Method for co-producing lithium, aluminum and silicon-oxygen (Si-O) materials

Abstract

The present invention relates generally to a process for co-producing lithium, aluminum and silicon-oxygen (Si-O) materials, and more particularly, to a process for co-producing lithium, aluminum and Si-O materials from a hard rock source in the form of a particulate concentrate of one or more lithium-containing silicate minerals comprising spodumene. Specifically, a process is provided for co-production of Li, Al and Si-O materials from the beta-form of lithium-containing silicate mineral spodumene having the composition LiAlSi2O6 in its purely state.

Description

Technical Field

[0001] This invention generally relates to a method for the co-production of lithium, aluminum and silicon-oxygen (Si-O) materials, and more specifically, to a method for the co-production of lithium, aluminum and Si-O materials from a particulate concentrate formed from one or more lithium-containing silicate minerals (including spodumene).

[0002] Statement regarding federally funded research or development

[0003] none.

[0004] Statement regarding the inventor's previous disclosures

[0005] The invention described in U.S. Provisional Application 63 / 413029 (filed on September 30, 2022) was disclosed to Medaro Mining Corporation after September 30, 2022, under the terms of a confidentiality agreement and a joint venture agreement. Background Technology

[0006] Lithium (Li), aluminum (Al), and silicon (Si) materials are crucial in many commercial applications when recovered and processed from sources in the Earth's crust. In the case of lithium and its compounds, the most common uses are in the manufacture of lithium-ion batteries, lubricants, and glass ceramics, as well as in the formation of lithium alloys with aluminum and magnesium (Mg). Aluminum and its compounds also have many different uses, for example, in the case of alumina (Al₂O₃): as an Al source for the manufacture of metallic Al, Al alloys, and glass ceramics; as an abrasive; and as a catalyst support. As for silicon, its common oxide, silicon dioxide (SiO₂), is used in the manufacture of, for example, glass ceramics, silicon-based glass optical fibers, glass fibers, precipitated silica, and silica gel.

[0007] Specifically for lithium materials, the increasing demand for higher capacity and longer-lasting lithium batteries has driven the demand for lithium carbonate (Li2CO3) and lithium hydroxide monohydrate (LiOH·H2O).

[0008] In response to this development, brine deposits in South America (mainly in Chile and Argentina) have become a major source of Li materials, especially Li₂CO₃. Simultaneously, lithium extraction from Li-bearing silicate minerals has increased dramatically, most notably from spodumene minerals (whose purest form is LiAlSi₂O₆).

[0009] Representative literature reflecting the state of the art regarding the extraction of Li from spodumene includes, for example, US2017 / 0175228 A1 (Hunwick), published on June 22, 2017, which describes a method comprising a heat treatment unit configured to operate at a temperature that converts previously leached lithium material into solid lithium oxide (Li₂O). The heat treatment unit may include a baker. The heat treatment may also employ indirect heating of the extracted lithium material (which may be lithium nitrate (LiNO₃)). In the case of LiNO₃, indirect heating may include the catalytic combustion of ammonia (NH₃) in excess air. The gas stream generated by the heat treatment may be collected for reuse in acid leaching and / or for regenerating nitric acid. The reference notes that, in acid leaching, the silicate mineral may be mixed with nitric acid. The reference also notes that leaching conditions may include increasing temperature and / or pressure to accelerate the extraction of lithium as lithium nitrate from the silicate mineral, but non-lithium values ​​in the silicate mineral tend not to leach from the silicate mineral. As will become apparent from the following text, the conditions that tend to prevent non-lithium leaching are the opposite of what occurs in this invention.

[0010] Another reference, CA 3009374A1 (Hunwick), published on June 29, 2017, discloses a method for recovering lithium from silicate minerals, the method comprising: (a) mixing the silicate minerals with nitric acid; (b) subjecting the mixture obtained from step (a) to a leaching process having conditions that allow the lithium value in the silicate minerals to be leached as LiNO3 into an aqueous phase; (c) separating LiNO3 from the aqueous phase; (d) heat-treating the LiNO3 obtained from step (c) at a temperature that decomposes the separated LiNO3 into solid lithium oxide and results in the generation of a gaseous stream containing nitrogen oxides; and (e) feeding the gaseous stream containing nitrogen oxides to a nitric acid production stage, in which nitric acid is formed for reuse in the leaching process.

[0011] In addition, CN106906359A (ICSIP Pty Ltd.), published on June 30, 2017, discloses a method for recovering lithium from silicate minerals, wherein in an embodiment described as a side-flow treatment scheme, ammonium carbonate can be used to precipitate lithium as lithium carbonate.

[0012] Furthermore, CN113603122A (Hunan Tiantai Tianrun New Energy Technology Co., Ltd.), published on November 5, 2021, discloses a method for synthesizing battery-grade lithium carbonate, specifically including the following steps: S1: Pretreatment: After discharging, dismantling, and crushing recycled waste lithium iron phosphate batteries, electrode powder is obtained; S2: Nitration reaction: The above electrode powder is added to a nitric acid solution for nitration reaction, with a liquid-to-solid ratio of 4:1, and a nitrate product is obtained after the reaction; S3: Calcination: The above nitrate product is calcined to obtain calcined sand; S4: Leaching: The calcined sand is leached with water, with a solid-to-liquid ratio of 1:2, and filtered to obtain a lithium-rich solution; S5: Preparation of battery-grade lithium carbonate: While stirring at 50°C, a carbonate (e.g., ammonium carbonate) is added to the lithium-rich solution. The reference indicates that battery-grade lithium carbonate is obtained after reaction, filtration and washing, drying, sieving, and packaging.

[0013] CN115537580A (Jiangxi Shanning Technology Co., Ltd.), published on December 30, 2022 (after the priority date of this application), discloses a method for extracting lithium from lithium ore, comprising the following steps: 1) after mixing lithium ore with nitrate, ball milling, roasting, acid leaching, and filtering, obtaining a lithium-containing solution and silica-rich slag; 2) after mixing the lithium-containing solution with a carbonate (e.g., ammonium carbonate), precipitating lithium to obtain a lithium-containing compound; wherein the lithium ore is selected from "at least two of spodumene, lepidolite, and lithium porcelain stone". In a preferred embodiment, the precipitation is described as being carried out at 85°C-100°C.

[0014] In addition, CN1024124C (Xinjiang Institute of Nonferrous Metals), published on April 6, 1994, discloses a method for preparing lithium carbonate (quilonum retard), which includes steps such as obtaining lithium carbonate from a lithium-containing sulfate solution using ammonium carbonate as a precipitant.

[0015] Given the current state of the art, there is still a need in the field for a more robust and environmentally friendly method to recover lithium from lithium-containing silicate minerals, including spodumene.

[0016] There is also a need in the field to develop a method that can reduce the current total (β) spodumene conversion cost by about 30-50%, β-spodumene being a crystal form of spodumene that is easily leached by various types of solvents.

[0017] There is also a need in the art for a β-spodumene conversion method that allows for the recovery of not only lithium value, but also aluminum and silicon value.

[0018] There is also a need in the art for a β-spodumene conversion method by which valuable lithium, aluminum and Si-O-containing materials can be co-produced, and then separated to a substantially complete degree of near 100% by a reaction occurring at a temperature of less than or equal to (≤) about 600°C.

[0019] There is also a need in the art for a β-spodumene conversion method in which Li, Al and Si-O-containing materials are produced, separated and recovered in a closed-loop internal chemical cycle, designed to avoid or substantially reduce any Li, Al or Si incorporation into any kind of solid, liquid or gaseous waste.

[0020] There is also a need in the art for a β-spodumene conversion method, by which the only waste generated is essentially: first, quartz, feldspar and other lithium-poor silicate minerals that are typically present in spodumene concentrate; and second, very small amounts (i.e., insignificant, negligible or trace amounts) of crystalline-bound iron, manganese, sodium, potassium, magnesium, calcium, etc., typically less than about 2 wt%, which are inevitably released when β-spodumene is converted into a Li, Al and Si-O-containing material during the execution of the steps according to the invention.

[0021] There is also a need in the art for a physicochemical approach that can not only co-produce valuable Li, Al, and Si-O materials, but also be implemented in compact, modular, and highly scalable manufacturing facilities suitable for deployment in remote geographic locations.

[0022] One or more of the above-mentioned needs, as well as other needs, can be met by the invention described below. Summary of the Invention

[0023] This invention discloses a method for co-producing Li, Al, and Si-O materials from hard-rock source spodumene (which is converted to the β-crystal form). Specifically, the method according to the invention is a novel and entirely different thermochemical technique for extracting Li from β-spodumene and converting it into Li₂CO₃ and / or LiOH·H₂O. Furthermore, the method allows for the co-production of commercially available Al and Si-O materials, such as aluminum hydroxide (Al(OH)₃), alumina (Al₂O₃), and various forms of SiO₂. In one embodiment, after extracting a large amount of Li and Al from β-spodumene in calcined spodumene concentrate using nitric acid, the method utilizes a combined liquid fraction obtained first from nitric acid leaching and then from water washing of the leached particulate β-spodumene fraction, with the aim of producing, separating, and recovering aluminum precipitates. Optionally, the aluminum precipitate may be formed by contacting the combined liquid fraction with one or more of the following: an aqueous solution of ammonium hydroxide (NH4OH); an aqueous solution of ammonium carbonate ((NH4)2CO3); and solid (NH4)2CO3. Subsequently: (i) the aluminum precipitate is recovered using physical means of solid-liquid separation; (ii) the liquid obtained from the solid-liquid separation is contacted with ammonia-carbon dioxide (NH3-CO2) gas and / or a source of (NH4)2CO3 to produce a solid Li2CO3 precipitate; (iii) the Li2CO3 precipitate is recovered using physical means of solid-liquid separation; and (iv) processing steps are taken to regenerate and reuse chemicals capable of additionally producing, separating, and recovering Li, Al, and Si-O materials, these recycled chemicals themselves containing less than about 5% by weight (wt.%) of dissolved, suspended, or entrained Li, Al, and Si-O materials.

[0024] In one embodiment, the present invention relates to a method for extracting Li, Al, and Si-O materials from a hard rock source, wherein the hard rock source is in the form of a granular concentrate of one or more lithium-containing aluminum silicate minerals (including spodumene), the method comprising:

[0025] Provide a hard rock source in the form of a granular concentrate of one or more lithium aluminum silicate minerals (including α-spodumene) (Step 1);

[0026] The granular concentrate is calcined at a high temperature (e.g., in the range of about 900°C to about 1200°C) to obtain a granular concentrate comprising β-spodumene (step 2).

[0027] The granular concentrate containing β-spodumene is mixed with an aqueous nitric acid solution, and the resulting acidic mixture is then stirred or agitated in a first reactor at a temperature greater than or equal to (≥) about 120°C and a pressure greater than or equal to about 1 atm to achieve leaching of Li and Al (step 3).

[0028] The acidic mixture is fed to a second reactor to extract NOH gas at a temperature of ≥120°C and (if necessary) a reduced ambient gas pressure of about 1 atm, to form a slurry with NOH gas removed (Note: "NOH" is NO x (x = 1 and / or 2) - O2 ± H2O ± HNO3, where the symbol “±” indicates the additional presence or absence of the gaseous substance described to the right of the symbol (step 4);

[0029] The slurry is conveyed from the second reactor through a cooling unit to a separator, where it is separated into two fractions: one fraction is rich in leached granular β-spodumene, and the other fraction is an aqueous liquid containing dissolved LiNO3 and dissolved aluminum nitrate (Al(NO3)3) (Note: the aqueous liquid may also contain other dissolved, suspended and / or entrained solids, some of which are impurities whose amount is minimally harmful to the method) (steps 4-6);

[0030] The aqueous liquid containing LiNO3 and Al(NO3)3 is fractionally transferred to the first liquid mixer (step 8);

[0031] The fraction rich in leached β-spodumene particles is transferred to a mixer-washer, where it is mixed with water of sufficient purity and introduced into the mixer-washer together or separately with the water to form a slurry-rich fraction rich in leached β-spodumene particles, wherein the water of sufficient purity is mixed with the residual aqueous liquid containing LiNO3 and Al(NO3)3 formed during the Li-Al leaching process to form wash water containing LiNO3 and Al(NO3)3 (steps 5-7);

[0032] The water-slurry-rich fraction containing leached β-spodumene particles is fed to a separator, where the solid and liquid are separated into two fractions: one fraction contains substantially all of the leached β-spodumene particles (note: this fraction may also contain one or more mineral impurities in amounts that are minimally harmful to the method), and the other fraction contains wash water containing LiNO3 and Al(NO3)3 (step 7).

[0033] The wash water is transferred to the first liquid mixer, where it is combined with the previously separated LiNO3 and Al(NO3)3-containing liquid that has entered the liquid mixer to form an aqueous liquid containing LiNO3 and Al(NO3)3 (step 8). Optionally, the water-washed, leached particulate solids are then sent to an optional reactor (e.g., Figure 1In reactor 9), they are mixed with aqueous / crystalline sodium hydroxide (NaOH) and / or aqueous / crystalline potassium hydroxide (KOH) to produce (Na and / or K, Li, Al, Si-O)-H2O liquid (step 39);

[0034] The liquid in the first liquid mixer is transferred to the third reactor (steps 8 and 9a); and

[0035] The aqueous liquid containing LiNO3 and Al(NO3)3 in the third reactor is treated to form an aluminum precipitate containing H2O (“Al(OH)3”), which may contain amorphous Al-OH solid material mixed with various amounts of quasi-crystalline Al-OH. The treatment includes one or more of the following: (i) heat treatment at a temperature sufficient to decompose Al(NO3)3 dissolved in the liquid (e.g., about 180°C) (step 9a); (ii) reaction with an aqueous liquid containing dissolved NH4OH (step 9b); (iii) contact with an aqueous solution of (NH4)2CO3 (step 9c); and (iv) contact with solid (NH4)2CO3 (step 9c).

[0036] In the context of this invention, the phrase "water of sufficient purity" means any water having sufficient purity for use in the methods according to the invention, and may include untreated atmospheric precipitation or groundwater, or water purified by known methods such as filtration, distillation (including in-situ condensation within the treatment system), and / or by reverse osmosis (RO) / deionization (DI) to the purity levels typically required for process water in the extraction or production of Li suitable for commercial use (e.g., in batteries). Those skilled in the art will understand or be able to determine the required purity level through routine experiments.

[0037] In another implementation, all or substantially all chemicals (e.g., HNO3) and water of sufficient purity are recycled to achieve significant cost savings.

[0038] In another embodiment of the invention, the co-production of Li, Al, and Si-O materials from β-spodumene in calcined spodumene concentrate comprises the following steps (Note: the embodiment is shown in the accompanying drawings). Figure 1-5 In the diagram, the step number on each figure corresponds to the step number contained in parentheses below:

[0039] Provide particulate spodumene concentrate, wherein most of the spodumene is typically present in the α-crystal form (step 1);

[0040] The concentrate is calcined at high temperature to convert substantially all of the α-spodumene into the β-crystal form of the mineral (step 2);

[0041] Before or after entering the first reactor, the (now) β-spodumene concentrate is mixed with (i) an aqueous solution of nitric acid (HNO3) and / or (ii) NOH gas + liquid water (H2O) at a temperature of ≥ about 25°C and a pressure of about 1 atmosphere (1 atm) to about 10 atm (step 3).

[0042] In the first reactor, the acidic mixture contained therein is stirred or agitated at a temperature of ≥120°C and a pressure between 1 atm and 10 atm for a time sufficient to allow the leaching of Li and Al from β-spodumene (step 3).

[0043] The acidic mixture is fed to a second reactor to extract NOH gas at a temperature of ≥ about 120°C, and if necessary, the ambient gas pressure is reduced to about 1 atm to form a substantially gas-free mixture (slurry) (steps 3 and 4).

[0044] The (now) substantially gas-free mixture (slurry) is conveyed from the second reactor through a cooling unit to a separator, where it is separated into two fractions: one fraction is rich in leached granular β-spodumene, and the other fraction is an aqueous liquid containing dissolved LiNO3 and dissolved aluminum nitrate (Al(NO3)3) (Note: As mentioned above, the aqueous liquid may contain very small amounts of dissolved, suspended, and / or entrained solids, some of which are impurities) (steps 4-6);

[0045] The aqueous liquid containing LiNO3 and Al(NO3)3 is transferred to the first liquid mixer (steps 6 and 8);

[0046] The fraction rich in leached β-spodumene particles is transferred to a mixer-washer together with water of sufficient purity that has been mixed into the fraction rich in leached β-spodumene particles before entering the mixer-washer, or this mixing occurs after the fraction rich in leached β-spodumene particles enters the mixer-washer, wherein the water of sufficient purity is mixed with a small amount of residual aqueous liquid containing LiNO3 and Al(NO3)3 formed during the Li-Al leaching process to form wash water containing LiNO3 and Al(NO3)3 (steps 6 and 7);

[0047] The water-slurry-rich fraction containing leached β-spodumene particles is fed to a separator, where the solid and liquid are separated into two fractions: one fraction contains substantially all of the leached β-spodumene particles plus one or more mineral impurities, and the other fraction contains wash water containing LiNO3 and Al(NO3)3 formed in the previous mixing-washing step (step 7).

[0048] The wash water is transferred to the first liquid mixer, where it is combined with the previously separated liquid containing LiNO3 and Al(NO3)3 that has entered the liquid mixer to form an aqueous liquid containing LiNO3 and Al(NO3)3 (steps 7 and 8). Optionally, the water-washed leached particulate solids are then sent to the ninth reactor (step 39), where they are mixed with aqueous / crystalline NaOH and / or aqueous / crystalline KOH to produce a (Na and / or K, Li, Al, Si-O)-H2O liquid (step 7).

[0049] The liquid in the first liquid mixer is transferred to the third reactor (steps 8 and 9a);

[0050] The aqueous liquid containing LiNO3 and Al(NO3)3 in the third reactor is treated to form an aluminum precipitate containing H2O (“Al(OH)3”), which may contain amorphous Al-OH solid material mixed with various amounts of quasi-crystalline Al-OH phase. The treatment includes one or more of the following: (i) heat treatment at a temperature sufficient to decompose Al(NO3)3 dissolved in the liquid (e.g., about 180°C); (ii) reaction with an aqueous liquid containing dissolved NH4OH; (iii) contact with an aqueous solution of (NH4)2CO3; and (iv) contact with solid (NH4)2CO3 (steps 9a-9c).

[0051] (For simplicity, it is assumed that the aluminum precipitate is formed only by heat treatment at about 180°C to decompose Al(NO3)3 dissolved in the liquid.) The slurry flowing out of the third reactor is cooled and then transferred to a mixer-separator, where it is thoroughly stirred and / or agitated to improve the homogeneity of the aqueous liquid. It is then divided into two fractions, one fraction containing substantially all of the aluminum precipitate formed in the third reactor, and the other fraction containing the aqueous liquid containing dissolved LiNO3 (Note: the aqueous liquid may also contain a minimum amount of dissolved, suspended and / or entrained aluminum material, and a small amount of dissolved, suspended and / or entrained solid impurities) (steps 10 and 11).

[0052] The LiNO3-containing liquid fraction is transferred from the separator to the second liquid mixer (steps 11 and 15);

[0053] The moist Al(OH)3 is mixed with water, and the resulting slurry is fed to a mixer-washer, where it is stirred and / or agitated, and then separated into two fractions, one fraction rich in the aluminum precipitate and the other fraction being wash water containing some dissolved LiNO3 (steps 11 and 12).

[0054] The separated wash water is conveyed to the second liquid mixer, where it is combined with the previously separated LiNO3-containing aqueous liquid that has entered the liquid mixer (steps 12 and 15).

[0055] The separated aluminum precipitate is converted into one or more Al-OH solids, such as Al(OH)3 and Al2O3 (step 13 and optional step 14);

[0056] The mixed aqueous liquid containing LiNO3 is transferred from the second liquid mixer to the fourth reactor (step 15);

[0057] The aqueous liquid containing LiNO3 in the fourth reactor is mixed with NH3-CO2 gas and / or (NH4)2CO3 aqueous solution and / or solid (NH4)2CO3 to induce precipitation of solid Li2CO3 and form NH4NO3 aqueous solution at the same time (step 16).

[0058] The aqueous slurry containing Li2CO3, NH4NO3 and (NH4)2CO3 is transferred from the fourth reactor to the fifth reactor, where it is heated to a temperature of about 100°C and subjected to a pressure of about 1 atm, resulting in the decomposition of substantially all remaining dissolved (NH4)2CO3, as demonstrated by the generation of NH3-CO2 exhaust gas (steps 16 and 17).

[0059] The slurry containing Li2CO3 and NH4NO3 flowing out of the fifth reactor is cooled and then transferred to a mixer-separator, where it is stirred or agitated to improve the homogeneity of the aqueous liquid. It is then divided into two fractions: one fraction contains substantially all of the solid Li2CO3 formed in the fourth reactor, and the other fraction is an aqueous liquid containing NH4NO3 (Note: the aqueous liquid containing NH4NO3 may also contain a minimum amount of dissolved, suspended and / or entrained Li2CO3) (steps 18 and 19).

[0060] The aqueous liquid containing NH4NO3 is transferred to a third liquid mixer, and the fraction containing substantially all of the solid Li2CO3 is mixed with water and then sent to a mixer-washer, where it is stirred or agitated, resulting in the formation and separation of wash water containing some dissolved NH4NO3 in a separator connected to the mixer-washer (Note: the formed wash water may also contain the minimum harmful amount of dissolved, suspended and / or entrained Li2CO3 obtained from the wet Li2CO3) (steps 19 and 20);

[0061] The NH4NO3-containing wash water is transferred to the third liquid mixer, where it is combined with the previously separated NH4NO3-containing aqueous liquid that has entered the liquid mixer (steps 20 and 23).

[0062] Optionally, the moist Li2CO3 is conveyed from the separator to the dryer, and then the dried Li2CO3 is optionally transferred to the chemical conversion system, or the moist Li2CO3 is optionally transferred directly from the separator to the chemical conversion system, wherein, regardless of the specific transfer option chosen, the chemical conversion system is used to produce an aqueous LiOH solution and / or solid LiOH·xH2O (x = 1, 2, 3 or 6) by means of techniques known in the art, such as by reacting Li2CO3 with water-slurry Ca(OH)2 (steps 20-22);

[0063] After leaving the third liquid mixer, the aqueous liquid containing NH4NO3 is optionally heated to a temperature of about 120°C as it flows toward an additional mixer, in which it is mixed with an excess of solid magnesium oxide (MgO) and / or magnesium hydroxide (Mg(OH)2), which may be preheated before being mixed with the aqueous liquid containing NH4NO3 (steps 23 and 24).

[0064] The multiphase material is fed from the mixer to a sixth reactor, where its temperature is raised to or maintained at about 120°C, which results in the formation of an aqueous solution of magnesium nitrate (Mg(NO3)2) and possibly additional magnesium hydroxide (Mg(OH)2) and NH3 gas (steps 24 and 25).

[0065] The NH3 gas is fed to a gas mixer, where it is mixed with the supplied CO2 and the NH3-CO2 gas produced in the fifth reactor (steps 25 and 26);

[0066] The mixed NH3-CO2 gas is conveyed through a cooling unit and then recycled to precipitate additional Li2CO3 (step 16), or optionally sent to a seventh reactor, where it is mixed with H2O to form an aqueous (NH4)2CO3 solution, and then the resulting aqueous liquid containing (NH4)2CO3 is recycled to precipitate additional Li2CO3 (step 16) (steps 26 and 27).

[0067] The aqueous slurry (containing significant amounts of Mg(NO3)2, Mg(OH)2 and H2O in the sixth reactor) is transferred to a mixer, where it is stirred or agitated, and then transferred to a separator, where it is separated into two fractions, one fraction containing significant amounts of Mg(OH)2 and the other fraction containing an aqueous liquid containing dissolved Mg(NO3)2 (steps 25 and 28).

[0068] The aqueous liquid containing Mg(NO3)2 is conveyed to the fourth liquid mixer (step 28);

[0069] The Mg(OH)2-rich solid is mixed with water, and the resulting slurry is sent to a mixer-washer where it is stirred or agitated, resulting in wash water containing dissolved Mg(NO3)2 (Note: This Mg(NO3)2-containing wash water may also contain a minimum amount of suspended and / or entrained Mg(OH)2) (steps 28 and 29).

[0070] The aqueous slurry containing Mg(OH)2 and Mg(NO3)2 is transferred to a separator, where it is separated into two fractions, one fraction containing the minimum harmful amount of Mg(OH)2 plus any MgO, and the other fraction containing the Mg(NO3)2-containing wash water formed in the mixer-washer (step 29).

[0071] The Mg(NO3)2-containing wash water is transferred to the fourth liquid mixer, where it is combined with the previously separated Mg(NO3)2-containing aqueous liquid that has entered the liquid mixer (step 29).

[0072] A portion of the moist Mg(OH)2 ± residual MgO (the symbol “±” indicates that MgO may be absent or present) is transferred to the first furnace, where it is heated to a maximum temperature of approximately 600°C, resulting in the production of MgO and water vapor, and the MgO is recycled back to step 24 (steps 29 and 33).

[0073] The aqueous liquid containing Mg(NO3)2 is transferred from the fourth liquid mixer to an evaporator, where it is heated to a temperature of about 150°C, thereby initiating the production of molten Mg(NO3)2·xH2O (x≤6), water vapor, and possibly NOH gas (steps 30 and 31).

[0074] After leaving the evaporator, the H2O-poor (expected x < 2) Mg(NO3)2·xH2O liquid is fed to a mixer, where it is mixed with a portion of the previously generated (step 29) moist Mg(OH)2±MgO (steps 31 and 32).

[0075] The Mg(NO3)2·xH2O-Mg(OH)2±MgO slurry is transferred from the mixer to a second furnace, where it is heated to a maximum temperature of about 600°C to form MgO (which will contain the minimum amount of harmful solid impurities) and NOH gas containing NO2 and O2 (steps 32 and 34).

[0076] The MgO+ solid impurities are fed to a mixer-washer, where the solids are slurried with a liquid in which MgO is substantially insoluble but the solid impurities are fully soluble (steps 34 and 35).

[0077] The MgO-containing slurry is stirred or agitated and then sent to a separator, where it is divided into two fractions. One fraction contains substantially all of the MgO, which is recycled back to step 24, and the other fraction contains a liquid rich in impurities (step 35).

[0078] Optionally, the liquid is processed in a certain way to separate it into two fractions, one fraction being a purified liquid and the other fraction containing impurities present in the liquid fraction formed in the separator (step 36);

[0079] Optionally, the purified liquid can be recycled back to an earlier step, wherein the MgO+ solid impurities are slurried with the initially provided liquid (step 36);

[0080] (i) the NOH gas removed from the second and third reactors, (ii) the NOH gas generated in the evaporator (if any), and (iii) the NOH gas containing NO2 and O2 formed in the second furnace are fed to a gas mixer, where the individual gas streams are mixed (step 37).

[0081] The NOH gas is fed from the gas mixer back to the first reactor and / or to the eighth reactor, where it is mixed with H2O to produce an aqueous HNO3 solution, which is then fed back to the first reactor (step 38).

[0082] Further details of the steps in the described implementation are presented in the following detailed description. Attached Figure Description

[0083] Figure 1-5 Non-limiting embodiments of the physicochemical method of the present invention are shown, with the step numbers on each figure corresponding to the corresponding enumerated steps in the detailed description below. Figure 2As can be observed, although three potential independent options are proposed for converting aqueous Al(NO3)3 into aluminum precipitate (“Al(OH)3”), for the sake of simplicity, the first option (i), namely heat treatment, is chosen to illustrate this conversion. Detailed Implementation

[0084] As shown in the accompanying drawings, the present invention relates to a method for producing Li, Al, and Si-O materials from the β-form of spodumene, wherein the β-form of spodumene has the composition LiAlSi2O6 in its purest state. The following description presents exemplary non-limiting embodiments of the invention, while the appended claims define the scope of patent protection.

[0085] Throughout the following text, the words “transfer,” “transport,” “separate,” and “impurity” can be understood as having the following meanings.

[0086] In the context of the terms “transfer” and “transport,” when used to indicate the movement of the physical location of a liquid or slurry, it can be understood that the material can be pumped by mechanical or gravity or by pressure differential.

[0087] In the context of the word "separation," when used to refer to separating a slurry into solid and liquid components, it can be understood that the separation can be achieved through centrifugation and / or filtration.

[0088] In the context of the term "impurities," the usage includes mineralogical and chemical contaminants that enter, pass through, and ultimately exit the processing loop in the material. Mineralogical impurities include quartz, feldspar, and other substantially lithium-free crystalline solids that may be present in spodumene concentrate. It is worth noting that spodumene concentrate may also contain minor amounts of lithium-bearing minerals other than spodumene, such as petalite, lepidolite, and phosphogypsum, and it should be understood that the processing steps of this invention may have a similar effect on them as the processing steps have on spodumene. However, this document does not further focus on any granite pegmatite accessory minerals that may be present in spodumene concentrate.

[0089] Regarding chemical impurities, only selected trace and minor elements typically present in spodumene in a crystallographic manner are considered below, namely iron, manganese, sodium, potassium, magnesium, and calcium. It will be proposed that the problems associated with these contaminants can be addressed after dissolution (in an aqueous medium) by: (i) inducing precipitation of calcium hydroxide, magnesium hydroxide, and iron and manganese oxides and hydroxides using a caustic alkaline aqueous liquid (e.g., ammonium hydroxide NH4OH aqueous solution); or (ii) inducing precipitation of calcium carbonate and magnesium carbonate using bicarbonate / carbonate materials (e.g., ammonium carbonate (NH4)2CO3 aqueous solution or solid (NH4)2CO3) prior to the conversion of LiNO3 to Li2CO3; and (iii) allowing dissolved alkali metals (most notably Na and K) to remain in solution until all valuable Li, Al, and Si-O materials have formed and separated.

[0090] Another important point is: to simplify the discussion of certain key processing steps and Figure 1-5 The representation of these steps ignores impurities present in the wash water. Although the wash water formed according to the invention will contain dissolved, suspended, and / or entrained contaminants, their amounts are expected to be far lower than their abundance in other liquids formed and evolved in the methods of the invention, and therefore, their presence generally does not adversely affect the treatment or the resulting final product.

[0091] It should also be understood that in various chemical reactions, the abbreviations enclosed in parentheses (attached to the molecular formula of the chemical substance) have the following definitions: s = solid, liq = liquid, aq = aqueous solution, g = gas.

[0092] It can be envisioned that the reactors mentioned below are typically continuous stirred tank reactors, which are very compact due to the rapid kinetics of the reactions occurring inside them.

[0093] It can also be imagined that each of the cooling units mentioned below could be a heat exchanger, or simply a tube wrapped in a heat transfer fluid, whether or not it is at a constant temperature.

[0094] It is also conceivable that, in many cases, satisfactory mixing of liquids and gases in the method of the present invention can be achieved in a static mixer.

[0095] Finally, after weighing the advantages of the chemical techniques disclosed in this specification, those skilled in the art will understand that the method can be applied across a range of lengths, from laboratory benchtops to factory workshops.

[0096] Now, for reference Figure 1-5 The physicochemical steps in the exemplary embodiments are listed and described, with sufficient detail to enable those skilled in the art to use them effectively.

[0097] Step 1: Provide particulate spodumene concentrate, wherein the spodumene exists primarily in the α-crystal form.

[0098] Spodumene is a natural mineral with an ideal / pure / theoretical / end-member composition of LiAlSi2O6. Spodumene concentrate is a granular mechanical mixture of minerals formed by crushing and grinding rocks excavated from spodumene pegmatite formations, wherein the proportion of spodumene in the resulting granular solids is typically increased by at least one refining method, such as heavy media separation and froth flotation.

[0099] Other lithium minerals may also be present in spodumene concentrate, such as petalite (ideally LiAlSi4O). 10 Lithium mica (ideally K(Li,Al)3(Al,Si,Rb)4O) 10 (F,OH)2) and phosphogypsum (ideally (Li,Na)AlPO4(F,OH)), but in always minor amounts. It is worth noting that the three other minor minerals commonly present in spodumene concentrate—quartz (ideally SiO2), albite (ideally NaAlSi3O8), and microcline / orthoclase (ideally KAlSi3O8)—contain only negligible amounts of lithium and are therefore referred to as “mineral impurities” below to distinguish them from chemical impurities.

[0100] Commercially available spodumene concentrate is typically graded based on its Li₂O content. Pure spodumene contains 8.03 wt.% Li₂O; raw spodumene pegmatite ore typically contains 1-2 wt.% Li₂O; spodumene concentrate typically contains 6-7 wt.% Li₂O, with the proportion of spodumene generally between 75 and 87 wt%, which is the desired property for use in the manufacture of Li compounds. Spodumene concentrate containing at least 7.6 wt.% Li₂O and with low iron content is used in the manufacture of ceramics and other special applications.

[0101] Step 2: The granular α-spodumene concentrate provided in Step 1 is calcined at a high temperature or temperature range, for example, between about 900°C and about 1200°C, but more commonly at a temperature or temperature range between about 950°C and 1100°C, with the main purpose of converting all α-lepidolite into β-spodumene.

[0102] Step 3: Provide an aqueous solution of HNO3 and / or NOH gas + H2O, which will be introduced into the first reactor ( Figure 1 It is mixed into the granular β-spodumene concentrate shortly before or after reactor No. 1 in the reactor.

[0103] If provided, the aqueous solution containing HNO3 may contain about 20 wt.% to about 68 wt.% HNO3, with the balance being primarily water. Most preferably, for commercial applications, the aqueous solution will contain about 40 wt.% to about 68 wt.% HNO3.

[0104] Before being fed into the reactor, the aqueous HNO3 solution (if provided) and NOH gas (if provided) can be pretreated to approximately 25 ≤ T (°C) ≤ approximately 140°C and approximately 1 ≤ P (atm) ≤ approximately 10°C. In any case, the final temperature of the resulting acidic slurry is advantageously approximately 120 ≤ T (°C) ≤ approximately 140°C. Heating to temperatures up to approximately 140°C can be achieved by flowing the multiphase material through one or more pipes immersed in a heat transfer liquid. As the material flows, the pressure and temperature of the entire quantity of the material can be maintained or allowed to increase slightly.

[0105] In this step, the particulate β-spodumene begins to leach, wherein at least a significant amount of Li and a smaller portion of Al from the mineral dissolve in the acidic aqueous liquid (see below). This contrasts directly with the description in the prior art reference (US2017 / 0175228A1 (Hunwick)) discussed above, in which the leaching conditions created tend to prevent non-lithium values ​​from leaching from the silicate mineral. Indeed, one of the key features of the method according to the invention is the extraction of both Li and Al during the nitric acid leaching of particulate β-spodumene.

[0106] Data from laboratory-scale testing indicate that contact of β-spodumene with an aqueous HNO3 solution at approximately 120°C and 1 atm results in significant leaching of Li, less (but still significant) leaching of Al, and negligible leaching of Si-O material. Therefore, unlike separating β-spodumene into discrete Li, Al, and Si-O fractions (which is the ultimate goal of the method of this invention), the currently available evidence suggests that the contact produces a partially leached solid material that: may contain a small amount of residual Li; may contain a large amount of residual Al; and of course, contains most of the Si-O material initially present in the β-spodumene. Therefore, it is conceivable that the final composition of β-spodumene leached with nitric acid may include LiAl3Si8O. 20 (OH)2、LiAl4Si 32 O 70 OH and / or Al4Si 64 O 134 Solid aluminosilicates with these compositions may be formed through one or more reactions similar to reaction 1 below, and two more reactions that follow:

[0107]

[0108] It should be understood that in reaction 1 and certain related reactions following this disclosure, the calculated figures above the substances are tonne mass balance figures for the production of 1 ton of LiOH·H2O, assuming (i) LiOH·H2O is produced according to reaction 4 below, and (ii) the final source of Li in LiOH·H2O is LiAlSi2O6 in β-spodumene, which reacts with an aqueous solution of HNO3 according to reaction 1.

[0109] The guiding principle for achieving satisfactory nitric acid Li-Al leaching of β-spodumene is that solid-liquid mixing is preferably carried out under physicochemical conditions that tend to maintain or even increase the wt.% concentration of the HNO3 aqueous solution while preventing any significant loss of β-spodumene. For example, to mitigate the decrease in the wt.% of the HNO3 aqueous solution during the leaching of Li and Al from β-spodumene: (i) the initial wt.% concentration of the HNO3 aqueous solution may be higher than the absolutely necessary concentration, for example, in the range of 50-68 wt.%; and / or (ii) the initial weight ratio of the HNO3 aqueous solution to β-spodumene can be set high enough to ensure that the t.% concentration of the HNO3 aqueous solution remains high throughout the Li-Al leaching process. Alternatively, the wt.% of the HNO3 aqueous solution can be kept high by NOH gas, the continuous presence of which will trigger the reaction 4NO2(g) + O2(g) + 2H2O(liq,g) → 4HNO3(aq,g). As a result, the HNO3 aqueous solution consumed by the reaction with β-spodumene will be offset by the HNO3 aqueous solution replenished by the reaction between NO2, O2 and H2O.

[0110] Finally, at the end of this step, the acidic aqueous slurry in the reactor (which preferably contains about 30% to about 70% by volume of solids) is transferred to a second reactor. Figure 1 Reactor No. 2 in the middle).

[0111] Step 4: Reduce the ambient pressure in reactor 2 to the level required to convert most of the remaining HNO3 aqueous solution into NOH gas.

[0112] By creating a topspace, the gas pressure in reactor 2 can be reduced to approximately 1 atm, in which gas can enter from the heated aqueous slurry below, and gas can be extracted through one or more sides and / or the top of the topspace, which facilitates the degassing of the slurry. It is envisioned that the removed gas will contain volatile NOH substances such as HNO3, H2O, NO2, and O2.

[0113] Step 5: The lean HNO3 aqueous slurry formed in reactor 2 is conveyed to the cooling unit, where its temperature is reduced to a satisfactory level before being transferred to the separator.

[0114] The delivery of the slurry may be entirely or partially driven by a fluid pressure gradient.

[0115] Step 6: After cooling to approximately 25 ≤ T (°C) ≤ approximately 60, the slurry is transferred to a separator, where it is separated into two fractions. One fraction contains substantially all of the leached β-spodumene particles (with minor amounts of one or more lithium pegmatite byproducts), and the other fraction is an aqueous liquid containing LiNO3 and Al(NO3)3 with minimal amounts of residual dissolved, suspended, and / or entrained solids, some of which are impurities.

[0116] After separation, the reacted particulate solids are slurried with water of sufficient purity and conveyed to a mixer-washer connected to the separator. Alternatively, the liquid produced by separation is transferred to a first liquid mixer. Figure 1 Filter before the No. 1 liquid mixer.

[0117] Step 7: Before being transferred to the separator, the water-slurryed particulate solids sent to the mixer-washer are stirred and / or agitated, and then the resulting wash water containing LiNO3 and Al(NO3)3 is sent to liquid mixer No. 1, where it is combined with the aqueous liquid containing LiNO3 and Al(NO3)3 formed in step 6.

[0118] Preferably, the solid is washed in a minimum amount of water of sufficient purity, and after separation, the solid may optionally be reacted with aqueous / crystalline NaOH and / or aqueous / crystalline KOH to produce a caustic alkali (Na and / or K, Li, Al, Si-O)-H2O liquid (step 39).

[0119] Step 8: The aqueous liquid containing LiNO3 and Al(NO3)3 in liquid mixer No. 1 is transferred to the third reactor. Figure 1 and Figure 2 Reactor No. 3 on the surface.

[0120] (Important Note: Steps 9a-c below describe three potential independent methods for producing H2O-containing aluminum precipitates from aqueous liquids containing LiNO3 and Al(NO3)3. For simplicity, this precipitate will be referred to as "Al(OH)3" below, and it is understood to be a water-rich substance that may contain abundant amorphous Al-OH semi-solid (gel-like) material, possibly mixed with one or more quasi-crystalline Al-OH phases.)

[0121] Step 9a: The aqueous liquid containing LiNO3 and Al(NO3)3 present in reactor 3 is heated to ≥140°C to decompose substantially all of the dissolved Al(NO3)3, with the key result being the precipitation of Al(OH)3. (As previously stated, in this disclosure, heat treatment is a selected exemplary processing option for converting the aqueous Al(NO3)3 solution into Al(OH)3. Steps 9b and 9c described below are only intended to indicate the existence of alternative methods for inducing Al(OH)3 precipitation from the aqueous liquid containing LiNO3 and Al(NO3)3.) It is contemplated that the aqueous Al(NO3)3 solution will be decomposed by a reaction similar to the following:

[0122]

[0123] Step 9b: Provide a liquid containing NH4OH dissolved in water and / or a gas containing a large amount of NH3, and mix it with the liquid present in the third reactor to precipitate Al(OH)3. It is envisioned that one or both of these actions will reduce the amount of Al(NO3)3 in the aqueous liquid through a reaction similar to the following:

[0124] Al(NO3)3(aq)+3NH4OH(aq)→Al(OH)3(s)↓+3NH4NO3(aq). (2b)

[0125] In a commercial context, precipitation of Al(OH)3 by any action is preferably carried out at about 25 ≤ T (°C) ≤ about 60 and about 1 ≤ P (atm) ≤ about 10.

[0126] Step 9c: Provide an aqueous liquid containing dissolved (NH4)2CO3 and / or a material containing particulate (NH4)2CO3 and / or a gas containing a large amount of NH3 and CO2, and mix it with the liquid present in reactor 3 for the purpose of precipitating Al(OH)3.

[0127] The three possible reactions for inducing the precipitation of Al(OH)3 from an aqueous liquid containing LiNO3 and Al(NO3)3 using (NH4)2CO3 are:

[0128]

[0129] It is conceivable that, using any of the above reactions, precipitation of Al(OH)3 can be induced at an ambient pressure of approximately 25 ≤ T (°C) ≤ approximately 60 and approximately 1 atm. To ensure optimal production of Al(OH)3 in a commercial context: firstly, the amount of (NH4)2CO3 provided should be close to the minimum amount required to react and remove almost all of the aqueous Al(NO3)3 present in the liquid; secondly, the generated CO2±O2 gases should be removed from the reactor during formation.

[0130] Step 10: The aqueous slurry containing Al(OH)3 and LiNO3 formed in step 9a is transported from reactor No. 3 through the cooling unit to a mixer connected to the separator.

[0131] Step 11: Stir and / or agitate the slurry in the mixer and then flow it into the separator, where it is separated into two fractions, one fraction being essentially Al(OH)3 and the other fraction being an aqueous liquid containing LiNO3.

[0132] After separation, the Al(OH)3 is slurried with water and conveyed to a mixer-washer connected to the separator. Alternatively, it is transferred to a second liquid mixer ( Figure 2 Before the No. 2 liquid mixer on the plate, the aqueous liquid containing LiNO3 produced by separation is filtered.

[0133] Step 12: Stir and / or agitate the water-slurry Al(OH)3 sent to the mixer-washer, and then separate it into fractions rich in Al(OH)3 and rich in washing water.

[0134] Preferably, after adding water to Al(OH)3 in step 11, the slurry obtained in the mixer-washer will contain approximately 30-70% by volume of solids. The newly formed slurry is then stirred and / or agitated, and the Al(OH)3 and wash water may be separated therein by centrifugation and / or filtration. At the end of this step, the wash water is sent to liquid mixer #2, where it is combined with the LiNO3-containing aqueous liquid formed in step 11.

[0135] Step 13: The moist Al(OH)3 produced in step 12 may be heated to a temperature or temperature range between about 100°C and about 300°C to dehydrate the material, which may result in the formation of one or more forms of crystalline Al(OH)3 and / or crystalline Al2O3.

[0136] Step 14: Optionally, the Al-OH solid produced in step 13 may be further processed to produce one or more forms of high-quality Al2O3 and / or Al metal.

[0137] Step 15: Transfer the LiNO3-containing aqueous liquid from liquid mixer No. 2 to reactor No. 4 ( Figure 2 and Figure 3 Reactor No. 4 on the surface.

[0138] Step 16: Combine the LiNO3-H2O liquid in reactor 4 with either of the following: (i) a mixture of NH3-CO2 gas, the composition of which is as shown above, suitable for converting the LiNO3 aqueous solution into particulate Li2CO3, provided in an amount sufficient to react almost all of the LiNO3 aqueous solution; or (ii) an aqueous liquid and / or particulate (NH4)2CO3 containing (NH4)2CO3, provided in an amount of aqueous / solid (NH4)2CO3 exceeding the amount required to react substantially all of the LiNO3 aqueous solution.

[0139] (Optionally, at the beginning of this step, a small amount of NH3-CO2 gas and / or aqueous / solid (NH4)2CO3 is mixed into the aqueous liquid containing LiNO3 to induce precipitation of solid materials containing CaCO3 and MgCO3, the precipitate preferably being immediately separated from the surrounding liquid by filtration and / or centrifugation.)

[0140] When the LiNO3-H2O liquid is combined with a sufficient amount of NH3-CO2 gas of appropriate composition or composition range, it is envisioned that the precipitation of particulate Li2CO3 will occur primarily through the following reaction:

[0141]

[0142] When the LiNO3-H2O liquid is combined with a sufficient amount of an aqueous liquid containing (NH4)2CO3 and / or with particulate (NH4)2CO3 (the amount of (NH4)2CO3 supplied exceeds the amount required to react substantially all of the LiNO3 aqueous solution), it is envisioned that the precipitation of particulate Li2CO3 will occur primarily through the following reaction:

[0143]

[0144] In any case, in a commercial context, this step is preferably performed at about 25 ≤ T (°C) ≤ about 80 and about 1 ≤ P (atm) ≤ about 10, and at the end, the resulting aqueous slurry containing Li2CO3, NH4NO3 and (NH4)2CO3 is transferred to a fifth reactor. Figure 3 Reactor No. 5 on the surface.

[0145] Step 17: The aqueous slurry containing Li₂CO₃, NH₄NO₃, and (NH₄)₂CO₃, transferred to reactor 5, is heated to substantially decompose all of the (NH₄)₂CO₃ aqueous solution. This is likely a result of the reaction (NH₄)₂CO₃(aq) → 2NH₃(g)↑ + CO₂(g)↑ + H₂O(liq), which in a commercial context is preferably induced at a pressure of about 60 ≤ T (°C) ≤ about 120 and close to 1 atm. To ensure maximum decomposition of the remaining (NH₄)₂CO₃ aqueous solution, the generated NH₃-CO₂ gas should be removed from the reactor upon formation.

[0146] Step 18: The aqueous slurry containing Li2CO3 and NH4NO3 produced in reactor No. 5 is fed into a mixer connected to the separator through a cooling unit.

[0147] Step 19: Stir and / or agitate the slurry in the mixer and then flow it into the separator, where it is separated into two fractions, one fraction being essentially particulate Li2CO3 and the other fraction being an aqueous liquid containing NH4NO3.

[0148] After separation, the Li₂CO₃ is slurried with preferably 30-70% by volume of water and then fed into a mixer-washer connected to the separator. Alternatively, it is then transferred to a third liquid mixer ( Figure 3 Before the No. 3 liquid mixer on the plate, the aqueous liquid containing NH4NO3 produced by separation is filtered.

[0149] Step 20: Stir and / or agitate the water-slurry-like granular Li2CO3 fed to the mixer-washer, and then separate it into fractions rich in Li2CO3 and rich in wash water.

[0150] At the end of this step, the wash water is sent to liquid mixer No. 3, where it is combined with the aqueous liquid containing NH4NO3 formed in step 19.

[0151] Step 21: Optionally, the moist Li2CO3 produced in step 20 is further processed to remove impurities, and then optionally heated to a temperature or temperature range between about 80°C and about 120°C to thoroughly dry the material.

[0152] Step 22: Optionally, the moist Li2CO3 generated in step 20 or the Li2CO3 optionally purified and / or dried in step 21 is converted into LiOH(aq) and / or solid LiOH·xH2O (x = 1, 2, 3 or 6).

[0153] The conversion of particulate Li₂CO₃ to, for example, particulate LiOH·H₂O can be achieved in several ways, one of which is particularly well known: through the following metathesis reaction:

[0154]

[0155] The hydration state of the LiOH·xH2O was then adjusted to produce LiOH·H2O.

[0156] Step 23: After a sufficient time in the No. 3 liquid mixer, the aqueous liquid containing NH4NO3 exiting from it is optionally heated to approximately 120°C as it flows back to the mixer. Figure 4 ).

[0157] Step 24: After the aqueous liquid containing NH4NO3 reaches the mixer, it comes into contact with an excess of granular MgO.

[0158] Optionally, the MgO is heated before entering the mixer, and at the end of this step, the resulting aqueous slurry containing MgO±Mg(OH)2 and NH4NO3 is conveyed to the sixth reactor. Figure 4 Reactor No. 6 on the surface.

[0159] (In the following text, it is assumed that in step 23, the aqueous liquid containing NH4NO3 is heated before reaching the mixer, and in step 24, the heated aqueous liquid containing NH4NO3 is brought into contact with heated MgO.)

[0160] Step 25: Stir and / or agitate the slurry in reactor 6 at approximately 120°C for a sufficient time to react substantially all of the NH4NO3 aqueous solution.

[0161] It is envisioned that the aqueous solution of NH4NO3 will disappear from the slurry through all three of the following reactions:

[0162]

[0163] and

[0164] 2NH4NO3(aq)+Mg(OH)2(s)→Mg(NO3)2(aq)+2H2O(liq)+2NH3(g)↑. (5c)

[0165] It is recommended to feed an excess of MgO into reactor 6 for two reasons: First, if the amount of MgO present is close to zero, the kinetics of reaction 5a will be significantly slowed down; second, some of the introduced MgO will combine with H2O to form Mg(OH)2 (reaction 5b). Mg(OH)2 is less reactive with NH4NO3 than MgO because Mg(OH)2 is stable in the presence of hot liquid H2O, while MgO is unstable.

[0166] At the end of this step, the resulting aqueous slurry containing Mg(NO3)2 and Mg(OH)2±MgO is transferred to a mixer connected to the separator (see step 28).

[0167] Step 26: Mix the NH3-CO2 gas generated in step 17, the NH3 gas leaving reactor 6, and the supplied CO2 gas in a gas mixer connected to the cooling unit.

[0168] To improve the processing efficiency in this invention, the composition of the NH3-CO2 gas should be suitable for consumption in step 16 or the next step.

[0169] Step 27: Optionally, the mixed NH3-CO2 gas leaving the cooling unit is transferred to the seventh reactor ( Figure 4 Reactor No. 7 on the surface is used to bring it into contact with water to produce a liquid containing (NH4)2CO3 dissolved in the water.

[0170] It is conceivable that an aqueous solution of (NH4)2CO3 will undergo the following reaction,

[0171]

[0172] It is formed at approximately 25 ≤ T (°C) ≤ approximately 80 and approximately 1 ≤ P (atm) ≤ approximately 10. Furthermore, optionally ( Figure 4 (Not shown above) After forming an aqueous liquid containing (NH4)2CO3, most of the water can be removed from the aqueous liquid containing (NH4)2CO3 to precipitate particulate (NH4)2CO3, which can then be separated from any remaining liquid.

[0173] At the end of this step, the aqueous liquid and / or particulate (NH4)2CO3 containing (NH4)2CO3 are returned to step 16.

[0174] Step 28: Stir and / or agitate the aqueous slurry containing Mg(NO3)2 and Mg(OH)2±MgO in the mixer immediately downstream of reactor 6, and then flow it into the separator, where it is separated into two fractions: one fraction is substantially fine-grained Mg(OH)2±residual MgO, and the other fraction is an aqueous liquid containing Mg(NO3)2.

[0175] At the end of this step: (i) the moist Mg(OH)₂±MgO is slurried with preferably about 30-70% by volume of water, and then sent to a mixer-washer connected to a separator; and (ii) the aqueous liquid containing Mg(NO₃)₂ is conveyed to a fourth liquid mixer ( Figure 4 (Liquid mixer #4 on top).

[0176] Step 29: Stir and / or agitate the Mg(OH)2±MgO aqueous slurry in the mixer-washer, and then separate it into fractions rich in Mg(OH)2±MgO and fractions rich in washing water.

[0177] At the end of this step, a portion of the moistened Mg(OH)2±MgO is fed into the first furnace (furnace No. 1, see...). Figure 5 In step 33), the washing water containing Mg(NO3)2 is sent to liquid mixer No. 4, where it is combined with the aqueous liquid containing Mg(NO3)2 formed in step 28.

[0178] Step 30: Send the aqueous liquid containing Mg(NO3)2 in the No. 4 liquid mixer to the evaporator.

[0179] Step 31: The aqueous liquid containing Mg(NO3)2 in the evaporator is heated to about 150°C, resulting in the production of molten Mg(NO3)2·xH2O and water vapor, as well as possible NOH gas.

[0180] The melting temperatures of Mg(NO3)2·6H2O and Mg(NO3)2·2H2O reported in the literature are 89℃ and 129℃, respectively. As the temperature rises above 129℃, the composition of the hydrated Mg(NO3)2 melt can be represented by the formula Mg(NO3)2·xH2O, where x < 2.0, and the value of x steadily decreases to << 2.0 with increasing temperature. Therefore, it is hypothesized that as the temperature rises above approximately 129℃ to approximately 330℃ (the latter being the approximate upper limit of the thermal stability of anhydrous Mg(NO3)2), the molten Mg(NO3)2·xH2O undergoes dehydration via the reaction Mg(NO3)2·xH2O(liq) → Mg(NO3)2·(xy)H2O(liq) + yH2O(g), where 0 ≤ y < 2.

[0181] At the end of this step, the generated NOH gas (if any) is transferred to a gas mixer (see [link]). Figure 5 (See step 37 above), and then feed the H2O-poor molten Mg(NO3)2·xH2O into the mixer (see step 32).

[0182] Step 32: In the mixer ( Figure 4 and Figure 5 In step 29, the Mg(NO3)2·xH2O (x < 2) liquid is contacted with a portion of the moist Mg(OH)2±MgO produced in step 29. After the two materials are mixed, the resulting Mg(NO3)2·xH2O + Mg(OH)2±MgO slurry is conveyed to the second furnace (furnace No. 2, see [link]). Figure 5 Step 34 above.

[0183] Step 33: The moist Mg(OH)₂±MgO in furnace No. 1 is heated to a temperature of up to about 600°C at about 1-2 atm, resulting in the production of MgO and water vapor through the following reaction:

[0184]

[0185] At the end of this step, the generated MgO is recycled back to step 24.

[0186] Step 34: The Mg(NO3)2·xH2O+Mg(OH)2±MgO slurry in furnace No. 2 is heated to a temperature of up to about 600°C at about 1-2 atm, resulting in the production of MgO and NOH gas containing NO2, O2 and H2O.

[0187] It is envisioned that the Mg(NO3)2·xH2O portion of the slurry will decompose via the following reaction:

[0188]

[0189] At the end of this step: (i) the generated MgO is slurried with liquid and fed to a mixer-washer connected to the separator; and (ii) the co-generated NOH gas containing NO2 and O2 is transferred to a gas mixer (see step 37). Preferably, the slurry fed to the mixer-washer will contain about 30-70% by volume of liquid. Furthermore, the liquid in the slurry should be a liquid in which MgO is substantially insoluble but impurities (e.g., alkali metal nitrates) are significantly soluble.

[0190] Step 35: Stir and / or agitate the slurry in the mixer-washer, and then separate it into fractions rich in MgO and rich in liquid.

[0191] Optionally, the MgO formed in this step may be further purified before being recycled back to step 24.

[0192] Step 36: Optionally, the liquid + impurities formed in step 35 are subjected to physical and / or chemical treatment in some way to separate it into two fractions, one fraction being a liquid containing very little dissolved, suspended and / or entrained solid material, and the other fraction mainly containing impurities that remained in the liquid prior to the physical and / or chemical treatment.

[0193] Optionally, the high-purity liquid is recycled back to step 35.

[0194] Step 37: The gas mixer receives the NOH gas removed from reactors 2 and 3 (steps 4 and 9a), the NOH gas generated in the evaporator (if any) (step 31), and the NOH- gas containing NO2, O2 and H2O formed in furnace 2 (step 34, and subsequently cooled), and mixes them there.

[0195] Optionally, some H2O may be intentionally condensed and separated from the gas mixture for reuse in the processing loop, and also optionally (i) some or all of the gas mixture may be returned to step 3 to replenish the significant portion of the HNO3 aqueous solution consumed in that step, and / or (ii) some or all of the gas mixture may be fed to the eighth reactor. Figure 5 Reactor No. 8 on the surface.

[0196] Step 38: Mix the NOH gas (if any) sent to reactor 8 with H2O to produce an aqueous HNO3 solution, which is then recycled back to step 3 to replenish the significant portion of the aqueous HNO3 solution consumed in that step.

[0197] At one or more points in the processing loop, NOH gas containing NO2 and O2 is mixed with water, which may produce HNO3 in two stages. The first stage involves the formation of a portion of HNO3 through the reaction 3NO2(g) + H2O(liq,g) → 2HNO3(aq,g) + NO(g). The second stage is characterized by the further synthesis of HNO3 through the reaction 4NO(g) + 3O2(g) + 2H2O(liq,g) → 4HNO3(aq,g).

[0198] Under any circumstances, the overall regeneration reaction of HNO3 is expected to be as follows:

[0199]

[0200] Step 39: Optionally, the water-washed leached particulate solids produced in step 7 are transferred to the ninth reactor (step 39), where they are mixed with aqueous / crystalline NaOH and / or aqueous / crystalline KOH to produce a (Na and / or K, Li, Al, Si-O)-H2O liquid.

[0201] Table 1 below shows the calculated tons of each substance consumed (C) and produced (P) in each of reactions 1, 2a, 3b, 4, 5a, 5b, 6, 7, 8 and 9 in a hypothetical embodiment, wherein all ten reactions are carried out to completion with the production of one ton of LiOH·H2O.

[0202] Table 1

[0203]

[0204] Table 2 below shows the calculated total amount (tons) of reactants and products in mass balance for each of reactions 1, 2a, 3b, 4, 5a, 5b, 6, 7, 8 and 9 in a hypothetical embodiment, wherein all ten reactions are carried out to completion in the production of one ton of LiOH·H2O.

[0205] Table 2

[0206]

Claims

1. A method for co-producing Li, Al, and Si-O materials from a hard rock source, wherein the hard rock source is in the form of a particulate concentrate of one or more lithium-bearing aluminum silicate minerals including spodumene, the method comprising: Provide a hard rock source in the form of a granular concentrate of one or more lithium aluminum silicate minerals including α-spodumene (step 1); The granular concentrate is calcined at high temperature to obtain a granular concentrate comprising β-spodumene (step 2); The granular concentrate containing β-spodumene is mixed with an aqueous nitric acid solution, and the resulting acidic mixture is then stirred or agitated in a first reactor at a temperature greater than or equal to (≥) about 120°C and a pressure greater than or equal to about 1 atm to achieve leaching of Li and Al (step 3). The acidic mixture is fed to a second reactor to extract NOH gas at a temperature greater than or equal to (≥) about 120°C to form a slurry in which NOH gas has been removed (step 4). The slurry is conveyed from the second reactor to a separator via a cooling unit, where it is separated into two fractions: one fraction is rich in leached β-spodumene particles, and the other fraction contains an aqueous liquid containing dissolved lithium nitrate (LiNO3) and dissolved aluminum nitrate (Al(NO3)3), wherein the fraction rich in leached β-spodumene particles contains some residual aqueous liquid containing LiNO3 and Al(NO3)3 formed during the Li-Al leaching process (steps 5 and 6). The fraction containing the aqueous liquid with dissolved LiNO3 and Al(NO3)3 is transferred to the first liquid mixer (steps 5, 6 and 8); Before or after the fraction rich in leached β-spodumene particles enters the mixer-washer, the fraction rich in leached β-spodumene particles is mixed with water of sufficient purity to form a water-slurry fraction rich in leached β-spodumene particles. This causes the water of sufficient purity to mix with the residual aqueous liquid containing LiNO3 and Al(NO3)3 formed during the Li-Al leaching process to form wash water containing LiNO3 and Al(NO3)3 (steps 5-7). The water-slurry-rich fraction containing leached β-spodumene particles is fed to a separator, in which the solid and liquid are separated into two fractions, one fraction containing leached β-spodumene particles and the other fraction containing wash water containing LiNO3 and Al(NO3)3 (step 7). The washing water is transferred to the first liquid mixer, where it is combined with the previously separated liquid containing LiNO3 and Al(NO3)3 that has entered the first liquid mixer to form an aqueous liquid containing LiNO3 and Al(NO3)3 (step 8). Optionally, the water-washed leached particulate solids are sent to an optional reactor in which the water-washed leached particulate solids are mixed with aqueous / crystalline sodium hydroxide (NaOH) and / or aqueous / crystalline potassium hydroxide (KOH) to produce (Na and / or K, Li, Al, Si-O)-H2O liquid (step 39). The liquid in the first liquid mixer is transferred to the third reactor (step 9a); and The aqueous liquid containing LiNO3 and Al(NO3)3 in the third reactor is treated to form an aluminum precipitate containing H2O ("Al(OH)3"), the aluminum precipitate containing amorphous Al-OH solid material or amorphous Al-OH solid material mixed with quasi-crystalline Al-OH, the treatment comprising one or more of the following: (i) heat treatment at a temperature sufficient to decompose Al(NO3)3 dissolved in the liquid (step 9a); (ii) reaction with an aqueous liquid containing dissolved NH4OH (step 9b); (iii) contact with an aqueous solution of (NH4)2CO3 (step 9c); and (iv) contact with solid (NH4)2CO3 (step 9c).

2. The method according to claim 1, wherein the particulate concentrate of one or more lithium-containing aluminum silicate minerals including α-spodumene is calcined at a temperature in the range of about 900°C to about 1200°C.

3. The method of claim 1, wherein if the ambient gas pressure in the second reactor is greater than about 1 atm, it is reduced to about 1 atm to form a slurry in which NOH has been removed.

4. The method according to claim 1, wherein the aqueous liquid containing LiNO3 and Al(NO3)3 in the third reactor is heat-treated (i) at a temperature of about 180°C (step 9a).

5. A method for co-producing Li, Al, and Si-O materials from a granular concentrate comprising α-spodumene, the method comprising: Provide a granular concentrate comprising α-type spodumene (step 1); The concentrate is calcined at high temperature to convert virtually all of the α-spodumene into the β(β) crystal form (step 2); Before or after entering the first reactor, the obtained β-spodumene concentrate is mixed with an aqueous solution of nitric acid (HNO3) and / or NOH gas with water (H2O) at a temperature of ≥ about 120°C and a pressure of about 1 atmosphere (1 atm) to about 10 atm to form an acidic mixture (step 3). In the first reactor, the acidic mixture contained therein is stirred or agitated at ≥120°C and ≥1 atm for a time sufficient to allow Li and Al to leach from β-spodumene (step 3); The resulting acidic mixture is fed to a second reactor to extract NOH gas, wherein, if necessary, the ambient gas pressure is reduced to approximately 1 atm to form a slurry that has substantially depleted the gas (steps 3 and 4). The slurry, which is essentially depleted of gas, is conveyed from the second reactor through a cooling unit to a separator, in which it is separated into two fractions: one fraction is rich in leached granular β-spodumene, and the other fraction contains an aqueous liquid containing dissolved lithium nitrate (LiNO3) and dissolved aluminum nitrate (Al(NO3)3) (steps 4 and 5). The aqueous liquid containing LiNO3 and Al(NO3)3 is transferred to the first liquid mixer (step 6); Before or after the fraction rich in leached β-spodumene particles enters the mixer-washer, the fraction rich in leached β-spodumene particles is mixed with water of sufficient purity to form a water-slurry fraction rich in leached β-spodumene particles. This causes the water of sufficient purity to mix with the residual aqueous liquid containing LiNO3 and Al(NO3)3 formed during the Li-Al leaching process, forming wash water containing dissolved LiNO3 and Al(NO3)3 (steps 5-7). The water-slurry-rich fraction containing leached β-spodumene particles is fed to a separator, in which the solid and liquid are separated into two fractions, one fraction containing leached β-spodumene particles and the other fraction containing wash water containing LiNO3 and Al(NO3)3 (step 7). The washing water is transferred to the first liquid mixer, where it is combined with the previously separated liquid containing LiNO3 and Al(NO3)3 that has entered the first liquid mixer to form an aqueous liquid containing LiNO3 and Al(NO3)3 (steps 7 and 8). Optionally, the water-washed leached particulate solids are sent to a ninth reactor, in which the water-washed leached particulate solids are mixed with (i) aqueous and / or crystalline sodium hydroxide (NaOH) and / or (ii) aqueous and / or crystalline potassium hydroxide (KOH) to produce a (Na and / or K, Li, Al, Si-O)-H2O liquid (step 39). The liquid in the first liquid mixer is transferred to the third reactor (step 8); The aqueous liquid containing LiNO3 and Al(NO3)3 in the third reactor is treated to form an aluminum precipitate containing H2O ("Al(OH)3"), the aluminum precipitate containing amorphous Al-OH solid material or amorphous Al-OH solid material mixed with quasi-crystalline Al-OH, the treatment comprising one or more of the following: (i) heat treatment at a temperature sufficient to decompose Al(NO3)3 dissolved in the liquid (step 9a); (ii) reaction with an aqueous liquid containing dissolved ammonium hydroxide NH4OH (step 9b); (iii) contact with an aqueous solution of ammonium carbonate (NH4)2CO3 (step 9c); and (iv) contact with solid (NH4)2CO3 (step 9c), provided that when only treatment (i) is used, the method step further includes cooling the slurry flowing out of the third reactor (step 10). The slurry is transferred to a mixer-separator, in which it is thoroughly stirred and / or agitated, and then separated into two fractions, one fraction containing aluminum precipitate formed in the third reactor, and the other fraction containing an aqueous liquid containing dissolved LiNO3 (step 11). The fraction containing the aqueous liquid with dissolved LiNO3 is transferred from the separator to the second liquid mixer (step 11); The slurry containing Al(OH)3 is mixed with water of sufficient purity, and the resulting slurry is fed to a mixer-washer, where it is stirred and / or agitated, and then separated into two fractions, one fraction rich in Al(OH)3 and the other fraction containing wash water containing dissolved LiNO3 (steps 11 and 12). The separated fraction containing wash water is conveyed to the second liquid mixer, where it is combined with the previously separated LiNO3-containing aqueous liquid transferred to the liquid mixer (step 12). The separated Al(OH)3 is converted into one or more Al-OH solids (step 13 and optional step 14); The combined aqueous liquid containing LiNO3 is transferred from the second liquid mixer to the fourth reactor (step 15); The combined aqueous liquid containing LiNO3 in the fourth reactor is mixed with NH3-CO2 gas and / or (NH4)2CO3 aqueous solution and / or solid (NH4)2CO3 to induce precipitation of solid Li2CO3 and simultaneously form NH4NO3 aqueous solution to form an aqueous slurry containing Li2CO3, NH4NO3 and (NH4)2CO3 (step 16). The aqueous slurry containing Li2CO3, NH4NO3 and (NH4)2CO3 is transferred from the fourth reactor to the fifth reactor, where it is heated to a temperature of about 100°C and subjected to a pressure of about 1 atm, resulting in the decomposition of substantially all remaining dissolved (NH4)2CO3, as demonstrated by the generation of NH3-CO2 exhaust gas, to form a slurry containing Li2CO3 and NH4NO3 (steps 16 and 17). The slurry containing Li2CO3 and NH4NO3 flowing out of the fifth reactor is cooled and then transferred to a mixer-separator, where it is stirred and / or agitated and then separated into two fractions, one fraction containing solid Li2CO3 formed in the fourth reactor and the other fraction containing an aqueous liquid containing NH4NO3 (steps 18 and 19). The aqueous liquid containing NH4NO3 is transferred to a third liquid mixer, and the fraction containing solid Li2CO3 is mixed with water of sufficient purity and then sent to a mixer-washer, where it is stirred and / or agitated, resulting in the formation and separation of wash water containing dissolved NH4NO3 in a separator connected to the mixer-washer (steps 19 and 20). The washing water containing NH4NO3 is transferred to the third liquid mixer, where it is combined with the previously separated aqueous liquid containing NH4NO3 that has entered the liquid mixer (step 20). Optionally, the wet Li2CO3 is conveyed from the separator to the dryer, and then the dried Li2CO3 is optionally transferred to a chemical conversion system, or the wet Li2CO3 is optionally transferred directly from the separator to the chemical conversion system, wherein the chemical conversion system is used to convert or react the Li2CO3 to produce an aqueous LiOH solution and / or solid LiOH·xH2O (x = 1, 2, 3 or 6) (steps 20-22); After leaving the third liquid mixer, the aqueous liquid containing NH4NO3 is optionally heated to a temperature of about 120°C as it flows toward an additional mixer, in which it is mixed with an excess of solid magnesium oxide (MgO), which is optionally preheated before being mixed with the aqueous liquid containing NH4NO3 to form a multiphase material (steps 23 and 24). The multiphase material is fed from the additional mixer to a sixth reactor, where its temperature is maintained at about 120°C, which results in the formation of an aqueous slurry of magnesium nitrate (Mg(NO3)2) and magnesium hydroxide (Mg(OH)2) and NH3 gas (steps 24 and 25). The NH3 is fed to a gas mixer, where it is mixed with supplied CO2 and NH3-CO2 gas generated in the fifth reactor (steps 25 and 26); The mixed NH3-CO2 gas is conveyed through a cooling unit and then recycled to precipitate additional Li2CO3 (step 16), or optionally sent to a seventh reactor, where it is mixed with H2O to form an aqueous (NH4)2CO3 solution, and the resulting aqueous liquid containing (NH4)2CO3 is then recycled to precipitate additional Li2CO3 (steps 26 and 27). The aqueous slurry produced in the sixth reactor, which contains Mg(NO3)2, Mg(OH)2 and H2O, is transferred to a mixer in which it is stirred and / or agitated and then separated into two fractions, one fraction containing solids rich in Mg(OH)2 and the other fraction being an aqueous liquid containing dissolved Mg(NO3)2 (steps 25 and 28). The aqueous liquid containing Mg(NO3)2 is conveyed to the fourth liquid mixer (step 28); The Mg(OH)2-rich solid is mixed with water, and the resulting slurry is then fed to a mixer-washer, where it is stirred and / or agitated, resulting in the formation of wash water containing dissolved Mg(NO3)2 (steps 28 and 29). The aqueous slurry containing Mg(OH)2 and Mg(NO3)2 is transferred to a separator, in which it is separated into two fractions: one fraction contains wet Mg(OH)2 plus any residual MgO, and the other fraction is wash water containing Mg(NO3)2 formed in the mixer-washer (step 29). The Mg(NO3)2-containing wash water is transferred to the fourth liquid mixer, where it is combined with the previously separated Mg(NO3)2-containing aqueous liquid that has entered the liquid mixer (step 29). A portion of the moist Mg(OH)2±MgO is transferred to the first furnace and heated to a maximum temperature of approximately 600°C, resulting in the production of MgO and water vapor. The MgO is then recycled back to step 24 (steps 29 and 33). An aqueous liquid containing Mg(NO3)2 is transferred from the fourth liquid mixer to an evaporator, where it is heated to a temperature of approximately 150°C to begin producing molten Mg(NO3)2·xH2O (x≤6), water vapor, and any generated NOH gas (steps 30 and 31). After leaving the evaporator, the H2O-poor Mg(NO3)2·xH2O liquid is conveyed to a mixer, where it is mixed with a portion of the previously generated (step 29) moist Mg(OH)2±MgO (steps 31 and 32). The Mg(NO3)2·xH2O-Mg(OH)2±MgO slurry is transferred from the mixer to a second furnace, where it is heated to a maximum temperature of about 600°C to form MgO plus solid impurities and NOH gas containing NO2 and O2 (steps 32 and 34). The MgO+ solid impurity is fed to a mixer-washer, in which the solid is slurried with a liquid in which MgO is substantially insoluble but the solid impurity is substantially soluble (steps 34 and 35). The slurry containing MgO is stirred or agitated and then sent to a separator, in which it is divided into two fractions, one fraction containing MgO, which is recycled back to step 24, and the other fraction is a liquid rich in impurities (step 35). Optionally, the liquid is processed in a certain way to separate it into two fractions, one fraction being a purified liquid and the other fraction containing impurities present in the liquid fraction formed in the separator (step 36); Optionally, the purified liquid can be recycled back to an earlier step, wherein the MgO+ solid impurities are slurried with the initially provided liquid (step 36); (i) the NOH gas removed from the second and third reactors, (ii) the NOH gas generated in the evaporator (if any), and (iii) the NOH gas containing NO2, O2 and H2O formed in the second furnace are fed to a gas mixer in which the individual gas streams are mixed (step 37). The NOH gas is fed from the gas mixer back to the first reactor and / or back to the eighth reactor, where it is mixed with H2O to produce an aqueous HNO3 solution, which is then fed back to the first reactor (step 38).

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