A process for the recovery of cobalt from cobalt-containing copper raffinate

Abstract

This invention relates to a method for recovering cobalt from cobalt-containing copper raffinate, comprising the following steps: (1) adding a first precipitant to the cobalt-containing copper raffinate for pre-removal of impurities, followed by solid-liquid separation to obtain a post-removal liquid and impurity residue; (2) adding a second precipitant to the post-removal liquid for cobalt precipitation, followed by solid-liquid separation to obtain a post-precipitation liquid and cobalt precipitation residue; (3) adding a leaching agent to the cobalt precipitation residue and performing solid-liquid separation to obtain leaching residue and leaching liquid; (4) adding a third precipitant and an oxidizing agent to the leaching liquid for oxidative cobalt precipitation, followed by solid-liquid separation to obtain a post-precipitation liquid and cobalt-enriched residue; (5) adding a transformation agent to the cobalt-enriched residue for transformation leaching, followed by solid-liquid separation to obtain a cobalt-enriched liquid and transformation residue; (6) cooling and crystallizing the cobalt-enriched liquid and performing solid-liquid separation to obtain crystalline cobalt salt and crystallized liquid. This invention achieves efficient cobalt recovery and high-purity product preparation with low reagent consumption and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of metallurgical separation technology, and in particular to a method for recovering cobalt from cobalt-containing copper raffinate. Background Technology

[0002] Cobalt, as a strategic metal, is widely used in key areas such as power batteries for new energy vehicles. my country is poor in cobalt resources and mainly relies on imports from the Democratic Republic of Congo (DRC). Currently, DRC cobalt products primarily come from the cobalt-containing copper leaching residue of copper oxide cobalt ore. The process typically involves "wet leaching - extraction to remove copper - neutralization with calcium oxide or calcium carbonate to remove iron, aluminum, and manganese - magnesium oxide precipitation of cobalt - calcium oxide removal of magnesium" to produce crude cobalt hydroxide intermediates. However, in actual industrial applications, there are still a series of problems, including low iron removal rates, slow iron slag settling and easy turbidity, significant cobalt loss during impurity removal, and high costs of neutralizing agents such as calcium oxide, calcium carbonate, and magnesium oxide. Furthermore, crude cobalt hydroxide products generally have low cobalt content, typically 20-40%, with high levels of impurities such as Fe, Mn, and Mg, making subsequent purification difficult.

[0003] To further improve the grade of crude cobalt hydroxide, CN112626337A discloses a method of co-precipitating copper, zinc, cobalt, iron, and manganese ions with sulfides, followed by stepwise leaching of manganese, iron, and cobalt with sulfuric acid on the precipitate residue. The resulting cobalt-rich leaching solution is then used to produce crude cobalt hydroxide. However, the sulfidation method suffers from high reagent costs, the easy generation of toxic H2S gas, and residual sulfur in the precipitate solution. 2- Problems such as the need for separate treatment and high acid consumption during secondary leaching make it difficult to apply on a large scale. CN114959299A discloses a strategy of using phosphoric acid extractants to pre-remove impurities such as iron, aluminum, and zinc, and then using hydroxyoxime extractants to extract cobalt. However, the organic reagents used in the extraction method are expensive, the wastewater treatment volume is large, and with the addition of the copper removal process in the front-end extractant, the process involves multiple different organic phase systems, and the mechanism of mutual influence is unclear.

[0004] Furthermore, the obtained crude cobalt hydroxide intermediate still requires acid dissolution followed by cobalt separation and purification to obtain a high-purity cobalt product. CN120555764A discloses a method of leaching cobalt with a reducing agent, followed by adding a cobalt complexing agent and an oxidizing agent for deep manganese removal, achieving the separation of cobalt and manganese. To reduce the production cost of impurity removal and purification of crude cobalt hydroxide, CN113046574A discloses a method of dissolving crude cobalt hydroxide in the copper electrolytic copper-removing solution, followed by neutralization to remove iron, fluorination to remove calcium and magnesium, P204 extraction for deep removal of iron, copper, zinc, and manganese impurities, and P507 extraction to separate nickel and cobalt.

[0005] Existing cobalt raw material processing and cobalt product preparation technologies generally suffer from prominent drawbacks such as poor process flow, high reagent consumption, lengthy process flows, high production costs, low material recovery rates, and weak adaptability to local raw material processing scenarios, failing to effectively alleviate supply chain pressures. Therefore, overcoming the challenges of seamless process flow in cobalt extraction from cobalt-containing copper leaching residue, reducing ineffective and repeated reagent consumption, shortening the overall production process, lowering comprehensive production costs, and simultaneously adapting to the local processing requirements of overseas raw materials and the urgent needs of domestic downstream industries to achieve efficient, low-cost, and stable production of cobalt-containing products has become a critical technical issue urgently needing to be addressed in the cobalt smelting industry. Summary of the Invention

[0006] To address the aforementioned technical issues, this invention employs a synergistic process involving pre-removal of impurities, cobalt precipitation, selective leaching, cobalt enrichment through oxidation precipitation, transformation leaching, and cooling crystallization. This process enables the efficient recovery and purification of cobalt resources from cobalt-containing copper leaching residues. The materials can be recycled, significantly reducing the ineffective consumption of various reagents. It simplifies operational procedures, shortens the overall process, and balances the operability of the process with the needs of low-cost, large-scale production. It can stably produce qualified cobalt products, effectively alleviating the cobalt raw material supply pressure in the domestic lithium battery industry.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for recovering cobalt from cobalt-containing copper raffinate, comprising the following steps: (1) Add the first precipitant to the cobalt-containing copper raffinate to remove impurities, and then separate the solid and liquid to obtain the purified liquid and impurity residue; (2) Add a second precipitant to the purified liquid to precipitate cobalt, and separate the solid and liquid to obtain the cobalt-precipitated liquid and the cobalt-precipitated slag; (3) The cobalt precipitate residue is added to the leaching agent and then leached to separate the solid and liquid, resulting in leaching residue and leaching solution; (4) The leachate is added with a third precipitant and an oxidant to oxidize and precipitate cobalt, and the solid and liquid are separated to obtain the precipitated liquid and the cobalt-enriched residue; (5) The cobalt enrichment slag is added to a transformation agent for transformation leaching, and solid-liquid separation is performed to obtain cobalt enrichment liquid and transformation slag; (6) After the cobalt enrichment solution is cooled and crystallized, solid-liquid separation is performed to obtain crystalline cobalt salt and crystallized liquid.

[0008] This invention removes iron, aluminum, and manganese impurities through pre-treatment, enriches cobalt through selective cobalt precipitation, and then leaches the cobalt-precipitated slag followed by oxidative cobalt precipitation. The precipitant introduced during the oxidation precipitation can be removed in the conversion leaching step. Impurities are removed stepwise, useful components are recyclable, harmful ions do not accumulate, and the material can be recycled for deep purification. High-purity cobalt solution is obtained through conversion leaching, and finally, crystalline cobalt salt is obtained through cooling and crystallization. The process is compact, has a high recycling rate, and significantly improves cobalt recovery rate and product purity.

[0009] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0010] The present invention does not limit the solid-liquid separation described herein, and any method known to those skilled in the art for solid-liquid separation may be used, such as filtration, sedimentation or centrifugation.

[0011] As a preferred technical solution of the present invention, the cobalt-containing copper raffinate in step (1) contains, in addition to cobalt ions, any one or at least two of the following: calcium ions, magnesium ions, iron ions, aluminum ions, copper ions, zinc ions, manganese ions, and silicon ions.

[0012] Preferably, the cobalt-containing copper raffinate is derived from the raffinate obtained after acid leaching and extraction of copper from copper-cobalt ore.

[0013] Preferably, the first precipitant comprises a combination of calcium carbonate and sulfur dioxide.

[0014] Preferably, the calcium carbonate is pre-mixed into a calcium carbonate slurry at a mass concentration of 10-30%, for example, it can be 10%, 15%, 20%, 25% or 30%, etc., to achieve uniform feeding and avoid local over-alkaliness.

[0015] Preferably, the sulfur dioxide is mixed with compressed air and then introduced into the reaction system. The volume concentration of sulfur dioxide in the mixed gas is 1-5%, for example, it can be 1%, 2%, 3%, 4% or 5%, etc., and the pressure of the mixed gas is 0.1-1 MPa, for example, it can be 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa or 1.0 MPa, etc.

[0016] Preferably, the proportion of -0.074mm particles in the calcium carbonate is 50-80%, for example, it can be 50%, 60%, 70%, 75% or 80%, etc., to ensure that the particles have a suitable specific surface area and reactivity, so that the neutralization and cobalt precipitation rate is moderate and complete.

[0017] Preferably, the pre-removal temperature is 25~50℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃, etc.

[0018] Preferably, the pre-removal process involves stirring for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, etc.

[0019] Preferably, the endpoint pH of the pre-removal is 4.5 to 5.5, for example, it can be 4.5, 4.8, 5.0, 5.2, 5.5, etc., to remove most of the impurities such as iron ions, aluminum ions, silicon ions and manganese ions.

[0020] Preferably, the gas generated in the pre-removal process is introduced into step (5) to assist the transformation leaching. The generated carbon dioxide gas can increase the carbonate concentration in the transformation leaching, strengthen the coordination environment of the transformation system, promote the efficient complexation leaching of cobalt, and at the same time allow calcium to precipitate more fully in the form of calcium carbonate, improve the separation effect of cobalt and calcium, and also inhibit the decomposition of ammonium salt, reduce ammonia volatilization, and stabilize the reaction pH.

[0021] As a preferred technical solution of the present invention, in step (2), the second precipitant includes calcium oxide; Preferably, the calcium oxide is pre-mixed into a calcium oxide slurry at a mass concentration of 10-30% to achieve uniform feeding and avoid local over-alkaliness.

[0022] Preferably, the proportion of -0.074mm particles in the calcium oxide is 50-80%, for example, it can be 50%, 60%, 70%, 75% or 80%.

[0023] Preferably, the temperature for cobalt deposition is 25~50℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃.

[0024] Preferably, the cobalt precipitation process involves stirring for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, or 4 hours.

[0025] Preferably, the final pH of the cobalt precipitation is 7-8, such as 7.0, 7.2, 7.5, 7.8, 8.0, etc., to ensure that cobalt ions in the solution are fully precipitated, while reducing the co-precipitation of other impurity ions, and achieving further separation of cobalt from some impurities.

[0026] Preferably, the cobalt-precipitated liquid is returned to the copper-cobalt ore leaching process for reuse and / or used as a dispersion solvent for calcium carbonate slurry and calcium oxide slurry, thereby achieving water recycling and reducing cobalt loss.

[0027] As a preferred technical solution of the present invention, the leaching agent in step (3) includes a combination of ammonium sulfate solution and ammonia water.

[0028] Preferably, the solid-liquid ratio of the cobalt precipitate to the ammonium sulfate solution is 1:(1~10)g / mL, for example, it can be 1:1, 1:3, 1:5, 1:8 or 1:10g / mL, etc.

[0029] Preferably, the concentration of the ammonium sulfate solution is 150~250 g / L, for example, it can be 150 g / L, 180 g / L, 200 g / L, 220 g / L or 250 g / L.

[0030] Preferably, the amount of ammonia water added, calculated as NH3, is 5.0 to 6.5 times the molar amount of cobalt in the cobalt precipitate, for example, it can be 5.0 times, 5.5 times, 5.8 times, 6.0 times, or 6.5 times.

[0031] Preferably, the leaching temperature is 25~100℃, for example, it can be 25℃, 40℃, 60℃, 80℃ or 100℃.

[0032] Preferably, the leaching process involves stirring for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, or 4 hours.

[0033] As a preferred technical solution of the present invention, the oxidant for oxidizing cobalt in step (4) includes any one or a combination of at least two of air, oxygen, hydrogen peroxide and ammonium persulfate.

[0034] Preferably, the third precipitant in step (4) includes calcium sulfate.

[0035] Preferably, the amount of oxidant added is 0.5 to 1.5 times the molar amount of cobalt ions, based on the effective oxidizing component, for example, it can be 0.5 times, 0.8 times, 1.0 times, 1.2 times or 1.5 times, etc.

[0036] Preferably, the leaching residue in step (3) is used as the third precipitant in step (4). The amount of leaching residue added, based on the amount of calcium sulfate, is 2.0 to 3.0 times the molar amount of cobalt ions in the leaching solution; for example, it can be 2.0 times, 2.2 times, 2.5 times, 2.8 times, or 3.0 times, etc. The main component of the leaching residue, calcium sulfate, can form an insoluble calcium cobalt ammonium precipitate with cobalt ions and ammonium ions in the solution, thereby achieving the precipitation and enrichment of cobalt. The dosage range ensures the complete reaction of the double salt precipitation, improves the cobalt recovery rate, and the calcium sulfate comes from the self-produced leaching residue, which can realize the resource utilization of solid waste, without introducing foreign impurities, and recovering trace amounts of unleached cobalt.

[0037] Preferably, the reaction temperature for cobalt oxide precipitation is 50~150℃, for example, it can be 50℃, 80℃, 100℃, 120℃ or 150℃.

[0038] Preferably, the cobalt oxide precipitation process is stirred for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours or 4 hours.

[0039] Preferably, when the oxidant is air or oxygen, the partial pressure of oxygen is 0.1~1.0 MPa, for example, it can be 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa or 1.0 MPa, and the gas flow rate is 0.1~1 L / min, for example, it can be 0.1 L / min, 0.3 L / min, 0.5 L / min, 0.8 L / min or 1 L / min.

[0040] As a preferred technical solution of the present invention, after the precipitated liquid is cooled and crystallized in step (4), solid-liquid separation is performed to obtain crystalline double salt and crystalline liquid.

[0041] Preferably, the crystallized liquid after precipitation is returned to step (3) as a leaching agent, making full use of the residual ammonium ions therein, realizing the recycling of ammonium salt components, greatly reducing the amount of fresh leaching agent added, and reducing the cost of the reagent.

[0042] Preferably, the temperature at which the precipitated liquid is cooled and crystallized is 5~25℃, for example, it can be 5℃, 10℃, 15℃, 20℃ or 25℃.

[0043] Preferably, the crystalline double salt comprises any one or a combination of at least two of ammonium copper sulfate, ammonium zinc sulfate, ammonium magnesium sulfate, and ammonium manganese sulfate.

[0044] As a preferred technical solution of the present invention, the transforming agent in step (5) includes ammonium carbonate solution and / or ammonium bicarbonate solution, which selectively react with calcium cobalt ammonium complex salt to convert cobalt into soluble cobalt ammonium complex, while calcium is separated in the form of calcium carbonate precipitate, thereby achieving efficient separation of cobalt and calcium.

[0045] Preferably, the concentration of the transforming agent is 50~200g / L, for example, it can be 50g / L, 80g / L, 100g / L, 150g / L, 180g / L or 200g / L.

[0046] Preferably, the solid-liquid ratio of the transformation leaching is 1:(1~10)g / mL, for example, it can be 1:1g / mL, 1:3g / mL, 1:5g / mL, 1:8g / mL or 1:10g / mL, etc.

[0047] Preferably, the temperature of the transformation leaching is 25~100℃, for example, 25℃, 50℃, 75℃ or 100℃, and the time is 0.5~4h, for example, 0.5h, 1h, 2h or 4h.

[0048] As a preferred technical solution of the present invention, the transformation slag in step (5) is returned to step (1) to prepare the first precipitant. The calcium carbonate component therein is used to realize the recycling of calcium source, reduce the use of purchased precipitant, reduce production costs, eliminate the need for additional treatment of transformation slag, and avoid the discharge of solid waste.

[0049] As a preferred technical solution of the present invention, the cooling crystallization temperature in step (6) is 25~50℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃, etc., and the time is 0.5~5h, for example, it can be 0.5h, 1h, 2h, 3h, 4h or 5h, etc.

[0050] As a preferred technical solution of the present invention, the crystalline cobalt salt is roasted to obtain a cobalt product.

[0051] Preferably, the crystalline cobalt salt comprises ammonium cobalt sulfate.

[0052] Preferably, the cobalt product is cobalt sulfate or cobalt oxide, and different cobalt products are produced by controlling the roasting temperature.

[0053] Preferably, the roasting temperature is 300~800℃, for example, 300℃, 400℃, 500℃, 600℃, 700℃ or 800℃, and the roasting time is 1~6h, for example, 1h, 2h, 3h, 4h, 5h or 6h.

[0054] Preferably, the liquid after crystallization in step (6) is returned to step (5) as a transforming agent, utilizing the residual ammonium carbonate, ammonium bicarbonate and ammonium ions therein to reduce the addition of fresh reagents, reduce production costs, avoid the discharge of ammonium salt waste liquid, and at the same time recover cobalt in the liquid after crystallization to reduce cobalt loss.

[0055] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention has a complete process flow of calcium precipitation of cobalt, oxidation to remove impurities, double salt precipitation and ammonium salt transformation. The process route is simple and the reaction conditions are mild. It can directly treat the complex raffinate. The process design realizes the directional enrichment and purification of cobalt. It solves the technical problems of long process flow, poor adaptability and large cobalt loss in traditional process. The cobalt precipitation rate and leaching rate in the process are both above 99%, and the comprehensive cobalt recovery rate is ≥94.8%, and can reach up to 95.83%. (2) This invention achieves efficient separation of cobalt and calcium by combining calcium cobalt ammonium salt precipitation with ammonium carbonate conversion. It can selectively enrich cobalt in complex cobalt-containing copper extraction residue, with high cobalt recovery rate and product purity, effectively solving the problems of difficult cobalt and calcium separation and incomplete impurity removal in traditional processes. (3) This invention realizes the recycling of leaching residue, crystallization liquid, transformation residue and reaction waste gas, greatly reducing the amount of purchased reagents and the discharge of three wastes. The raw materials used are cheap and readily available. The process is closely connected with the existing copper and cobalt smelting process, and has high industrial adaptability. It has excellent economic, environmental protection and large-scale application prospects. Attached Figure Description

[0056] Figure 1 This is a schematic flowchart of a method for recovering cobalt from cobalt-containing copper raffinate according to a specific embodiment of the present invention. Detailed Implementation

[0057] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0058] This invention provides a method for recovering cobalt from cobalt-containing copper raffinate, such as... Figure 1 As shown, it includes the following steps: (1) Add the first precipitant to the cobalt-containing copper raffinate for pre-removal of impurities, filter to obtain the purified liquid and impurity residue, and pass the generated carbon dioxide gas into the transformation leaching system; (2) Add a second precipitant to the impurity-removed liquid to precipitate cobalt, filter to obtain cobalt-precipitated liquid and cobalt-precipitated slag, the cobalt-precipitated liquid is used as a dispersion solvent for the first and second precipitants, and the remainder is returned to the copper-cobalt ore leaching process. (3) The cobalt precipitate residue is added to the leaching agent, leached, and then filtered to obtain leaching residue and leaching solution; (4) The leachate is oxidized by adding a third precipitant and an oxidant to precipitate cobalt, and then filtered to obtain the precipitated liquid and cobalt-enriched residue. The third precipitant is the leaching residue from step (3). (5) The cobalt enrichment slag is added to the transformation agent for transformation leaching, and filtered to obtain cobalt enrichment liquid and transformation slag. The transformation slag is returned to step (1) to prepare the first precipitant. (6) The cobalt enrichment solution is cooled, crystallized and filtered to obtain crystalline cobalt salt and crystallized liquid. The crystallized liquid is returned to the transformation leaching as a transformation agent. The crystalline cobalt salt is further roasted to obtain cobalt products. (7) The precipitate is cooled, crystallized and filtered to obtain mixed crystallized double salt and crystallized liquid; the crystallized liquid is returned to step (3) as a leaching agent to realize the internal circulation of ammonium salt and water. Steps (5) and (7) have no order.

[0059] The composition of the cobalt-containing copper raffinate used in the following examples and comparative examples is shown in Table 1.

[0060] Table 1 Example 1 This embodiment provides a method for recovering cobalt from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Take 10L of cobalt-containing copper raffinate and heat it to 50℃. Under stirring conditions, slowly add a pre-prepared calcium carbonate slurry with a mass concentration of about 20% (-0.074mm accounts for about 70%) until the pH is 5.5. The dispersion solvent of the slurry is the cobalt precipitation liquid. At the same time, a mixture of compressed air and sulfur dioxide is introduced into the reaction system. The volume concentration of sulfur dioxide in the mixture is 2.8%. The pressure of the mixture is maintained at 0.3MPa. The reaction is stirred continuously for 4 hours. The purified liquid and impurity residue are separated by filtration. The carbon dioxide gas generated during the reaction is collected through a closed pipeline and introduced into the transformation reaction tank. (2) After removing impurities, calcium oxide slurry (mass concentration of about 18%, -0.074mm account for about 65%) was added to the liquid. The dispersion solvent of the slurry was the cobalt precipitation liquid. The pH of the reaction endpoint was controlled at 7.9. After the reaction was completed, the liquid and slag were filtered to obtain the cobalt precipitation liquid and cobalt precipitation residue. The cobalt precipitation rate was 99.89%. (3) Place the cobalt precipitate obtained in step (2) into an acid-resistant reactor equipped with stirring and heating, and add ammonium sulfate solution with a concentration of 200 g / L at a solid-liquid ratio of 1:4 (g / mL); according to the cobalt content in the cobalt precipitate, add ammonia water at an NH3 / Co molar ratio of about 6.0, and stir the reaction at 60℃ for 2 hours; after the reaction is completed, perform hot filtration to obtain leaching residue and leaching solution. The leaching residue is used for later use, and the cobalt leaching rate is 99.86%; (4) Pump the leachate into a pressurized reactor and add the leaching residue obtained after leaching in step (3) at a ratio of 2.0 times the molar amount of calcium sulfate in the residue to cobalt in the solution; after sealing the reactor, introduce oxygen at a ratio of 1.0 times the total molar amount of cobalt in the solution, control the oxygen partial pressure to be maintained at 0.5 MPa, and the flow rate to be 500 mL / min; after sealing the reactor, turn on the stirring and heat to 120°C for 3 hours; after the reaction is completed, depressurize and filter to obtain the precipitated liquid and cobalt-enriched residue; (5) Place the cobalt enrichment slag obtained in step (4) into a transformation reaction tank with a solid-liquid ratio of 1:4 (g / mL), add ammonium carbonate solution with a concentration of 120 g / L, and stir the reaction at 65°C for 2 hours; after the reaction is completed, filter to obtain cobalt enrichment liquid and transformation slag whose main component is calcium carbonate; the transformation slag is returned to step (1) as a recycled material for part of the precipitant; in the cobalt enrichment liquid, cobalt mainly exists in the form of hexaamminecobalt(III) complex ions; (6) The obtained cobalt enrichment solution is pumped into the crystallization tank and slowly cooled to 25°C. It is stirred and crystallized for 3 hours. Then, it is filtered to obtain crystalline cobalt salt (mainly cobalt ammonium sulfate hexahydrate, [Co(NH3)6]2(SO4)3·6H2O) and the crystallized liquid. The crystallized liquid is returned to the transformation process in step (5) for recycling. The crystalline cobalt salt is placed in a muffle furnace and calcined at 800°C for 3 hours to decompose and obtain black cobalt oxide powder with a cobalt content of 72.98% and a cobalt comprehensive recovery rate of 94.85%. (7) The precipitated liquid is sent to a cooling crystallization tank, slowly cooled to 15°C and left to stand for 4 hours; after filtration, mixed crystallized double salt and crystallized liquid are obtained; the crystallized double salt is mainly magnesium ammonium sulfate, zinc ammonium sulfate and copper ammonium sulfate, which can be sold as by-products; the crystallized liquid is returned to step (3) as a leaching agent to realize the internal circulation of ammonium salt and water. There is no order between steps (5) and (7).

[0061] Example 2 This embodiment provides a method for recovering cobalt from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Take 5L of cobalt-containing copper raffinate and heat it to 35°C. Under stirring conditions, slowly add a pre-prepared calcium carbonate slurry with a mass concentration of about 28% (about 60% of -0.074mm) until the pH is 4.5. The dispersion solvent of the slurry is the cobalt precipitation liquid. At the same time, a mixture of compressed air and sulfur dioxide is introduced into the reaction system. The volume concentration of sulfur dioxide in the mixture is controlled at 3.5%, and the pressure of the mixture is maintained at 0.5MPa. The reaction is stirred continuously for 3 hours. The filtration separates the impurity-removed liquid and impurity residue. The carbon dioxide gas generated during the reaction is collected through a closed pipeline and introduced into the transformation reaction tank. (2) After removing impurities, calcium oxide slurry (mass concentration of about 25%, -0.074mm account for about 68%) was added to the liquid. The dispersion solvent of the slurry was the cobalt precipitation liquid. The pH of the reaction endpoint was controlled at 8.0. After the reaction was completed, the liquid and slag were filtered to obtain the cobalt precipitation liquid and cobalt precipitation residue. The cobalt precipitation rate was 99.98%. (3) Place the cobalt precipitate obtained in step (2) into an acid-resistant reactor equipped with stirring and heating, and add ammonium sulfate solution with a concentration of 150 g / L at a solid-liquid ratio of 1:2 (g / mL); according to the cobalt content in the cobalt precipitate, add ammonia water at an NH3 / Co molar ratio of about 5.5, and stir the reaction at 95℃ for 3 hours; after the reaction is completed, perform hot filtration to obtain leaching residue and leaching solution. The leaching residue is used for later use, and the cobalt leaching rate is 99.91%; (4) Pump the leachate into a pressurized reactor and add the leaching residue obtained after leaching in step (3) at a ratio of 2.5 times the molar amount of calcium sulfate in the residue to cobalt in the solution; after sealing the reactor, add ammonium persulfate at a ratio of 1.0 times the total molar amount of cobalt in the solution; after sealing the reactor, turn on the stirring and heat to 100°C for 4 hours; after the reaction is completed, depressurize and filter to obtain the precipitated liquid and cobalt-enriched residue; (5) Place the cobalt enrichment slag obtained in step (4) into a transformation reaction tank with a solid-liquid ratio of 1:6 (g / mL), add an ammonium carbonate solution with a concentration of 160 g / L, and stir the reaction at 70°C for 1.5 h; after the reaction is completed, filter to obtain cobalt enrichment liquid and transformation slag whose main component is calcium carbonate; the transformation slag is returned to step (1) as a recycled material for part of the precipitant; in the cobalt enrichment liquid, cobalt mainly exists in the form of hexaamminecobalt(III) complex ions; (6) The obtained cobalt enrichment solution is pumped into a crystallization tank and slowly cooled to 30°C. It is stirred and crystallized for 2 hours. Then, it is filtered to obtain crystalline cobalt salt (mainly cobalt ammonium sulfate hexahydrate, [Co(NH3)6]2(SO4)3·6H2O) and crystallized liquid. The crystallized liquid is returned to the transformation process in step (5) for recycling. The crystalline cobalt salt is placed in a muffle furnace and calcined at 400°C for 3 hours to decompose and obtain cobalt sulfate with a cobalt content of 37.16% and a cobalt comprehensive recovery rate of 95.79%. (7) The precipitated liquid is sent to a cooling crystallization tank, slowly cooled to 25°C and left to stand for 4 hours; after filtration, mixed crystallized double salt and crystallized liquid are obtained; the crystallized double salt is mainly magnesium ammonium sulfate and zinc ammonium sulfate, which can be sold as by-products; the crystallized liquid is returned to step (3) as a leaching agent to realize the internal circulation of ammonium salt and water. There is no order between steps (5) and (7).

[0062] Example 3 This embodiment provides a method for recovering cobalt from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Take 8L of cobalt-containing copper raffinate and heat it to 40℃. Under stirring conditions, slowly add a pre-prepared calcium carbonate slurry with a mass concentration of about 15% (about 80% of -0.074mm) until the pH is 4.5. The dispersion solvent of the slurry is the cobalt precipitation liquid. At the same time, a mixture of compressed air and sulfur dioxide is introduced into the reaction system. The volume concentration of sulfur dioxide in the mixture is controlled at 2.0%, and the pressure of the mixture is maintained at 0.2MPa. The reaction is stirred continuously for 2 hours. The filtration separates the impurity-removed liquid and impurity residue. The carbon dioxide gas generated during the reaction is collected through a closed pipeline and introduced into the transformation reaction tank. (2) After removing impurities, calcium oxide slurry (mass concentration of about 20%, -0.074mm accounts for about 75%) was added to the liquid. The dispersion solvent of the slurry was the cobalt precipitation liquid. The pH of the reaction endpoint was precisely controlled at 7.0. After the reaction was completed, the liquid and slag were filtered to obtain the cobalt precipitation liquid and cobalt precipitation residue. The cobalt precipitation rate was 98.85%. (3) Place the cobalt precipitate obtained in step (2) into an acid-resistant reactor equipped with stirring and heating, and add ammonium sulfate solution with a concentration of 200 g / L at a solid-liquid ratio of 1:6 (g / mL); according to the cobalt content in the cobalt precipitate, add ammonia water at an NH3 / Co molar ratio of about 5.5, and stir the reaction at 90℃ for 1 h; after the reaction is completed, perform hot filtration to obtain leaching residue and leaching solution. The leaching residue is used for later use, and the cobalt leaching rate is 99.88%; (4) Pump the leachate into a pressurized reactor and add the leaching residue obtained after leaching in step (3) at a ratio of 3.0 times the molar amount of calcium sulfate in the residue to cobalt in the solution; after sealing the reactor, introduce hydrogen peroxide at a ratio of 0.5 times the total molar amount of cobalt in the solution; after sealing the reactor, turn on the stirring and heat to 50°C for 2 hours; after the reaction is completed, depressurize and filter to obtain the precipitated liquid and cobalt-enriched residue; (5) Place the cobalt enrichment slag obtained in step (4) into a transformation reaction tank with a solid-liquid ratio of 1:8 (g / mL), add ammonium bicarbonate solution with a concentration of 100 g / L, and stir the reaction at 50°C for 3 h; after the reaction is completed, filter to obtain cobalt enrichment liquid and transformation slag whose main component is calcium carbonate; the transformation slag is returned to step (1) as a recycled material for part of the precipitant; in the cobalt enrichment liquid, cobalt mainly exists in the form of hexaamminecobalt(III) complex ions; (6) The obtained cobalt enrichment solution is pumped into a crystallization tank, slowly cooled to 50°C, and stirred for 4 hours to crystallize; then filtered to obtain crystalline cobalt salt (mainly cobalt ammonium sulfate hexahydrate, [Co(NH3)6]2(SO4)3·6H2O) and the crystallized liquid; the crystallized liquid is returned to the transformation process in step (5) for recycling; the crystalline cobalt salt is placed in a muffle furnace and calcined at 500°C for 5 hours to decompose and obtain cobalt sulfate with a cobalt content of 37.94% and a cobalt comprehensive recovery rate of 95.83%; (7) The precipitated liquid is sent to a cooling crystallization tank, slowly cooled to 20°C and left to stand for 4 hours; after filtration, mixed crystallized double salt and crystallized liquid are obtained; the crystallized double salt is mainly magnesium ammonium sulfate, zinc ammonium sulfate and copper ammonium sulfate, which can be sold as by-products; the crystallized liquid is returned to step (3) as a leaching agent to realize the internal circulation of ammonium salt and water. There is no order between steps (5) and (7).

[0063] Example 4 This embodiment provides a method for recovering cobalt from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Take 12L of cobalt-containing copper raffinate and heat it to 25°C. Under stirring conditions, slowly add a pre-prepared calcium carbonate slurry with a mass concentration of about 25% (-0.074mm accounts for about 58%) until the pH is 4.9. The dispersion solvent of the slurry is the cobalt precipitation liquid. At the same time, a mixture of compressed air and sulfur dioxide is introduced into the reaction system. The volume concentration of sulfur dioxide in the mixture is controlled at 5.0%, and the pressure of the mixture is maintained at 1.0MPa. The reaction is stirred continuously for 2.5h. The purified liquid and impurity residue are separated by filtration. The carbon dioxide gas generated during the reaction is collected through a closed pipeline and introduced into the transformation reaction tank. (2) After removing impurities, calcium oxide slurry (mass concentration of about 30%, -0.074mm accounts for about 55%) was added to the liquid. The dispersion solvent of the slurry was the cobalt precipitation liquid. The pH of the reaction endpoint was precisely controlled at 7.5. After the reaction was completed, the liquid and slag were filtered to obtain the cobalt precipitation liquid and cobalt precipitation residue. The cobalt precipitation rate was 99.92%. (3) Place the cobalt precipitate obtained in step (2) into an acid-resistant reactor equipped with stirring and heating, and add ammonium sulfate solution with a concentration of 200 g / L at a solid-liquid ratio of 1:8 (g / mL); according to the cobalt content in the cobalt precipitate, add ammonia water at an NH3 / Co molar ratio of about 6.5, and stir the reaction at 80℃ for 4 hours; after the reaction is completed, perform hot filtration to obtain leaching residue and leaching solution. The leaching residue is used for later use, and the cobalt leaching rate is 99.93%; (4) Pump the leachate into a pressurized reactor and add the leaching residue obtained after leaching in step (3) at a ratio of 2.8 times the molar amount of calcium sulfate in the residue to cobalt in the solution; after sealing the reactor, introduce air at a ratio of 1.5 times the total molar amount of cobalt in the solution, control the oxygen partial pressure to be maintained at 1.0 MPa, and the flow rate to 1 L / min; after sealing the reactor, turn on the stirring and heat to 150°C to react for 1.5 h; after the reaction is completed, depressurize and filter to obtain the precipitated liquid and cobalt-enriched residue; (5) Place the cobalt enrichment slag obtained in step (4) into a transformation reaction tank with a solid-liquid ratio of 1:5 (g / mL), add ammonium bicarbonate solution with a concentration of 180 g / L, and stir the reaction at 90°C for 3.5 h; after the reaction is completed, filter to obtain cobalt enrichment liquid and transformation slag whose main component is calcium carbonate; the transformation slag is returned to step (1) as recycled material as part of the precipitant; in the cobalt enrichment liquid, cobalt mainly exists in the form of hexaamminecobalt(III) complex ions; (6) The obtained cobalt enrichment solution is pumped into a crystallization tank and slowly cooled to 45°C. It is then stirred and crystallized for 4.5 hours. Subsequently, it is filtered to obtain crystalline cobalt salt (mainly cobalt ammonium sulfate hexahydrate, [Co(NH3)6]2(SO4)3·6H2O) and the crystallized liquid. The crystallized liquid is returned to the transformation process in step (5) for recycling. The crystalline cobalt salt is placed in a muffle furnace and calcined at 450°C for 4 hours to decompose and obtain cobalt sulfate with a cobalt content of 37.81% and a cobalt comprehensive recovery rate of 95.21%. (7) The precipitated liquid is sent to a cooling crystallization tank, slowly cooled to 10°C and left to stand for 4 hours; after filtration, mixed crystallized double salt and crystallized liquid are obtained; the crystallized double salt is mainly magnesium ammonium sulfate, zinc ammonium sulfate and copper ammonium sulfate, which can be sold as by-products; the crystallized liquid is returned to step (2) as a leaching agent to realize the internal circulation of ammonium salt and water. There is no order between steps (5) and (7).

[0064] Example 5 This embodiment provides a method for recovering cobalt from cobalt-containing copper leaching residue. The difference from Embodiment 1 is that the reaction temperature for cobalt oxidation in step (4) is controlled at 40°C, while the remaining steps are the same as in Embodiment 1. In step (4), the cobalt precipitation rate is reduced to 46.5%, and in step (7), some cobalt precipitates in the form of cobalt ammonium sulfate, resulting in cobalt loss. The overall cobalt recovery rate is 63.41%.

[0065] Example 6 This embodiment provides a method for recovering cobalt from cobalt-containing copper leaching residue. The difference from Embodiment 1 is that: in step (1) during the pre-removal process, a mixture of compressed air and sulfur dioxide is not introduced. The remaining steps are the same as in Embodiment 1, which leads to a decrease in the removal rate of iron and manganese. The residual iron and manganese enter the cobalt precipitate residue and are partially leached into the leaching solution. The cobalt content of the cobalt oxide obtained by roasting is reduced to 70.42%, and the overall cobalt recovery rate is 95.12%.

[0066] Comparative Example 1 This comparative example provides a method for recovering cobalt from cobalt-containing copper raffinate. The difference from Example 1 is that the leaching residue obtained in step (3) is not added during the cobalt oxidation precipitation process in step (4). The remaining steps are the same as in Example 1. In this comparative example, trivalent cobalt exists stably in cobalt ammonium sulfate solution and cannot achieve cobalt oxidation precipitation.

[0067] Comparative Example 2 This comparative example provides a method for recovering cobalt from cobalt-containing copper leaching residue. The difference from Example 1 is that step (1) pre-removal is not performed, while the rest is the same as in Example 1. The leaching residue in step (3) of this comparative example contains a large amount of iron and manganese impurities, which is not conducive to the reuse of the leaching residue.

[0068] Comparative Example 3 This comparative example provides a method for recovering cobalt from cobalt-containing copper leaching residue. The difference from Example 1 is that the cobalt slag from step (2) is directly subjected to transformation leaching, while the rest is the same as in Example 1. Cobalt, copper, and zinc are leached simultaneously and precipitated simultaneously during the subsequent cooling and crystallization process. Due to the excessively high impurity content in the cobalt oxide, the cobalt content of the cobalt oxide obtained by roasting in this comparative example is reduced to 61.53%, and the overall cobalt recovery rate is 88.95%.

[0069] Comparative Example 4 This comparative example provides a method for recovering cobalt from cobalt-containing copper leaching residue. The difference from Example 1 is that after the reaction in step (3), no solid-liquid separation is performed. The entire slurry containing leaching solution and leaching residue is directly pumped into a pressurized reactor for step (4) oxidation precipitation of cobalt. The remaining steps are the same as in Example 1. In this comparative example, a large amount of calcium sulfate directly enters the subsequent transformation leaching process with the leaching residue, which greatly increases the consumption of ammonium carbonate, resulting in incomplete cobalt leaching, increased cobalt loss rate, and a cobalt comprehensive recovery rate of 81.63%.

[0070] (1) As can be seen from Examples 1 to 4, the present invention achieves a cobalt precipitation rate and leaching rate of over 99% through steps such as pre-removal of impurities, cobalt precipitation, ammonia leaching, cobalt oxidation precipitation, transformation leaching and cooling crystallization. This realizes the recycling of materials within the process, and the overall cobalt recovery rate is higher than 94.85%, with a maximum of 95.83%. This enables efficient recovery of cobalt and preparation of high-purity products.

[0071] (2) As can be seen from Examples 5 and 6, the present invention can achieve better technical results by further optimizing the key process conditions. In Example 5, when the cobalt oxidation precipitation temperature is reduced to 40°C in step (4), the cobalt precipitation rate is significantly lower than that in Example 1, and the overall cobalt recovery rate drops sharply to 63.41%. In Example 6, when sulfur dioxide mixed gas is not introduced in step (1), the removal of iron and manganese is incomplete, and the purity of the final cobalt oxide product decreases.

[0072] (3) As can be seen from Example 1 and Comparative Examples 1-4, the present invention can obtain high-purity cobalt products through key operations such as adding leaching residue in step (4) to form a double salt precipitate, pre-removal of impurities in step (1), transformation of cobalt precipitate after ammonia leaching in step (2), and solid-liquid separation in step (3). Comparative Example 1 did not add leaching residue, so it could not effectively form cobalt-calcium-ammonium double salt precipitate, and cobalt oxidation precipitation was difficult to carry out; Comparative Example 2 omitted pre-removal of impurities, and the leaching residue contained a large amount of iron and manganese impurities, which affected the reuse of leaching residue and product purity; Comparative Example 3 directly transformed the cobalt precipitate into leaching, and impurities entered the cobalt enrichment solution at the same time, and the final product purity was much lower than that of Example 1, and the overall cobalt recovery rate was reduced to 88.95%; Comparative Example 4 did not carry out solid-liquid separation in step (3), and a large amount of calcium sulfate entered the subsequent transformation process, which increased the consumption of ammonium carbonate and easily caused incomplete cobalt leaching and increased cobalt loss, with an overall recovery rate of only 81.63%.

[0073] In summary, this invention achieves efficient cobalt recovery and the preparation of high-purity products through a process route of pre-removal, cobalt precipitation, ammoniacal leaching, oxidative double salt precipitation, ammonium carbonate conversion, and cooling crystallization, combined with an internal recycling system that returns leaching residue to cobalt precipitation, conversion residue to pre-removal, and crystallization liquid for reuse. It requires no organic extractant, has low reagent consumption, is environmentally friendly, and has good prospects for industrial application.

[0074] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A process for the recovery of cobalt from a cobalt-containing copper raffinate, characterized in that, The method comprises the following steps: (1) adding a first precipitant to the cobalt-containing copper raffinate to remove impurities, and then performing solid-liquid separation to obtain a liquid after impurity removal and an impurity residue; (2) adding a second precipitant to the liquid after impurity removal to precipitate cobalt, and then performing solid-liquid separation to obtain a liquid after cobalt precipitation and a cobalt precipitation residue; (3) adding a leaching agent to the cobalt precipitation residue to perform leaching, and then performing solid-liquid separation to obtain a leaching residue and a leaching liquid; (4) adding a third precipitant and an oxidizing agent to the leaching liquid to perform oxidative cobalt precipitation, and then performing solid-liquid separation to obtain a liquid after precipitation and a cobalt enrichment residue; (5) adding a transformation agent to the cobalt enrichment residue to perform transformation leaching, and then performing solid-liquid separation to obtain a cobalt enrichment liquid and a transformation residue; (6) performing solid-liquid separation on the cobalt enrichment liquid after cooling and crystallization to obtain a crystallized cobalt salt and a liquid after crystallization.

2. The method of claim 1, wherein, In step (1), the cobalt-containing copper raffinate contains any one or a combination of at least two of calcium ions, magnesium ions, iron ions, aluminum ions, copper ions, zinc ions, manganese ions and silicon ions in addition to cobalt ions; Preferably, the cobalt-containing copper raffinate is obtained after acid leaching and copper extraction from a copper-cobalt ore. Preferably, the first precipitant comprises a combination of calcium carbonate and sulfur dioxide. Preferably, the calcium carbonate is pre-adjusted to a calcium carbonate slurry with a mass concentration of 10-30%. Preferably, the sulfur dioxide is mixed with compressed air and then introduced into the reaction system, and the volume concentration of sulfur dioxide in the mixed gas is 1-5%, and the pressure of the mixed gas is 0.1-1 MPa. Preferably, the proportion of particles with a particle size of-0.074 mm in the calcium carbonate is 50-80%. Preferably, the end point pH of the pre-impurity removal is 4.5-5.

5. Preferably, the gas generated in the pre-impurity removal process is introduced into step (5) to assist the transformation leaching.

3. The method according to claim 1 or 2, characterized in that, In step (2), the second precipitant comprises calcium oxide. Preferably, the calcium oxide is pre-adjusted to a calcium oxide slurry with a mass concentration of 10-30%. Preferably, the end point pH of the cobalt precipitation is 7-8. Preferably, the proportion of particles with a particle size of-0.074 mm in the calcium oxide is 50-80%. Preferably, the liquid after cobalt precipitation is returned to the copper-cobalt ore leaching process for reuse and / or used as a dispersion solvent for the calcium carbonate slurry and the calcium oxide slurry.

4. The method according to any one of claims 1 to 3, characterized in that, In step (3), the leaching agent comprises a combination of an ammonium sulfate solution and ammonia water. Preferably, the solid-liquid ratio of the cobalt precipitation residue to the ammonium sulfate solution is 1:(1-10) g / mL. Preferably, the concentration of the ammonium sulfate solution is 150-250 g / L. Preferably, the amount of ammonia water added is 5.0-6.5 times the molar amount of cobalt in the cobalt precipitation residue. Preferably, the leaching temperature is 25-100°C. Preferably, the leaching process is performed with stirring, and the stirring time is 0.5-4 h.

5. The method according to any one of claims 1 to 4, characterized in that, In step (4), the oxidizing agent for oxidative cobalt precipitation comprises any one or a combination of at least two of air, oxygen, hydrogen peroxide and ammonium persulfate. Preferably, the third precipitant in step (4) comprises calcium sulfate. Preferably, the leaching residue in step (3) is used as the third precipitant in step (4), and the amount of the leaching residue added is 2.0-3.0 times the molar amount of cobalt ions in the leaching liquid. Preferably, the amount of oxidant added is 0.5 to 1.5 times the molar amount of cobalt ions, based on the effective oxidizing component; Preferably, the reaction temperature for cobalt oxide precipitation is 50~150℃; Preferably, the cobalt oxide precipitation process is carried out with stirring for 0.5 to 4 hours; Preferably, when the oxidant is air or oxygen, the partial pressure of oxygen is 0.1~1.0 MPa and the gas flow rate is 0.1~1 L / min.

6. The method according to any one of claims 1 to 5, characterized in that, After cooling and crystallizing the precipitated liquid in step (4), solid-liquid separation is performed to obtain crystalline double salt and crystalline liquid; Preferably, the crystallized liquid after precipitation is returned to step (3) as a leaching agent; Preferably, the temperature at which the precipitated liquid is cooled and crystallized is 5~25℃; Preferably, the crystalline double salt comprises any one or a combination of at least two of ammonium copper sulfate, ammonium zinc sulfate, ammonium magnesium sulfate, and ammonium manganese sulfate.

7. The method according to any one of claims 1 to 6, characterized in that, The transforming agent in step (5) includes ammonium carbonate solution and / or ammonium bicarbonate solution; Preferably, the concentration of the transforming agent is 50~200g / L; Preferably, the solid-liquid ratio of the transformation leaching is 1:(1~10)g / mL; Preferably, the transformation leaching temperature is 25~100℃ and the time is 0.5~4h.

8. The method according to any one of claims 1 to 7, characterized in that, The transformation residue described in step (5) is returned to step (1) for the preparation of the first precipitant.

9. The method according to any one of claims 1 to 8, characterized in that, The cooling crystallization temperature in step (6) is 25~50℃ and the time is 0.5~5h.

10. The method according to any one of claims 1 to 9, characterized in that, The cobalt product is obtained by calcining the crystalline cobalt salt described in step (6); Preferably, the crystalline cobalt salt comprises ammonium cobalt sulfate; Preferably, the cobalt product is cobalt sulfate or cobalt oxide; Preferably, the crystallized liquid from step (6) is returned to step (5) as a transforming agent.

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