step is maintained by addition of acids (e.g., organic acids, inorganic acids) or bases (e.g., organic bases, inorganic bases). Any suitable acids and bases known to those of ordinary skill in the art can be used. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the mineral acid is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the mineral acid comprises hydrochloric acid. In some embodiments, the mineral acid comprises hydrobromic acid. In some embodiments, the mineral acid comprises hydroiodic acid. In some embodiments, the mineral acid comprises sulfuric acid. In some embodiments, the base is a hydroxide-based reagent. In some embodiments, the hydroxide- based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide, In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide. In some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0051] In some embodiments, the process 100 and / or embodiments thereof further comprises heating during the leaching of the material comprising iron step to maintain a temperature between from about 50 °C to about 120 °C, In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 50 °C to about 120 °C, from about 55 °C to about 120 °C, from about 60 °C to about 120 °C, from about 65 °C to about 120 °C, from about 70 °C to about 120 °C, from about 75 °C to about 120 °C, from about 80 °C to about 120 °C, from about 85 °C to about 120 °C, from about 90 °C to about 120 °C, from about 95 °C to about 120 °C, from about 100 °C to aboutAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)120 °C, from about 105 °C to about 120 °C, from about 110 °C to about 120 °C, from about 115 °C to about 120 °C, from about 50 °C to about 115 °C, from about 55 °C to about 115 °C, from about 60 °C to about 115 °C, from about 65 °C to about 115 °C, from about 70 °C to about 115 °C, from about 75 °C to about 115 °C, from about 80 °C to about 115 °C, from about 85 °C to about 115 °C, from about 90 °C to about 115 °C, from about 95 °C to about 115 °C, from about 100 °C to about 115 °C, from about 105 °C to about 115 °C, from about 110 °C to about 115 °C, from about 50 °C to about 110 °C, from about 55 °C to about 110 °C, from about 60 °C to about 110 °C, from about 65 °C to about 110 °C, from about 70 °C to about 110 °C, from about 75 °C to about 110 °C, from about 80 °C to about 110 °C, from about 85 °C to about 110 °C, from about 90 °C to about 110 °C, from about 95 °C to about 110 °C, from about 100 °C to about 110 °C, from about 105 °C to about 110 °C, from about 50 °C to about 105 °C, from about 55 °C to about 105 °C, from about 60 °C to about 105 °C, from about 65 °C to about 105 °C, from about 70 °C to about 105 °C, from about 75 °C to about 105 °C, from about 80 °C to about 105 °C, from about 85 °C to about 105 °C, from about 90 °C to about 105 °C, from about 95 °C to about 105 °C, from about 100 °C to about 105 °C, from about 50 °C to about 100 °C, from about 55 °C to about 100 °C, from about 60 °C to about 100 °C, from about 65 °C to about 100 °C, from about 70 °C to about 100 °C, from about 75 °C to about 100 °C, from about 80 °C to about 100 °C, from about 85 °C to about 100 °C, from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, from about 50 °C to about 95 °C, from about 55 °C to about 95 °C, from about 60 °C to about 95 °C, from about 65 °C to about 95 °C, from about 70 °C to about 95 °C, from about 75 °C to about 95 °C, from about 80 °C to about 95 °C, from about 85 °C to about 95 °C, from about 90 °C to about 95 °C, from about 50 °C to about 90 °C, from about 55 °C to about 90 °C, from about 60 °C to about 90 °C, from about 65 °C to about 90 °C, from about 70 °C to about 90 °C, from about 75 °C to about 90 °C, from about 80 °C to about 90 °C, from about 85 °C to about 90 °C, from about 50 °C to about 85 °C, from about 55 °C to about 85 °C, from about 60 °C to about 85 °C, from about 65 °C to about 85 °C, from about 70 °C to about 85 °C, from about 75 °C to about 85 °C, from about 80 °C to about 85 °C, from about 50 °C to about 80 °C, from about 55 °C to about 80 °C, from about 60 °C to about 80 °C, from about 65 °C to about 80 °C, from about 70 °C to about 80 °C, from about 75 °C to about 80 °C, from about 50 °C to about 75 °C, from about 55 °C to about 75 °C, from about 60 °C to about 75 °C, from about 65 °C to about 75 °C, from about 70 °C to about 75 °C, from about 50 °C to about 70 °C, from about 55 °C to about 70 °C, from about 60 °C to about 70 °C, from about 65 °C to about 70 °C, from about 50 °C to about 65 °C, from about 55 °C to about 65Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)°C, from about 60 °C to about 65 °C, from about 50 °C to about 60 °C, from about 55 °C to about 60 °C, from about 50 °C to about 65 °C, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 85 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 90 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 95 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 85 °C to about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 90 °C to about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 90 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 85 °C to about 90 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 85 °C.

[0052] In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 50 °C, about 51 °C, about 52 °C, about 53 °C, about 54 °C, about 55 °C, about 56 °C, about 57 °C, about 58 °C, about 59 °C, about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 67 °C, about 68 °C, about 69 °C, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, about 100 °C, about 101 °C, about 102 °C, about 103 °C, about 104 °C, about 105 °C, about 106 °C, about 107 °C, about 108 °C, about 109 °C, about 110 °C, about 111 °C, about 112 °C, about 113 °C, about 114 °C, about 115 °C, about 116 °C, about 117 °C, about 118 °C, about 119 °C, about 120 °C, below 50 °C, above 120 °C, or at any other suitable temperature. In some embodiments, the heating during theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)leaching of the material comprising iron step maintains the temperature at about 80 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 85 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 90 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 100 °C.

[0053] In some embodiments, the length of duration of leaching during the leaching of the material comprising iron step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0054] In some embodiments, the process 100 and / or embodiments thereof further comprises separating the first leachate from the first leach residue prior to contacting the first leachate with the iron-containing reagent to produce the ferrous oxalate. In some embodiments, separating the first leachate from the first leach residue comprises filtering the mixture comprising the first leachate and the first leach residue.

[0055] In some embodiments, the contacting the first leachate with the iron-containing reagent (e.g., iron powder) step comprises precipitating the ferrous oxalate to produce ferrous oxalate precipitate and a first supernatant, hi some embodiments, the first supernatant comprises a metal or metal-containing compound comprising, but not limited to, aluminum, titanium, zinc, gallium, germanium, or a combination thereof. In some embodiments, the metal or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof comprises titanium oxalates, aluminum oxalates, zinc oxalates, gallium oxalates, germanium oxalates, or a combination thereof. In some embodiments of the process 100 and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering the metal or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof from the first supernatant. In some embodiments, the metal or metal¬ containing compound comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof of the first supernatant is extracted and / or recovered according to the process 400 and / or embodiments thereof disclosed herein.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0056] In some embodiments, isolating the ferrous oxalate from the contacted first leachate (i.e., separating the ferrous oxalate precipitate from the first supernatant) comprises separating the ferrous oxalate from the contacted first leachate by filtration. In some embodiments, isolating the ferrous oxalate further comprises separating the ferrous oxalate from the iron-containing reagent (e.g., elemental iron, iron powder, iron turnings, iron flakes). In some embodiments, separating the ferrous oxalate from the iron -containing reagent comprises magnetic separation of the ferrous oxalate from the iron-containing reagent. Magnetic separation can be conducted using any suitable magnetic field known to those of ordinary’ skill in the art. In some embodiments, the iron-containing reagent is separated in the magnetic fraction. In some embodiments, the iron-containing reagent is recovered and optionally used for the contacting the first leachate step to further produce the ferrous oxalate.

[0057] In some embodiments, a pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 0 to about 7. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in the range between from about 0 to about 7, from about 0.5 to about 7, from about 1 to about 7, from about 1.5 to about 7, from about 2 to about 7, from about 2.5 to about 7, from about 3 to about 7, from about 3.5 to about 7, from about 4 to about 7, from about 4.5 to about 7, from about 5 to about 7, from about 5.5 to about 7, from about 6 to about 7, from about 6.5 to about 7, from about 0 to about 6.5, from about 0.5 to about 6.5, from about 1 to about 6.5, from about 1.5 to about 6.5, from about 2 to about 6.5, from about 2.5 to about 6.5, from about 3 to about 6.5, from about 3.5 to about 6.5, from about 4 to about 6.5, from about 4.5 to about 6.5, from about 5 to about 6.5, from about 5.5 to about 6.5, from about 6 to about 6.5, from about 0 to about 6, from about 0.5 to about 6, from about 1 to about 6, from about 1.5 to about 6, from about 2 to about 6, from about 2.5 to about 6, from about 3 to about 6, from about 3.5 to about 6, from about 4 to about 6, from about 4.5 to about 6, from about 5 to about 6, from about 5.5 to about 6, from about 0 to about 5.5, from about 0.5 to about 5.5, from about 1 to about 5.5, from about 1.5 to about 5.5, from about 2 to about 5.5, from about 2.5 to about 5.5, from about 3 to about 5.5, from about 3.5 to about 5.5, from about 4 to about 5.5, from about 4.5 to about 5.5, from about 5 to about 5.5, from about 0 to about 5, from about 0.5 to about 5, from about 1 to about 5, from about 1.5 to about 5, from about 2 to about 5, from about 2.5 to about 5, from about 3 to about 5, from about 3.5 to about 5, from about 4 to about 5, from about 4.5 to about 5, from about 0 to about 4.5, from about 0.5 to about 4.5, from about 1 to about 4.5, from about 1.5 to about 4.5, from about 2 toAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 4.5, from about 2.5 to about 4.5, from about 3 to about 4.5, from about 3.5 to about 4.5, from about 4 to about 4.5, from about 0 to about 4, from about 0.5 to about 4, from about 1 to about 4, from about 1.5 to about 4, from about 2 to about 4, from about 2.5 to about 4, from about 3 to about 4, from about 3.5 to about 4, from about 0 to about 3.5, from about 0.5 to about 3.5, from about 1 to about 3.5, from about 1.5 to about 3.5, from about 2 to about 3.5, from about 2.5 to about 3.5, from about 3 to about 3.5, from about 0 to about 3, from about 0.5 to about 3, from about 1 to about 3, from about 1.5 to about 3, from about 2 to about 3, from about 2.5 to about 3, from about 0 to about 2.5, from about 0.5 to about 2.5, from about 1 to about 2.5, from about 1.5 to about 2.5, from about 2 to about 2.5, from about 0 to about 2, from about 0.5 to about 2, from about 1 to about 2, from about 1.5 to about 2, from about 0 to about 1.5, from about 0.5 to about 1.5, from about 1 to about 1.5, from about 0 to about 1, from about 0.5 to about 1, from about 0 to about 0.5, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4 to about 6. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4.5 to about 6. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 5 to about 6, In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 5.5 to about 6. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4 to about 5,5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4.5 to about 5.5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 5 to about 5.5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4 to about 5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4.5 to about 5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained in a range between from about 4 to about 4.5.

[0058] In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained at about 0, at about 0.1, at about 0.2, at about 0.3, at about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 1.1, about 1.2,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, about 3, about 3.1, about 3.2, about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, about 3.9, about 4, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9, about 5, about 5.1, at about 5,2, at about 5.3, at about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6, about 6.1, at about 6.2, at about 6.3, at about 6.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, about 7, lower than 0, greater than 7, or any other suitable pH. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained at about 4, In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained at about 4.5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained at about 5. In some embodiments, the pH during the contacting the first leachate with the iron -containing reagent step is maintained at about 5.5, In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent step is maintained at about 6.

[0059] In some embodiments, the contacting the first leachate with the iron-containing reagent step further comprises heating the first leachate to maintain a temperature between from about 30 °C to about 70 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 30 °C to about 70 °C, from about 35 °C to about 70 °C, from about 40 °C to about 70 °C, from about 45 °C to about 70 °C, from about 50 °C to about 70 °C, from about 55 °C to about 70 °C, from about 60 °C to about 70 °C, from about 65 °C to about 70 °C, from about 30 °C to about 65 °C, from about 35 °C to about 65 °C, from about 40 °C to about 65 °C, from about 45 °C to about 65 °C, from about 50 °C to about 65 °C, from about 55 °C to about 65 °C, from about 60 °C to about 65 °C, from about 30 °C to about 60 °C, from about 35 °C to about 60 °C, from about 40 °C to about 60 °C, from about 45 °C to about 60 °C, from about 50 °C to about 60 °C, from about 55 °C to about 60 °C, from about 30 °C to about 55 °C, from about 35 °C to about 55 °C, from about 40 °C to about 55 °C, from about 45 °C to about 55 °C, from about 50 °C to about 55 °C, from about 30 °C to about 50 °C, from about 35 °C to about 50 °C, from about 40 °C to about 50 °C, from about 45 °C to about 50 °C, from about 30 °C to about 45 °C, from about 35 °C to about 45 °C, from about 40 °C to about 45 °C, from about 30 °C to about 40 °C, from about 35 °C to about 40 °C, from about 30 °C to about 35 °C, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, the contacting the firstAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 45 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 50 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 55 °C to about 60 °C, In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 55 °C. In some embodiments, the contacting the first leachate with the iron -containing reagent step comprises heating the first leachate to maintain a temperature between from about 45 °C to about 55 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 50 °C to about 55 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 50 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 45 °C to about 50 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 45 °C.

[0060] In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature at about 30 °C, about 31 °C, about 32 °C, about 33 °C, about 34 °C, about 35 °C, about 36 °C, about 37 °C, about 38 °C, about 39 °C, about 40 °C, about 41 °C, about 42 °C, about 43 °C, about 44 °C, about 45 °C, about 46 °C, about 47 °C, about 48 °C, about 49 °C, about 50 °C, about 51 °C, about 52 °C, about 53 °C, about 54 °C, about 55 °C, about 56 °C, about 57 °C, about 58 °C, about 59 °C, about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 66 °C, about 68 °C, about 69 °C, about 70 °C, below 30 °C, above 70 °C, or at any other suitable temperature. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature at about 40 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature atAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 45 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent step comprises heating the first leachate to maintain a temperature at about 50 °C. In some embodiments, the contacting the first leachate with the iron -containing reagent step comprises heating the first leachate to maintain a temperature at about 55 °C. In some embodiments, the contacting the first leachate with the iron -containing reagent step comprises heating the first leachate to maintain a temperature at about 60 °C.

[0061] In some embodiments, the length of duration of the contacting the first leachate with the iron-containing reagent step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2,5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4,5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0062] In some embodiments, converting the ferrous oxalate to iron can involve the use of thermal techniques / methods, electrochemical techniques / methods, and / or any other techniques / methods known to those of ordinary skill in the art. In some embodiments, converting the ferrous oxalate to iron comprises heating the ferrous oxalate. In some embodiments, converting the ferrous oxalate to iron comprises electrolysis of the ferrous oxalate. In some embodiments, converting the ferrous oxalate to iron according to any of the techniques / methods disclosed herein also produces iron oxides (i.e., converting the ferrous oxalate to iron comprises conversion of the ferrous oxalate to an iron oxide).

[0063] In some embodiments, converting the ferrous oxalate to iron comprises heating the ferrous oxalate. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 1100 °C. In some embodiments, the heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 1100 °C, from about 450 °C to about 1100 °C, from about 500 °C to about 1100 °C, from about 550 °C to about 1100 °C, from about 600 °C to about 1100 °C, from about 650 °C to about 1100 °C, from about 700 °C to about 1100 °C, from about 750 °C to about 1100 °C, from about 800 °C to about 1100 °C, from about 850 °C to about 1100 °C, from about 900 °C to about 1100 °C, from about 950 °C to about 1100 °C, from about 1000 °C to about 1100 °C, from about 1050 °C to about 1100 °C, about 400 °C to about 1050 °C, from about 450 °C to about 1050 °C, from about 500 °C to about 1050 °C, from about 550 °C to about 1050 °C, from about 600 °C to about 1050 °C, from about 650 °C to about 1050 °C, from about 700 °C to about 1050 °C, from about 750 °C to about 1050 °C, from about 800 °C to about 1050 °C, from about 850 °C to about 1050 °C, from about 900 °C to about 1050 °C,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)from about 950 °C to about 1050 °C, from about 1000 °C to about 1050 °C, about 400 °C to about 1000 °C, from about 450 °C to about 1000 °C, from about 500 °C to about 1000 °C, from about 550 °C to about 1000 °C, from about 600 °C to about 1000 °C, from about 650 °C to about 1000 °C, from about 700 °C to about 1000 °C, from about 750 °C to about 1000 °C, from about 800 °C to about 1000 °C, from about 850 °C to about 1000 °C, from about 900 °C to about 1000 °C, from about 950 °C to about 1000 °C, about 400 °C to about 950 °C, from about 450 °C to about 950 °C, from about 500 °C to about 950 °C, from about 550 °C to about 950 °C, from about 600 °C to about 950 °C, from about 650 °C to about 950 °C, from about 700 °C to about 950 °C, from about 750 °C to about 950 °C, from about 800 °C to about 950 °C, from about 850 °C to about 950 °C, from about 900 °C to about 950 °C, about 400 °C to about 900 °C, from about 450 °C to about 900 °C, from about 500 °C to about 900 °C, from about 550 °C to about 900 °C, from about 600 °C to about 900 °C, from about 650 °C to about 900 °C, from about 700 °C to about 900 °C, from about 750 °C to about 900 °C, from about 800 °C to about 900 °C, from about 850 °C to about 900 °C, about 400 °C to about 850 °C, from about 450 °C to about 850 °C, from about 500 °C to about 850 °C, from about 550 °C to about 850 °C, from about 600 °C to about 850 °C, from about 650 °C to about 850 °C, from about 700 °C to about 850 °C, from about 750 °C to about 850 °C, from about 800 °C to about 850 °C, about 400 °C to about 800 °C, from about 450 °C to about 800 °C, from about 500 °C to about 800 °C, from about 550 °C to about 800 °C, from about 600 °C to about 800 °C, from about 650 °C to about 800 °C, from about 700 °C to about 800 °C, from about 750 °C to about 800 °C, about 400 °C to about 750 °C, from about 450 °C to about 750 °C, from about 500 °C to about 750 °C, from about 550 °C to about 750 °C, from about 600 °C to about 750 °C, from about 650 °C to about 750 °C, from about 700 °C to about 750 °C, about 400 °C to about 700 °C, from about 450 °C to about 700 °C, from about 500 °C to about 700 °C, from about 550 °C to about 700 °C, from about 600 °C to about 700 °C, from about 650 °C to about 700 °C, from about 400 °C to about 650 °C, from about 450 °C to about 650 °C, from about 500 °C to about 650 °C, from about 550 °C to about 650 °C, from about 600 °C to about 650 °C, from about 400 °C to about 600 °C, from about 450 °C to about 600 °C, from about 500 °C to about 600 °C, from about 550 °C to about 600 °C, from about 400 °C to about 550 °C, from about 450 °C to about 550 °C, from about 500 °C to about 550 °C, from about 400 °C to about 500 °C, from about 450 °C to about 500 °C, from about 400 °C to about 450 °C, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to aboutAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)700 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 450 °C to about 700 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 500 °C to about 700 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 550 °C to about 700 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 600 °C to about 700 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 650 °C to about 700 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 650 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 450 °C to about 650 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 500 °C to about 650 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 550 °C to about 650 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 600 °C to about 650 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 600 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 450 °C to about 600 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 500 °C to about 600 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 550 °C to about 600 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 550 °C. in some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 450 °C to about 550 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 500 °C to about 550 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 500 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 450 °C to about 500 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 450 °C. In some embodiments, heating the ferrous oxalate further comprises conversion of the ferrous oxalate to an iron oxide. In some embodiments, the iron oxide comprises FeO.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0064] In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 400 °C, about 425 °C, about 450 °C, about 475 °C, about 500 °C, about 525 °C, about 550 °C, about 575 °C, about 600 °C, about 625 °C, about 650 °C, about 675 °C, about 700 °C, about 725 °C, about 750 °C, about 775 °C, about 800 °C, about 825 °C, about 850 °C, about 875 °C, about 900 °C, about 925 °C, about 950 °C, about 975 °C, about 1000 °C, about 1025 °C, about 1050 °C, about 1075 °C, about 1100 °C, or at any other suitable temperature. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 400 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 425 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 450 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 475 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 500 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 525 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 550 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 575 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 600 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 625 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 650 °C. hi some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 675 °C. In some embodiments, heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature of about 700 °C.

[0065] In some embodiments, heating the ferrous oxalate comprises heating under an ambient environment, an inert environment, or a low pCh environment. In some embodiments, the ferrous oxalate is heated under an ambient environment. In some embodiments, the ferrous oxalate is heated under an inert environment. In some embodiments, the ferrous oxalate is heated under a low pO? environment. In some embodiments, the inert environment comprises N2 (g). In some embodiments, the low pCh environment comprises M2 (g), H2 (g), CO (g), CO2 (g), H2O (g), O2 (g), or a mixture thereof. In some embodiments, the low pO2 environment comprises a mixture of N?. (g) and H2 (g). In some embodiments, the low pO₂ environment comprises CO (g), CO₂ (g), H₂O (g), O₂ (g), or a mixture thereof. In some embodiments, the low pO₂ environment comprises CO (g), CO₂Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)(g), H₂O (g), or a mixture thereof. In some embodiments, the low pO₂ environment comprises CO (g), CO₂ (g), or a mixture thereof. In some embodiments, the low pO₂ environment comprises N₂ (g). In some embodiments, the low pO₂ environment comprises H₂ (g). In some embodiments, the low pO₂ environment comprises CO (g). In some embodiments, the low pO₂ environment comprises CO₂ (g). In some embodiments, the low pO₂ environment comprises H₂O (g). In some embodiments, the low pO₂ environment comprises O₂ (g). In some embodiments, the low pO₂ environment comprises CO (g), CO₂ (g), H₂O (g), O₂ (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate). In some embodiments, a portion of the low pO₂ environment comprises CO (g), CO₂ (g), H₂O (g), O₂ (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate). In some embodiments, the low pO₂ environment comprises CO (g), CO₂ (g), H₂O (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate). In some embodiments, a portion of the low pO₂ environment comprises CO (g), CO₂ (g), H₂O (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate).

[0066] In some embodiments, the ferrous oxalate is heated in the presence of a carbon source. The carbon source can be any suitable source that produces carbon suitable for aiding in the reduction of ferrous oxalate (e.g., reduction of ferrous oxalate to iron). In some embodiments, the ferrous oxalate is heated in the presence of carbon. In some embodiments, the carbon is derived from a carbon source comprising graphite. In some embodiments, the ferrous oxalate is heated in the presence of powdered carbon. In some embodiments, the ferrous oxalate is heated in the presence of solid carbon.

[0067] In some embodiments, the length of duration of heating the ferrous oxalate can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration,

[0068] In some embodiments, heating the ferrous oxalate also produces carbon monoxide (CO), carbon dioxide (CO₂), moisture, carbon, or a mixture thereof. In some embodiments, heating the ferrous oxalate also produces carbon monoxide (CO), carbon dioxide (CO₂), moisture, or a mixture thereof. In some embodiments, heating the ferrous oxalate also produces carbon monoxide (CO). In some embodiments, heating the ferrous oxalate alsoAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)produces carbon dioxide (CO2). In some embodiments, heating the ferrous oxalate also produces moisture. In some embodiments, heating the ferrous oxalate also produces carbon.

[0069] In some embodiments, the process 100 and / or embodiments thereof are carried out under ambient light conditions. In some embodiments, the process 100 and / or embodiments thereof do not comprise illumination with a UV-light or an infrared-light source device. In some embodiments, the process 100 and / or embodiments thereof do not comprise illumination with a UV-light source device. In some embodiments, the process 100 and / or embodiments thereof do not comprise illumination with an infrared-light source device.

[0070] In some embodiments, the iron produced according to the process 100 and / or embodiments thereof comprises at least one of: metallic iron, elemental iron, iron powder, iron flakes, iron turnings, and pig iron. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of metallic iron, iron powder, iron flakes, iron turnings, pig iron, or a mixture thereof. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of metallic iron. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of iron powder. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of iron flakes. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of iron turnings. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of pig iron.

[0071] As shown in FIG. 1, in an embodiment of the process 100 for extracting and / or recovering iron from a material comprising iron, the process comprises: leaching the material comprising iron with an oxalate-based leaching agent comprising oxalic acid to produce a mixture comprising a first leachate and a first leach residue, wherein the first leachate comprises ferric oxalate; contacting the first leachate with an iron-containing reagent comprising elemental iron (e.g., iron powder) to produce ferrous oxalate from the ferric oxalate; isolating the ferrous oxalate from the contacted first leachate; and converting the ferrous oxalate to iron by heating the ferrous oxalate to produce iron.

[0072] In some embodiments, the material comprising iron can include iron-containing tailings from industrial processes, electric arc furnace dusts (e.g., electric arc furnace dusts containing iron and zinc (Zn)), gothites, jarosites, titanium materials, scandium materials, titanium-scandium materials, low grade iron ores, zinc refinery residues (e.g., zinc refinery residues comprising zinc, gallium, and / or germanium), waste permanent rare-earth magnets, neodymium iron boron (NdFeB) magnets, and mill scales. In some embodiments, theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)material comprising iron is selected from: bauxite residue, electric arc furnace dusts, gothites, jarosites, titanium-scandium wastes, low grade iron ores, zinc refinery residues, waste permanent rare-earth magnets, NdFeB magnets, mill scales, and a combination thereof. In some embodiments, the material comprising iron is from a Bayer process. In some embodiments, the material comprising iron comprises bauxite residue. In some embodiments, the bauxite residue comprises raw bauxite residue from a Bayer process. In some embodiments, the raw bauxite residue is in the form of a slurry. In some embodiments, the raw bauxite residue slurry is used directly for the process 100 and / or embodiments thereof. In some embodiments, the bauxite residue from the Bayer process (e.g., the raw bauxite residue slurry) can be further treated (e.g., hydration, any other suitable treatment) prior to processing according to the process 100 and / or embodiments thereof.

[0073] In some embodiments, the oxalate-based leaching agent comprising oxalic acid is in the form of a solution. In some embodiments, the oxalate-based leaching agent comprising oxalic acid is in the form of an aqueous solution. In some embodiments, the oxalate-based leaching agent is oxalic acid. In some embodiments, the oxalic acid leaching agent is in the form of a solution. In some embodiments, the oxalic acid leaching agent is in the form of an aqueous solution.

[0074] In some embodiments, the iron-containing reagent comprising elemental iron is selected from: iron powder, iron flakes, iron turnings, or a combination thereof. In some embodiments, the iron-containing reagent comprising elemental iron comprises iron powder. In some embodiments, the iron-containing reagent comprising elemental iron comprises iron flakes. In some embodiments, the iron-containing reagent comprising elemental iron comprises iron turnings. In some embodiments, the iron-containing reagent comprising elemental iron comprises a combination of iron powder, iron flakes, and iron turnings. In some embodiments, the iron-containing reagent comprising elemental iron comprises a combination of iron powder and iron flakes. In some embodiments, the iron-containing reagent comprising elemental iron comprises a combination of iron powder and iron turnings. In some embodiments, the iron-containing reagent comprising elemental iron comprises a combination of iron flakes and iron turnings. In some embodiments, the iron-containing reagent comprising elemental iron comprises at least one of: iron powder, iron flakes, and iron turnings.

[0075] In some embodiments, a pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range betweenAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)from about 0 to about 3, from about 0.5 to about 3, from about 1 to about 3, from about 1.5 to about 3, from about 2 to about 3, from about 2.5 to about 3, from about 0 to about 2,5, from about 0.5 to about 2.5, from about 1 to about 2.5, from about 1.5 to about 2.5, from about 2 to about 2.5, from about 0 to about 2, from about 0.5 to about 2, from about 1 to about 2, from about 1.5 to about 2, from about 0 to about 1.5, from about 0.5 to about 1,5, from about 1 to about 1.5, from about 0 to about 1, from about 0.5 to about 1, or from about 0 to about 0.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 1 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 1.5 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 2 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 2.5 to about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 2.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0,5 to about 2.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 1 to about 2.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 1.5 to about 2.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 2 to about 2.5. hi some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 1 to about 2, In some embodiments, the pH during the leaching of the material comprising iron step is maintained in the range between from about 1.5 to about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 1.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 1.5. In some embodiments, the pH during theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)leaching of the material comprising iron step is maintained in a range between from about 1 to about 1.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 1. In some embodiments, the pH during the leaching of the material comprising iron step is maintained in a range between from about 0.5 to about 1.

[0076] In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 0, at about 0.1, at about 0.2, at about 0.3, at about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1,6, about 1,7, about 1.8, about 1.9, about 2, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, or about 3. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 0. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 0.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 1. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 1.5. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 2. In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 2.5 In some embodiments, the pH during the leaching of the material comprising iron step is maintained at about 3.

[0077] In some embodiments, the pH or pH range during the leaching of the material comprising iron step is maintained by addition of acids (e.g., organic acids, inorganic acids) or bases (e.g., organic bases, inorganic bases). Any suitable acids and bases known to those of ordinary skill in the art can be used. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the mineral acid is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the mineral acid comprises hydrochloric acid. In some embodiments, the mineral acid comprises hydrobromic acid. In some embodiments, the mineral acid comprises hydroiodic acid. In some embodiments, the mineral acid comprises sulfuric acid. In some embodiments, the base is a hydroxide-based reagent. In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof, hi some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)the alkali metal hydroxide comprises lithium hydroxide, hi some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide, hi some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide,

[0078] In some embodiments, the process 100 and / or embodiments thereof further comprises heating during the leaching of the material comprising iron step to maintain a temperature between from about 80 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 100 °C, from about 85 °C to about 100 °C, from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, from about 80 °C to about 95 °C, from about 85 °C to about 95 °C, from about 90 °C to about 95 °C, from about 80 °C to about 90 °C, from about 85 °C to about 90 °C, or from about 80 °C to about 85 °C. In some embodiments, the heating during tire leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 100 °C, In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 85 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 90 °C to about 100 °C, In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 95 °C to about 100 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 85 °C to about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 90 °C to about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 90 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature between from about 85 °C to about 90 °C. In some embodiments, the heating during theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)leaching of the material comprising iron step maintains the temperature between from about 80 °C to about 85 °C.

[0079] In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, or about 100 °C. in some embodiments, tlie heating during tlie leaching of the material comprising iron step maintains the temperature at about 80 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 85 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 90 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 95 °C. In some embodiments, the heating during the leaching of the material comprising iron step maintains the temperature at about 100 °C.

[0080] In some embodiments, the length of duration of leaching during the leaching of the material comprising iron step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0081] In some embodiments, the process 100 and / or embodiments thereof further comprises separating the first leachate from the first leach residue prior to contacting the first leachate with the iron-containing reagent comprising elemental iron (e.g. iron powder) to produce the ferrous oxalate. In some embodiments, separating the first leachate from the first leach residue comprises filtering the mixture comprising the first leachate and the first leach residue,

[0082] In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron (e.g., iron powder) step comprises precipitating the ferrous oxalate to produce ferrous oxalate precipitate and a first supernatant. In some embodiments, the first supernatant comprises metals or metal -containing compounds comprising, but not limited to, aluminum, titanium, zinc, gallium, germanium, or a combination thereof. In some embodiments, the metals or metal-containing compounds comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof comprise titanium oxalates, aluminum oxalates, zinc oxalates, gallium oxalates, germanium oxalates, or a combination thereof. InAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)some embodiments of the process 100 and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering the metals or metalcontaining compounds comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof from the first supernatant. In some embodiments, the metals or metal¬ containing compounds comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof of the first supernatant are extracted and / or recovered according to the process 400 and / or embodiments thereof disclosed herein.

[0083] In some embodiments, isolating the ferrous oxalate from the contacted first leachate (i.e., separating the ferrous oxalate precipitate from the first supernatant) comprises separating the ferrous oxalate from the contacted first leachate by filtration. In some embodiments, isolating the ferrous oxalate further comprises separating the ferrous oxalate from the iron-containing reagent comprising elemental iron (e.g., elemental iron, iron powder, iron turnings, iron flakes). In some embodiments, separating the ferrous oxalate from the iron-containing reagent comprising elemental iron comprises magnetic separation of the ferrous oxalate from the iron-containing reagent comprising elemental iron. Magnetic separation can be conducted using any suitable magnetic field known to those of ordinary skill in tire art. In some embodiments, the iron-containing reagent comprising elemental iron is separated in the magnetic fraction. In some embodiments, the iron-containing reagent comprising elemental iron is recovered and optionally used for the contacting the first leachate step to further produce the ferrous oxalate.

[0084] In some embodiments, a pH during the contacting the first leachate with the iron- containing reagent comprising elemental iron step is maintained in a range between from about 4 to about 6. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in the range between from about 4 to about 6, from about 4.5 to about 6, from about 5 to about 6, from about 5.5 to about 6, from about 4 to about 5.5, from about 4.5 to about 5.5, from about 5 to about 5.5, from about 4 to about 5, from about 4.5 to about 5, or from about 4 to about 4.5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in a range between from about 4 to about 6. In some embodiments, the pH during tire contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in a range between from about 4.5 to about 6. In some embodiments, the pH during the contacting the first leachate with the iron- containing reagent comprising elemental iron step is maintained in a range between from about 5 to about 6. In some embodiments, the pH during the contacting the first leachate withAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)the iron-containing reagent comprising elemental iron step is maintained in a range between from about 5.5 to about 6, In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in a range between from about 4 to about 5.5. In some embodiments, the pH during the contacting the first leachate with the iron -containing reagent comprising elemental iron step is maintained in a range between from about 4.5 to about 5.5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in a range between from about 5 to about 5.5. In some embodiments, the pH during the contacting the first leachate with the iron -containi ng reagent comprising elemental iron step is maintained in a range between from about 4 to about 5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in a range between from about 4.5 to about 5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained in a range between from about 4 to about 4.5.

[0085] In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained at about 4, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9, about 5, about 5.1, at about 5,2, at about 5.3, at about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, or about 6. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained at about 4. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained at about 4.5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained at about 5. In some embodiments, the pH during the contacting the first leachate with the iron-containing reagent comprising elemental iron step is maintained at about 5.5. In some embodiments, the pH during the contacting the first leachate with the iron- containing reagent comprising elemental iron step is maintained at about 6.

[0086] In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemen tal iron step further comprises heating the first leachate to maintain a temperature between from about 40 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 60 °C, from about 45 °C to about 60 °C, from about 50 °C to about 60 °C, from aboutAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)55 °C to about 60 °C, from about 40 °C to about 55 °C, from about 45 °C to about 55 °C, from about 50 °C to about 55 °C, from about 40 °C to about 50 °C, from about 45 °C to about 50 °C, or from about 40 °C to about 45 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 45 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step composes heating the first leachate to maintain a temperature between from about 50 °C to about 60 °C. In some embodiments, the contacting the first leachate with tire iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 55 °C to about 60 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 55 °C. In some embodiments, the con tacting the first leachate with the iron -containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 45 °C to about 55 °C. In some embodiments, the contacting the first leachate with the iron -containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 50 °C to about 55 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 50 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 45 °C to about 50 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature between from about 40 °C to about 45 °C.

[0087] In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature at about 40 °C, about 41 °C, about 42 °C, about 43 °C, about 44 °C, about 45 °C, about 46 °C, about 47 °C, about 48 °C, about 49 °C, about 50 °C, about 51 °C, about 52. °C, about 53 °C, about 54 °C, about 55 °C, about 56 °C, about 57 °C, about 58 °C, about 59 °C, or about 60 °C. In some embodiments, the contacting the first leachate with the iron-containingAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature at about 40 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature at about 45 °C. In some embodiments, the contacting the first leachate with the iron step comprises heating the first leachate to maintain a temperature at about 50 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature at about 55 °C. In some embodiments, the contacting the first leachate with the iron-containing reagent comprising elemental iron step comprises heating the first leachate to maintain a temperature at about 60 °C.

[0088] In some embodiments, the length of duration of the contacting the first leachate with the iron-containing reagent comprising elemental iron step can be about 0,5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0089] In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 700 °C, from about 450 °C to about 700 °C, from about 500 °C to about 700 °C, from about 550 °C to about 700 °C, from about 600 °C to about 700 °C, from about 650 °C to about 700 °C, from about 400 °C to about 650 °C, from about 450 °C to about 650 °C, from about 500 °C to about 650 °C, from about 550 °C to about 650 °C, from about 600 °C to about 650 °C, from about 400 °C to about 600 °C, from about 450 °C to about 600 °C, from about 500 °C to about 600 °C, from about 550 °C to about 600 °C, from about 400 °C to about 550 °C, from about 450 °C to about 550 °C, from about 500 °C to about 550 °C, from about 400 °C to about 500 °C, from about 450 °C to about 500 °C, or from about 400 °C to about 450 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 450 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 500 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate stepAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)comprises heating the ferrous oxalate at a temperature from about 550 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 600 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 650 °C to about 700 °C. In some embodiments, the heating the ferrous oxalate step composes heating the ferrous oxalate at a temperature from about 400 °C to about 650 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 450 °C to about 650 °C. In some embodiments, the heating the ferrous oxalate step compri ses heating the ferrous oxalate at a temperature from about 500 °C to about 650 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 550 °C to about 650 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 600 °C to about 650 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 600 °C. In some embodiments, the heating the ferrous oxalate step comprises heating tire ferrous oxalate at a temperature from about 450 °C to about 600 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 500 °C to about 600 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 550 °C to about 600 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 550 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 450 °C to about 550 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 500 °C to about 550 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 500 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 450 °C to about 500 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature from about 400 °C to about 450 °C. In some embodiments, heating the ferrous oxalate further comprises conversion of the ferrous oxalate to an iron oxide. In some embodiments, the iron oxide comprises FeO.

[0090] In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 400 °C, about 425 °C, about 450 °C, about 475 °C,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 500 °C, about 525 °C, about 550 °C, about 575 °C, about 600 °C, about 625 °C, about 650 °C, about 675 °C, or about 700 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 400 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 425 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 450 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 475 °C. In some embodiments, the heating tire ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 500 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 525 °C. In some embodiments, the heating tire ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 550 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 575 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 600 °C. hi some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 625 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 650 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 675 °C. In some embodiments, the heating the ferrous oxalate step comprises heating the ferrous oxalate at a temperature of about 700 °C.

[0091] In some embodiments, heating the ferrous oxalate comprises heating under an ambient environment, an inert environment, or a low pC>2 environment. In some embodiments, the ferrous oxalate is heated under an ambient environment. In some embodiments, the ferrous oxalate is heated under an inert environment. In some embodiments, the ferrous oxalate is heated under a low pCh environment. In some embodiments, the inert environment comprises Ng (g). In some embodiments, the low pCh environment comprises N2 (g), H2 (g), CO (g), CO ■ (g), H2O (g), O2 (g), or a mixture thereof. In some embodiments, the low pO?. environment comprises a mixture ofN2 (g) and H?. (g). In some embodiments, the low p©2 environment comprises CO (g), CO2 (g), H2O (g), O2 (g), or a mixture thereof. In some embodiments, the low pO2 environment comprises CO (g), CO2 (g), H2O (g), or a mixture thereof. In some embodiments, the low pO2 environment comprises CO (g), CO2 (g), or a mixture thereof. In some embodiments, the low pO2 environment comprises N2 (g). hi some embodiments, the low pO2 environment comprises H2 (g). In someAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)embodiments, the low pC>2 environment comprises CO (g). In some embodiments, the low pO ’ environment comprises CO2 (g). In some embodiments, the low pO2 environment comprises H2O (g). In some embodiments, the low pO2 environment comprises O2 (g). In some embodiments, the low pO2 environment comprises CO (g), CO2 (g), H2O (g), O2 (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate). In some embodiments, a portion of the low pO2 environment comprises CO (g), CO2 (g), H O (g), O2 (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate). In some embodiments, the low pO2 environment comprises CO (g), CO2 (g), H2O (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g., upon thermal degradation of ferrous oxalate). In some embodiments, a portion of the low pO2 environment comprises CO (g), CO2 (g), H2O (g), or a mixture thereof generated from heating of the ferrous oxalate (e.g,, upon thermal degradation of ferrous oxalate),

[0092] In some embodiments, the ferrous oxalate is heated in the presence of a carbon source. The carbon source can be any suitable source that produces carbon suitable for aiding in the reduction of ferrous oxalate (e.g., reduction of ferrous oxalate to iron). In some embodiments, the ferrous oxalate is heated in the presence of carbon. In some embodiments, the carbon is derived from a carbon source comprising graphite. In some embodiments, the ferrous oxalate is heated in the presence of powdered carbon. In some embodiments, the ferrous oxalate is heated in the presence of solid carbon.

[0093] In some embodiments, the length of duration of the heating the ferrous oxalate step can be about 0.5 hours, about 1 hour, about 1,5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0094] In some embodiments, heating the ferrous oxalate to produce iron also produces carbon monoxide (CO), carbon dioxide (CO2), moisture, carbon, or a mixture thereof. In some embodiments, heating the ferrous oxalate to produce iron also produces carbon monoxide (CO), carbon dioxide (CO2), moisture, or a mixture thereof. In some embodiments, heating the ferrous oxalate to produce iron also produces carbon monoxide (CO). In some embodiments, heating the ferrous oxalate to produce iron also produces carbon dioxide (CO2). In some embodiments, heating the ferrous oxalate to produce iron also producesAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)moisture. In some embodiments, heating the ferrous oxalate to produce iron also produces carbon.

[0095] In some embodiments, the process 100 and / or embodiments thereof are carried out under ambient light conditions. In some embodiments, the process 100 and / or embodiments thereof do not comprise illumination with a UV-light or an infrared-light source device. In some embodiments, the process 100 and / or embodiments thereof do not comprise illumination with a UV-light source device. In some embodiments, the process 100 and / or embodiments thereof do not comprise illumination with an infrared-light source device.

[0096] In some embodiments, the iron produced according to the process 100 and / or embodiments thereof comprises at least one of: metallic iron, elemental iron, iron powder, iron flakes, iron turnings, and pig iron. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of metallic iron, iron powder, iron flakes, iron turnings, pig iron, or a mixture thereof. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of metallic iron. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of iron powder. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of iron flakes. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of iron turnings. In some embodiments, the iron produced according to the process 100 and / or embodiments thereof is in the form of pig iron.

[0097] In some embodiments of the process 100 and / or embodiments thereof, the first leach residue comprises a metal or metal-containing compound comprising, but not limited to, iron, aluminum, titanium, calcium, zinc, gallium, germanium, rare-earth metals (e.g., scandium, yttrium, lanthanum, europium, dysprosium, neodymium), or a combination thereof. In some embodiments, the metal or metal-containing compound comprises iron oxalates, aluminum oxalates, titanium oxalates, calcium oxalates, zinc oxalates, gallium oxalates, germanium oxalates, rare-earth metal oxalates (e.g., scandium oxalates, yttrium oxalates, lanthanum oxalates, europium oxalates, dysprosium oxalates, neodymium oxalates), or a combination thereof. In some embodiments of the process 100 and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering the metal or metal-containing compound (e.g., rare-earth metal or rare-earth metal-containing compound) of the first leach residue. In some embodiments, the metal or metal-containing compound (e.g., rare-earth metal or rare-earth metal-containing compound) of the first leach residue isAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)extracted and / or recovered according to the process 200 and / or embodiments thereof disclosed herein.

[0098] An aspect of the disclosure also provides for iron extracted, recovered, and / or prepared according to the process 100 and / or embodiments thereof,4.3. Processes for Extraction and / or Recovery of Metals and / or Metal-Containing Compounds (e.g., Rare-Earth Metals and / or Rare-Earth Metal-Containing Compounds)

[0099] As shown in FIG. 2, an aspect of the disclosure provides for a process 200 for extracting and / or recovering a metal or metal-containing compound (e.g., including, but not limited to, a rare-earth metal and / or rare-earth metal -containing compound) from a sample (e.g., a leach residue, or any other suitable sample, including those disclosed herein), the process comprising: contacting the sample with a carbonate-based reagent, a bicarbonate-based reagent, or a combination thereof to produce a mixture comprising a second leachate and a second leach residue; contacting the second leachate with an acid to produce a mixture comprising a first precipitate and a second supernatant; isolating the second supernatant from the first precipitate; and contacting the second supernatant with a hydroxide-based reagent.

[0100] An aspect of the disclosure also provides for an embodiment of the process 200 for extracting and / or recovering a metal or metal -containing compound (e.g., a rare-earth metal and / or rare-earth metal -containing compound) of a first leach residue (e.g., the first leach residue from the process 100 and / or embodiments thereof), the process comprising: contacting the first leach residue with a carbonate -based reagent, a bicarbonate-based reagent, or a combination thereof to produce a mixture comprising a second leachate and a second leach residue; contacting the second leachate with an acid (e.g., a mineral acid) to produce a mixture comprising a first precipitate and a second supernatant; isolating the second supernatant from the first precipitate; and contacting the second supernatant with a hydroxide-based reagent.

[0101] In some embodiments, the first leach residue comprises the first leach residue from the process 100 or an embodiment thereof.

[0102] In some embodiments, the carbonate -based reagent is in the form of a solution. In some embodiments, the carbonate-based reagent is in the form of an aqueous solution. In some embodiments, the bicarbonate-based reagent is in the form of a solution. In some embodiments, the bicarbonate-based reagent is in the form of an aqueous solution, hi some embodiments, the combination of the carbonate-based reagent and the bicarbonate-basedAttomey Ref: 43300-65026 / WO (0001-WO-NPV01)reagent is in the form of a solution. In some embodiments, the combination of the carbonate- based reagent and the bicarbonate -based reagent is in the form of an aqueous solution.

[0103] In some embodiments, the carbonate -based reagent comprises a carbonate-based salt. In some embodiments, the carbonate-based salt comprises an ammonium carbonate, an alkali metal carbonate, an alkaline earth metal carbonate, or a combination thereof. In some embodiments, the carbonate-based salt comprises any other suitable carbonate -based salt. In some embodiments, the carbonate-based salt comprises an alkali metal carbonate. In some embodiments, the alkali metal carbonate comprises lithium carbonate. In some embodiments, the alkali metal carbonate comprises sodium carbonate. In some embodiments, the alkali metal carbonate comprises potassium carbonate. In some embodiments, the alkali metal carbonate comprises cesium carbonate. In some embodiments, the carbonate-based salt comprises an alkaline earth metal carbonate. In some embodiments, the alkaline earth metal carbonate comprises magnesium carbonate. In some embodiments, the alkaline earth metal carbonate comprises calcium carbonate. In some embodiments, the alkaline earth metal carbonate comprises strontium carbonate. In some embodiments, the alkaline earth metal carbonate comprises barium carbonate.

[0104] In some embodiments, the bicarbonate-based reagent comprises a bicarbonate-based salt. In some embodiments, the bicarbonate -based salt comprises an ammonium bicarbonate, an alkali metal bicarbonate, or a combination thereof. In some embodiments, the bicarbonatebased salt comprises any other suitable bicarbonate -based salt. In some embodiments, the bicarbonate-based salt comprises an alkali metal bicarbonate. In some embodiments, the alkali metal bicarbonate comprises lithium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises sodium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises potassium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises cesium bicarbonate.

[0105] In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent comprises sodium carbonate and sodium bicarbonate.

[0106] In some embodiments, the first leach residue is contacted with the carbonate -based reagent. In some embodiments, the first leach residue is contacted with the bicarbonate-based reagent. In some embodiments, the first leach residue is contacted with the combination of the carbonate-based reagent and the bicarbonate -based reagent.

[0107] In some embodiments, the contacting the first leach residue with the carbonate-based reagent, the bicarbonate-based reagent, or a combination thereof step is carried out in one or more stages. In some embodiments, the contacting the first leach residue with the carbonate-Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)based reagent, the bicarbonate-based reagent, or a combination thereof step is carried out in at least two stages. In some embodiments, the contacting the first leach residue with the carbonate-based reagent, the bicarbonate-based reagent, or a combination thereof step is carried out in two stages.

[0108] In some embodiments, the acid comprises an organic acid, inorganic acid, or a combination thereof. In some embodiments, the acid comprises an inorganic acid. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the acid (e.g., mineral acid) is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the acid comprises sulfuric acid. In some embodiments, the acid is in the form of an aqueous solution. Additionally or alternatively, any suitable acid known to those of ordinary’ skill in the art can be used.

[0109] In some embodiments, the first precipitate comprises titanium oxides. In some embodiments, the titanium oxides comprise a titania (TiO₂) precipitate. In some embodiments, the first precipitate comprises titania.

[0110] In some embodiments, the hydroxide-based reagent is in the form of a solution. In some embodiments, the hydroxide-based reagent is in the form of an aqueous solution.

[0111] In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide. In some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0112] In some embodiments, the process 200 and / or embodiments thereof further comprises separating the second leachate from the second leach residue prior to contacting the second leachate with the acid (e.g., mineral acid). In some embodiments, separating the secondAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)leachate from the second leach residue comprises filtration of the mixture comprising the second leachate and the second leach residue,

[0113] In some embodiments, isolating the second supernatant from the first precipitate comprises separating tire second supernatant from the first precipitate by filtration.

[0114] In some embodiments, contacting the second supernatant with the hydroxide-based reagent comprises precipitating the metal or metal -containing compound. In some embodiments, the metal or metal-containing compound comprises a rare-earth metal and / or rare-earth metal-containing compound, hi some embodiments, the precipitated metal or metal-containing compound (e.g., rare-earth metal or rare-earth metal-containing compound) comprises a metal oxide (e.g., a mixed rare-earth metal oxide). The rare-earth metal oxide can include scandium oxides, yttrium oxides, lanthanum oxides, europium oxides, dysprosium oxides, neodymium oxides, and combinations thereof. In some embodiments, the process 200 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated metal or metal -containing compound (e.g., rare-earth metal or rare-earth metal-containing compound). In some embodiments, the precipitated metal or metal -containing compound (e.g., rare-earth metal or rare-earth metal-containing compound) is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery of the precipitated metal or metal-containing compound (e.g., rare-earth metal or rare-earth metal-containing compound) leaves behind a spent solution (e.g., a first spent solution). In some embodiments, the spent solution from the process 200 and / or embodiments thereof (i.e., first spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal- containing compounds, and / or other compounds (e.g., oxalic acid).

[0115] In some embodiments, the process 200 and / or embodiments thereof further comprises an optional roasting / calcination step prior to the contacting the sample (e.g., first leach residue) with the carbonate-based reagent, bicarbonate-based reagent, or combination thereof step. In some embodiments, the roasting / calcination step produces CO (g), CO2 (g), or a mixture thereof.

[0116] As show in FIG. 3, in an embodiment of the process 200, the process comprises: contacting the first leach residue with a carbonate -based reagent comprising sodium carbonate, a bicarbonate-based reagent comprising sodium bicarbonate, or a combination thereof to produce a mixture comprising a second leachate and a second leach residue; contacting the second leachate with an acid (e.g., mineral acid) comprising sulfuric acid toAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)produce a mixture comprising a first precipitate and a second supernatant; isolating the second supernatant from the first precipitate; and contacting the second supernatant with a hydroxide-based reagent comprising sodium hydroxide.

[0117] In some embodiments, the first leach residue comprises the first leach residue from the process 100 or an embodiment thereof.

[0118] In some embodiments, the carbonate -based reagent comprises sodium carbonate. In some embodiments, the carbonate-based reagent is sodium carbonate. In some embodiments, the bicarbonate-based reagent comprises sodium bicarbonate. In some embodiments, the bicarbonate-based reagent is sodium bicarbonate. In some embodiments, the combination of the carbonate-based reagent and the bicarbonate -based reagent comprises sodium carbonate and sodium bicarbonate. In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent consists essentially of sodium carbonate and sodium bicarbonate. In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent consists of sodium carbonate and sodium bicarbonate.

[0119] In some embodiments, the carbonate-based reagent comprising sodium carbonate is in the form of a solution. In some embodimen ts, the carbonate-based reagent comprising sodium carbonate is in the form of an aqueous solution. In some embodiments, the carbonate-based reagent is sodium carbonate. In some embodiments, the sodium carbonate is in the form of a solution. In some embodiments, the sodium carbonate is in the form of an aqueous solution. In some embodiments, the bicarbonate-based reagent comprising sodium bicarbonate is in the form of a solution. In some embodiments, the bicarbonate-based reagent comprising sodium bicarbonate is in the form of an aqueous solution. In some embodiments, the bicarbonatebased reagent is sodium bicarbonate. In some embodiments, the sodium bicarbonate is in the form of a solution. In some embodiments, the sodium bicarbonate is in the form of an aqueous solution.

[0120] In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent comprising sodium carbonate and sodium bicarbonate is in the form of a solution. In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent comprising sodium carbonate and sodium bicarbonate is in the form of an aqueous solution. In some embodimen ts, the combination of the carbonate- based reagent and the bicarbonate -based reagent consists essentially of sodi um carbonate and sodium bicarbonate. In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent consists essentially of a sodium carbonate and sodium bicarbonate solution. In some embodiments, the combination of the carbonate-based reagentAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)and the bicarbonate-based reagent consists essentially of a sodium carbonate and sodium bicarbonate aqueous solution. In some embodiments, the combination of the carbon ate -based reagent and the bicarbonate-based reagent consists of sodium carbonate and sodium bicarbonate. In some embodiments, the combination of the carbonate-based reagent and the bicarbonate-based reagent consists of a sodium carbonate and sodium bicarbonate solution. In some embodiments, the combination of tire carbonate-based reagent and the bicarbonatebased reagent consists of a sodium carbonate and sodium bicarbonate aqueous solution.

[0121] In some embodiments, the first leach residue is contacted with the carbonate -based reagent comprising sodium carbonate. In some embodiments, the first leach residue is contacted with the bicarbonate-based reagent comprising sodium bicarbonate. In some embodiments, the first leach residue is contacted with the combination of the carbonate -based reagent comprising sodium carbonate and the bicarbonate-based reagent comprising sodium bicarbonate. In some embodiments, the first leach residue is contacted with the combination of the carbonate-based reagent and the bicarbonate-based reagent consisting essentially of sodium carbonate and sodium bicarbonate. In some embodiments, the first leach residue is contacted with the combination of the carbonate -based reagent and the bicarbonate-based reagent consisting of sodium carbonate and sodium bicarbonate.

[0122] In some embodiments, the contacting the first leach residue with the carbonate-based reagent comprising sodium carbonate, the bicarbonate-based reagent comprising sodium bicarbonate, or a combination thereof s tep is carried out in one or more stages. In some embodiments, the contacting the first leach residue with the carbonate-based reagent comprising sodium carbonate, the bicarbonate-based reagent comprising sodium bicarbonate, or a combination thereof step is carried out in at least two stages. In some embodiments, the contacting the first leach residue with the carbonate-based reagent comprising sodium carbonate, the bicarbonate -based reagent comprising sodium bicarbonate, or a combination thereof step is carried out in two stages.

[0123] In some embodiments, the acid (e.g., mineral acid) comprising sulfuric acid is in the form of an aqueous solution. In some embodiments, the acid (e.g., mineral acid) is sulfuric acid. In some embodiments, the sulfuric acid is in the form of an aqueous solution.

[0124] In some embodiments, the first precipitate comprises titanium oxides. In some embodiments, the titanium oxides comprise a titania (TiO₂) precipitate. In some embodiments, the first precipitate comprises titania.

[0125] In some embodiments, the hydroxide-based reagent comprising sodium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprisingAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)sodium hydroxide is in tire form of an aqueous solution. In some embodiments, the hydroxide-based reagent is sodium hydroxide. In some embodiments, the sodium hydroxide is in the form of a solution. In some embodiments, the sodium hydroxide is in the form of an aqueous solution.

[0126] In some embodiments, the process 200 and / or embodiments thereof further comprises separating the second leachate from the second leach residue prior to contacting the second leachate with the acid (e.g., mineral acid) comprising sulfuric acid. In some embodiments, separating tire second leachate from the second leach residue comprises filtration of the mixture comprising the second leachate and the second leach residue.

[0127] in some embodiments, isolating the second supernatant from the first precipitate comprises separating tire second supernatant from the first precipitate by filtration.

[0128] In some embodiments, contacting the second supernatant with the hydroxide-based reagent comprising sodium hydroxide comprises precipitating a metal or metal-containing compound. In some embodiments, the metal or metal-containing compound comprises a rare-earth metal and / or rare-earth metal -containing compound. In some embodiments, the precipitated metal or metal -containing compound (e.g., rare-earth metal or rare-earth metalcontaining compound) comprises a rare-earth metal oxide (e.g., a mixed rare-earth metal oxide). Hie rare-earth metal oxide can include scandium oxides, yttrium oxides, lanthanum oxides, europium oxides, dysprosium oxides, neodymium oxides, or a combination thereof. In some embodiments, the process 200 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated metal or metal -containing compound (e.g,, rare-earth metal or rare-earth metal-containing compound). In some embodiments, the precipitated metal or metal -containing compound (e.g., rare-earth metal or rare-earth metalcontaining compound) is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery of the precipitated metal or metal¬ containing compound (e.g., rare-earth metal or rare-earth metal-containing compound) leaves behind a spent solution (e.g., a first spent solution), hi some embodiments, the spent solution from the process 200 and / or embodiments thereof (i.e., first spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal-containing compounds, and / or other compounds (e.g., oxalic acid).

[0129] In some embodiments, the process 200 and / or embodimen ts thereof further comprises an optional roasting / calcination step prior to the contacting the sample (e.g., first leachAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)residue) with the carbonate-based reagent, bicarbonate-based reagent, or combination thereof step. In some embodiments, the roasting / calcination step produces CO (g), CO2 (g), or a mixture thereof.

[0130] An aspect of the disclosure also provides for a metal and / or metal -containing compound extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof. In some embodiments, a rare-earth metal and / or rare-earth metalcontaining compound is extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof. In some embodiments, a rare-earth metal oxide is extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof. In some embodiments, titania is extracted, recovered, and / or prepared according to the process 200 and / or embodiments thereof.

[0131] As shown in FIG, 4, an aspect of the disclosure also provides for a process 300 for extracting and / or recovering a metal or metal-containing compound (e.g., a rare-earth metal and / or rare-earth metal -containing compound) from a sample (e.g., a leach residue, or any other suitable sample, including those disclosed herein), the process comprising: contacting the sample with an acid; leaching the acid-contacted sample with a solution comprising water to produce a mixture comprising a third leachate and a third leach residue, wherein the third leachate comprises a metal sulfate (e.g., a rare-earth metal sulfate); contacting the third leachate with an oxalate-based reagent to produce a metal oxalate (e.g., a rare-earth metal oxalate) from the metal sulfate; and roasting the metal oxalate to produce a metal oxide (e.g., a rare-earth metal oxide).

[0132] An aspect of the disclosure also provides for an embodiment of the process 300 for extracting and / or recovering a metal or metal -containing compound (e.g., a rare-earth metal and / or rare-earth metal -containing compound) of a first leach residue (e.g., the first leach residue from the process 100 and / or embodiments thereof), tire process comprising: contacting the first leach residue with an acid (e.g., mineral acid); leaching the acid-contacted first leach residue with a solution comprising water to produce a mixture comprising a third leachate and a third leach residue, wherein the third leachate comprises a metal sulfate (e.g., a rare-earth metal sulfate); contacting the third leachate with an oxalate-based reagent to produce a metal oxalate (e.g., a rare-earth metal oxalate) from the metal sulfate; and roasting the metal oxalate to produce a metal oxide (e.g., a rare-earth metal oxide).

[0133] In some embodiments, the first leach residue comprises the first leach residue from the process 100 or an embodiment thereof.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0134] In some embodiments, the acid comprises an organic acid, inorganic acid, or a combination thereof. In some embodiments, the acid comprises an inorganic acid. Tn some embodiments, the inorganic acid is a mineral acid. In some embodiments, the acid (e.g., mineral acid) is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the acid comprises sulfuric acid. In some embodiments, the acid is in the form of an aqueous solution. Additionally or alternatively, any suitable acid known to those of ordinary skill in the art can be used.

[0135] In some embodiments, the solution comprising water is water.

[0136] in some embodiments, the oxalate-based reagent comprises oxalic acid, an oxalate salt, or a combination thereof. In some embodiments, the oxalate-based reagent is in the form of a solution. In some embodiments, the oxalate-based reagent is in the form of an aqueous solution. In some embodiments, the oxalate-based reagent comprises oxalic acid. In some embodiments, the oxalate-based reagent is oxalic acid. In some embodiments, the oxalic acid is in the form of a solution. In some embodiments, the oxalic acid is in the form of an aqueous solution.

[0137] in some embodiments, the contacting the first leach residue with the acid step further comprises heating the acid-contacted first leach residue, hi some embodiments, heating the acid -contacted first leach residue comprises a sulfating roast.

[0138] In some embodiments, the length of duration of the contacting the first leach residue with the acid step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3,5 hours, about 4 hours, about 4,5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration. In some embodiments, the length of duration of the leaching the acid-contacted first leach residue step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0139] In some embodiments, the process 300 and / or embodiments thereof further comprises separating the third leachate from the third leach residue prior to contacting the third leachate with the oxalate-based reagent. In some embodiments, separating the third leachate from theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)third leach residue comprises filtration of the mixture comprising the third leachate and the third leach residue. In some embodiments, the metal sulfate comprises a rare-earth metal sulfate. In some embodiments, the rare-earth metal sulfate of the third leachate includes scandium sulfates, yttrium sulfates, lanthanum sulfates, europium sulfates, dysprosium sulfates, neodymium sulfates, or a combination thereof.

[0140] In some embodiments, contacting the third leachate with the oxalate-based reagent comprises precipitating the metal oxalate, in some embodiments, the metal oxalate comprises a rare-earth metal oxalate. In some embodiments, the rare-earth metal oxalate includes scandium oxalates, yttrium oxalates, lanthanum oxalates, europium oxalates, dysprosium oxalates, neodymium oxalates, or a combination thereof. In some embodiments, the process 300 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated metal oxalate (e.g,, the rare-earth metal oxalate). In some embodiments, the precipitated metal oxalate (e.g., the rare-earth metal oxalate) is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery of the precipitated metal oxalate (e.g., the rare-earth metal oxalate) leaves behind a spent solution (e.g., a second spent solution). In some embodiments, the spent solution from the process 300 and / or embodiments thereof (i.e., second spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal -containing compounds, and / or other compounds (e.g., oxalic acid).

[0141] In some embodiments, the rare-earth metal oxides (e.g., mixed rare-earth metal oxides) produced by roasting the rare-earth metal oxalates include scandium oxides, ytrium oxides, lanthanum oxides, europium oxides, dysprosium oxides, neodymium oxides, or a combination thereof.

[0142] In some embodiments, the third leach residue comprises an iron oxide, aluminum oxide, titanium oxide, or a combination thereof. In some embodiments of the process 300 and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering a metal or metal-containing compound comprising iron, aluminum, titanium, or a combination thereof from the iron oxide, aluminum oxide, titanium oxide, or a combination thereof of the third leach residue. In some embodiments, the metal or metal-containing compound comprising iron, aluminum, titanium, or a combination thereof is extracted and / or recovered from the third leach residue according to the process 600 and / or embodiments thereof disclosed herein.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0143] In some embodiments, the process 300 and / or embodiments thereof further comprises an optional roasting / calcination step prior to the contacting the sample (e.g,, first leach residue) with the acid step. In some embodiments, the roasting / calcination step produces CO (g), CO₂ (g), or a mixture thereof.

[0144] As shown FIG. 5, in an embodiment of the process 300, the process comprises: contacting the first leach residue with an acid (e.g., mineral acid) comprising sulfuric acid; leaching the sulfuric acid-contacted first leach residue with water to produce a mixture comprising a third leachate and a third leach residue, wherein tire third leachate comprises a metal sulfate comprising a rare-earth metal sulfate; contacting the third leachate with an oxalate-based reagent comprising oxalic acid to produce a metal oxalate comprising a rare- earth metal oxalate from the metal sulfate comprising a rare-earth metal sulfate; and roasting the metal oxalate comprising a rare-earth metal oxalate to produce a metal oxide comprising a rare-earth metal oxide.

[0145] In some embodiments, the first leach residue comprises the first leach residue from the process 100 or an embodiment thereof.

[0146] In some embodiments, the acid (e.g., mineral acid) comprising sulfuric acid is in the form of an aqueous solution. In some embodiments, the acid (e.g., mineral acid) is sulfuric acid. In some embodiments, the sulfuric acid is in the form of an aqueous solution.

[0147] In some embodiments, the oxalate-based reagent comprising oxalic acid is in the form of a solution. In some embodiments, tire oxalate-based reagent comprising oxalic acid is in the form of an aqueous solution. In some embodiments, the oxalate-based reagent is oxalic acid. In some embodiments, the oxalic acid is in the form of a solution. In some embodiments, the oxalic acid is in the form of an aqueous solution.

[0148] in some embodiments, the contacting the first leach residue with the acid (e.g., mineral acid) comprising sulfuric acid step further comprises heating the sulfuric acid- contacted first leach residue. In some embodiments, heating the sulfuric acid-contacted first leach residue comprises a sulfating roast.

[0149] In some embodiments, the length of duration of the contacting tire first leach residue with the acid comprising sulfuric acid step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration. In some embodiments, the length of duration of the leaching the sulfuric acid-contacted firstAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)leach residue step can be about 0.5 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 6.5 hours, about 7 hours, about 7.5 hours, about 8 hours, about 8.5 hours, about 9 hours, about 9.5 hours, about 10 hours, longer than 10 hours, any intermediate duration, or any other suitable duration.

[0150] In some embodiments, the process 300 and / or embodiments thereof further comprises separating the third leachate from the third leach residue prior to contacting the third leachate with the oxalate-based reagent comprising oxalic acid, hi some embodiments, separating the third leachate from the third leach residue comprises filtration of the mixture comprising the third leachate and the third leach residue. In some embodiments, the metal sulfate comprising the rare-earth metal sulfate of the third leachate includes scandium sulfates, yttrium sulfates, lanthanum sulfates, europium sulfates, dysprosium sulfates, neodymium sulfates, ora combination thereof.

[0151] In some embodiments, contacting the third leachate with the oxalate-based reagent comprising oxalic acid comprises precipitating the metal oxalate comprising the rare-earth metal oxalate. In some embodiments, the rare-earth metal oxalate includes scandium oxalates, yttrium oxalates, lanthanum oxalates, europium oxalates, dysprosium oxalates, neodymium oxalates, or a combination thereof. In some embodiments, the process 300 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated metal oxalate comprising the rare-earth metal oxalate. In some embodiments, the precipitated metal oxalate comprising the rare-earth metal oxalate is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery’ of the precipitated metal oxalate comprising the rare-earth metal oxalate leaves behind a spent solution (e.g., a second spent solution). In some embodiments, the spent solution from the process 300 and / or embodiments thereof (i.e., second spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal-containing compounds, and / or other compounds (e.g., oxalic acid).

[0152] In some embodiments, the metal oxide comprising the rare-earth metal oxide(e.g., mixed rare-earth metal oxides) produced by roasting the metal oxalate comprising the rare- earth metal oxalate includes scandium oxides, yttrium oxides, lanthanum oxides, europium oxides, dysprosium oxides, neodymium oxides, or a combination thereof.

[0153] In some embodiments, the third leach residue comprises an iron oxide, aluminum oxide, titanium oxide, or a combination thereof. In some embodiments of the process 300Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering a metal or metal -containing compound comprising iron, aluminum, titanium, or a combination thereof from the iron oxide, aluminum oxide, titanium oxide, or a combination thereof of the third leach residue. In some embodiments, the metal or metal-containing compound comprising iron, aluminum, titanium, or a combination thereof is extracted and / or recovered from the third leach residue according to the process 600 and / or embodiments thereof disclosed herein.

[0154] In some embodiments, the process 300 and / or embodiments thereof further comprises an optional roasting / calcination step prior to the contacting the sample (e.g., first leach residue) with tire acid step. In some embodiments, the roasting / calcination step produces CO (g), CO₂ (g), or a mixture thereof.

[0155] An aspect of the disclosure also provides for a metal and / or metal -containing compound extracted, recovered, and / or prepared according to the process 300 and / or embodiments. In some embodiments, a rare-earth metal and / or rare-earth metal-containing compound is extracted, recovered, and / or prepared according to the process 300 and / or embodiments. In some embodiments, a rare-earth metal sulfate is extracted, recovered, and / or prepared according to the process 300 and / or embodiments. In some embodiments, a rare-earth metal oxalate is extracted, recovered, and / or prepared according to the process 300 and / or embodiments. In some embodiments, a rare-earth metal oxide is extracted, recovered, and / or prepared according to the process 300 and / or embodiments.4.4. Processes for Extraction and / or Recovery of Metals and / or Metal-Containing Compounds (e.g., Aluminum, Titanium, Zinc, Gallium, and / or Germanium Metals and / or Metal-Containing Compounds)

[0156] As shown in FIG. 6, an aspect of the disclosure provides for a process 400 for extracting and / or recovering a metal or metal -containing compound comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof from a sample (e.g., a supernatant, or any other suitable sample, including those disclosed herein), the process comprising: contacting the sample with an acid; heating the acid-contacted sample to produce a mixture comprising a second precipitate and a third supernatant; isolating the third supernatant from the second precipitate; and contacting the third supernatant with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0157] An aspect of the disclosure also provides for an embodiment of the process 400 for extracting and / or recovering a metal or metal -containing compound comprising aluminum, titanium, zinc, gallium, germanium, or the combination thereof from a first supernatant (e.g., the first supernatant from the process 100 and / or embodiments thereof), the process comprising: contacting the first supernatant with an acid (e.g., mineral acid); heating the acid-contacted first supernatant to produce a mixture comprising a second precipitate and a third supernatant; isolating the third supernatant from the second precipitate; and contacting the third supernatant with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof.

[0158] in some embodiments, the first supernatant comprises the first supernatant from the process 100 or an embodiment thereof.

[0159] In some embodiments, the acid comprises an organic acid, inorganic acid, or a combination thereof. In some embodiments, the acid comprises an inorganic acid. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the acid (e.g., mineral acid) is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the acid comprises sulfuric acid. In some embodiments, the acid is in the form of an aqueous solution. Additionally or alternatively, any suitable acid known to those of ordinary’ skill in the art can be used.

[0160] In some embodiments, the second precipitate comprises titanium oxides. In some embodiments, the titanium oxides comprise a titania (TiO₂) precipitate. In some embodiments, the second precipitate comprises titania.

[0161] In some embodiments, the third supernatant comprises an aluminum salt. In some embodiments, the third supernatant comprises an aluminum sulfate, an aluminum oxalate, or a combination thereof. In some embodiments, the third supernatant comprises an aluminum sulfate. In some embodiments, the third supernatant comprises an aluminum oxalate. In some embodiments, the third supernatant comprises a combination of an aluminum sulfate and an aluminum oxalate.

[0162] In some embodiments, the hydroxide-based reagent is in the form of a solution. In some embodiments, the hydroxide-based reagent is in the form of an aqueous solution. In some embodiments, the metal oxide-based reagent is in the form of a solution. In some embodiments, the metal oxide-based reagent is in tire form of an aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-basedAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)reagent is in the form of a solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent is in the form of an aqueous solution.

[0163] In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide, hi some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide, hi some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0164] In some embodiments, the metal oxide-based reagent comprises a metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide, an alkaline earth metal oxide, or a combination thereof. In some embodiments, the metal oxide salt comprises any other suitable metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide. In some embodiments, the alkali metal oxide comprises lithium oxide. In some embodiments, the alkali metal oxide comprises sodium oxide. In some embodiments, the alkali metal oxide comprises potassium oxide. In some embodiments, the alkali metal oxide comprises cesium oxide. In some embodiments, the metal oxide salt comprises an alkaline earth metal oxide. In some embodiments, the alkaline earth metal oxide comprises magnesium oxide. In some embodiments, the alkaline earth metal oxide comprises calcium oxide, hi some embodiments, the alkaline earth metal oxide comprises strontium oxide. In some embodiments, the alkaline earth metal oxide comprises barium oxide.

[0165] In some embodiments, the third supernatant is contacted with the hydroxide-based reagent. In some embodiments, the third supernatant is contacted with the metal oxide-based reagent. In some embodiments, the third supernatant is contacted with the combination of the hydroxide-based reagent and die metal oxide-based reagent.

[0166] In some embodiments, a pH during the heating die acid-contacted first supernatant step is maintained in a range between from about 0 to about 4. In some embodiments, die pHAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)during the heating the acid-contacted first supernatant step is maintained in the range betw een from about 0 to about 4, from about 0.5 to about 4, from about 1 to about 4, from about 1.5 to about 4, from about 2 to about 4, from about 2.5 to about 4, from about 3 to about 4, from about 3.5 to about 4, from about 0 to about 3.5, from about 0.5 to about 3.5, from about 1 to about 3.5, from about 1.5 to about 3.5, from about 2 to about 3.5, from about 2.5 to about 3.5, from about 3 to about 3.5, from about 0 to about 3, from about 0.5 to about 3, from about 1 to about 3, from about 1.5 to about 3, from about 2 to about 3, from about 2.5 to about 3, from about 0 to about 2.5, from about 0.5 to about 2.5, from about 1 to about 2.5, from about 1.5 to about 2.5, from about 2 to about 2.5, from about 0 to about 2, from about 0.5 to about 2, from about 1 to about 2, from about 1.5 to about 2, from about 0 to about 1.5, from about 0.5 to about 1.5, from about 1 to about 1.5, from about 0 to about 1, from about 0.5 to about 1, from about 0 to about 0.5, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, the pH during the heating the acid- contacted first supernatant step is maintained in the range between from about 0 to about 2. hi some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range between from about 0.5 to about 2. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range between from about 1 to about 2. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range between from about 1.5 to about 2. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range between from about 0 to about 1.5. In some embodiments, the pH during the heating the acid -contacted first supernatant step is maintained in the range between from about 0.5 to about 1.5. In some embodiments, the pH during the heating the acid- contacted first supernatant step is maintained in the range between from about 1 to about 1.5. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range between from about 0 to about 1, In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range betw een from about 0.5 to about 1. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained in the range between from about 0 to about 0,5

[0167] In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 0, at about 0.1, at about 0.2, at about 0.3, at about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, about 3, about 3.1, about 3.2,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, about 3.9, about 4, lower than 0, greater than 4, or any other suitable pH, In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 0. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 0.5. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 1. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 1.5. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 2. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 2.5. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 3. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 3.5. In some embodiments, the pH during the heating the acid-contacted first supernatant step is maintained at about 4.

[0168] In some embodiments, heating during tire acid -contacted first supernatant step maintains the temperature between from about 70 °C to about 110 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 70 °C to about 110 °C, from about 75 °C to about 110 °C, from about 80 °C to about 110 °C, from about 85 °C to about 110 °C, from about 90 °C to about 110 °C, from about 95 °C to about 110 °C, from about 100 °C to about 110 °C, from about 105 °C to about 110 °C, from about 70 °C to about 105 °C, from about 75 °C to about 105 °C, from about 80 °C to about 105 °C, from about 85 °C to about 105 °C, from about 90 °C to about 105 °C, from about 95 °C to about 105 °C, from about 100 °C to about 105 °C, from about 70 °C to about 100 °C, from about 75 °C to about 100 °C, from about 80 °C to about 100 °C, from about 85 °C to about 100 °C, from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, from about 70 °C to about 95 °C, from about 75 °C to about 95 °C, from about 80 °C to about 95 °C, from about 85 °C to about 95 °C, from about 90 °C to about 95 °C, from about 70 °C to about 90 °C, from about 75 °C to about 90 °C, from about 80 °C to about 90 °C, from about 85 °C to about 90 °C, from about 70 °C to about 85 °C, from about 75 °C to about 85 °C, from about 80 °C to about 85 °C, from about 70 °C to about 80 °C, from about 75 °C to about 80 °C, from about 70 °C to about 75 °C, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 80 °C to about 100 °C. In some embodiments, heating during the acid-contactedAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)first supernatant step maintains the temperature between from about 85 °C to about 100 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 90 °C to about 100 °C. In some embodiments, heating during tire acid-contacted first supernatant step maintains the temperature between from about 95 °C to about 100 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 80 °C to about 95 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 85 °C to about 95 °C. In some embodiments, heating during the acid -contacted first supernatant step maintains the temperature between from about 90 °C to about 95 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 80 °C to about 90 °C. In some embodiments, heating during the acid -contacted first supernatant step maintains the temperature between from about 85 °C to about 90 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature between from about 80 °C to about 85 °C.

[0169] In some embodiments, heating during tire acid -contacted first supernatant step maintains the temperature at about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, about 100 °C, about 101 °C, about 102 °C, about 103 °C, about 104 °C, about 105 °C, about 106 °C, about 107 °C, about 108 °C, about 109 °C, about 110 °C, below 70 °C, above 110 °C, or at any other suitable temperature. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature at about 80 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature at about 85 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature at about 90 °C, In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature at about 95 °C. In some embodiments, heating during the acid-contacted first supernatant step maintains the temperature at about 100 °C.

[0170] In some embodiments, isolating the third supernatant from the second precipitate comprises separating the third supernatant from the second precipitate by filtration.

[0171] In some embodiments, the process 400 and / or embodiments thereof further comprises solvent extraction of the third supernatant to produce a first solvent extract. In some embodiments, the solvent extraction of the third supernatant comprises extraction withAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)trioctyl amine (N235), tributyl phosphate (TBP), or a combination thereof. Additionally or alternatively, any other suitable solvent extraction reagents known to those of ordinary skill in the art can be used. In some embodiments, the first solvent extract comprises a metal or metal-containing compound comprising, but not limited to, gallium, germanium, or a combination thereof. In some embodiments of the process 400 and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering the metal or metal-containing compound comprising gallium, germanium, or a combination thereof from the first solvent extract. In some embodiments, the metal or metal-containing compound comprising gallium, germanium, or a combination thereof of the first solvent extract is extracted and / or recovered according to the process 700 and / or embodiments thereof disclosed herein.

[0172] In some embodiments, a pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in a range between from about 4 to about 7. In some embodiments, the pH during the contacting the third supernatant with the hydroxide -based reagent, the metal oxide -based reagent, or a combination thereof step is maintained in the range between from about 4 to about 7, from about 4.5 to about 7, from about 5 to about 7, from about 5.5 to about 7, from about 6 to about 7, from about 6.5 to about 7, from about 4 to about 6.5, from about 4.5 to about 6.5, from about 5 to about 6.5, from about 5.5 to about 6.5, from about 6 to about 6.5, from about 4 to about 6, from about 4.5 to about 6, from about 5 to about 6, from about 5.5 to about 6, from about 4 to about 5.5, from about 4.5 to about 5.5, from about 5 to about 5.5, from about 4 to about 5, from about 4.5 to about 5, from about 4 to about 4.5, any other intermediate range, any other suitable range, any other lower range, or any other greater range. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4 to about 7, In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide¬ based reagent, or a combination thereof step is maintained in the range between from about 4.5 to about 7. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 5 to about 7. In some embodiments, the pH during tire contacting the third supernatant with the hydroxide-based reagent, tire metal oxide¬ based reagent, or a combination thereof step is maintained in the range between from about 5.5 to about 7. In some embodiments, tire pH during the contacting the third supernatant withAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 6 to about 7. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide¬ based reagent, or a combination thereof step is maintained in the range betw een from about 6.5 to about 7. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4 to about 6.5. In some embodiments, the pH during the contacting tire third supernatant with the hydroxide-based reagent, the metal oxide¬ based reagent, or a combination thereof step is maintained in the range between from about 4.5 to about 6.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 5 to about 6.5, In some embodiments, the pH during tire contacting the third supernatant w ith the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range betw een from about 5.5 to about 6.5. In some embodiments, the pH during tire contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range betw een from about 6 to about 6.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4 to about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4.5 to about 6. In some embodiments, the pH during the contacting the third supernatant w ith the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 5 to about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 5.5 to about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxi de -based reagent, or a combination thereof step is maintained in the range between from about 4 to about 5.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxidebased reagent, or a combination thereof step is maintained in the range betw een from about 4.5 to about 5.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereofAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)step is maintained in the range between from about 5 to about 5.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4 to about 5. In some embodiments, tire pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4.5 to about 5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained in the range between from about 4 to about 4.5.

[0173] in some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 4, about 4.1, about 4,2, about 4.3, about 4.4, about 4.5, about 4,6, about 4.7, about 4.8, about 4.9, about 5, about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6, about 6.1, about 6.2, about 6.3, about 6.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, about 7, lower than 4, greater than 7, or any other suitable pH. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 4. In some embodiments, tire pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 4.5. In some embodimen ts, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide¬ based reagent, or a combination thereof step is maintained at about 5.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 6.5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step is maintained at about 7.

[0174] In some embodiments, contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof comprises precipitating an aluminum hydroxide. In some embodiments, tlie aluminum hydroxide comprises aluminumAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)hydroxide (Al(OH)₃). In some embodiments, contacting the third supernatant with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof comprises precipitating aluminum hydroxide (Al(OH)₃). In some embodiments, the aluminum hydroxide can be used in a Bayer process. In some embodiments, the process 400 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated aluminum hydroxide (e.g., aluminum hydroxide). In some embodiments, the precipitated aluminum hydroxide is separated, isolated, and / or recovered by filtration, in some embodiments, separation, isolation, and / or recovery of the precipitated aluminum hydroxide leaves behind a spent solution (e.g., a third spent solution). In some embodiments, the spent solution from the process 400 and / or embodiments thereof (i.e., third spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal-containing compounds, and / or other compounds (e.g., oxalic acid).

[0175] In some embodiments, the process 400 and / or embodiments thereof further comprises extracting and / or recovering a metal or metal -containing compound (e.g., zinc metal or a zinc-containing compound) from the third spent solution. In some embodiments, the metal or metal-containing compound (e.g., zinc metal or zinc-containing compound) of the third spent solution is extracted and / or recovered according to a process comprising: contacting the third spent solution with a hydroxide-based reagent, a metal oxide-based reagent, a carbonate- based reagent, a bicarbonate-based reagent, or a combination thereof.

[0176] In some embodiments, the hydroxide-based reagent is in the form of a solution. In some embodiments, the hydroxide-based reagent is in the form of an aqueous solution. In some embodiments, the metal oxide-based reagent is in the form of a solution. In some embodiments, the metal oxide-based reagent is in the form of an aqueous solution.

[0177] In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide. In some embodiments, the hydroxide salt comprises an alkalineAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0178] In some embodiments, the metal oxide-based reagent comprises a metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide, an alkaline earth metal oxide, or a combination thereof. In some embodiments, the metal oxide salt comprises any other suitable metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide. In some embodiments, the alkali metal oxide comprises lithium oxide. In some embodiments, the alkali metal oxide comprises sodium oxide. In some embodiments, the alkali metal oxide comprises potassium oxide. In some embodiments, the alkali metal oxide comprises cesium oxide. In some embodiments, the metal oxide salt comprises an alkaline earth metal oxide. In some embodiments, the alkaline earth metal oxide comprises magnesium oxide. In some embodiments, the alkaline earth metal oxide comprises calcium oxide. In some embodiments, the alkaline earth metal oxide comprises strontium oxide. In some embodiments, the alkaline earth metal oxide comprises barium oxide.

[0179] In some embodiments, the carbonate -based reagent is in the form of a solution. In some embodiments, the carbonate-based reagent is in the form of an aqueou s solution. In some embodiments, the bicarbonate-based reagent is in the form of a solution. In some embodiments, the bicarbonate-based reagent is in the form of an aqueous solution.

[0180] In some embodiments, the carbonate -based reagent comprises a carbonate-based salt. In some embodiments, the carbonate-based salt comprises an ammonium carbonate, an alkali metal carbonate, an alkaline earth metal carbonate, or a combination thereof. In some embodiments, the carbonate-based salt comprises any other suitable carbonate-based salt. In some embodiments, the carbonate-based salt comprises an alkali metal carbonate. In some embodiments, the alkali metal carbonate comprises lithium carbonate. In some embodiments, the alkali metal carbonate comprises sodium carbonate. In some embodiments, the alkali metal carbonate comprises potassium carbonate. In some embodiments, the alkali metal carbonate comprises cesium carbonate. In some embodiments, the carbonate-based salt comprises an alkaline earth metal carbonate, hi some embodiments, the alkaline earth metal carbonate comprises magnesium carbonate. In some embodiments, the alkaline earth metal carbonate comprises calcium carbonate. In some embodiments, the alkaline earth metalAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)carbonate comprises strontium carbonate. In some embodiments, the alkaline earth metal carbonate comprises barium carbonate.

[0181] In some embodiments, the bicarbonate-based reagent comprises a bicarbonate-based salt. In some embodiments, the bicarbonate -based salt comprises an ammonium bicarbonate, an alkali metal bicarbonate, or a combination thereof. In some embodiments, the bicarbonatebased salt comprises any other suitable bicarbonate -based salt. In some embodiments, the bicarbonate-based salt comprises an alkali metal bicarbonate. In some embodiments, the alkali metal bicarbonate comprises lithium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises sodium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises potassium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises cesium bicarbonate.

[0182] In some embodiments, the metal or metal -containing compound (e.g., zinc metal or zinc-containing compound) is extracted and / or recovered as a metal hydroxide (e.g., a zinc hydroxide), a metal oxide (e.g., a zinc oxide), a metal carbonate (e.g., a zinc carbonate), a metal bicarbonate (e.g., a zinc bicarbonate), or a combination thereof.

[0183] In some embodiments, the process for extracting and / or recovering the metal or metal-containing compound (e.g., the zinc metal or a zinc-containing compound) can be used for extracting and / or recovering the metal or metal-containing compound (e.g., the zinc metal or a zinc-containing compound) from any other sample (e.g., any leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, 700, and / or embodiments thereof).

[0184] As shown in FIG. 7, in an embodiment of the process 400, the process comprises: contacting the first supernatant with an acid (e.g., mineral acid) comprising sulfuric acid; heating the sulfuric acid-contacted first supernatant to produce a mixture comprising a second precipitate and a third supernatant; isolating the third supernatant from the second precipitate; and contacting the third supernatant with a hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, a metal oxide-based reagent comprising calcium oxide, or a combination thereof.

[0185] In some embodiments, the supernatant comprises the first supernatant from the process 100 or an embodiment thereof.

[0186] In some embodiments, the acid (e.g., mineral acid) comprising sulfuric acid is in the form of an aqueous solution. In some embodiments, the acid is sulfuric acid. In some embodiments, the sulfuric acid is in the form of an aqueous solution.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0187] In some embodiments, the second precipitate comprises titanium oxides. In some embodiments, the titanium oxides compose a titania (TiO₂) precipitate. In some embodiments, the second precipitate comprises titania.

[0188] In some embodiments, the third supernatant comprises an aluminum salt. In some embodiments, the third supernatant comprises an aluminum sulfate, an aluminum oxalate, or a combination thereof. In some embodiments, the third supernatant comprises an aluminum sulfate. In some embodiments, the third supernatant comprises an aluminum oxalate. In some embodiments, the third supernatant comprises a combination of an aluminum sulfate and an aluminum oxalate.

[0189] in some embodiments, the hydroxide-based reagent comprises sodium hydroxide. In some embodiments, the hydroxide-based reagent is sodium hydroxide. In some embodiments, the hydroxide-based reagent comprises calcium hydroxide. In some embodiments, the hydroxide-based reagent is calcium hydroxide. In some embodiments, tire hydroxide-based reagent comprises a combination of sodium hydroxide and calcium hydroxide. In some embodiments, the hydroxide-based reagent consists essentially of a combination of sodium hydroxide and calcium hydroxide. In some embodiments, the hydroxide-based reagent consists of a combination of sodium hydroxide and calcium hydroxide.

[0190] In some embodiments, the hydroxide-based reagent comprising sodium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprising sodium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide-based reagent is sodium hydroxide. In some embodiments, the sodium hydroxide is in the form of a solution. In some embodiments, the sodium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide-based reagent comprising calcium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprising calcium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide-based reagent is calcium hydroxide. In some embodiments, the calcium hydroxide is in the form of a solution. In some embodiments, the calcium hydroxide is in tlie form of an aqueous solution.

[0191] In some embodiments, the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide -based reagent comprising the combination of sodium hydroxide and calcium hydroxide consists essentially of sodium hydroxide and calcium hydroxide. In some embodiments, theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide consists essentially of a sodium hydroxide and calcium hydroxide solution. In some embodiments, the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide consists essentially of a sodium hydroxide and calcium hydroxide aqueous solution. In some embodiments, the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide consists of sodium hydroxide and calcium hydroxide. In some embodiments, the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide consists of a sodium hydroxide and calcium hydroxide solution. In some embodiments, the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide consists of a sodium hydroxide and calcium hydroxide aqueous solution.

[0192] In some embodiments, the metal oxide-based reagent comprising calcium oxide is in the form of a solution. In some embodiments, the metal oxide-based reagent comprising calcium oxide is in the form of an aqueous solution.

[0193] In some embodiments, the third supernatant is contacted with the hydroxide-based reagent comprising sodium hydroxide. In some embodiments, the third supernatant is contacted with the hydroxide-based reagent comprising calcium hydroxide. In some embodiments, the third supernatant is contacted with the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide. In some embodiments, the third supernatant is contacted with the hydroxide-based reagent consisting essentially of a combination of sodium hydroxide and calcium hydroxide. In some embodiments, the third supernatant is contacted with the hydroxide-based reagent consisting of a combination of sodium hydroxide and calcium hydroxide. In some embodiments, the third supernatant is contacted with the metal oxide-based reagent comprising calcium oxide. In some embodiments, the third supernatant is contacted with the combination of the metal oxide¬ based reagent comprising calcium oxide and the hydroxide-based reagent. In some embodiments, the third supernatant is contacted with the combination of the metal oxide¬ based reagent comprising calcium oxide and tire hydroxide-based reagent comprising sodium hydroxide. In some embodiments, the third supernatant is contacted with the combination of the metal oxide-based reagent comprising calcium oxide and the hydroxide-based reagent comprising calcium hydroxide. In some embodiments, the third supernatant is contacted with the combination of the metal oxide-based reagent comprising calcium oxide and the hydroxide-based reagent comprising the combination of sodium hydroxide and calcium hydroxide. In some embodiments, the third supernatant is contacted with the combination ofAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)the metal oxide-based reagent consisting essentially of calcium oxide and the hydroxide- based reagent consisting essentially of a combination of sodium hydroxide and calcium hydroxide. In some embodiments, the third supernatant is contacted with the combination of the metal oxide-based reagent consisting of calcium oxide and the hydroxide-based reagent consisting of a combination of sodium hydroxide and calcium hydroxide.

[0194] In some embodiments, a pH during the heating tire sulfuric acid-contacted first supernatant step is maintained in a range betw een from about 1 to about 2. In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained in the range between from about 1,5 to about 2. In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained in the range between from about 1 to about 1.5.

[0195] In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained at about I, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, or about 2. In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained at about 1. In some embodiments, the pH during the heating the sulfuric acid-con tacted first supernatant step is maintained at about 1.2. In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained at about 1.4. hi some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained at about 1.6. In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained at about 1.8. In some embodiments, the pH during the heating the sulfuric acid-contacted first supernatant step is maintained at about 2.

[0196] In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains the temperature between from about 85 °C to about 95 °C. In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains the temperature between from about 85 °C to about 95 °C, from about 90 °C to about 95 °C, or from about 85 °C to about 90 °C. In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains the temperature between from about 85 °C to about 90 °C. In some embodiments, heating the sulfuric acid -contacted first supernatant step maintains the temperature between from about 90 °C to about 95 °C.

[0197] In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains the temperature at about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, or about 95 °C. In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)temperature at about 85 °C. In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains the temperature at about 90 °C. In some embodiments, heating the sulfuric acid-contacted first supernatant step maintains tire temperature at about 95 °C.

[0198] In some embodiments, isolating the third supernatant from tire second precipitate comprises separating the third supernatant from the second precipitate by filtration.

[0199] In some embodiments, the process 400 and / or embodimen ts thereof further comprises solvent extraction of the third supernatant to produce a first solvent extract. In some embodiments, the solvent extraction of the third supernatant comprises extraction with trioctyl amine (N235), tributyl phosphate (TBP), or a combination thereof. Additionally or alternatively, any other suitable solvent extraction reagents known to those of ordinary skill in the art can be used. In some embodiments, the first solvent extract comprises a metal or metal-containing compound comprising, but not limited to, gallium, germanium, or a combination thereof. In some embodiments of the process 400 and / or embodiments thereof, the process and / or embodiments thereof further comprises extracting and / or recovering the metal or metal-containing compound comprising gallium, germanium, or a combination thereof from the first solvent extract. In some embodiments, the metal or metal -containing compound comprising gallium, germanium, or a combination thereof of the first solvent extract is extracted and / or recovered according to the process 700 and / or embodiments thereof disclosed herein,

[0200] In some embodiments, a pH during the contacting tire third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained in a range between from about 5 to about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, tire metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained in the range between from about 5.5 to about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained in the range between from about 5 to about 5.5.

[0201] In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 5, about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 5.7, about 5.8, about 5.9, or about 6. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 5. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 5.2. In some embodiments, the pH during the contacting the third supernatant with tire hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 5.4. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 5.6. In some embodiments, the pH during the contacting tire third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 5.8. In some embodiments, the pH during the contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof step is maintained at about 6.

[0202] In some embodiments, contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof comprises precipitating an aluminum hydroxide. In some embodiments, the aluminum hydroxide comprises aluminum hydroxide (Al(0H)3), In some embodiments, contacting the third supernatant with the hydroxide-based reagent comprising sodium hydroxide, calcium hydroxide or a combination thereof, the metal oxide-based reagent comprising calcium oxide, or a combination thereof comprises precipitating aluminum hydroxide (Al(OH)₃). In some embodiments, the aluminum hydroxide can be used for a Bayer process. In some embodiments, the process 400 and / or embodiments thereof further comprises separ ating, isolating, and / or recovering the precipitated aluminum hydroxide (e.g., aluminum hydroxide). In some embodiments, the precipitated aluminum hydroxide is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery of theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)precipitated aluminum hydroxide leaves behind a spent solution (e.g., a third spent solution). In some embodiments, the spent solution from the process 400 and / or embodiments thereof (i.e., third spent solution) can be used as the input sample, source, and / or waste / process stream in any of tire processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery’ of different metals, metal -containing compounds, and / or other compounds (e.g., oxalic acid).

[0203] In some embodiments, the process 400 and / or embodiments thereof further comprises extracting and / or recovering zinc metal or a zinc-containing compound from the third spent solution. In some embodiments, the zinc metal or zinc-containing compound of the third spent solution is extracted and / or recovered according to a process comprising: contacting the third spent solution with a hydroxide-based reagent, a metal oxide-based reagent, a carbonate-based reagent, a bi carbonate -based reagent, or a combination thereof.

[0204] In some embodiments, the hydroxide-based reagent is in the form of a solution. In some embodiments, the hydroxide-based reagent is in the form of an aqueous solution, hi some embodiments, the metal oxide-based reagent is in the form of a solution. In some embodiments, the metal oxide-based reagent is in the form of an aqueous solution.

[0205] in some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide, hi some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0206] In some embodiments, the metal oxide-based reagent comprises a metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide, an alkaline earth metal oxide, or a combination thereof. In some embodiments, the metal oxide salt comprises any other suitable metal oxide salt. In some embodiments, the metal oxide salt comprises anAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)alkali metal oxide. In some embodiments, the alkali metal oxide comprises lithium oxide. In some embodiments, the alkali metal oxide comprises sodium oxide. In some embodiments, the alkali metal oxide comprises potassium oxide. In some embodiments, the alkali metal oxide comprises cesium oxide. In some embodiments, the metal oxide salt comprises an alkaline earth metal oxide. In some embodiments, the alkaline earth metal oxide comprises magnesium oxide. In some embodiments, the alkaline earth metal oxide comprises calcium oxide. In some embodiments, the alkaline earth metal oxide comprises strontium oxide. In some embodiments, the alkaline earth metal oxide comprises barium oxide.

[0207] In some embodiments, the carbonate -based reagent is in the form of a solution. In some embodiments, the carbonate-based reagent is in the form of an aqueous solution. In some embodiments, the bicarbonate-based reagent is in the form of a solution. In some embodiments, the bicarbonate-based reagent is in the form of an aqueous solution.

[0208] In some embodiments, the carbonate -based reagent comprises a carbonate-based salt. In some embodiments, the carbonate-based salt comprises an ammonium carbonate, an alkali metal carbonate, an alkaline earth metal carbonate, or a combination thereof. In some embodiments, the carbonate-based salt comprises any other suitable carbonate-based salt. In some embodiments, the carbonate-based salt comprises an alkali metal carbonate. In some embodiments, the alkali metal carbonate comprises lithium carbonate. In some embodiments, the alkali metal carbonate comprises sodium carbonate. In some embodiments, the alkali metal carbonate comprises potassium carbonate. In some embodiments, the alkali metal carbonate comprises cesium carbonate. In some embodiments, the carbonate-based salt comprises an alkaline earth metal carbonate. In some embodiments, the alkaline earth metal carbonate comprises magnesium carbonate. In some embodiments, tire alkaline earth metal carbonate comprises calcium carbonate. In some embodiments, the alkaline earth metal carbonate comprises strontium carbonate. In some embodiments, the alkaline earth metal carbonate comprises barium carbonate.

[0209] In some embodiments, the bicarbonate-based reagent comprises a bicarbonate-based salt, hi some embodiments, the bicarbonate-based salt comprises an ammonium bicarbonate, an alkali metal bicarbonate, or a combination thereof. In some embodiments, the bicarbonatebased salt comprises any other suitable bicarbonate -based salt. In some embodiments, the bicarbonate-based salt comprises an alkali metal bicarbonate. In some embodiments, the alkali metal bicarbonate comprises lithium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises sodium bicarbonate. In some embodiments, the alkali metalAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)bicarbonate comprises potassium bicarbonate. In some embodiments, the alkali metal bicarbonate comprises cesium bicarbonate,

[0210] In some embodiments, the zinc metal or zinc-containing compound is extracted and / or recovered as a zinc hydroxide, a zinc oxide, a zinc carbonate, a zinc bicarbonate, or a combination thereof. In some embodiments, the zinc metal or zinc-containing compound is extracted and / or recovered as zinc hydroxide. In some embodiments, the zinc metal or zinc- containing compound is extracted and / or recovered as zinc carbonate.

[0211] In some embodiments, the process for extracting and / or recovering the zinc metal or zinc-containing compound can be used for extracting and / or recovering the zinc metal or zinc-containing compound from any other sample (e.g., any leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, 700, and / or embodiments thereof).

[0212] An aspect of the disclosure also provides for a metal and / or metal -containing compound comprising aluminum, titanium, zinc, gallium, germanium, or the combination thereof extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, an aluminum sulfate is extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, an aluminum oxalate is extracted, recovered, and / or prepared according to tire process 400 and / or embodiments thereof. In some embodiments, aluminum hydroxide is extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, zinc hydroxide is extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, zinc carbonate is extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof. In some embodiments, titania is extracted, recovered, and / or prepared according to the process 400 and / or embodiments thereof.

[0213] As shown in FIG, 10, an aspect of the disclosure also provides for a process 600 for extracting and / or recovering metals or metal -containing compounds comprising iron, aluminum, titanium, or a combination thereof from iron oxides, aluminum oxides, titanium oxides, or a combination thereof from a sample (e.g., a leach residue, or any other suitable sample, including those disclosed herein), the process comprising: contacting the sample with an acid; and contacting the acid-contacted sample with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof to produce a mixture comprising iron hydroxides (e.g., ferric hydroxide).Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0214] An aspect of the disclosure also provides for an embodiment of the process 600 for extracting and / or recovering metals or metal -containing compounds comprising iron, aluminum, titanium, or a combination thereof from iron oxides, aluminum oxides, titanium oxides, or a combination thereof from a third leach residue (e.g., the third leach residue from the process 300 and / or embodiments thereof), the process comprising: contacting the third leach residue with an acid (e.g., mineral acid); and contacting the acid-contacted third leach residue with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof to produce a mixture comprising iron hydroxides (e.g., ferric hydroxide).

[0215] In some embodiments, the third leach residue comprises the third leach residue from the process 300 or an embodiment thereof.

[0216] In some embodiments, the acid comprises an organic acid, inorganic acid, or a combination thereof. In some embodiments, the acid comprises an inorganic acid. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the acid (e.g., mineral acid) is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the acid comprises sulfuric acid. In some embodiments, the acid is in the form of an aqueous solution. Additionally or alternatively, any suitable acid known to those of ordinary skill in the art can be used.

[0217] In some embodiments, the hydroxide-based reagent is in the form of a solution. In some embodiments, the hydroxide-based reagent is in the form of an aqueous solution. In some embodiments, the metal oxide-based reagent is in the form of a solution. In some embodiments, the metal oxide-based reagent is in the form of an aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent is in the form of a solution. In some embodiments, the combination of the hydroxide- based reagent and the metal oxide-based reagent is in the form of an aqueous solution.

[0218] In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide. In some embodiments, the hydroxide salt comprises an alkalineAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0219] In some embodiments, the metal oxide-based reagent comprises a metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide, an alkaline earth metal oxide, or a combination thereof. In some embodiments, the metal oxide salt comprises any other suitable metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide. In some embodiments, the alkali metal oxide comprises lithium oxide. In some embodiments, the alkali metal oxide comprises sodium oxide. In some embodiments, the alkali metal oxide comprises potassium oxide. In some embodiments, the alkali metal oxide comprises cesium oxide. In some embodiments, the metal oxide salt comprises an alkaline earth metal oxide. In some embodiments, the alkaline earth metal oxide comprises magnesium oxide. In some embodiments, the alkaline earth metal oxide comprises calcium oxide. In some embodiments, the alkaline earth metal oxide comprises strontium oxide. In some embodiments, the alkaline earth metal oxide comprises barium oxide.

[0220] In some embodiments, the combination of the hydroxide- based reagent and the metal oxide-based reagent comprises calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprises lime (i.e., for a liming reaction).

[0221] In some embodiments, the acid-contacted third leach residue is contacted with the hydroxide-based reagent. In some embodiments, the acid-contacted third leach residue is contacted with the metal oxide-based reagent. In some embodiments, the acid-contacted third leach residue is contacted with the combination of the hydroxide-based reagent and the metal oxide-based reagent.

[0222] In some embodiments, contacting the acid-contacted third leach residue with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step comprises precipitating the iron hydroxides (e.g., ferric hydroxide). In some embodiments, the process 600 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated iron hydroxides (e.g., ferric hydroxide). In some embodiments, the precipitated iron hydroxides are separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery of the precipitated iron hydroxides leaves behind a spent solution (e.g., a fourth spent solution). In some embodiments, the spentAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)solution from the process 600 and / or embodiments thereof (i.e., fourth spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal-containing compounds, and / or other compounds (e.g., oxalic acid). In some embodiments, the spent solution from the process 600 and / or embodiments thereof (i.e., fourth spent solution) comprises aluminum sulfates, titanium sulfates, or a combination thereof. In some embodiments, tlie aluminum sulfates, titanium sulfates, or a combination thereof can be extracted and / or recovered.

[0223] As shown in FIG. 11, in an embodiment of the process 600, the process comprises: contacting tlie third leach residue with an acid (e.g., mineral acid) comprising sulfuric acid; and contacting the sulfuric acid-contacted third leach residue with a hydroxide -based reagent comprising calcium hydroxide, a metal oxide-based reagent comprising calcium oxide, or a combination thereof to produce a mixture comprising ferric hydroxide.

[0224] In some embodiments, the third leach residue comprises the third leach residue from the process 300 or an embodiment thereof.

[0225] In some embodiments, the acid (e.g., mineral acid) comprising sulfuric acid is in the form of an aqueous solution. In some embodiments, the acid is sulfuric acid. In some embodiments, the sulfuric acid is in the form of an aqueous solution.

[0226] In some embodiments, the hydroxide-based reagent comprises calcium hydroxide. In some embodiments, the hydroxide-based reagent is calcium hydroxide. In some embodiments, the metal oxide-based reagent comprises calcium oxide. In some embodiments, the metal oxide-based reagent is calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprises calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and tire metal oxide-based reagent consists essentially of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide¬ based reagent comprises lime (i.e., for a liming reaction).

[0227] In some embodiments, the hydroxide-based reagent comprising calcium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprising calcium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide-based reagent is calcium hydroxide. In some embodiments, tire calcium hydroxideAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)is in the form of a solution. In some embodiments, the calcium hydroxide is in the form of an aqueous solution.

[0228] In some embodiments, the metal oxide-based reagent comprising calcium oxide is in the form of a solution. In some embodiments, the metal oxide-based reagent comprising calcium oxide is in the form of an aqueous solution. In some embodiments, the metal oxidebased reagent is calcium oxide. In some embodiments, the calcium oxide is in the form of a solution. In some embodiments, the calcium oxide is in the form of an aqueous solution.

[0229] In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprising calcium hydroxide and calcium oxide is in the form of a solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprising calcium hydroxide and calcium oxide is in the form of an aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists essentially of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists essentially of a calcium hydroxide and calcium oxide solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide¬ based reagent consists essentially of a calcium hydroxide and calcium oxide aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of a calcium hy droxide and calcium oxide solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of a calcium hydroxide and calcium oxide aqueous solution.

[0230] In some embodiments, the sulfuric acid-contacted third leach residue is contacted with the hydroxide-based reagent comprising calcium hydroxide. In some embodiments, the sulfuric acid -contacted third leach residue is contacted with the metal oxide-based reagent comprising calcium oxide. In some embodiments, the sulfuric acid-contacted third leach residue is contacted with the combination of the hydroxide-based reagent and the metal oxide -based reagent comprising calcium hydroxide and calcium oxide. In some embodiments, the sulfuric acid-contacted third leach residue is contacted with the combination of the hydroxide-based reagent and the metal oxide-based reagent consisting essentially of calcium hydroxide and calcium oxide. In some embodiments, the sulfuric acid- contacted third leach residue is contacted with the combination of the hydroxide-basedAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)reagent and the metal oxide-based reagent consisting of calcium hydroxide and calcium oxide,

[0231] In some embodiments, contacting the sulfuric acid-contacted third leach residue with the metal hydroxide-based reagent comprising calcium hydroxide, metal oxide-based reagent comprising calcium oxide, or a combination thereof step comprises precipitating the ferric hydroxide. In some embodiments, the process 600 and / or embodiments thereof further comprises separating, isolating, and / or recovering the precipitated ferric hydroxide. In some embodiments, the precipitated ferric hydroxide is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery’ of the precipitated ferric hydroxide leaves behind a spent solution (e.g., a fourth spent solution). In some embodiments, the spent solution from the process 600 and / or embodiments thereof (i.e., fourth spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal -containing compounds, and / or other compounds (e.g., oxalic acid). In some embodiments, the spent solution from the process 600 and / or embodiments thereof (i.e., fourth spent solution) comprises aluminum sulfates, titanium sulfates, or a combination thereof. In some embodiments, the aluminum sulfates, titanium sulfates, or a combination thereof can be extracted and / or recovered.

[0232] An aspect of the disclosure also provides for a metal and / or metal -containing compound comprising iron, aluminum, titanium, or a combination thereof extracted, recovered, and / or prepared according to the process 600 and / or embodiments thereof, hi some embodiments, iron hydroxides (e.g., ferric hydroxide) are extracted, recovered, and / or prepared according to the process 600 and / or embodiments thereof. In some embodiments, ferric hydroxide is extracted, recovered, and / or prepared according to the process 600 and / or embodiments thereof.

[0233] As shown in FIG, 12, an aspect of the disclosure provides for a process 700 for extracting and / or recovering a metal or metal -containing compound comprising gallium, germanium, or a combination thereof from a sample (e.g., a solvent extract, or any other suitable sample, including those disclosed herein), the process comprising: contacting the sample with an acid to produce a mixture comprising a third precipitate and a sixth supernatant; isolating the sixth supernatant from the third precipitate; and contacting the sixth supernatant with a hydroxide-based reagent to produce a mixture comprising a fourth precipitate and a fifth spent solution.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0234] An aspect of the disclosure also provides for an embodiment of the process 700 for extracting and / or recovering a metal or metal -containing compound comprising gallium, germanium, or the combination thereof from a first solvent extract (e.g., the first solven t extract from the process 400 and / or embodiments thereof), the process comprising: contacting the sample with an acid (e.g., mineral acid) to produce a mixture comprising a third precipitate and a sixth supernatant; isolating the sixth supernatant from the third precipitate; and contacting the sixth supernatant with a hydroxide-based reagent to produce a mixture comprising a fourth precipitate and a fifth spent solution.

[0235] In some embodiments, the first solvent extract comprises the first solvent extract from the process 400 or an embodiment thereof.

[0236] In some embodiments, the acid comprises an organic acid, inorganic acid, or a combination thereof. In some embodiments, the acid comprises an inorganic acid. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the acid (e.g., mineral acid) is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In some embodiments, the acid comprises sulfuric acid. In some embodiments, the acid is in the form of an aqueous solution. Additionally or alternatively, any suitable acid known to those of ordinary skill in the art can be used.

[0237] In some embodiments, the third precipitate comprises gallium hydroxides. In some embodiments, the gallium hydroxides comprise a gallium hydroxide (Ga(OH)₃) precipitate. In some embodiments, the third precipitate comprises gallium hydroxide (Ga(OH)₃).

[0238] In some embodiments, the hydroxide-based reagent is in the form of a solution. In some embodiments, the hydroxide-based reagent is in the form of an aqueous solution.

[0239] In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metal hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide, hr some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprisesAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0240] In some embodiments, isolating the sixth supernatant from the third precipitate comprises separating the sixth supernatant from the third precipitate by filtration.

[0241] In some embodiments, the fourth precipitate comprises germanium hydroxides. In some embodiments, the germanium hydroxides comprise a germanium hydroxide (Ge(OH)₄) precipitate. In some embodiments, the fourth precipitate comprises germanium hydroxide (Ge(OH)₄).

[0242] In some embodiments, the process 700 and / or embodiments thereof further comprises separating, isolating, and / or recovering the fourth precipitate (e.g., germanium hydroxide). In some embodiments, the fourth precipitate is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recover} / of the fourth precipitate leaves behind a spent solution (e.g., a fifth spent solution). In some embodiments, the spent solution from the process 700 and / or embodiments thereof (i.e., fifth spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for tire extraction and / or recovery of different metals, metal-containing compounds, and / or other compounds (e.g., oxalic acid),

[0243] As shown in FIG. 13, in an embodiment of the process 700, the process comprises: contacting the sample with an acid (e.g., mineral acid) comprising sulfuric acid to produce a mixture comprising a third precipitate and a sixth supernatant; isolating the sixth supernatant from the third precipitate; and contacting the sixth supernatant with a hydroxide-based reagent comprising sodium hydroxide to produce a mixture comprising a fourth precipitate and a fifth spent solution.

[0244] In some embodiments, the first solvent extract comprises the first solvent extract from the process 400 or an embodiment thereof.

[0245] In some embodiments, the acid (e.g., mineral acid) comprising sulfuric acid is in the form of an aqueous solution. In some embodiments, the acid is sulfuric acid. In some embodiments, the sulfuric acid is in the form of an aqueous solution.

[0246] In some embodiments, the third precipitate comprises gallium hydroxides. In some embodiments, the gallium hydroxides comprise a gallium hydroxide (Ga(OH)₃) precipitate. In some embodiments, the third precipitate comprises gallium hydroxide (Ga(OH)₃).Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0247] In some embodiments, the hydroxide-based reagent comprises sodium hydroxide. In some embodiments, the hydroxide-based reagent is sodium hydroxide. In some embodiments, the hydroxide-based reagent comprising sodium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprising sodium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide-based reagent is sodium hydroxide. In some embodiments, the sodium hydroxide is in the form of a solution. In some embodiments, the sodium hydroxide is in the form of an aqueous solution.

[0248] In some embodiments, isolating the sixth supernatant from the third precipitate comprises separating the sixth supernatant from the third precipitate by filtration.

[0249] in some embodiments, the fourth precipitate comprises germanium hydroxides. In some embodiments, the germanium hydroxides comprise a germanium hydroxide (Ge(OH)4) precipitate. In some embodiments, the fourth precipitate comprises germanium hydroxide (Ge(OH)4).

[0250] In some embodiments, the process 700 and / or embodiments thereof further comprises separating, isolating, and / or recovering the fourth precipitate (e.g., germanium hydroxide). In some embodiments, the fourth precipitate is separated, isolated, and / or recovered by filtration. In some embodiments, separation, isolation, and / or recovery of the fourth precipitate leaves behind a spent solution (e.g., a fifth spent solution). In some embodiments, the spent solution from the process 700 and / or embodiments thereof (i.e,, fifth spent solution) can be used as the input sample, source, and / or waste / process stream in any of the processes and / or embodiments thereof disclosed herein to be repurposed and / or recycled for the extraction and / or recovery of different metals, metal-containing compounds, and / or other compounds (e.g., oxalic acid).

[0251] An aspect of the disclosure also provides for a metal and / or metal -containing compound comprising gallium, germanium, or the combination thereof extracted, recovered, and / or prepared according to the process 700 and / or embodiments thereof. In some embodiments, gallium hydroxide is extracted, recovered, and / or prepared according to the process 700 and / or embodiments thereof, hi some embodiments, germanium hydroxide is extracted, recovered, and / or prepared according to the process 700 and / or embodiments thereof.4.5. Processes for Recycling of Oxalate-Containing Tailings and Other Waste / Process Streams for Recovery of Oxalic AcidAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0252] As shown in FIG. 8, an aspect of the disclosure provides for a process 500 for recycling and / or recovering oxalic acid from a sample (e.g., one or more sources of oxalate, an oxalate-containing tailing, or any other suitable sample, including those disclosed herein), the process comprising: contacting the sample with a hydroxide-based reagent, a metal oxide- based reagent, or a combination thereof to produce a mixture comprising a metal oxalate; and contacting the metal oxalate with an acid to produce a mixture comprising oxalic acid.

[0253] An aspect of the disclosure also provides for an embodiment of the process 500 for recycling and / or recovering oxalic acid from one or more sources of oxalate (e.g., oxalate-containing tailings), the process comprising: contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof to produce a mixture comprising a metal oxalate; and contacting the metal oxalate with an acid (e.g., mineral acid) to produce a mixture comprising oxalic acid.

[0254] In some embodiments, the one or more sources of oxalate comprise oxalate-containing tailings. In some embodiments, the oxalate-containing tailings comprise sodium oxalate tailings from a Bayer process. In some embodiments, the one or more sources of oxalate comprise oxalate-containing tailings produced from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof).

[0255] In some embodiments, the hydroxide-based reagent is in the form of a solution, hi some embodiments, the hydroxide-based reagent is in the form of an aqueous solution. In some embodiments, the metal oxide-based reagent is in the form of a solution. In some embodiments, the metal oxide-based reagent is in the form of an aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent is in the form of a solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent is in the form of an aqueous solution.

[0256] In some embodiments, the hydroxide-based reagent comprises a hydroxide salt. In some embodiments, the hydroxide salt comprises an ammonium hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. In some embodiments, the hydroxide salt comprises any other suitable hydroxide salt. In some embodiments, the hydroxide salt comprises an alkali metal hydroxide. In some embodiments, the alkali metal hydroxide comprises lithium hydroxide. In some embodiments, the alkali metal hydroxide comprises sodium hydroxide. In some embodiments, the alkali metalAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)hydroxide comprises potassium hydroxide. In some embodiments, the alkali metal hydroxide comprises cesium hydroxide. In some embodiments, the hydroxide salt comprises an alkaline earth metal hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises magnesium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises calcium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises strontium hydroxide. In some embodiments, the alkaline earth metal hydroxide comprises barium hydroxide.

[0257] In some embodiments, the metal oxide-based reagent comprises a metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide, an alkaline earth metal oxide, or a combination thereof. In some embodiments, the metal oxide salt comprises any other suitable metal oxide salt. In some embodiments, the metal oxide salt comprises an alkali metal oxide. In some embodiments, the alkali metal oxide comprises lithium oxide. In some embodiments, the alkali metal oxide comprises sodium oxide. In some embodiments, the alkali metal oxide comprises potassium oxide. In some embodiments, the alkali metal oxide comprises cesium oxide, In some embodiments, the metal oxide salt comprises an alkaline earth metal oxide. In some embodiments, the alkaline earth metal oxide comprises magnesium oxide. In some embodiments, the alkaline earth metal oxide comprises calcium oxide. In some embodiments, the alkaline earth metal oxide comprises strontium oxide. In some embodiments, the alkaline earth metal oxide comprises barium oxide.

[0258] In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprises calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprises lime (i.e., for a liming reaction).

[0259] In some embodiments, the one or more sources of oxalate (e.g., oxalate-containing tailings) are contacted with the hydroxide-based reagent. In some embodiments, the one or more sources of oxalate (e.g,, oxalate-containing tailings) are contacted with the metal oxidebased reagent. In some embodiments, the one or more sources of oxalate (e.g., oxalate- containing tailings) are contacted with the combination of the hydroxide-based reagent and the metal oxide-based reagent.

[0260] In some embodiments, the acid comprises an organic acid, inorganic acid, or a combination thereof. In some embodiments, the acid comprises an inorganic acid. In some embodiments, the inorganic acid is a mineral acid. In some embodiments, the acid (e.g., mineral acid) is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, perchloric acid, and a combination thereof. In someAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)embodiments, the acid comprises sulfuric acid. In some embodiments, the acid is in the form of an aqueous solution. Additionally or alternatively, any suitable acid known to those of ordinary skill in the art can be used.

[0261] In some embodiments, contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with the hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof step comprises precipitating the metal oxalate to produce a metal oxalate precipitate and a fourth supernatant.

[0262] In some embodiments, the process 500 and / or embodiments thereof further comprises separating the metal oxalate precipitate from the fourth supernatant prior to contacting the metal oxalate with the acid (e.g., mineral acid). In some embodiments, separating the metal oxalate precipitate from the fourth supernatant comprises filtration of the mixture comprising the metal oxalate precipitate and the fourth supernatant.

[0263] In some embodiments, the contacting the metal oxalate with the acid (e.g., a mineral acid comprising sulfuric acid) step comprises precipitating a metal sulfate to produce a metal sulfate precipitate and a fifth supernatant. In some embodiments, the metal sulfate precipitate comprises gypsum. In some embodiments, the fifth supernatant comprises oxalic acid.

[0264] In some embodiments, the contacting the metal oxalate with the acid (e.g., mineral acid) step further comprises heating to maintain a temperature between from about 70 °C to about 120 °C. In some embodiments, the contacting the metal oxalate with the acid (e.g., mineral acid) step comprises heating to maintain the temperature between from about 70 °C to about 120 °C, from about 75 °C to about 120 °C, from about 80 °C to about 120 °C, from about 85 °C to about 120 °C, from about 90 °C to about 120 °C, from about 95 °C to about 120 °C, from about 100 °C to about 120 °C, from about 105 °C to about 120 °C, from about 110 °C to about 120 °C, from about 115 °C to about 120 °C, from about 70 °C to about 115 °C, from about 75 °C to about 115 °C, from about 80 °C to about 115 °C, from about 85 °C to about 115 °C, from about 90 °C to about 115 °C, from about 95 °C to about 115 °C, from about 100 °C to about 115 °C, from about 105 °C to about 115 °C, from about 110 °C to about 115 °C, from about 70 °C to about 110 °C, from about 75 °C to about 110 °C, from about 80 °C to about 110 °C, from about 85 °C to about 110 °C, from about 90 °C to about 110 °C, from about 95 °C to about 110 °C, from about 100 °C to about 110 °C, from about 105 °C to about 110 °C, from about 70 °C to about 105 °C, from about 75 °C to about 105 °C, from about 80 °C to about 105 °C, from about 85 °C to about 105 °C, from about 90 °C to about 105 °C, from about 95 °C to about 105 °C, from about 100 °C to about 105 °C, from about 70 °C to about 100 °C, from about 75 °C to about 100 °C, from about 80 °C to aboutAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)100 °C, from about 85 °C to about 100 °C, from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, from about 70 °C to about 95 °C, from about 75 °C to about 95 °C, from about 80 °C to about 95 °C, from about 85 °C to about 95 °C, from about 90 °C to about 95 °C, from about 70 °C to about 90 °C, from about 75 °C to about 90 °C, from about 80 °C to about 90 °C, from about 85 °C to about 90 °C, from about 70 °C to about 85 °C, from about 75 °C to about 85 °C, from about 80 °C to about 85 °C, from about 70 °C to about 80 °C, from about 75 °C to about 80 °C, from about 70 °C to about 75 °C, any other intermediate range, any other suitable range, any other lower range, or any other greater range, In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 80 °C to about 100 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 85 °C to about 100 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 90 °C to about 100 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 95 °C to about 100 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 80 °C to about 95 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 85 °C to about 95 °C, In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 90 °C to about 95 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 80 °C to about 90 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 85 °C to about 90 °C. In some embodiments, tire contacting the metal oxalate with the acid step comprises heating to maintain the temperature between from about 80 °C to about 85 °C.

[0265] In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature at about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, about 100 °C, about 101 °C, about 102 °C, about 103 °C, about 104 °C, about 105 °C, about 106 °C, about 107 °C, about 108 °C, about 109 °C, about 110 °C, about 111 °C, about 112 °C, about 113 °C, about 114 °C,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 115 °C, about 116 °C, about 117 °C, about 118 °C, about 119 °C, about 120 °C, below 70 °C, above 120 °C, or at any other suitable temperature. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature at about 80 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature at about 85 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature at about 90 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature at about 95 °C. In some embodiments, the contacting the metal oxalate with the acid step comprises heating to maintain the temperature at about 100 °C.

[0266] In some embodiments, the oxalic acid remains in solution in the fifth supernatant.

[0267] In some embodiments, the process 500 and / or embodiments further comprises separating the metal sulfate precipitate from the fifth supernatant. In some embodiments, separating the metal sulfate precipitate from the fifth supernatant comprises filtration of the mixture of the metal sulfate precipitate and the fifth supernatant (i.e., filtration of the mixture comprising oxalic acid). In some embodiments, separating the metal sulfate precipitate from the fifth supernatant comprises filtration of the mixture comprising oxalic acid. In some embodiments, the separated fifth supernatant comprising oxalic acid can be used in any of the processes and / or embodiments thereof disclosed herein (i.e., this recycled / recovered oxalic acid solution can be used as the oxalate-based leaching agent or the oxalate-based reagent).

[0268] In some embodiments, the filtration step further comprises heating the mixture comprising the oxalic acid (i.e., the mixture of the metal sulfate precipitate and the fifth supernatant) to maintain a temperature between from about 70 °C to about 110 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 70 °C to about 110 °C, from about 75 °C to about 110 °C, from about 80 °C to about 110 °C, from about 85 °C to about 110 °C, from about 90 °C to about 110 °C, from about 95 °C to about 110 °C, from about 100 °C to about 110 °C, from about 105 °C to about 110 °C, from about 70 °C to about 105 °C, from about 75 °C to about 105 °C, from about 80 °C to about 105 °C, from about 85 °C to about 105 °C, from about 90 °C to about 105 °C, from about 95 °C to about 105 °C, from about 100 °C to about 105 °C, from about 70 °C to about 100 °C, from about 75 °C to about 100 °C, from about 80 °C to about 100 °C, from about 85 °C to about 100 °C, from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, from about 70 °C to about 95 °C, from about 75 °C to about 95 °C, from about 80 °C to about 95 °C, from about 85 °C to about 95 °C, from about 90 °C toAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)about 95 °C, from about 70 °C to about 90 °C, from about 75 °C to about 90 °C, from about 80 °C to about 90 °C, from about 85 °C to about 90 °C, from about 70 °C to about 85 °C, from about 75 °C to about 85 °C, from about 80 °C to about 85 °C, from about 70 °C to about 80 °C, from about 75 °C to about 80 °C, from about 70 °C to about 75 °C, any other intermediate range, any other suitable range, any other lower range, or any other greater range, during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 85 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 90 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 95 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains tire temperature between from about 85 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 90 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 90 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 85 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 85 °C during filtration.

[0269] In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, about 100 °C, about 101 °C, about 102 °C, about 103 °C, about 104 °C, about 105 °C, about 106 °C, about 107 °C, about 108 °C, about 109 °C, about 110 °C, below 70 °C, above 110 °C, or at any other suitable temperature, during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 80 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 85 °C during filtration. In someAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 90 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 100 °C during filtration.

[0270] As shown in FIG. 9, in an embodiment of the process 500, the process comprises: contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with a hydroxide-based reagent comprising calcium hydroxide, a metal oxide-based reagent comprising calcium oxide, or a combination thereof to produce a mixture comprising a calcium oxalate; and contacting the calcium oxalate with an acid (e.g., mineral acid) comprising sulfuric acid to produce a mixture comprising oxalic acid.

[0271] In some embodiments, the one or more sources of oxalate comprise oxalate-containing tailings. In some embodiments, the oxalate-containing tailings comprise sodium oxalate tailings from a Bayer process. In some embodiments, the one or more sources of oxalate comprise oxalate-containing tailings produced from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof).

[0272] In some embodiments, the hydroxide-based reagent comprises calcium hydroxide. In some embodiments, the hydroxide-based reagent is calcium hydroxide. In some embodiments, the metal oxide-based reagent comprises calcium oxide. In some embodiments, the metal oxide-based reagent is calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprises calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and die metal oxide-based reagent consists essentially of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxidebased reagent comprises lime (i.e., for a liming reaction).

[0273] In some embodiments, the hydroxide-based reagent comprising calcium hydroxide is in the form of a solution. In some embodiments, the hydroxide-based reagent comprising calcium hydroxide is in the form of an aqueous solution. In some embodiments, the hydroxide-based reagent is calcium hydroxide. In some embodiments, the calcium hydroxideAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)is in the form of a solution. In some embodiments, the calcium hydroxide is in the form of an aqueous solution.

[0274] In some embodiments, the metal oxide-based reagent comprising calcium oxide is in the form of a solution. In some embodiments, the metal oxide-based reagent comprising calcium oxide is in the form of an aqueous solution. In some embodiments, the metal oxidebased reagent is calcium oxide. In some embodiments, the calcium oxide is in the form of a solution. In some embodiments, the calcium oxide is in the form of an aqueous solution.

[0275] In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprising calcium hydroxide and calcium oxide is in the form of a solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent comprising calcium hydroxide and calcium oxide is in the form of an aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists essentially of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists essentially of a calcium hydroxide and calcium oxide solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide¬ based reagent consists essentially of a calcium hydroxide and calcium oxide aqueous solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of calcium hydroxide and calcium oxide. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of a calcium hy droxide and calcium oxide solution. In some embodiments, the combination of the hydroxide-based reagent and the metal oxide-based reagent consists of a calcium hydroxide and calcium oxide aqueous solution.

[0276] In some embodiments, the one or more sources of oxalate (e.g., oxalate-containing tailings) are contacted with the hydroxide-based reagent comprising calcium hydroxide, hi some embodiments, the one or more sources of oxalate (e.g., oxalate-containing tailings) are contacted with the metal oxide-based reagent comprising calcium oxide. In some embodiments, the one or more sources of oxalate (e.g., oxalate-containing tailings) are contacted with the combination of the hydroxide-based reagent and the metal oxide-based reagent comprising calcium hydroxide and calcium oxide. In some embodiments, the one or more sources of oxalate (e.g., oxalate-containing tailings) are contacted with the combination of the hydroxide-based reagent and the metal oxide-based reagent consisting essentially of calcium hydroxide and calcium oxide. In some embodiments, the one or more sources of oxalate (e.g., oxalate-containing tailings) are contacted with the combination of theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)hydroxide-based reagent and the metal oxide-based reagent consisting of calcium hydroxide and calcium oxide,

[0277] In some embodiments, the acid (e.g., mineral acid) comprising sulfuric acid is in the form of an aqueous solution. In some embodiments, the acid is sulfuric acid. In some embodiments, the sulfuric acid is in the form of an aqueous solution.

[0278] In some embodiments, contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with the hydroxide-based reagent comprising calcium hydroxide, metal oxide-based reagent comprising calcium oxide, or a combination thereof comprises precipitating the calcium oxalate to produce a calcium oxalate precipitate and a fourth supernatant.

[0279] In some embodiments, the process 500 and / or embodiments thereof further comprises separating the calcium oxalate precipitate from the fourth supernatant prior to contacting the calcium oxalate with the acid comprising sulfuric acid. In some embodiments, separating the calcium oxalate precipitate from the fourth supernatant comprises filtration of the mixture comprising the calcium oxalate precipitate and the fourth supernatant.

[0280] In some embodiments, the contacting the calcium oxalate with the acid (e.g., mineral acid) comprising sulfuric acid step comprises precipitating a calcium sulfate (e.g., gypsum) to produce a calcium sulfate precipitate and a fifth supernatant. In some embodiments, the calcium sulfate precipitate comprises gypsum. In some embodiments, the fifth supernatant comprises oxalic acid.

[0281] In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step further comprises heating to maintain a temperature between from about 90 °C to about 100 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature between from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, or from about 90 °C to about 95 °C, In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature between from about 90 °C to about 95 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature between from about 95 °C to about 100 °C.

[0282] In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature at about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, or about 100 °C. In some embodiments, the contacting the calcium oxalate withAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)the acid comprising sulfuric acid step comprises heating to maintain tire temperature at about 90 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature at about 92 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature at about 94 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature at about 96 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature at about 98 °C. In some embodiments, the contacting the calcium oxalate with the acid comprising sulfuric acid step comprises heating to maintain the temperature at about 100 °C.

[0283] In some embodiments, the oxalic acid remains in solution in the fifth supernatant.

[0284] In some embodiments, the process 500 and / or embodiments further comprises separating the calcium sulfate precipitate from the fifth supernatant. In some embodiments, separating the calcium sulfate precipitate from the fifth supernatant comprises filtration of the mixture of the calcium sulfate precipitate and the fifth supernatant (i.e., filtration of the mixture comprising oxalic acid). In some embodiments, separating the calcium sulfate precipitate from the fifth supernatant comprises filtration of the mixture comprising oxalic acid. In some embodiments, the separated fifth supernatant comprising oxalic acid can be used in any of the processes and / or embodiments thereof disclosed herein (i.e., this recycled / recovered oxalic acid solution can be used as the oxalate-based leaching agent or the oxalate-based reagent).

[0285] In some embodiments, the filtration step further comprises heating the mixture comprising the oxalic acid (i.e., the mixture of the calcium sulfate precipitate and the fifth supernatant) to maintain a temperature between from about 80 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 100 °C, from about 85 °C to about 100 °C, from about 90 °C to about 100 °C, from about 95 °C to about 100 °C, from about 80 °C to about 95 °C, from about 85 °C to about 95 °C, from about 90 °C to about 95 °C, from about 80 °C to about 90 °C, from about 85 °C to about 90 °C, or from about 80 °C to about 85 °C. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 85 °C to about 100 °C during filtration. In some embodiments, heatingAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)the mixture comprising the oxalic acid maintains the temperature between from about 90 °C to about 100 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 95 °C to about 100 °C during filtration. In some embodiments, heating tire mixture comprising the oxalic acid maintains tire temperature between from about 80 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 85 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 90 °C to about 95 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 90 °C during filtration. In some embodiments, heating tire mixture comprising the oxalic acid maintains tire temperature between from about 85 °C to about 90 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature between from about 80 °C to about 85 °C during filtration.

[0286] In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, or about 100 °C, during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 80 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 85 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 90 °C during filtration. In some embodiments, heating the mixture comprising the oxalic acid maintains the temperature at about 95 °C during filtration. In some embodiments, heating tire mixture comprising the oxalic acid maintains the temperature at about 100 °C during filtration.

[0287] An aspect of the disclosure also provides for oxalic acid recycled, extracted, recovered, and / or prepared according to the process 500 and / or embodiments thereof. In some embodiments, the oxalic acid is recycled, extracted, recovered, and / or prepared from one or more sources of oxalate according to the process 500 and / or embodiments thereof. In some embodiments, the oxalic acid is recycled, extracted, recovered, and / or prepared from sodium oxalate tailings from a Bayer process according to the process 500 and / or embodiments thereof. In some embodiments, the oxalic acid is in the form of a solution (e.g.,Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)aqueous solution) recycled, extracted, recovered, and / or prepared according to the process 500 and / or embodiments thereof.

[0288] An aspect of the disclosure also provides for processes for recycling of CO(g), CO2 (g), and combinations thereof for recovery of oxalic acid. In some embodiments, the processes for recycling CO2 (g) or gaseous mixtures comprising CO2 (g) comprise conversion of the CO2 (g) to CO (g).

[0289] As shown in FIG. 14, an aspect of the disclosure provides for a process 800 for recovering oxalic acid from a sample (e.g., a gas comprising CO (g), or any other suitable sample, including those disclosed herein), the process comprising: converting the CO (g) present in the sample to an oxalic acid diester; dehydrating the oxalic acid diester; purifying the oxalic acid diester; and hydrolyzing the oxalic acid diester to oxalic acid.

[0290] In some embodiments, converting the CO (g) present in the sample to the oxalic acid diester comprises reacting the CO (g) with an alcohol in the presence of a palladium source, a metal halide, and oxygen. In some embodiments, the alcohol is selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, or a combination thereof. In some embodiments, the palladium source is a palladium catalyst. In some embodiments, the palladium source is a palladium dihalide. In some embodiments, the palladium dihalide comprises palladium dichloride. In some embodiments, the palladium dichloride behaves as a catalyst for the reaction. In some embodiments, the metal halide comprises a copper halide. In some embodiments, the copper halide comprises copper dichloride. In some embodiments, the copper dichloride behaves as a catalyst for the reaction. In some embodiments, the oxygen comprises oxygen recycled from any one of the processes disclosed herein (e.g., of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof). In some embodiments, the oxygen comprises oxygen recycled from the process 100 and / or embodiments thereof. In some embodiments, oxygen recycled from the process 100 and / or embodiments thereof is produced during the heating of the ferrous oxalate.

[0291] In some embodiments, dehydrating the oxalic acid diester comprises heating the oxalic acid diester.

[0292] In some embodiments, purifying the oxalic acid diester comprises separation of the oxalic acid diester from the palladium source and / or metal halide. In some embodiments, the separation of the oxalic acid diester from the palladium source and / or metal halide comprises filtration. In some embodiments, purifying the oxalic acid diester comprises distillation of the oxalic acid diester. In some embodiments, the oxalic acid diester is separated from theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)palladium source and / or metal halide prior to distillation, In some embodiments, the oxalic acid diester is not separated from the palladium source and / or metal halide prior to distillation.

[0293] In some embodiments, hydrolyzing the oxalic acid diester to oxalic acid comprises contacting the oxalic acid diester with water. In some embodiments, hydrolyzing the oxalic acid diester to oxalic acid comprises contacting the oxalic acid diester with an aqueous solution.

[0294] An aspect of the disclosure also provides for oxalic acid recycled, extracted, recovered, and / or prepared according to the process 800 and / or embodiments thereof. In some embodiments, the oxalic acid is in the form of a solution (e.g., aqueous solution) recycled, extracted, recovered, and / or prepared according to the process 800 and / or embodiments thereof,

[0295] Recycling of CO(g), CO2 (g), and combinations thereof for recovery of oxalic acid can also involve other processes, including those disclosed in: U. S. Pat. No. 1,602,802 entitled “Manufacture of Oxalates and Oxalic Acid’’; U. S. Pat. No. 4,713,483 entitled “Process for the Production of Oxalic Acid Diesters’’; and U. S. Pat. No. 5,171,887 entitled “Process for the Preparation of Oxalic Acid and Sodium Hydrogen Oxalate From Crude Sodium Oxalate"’; which are hereby incorporated by reference in their entirety, for all purposes. Aspects of these processes can also be adapted for use in the processes of the present disclosure, including their use in combination wi th processes of the present disclosure, or use of their aspects to modify tire processes of tire present disclosure.

[0296] Aspects of the disclosure provide for processes for recycling and / or repurposing of various tailings (e.g., from industrial processes, from processes and / or embodiments thereof disclosed herein, from any other process) and waste / process streams (e.g., from industrial processes, from any other suitable process) for the extraction and / or recovery of oxalic acid. Oxalic acid extracted and / or recovered from such sources / samples (e.g., in the form of an oxalic acid solution) can be used to carry out any of the processes and / or embodiments thereof disclosed herein (i.e., the recovered oxalic acid can serve as an oxalate-based leaching agent or oxalate-based reagent). Thus, tailings and waste / process streams generated from the processes and / or embodiments thereof disclosed herein, as well as tailings and waste / process streams from any other process (e.g., other industrial sources, such as a Bayer process, thermal power plant, steam methane reforming plant), can be repurposed and / or recycled (e.g., by recovering oxalic acid from oxalates, CO (g), CO2 (g), or any other suitable oxalic acid precursor) to increase the efficiency of the processes and / or embodiments thereofAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)disclosed herein. An embodiment of such a recycling scheme is illustrated in FIG. 15. Other suitable recycling schemes can also be contemplated based on the present disclosure.

[0297] In some embodiments of any of the processes disclosed herein (i.e., process 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), the oxalate-based leaching agent or oxalate-based reagent comprises oxalic acid derived or recycled from one or more sources selected from: commercially available oxalic acid, an oxalate -containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g). In some embodiments of the process 100, the oxalate-based leaching agent comprises oxalic acid derived or recycled from one or more sources selected from: commercially available oxalic acid, an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g). In some embodiments of the process 300, the oxalate-based reagent comprises oxalic acid derived or recycled from one or more sources selected from: commercially available oxalic acid, an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g).

[0298] In some embodiments of any of the processes disclosed herein (i.e., process 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), the oxalate-based leaching agent or oxalate-based reagent comprises oxalic acid recycled, extracted, and / or recovered from one or more sources selected from: an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate- containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g). In some embodiments of the process 100, the oxalate-based leaching agent comprises oxalic acid recycled from one or more sources selected from: an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of theAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g). In some embodiments of the process 300, the oxalate-based reagent comprises oxalic acid recycled from one or more sources selected from: an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate -containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g).

[0299] In some embodiments, the recycling (e.g., recycling of the one or more sources selected from: an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from any of the processes disclosed herein (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts from any of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof), CO (g), and CO2 (g)) comprises at least 25%, at least 26%, at least 27%, at least 28%, at least 29%, at least 30%, at least 31%, at least 32%, at least 33%, at least 34%, at least 35%. at least 36%, at least 37%, at least 38%, at least 39%, at least 40%, at least 41%, at least 42%, at least 43%, at least 44%, at least 45%, at least 46%, at least 47%, at least 48%, at least 49%, at least 50%, at least 51%, at least 52%, at least 53%, at least 54%, at least 55%, at least 56%, at least 57%, at least 58%, at least 59%, at least 60%, at least 61%, at least 62%, at least 63%, at least 64%, at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71 %, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100% recovery of oxalic acid based on the one or more sources. In some embodiments, the recycling comprises at least 40% recovery of oxalic acid based on the one or more sources. In some embodiments, the recycling comprises at least 45 % recovery of oxalic acid based on the one or more sources. In some embodiments, the recycling comprises at least 50% recovery’ of oxalic acid based on the one or more sources. In some embodiments, the recycling compri ses at least 55% recovery’ of oxalic acid based on the one or more sources. In some embodiments, tire recycling comprises at least 60% recovery of oxalic acid based on the one or more sources. In some embodiments, the recycling comprises at least 65% recovery’ of oxalic acid based on the one or more sources. In some embodiments, the recycling comprises at least 70?<) recovery of oxalic acid based on the one or more sources. InAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)some embodiments, the recycling comprises at least 75% recovery of oxalic acid based on the one or more sources.

[0300] In some embodiments, any of the processes disclosed herein (i.e., process 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof) can be repeated multiple times (i.e., multiple cycles ofthe process). In some embodiments, the process 100 is repeated multiple times (i.e., multiple cycles of the process 100). In some embodiments, one or more times / cycles ofthe process 100 further comprise one or more times / cycles of the process 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof In some embodiments, the oxalic acid used is recycled, extracted, and / or recovered from one or more oxalate-containing tailings selected from leachates, leach residues, supernatants, precipitates, or spent solutions produced from a previous cycle of any of the processes disclosed herein (i.e., process 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof). In some embodiments, the oxalic acid is recycled, extracted, and / or recovered from one or more oxalate-containing tailings selected from leachates, leach residues, supernatants, precipitates, or spent solutions according to the process 500 and / or embodiments thereof disclosed herein.

[0301] In some embodiments, the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof can be carried out in combination for the extraction and / or recovery of metals and metal-containing compounds from a material comprising iron (e.g. bauxite residue). In some embodiments, the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof can be carried out in combination for the extraction and / or recovery of metals and metal-containing compounds from other samples, sources, and / or waste / process streams. In some embodiments, a subset of the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof can be carried out in combination for the extraction and / or recovery of metals and metal -containing compounds from a material comprising iron. The processes can be carried out in any order (e.g., any suitable order). In some embodiments, the processes 100, 200, 300, 400, 500, 600, and / or 700 and / or embodiments thereof can be carried out independently of each other.In some embodiments, the processes disclosed herein can be performed at a site co-located with one or more sites that are the sources of samples, tailings, and / or waste / process streams that can be repurposed and / or recycled according to the processes disclosed herein (e.g., at a site co-located with an aluminum refine ry, thermal power plant, or any other suitable site). This can eliminate transportation needs, further mitigating costs and environmental impacts.5. EQUIVALENTS AND INCORPORATION BY REFERENCEAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)

[0302] While aspects of this disclosure have been particularly shown and described with reference to a preferred embodiment and various alternate embodiments, it will be understood by persons skilled in the relevant art that various changes in form and details can be made therein without departing from the scope of the disclosure.

[0303] All references, issued patents and patent applications cited within the body of the instant specification, including U. S. Provisional Appl. No. 63 / 749,970, are hereby incorporated by reference in their entirety, for all purposes.

Claims

Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)CLAIMSWhat is claimed is:

1. A process for extracting iron from a material comprising iron, the process comprising:leaching the material comprising iron with an oxalate -based leaching agent to produce a mixture comprising a first leachate and a first leach residue, wherein tire first leachate comprises ferric oxalate;contacting the first leachate with an iron-containing reagent to produce ferrous oxalate;isolating the ferrous oxalate from the contacted first leachate; andconverting the ferrous oxalate to iron.

2. The process of claim 1, wherein the material comprising iron is selected from: bauxite residue, electric arc furnace dusts, gothites, jarosites, titanium-scandium wastes, low grade iron ores, zinc refinery residues, waste permanent rare-earth magnets, NdFeB magnets, mill scales, and a combination thereof.

3. The process of claim 2, wherein the material comprising iron comprises bauxite residue.

4. The process of claim 3, wherein the bauxite residue comprises raw bauxite residue from a Bayer process.

5. The process of claim 4, wherein the raw bauxite residue is in the form of a slurry.

6. The process of any one of claims 1 to 5, wherein the oxalate-based leaching agent comprises oxalic acid, an oxalate salt, or a combination thereof.

7. The process of claim 6, wherein the oxalate-based leaching agent comprises oxalic acid,8. Tire process of any one of claims 1 to 7, wherein the oxalate-based leaching agent is in the form of an aqueous solution.

9. The process of any one of claims 1 to 8, further comprising separating the first leachate from the first leach residue prior to contacting the first leachate with the iron-Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)containing reagent to produce the ferrous oxalate.

10. The process of claim 9, wherein separating the first leachate from the first leach residue comprises filtering the mixture comprising the first leachate and the first leach residue.

11. The process of any one of claims 1 to 10, wherein the contacting the first leachate with the iron-containing reagent step comprises precipitating the ferrous oxalate to produce ferrous oxalate precipitate and a first supernatant,12. Tire process of any one of claims 1 to 11, wherein isolating the ferrous oxalate from the contacted first leachate comprises separating the ferrous oxalate from the contacted first leachate by filtration.

13. The process of any one of claims 1 to 12, wherein isolating the ferrous oxalate further comprises separating the ferrous oxalate from the iron-containing reagent.

14. The process of claim 13, wherein separating the ferrous oxalate from the iron- containing reagent comprises magnetic separation of the ferrous oxalate from the iron- containing reagent.

15. The process of claim 14, wherein the iron -containing reagent is recovered and optionally used for the contacting the first leachate step to further produce the ferrous oxalate.

16. Tire process of any one of claims 1 to 15, wherein the iron-containing reagent comprises elemental iron.

17. The process of claim 16, wherein the elemental iron is selected from: iron powder, iron flakes, iron turnings, or a combination thereof.

18. The process of any one of claims 1 to 17, wherein a pH during the leaching of the material comprising iron step is maintained in a range between from about 0 to about 3 (e.g., from about 1.5 to about 3, or from about 2 to about 2.5).

19. The process of any one of claims 1 to 18, further comprising heating during the leaching of the material comprising iron step to maintain a temperature between from aboutAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)80 °C to about 100 °C (e.g., from about 90 °C to about 95 °C).

20. The process of any one of claims 1 to 19, wherein the contacting the first leachate with tire iron-containing reagent step further comprises heating the first leachate to maintain a temperature between from about 40 °C to about 60 °C (e.g., at about 50 °C).

21. The process of any one of claims 1 to 20, wherein converting the ferrous oxalate to iron comprises heating the ferrous oxalate.

22. The process of claim 21, wherein heating tire ferrous oxalate further comprises conversion of the ferrous oxalate to an iron oxide.

23. The process of claim 21 or 22, wherein heating the ferrous oxalate comprises heating under an ambient environment, an inert environment, or a low pCh environment.

24. The process of claim 23, wherein the inert environment comprises N2 (g).

25. The process of claim 23, wherein the low pCh environment comprises N2 (g), H2 (g), CO (g), CO2 (g), H2O (g), O2 (g), or a mixture thereof.

26. The process of any one of claims 21 to 25, wherein the ferrous oxalate is heated in the presence of a carbon source.

27. Tire process of claim 26, wherein the carbon source is selected from solid carbon, powdered carbon, graphite, or a combination thereof.

28. The process of any one of claims 21 to 27, wherein heating the ferrous oxalate comprises heating the ferrous oxalate at a temperature from about 400 °C to about 1100 °C (e.g., from about 400 °C to about 700 °C, or from about 400 °C to about 500 °C).

29. The process of any one of claims 1 to 28, wherein the process is carried out under ambient light conditions.

30. The process of claim 29, wherein the process does not comprise illumination w ith a UV-light or an infrared-light source device.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)31. The process of any one of claims 1 to 30, wherein the first leach residue comprises a metal or metal -containing compound composing iron, aluminum, titanium, calcium, rare-earth metals, or a combination thereof.

32. The process of claim 31, further comprising extracting the rare-earth metal or rare-earth metal-containing compound.

33. The process of claim 31 or 32, wherein extracting the metal or metal-containing compound (e.g., the rare-earth metal or rare-earth metal -containing compound) comprises: contacting the first leach residue with a carbonate -based reagent, a bicarbonate-based reagent, or a combination thereof to produce a mixture comprising a second leachate and a second leach residue;contacting the second leachate with an acid (e.g., a mineral acid) to produce a mixture comprising a first precipitate and a second supernatant;isolating the second supernatant from the first precipitate; andcontacting the second supernatant with a hydroxide-based reagent,34. Tire process of claim 33, wherein the carbonate-based reagent comprises a carbonate-based salt.

35. The process of claim 34, wherein the carbonate-based salt comprises an alkali metal carbonate (e.g., sodium carbonate), an alkaline earth metal carbonate, or a combination thereof.

36. The process of claim 33, wherein the bicarbonate-based reagent comprises a bicarbonate-based salt.

37. The process of claim 36, wherein the bicarbonate-based salt comprises an alkali metal bicarbonate (e.g., sodium bicarbonate).

38. Tire process of any one of claims 33 to 37, wherein the acid comprises sulfuric acid.

39. The process of any one of claims 33 to 38, wherein the first precipitate comprises a titania precipitate.

40. Tire process of any one of claims 33 to 39, wherein the hydroxide-based reagentAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)comprises a hydroxide salt.

41. The process of claim 40, wherein the hydroxide salt comprises an alkali metal hydroxide (e.g,, sodium hydroxide).

42. Tire process of any one of claims 33 to 41, further comprising separating (e.g., by¬ filtration) tlie second leachate from the second leach residue prior to contacting the second leachate with the acid.

43. Hie process of any one of claims 33 to 42, wherein isolating the second supernatant from the first precipitate comprises separating the second supernatant from the first precipitate by filtration.

44. The process of any one of claims 33 to 43, wherein contacting the second supernatant with the hydroxide-based reagent comprises precipitating the metal or metal-containing compound (e.g., the rare-earth metal or rare-earth metal -containing compound).

45. The process of any one of claims 33 to 44, further comprising an optional roasting step prior to contacting the first leach residue with the carbonate -based reagent, bicarbonate¬ based reagent, or combination thereof step.

46. The process of claim 31 or 32, wherein extracting the metal or metal-containing compound (e.g., the rare-earth metal or rare-earth metal -containing compound) comprises: contacting the first leach residue with an acid (e.g., a mineral acid);leaching the acid-contacted first leach residue with a solution comprising water to produce a mixture comprising a third leachate and a third leach residue, wherein the third leachate comprises a metal sulfate (e.g., a rare-earth metal sulfate);contacting the third leachate with an oxalate-based reagent to produce a metal oxalate (e.g., a rare-earth metal oxalate) from the metal sulfate; androasting the metal oxalate to produce a metal oxide (e.g., a rare-earth metal oxide).

47. Tire process of claim 46, wherein the acid comprises sulfuric acid.

48. The process of claim 46 or 47, wherein the oxalate-based reagent comprises oxalic acid, an oxalate salt, or a combination thereof.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)49. The process of claim 48, wherein the oxalate-based reagent comprises oxalic acid.

50. The process of any one of claims 46 to 49, further comprising separating (e.g., by filtration) the third leachate from the third leach residue prior to contacting the third leachate with the oxalate-based reagent.

51. The process of any one of claims 46 to 50, wherein contacting the third leachate with the oxalate-based reagent comprises precipitating the metal oxalate (e.g., the rare-earth metal oxalate).

52. Tire process of any one of claims 46 to 51, wherein the third leach residue comprises an iron oxide, aluminum oxide, titanium oxide, or a combination thereof.

53. The process of claim 52, further comprising extracting a metal or metal -containing compound comprising iron, aluminum, titanium, or a combination thereof from the iron oxide, aluminum oxide, titanium oxide, or the combination thereof of the third leach residue.

54. The process of any one of claims 46 to 53, further comprising an optional roasting step prior to contacting the first leach residue with the acid.

55. The process of any one of claims 11 to 54, wherein the first supernatant comprises a metal or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or a combination thereof (e.g,, titanium oxalates, aluminum oxalates, zinc oxalates, gallium oxalates, germanium oxalates, or a combination thereof).

56. The process of claim 55, further comprising extracting the metal or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or the combination thereof.

57. The process of claim 56, wherein extracting the metal or metal-containing compound comprising aluminum, titanium, zinc, gallium, germanium, or the combination thereof comprises:contacting the first supernatant with an acid (e.g., a mineral acid);heating the acid-contacted first supernatant to produce a mixture comprising a second precipitate and a third supernatant;Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)isolating the third supernatant from the second precipitate; andcontacting the third supernatant with a hydroxide-based reagent, a metal oxide-based reagent, or a combination thereof.

58. The process of claim 57, wherein the acid comprises sulfuric acid.

59. The process of claim 57 or 58, wherein the second precipitate comprises a titania precipitate.

60. The process of any one of claims 57 to 59, wherein the third supernatant comprises an aluminum sulfate, an aluminum oxalate, or a combination thereof.

61. The process of any one of claims 57 to 60, wherein the hydroxide-based reagent comprises a hydroxide salt.

62. The process of claim 61, wherein the hydroxide salt comprises an alkali metal hydroxide (e.g., sodium hydroxide), an alkaline earth metal hydroxide (e.g., calcium hydroxide), or a combination thereof.

63. Tire process of any one of claims 57 to 62, wherein the metal oxide-based reagent comprises calcium oxide.

64. The process of any one of claims 57 to 63, wherein a pH during the heating the acid- contacted first supernatant step is maintained in a range between from about 0 to about 4 (e.g., from about 1 to about 2).

65. The process of any one of claims 57 to 64, wherein the heating the acid-contacted first supernatant step maintains the temperature between from about 85 °C to about 95 °C (e.g., at about 90 °C).

66. The process of any one of claims 57 to 65, wherein isolating the third supernatant from the second precipitate comprises separating the third supernatant from the second precipitate by filtration.

67. The process of any one of claims 57 to 66, wherein a pH during the contacting the third supernatant w ith the hydroxide -based reagent, the metal oxide-based reagent, or aAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)combination thereof step is maintained in a range between from about 5 to about 6.

68. The process of any one of claims 57 to 67, wherein contacting the third supernatant with tire hydroxide-based reagent, the metal oxide-based reagent, or a combination thereof comprises precipitating Al(OH)3.

69. The process of any one of claims 57 to 68, further comprising extracting the zinc metal or zinc-containing compound from a third spent solution remaining following precipitation of the Al(0H)3, the process for extracting the zinc metal or zinc-containing compound comprising: contacting the third spent solution with a hydroxide-based reagent, a metal oxide-based reagent, a carbonate-based reagent, a bicarbonate -based reagent, or a combination thereof.

70. The process of any one of claims 1 to 69, wherein the oxalate-based leaching agent comprises oxalic acid derived or recycled from one or more sources selected from: commercially available oxalic acid, an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from the process according to any one of claims 1 to 69 (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts), CO, and CO2.

71. The process of any one of claims 1 to 69, wherein the oxalate-based leaching agent comprises oxalic acid recycled from one or more sources selected from: an oxalate-containing tailing from a Bayer process, an oxalate-containing tailing from tire process according to any one of claims 1 to 69 (e.g., oxalate-containing leaches, leach residues, supernatants, precipitates, spent solutions, or solvent extracts), CO, and CO2.

72. Ihe process of claim 71, wherein the recycling comprises at least 50% recovery of oxalic acid based on the one or more sources.

73. The process of claim 70 or 71, further comprising repeating the process of claim 1 one or more times.

74. The process of claim 73, wherein the oxalic acid is recycled from one or more oxalate-containing tailings selected from leachates, leach residues, supernatants, precipitates, spent solutions, or solvent extracts produced from a previous cycle of the process.Attorney Ref: 43300-65026 / WO (0001-WO-NPV01)75. The process of any one of claims 70 to 74, wherein the oxalic acid is recycled from one or more sources of oxalate (e.g., oxalate-containing tailings) according to a process comprising:contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with a hydroxide-based reagent (e.g., an alkaline earth metal hydroxide), a metal oxide-based reagent (e.g., an alkaline earth metal oxide), or a combination thereof to produce a mixture comprising a metal oxalate (e.g., an alkaline earth metal oxalate); andcontacting the metal oxalate with an acid (e.g., a mineral acid) to produce a mixture comprising oxalic acid.

76. The process of claim 75, wherein the hydroxide-based reagent comprises calcium hydroxide.

77. The process of claim 75, wherein the metal oxide-based reagent comprises calcium oxide.

78. Tire process of any one of claims 75 to 77, wherein the acid comprises sulfuric acid.

79. The process of any one of claims 75 to 78, wherein the contacting the one or more sources of oxalate (e.g., oxalate-containing tailings) with the hydroxide-based reagent, tire metal oxide-based reagent, or the combination thereof step comprises precipitating the metal oxalate (e.g., the alkaline earth metal oxalate) to produce a metal oxalate precipitate and a fourth supernatant.

80. The process of any one of claims 75 to 79, further comprising separating (e.g., by filtration) the metal oxalate (e.g., the alkaline earth metal oxalate) precipitate from the fourth supernatant prior to contacting the metal oxalate with the acid (e.g., mineral acid).

81. The process of any one of claims 75 to 80, wherein the contacting the metal oxalate (e.g., the alkaline earth metal oxalate) with the acid (e.g., mineral acid) step comprises precipitating a metal sulfate (e.g., an alkaline earth metal sulfate) to produce a metal sulfate precipitate and a fifth supernatant.

82. The process of any one of claims 75 to 81, wherein the contacting the metal oxalate (e.g., the alkaline earth metal oxalate) with the acid (e.g., mineral acid) step further comprisesAttorney Ref: 43300-65026 / WO (0001-WO-NPV01)heating to maintain a temperature between from about 90 °C to about 100 °C.

83. The process of any one of claims 75 to 82, wherein the oxalic acid remains in solution in the fifth supernatant.

84. Tire process of any one of claims 75 to 83, further comprising separating the metal sulfate (e.g., the alkaline earth metal sulfate) precipitate from the fifth supernatant.

85. The process of claim 84, wherein separating the metal sulfate (e.g., the alkaline earth metal sulfate) precipitate from the fifth supernatant comprises filtering the mixture comprising oxalic acid.

86. The process of claim 85, wherein the filtration step further comprises heating the mixture comprising the oxalic acid to maintain a temperature at about 90 °C during filtration.

87. The process of claim 70 or 71, wherein the CO, CO2, or combination thereof is derived or recycled from the process according to any one of claims 1 to 86 (e.g., upon heating of the ferrous oxalate for conversion to iron), an output of an industrial process (e.g., a by-product or waste stream of steam methane reforming, or operation of a thermal power plant), or a combination thereof.

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