A process for the recovery of cobalt from a zinc hydrometallurgy cobalt-containing solution

Abstract

This application provides a method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc smelting process, relating to the field of hydrometallurgy. The method includes: reacting the cobalt-containing solution with an organic ligand and an oxidant to obtain a cobalt-precipitated liquid and a cobalt-containing precipitate; subjecting the cobalt-containing precipitate to a liquid-phase conversion treatment under closed conditions to obtain a cobalt-rich intermediate; mixing the cobalt-rich intermediate with dilute sulfuric acid to obtain a cobalt-rich solution; extracting the cobalt-rich solution with an extractant to obtain a purified cobalt solution; and using the purified cobalt solution to prepare a cobalt-containing product, which includes at least one of cobalt sulfate, cobalt tetroxide, and metallic cobalt. This application enables efficient separation and extraction of cobalt from a cobalt-containing solution in a hydrometallurgical zinc smelting process and can prepare high-value-added cobalt-containing products. The overall cobalt recovery rate of this application is greater than 93%, and the purity of the cobalt-containing product can reach over 99.5%. This application achieves efficient and high-value utilization of cobalt resources in the hydrometallurgical zinc smelting process.

Description

Technical Field

[0001] This application relates to the field of hydrometallurgy, and more particularly to a method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc process. Background Technology

[0002] Zinc is a crucial basic metal in modern industry, and hydrometallurgical zinc refining is the mainstream zinc production method today. During hydrometallurgical zinc refining, some of the cobalt associated with the zinc concentrate enters the neutral leaching solution. Although zinc powder replacement can preferentially remove impurities such as copper and cadmium, cobalt, due to its similar potential to zinc, is difficult to remove completely. Even a small amount of cobalt can severely affect zinc electrodeposition efficiency and cathode zinc quality; therefore, cobalt is considered a harmful impurity requiring deep purification and removal. Traditional methods typically use antimony or arsenic salts to activate zinc powder for deep cobalt purification. This process not only consumes a large amount of zinc powder but also results in cobalt entering the slag as impure cobalt residue. This cobalt has low grade, complex impurities, and subsequent recovery processes are lengthy, costly, and have unsatisfactory recovery rates, posing significant environmental risks and failing to achieve efficient, clean, and high-value utilization of cobalt resources.

[0003] With the rapid development of the new energy vehicle and energy storage industries, cobalt, as a key raw material for lithium-ion battery cathode materials, is increasingly demonstrating its strategic value. Therefore, developing a new technology that can directly, efficiently, and economically recover cobalt from hydrometallurgical zinc smelting systems and produce high-quality cobalt products is of great significance for improving the comprehensive resource utilization level and economic benefits of hydrometallurgical zinc smelting enterprises. Summary of the Invention

[0004] The purpose of this application is to provide a method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process, in order to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution: A method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process includes: The cobalt-containing solution from the wet zinc refining process is mixed with an organic ligand and an oxidant to carry out a cobalt precipitation reaction, followed by solid-liquid separation to obtain a cobalt-precipitated liquid and a cobalt-containing precipitate. The cobalt-containing precipitate is subjected to liquid-phase conversion treatment under closed conditions to transform the cobalt phase in the cobalt-containing precipitate, thereby obtaining a cobalt-rich intermediate. The cobalt-rich intermediate was mixed with dilute sulfuric acid to obtain a cobalt-rich solution; The cobalt-rich solution is mixed with an extractant and extracted to obtain a purified cobalt solution; Cobalt-containing products are prepared using the purified cobalt solution, wherein the cobalt-containing products include at least one of cobalt sulfate, cobalt tetroxide, and metallic cobalt.

[0006] According to embodiments of this application, the cobalt-containing solution in the wet zinc smelting process is a neutral leaching solution or a purified solution from the wet zinc smelting process. And / or, the zinc concentration in the cobalt-containing solution of the wet zinc refining process is 50-150 g / L, and the cobalt concentration is 10-200 mg / L.

[0007] According to embodiments of this application, the organic ligand includes at least one of citrate, tartrate, and gluconate; the citrate includes sodium citrate; the tartrate includes potassium sodium tartrate; and the gluconate includes sodium gluconate. And / or, the oxidant includes at least one of ammonium persulfate, hydrogen peroxide, ozone, manganese dioxide, air, and oxygen.

[0008] According to an embodiment of this application, the molar amount of the organic ligand is 1.5-3.0 times the molar amount of cobalt ions in the cobalt-containing solution of the wet zinc smelting process; And / or, the amount of oxidant added, in terms of oxidation equivalent, is 1.05-5.0 times the theoretical amount required for complete oxidation of cobalt ions in the cobalt-containing solution of the wet zinc smelting process.

[0009] According to an embodiment of this application, the cobalt precipitation reaction is carried out at a pH of 4.5-5.5, at a temperature of 60-85°C, and for a time of 30-90 minutes. And / or, when carrying out the cobalt precipitation reaction, the method further includes: controlling the pH value of the reaction system to 4.5-5.5 by adding a pH adjuster, wherein the pH adjuster includes at least one of zinc electrolytic waste liquid and dilute sulfuric acid; And / or, at the endpoint of the cobalt precipitation reaction, the concentration of cobalt ions in the solution is less than 7 mg / L.

[0010] According to embodiments of this application, the medium used in the liquid-phase conversion treatment includes any one of water, ammonia solution, and alcohol solution; And / or, the liquid phase conversion treatment is carried out at 120-250°C and 0.3-1.5 MPa; And / or, the liquid phase conversion treatment time is 1-4 hours; And / or, the cobalt-rich intermediate includes at least one of cobalt basic salts and cobalt oxides.

[0011] According to embodiments of this application, the extractant includes at least one of P204 and Cyanex 272 extractants; And / or, the extraction comprises: performing 2-4 stages of countercurrent extraction under conditions of pH 3.5-4.5, controlling the extraction ratio O / A to be (0.5-3):1, to obtain a cobalt-loaded organic phase; And / or, after obtaining the cobalt-loaded organic phase, the method further includes: back-extracting the cobalt-loaded organic phase with sulfuric acid at a concentration of 1.5-2.5 mol / L or hydrochloric acid at a concentration of 3.5-6.0 mol / L, controlling the back-extraction ratio O / A to be (2-10):1, to obtain a purified cobalt solution.

[0012] According to an embodiment of this application, when the cobalt-containing product is cobalt sulfate, the preparation of the cobalt-containing product includes: concentrating the purified cobalt solution to obtain cobalt sulfate.

[0013] According to an embodiment of this application, when the cobalt-containing product is cobalt tetroxide, the preparation of the cobalt-containing product includes: adding a precipitant to the purified cobalt solution to obtain a cobalt precursor, and after filtration, washing, and drying, calcining it at 450-650°C for 2-4 hours to obtain cobalt tetroxide; The precipitant includes at least one of sodium carbonate solution and ammonium oxalate solution, and the cobalt precursor precipitate includes at least one of cobalt carbonate and cobalt oxalate.

[0014] According to an embodiment of this application, when the cobalt-containing product is metallic cobalt, the preparation of the cobalt-containing product includes: preparing metallic cobalt from the purified cobalt solution using a closed electrolysis method.

[0015] Compared with the prior art, the beneficial effects of this application include: This application addresses the challenge of recovering cobalt resources with low concentration and high impurities from cobalt-containing solutions in hydrometallurgical zinc refining. It proposes a coupled process of "selective precipitation-phase transformation-enrichment and purification," which achieves efficient separation of cobalt. The overall cobalt recovery rate of this application is greater than 93%, the product purity can reach over 99.5%, and high-value-added cobalt-containing products have been prepared.

[0016] 1. High efficiency and high selectivity: Through the synergistic effect of organic ligands and oxidants, high efficiency and selective precipitation separation of low-concentration cobalt in zinc matrix is ​​achieved, with a one-step precipitation rate of more than 95%, which greatly enriches cobalt and provides a foundation for further purification of cobalt.

[0017] 2. Short process and low cost: This application avoids the complex steps of generating cobalt slag, transportation, and re-leaching in traditional processes. The precipitate can be converted into a high-purity intermediate in one step, which can be directly connected to the product preparation process, greatly shortening the process and reducing reagent and energy consumption.

[0018] 3. High product value: The method of this application can directly produce battery-grade cobalt sulfate, or cobalt tetroxide, or metallic cobalt. The added value of these products is much higher than that of traditional cobalt salts or crude cobalt oxides, which significantly enhances the value of resources.

[0019] 4. Environmentally friendly: The method described in this application does not introduce any toxic arsenic or antimony reagents throughout the entire process, generates little wastewater, and operates under mild reaction conditions, thus achieving clean production.

[0020] 5. High adaptability: The method of this application is not only applicable to hydrometallurgical zinc smelting systems, but can also be extended to other purification and resource utilization processes of cobalt-containing solutions. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0022] Figure 1 This is a flowchart of the method for recovering cobalt from a cobalt-containing solution in the hydrometallurgical zinc refining process, as described in this application. Detailed Implementation

[0023] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0024] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0025] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0026] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0027] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0028] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0029] A method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process, referenced. Figure 1 ,include: The cobalt-containing solution from the wet zinc refining process is mixed with an organic ligand and an oxidant to carry out a cobalt precipitation reaction, followed by solid-liquid separation to obtain a cobalt-precipitated liquid and a cobalt-containing precipitate. The cobalt-containing precipitate is subjected to liquid-phase conversion treatment under closed conditions to transform the cobalt phase in the cobalt-containing precipitate, thereby obtaining a cobalt-rich intermediate. The cobalt-rich intermediate was mixed with dilute sulfuric acid to obtain a cobalt-rich solution; The cobalt-rich solution is mixed with an extractant and extracted to obtain a purified cobalt solution; Cobalt-containing products are prepared using the purified cobalt solution, wherein the cobalt-containing products include at least one of cobalt sulfate, cobalt tetroxide, and metallic cobalt.

[0030] This application enables the efficient separation and extraction of cobalt from cobalt-containing solutions in hydrometallurgical zinc refining, and can produce high-value-added cobalt-containing products. The overall cobalt recovery rate is greater than 93%, and the purity of the cobalt-containing products can reach over 99.5%. This application achieves efficient and high-value utilization of cobalt resources during hydrometallurgical zinc refining. Furthermore, this application has advantages such as a short process flow, low cost, and environmental friendliness. Specifically, this application abandons the lengthy traditional path of generating and reprocessing "cobalt slag," directly targeting the purified cobalt-containing solution (cobalt concentration typically 10-200 mg / L). By introducing specific organic ligands and oxidants, a selective precipitation reaction of cobalt ions is induced under mild conditions, achieving preliminary and efficient separation of cobalt from zinc and other impurities. Then, the initial precipitate undergoes a mild phase transformation treatment, significantly improving its purity and crystallinity, obtaining a cobalt-rich intermediate that is easy to process later. Finally, through a simplified dissolution-purification-crystallization / calcination process, the battery-grade cobalt products required by the market are directly produced.

[0031] According to embodiments of this application, the cobalt-containing solution in the wet zinc smelting process is a neutral leaching solution or a purified solution from the wet zinc smelting process. Furthermore, the cobalt-containing solution in the wet zinc smelting process is a neutral leachate or purified solution obtained by zinc powder replacement purification to remove impurities such as copper and cadmium.

[0032] The zinc concentration in the cobalt-containing solution of the wet zinc smelting process is 50-150 g / L, and the cobalt concentration is 10-200 mg / L.

[0033] For example, the zinc concentration in the cobalt-containing solution of the wet zinc smelting process is 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L, 135 g / L, 140 g / L, 145 g / L, 150 g / L, or any value between 50 and 150 g / L; the cobalt concentration in the cobalt-containing solution of the wet zinc smelting process is 10 mg / L, 30 mg / L, 50 mg / L, 80 mg / L, 100 mg / L, 120 mg / L, 150 mg / L, 180 mg / L, 200 mg / L, or any value between 10 and 200 mg / L.

[0034] According to embodiments of this application, the organic ligand includes at least one of citrate, tartrate, and gluconate; the acid radical in the organic ligand can react with Co in solution. 2+ The formation of complexes can effectively reduce the oxidation potential of divalent cobalt and promote the oxidation of Co. 3+ The formation of [the substance] creates conditions for precipitation and subsequent phase transformation; the citrate includes sodium citrate; the tartrate includes potassium sodium tartrate; and the gluconate includes sodium gluconate.

[0035] The oxidant includes at least one of ammonium persulfate, hydrogen peroxide, ozone, manganese dioxide, air, and oxygen.

[0036] According to the embodiments of this application, the molar amount of the organic ligand is 1.5-3.0 times the molar amount of cobalt ions in the cobalt-containing solution of the wet zinc smelting process. When the amount of organic ligand is controlled within the above range, the cobalt ions can be fully complexed, production costs can be effectively controlled, and reagent waste can be avoided. If the amount of organic ligand is too small, the complexation reaction will be insufficient, which will affect the cobalt recovery effect. If the amount of organic ligand is too large, it will cause reagent waste and increase production costs.

[0037] For example, the molar amount of the organic ligand is any value between 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, or 1.5-3.0 times the molar amount of cobalt ions in the cobalt-containing solution of wet zinc refining.

[0038] The amount of oxidant added, in terms of oxidation equivalent, is 1.05-5.0 times the theoretical amount required for complete oxidation of cobalt ions in the cobalt-containing solution of the wet zinc smelting process. If the amount of oxidant added is too small, it will lead to incomplete oxidation, thus affecting the cobalt recovery effect; if the amount of oxidant added is too large, it will result in waste of reagents.

[0039] For example, the amount of oxidant added, expressed as oxidation equivalent, is any value between 1.05, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, or 1.05-5.0 times the theoretical amount required for complete oxidation of cobalt ions in the cobalt-containing solution of wet zinc smelting.

[0040] According to the embodiments of this application, the cobalt precipitation reaction is carried out under conditions of pH 4.5-5.5. If the cobalt precipitation reaction is carried out at too low pH, the precipitation reaction will be insufficient; if the cobalt precipitation reaction is carried out at too high pH, ​​a large amount of zinc precipitation will be lost.

[0041] The temperature of the cobalt precipitation reaction is 60-85℃, and the reaction time is 30-90 minutes; For example, the pH value of the cobalt precipitation reaction can be any value between 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5 or 4.5-5.5; the temperature of the cobalt precipitation reaction can be any value between 60℃, 65℃, 70℃, 75℃, 80℃, 85℃ or 60-85℃; and the time of the cobalt precipitation reaction can be any value between 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes or 30-90 minutes.

[0042] When performing the cobalt precipitation reaction, the method further includes: controlling the pH value of the reaction system to 4.5-5.5 by adding a pH adjuster, wherein the pH adjuster includes at least one of zinc electrolytic waste liquid and dilute sulfuric acid; Through the cobalt precipitation reaction, cobalt ions in the cobalt-containing solution of wet zinc smelting can be selectively converted into precipitates, while zinc and other trace impurity ions remain in the solution.

[0043] The concentration of cobalt ions in the solution at the endpoint of the cobalt precipitation reaction is less than 7 mg / L. For example, the concentration of cobalt ions in the solution at the endpoint of the cobalt precipitation reaction can be 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, or any value less than 7 mg / L.

[0044] According to embodiments of this application, the medium used in the liquid-phase conversion treatment includes any one of water, ammonia solution, and alcohol solution; further, the alcohol in the alcohol solution can be a low molecular weight alcohol compound.

[0045] The liquid-phase conversion treatment is carried out at 120-250℃ and 0.3-1.5 MPa. For example, the temperature of the liquid phase conversion treatment is 120℃, 150℃, 180℃, 200℃, 230℃, 250℃ or any value between 120℃ and 250℃; the pressure of the liquid phase conversion treatment is 0.3MPa, 0.5MPa, 0.8MPa, 1MPa, 1.3MPa, 1.5MPa or any value between 0.3MPa and 1.5MPa.

[0046] The liquid phase conversion treatment time is 1-4 hours; for example, the liquid phase conversion treatment time is 1 hour, 2 hours, 3 hours, 4 hours or any value between 1 and 4 hours.

[0047] The cobalt-rich intermediate includes at least one of cobalt basic salts and cobalt oxides.

[0048] By performing liquid-phase conversion treatment under the above conditions, a high-purity cobalt-rich intermediate can be obtained.

[0049] In some embodiments, the method for preparing the cobalt-rich solution includes: mixing a cobalt-rich intermediate with dilute sulfuric acid under heating conditions to obtain a cobalt-rich solution. This allows the cobalt-rich intermediate to dissolve, facilitating further purification. The dilute sulfuric acid used in this step can be dilute sulfuric acid with a mass fraction of 8%-12% (e.g., 8%, 9%, 10%, 11%, 12%, or any value between 8% and 12%). The heating temperature can be 55-70℃ (e.g., 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, or any value between 55-70℃).

[0050] According to embodiments of this application, the extractant includes at least one of P204 and Cyanex 272 extractants; The extraction process includes: performing 2-4 stages of countercurrent extraction under conditions of pH 3.5-4.5, controlling the extraction ratio O / A to be (0.5-3):1, to obtain a cobalt-loaded organic phase.

[0051] In some embodiments, after obtaining the cobalt-loaded organic phase, the method further includes: back-extracting the cobalt-loaded organic phase with sulfuric acid at a concentration of 1.5-2.5 mol / L or hydrochloric acid at a concentration of 3.5-6.0 mol / L, controlling the back-extraction ratio O / A to be (2-10):1, to obtain a purified cobalt solution.

[0052] For example, the extraction pH is 3.5, 4, 4.5, or any value between 3.5 and 4.5; the countercurrent extraction stages are 2, 3, 4, or any value between 2 and 4 stages; the extraction ratio O / A is 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any value between (0.5-3):1; the back-extraction ratio O / A is 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any value between (2-10):1.

[0053] Extraction can be used to deeply purify cobalt-rich solutions and remove residual impurities such as nickel and manganese.

[0054] According to an embodiment of this application, when the cobalt-containing product is cobalt sulfate, the preparation of the cobalt-containing product includes: concentrating the purified cobalt solution to obtain cobalt sulfate.

[0055] According to an embodiment of this application, when the cobalt-containing product is cobalt tetroxide, the preparation of the cobalt-containing product includes: adding a precipitant to the purified cobalt solution to obtain a cobalt precursor, filtering, washing, and drying it, and then calcining it at 450-650℃ (e.g., 450℃, 500℃, 550℃, 600℃, 650℃ or any value between 450-650℃) for 2-4 hours (e.g., 2 hours, 3 hours, 4 hours or any value between 2-4 hours) to obtain cobalt tetroxide; The precipitant includes at least one of sodium carbonate solution and ammonium oxalate solution, and the cobalt precursor precipitate includes at least one of cobalt carbonate and cobalt oxalate.

[0056] According to an embodiment of this application, when the cobalt-containing product is metallic cobalt, the preparation of the cobalt-containing product includes: preparing metallic cobalt from the purified cobalt solution using a closed electrolysis method. Furthermore, the oxygen and acid mist produced at the anode can be collected through the closed electrolysis system and discharged in an organized manner.

[0057] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0058] Example 1 Example 1 provides a method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process, comprising: (1) A neutral leachate from a hydrometallurgical zinc plant after zinc powder replacement purification to remove copper and cadmium was taken. Its composition was: Zn 150 g / L, Co 80 mg / L, Cd < 1 mg / L, Cu < 0.5 mg / L. The solution temperature was controlled at 70℃. Sodium citrate (the molar amount of sodium citrate was 2.0 times the molar amount of Co in the solution) was added under stirring, and the pH was adjusted to 5.0 with dilute sulfuric acid. Then ammonium persulfate solution was slowly added (the amount of ammonium persulfate solution added was 1.2 times the theoretical amount required for complete oxidation of cobalt ions in the solution, calculated by oxidation equivalent), and the reaction was carried out at a constant temperature for 60 minutes. After the reaction was completed, the solution was filtered under pressure to obtain a dark brown precipitate. The cobalt concentration in the filtrate decreased to 3.2 mg / L, and the cobalt precipitation rate exceeded 96%.

[0059] (2) The above precipitate was transferred to a high-pressure reactor, and deionized water was added to make a slurry. The slurry was then subjected to hydrothermal reaction at 180°C and 0.8 MPa for 2 hours. After the reaction was completed, the precipitate was filtered and washed to obtain a black powdery intermediate. XRD analysis showed that the main component was Co3O4, and the purity was significantly improved.

[0060] (3) Dissolve the intermediate in a 10% dilute sulfuric acid solution at 60°C to obtain a cobalt sulfate solution with a Co concentration of about 25 g / L.

[0061] (4) Mix cobalt sulfate solution with P204 extractant (saponification rate 70%), and perform three-stage countercurrent extraction under pH=4.0 conditions, controlling the extraction ratio O / A to be 3:1, to obtain cobalt-loaded organic phase; back-extract the cobalt-loaded organic phase with 1.53 mol / L sulfuric acid, controlling the back-extraction ratio O / A to be 6:1, to obtain pure cobalt sulfate solution.

[0062] (5) The cobalt sulfate solution was concentrated to a cobalt concentration of 120 g / L, cooled to crystallize, centrifuged, and dried at 80°C to obtain battery-grade cobalt sulfate (CoSO4·7H2O) product. The product quality met the standard for battery-grade cobalt sulfate (HG / T 5918-2021), with a Co content ≥20.5%. The total cobalt recovery rate of the entire process was 94.5%. Example 2 Example 2 provides a method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process, comprising: (1) Take the purified liquid from another hydrometallurgical zinc smelting system, whose composition is: Zn 130 g / L, Co 120 mg / L, Ni 15 mg / L. Control the solution temperature at 80℃, add potassium sodium tartrate (the molar amount of potassium sodium tartrate is 2.5 times the molar amount of Co in the solution), and adjust the pH to 5.2 with zinc electrolysis waste liquid. Add hydrogen peroxide as an oxidant. The amount of hydrogen peroxide added, based on the oxidation equivalent, is 1.9 times the theoretical amount required for complete oxidation of cobalt ions in the cobalt-containing solution of the hydrometallurgical zinc smelting. React for 90 minutes. Filter to obtain the precipitate, and the cobalt concentration of the filtrate is 4.8 mg / L.

[0063] (2) Precipitation was carried out in a 20% ammonia solution as a medium and subjected to solvothermal treatment at 150℃ and 0.9MPa for 2.5 hours to obtain a cobalt-rich intermediate.

[0064] (3) Dissolve the obtained cobalt-rich intermediate in a 10% sulfuric acid solution at 60°C to obtain a cobalt-rich solution; (4) Mix the cobalt-rich solution with Cyanex 272 extractant and perform two-stage countercurrent extraction at a pH of 4.5, controlling the extraction ratio O / A to be 1.5:1, to remove impurities such as nickel and obtain a purified cobalt solution.

[0065] (5) Add ammonium oxalate solution to the purified cobalt solution to precipitate cobalt oxalate. After filtration, washing and drying, the precipitate is calcined in a muffle furnace at 550℃ for 3 hours to obtain cobalt tetroxide powder. The product quality meets the cobalt tetroxide standard (YS / T633-2024), with a Co content ≥72.6%. The overall cobalt recovery rate is 93.8%.

[0066] Example 3 Example 3 provides a method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process, comprising: (1) A simulated solution was prepared after purification in a hydrometallurgical zinc smelting system. The composition of the solution was: Zn 140 g / L, Co 100 mg / L, Ni 30 mg / L. The solution temperature was controlled at 80℃. Sodium gluconate was added (the molar amount of sodium gluconate was 2.0 times the molar amount of Co in the solution). The pH was adjusted to 5.2 using zinc electrolysis waste liquid. Air was introduced as an oxidant. The amount of oxidant added was 4.5 times the theoretical amount required for complete oxidation of cobalt ions in the cobalt-containing solution of the hydrometallurgical zinc smelting system, based on oxidation equivalents. The reaction was bubbled for 90 minutes. The precipitate was obtained by filtration, and the cobalt concentration of the filtrate was 7 mg / L.

[0067] (2) Precipitation was carried out in a 20% ammonia solution as a medium and subjected to solvothermal treatment at 130℃ and 0.7 MPa for 3 hours to obtain a cobalt-rich intermediate.

[0068] (3) The cobalt-rich intermediate was dissolved in a 10% sulfuric acid solution at 70°C to obtain a cobalt-rich solution; (4) Mix the cobalt-rich solution with Cyanex 272 extractant and perform three-stage countercurrent extraction at a pH of 4.0, controlling the extraction ratio O / A to be 1:1, to remove impurities such as nickel and obtain a purified cobalt solution.

[0069] (5) The cobalt solution is purified and subjected to closed-loop electrolysis in a sulfuric acid system to produce metallic cobalt. At the same time, the oxygen generated at the anode is recovered and can be used as an oxidant in the aforementioned process. The purity of metallic cobalt is ≥99.8%, and the overall cobalt recovery rate is 94.7%.

[0070] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that sodium citrate is not added in step (1). Everything else is the same as in Example 1.

[0071] After the reaction in step (1) of Comparative Example 1 was completed, the solution was filtered under pressure. The cobalt concentration in the filtrate was 68.4 mg / L, and the cobalt precipitation rate was only 14.5%. This indicates that without an organic ligand, cobalt is difficult to effectively oxidize and precipitate.

[0072] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that ammonium persulfate solution is not added in step (1). Everything else is the same as in Example 1.

[0073] After the reaction in step (1) of Comparative Example 2 was completed, the solution was filtered under pressure. The cobalt concentration in the filtrate was 79.8 mg / L, and the cobalt precipitation rate was only 0.25%, with almost no precipitation. This indicates that in the absence of an oxidizing agent, cobalt exists in the solution as a stable complex.

[0074] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that in step (1) of Comparative Example 3, an equal molar amount of glycine was used instead of sodium citrate in Example 1. Everything else was the same as in Example 1.

[0075] After the reaction in step (1) of Comparative Example 3 was completed, solid-liquid separation was performed. The residual concentration of cobalt in the solution was 52 mg / L, and the precipitation rate was only 35%. This may be because glycine has insufficient complexing ability for cobalt under weakly acidic conditions and tends to coprecipitate zinc, resulting in poor cobalt-zinc separation.

[0076] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that in step (1) of Comparative Example 4, sodium hypochlorite solution with an equivalent oxidizing amount is used instead of ammonium persulfate solution in Example 1. Everything else is the same as in Example 1.

[0077] After the reaction in step (1) of Comparative Example 4 was completed, the solution was filtered under pressure. The cobalt concentration in the filtrate was 5.6 mg / L, the cobalt precipitation rate was 93.0%, and the filtrate contained chloride ions. This indicates that using sodium hypochlorite solution as an oxidant can achieve the effect of oxidation and precipitation, but it will introduce chloride ions as impurities, which will pollute the neutral leachate.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0079] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process, characterized in that, include: The cobalt-containing solution from the wet zinc refining process is mixed with an organic ligand and an oxidant to carry out a cobalt precipitation reaction, followed by solid-liquid separation to obtain a cobalt-precipitated liquid and a cobalt-containing precipitate. The cobalt-containing precipitate is subjected to liquid-phase conversion treatment under closed conditions to transform the cobalt phase in the cobalt-containing precipitate, thereby obtaining a cobalt-rich intermediate. The cobalt-rich intermediate was mixed with dilute sulfuric acid to obtain a cobalt-rich solution; The cobalt-rich solution is mixed with an extractant and extracted to obtain a purified cobalt solution; Cobalt-containing products are prepared using the purified cobalt solution, wherein the cobalt-containing products include at least one of cobalt sulfate, cobalt tetroxide, and metallic cobalt.

2. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to claim 1, characterized in that, The cobalt-containing solution in the hydrometallurgical zinc refining process is a neutral leaching solution or a purified solution from the hydrometallurgical zinc refining process. And / or, the zinc concentration in the cobalt-containing solution of the wet zinc refining process is 50-150 g / L, and the cobalt concentration is 10-200 mg / L.

3. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to claim 1, characterized in that, The organic ligand includes at least one of citrate, tartrate, and gluconate; the citrate includes sodium citrate; the tartrate includes potassium sodium tartrate; and the gluconate includes sodium gluconate. And / or, the oxidant includes at least one of ammonium persulfate, hydrogen peroxide, ozone, manganese dioxide, air, and oxygen.

4. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to claim 2, characterized in that, The molar amount of the organic ligand is 1.5-3.0 times the molar amount of cobalt ions in the cobalt-containing solution of the wet zinc smelting process; And / or, the amount of oxidant added, in terms of oxidation equivalent, is 1.05-5.0 times the theoretical amount required for complete oxidation of cobalt ions in the cobalt-containing solution of the wet zinc smelting process.

5. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to claim 2, characterized in that, The cobalt precipitation reaction is carried out at a pH of 4.5-5.5, at a temperature of 60-85℃, and for a time of 30-90 minutes. And / or, when carrying out the cobalt precipitation reaction, the method further includes: controlling the pH value of the reaction system to 4.5-5.5 by adding a pH adjuster, wherein the pH adjuster includes at least one of zinc electrolytic waste liquid and dilute sulfuric acid; And / or, at the endpoint of the cobalt precipitation reaction, the concentration of cobalt ions in the solution is less than 7 mg / L.

6. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to claim 1, characterized in that, The medium used in the liquid phase conversion treatment includes any one of water, ammonia solution, and alcohol solution; And / or, the liquid phase conversion treatment is carried out at 120-250°C and 0.3-1.5 MPa; And / or, the liquid phase conversion treatment time is 1-4 hours; And / or, the cobalt-rich intermediate includes at least one of cobalt basic salts and cobalt oxides.

7. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to claim 1, characterized in that, The extractant includes at least one of P204 and Cyanex 272 extractants; And / or, the extraction comprises: performing 2-4 stages of countercurrent extraction under conditions of pH 3.5-4.5, controlling the extraction ratio O / A to be (0.5-3):1, to obtain a cobalt-loaded organic phase; And / or, after obtaining the cobalt-loaded organic phase, the method further includes: back-extracting the cobalt-loaded organic phase with sulfuric acid at a concentration of 1.5-2.5 mol / L or hydrochloric acid at a concentration of 3.5-6.0 mol / L, controlling the back-extraction ratio O / A to be (2-10):1, to obtain a purified cobalt solution.

8. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to any one of claims 1-7, characterized in that, When the cobalt-containing product is cobalt sulfate, the preparation of the cobalt-containing product includes: concentrating the purified cobalt solution to obtain cobalt sulfate.

9. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to any one of claims 1-7, characterized in that, When the cobalt-containing product is cobalt tetroxide, the preparation of the cobalt-containing product includes: adding a precipitant to the purified cobalt solution to obtain a cobalt precursor, and after filtration, washing, and drying, calcining it at 450-650℃ for 2-4 hours to obtain cobalt tetroxide; The precipitant includes at least one of sodium carbonate solution and ammonium oxalate solution, and the cobalt precursor precipitate includes at least one of cobalt carbonate and cobalt oxalate.

10. The method for recovering cobalt from a cobalt-containing solution in a hydrometallurgical zinc refining process according to any one of claims 1-7, characterized in that, When the cobalt-containing product is metallic cobalt, the preparation of the cobalt-containing product includes: preparing metallic cobalt from the purified cobalt solution by closed electrolysis.

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