Reduction of Chalcopyrite with an Aqueous Reducing Agent to Enable Wet Refining Extraction of Copper

Abstract

Copper concentrate, such as chalcopyrite, is contacted with an aqueous solution containing an acid, and a reducing agent, such as vanadium(II) ions, chromium(II) ions, or zinc tungstoate (HZnW 12 O 40 ). The aqueous solution reduces the copper in the copper concentrate, which can then be dissolved in solution for recovery therefrom or precipitated from solution as copper compounds or elemental copper for recovery as a solid phase product. The solid phase product can then be isolated, dissolved, and further electrowinning to recover the copper product from the copper concentrate. The oxidized reducing agent can be recovered in an electrochemical device with a ferrous reactant. A hydrometallurgical route for converting copper concentrate to copper is potentially cheaper and less polluting than current high temperature smelting processes, and is an advantageous response to environmental and economic pressures for increased copper production.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is an international stage application of PCT / US2021 / 065450, filed December 29, 2021, which claims priority to U.S. Provisional Application No. 63 / 131,838, filed December 30, 2020, and U.S. Provisional Application No. 63 / 294,098, filed December 28, 2021, the entire contents of which are incorporated by reference as if set forth herein.

[0002] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with United States government support under 1644869 awarded by the National Science Foundation. The United States government has certain rights in this invention. [Background technology]

[0003] Renewable energy sources have become more desirable in the 21st century due to the environmental impact and increasing cost of fossil fuels. However, they can require five times more copper than traditional power sources. Copper is highly renewable because its high electrical conductivity translates into efficient transmission of electricity, and its relatively low cost makes it economically advantageous over other metals. Wind and solar power plants require vast amounts of copper to connect components separated by long distances, including energy storage systems and the grid. A solar power system contains approximately 5.5 tons of Cu per MW, and a single wind farm can contain 4 to 15 million pounds of copper. A hybrid vehicle contains approximately 45 kg of copper in its wiring, motor, radiator, and brakes.

[0004] High demand for copper coincides with a rapid decline in copper reserves, resulting in a copper shortage expected in the coming decades. Expanding new copper availability over the coming decades is essential to facilitate the transition to renewable energy technologies.

[0005] The cost of copper production is expected to increase in the coming decades. Researchers predict a global peak in the copper industry by 2050, which is partly due to the high cost of copper production. The development of new processing technologies for copper-containing ores is important to reduce the cost of copper production and expand new copper availability for decades.

[0006] Chalcopyrite (CuFeS2) is the most abundant copper-containing mineral found in nature and accounts for about 70% of the world's copper reserves. However, the high demand for copper coincides with the global peak in copper production, which is due to the depletion of copper reserves and the high costs associated with current copper production technologies. There is interest in the transition from high-temperature smelting to hydrometallurgy for environmentally and economically sustainable copper production.

[0007] CuFeS2 minerals are typically mined, concentrated, and then smelted to produce copper. The high-temperature smelting process is characterized by high investment costs, high operating costs, and the potential release of environmentally harmful by-products such as sulfur dioxide and arsenic. Table 1 shows an overview of the key operating steps and associated costs of the high-temperature smelting process. Ore mining and crushing require the ore to be crushed to the millimeter scale. Ball milling is used to further reduce the particle size to the micron scale. Flotation is used to separate the sulfide mineral phase from the silicate phase. Transportation for smelting is necessary to transport the concentrated ore to overseas smelters. Smelting is required to convert CuFeS2 to Cu, but sulfur dioxide (SO2) and arsenic (As) may be released as by-products. Finally, electrochemical purification is carried out to produce high-quality Cu for sale.

[0008]

Table 1

[0009] The investment costs shown in Table 1 can be converted to indirect operating costs by assuming a capital payback of 12% per year, including such costs. Working capital is assumed to be 10% per ton of Cu per year, so the total investment cost is estimated to be $33,000 per ton of Cu per year. The direct ($2 / kg Cu) and indirect ($4 / kg Cu) costs of copper production add up to $6 / kg Cu, which is close to the selling price.

[0010] Thus, there is considerable interest in pursuing hydrometallurgical processing of CuFeS2 to reduce the cost and environmental impact of future copper production. Hydrometallurgical leaching of CuFeS2 is generally performed using Fe as the oxidant. 3+ Although oxidant diffusion is generally inhibited by the formation of a passivation layer on the mineral surface, disagreement remains regarding the chemical structure of the passivation layer and the mechanism of its formation. In various media, elemental sulfur, disulfides, and polysulfides have been identified on the chalcopyrite surface, all of which likely contribute to passivation. Electrodissolution of CuFeS2 has shown that the range of applied potential affects the chemical phase of the passivation layer. XPS analysis of electrodissolved CuFeS2 revealed that a metal-deficient sulfide film containing cuprous sulfide (Cu-S) and iron sulfide (Fe-S) bonds formed at 0.90 V. SHE It was found to be the most likely phase that passivates the CuFeS2 surface at potentials above 1000 K. Resident bacteria, which increase the oxidation rate of other copper sulfides, do not significantly improve the CuFeS2 oxidation rate. Silver ions may alter the reaction pathway of CuFeS2, which reduces the severity of sulfur passivation. Electrolytic dissolution of CuFeS2 with silver ions has shown the formation of Ag2S in the passivation layer. The formation of Ag2S requires the formation of sulfur vacancies and paired holes, which reduces the passivation of the film and improves the CuFeS2 dissolution rate. Although silver ions are an effective catalyst, their high cost prevents their practical use.

[0011] By converting CuFeS2 into a suitable mineral phase through chemical oxidation, the problems associated with CuFeS2 passivation can be avoided. Studies have shown that CuFeS2 can be converted to chalcocite (Cu2S) using solid copper, sulfur dioxide gas, iron, and aluminum as reducing agents. However, chemical reducing agents typically result in relatively low conversion rates and require fine CuFeS2 particle sizes or high temperatures.

[0012] Alternative methods have been developed for electrochemically reducing CuFeS2 to Cu2S in an acidic aqueous solution. Studies have been conducted to analyze the effects of operating parameters such as acid concentration, CuFeS2 pulp concentration, and temperature. Aluminum cathodes are thought to convert CuFeS2 to Cu2S more efficiently than copper, carbon, or platinum cathode materials, and it has been shown that direct contact between the mineral phase and the cathode is necessary for the reaction to proceed. Reactions 1 and 2 show that CuFeS2 can be electrochemically reduced to Cu2S and subsequently to Cu2O. These reactions have undergone many optimizations by changing the electrolyte, separator, electrode material, and reactor design.

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[0013] Reactions 1 and 2 directly compete with the hydrogen evolution reaction and thus typically operate at a Faradaic efficiency of less than 40%. These slurry reactions also present potential engineering problems such as reactor clogging and electrode fouling.

Summary of the Invention

Means for Solving the Problems

[0014] Some aspects of the present disclosure relate to methods for producing a copper product from a copper concentrate. In some embodiments, the method includes providing a composition comprising the copper concentrate. In some embodiments, the method includes contacting the composition with an aqueous solution comprising one or more chemical reducing agents. In some embodiments, the method includes reacting at least a portion of the copper concentrate with the chemical reducing agents to reduce copper within the copper concentrate. In some embodiments, the method includes isolating a solid-state reaction product, the solid-state reaction product comprising a copper product. In some embodiments, the method includes contacting the solid-state reaction product with an acidic stream to produce a dissolved copper product, the acidic stream comprising one or more acids. In some embodiments, the method includes electrowinning the dissolved copper product and isolating the copper product and the regenerated acid.

[0015] In some embodiments, the step of isolating the solid-phase reaction product comprises isolating a liquid-phase reaction product comprising an oxidized chemical reductant and providing the liquid-phase reaction product to an electrochemical device. In some embodiments, the method comprises reducing the oxidized chemical reductant to a regenerated chemical reductant in the electrochemical device and contacting the regenerated chemical reductant with the composition. In some embodiments, the method comprises isolating a second copper product from the liquid-phase reaction product. In some embodiments, the step of isolating the solid-phase reaction product comprises isolating a gaseous reaction product comprising hydrogen sulfide, contacting the gaseous reaction product with a ferric iron stream to form a ferrous iron effluent stream and an elemental sulfur effluent stream, and regenerating the ferrous iron effluent stream to the electrochemical device.

[0016] In some embodiments, the copper concentrate comprises chalcopyrite. In some embodiments, the acidic stream comprises a concentration of iron(III) sulfate, sulfuric acid, or a combination thereof. In some embodiments, the chemical reducing agent is vanadium(II) ions, compounds containing vanadium(II) ions, chromium(II) ions, compounds containing chromium(II) ions, zinc tungstate (HZnW), or a combination thereof. 12 O40 ) or combinations thereof. In some embodiments, the chemical reducing agent includes vanadium(II) sulfate, chromium(II) chloride, or combinations thereof.

[0017] Some aspects of the present disclosure include providing a composition comprising a concentration of chalcopyrite, and contacting the composition with an acidic aqueous solution comprising one or more acids and one or more chemical reducing agents, wherein the one or more acids include sulfuric acid, hydrochloric acid, or combinations thereof, and the one or more chemical reducing agents include vanadium(II) ions, compounds containing vanadium(II) ions, chromium(II) ions, compounds containing chromium(II) ions, tungstozincic acid (H6ZnW 12 O 40 ) or combinations thereof, reacting the chalcopyrite with the chemical reducing agent to reduce at least a portion of the copper contained therein, separating a solid reaction product stream, a liquid reaction product stream, and a gas reaction product stream, providing the oxidized chemical reducing agent to an electrochemical device, reducing the oxidized chemical reducing agent to a regenerated chemical reducing agent in the electrochemical device, contacting the regenerated chemical reducing agent with the composition, treating the gas reaction product stream with a concentration of ferric iron to produce a sulfur product and a concentration of ferrous iron, regenerating the ferric iron in the electrochemical device, contacting the solid reaction product stream with one or more acids to produce a dissolved copper product stream, and electrowinning the dissolved copper product stream to isolate a copper product and a regenerated acid.

[0018] In some embodiments, the solid reaction product stream includes copper, copper compounds, or combinations thereof, the liquid reaction product stream includes an oxidized chemical reducing agent, and the gas reaction product stream includes H2S. In some embodiments, the acidic aqueous solution has a reducing agent concentration of from about 0.01 M to about 10 M.

[0019] Some aspects of the present disclosure relate to a system for producing copper products from copper concentrate. In some embodiments, the system includes a copper concentrate source, a reduction reactor in communication with the copper concentrate source, a solid-phase product outlet stream in communication with a first product outlet, a dissolution reactor in communication with one or more acid inlet streams and the solid-phase product outlet stream to produce a dissolved copper product stream, and a copper isolation electrolytic extraction reactor in fluid communication with the dissolved copper product stream, the copper isolation electrolytic extraction reactor producing a copper product and a regenerated acidic stream in fluid communication with the dissolution reactor.

[0020] In some embodiments, the reduction reactor includes one or more chemical reducing agents and an acidic aqueous solution including at least a first product outlet. In some embodiments, the copper concentrate includes chalcopyrite. In some embodiments, the chemical reducing agent includes vanadium (II) ions, a compound including vanadium (II) ions, chromium (II) ions, a compound including chromium (II) ions, tungstozincic acid (H6ZnW 12 O 40 ), or a combination thereof. In some embodiments, the chemical reducing agent includes vanadium (II) sulfate, chromium (II) chloride, or a combination thereof. In some embodiments, the acid inlet stream includes a certain concentration of iron (III) sulfate, sulfuric acid, or a combination thereof.

[0021] In some embodiments, the reduction reactor includes a second product outlet. In some embodiments, the system includes a liquid-phase product outlet stream in fluid communication with the second product outlet, a liquid-phase product stream comprising an oxidized chemical reductant, an electrochemical device in fluid communication with the liquid-phase outlet stream, and a regenerated chemical reductant stream produced by the electrochemical device and in fluid communication with the reduction reactor. In some embodiments, the reduction reactor includes a third product outlet. In some embodiments, the system includes a gas-phase product outlet stream in fluid communication with the third product outlet, a gas-phase product outlet stream comprising hydrogen sulfide, a gas-phase processing reactor in fluid communication with the gas-phase product outlet stream, a ferric iron feed stream provided from the electrochemical device to the gas-phase processing reactor, a ferrous iron feed stream provided from the gas-phase processing reactor to the electrochemical device, and an elemental sulfur effluent stream.

[0022] For the purpose of illustrating the invention, the drawings show embodiments of the disclosed subject matter, but the application is not limited to the precise arrangements and instrumentalities shown in the drawings. [Brief explanation of the drawings]

[0023]

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[0024] Referring now to FIG. 1, some embodiments of the present disclosure are directed to a method 100 for producing copper products from copper concentrate. As used herein, the term "copper concentrate" refers to a composition containing a certain concentration of copper from which extraction is desired. In some embodiments, the copper concentrate is a copper-containing mineral or a combination of copper-containing minerals. In some embodiments, the copper concentrate occurs naturally. In some embodiments, the copper concentrate contains a certain concentration of chalcopyrite. In some embodiments, the copper concentrate is artificial. In some embodiments, the copper concentrate is, for example, a waste from an industrial process. As an example, certain mining processes produce waste containing copper, but may have an arsenic content that is too high or an actual copper content that is too low to be processed by conventional processes for the purpose of isolating the copper component. However, the systems of the methods of the present disclosure can extract copper components even from these previously unutilized copper sources.

[0025] Still referring to FIG. 1, some embodiments of the present disclosure include, for example, the production of copper products from copper concentrate by indirect reduction of the concentrate from chalcopyrite. The reduction treatment process consistent with the present disclosure is in contrast to the oxidation treatment that has been more commonly pursued in the literature. At 102, a composition containing copper concentrate is provided. In some embodiments, the composition is provided in any suitable reaction vessel that can contain the chemical reactions described below with respect to various embodiments of the present disclosure. At 104, the composition is contacted with an aqueous solution containing one or more chemical reducing agents. In some embodiments, the reducing agent is configured to reduce the copper in the copper concentrate. In some embodiments, the reducing agent is also configured to be regenerated after oxidation via one or more electrochemical processes. In some embodiments, the chemical reducing agent includes reducing ions, compounds containing reducing ions, or combinations thereof. In some embodiments, the chemical reducing agent includes vanadium (II) ions, compounds containing vanadium (II) ions, chromium (II) ions, compounds containing chromium (II) ions, or combinations thereof. In some embodiments, vanadium (II) sulfate, chromium (II) chloride, zinc tungstate acid (H6ZnW 12 O40 ), or a combination thereof. In some embodiments, the aqueous solution has a concentration of the reducing agent from about 0.01 M to about 10 M.

[0026] In some embodiments, the aqueous solution is acidic. In some embodiments, the aqueous solution comprises one or more acids. In some embodiments, the acid comprises sulfuric acid, hydrochloric acid, or a combination thereof. In some embodiments, the reaction vessel also comprises one or more inert species, such as FeS, silicates, other materials, or a combination thereof.

[0027] At 106, at least a portion of the copper concentrate is reacted with a chemical reducing agent to reduce the copper within the copper concentrate. Without wishing to be bound by theory, the reaction between the aqueous solution and the reducing agent and the copper concentration are shown below. In these exemplary embodiments, chalcopyrite is chemically reduced by the reducing agent. Reactions 3 and 4 show the reaction between CuFeS2, VSO4, and H2SO4. The products Cu2S and Cu 0 is thermodynamically stable under low pH and reducing conditions. These reactions are similar to reactions 1 and 2 above, but use V as the electron carrier to improve electrochemical performance. 2+ Use ions.

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[0028] CuFeS2 concentrate was acidified with V 2+ Upon addition to the solution, a vigorous reaction was observed. The rapid release of gaseous species is consistent with the production of H2S as shown in Reactions 3 and 4. A liquid phase sample was measured by GC-MS, which confirmed the presence of dissolved H2S. Reaction 5 shows the reaction of CrCl2 with hydrochloric acid.

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[0029] Again, when CuFeS2 concentrate is added to an aqueous solution of CrCl2 and hydrochloric acid, a vigorous reaction is observed, which is consistent with the generation of the gas species predicted in Reaction 5. Although the cost of these reducing agents is high relative to copper, the process can be utilized to efficiently regenerate the reducing agent, such as a vanadium redox flow battery, or a similar electrochemical cell, to regenerate V at a high current density. 2+ To regenerate, the process can be utilized. In some embodiments, the reduction reaction occurs uniformly, e.g., throughout the reaction vessel or throughout the copper concentrate. As demonstrated by Reactions 3-5 above, Reaction Step 106 produces a copper product that can be isolated and used, or further processed for use, in any downstream process desired by the user. In some embodiments, the copper product is elemental copper. In some embodiments, the copper product exists as a copper-containing compound and can then be processed to isolate elemental copper therefrom, which will be described later. In some embodiments, at least a portion of the copper product precipitates out of solution during or after Reaction Step 106. In some embodiments, at least a portion of the copper product precipitates out of the solution in the reaction vessel. In some embodiments, at least a portion of the copper product precipitates out of solution as elemental copper. In some embodiments, at least a portion of the copper product precipitates out of solution as a copper compound. In some embodiments, at least a portion of the copper product remains in solution.

[0030] In 108, the solid-phase reaction product is isolated. In some embodiments, the solid-phase reaction product comprises one or more seeds, such as copper products, that precipitate from the solution during or in response to step 106. As described above, in some embodiments, the solid-phase reaction product comprises solid elemental copper, solid copper-containing compounds, or combinations thereof. In some embodiments, the solid-phase reaction product comprises at least a portion of the copper product. In some embodiments, the solid-phase reaction product comprises all of the copper product. In some embodiments, in 110, at least a portion of the solid-phase reaction product is contacted with an acidic stream. The acidic stream is effective to solubilize the copper product in the solid-phase reaction product and produce a dissolved copper product. In some embodiments, the acidic stream comprises one or more acids. In some embodiments, the acidic stream comprises a certain concentration of iron(III) sulfate, sulfuric acid, or combinations thereof. In some embodiments, the solid-phase reaction product comprises inorganic inerts. Without wishing to be bound by theory, the inerts mostly comprise pyrite and silicates, although there may be compounds containing trace amounts of rhenium and arsenic. Recovering the rhenium-containing inert material for rhenium production can be economically advantageous, and recovering the arsenic-containing inert material for conversion to a benign form can be environmentally advantageous.

[0031] In 112, the dissolved copper product is electrowon, for example, provided to an electrowinning reactor to isolate the copper product and produce a regenerated acid. In some embodiments, the regenerated acid is regenerated for use during contacting step 110.

[0032] Referring further to FIG. 1, in 114, the liquid-phase reaction product is isolated. In some embodiments, the liquid-phase reaction product is isolated in 114 as a result of the solid-phase reaction product being isolated in step 108, as described above. In some embodiments, the liquid-phase reaction product comprises an oxidative chemical reductant, such as V 3+ and / or Cr 3+ In some embodiments, the liquid phase comprises Fe in sulfuric acid 2+It also includes ions. In some embodiments, the high solubility of the redox agent can be utilized for its separation from Fe 2+ In some embodiments, a biological reactor is used to oxidize V 3+ and Fe 2+ and thus facilitate their separation. In some embodiments, at 116, the second copper product is isolated from the liquid-phase reaction product by any suitable means.

[0033] At 118, the liquid-phase reaction product is fed to an electrochemical device. At 120, the oxidized chemical reducing agent is reduced in the electrochemical device. In some embodiments, the electrochemical device contains a certain concentration of ferrous iron or other reactant effective to assist in reducing the oxidized chemical reducing agent. In some embodiments, the oxidized chemical reducing agent is reduced to a regenerated chemical reducing agent. Without wishing to be bound by theory, in an exemplary embodiment, the cathode reaction of the electrochemical device is given by Reaction 6, while the anode reaction is given by Reaction 7.

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[0034] Vanadium species membrane crossover can be mitigated by the application of high current density and is also desirable to achieve a high reaction rate. Iron species crossover can potentially reduce the efficiency of the electrochemical cell, but may not cause long-term damage due to downstream separation of iron. At 122, the regenerated chemical reducing agent contacts the composition, for example, in a reaction vessel.

[0035] Referring further to Figure 1, at 124, the gaseous reaction product is isolated. In some embodiments, the solid-phase reaction product is isolated in step 108, the liquid-phase product is isolated in step 114, or as a result of a combination thereof, the gas-phase reaction product is isolated at 124. In some embodiments, the gaseous reaction product comprises hydrogen sulfide. In some embodiments, at 126, the gaseous reaction product is contacted with a second iron stream. Without wishing to be bound by theory, in an exemplary embodiment, the gaseous reaction product is treated with ferrous ions for the recovery of protons by the following reaction 8.

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[0036] In some embodiments, the protons generated by this reaction are transported across the separator of the electrochemical device and thus recovered. In some embodiments, the second iron stream is provided from the electrochemical device. In some embodiments, the contacting step 126 forms a first iron effluent stream and an elemental sulfur effluent stream. In some embodiments, the first iron effluent stream is recycled to the electrochemical device. In some embodiments, the sulfur product in the elemental sulfur effluent stream is recycled for use in one or more downstream processes. In some embodiments, the sulfur product in the elemental sulfur effluent stream is discarded.

[0037] Referring now to Figure 2, some embodiments of the present disclosure are directed to a system 200 for producing copper products from copper concentrate. In some embodiments, system 200 includes a source 202 of copper concentrate. As described above, in some embodiments, the copper concentrate from the source is natural, artificial, or a combination thereof. In some embodiments, the copper concentrate comprises a certain concentration of chalcopyrite, e.g., waste from an industrial process, or a combination thereof.

[0038] In some embodiments, system 200 includes a reduction reactor 204, e.g., the reaction vessel described above with respect to method 100. In some embodiments, the reduction reactor has one or more inputs 204A and one or more outputs 204B. In some embodiments, system 200 is configured to provide copper concentrate from source 202 to reduction reactor 204. In some embodiments, reduction reactor 204 is in communication with copper concentrate source 202, e.g., via input 204A’. In some embodiments, reduction reactor 204 includes an aqueous solution 206. As described above, in some embodiments, aqueous solution 206 includes one or more chemical reducing agents. In some embodiments, the chemical reducing agent includes reducing ions, a compound containing reducing ions, or a combination thereof. In some embodiments, the chemical reducing agent includes vanadium (II) ions, a compound containing vanadium (II) ions, chromium (II) ions, a compound containing chromium (II) ions, or a combination thereof. In some embodiments, the chemical reducing agent includes vanadium (II) sulfate, chromium (II) chloride, tungstozincic acid (H6ZnW 12 O 40 ), or a combination thereof. In some embodiments, aqueous solution 206 has a reducing agent concentration of from about 0.01 M to about 10 M. In some embodiments, aqueous solution 206 is acidic. In some embodiments, the aqueous solution includes one or more acids. In some embodiments, the acid includes sulfuric acid, hydrochloric acid, or a combination thereof.

[0039] In some embodiments, system 200 is configured to provide a chemical reducing agent to reduction reactor 204. In some embodiments, the chemical reducing agent is provided from a source 208 of chemical reducing agent, e.g., at input 204A. In some embodiments, at least a portion of the chemical reducing agent in aqueous solution 206 is in the form of a recycle stream generated by system 200 itself via one or more other components. This is described in detail below. In some embodiments, system 200 is configured to provide one or more acids to reduction reactor 204. In some embodiments, the acid is provided from a source 210 of acid, e.g., at input 204A. In some embodiments, at least a portion of the acid in aqueous solution 206 is in the form of a recycle stream provided by system 200 itself via one or more other components.

[0040] As described above, reduction reactor 204 is configured to react at least a portion of the copper concentrate with a chemical reducing agent to reduce copper within the copper concentrate and to separate a copper product from the copper concentrate. In some embodiments, at least a portion of the copper product precipitates from the solution within reduction reactor 204. In some embodiments, at least a portion of the copper product precipitates from the solution as elemental copper. In some embodiments, at least a portion of the copper product precipitates from the solution as a copper compound. In some embodiments, at least a portion of the copper product remains in solution.

[0041] Still referring to FIG. 2, system 200 includes a solid product outlet stream 212. In some embodiments, solid product outlet stream 212 communicates with reduction reactor 204 via an outlet, e.g., a first product outlet 204B', and is removed therefrom. As described above, in some embodiments, solid product outlet stream 212 includes solid elemental copper, solid copper-containing compounds, or combinations thereof. In some embodiments, solid product outlet stream 212 includes at least a portion of the copper product. In some embodiments, solid product outlet stream 212 includes all of the copper product.

[0042] In some embodiments, the solid-phase reaction product stream 212 is provided to the dissolution reactor 214. In some embodiments, the system 200 is configured to provide one or more acids to the dissolution reactor 214. In some embodiments, the dissolution reactor 214 is in communication with one or more acid inlet streams 216. As described above, at least a portion of the solid-phase product outlet stream 212 contacts, for example, an acid from the acid inlet stream 216. The acid is effective to solubilize the copper product in the solid-phase product outlet stream 212 and produce a dissolved copper product stream 218. In some embodiments, the acid inlet stream 216 comprises a certain concentration of iron(III) sulfate, sulfuric acid, or a combination thereof. In some embodiments, the dissolved copper product stream 218 is sent to an electrowinning reactor 220, which produces and / or separates a copper product 221 and a regenerated acid stream 222. In some embodiments, at least a portion of the regenerated acid stream 222 is fed back to the dissolution reactor 214 for use in dissolving the solid-phase product outlet stream 212 within that reactor.

[0043] Referring further to FIG. 2, the system 200 includes a liquid-phase product outlet stream 224. In some embodiments, the liquid-phase product outlet stream 224 communicates with and is removed from the reduction reactor 204 by an outlet, for example, a second product outlet 204B. As described above, in some embodiments, the liquid-phase product outlet stream 224 comprises an oxidative chemical reducing agent, for example, V 3+ and / or Cr 3+ . In some embodiments, the liquid phase also comprises Fe 2+ ions in sulfuric acid. In some embodiments, iron(II) ion species, a second copper product, for example, a dissolved copper product, or a combination thereof are removed from the liquid-phase product outlet stream via one or more streams 225. In some embodiments, the high solubility of the redox agent can be utilized for its separation from Fe 2+ . In some embodiments, the liquid-phase product outlet stream 224 comprises a certain concentration of dissolved copper product, which can be isolated and recovered, for example, via an electrowinning process.

[0044] In some embodiments, at least a portion of the liquid phase product outlet stream 224 is supplied to the electrochemical device 226. As described above, the electrochemical device 226 contains a concentration of iron or other reactants effective to assist in reducing the oxidized chemical reductant. In some embodiments, the oxidized chemical reductant is reduced to a regenerated chemical reductant and removed from the electrochemical device 226 as the regenerated chemical reductant stream 228. In some embodiments, the regenerated chemical reductant stream 228 is returned to the reduction reactor 204, for example, at input 204A. In some embodiments, at least a portion of the ferrous iron is oxidized and removed as the ferric iron feed stream 230. This will be described in more detail below.

[0045] Referring further to FIG. 2, the system 200 includes a gas phase product outlet stream 232. In some embodiments, the gas phase product outlet stream 232 communicates with and is removed from the reduction reactor 204 by an outlet, for example, the third product outlet 204B. As described above, in some embodiments, the gas phase product outlet stream 232 contains hydrogen sulfide gas. In some embodiments, the ferric iron feed stream 230 and the gas product outlet stream 232 are combined in the gas treatment reactor 234. The reaction between stream 230 and stream 232 forms a ferrous iron effluent stream 236 and an elemental sulfur effluent stream 238. In some embodiments, the ferrous iron effluent stream 236 is regenerated in the electrochemical device 226 for use in reducing the oxidized chemical reductant. In some embodiments, the sulfur product in the elemental sulfur effluent stream 238 is regenerated for use in one or more downstream processes. In some embodiments, the sulfur product in the elemental sulfur effluent stream 238 is discarded.

[0046] As will be apparent to those skilled in the art, a system consistent with embodiments of the present disclosure may include any additional miscellaneous components, such as conduits, power supplies, controllers, product collection reservoirs, etc., to facilitate the reduction of chalcopyrite and the isolation of copper products.

[0047] Examples In an exemplary embodiment, a sample of chalcopyrite mineral concentrate was provided. The sample was analyzed by energy dispersive X-ray diffraction and found to have a composition according to Table 2 below. [Table 2]

[0048] In addition to the concentrate shown in Table 2, three other versions of concentrate were provided with varying amounts of copper and other inerts. The disclosed process was determined to be compatible with concentrates of a wide range of purity. The CuFeS2 concentrate was sieved (-140 +270 mesh) to limit particle size to 53-106 μm. The concentrate was then rinsed with deionized water and 1 M H2SO4 to remove soluble iron and copper ions generated during natural concentrate oxidation during transport and storage.

[0049] In a first exemplary embodiment, CuFeS2 concentrate pulp densities of 39, 78, 117, or 234 g / L were added to a 250 mL Erlenmeyer flask containing 25 mL of a solution containing 1 M VSO4 and 4 M H2SO4. For other experiments, CuFeS2 concentrate pulp densities of 39 g / L were added to solutions containing 1 M VSO4 and various H2SO4. The reactions were carried out in a hood with rapid evolution of H2S gas. 100 μL samples of the liquid phase were taken at 0, 5, 10, 20, 40, and 60 minutes, after which Fe 2+ and Cu + Dilution was performed to measure the content. After reduction, the mineral particles were filtered from the solution and air-dried before characterization.

[0050] The release of iron and copper ions from CuFeS2 into solution during reduction was measured using an iCE3300AAS. The characteristic wavelengths for iron and copper measurements were 248.3 nm and 324.8 nm, respectively. Standards ranging from 0 to 4 ppm were measured immediately before the samples to construct a linear (R2 > 0.995) calibration curve.

[0051] The bulk mineral phases of the reaction products were measured using a PANalytical XPert3 powder XRD. The XRD was operated with filtered Empyrean Cu Ka radiation (k = 0.15418 nm), a tube voltage of 45 kV, and a current of 40 mA. The mineral products were placed on a silicon crystal zero diffraction plate (MTI Corporation) and adhered in place with Apiezon grease. The sample was continuously scanned in the range of 10 - 100° with a step size of 0.0065° on a spinning plate with a rotation time of 2.0 seconds. A PIXcel1D detector was used to record the peak intensities for subsequent analysis of the mineral composition.

[0052] Images of the mineral products after the reaction were captured using a Zeiss Sigma VP SEM. The SEM-EDS analysis was carried out at an acceleration potential of 6 kV and a base pressure of about 1×10 -5 torr. The samples were supported on carbon tape and coated with gold using a Cressington 108 Auto Sputter Coater. Sputtering was carried out for 20 seconds under a flow of argon gas at a pressure of 0.1 mbar to obtain a 1 nm coating of AuPd. A Bruker XFlash Detector was used for EDS analysis to analyze the elemental composition.

[0053] Samples of the mineral products were digested in aqua regia for copper extraction, and equivalent samples of the mineral products were leached in a solution containing 0.5 M Fe2(SO4)3 in 1 M H2SO4. The percentage of copper released was determined by the ratio of copper extracted by the two leachates.

[0054] H2S gas was rapidly released and qualitatively measured with a Sensorcon detector. The gas release occurred immediately after the addition of the concentrate and ended within a few minutes of the reaction time. The liquid phase samples were measured by gas chromatography - mass spectrometry (GC-MS) to confirm the presence of dissolved H2S. No other gases were detected. H2S gas can be oxidized to harmless S 0 in an industrial process.

[0055] Figure 3 shows the Fe released from CuFeS concentrate during its direct electrochemical reduction (reactions 1-2) and its reduction with VSO (reactions 3-4). 2+ The FeS2 in the concentrate is inert, so the Fe 2+ The measurement of Fe from CuFeS2 concentrate was experimentally confirmed to be a suitable proxy for CuFeS2 conversion. The figure shows that the use of an electron carrier is kinetically beneficial for the direct electrochemical reduction of CuFeS2 concentrate. VSO4 was able to convert Fe from CuFeS2 concentrate within 60 min despite a relatively high loading of 39 g / L. 2+ This allows for 100% release of the concentrate. Direct electrochemical reduction requires extended periods of time to achieve complete conversion of the concentrate due to the tendency of the hydrogen evolution reaction to occur at the slurry electrode. The direct electrochemical reduction results shown in Figure 3 utilized the same experimental procedure presented in the literature with an applied current density of 10 mA / cm.

[0056] Figure 4 shows the X-ray diffraction characteristics of the mineral products immediately after reduction leaching with VSO4. The main peaks in the unreacted CuFeS2 concentrate sample correspond to CuFeS2, FeS2, and SiO2, which is consistent with the mineralogy shown in Table 2. The peaks corresponding to CuFeS2 decreased in the spectrum of the reacted mineral products, and peaks corresponding to the mineral products appeared. The copper-bearing solid CuFeS2 was converted to Cu2S and Cu 0 This is consistent with reactions 3 and 4. XRD spectra confirmed that FeS2 and silicates were inactive during reductive leaching with VSO4.

[0057] Figure 5 shows the Cu content of the mineral products during the air drying process. 0 The sulfuric acid still coated on the sample reacted with air as shown in reaction 9 to produce CuSO4 5H2O. Without wishing to be bound by theory, the Cu 0 It is hypothesized that galvanic interactions between vanadium and FeS2 may also occur in vanadium-containing systems and have secondary effects.

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[0058] Figures 6A - 6D show the characteristics of the mineral products after 60 minutes of reaction between 1M VSO4, 4M H2SO4, and CuFeS2 concentrate at various filling amounts (Reactions 3 and 4 above), and after air drying (Reaction 9). Figure 6A shows an optical microscope image of the mineral product obtained with a Keyence VHX - 5000 microscope. The appearance of the mineral product was significantly different from that of the unreacted CuFeS2 concentrate. The mineral product had a blue appearance that could indicate CuSO4·5H2O. Figure 6B shows the SEM - EDS of the mineral product after 60 minutes of reaction between 1M VSO4, 4M H2SO4, and concentrates at various filling amounts. The unreacted chalcopyrite concentrate sample showed peaks corresponding to the characteristic energies of C, O, Fe, Cu, Al, Si, and S, which is consistent with the mineralogy shown in Table 2. The presence of the C peak is an artifact of placing the sample on carbon tape prior to analysis. The reacted sample showed a decrease in the peaks of Fe 2+ and S due to the release of Fe ions into the solution and the release of H2S as a gas. The reacted sample also showed a decrease in the Al and Si peaks due to the decrease in the mass fraction within the sample. The main peaks of the reacted sample were Cu, S, and O, which is consistent with the formation of CuSO4·5H2O. The elongation of the O peak in the spectrum is consistent with this product. Without wishing to be bound by theory, the absence of a V peak indicates that V does not precipitate as a solid phase during the progress of the reaction.

[0059] Figure 6C shows the XRD spectrum of the mineral product after 60 minutes of reaction between 1M VSO4, 4M H2SO4, and concentrates at various filling amounts. The main peaks of the unreacted CuFeS2 concentrate sample corresponded to CuFeS2, FeS2, and SiO2, which is consistent with the mineralogy shown in Table 2. The peak corresponding to CuFeS2 decreased in the spectrum of the reacted mineral product, and peaks corresponding to the mineral product appeared. Figure 6D shows the region of the XRD spectrum used to identify the mineral product. The XRD spectrum of the mineral product was consistent with the formation of CuSO4·5H2O, which was consistent with the SEM - EDS dataset.

[0060] Figure 7 shows that the X-ray diffraction spectrum consistent with CuSO4·5H2O was reproducible for tests conducted between 1M VSO4, 39 g / L of concentrate, and initial H2SO4 concentrates of 0.5M and 1M. The pH of the solution after the reaction was less than 1 for all of these experiments, indicating that these reactions were not pH-limited. For none of these conditions was the precipitation of vanadium salts from the solution observed, indicating that this process has the potential for high vanadium recovery and reuse. The pH of these solutions is less than 1, suggesting that these reactions are not pH-limited. Vanadium redox flow batteries (VRFBs) typically operate at H2SO4 concentrations in the range of 2 - 4M, and thus, the downstream vanadium(II) regeneration process can benefit from relatively high acid concentrations.

[0061] Figure 8A shows the percent of Fe released as a function of time for slurries containing 1M VSO4, 4M H2SO4, and CuFeS2 concentrate loadings of 39, 78, 117, and 234 g / L. The figure shows that approximately 100% of the Fe was released from CuFeS2 during reduction, which is consistent with Reactions 3 and 4. Without wishing to be bound by theory, the incomplete release of Fe for the experiments conducted at concentrate loadings of 117 g / L and 234 g / L suggests the complete utilization of V. 2+ of the slurry containing 1M VSO4, 4M H2SO4, and CuFeS2 concentrate loadings of 39, 78, 117, and 234 g / L. The figure shows that approximately 100% of the Fe 2+ was released from CuFeS2 during reduction, which is consistent with Reactions 3 and 4. Without wishing to be bound by theory, the incomplete release of Fe for the experiments conducted at concentrate loadings of 117 g / L and 234 g / L suggests the complete utilization of V. 2+ of the slurry containing 1M VSO4, 4M H2SO4, and CuFeS2 concentrate loadings of 39, 78, 117, and 234 g / L. The figure shows that approximately 100% of the Fe 2+ was released from CuFeS2 during reduction, which is consistent with Reactions 3 and 4. Without wishing to be bound by theory, the incomplete release of Fe for the experiments conducted at concentrate loadings of 117 g / L and 234 g / L suggests the complete utilization of V.

[0062] Figure 8B shows the results of the subsequent extraction of Cu from the mineral products by reacting for 60 minutes in a solution containing 0.5M Fe2(SO4)3 in 1M H2SO4. Reaction 10 shows the dissolution of CuSO4·5H2O, which was characteristic of the final mineral product of the reaction between 1M VSO4, 4M H2SO4 and 39 g / L of chalcopyrite concentrate. 2+ of the slurry containing 1M VSO4, 4M H2SO4, and CuFeS2 concentrate loadings of 39, 78, 117, and 234 g / L. The figure shows that approximately 100% of the Fe

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[0063] The results showed that virtually all of the Cu was removed from the 39 g / L mineral product within minutes. 2+ The 39 g / L sample was also solubilized in 1M H2SO4. The aqueous solution can proceed to solvent extraction and electrowinning for the production of metallic copper. Without wishing to be bound by theory, the incomplete copper extraction due to the higher pulp density is partly related to the incomplete conversion of CuFeS2 indicated by the XRD analysis above. CuFeS2 concentrate does not contain Cu. 2+ was hardly extracted, thus indicating that the reduction treatment directly leads to the extraction of Cu.

[0064] Figure 9A shows that for a concentrate loading of 39 g / L and H2SO4 concentrations of 0.5 M, 1 M, and 4 M, approximately 100% Fe 2+ Figure 9B shows that the mineral product reacts completely with a solution containing 0.5 M Fe(SO) in 1 M HSO for complete recovery of copper. These results indicate that the reduction process will not depend on acid concentration as long as a sufficient number of protons are available to drive the reaction.

[0065] In a second exemplary embodiment, CuFeS2 concentrate pulp densities of 39, 78, 117, or 234 g / L were added to a 250 mL Erlenmeyer flask containing 25 mL of a solution containing 1 M CrCl2 and 4 M HCl. For other experiments, 39 g / L of CuFeS2 concentrate pulp densities were added to solutions containing 1 M CrCl2 and various hydrochloric acid concentrations. Third, for other tests, 39 g / L of CuFeS2 concentrate pulp densities were added to solutions containing 1 M CrCl2, 4 M HCl, and various concentrations of FeCl2. As shown in Figure 10, the reaction was carried out in a hood due to the rapid evolution of H2S gas. 100 μL samples of the liquid phase were taken at 0, 5, 10, 20, 40, and 60 minutes, followed by FeCl2. 2+ and Cu + Dilution was performed to determine the content. After reduction, the mineral particles were filtered from the solution and air-dried before characterization.

[0066] Using the iCE3300AAS, the release of Fe 2+ and Cu + from CuFeS2 during reduction into the solution was measured. The characteristic wavelengths for iron and copper measurements were 248.3 nm and 324.8 nm, respectively. Standards in the range of 0 - 4 ppm were measured immediately before the samples in order to construct a linear (R2>0.995) calibration curve.

[0067] The bulk mineral phases of the reaction products were measured using a PANalytical XPert3 powder XRD. The XRD was operated with filtered Empyrean CuKa radiation (k = 0.15418 nm), a tube voltage of 45 kV, and a current of 40 mA. The mineral products were placed on a silicon crystal zero diffraction plate (MTI Corporation) and adhered in place with Apiezon grease. The sample was continuously scanned in the range of 10 - 100° with a step size of 0.0065° on a spinning plate with a rotation time of 2.0 s. A PIXcel1D detector was used to record the peak intensities for subsequent analysis of the mineral composition.

[0068] The elemental composition of the reaction product surface was measured using a PHI5500XPS equipped with an Alx source. The base pressure of the chamber was about 1×10 -8 torr. The sample was supported on carbon tape.

[0069] Images of the mineral products after the reaction were captured using a Zeiss Sigma VP SEM. The SEM-EDS analysis was performed at an acceleration potential of 6 kV and a base pressure of about 1×10 -5 torr. The sample was supported on carbon tape and coated with gold using a Cressington 108 Auto Sputter Coater. Sputtering was carried out for 20 s under an argon gas flow at a pressure of 0.1 mbar to obtain a 1 nm coating of AuPd. A Bruker XFlash Detector was used for EDS analysis to analyze the elemental composition.

[0070] A sample of the mineral product was digested in aqua regia for complete copper extraction, and an equivalent sample of the mineral product was leached in a solution containing 0.5 M Fe2(SO4)3 in 1 M H2SO4. The percent copper released was determined by the ratio of the copper extracted by the two leachates.

[0071] Figure 10 shows photographs of the reaction between 1 M CrCl, 4 M HCl, and 78 g / L CuFeS concentrate after 0, 2, 3, 5, and 60 seconds of reaction time. The images show the rapid evolution of H2S gas, which was measured qualitatively using a Sensorcon detector. Gas evolution occurred immediately after the addition of the concentrate and was complete within 1 minute of reaction time. Liquid-phase samples were measured by gas chromatography-mass spectrometry (GC-MS), confirming the presence of dissolved H2S in similar experiments.

[0072] The generation of gaseous H2S is due to Fe 2+ Consistent with the release of ions into solution, consistent with reaction 5 above. Figure 11A shows the released Fe for slurries containing 1 M CrCl, 4 M HCl, and CuFeS concentrate loadings of 39, 78, 117, and 234 g / L. 2+ The percentage of Fe is shown as a function of time. For CuFeS2 concentrate loadings of 39, 78, and 117 g / L, approximately 100% of Fe 2+ The reaction rate was rapid, considering that Fe was released from CuFeS2 within 5 min. 2+ The release of Cr was limited to a CuFeS2 concentrate loading of 234 g / L. 2+ Without wishing to be bound by theory, the full utilization of Fe in excess of 100% 2+ Measurement of emissions may represent a slight error in estimating the composition shown in Table 2 due to both the error in XRD quantification and the sieving of the concentrate within 53-106 μm. Experiments were performed while purging the reactor headspace with argon and similar results were observed, suggesting that the small amount of oxygen present in the system may have contributed to the Cr content for the experiments shown. 2+ It was shown that the reaction did not oxidize Cu to a significant level. +release was measured, but quantitative results for the precipitation of Cu + ions from the solution did not match. The pH of the solution after the reduction experiment was less than zero, indicating that these reactions were not pH-limited.

[0073] Figure 11B shows the percent of Fe 2+ released as a function of time for slurries containing 1 M of CrCl2, 39 g / L of CuFeS2 concentrate, and initial HCl concentrations of 0 M, 0.5 M, 1 M, and 4 M. The pH of the solution after the reduction step was approximately 2.5 for slurries with initial HCl concentrations of 0 M, 0.5 M, and 1 M, indicating that these reactions were pH-limited. The pH of the solution after the reduction step may be utilized to facilitate the separation between Fe 2+ and Cr 3+ and may be desirable prior to the reduction of Cr 3+ to Cr 2+ by an electrolysis unit. According to these results, protons are suggested to be in a stoichiometric amount greater than that of CuFeS2, which is consistent with Reaction 5. Experiments conducted at initial HCl concentrations of 2 M and 3 M found that the pH was not limited.

[0074] Figure 12 shows images of the mineral products after 60 minutes of reduction by Cr 2+ ions obtained with a Keyence VHX-5000 microscope. Although not wishing to be bound by theory, the results indicate that the mineral products are affected by the filling amount of the CuFeS2 concentrate. A CuFeS2 filling amount of 39 g / L produced a green product consistent with the appearance of CuCl and, similarly, other potential Cu-Cl complexes. Examination of the characteristics of various mineral products has shown that they result in different amounts of copper recovery. Mineral products after reaction with various HCl concentrations showed the same trend in appearance.

[0075] Figure 13 shows XRD spectra for various chalcopyrite concentrate filling amounts after reaction with Cr 2+ ions, and Figure 14 shows Cr 2+Figure 1 shows the XRD spectra for the mineral samples after reaction with ions and various initial HCl concentrations. The main peaks of the unreacted CuFeS2 concentrate were consistent with CuFeS2, FeS2, and SiO2, as shown in Table 2. The relative intensity of the peaks associated with CuFeS2 in the reaction mineral products decreased, which is consistent with the Fe2+ content measured by AAS. 2+ The spectra were consistent with the release of CuCl. At higher CuFeS2 conversions, peaks associated with reaction products appeared. The primary mineral product was determined to be copper chloride (CuCl) from the spectrum. Secondary products, such as Cu2(OH)3Cl, were consistent with the spectrum. Reaction 11 shows the precipitation of CuCl from solution, the primary product formed. Reaction 11 is shown for simplicity; however, the chemical reaction occurring is more complex, and various Cu-Cl complexes may precipitate. The precipitation of CuCl from a solution containing 4M HCl was unexpected, considering the Cl / Cu molar ratio was 36 in the system. However, the Cl / Cr molar ratio was 6, and Cl - and Cr 3+ The complex formed between Cu + Cl available to stabilize - The number of Cu ions in the solution after 60 minutes of reduction can be reduced. + The concentration is approximately 0.07 M, close to the solubility limit of 0.233 M reported in 2 M HCl in the literature. 36 Experiments performed with a concentrate loading of 39 g / L and an acid concentration of 4 M HCl showed that 40% of the copper in the system was dissolved in Cu. + It is estimated that 60% remained in the bulk solution as HCl and 60% precipitated from the solution.

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[0076] XRD data combined with AAS data indicate that FeS2 and silicate were inert during the reduction process. Experiments were conducted among 39 g / L CuFeS2 concentrate, 1 M CrCl2, 4 M HCl, and initial ferrous chloride (FeCl2) of 0, 0.5 M, 1 M, and 2 M. Although not wishing to be bound by theory, the reduction method was judged to be able to withstand an initial FeCl2 concentration of 1 M or less. Fe 2+ precipitated from the solution due to the tests conducted at an initial FeCl2 concentration of 2 M.

[0077] Figure 15 shows the SEM results of the mineral product after reacting with 1 M CrCl2 and 4 M HCl for 60 minutes. The mineral product develops some mossy features that may be related to the growth of CuCl. Figure 16 shows Cr 2+ EDS results of the mineral sample after reduction by Cr ions. The unreacted CuFeS2 concentrate sample shows peaks corresponding to Cu, Fe, S, Si, and O. The reacted sample shows a decrease in Fe and S peaks, which is consistent with the release of Fe 2+ into the solution and the release of H2S as a gas. The small S peak present in the 39 g / L sample may be related to the presence of unreacted FeS2 in the mineral product. The reacted sample also shows the appearance of a Cl peak, which is consistent with the formation of CuCl. The Cu peak extends for the reacted sample due to an increase in the mass fraction of Cu within the sample. No peak corresponding to Cr is observed in the spectrum, indicating that the presence of Cr in the sample is negligible. The sample was digested in aqua regia, and the mass fraction of Cr in the sample was estimated to be 1 - 3%. Although not wishing to be bound by theory, the presence of chromium is considered to be an artifact of the procedure used to filter and dry the mineral product.

[0078] Figures 17A - 17B show the XPS spectra of Cu (Figure 17A) and Cl (Figure 17B) for the mineral sample after reduction by Cr 2+ ions. Cr atoms are not observed on the mineral product, further indicating that the sample does not contain chromium. Fe and S are not observed on the surface of the mineral product, which is Fe 2+This is consistent with the release of H2S from the particle surface into the liquid phase. The absence of a sulfur passivation layer may explain the rapid kinetics of the reduction reaction. Various copper peaks indicate the presence of several copper-containing products. For example, peaks at binding energies of 944 and 935 eV are assigned to Cu2(OH)3Cl and CuCl, respectively. The Cu scan also shows an observable shift in binding energy from the CuFeS2 concentrate standard. The appearance of a Cl peak in the reacted sample is consistent with the formation of a Cu-Cl complex.

[0079] Figure 18 shows the Cu content of the mineral products with 0.5M Fe2(SO4)3. 2+ Reaction 12 shows the extraction of Fe 3+ The leaching reaction of CuCl by the oxidizing agent is shown, which is complete within a few minutes.

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[0080] The results showed that virtually all of the Cu was removed from the 39 g / L mineral product within minutes. 2+ This shows that CuFeS2 can be extracted from the CuFeS2 concentrate. In an experiment not shown, a 39 g / L sample was solubilized in 1 M H2SO4. The aqueous solution can proceed to solvent extraction and electrowinning for the production of metallic copper. Without wishing to be bound by theory, the incomplete copper extraction due to the higher pulp density is at least partially related to the incomplete conversion of CuFeS2 shown in Figures 11A-11B. Additionally, intermediates that may be formed, such as Cu2(OH)3Cl, may be resistant to copper leaching and may be undesirable. CuFeS2 concentrate may not contain Cu. 2+ was hardly extracted, indicating that the reduction treatment directly leads to the extraction of Cu.

[0081] The disclosed methods and systems advantageously provide a transformative hydrometallurgical process to reduce the cost of copper production, thereby sustaining copper use throughout the global transition to renewable energy technologies. These embodiments enable hydrometallurgical production of copper, which is more environmentally and economically sustainable than the current state of the art. Hydrometallurgical processing is preferred and used for other copper mineral deposits, such as copper oxide. The focus of the hydrometallurgical process is the reduction of chalcopyrite, as opposed to the oxidation treatments more commonly pursued in the literature. Without wishing to be bound by theory, chemical reduction of CuFeS2 is advantageous at least because it avoids the hydrogen evolution reaction and avoids the engineering challenges associated with slurry electrodes. While the cost of vanadium and chromium is high relative to copper, VRFBs or iron-chromium flow batteries (ICFBs) offer the potential for V at high current densities. 2+ or Cr 2+ 1M H2SO4 and 1.5M Fe in 1M H2SO4 can be utilized to efficiently regenerate 3+ The mineral product was leached with a solution containing 2,3-dichloro-1,4-dimethyl-2,5-trimethyl-1,6-dichloro-2,7-dione, and demonstrated to result in complete copper extraction.

[0082] The process flow diagram and associated techno-economic analysis suggest that reduction of chalcopyrite with aqueous reductants can compete with pyrometallurgical specifications for copper production. Table 3 shows the investment and operating costs for the steps in the hydrometallurgical process. The direct ($3.1 / Cu kg) and indirect ($2.4 / Cu kg) costs of copper production total $5.5 / Cu kg, which is lower than the estimated costs for the pyrometallurgical process. [Table 3]

[0083] The reduction and dissolution reactor was assumed to have the same investment and operating costs as a solvent extraction plant, including the costs of mixers, pumps, and storage tanks. This assumption was reasonable since the fast kinetics of the reaction resulted in a relatively small reactor volume. The investment cost of the electrochemical device was estimated from the reported scale-up costs of VRFBs. It was estimated that a 20 MW VRFB would be required to match the copper ore output of a typical refinery processing 4,000 tons of CuFeS2 concentrate per day. For these calculations, the mass fraction of the concentrate was assumed to be 0.3 and the nominal voltage of the electrochemical cell was assumed to be 1.35 V. The operating cost of the electrochemical device was estimated from the industrial cost of electricity, assuming that 1 mole of vanadium was lost for every 20 moles of copper produced. The operating cost of the electrochemical device may vary depending on the quality of vanadium / iron separation and the selling price of V2O5.

[0084] Figure 19 shows the estimated energy requirements for the pyrometallurgical, electrorefining, and hydrometallurgical routes for Cu production after the ore has been mined and concentrated. The pyrometallurgical route has the highest energy requirement of approximately 13 kJ / lb of Cu, which correlates with a significant amount of CO2 emissions. The electrorefining route has a similar energy requirement, partly due to the high energy requirement of the electrochemical cell. The electrochemical cell was assumed to operate at a cell potential of 2.5 V and a Faradaic efficiency of 40% to estimate its energy requirement. The hydrometallurgical route for Cu production is estimated to use approximately 8 kJ / lb of Cu, which represents a significant reduction in global CO2 emissions. The electrochemical cell was assumed to operate at a cell potential of 1.35 V and a Faradaic efficiency of 95% to estimate its energy requirement. Also, the V / Fe separation step was assumed to have the same energy requirement as conventional solvent extraction.

[0085] As described above, the global mining industry is interested in the hydrometallurgical route for converting chalcopyrite to copper due to environmental and economic pressures. Embodiments of the present disclosure are potentially less expensive and less polluting than current pyrometallurgical processes and also enable an increase in domestic copper production in the United States.

[0086] Although the present invention has been described and illustrated with respect to its exemplary embodiments, it should be understood by those skilled in the art that various other changes, omissions, and additions may be made therein and thereto without departing from the spirit and scope of the present invention.

Claims

1. A method for producing a copper product from copper concentrate, comprising: providing a composition comprising copper concentrate; contacting the composition with an aqueous solution comprising one or more chemical reducing agents; reacting at least a portion of the copper concentrate with the chemical reducing agent to reduce copper within the copper concentrate; isolating a solid-phase reaction product comprising Cu 0; and the copper concentrate comprises chalcopyrite; the chemical reducing agent comprises vanadium (II) ions, a compound comprising vanadium (II) ions, chromium (II) ions, a compound comprising chromium (II) ions, or a combination thereof.

2. The method according to claim 1, further comprising contacting the solid-phase reaction product with an acidic stream comprising one or more acids to produce a dissolved copper product.

3. The method according to claim 2, wherein the acidic stream comprises ferric sulfate, sulfuric acid, or a combination thereof at a certain concentration.

4. The method according to claim 2, comprising electro-winning the dissolved copper product to isolate the copper product and the regenerated acid.

5. The step of isolating the solid-phase reaction product comprises: isolating a liquid-phase reaction product comprising an oxidized chemical reducing agent; feeding the liquid-phase reaction product to an electrochemical device; and the method according to claim 1.

6. reducing the oxidized chemical reducing agent to a regenerated chemical reducing agent in the electrochemical device; contacting the regenerated chemical reducing agent with the composition; and the method according to claim 5.

7. The method according to claim 5, further comprising isolating a second copper product from the liquid-phase reaction product.

8. The method according to claim 1, wherein the chemical reducing agent comprises vanadium (II) sulfate, chromium (II) chloride, or a combination thereof.

9. The step of isolating the solid-phase reaction product comprises: isolating a gas reaction product comprising hydrogen sulfide; contacting the gas reaction product with a second iron stream to form a first iron effluent stream and an elemental sulfur effluent stream; regenerating the first iron effluent stream in the electrochemical device; and the method according to claim 1.

10. A system for producing a copper product from copper concentrate, comprising: a source of copper concentrate; a reduction reactor in communication with the source of copper concentrate, the reduction reactor comprising: an acidic aqueous solution comprising one or more chemical reducing agents; at least a first product outlet; and the reduction reactor. communicates with the first product outlet and includes a solid product outlet stream containing Cu 0, a dissolution reactor that communicates with one or more acid inlet streams and the solid product outlet stream to produce a dissolved copper product stream, a copper isolation electrolytic extraction reactor in fluid communication with the dissolved copper product stream, the copper isolation electrolytic extraction reactor being in fluid communication with the dissolution reactor and producing a copper product and a regenerated acid stream comprising the copper concentrate includes chalcopyrite, the chemical reducing agent includes vanadium (II) ions, a compound containing vanadium (II) ions, chromium (II) ions, a compound containing chromium (II) ions, or a combination thereof, a system. **Claim 11** The system according to claim 10, wherein the chemical reducing agent includes vanadium (II) sulfate, chromium (II) chloride, or a combination thereof. **Claim 12** The system according to claim 10, wherein the acid inlet stream includes a certain concentration of iron (III) sulfate, sulfuric acid, or a combination thereof. **Claim 13** The reduction reactor further includes a second product outlet, and the system includes a liquid product outlet stream in fluid communication with the second product outlet and containing an oxidized chemical reducing agent, an electrochemical device in fluid communication with the liquid outlet stream, and a regenerated chemical reducing agent stream produced by the electrochemical device and in fluid communication with the reduction reactor. The system according to claim 10, further comprising. **Claim 14** The reduction reactor further includes a third product outlet, and the system includes a gas-phase product outlet stream in fluid communication with the third product outlet and containing hydrogen sulfide, a gas treatment reactor in fluid communication with the gas-phase product outlet stream, a second iron feed stream supplied from the electrochemical device to the gas treatment reactor, a first iron feed stream supplied from the gas treatment reactor to the electrochemical device, and an elemental sulfur effluent stream. The system according to claim 13, further comprising. **Claim 15** A method for indirectly reducing chalcopyrite, comprising providing a composition containing a certain concentration of chalcopyrite, contacting the composition with an acidic aqueous solution containing one or more acids and one or more chemical reducing agents, wherein the one or more acids include sulfuric acid, hydrochloric acid, or a combination thereof, and the one or more chemical reducing agents include vanadium (II) ions, a compound containing vanadium (II) ions, chromium (II) ions, a compound containing chromium (II) ions, or a combination thereof. A step of reacting the chalcopyrite with the chemical reducing agent to reduce at least a part of the copper contained therein; A step of separating a solid reaction product stream, a liquid reaction product stream, and a gas reaction product stream, wherein the solid reaction product stream contains Cu 0, the liquid reaction product stream contains an oxidized chemical reducing agent, The gas generation stream contains H ２ S, and a process a step of providing the oxidized chemical reducing agent to an electrochemical device; a step of reducing the oxidized chemical reducing agent to a regenerated chemical reducing agent in the electrochemical device; a step of bringing the regenerated chemical reducing agent into contact with the composition; a step of treating the gas reaction product stream with a certain concentration of ferric to produce a sulfur product and a certain concentration of ferrous; a step of regenerating the ferrous to the electrochemical device; a step of bringing the solid reaction product stream into contact with the one or more acids to produce a dissolved copper product stream; a step of electrolytically extracting the dissolved copper product stream to isolate a copper product and a regenerated acid A method comprising. **Claim 16** The method according to claim 15, wherein the acidic aqueous solution has a concentration of reducing agent of 0.01 M to 10 M.

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