Ozonolytic precipitation of elements from aqueous streams.

Abstract

The disclosed method utilizes chemical-free ozone oxidation precipitation to recover dissolved metal ions (such as Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl) from aqueous solutions. The aqueous solutions can be mining or industrially impacted waters, or leachates obtained by treating primary or secondary sources of the elements. This process selectively separates these elements from the aqueous stream, which may then be utilized in a purification process. The target elements are recovered without chemical pH adjustment or the use of expensive oxidizing agents, thereby minimizing process costs, chemical consumption, and environmental footprint. In acidic and neutral solutions, these elements can be recovered as solid precipitates. In alkaline solutions, these elements are again recovered as solid precipitates.

Description

[Technical Field]

[0001] Related Applications This patent application claims priority to and benefit of U.S. Provisional Application No. US 63 / 392,330, entitled "OZONE OXIDATIVE PRECIPITATION OF ELEMENTS FROM AQUEOUS STREAMS," filed July 26, 2022, and incorporated herein by reference in its entirety.

[0002] Government Support Statement This invention was made with government support under Contract No. DE-FE0022594 awarded by the U.S. Department of Energy. The government has certain rights in this invention. [Background technology]

[0003] Cobalt (Co) and manganese (Mn) are some of the critical elements listed by the United States Department of the Interior, and the United States relies heavily on foreign sources for these elements. [1-4] Cobalt is a silvery-gray metal with a wide range of applications due to its unique properties, including ferromagnetism, hardness, wear resistance when alloyed with other metals, low thermal and electrical conductivity, high melting point, and multiple valences. In the United States, the majority of Co in 2021 (42%) was used in superalloys, primarily in aircraft gas turbine engines, followed by chemical applications (33%), metallurgical applications (16%), and the production of cemented carbides for cutting and wear-resistant applications (9%). [3] Mn is an iron-based metal primarily used in steel production due to its desulfurization and strong deoxidation capabilities. [5] It is also widely used in nonmetallic applications such as animal feed, brick coloring, dry cell batteries, and fertilizer production. [3, 4] Demand for Cobalt (Co) and Manganese (Mn) is expected to increase due to its application as a battery material in electric vehicles. Due to the increase in electric vehicle manufacturing, global demand for cobalt for battery applications is expected to increase by 60-70%, further increasing the need for cobalt products [1, 6].

[0004] Because primary resources of cobalt and manganese are limited within the United States, it is important to explore and extract these elements from viable secondary sources, such as waste streams associated with the mining and processing of coal and various ores. One of these waste streams is acid mine drainage (AMD), which results from the oxidation of pyrite components in mining and processing waste streams [7-11].

[0005] Oxidation of pyrite in coal and sulfide mineral waste streams in the presence of oxygen and water releases iron, sulfate, and hydrogen ions, producing an acidic wastewater (i.e., AMD). The mechanism of AMD formation involves oxidation of pyrite, oxidation of ferrous iron, and further oxidation of pyrite by ferric iron. FeS2+7 / 2O2+H2O→Fe 2+ +2SO4 2- +2H + (I) Fe 2+ +1 / 4O2+H + →Fe 3+ +1 / 2H2O (II) FeS2+14Fe 3+ +8H2O→15Fe 2+ +2SO4 2- +16H + (III)

[0006] This acidic wastewater promotes dissolution of elements (including major, trace, and critical elements) present in the host rock in the waste stream due to increased metal hydroxide solubility under highly acidic conditions [8, 15, 11]. AMD's acidity, high total dissolved solids content, and high electrical conductivity are environmental concerns. AMD must be treated to meet environmental regulations before being released into the environment

[16] . Treatment typically involves neutralizing the AMD and precipitating metals through chemical addition. Recovering critical elements while treating AMD increases the sustainability of the treatment process.

[0007] The primary methods for recovering cobalt (Co) and manganese (Mn) from aqueous streams include precipitation (i.e., hydroxide, carbonate, ammonia, sulfide, and oxidative precipitation), solvent extraction, electrochemical recovery, and ion exchange [17, 22]. Hydroxide precipitation is more efficient when combined with other methods for separating Mn from other metals in solution

[22] . Carbonate / ammonia precipitation is another practical method for recovering Mn from aqueous solutions. This method is more selective than hydroxide precipitation for Mn recovery when the pH is above 8.5. Sulfide precipitation (using H2S, Na2S, and (NH4)2S) and ion exchange effectively recover Mn and other metals, such as Co and Ni

[22] . Recovery of Mn as insoluble manganese oxides (mainly MnO2) from aqueous solutions of Zn, Co, and Ni has been reported by oxidative precipitation

[22] . SO2 / O2, ozone (O3), Caro's acid (H2SO5), peroxydisulfuric acid (H2S2O8), hypochlorite (ClO - Various oxidizing agents, such as chlorite, sodium persulfate (NaSO), and potassium permanganate (KMnO), are used to recover Mn and Co from aqueous solutions [27-28, 22]. Solvent extraction using di(2-ethylhexyl) phosphoric acid has also been reported to selectively separate Mn from aqueous solutions containing Co, Ni, and Mg. This method incurs a significant cost for the base required for neutralization

[22] . Resin-based ion exchange is another environmentally friendly and easy-to-control method for separating Mn from Co, Cu, Ni, Pb, and Fe. However, the capacity of resins is limited to the adsorption of certain metals, making this method more suitable for purification processes

[22] .

[0008] Chemical-free electrochemical methods also show promise for selectively recovering dissolved metals from aqueous solutions using oxidizing and neutralizing agents. Process efficiency and selectivity, desired product grade, and reagent costs are some of the determining factors in selecting an appropriate method for recovering metals (e.g., Co and Mn) from aqueous solutions [17, 22].

[0009] Several studies have been conducted on the selective recovery and purification of Co, Mn, and Ni from AMD sources. Considering the flow rate, required processing capacity, and chemical costs of AMD streams, precipitation offers a viable solution for recovering Co and Mn from AMD. Stepwise precipitation is an effective approach for selective element recovery because it sequentially precipitates elements and produces multiple precipitation products

[11] . However, precipitation of Co and Mn from AMD throughout the neutralization process is challenging because these elements do not precipitate near neutral pH. Precipitation throughout the conventional hydroxide AMD treatment process begins at a pH of approximately 9. Their high recovery rates require even higher pH (approximately 10.5). Oxidative precipitation using KMnO4 has reported high recovery rates (i.e., 99%) of Mn from AMD at pH 7. However, the economic drawback of this process is the high chemical cost. Therefore, new technological solutions are needed to develop a process for selectively recovering Co and Mn throughout the AMD treatment process without the need to increase the pH or use expensive materials. The precipitation behavior of elements during AMD processing depends mainly on the available ligands, solution chemistry, and element concentration

[11] . Summary of the Invention [Problem to be solved by the invention]

[0010] The disclosed system and method utilize chemical-free ozone oxidation precipitation to recover dissolved metal ions (e.g., Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and Tl) from aqueous solutions. The aqueous solutions can be mining or industrially impacted waters, or leachates obtained by treating primary or secondary sources of the elements. This process can selectively separate these elements from aqueous streams, allowing them to be utilized in purification processes. Advantages include a chemical-free process for recovering or separating elements from aqueous streams, which can be carried out over a wide range of original solution pH, from acidic to basic. Therefore, these elements can be recovered without chemical pH adjustment or the use of expensive oxidizing agents, thereby minimizing process costs, chemical consumption, and environmental footprint. In acidic and neutral solutions, these elements can be recovered as solid precipitates. In alkaline solutions, these elements are again recovered as solid precipitates, and ozone injection lowers the solution pH to ensure the final pH meets discharge requirements. [Means for solving the problem]

[0011] In some embodiments, the technology described herein relates to a method for removing / recovering dissolved metals from an aqueous solution, the method comprising the steps of: a) mixing ozone with the aqueous solution, thereby forming a metal precipitate; and b) removing the metal precipitate.

[0012] In some embodiments, the techniques described herein relate to methods further comprising: c) measuring the dissolved metal concentration, Eh, and pH in the aqueous solution; and d) repeating steps a) through c) until the measured dissolved metal concentration does not substantially change.

[0013] In some embodiments, the technology described herein relates to methods in which the aqueous solution comprises one or more dissolved metals Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0014] In some embodiments, the technology described herein relates to methods that include removing Fe, Al, Ca, Mg, Na, P, and / or rare earth elements before mixing ozone into an aqueous solution.

[0015] In some embodiments, the techniques described herein relate to methods that include removing Fe, Al, Ca, Mg, Na, P, and / or rare earth elements after step d).

[0016] In some aspects, the technology described herein relates to methods in which ozone is mixed into an aqueous solution at a predetermined flow rate.

[0017] In some embodiments, the technology described herein relates to a method in which the temperature of the aqueous solution during steps a) to d) is about 0 to 80°C.

[0018] In some embodiments, the technology described herein relates to methods in which the flow rate of ozone is varied as steps a)-c) are repeated.

[0019] In some embodiments, the technology described herein relates to methods in which the temperature of the aqueous solution is changed as steps a) to c) are repeated.

[0020] In some embodiments, the techniques described herein relate to methods in which steps a) through c) are repeated until the measured pH is about 8.0.

[0021] In some embodiments, the technology described herein relates to methods in which the pH of the aqueous solution is about 0-12.

[0022] In some embodiments, the technology described herein relates to methods where the aqueous solution comprises acid mine drainage, mine-impacted water, industrial wastewater, brine, geothermal brine, oil and gas produced water and wastewater, sludge leachate, e-waste recycling leachate, battery recycling leachate, solar panel recycling leachate, leachate / pregnant leachate obtained from processing ores or any other primary and secondary metal sources, or other aqueous wastes containing Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0023] In some embodiments, the technology described herein relates to methods in which the dissolved metal forms a precipitate, and the precipitate is a Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl precipitate.

[0024] In some embodiments, the techniques described herein relate to methods in which about 50-99% of the dissolved metals are recovered as precipitates from aqueous solutions.

[0025] In some aspects, the technology described herein relates to methods in which precipitates of dissolved metals are purified for secondary use.

[0026] In some embodiments, the technology described herein relates to a method of recovering dissolved metals from an acid mine drainage stream, the method comprising: a) removing Fe; b) removing Al; c) removing REEs; d) mixing ozone with the acid mine drainage stream at a rate to thereby form a dissolved metal precipitate; e) separating the dissolved metal precipitate; f) measuring the dissolved metal concentration and pH of the acid mine drainage stream; and g) repeating steps d) through f) until the measured dissolved metal concentration no longer changes.

[0027] In some embodiments, the technology described herein relates to methods in which Fe is removed by aeration or chemical precipitation.

[0028] In some embodiments, the technology described herein relates to methods in which Al is removed by chemical precipitation at low pH.

[0029] In some embodiments, the technology described herein relates to methods in which rare earth elements are removed by chemical precipitation at acidic or neutral pH.

[0030] In some embodiments, the technology described herein relates to a method for purifying or selectively removing dissolved metals from an aqueous solution, the method comprising: a) adjusting the pH of the aqueous solution to a predetermined pH; b) flowing ozone into the aqueous solution to achieve a predetermined redox potential and stirring the aqueous solution for a predetermined time to form a first solid metal fraction; c) separating the first solid metal fraction; and d) repeating steps a)-c) for a second or more solid metal fractions.

[0031] In some embodiments, the technology described herein relates to methods wherein one of the first, second or more solid metal fractions comprises dissolved metal, and the dissolved metal is one or more of Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0032] In some embodiments, the technology described herein relates to methods where the predetermined pH is in the range of about 0 to about 8.

[0033] In some embodiments, the technology described herein relates to methods wherein the aqueous solution is brine, wastewater from mining, oil and gas industries, or leachate obtained from ore processing, secondary source processing, waste processing, sludge processing, sediment processing, or recycling of e-waste, batteries, and solar panels.

[0034] In some embodiments, the technology described herein relates to methods in which about 50-99% of the metal is recovered from the first, second, or more solid metal fractions of the aqueous solution.

[0035] Those skilled in the art will understand that the drawings, described below, are for illustrative purposes only. [Brief explanation of the drawings]

[0036] [Figure 1] 1 shows a conceptual diagram of stepwise precipitation. [Figure 2A] Figure 1 shows Eh-pH diagrams for different ligands showing the major species for the Mn and Co-HO systems at 25 °C. [Figure 2B] Figure 1 shows Eh-pH diagrams for different ligands showing the major species for the Mn and Co-HO systems at 25 °C. [Figure 2C] Figure 1 shows Eh-pH diagrams for different ligands showing the major species for the Mn and Co-HO systems at 25 °C. [Figure 2D] Figure 1 shows Eh-pH diagrams for different ligands showing the major species for the Mn and Co-HO systems at 25 °C. [Figure 2E] Figure 1 shows Eh-pH diagrams for different ligands showing the major species for the Mn and Co-HO systems at 25 °C. [Figure 3] Figures 3A-3D show the cumulative recovery of Mn (Figure 3A) and Co (Figure 3B) and the grades of Mn (Figure 3C) and Co (Figure 3D) in the stepwise precipitation of AMD using various chemicals. [Figure 4] Figures 4A-4C show the cumulative recovery of Mn (Figure 4A) and Co (Figure 4B) achieved using various oxidizing agents in AMD staged precipitation, where Stages I and II represent the two-stage carbonate precipitation process for Al and REE removal at pH values ​​of 5 and 7, respectively, and Stage III shows oxidative precipitation for Co and Mn recovery at pH 7, along with the corresponding grades of various elements in the precipitates at this stage (Figure 4C). [Figure 5]1 shows the progress of oxidative precipitation by ozone injection into 20 L of AMD at stage III (pH 7) as a function of time. [Figure 6] Results are presented for a stepwise precipitation process developed for AMD treatment for Fe removal and selective recovery of Al, REEs, Co, and Mn. [Figure 7] Figures 7A-7D show the XRD pattern (Figure 7A), FT-IR peaks (Figure 7B), EDS peaks (Figure 7C), and SEM micrograph (Figure 7D) of the precipitated solid from oxidizing ozone precipitation. [Figure 8] FIG. 8 shows the response surface plot of Co recovery as a function of process parameters. [Figure 9] FIG. 9 shows the response surface plot of Mn recovery as a function of key process parameters. [Figure 10] 10A-10D show the Co precipitation rate versus temperature. [Figure 11] 11A-11E show Mn precipitation rate versus temperature. [Figure 12A] The activation energy of Co solution at two different times (60 seconds and 30 minutes) is shown. [Figure 12B] The activation energy of Mn solution at two different times (60 seconds and 30 minutes) is shown. [Figure 13] 13A-13D show the Co-Mn precipitation rate versus agitation speed. [Figure 14] 14A-14F show the Co-Mn precipitation rate versus initial ion concentration. [Figure 15] 15A-15D show Co-Mn precipitation rate versus flow rate. [Figures 16A-16F] 16A-16F show Eh-pH diagrams for different elements showing the major species in the H2O system at 25 °C. [Figures 16G-16L] Figures 16G-16L show Eh-pH diagrams for different elements showing the major species in the HO system at 25 °C. [Figures 16M-16R] Figures 16M-16R show Eh-pH diagrams for different elements showing the major species in the HO system at 25 °C. [Figure 17]Selective recovery of key elements by ORP control in Co-Mn stock solution is shown. [Figure 18] Selective recovery of key elements by ORP control in AMD / sludge leachate is demonstrated. [Figure 19] Selective recovery of key elements from e-waste leachate using ozone oxidation precipitation by controlling ORP is demonstrated. DETAILED DESCRIPTION OF THE INVENTION

[0037] Several references, which may include various patents, patent applications, and publications, are cited in the reference list and discussed in the disclosure provided herein. Citation and / or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is "prior art" to any aspect of the present disclosure described herein. For purposes of notation, "[n]" corresponds to the nth reference in the list. All references cited and discussed herein are incorporated herein by reference in their entirety and to the same extent as if each reference were incorporated by reference separately.

[0038] Although exemplary embodiments of the present disclosure have been described in detail herein, in some instances, it should be understood that other embodiments are contemplated. Accordingly, the present disclosure is not intended to be limited in scope to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0039] It should also be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When such a range is expressed, other exemplary embodiments include from the one particular value and / or to the other particular value.

[0040] "Comprising" or "containing" or "including" means that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, or method steps, even if other such compounds, materials, particles, or method steps have the same function as the named one.

[0041] In describing exemplary embodiments, technical terminology will be used for the sake of clarity. Each term is intended to accord the broadest meaning of that term, as understood by those skilled in the art, and to include all technical equivalents that operate in a similar manner to achieve a similar purpose. It should also be understood that the reference to one or more steps of a method does not exclude the presence of additional or intervening method steps between those explicitly identified steps. Method steps may be performed in a different order than described herein without departing from the scope of the present disclosure. Similarly, it should also be understood that the reference to one or more components in a device or system does not exclude the presence of additional or intervening components between those explicitly identified components.

[0042] As used herein, the expressions "ambient temperature" and "room temperature" are art-recognized and generally refer to temperatures from about 20°C to about 35°C.

[0043] As used herein, the term "composition" is intended to encompass a product comprising the specified ingredients in the specified amounts, and any product resulting, directly or indirectly, from combining the specified ingredients in the specified amounts.

[0044] References in the specification and concluding claims to parts by weight of a particular element or component in a composition indicate the weight relationship between the element or component and any other element or component in the composition or product for which the parts by weight are expressed. Thus, in a mixture containing 2 parts by weight of component X and 5 parts by weight of component Y, X and Y are present in a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are included in the mixture.

[0045] Weight percent (wt %) of a component is based on the total weight of the formulation or composition in which the component is included, unless specifically stated to the contrary.

[0046] When an element is referred to as being "connected" or "coupled" to another element, it will be understood that it is directly connected or coupled to the other element, or that intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other terms used to describe relationships between elements or layers should be interpreted similarly (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," "on" vs. "directly on").

[0047] Although the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in each testing measurement. Furthermore, when different ranges of values ​​are set forth herein, it is contemplated that any combination of these values, including the recited values, may be used. Furthermore, ranges herein can be expressed as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment includes from one particular value and / or to the other particular value.

[0048] Similarly, when values ​​are expressed as approximations, by use of the antecedent word "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. Unless otherwise specified, the term "about" will mean within 5% (e.g., within 2% or 1%) of the particular value modified by the term "about."

[0049] Similarly, numerical ranges recited herein include subranges subsumed within those ranges by endpoint (e.g., 1 to 5 includes 1 to 1.5, 1.5 to 2, 2 to 2.75, 2.75 to 3, 3 to 3.90, 3.90 to 4, 4 to 4.24, 4.24 to 5, 2 to 5, 3 to 5, 1 to 4, 2 to 4). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term "about."

[0050] It should be understood that terms such as “first,” “second,” and the like may be used herein to describe various elements, components, regions, layers, and / or sections. It should be understood that these elements, components, regions, layers, and / or sections are not intended to be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section described below could be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0051] As used herein, the term "substantially" means that the subsequently described events or circumstances occur exactly, or that the subsequently described events or circumstances occur generally, typically, or approximately.

[0052] Additionally, the term "substantially" can, in some embodiments, refer to at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or about 100% of a described property, component, composition, or other term used to characterize or quantify the amount of substantially.

[0053] In other aspects, as used herein, the term "substantially free" is intended to refer to a composition that is substantially absent, or when used in the context of a component of a composition, an amount of less than about 1 wt. %, e.g., less than about 0.5 wt. %, less than about 0.1 wt. %, less than about 0.05 wt. %, or less than about 0.01 wt. % of the recited material, based on the total weight of the composition.

[0054] As used herein, the terms "substantially identical reference composition," "substantially identical reference article," or "substantially identical reference electrochemical cell" refer to a reference composition, article, or electrochemical cell that includes substantially identical components without the inventive elements present. In another exemplary embodiment, the term "substantially," e.g., in the context of "substantially identical reference composition," "substantially identical reference article," or "substantially identical reference electrochemical cell," refers to a reference composition, article, or electrochemical cell that includes substantially identical components, with the inventive elements substituted for elements common in the art.

[0055] The systems and methods of the appended claims are not limited in scope by the specific systems and methods described herein, but are intended as illustrations of some aspects of the claims. Any systems and methods that are functionally equivalent are intended to be within the scope of the claims. Various modifications of the systems and methods in addition to those shown and described herein are intended to be within the scope of the appended claims. Furthermore, only certain representative system and method steps disclosed herein are specifically recited, but other system and method step combinations are intended to be within the scope of the appended claims even if not specifically recited. Thus, combinations of steps, elements, components, or ingredients may or may not be explicitly recited herein, but other combinations of steps, elements, components, and ingredients are included even if not explicitly recited.

[0056] While several embodiments of the present invention are disclosed in the foregoing specification, it will be understood that many modifications and other embodiments of the present invention will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. It is therefore to be understood that the invention is not limited to the specific embodiments disclosed herein, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, certain terms used in this specification and in the following claims are used in a generic and descriptive sense only, and not for the purpose of limiting the described invention or the following claims.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed invention belongs. Publications cited herein and the material for which they are cited are specifically incorporated herein by reference.

[0058] Although aspects may be described and claimed in particular statutory classes, such as system statutory classes, this is for convenience only, and one of ordinary skill in the art will understand that each aspect of the present invention may be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring its steps to be performed in a particular order. Accordingly, no order is intended to be inferred in any method claim unless the claims or specification specifically state that the steps are to be limited to a particular order. This holds for any possible implicit basis for interpretation, including the obvious meaning derived from the arrangement of steps or operational flow, grammatical construction or punctuation, or logical matters regarding the number or type of aspects described in the specification.

[0059] In view of the processes and compositions described, the following particularly detailed embodiments of the invention are set forth. However, these specifically recited embodiments should not be construed as having any limiting effect on any different claims containing different or more general teachings set forth herein, or that the "particular" embodiments are limited in any way other than by the inherent meaning of the words and formulae literally used therein.

[0060] The present invention may be understood more readily by reference to the detailed description of various aspects of the invention and the examples contained therein, as well as the drawings and accompanying description.

[0061] In an exemplary embodiment, a method for removing dissolved metals from an aqueous solution is described. The method may include: a) mixing ozone with the aqueous solution, thereby forming a dissolved metal precipitate; and then b) removing the dissolved metal precipitate from the aqueous solution. Further, the method may include c) measuring the dissolved metal concentration, oxidation-reduction potential (Eh), and pH of the aqueous solution. The method may include d) repeating steps a) through c) until the measured dissolved metal concentration remains substantially unchanged.

[0062] In some embodiments, the aqueous solution may contain one or more dissolved metals Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl. In particular, the aqueous solution may contain dissolved Co and Mn.

[0063] In some embodiments, the method may include removing Fe, Al, Ca, Mg, Na, P, and / or rare earth elements before mixing ozone with the aqueous solution. In other embodiments, the method may include removing Fe, Al, Ca, Mg, Na, P, and / or rare earth elements (REEs) after step d).

[0064] In some embodiments, the method may include mixing ozone into the aqueous solution at a predetermined flow rate. The flow rate may be determined by the engineering parameters of the processing system. For example, a processing system for a small scale (about 1-100 L of aqueous solution) may use an ozone flow rate of about 500-1100 mL / min. In particular, a processing system containing about 10 L, about 20 L, about 30 L, about 40 L, about 50 L, about 60 L, about 70 L, about 80 L, or about 90 L of aqueous solution may be supplied with an ozone flow rate of about 600 mL / min, about 700 mL / min, about 800 mL / min, about 900 mL / min, or about 1000 mL / min. One skilled in the art may use techniques known in the art to determine the optimal flow rate. In some embodiments, the ozone flow rate may be varied throughout the process, particularly after removing dissolved metal precipitates.

[0065] In some embodiments, the aqueous solution may be at a temperature of about 0° C. to about 80° C. Throughout various steps of the method, the temperature may be varied to optimize desired dissolved metal precipitation, examples of which are disclosed in the Examples section. In particular, the aqueous solution may be at a temperature of about 10° C., about 20° C., about 30° C., about 40° C., about 50° C., about 60° C., or about 70° C. In some embodiments, the temperature of the aqueous solution may be varied throughout the method, particularly after removing dissolved metal precipitates.

[0066] In some embodiments, the aqueous solution for treatment may have a pH of about 0 to about 12. In particular, the pH of the aqueous system may be about 1, about 2, about 3, about 4, about 5, about 6, or about 7 before treatment, and then steps a) through c) of the method may be repeated until the measured pH is about 8. In another example, the pH of the aqueous system may be about 11, about 10, or about 9 before treatment, and then steps a) through c) of the method may be repeated.

[0067] In various embodiments, the aqueous solution may include acid mine drainage, mine-affected water, industrial wastewater, brine, geothermal brine, oil and gas produced water and wastewater, sludge leachate, e-waste recycling leachate, battery recycling leachate, solar panel recycling leachate, leachate / pregnant leachate obtained from processing ores or any other primary and secondary metal sources, or other aqueous waste products containing Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl. In some embodiments, the aqueous solution may be an aqueous stream.

[0068] In some embodiments, the dissolved metal may form a precipitate, which may be a precipitate of Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl. Using the above method, approximately 50-99% of the dissolved metal is recovered as a precipitate from the aqueous solution. Specifically, approximately 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, and / or 95% of the dissolved metal is recovered as a precipitate from the aqueous solution. After recovery, the dissolved metal precipitate may be purified for secondary use.

[0069] In another exemplary embodiment, a method for recovering elements from an acid mine drainage stream is described. The method may include the steps of: a') removing Fe; b') removing Al; c') removing REEs; d') mixing ozone with the acid mine drainage stream at a rate to form a precipitate of dissolved metals; e') separating the precipitate of dissolved metals; f') measuring the dissolved metal concentrations and pH of the acid mine drainage sample; and g') repeating steps d') through f') until the measured dissolved metal concentrations no longer change.

[0070] In some embodiments of the method for recovering elements from acid mine drainage streams, Fe may be removed by aeration or chemical precipitation. In other embodiments, Al may be removed by chemical precipitation at low pH. In still other embodiments, REEs may be removed by chemical precipitation at acidic or neutral pH.

[0071] In another exemplary embodiment, a method for purifying or selectively removing metals from an aqueous solution is described. The method may include: a'') adjusting the pH of the aqueous solution to a predetermined pH; b'') flowing ozone into the aqueous solution to achieve a predetermined redox potential and stirring the aqueous solution for a predetermined time to form a first solid metal fraction; c'') separating the first solid metal fraction; and d'') repeating steps a'')-c'') for a second or more solid metal fractions.

[0072] In some embodiments, one of the first, second, or more solid metal fractions can include dissolved metals, and the dissolved metals in the aqueous solution can be one or more of Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, and / or Tl. In other embodiments, the predetermined pH is in the range of about 0 to about 8. In particular, the predetermined pH can be about 1, about 2, about 3, about 4, about 5, about 6, or about 7.

[0073] In other embodiments, the aqueous solution may be brine, wastewater from mining, oil and gas industries, or leachate obtained from ore processing, secondary source processing, waste processing, sludge processing, sediment processing, or recycling of e-waste, batteries, and solar panels.

[0074] Using the above methods, about 50-99% of the dissolved metal is recovered from the aqueous solution as a precipitate, particularly about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, and / or about 95% of the dissolved metal is recovered from the aqueous solution as a precipitate. [Example]

[0075] Example 1. Chemical-free process using ozone oxidation precipitation for the recovery of cobalt and manganese from acid mine drainage.

[0076] Samples and Materials. Representative samples of AMD (800 L) and sludge (800 L of decanted, filtered, and dried slurry) were collected from an AMD treatment facility operated by the Pennsylvania Department of Environmental Protection (PADEP). AMD and sludge samples were collected at the feed point to the AMD treatment facility during sludge pumping operations and the sludge pond, respectively. The AMD stream originating from the Lower Kittanning coal seam had a measured pH of 3.5. The elemental composition of the AMD and sludge samples is shown in Table 1.

[0077] [Table 1]

[0078] The relatively high content of key elements in AMD (e.g., 45.6 ppm Al, 0.5 ppm rare earth elements (REEs), 0.9 ppm Co, and 41.8 ppm Mn) indicates that AMD is a highly valuable secondary resource of multiple key elements. The high concentrations of these elements in the associated sludge material (e.g., 4.5% Al, 553 ppm REEs, 1180 ppm Co, and 3.1% Mn) indicate that precipitation is a viable method for enriching these elements from AMD. Therefore, a modification of the precipitation method (i.e., stepwise precipitation) was considered to selectively recover these elements from AMD while addressing environmental concerns. In the current example, NaOH, Na2CO3, Na2HPO4, NH4OH, (NH4)2SO4, Na2SO4, NH4HCO3, KMnO4, Na2S2O8, and O3 were used to study the effects of various ligands and oxidants on the precipitation behavior of Co and Mn. All reagents were ACS grade. For oxidative ozone precipitation, a 1000 mg / h ozone generator (T-king Enaly model) with air as input gas was used to supply ozone. The volumetric flow rate of ozone injected into the system was controlled by a flow meter.

[0079] Stepwise precipitation. A two-stage carbonate precipitation process for selectively recovering Al and REEs from AMD was previously disclosed

[34] . In the previously described process, after airing and removing Fe, 90% of Al was recovered in the first step, and 85% of REEs were recovered in the second step, achieving a very high REE concentration of 1.6% using carbonate ligands (i.e., CO2 or Na2CO3). Details of the two-stage precipitation process have been described elsewhere [11, 34], and those conditions served as a baseline for the currently described system and method. In the current example, a third precipitation stage was evaluated to recover Co and Mn. Each experiment was conducted using a 20 L AMD sample that was first filtered to remove algae and coarse particles.

[0080] Ligand Precipitation. The effect of various ligands on the precipitation of these elements was first studied using a stepwise precipitation process. Different chemicals, including NaOH, Na2CO3, Na2HPO4, NH4HCO3, NH4OH, (NH4)2SO4, and Na2S2O8, were used to investigate the precipitation of hydroxides, carbonates, ammonia, and sulfates. After aeration and iron removal (approximately pH 4), the pH of the solution was raised to the target pH value (i.e., 5, 7, 8, or 9) for each stage of ligand precipitation. For chemicals that did not increase the pH (i.e., Na2HPO4, (NH4)2SO4, and Na2S2O8), NaOH was used as a pH modifier after adding a fixed dosage of the chemical at each stage. This dosage was determined based on the amount of ligand required to form the metal complex, if thermodynamically possible, while maintaining the ionic strength of the relevant solution at the same order of magnitude as the other chemicals. The concentrations of the chemicals and pH modifiers used in the precipitation stages are listed in Table 2. At each target pH, the solution was stirred for 24 hours to provide adequate aging time for precipitate nucleation and growth [35, 36]. The precipitates were then collected by filtering the solution through a 0.45 μm hydrophilic polyvinylidene fluoride (PVDF) filter (Durapore® membrane - Millipore - Sigma) in a high-pressure (700 kPa) filtration apparatus. Finally, the precipitates collected at each stage were dried at low temperature (70 °C) in a vacuum oven (-70 kPa) and stored in a sealed container for characterization.

[0081] [Table 2]

[0082] Oxidative Precipitation. Oxidative precipitation of Co and Mn was studied using KMnO4, Na2S2O8, and O3, which are common oxidants used in Co and Mn separation processes [27, 37-41]. Oxidative precipitation was performed on neutralized AMD (i.e., pH 7) obtained from a two-stage carbonate precipitation process. The neutralized AMD was then oxidized by adding oxidants (KMnO4 and Na2S2O8) or injecting ozone (O3) into the solution at a rate of 500 mL / min, generating 1 g / h of ozone in the system. With stirring, oxidation was continued through the stepwise addition of chemicals (i.e., 79 mg / L of KMnO4 and 712 mg / L of Na2S2O8) or ozone injection (8 h) until no Co or Mn precipitates remained. The concentrations in the solution were confirmed to remain constant over time, and the solution pH was maintained at approximately 7.0. The precipitate from each stage was collected by filtration, as described in the following section. The experimental setup is shown in Figure 1.

[0083] Analytical Procedures. Elemental concentrations of AMD, sludge, precipitate, and solution were measured using an Agilent 7900 inductively coupled plasma mass spectrometer (ICP-MS). Prior to ICP analysis, the sludge and precipitate were acid-digested with aqua regia. Analyses were performed in duplicate using ICP-MS standard solutions (ICP-MS-68B-A-100, HPS) with known elemental concentrations for quality control. The Co-Mn precipitate was thoroughly characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS). Elemental recovery values ​​were calculated based on element concentrations with reference to Equation 1, where C i is the concentration (mg / L) of the target element in the solution after filtration at each stage, and C f is the concentration of the same element in the AMD supply.

[0084]

number

[0085] Solution chemistry. Ligand (NH4 + , SO4 2- , PO4 3- , O.H. - , CO3 2- Pourbay diagrams for Co and Mn were constructed using the Pourbay diagram. For solution chemistry studies, the concentrations of Co and Mn were similar to those in the AMD samples, and the ligand concentrations were chosen based on their consumption during precipitation experiments (shown in Table 2).

[0086] Eh-pH diagram. Pourbay diagrams for Co and Mn systems using various ligands are shown in Figure 2A-2E. The total concentrations of dissolved Co and Mn were fixed at constant values ​​of 0.1 mM and 1 mM, respectively. The ligand concentrations for each system were set according to those used in the precipitation experiments (i.e., Table 2).

[0087] Based on the Pourbay diagram for Mn, as shown in Figures 2A–2E, Mn generally exists as an ion in solution under low pH and Eh conditions, and any change from these conditions causes Mn precipitation. In highly acidic environments, increasing Eh (using an oxidizing agent as an example) precipitates Mn in the form of MnO2. Increasing Eh at high pH values ​​also leads to the development of higher-grade Mn formations such as Mn2O3 and Mn3O4 (in the narrow intermediate oxidation potential region between MnO2 and Mn3O4), resulting in Mn precipitation. However, at relatively low Eh values, Mn precipitation requires relatively high pH values, depending on the type of ligand. This is consistent with previous studies that found that the precipitation efficiency of Mn increases as the solution pH increases when using various ligands [27, 42].

[0088] In hydroxide precipitation (Figure 2A), Mn exists as an ion in solution below pH 9, and above pH 9, Mn(OH)2 is formed. + Similar results were observed for the formation of Mn compounds in the presence of ligands (Figure 2B). With carbonate ligands, the formation of MnCO3 begins at lower pH values ​​(e.g., around 6) (Figure 2C). The results also show that PO4 3-It was shown that Mn could precipitate in the form of MnHPO4 at low pH and Eh values ​​in the presence of SO4 in acidic solutions (Fig. 2D). 2- The presence of Mn 2+ The ion pair (MnSO4 0 ), whereas Mn precipitation occurs at pH values ​​above 8 and appears in the form of hydroxide or oxide, as shown in Figure 2E.

[0089] Like Mn, Co generally exists as an ion in aqueous solution under low pH and Eh conditions (see Figures 2A-2E). Its precipitation occurs only at pH values ​​around 8.5, typically in the hydroxide form. Increasing the Eh of the solution also allows the element to precipitate at low pH values ​​(>6.5). The Poole Bay diagram shows that increasing the pH above 8.5 or adding OH - , NH4 + , PO4 3- By increasing Eh in the presence of ligand, Co precipitates as Co(OH)2 and Co(OH)3 (Figure 2A, 2B, 2D). 2- The Pourbay diagram of the ligand showed the precipitation of Co as CoCO3 in the pH range of 7–9, followed by Co(OH)2 at pH values ​​above 9 (Figure 2C). 2- In the presence of ligands, Co (as well as Mn) also reacts with CoSO4 at a pH of approximately 2. - It was confirmed that the elements remain in solution as hydroxides (Figure 2E). By increasing the pH, the elements precipitate in the form of hydroxides or oxides. The hydroxides of Co and Mn are easily oxidized to their higher-value oxide hydroxides (i.e., M(III)OOH, where M represents the metal) in the presence of air

[43] . Precipitation of CoOOH has also been reported in the literature [44, 40, 41].

[0090] Effect of different ligands on the stepwise precipitation of Co-Mn. OH on the precipitation of Co and Mn from AMD using different chemicals. - , SO4 2- , NH4 + , CO3 2- , and PO4 3-The effect of the ligand was studied through stepwise precipitation experiments. - NaOH and Ca(OH)2, which provide ions, are the most commonly used chemicals in the AMD activation treatment process. The general reaction for metal hydroxide precipitation can be expressed as Reaction IV, where M represents the metal and n represents the metal valence. The equilibrium constant for this reaction is K s It can be expressed by Equation 2, where is the solubility product.

[0091]

number

[0092]

number

[0093] Based on the hydroxide solubility diagrams for metals, Fe 3+ , Al 3+ , Pb 2+ , Cu 2+ , followed by Zn 2+ Mn is precipitated by hydroxide precipitation due to differences in solubility. 2+ However, it is expected that Co 2+ and Ni 2+ Mn 2+ It is difficult to separate Mn from aqueous solutions by hydroxide precipitation

[23] . Therefore, hydroxide precipitation is not an efficient approach for selectively recovering Mn from aqueous solutions, and this approach is only practical when combined with other separation techniques [22, 23].

[0094] Na2CO3 is another chemical used in AMD treatment, and in this study, CO3 2- Carbonate precipitation, especially in combination with ammonia, is an efficient method for recovering Mn and Co. However, during the chemical precipitation of MnCO3 (i.e., reaction V), Mg 2+ and Ca 2+ Mn ions in sulfate solutions (e.g., AMD) 2+Separating Mn from Mn ions is often difficult due to their similar chemical properties [25, 26]. Depending on temperature, pH, and Mg / Ca ratio, these two elements can co-precipitate with Mn, reducing the selectivity of the precipitation process and the grade of the Mn product

[26] .

[0095]

number

[0096] Ligands and metal ions (SO4 2- ) affect the pH of elemental precipitation. This is because metal ions react with SO4 2- Combines with anions, CoSO4 - , NiSO4 - , FeSO4 - (The corresponding log(K) is in the range of 1 to 2.5, i.e., reactions VI to VIII.) 2+ There is a large difference in the equilibrium constants for the precipitation of Ni(OH)2 from NiSO4 - (i.e., reactions IX and X) are more favorable (especially SO4 2- In the presence of , the solubility constant is small and therefore the precipitation pH is high.

[43] Similar reactions can occur when Co and Mn ions are in solution. Ni 2+ +SO4 2- =NiSO4logK=2.29 (VI) Co 2+ +SO4 2- =CoSO4logK=2.42 (VII) Fe 3+ +SO4 2- =FeSO4 + log K=1.94 (VIII) Ni 2+ +H2O=Ni(OH)2+2H + logK=-12.8 (IX) NiSO4+H2O=Ni(OH)2+2H + +SO4 2- logK=-15.1 (X)

[0097] Ammonia is also used in AMD treatment

[45] . Due to its low toxicity, low cost, and ease of regeneration via evaporation, it is widely used as an efficient leaching agent in various water metal treatment processes. Ammonia-ammonium carbonate solutions have been used to selectively recover cobalt from mixed Co-Mn aqueous solutions. Cobalt amine complexes are more stable than manganese ones and can be rapidly oxidized to cobalt(III) hexaamine salts. The hexaamine complex from the cobalt(II) ion is converted to Co. 2+ It is produced when excess ammonia is introduced into a solution containing ions [46-48, 24]. In this example, the effect of ammonia on the precipitation of Co and Mn was investigated using NH4OH and NH4HCO3. Additionally, (NH4)2SO4, Na2SO4, and NaHPO4 were also utilized, and NH4 + / NH3, SO4 2- , PO4 3- The effects of anions on the precipitation of Co and Mn were investigated.

[0098] The precipitation behavior of cations in solution is greatly influenced by their interactions with other ions in the aqueous environment and the properties of the elements [33, 49, 11]. In precipitation experiments using various ligands, the cumulative recoveries and grades of Co and Mn at different stages (i.e., Stage I at pH 5, Stage II at pH 7, and Stage III at pH 9) are shown in Figures 3A-3D. The results showed that under low Eh conditions (i.e., 0.3 V) in AMD, precipitation of Co and Mn began at high pH values ​​(≥ 9), regardless of the ligand in solution, but PO4 3- In the case of the ligands, elements began to precipitate significantly at pH 8. NaOH recovered less than 20% of Mn and only 61% of Co at pH 9. These results are consistent with the corresponding Poole-Bay diagrams (Figures 2A-2E), which show that a pH of 10 is required for hydroxide precipitation of Mn. Carbonate ligands provided by Na2CO3 or NH4HCO3 were ineffective, recovering less than 20% of Co and Mn. Previous work by Lin et al.

[25] showed that Mn in carbonate precipitation 2+ , Mg2+ , and Ca 2+ It has been shown that the precipitation of Co and Mn is different from hydroxide precipitation. The precipitation probability of these elements at a given pH follows the following order: MnCO3 > CaCO3 > MgCO3 > Mn(OH)2 > Mg(OH)2 > Ca(OH)2. Therefore, based on thermodynamics, carbonate precipitation is more feasible for separating Mn from Mg and Ca than hydroxide precipitation, indicating a higher selectivity for Mn over Ca and Mg

[25] . However, in the current example, the recovery values ​​of Co and Mn did not occur at low precipitation pH and were low even at pH 9. This is likely due to the low concentration of Mn-Co in solution, and the precipitation rate of Co-Mn is significantly affected by the initial concentration of the metal ions.

[0099] Provided by Na2HPO4, NH4OH, (NH4)2SO4, Na2SO4, PO4 3- , NH4 + , SO4 2- Other ligands, including PO4, achieved high recoveries of Co and Mn (i.e., over 87%) at pH 9. 3- The high recovery values ​​using the ligands are consistent with the corresponding Pourbay diagram (Fig. 2D), which is due to the low Gibbs free energy of the corresponding phosphate formation

[50] .

[0100] When ammonia is introduced into the Mn solution, Mn(NH3) n+ Cationic complexes of manganese with ammonia of the type NH4 are formed. Precipitation of Co and Mn in the presence of ammonium and sulfate ligands indicates supersaturation of the corresponding complexes of these elements. + and SO4 2- The ligand precipitates Co and Mn as metal hydroxides (Figure 2B and Figure 2E). Moderate concentrations of ammonium salts satisfy the stoichiometric requirement of ammonia for precipitating Mn hydroxide in the absence of oxidation. In ammonium media, the addition of ammonium sulfate reduces the solution pH, improving the stability of Mn amines. In the absence of ammonium sulfate, Mn amines hydrolyze to Mn hydroxides

[51] .

[0101] Precipitation grades showed no significant differences among the various ligands in terms of selectivity for Co and Mn precipitation. Corresponding grades were of the same order of magnitude (approximately 20-30% Mn, less than 1.8% Co). 3- The ligand precipitated a high amount of Ca (i.e., approximately 60% recovery) at pH 9 and reduced the grade of Co and Mn in the precipitate despite the high recovery.

[0102] Comparing the performance of various chemicals for Co and Mn precipitation, NH4OH achieved the highest recovery (>98%) and grade (0.9% Co and 29% Mn) of these elements at pH 9, without the addition of any other pH modifiers. Among the efficient chemicals, NH4OH offered the lowest chemical consumption, lowest cost, and environmental friendliness. This chemical is also widely used in AMD treatment. Therefore, it can be combined with the previous two-stage carbonate (provided by CO2 or Na2CO3) precipitation process for the selective recovery of Al and REEs from AMD. In the combined process, AMD was first aerated at pH 4 to remove Fe, followed by carbonate precipitation of Al and REEs at pH 5 and 7, respectively. Finally, NH4OH was added to precipitate Co and Mn at pH 9. In some cases, the wastewater was diluted with AMD to bring its pH closer to neutral. In such cases, it is considered that oxidative precipitation of Co and Mn in treated water (i.e., pH 7) obtained from the two-stage precipitation process can be utilized to reduce chemical consumption and address the problem of high pH effluent.

[0103] Effect of Various Oxidizing Agents on the Stepwise Precipitation of Co-Mn. Oxidative precipitation of Co and Mn has been investigated as an alternative approach to avoid the high pH requirement for precipitation of Co and Mn from AMD. Oxidative precipitation has been shown to be highly effective in hydrometallurgical processing [37, 27, 22]. Mn impurity removal from Zn, Co, and Ni processing circuits has been achieved by oxidative precipitation of Mn as insoluble manganese oxide, primarily MnO2. As a strong oxidizing agent, MnO2 has a standard reduction potential of 1.224 V. Therefore, strong oxidizing agents such as ozone, peroxydisulfuric acid, a mixture of SO2 and O2, or Caro's acid are required to oxidize Mn(II) to higher valence oxides, first Mn(III) and then MnO2

[22] .

[0104] This example demonstrates the oxidative precipitation of Co and Mn from AMD using Na2S2O8, KMnO4, and ozone as oxidants. The oxidants were added / purged into the treated / neutralized AMD after the two-stage precipitation process (i.e., at pH 7). Oxidative precipitation can also be a third treatment step after the two-stage precipitation process using previously disclosed methods. Na2S2O8 has been shown to be effective in oxidizing Mn in acidic aqueous systems (i.e., Reaction XI). However, precipitation of Co using this oxidant or potassium persulfate (K2S2O8) has been limited and is due to adsorption onto manganese oxide complexes, not precipitation of cobalt oxide / hydroxide. In reported experiments, four times the stoichiometric amount of Na2S2O8 was used [28, 53]. MnSO4+Na2S2O8+2H2O→MnO2+Na2SO4+2H2SO4(XI)

[0105] Mn was rapidly and effectively oxidized in highly contaminated AMD using KMnO4 (i.e., reaction XII). In a study by Freitas et al.

[27] , over 85% of Mn was precipitated from AMD samples using this oxidant under acidic and neutral pH conditions. Mn precipitates were found in the forms of birnessite, pyrolusite, undstitite (MnO2), hausmannite (Mn3O4), bixbeite (Mn2O3), and manganite (MnOOH). Depending on the pH, adsorption and coprecipitation may also contribute to the removal of Mn and other contaminants, such as Ca, Co, and Zn, from aqueous solutions [27, 54]. These mechanisms are supported by the consumption of less KMnO4 than the stoichiometrically required amount for Mn removal [27, 54]. However, these mechanisms are not highly selective for Mn ions, and therefore, when other elements are present, the number of available sites for Mn adsorption is reduced

[27] . 3Mn 2+ +2KMnO4+2H2O→5MnO2(s)+2K + +4H + (XII)

[0106] Traditional oxidation precipitation techniques often introduce secondary pollutants into the solution, which can adversely affect downstream electrorefining processes. Among various oxidants, such as KMnO4, NaClO, and Cl2, ozone is considered a clean oxidant

[41] . Ozone is a significantly more potent allotrope of oxygen than its diatomic allotrope (O2), making it one of the most powerful oxidants, with a standard redox potential of 1.24 V in alkaline solution. It is also widely used in various applications, such as chemical processing, environmental protection, and food preservation [37-41].

[0107] By using a strong oxidizing agent such as ozone, Mn 2+ and Co 2+ can be oxidized to an unstable state, and Mn 3+ , Mn 4+ , Co 3+These react with hydroxyl radicals and are removed from solution as MnO2, Mn2O3, and CoOOH, as illustrated in Reactions XIII-XV. The Gibbs free energies (△G θ ) value is negative, so the reaction is thermodynamically feasible.

[41] Mn 2+ +1 / 2O3+H2O→1 / 2Mn2O3+2H + +1 / 2O2(XIII) Mn 2+ +O3+H2O→MnO2+2H + +O2(XIV) Co 2+ +1 / 2O3+3 / 2H2O→CoOOH+2H + +1 / 2O2(XV)

[0108] In our study, oxidative precipitation using ozone and KMnO4 yielded recoveries of over 90% for both Co and Mn (Figure 4A-4B), consistent with previously mentioned literature. However, Na2S2O8 precipitation yielded lower recoveries for Co and Mn, 15% and 31%, respectively. The low recovery of Co was expected because this element is removed only through adsorption onto manganese oxide complexes. The low recovery of Mn using this oxidant is likely due to the low concentration of this element in the initial AMD feed.

[0109] The grades of elements, including Co and Mn, and other major and important elements in the precipitates obtained from oxidation precipitation are shown in Figures 4A–4C. High Mn grades (28%–54.6%) were obtained using all three oxidizing agents. The highest grades of Mn (i.e., 54.6%) and Co were obtained by using ozone (i.e., 0.9% Co and ozone vs. 0.4% and 0.2% Co obtained from KMnO4 and Na2S2O8, respectively). The main impurities were Ca and Mg, which can be separated through downstream purification processes. For example, Lin et al.

[25] used ammonium bicarbonate to selectively separate Mn from a sulfate solution containing Mg and Ca. The main advantages of using ammonium bicarbonate are its low cost, easy-to-control reaction, and the absence of contaminants other than ammonium ions

[25] . The reported presence of other important elements in the precipitates confirms the coprecipitation reported in the literature [25, 26]. The progress of oxidation ozone precipitation as a function of time is shown in Figure 5. Immediately after injecting ozone into the treated AMD, the solution color changed to yellow, then to light brown and dark brown after a few hours. The change in solution color suggests that high Co and Mn recoveries and grades can be obtained through control of reaction time. In the latter example, a kinetic study was performed to obtain the kinetic rates of Co and Mn precipitation and co-precipitation of other elements, which provided insight into how to obtain high-grade products and determine process scale-up parameters.

[0110] Proposed process for Co-Mn recovery from AMD. Ozone was found to be the most efficient oxidant for Co and Mn recovery. It also provides an environmentally friendly, chemical-free precipitation of these elements. Furthermore, other important elements, such as nickel (Ni), lead (Pb), copper (Cu), and manganese (Mn), can also be recovered when present in aqueous solutions such as AMD. The highest Co and Mn recovery rates and grades from AMD samples were obtained by the oxidative ozone precipitation method. Therefore, it was further investigated for use in AMD treatment processes.

[0111] For this purpose, ozone was also injected into original AMD samples to study the potential for Co and Mn precipitation during the initial stage and their removal during the aeration step. The results were compared with those obtained when ozone was injected into treated AMD (i.e., pH 7) obtained from a two-stage carbonate precipitation process. The data (shown in Table 3) indicated that there was no significant difference in Co-Mn recovery when ozone was injected into either original AMD (pH 3.5) or treated AMD (pH 7). However, ozone injection into original AMD resulted in a 28% loss of REEs (mainly scandium (Sc) at 30% recovery and cerium (Ce) at 90% recovery) in the corresponding precipitates. A similar discrepancy between the behavior of Ce in natural and synthetic systems was observed in Ce adsorption on Mn oxides, where significant Ce oxidation occurred in the synthetic system but was minimal in the natural system. If the AMD sample does not contain significant REEs, ozone purging of the original AMD is recommended because it avoids the aeration step. However, if the REE content of the AMD is important (as in the AMD used in this study), ozone needs to be purged after the recovery of Al and REEs. Therefore, the previous two-stage carbonate precipitation process was modified by including ozone injection at pH 7, i.e., after the recovery of REEs [57, 34, 11].

[0112] [Table 3]

[0113] The three-stage precipitation process tested and the corresponding key element recovery data for each stage are shown in Figure 6. In this process, AMD is first aerated to oxidize Fe, then precipitated at approximately pH 4. This process follows a three-stage precipitation process. The solution pH is increased to pH 5 and 7 using carbonate ligands (i.e., through Na2CO3 or CO2 mineralization) to selectively recover Al and REEs. In the third stage, ozone is injected to recover Co and Mn. This process achieved removal of over 95% Fe at pH 4, over 80% Al at pH 5, and over 94.5% REE recovery at pH 7. The remaining Co and Mn in solution were completely recovered by injecting ozone into the treated AMD, resulting in an overall recovery of over 98% for these elements, yielding a product containing 54.6% Mn and 0.9% Co.

[0114] The Co-Mn precipitate products of ozone precipitation were characterized using SEM-EDS and XRD (Figure 7A-7D). SEM-EDS images showed that most of the Co-Mn precipitate particles were submicron-sized with irregular shapes and rough surfaces (Figure 7D). XRD results revealed that the manganese precipitates were in the form of manganese oxide hydrate (MnO HO), manganese oxide hydroxide (MnOOH), and trimanganese tetroxide (MnO) (Figure 7A). These manganese forms were also confirmed by FT-IR analysis. FT-IR spectra showed a peak at approximately 528 cm, which is attributed to the Mn-O bond in the MnO and MnO structures. -1 It showed a strong absorption band at 1061cm -1 and 1620 cm -1 The bond between Co and Mn atoms is due to the OH bond vibration. Ca was found to be present in the form of aragonite (CaCO3) as one of the major impurities. XRD analysis did not reveal a sharp peak for Co due to its relatively low concentration. The literature discusses the adsorption of Co onto MnO2 during the precipitation process. However, SEM micrographs and EDS mapping data showed the independent precipitation of Co from Mn (Figures 7C-7D).

[0115] Conclusions: Through experimental and solution chemistry studies, the effect of various ligands and oxidants on the precipitation of Co and Mn as a function of pH and Eh was investigated, leading to the development of a process for the recovery of these key elements from AMD. - , CO3 2- , NH4 + , SO4 2- , PO4 3- Various ligands, such as Na2SO8, KMnO4, and O3, were studied as oxidants. Among the ligands, NH4OH showed the highest recovery rate (>98%) and grade (0.9% Co and 28% Mn) at pH 9, offering low chemical consumption, cost, and toxicity. Among the oxidants, O3 showed the highest recovery rate (>98%) and grade (0.9% Co and 54.6% Mn) while providing chemical-free oxidation precipitation of these elements at pH values ​​up to 7. The Mn precipitate obtained from oxidative ozone precipitation was in the form of MnO2·H2O, MnOOH, and Mn3O4. Based on the experimental results and the precipitation patterns of Al, REEs, Co, and Mn, a stepwise precipitation process was designed to selectively recover these elements and neutralize AMD to mitigate environmental concerns. Using this proposed three-step process, over 95% of Co-Mn and 90% of REEs and Al were selectively recovered at various stages of the process.

[0116] Example 2. Oxidative precipitation of cobalt and manganese using ozone, a parametric study.

[0117] A statistically designed parametric study using the Box-Behnken method was conducted to identify the key factors affecting the oxidation precipitation of Co-Mn. The experimental program evaluated the effects of gas flow rate (oxygen or air at the ozone generator inlet), stirring speed, and temperature.

[0118] The Box-Behnken design parameters for the oxidation of Co and Mn using ozone are as follows: gas flow rate (200, 1100, 2000 cc / min), stirring speed (0, 400, 800 rpm), and temperature (20, 50, 80 °C).

[0119] In this example, two different pure stock solutions were prepared, one containing 10 ppm Co and the other containing 50 ppm Mn, which are representative of the concentrations of these elements in AMD. A total of 34 experiments were conducted based on a three-stage experimental design. Two separate setups were used for Co-Mn, and dissolved ozone in the solution was measured (Figure 5).

[0120] For cobalt, the effects of process parameters including gas flow rate, agitation speed, and temperature on the oxidative precipitation of Co using ozone were studied.

[0121] The model was significant, with insignificant poor fit. Temperature and gas flow rate were important parameters in Co recovery. As can be seen from the surface response plot (Figure 8), Co recovery initially increased and then decreased with increasing gas flow rate and temperature. The optimal conditions for Co recovery were found to be a gas flow rate of 1100 ml / min and a temperature of 50°C. The analysis of variance for Co recovery is shown in Table 4.

[0122] The model was also significant for Mn, with insignificant poor fit. The interaction effect between temperature and gas flow rate, as well as the interaction effect between gas flow rate and agitation speed, were important parameters in Mn recovery.

[0123] As can be seen from the surface response plot (Figure 9), increasing the temperature and flow rate increases the recovery of Mn. The optimum conditions for Mn recovery were obtained at a gas flow rate of 700 ml / min and a temperature of 80°C. The analysis of variance for Co recovery is shown in Table 5.

[0124] [Table 4]

[0125] [Table 5]

[0126] The difference in the behavior of Mn and Co at high temperatures may be due to a combination of factors, including differences in solubility, differences in reaction rates, the importance of oxygen and ozone in promoting precipitation, the concentration of metal ions in solution, and the presence of other ions and compounds in solution.

[0127] In the following example, the oxidative precipitation of Co and Mn in a stock solution by ozone is reported. Various factors affecting the oxidative precipitation rate (temperature, stirring speed, gas flow rate, initial ion concentration) are comprehensively investigated, and the kinetic equations are established.

[0128] The oxidation process is temperature dependent, which has a significant effect on the mass transfer of ozone in aqueous solutions. During the experiments, parameters such as stirring speed 400 cc / min, gas flow rate 1100 ml / min, and pH 7 were kept constant.

[0129] In this example, three different kinetic models were explored for Co-Mn precipitation results. The linear model (Equation 3) assumes a first-order reaction at uniform ozone concentration, the Higbee model (Equation 4) accounts for mass transport limitation, and the pseudo-homogeneous model (Equation 5) combines both the linear and Higbee models to account for both homogeneity and mass transport limitation. Activation energies are measured using Equation 6 to better understand the Co-Mn precipitation mechanism.

[0130]

number

[0131]

number

[0132]

number

[0133]

number

[0134] Temperature is an important parameter in the oxidation precipitation of Co-Mn. Figures 10A-10D show the recovery of Co in solution as a function of temperature over time. The results show several features. First, the precipitation reaction is very fast, with more than 50% of the Co ions in solution being precipitated within the first minute. Second, increasing the temperature initially increased the recovery of Co, then decreased it. Third, an intermediate phase exists in the early stages of the reaction, complicating the kinetic mechanism.

[0135] Figures 11A-11E show the recovery of Mn in solution as a function of temperature over time. The results show that the precipitation reaction is very fast, with the highest recovery of approximately 95% achieved in 5 minutes, and the recovery rate further increased with increasing temperature.

[0136] The kinetic rates and activation energies of the reaction were calculated over short and long periods using three kinetic models, and pseudohomogeneous was found to best describe the reaction (Figures 12A and 12B).

[0137] Providing a specific mechanism for Co-Mn precipitation using ozone is difficult because other phenomena play a role, making the process more complex. For example, mass transfer of ozone plays an important role because it is continuously injected into the reaction throughout the entire process. Therefore, short-term and long-term kinetic rates and activation energies were determined for both Co and Mn. Nucleation is very rapid in the early stages of the reaction, and precipitate growth then begins at a much faster rate than nucleation. As shown in Figures 12A and 12B, the activation energy values ​​for Co-Mn indicate that the process is likely a diffusion-controlled reaction for both elements (Figures 12A and 12B). This suggests that the rate at which ozone molecules diffuse to the surfaces of Co and Mn particles largely determines the reaction rate. Therefore, ozone mass transfer plays an important role in the oxidation precipitation of Co-Mn.

[0138] The stirring speed is another important parameter in the oxidation process. The following parameters were kept constant throughout the experiment: temperature of 25 °C, ozone flow rate of 250 mL / min, and pH 7.0. Figures 13A-13D show that as the stirring speed increases, the concentration of Co-Mn in solution decreases at a faster rate. In other words, a higher stirring speed significantly improves the recovery rate of the Co-Mn precipitate. However, a very high stirring speed negatively impacts the recovery rate of Co (Figures 13A and 13B).

[0139] In this study, the effect of ion concentration on the recovery rates of Co and Mn was also investigated. The experimental conditions included a temperature of 25°C, pH 7, a stirring speed of 1500 rpm, and a flow rate of 1400 cc / min. As shown in Figures 14A-14F, it is clear that when the initial Co concentration is 0.01 mM, it takes approximately 1 minute for Co to completely precipitate. However, when the initial concentration is increased to 100 mM, the complete reaction of cobalt occurs within 1 hour. A similar trend was observed for Mn, but it took a longer time for Mn to completely precipitate (i.e., 4 hours for 100 mM), and therefore the precipitation rate of Co is faster than that of Mn.

[0140] The gas flow rate (oxygen flow rate) also has a significant effect on the oxidation precipitation of Co and Mn using ozone. The conditions of 25 °C, pH 7, and agitation speed of 400 rpm were kept constant throughout the experiment. Figures 15A-15D show the recovery of Co and Mn from solution as a function of flow rate over time. When the O2 flow rate was set at 200 mL / min, it was evident that it took approximately 20 min for Co to fully precipitate. However, when the O2 flow rate was increased to 2000 mL / min, the complete reaction of cobalt occurred within 5 min. Increasing the flow rate from 1400 to 2000 mL / min decreased the recovery of Co (in the first 3 min) (Figures 15A and 15B).

[0141] On the other hand, when the O2 flow rate is set at 200 and 2000 mL / min, it is clear that it takes about 5 min for Mn to completely precipitate (Figures 15C and 15D), but in the first 3 min, recovery increases slightly with higher flow rates.

[0142] Example 3. Purification - Selective Oxidative Precipitation.

[0143] In another example, the purification and selective separation of Co and Mn from different aqueous solutions (stock solution, AMD / sludge, e-waste) by potential-controlled oxidation with ozone was investigated.

[0144] Co and Mn can be selectively precipitated and purified by ozone oxidation precipitation through control of the oxidation-reduction potential (ORP). Ozone is a strong oxidizing agent and plays a key role in the oxidation process, converting Co and Mn species to their respective higher oxidation states and facilitating their subsequent precipitation or extraction.

[0145] pH control and ORP (oxidation-reduction potential) are important factors in the selective recovery of important elements from aqueous solutions. They can affect the species and solubility of elements, allowing for the selective separation of target elements.

[0146] By controlling the ORP and pH during the oxidation process, either Co or Mn can be selectively precipitated for purification. By adjusting the oxidation potential, one metal can be preferentially oxidized while the other is kept in a lower oxidation state. This allows Co and Mn to be separated from aqueous solutions based on their unique oxidation behavior.

[0147] The solubility of many metal ions is pH dependent. By controlling the pH of a solution, certain metal ions can be precipitated as insoluble compounds. Adjusting the pH to a specific range can promote the formation of the desired precipitate while keeping other elements in solution.

[0148] ORP plays an important role in the selective separation of Co and Mn during potential-controlled oxidation with ozone. ORP measures the tendency of a solution to undergo oxidation or reduction reactions. This provides valuable information about the oxidizing or reducing power of a system. In the context of selective separation, ORP is used to control the oxidation potential during the oxidation process. By adjusting ORP, it is possible to selectively target and oxidize one metal while minimizing the oxidation of the other. This differential oxidation behavior is essential for the successful separation of Co and Mn. Selective separation of Co and Mn is achieved by carefully controlling ORP. This ensures that one metal is effectively separated from the solution while minimizing unwanted reactions and losses of other metals. Therefore, monitoring and adjusting ORP is critical to achieving successful and efficient selective separation in potential-controlled oxidation processes. Initial results of selective separation of key elements from different aqueous solutions are promising. Furthermore, recovery of precious and other important elements (including Ni, Cu, Cd, Cr, Zr, Bi, Tl, Ga, and Sn), Ce, and Fe may be achieved by ozone oxidation precipitation. 16A-16R show Eh-pH diagrams illustrating the conditions under which various metal elements undergo the formation of insoluble compounds when exposed to ozone oxidation precipitation.

[0149] Co-Mn stock solution. In this example, the concentrations of Mn and Co, as well as the ORP of the system, were measured periodically. The experiment was conducted at a temperature of 25°C, a pH value of 4.0, an agitation speed of 1500 rpm, and a gas flow rate of 1100 cc / min. The results of this experiment are shown in Figure 17. In the first step, the separation of Mn was targeted, and its concentration rapidly decreased within the first 300 seconds. Meanwhile, the concentration of Co remained relatively stable, with minimal recovery (approximately 20%). In the second step, Co recovery was completed within the next 300 seconds, precipitating from the aqueous solution. Purity can be further improved by combining pH adjustment and ORP control.

[0150] AMD / Sludge. AMD sludge was leached, and the leachate was treated to recover elements by ozone precipitation. During purification of the AMD sludge leachate, the concentrations of Co, Mn, Ag, Cd, Zr, and Ce, as well as the ORP of the system, were periodically measured. The experiment was conducted at a temperature of 25°C, a pH value of 4.0, an agitation speed of 1500 rpm, and a gas flow rate of 1100 cc / min. The results of this experiment are shown in Figure 18. As can be seen, in terms of selective separation, Co and Mn show similar trends to those shown in Figure 17. Furthermore, separation of Ag, Cd, Zr, and Ce can be achieved by oxidative precipitation using ozone. Using ozone oxidative precipitation, the purity of the target elements can be further improved by combined control of pH and ORP values ​​determined based on the pH-Eh diagrams shown in Figures 16A-16R.

[0151] Element separation from leachate obtained by treating electronic waste. In this example, the leachate obtained by leaching electronic waste (discarded printed circuit boards) with sulfuric acid was subjected to stepwise precipitation at pH 7 to recover metals, and ozone was introduced into the leachate. The concentrations of Co, Mn, Cu, Ag, Ni, and Cd, as well as the ORP of the system, were periodically measured. The experiment was conducted in the leachate obtained by treating electronic waste at a temperature of 25°C, a pH value of 7.0, an agitation speed of 1500 rpm, and a gas flow rate of 1100 cc / min. The results of this experiment are shown in Figure 19. The first step targeted the separation of Cu, and its concentration rapidly decreased within the first 5 seconds. Meanwhile, the concentrations of other elements, including Mn, Ni, Co, Ag, and Cd, remained relatively stable, with minimal recovery (less than 5%). In the next step, Mn recovery was achieved in 300 seconds (recovery rate >80%), while the other elements remained in solution. Co recovery was achieved over the next 2 minutes (recovery rate >95%). Approximately 70% of Ag and 40% of Cd were subsequently recovered from the solution in 15 minutes, while most of the Ni remained in the aqueous solution. In the final step, Ni was recovered from the remaining solution within 2 hours (recovery rate >80%). This result demonstrates that selective separation of Co, Mn, Cu, Ag, Cd, and Ni can be achieved through potential-controlled oxidation using ozone, taking advantage of the differences in elemental precipitation rates. Combining a pH-controlled process can further improve separation efficiency. Exemplary Embodiments

[0152] Exemplary Embodiment 1. A method for removing dissolved metals from an aqueous solution includes the steps of a) mixing ozone with the aqueous solution, thereby forming a dissolved metal precipitate, and b) removing the dissolved metal precipitate.

[0153] Exemplary Embodiment 2. The method of Exemplary Embodiment 1 further includes c) measuring the dissolved metal concentration, Eh, and pH in the aqueous solution, and d) repeating steps a) through c) until the measured dissolved metal concentration does not substantially change.

[0154] Exemplary Embodiment 3. In the method of Exemplary Embodiment 1 or 2, the aqueous solution comprises one or more dissolved metals Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0155] Exemplary Embodiment 4. The method of any of Exemplary Embodiments 1-3 includes removing Fe, Al, Ca, Mg, Na, P, and / or rare earth metals before mixing ozone with the aqueous solution.

[0156] Exemplary Embodiment 5. The method of any of Exemplary Embodiments 1-3 includes removing Fe, Al, Ca, Mg, Na, P, and / or rare earth metals after step d).

[0157] Exemplary Embodiment 6. In the method of any of Exemplary Embodiments 1-5, ozone is mixed into the aqueous solution at a predetermined flow rate.

[0158] Exemplary Embodiment 7. In the method of any of Exemplary Embodiments 1-6, the temperature of the aqueous solution is about 0-80°C during steps a)-d).

[0159] Exemplary Embodiment 8. The method of any of Exemplary Embodiments 1-7, wherein the flow rate of ozone is varied as steps a)-c) are repeated.

[0160] Exemplary Embodiment 9. In the method of any of Exemplary Embodiments 1-8, the temperature of the aqueous solution is changed as steps a)-c) are repeated.

[0161] Exemplary Embodiment 10. In the method of any of Exemplary Embodiments 1-9, steps a)-c) are repeated until the measured pH is about 8.0.

[0162] Exemplary Embodiment 11. In the method of any of Exemplary Embodiments 1-10, the aqueous solution has a pH of about 0-12.

[0163] Exemplary Embodiment 12. In the method of any of Exemplary Embodiments 1-11, the aqueous solution comprises acid mine drainage, mine-affected water, industrial wastewater, brine, geothermal brine, oil and gas produced water and wastewater, sludge leachate, e-waste recycling leachate, battery recycling leachate, solar panel recycling leachate, leachate / pregnant leachate obtained from processing ores or any other primary and secondary metal sources, or other aqueous waste containing Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0164] Exemplary Embodiment 13. The method of any of Exemplary Embodiments 1-12, wherein the dissolved metal forms a precipitate, and the precipitate is a precipitate of Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0165] Exemplary Embodiment 14. In the method of Exemplary Embodiment 13, about 50-99% of the dissolved metal is recovered as a precipitate from the aqueous solution.

[0166] Exemplary Embodiment 15. In the method of Exemplary Embodiment 14, the precipitate of dissolved metals is purified for secondary use.

[0167] Exemplary Embodiment 16. A method of recovering dissolved metals from an acid mine drainage stream includes the steps of: a) removing Fe; b) removing Al; c) removing REEs; d) mixing ozone with the acid mine drainage stream at a rate to form a dissolved metal precipitate; e) separating the dissolved metal precipitate; f) measuring the dissolved metal concentration and pH of the acid mine drainage stream; and g) repeating steps d) through f) until the measured dissolved metal concentration no longer changes.

[0168] Exemplary Embodiment 17. In the method of Exemplary Embodiment 16, Fe is removed by aeration or chemical precipitation.

[0169] Exemplary Embodiment 18. In the method of any of Exemplary Embodiments 16-17, Al is removed by chemical precipitation at low pH.

[0170] Exemplary Embodiment 19. In the method of any of Exemplary Embodiments 16-18, the rare earth elements are removed by chemical precipitation at acidic or neutral pH.

[0171] Exemplary Embodiment 20. A method for purifying or selectively removing dissolved metals from an aqueous solution includes: a) adjusting the pH of the aqueous solution to a predetermined pH; b) flowing ozone into the aqueous solution to achieve a predetermined oxidation-reduction potential and stirring the aqueous solution for a predetermined time to form a first solid metal fraction; c) separating the first solid metal fraction; and d) repeating steps a)-c) for a second or more solid metal fractions.

[0172] Exemplary Embodiment 21. In the method of Exemplary Embodiment 20, one of the first, second, or more solid metal fractions comprises dissolved metal, and the dissolved metal is one or more of Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

[0173] Exemplary Embodiment 22. In the method of exemplary embodiment 20 or 21, the predetermined pH is in the range of about 0 to about 8.

[0174] Exemplary Embodiment 23. In the method of any of Exemplary Embodiments 20-22, the aqueous solution is brine, mining, oil and gas industry wastewater, or leachate obtained from ore processing, secondary source processing, waste treatment, sludge processing, sediment processing, or recycling of e-waste, batteries, and solar panels.

[0175] Exemplary Embodiment 24. In the method of any of Exemplary Embodiments 20-23, about 50-99% of the metal is recovered from the first, second, or more solid metal fractions of the aqueous solution.

[0176] References [1] PLRozelle, N. Mamula, BJArnold, T. O'Brien, M. Rezaee, SVPisupati, Secondary cobalt and manganese resources in Pennsylvania: quantities, linkage with mine reclamation, and preliminary flowsheet evaluation for the US domestic lithium-ion battery supply chain Pa.State Univ.Cent.Crit.Miner.2021. [2] Rozelle, PL, Shi, F., Rezaee, M., Pisupati, SV (2020). The Pennsylvania State University Center for Critical Minerals. [3]USGeological Survey.(2022a).Manganese.Mineral commodity summaries. [4]USGeological Survey.(2022b).Cobalt.Mineral commodity summaries. [5]Slack,J.F.,Kimball,B.E.,およびShedd,K.B.(2017).Cobalt,chap.F of Schulz,K.J.,DeYoung,J.H.,Jr.,Seal,R.R.,II,およびBradley,D.C.,eds.,Critical mineral resources of the United States-Economic and environmental geology and prospects for future supply:U.S.Geological Survey Professional Paper 1802,p.F1-F40,https: / / doi.org / 10.3133 / pp1802F. [6]International Energy Agency(IEA).(2021).The role of critical minerals in clean energy transition.World energy outlook special report. [7]D.B.Johnson,K.B.Hallberg,Acid mine drainage remediation options:a review,Sci.Total Environ.338(1-2)(2005)3-14. [8]M.Rezaee,F.E.Huggins,R.Q.Honaker,Minimizing the environmental impacts of coal waste disposal,Environ.Consid.Energy Prod.(2013)60-77. [9]M.Rezaee,R.C.Warner,R.Q.Honaker,Development of an electrical conductivity screening test for mine waste assessments,Chemosphere 160(2016)13-21.

[10] J.G.Skousen,P.F.Ziemkiewicz,L.M.McDonald,Acid mine drainage formation,control and treatment:approaches and strategies,Extr.Ind.Soc.6(1)(2019)241-249.

[11] B.Vaziri Hassas,M.Rezaee,S.V.Pisupati,Effect of various ligands on the selective precipitation of rare earth elements from acid mine drainage,Chemosphere 280(2021),130684.

[12] A.Akcil,S.Koldas,Acid mine drainage(AMD):causes,treatment,and case studies,J.Clean.Prod.14(12-13)(2006)1139-1145.

[13] M.Rezaee,R.Q.Honaker,Long-term leaching characteristic study of coal processing waste streams,Chemosphere 249(2020),126081.

[14] A.RoyChowdhury,D.Sarkar,R.Datta,Remediation of acid mine drainage-impacted water,Curr.Pollut.Rep.1(3)(2015)131-141.

[15] M.Rezaee,V.N.Rajagopalan,R.Q.Honaker,Conceptual modifications of coal preparation plants to minimize potential environmental issues associated with coal waste disposal,Fuel 250(2019)352-361.

[16] National Pollutant Discharge Elimination System(NPDES),1972.Federal Water Pollution Control Act Amendments of 1972,the Clean Water Act 33 U.S.C.§1251 et seq.

[17] G.Chen,Y.Ye,N.Yao,N.Hu,J.Zhang,Y.Huang,A critical review of prevention,treatment,reuse,and resource recovery from acid mine drainage,ISSN 0959-6526,J.Clean.Prod.329(2021),129666,https: / / doi.org / 10.1016 / j.jclepro.2021.129666.

[18] D.W.Fuerstenau,K.N.Han,Metallurgy and processing of marine manganese nodules,Miner.Process.Extr.Metall.Rev.1(1-2)(1983)1-83,https: / / doi.org / 10.1080 / 08827508308952589.

[19] Q.Li,W.Zhang,Process development for recovering critical elements from acid mine drainage,ISSN 0921-3449,Resour.Conserv.Recycl.180(2022),106214,https: / / doi.org / 10.1016 / j.resconrec.2022.106214.

[20] G.Pozo,S.Pongy,J.Keller,P.Ledezma,S.Freguia,A novel bioelectrochemical system for chemical-free permanent treatment of acid mine drainage,Water Res.126(2017)411-420,https: / / doi.org / 10.1016 / j.watres.2017.09.058.

[21] E.Y.Seo,Y.W.Cheong,G.J.Yim,K.W.Min,J.N.Geroni,Recovery of Fe,Al and Mn in acid coal mine drainage by sequential selective precipitation with control of pH,Catena 148(2017)11-16.

[22] W.Zhang,C.Y.Cheng,Manganese metallurgy review.Part II:Manganese separation and recovery from solution,Hydrometallurgy 89(3-4)(2007)160-177.

[23] A.A.Baba,L.Ibrahim,F.A.Adekola,R.B.Bale,M.K.Ghosh,A.R.Sheik,S.R.Pradhan,O.S.Ayanda,I.O.Folorunsho,Hydrometallurgical processing of manganese ores:a review,J.Miner.Mater.Charact.Eng.2(03)(2014)230.

[24] A.Katsiapi,P.E.Tsakiridis,P.Oustadakis,S.Agatzini-Leonardou,Cobalt recovery from mixed Co-Mn hydroxide precipitates by ammonia-ammonium carbonate leaching,Miner.Eng.23(8)(2010)643-651.

[25] Q.Lin,J.G.Fu,G.Gu,C.Wang,H.Wang,R.F.Zhu,Separation of manganese from calcium and magnesium in sulfate solutions via carbonate precipitation,Trans.Nonferrous Met.Soc.China 26(4)(2016)1118-1125.

[26] M.M.Muanda,P.P.D.Omalanga,Modeling and optimization of manganese carbonate precipitation using response surface methodology and central composite rotatable design,J.Eng.Exact.Sci.7(3)(2021).

[27] R.M.Freitas,T.A.Perilli,A.C.Q.Ladeira,Oxidative precipitation of manganese from acid mine drainage by potassium permanganate,J.Chem.(2013),287257.

[28] S.H.Joo,J.Kang,K.Woong,S.M.Shin,Production of chemical manganese dioxide from lithium-ion battery ternary cathodic material by selective oxidative precipitation of manganese,Mater.Trans.54(5)(2013)844-849.

[29] J.Van Rooyen,S.Archer,M.Fox,Manganese removal from cobalt solutions with dilute sulphur dioxide gas mixtures(July)Fourth South.Afr.Conf.Base Met.South.Afr.Inst.Min.Metall.2007 365 376.

[30] S.M.Park,J.C.Yoo,S.W.Ji,J.S.Yang,K.Baek,Selective recovery of dissolved Fe,Al,Cu,and Zn in acid mine drainage based on modeling to predict precipitation pH,Environ.Sci.Pollut.Res.22(2015)3013-3022,https: / / doi.org / 10.1007 / s11356-014-3536-x.

[31] W.Zhang,R.Honaker,Process development for the recovery of rare earth elements and critical metals from an acid mine drainage,Miner.Eng.153(2020),106382,https: / / doi.org / 10.1016 / j.mineng.2020.106382.

[32] M.Balintova,A.Petrilakova,Study of pH influence on selective precipitation of heavy metals from acid mine drainage,Chem.Eng.Trans.25(2011)345-350.

[33] Y.Haihe,Z.Tianwen,J.Zhirong,S.Tian,W.Chunguang,Study on the influencing factors and mechanism of calcium carbonate precipitation induced by urease bacteria,J.Cryst.Growth 564(2021)1-9.

[34] B.Vaziri Hassas,M.Rezaee,S.V.Pisupati,Precipitation of rare earth elements from acid mine drainage by CO2mineralization process,Chem.Eng.J.399(2020),125716.

[35] V.Philippini,T.Vercouter,A.Chauss´e,P.Vitorge,Precipitation of ALn(CO3)2,xH2O and Dy2(CO3)3,xH2O compounds from aqueous solutions for A + =Li + ,Na + ,K + ,Cs + ,NH4 + and Ln 3+ =La 3+ ,Nd 3+ ,Eu 3+ ,Dy 3+ ,J.Solid State Chem.181(9)(2008)2143-2154.

[36] J.D.Rodriguez-Blanco,B.Vallina,J.A.Blanco,L.G.Benning,The role of REE 3+ in the crystallization of lanthanites,Mineral.Mag.78(6)(2014)1373-1380.

[37] Bolton,G.L.,Sefton,V.B.,& Zubryckyj,N.(1981).U.S.Patent No.4,290,866.

[38] Sato,M.およびRobbins,E.I.(2000).Recovery / removal of metallic elements from acid mine drainage using ozone.Society for Mining,Metallurgy,and Exploration,Proceedings of the 2000 ICARD conference,v.II,p.1095-1100.

[39] S.J.Tewalt,M.Sato,F.T.Dulong,S.G.Neuzil,A.Kolker,K.O.Dennen,Use of ozone to remediate manganese from coal mine drainage waters Proc.Natl.Meet.Am.Soc.Min.Reclam.,2005,pp.1166-1176.

[40] Q.H.Tian,X.Y.Guo,Y.I.Yu,Z.H.Li,Kinetics of oxidation-precipitation of cobalt(II)from solution by ozone,Trans.Nonferrous Met.Soc.China 20(2010)s42-s45.

[41] Q.Tian,Y.Xin,H.Wang,X.Guo,Potential-controlled selective recovery of manganese and cobalt from cobalt slag leaching solution,Hydrometallurgy 169(2017)201-206.

[42] Senanayake.G.(2011).Acid leaching of metals from deep-sea manganese nodules -A critical review of fundamentals and applications Miner.Eng.,24(13)(2011),pp.1379-1396,10.1016 / j.mineng.2011.06.003.

[43] A.Jones,Enhanced metal recovery from a modified caron leach of mixed nickel-cobalt hydroxide.Doctoral dissertation Murdoch Univ.,2013,pp.1-179.

[44] J.D.Hem,C.E.Roberson,C.J.Lind,Thermodynamic stability of CoOOH and its coprecipitation with manganese,Geochim.Et Cosmochim.Acta 49(3)(1985)801-810.

[45] C.J.Bise,Modern American coal mining:methods and applications.Society for Mining,Metallurgy,and Exploration Inc.Englewood,CO 2013 563.ISBN:9780873353526.P.

[46] S.J.Clark,J.D.Donaldson,Z.I.Khan,Heavy metals in the environment.Part VI:Recovery of cobalt values from spent cobalt / manganese bromide oxidation catalysts,Hydrometallurgy 40(3)(1996)381-392.

[47] R.P.Das,S.Anand,S.C.Das,P.K.Jena,Leaching of manganese nodules in ammoniacal medium using glucose as reductant,Hydrometallurgy 16(3)(1986)335-344.

[48] R.S.Dean,Manganese extraction by carbamate solutions and the chemistry of new manganese ammonia complexes,Trans.AIME(1952)55-60.

[49] K.Osseo-Asare,Application of activity-activity diagrams to ammonia hydrometallurgy-3-Mn-NH3-H2O,Mn-NH3-H2O-CO3and Mn-NH3-H2O-SO4systems at 25 degree C.Transactions of the Institution of Mining and Metallurgy Sect.C:Miner.Process.Extr.Metall.,90,1981,pp.152-158.

[50] C.Drouet,Applied predictive thermodynamics(ThermAP).Part 2.Apatites containing Ni2+,Co2+,Mn2+,or Fe2+ions,J.Chem.Thermodyn.136(2019)182-189.

[51] S.Mohanty,M.K.Ghosh,V.Chakravortty,S.Anand,Behaviour of cobalt during precipitation of manganese from the NH3-(NH4)2SO4-Mn-O2 system,Hydrometallurgy 42(3)(1996)357-366.

[52] B.Vaziri Hassas,Y.Shekarian,M.Rezaee,S.V.Pisupati,Selective recovery of high-grade rare earth,Al,and Co-Mn from acid mine drainage treatment sludge material,Miner.Eng.187(2022),https: / / doi.org / 10.1016 / j.mineng.2022.107813.

[53] K.C.Nathsarma,P.B.Sarma,Separation of iron and manganese from sulphate solutions obtained from indian ocean nodules,Hydrometallurgy 17(2)(1987)239-249.

[54] J.W.Murray,J.G.Dillard,R.Giovanoli,H.Moers,W.Stumm,Oxidation of Mn(II):Initial mineralogy,oxidation state and ageing,Geochim.Et Cosmochim.Acta 49(2)(1985)463-470.

[55] J.E.Post,Manganese oxide minerals:crystal structures and economic and environmental significance,Proc.Natl.Acad.Sci.U.S.A.96(7)(1999)3447-3454.

[56] M.Bau,Scavenging of dissolved yttrium and rare earths by precipitating iron oxyhydroxide:experimental evidence for Ce oxidation,Y-Ho fractionation,and lanthanide tetrad effect,Geochim.Et Cosmochim.Acta 63(1)(1999)67-77.

[57] M.Rezaee,B.Vaziri,Hassas S.V.,Pisupati Recovery of rare earth elements from acidic solutions U.S.Pat.,WO2021155224A1.2021.

[58] M.Rezaee,Y.Shekarian,S.V.Pisupati,Ozone Oxidative Precipitation of Elements from Aqueous Streams U.S.Provisional Pat.Appl.Ser.No.63 / 392 2022 330.

Claims

1. A method for removing dissolved metal from an aqueous solution, a) A step of mixing ozone into the aqueous solution to form a dissolved metal precipitate, b) A method comprising the step of removing the dissolved metal precipitate.

2. c) A step of measuring the dissolved metal concentration, Eh, and pH of the aqueous solution, d) The method according to claim 1, further comprising the step of repeating steps a) to c) until the measured dissolved metal concentration no longer substantially changes.

3. The method according to claim 1 or 2, wherein the aqueous solution comprises one or more dissolved metals Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

4. The method according to claim 1 or 2, wherein the method comprises removing Fe, Al, Ca, Mg, Na, P, and / or rare earth metals before mixing the ozone with the aqueous solution.

5. The method according to claim 1 or 2, wherein the method comprises removing Fe, Al, Ca, Mg, Na, P, and / or rare earth metals after step d).

6. The method according to claim 1 or 2, wherein the ozone is mixed into the aqueous solution at a predetermined flow rate.

7. The method according to claim 1 or 2, wherein the temperature of the aqueous solution is approximately 0 to 80°C during steps a) to d).

8. The method according to claim 1 or 2, wherein the flow rate of ozone changes when steps a) to c) are repeated.

9. The method according to claim 1 or 2, wherein the temperature of the aqueous solution changes when steps a) to c) are repeated.

10. The method according to claim 1 or 2, wherein steps a) to c) are repeated until the measured pH becomes approximately 8.

11. The method according to claim 1 or 2, wherein the pH of the aqueous solution is approximately 0 to 12.

12. The method according to claim 1 or 2, wherein the aqueous solution comprises acidic mine wastewater, mine impact water, industrial wastewater, brine, geothermal brine, oil and gas production water and wastewater, sludge leachate, electronic waste recycling leachate, battery recycling leachate, solar panel recycling leachate, leachate / noble leachate obtained from processing ore or any other primary and secondary metal sources, or other aqueous waste containing Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

13. The method according to claim 1 or 2, wherein the molten metal forms a precipitate, and the precipitate is a Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl precipitate.

14. The method according to claim 13, wherein approximately 50 to 99% of the dissolved metal is recovered as a precipitate from the aqueous solution.

15. The method according to claim 14, wherein the precipitate of the molten metal is purified for secondary use.

16. A method for recovering molten metal from acidic mine drainage, a) A step of removing Fe, b) The step of removing Al, c) The step of removing REE, d) A step of mixing ozone into the acidic mine wastewater stream at a certain rate, thereby forming a precipitate of molten metal, e) A step of separating the precipitate of the molten metal, f) A step of measuring the dissolved metal concentration and pH of the acidic mine wastewater flow, g) A method comprising repeating steps d) to f) until the measured concentration of the dissolved metal no longer changes.

17. The method according to claim 16, wherein Fe is removed by aeration or chemical precipitation.

18. The method according to claim 16 or 17, wherein Al is removed by chemical precipitation at a low pH.

19. The method according to claim 16 or 17, wherein rare earth elements are removed by chemical precipitation at an acidic or neutral pH.

20. A method for purifying or selectively removing dissolved metal from an aqueous solution, a) A step of adjusting the pH of the aqueous solution to a predetermined pH, b) A step of forming a first solid metal fraction by introducing ozone into the aqueous solution to achieve a predetermined oxidation-reduction potential and stirring the aqueous solution for a predetermined time, c) The step of separating the first solid metal fraction, d) A method comprising repeating steps a) to c) for a second or more solid metal fraction.

21. The method according to claim 20, wherein one of the first, second, or more solid metal fractions comprises the molten metal, and the molten metal is one or more of Co, Mn, Ni, Cu, Ag, Cd, Zr, Ce, Os, Ir, Pd, Pt, Rh, Ru, Cr, Fe, Bi, Ga, Sn, and / or Tl.

22. The method according to claim 20 or 21, wherein the predetermined pH is in the range of approximately 0 to approximately 8.

23. The method according to claim 20 or 21, wherein the aqueous solution is brine, wastewater from the mining, oil and gas industry, or leachate obtained from the treatment of ore, secondary source treatment, waste treatment, sludge treatment, precipitate treatment, or recycling of electronic waste, batteries and solar panels.

24. The method according to claim 20 or 21, wherein approximately 50 to 99% of the metal is recovered from the first, second, or more solid metal fractions of the aqueous solution.

Images