Extraction, purification and deep impurity removal method for nickel sulfate solution

Abstract

The invention discloses an extraction purification deep impurity removal method for a nickel sulfate solution, and belongs to the technical field of nickel sulfate solution purification, and the extraction purification deep impurity removal method comprises the following steps: carrying out saponification treatment on a P204 extraction agent by adopting a sodium hydroxide solution to obtain a saponified organic phase P204, mixing the saponified organic phase P204 with a nickel sulfate water phase, stirring and standing to obtain a nickel sulfate solution; the method comprises the following steps: separating an organic phase from a water phase, mixing the organic phase with sulfuric acid, stirring, standing, separating out a nickel sulfate solution, concentrating the nickel sulfate, and recrystallizing to obtain the high-purity nickel sulfate with the purity of 99.4-99.9%. According to the method, the battery-grade nickel sulfate product with the purity as high as 99.9% can be obtained, the requirement of HG / T2824-2009 first-grade products is met, and the method is particularly suitable for purification of crude nickel sulfate generated in the copper ore smelting process and preparation of the battery-grade nickel sulfate.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel sulfate solution purification, and in particular relates to an extraction purification and deep impurity removal method for a nickel sulfate solution. Background Art

[0002] The crude nickel sulfate produced in the copper smelting process usually contains a variety of impurities, such as iron, calcium, magnesium, etc. These impurities seriously affect the quality of nickel sulfate and limit its application in new energy materials and other fields. Traditional impurity removal technologies, such as chemical precipitation and ion exchange, are often complicated to operate, costly and inefficient. For example, CN116002815A discloses a method for separating and purifying nickel sulfate electrolysis residual liquid and concentrating sulfuric acid. The patent uses nanofiltration membrane to separate and concentrate nickel sulfate, and reverse osmosis membrane to concentrate nanofiltration and dialysis dilute sulfuric acid. The operation process is complicated; CN115724477A discloses a method for purifying nickel sulfate solution, modified activated carbon and its preparation method. The patent uses H 2 O 2 The nickel sulfate solution is oxidized and adsorbed by modified activated carbon to remove impurities. This patent uses modified activated carbon oxidation adsorption to purify the nickel sulfate solution, which also has the problem of complicated operation process; CN109897955A discloses a method for deep purification of nickel sulfate solution, and the operation process is complicated; CN109110826A discloses a method for producing battery-grade nickel sulfate. This patent discloses that the nickel sulfide leachate is subjected to hydroxide neutralization of residual acid, impurity removal (iron, aluminum, silicon), extraction, degreasing, evaporation and crystallization to produce battery-grade nickel sulfate products, which is easy to cause environmental pollution.

[0003] Therefore, developing an efficient and low-cost method for removing impurities from nickel sulfate solution has important industrial significance. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for deep impurity removal of nickel sulfate solution by extraction purification. The present invention aims to achieve efficient removal of impurities in nickel sulfate solution by optimizing the selection of extractants and operating conditions to produce high-purity nickel sulfate solution. The present invention can obtain a battery-grade nickel sulfate product with a purity of up to 99.9%, which meets the first-class product requirements of HG / T2824-2009. The method of the present invention is particularly suitable for the purification of crude nickel sulfate produced in the copper ore smelting process and the preparation of battery-grade nickel sulfate.

[0005] To achieve the above object, the present invention provides a method for deep impurity removal of nickel sulfate solution by extraction purification, comprising the following steps: saponifying the P204 extractant with a sodium hydroxide solution to obtain a saponified organic phase P204;

[0006] The saponified organic phase P204 is mixed with the nickel sulfate aqueous phase, stirred and then allowed to stand to separate the organic phase and the aqueous phase;

[0007] The organic phase is mixed with sulfuric acid, stirred and then allowed to stand to separate a nickel sulfate solution;

[0008] Concentrating and recrystallizing the nickel sulfate to obtain high-purity nickel sulfate, wherein the purity of the high-purity nickel sulfate is 99.4-99.9%;

[0009] The volume ratio of the organic phase to the sulfuric acid is 1:1.

[0010] Compared with other extractants or methods, the advantage of P204 as an extractant is its high selectivity for nickel and high extraction efficiency. The saponification treatment further improves the extraction efficiency of P204, making the entire process more efficient. In contrast, the traditional chemical precipitation method and ion exchange method are complicated to operate, and may produce more wastewater and waste residue, causing great pressure on the environment. Although other extractants such as P507 can also achieve impurity removal, their efficiency is not as good as P204. The present invention uses P204 as an extractant and, through the method of saponification treatment, can achieve efficient purification and deep impurity removal of nickel sulfate solution, produce high-purity battery-grade nickel sulfate products, and reduce costs and environmental impacts.

[0011] Preferably, the mass ratio of the sodium hydroxide solution to the P204 extractant is 1:(0.5-1).

[0012] More preferably, the mass ratio of the sodium hydroxide solution to the P204 extractant is 1:1.

[0013] Preferably, the volume ratio of the saponified organic phase P204 to the nickel sulfate aqueous phase is 1:(1-2).

[0014] More preferably, the volume ratio of the saponified organic phase P204 to the nickel sulfate aqueous phase is 1: 2. Preferably, the stirring time after mixing the saponified organic phase P204 and the nickel sulfate aqueous phase is 10-15 minutes, and the standing time is 10-20 minutes.

[0015] Preferably, the stirring time after mixing the organic phase with sulfuric acid is 10-15 min, and the standing time is 5-10 min.

[0016] Preferably, the concentration is evaporative concentration.

[0017] Preferably, the temperature during the evaporation and concentration is 60° C., and the evaporation and concentration to an end point density is 1.3 g / mL.

[0018] The present invention also provides the use of the nickel sulfate prepared according to the method in preparing a nickel sulfate battery.

[0019] The crude nickel sulfate produced in the copper smelting process (i.e., the primary product after copper smelting) usually contains a variety of impurities, such as iron, calcium, magnesium, etc. These impurities seriously affect the quality of nickel sulfate and limit its application in the fields of new energy materials. In order to solve the above problems, the present invention uses P204 as an extractant and achieves efficient purification and deep impurity removal of nickel sulfate solution through saponification treatment. The causal relationship between its principle and technical effect is as follows:

[0020] 1. Selectivity of P204 extractant: P204 (tributyl phosphate) is a neutral phosphorus-oxygen extractant that has good selectivity for a variety of metal ions. In nickel sulfate solution, P204 can preferentially form complexes with nickel ions, while having low selectivity for impurity ions such as iron, calcium, and magnesium. This selectivity enables P204 to effectively extract nickel from nickel sulfate solution while leaving behind impurity ions.

[0021] 2. The role of saponification treatment: Saponification treatment refers to the reaction of P204 with sodium hydroxide solution to form saponification products of negative ions. This process increases the hydrophilicity of P204, making it easier to mix with water and improving the extraction efficiency. At the same time, the negative ions formed by the saponified P204 can more effectively form complexes with metal cations in the solution, thereby enhancing the extraction capacity. If potassium hydroxide solution is used, potassium ions will be introduced, affecting the purity of nickel sulfate.

[0022] 3. Control of the phase ratio and mixing time: By controlling the phase ratio (volume ratio of organic phase to aqueous phase) and mixing time, the mass transfer efficiency in the extraction process can be optimized. Appropriate phase ratio and mixing time can ensure that P204 is fully in contact with the nickel sulfate solution, thereby increasing the nickel extraction rate, while reducing the amount of extractant used and reducing costs.

[0023] 4. Optimization of the volume concentration of the extractant: Optimization of the volume concentration of the extractant helps to balance the extraction efficiency and economy. Appropriate volume concentration can ensure the effective use of the extractant in the extraction process while avoiding excessive concentration that leads to increased costs.

[0024] 5. Efficiency of the stripping process: In the stripping process, the organic phase containing impurities is treated with sulfuric acid, which can transfer nickel from the organic phase to the aqueous phase to obtain a high-purity nickel sulfate solution. This step utilizes the property that P204 has a reduced affinity for nickel under acidic conditions, achieving efficient recovery of nickel.

[0025] 6. Effect of crystallization and purification: By controlling the crystallization conditions (such as temperature, stirring time, etc.), the nickel sulfate solution can be purified to obtain battery-grade nickel sulfate products. This step utilizes the crystallization characteristics of nickel sulfate under specific conditions and improves the purity and consistency of the product by controlling the crystallization process.

[0026] The present invention provides a nickel sulfate solution purification technology that is both economical and efficient, simple to operate, and environmentally friendly by adopting P204 extractant and saponification treatment. Compared with the prior art, such as the membrane separation method of CN116002815A, the modified activated carbon oxidation adsorption method of CN115724477A, ​​the deep purification method of CN109897955A, and the battery-grade nickel sulfate production method of CN109110826A, the present invention has obvious advantages in simplifying the operation process, reducing the risk of environmental pollution, and reducing production costs. The present invention can produce battery-grade nickel sulfate products with a purity of up to 99.9%, which meets the strict requirements for high-purity nickel sulfate in the fields of new energy materials and other fields, and shows strong international competitiveness and market application potential.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The extraction, purification and deep impurity removal method of the nickel sulfate solution of the present invention shows significant advantages over the prior art in many aspects: First, the present invention innovatively uses P204 as an extractant, and through saponification treatment, it can directly produce high-purity nickel sulfate that meets battery-grade standards, significantly reducing the impurity content in the finished product. Secondly, the present invention combines the traditional iron, cobalt, calcium, magnesium and other impurity removal processes from three steps into one step through a simplified process flow, thereby improving operating efficiency, reducing energy and chemical consumption, and reducing environmental pollution, which is in line with the development trend of green chemistry. Finally, the process parameters of the present invention are easy to control, making the production process more stable and predictable, reducing the difficulty of operation, and at the same time improving the market competitiveness and economic value of the product. These advantages make the present invention have obvious competitiveness and broad application prospects in the field of nickel sulfate solution purification technology. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] The nickel sulfate aqueous phase in the present invention is a product obtained by dissolving the primary product after copper smelting processing in water.

[0035] Unless otherwise specified, room temperature in the present invention refers to 25±2°C.

[0036] Unless otherwise specified, the reagents in the present invention are purchased. For example, P204 extractant (CAS No.: 298-07-7) and P507 extractant (CAS No.: 57175-88-1) are purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; nickel sulfate seeds are purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0037] The technical solution of the present invention is further illustrated by the following embodiments.

[0038] Example 1

[0039] 1. Preparation of saponified organic phase: 100 g of P204 extractant was mixed with sodium hydroxide solution (concentration of 40 wt%) at a mass ratio of 1:1, and stirred for 30 min to obtain a saponified organic phase P204;

[0040] 2. Extraction process: The saponified organic phase P204 was mixed with a nickel sulfate aqueous phase containing 20 g / L nickel in a volume ratio of 1:2, stirred for 15 min, and then allowed to stand for 10 min to separate the organic phase (the organic phase contained impurities) and the aqueous phase;

[0041] 3. Stripping process: the organic phase containing impurities is mixed with sulfuric acid (3 mol / L) at a volume ratio of 1:1, stirred for 10 minutes, and allowed to stand for 5 minutes before separating the nickel sulfate solution (aqueous phase);

[0042] 4. Crystallization and purification: The nickel sulfate solution was evaporated and concentrated at 60°C to an end point density of 1.3 g / mL, then cooled to 40°C, nickel sulfate seed crystals were added, and after stirring for 30 minutes, the crystallized product was collected to obtain battery-grade nickel sulfate (purity of 99.9%), which meets the first-class requirements of HG / T2824-2009.

[0043] Example 2

[0044] 1. Preparation of saponified organic phase: 100 g of P204 extractant was mixed with sodium hydroxide solution (concentration of 40 wt%) at a mass ratio of 1:0.5, and stirred for 15 min to obtain a saponified organic phase P204;

[0045] 2. Extraction process: The saponified organic phase P204 was mixed with a nickel sulfate aqueous phase containing 20 g / L nickel in a volume ratio of 1:2, stirred for 15 min, and then allowed to stand for 10 min to separate the organic phase and the aqueous phase;

[0046] 3. Stripping process: The organic phase containing impurities was mixed with sulfuric acid (3 mol / L) at a volume ratio of 1:1, stirred for 10 min, and allowed to stand for 5 min before separating the nickel sulfate solution;

[0047] 4. Crystallization and purification: The nickel sulfate solution was evaporated and concentrated at 60°C to an end point density of 1.3 g / mL, then cooled to 40°C, nickel sulfate seed crystals were added, and after stirring for 30 minutes, the crystallized product was collected to obtain battery-grade nickel sulfate (purity of 99.5%), which meets the first-class requirements of HG / T2824-2009.

[0048] Example 3

[0049] 1. Preparation of saponified organic phase: 100 g of P204 extractant and sodium hydroxide solution (concentration of 40 wt%) were mixed in a mass ratio of 1:1 and stirred for 15 min to obtain a saponified organic phase P204;

[0050] 2. Extraction process: The saponified organic phase P204 was mixed with a nickel sulfate aqueous phase containing 20 g / L nickel in a volume ratio of 1:1, stirred for 10 min, and then allowed to stand for 20 min to separate the organic phase and the aqueous phase;

[0051] 3. Stripping process: The organic phase containing impurities was mixed with sulfuric acid (3 mol / L) at a volume ratio of 1:1, stirred for 15 min, and allowed to stand for 10 min before separating the nickel sulfate solution;

[0052] 4. Crystallization and purification: The nickel sulfate solution was evaporated and concentrated at 60°C to an end point density of 1.3 g / mL, then cooled to 40°C, nickel sulfate seed crystals were added, and after stirring for 30 minutes, the crystallized product was collected to obtain battery-grade nickel sulfate (purity of 99.4%), which meets the first-class requirements of HG / T2824-2009.

[0053] Comparative Example 1 Traditional Chemical Precipitation Method

[0054] 1. Chemical precipitation process:

[0055] A nickel sulfate solution containing 20 g / L nickel was heated to 60°C, a chemical precipitant (a sodium hydroxide solution with a concentration of 40 wt%) was added, the pH was adjusted to 4.5, and impurities such as iron, calcium, and magnesium were precipitated. The solution was stirred for 30 min, allowed to stand for 2 hours, and the precipitate and supernatant were separated.

[0056] 2. Filtration and washing:

[0057] The precipitate was filtered and washed three times with deionized water to remove the residual nickel sulfate solution.

[0058] 3. Crystallization and purification:

[0059] The supernatant was evaporated and concentrated at 60°C to an end point density of 1.3 g / mL, cooled to 40°C, nickel sulfate seeds were added, stirred for 30 min, and the crystalline product nickel sulfate (purity: 96%) was collected.

[0060] Compared with the solution of the present invention, although the traditional chemical precipitation method can also obtain nickel sulfate with higher purity, the chemical precipitation method is complicated to operate, requires multiple steps, and the precipitate is difficult to handle, and the risk of environmental pollution is high.

[0061] Comparative Example 2 Ion Exchange Method

[0062] 1. Ion exchange process:

[0063] A nickel sulfate solution containing 20 g / L of nickel was passed through an ion exchange resin column (sulfonic acid strong acid cation exchange resin, model φ200x1500x7) to remove impurities by utilizing the selective adsorption of specific ions by the resin.

[0064] 2. Crystallization and purification:

[0065] The nickel sulfate solution passing through the resin column was collected, evaporated and concentrated at 60°C to an end point density of 1.3 g / mL, cooled to 40°C, seed crystals were added, stirred for 30 min, and the crystalline product nickel sulfate (purity: 99%) was collected.

[0066] 3. Resin regeneration:

[0067] The resin was regenerated using acid (2-3 wt% dilute sulfuric acid solution) and alkaline solution (2-3 wt% sodium hydroxide solution) to restore its adsorption capacity.

[0068] Compared with the solution of the present invention, although the ion exchange method can also remove impurities, the regeneration and treatment of the resin are complicated, and the operating cost and maintenance cost are much higher than the method of the present invention.

[0069] Comparative Example 3: Different stripping conditions

[0070] 1. Preparation of saponified organic phase: 100 g of P204 extractant was mixed with sodium hydroxide solution (concentration of 40 wt%) at a mass ratio of 1:1, and stirred for 30 min to obtain a saponified organic phase P204;

[0071] 2. Extraction process: The saponified organic phase P204 was mixed with a nickel sulfate aqueous phase containing 20 g / L nickel in a volume ratio of 1:2, stirred for 15 min, and then allowed to stand for 10 min to separate the organic phase and the aqueous phase;

[0072] 3. Stripping process: the organic phase containing impurities was mixed with sulfuric acid (3 mol / L) at a volume ratio of 1:0.5, stirred for 5 min, and allowed to stand for 5 min before separating the nickel sulfate solution;

[0073] 4. Crystallization and purification: The nickel sulfate solution was evaporated and concentrated at 60°C to an end point density of 1.3 g / mL, then cooled to 40°C, nickel sulfate seed crystals were added, and after stirring for 30 minutes, the crystallized product was collected to obtain battery-grade nickel sulfate (purity of 99.1%).

[0074] Compared with Example 1, this comparative example reduces the amount of sulfuric acid used and shortens the stirring time, both of which lead to insufficient stripping, thereby affecting the purity of nickel sulfate. The stripping conditions of the embodiment of the present invention can more effectively improve the purity of nickel sulfate.

[0075] Comparative Example 4: Different crystallization conditions

[0076] 1. Preparation of saponified organic phase: 100 g of P204 extractant was mixed with sodium hydroxide solution (concentration of 40 wt%) at a mass ratio of 1:1, and stirred for 30 min to obtain a saponified organic phase P204;

[0077] 2. Extraction process: The saponified organic phase P204 was mixed with a nickel sulfate aqueous phase containing 20 g / L nickel in a volume ratio of 1:2, stirred for 15 min, and then allowed to stand for 10 min to separate the organic phase (the organic phase contained impurities) and the aqueous phase;

[0078] 3. Stripping process: The organic phase containing impurities was mixed with sulfuric acid (3 mol / L) at a volume ratio of 1:1, stirred for 10 min, and allowed to stand for 5 min before separating the nickel sulfate solution;

[0079] 4. Crystallization and purification: The nickel sulfate solution was evaporated and concentrated at 50°C to an end point density of 1.2 g / mL, then cooled to 30°C, nickel sulfate seeds were added, and after stirring for 20 minutes, the crystallized product was collected to obtain nickel sulfate (purity of 99.5%), which did not meet the first-class requirements of HG / T2824-2009.

[0080] This comparative example reduces the evaporation temperature and shortens the stirring time. Although the purity of nickel sulfate is also high, it will lead to incomplete crystallization, affecting the particle size and morphology of nickel sulfate. The crystallization conditions of the embodiment of the present invention can better control the crystallization process and improve the quality and consistency of the product.

[0081] The present invention produces a battery-grade nickel sulfate product by a direct extraction method of P204, optimizes the process, abandons the traditional P507 extraction step, and the prepared battery-grade nickel sulfate meets the industry standard HG / T2824-2022. Compared with the traditional chemical precipitation and ion exchange methods, the process operation of the present invention is simpler and easy to industrialize; the present invention reduces the use of chemical reagents and reduces production costs. The present invention uses P204 as an extractant, and at the same time particularly emphasizes the enhancement of its extraction efficiency by saponification treatment. Saponification treatment not only improves the hydrophilicity of P204, but also enhances its ability to form a complex with metal cations, which is not mentioned in the prior art. At the same time, the present invention optimizes the saponification conditions and extraction parameters to achieve higher purity and efficiency. That is, in the present invention, the saponification treatment of P204 and sodium hydroxide is one of the innovative points, and this treatment method is not described in detail in the prior art. The present invention significantly improves the operating efficiency and reduces the consumption of energy and chemicals by simplifying the traditional multi-step impurity removal process into one step, which is not mentioned in the prior art.

[0082] The present invention emphasizes environmental friendliness and reduces the use and emission of harmful chemicals, which shows stronger environmental awareness and practical effects compared with the prior art. The present invention reduces production costs by reducing the use of chemical reagents and optimizing the operating process. The present invention can produce battery-grade nickel sulfate products with a purity of up to 99.9%, showing the significant advantages of the present invention in improving product purity. The process parameters of the present invention are easy to control, making the production process more stable and predictable. The process of the present invention is not only suitable for the purification of crude nickel sulfate produced in the copper smelting process, but also suitable for the preparation of battery-grade nickel sulfate, showing stronger adaptability and application range.

[0083] In summary, it can be seen that the present invention is significantly different from the prior art in terms of selection of extractant, saponification treatment, simplification of operation process, environmental friendliness, cost-effectiveness, technical effect and process adaptability. These differences and effects not only improve the purity and quality of nickel sulfate, but also reduce costs and environmental impacts, thereby enhancing the industrial application value and market competitiveness of the present invention.

[0084] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for deep impurity removal by extraction purification of nickel sulfate solution, characterized in that: The following steps are involved: The P204 extractant is saponified with a sodium hydroxide solution to obtain a saponified organic phase P204; The saponified organic phase P204 is mixed with the nickel sulfate aqueous phase, stirred and then allowed to stand to separate the organic phase and the aqueous phase; The organic phase is mixed with sulfuric acid, stirred and then allowed to stand to separate a nickel sulfate solution; Concentrating and recrystallizing the nickel sulfate to obtain high-purity nickel sulfate, wherein the purity of the high-purity nickel sulfate is 99.4-99.9%; The volume ratio of the organic phase to the sulfuric acid is 1:

1.

2. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 1, characterized in that: The mass ratio of the sodium hydroxide solution to the P204 extractant is 1:(0.5-1).

3. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 2, characterized in that: The mass ratio of the sodium hydroxide solution to the P204 extractant is 1:

1.

4. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 1, characterized in that: The volume ratio of the saponified organic phase P204 to the nickel sulfate aqueous phase is 1:(1-2).

5. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 4, characterized in that: The volume ratio of the saponified organic phase P204 to the nickel sulfate aqueous phase is 1:

2.

6. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 1, characterized in that: The saponified organic phase P204 and the nickel sulfate aqueous phase are mixed and stirred for 10-15 minutes and allowed to stand for 10-20 minutes.

7. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 1, characterized in that: The stirring time after mixing the organic phase and sulfuric acid is 10-15 minutes, and the standing time is 5-10 minutes.

8. The method for deep impurity removal by extraction and purification of nickel sulfate solution according to claim 1, characterized in that: The concentration is evaporation concentration.

9. Use of nickel sulfate obtained according to the method according to any one of claims 1 to 8 in the preparation of nickel sulfate batteries.