CN117413094A - Reduction of chalcopyrite by aqueous phase reducing agents to effect hydrometallurgical extraction of copper - Google Patents

Reduction of chalcopyrite by aqueous phase reducing agents to effect hydrometallurgical extraction of copper Download PDF

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CN117413094A
CN117413094A CN202180094952.2A CN202180094952A CN117413094A CN 117413094 A CN117413094 A CN 117413094A CN 202180094952 A CN202180094952 A CN 202180094952A CN 117413094 A CN117413094 A CN 117413094A
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copper
product
stream
reducing agent
chemical reducing
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J·瓦尔德纳
A·韦斯特
S·班塔
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Columbia University in the City of New York
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Columbia University in the City of New York
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Priority claimed from PCT/US2021/065450 external-priority patent/WO2022147078A1/en
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Abstract

Contacting a copper concentrate, such as chalcopyrite, with an aqueous solution comprising an acid and a reducing agent, such as vanadium (II) ions, chromium (II) cations or zincate (H) 6 ZnW 12 O 40 ). The aqueous solution reduces the copper in the copper concentrate, which may then be dissolved into the solution for recovery from the solution or precipitated from the solution as copper compounds or elemental copper for recovery as a solid phase product. The solid phase product may then be separated, dissolved and further electrowinning to recover copper product from the copper concentrate. Oxidized byCan be recovered in an electrochemical device having a ferrous reactant. Hydrometallurgical routes to convert copper concentrates to copper may be less costly, less polluting than current pyrometallurgical processes, and are an advantageous response to environmental and economic pressures to increase copper yield.

Description

Reduction of chalcopyrite by aqueous phase reducing agents to effect hydrometallurgical extraction of copper
Cross reference to related applications
The present application claims the benefit of U.S. provisional application 63/131,838 filed on 12 months 30 in 2020 and U.S. provisional application 63/294,098 filed on 12 months 28 in 2021, which are hereby incorporated by reference as if disclosed in their entirety herein.
Statement regarding federally sponsored research and development
The present invention was completed with U.S. government funding at 1644869 awarded by the national science foundation (National Science Foundation). The united states government has certain rights in this invention.
Background
Renewable energy has become increasingly popular in the 21 st century due to the environmental impact of fossil fuels and the increase in cost. However, the demand for copper from renewable energy sources may be five times as great as that of traditional energy sources because of their high conductivity translating into efficient power transmission and their relatively low cost making them economically advantageous over other metals. For wind and solar power plants, large amounts of copper are required to connect remotely separated components, including energy storage systems and power grids. Photovoltaic solar power generation systems contain about 5.5 tons of copper per Megawatt (MW), and a single wind farm may contain 400-1500 kilopounds of copper. The wires, motor, radiator and brake of the hybrid vehicle contained about 45 kg of copper.
The high demand for copper is synchronized with the dramatic drop in copper reserves, and therefore, copper shortages are expected to occur in the next decades. The availability of new copper must be extended for decades to facilitate the transition to renewable energy technologies.
Copper production costs are expected to rise in the next few decades. Researchers have expected that by 2050, the copper industry will reach a global peak, in part because of the high cost of copper production. Development of new processing techniques for copper-containing ores is critical to reduce copper production costs and extend the availability of new copper for decades.
Chalcopyrite (CuFeS) 2 ) Is the most abundant copper-containing mineral found in nature, accounting for about 70% of the global copper reserves. However, the high demand for copper is synchronized with global peaks in global copper production, which results from the exhaustion of copper reserves and the high cost of current copper production technology. Attention is paid to CuFeS 2 The pyrometallurgical process of (c) is converted to a hydrometallurgical process to achieve environmentally and economically sustainable copper production.
CuFeS 2 Minerals are typically mined, concentrated, and then smelted to produce copper. Pyrometallurgical processes are characterized by high investment costs, high operating costs, and the possibility of release of environmentally harmful byproducts, such as sulfur dioxide and arsenic. Table 1 lists the key operating steps and associated costs of the pyrometallurgical process. Mining and crushing of ore requires crushing the ore to the millimeter level. Ball milling is used to reduce the particle size further to the micrometer scale. Flotation is used to separate sulfide mineral phases from silicate phases. Transportation smelting is required to transport the concentrate to overseas smelters. The CuFeS is required to be smelted 2 Is converted to Cu, but may release sulfur dioxide (SO 2 ) And arsenic (As) As a byproduct. Finally, electrochemical refining is used to produce high quality copper for sale.
TABLE 1 CuFeS 2 Investment and operating costs of the pyrometallurgical process route
The investment costs shown in table 1 can be converted to indirect operating costs by assuming 12% per year capital investment recovery (including interest costs). Assuming operating capital is 10%/year/ton copper, the total investment cost is estimated to be $33000/ton copper/year. The direct cost ($2/kg Cu) and indirect cost ($4/kg Cu) of copper production total $6/kg Cu, approaching sales price.
Thus, for CuFeS 2 Is of great interest to reduce the cost of future copper production and to reduce environmental impact. Although for reagents such as O 2 And H 2 O 2 The reagents were studied, but CuFeS 2 Hydrometallurgical leaching of (2) is typically performed with Fe 3+ As an oxidizing agent. The diffusion of the oxidizing agent is typically inhibited by forming a passivation layer on the mineral surface. There have been divergences concerning the chemical composition of the passivation layer and its mechanism of formation. Elemental sulfur, disulfides, and polysulfides have been identified on chalcopyrite surfaces in a variety of media, all of which may contribute to passivation. CuFeS 2 The range of applied potentials indicates that the chemical phase of the passivation layer is affected. Electrodissolved CuFeS 2 XPS analysis of (C) reveals that at greater than 0.90V SHE Is most likely CuFeS at the potential of (a) 2 The surface passivation phase is a metal-depleted sulfide film that includes cuprous sulfide (Cu-S) bonds and ferric sulfide (Fe-S) bonds. Indigenous bacteria that enhance other copper-sulfur oxidation kinetics do not significantly improve CuFeS 2 Oxidation kinetics. Silver ions can change CuFeS 2 Thereby lessening the severity of sulfur deactivation. CuFeS 2 Electrodissolution with the presence of silver ions reveals Ag in the passivation layer 2 And S is formed. Ag (silver) 2 S requires the formation of sulfur vacancies and a pair of holes, which reduces the passivation properties of the film and improves CuFeS 2 Is not limited, and the dissolution rate of the polymer is not limited. Although silver ions are effective catalysts, they are not used in practice due to their high cost.
By combining CuFeS 2 Is converted into mineral phase more suitable for chemical oxidation, and can avoid CuFeS 2 Passivation is a related challenge. Research has shown that CuFeS can be produced using solid copper, sulfur dioxide gas, iron and aluminum as reducing agents 2 Conversion to chalcocite (Cu) 2 S). However, chemical reducing agents generally produce relatively low conversions and require fine CuFeS 2 Particle size or high temperature.
A method of treating CuFeS in an acidic solution has been developed 2 Electrochemical reduction to Cu 2 Alternative to S. Studies have been conducted to analyze operating parameters such as acid concentration, cuFeS 2 Slurry density and temperature. Aluminum cathodes are believed to be more effective at converting CuFeS than copper, carbon or platinum cathode materials 2 Conversion to Cu 2 S, and it has been shown that direct contact between the mineral phase and the cathode is necessary to carry out the reaction. Reactions 1 and 2 show that CuFeS 2 Can be electrochemically reduced to Cu 2 S, and then reduced to Cu 2 O. These reactions have been optimized by modifying the electrolyte, separator, electrode materials and reactor design.
2CuFeS 2 +6H + +2e - →Cu 2 S+2Fe 2+ +3H 2 S [1]
2Cu 2 S+4H + +O 2 +4e - →2Cu 2 O+2H 2 S [2]
Reactions 1 and 2 compete directly with the hydrogen evolution reaction and therefore typically operate at faradaic efficiencies below 40%. These slurry reactions also present potential engineering challenges, such as reactor plugging and electrode fouling.
SUMMARY
Some aspects of the present disclosure relate to methods of producing copper products from copper concentrates. In some embodiments, the method includes providing a composition comprising copper concentrate. In some embodiments, the method comprises: contacting the composition with an aqueous solution comprising one or more chemical reducing agents. In some embodiments, the method comprises: reacting at least a portion of the copper concentrate with a chemical reducing agent to reduce copper in the copper concentrate. In some embodiments, the method comprises: separating a solid phase reaction product comprising a copper product. In some embodiments, the method comprises: the solid phase reaction product is contacted with an acid stream comprising one or more acids to produce a dissolved copper product. In some embodiments, the method comprises: the dissolved copper product is electrodeposited to separate the copper product and recycled acid.
In some embodiments, the step of isolating the solid phase reaction product comprises: separating a liquid phase reaction product comprising an oxidized chemical reducing agent; and feeding the liquid phase reaction product to an electrochemical device. In some embodiments, the method comprises: reducing the oxidized chemical reducing agent to a recycled chemical reducing agent at the electrochemical device, and contacting the recycled chemical reducing agent with the composition. In some embodiments, the method comprises: separating the second copper product from the liquid phase reaction product. In some embodiments, the step of isolating the solid phase reaction product comprises: a gas-off reaction product, the gas 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 recycling the ferrous iron effluent stream to an electrochemical device.
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 comprises vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, zincate (H) 6 ZnW 12 O 40 ) Or a combination thereof. In some embodiments, the chemical reducing agent comprises vanadium (II) sulfate, chromium (II) chloride, or a combination thereof.
Some aspects of the disclosure relate to a method of indirectly reducing chalcopyrite, the method comprising: providing a composition comprising a concentration of chalcopyrite; 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 comprise sulfuric acid, hydrochloric acid, or a combination thereof, and the one or more chemical reducing agents comprise vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, tungstenic acid (H 6 ZnW 12 O 40 ) Or a combination thereof; reacting chalcopyrite with a chemical reducing agent, thereby reducing at least part of the copper contained therein; separating a solid reaction product stream, a liquid reaction product stream and a gaseous reactionA product stream; providing the reacted chemical reducing agent to an electrochemical device; reducing the oxidized chemical reducing agent to a recycled chemical reducing agent at the electrochemical device; contacting the recycled chemical reducing agent with the composition; treating the gaseous reaction product stream with a concentration of ferric iron to produce a sulfur product and a concentration of ferrous iron; recycling ferrous iron to the electrochemical device; contacting the solid reaction product stream with one or more acids, thereby producing a dissolved copper product stream; and electrowinning the dissolved copper product thereby separating the copper product and the recycle acid.
In some embodiments, the solid reaction product stream comprises copper, a copper compound, or a combination thereof, the liquid reaction product stream comprises an oxidized chemical reducing agent, and the gaseous reaction product stream comprises H 2 S, S. In some embodiments, the acidic aqueous solution has a concentration of about 0.01M to about 10M of the reducing agent.
Some aspects of the present disclosure relate to systems for producing copper products from copper concentrates. In some embodiments, the system comprises: a copper concentrate source; a reduction reactor in communication with a copper concentrate source; a solid phase product outlet stream in communication with the first product outlet; a dissolution reactor in communication with the one or more acid inlet streams and the solid phase product outlet stream, the dissolution reactor producing a dissolved copper product stream; and a copper separation electrowinning reactor in fluid communication with the dissolved copper product stream, the copper separation electrowinning reactor producing a copper product and a recycle acid stream in fluid communication with the dissolution reactor.
In some embodiments, the reduction reactor includes an acidic aqueous solution comprising one or more chemical reducing agents and at least a first product outlet. In some embodiments, the copper concentrate comprises chalcopyrite. In some embodiments, the chemical reducing agent comprises vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, zincate (H) 6 ZnW 12 O 40 ) Or a combination thereof. In some embodiments, the chemical reducing agent comprises vanadium (II) sulfate, chromium (II) chloride, or a combination thereof. In some embodiments, the acid inlet stream comprisesConcentrated ferric (III) sulfate, sulfuric acid, or a combination thereof.
In some embodiments, the reduction reactor includes a second product outlet. In some embodiments, the system comprises: a liquid phase product outlet stream in fluid communication with the second product outlet, the liquid phase product stream comprising an oxidized chemical reducing agent; an electrochemical device in fluid communication with the liquid phase outlet stream; and a recirculated 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 comprises: a gas phase product outlet stream in fluid communication with the third product outlet, the gas phase product outlet stream comprising hydrogen sulfide; a gas treatment reactor in fluid communication with the gas phase product outlet stream; providing a ferric iron feed stream from an electrochemical device to a gas treatment reactor; providing a ferrous feed stream from a gas treatment reactor to an electrochemical device; and an elemental sulfur effluent stream.
Brief description of the drawings
For the purpose of illustrating the invention, the drawings show embodiments of the disclosed subject matter. However, it should be understood that this application is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:
FIG. 1 is a flow chart of a method of producing copper products from copper concentrate according to some embodiments of the present disclosure;
FIG. 2 is a schematic diagram of a system for producing copper products from copper concentrate according to some embodiments of the present disclosure;
FIG. 3 depicts a VSO at 1M 4 、4M H 2 SO 4 Reaction with 39g/L concentrate and reaction at 1MH 2 SO 4 During the direct reduction from chalcopyrite (CuFeS) 2 ) Released Fe 2+ Graph of percentage;
FIG. 4 depicts a 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 A plot of x-ray diffraction (XRD) results of the mineral products after 60 minutes of reaction between concentrates;
FIG. 5 depicts a 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 A plot of XRD results of the mineral products after 60 minutes of reaction between concentrates;
FIG. 6A depicts a 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 Pictures of mineral products after 60 minutes of reaction between concentrates;
FIG. 6B depicts a 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 Scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDS) results of the mineral products after 60 minutes of reaction between the concentrates;
FIGS. 6C-6D depict 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 XRD spectrum of the mineral product after 60 minutes of reaction between concentrates;
FIG. 7 depicts a 1M VSO 4 、39g/L CuFeS 2 Concentrate and various initial concentrations H 2 SO 4 A plot of XRD results of the mineral product after 60 minutes of reaction therebetween;
FIG. 8A depicts a 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 Fe during the reaction between concentrates 2+ A graph of ion release into solution;
FIG. 8B depicts a 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 After the reaction between concentrates, by containing 1M H 2 SO 4 With 0.5M Fe 2 (SO 4 ) 3 Extraction of Cu from mineral products 2+ Is a graph of (2);
FIG. 9A depicts a 1M VSO 4 、39g/L CuFeS 2 Concentrate and various initial concentrations H 2 SO 4 Fe during the reaction between them 2+ A graph of ion release into solution;
FIG. 9B depicts a 1M VSO 4 、39g/L CuFeS 2 Concentrate and various initial concentrations H 2 SO 4 After the reaction, by containing 1M H 2 SO 4 With 0.5M Fe 2 (SO 4 ) 3 Extraction of Cu from mineral products 2+ Is a graph of (2);
FIG. 10 depicts the time between a) 0 seconds, b) 2 seconds, c) 3 secondsD) 5 seconds and e) 1M CrCl at 1 minute 2 4M HCl and 78g/L CuFeS 2 Pictures of reactions between concentrates;
FIG. 11A depicts 1M CrCl 2 4M HCl and various loadings of CuFeS 2 Fe during the reaction between concentrates 2+ A graph of ion release into solution;
FIG. 11B depicts 1M CrCl 2 、39g/L CuFeS 2 Fe during the reaction between concentrate and HCl of various initial concentrations 2+ A graph of ion release into solution;
FIG. 12 depicts 1M CrCl at various chalcopyrite concentrate loadings 2 Optical microscopy images of the mineral product after 60 minutes of reaction with 4M HCl;
FIG. 13 depicts 1M CrCl at various chalcopyrite concentrate loadings 2 XRD results for the mineral product after 60 minutes of reaction with 4M HCl;
FIG. 14 depicts chalcopyrite concentrate at 39g/L at 1M CrCl 2 XRD results plots of the mineral product after 60 minutes of reaction between HCl of various initial concentrations;
FIG. 15 depicts a solution of 1M CrCl 2 SEM images of the mineral product after 60 minutes of reaction with 4M HCl;
FIG. 16 depicts a solution of 1M CrCl 2 EDS images of mineral product after 60 minutes of reaction with 4M HCl;
FIG. 17A depicts a solution of 1M CrCl 2 XPS images of Cu of the mineral product after 60 minutes of reaction with 4M HCl;
FIG. 17B depicts a solution of 1M CrCl 2 XPS image of Cl of the mineral product after 60 minutes of reaction with 4M HCl;
FIG. 18 depicts a display at 1M CrCl 2 4M HCl and various loadings of CuFeS 2 Reaction between concentrates and further at 1M CrCl 2 、39g/L CuFeS 2 After the reaction between concentrate and various initial concentrations of HCl, cu is extracted from the mineral product by 0.5m Fe2 (SO 4) 3 2+ Is a diagram of (1); and
FIG. 19 depicts a graph summarizing the energy requirements of various metallurgical processes.
Detailed Description
Referring now to fig. 1, some embodiments of the present disclosure relate to a method 100 of producing a copper product from a copper concentrate. As used herein, the term "copper concentrate" refers to a composition comprising a concentration of copper that requires extraction. In some embodiments, the copper concentrate is a copper-containing mineral or a combination of copper-containing minerals. In some embodiments, the copper concentrate is naturally occurring. In some embodiments, the copper concentrate includes a concentration of chalcopyrite. In some embodiments, the copper concentrate is artificial. In some embodiments, the copper concentrate is a waste product, e.g., from an industrial process. For example, some mining processes produce waste products that contain copper, but which may have too high an arsenic content or too low an actual copper content to be treated by conventional processes to separate the copper components. However, the system of the disclosed method is even capable of extracting copper components from these traditionally unavailable copper sources.
Still referring to fig. 1, some embodiments of the present disclosure include producing a copper product from a copper concentrate (e.g., from chalcopyrite) by indirect reduction of the concentrate. Reduction processes consistent with the present disclosure are in contrast to oxidation processes more common in the literature. At 102, a composition comprising copper concentrate is provided. In some embodiments, the composition is provided to any suitable reaction vessel capable of containing the chemical reactions described below with reference to the various embodiments of the present disclosure. At 104, the composition is contacted with an aqueous solution comprising one or more chemical reducing agents. In some embodiments, the reducing agent is configured to reduce copper in the copper concentrate. In some embodiments, the reducing agent is further configured to be regenerated by one or more electrochemical processes after oxidation. In some embodiments, the chemical reducing agent comprises a reducing ion, a compound comprising a reducing ion, or a combination thereof. In some embodiments, the chemical reducing agent comprises vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, or combinations thereof. In some embodiments, the chemical reducing agent comprises vanadium (II) sulfate, chromium (II) chloride, tungstophenolic acid (H 6 ZnW 12 O 40 ) Or a combination thereof.In some embodiments, the aqueous solution has a concentration of the reducing agent of about 0.01M to about 10M.
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 further comprises one or more inert substances, e.g., feS 2 Silicate, other materials, or combinations thereof.
At 106, at least a portion of the copper concentrate is reacted with a chemical reducing agent to reduce copper in the copper concentrate. Without being bound by theory, the reaction between the aqueous solution and the reducing agent and copper concentrate is provided below. In these exemplary embodiments, the chalcopyrite is chemically reduced by a reducing agent. Reactions 3 and 4 show CuFeS 2 、VSO 4 And H 2 SO 4 The reaction between them. Product Cu 2 S and Cu0 are thermodynamically stable at low pH and reducing conditions. These reactions are similar to reactions 1 and 2 above, but use V 2+ Ions act as electron mediators to enhance electrochemical performance.
2CuFeS 2 +6H + +2V 2+ →Cu 2 S+2Fe 2+ +3H 2 S+2V 3+ [3]
Cu 2 S+2H + +2V 2+ →2Cu+H 2 S+2V 3+ [4]
In the process of putting CuFeS 2 Concentrate addition to acid V 2+ A severe reaction was observed while in solution. Rapid release of gaseous species with H shown in reactions 3 and 4 2 S produces a match. Liquid phase samples were measured by GC-MS to confirm dissolved H 2 The presence of S.
Reaction 5 shows CrCl 2 And HCl.
CuFeS 2 +4H + +Cr 2+ →Cu + +Fe 2+ +2H 2 S+Cr 3+ [5]
Also, in the process of putting CuFeS 2 Concentrate addition to CrCl 2 And HCl, which is comparable to the evolution of the gaseous species predicted in reaction 5And become coincident. Although the cost of these reducing agents is high relative to copper, the process can be utilized to effectively regenerate the reducing agents, e.g., vanadium redox flow batteries or similar electrochemical cells, such that V is achieved at high current densities 2+ And (5) regenerating. In some embodiments, the reduction reaction occurs uniformly, for example, within the entire reaction vessel or across the entire copper concentrate. As demonstrated in reactions 3-5 above, reaction step 106 produces a copper product, which may be isolated and used, or further processed for any downstream processing desired by the user. In some embodiments, the copper product is elemental copper. In some embodiments, the copper product is present in the form of a copper-containing compound, which may then be treated to separate elemental copper therefrom, as will be discussed in more detail below. In some embodiments, at least a portion of the copper product precipitates from solution during or after the reacting step 106. In some embodiments, at least a portion of the copper product precipitates from solution in the reaction vessel. In some embodiments, at least a portion of the copper product precipitates as elemental copper from the solution. In some embodiments, at least a portion of the copper product precipitates as a copper compound from the solution. In some embodiments, at least a portion of the copper product remains in solution.
At 108, the solid phase reaction product is isolated. In some embodiments, the solid phase reaction product includes one or more species, such as copper product, that precipitate out of solution during step 106 or in response to step 106. As discussed above, in some embodiments, the solid phase reaction product comprises solid elemental copper, a solid copper-containing compound, or a combination thereof. In some embodiments, the solid phase reaction product comprises at least a portion of a copper product. In some embodiments, the solid phase reaction product includes all copper products. In some embodiments, at 110, at least a portion of the solid phase reaction product is contacted with an acidic stream. The acidic stream effectively dissolves copper product in the solid phase reaction product and produces a dissolved copper product. In some embodiments, the acid stream comprises one or more acids. In some embodiments, the acidic stream comprises a concentration of iron (III) sulfate, sulfuric acid, or a combination thereof. In some embodiments, the solid phase reaction product comprises a mineral inert. Without being bound by theory, while trace amounts of rhenium-and arsenic-containing compounds may be present, the inert materials primarily include pyrite and silicates. It may be economically advantageous to recover the rhenium-containing inert material for rhenium production, and it may be environmentally advantageous to recover the arsenic-containing inert material for conversion to benign form.
At 112, the dissolved copper product is electrowinning, e.g., provided to an electrowinning reactor, to separate the copper product and produce recycled acid. In some embodiments, the recycled acid is recycled for use during the contacting step 110.
Still referring to fig. 1, at 114, a liquid phase reaction product is separated. In some embodiments, the liquid phase reaction product is separated 114 as the solid phase reaction product is separated at step 108 as described above. In some embodiments, the liquid phase reaction product comprises an oxidized chemical reducing agent, e.g., V 3+ And/or Cr 3+ . In some embodiments, the liquid phase further comprises Fe in sulfuric acid 2+ Ions. In some embodiments, the high solubility of the oxidized reducing agent may be used to react it with Fe 2+ And (5) separating. In some embodiments, a bioreactor is used to oxidize V 3+ And Fe (Fe) 2+ Thereby facilitating its separation. In some embodiments, at 116, the second copper product is separated from the liquid phase reaction product by any suitable method.
At 118, the liquid phase reaction product is fed to an electrochemical device. At 120, the oxidized chemical reducing agent is reduced at the electrochemical device. In some embodiments, the electrochemical device comprises a concentration of ferrous iron or other reactant effective to assist in reducing the oxidized chemical reducing agent. In some embodiments, the chemical reducing agent undergoing oxidation is reduced to a recycled chemical reducing agent. Without being bound by theory, in an exemplary embodiment, the cathodic reaction of the electrochemical device is given by reaction 6, while the anodic reaction is given by reaction 7.
V 3+ +e-→V 2+ [6]
Fe 2+ →Fe 3+ +e - [7]
The membrane crossover of vanadium species can be reduced by applying high current densities, which is also required to achieve high reaction rates. The crossover of iron species may reduce the efficiency of the electrochemical cell but may not result in long term damage due to downstream iron separation. At 122, the recycled chemical reducing agent is contacted with the composition, for example, at a reaction vessel.
Still referring to FIG. 1, at 124, gaseous reaction products are separated. In some embodiments, the gas phase reaction product is separated 124 due to separation of the solid phase reaction product at step 108, separation of the liquid phase product at step 114, or a combination thereof. In some embodiments, the gaseous reaction product comprises hydrogen sulfide. In some embodiments, at 126, the gaseous reaction product is contacted with a ferric stream. Without being bound by theory, in an exemplary embodiment, the gaseous reaction product is treated with ferric iron to recover protons through reaction 8 below.
2Fe 3+ +H 2 S→2Fe 2+ +2H + +S 0 [8]
In some embodiments, protons produced by the reaction are transported through a membrane of an electrochemical device and are thus recovered. In some embodiments, the ferric stream is provided by an electrochemical device. In some embodiments, the contacting step 126 forms a ferrous effluent stream and an elemental sulfur effluent stream. In some embodiments, the ferrous 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.
Referring now to fig. 2, some embodiments of the present disclosure relate to a system 200 for producing copper products from copper concentrate. In some embodiments, the system 200 includes a copper concentrate source 202. As discussed above, in some embodiments, the copper concentrate from the source is naturally occurring, man-made, or a combination thereof. In some embodiments, the copper concentrate comprises: concentrate of chalcopyrite; waste products, such as those from industrial processes; or a combination thereof.
In some embodiments, the system 200 includes a reduction reactor 204, e.g., a reaction vessel as described above with reference to the method 100. In some embodiments, the reduction reactor has one or more inlets 204A and one or more outlets 204B. In some embodiments, the system 200 is configured to provide copper concentrate from the source 202 to the reduction reactor 204. In some embodiments, the reduction reactor 204 is in communication with the copper concentrate source 202, e.g., through inlet 204A'. In some embodiments, the reduction reactor 204 comprises an aqueous solution 206. As discussed above, in some embodiments, the aqueous solution 206 includes one or more chemical reducing agents. In some embodiments, the chemical reducing agent comprises a reducing ion, a compound comprising a reducing ion, or a combination thereof. In some embodiments, the chemical reducing agent comprises vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, or combinations thereof. In some embodiments, the chemical reducing agent comprises vanadium (II) sulfate, chromium (II) chloride, tungstophenolic acid (H 6 ZnW 12 O 40 ) Or a combination thereof. In some embodiments, the aqueous solution 206 has a concentration of the reducing agent of about 0.01M to about 10M. In some embodiments, the aqueous solution 206 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 system 200 is configured to provide a chemical reductant to the reduction reactor 204. In some embodiments, the chemical reductant is provided by a chemical reductant source 208, for example, at inlet 204A. In some embodiments, the bell portion of the chemical reductant in the aqueous solution 206 is in the form of a recycle stream generated by the system 200 itself via one or more other components, as will be discussed in more detail below. In some embodiments, the system 200 is configured to provide one or more acids to the reduction reactor 204. In some embodiments, the acid is provided by an acid source 210, e.g., at inlet 204A. In some embodiments, at least a portion of the acid in the aqueous solution 206 is in the form of a recycle stream provided by the system 200 itself through one or more other components.
As described above, the reduction reactor 204 is configured to react at least a portion of the copper concentrate with a chemical reducing agent, thereby reducing copper in the copper concentrate and separating copper product from the copper concentrate. In some embodiments, at least a portion of the copper product precipitates from solution in reduction reactor 204. In some embodiments, at least a portion of the copper product precipitates as elemental copper from the solution. In some embodiments, at least a portion of the copper product precipitates as a copper compound from the solution. In some embodiments, at least a portion of the copper product remains in solution.
Still referring to fig. 2, system 200 includes a solid phase product outlet stream 212. In some embodiments, the solid phase product outlet stream 212 communicates with and is withdrawn from the reduction reactor 204 through an outlet (e.g., first product outlet 204B'). As discussed above, in some embodiments, the solid phase product outlet stream 212 comprises solid elemental copper, solid copper-containing compounds, or combinations thereof. In some embodiments, the solid phase product outlet stream 212 includes at least a portion of the copper product. In some embodiments, the solid phase product outlet stream 212 includes all of the copper product.
In some embodiments, the solid phase reaction product stream 212 is provided to a 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 discussed above, at least a portion of the solid phase product outlet stream 212 is contacted with an acid, e.g., an acid from the acid inlet stream 216. The acid effectively dissolves the copper product in the solid phase product outlet stream 212 and produces a dissolved copper product stream 218. In some embodiments, the acid inlet stream comprises a 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, producing and/or separating copper product 221 and recycle acid stream 222. In some embodiments, at least a portion of recycle acid stream 222 is fed back to dissolution reactor 214 for dissolution of solid phase product outlet stream 212 in the reactor.
Still referring to fig. 2, system 200 includes a liquid phase product outlet stream 224. In some embodiments, the liquid phase product outlet stream 224 communicates with and is withdrawn from the reduction reactor 204 through an outlet (e.g., second product outlet 204B'). As discussed above, in some embodiments, the liquid phase product outlet stream 224 comprises an oxidized chemical reducing agent, such as V 3+ And/or Cr 3+ . In some embodiments, the liquid phase further comprises Fe in sulfuric acid 2+ Ions. In some embodiments, iron (II) ion species, a second copper product (e.g., a dissolved copper product), or a combination thereof are withdrawn from the liquid phase product outlet stream via one or more streams 225. In some embodiments, the high solubility of the oxidized reducing agent may be used to react it with Fe 2+ And (5) separating. In some embodiments, the liquid phase product outlet stream 224 comprises a concentration of dissolved copper product that is separated and recovered by an electrowinning process.
In some embodiments, at least a portion of the liquid phase product outlet stream 224 is fed to an electrochemical device 226. As discussed above, the electrochemical device 226 contains a 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 recycled chemical reducing agent and withdrawn from electrochemical device 226 for use as recycled chemical reducing agent stream 228. In some embodiments, the recycled chemical reductant stream 228 is provided back to the reduction reactor 204, for example at inlet 204A ". In some embodiments, at least a portion of the ferrous iron is oxidized and withdrawn as ferric feed stream 230, as will be discussed below.
Still referring 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 withdrawn from the reduction reactor 204 through an outlet (e.g., third product outlet 204B' "). As discussed above, in some embodiments, the gas phase product outlet stream 232 comprises hydrogen sulfide gas. In some embodiments, ferric iron feed stream 230 and gaseous product outlet stream 232 are combined in gas treatment reactor 234. The reaction between stream 230 and stream 232 forms a ferrous effluent stream 236 and an elemental sulfur effluent stream 238. In some embodiments, the ferrous effluent stream 236 is recycled to the electrochemical device 226 for reduction of the oxidized chemical reducing agent. In some embodiments, the sulfur products in the elemental sulfur effluent stream 238 are recycled for use in one or more downstream processes. In some embodiments, the sulfur products in the elemental sulfur effluent stream 238 are discarded.
As will be apparent to those of skill in the art, systems consistent with embodiments of the present disclosure include any additional various components, such as conduits, power supplies, controllers, product collection reservoirs, etc., to facilitate reduction of chalcopyrite and separation of copper products.
Examples
In one exemplary embodiment, a sample of chalcopyrite mineral concentrate is provided. The samples were analyzed by energy dispersive X-ray diffraction and were found to have a composition according to table 2 below:
table 2: mineralogy of chalcopyrite concentrate
In addition to the concentrates shown in table 2, three other forms of concentrates are provided, with varying amounts of copper and other inert materials. The method of the present disclosure was determined to be compatible with broad purity broad concentrates. For CuFeS 2 The concentrate was screened (-140+270 mesh) limiting the particle size to 53 to 106 μm. Subsequently, the concentrate was treated with deionized water and 1M H 2 SO 4 Flushing to remove any soluble iron and copper ions generated during natural oxidation of the concentrate during transportation and storage.
In a first exemplary embodiment, a density of 39, 78, 117, or 234g/L is usedCuFeS 2 Concentrate slurry was added to a 250mL Erlenmeyer flask containing 25mL of 1M VSO 4 And 4M H 2 SO 4 Is a solution of (a) and (b). For other experiments, cuFeS with a density of 39g/L was used 2 Concentrate slurry addition contains 1M VSO 4 And various concentrations H 2 SO 4 Is a solution of (a) and (b). Due to H 2 The rapid release of S gas and the reaction was carried out in a fume hood. 100 μl of liquid phase samples were collected at time points of 0, 5, 10, 20, 40 and 60 minutes, and then diluted for Fe 2+ And Cu + And (5) measuring the content. After reduction, the mineral particles were filtered from the solution and allowed to air dry prior to characterization.
CuFeS measurement Using ICE 3300AAS 2 Iron and copper ions are released into the solution during its reduction. The characteristic wavelengths measured for iron and copper were 248.3nm and 324.8nm, respectively. In the sample construction of the linearity (R2>0.995 Immediately before the calibration curve, a standard in the range of 0-4ppm was measured.
PANalytical XPert3 Powder XRD was used to measure the reaction products of the bulk (bulk) mineral phases. XRD was operated at filtered Empyrean Cu-Ka radiation (k=0.15418 nm), tube voltage of 45kV and current of 40 mA. The mineral product was placed on a silicon crystal zero diffraction plate (MTI compartment) and adhered in place with apizon grease. The samples were scanned continuously over the rotating plate in steps of 0.0065 ° in the range of 10-100 ° with a 2.0 second rotation time. Peak intensities were recorded using a PIXcel1D detector for subsequent mineral composition analysis.
Zeiss SigmaVP SEM was used to capture images of the reacted mineral products. SEM-EDS analysis at an acceleration potential of 6kV and about 1X 10 -5 Under the basic pressure of the tray. The sample was carried on a carbon tape and coated with gold using a Cressington 108 automatic sputter coater (Cressington 108Auto Sputter Coater). Sputtering was performed under argon flow and a pressure of 0.1 mbar for 20 seconds to obtain an AuPd coating of 1 nm. The elemental composition was analyzed using a Bruker xflsh detector for EDS analysis.
Samples of mineral products were digested in aqua regia for copper extraction and equivalent samples of mineral products were obtained with 0.5M Fe 2 (SO 4 ) 3 1M H of (2) 2 SO 4 Leaching in the solution. The percentage of copper released is determined by the ratio of copper extracted by the two leaches.
H 2 The S gas was released rapidly and qualitative measurements were made with a Sensorcon detector. The gas was released immediately after the concentrate addition and ended within a few minutes of reaction time. Liquid phase samples were measured using gas chromatography-mass spectrometry (GC-MS) to confirm dissolved H 2 S, while no other gases are detected. In an industrial process, H 2 The S gas can be oxidized into harmless S 0 。
FIG. 3 shows the process in CuFeS 2 Direct electrochemical reduction of concentrate (reactions 1-2) and through VSO 4 Fe released therefrom during reduction (reactions 3-4) 2+ Is a percentage of (c). Experiments verify FeS in concentrate 2 Is inert and therefore Fe 2+ Is suitably representative of CuFeS 2 Conversion rate. The graph shows that the use of an electronic medium is kinetically favored by CuFeS 2 The concentrate is directly subjected to electrochemical reduction. VSO (vertical seismic offset) 4 Can make CuFeS 2 Concentrate releases 100% of Fe in 60 minutes 2+ Although the concentrate loading was relatively high, it was 39g/L. Direct electrochemical reduction requires an extended duration to achieve complete conversion of concentrate due to the tendency of the slurry electrode to undergo hydrogen evolution reactions. The direct electrochemical reduction results shown in FIG. 3 used the same experimental procedure as shown in the literature, with an applied current density of 10mA/cm 2 。
FIG. 4 shows the immediate passage of VSO 4 XRD characterization of the mineral product after reduction leaching. Unreacted CuFeS 2 The main peak of the concentrate sample corresponds to CuFeS 2 、FeS 2 And SiO 2 This is consistent with mineralogy shown in table 2. In the spectrum of the reacted mineral product, corresponds to CuFeS 2 And a peak corresponding to the mineral product appears. The results show that the copper-containing solids are removed from CuFeS 2 To Cu 2 S and Cu 0 This corresponds to reactions 3 and 4. XRD spectra confirm FeS 2 And silicate at VSO 4 Is inert during the reduction leaching process.
FIG. 5 shows the mineral product from Cu during the air drying step 0 To CuSO 4 ·5H 2 O transition. The sulfuric acid still coated on the sample reacts with air as shown in reaction 9 to produce CuSO 4 ·5H 2 O. Without being bound by theory, it is hypothesized that Cu studied in iron-containing systems 0 And FeS 2 The galvanic interactions between them may also occur in vanadium-containing systems and have a secondary effect.
2Cu 0 +2H 2 SO 4 +O 2 →2CuSO 4 +2H 2 O [9]
FIGS. 6A-6D show 1M VSO 4 、4M H 2 SO 4 And various loadings of CuFeS 2 Characterization of mineral products after 60 minutes of reaction between concentrates (reactions 3 and 4 above) and after air drying (reaction 9). FIG. 6A shows an optical microscope image of a mineral product obtained with a Keyence VHX-5000 microscope. Appearance of mineral product and unreacted CuFeS 2 The concentrate is significantly different. The mineral product appears blue in appearance, which may be CuSO 4 ·5H 2 And O. FIG. 6B shows 1M VSO 4 、4M H 2 SO 4 And SEM-EDS results of the mineral product after 60 minutes of reaction between the various loadings of concentrate. The unreacted chalcopyrite concentrate samples showed peaks corresponding to the characteristic energies of C, O, fe, cu, al, si and S, which are consistent with the mineralogy shown in table 2. The presence of the C peak is an artifact of placing the sample on the carbon tape prior to analysis. The reacted sample showed that due to Fe 2+ Ion release into solution and H 2 S is released as a gas, and the peaks of Fe and S are respectively reduced. The reacted sample also showed that Al and Si peaks decreased due to their reduced mass fraction in the sample. The main peaks of the reacted sample are Cu, S and O, which are compared with CuSO 4 ·5H 2 The formation of O is consistent. The extension of the O peak in the spectrum is consistent with the product. Without being bound by theory, the absence of V peak in the indication indicates that V did not precipitate into the solid phase during the course of the reaction.
FIG. 6C shows 1M VSO 4 、4M H 2 SO 4 And XRD spectrum of the mineral product after 60 minutes of reaction between the various loaded concentrates. Unreacted CuFeS 2 The main peak of the concentrate sample corresponds to CuFeS 2 、FeS 2 And SiO 2 This is consistent with mineralogy shown in table 2. In the spectrum of the reacted mineral product, corresponds to CuFeS 2 And a peak corresponding to the mineral product appears. Figure 6D shows the XRD regions for identifying mineral products. XRD spectra of mineral products and CuSO 4 ·5H 2 O formation is consistent with SEM-EDS data set.
FIG. 7 shows that for a VSO at 1M 4 39g/L concentrate and 0.5M and 1M initial H 2 SO 4 Experiments performed between concentrations with CuSO 4 ·5H 2 The O-coincident XRD spectrum is reproducible. For all these experiments, the pH of the solution after the reaction was below 1, indicating that the reactions were not pH limiting. No precipitation of vanadium salts from solution was observed under any of these conditions, indicating the potential of the process for high vanadium recovery and recycle. The pH of these solutions was below 1, indicating that these reactions were not pH limiting. Vanadium Redox Flow Batteries (VRFB) typically use H at a concentration of 2-4M 2 SO 4 Operation, therefore, the downstream vanadium (II) regeneration step may benefit from a relatively high acid concentration.
FIG. 8A shows that for a VSO containing 1M 4 、4M H 2 SO 4 And CuFeS loading amounts of 39, 78, 117 and 234g/L 2 Slurry of concentrate, fe 2+ As a function of time. The figure shows that during reduction, about 100% of Fe 2 + From CuFeS 2 This is consistent with reactions 3 and 4. Without being bound by theory, in experiments performed with concentrate loadings of 117 and 234g/L, fe 2+ Is indicative of V 2+ Is fully utilized.
FIG. 8B shows the subsequent passage through and inclusion of 0.5M Fe 2 (SO 4 ) 3 1M H of (2) 2 SO 4 Solution reaction for 60 min to extract Cu from mineral product 2+ As a result of (a). Reaction 10 shows CuSO 4 ·5H 2 Dissolution of O, characterized by 1M VSO 4 、4M H 2 SO 4 And 39g/L chalcopyrite concentrateFinal mineral product.
The results show that almost all Cu can be extracted from 39g/L of mineral product in a few minutes 2+ .39g/L sample was also dissolved in 1M H 2 SO 4 Is a kind of medium. The aqueous solution may be used for solvent extraction and electrowinning to produce metallic copper. Without being bound by theory, the incomplete copper extraction of higher slurry density is partially equivalent to CuFeS shown by XRD analysis described above 2 Incomplete conversion is relevant. The results indicate that CuFeS 2 Little Cu is extracted from concentrate 2+ Thus, the reduction treatment directly results in copper extraction.
FIG. 9A shows concentrate loadings of 39g/L and H of 0.5M, 1M and 4M 2 SO 4 Concentration from CuFeS 2 About 100% of Fe is released 2+ . FIG. 9B shows the mineral product and the composition of the mineral product containing 0.5M Fe 2 (SO 4 ) 3 1M H of (2) 2 SO 4 The solution was fully reacted to fully recover copper. These results indicate that the reduction step may depend on the acid concentration, provided that a sufficient number of protons are available to promote the reaction.
In a second exemplary embodiment, cuFeS having a density of 39, 78, 117, or 234g/L is used 2 Concentrate slurry was added to a 250mL Erlenmeyer flask containing 25mL of 1M CrCl 2 And 4M HCl in solution. For other experiments, cuFeS with a density of 39g/L was used 2 Concentrate slurry addition contains 1M CrCl 2 And HCl of various concentrations, for other experiments, cuFeS at a density of 39g/L 2 Concentrate slurry addition contains 1M CrCl 2 4M HCl and FeCl of various concentrations 2 Is a solution of (a) and (b). Due to H 2 The rapid release of S gas and the reaction was carried out in a fume hood as shown in fig. 10. 100 μl of liquid phase samples were collected at time points of 0, 5, 10, 20, 40 and 60 minutes, and then diluted for Fe 2+ And Cu + And (5) measuring the content. After reduction, mineral particles are filtered from the solution and prior to characterizationAir drying is allowed.
CuFeS measurement Using ICE 3300AAS 2 Releasing Fe into solution during its reduction 2+ And Cu + Ions. The characteristic wavelengths measured for iron and copper were 248.3nm and 324.8nm, respectively. In the sample construction of the linearity (R2>0.995 Immediately before the calibration curve, a standard in the range of 0-4ppm was measured.
PANalytical XPert3 Powder XRD was used to measure the reaction products of the bulk (bulk) mineral phases. XRD was operated at filtered Empyrean Cu-Ka radiation (k=0.15418 nm), tube voltage of 45kV and current of 40 mA. The mineral product was placed on a silicon crystal zero diffraction plate (MTI compartment) and adhered in place with apizon grease. The samples were scanned continuously over the rotating plate in steps of 0.0065 ° in the range of 10-100 ° with a 2.0 second rotation time. Peak intensities were recorded using a PIXcel1D detector for subsequent mineral composition analysis.
PHI 5500XPS equipped with an Al x-ray source was used to measure elemental composition of the reaction product surface. The base pressure of the chamber is about 1 x 10 -8 And (5) a bracket. Carrying the sample on a carbon tape
Zeiss Sigma VP SEM was used to capture images of the reacted mineral products. SEM-EDS analysis at an acceleration potential of 6kV and about 1X 10 -5 Under the basic pressure of the tray. The sample was carried on a carbon tape and coated with gold using a Cressington 108 automatic sputter coater (Cressington 108Auto Sputter Coater). Sputtering was performed under argon flow and a pressure of 0.1 mbar for 20 seconds to obtain an AuPd coating of 1 nm. The elemental composition was analyzed using a Bruker xflsh detector for EDS analysis.
Samples of mineral products were digested in aqua regia for complete copper extraction and equivalent samples of mineral products were found in 1M H 2 SO 4 Contains 0.5M Fe 2 (SO 4 ) 3 Is leached from the solution of (a). The percentage of copper released is determined by the ratio of copper extracted by the two leaches.
FIG. 10 shows 1M CrCl 2 4M HCl and 78g/L CuFeS 2 Reaction pictures of concentrate after 0, 2, 3, 5 and 60 seconds reaction time. Pictures show H 2 S gas is rapidly released to enableQualitative measurements were made with a sensor con detector. The gas was released immediately after the concentrate addition and ended within 1 minute reaction time. For similar experiments, liquid phase samples were measured using gas chromatography-mass spectrometry (GC-MS) to confirm dissolved H 2 The presence of S.
Gas H 2 Precipitation of S and Fe 2+ The release of ions into solution is consistent, which is consistent with reaction 5 above. FIG. 11A shows the released Fe 2+ Percentage and contain 1M CrCl 2 4M HCl and CuFeS at loadings of 39, 78, 117 and 234g/L 2 Relationship of slurry of concentrate. Consider CuFeS at 39, 78 and 117g/L 2 About 100% Fe at concentrate loading 2+ From CuFeS within 5 minutes 2 The reaction kinetics are rapid. However, for a CuFeS of 234g/L 2 Concentrate, fe 2+ Is limited, indicating that Cr 2+ Is fully utilized. Without being bound by theory, fe 2+ The measurement results with release exceeding 100% can show that there is a slight error in the composition estimation shown in table 2 due to errors in XRD quantification and concentrate sieving to 53-106 μm. Experiments were performed while purging the headspace of the reactor with argon and similar results were observed, indicating that for the experiments shown, the small amount of oxygen present in the system did not drive Cr 2+ Oxidation to any significant level. Measurement of Cu during the course of the reaction + Released to solution but due to Cu + Ions precipitate out of solution and the quantitative results are not consistent. The pH of the solution after the reduction experiment was below zero, indicating that these reactions were not pH limiting.
FIG. 11B shows that for a composition comprising 1M CrCl 2 、39g/L CuFeS 2 Slurry of concentrate and initial concentration HCl of 0M, 0.5M, 1M and 4M, released Fe 2+ As a function of time. For slurries with initial HCl concentrations of 0M, 0.5M and 1M, the pH of the solution after the reduction step was about 2.5, indicating that these reactions were pH limited. The pH of the solution after the reduction step may be used to promote Fe 2+ And Cr (V) 3+ Separation between, this is achieved by passing Cr through an electrolysis unit 3+ Reduction to Cr 2+ Which may have been desirable before. These results indicate the stoichiometric number of protonsRatio CuFeS 2 This is in agreement with reaction 5. Experiments with initial HCl concentrations of 2M and 3M were found to be without pH limitation.
FIG. 12 shows the obtained by Keyence VHX-5000 microscope with Cr 2+ Image of mineral product after 60 minutes of ion reduction. Without being bound by theory, the results indicate that the mineral product is subject to CuFeS 2 Concentrate loading effect. 39g/L CuFeS 2 The loading yields a green product, which is consistent with the appearance of CuCl and other potential cu—cl complexes. Various mineral products were characterized and showed varying amounts of copper recovery. The mineral products after reaction with various HCl concentrations have the same tendency in appearance.
FIG. 13 shows the effect of Cr 2+ XRD spectra of various chalcopyrite concentrate loadings after ion reaction, and FIG. 14 shows the mineral samples in contact with Cr 3+ XRD spectrum after reaction of ions with HCl of various initial concentrations. Unreacted CuFeS 2 The main peak of concentrate and CuFeS 2 、FeS 2 And SiO 2 The agreement is as shown in table 2. For reacted mineral products, with CuFeS 2 The relative intensity of the associated peak decreases, which is comparable to Fe measured by AAS 2+ Release coincides. For having high CuFeS 2 The mineral product of the conversion shows a peak related to the reaction product. From the spectrum it was determined that the main mineral product was copper chloride (CuCl). Second products, e.g. Cu 2 (OH) 3 Cl is consistent with this spectrum. Reaction 11 shows that CuCl precipitates out of solution, which is the primary product formed. Reaction 11 shows that for simplicity, the chemical reactions that take place are more complex and various cu—cl complexes can be precipitated. The precipitation of CuCl from a solution containing 4M HCl was unexpected given a Cl/Cu molar ratio of 36 in the system. However, the molar ratio of Cl/Cr is 6, and therefore, cl - And Cr (V) 3+ The complexes formed between them may reduce the availability of stable Cu + Cl of (2) - Ion amount. Cu in solution after 60 minutes reduction + The concentration was about 0.07M, which is close to the solubility limit of 0.233M recorded in literature 36 at 2M HCl. For experiments with a concentrate loading of 39g/L and an acid concentration of 4M HCl, an estimate was made 40% of copper in the system is calculated as Cu + In the bulk solution, 60% of the copper precipitates out of solution.
Cu + +Cl-→CuCl [11]
XRD data and AAS data indicate FeS 2 And silicate is inert during the reduction treatment. At 39g/L CuFeS 2 Concentrate, 1M CrCl 2 Initial concentrations of ferrous chloride (FeCl) of 4M HCl and 0, 0.5M, 1M and 2M 2 ) Experiments were performed therebetween. Without being bound by theory, it is determined that the reduction process can tolerate an initial FeCl below 1M 2 Concentration. Fe (Fe) 2+ Precipitated from the solution for use in 2M initial FeCl 2 Experiments performed on concentration.
FIG. 15 shows the reaction with 1M CrCl 2 SEM results of the mineral product after 60 minutes of reaction with 4M HCl. The mineral product has some mossy character, which may be related to the growth of CuCl. FIG. 16 shows the use of Cr 2+ EDS results of ion reduced mineral samples. Unreacted CuFeS 2 Concentrate samples showed peaks corresponding to Cu, fe, S, si and O. The reacted sample showed a reduction in Fe and S peaks, which was comparable to Fe 2+ Release into solution and H 2 S coincides with the release of gas. The minor S peak present in the 39g/L sample may be correlated with the presence of unreacted FeS in the mineral product 2 Related to the following. The reacted sample also showed the appearance of Cl peaks, which is consistent with the formation of CuCl. As the mass fraction of Cu in the sample increases, the Cu peak of the reacted sample extends. No peak corresponding to Cr was observed in the spectrum, indicating that the presence of Cr in the sample was slight. The sample was digested in aqua regia and the mass fraction of Cr in the sample was estimated to be 1-3%. Without being bound by theory, the presence of chromium is believed to be an artifact in the process for filtering and drying mineral products.
FIGS. 17A-17B show the use of Cr 2+ XPS spectra of Cu (fig. 17A) and Cl (fig. 17B) of the ion reduced mineral samples. No Cr element was observed on the mineral product, further indicating that the sample was chromium free. Similarly, no Fe and S are observed on the surface of the mineral reaction product, which is comparable to Fe 2+ And H 2 S is released from the particle surface into the solution phase. Is not stored inThe rapid kinetics of the reduction reaction can be explained in the sulfur passivation layer. Multiple copper peaks indicate the presence of multiple copper-containing products. For example, peaks with binding energies 944 and 935eV are attributed to Cu, respectively 2 (OH) 3 Cl and CuCl. Cu scanning also showed a reaction with CuFeS 2 The observable binding energy of the concentrate standard changes. The appearance of the Cl peak of the reaction sample was consistent with the formation of cu—cl complex.
FIG. 18 shows the passage of 0.5M Fe 2 (SO 4 ) 3 Extraction of Cu from mineral products 2+ . Reaction 12 shows passage of CuCl through Fe 3+ Leaching of the oxidizing agent is completed in a few minutes.
CuCl+Fe 3+ →Cu 2+ +Cl - +Fe 2+ [12]
The results show that almost all Cu can be extracted from 39g/L of mineral product in a few minutes 2+ . In an experiment not shown, 39g/L of sample was dissolved in 1M H 2 SO 4 Is a kind of medium. The aqueous solution may be used for solvent extraction and electrowinning to produce metallic copper. Incomplete copper extraction at higher slurry density is at least partially equivalent to CuFeS shown in fig. 11A-11B 2 Is associated with incomplete conversion of (c). In addition, potential intermediates formed (e.g., cu 2 (OH) 3 Cl) may be refractory to copper leaching and is undesirable. The results indicate that CuFeS 2 Little Cu is extracted from concentrate 2+ Thus, the reduction treatment directly results in copper extraction.
The methods and systems of the present disclosure advantageously provide a revolutionary hydrometallurgical process to reduce copper production costs, thereby maintaining copper use throughout the transition to renewable energy technology worldwide. These embodiments enable hydrometallurgical production of copper that is more environmentally and economically sustainable than existing. Hydrometallurgical processing is preferred and is used for other copper mineral reserves such as copper oxide. The focus of hydrometallurgical processes is the reduction treatment of chalcopyrite, as opposed to the more common oxidation treatments in the literature. Without being bound by theory, cuFeS 2 Is advantageous at least because it avoids hydrogen evolution reactions and circumvents the chemical reduction associated with slurry electrodesEngineering challenges. Although the cost of vanadium and chromium is high relative to copper, VRFB or iron-chromium flow batteries (ICFB) can be used to effectively regenerate V at high current densities 2+ Or Cr 2+ . The mineral product is produced by a process comprising 1M H 2 SO 4 And 1.5M Fe 3+ 1M H of (2) 2 SO 4 The solution was leached to demonstrate that the mineral product produced complete copper extraction.
Process flow diagrams and related technical economic analysis indicate that the reduction of chalcopyrite by aqueous reducing agents may be competitive with pyrometallurgical standards for copper production. Table 3 shows the investment and operating costs of the hydrometallurgical process steps. The direct cost ($3.1/kg Cu) and indirect cost ($2.4/kg Cu) of copper production total $5.5/kg, which is lower than the estimated cost of pyrometallurgical processes.
TABLE 3 CuFeS 2 Estimated investment and operating costs for chemical reduction
The reduction and dissolution reactor is assumed to have the same investment and operating costs as the solvent extraction unit, including the costs of the mixer, pump and storage tanks. This assumption is reasonable because the rapid kinetics of the reaction results in a relatively small reactor volume. The investment cost of the electrochemical device is estimated based on the scaled-up report cost of the VRFB. It is estimated that 20MW of VRFB is required to match the copper yield of a typical smelter that processes 4000 tons of CuFeS per day 2 Concentrate. These calculations were performed assuming a mass fraction of concentrate of 0.3 and a nominal voltage of the electrochemical cell of 1.35V. The operating costs of the electrochemical device were estimated from the cost of industrial power and assumed to be 1 mole of vanadium lost per 20 moles of copper produced. The operation cost of the electrochemical device can be based on the quality of vanadium/iron separation and V 2 O 5 And the selling price of (c) fluctuates.
FIG. 19 shows estimated energy requirements for pyrometallurgical, electrometallurgical and hydrometallurgical routes for copper production after the ore has been mined and concentratedAnd (5) solving. The highest energy requirement of pyrometallurgical routes is about 13kJ/lb Cu, which is associated with a large amount of CO 2 Related to release of (c). The electrometallurgical route has similar energy requirements, in part due to the high energy requirements of the electrochemical cells. The electrochemical cell was assumed to operate at a cell potential of 2.5V and a faraday efficiency of 40% to estimate its energy requirement. Hydrometallurgical route prediction for copper production uses about 8kJ/lb copper, which represents global CO 2 The discharge amount is significantly reduced. The electrochemical cell was assumed to operate at a cell potential of 1.35V and a faraday efficiency of 95% to estimate its energy requirement. Furthermore, it is assumed that the V/Fe separation step has the same energy requirements as conventional solvent extraction.
As discussed above, the global mining industry is interested in hydrometallurgical routes for converting chalcopyrite to copper due to environmental and economic pressures. Embodiments of the present disclosure may be cheaper and less polluting than current pyrometallurgical processes, and also allow for increased copper production in the united states.
While the present invention has been described and illustrated with respect to exemplary embodiments thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.

Claims (20)

1. A method of producing a copper product from a copper concentrate, the method 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 a chemical reducing agent to reduce copper in the copper concentrate; and
separating a solid phase reaction product comprising a copper product.
2. The method of claim 1, wherein the copper concentrate comprises chalcopyrite.
3. The method of claim 1, the method further comprising:
the solid phase reaction product is contacted with an acid stream comprising one or more acids to produce a dissolved copper product.
4. A method according to claim 3, wherein the acid stream comprises an iron (III) sulfate concentration, a sulfuric acid concentration, or a combination thereof.
5. A process according to claim 3, wherein the dissolved copper product is electrodeposited to separate the copper product and recycled acid.
6. The method of claim 1, wherein the step of separating the solid phase reaction product further comprises:
separating a liquid phase reaction product comprising an oxidized chemical reducing agent; and
the liquid phase reaction product is fed to an electrochemical device.
7. The method of claim 6, the method further comprising:
reducing the oxidized chemical reducing agent to a recycled chemical reducing agent at the electrochemical device; and
the recycled chemical reducing agent is contacted with the composition.
8. The method of claim 6, the method further comprising:
separating the second copper product from the liquid phase reaction product.
9. The method of claim 1, wherein the chemical reducing agent comprises vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, zincate (H) 6 ZnW 12 O 40 ) Or a combination thereof.
10. The method of claim 9, wherein the chemical reducing agent comprises vanadium (ii) sulfate, chromium (ii) chloride, or a combination thereof.
11. The method of claim 1, wherein the step of separating the solid phase reaction product further comprises:
separating 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
the ferrous iron effluent stream is recycled to an electrochemical device.
12. A system for producing a copper product from a copper concentrate, the system comprising:
A copper concentrate source;
a reduction reactor in communication with a copper concentrate source, the reduction reactor comprising:
an acidic aqueous solution comprising one or more chemical reducing agents; and
at least a first product outlet;
a solid phase product outlet stream in communication with the first product outlet;
a dissolution reactor in communication with the one or more acid inlet streams and the solid phase product outlet stream, the dissolution reactor producing a dissolved copper product stream; and
a copper separation electrowinning reactor in fluid communication with the dissolved copper product stream, the copper separation electrowinning reactor producing a copper product and a recycle acid stream in fluid communication with the dissolution reactor.
13. The system of claim 12, wherein the copper concentrate comprises chalcopyrite.
14. The system of claim 12, wherein the chemical reducing agent comprises vanadium (ii) ions, vanadium (ii) ion-containing compounds, chromium (ii) ions, chromium (ii) ion-containing compounds, zincate (H) 6 ZnW 12 O 40 ) Or a combination thereof.
15. The system of claim 14, wherein the chemical reducing agent comprises vanadium (ii) sulfate, chromium (ii) chloride, or a combination thereof.
16. The system of claim 12, wherein the acid inlet stream comprises an iron (III) sulfate concentration, a sulfuric acid concentration, or a combination thereof.
17. The system of claim 13, wherein the reduction reactor further comprises a second product outlet, and the system further comprises:
a liquid phase product outlet stream in fluid communication with the second product outlet, the liquid phase product stream comprising an oxidized chemical reducing agent;
an electrochemical device in fluid communication with the liquid phase outlet stream; and
a recirculated chemical reductant stream is generated by the electrochemical device and is in fluid communication with the reduction reactor.
18. The system of claim 17, wherein the reduction reactor further comprises a third product outlet, and the system further comprises:
a gas phase product outlet stream in fluid communication with the third product outlet, the gas phase product outlet stream comprising hydrogen sulfide;
a gas treatment reactor in fluid communication with the gas phase product outlet stream;
providing a ferric iron feed stream from an electrochemical device to a gas treatment reactor;
providing a ferrous feed stream from a gas treatment reactor to an electrochemical device;
elemental sulfur effluent stream.
19. A method of indirectly reducing chalcopyrite, the method comprising:
providing a composition comprising a chalcopyrite concentration;
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 comprise sulfuric acid Hydrochloric acid or a combination thereof, and the one or more chemical reducing agents include vanadium (II) ions, vanadium (II) ion-containing compounds, chromium (II) ions, chromium (II) ion-containing compounds, tungstenic acid (H) 6 ZnW 12 O 40 ) Or a combination thereof;
reacting chalcopyrite with a chemical reducing agent, thereby reducing at least part of the copper contained therein;
separating the solid reaction product stream, the liquid reaction product stream, and the gaseous reaction product stream, wherein:
the solid reaction product stream comprises copper, copper compounds, or combinations thereof,
the liquid reaction product stream includes an oxidized chemical reducing agent, and
the gaseous reaction product stream comprises H 2 S；
Providing the reacted chemical reducing agent to an electrochemical device;
reducing the oxidized chemical reducing agent to a recycled chemical reducing agent at the electrochemical device;
contacting the recycled chemical reducing agent with the composition;
treating the gaseous reaction product stream with a ferric iron concentration to produce a sulfur product and a ferrous iron concentration;
recycling ferrous iron to the electrochemical device;
contacting the solid reaction product stream with one or more acids, thereby producing a dissolved copper product stream; and
the dissolved copper product is electrowinning, thereby separating the copper product and the recycle acid.
20. The method of claim 19, wherein the acidic aqueous solution has a concentration of the reducing agent of about 0.01M to about 10M.
CN202180094952.2A 2020-12-30 2021-12-29 Reduction of chalcopyrite by aqueous phase reducing agents to effect hydrometallurgical extraction of copper Pending CN117413094A (en)

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US63/131,838 2020-12-30
US202163294098P 2021-12-28 2021-12-28
US63/294,098 2021-12-28
PCT/US2021/065450 WO2022147078A1 (en) 2020-12-30 2021-12-29 Reduction of chalcopyrite by an aqueous phase reducant to enable hydrometallurgical extraction of copper

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