Method for preparing high-purity nickel by synergic circulation of electrowinning nickel anode liquid

Abstract

This invention belongs to the field of nickel smelting technology and discloses a method for preparing high-purity nickel through electrowinning and synergistic recycling of nickel anolyte. The method includes: firstly, a nickel sulfate solution undergoes primary nickel precipitation with sodium carbonate, followed by solid-liquid separation to obtain nickel carbonate and a primary filtrate; secondly, the primary filtrate undergoes secondary nickel precipitation with sodium hydroxide, followed by solid-liquid separation to obtain nickel hydroxide and a secondary filtrate; the nickel carbonate and nickel hydroxide are then dissolved in the anolyte after electrowinning to generate a nickel-containing solution, which is then mixed with pure water, boric acid, anolyte, and sodium sulfate to prepare a new cathode solution, which is then electrowinning to obtain high-purity nickel. This process has significant advantages: the primary nickel precipitation uses sodium carbonate, which is suitable for large-scale nickel precipitation needs, and the product is easy to filter and inexpensive; the secondary nickel precipitation uses sodium hydroxide, achieving deep nickel precipitation with a small dosage, avoiding the difficulty in filtration; the pre-precipitation nickel precipitation process can intercept impurities, balancing impurity removal and separation efficiency, and significantly reducing overall production costs.

Description

Technical Field

[0001] This invention belongs to the field of nickel material smelting technology, and relates to a process for preparing high-purity nickel, specifically a method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte. Background Technology

[0002] Nickel is widely used in stainless steel, batteries, electroplating, alloys, and other fields. With the rapid development of the new energy industry, especially the surge in demand for high-purity nickel from power batteries, nickel smelting and production technologies are constantly being innovated. The traditional sulfate-based electrowinning nickel production process mainly involves leaching, purification, and electrowinning steps to prepare metallic nickel.

[0003] In traditional processes, the anolyte after nickel electrolysis is typically recycled by dividing it into three parts: one part is used for nickel immersion, one part serves as an acid solvent for the immersion product, and the other part directly participates in the preparation of the catholyte. This process suffers from low nickel recovery and high production costs. Furthermore, auxiliary materials such as boric acid cannot be effectively recycled within the system and must be added in precise quantities each time, resulting in significant consumption. In addition, the recovery and utilization rates of byproducts such as sodium sulfate are low, failing to achieve high-value resource utilization. The various production stages are not efficiently connected, leading to low overall production efficiency. Summary of the Invention

[0004] In view of the defects and deficiencies of the existing technology, firstly, the present invention provides a method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte; secondly, the present invention provides a high-purity nickel.

[0005] In a first aspect, the present invention provides a method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte, comprising the following steps:

[0006] 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;

[0007] 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;

[0008] Step 3: Nickel carbonate and nickel hydroxide are dissolved in acid using the anolyte after electrowinning to generate a nickel-containing solution;

[0009] 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.

[0010] 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.

[0011] Preferably, the anolyte mainly contains nickel sulfate and sulfuric acid, with a nickel content of 60-65 g / L, a sulfuric acid content of 42-50 g / L, and impurities such as copper, iron, cobalt, lead, manganese, and arsenic at a content of 4-10 ppm.

[0012] Preferably, 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℃.

[0013] Preferably, 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℃.

[0014] Preferably, both nickel carbonate and nickel hydroxide obtained in step 1 are washed with water to remove impurities, and the washing is performed 2 to 3 times.

[0015] Further optimization involves recycling the wash water after water washing to remove impurities. After multiple uses, the COD, sulfide, and other impurity ions in the wash water increase, so it is returned to the raw material pulping section.

[0016] Further optimization involves 8-10 cycles of washing water, with a solid-liquid ratio of 1:3~5 t / m during washing. 3 .

[0017] Preferably, in step 3, the amount of anolyte added is based on the amount of sulfuric acid therein, 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℃.

[0018] Preferably, in step 4, the boric acid content in the new cathode solution is 3-10 g / L, the nickel content in the new cathode solution 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.

[0019] Preferably, in step 4, during electrodeposition, the temperature of the cathode molten metal is 65-70°C, 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.

[0020] Preferably, the anolyte after electrowinning is purified and recovered. Specifically, a portion of the anolyte is purified by adding a purification agent, and after pressure filtration, the purified anolyte is returned to step 4 to participate in the preparation of the catholyte; the other portion of the anolyte is returned to step 3 for acid dissolution.

[0021] Further preferred, the impurity removal agent is any one or both of barium carbonate (BaCO3) and black nickel (NiOOH).

[0022] Further optimization involves using barium carbonate in a molar ratio of barium carbonate to lead ions in the anolyte of 1 to 1.1:1.

[0023] Further optimization involves using black nickel in an amount equal to the Fe content 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 Co3+

[0024] Preferably, a sodium sulfate solution is obtained by adding sulfuric acid to the secondary nickel precipitation filtrate for neutralization reaction, followed by evaporation and crystallization to obtain solid particles of sodium sulfate.

[0025] Further optimization involves setting the evaporation and crystallization temperature to 135-150℃ and the crystallization time to 60-120 min.

[0026] Further preferred, the ratio of the molar amount of added sulfuric acid to the sum of the molar amounts of hydroxide and carbonate ions in the secondary nickel precipitation filtrate is 1.1-1.2:1.

[0027] Preferably, the solid-liquid separation in both steps 1 and 2 is performed using a pressure filtration process.

[0028] Preferably, the nickel-containing solution obtained in step 3 is subjected to pressure filtration separation treatment.

[0029] Preferably, the cathode solution prepared in step 4 undergoes precision filtration.

[0030] Secondly, the present invention provides a high-purity nickel, which is prepared by the above-described method, wherein the purity of the high-purity nickel is greater than 99.97%.

[0031] Compared with the prior art, one or more technical solutions provided by the present invention have at least one of the following beneficial effects:

[0032] (1) The reaction rate of nickel precipitation using sodium carbonate is slow, and the precipitate has a large particle size, which is easy to filter. The nickel hydroxide precipitate formed by sodium hydroxide precipitation is easy to form a colloidal substance that is difficult to pass through. Based on this, sodium carbonate is used in the first stage of nickel precipitation to meet the demand for a large amount of nickel precipitation, and its product is easy to filter. Sodium hydroxide is used in the second stage to achieve deep nickel precipitation with a small amount, avoiding its difficult-to-filter defect. Combined with the pre-precipitation nickel precipitation process to intercept impurities, it takes into account both the impurity removal effect and separation efficiency. In addition, the price of sodium carbonate is lower than that of sodium hydroxide. The reagent consumption of the first stage of nickel precipitation is large, and the use of sodium carbonate is conducive to controlling costs. The reagent consumption of the second stage of nickel precipitation is small, and the amount of sodium hydroxide used is small, which can reduce costs.

[0033] (2) The method for preparing high-purity nickel provided by the present invention has the advantages of short process, high degree of continuity and high resource utilization.

[0034] (3) Closed-loop utilization of resources: The efficient recycling of anode liquid and washing water significantly reduces the consumption of new water and material loss, thus realizing the closed-loop utilization of resources.

[0035] (4) High-value utilization of by-products: The sodium sulfate solution after acidification of the secondary nickel precipitation filtrate has high purity and can be used to prepare sodium sulfate products through evaporation and crystallization, thus realizing the high-value utilization of by-products.

[0036] (5) Effective control of impurities: Impurity removal processes (water washing and anolyte removal) are set up in multiple processes to effectively control the impurity content in the system and effectively improve the purity of electrolytic nickel and sodium sulfate products, thereby effectively ensuring product quality.

[0037] (6) Production energy consumption is reduced. Boric acid is recycled in a closed loop in the system. Only the first addition is required, and subsequent production basically does not require replenishment, which reduces production costs.

[0038] (7) Environmentally friendly, the recycling of washing water and the high-value utilization of by-products reduce wastewater discharge and environmental pollution, which meets the requirements of green production. Attached Figure Description

[0039] Figure 1 The process flow diagram is provided by the present invention for the method of preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte. Detailed Implementation

[0040] The present invention provides the following specific technical solutions.

[0041] In a first aspect, the present invention provides a method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte, comprising the following steps:

[0042] 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;

[0043] 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;

[0044] Step 3: Nickel carbonate and nickel hydroxide are dissolved in acid using the anolyte after electrowinning to generate a nickel-containing solution;

[0045] Step 4: Mix the nickel-containing solution with pure water, boric acid solution, anolyte, and sodium sulfate solution to prepare a new cathode solution. Electrodecompose the new cathode solution to obtain high-purity nickel.

[0046] 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.

[0047] The main chemical reaction equations in the above process are as follows:

[0048] Primary nickel plating:

[0049] NiSO4 + Na2CO3 = NiCO3↓ + Na2SO4

[0050] Secondary nickel plating:

[0051] NiSO4 + 2NaOH = Ni(OH)2↓ + Na2SO4

[0052] Acid solubility:

[0053] NiCO3 + H2SO4 = NiSO4 + CO2↑ + H2O

[0054] Ni(OH)₂ + H₂SO₄ = NiSO₄ + 2H₂O

[0055] Nickel electrolytic deposition:

[0056] Ni 2+ +2e - =Ni (cathode)

[0057] 2H2O-4e - =O2↑+4H + (anode)

[0058] 2Ni 2+ +2H₂O=2Ni+O₂↑+4H + (Overall reaction)

[0059] 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.

[0060] In practical applications, the oil removal process is as follows: (1) First, adjust the pH of the nickel sulfate solution to a stable range of 3-5 (if it deviates, use dilute sulfuric acid or weak alkali to calibrate) to avoid pH fluctuations affecting the efficiency of subsequent oil removal agents. At the same time, heat the solution to 40-60℃ to reduce the viscosity of the oil phase and promote the aggregation of oil droplets; (2) Add a non-ionic demulsifier (such as polyoxyethylene polyoxypropylene ether) suitable for a weak acid system to the solution to destroy the oil-water emulsion system and make the tiny oil droplets aggregate into large oil droplets. Activated carbon adsorption can also be used to adsorb dispersed oil and some organic impurities using the porous structure of activated carbon; (3) Use pressure filtration or air flotation separation process to separate oil residue from the solution. Pressure filtration can retain activated carbon and oil sludge flocs. Air flotation method uses microbubbles to carry oil droplets to the surface to form a scum layer for scraping, and finally obtains a refined nickel sulfate solution with an oil content of 3-10 ppm.

[0061] Degreasing treatment can prevent oil from being trapped by nickel carbonate and nickel hydroxide precipitates, improving the purity of nickel-based precipitates and providing high-quality raw materials for subsequent acid dissolution; it can prevent oil from entering the electrowinning process, avoiding the formation of an oil film on the cathode surface, ensuring the surface quality of high-purity nickel and the efficiency of electrowinning current; it can reduce the adhesion and blockage of oil on equipment, extend equipment life, and reduce operation and maintenance costs; and it can work in conjunction with subsequent water washing and other processes to intercept organic impurities in advance, which is in line with the overall process logic of front-end impurity control.

[0062] Preferably, the anolyte mainly contains nickel sulfate and sulfuric acid, with a nickel content of 60-65 g / L, a sulfuric acid content of 42-50 g / L, and impurities such as copper, iron, cobalt, lead, manganese, and arsenic at a content of 4-10 ppm.

[0063] Preferably, 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℃.

[0064] The optimized process parameters for the primary nickel plating step 1 offer significant technical advantages. The molar ratio of sodium carbonate to nickel ions is controlled at 1.1-1.5:1, ensuring sufficient nickel ion precipitation without waste due to excessive reagent usage, thus achieving a balance between plating efficiency and raw material cost. The reaction time of 60-120 minutes and the plating temperature of 75-90℃ are well-suited to the reaction characteristics of sodium carbonate, promoting the full growth of nickel carbonate grains and forming large-particle precipitates. This significantly reduces filtration difficulty, improves solid-liquid separation efficiency, and minimizes the probability of impurities being carried over into the precipitate, ensuring high purity of the nickel carbonate. Under these parameters, the primary nickel plating reaction rate is moderate, without issues such as localized over-alkali treatment or fine grain fragmentation, providing high-quality raw materials for subsequent secondary nickel plating and anolyte acid dissolution processes, laying a solid foundation for the stable preparation of the final high-purity nickel.

[0065] Preferably, 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℃.

[0066] The optimized process parameters for the secondary nickel plating in step 2 offer significant technical advantages. The molar ratio of sodium hydroxide to nickel ions in the primary nickel plating filtrate is controlled at 2.1-2.2:1. This low excess ratio ensures deep precipitation of residual nickel ions in the filtrate while avoiding excessively high pH levels due to excessive alkali, thus reducing the formation of colloidal nickel hydroxide. Simultaneously, it minimizes reagent consumption, meeting the requirement of low reagent consumption in the secondary nickel plating process. A reaction time of 60-120 minutes and a nickel plating temperature of 75-90℃ promote the orderly growth of nickel hydroxide grains, mitigating its tendency to form a gel and hindering filtration, improving solid-liquid separation efficiency, and reducing the probability of impurities entrained in the precipitate, ensuring the purity of the nickel hydroxide. The secondary nickel plating parameters provide a high-purity nickel source for subsequent anolyte acid dissolution and high-purity nickel electrowinning, contributing to efficient nickel recovery and product quality control throughout the process.

[0067] Preferably, both nickel carbonate and nickel hydroxide obtained in step 1 are washed with water to remove impurities, and the washing is performed 2 to 3 times.

[0068] Further optimization involves recycling the wash water after water washing and impurity removal. If, after multiple uses, impurity ions such as COD and thiosulfates reach the discharge concentration, the water is returned to the raw material pulping section.

[0069] Washing effectively removes soluble salts, unreacted reagents, thiosulfate, COD, and other impurities trapped on the surface and in the pores of both types of nickel precipitates, significantly improving the purity of the precipitates and laying a raw material foundation for the subsequent acid dissolution of the anolyte to prepare a high-purity nickel-containing solution. Secondly, the recycling of wash water can significantly reduce the consumption of fresh water and reduce wastewater treatment costs, meeting the requirements of green chemical production. Finally, the wash water with excessive impurities is returned to the raw material slurry chemical section, which not only avoids the environmental pressure of wastewater discharge but also recovers trace nickel resources from the wash water. At the same time, it achieves centralized pretreatment of impurities, preventing them from entering the downstream electrolysis system and affecting the quality of the final high-purity nickel product.

[0070] The raw material pulping stage is: the nickel sulfate deoiled liquid obtained by leaching, extraction purification, and deoiling of nickel-containing minerals or intermediates (such as nickel concentrate, high-nickel matte, nickel briquettes, nickel hydroxide, nickel carbonate, etc.). The nickel-containing raw materials need to be pulped before leaching, which is the raw material pulping stage.

[0071] Further optimization involves 8-10 cycles of washing water, with a solid-liquid ratio of 1:3~5 t / m during washing. 3 .

[0072] Preferably, in step 3, the ratio of the mass of the anolyte to the sum of the masses of nickel carbonate and nickel hydroxide is 10-50:1, the acid dissolution time is 30-60 min, and the acid dissolution temperature is 70-90℃.

[0073] The high-purity nickel carbonate and nickel hydroxide obtained from acid dissolution and the preceding primary and secondary nickel precipitation processes provide a low-impurity nickel source for acid dissolution. The mild reaction conditions of 70-90℃ and 30-60 minutes for acid dissolution are well-suited to the dissolution characteristics of the high-purity nickel precipitate, ensuring sufficient dissolution without causing excessive leaching of small amounts of residual impurities from the precipitate due to violent reactions. This continues the "front-end impurity control" process logic, guaranteeing the purity of the nickel-containing solution. Furthermore, the use of the anolyte from electrowinning as the acid source in acid dissolution achieves resource recycling of the anolyte, reducing the cost of purchasing new acid. The nickel-containing solution obtained from acid dissolution can be directly used to prepare new cathode solutions without additional complex purification, seamlessly connecting to the subsequent electrowinning process. Simultaneously, the anolyte is quantitatively returned to the acid dissolution process, achieving a synergistic effect of "acid dissolution + nickel replenishment," precisely controlling the nickel concentration and acidity of the nickel-containing solution. This provides a suitable raw material system for the stable preparation of new cathode solutions and the efficient electrowinning of high-purity nickel, forming a closed-loop process of "anolyte recycling - acid dissolution - electrowinning."

[0074] Preferably, in step 4, the boric acid content in the new cathode solution is 3-10 g / L, the nickel content in the new cathode solution is 70-100 g / L, the sodium ion concentration in the new cathode solution is 20-30 g / L, and the pH value of the new cathode solution is 3.0-5.0.

[0075] The optimal parameters of the cathode electrolyte can comprehensively ensure the stability of high-purity nickel electrodeposition and product quality. Boric acid of 3-10 g / L can effectively buffer the pH of the system, avoid large pH fluctuations near the cathode that cause impurity precipitation, and also optimize the nickel crystal morphology. A nickel content of 70-100 g / L is within the suitable range for electrodeposition, which can ensure electrodeposition efficiency and prevent coarse crystals from affecting purity. A pH value of 3.0-5.0 can inhibit preferential discharge of hydrogen ions, improve current efficiency, and work with boric acid to maintain system stability, ultimately helping to produce high-purity, high-quality electrodeposited nickel.

[0076] Preferably, in step 4, during electrodeposition, the temperature of the cathode molten metal is 65-70°C, 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.

[0077] The optimal parameters for electrodeposition balance the efficiency and quality of high-purity nickel production: 160-190 A / m 2 The current density and 7500-15800A current intensity ensure uniform and efficient nickel ion deposition, avoiding coarse grains or slow deposition; the 6-8d cathode cycle promotes dense nickel layer growth, balancing production capacity and purity; the 3.3-3.8V cell voltage suppresses side reactions and hydrogen ion discharge, improves current efficiency, and reduces power consumption. The overall parameters work together to ensure a stable and controllable electrodeposition process, helping to produce high-grade, high-purity nickel.

[0078] Preferably, the anolyte after electrowinning is purified and recovered. Specifically, a portion of the anolyte is purified by adding a purification agent, and after pressure filtration, the purified anolyte is returned to step 4 to participate in the preparation of the catholyte; the other portion of the anolyte is returned to step 3 for acid dissolution.

[0079] A portion of the anolyte is purified with a cleaning agent and returned to step 4 to prepare the cathode solution. This removes impurities accumulated during the electrodeposition process, ensuring the purity of the new cathode solution and preventing any impact on the quality of high-purity nickel. The other portion is directly recycled back to step 3 for acid dissolution, achieving resource recycling of the anolyte, reducing the amount of new acid added, and lowering raw material costs. This design constructs a closed-loop utilization system for the anolyte, which strengthens impurity control throughout the entire process, improves resource utilization, and balances product quality with process economy, aligning with the green and circular chemical production concept.

[0080] Further preferred, the impurity removal agent is any one or both of barium carbonate (BaCO3) and black nickel (NiOOH).

[0081] The composition of the virgin cathode solution has strict requirements: nickel content must be controlled at 70-100 g / L, boric acid at 3-10 g / L, and pH at 3.0-5.0. The sulfate concentration must only meet the minimum requirements for charge balance with nickel and sodium ions and maintaining the solution's conductivity. However, due to the continuous accumulation of sulfate in the anolyte, its concentration will be significantly higher than the optimal concentration for the virgin cathode solution. Therefore, the sulfate in the anolyte is in excess relative to the requirements for preparing the cathode solution. Using barium carbonate for purification can simultaneously achieve deep removal of excess sulfate and lead ions from the anolyte, resulting in a significant dual purification effect. Barium carbonate reacts with sulfate in the anolyte to produce barium sulfate. The resulting barium sulfate co-precipitates with lead ions, preventing lead from affecting the purity of the nickel in the cathode. The resulting particulate precipitate is easily filtered and separated, and the carbonate is converted into carbon dioxide and water in the acidic system, without introducing secondary pollution. The process is a closed loop, using inexpensive raw materials with precise and controllable dosage, combining economic efficiency and environmental friendliness. The preferred amount of barium carbonate is 1 to 1.1 molar ratio of barium carbonate to lead ions in the anolyte.

[0082] Black nickel was chosen as the impurity remover, utilizing its oxidizing properties to remove Fe. 2+ Oxidized to Fe 3+ Co 2+ Oxidized to Co 3+ The oxidized ions form hydroxide precipitates that are removed to prevent them from affecting the deposition of nickel at the cathode during electrolysis. Furthermore, the black nickel itself is converted into Ni after the oxidation reaction. 2+ It can be used as a nickel source in subsequent electrodeposition without introducing new harmful impurities into the anolyte, thus ensuring the quality of the cathode nickel. The amount of black nickel used is determined by the Fe content 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+ .

[0083] In practical applications, barium hydroxide can be used to replace barium carbonate for removing lead ions, but its effect is not as good as that of barium carbonate. Lead hydroxide reacts directly with lead ions to produce lead hydroxide precipitate, which cannot achieve the dual purification effect of barium carbonate.

[0084] Preferably, the anolyte after electrowinning meets the acid dissolution requirements in step 3, and the remaining anolyte is used in step 4 to participate in the preparation of the new cathode solution.

[0085] Further preferred, the amount of anolyte after electrowinning in step 3 is 85~95 vol%, and the remaining 5~15 vol% of the anolyte after electrowinning enters step 4 to participate in the preparation of new cathode solution.

[0086] Preferably, the sodium sulfate solution obtained after neutralizing the secondary nickel precipitation filtrate with acid is then evaporated and crystallized to obtain solid particles of sodium sulfate.

[0087] By treating the sodium sulfate-containing filtrate generated during the nickel plating stage, the waste liquid is converted into reusable or exportable sodium sulfate solid, achieving efficient recovery of byproducts and improving the overall resource utilization rate of the process. Simultaneously, acid neutralization eliminates the alkalinity of the filtrate, preventing equipment corrosion caused by direct evaporation 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 the environmental risks of waste liquid discharge and adding extra economic benefits to the process, aligning with the production concepts of green chemistry and resource recycling.

[0088] Further optimization involves setting the evaporation and crystallization temperature to 135-150℃ and the crystallization time to 60-120 min.

[0089] The above-mentioned optimized parameters can be adapted to the crystallization characteristics of sodium sulfate, promote the rapid and complete precipitation of sodium sulfate, form solid particles with uniform particle size, improve crystallization efficiency and product quality; at the same time, these parameters can shorten the crystallization cycle, reduce energy consumption, reduce the risk of equipment corrosion, and realize the efficient resource recovery of sodium sulfate in waste liquid, taking into account both environmental and economic benefits.

[0090] Further preferred, the molar amount of sulfuric acid is the ratio of the sum of the molar amounts of hydroxide and carbonate ions in the secondary nickel precipitation filtrate to 1.1-1.2:1.

[0091] The solution after nickel precipitation is alkaline, so sulfuric acid is added to adjust the acidity of the filtrate to neutralize the excess alkali and completely convert the residual carbonate ions into carbon dioxide, thus preventing the formation of impurities such as sodium bicarbonate and sodium carbonate 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 impurity entrainment in the crystallization product, promote the rapid precipitation of sodium sulfate and the formation of uniform particles, and improve crystallization efficiency and product yield.

[0092] Preferably, the solid-liquid separation in both steps 1 and 2 is performed using a pressure filtration process.

[0093] Preferably, the nickel-containing solution obtained in step 3 is subjected to pressure filtration separation.

[0094] The strong solid-liquid separation capability of pressure filtration can efficiently retain the nickel carbonate and nickel hydroxide solid phases in the nickel precipitation stage, as well as fine impurity particles in the nickel-containing solution and cathode fresh liquid, ensuring the purity of the feed solution at each stage and laying a solid foundation for the preparation of high-purity nickel. At the same time, pressure filtration has high separation efficiency and stable operation, which can adapt to the needs of continuous production, reduce process time, and balance product quality and process operation efficiency.

[0095] Preferably, the cathode solution prepared in step 4 undergoes precision filtration.

[0096] In practical applications, to ensure the quality of the new cathode solution, precision filtration is performed to remove impurities from the solution. A precision filter is used to filter the new cathode solution.

[0097] Secondly, the present invention provides a high-purity nickel, which is prepared by the above-described method, wherein the purity of the high-purity nickel is greater than 99.97%.

[0098] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0099] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0100] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0101] Figure 1 The process flow diagram is provided by the present invention for the method of preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte.

[0102] In step 1 of a specific embodiment of the present invention, the nickel content of the nickel sulfate solution in the degreasing solution is 70-130 g / L, the content of impurities such as copper, iron, lead, manganese, and arsenic is 10-50 ppm, the pH value is 3-5, and the oil content is 3-10 ppm. The anolyte used in step 4 mainly contains nickel sulfate and sulfuric acid, with a nickel content of 60-65 g / L, a sulfuric acid content of 42-50 g / L, and the content of impurities such as copper, iron, cobalt, lead, manganese, and arsenic is 4-10 ppm.

[0103] Example 1:

[0104] A method for preparing high-purity nickel through synergistic recycling of electrolytic nickel anolyte includes the following steps:

[0105] Step 1, primary nickel precipitation: Mix sodium carbonate and nickel sulfate degreasing solution. The molar amount of sodium carbonate is 1.2 times the molar amount of nickel ions in the nickel sulfate degreasing solution (nickel content is 125 g / L). The reaction temperature is controlled at 75℃ and the reaction time is 120 min. After pressure filtration, nickel carbonate solid and primary nickel precipitation filtrate are obtained.

[0106] Step 2: Add sodium hydroxide to the primary nickel precipitate filtrate. The molar amount of sodium hydroxide added is 2.1 times the molar amount of nickel ions in the primary nickel precipitate filtrate (nickel content is 5.3 g / L). The reaction temperature is 75℃ and the reaction time is 60 min. Separate by pressure filtration to obtain solid nickel hydroxide and secondary nickel precipitate filtrate.

[0107] Step 3: Mix the nickel carbonate obtained in Step 1 and the nickel hydroxide obtained in Step 2 at a solid-liquid ratio of 1:3 t / m 3 The material is washed twice. The wash water after impurity removal is recycled 10 times. After 10 cycles, the water is tested to reach the discharge concentration and then returned to the raw material pulping section.

[0108] Step 4: Acid dissolution. Mix the anolyte, nickel carbonate, and nickel hydroxide. The molar ratio of sulfuric acid in the anolyte to the sum of the molar amounts of nickel ions in nickel carbonate and nickel hydroxide is 1.2:1. After thorough mixing, react at an acid dissolution temperature of 70℃ for 60 minutes to obtain a nickel-containing solution. Add sulfuric acid to the secondary nickel precipitation filtrate for neutralization to obtain a sodium sulfate solution. The molar ratio of sulfuric acid added is 1.2:1, matching the sum of the molar amounts of hydroxide and carbonate ions in the secondary nickel precipitation filtrate. Then filter and evaporate the filtered sodium sulfate solution to prepare the sodium sulfate product. The evaporation and crystallization temperature is 140℃, and the crystallization time is 90 minutes.

[0109] Step 5: The nickel-containing solution is filtered to remove insoluble matter. Then, the cathode solution is prepared by mixing the nickel-containing solution with pure water, boric acid, anolyte, and sodium sulfate to obtain a new cathode solution. The boric acid content in the new cathode solution is controlled at 5 g / L, the pH value is 3.5, the nickel content is 85 g / L, and the sodium ion concentration in the new cathode solution is 25 g / L.

[0110] Step 6: After precision filtration, the temperature of the cathode solution is controlled at 68°C, and then it enters the electrowinning process. During electrowinning, the current intensity is 12000A and the current density is 180A / m. 2 The cathode cycle is 7 days, the cell voltage is 3.6V, and high-purity electrolytic nickel is produced.

[0111] Step 7: The 10 vol% anolyte produced after electrowinning (the amount of anolyte required in Step 5) is purified by adding barium carbonate and black nickel. The amount of barium carbonate added is 1.1 times (in molar terms) of the theoretical amount required to remove lead ions from the anolyte, and the amount of black nickel added is 1.1 times (in molar terms) of the theoretical amount required to remove iron and cobalt from the anolyte. After purification, the anolyte is filtered by pressure to obtain the purified anolyte, which is then returned to Step 5 to participate in the preparation of the new cathode solution.

[0112] The remaining anolyte is returned to the acid dissolution process in step 4 to dissolve nickel carbonate and nickel hydroxide, thus achieving the recycling of the anolyte.

[0113] Comparative Example 1:

[0114] A method for preparing high-purity nickel through synergistic recycling of electrolytic nickel anolyte includes the following steps:

[0115] Step 1, primary nickel precipitation: Mix sodium carbonate and nickel sulfate degreasing solution. The molar amount of sodium carbonate is 1.2 times the molar amount of nickel ions in the nickel sulfate degreasing solution (nickel content is 125 g / L). The reaction temperature is controlled at 75℃ and the reaction time is 120 min. After pressure filtration, nickel carbonate solid and primary nickel precipitation filtrate are obtained.

[0116] 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 (nickel content is 6.5 g / L). The reaction temperature is 75℃ and the reaction time is 60 min. Separate by pressure filtration to obtain solid nickel carbonate and secondary nickel precipitation filtrate.

[0117] Step 3 is the same as in Example 1.

[0118] Step 4: Acid dissolution. Mix the anolyte and nickel carbonate. The molar ratio of sulfuric acid in the anolyte to nickel ions in the nickel carbonate is 1.2:1. After thorough mixing, react at an acid dissolution temperature of 70℃ for 60 minutes to obtain a nickel-containing solution. The secondary nickel precipitation filtrate is neutralized with acid to obtain a sodium sulfate solution, which can be evaporated and crystallized to prepare sodium sulfate product. The evaporation and crystallization temperature is 140℃, and the crystallization time is 90 minutes.

[0119] Steps 5-7 are the same as in Example 1.

[0120] Comparative Example 2:

[0121] A method for preparing high-purity nickel through synergistic recycling of electrolytic nickel anolyte includes the following steps:

[0122] Step 1, primary nickel precipitation: Mix sodium hydroxide and nickel sulfate degreasing solution. The molar amount of sodium hydroxide is 1.2 times the molar amount of nickel ions in the nickel sulfate degreasing solution (nickel content is 125 g / L). The reaction temperature is controlled at 75℃ and the reaction time is 120 min. After pressure filtration, nickel hydroxide solid and primary nickel precipitation filtrate are obtained.

[0123] Step 2: Add sodium hydroxide to the primary nickel precipitate filtrate. The molar amount of sodium hydroxide added is 1.1 times the molar amount of nickel ions in the primary nickel precipitate filtrate (nickel content is 3.8 g / L). The reaction temperature is 75℃ and the reaction time is 60 min. Separate by pressure filtration to obtain solid nickel hydroxide and secondary nickel precipitate filtrate.

[0124] Step 3 is the same as in Example 1.

[0125] Step 4: Acid dissolution. Mix the anolyte and nickel hydroxide. The molar ratio of sulfuric acid in the anolyte to nickel ions in the nickel hydroxide is 1.2:1. After thorough mixing, react at an acid dissolution temperature of 70℃ for 60 minutes to obtain a nickel-containing solution. The secondary nickel precipitation filtrate is neutralized with acid to obtain a sodium sulfate solution, which can be evaporated and crystallized to prepare sodium sulfate product. The evaporation and crystallization temperature is 140℃, and the crystallization time is 90 minutes.

[0126] Steps 5-7 are the same as in Example 1.

[0127] Comparative Example 3:

[0128] A method for preparing high-purity nickel through synergistic recycling of electrolytic nickel anolyte includes the following steps:

[0129] Step 1, primary nickel precipitation: Mix sodium hydroxide and nickel sulfate degreasing solution. The molar amount of sodium hydroxide is 1.2 times the molar amount of nickel ions in the nickel sulfate degreasing solution (nickel content is 125 g / L). The reaction temperature is controlled at 75℃ and the reaction time is 120 min. After pressure filtration, nickel hydroxide solid and primary nickel precipitation filtrate are obtained.

[0130] 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 (nickel content is 4.3 g / L). The reaction temperature is 75℃ and the reaction time is 60 min. Separate by pressure filtration to obtain solid nickel carbonate and secondary nickel precipitation filtrate.

[0131] Steps 3 to 7 are the same as in Example 1.

[0132] Example 2:

[0133] A method for preparing high-purity nickel through synergistic recycling of electrolytic nickel anolyte includes the following steps:

[0134] Step 1, primary nickel precipitation: Mix sodium carbonate and nickel sulfate degreasing solution. The molar amount of sodium carbonate is 1.1 times the molar amount of nickel ions in the nickel sulfate degreasing solution (nickel content is 122 g / L). The reaction temperature is controlled at 80℃ and the reaction time is 100 min. After pressure filtration, nickel carbonate solid and primary nickel precipitation filtrate are obtained.

[0135] Step 2: Add sodium hydroxide to the primary nickel precipitate filtrate. The molar amount of sodium hydroxide added is 1.2 times the molar amount of nickel ions in the primary nickel precipitate filtrate (nickel content is 5.1 g / L). The reaction temperature is 80℃ and the reaction time is 80 min. Separate by pressure filtration to obtain solid nickel hydroxide and secondary nickel precipitate filtrate.

[0136] Step 3: Mix the nickel carbonate obtained in Step 1 and the nickel hydroxide obtained in Step 2 at a solid-liquid ratio of 1:5t / m 3The material is washed twice. The wash water after impurity removal is recycled 10 times. After 10 cycles, the water is tested to reach the discharge concentration and then returned to the raw material pulping section.

[0137] Step 4: Acid dissolution. Mix the anolyte, nickel carbonate, and nickel hydroxide. The molar ratio of sulfuric acid in the anolyte to the sum of the molar amounts of nickel ions in nickel carbonate and nickel hydroxide is 1.1:1. After thorough mixing, react at an acid dissolution temperature of 80℃ for 40 minutes to obtain a nickel-containing solution. Add sulfuric acid to the secondary nickel precipitation filtrate for neutralization to obtain a sodium sulfate solution. The molar ratio of sulfuric acid added is 1.1:1, matching the sum of the molar amounts of hydroxide and carbonate ions in the secondary nickel precipitation filtrate. Then filter and evaporate the filtered sodium sulfate solution to prepare the sodium sulfate product. The evaporation and crystallization temperature is 135℃, and the crystallization time is 120 minutes.

[0138] Step 5: The nickel-containing solution is filtered to remove insoluble matter. Then, the cathode solution is prepared by mixing the nickel-containing solution with pure water, boric acid, anolyte, and sodium sulfate to obtain a new cathode solution. The new cathode solution has a boric acid content of 3 g / L, a pH value of 3.0, a nickel content of 76 g / L, and a sodium ion concentration of 20 g / L.

[0139] Step 6: After precision filtration, the temperature of the cathodic flux is controlled at 70°C, and then it enters the electrowinning process. During electrowinning, the current intensity is 7500A and the current density is 160A / m. 2 The cathode cycle is 6 days, the cell voltage is 3.3V, and high-purity electrolytic nickel is produced.

[0140] Step 7: The 8 vol% anolyte produced after electrowinning (the amount of anolyte required in Step 5) is purified by adding barium carbonate and black nickel. The amount of barium carbonate added is the theoretical amount (in molar quantities) required to remove lead ions from the anolyte, and the amount of black nickel added is the theoretical amount (in molar quantities) required to remove iron and cobalt from the anolyte. After purification, the anolyte is filtered to obtain the purified anolyte, which is returned to Step 5 to participate in the preparation of the new cathode solution. The remaining anolyte is returned to the acid dissolution process in Step 4 to dissolve nickel carbonate and nickel hydroxide, thus achieving the recycling of the anolyte.

[0141] Example 3:

[0142] A method for preparing high-purity nickel through synergistic recycling of electrolytic nickel anolyte includes the following steps:

[0143] Step 1, primary nickel precipitation: Mix sodium carbonate and nickel sulfate degreasing solution. The molar amount of sodium carbonate is 1.5 times the molar amount of nickel ions in the nickel sulfate degreasing solution (nickel content is 130 g / L). The reaction temperature is controlled at 90℃ and the reaction time is 120 min. After pressure filtration, nickel carbonate solid and primary nickel precipitation filtrate are obtained.

[0144] Step 2: Add sodium hydroxide to the primary nickel precipitate filtrate. The molar amount of sodium hydroxide added is 2.15 times the molar amount of nickel ions in the primary nickel precipitate filtrate (nickel content is 6.4 g / L). The reaction temperature is 90℃ and the reaction time is 120 min. Separate by pressure filtration to obtain solid nickel hydroxide and secondary nickel precipitate filtrate.

[0145] Step 3: Mix the nickel carbonate obtained in Step 1 and the nickel hydroxide obtained in Step 2 at a solid-liquid ratio of 1:3 t / m 3 The material is washed twice. The wash water after impurity removal is recycled 10 times. After 10 cycles, the water is tested to reach the discharge concentration and then returned to the raw material pulping section.

[0146] Step 4: Acid dissolution. Mix the anolyte, nickel carbonate, and nickel hydroxide. The molar ratio of sulfuric acid in the anolyte to the sum of the molar amounts of nickel ions in nickel carbonate and nickel hydroxide is 1.15:1. After thorough mixing, react at an acid dissolution temperature of 90℃ for 60 minutes to obtain a nickel-containing solution. Add sulfuric acid to the secondary nickel precipitation filtrate for neutralization to obtain a sodium sulfate solution. The molar ratio of sulfuric acid added is 1.15:1, the sum of the molar amounts of hydroxide and carbonate ions in the secondary nickel precipitation filtrate. Then filter and evaporate the filtered sodium sulfate solution to prepare the sodium sulfate product. The evaporation and crystallization temperature is 150℃, and the crystallization time is 60 minutes.

[0147] Step 5: The nickel-containing solution is filtered to remove insoluble matter. Then, the cathode solution is prepared by mixing the nickel-containing solution with pure water, boric acid, anolyte, and sodium sulfate to obtain a new cathode solution. The new cathode solution has a boric acid content of 10 g / L, a pH value of 5.0, a nickel content of 92 g / L, and a sodium ion concentration of 30 g / L.

[0148] Step 6: After precision filtration, the temperature of the cathode solution is controlled at 67°C, and then it enters the electrowinning process. During electrowinning, the current intensity is 15800A and the current density is 190A / m³. 2 The cathode cycle is 8 days, the cell voltage is 3.8V, and high-purity electrolytic nickel is produced.

[0149] Step 7: The 15 vol% anolyte produced after electrowinning (the amount of anolyte required in Step 5) is purified by adding barium carbonate and black nickel. The amount of barium carbonate added is 1.1 times (in molar terms) of the theoretical amount required to remove lead ions from the anolyte, and the amount of black nickel added is 1.1 times (in molar terms) of the theoretical amount required to remove iron and cobalt from the anolyte. After purification, the anolyte is filtered to obtain the purified anolyte, which is returned to Step 5 to participate in the preparation of the new cathode solution. The remaining 90 vol% anolyte is returned to the acid dissolution process in Step 4 to dissolve nickel carbonate and nickel hydroxide, thus achieving the recycling of the anolyte.

[0150] The purity of the high-purity nickel and sodium sulfate prepared in Examples 1-3 was determined by ICP-OES testing and calculation, as shown in Table 1 below.

[0151] Table 1. Purity of high-purity nickel and sodium sulfate obtained in Examples 1-3 and Comparative Examples 1-3

[0152]

[0153] As shown in Table 1, the high-purity nickel obtained by electrowinning in Examples 1-3 all has a purity of 99.97% or higher, and the products meet the national standard GB / T6516-2010 for electrolytic nickel, with Ni+Co≥99.96% and Co≤0.02%. The purity of sodium sulfate is greater than 98.00%, which indicates that the process route provided by this invention can produce high-purity elemental nickel and the byproduct sodium sulfate with relatively high purity.

[0154] In summary, by comparing the high-purity nickel and sodium sulfate obtained in Example 1 with those in Comparative Examples 1, 2, and 3, it can be shown that for electrolytic nickel products: Example 1 uses a process of primary nickel precipitation with sodium carbonate and secondary nickel precipitation with sodium hydroxide. First, high-particle-size precipitation and pre-removal of impurities are achieved through coarse precipitation with nickel carbonate, and then fine precipitation with nickel hydroxide ensures deep recovery. The resulting precipitate has high purity and few impurities. The reaction is stable during acid dissolution and the amount of impurities dissolved is low. The subsequent electrolytic nickel crystals are uniform and the purity can reach over 99.97%.

[0155] Comparative Example 1 uses only sodium carbonate to precipitate nickel. The precipitate has high solubility, low recovery rate and many impurities. The impurity concentration in the solution after acid dissolution is high. Electrodeposition of nickel is prone to slag inclusion and insufficient purity.

[0156] Comparative Example 2 shows that using sodium hydroxide alone to precipitate nickel easily produces colloids, making filtration and washing difficult. The acid dissolution efficiency is low, and impurities are severely co-precipitated. Electrodeposition of nickel easily produces burrs and performance fluctuations.

[0157] In Comparative Example 3, the nickel plating sequence was reversed. The initial colloid resulted in poor purity, the secondary nickel plating was incomplete, and the purity of the nickel solution after acid dissolution was insufficient. As a result, the final electrolytic nickel quality could not meet the standards. Compared with Example 1 and Comparative Examples 1 to 3, the rationality of the process provided by the present invention can be highlighted.

[0158] For sodium sulfate byproducts, the process in Example 1 achieves precise stepwise removal of impurities, resulting in extremely low impurity content in the final filtrate, and sodium sulfate obtained by evaporation and crystallization can reach a purity of 98% or higher.

[0159] In Comparative Example 1, only sodium carbonate was used to precipitate nickel. The basic carbonate impurities formed by the residual Ca, Mg, Fe and Al in the filtrate were easily carried along during evaporation and crystallization, which reduced the purity of sodium sulfate.

[0160] Comparative Example 2 only used sodium hydroxide to precipitate nickel. The colloid easily adsorbed Fe, Al and incompletely precipitated nickel ions, resulting in a high concentration of impurities in the filtrate. The sodium sulfate crystals were not pure enough and may have exceeded the heavy metal limit.

[0161] In Comparative Example 3, the reversed nickel precipitation sequence resulted in impurities being carried into the initial colloids, incomplete secondary nickel precipitation, and high levels of residual nickel and other impurities in the filtrate, making it difficult to reduce the purity of sodium sulfate.

[0162] In other words, the sodium sulfate byproduct produced by the two-stage nickel plating process has the advantages of high purity (basically reaching industrial grade), significant resource utilization benefits (reducing wastewater treatment costs and realizing waste reuse), stable and controllable output, and smooth integration with the main process.

[0163] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

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; 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℃. Step 2: React the primary nickel precipitation filtrate with sodium hydroxide to perform secondary nickel precipitation, and separate the solid and liquid to obtain nickel hydroxide and secondary nickel precipitation filtrate; 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℃. Step 3: Nickel carbonate and nickel hydroxide are dissolved in acid using 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 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℃.

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 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.

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 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.

5. 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.

6. The method for preparing high-purity nickel by synergistic recycling of electrolytic nickel anolyte as described in claim 5, 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+ .

7. 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.

8. 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.

Images