A production method for purifying and removing impurities of high-arsenic cobalt ore to prepare battery-grade cobalt sulfate

Abstract

The application discloses a production method for purifying and removing impurities of high-arsenic cobalt ore to prepare battery-grade cobalt sulfate, which comprises the following steps: (1) grinding ore; (2) two-stage countercurrent leaching; (3) secondary purification and removal of iron and arsenic; (4) cobalt precipitation and magnesium removal; and (5) return dissolution of sulfuric acid for the cobalt precipitation material. The cobalt sulfate solution obtained by the method has high cobalt concentration and yield, low impurity ion concentration, good iron and arsenic removal effect and good cobalt and magnesium separation effect, the flux of an extraction section is reduced, the extraction stages are reduced, the battery-grade cobalt sulfate product is prepared by further extraction and impurity removal, the process and reagent are simple, the production process is short, the production cost is low, the method is green and environment-friendly, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to a method for producing cobalt sulfate from high-arsenic cobalt ore, specifically a method for producing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore. Background Technology

[0002] Cobalt, as a rare metal, is a crucial raw material for battery cathode materials, used in the manufacture of lithium nickel cobalt manganese (LCM) and lithium nickel cobalt aluminum (LCA) batteries, and widely applied in electric vehicles, energy storage systems, and electronic devices such as mobile phones and computers. The rapid development of the new energy industry has led to a surge in demand for cobalt, with global cobalt consumption reaching 175,000 tons in 2023. my country is a major consumer of cobalt resources but also a country severely lacking in them. It has few high-grade cobalt ores, with most being low-grade, complex, and difficult-to-process ores. China heavily relies on imports for cobalt, accounting for approximately 65% ​​of global consumption, ranking first in the world, with an import dependency rate as high as 97%. my country faces a severe supply and demand situation for cobalt resources, while global cobalt reserves are also scarce. In recent years, cobalt resources have received increasing attention. With the dramatic increase in global demand for cobalt, countries in Europe and America have elevated cobalt resources to a national strategic mineral resource, making the efficient extraction of cobalt from low-grade cobalt ores an urgent priority.

[0003] The smelting methods for cobalt vary depending on the ore composition. Furthermore, since cobalt mainly exists as a by-product in other metal ores, its extraction, except for extraction from arsenic-cobalt ores and cobaltite, is based on the main metal production process. Cobalt is enriched in intermediate products and then recovered, making the process flow often quite complex. The methods for extracting cobalt from cobalt-containing raw materials are essentially pyrometallurgical and hydrometallurgical processes: pyrometallurgical treatment alters the phase composition of cobalt in the material or enriches cobalt in intermediate products, preparing for subsequent hydrometallurgical processing; hydrometallurgical processing aims to remove impurities and obtain high-purity metallic cobalt, or directly produce various cobalt-containing compounds required for industrial applications. Therefore, the methods for extracting cobalt from cobalt-containing raw materials can be summarized into three types: a fully pyrometallurgical process, a fully hydrometallurgical process, and a combined pyrometallurgical and hydrometallurgical process. The all-pyrometallurgical process was widely used before the 1940s, but now only the Panda Cobalt Plant uses electric furnaces to smelt copper-cobalt alloys. The all-hydrometallurgical process mainly includes pressurized acid leaching, ammonia leaching, sulfuric acid and nitric acid leaching, and chlorination leaching of cobalt-containing materials. The combined pyrometallurgical-hydrometallurgical process first uses sulfation roasting (copper-cobalt concentrate, pyrite), reduction roasting (latite), and arsenic removal roasting (arsenic-cobalt concentrate), followed by acid or ammonia leaching. Alternatively, during the pyrometallurgical smelting of copper, nickel, zinc, etc., cobalt is enriched as an intermediate product and then treated hydrometallurgically. The complexity of cobalt-containing raw materials means that there are no traditional processes or standards to follow in cobalt metallurgy, but all processes ultimately require hydrometallurgical treatment, which is a characteristic of cobalt metallurgy.

[0004] Arsenic-cobalt ore is mainly produced in Morocco. High-grade concentrates can be easily obtained through flotation. Arsenic-cobalt ore typically contains 5-12% cobalt and 15-60% arsenic. After smelting, oxidative roasting, roasting leaching, and purification of the leachate, the arsenic-cobalt concentrate can be used to produce electrolytic cobalt, cobalt powder, cobalt salts, and cobalt oxide. However, high-arsenic-cobalt ore has a more complex composition, generally containing major elements such as Co, Mg, Fe, As, Ni, Zn, Mn, Ca, Cu, and Al. Therefore, to extract cobalt and prepare cobalt sulfate, cobalt must be separated from the other elements.

[0005] Currently, the P204-C272 combined extraction process is commonly used in production to separate cobalt from other impurities such as nickel and magnesium to produce cobalt sulfate, thereby shortening the process and reducing production costs. However, C272 extraction suffers from difficulties in separating cobalt and magnesium, often resulting in high magnesium and low cobalt concentrations in the cobalt solution, significantly reducing the cobalt extraction efficiency. The main technical drawback of the current process is that when removing calcium and magnesium using chemical precipitation, sodium fluoride is required. The resulting calcium-magnesium fluoride slag is an unmanageable solid waste, and the fluoride ions place high demands on equipment during subsequent evaporation of the finished product. Therefore, there is an urgent need to develop a new process route to shorten the production process, reduce production costs, and improve the yield and purity of cobalt, thus finding a new avenue for the comprehensive utilization of similar high-arsenic cobalt ores.

[0006] CN115353152A discloses a battery-grade cobalt sulfate, its production process, and a battery, using crude cobalt hydroxide as raw material; CN115121006A discloses a method and process for removing nickel and cadmium impurities from a cobalt sulfate solution. Although this method can separate nickel and enrich cobalt through resin adsorption, avoiding the purification and impurity removal process, the resin adsorption method is costly, and the regeneration and treatment of the resin require additional processes and costs; in addition, the resin adsorption method may become less efficient when dealing with high concentrations of impurities.

[0007] CN108517403A discloses a method for producing battery-grade cobalt sulfate from metallic cobalt. Although this method improves the purity of cobalt sulfate through multiple impurity removal steps (such as oxidation precipitation, fluorination, and P204 extraction), the entire process is lengthy, involving multiple complex chemical reactions and separation steps, which increases production costs and operational difficulty. In addition, the precipitates produced by the fluorination method (such as calcium fluoride and magnesium fluoride) are fine particles that easily form colloids, making them difficult to settle and filter, increasing the difficulty of treatment. At the same time, the fluoride wastewater and waste gas generated must be properly treated to reduce the impact on the environment.

[0008] CN111593205A discloses a method for recovering cobalt from cobalt-containing sulfuric acid slag, which uses the cobalt sulfuric acid slag as raw material to produce high-purity cobalt hydroxide. However, this method is not suitable for processing high-arsenic cobalt ore and cannot remove arsenic and magnesium from arsenic cobalt ore.

[0009] CN113278817A describes a method for removing impurities from cobalt ore and crude cobalt salt sulfuric acid leaching solution, and its application. This method uses cobalt ore and crude cobalt salt as raw materials and utilizes vanadium ferroammonium for iron removal. However, this method cannot handle high-arsenic cobalt ores, especially as arsenic and magnesium cannot be removed.

[0010] CN101497943A describes a method for recovering cobalt from cobalt waste residue through sodium persulfate oxidation. This method uses cobalt waste residue as raw material and employs a first-stage leaching process, including displacement separation, filtration and drying, followed by a second-stage leaching process, filtration, iron removal, sodium persulfate oxidation to precipitate cobalt, filtration, and the yield of cobalt concentrate. However, this method is only suitable for enriching cobalt in the waste residue by more than 40 times and is not applicable to treating high-arsenic cobalt ores, especially since arsenic and magnesium in these ores cannot be effectively removed.

[0011] In summary, there is an urgent need to find a production method for purifying and removing impurities from high-arsenic cobalt ore to prepare battery-grade cobalt sulfate, which results in a high cobalt concentration and yield, low impurity ion concentration, good separation of iron, arsenic, cobalt, and magnesium, while reducing the throughput and extraction stages of the extraction process. This method would facilitate further extraction and impurity removal to prepare battery-grade cobalt sulfate products. It would also require simple processes and reagents, a short production flow, low production costs, and be environmentally friendly, making it suitable for industrial-scale production. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for producing battery-grade cobalt sulfate with high cobalt concentration and yield, low impurity ion concentration, good separation effect of iron, arsenic and cobalt and magnesium, and reduced throughput and extraction stages in the extraction section, which is conducive to further extraction and impurity removal to prepare battery-grade cobalt sulfate products. The process and reagents are simple, the production process is short, the production cost is low, and it is green and environmentally friendly, making it suitable for industrial production of high-arsenic cobalt ore purification and impurity removal to prepare battery-grade cobalt sulfate.

[0013] The technical solution adopted by the present invention to solve its technical problem is as follows: A production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high arsenic cobalt ore, comprising the following steps: (1) grinding; (2) two-stage countercurrent leaching; (3) secondary purification to remove iron and arsenic; (4) cobalt precipitation to remove magnesium; (5) sulfuric acid back dissolution of cobalt precipitation material.

[0014] Preferably, the method for producing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore specifically includes the following steps: (1) Grinding: Grind the high-arsenic cobalt ore roasted sand and sieve it to obtain high-arsenic cobalt ore powder; (2) Second stage countercurrent leaching: First-stage low-acid leaching: Add water to the reaction tank, start stirring, then add the high-arsenic cobalt ore powder obtained in step (1), stir evenly, add concentrated sulfuric acid and / or the high-acid leaching solution obtained from the second-stage high-acid leaching, stir evenly, carry out the heating and stirring leaching reaction, filter, and obtain low-acid leaching residue and low-acid leaching solution; or add the high-acid leaching solution obtained from the second-stage high-acid leaching to the reaction tank, start stirring, then add the high-arsenic cobalt ore powder obtained in step (1), stir evenly, carry out the heating and stirring leaching reaction, filter, and obtain low-acid leaching residue and low-acid leaching solution; Two-stage high acid leaching: Add water to the reaction tank, start stirring, then add the low acid leaching residue obtained from the first stage of low acid leaching, stir evenly, add concentrated sulfuric acid, heat and stir to react, then add oxidant, carry out the heating and stirring leaching reaction, filter, and obtain high acid leachate. (3) Secondary purification to remove iron and arsenic: Oxidation and neutralization: Add the low acid leachate obtained from the first low acid leaching in step (2) to the reaction tank, turn on the stirring, add ferrous sulfate, heat and stir, add oxidant, heat and react, keep warm and slowly adjust the pH value to carry out the oxidation and neutralization reaction, and continue to keep warm after the pH value reaches the reaction endpoint, filter, and obtain the first iron and arsenic removal solution. Hydrolysis and precipitation: After stirring and heating the primary iron and arsenic removal solution obtained from oxidation and neutralization, the solution is kept at a certain temperature and the pH value is slowly adjusted to carry out the hydrolysis and precipitation reaction. After the pH value reaches the reaction endpoint, the reaction is kept at a certain temperature and then filtered to obtain the secondary iron and arsenic removal solution. (4) Cobalt precipitation and magnesium removal: After stirring and heating the secondary iron and arsenic removal liquid obtained in step (3), keep it warm and slowly adjust the pH value to carry out cobalt precipitation and magnesium removal. After the pH value reaches the reaction endpoint, continue to keep it warm and filter to obtain cobalt precipitation material. (5) Sulfuric acid back dissolution of cobalt precipitate: Add the cobalt precipitate obtained in step (4) to water, stir evenly, add sulfuric acid until acidic, heat, and keep warm to react, and obtain battery grade cobalt sulfate solution.

[0015] The inventive concept of this invention is as follows: After grinding high-arsenic cobalt ore roasted sand, a two-stage countercurrent leaching process (low-acid leaching + high-acid leaching) is adopted. First, a low-acid leaching stage is performed. The leaching residue from the first low-acid leaching stage is then subjected to a second high-acid leaching stage. The leachate from the second high-acid leaching stage is used as the base solution for the first low-acid leaching stage. The purpose of the two-stage leaching is twofold: first, to increase leaching efficiency; second, during the first low-acid leaching stage, most of the silicon in the high-arsenic cobalt ore roasted sand will enter the low-acid leaching solution in ionic form, thereby reducing the silicon content in the high-arsenic cobalt ore roasted sand. The leaching process is carried out in the form of silica sol under acidic conditions to avoid filtration difficulties. The leachate from the first stage of low-acid leaching enters the purification process for iron and arsenic removal. Based on the composition of the low-acid leachate, oxidation neutralization and hydrolysis precipitation are adopted to remove iron, arsenic, copper, aluminum and other related low-pH hydrolytic impurities from the leachate. The second iron and arsenic removal solution after the two stages of iron and arsenic removal is then subjected to cobalt precipitation and magnesium removal. After sulfuric acid back-dissolution and filtration of the cobalt precipitation material, the resulting cobalt sulfate solution creates favorable conditions for subsequent extraction to produce battery-grade cobalt sulfate products.

[0016] Preferably, in step (1), the main components and mass fractions of the high-arsenic cobalt ore roasted sand are as follows: Co 6-10%, Mg 3-7%, Fe 6-10%, As 15-25%, Si 12-18%, Ni 0.5-1.5%, Zn 0.05-0.20%, Mn 0.10-0.25%, Ca 4-7%, Cu 0.2-0.4%, and Al 2-4%. The high-arsenic cobalt ore roasted sand used in this invention mainly comes from a certain smelter.

[0017] Preferably, in step (1), the sieving is performed to a 120-mesh sieve. This particle size ensures that cobalt and other metals in the ore are adequately exposed in the leachate.

[0018] The method of this invention returns the second stage of high-acid leachate to a first stage of low-acid leachate, which is called countercurrent leaching.

[0019] Preferably, in step (2), during the first stage of low-acid leaching, the solid-liquid ratio (kg / L) of the high-arsenic cobalt ore powder to the liquid phase in the leaching system is 1:2 to 4 (more preferably 1:2.5 to 3.5). If the liquid phase is too small, the fluidity of the slurry will decrease, which is not conducive to the transport of the slurry; if the liquid phase is too large, it will reduce the concentration of cobalt in the solution and increase the amount of wastewater to be treated.

[0020] Preferably, in step (2), during the first-stage low-acid leaching, the hydrogen ion concentration in the liquid phase of the leaching system is 0.2–1.7 mol / L (more preferably 0.4–1.5 mol / L, and even more preferably 0.8–1.4 mol / L). If the hydrogen ion concentration in the first-stage low-acid leaching is too high (i.e., the pH value is too low), most of the silicon in the high-arsenic cobalt ore roasted sand will form silica gel, making the slurry difficult to filter; if the hydrogen ion concentration in the first-stage low-acid leaching is too low (i.e., the pH value is too high), it will be detrimental to the leaching of cobalt. If the hydrogen ion concentration of the high-acid leaching solution is within the above range, it can be directly used for the first-stage low-acid leaching. If the amount or concentration of the high-acid leaching solution is insufficient, it can be adjusted and supplemented by adding concentrated sulfuric acid and water.

[0021] Preferably, in step (2), the high acid leachate is not added during the first run of the low acid leaching process, but is added in a cycle after the subsequent stable operation. The above is the default operation during stable operation.

[0022] Preferably, in step (2), after adding the high-arsenic cobalt ore powder obtained in step (1) and the high-acid leachate obtained from the second-stage high-acid leaching, the mixture is stirred for 5 to 30 minutes until homogeneous. The purpose of stirring is to prevent the slurry from settling to the bottom of the tank, which would be detrimental to leaching.

[0023] Preferably, in step (2), the temperature of the heating and stirring leaching reaction in the first stage of low acid leaching is 80-90°C, and the time is 3-4 hours. The purpose of the first stage of low acid leaching is to partially dissolve the cobalt into the solution.

[0024] Preferably, in step (2), after adding the low-acid leaching residue obtained from the first-stage low-acid leaching in the second-stage high-acid leaching, the mixture is stirred for 5-30 minutes until homogeneous. The purpose of stirring is to prevent the slurry from settling to the bottom of the tank, which would be detrimental to leaching.

[0025] Preferably, in step (2), during the two-stage high-acid leaching, the solid-liquid ratio (kg / L) of the low-acid leaching residue to the liquid phase in the leaching system is 1:2 to 4 (more preferably 1:2.5 to 3.5). Under a certain acid-to-ore ratio, if the liquid phase is too small, the fluidity of the slurry will decrease, which is not conducive to the transport of the slurry; if the liquid phase is too large, it will reduce the concentration of cobalt in the solution and increase the amount of wastewater to be treated.

[0026] Preferably, in step (2), during the two-stage high-acid leaching, the hydrogen ion concentration in the liquid phase of the leaching system is 2.6–3.5 mol / L (more preferably 3.0–3.5 mol / L). If the hydrogen ion concentration is too low, it will affect the leaching rate of arsenic-cobalt ore; if the hydrogen ion concentration is too high, it will not increase the leaching rate of arsenic-cobalt ore. If the hydrogen ion concentration is too high, it will lead to an excessively high hydrogen ion concentration in the high-acid leaching solution. When the high-acid leaching solution is returned to the first-stage low-acid leaching, it may lead to an excessively high hydrogen ion concentration in the first-stage low-acid leaching, which is not conducive to the filtration of the first-stage low-acid leaching slurry.

[0027] Preferably, in step (2), the temperature of the heating and stirring reaction in the two-stage high acid leaching is 80-90°C and the time is 10-80 min (more preferably 10-60 min).

[0028] Preferably, in step (2), the amount of oxidant used in the two-stage high acid leaching is equivalent to 5-15% (more preferably 6-12%) of the mass of the low acid leaching residue.

[0029] Preferably, in step (2), the oxidant in the two-stage high-acid leaching includes one or more of sodium chlorate, hydrogen peroxide, ozone, or oxygen. More preferably, the oxidant is sodium chlorate, which is a strong oxidant. Adding sodium chlorate can enhance leaching and increase the leaching rate of cobalt.

[0030] Preferably, in step (2), the temperature of the heating and stirring leaching reaction in the two-stage high-acid leaching is 80-90°C, and the time is 2-4 hours. The purpose of the two-stage high-acid leaching is to further improve the leaching rate of cobalt and ensure that the total leaching rate of cobalt is ≥95%.

[0031] Preferably, in step (3), during the oxidation and neutralization, the amount of ferrous sulfate used is such that the molar ratio of iron to arsenic in the low-acid leachate is 1.2–1.4:1. Under certain temperature and pH conditions, iron and arsenic can form a non-toxic ferric arsenate precipitate (Fe). 3+ (aq) + AsO4 3- (aq) + 2H2O → FeAsO4·2H2O(s)↓), an excess of iron ions is necessary to ensure that arsenic can be completely precipitated, while an excessive addition of ferrous ions will result in waste and introduce new impurities.

[0032] Preferably, in step (3), during the oxidation and neutralization, the heating and stirring temperature is 70–90°C, and the time is 10–40 min. The heating and stirring can make the materials mix evenly and accelerate the oxidation reaction.

[0033] Preferably, in step (3), during the oxidation and neutralization, the amount of oxidant used is such that the Fe in the low-acid leachate is reduced. 2+ Oxidized to Fe3+ The dosage is 1.1 to 1.3 times the theoretical amount. The purpose of adding the oxidant is to oxidize ferrous iron to ferric iron, which then forms ferric arsenate precipitate with arsenic, thereby achieving the purpose of arsenic removal. The reaction equation is shown below: Fe 2+ (aq) + 1 / 4O2 + H + → Fe 3+ + 1 / 2H2O; or 6Fe 2+ (aq) + ClO3 - + 6H + → 6Fe 3+ + Cl - +3H2O; Fe 3+ (aq) + AsO4 3- (aq) + 2H2O → FeAsO4·2H2O(s)↓; This method of simultaneous oxidation and precipitation differs in mechanism from directly adding ferric iron; the reaction equation is shown below: Fe 3+ (aq) +3OH - (aq) → Fe(OH)3 (s)↓; The former is more conducive to the formation of ferric arsenate precipitate, while the latter is more likely to form ferric hydroxide precipitate or a mixed precipitate of ferric hydroxide and ferric arsenate, which is not conducive to the complete precipitation of arsenic.

[0034] Preferably, in step (3), the oxidant in the oxidation and neutralization includes one or more of sodium chlorate, hydrogen peroxide, ozone or oxygen.

[0035] Preferably, in step (3), the temperature of the heating reaction during the oxidation and neutralization is 70-90°C (more preferably 80-90°C) and the time is 10-40 min (more preferably 20-30 min).

[0036] Preferably, in step (3), the pH value is adjusted by using an alkaline solution with a mass concentration of 5-15% during the oxidation and neutralization process.

[0037] Preferably, in step (3), during the oxidation and neutralization, the pH value at the reaction endpoint is 3.5–4.0. By adjusting the pH value, arsenic is removed by precipitation in the form of ferric arsenate.

[0038] Preferably, in step (3), the holding time during the oxidation and neutralization process is 30–60 min (more preferably 30–45 min). At the pH value at the reaction endpoint, this holding time is more conducive to ensuring complete precipitation of ferric arsenate.

[0039] Preferably, in step (3), during the oxidation and neutralization process, the total reaction time from the addition of ferrous sulfate to the end of the heat preservation reaction is controlled within the range of 4 to 5 hours. During the oxidation and neutralization process, Fe... 2+ Oxidized to Fe 3+ Simultaneously, ferric and arsenic ions precipitate as ferric arsenate (onionite structure). By controlling the total reaction time, the pH value is slowly adjusted to avoid excessively high pH values ​​leading to Fe... 2+ and Fe 3+ It can form hydroxide or carbonate precipitates.

[0040] Preferably, in step (3), the stirring and heating during the hydrolysis precipitation is carried out at 70-90°C. During the hydrolysis precipitation process, in addition to further precipitating ferric arsenate, it is also necessary to hydrolyze and precipitate other metallic impurities. Since the formation process of ferric arsenate and other impurities hydrolysis precipitation is an endothermic reaction, if the temperature is too low, the reaction time will be too long, and if the temperature is too high, the energy consumption will be too high.

[0041] Preferably, in step (3), the pH value is adjusted by using an alkaline solution with a mass concentration of 5-15% during the hydrolysis precipitation.

[0042] Preferably, in step (3), the pH value at the endpoint of the hydrolysis precipitation is 4.5 to 5.0. If the pH value is too low, it will not be conducive to the formation of ferric arsenate, and at the same time, impurities such as iron, copper, and aluminum will not precipitate or will not precipitate completely; if the pH value is too high, iron ions will precipitate in the form of hydroxides and will not precipitate in the form of ferric arsenate, making it difficult to achieve the purpose of arsenic removal, and aluminum ions will also not precipitate.

[0043] Preferably, in step (3), the time for the heat preservation reaction during the hydrolysis precipitation is 20-60 min (more preferably 30-50 min). At the pH value at the end of the reaction, the heat preservation reaction time is more conducive to ensuring the complete precipitation of ferric arsenate and excess iron, copper, aluminum and other related low pH hydrolysis impurities.

[0044] Preferably, in step (3), the total reaction time from adjusting the pH value to the end of the heat preservation reaction is controlled within the range of 3 to 5 hours (more preferably 3.5 to 4.5 hours). If the reaction time is too long, the production efficiency will be reduced; if the reaction time is too short, the alkali solution will be added too quickly, causing local supersaturation of the solution, which is not conducive to the formation of stable ferric arsenate precipitate. Throughout the hydrolysis and precipitation process, slowly adjusting the pH value can avoid the Fe2+ precipitate from being too high due to excessively high pH value. 2+ and Fe 3+ It forms hydroxide or carbonate precipitates, rather than ferric arsenate precipitates.

[0045] After purification and removal of iron and arsenic by adjusting the pH value twice in step (3), the iron and arsenic content in the filtrate is already very low, which is sufficient to meet the subsequent process requirements, so as to further control the impurity content and create favorable conditions for the product to reach electronic grade.

[0046] Preferably, in step (4), the stirring and heating is carried out at 70-90°C. The cobalt carbonate precipitation process is an endothermic process. If the temperature is too low, the reaction time will be too long; if the temperature is too high, the energy consumption will be too high.

[0047] Preferably, in step (4), the pH value is adjusted with an alkaline solution with a mass concentration of 5-10%.

[0048] Preferably, in step (4), the pH value at the reaction endpoint is 7.0 to 7.5. The purpose of adjusting the pH value is to precipitate cobalt. If the pH value is too low, it will be difficult to achieve the effect of cobalt precipitation. If the pH value is too high, it will cause magnesium precipitation, thus making it difficult to achieve the effect of cobalt-magnesium separation.

[0049] Preferably, in step (4), the heat preservation reaction time is 10–60 min (more preferably 10–40 min). This reaction time helps ensure that the cobalt precipitation and magnesium removal process can effectively stabilize the cobalt yield ≥99.5% and the magnesium removal rate ≥90%.

[0050] Preferably, in step (4), the total reaction time from the start of pH adjustment to the end of the heat preservation reaction is controlled within the range of 3.5 to 4.5 hours. Cobalt precipitation and magnesium removal are mainly based on the different solubility equilibrium constants of cobalt and magnesium carbonate, that is, the difference in precipitation hydrolysis at different pH values. By controlling the total reaction time, the pH value of the solution is slowly adjusted, reducing pH fluctuations, removing some magnesium and calcium, and enriching cobalt, thereby achieving the purpose of cobalt precipitation and partial magnesium removal.

[0051] Preferably, in steps (3) and (4), the alkaline solution includes an aqueous solution of sodium carbonate, sodium hydroxide, or calcium carbonate.

[0052] Preferably, in step (5), the solid-liquid ratio of the cobalt precipitate to water is 1:1.5 to 2.5 (more preferably 1:1.8 to 2.2). If the amount of water is too small, it will be difficult to achieve the purpose of dissolution; if the amount of water is too large, the concentration of cobalt in the solution will be too low, increasing the throughput of the extraction section.

[0053] Preferably, in step (5), the acidic pH value is 4.0 to 5.5. The purpose of adding sulfuric acid is to completely dissolve the cobalt while minimizing the dissolution of impurities such as magnesium carbonate. If the pH value is too low, it will cause the dissolution of impurities such as magnesium carbonate, resulting in an excessively high concentration of magnesium in the solution.

[0054] Preferably, in step (5), the mass fraction of the sulfuric acid is 10-98%.

[0055] Preferably, in step (5), the heating is carried out to 70-90°C. The heat preservation reaction process is the dissolution process of cobalt carbonate. The reaction between cobalt carbonate and sulfuric acid is an endothermic reaction. If the temperature is too low, the reaction time will be too long; if the temperature is too high, the energy consumption will be too high.

[0056] Preferably, in step (5), the heat preservation reaction time is 20 to 50 minutes.

[0057] Preferably, in steps (2) to (5), the stirring speed is 30 to 60 r / min.

[0058] Preferably, the concentrated sulfuric acid used in this invention has a mass fraction of 95-98%.

[0059] The concentrations of each element in the cobalt sulfate solution obtained by the method of this invention are determined by potentiometric titration of Co and by ICP determination of impurity ions such as Cu, Mn, and Ca.

[0060] The beneficial effects of the method of the present invention are as follows: (1) The method of the present invention overcomes the shortcomings of the existing technology for removing impurities in the production of cobalt sulfate solution from high-arsenic cobalt ore. In the obtained cobalt sulfate solution, the concentration of Co can reach 17-25 g / L, the cobalt yield is as high as 99.5%, and the concentration of each component can be as low as: Mg 0.6-0.69 g / L, Fe <1 mg / L, As <1 mg / L, Ni 1.2-3 g / L, Zn 0.05-0.30 g / L, Mn 0.25-0.50 g / L, Ca 0.1-0.5 g / L, Cu 6-25 mg / L, Al <6 mg / L. The content of impurities such as magnesium and calcium is greatly reduced, the removal of iron and arsenic and the separation of cobalt and magnesium are good, the cobalt-magnesium ratio increases from 2.7:1 to 25:1, and at the same time the throughput of the extraction section is reduced and the number of extraction stages is reduced, which provides favorable conditions for further extraction and impurity removal to prepare battery-grade cobalt sulfate products. (2) The method and reagents of the present invention are simple, the production process is short and the production cost is low. It mainly removes impurities and purifies high-arsenic cobalt ore by acid leaching and strict adjustment of pH value, and obtains cobalt sulfate solution with almost all iron and arsenic removed and magnesium content greatly reduced. This provides favorable conditions for further extraction to produce high-purity battery-grade cobalt sulfate crystals. It is green and environmentally friendly and suitable for industrial production. Attached Figure Description

[0061] Figure 1 This is a comparison of the Raman spectra of the high-acid leaching residue obtained in step (2) of Example 3 and Comparative Example 3 of the present invention with that of the high-arsenic cobalt ore roasted sand. Detailed Implementation

[0062] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0063] The high-arsenic cobalt ore roasted sand used in this invention is sourced from a smelter, and its main components and mass fractions are as follows: Co 8.98%, Mg 4.08%, Fe 7.91%, As 16.13%, Si 14.01%, Ni 0.75%, Zn 0.078%, Mn 0.16%, Ca 4.99%, Cu 0.28%, Al 2.76%; the concentrated sulfuric acid used in the embodiments of this invention has a mass fraction of 98%; unless otherwise specified, the raw materials or chemical reagents used in the embodiments of this invention are obtained through conventional commercial channels. The concentrations of each element in the cobalt sulfate solution obtained in this embodiment of the invention were determined by potentiometric titration of Co and by ICP determination of impurity ions such as Cu, Mn, and Ca.

[0064] Example 1 (1) Grinding: Grind the high arsenic cobalt ore roasted sand and sieve it to 120 mesh to obtain high arsenic cobalt ore powder; (2) Second stage countercurrent leaching: First stage low acid leaching: Add water to the reaction tank, start stirring, then add the high arsenic cobalt ore powder obtained in step (1), stir for 30 min until uniform, add concentrated sulfuric acid and the high acid leaching solution obtained from the second stage high acid leaching, stir for 30 min until uniform, then carry out the heating and stirring leaching reaction at 85℃ for 3 h, filter, and obtain low acid leaching residue and low acid leaching solution; wherein, the amount of water, concentrated sulfuric acid and the high acid leaching solution obtained from the second stage high acid leaching are added so that the solid-liquid ratio of high arsenic cobalt ore powder to the liquid phase in the leaching system is 1:3 kg / L, and the hydrogen ion concentration in the liquid phase in the leaching system is 1.2 mol / L; Two-stage high-acid leaching: Water is added to the reaction tank, stirring is started, and then the low-acid leaching residue obtained from the first-stage low-acid leaching is added. After stirring for 30 minutes until uniform, concentrated sulfuric acid is added, and the reaction is carried out at 85°C with stirring for 60 minutes. Then, sodium chlorate equivalent to 10% of the mass of the low-acid leaching residue is added, and the leaching reaction is carried out at 90°C with stirring for 2.5 hours. After filtration, high-acid leachate is obtained. The amount of water and concentrated sulfuric acid added makes the solid-liquid ratio of the low-acid leaching residue to the liquid phase in the leaching system 1:3 kg / L, and the hydrogen ion concentration in the liquid phase of the leaching system is 3.5 mol / L. (3) Secondary purification to remove iron and arsenic: Oxidation and neutralization: The low-acid leachate obtained from the first low-acid leaching in step (2) is added to the reaction tank, stirring is started, ferrous sulfate is added to ensure that n(Fe):n(As) = 1.2:1 in the low-acid leachate, and after heating and stirring at 90℃ for 30 min, sodium chlorate is added to ensure that n(Fe):n(NaClO3) = 6:1.2, and the reaction is heated at 90℃ for 30 min. The reaction is kept at the temperature and the pH value is slowly adjusted using a 15% sodium carbonate solution. The reaction is carried out until the pH value reaches the reaction endpoint of 3.5, and the reaction is kept at the temperature for another 30 min. The total reaction time from the addition of ferrous sulfate to the end of the reaction is controlled to be 4 h. The solution is filtered to obtain a first iron and arsenic removal solution (the cobalt concentration is 14.62 g / L, and the yield of this step is 97.2%). Hydrolysis and precipitation: The iron and arsenic removal solution obtained from the oxidation and neutralization was stirred and heated to 90°C, kept at this temperature, and subjected to hydrolysis and precipitation reaction by slowly adjusting the pH value with a 10% sodium carbonate solution. After the pH value reached the reaction endpoint of 4.5, the reaction was continued to be kept at this temperature for 30 minutes. The total reaction time from the start of pH adjustment to the end of the reaction was controlled to be 4 hours. After filtration, a secondary iron and arsenic removal solution was obtained (the concentration of cobalt was 11.5 g / L, the concentration of magnesium was 6 g / L, and the cobalt yield in this step was 97.58%). (4) Cobalt precipitation and magnesium removal: After stirring and heating the secondary iron and arsenic removal liquid obtained in step (3) to 90°C, keep it warm and use a 5% sodium carbonate solution to slowly adjust the pH value to carry out cobalt precipitation and magnesium removal. After the pH value reaches the reaction endpoint of 7.5, continue to keep it warm for 30 minutes. Control the total reaction time from the start of pH adjustment to the end of the warm reaction to 4 hours. Filter to obtain cobalt precipitation material. (5) Sulfuric acid back dissolution of cobalt precipitate: Add the cobalt precipitate obtained in step (4) to water at a solid-liquid ratio of 1:2, stir evenly, add 98% sulfuric acid by mass until the pH value stabilizes at 4.0, heat to 90°C, and keep the reaction at this temperature for 30 minutes to obtain battery-grade cobalt sulfate solution. In steps (2) to (5), the stirring speed is 30 r / min.

[0065] After testing, in step (2), after two-stage countercurrent leaching, the silicon content in the high-acid leaching solution was ≤50mg / L; in the battery-grade cobalt sulfate solution obtained in step (5), the concentration of Co was 24.5g / L, the total cobalt yield was 93.1%, and the concentrations of other impurities were: Mg 0.659g / L, Fe <1mg / L, As <1mg / L, Ni 2.75g / L, Zn 0.208g / L, Mn 0.326g / L, Ca 0.377g / L, Cu 7.91mg / L, Al 5.12mg / L; among them, the cobalt-magnesium ratio reached 37:1, which is higher than the 2:1 cobalt-magnesium ratio in the process without cobalt precipitation and magnesium removal, thus improving the cobalt-impurity ratio and basically meeting the requirements for entering the extraction process, providing a guarantee for the subsequent P507 cobalt extraction and MVR evaporation crystallization to produce qualified products.

[0066] Example 2 (1) Grinding: Grind the high arsenic cobalt ore roasted sand and sieve it to 120 mesh to obtain high arsenic cobalt ore powder; (2) Second stage countercurrent leaching: First stage low acid leaching: Add the high acid leaching solution obtained from the second stage high acid leaching to the reaction tank, start stirring, then add the high arsenic cobalt ore powder obtained in step (1), stir for 30 min until uniform, and then carry out the heating and stirring leaching reaction at 90℃ for 3 h. Filter to obtain low acid leaching residue and low acid leaching solution; wherein, the amount of high acid leaching solution added from the second stage high acid leaching is such that the solid-liquid ratio of high arsenic cobalt ore powder to the liquid phase in the leaching system is 1:3 kg / L, and the hydrogen ion concentration in the liquid phase in the leaching system is 1.0 mol / L; Two-stage high-acid leaching: Water is added to the reaction tank, stirring is started, and then the low-acid leaching residue obtained from the first-stage low-acid leaching is added. After stirring for 30 minutes until uniform, concentrated sulfuric acid is added, and the reaction is carried out at 85°C with stirring for 60 minutes. Then, sodium chlorate equivalent to 10% of the mass of the low-acid leaching residue is added, and the leaching reaction is carried out at 90°C with stirring for 2.5 hours. After filtration, high-acid leachate is obtained. The amount of water and concentrated sulfuric acid added makes the solid-liquid ratio of the low-acid leaching residue to the liquid phase in the leaching system 1:3 kg / L, and the hydrogen ion concentration in the liquid phase of the leaching system is 3.3 mol / L. (3) Secondary purification to remove iron and arsenic: Oxidation and neutralization: The low-acid leachate obtained from the first low-acid leaching in step (2) is added to the reaction tank, stirring is started, ferrous sulfate is added to ensure that n(Fe):n(As) = 1.4:1 in the low-acid leachate, and after heating and stirring at 90℃ for 30 min, sodium chlorate is added to ensure that n(Fe):n(NaClO3) = 6:1.2, and the reaction is heated at 90℃ for 30 min. The reaction is kept at the temperature and the pH value is slowly adjusted using a 5% sodium carbonate solution. The oxidation and neutralization reaction is carried out until the pH value reaches the reaction endpoint of 4.0. The reaction is kept at the temperature for another 30 min. The total reaction time from the addition of ferrous sulfate to the end of the reaction is controlled to be 4 h. The solution is filtered to obtain a first iron and arsenic removal solution (the cobalt concentration is 15.18 g / L, and the yield of this step is 97.2%). Hydrolysis and precipitation: The iron and arsenic removal solution obtained from the oxidation and neutralization was stirred and heated to 90°C, kept at this temperature, and subjected to hydrolysis and precipitation reaction by slowly adjusting the pH value with a 10% sodium carbonate solution. After the pH value reached the reaction endpoint of 5.0, the reaction was continued for 30 minutes. The total reaction time from the start of pH adjustment to the end of the reaction was controlled to be 4 hours. After filtration, a secondary iron and arsenic removal solution was obtained (the concentration of cobalt was 11.76 g / L, the concentration of magnesium was 6.2 g / L, and the cobalt yield in this step was 97.5%). (4) Cobalt precipitation and magnesium removal: After stirring and heating the secondary iron and arsenic removal liquid obtained in step (3) to 90°C, keep it warm and use a 5% sodium carbonate solution to slowly adjust the pH value to carry out cobalt precipitation and magnesium removal. After the pH value reaches the reaction endpoint of 7.5, continue to keep it warm for 30 minutes. Control the total reaction time from the start of pH adjustment to the end of the warm reaction to 4 hours. Filter to obtain cobalt precipitation material. (5) Sulfuric acid back dissolution of cobalt precipitate: The cobalt precipitate obtained in step (4) is added to water at a solid-liquid ratio of 1:2. After stirring evenly, 98% sulfuric acid is added until the pH value stabilizes at 4.5. After heating to 90°C, the reaction is kept at the temperature for 30 minutes to obtain battery-grade cobalt sulfate solution. In steps (2) to (5), the stirring speed is 30 r / min.

[0067] After testing, in step (2), after two-stage countercurrent leaching, the silicon content in the high-acid leaching solution was ≤50mg / L; in the battery-grade cobalt sulfate solution obtained in step (5), the concentration of Co was 20.1g / L, the total cobalt yield was 92.1%, and the concentrations of other impurities were: Mg 0.62g / L, Fe <1mg / L, As <1mg / L, Ni 2.8g / L, Zn 0.28g / L, Mn 0.325g / L, Ca 0.147g / L, Cu 6.8mg / L, Al 3.12mg / L; among them, the cobalt-magnesium ratio reached 32:1, which is higher than the 2:1 cobalt-magnesium ratio in the process of removing magnesium without cobalt precipitation, thus improving the cobalt-impurity ratio and basically meeting the requirements for entering the extraction process, providing a guarantee for the subsequent P507 cobalt extraction and MVR evaporation crystallization to produce qualified products.

[0068] Example 3 (1) Grinding: Grind the high-arsenic cobalt ore roasted sand and sieve it to 120 mesh to obtain high-arsenic cobalt ore powder; (2) Second stage countercurrent leaching: First stage low acid leaching: Add water to the reaction tank, start stirring, then add the high arsenic cobalt ore powder obtained in step (1), stir for 5 minutes until uniform, add concentrated sulfuric acid and the high acid leaching solution obtained from the second stage high acid leaching, stir for 30 minutes until uniform, and then carry out the heating and stirring leaching reaction at 85°C for 3.5 hours. Filter to obtain low acid leaching residue and low acid leaching solution; wherein, the amount of water, concentrated sulfuric acid and the high acid leaching solution obtained from the second stage high acid leaching are added so that the solid-liquid ratio of high arsenic cobalt ore powder to the liquid phase in the leaching system is 1:3 kg / L, and the hydrogen ion concentration in the liquid phase in the leaching system is 1.11 mol / L; Two-stage high-acid leaching: Water is added to the reaction tank, stirring is started, and then the low-acid leaching residue obtained from the first-stage low-acid leaching is added. After stirring for 5 minutes until uniform, concentrated sulfuric acid is added. The mixture is heated and stirred at 85°C for 10 minutes. Then, sodium chlorate equivalent to 8.3% of the mass of the low-acid leaching residue is added. The leaching reaction is carried out at 85°C for 3.5 hours with heating and stirring. After filtration, a high-acid leachate is obtained. The amount of water and concentrated sulfuric acid added makes the solid-liquid ratio of the low-acid leaching residue to the liquid phase in the leaching system 1:3 kg / L, and the hydrogen ion concentration in the liquid phase of the leaching system is 3.41 mol / L. (3) Secondary purification to remove iron and arsenic: Oxidation and neutralization: The low-acid leachate obtained from the first low-acid leaching in step (2) is added to the reaction tank, stirring is started, ferrous sulfate is added to ensure that n(Fe):n(As) = 1.2:1 in the low-acid leachate, and after heating and stirring at 70℃ for 10 min, sodium chlorate is added to ensure that n(Fe):n(NaClO3) = 6:1.2; the reaction is heated at 85℃ for 20 min, kept warm, and oxidative neutralization reaction is carried out while slowly adjusting the pH value with a 10% sodium carbonate solution. After the pH value reaches the reaction endpoint of 3.5, the reaction is kept warm for another 40 min. The total reaction time from the addition of ferrous sulfate to the end of the reaction is controlled to be 4.5 h. After filtration, a first iron and arsenic removal solution is obtained (the concentration of cobalt is 15.01 g / L, and the yield of this step is 99.68%). Hydrolysis and precipitation: The iron and arsenic removal solution obtained from the oxidation and neutralization was stirred and heated to 80°C, kept at this temperature, and subjected to hydrolysis and precipitation reaction by slowly adjusting the pH value with a 10% sodium carbonate solution. After the pH value reached the reaction endpoint of 4.5, the reaction was continued at this temperature for 40 minutes. The total reaction time from the start of pH adjustment to the end of the reaction was controlled to be 4.5 hours. After filtration, a secondary iron and arsenic removal solution was obtained (cobalt concentration of 14.02 g / L, magnesium concentration of 7.64 g / L, and cobalt yield of 99.94% in this step). (4) Cobalt precipitation and magnesium removal: After stirring and heating the secondary iron and arsenic removal liquid obtained in step (3) to 80°C, keep it warm and use a 5% sodium carbonate solution to slowly adjust the pH value to carry out cobalt precipitation and magnesium removal. After the pH value reaches the reaction endpoint of 7.0, continue to keep it warm for 10 minutes. Control the total reaction time from the start of pH adjustment to the end of the warm reaction to be 3.5 hours. Filter to obtain cobalt precipitation material. (5) Sulfuric acid back dissolution of cobalt precipitate: Add the cobalt precipitate obtained in step (4) to water at a solid-liquid ratio of 1:1.8, stir evenly, add 50% sulfuric acid by mass until the pH value stabilizes at 5.4, heat to 70°C, and keep the reaction at this temperature for 20 minutes to obtain battery-grade cobalt sulfate solution. In steps (2) to (5), the stirring speed is 30 r / min.

[0069] After testing, in step (2), after two-stage countercurrent leaching, the silicon content in the high-acid leaching solution was ≤50mg / L; in the battery-grade cobalt sulfate solution obtained in step (5), the concentration of Co was 20.01g / L, the total cobalt yield was 99.5%, and the concentrations of other impurities were: Mg 0.618g / L, Fe <0.1mg / L, As <0.5mg / L, Ni 1.27g / L, Zn 0.087g / L, Mn 0.27g / L, Ca 0.126g / L, Cu 9.5mg / L, Al 0.31mg / L; among them, the cobalt-magnesium ratio reached 32:1, which is higher than the 2:1 cobalt-magnesium ratio in the process of removing magnesium without cobalt precipitation, thus improving the cobalt-impurity ratio and basically meeting the requirements for entering the extraction process, providing a guarantee for the subsequent P507 cobalt extraction and MVR evaporation crystallization to produce qualified products.

[0070] In order to determine whether the two-stage countercurrent leaching in step (2) is beneficial to avoid the formation of silicon polygel by Si and thus affect the filtration performance of the slurry residue, the high acid leaching residue obtained in step (2) was subjected to Raman spectroscopy detection and analysis.

[0071] like Figure 1 As shown, in the high-acid leaching residue obtained in step (2), at a depth of 400–600 cm⁻¹ -1 Only a weak absorption peak, generated by bond-symmetric stretching vibration, was detected at 600–800 cm⁻¹. -1 No obvious weak absorption peaks generated by bond bending vibrations were detected at 950–1150 cm⁻¹. -1 Only a weak absorption peak generated by bond asymmetric stretching vibration was detected at the point, meaning that no Si-O-Si bonds forming the silicon network structure were detected. Combined with the low Si content in the high acid leaching solution, this indicates that Si was filtered out with the high acid leaching residue in the form of other silicates, and the filtration performance was good.

[0072] Comparative Example 1 The only difference between this comparative example and Example 1 is that steps (4) and (5) are removed. Since the magnesium concentration in the secondary iron and arsenic removal solution obtained in step (3) is 6 g / L, it is necessary to remove impurities from the magnesium ions in the secondary iron and arsenic removal solution. The extraction process is: P204 extraction (34 stages, including 6 stages of cobalt washing and 5 stages of back-extraction) + Cyanex272 extraction (40 stages, including 6 stages of cobalt washing and 5 stages of back-extraction); the rest is the same as in Example 1.

[0073] In the Cyanex 272 extraction stage, compared to Example 1, ≥5 additional stages of back-extraction are required to remove magnesium in order to ensure that the concentration of magnesium ions in the resulting cobalt sulfate solution is ≤0.001 g / L (compliant with industry standard "Cobalt Sulfate and Nickel Sulfate for Batteries" (HG / T 5918~5919-2021)). However, the above operation is not only complex, but also, due to the presence of calcium ions in the secondary arsenic removal iron solution, the calcium concentration in the solution increases during the P204 cobalt washing and back-extraction stages, which easily causes calcium sulfate slag precipitation, resulting in calcium slag deposition in the extraction tank. This necessitates periodic manual cleaning of the tank, increasing labor intensity and reducing production efficiency.

[0074] Comparative Example 2 The only difference between this comparative example and Example 2 is that in step (2), ferrous sulfate is added at a mass ratio of 1:0.6 between the high arsenic cobalt ore powder obtained in step (1) and the high arsenic cobalt ore powder. The rest is the same as in Example 2.

[0075] The purpose of adding ferrous sulfate in the two-stage countercurrent leaching stage is twofold: first, to control the iron-arsenic ratio in the leaching solution for subsequent arsenic removal; and second, to act as a reducing agent to reduce the high-valent cobalt in the roasted sand. Testing showed that the iron concentration in the low-acid leaching solution was 30–40 g / L, the arsenic concentration was 30–40 g / L, and the total leaching rate in the two-stage countercurrent leaching was 98.0% (in Example 2, the iron concentration was 5–10 g / L, the arsenic concentration was 25–35 g / L, and the total leaching rate in the two-stage countercurrent leaching was 98.2%). Therefore, adding ferrous sulfate in the low-acid leaching did not significantly increase the cobalt leaching rate, nor did it reduce the arsenic concentration in the leaching solution; instead, it increased production costs.

[0076] Comparative Example 3 The only difference between this comparative example and Example 3 is that in step (2), the high-arsenic cobalt ore powder is directly leached with high acid; otherwise, it is the same as Example 3.

[0077] Tests showed that the silicon content in the high-acid leachate obtained in this comparative example was as high as 1.3 to 1.8 g / L.

[0078] like Figure 1 As shown, the high-acid leaching residue obtained in step (2) was analyzed by Raman spectroscopy, with the results obtained at 400–600 cm⁻¹. -1 A strong absorption peak, generated by bond-symmetric tensile vibration, was detected at 600–800 cm⁻¹. -1 A distinct weak absorption peak, generated by bond bending vibration, was detected at 950–1150 cm⁻¹. -1A distinct weak absorption peak was detected at the point where the bond asymmetric stretching vibration was generated, indicating the formation of Si-O-Si bonds in the silicon network structure. The peak shape was obvious and the proportion was large in all three intervals, indicating that under high acid conditions, hydrated silica in the high acid leaching solution of this comparative example will polymerize to form a difficult-to-filter network structure of silica polygel. The silica polygel will make it difficult to filter the leaching slurry and make it difficult to achieve efficient leaching in one-step high acid leaching.

Claims

1. A method for producing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore, characterized in that, Includes the following steps: (1) Grinding; (2) Two-stage countercurrent leaching; (3) Secondary purification to remove iron and arsenic; (4) Cobalt precipitation to remove magnesium; (5) Cobalt precipitation material to be dissolved in sulfuric acid.

2. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to claim 1, characterized in that, Specifically, the following steps are included: (1) Grinding: Grind the high-arsenic cobalt ore roasted sand and sieve it to obtain high-arsenic cobalt ore powder; (2) Second-stage countercurrent leaching: First-stage low-acid leaching: Add water to the reaction tank, start stirring, then add the high-arsenic cobalt ore powder obtained in step (1), stir evenly, add concentrated sulfuric acid and / or the high-acid leaching solution obtained from the second-stage high-acid leaching, stir evenly, carry out the heating and stirring leaching reaction, filter, and obtain low-acid leaching residue and low-acid leaching solution; or add the high-acid leaching solution obtained from the second-stage high-acid leaching to the reaction tank, start stirring, then add the high-arsenic cobalt ore powder obtained in step (1), stir evenly, carry out the heating and stirring leaching reaction, filter, and obtain low-acid leaching residue and low-acid leaching solution; Two-stage high acid leaching: Add water to the reaction tank, start stirring, then add the low acid leaching residue obtained from the first stage of low acid leaching, stir evenly, add concentrated sulfuric acid, heat and stir to react, then add oxidant, carry out the heating and stirring leaching reaction, filter, and obtain high acid leachate. (3) Secondary purification to remove iron and arsenic: Oxidation and neutralization: Add the low acid leachate obtained from the first low acid leaching in step (2) to the reaction tank, turn on the stirring, add ferrous sulfate, heat and stir, add oxidant, heat and react, keep warm and slowly adjust the pH value to carry out the oxidation and neutralization reaction, and continue to keep warm after the pH value reaches the reaction endpoint, filter, and obtain the first iron and arsenic removal solution. Hydrolysis and precipitation: After stirring and heating the primary iron and arsenic removal solution obtained from oxidation and neutralization, the solution is kept at a certain temperature and the pH value is slowly adjusted to carry out the hydrolysis and precipitation reaction. After the pH value reaches the reaction endpoint, the reaction is kept at a certain temperature and then filtered to obtain the secondary iron and arsenic removal solution. (4) Cobalt precipitation and magnesium removal: After stirring and heating the secondary iron and arsenic removal liquid obtained in step (3), keep it warm and slowly adjust the pH value to carry out cobalt precipitation and magnesium removal. After the pH value reaches the reaction endpoint, continue to keep it warm and filter to obtain cobalt precipitation material. (5) Sulfuric acid back dissolution of cobalt precipitate: Add the cobalt precipitate obtained in step (4) to water, stir evenly, add sulfuric acid until acidic, heat, and keep warm to react, and obtain battery grade cobalt sulfate solution.

3. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to claim 2, characterized in that: In step (1), the main components and mass fractions of the high-arsenic cobalt ore roasted sand are as follows: Co 6-10%, Mg 3-7%, Fe 6-10%, As 15-25%, Si 12-18%, Ni 0.5-1.5%, Zn 0.05-0.20%, Mn 0.10-0.25%, Ca 4-7%, Cu 0.2-0.4%, Al 2-4%; and the sieve is passed through a 120-mesh sieve.

4. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to claim 2 or 3, characterized in that: In step (2), during the first-stage low-acid leaching, the solid-liquid ratio of the high-arsenic cobalt ore powder to the liquid phase in the leaching system is 1:2 to 4 kg / L; the hydrogen ion concentration in the liquid phase of the leaching system is 0.2 to 1.7 mol / L; after adding the high-arsenic cobalt ore powder obtained in step (1), and after adding concentrated sulfuric acid and / or the high-acid leaching solution obtained from the second-stage high-acid leaching, the mixture is stirred for 5 to 30 minutes until homogeneous; the temperature of the heating and stirring leaching reaction is 80 to 90°C, and the time is 3 to 4 hours.

5. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to any one of claims 2 to 4, characterized in that: In step (2), after adding the low-acid leaching residue obtained from the first-stage low-acid leaching in the second-stage high-acid leaching, the mixture is stirred for 5-30 minutes until homogeneous; the solid-liquid ratio of the low-acid leaching residue to the liquid phase in the leaching system is 1:2-4 kg / L; the hydrogen ion concentration in the liquid phase of the leaching system is 2.6-3.5 mol / L; the temperature of the heating and stirring reaction is 80-90℃, and the time is 10-80 minutes; the amount of oxidant used is equivalent to 5-15% of the mass of the low-acid leaching residue; the oxidant includes one or more of sodium chlorate, hydrogen peroxide, ozone, or oxygen; the temperature of the heating and stirring leaching reaction is 80-90℃, and the time is 2-4 hours.

6. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to any one of claims 2 to 5, characterized in that: In step (3), during the oxidation and neutralization, the amount of ferrous sulfate used is such that the molar ratio of iron to arsenic in the low-acid leachate is 1.2–1.4:1; the heating and stirring temperature is 70–90°C, and the time is 10–40 min; the amount of oxidant used is to reduce the Fe in the low-acid leachate. 2+ Oxidized to Fe 3+ The dosage is 1.1 to 1.3 times the theoretical amount; the oxidant includes one or more of sodium chlorate, hydrogen peroxide, ozone, or oxygen; the heating reaction temperature is 70 to 90°C, and the time is 10 to 40 minutes; the pH value is adjusted with a 5 to 15% alkaline solution; the pH value at the reaction endpoint is 3.5 to 4.0; the heat preservation reaction time is 30 to 60 minutes; the total reaction time from the addition of ferrous sulfate to the end of the heat preservation reaction is controlled within the range of 4 to 5 hours.

7. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to any one of claims 2 to 6, characterized in that: In step (3), during the hydrolysis precipitation, the stirring and heating are carried out to 70-90°C; the pH value is adjusted with an alkaline solution of 5-15% by mass; the pH value at the end of the reaction is 4.5-5.0; the heat preservation reaction time is 20-60 min; and the total reaction time from the start of pH adjustment to the end of the heat preservation reaction is controlled within the range of 3-5 h.

8. The production method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to any one of claims 2 to 7, characterized in that: In step (4), the stirring and heating are carried out to 70-90°C; the pH value is adjusted with an alkaline solution of 5-10% by mass; the pH value at the end of the reaction is 7.0-7.5; the heat preservation reaction time is 10-60 min; and the total reaction time from the start of pH adjustment to the end of heat preservation reaction is controlled within the range of 3.5-4.5 h.

9. The method for preparing battery-grade cobalt sulfate by purifying and removing impurities from high-arsenic cobalt ore according to any one of claims 2 to 8, characterized in that: In step (5), the solid-liquid ratio of the cobalt precipitate to water is 1:1.5 to 2.5; the pH value of the acid is 4.0 to 5.5; the mass fraction of the sulfuric acid is 10 to 98%; the heating is to 70 to 90°C; the heat preservation reaction time is 20 to 50 min; in steps (2) to (5), the stirring speed is 30 to 60 r / min.

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