Method for preparing high-purity nickel through synergistic circulation of electrodeposited nickel anolyte

Abstract

The invention belongs to the technical field of nickel material smelting, and discloses a method for preparing high-purity nickel by synergic circulation of electrodeposited nickel anolyte, which comprises the following steps: performing primary nickel precipitation on a nickel sulfate solution and sodium carbonate, and performing solid-liquid separation to obtain nickel carbonate and primary filtrate; carrying out second-stage nickel precipitation on the first-stage filtrate and sodium hydroxide, and carrying out solid-liquid separation to obtain nickel hydroxide and second-stage filtrate; the method comprises the following steps: performing electrodeposition on nickel carbonate and nickel hydroxide, performing acid dissolution on anolyte to generate a nickel-containing solution, preparing a new cathode solution from the nickel-containing solution, pure water, boric acid, the anolyte and sodium sulfate, and performing electrodeposition to obtain high-purity nickel. The process has remarkable advantages, sodium carbonate is used for primary nickel precipitation, the requirement for large-scale nickel precipitation is met, and the product is easy to filter and low in cost; sodium hydroxide is used for secondary nickel deposition, deep nickel deposition is achieved, the use amount is small, and the defect of difficult filtration is avoided; and the front nickel deposition process can intercept impurities, the impurity removal effect and the separation efficiency are both considered, and the overall production cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nickel material smelting, and relates to a preparation process of high-purity nickel, in particular to a method for preparing high-purity nickel by synergistic circulation of electrodeposited nickel anode liquid. BACKGROUND

[0002] Nickel is widely used in the fields of stainless steel, batteries, electroplating, alloys and the like. With the rapid development of the new energy industry, especially the surge in demand for high-purity nickel for power batteries, nickel smelting production technology is constantly innovated. The traditional sulfate system electrodeposited nickel production process mainly prepares metal nickel through steps of leaching, purification, electrodeposition and the like.

[0003] In the traditional process, for the recycling of the anode liquid after electrodeposited nickel, the anode liquid is usually opened in three parts, that is, a part is subjected to nickel deposition, a part is used as an acid solvent for the product of nickel deposition, and a part directly participates in the preparation of the cathode liquid. The nickel recovery rate is low and the production cost is high in the process flow. At the same time, auxiliary materials such as boric acid cannot be effectively recycled in the system and need to be added in a certain amount each time, which consumes a large amount. In addition, the recovery and utilization rate of by-products such as sodium sulfate is low, and high-value utilization of resources cannot be achieved, and the production efficiency is low due to the inefficient connection of each production link. SUMMARY

[0004] In view of the defects and deficiencies of the prior art, in a first aspect, the application provides a method for preparing high-purity nickel by synergistic circulation of electrodeposited nickel anode liquid, and in a second aspect, the application provides high-purity nickel.

[0005] In a first aspect, the application provides a method for preparing high-purity nickel by synergistic circulation of electrodeposited nickel anode liquid, comprising the following steps: Step 1, reacting the nickel sulfate solution with sodium carbonate to carry out primary nickel deposition, and performing solid-liquid separation to obtain nickel carbonate and a primary nickel deposition filtrate; Step 2, reacting the primary nickel deposition filtrate with sodium hydroxide to carry out secondary nickel deposition, and performing solid-liquid separation to obtain nickel hydroxide and a secondary nickel deposition filtrate; Step 3, using the anode liquid after electrodeposition to perform acid dissolution of the nickel carbonate and the nickel hydroxide to generate a nickel-containing solution; Step 4, mixing the nickel-containing solution with pure water, boric acid, anode liquid and sodium sulfate to prepare a new cathode liquid, and electrodeposition of the new cathode liquid to obtain high-purity nickel.

[0006] Preferably, the nickel sulfate solution is subjected to oil removal treatment, the obtained nickel sulfate solution has a nickel content of 70-130 g / L, a content of impurities such as copper, iron, lead, manganese and arsenic of 10-50 ppm, a pH value of 3-5 and an oil content of 3-10 ppm.

[0007] Preferably, the anolyte mainly contains nickel sulfate and sulfuric acid, the content of nickel is 60-65 g / L, the content of sulfuric acid is 42-50 g / L, and the content of impurities such as copper, iron, cobalt, lead, manganese and arsenic is 4-10 ppm.

[0008] Preferably, in step 1, the ratio of the molar amount of sodium carbonate to the molar amount of nickel ions in the nickel sulfate solution is 1.1-1.5:1, the nickel precipitation time is 60-120 min, and the nickel precipitation temperature is 75-90℃.

[0009] Preferably, in step 2, the ratio of the molar amount of sodium hydroxide to the molar amount of nickel ions in the primary nickel precipitation filtrate is 2.1-2.2:1, the nickel precipitation time is 60-120 min, and the nickel precipitation temperature is 75-90℃.

[0010] Preferably, the nickel carbonate and nickel hydroxide obtained in step 1 are both water-washed to remove impurities, and the washing is performed 2-3 times.

[0011] Further preferably, the washing water after impurity removal is recycled and used multiple times, and if the COD and other impurity ions in the washing water increase after multiple uses, the washing water is returned to the raw material slurry section.

[0012] Further preferably, the recycling number of the washing water is 8-10 times, and the solid-liquid ratio during water washing is 1:3-5 t / m 3 .

[0013] Preferably, in step 3, the amount of the anolyte added is based on the amount of sulfuric acid, and the ratio of the molar amount of sulfuric acid to the total molar amount of nickel ions in the nickel carbonate and nickel hydroxide is 1.1-1.2:1, the acid dissolution time is 30-60 min, and the acid dissolution temperature is 70-90℃.

[0014] Preferably, in step 4, the content of boric acid in the cathode new solution is 3-10 g / L, the content of nickel in the cathode new solution is 70-100 g / L, the pH value of the cathode new solution is 3.0-5.0, and the content of sodium ions is 20-30 g / L.

[0015] Preferably, in step 4, during electrodeposition, the temperature of the cathode new solution is 65-70℃, the current intensity is 7500-15800 A, the current density is 160-190 A / m 2 , the cathode cycle is 6-8 d, and the cell voltage is 3.3-3.8 V.

[0016] Preferably, the anolyte after electrodeposition is removed and recovered, specifically: a part of the anolyte is added with a removal agent to remove impurities, and after pressure filtration, an anode purified solution is obtained and returned to step 4 to participate in the preparation of the cathode solution; another part of the anolyte is returned to step 3 for acid dissolution.

[0017] It is further preferred that the impurity removing agent is any one or both of barium carbonate (BaCO3) and black nickel (NiOOH).

[0018] It is further preferred that the amount of barium carbonate is such that the molar ratio of barium carbonate to lead ions in the anolyte is 1-1.1:1.

[0019] It is further preferred that the amount of black nickel is calculated based on the amount of Fe 2+ and Co 2+ in the anolyte, n 黑镍 =(1-1.1)×n Fe2+ +(2-2.1)n Co3+ Preferably, the sodium sulfate solution obtained by adding sulfuric acid to the secondary nickel precipitation filtrate for neutralization reaction is subjected to evaporation crystallization to obtain solid particles of sodium sulfate.

[0020] It is further preferred that the evaporation crystallization is performed at a temperature of 135-150°C for 60-120 min.

[0021] It is further preferred that the ratio of the molar amount of sulfuric acid added to the sum of the molar amounts of hydroxide and carbonate in the secondary nickel precipitation filtrate is 1.1-1.2:1.

[0022] Preferably, the solid-liquid separation in steps 1 and 2 is performed by pressure filtration.

[0023] Preferably, the nickel-containing solution prepared in step 3 is subjected to pressure filtration.

[0024] Preferably, the cathode new solution prepared in step 4 is subjected to precision filtration.

[0025] In a second aspect, the present application provides a high-purity nickel having a purity of greater than 99.97% and prepared by the above method.

[0026] Compared with the prior art, one or more technical solutions provided by the present application have at least one of the following advantages: (1) The use of sodium carbonate for nickel precipitation has a slow reaction rate, large particle size of the precipitated crystal particles, and easy filtration; the use of sodium hydroxide for nickel precipitation forms a gelatinous nickel hydroxide precipitate that is difficult to filter; therefore, sodium carbonate is used for primary nickel precipitation to meet the demand for large-scale nickel precipitation, and the product is easy to filter; secondary sodium hydroxide is used for deep nickel precipitation with a small amount, which avoids the difficulty of filtration, and the pre-nickel precipitation process intercepts impurities, taking into account the impurity removal effect and separation efficiency; and the price of sodium carbonate is lower than that of sodium hydroxide, the reagent consumption of primary nickel precipitation is large, and the use of sodium carbonate is beneficial to cost control, the reagent consumption of secondary nickel precipitation is small, and the amount of sodium hydroxide is small, which can reduce the cost.

[0027] (2) The preparation method of high-purity nickel provided by the application has the advantages of short process, high degree of continuity, and high resource utilization rate.

[0028] (3) Resource closed-loop utilization, efficient recycling of anolyte and washing water significantly reduces new water consumption and material loss, and realizes closed-loop utilization of resources.

[0029] (4) High-value by-product, the purity of the sodium sulfate solution after adjusting the acid of the secondary nickel precipitation filtrate is high, and the sodium sulfate product can be prepared by evaporation crystallization, realizing high-value utilization of by-products.

[0030] (5) Effective control of impurities, impurity removal processes (water washing and anolyte impurity removal) are set in multiple processes, which can effectively control the impurity content in the system and effectively improve the purity of the electrodeposited nickel and sodium sulfate product, thereby effectively ensuring product quality.

[0031] (6) Reduced production energy consumption, boric acid is closed-circuit and recycled in the system, only needs to be added for the first time, and basically does not need to be supplemented in subsequent production, reducing production cost.

[0032] (7) Environmentally friendly, recycling of washing water and high-value utilization of by-products reduce wastewater discharge and environmental pollution, meeting the requirements of green production. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The process flow chart of the method for preparing high-purity nickel by electrodeposition of nickel anolyte is provided. DETAILED DESCRIPTION

[0034] The application provides the following specific technical solutions.

[0035] In a first aspect, the application provides a method for preparing high-purity nickel by electrodeposition of nickel anolyte, comprising the following steps: Step 1, reacting a nickel sulfate solution with sodium carbonate to perform primary nickel precipitation, and performing solid-liquid separation to obtain nickel carbonate and a primary nickel precipitation filtrate; Step 2, reacting the primary nickel precipitation filtrate with sodium hydroxide to perform secondary nickel precipitation, and performing solid-liquid separation to obtain nickel hydroxide and a secondary nickel precipitation filtrate; Step 3, using the anolyte after electrodeposition to perform acid dissolution of the nickel carbonate and the nickel hydroxide to generate a nickel-containing solution; Step 4, mixing the nickel-containing solution with pure water, a boric acid solution, an anolyte, and a sodium sulfate solution to prepare a new cathode solution, and electrodeposition of the new cathode solution to obtain high-purity nickel.

[0036] The first-stage nickel immersion process addresses the high-volume front-end nickel immersion demand by using lower-priced sodium carbonate. This leverages sodium carbonate's moderate reaction rate and the resulting large-particle nickel carbonate that is easy to filter, ensuring efficient immersion and separation while effectively controlling costs in the main immersion stages. The second-stage nickel immersion process, a deep immersion step, consumes less reagent. Using sodium hydroxide, even a small amount achieves deep nickel removal, avoiding the formation of gel-like, difficult-to-filter precipitates. Furthermore, the pre-immersion process focuses on externally added nickel sulfate solution, effectively intercepting impurities such as thiosulfate, sulfides, and COD, preventing their introduction into the downstream electrolysis system. This ensures the high purity of the nickel carbonate and nickel hydroxide products. The nickel-containing solution obtained after electrowinning and acid dissolution in the anolyte maintains its purity. Finally, high-purity nickel is obtained through electrowinning with a fresh cathode solution. This two-stage nickel immersion design, combining reagent characteristics, usage requirements, and process logic, achieves synergistic optimization of immersion effect, filtration efficiency, and cost control.

[0037] The main chemical reaction equations in the above process are as follows: Primary nickel plating: NiSO4 + Na2CO3 = NiCO3↓ + Na2SO4 Secondary nickel plating: NiSO4 + 2NaOH = Ni(OH)2↓ + Na2SO4 Acid solubility: NiCO3 + H2SO4 = NiSO4 + CO2↑ + H2O Ni(OH)₂ + H₂SO₄ = NiSO₄ + 2H₂O Nickel electrolytic deposition: Ni 2+ +2e - =Ni (cathode) 2H2O-4e - =O2↑+4H + (anode) 2Ni 2+ +2H₂O=2Ni+O₂↑+4H + (Overall reaction) Preferably, the nickel sulfate solution is deoiled to obtain a nickel solution with a nickel content of 70-130 g / L, a content of impurities such as copper, iron, lead, manganese and arsenic of 10-50 ppm, a pH value of 3-5, and an oil content of 3-10 ppm.

[0038] In practical application, the oil removal treatment is specifically as follows: (1) first, the pH of the nickel sulfate solution is adjusted to a stable interval of 3-5 (if deviating, it is adjusted by using dilute sulfuric acid or weak base), to avoid the influence of pH fluctuation on the efficiency of the subsequent oil removal agent, and at the same time, the solution is heated to 40-60°C, to reduce the viscosity of the oil phase and promote the coalescence of oil droplets; (2) a non-ionic demulsifier (such as polyoxyethylene polyoxypropylene ether) suitable for weak acid system is added to the solution, to destroy the oil-water emulsion system and make the small oil droplets coalesce into large oil beads, and activated carbon adsorption can also be used to adsorb dispersed oil and part of organic impurities by using the porous structure of activated carbon; (3) the oil residue and the solution are separated by using a pressurized filtration or air flotation separation process, the pressurized filtration can intercept activated carbon and oil sludge floes, and the air flotation method can form a floating sludge layer by using micro-bubbles to carry oil beads to float and be scraped off, to obtain a refined nickel sulfate solution with an oil content of 3-10 ppm.

[0039] The oil removal treatment can avoid the oil being entrapped by the nickel carbonate and nickel hydroxide precipitation, improve the purity of the nickel-based precipitate, and provide high-quality raw materials for subsequent acid dissolution; can prevent the oil from entering the electrodeposition process, avoid the formation of an oil film on the cathode surface, and ensure the surface quality of high-purity nickel and the electrodeposition current efficiency; can reduce the adhesion and blockage of equipment by oil, prolong the service life of the equipment, and reduce the operation and maintenance cost; and can cooperate with subsequent washing and other processes to intercept organic impurities in advance, which is consistent with the overall logic of the front-end impurity control process.

[0040] Preferably, the anolyte mainly contains nickel sulfate and sulfuric acid, the nickel content is 60-65 g / L, the sulfuric acid content is 42-50 g / L, and the contents of impurities such as copper, iron, cobalt, lead, manganese and arsenic are 4-10 ppm.

[0041] Preferably, in step 1, the ratio of the molar amount of sodium carbonate to the molar amount of nickel ions in the nickel sulfate solution is 1.1-1.5:1, the nickel precipitation time is 60-120 min, and the nickel precipitation temperature is 75-90°C.

[0042] The preferred process parameters of the first-stage nickel precipitation in step 1 have significant technical advantages, the molar ratio of sodium carbonate to nickel ions is controlled to be 1.1-1.5:1, which not only ensures that the nickel ions are fully precipitated, but also avoids waste caused by excessive reagents, achieving a balance between the effect of nickel precipitation and the cost of raw materials; the reaction time of 60-120 min and the nickel precipitation temperature of 75-90°C are suitable for the reaction characteristics of sodium carbonate, which can promote the full growth of nickel carbonate crystal grains and form large-sized precipitates, greatly reducing the difficulty of filtration, improving the efficiency of solid-liquid separation, and reducing the probability of impurities being entrapped by the precipitate, thereby ensuring the high purity of the nickel carbonate. The reaction rate of the first-stage nickel precipitation under the parameters is moderate, there is no problem of local over-alkalinity or fine-grained crystal, which provides high-quality raw materials for the subsequent second-stage nickel precipitation and anolyte acid dissolution process, and lays a solid foundation for the stable preparation of high-purity nickel.

[0043] Preferably, in step 2, the ratio of the molar amount of sodium hydroxide to the molar amount of nickel ions in the primary nickel precipitation filtrate is 2.1-2.2:1, the nickel precipitation time is 60-120 min, and the nickel precipitation temperature is 75-90℃.

[0044] The preferred process parameters for secondary nickel precipitation in step 2 have outstanding technical advantages. The molar ratio of sodium hydroxide to nickel ions in the primary nickel precipitation filtrate is controlled at 2.1-2.2:1. This low excess ratio can achieve deep precipitation of residual nickel ions in the filtrate, avoid high pH value of the system due to excessive alkali, reduce the generation of colloidal nickel hydroxide, and maximize the control of reagent consumption, which meets the scene requirement of small reagent consumption for secondary nickel precipitation. The reaction time of 60-120 min and the nickel precipitation temperature of 75-90℃ can promote the ordered growth of nickel hydroxide grains, improve the defect of easy gelation and difficult filtration, improve the solid-liquid separation efficiency, and reduce the probability of precipitated impurities, ensuring the purity of nickel hydroxide. The secondary nickel precipitation under this parameter provides a high-purity nickel source for subsequent anode liquid acid dissolution and high-purity nickel electrodeposition, helping the overall process to achieve efficient recovery of nickel and control of product quality.

[0045] Preferably, the nickel carbonate and nickel hydroxide obtained in step 1 are both washed with water to remove impurities, and the washing is performed 2-3 times.

[0046] Further preferably, the washing water after impurity removal is recycled and used multiple times. If the COD and thiosulfate impurity ions reach the discharge concentration, the washing water is returned to the raw material slurry section.

[0047] Water washing can effectively remove soluble salts, unreacted reagents, thiosulfate, COD and other impurities trapped in the surface and pores of the two kinds of nickel precipitates, significantly improving the purity of the precipitates and laying a foundation for the preparation of high-purity nickel-containing solution in the subsequent anode liquid acid dissolution. Second, recycling the washing water can significantly reduce the consumption of fresh water and the cost of wastewater treatment, meeting the requirements of green chemical production. Finally, the washing water with excessive impurities is returned to the raw material slurry section, which not only avoids the environmental pressure of wastewater discharge, but also recovers trace nickel resources in the washing water, while achieving centralized pretreatment of impurities to prevent them from affecting the quality of the final high-purity nickel product in the electrolysis system.

[0048] The raw material slurry section is a nickel sulfate solution obtained by leaching, extraction purification, oil removal and other processes from nickel-containing minerals or intermediate products (such as nickel concentrate, high-nickel matte, nickel beans, nickel hydroxide, nickel carbonate, etc.). The nickel-containing raw material before leaching needs to be slurry, which is the raw material slurry section.

[0049] Further preferably, the recycling frequency of the washing water is 8-10 times, and the solid-liquid ratio during washing is 1:3-5 t / m 3 .

[0050] Preferably, in step 3, the ratio of the mass of the anolyte to the sum of the mass of the nickel carbonate and the mass of the nickel hydroxide is 10-50:1, the acid dissolution time is 30-60 min, and the acid dissolution temperature is 70-90°C.

[0051] The high-purity nickel carbonate and the high-purity nickel hydroxide obtained by acid dissolution and the preceding primary and secondary nickel precipitation provide a low-impurity nickel source for the acid dissolution, and the mild reaction conditions of the acid dissolution, i.e., the 70-90°C temperature and the 30-60 min time length, can adapt to the dissolution characteristics of the high-purity nickel precipitate, ensuring sufficient dissolution and preventing a large amount of residual impurities in the precipitate from being dissolved due to a violent reaction, thereby continuing the process logic of "controlling impurities at the front end" and ensuring the purity of the nickel-containing solution. Moreover, the acid dissolution uses the anolyte after electrodeposition as an acid source, thereby realizing the recycling of the anolyte and reducing the cost of purchasing new acid; the nickel-containing solution obtained by the acid dissolution can be directly used to prepare a new catholyte without additional complex purification, thereby linking the subsequent electrodeposition process; at the same time, the anolyte is quantitatively returned to the acid dissolution process, thereby realizing the synergistic effect of "acid dissolution + nickel supplementing", accurately controlling the nickel concentration and the acidity of the nickel-containing solution, and providing an adaptive raw material system for the stable preparation of the new catholyte and the efficient electrodeposition of high-purity nickel, thereby forming a closed-loop process of "anolyte recycling-acid dissolution-electrodeposition".

[0052] Preferably, in step 4, the content of boric acid in the new catholyte is 3-10 g / L, the content of nickel in the new catholyte is 70-100 g / L, the concentration of sodium ions in the new catholyte is 20-30 g / L, and the pH value of the new catholyte is 3.0-5.0.

[0053] The preferred parameters of the new catholyte can comprehensively ensure the stability of the electrodeposition of high-purity nickel and the product quality. The 3-10 g / L boric acid can effectively buffer the pH of the system, avoid the precipitation of impurities due to a large fluctuation in the pH near the cathode, and optimize the crystallization form of nickel; the 70-100 g / L nickel content is in the adaptive range of electrodeposition, which can ensure the electrodeposition efficiency and prevent the crystallization from being coarse to affect the purity; and the 3.0-5.0 pH value can inhibit the preferential discharge of hydrogen ions, improve the current efficiency, and maintain the stability of the system in cooperation with the boric acid, thereby ultimately assisting in the production of high-purity and high-quality electrodeposited nickel.

[0054] Preferably, in step 4, during the electrodeposition, the temperature of the new catholyte is 65-70°C, the current intensity is 7500-15800 A, the current density is 160-190 A / m 2 , the cathode cycle is 6-8 d, and the cell voltage is 3.3-3.8 V.

[0055] The preferred parameters of the electrodeposition can take into account the efficiency and quality of the preparation of high-purity nickel: the 160-190 A / m 2The current density and the current intensity of 7500-15800 A can ensure uniform and efficient deposition of nickel ions and avoid coarse grains or slow deposition. The cathode cycle of 6-8 d can promote the compact growth of the nickel layer and balance the productivity and purity. The tank voltage of 3.3-3.8 V can inhibit the side reaction and hydrogen ion discharge, improve the current efficiency, and reduce the power consumption. The overall parameters can ensure the stable and controllable electrodeposition process and help produce high-grade and high-purity nickel.

[0056] Preferably, the anolyte after electrodeposition is subjected to impurity removal and recovery, specifically, a part of the anolyte is added with an impurity removal agent for impurity removal, and the anolyte after pressure filtration is obtained as an anolyte purification liquid and returned to step 4 for preparation of the catholyte; another part of the anolyte is returned to step 3 for acid dissolution.

[0057] The part of the anolyte is added with the impurity removal agent for purification and then returned to step 4 for preparation of the catholyte, which can remove the impurities enriched in the electrodeposition process, ensure the purity of the catholyte, and avoid affecting the quality of the high-purity nickel. The other part is directly returned to step 3 for acid dissolution, which realizes the recycling of the anolyte, reduces the amount of new acid to be added, and reduces the raw material cost. The design builds a closed-loop utilization system for the anolyte, which not only strengthens the impurity control in the whole process, but also improves the resource utilization rate, and takes into account the product quality and process economy, which is consistent with the green and circular chemical production concept.

[0058] Further preferably, the impurity removal agent is any one or both of barium carbonate (BaCO3) and black nickel (NiOOH).

[0059] The catholyte has strict requirements on the component ratio: the nickel content needs to be controlled to 70-100 g / L, the boric acid content needs to be controlled to 3-10 g / L, and the pH needs to be controlled to 3.0-5.0. The concentration of sulfate ions only needs to meet the charge balance with nickel ions and sodium ions and meet the minimum requirement for maintaining the conductivity of the solution. The concentration of sulfate ions in the anolyte is significantly higher than the suitable concentration of the catholyte due to the continuous accumulation of sulfate ions. Therefore, the sulfate ions in the anolyte are in an excess state compared with the requirement for preparing the catholyte. The use of barium carbonate for impurity removal can simultaneously achieve deep removal of the excess sulfate ions and lead ions in the anolyte, and the double purification effect is significant. Barium sulfate is produced by the reaction of barium carbonate and sulfate ions in the anolyte, and the obtained barium sulfate and lead ions are co-crystallized and precipitated, which avoids the influence of lead on the purity of the cathode nickel. The granular precipitate generated by the reaction is easy to separate by filtration, and the carbonate ions are converted into carbon dioxide and water in an acidic system, which does not introduce secondary pollution. The suitable process is closed-loop, the raw material is cheap, and the addition amount is precisely controllable, which has both economic and environmental benefits. The amount of barium carbonate is preferably 1-1.1:1 in terms of the molar amount of barium carbonate to lead ions in the anolyte.

[0060] When black nickel is selected as the impurity removal agent, Fe 2+ is oxidized to Fe 3+ , and Co 2+ is oxidized to Co 3+, the oxidized ions form hydroxyl precipitates which are removed, avoiding affecting the deposition of cathode nickel in the electrolysis process, and the black nickel is converted into Ni 2+ after oxidation, which can participate in subsequent electrodeposition as a nickel source, does not introduce new harmful impurities into the anolyte, and ensures the quality of the cathode nickel. The amount of black nickel is calculated based on the amount of Fe 2+ and Co 2+ in the anolyte, n 黑镍 =(1~1.1)×n Fe2+ +(2~2.1)n Co2+ .

[0061] In actual application, barium hydroxide can be used to replace barium carbonate to remove lead ions, but its effect is not as good as barium carbonate. Lead hydroxide directly reacts with lead ions to produce lead hydroxide precipitate, which cannot achieve the double purification effect of barium carbonate.

[0062] Preferably, the anolyte after electrodeposition preferably meets the requirements of acid dissolution in step 3, and the remaining anolyte enters step 4 to participate in the configuration of the new cathode liquid.

[0063] Further preferably, the amount of anolyte after electrodeposition entering step 3 is 85-95vol%, and the remaining 5-15vol% of anolyte after electrodeposition enters step 4 to participate in the configuration of the new cathode liquid.

[0064] Preferably, the sodium sulfate solution obtained by adjusting and neutralizing the secondary nickel deposition filtrate is then evaporated and crystallized to obtain solid particles of sodium sulfate.

[0065] The sodium sulfate-containing filtrate generated during the nickel deposition stage is treated as a resource, converting the waste liquid into reusable or marketable sodium sulfate solids, achieving efficient recovery of by-products and improving the overall resource utilization rate of the process. At the same time, adjusting and neutralizing the filtrate can eliminate its alkalinity, avoiding direct evaporation which can cause equipment corrosion and ensuring the stability of the crystallization process. After removing soluble salts through evaporation and crystallization, the load and cost of subsequent wastewater treatment are significantly reduced, avoiding environmental risks associated with waste liquid discharge and adding additional economic benefits to the process, in line with the production philosophy of green chemical industry and resource recycling.

[0066] Further preferably, the temperature for evaporation and crystallization is 135-150°C, and the crystallization time is 60-120min.

[0067] The above preferred parameters can adapt to the crystallization characteristics of sodium sulfate, promoting the rapid and complete analysis of sodium sulfate, forming solid particles with uniform particle size, improving the crystallization efficiency and product quality; at the same time, this parameter can shorten the crystallization period, reduce energy consumption, and also reduce the risk of equipment corrosion, achieving efficient resource recovery of sodium sulfate in waste liquid, taking into account environmental benefits and economic benefits.

[0068] Further preferably, the ratio of the molar amount of sulfuric acid to the sum of the molar amounts of hydroxyl ions and carbonate ions in the secondary nickel precipitation filtrate is 1.1-1.2:1.

[0069] After nickel precipitation, the solution is alkaline, so sulfuric acid is added to neutralize the filtrate, neutralize the excess alkali, and completely convert the residual carbonate ions into carbon dioxide to separate the system, avoiding the generation of sodium bicarbonate, sodium carbonate and other impurities during subsequent evaporation and crystallization, and ensuring the purity of the sodium sulfate product; a moderate excess of sulfuric acid can inhibit the hydrolysis of impurity ions, reduce the entrainment of impurities in the crystalline product, promote the rapid precipitation of sodium sulfate and the formation of uniform particles, and improve the crystallization efficiency and product yield.

[0070] Preferably, solid-liquid separation in steps 1 and 2 is performed using a pressure filtration separation process.

[0071] Preferably, the nickel-containing solution prepared in step 3 is subjected to pressure filtration separation.

[0072] The strong solid-liquid separation capability of pressure filtration can efficiently trap nickel carbonate and nickel hydroxide solids from the nickel precipitation stage, as well as fine impurity particles in the nickel-containing solution and the new cathode solution, ensuring the purity of the material liquid in each stage and laying a solid foundation for high-purity nickel production; at the same time, pressure filtration has high separation efficiency and stable operation, which can meet the needs of continuous production, reduce process time, and balance product quality and process efficiency.

[0073] Preferably, the new cathode solution prepared in step 4 is subjected to precision filtration.

[0074] In actual application, to ensure the quality of the new cathode solution, precision filtration is performed to filter impurities in the solution, and a precision filter is used to filter the new cathode solution.

[0075] In a second aspect, the present application provides a high-purity nickel prepared by the above method, wherein the purity of the high-purity nickel is greater than 99.97%.

[0076] To make the technical problems, technical solutions and technical advantages of the present application clearer, specific examples will be described in detail below, but the scope of protection of the present application is not limited to the following specific examples.

[0077] Unless otherwise defined, all professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present application.

[0078] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods.

[0079] Figure 1The process flow chart of the method for preparing high-purity nickel by synergic circulation of electrodeposited nickel anode solution is provided in the application.

[0080] In step 1 of the embodiment of the application, the nickel sulfate solution in the oil-removed nickel sulfate solution has a nickel content of 70-130 g / L, a content of impurities such as copper, iron, lead, manganese and arsenic of 10-50 ppm, a pH value of 3-5 and an oil content of 3-10 ppm. The anode solution used in step 4 mainly contains nickel sulfate and sulfuric acid, has a nickel content of 60-65 g / L, a sulfuric acid content of 42-50 g / L and a content of impurities such as copper, iron, cobalt, lead, manganese and arsenic of 4-10 ppm.

[0081] Embodiment 1 A method for preparing high-purity nickel by synergic circulation of electrodeposited nickel anode solution, comprising the following steps: Step 1, primary nickel precipitation, mixing sodium carbonate and oil-removed nickel sulfate solution, the molar amount of sodium carbonate is 1.2 times of the molar amount of nickel ions in the oil-removed nickel sulfate solution (the nickel content is 125 g / L), the reaction temperature is controlled at 75℃, the reaction time is 120 min, pressure filtration separation is performed to obtain nickel carbonate solid and primary nickel precipitation filtrate.

[0082] Step 2, adding sodium hydroxide to the primary nickel precipitation filtrate, the molar amount of sodium hydroxide added is 2.1 times of the molar amount of nickel ions in the primary nickel precipitation filtrate (the nickel content is 5.3 g / L), the reaction temperature is 75℃, the reaction time is 60 min, pressure filtration separation is performed to obtain nickel hydroxide solid and secondary nickel precipitation filtrate.

[0083] Step 3, mixing the nickel carbonate obtained in step 1 and the nickel hydroxide obtained in step 2 according to a solid-liquid ratio of 1:3 t / m 3 Water washing 2 times. The washing water after impurity removal is recycled, and the recycling number is 10 times. After 10 times of recycling, the detection reaches the discharge concentration, and the washing water is returned to the raw material slurry section.

[0084] Step 4, acid dissolution, mixing anode solution, nickel carbonate and nickel hydroxide, the ratio of the sum of the molar amounts of sulfuric acid in the anode solution and nickel ions in the nickel carbonate and nickel hydroxide is 1.2:1, after uniform mixing, the acid dissolution temperature is 70℃, the acid dissolution time is 60 min, and a nickel-containing solution is obtained. After neutralization reaction of the secondary nickel precipitation filtrate by adding sulfuric acid, a sodium sulfate solution is obtained. The molar amount of sulfuric acid added is 1.2:1 of the sum of the molar amounts of hydroxide and carbonate in the secondary nickel precipitation filtrate. Then, filtration is performed, and the filtered sodium sulfate solution is evaporated and crystallized to prepare a sodium sulfate product. The evaporation and crystallization temperature is 140℃, and the crystallization time is 90 min.

[0085] Step 5, the nickel-containing solution is filtered to remove insoluble substances, and then the cathode solution is configured by mixing the nickel-containing solution with pure water, boric acid, anode solution and sodium sulfate to obtain a new cathode solution, the content of boric acid in the new cathode solution is controlled to be 5 g / L, the pH value is controlled to be 3.5, the content of nickel is controlled to be 85 g / L, and the concentration of sodium ions in the new cathode solution is controlled to be 25 g / L.

[0086] Step 6, after the new cathode solution is precisely filtered, the temperature of the new cathode solution is controlled to be 68℃, and then the new cathode solution enters the electrodeposition process, the current intensity in the electrodeposition process is 12000 A, the current density is 180 A / m 2 , the cathode cycle is 7d, the cell voltage is 3.6V, and high-purity electrodeposited nickel is produced.

[0087] Step 7, 10vol% of the anode solution produced after electrodeposition (the amount of the anode solution required in step 5) is removed by adding barium carbonate and black nickel, the amount of barium carbonate added is 1.1 times (in terms of molar amount) of the theoretical amount required to remove lead ions in the anode solution, and the amount of black nickel added is 1.1 times (in terms of molar amount) of the theoretical amount required for iron and cobalt in the anode solution, after the impurities are removed, the anode solution is filtered to obtain a purified anode solution, which is returned to step 5 to participate in the configuration of the new cathode solution.

[0088] The remaining anode solution is returned to the acid dissolution process of step 4 to dissolve nickel carbonate and nickel hydroxide, realizing the recycling of the anode solution.

[0089] Comparative Example 1 A method for preparing high-purity nickel by electrodeposition of nickel anode solution and recycling, comprising the following steps: Step 1, primary nickel precipitation, after mixing sodium carbonate and nickel sulfate oil-removed solution, the molar amount of sodium carbonate is 1.2 times the molar amount of nickel ions in the nickel sulfate oil-removed solution (the content of nickel is 125 g / L), the reaction temperature is controlled at 75℃, the reaction time is 120 min, and the pressure filtration separation is performed to obtain nickel carbonate solid and primary nickel precipitation filtrate.

[0090] Step 2, add sodium carbonate to the primary nickel precipitation filtrate, the molar amount of sodium carbonate added is 1.1 times the molar amount of nickel ions in the primary nickel precipitation filtrate (the content of nickel is 6.5 g / L), the reaction temperature is 75℃, the reaction time is 60 min, and the pressure filtration separation is performed to obtain nickel carbonate solid and secondary nickel precipitation filtrate.

[0091] Step 3 is the same as Example 1.

[0092] Step 4, acid dissolution, the mixed anolyte, nickel carbonate, the molar ratio of sulfuric acid in the anolyte and nickel ions in the nickel carbonate is 1.2:1, after mixing evenly, the acid dissolution temperature is 70℃, the acid dissolution time is 60min, to obtain a solution containing nickel. The secondary nickel precipitation filtrate is neutralized by adjusting the acid to obtain a sodium sulfate solution, which can be evaporated and crystallized to prepare a sodium sulfate product, the evaporation crystallization temperature is 140℃, and the crystallization time is 90min.

[0093] Steps 5-7 are the same as in Example 1.

[0094] Comparative Example 2: A method for preparing high-purity nickel by synergistic circulation of electrodeposited nickel anolyte includes the following steps: Step 1, primary nickel precipitation, mixing sodium hydroxide and nickel sulfate after oil removal, the molar amount of sodium hydroxide is 1.2 times the molar amount of nickel ions in the nickel sulfate after oil removal (nickel content is 125g / L), the reaction temperature is controlled at 75℃, the reaction time is 120min, and pressure filtration separation is performed to obtain nickel hydroxide solid and primary nickel precipitation filtrate.

[0095] Step 2, adding sodium hydroxide to the primary nickel precipitation filtrate, the molar amount of sodium hydroxide added is 1.1 times the molar amount of nickel ions in the primary nickel precipitation filtrate (nickel content is 3.8g / L), the reaction temperature is 75℃, the reaction time is 60min, and pressure filtration separation is performed to obtain nickel hydroxide solid and secondary nickel precipitation filtrate.

[0096] Step 3 is the same as in Example 1.

[0097] Step 4, acid dissolution, the mixed anolyte, nickel carbonate, the molar ratio of sulfuric acid in the anolyte and nickel ions in the nickel carbonate is 1.2:1, after mixing evenly, the acid dissolution temperature is 70℃, the acid dissolution time is 60min, to obtain a solution containing nickel. The secondary nickel precipitation filtrate is neutralized by adjusting the acid to obtain a sodium sulfate solution, which can be evaporated and crystallized to prepare a sodium sulfate product, the evaporation crystallization temperature is 140℃, and the crystallization time is 90min.

[0098] Steps 5-7 are the same as in Example 1.

[0099] Comparative Example 3: A method for preparing high-purity nickel by synergistic circulation of electrodeposited nickel anolyte includes the following steps: Step 1, primary nickel precipitation, mixing sodium hydroxide and nickel sulfate after oil removal, the molar amount of sodium hydroxide is 1.2 times the molar amount of nickel ions in the nickel sulfate after oil removal (nickel content is 125g / L), the reaction temperature is controlled at 75℃, the reaction time is 120min, and pressure filtration separation is performed to obtain nickel hydroxide solid and primary nickel precipitation filtrate.

[0100] Step 2, sodium carbonate is added to the first stage of nickel precipitation filtrate, the molar amount of sodium carbonate added is 1.1 times the molar amount of nickel ions in the first stage of nickel precipitation filtrate (nickel content is 4.3 g / L), the reaction temperature is 75℃, the reaction time is 60 min, pressure filtration separation, nickel carbonate solid and secondary nickel precipitation filtrate.

[0101] Steps 3-7 are the same as in Example 1.

[0102] Example 2: A method for preparing high-purity nickel by electrodeposition of nickel anode solution and synergistic circulation, comprising the following steps: Step 1, first stage of nickel precipitation, mixed sodium carbonate and nickel sulfate after oil removal solution, the molar amount of sodium carbonate is 1.1 times the molar amount of nickel ions in the nickel sulfate after oil removal solution (nickel content is 122 g / L), the reaction temperature is controlled at 80℃, the reaction time is 100 min, pressure filtration separation, nickel carbonate solid and first stage of nickel precipitation filtrate are obtained.

[0103] Step 2, sodium hydroxide is added to the first stage of nickel precipitation filtrate, the molar amount of sodium hydroxide added is 1.2 times the molar amount of nickel ions in the first stage of nickel precipitation filtrate (nickel content is 5.1 g / L), the reaction temperature is 80℃, the reaction time is 80 min, pressure filtration separation, nickel hydroxide solid and secondary nickel precipitation filtrate are obtained.

[0104] Step 3, the nickel carbonate obtained in step 1 and the nickel hydroxide obtained in step 2 are mixed according to a solid-liquid ratio of 1:5 t / m 3 Washed with water 2 times. The washing water after impurity removal is recycled, and the recycling number is 10 times. After 10 times of recycling, the concentration detected reaches the discharge concentration, and returns to the raw material slurry section.

[0105] Step 4, acid dissolution, mixed anode solution, nickel carbonate, nickel hydroxide, the ratio of the sum of the molar amounts of sulfuric acid in the anode solution and nickel carbonate to nickel ions in the nickel hydroxide is 1.1:1, after mixing evenly, the acid dissolution temperature is 80℃, the acid dissolution time is 40 min, and a nickel-containing solution is obtained. After neutralization reaction of the secondary nickel precipitation filtrate by adding sulfuric acid, a sodium sulfate solution is obtained. The molar amount of sulfuric acid added is 1.1:1 of the sum of the molar amounts of hydroxide and carbonate in the secondary nickel precipitation filtrate. Then filter, evaporate and crystallize the filtered sodium sulfate solution to prepare sodium sulfate product, the evaporation crystallization temperature is 135℃, and the crystallization time is 120 min.

[0106] Step 5, the nickel-containing solution is filtered to remove insoluble matter, and then the cathode solution is configured. The nickel-containing solution is mixed with pure water, boric acid, anode solution and sodium sulfate to obtain a new cathode solution. The boric acid content in the new cathode solution is 3 g / L, the pH value is 3.0, the nickel content is 76 g / L, and the sodium ion concentration in the new cathode solution is 20 g / L.

[0107] Step 6, after the cathode new solution is precisely filtered, the temperature of the cathode new solution is controlled to be 70℃, and then the cathode new solution enters the electrodeposition process, the current intensity in the electrodeposition process is 7500A, the current density is 160A / m 2 , the cathode cycle is 6d, the tank voltage is 3.3V, and high-purity electrodeposited nickel is produced.

[0108] Step 7, 8vol% of the anode solution produced after the electrodeposition (the amount of the anode solution required in step 5) is subjected to impurity removal by adding barium carbonate and black nickel, the amount of the barium carbonate added is the theoretical amount (in terms of molar amount) required for removing lead ions in the anode solution, the amount of the black nickel added is the theoretical amount (in terms of molar amount) required for the iron and cobalt in the anode solution, after the impurity removal, the anode purified solution is obtained through pressure filtration and is returned to step 5 to participate in the configuration of the cathode new solution. The remaining anode solution is returned to the acid dissolution process in step 4 to dissolve the nickel carbonate and the nickel hydroxide, so as to realize the cyclic utilization of the anode solution.

[0109] Example 3 A method for preparing high-purity nickel by electrodeposition of an anode solution in cooperation with cyclic utilization, comprising the following steps: Step 1, primary nickel precipitation, after the oil removal of the mixed sodium carbonate and nickel sulfate solution, the molar amount of the sodium carbonate is 1.5 times the molar amount of the nickel ions in the oil-removed nickel sulfate solution (the nickel content is 130g / L), the reaction temperature is controlled to be 90℃, the reaction time is 120min, pressure filtration is performed to separate, and nickel carbonate solid and primary nickel precipitation filtrate are obtained.

[0110] Step 2, sodium hydroxide is added to the primary nickel precipitation filtrate, the molar amount of the added sodium hydroxide is 2.15 times the molar amount of the nickel ions in the primary nickel precipitation filtrate (the nickel content is 6.4g / L), the reaction temperature is 90℃, the reaction time is 120min, pressure filtration is performed to separate, and nickel hydroxide solid and secondary nickel precipitation filtrate are obtained.

[0111] Step 3, the nickel carbonate obtained in step 1 and the nickel hydroxide obtained in step 2 are mixed according to a solid-liquid ratio of 1:3t / m 3 Water washing is performed twice. The washing water after the impurity removal is recycled, the recycling number is 10 times, after the 10 times of recycling, the washing water is detected to reach the discharge concentration, and is returned to the raw material slurry section.

[0112] Step 4, acid dissolution, the anode solution, nickel carbonate and nickel hydroxide are mixed, the ratio of the sum of the molar amounts of the sulfuric acid in the anode solution and the nickel ions in the nickel carbonate and the nickel hydroxide is 1.15:1, after being uniformly mixed, the acid dissolution is performed at an acid dissolution temperature of 90℃ for an acid dissolution time of 60min, and a nickel-containing solution is obtained. After the neutralization reaction of the secondary nickel precipitation filtrate by adding sulfuric acid, a sodium sulfate solution is obtained, the molar amount of the added sulfuric acid is 1.15:1 of the sum of the molar amounts of the hydroxide and the carbonate in the secondary nickel precipitation filtrate, then filtration is performed, the sodium sulfate solution after the filtration is evaporated and crystallized to prepare a sodium sulfate product, and the evaporation crystallization temperature is 150℃ and the crystallization time is 60min.

[0113] Step 5, the nickel-containing solution is filtered to remove insoluble substances, and then the cathode liquid is configured by mixing the nickel-containing solution with pure water, boric acid, anode liquid and sodium sulfate to obtain a new cathode liquid, the content of boric acid in the new cathode liquid is 10 g / L, the pH value is 5.0, the content of nickel is 92 g / L, and the concentration of sodium ions in the new cathode liquid is 30 g / L.

[0114] Step 6, after the new cathode liquid is precisely filtered, the temperature of the new cathode liquid is controlled to be 67℃, and then the new cathode liquid enters the electrodeposition process, the current intensity in the electrodeposition process is 15800 A, the current density is 190 A / m 2 , the cathode cycle is 8d, and the cell voltage is 3.8V, and high-purity electrodeposited nickel is produced.

[0115] Step 7, 15vol% of the anode liquid produced after electrodeposition (the amount of the anode liquid required in step 5) is removed by adding barium carbonate and black nickel, the amount of barium carbonate added is 1.1 times (in terms of molar amount) of the theoretical amount required to remove lead ions in the anode liquid, and the amount of black nickel added is 1.1 times (in terms of molar amount) of the theoretical amount required for iron and cobalt in the anode liquid, after removal of impurities, the anode liquid is filtered to obtain a purified anode liquid, which is returned to step 5 to participate in the configuration of the new cathode liquid. The remaining 90vol% of the anode liquid is returned to the acid dissolution process of step 4 to dissolve nickel carbonate and nickel hydroxide, realizing the recycling of the anode liquid.

[0116] The purity of the high-purity nickel and sodium sulfate prepared in Examples 1-3 is tested by ICP-OES and calculated and analyzed, as shown in Table 1 below.

[0117] Table 1 Purity of high-purity nickel and sodium sulfate prepared in Examples 1-3 and Comparative Examples 1-3 As can be seen from Table 1, the purity of the high-purity nickel obtained by electrodeposition in Examples 1-3 is all above 99.97%, and the product reaches the national standard of GB / T6516-2010 electrolytic nickel, Ni+Co≥99.96%, Co≤0.02%. The purity of sodium sulfate is all greater than 98.00%, which can indicate that the process route provided by the present application can prepare high-purity nickel and high-purity byproduct sodium sulfate.

[0118] In summary, by comparing the high-purity nickel and sodium sulfate prepared in Example 1 and Comparative Examples 1, 2 and 3, it can be shown that for the electrodeposited nickel product: Example 1 adopts the process of sodium carbonate primary nickel precipitation + sodium hydroxide secondary nickel precipitation, which realizes high-particle-size precipitation and pre-impurity removal through coarse nickel carbonate precipitation, and guarantees deep recovery through nickel hydroxide fine precipitation, the obtained precipitate has high purity and less impurities, the reaction is stable during acid dissolution and the amount of impurities dissolved is low, and the subsequent electrodeposited nickel crystallizes uniformly and the purity can reach above 99.97%.

[0119] The nickel is precipitated by sodium carbonate only in Comparative Example 1, the precipitate has high solubility, low recovery rate and high impurity entrainment, the impurity concentration of the solution after acid dissolution is high, and the nickel electrodeposition is prone to slag inclusion and insufficient purity.

[0120] The nickel is precipitated by sodium carbonate only in Comparative Example 1, the precipitate has high solubility, low recovery rate and high impurity entrainment, the impurity concentration of the solution after acid dissolution is high, and the nickel electrodeposition is prone to slag inclusion and insufficient purity.

[0121] The nickel is precipitated by sodium carbonate only in Comparative Example 1, the precipitate has high solubility, low recovery rate and high impurity entrainment, the impurity concentration of the solution after acid dissolution is high, and the nickel electrodeposition is prone to slag inclusion and insufficient purity.

[0122] For the sodium sulfate by-product, the process of Example 1 realizes step-by-step accurate removal of impurities, and the impurity content of the final filtrate is extremely low, and the purity of the sodium sulfate obtained by evaporation and crystallization can reach 98% or more.

[0123] In Comparative Example 1, the nickel is precipitated by sodium carbonate only, and the basic carbonate impurities formed by the residual Ca, Mg, Fe and Al in the filtrate are prone to entrain these impurities during evaporation and crystallization, and the purity of sodium sulfate is reduced.

[0124] In Comparative Example 2, the nickel is precipitated by sodium hydroxide only, and the colloid is prone to adsorbing Fe, Al and incompletely precipitated nickel ions, so the filtrate has high impurity concentration, and the purity of sodium sulfate is insufficient and the heavy metals may exceed the standard.

[0125] In Comparative Example 3, the order of nickel precipitation is reversed, which leads to the initial colloid entraining impurities and incomplete secondary nickel precipitation, and the residual nickel and other impurities in the filtrate are both high, so the purity of sodium sulfate is difficult to be low.

[0126] That is, the two-stage nickel precipitation process produces sodium sulfate by-products with high purity (basically reaching industrial grade), significant resource utilization benefits (reducing wastewater treatment costs and realizing waste reuse), stable and controllable yield, and smooth connection with the main process.

[0127] The above-described examples are only preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent substitutions or changes within the technical scope of the present application according to the technical solutions and concepts of the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for preparing high-purity nickel through electrowinning anolyte synergistic recycling, characterized in that, Includes the following steps: Step 1: React nickel sulfate solution with sodium carbonate to perform primary nickel precipitation, followed by solid-liquid separation to obtain nickel carbonate and primary nickel precipitation filtrate; Step 2: React the primary nickel precipitation filtrate with sodium hydroxide to perform secondary nickel precipitation, followed by solid-liquid separation to obtain nickel hydroxide and secondary nickel precipitation filtrate; Step 3: Nickel carbonate and nickel hydroxide are acid-dissolved in the anolyte after electrowinning to generate a nickel-containing solution; Step 4: Mix the nickel-containing solution with pure water, boric acid, anolyte, and sodium sulfate to prepare a new cathode solution. Electrodecompose the new cathode solution to obtain high-purity nickel.

2. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, In step 1, the molar ratio of sodium carbonate to nickel ions in the nickel sulfate solution is 1.1-1.5:1, the nickel precipitation time is 60-120 min, and the nickel precipitation temperature is 75-90℃.

3. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, In step 2, the molar ratio of sodium hydroxide to nickel ions in the primary nickel precipitation filtrate is 2.1-2.2:1, the nickel precipitation time is 60-120 min, and the nickel precipitation temperature is 75-90℃.

4. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, In step 3, the amount of anolyte added is based on the amount of sulfuric acid in it. The ratio of the molar amount of sulfuric acid to the total molar amount of nickel ions in nickel carbonate and nickel hydroxide is 1.1-1.2:

1. The acid dissolution time is 30-60 min and the acid dissolution temperature is 70-90℃.

5. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, In step 4, the boric acid content in the new cathode solution is 3-10 g / L, the nickel content is 70-100 g / L, the pH value of the new cathode solution is 3.0-5.0, and the sodium ion content is 20-30 g / L.

6. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, In step 4, during electrodeposition, the temperature of the cathode molten metal is 65-70℃, the current intensity is 7500-15800A, and the current density is 160-190A / m. 2 The cathode period is 6-8 days, and the cell voltage is 3.3-3.8V.

7. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, The anolyte after electrowinning is purified and recovered. Specifically, a portion of the anolyte is treated with a purification agent, filtered under pressure to obtain purified anolyte, and returned to step 4 for catholyte preparation. The other portion of the anolyte is returned to step 3 for acid dissolution.

8. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 7, characterized in that, The impurity remover is any one or both of barium carbonate and black nickel; the amount of barium carbonate used is: barium carbonate : lead ions in the anolyte molar ratio of 1 to 1.1 : 1; the amount of black nickel used is based on the Fe in the anolyte. 2+ and Co 2+ The quantity is used as the basis for calculation, n 黑镍 =(1~1.1)×n Fe2+ +(2~2.1)n Co2+ .

9. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, The sodium sulfate solution obtained by neutralizing the secondary nickel precipitation filtrate with sulfuric acid is then evaporated and crystallized to obtain solid particles of sodium sulfate.

10. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 1, characterized in that, The evaporation crystallization temperature is 135-150℃, and the crystallization time is 60-120 min.

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