Preparation method of nickel sulfate for power battery

Abstract

The invention belongs to the technical field of preparation of a ternary precursor material nickel salt for a power lithium ion battery, and discloses a preparation method of nickel sulfate for a power battery, which comprises the following steps: dissolving crude nickel sulfate in water, filtering to remove impurities, introducing compressed air into the solution at a set temperature, and stirring; slurrying beta-hydroxy nickel oxide, adding a solution, reacting for a set time, filtering, heating the obtained first-stage hydroxylated liquid to a set temperature, introducing compressed air into the first-stage hydroxylated liquid, reacting, filtering, heating the obtained second-stage hydroxylated liquid, adding a sodium fluoride solution into the second-stage hydroxylated liquid, reacting for a set time, and filtering to obtain an impurity-removed liquid and impurity-removed slag; mixing P204 and light white oil according to a ratio, firstly performing sodium soap, then performing nickel soap, adding the obtained nickel soap organic phase into the impurity removal liquid, and performing first-stage extraction to obtain first-stage raffinate; and mixing P507 and light white oil according to a ratio, firstly performing sodium soap, then performing nickel soap, adding the obtained nickel soap organic phase into the first-stage raffinate, performing second-stage extraction to obtain second-stage raffinate, and performing evaporative crystallization on the second-stage raffinate to obtain the nickel sulfate for the power battery.

Description

Technical Field

[0001] This invention belongs to the technical field of nickel salt preparation of ternary precursor materials for power lithium-ion batteries, specifically relating to a method for preparing nickel sulfate for power batteries. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Currently, the domestic process for preparing battery-grade nickel sulfate is as follows: crude nickel sulfate solution is first subjected to iron removal using the sodium vanadium ferrophosphate method, followed by zinc removal by sulfidation, calcium and magnesium removal by fluorination, nickel precipitation with sodium carbonate, acid dissolution with nickel carbonate, and finally extraction, evaporation and crystallization to obtain refined nickel sulfate.

[0004] The precipitation of sodium ferrovanadium requires high temperature, high acidity, and oxidizing conditions. If the process does not meet the requirements, ferric hydroxide colloid is easily formed. This colloid is difficult to remove through conventional filtration, resulting not only in nickel loss due to iron inclusion but also contamination of subsequent processes. Simultaneously, the introduction of sodium salts leads to increased sodium content in the system. + Accumulation can lead to scaling (sodium sulfate) and excessive sodium content in the product during subsequent evaporation and crystallization processes.

[0005] In the zinc removal process using sulfidation, the solubility products of NiS and ZnS are very close. When a sulfiding agent (such as Na₂S or H₂S) is added, Ni... 2 + Will with Zn 2+ A fierce competitive precipitation reaction occurs. When the sulfiding agent is excessive, nickel will precipitate as NiS, resulting in nickel loss. When the amount of sulfiding agent is insufficient, zinc residue is likely to occur.

[0006] In the fluorination process to remove calcium and magnesium, F is easily generated. - The residue, F - It can cause intergranular corrosion in stainless steel equipment and is also a harmful impurity in batteries; on the other hand, the solubility of MgF2 in nickel sulfate solution is relatively high, which limits the ability of fluorination to remove magnesium and makes it difficult to stably meet battery-grade requirements.

[0007] In the sodium carbonate nickel plating process, the use of Na₂CO₃ will introduce Na again. + If the nickel carbonate filter cake is not washed thoroughly, Na... + It will be carried into the subsequent solution and become the source of sodium impurities in the crystallized product.

[0008] Therefore, the existing crude nickel sulfate refining process has problems such as nickel loss, sodium ion accumulation affecting product quality, and limited magnesium removal capacity. Summary of the Invention

[0009] In view of the deficiencies of the prior art, the purpose of the present application is to provide a preparation method of nickel sulfate for power battery.

[0010] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme: The present application provides a preparation method of nickel sulfate for power battery, comprising the following steps: The crude nickel sulfate is dissolved in water, impurities are removed by filtration, then compressed air is first introduced into the solution at a set temperature, and stirring is carried out for a set time; then the beta-hydroxyl nickel oxide is slurried and added to the solution, and the reaction is carried out for a set time, and then filtration is carried out to obtain a first-stage hydroxylated solution and iron removal residue; The first-stage hydroxylated solution is heated to a set temperature, then compressed air is secondly introduced into the solution, and after the reaction, filtration is carried out to obtain a second-stage hydroxylated solution and zinc removal residue; The second-stage hydroxylated solution is heated, then sodium fluoride solution is added thereto, and the reaction is carried out for a set time, and then filtration is carried out to obtain a removal solution and removal residue; P204 and light white oil are mixed in a certain proportion, then sodium soap is prepared, and then nickel soap is prepared, the obtained nickel soap organic phase is added to the removal solution, extraction is carried out, and a first-stage raffinate is obtained; P507 and light white oil are mixed in a certain proportion, then sodium soap is prepared, and then nickel soap is prepared, the obtained nickel soap organic phase is added to the first-stage raffinate, extraction is carried out, and a second-stage raffinate is obtained, the second-stage raffinate is subjected to evaporation crystallization, and nickel sulfate for power battery is obtained.

[0011] The beneficial effects obtained by one or more embodiments of the present application are as follows: The present application replaces the traditional high-risk impurity removal process by the process of "hydroxylated precipitation-extraction purification", and the beta-hydroxyl nickel oxide mediated hydroxylated iron removal and air oxidation hydroxylated zinc removal, avoids nickel loss and sodium salt introduction; combined with sodium fluoride assisted precipitation of calcium and magnesium and P204 / P507 fractional extraction, the impurities are removed in a targeted manner, and finally the low-sodium and low-impurity nickel sulfate for power battery is prepared. BRIEF DESCRIPTION OF DRAWINGS

[0012] The drawings accompanying the specification of the present application form a part of the present application and serve to provide a further understanding of the present application, the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0013] Figure 1 It is a process flow chart of the embodiment of the present application. DETAILED DESCRIPTION

[0014] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0015] In view of the technical problems existing in the process of preparing nickel sulfate for power batteries by refining crude nickel sulfate in the prior art mentioned in the background, the present application provides a preparation method of nickel sulfate for power batteries, comprising the following steps: (1) Dissolve the crude nickel sulfate in water, filter out impurities, then at a set temperature, first pass compressed air into the solution, stir and react for a set time; then add the β-hydroxyl nickel slurry into the solution, react for a set time, filter to obtain a first-stage hydroxylated solution and iron removal residue. The reaction in this stage is specifically: ; ; ; ; ; (2) Heat the first-stage hydroxylated solution to a set temperature, then second pass compressed air into it, after reaction, filter to obtain a second-stage hydroxylated solution and zinc removal residue. The reaction in this stage is specifically: ; ; ; ; ; Heat the second-stage hydroxylated solution, then add sodium fluoride solution into it, react for a set time, filter to obtain a removal solution and removal residue. The reaction in this stage is specifically: ; ; Mix P204 and light white oil according to the proportion, first carry out sodium soap, then carry out nickel soap, add the obtained nickel soap organic phase into the removal solution, carry out a first-stage extraction to obtain a first-stage extraction residue. The reactions occurring in this process are specifically: sodium soap ; nickel soap ; extraction (wherein, Me represents metal ions, including Cu 2+ , Fe 3+ , Co 2+ , Zn 2+ , Ca 2+ , Mg 2+ and Mn 2+ metal ions); P507 and light white oil were mixed in proportion, sodium soap was carried out first, then nickel soap was carried out, the obtained nickel soap organic phase was added into the first stage raffinate to carry out second stage extraction, the second stage raffinate was evaporated and crystallized to obtain the nickel sulfate for power batteries.

[0016] Fe in the crude nickel sulfate solution 2+ Fe 3+ was removed. The traditional yellow sodium iron vanadium method relies on high temperature and high acid conditions, and is easy to form difficult-to-filter iron hydroxide colloid and introduce Na + . The method passes compressed air (provides oxygen) to oxidize Fe 2+ to Fe 3+ , and at the same time, β-hydroxyl nickel oxide (β-NiO(OH)) is added as a crystal seed and a pH regulator (to adjust the pH to 1-3). The surface hydroxyl of β-NiO(OH) can adsorb Fe 3+ and induce it to form a structurally stable iron hydroxyl compound precipitate (such as FeO(OH)), avoiding the formation of colloid and realizing efficient separation of iron, and without the need to introduce sodium salt, reducing the cumulative risk of Na + .

[0017] The traditional sulfidation zinc removal is easy to cause nickel coprecipitation loss due to the close solubility product of NiS and ZnS. The method passes compressed air into the first stage hydroxylated solution again, and uses the high temperature (70-90°C) oxygen environment to make Zn 2+ combine with the hydroxyl (possibly from the hydrolysis of β-NiO(OH) or the dissociation of water) in the solution to form a difficult-to-dissolve zinc hydroxyl compound (such as Zn(OH)2 or ZnO(OH)) precipitate. Since Ni 2+ has a weaker ability to combine with hydroxyl under this condition, it can remain in the solution, thereby realizing selective removal of zinc and avoiding nickel loss caused by excessive sulfidation agent.

[0018] The second stage hydroxylated solution still contains Ca 2+ , Mg 2+ and other alkaline earth metal ions. After adding sodium fluoride solution, F - reacts with Ca 2+ , Mg 2+ to form difficult-to-dissolve fluoride precipitates (CaF2, MgF2). Although the solubility of MgF2 is slightly higher than that of CaF2, by controlling the reaction temperature (80-90°C) and time (2-3h), the growth of the precipitate crystals can be promoted, and the filtration efficiency can be improved; at the same time, compared with the traditional fluoridation impurity removal, this step is carried out after the hydroxyl iron and zinc removal, and the impurity ion concentration has been reduced, which can reduce the amount of F - and reduce the corrosion risk of fluorine residues on subsequent equipment.

[0019] The trace amounts of heavy metal ions such as Cu, Pb, Zn and the like in the impurity removal solution are treated by using a P204 (diisooctyl phosphate) and light white oil mixed organic phase, and then the organic phase is treated by sodium soap (adjusting the alkalinity of the organic phase and enhancing the extraction capacity) and nickel soap (loading Ni 2+ , and improving the selectivity to impurities) to contact with the impurity removal solution. 3+ The extraction capacity of P204 to Fe 2+ , Cu 2+ , Zn 2+ and the like is stronger than that of Ni 2+ , and thus the heavy metal ions can be transferred from the aqueous phase to the organic phase, while Ni 2+ is left in the aqueous phase (first-stage raffinate), so that the heavy metal impurities are deeply removed.

[0020] The first-stage raffinate still contains impurities such as Ca 2+ , Mg 2+ , Co 2+ and the like, and the impurities are treated by using a P507 (2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester) and light white oil mixed organic phase, and then the organic phase is treated by sodium soap and nickel soap to perform extraction. The extraction selectivity of P507 to Ca 2+ , Mg 2+ , Co 2+ is higher than that of Ni 2+ , and thus the impurities can be further extracted into the organic phase, so that a high-purity NiSO4 solution (second-stage raffinate) is obtained, and the nickel sulfate product meeting the battery grade standard is obtained after evaporation and crystallization.

[0021] In some embodiments, the temperature when the compressed air is first introduced is 70-90°C, and the reaction time is 1-3h.

[0022] The oxygen provided by the compressed air needs to oxidize Fe 3+ to Fe 2+ so as to be removed by precipitation, and the high temperature can significantly improve the oxidation reaction rate to ensure that Fe 3+ is fully converted within 1-3h; the β-hydroxyl nickel oxide (β-NiO(OH)) as a crystal seed is more likely to induce the formation of the structural stable iron hydroxyl compound (such as FeO(OH)) precipitate at high temperature, so as to avoid the iron hydroxide colloid easily produced at low temperature in the traditional process, thereby improving the filtration efficiency and reducing the nickel entrainment loss; the surface hydroxyl of the β-NiO(OH) is more active at high temperature, and can effectively adsorb Fe 3+ and regulate the pH of the solution to 1-3 to ensure that the iron precipitate is completely removed, while avoiding the introduction of sodium salt.

[0023] Preferably, the temperature when the compressed air is first introduced is 75-85°C.

[0024] Preferably, the β-hydroxyl nickel oxide is slurried and added to the solution, the pH value is adjusted to 1-3, and the stirring reaction time is 0.5-1.5 h.

[0025] Fe 3+ Fe 3+ Fe 2+ Fe 2+ Fe 2+ Fe

[0026] In some embodiments, the temperature of the first hydroxylated solution after heating is 70-90°C, compressed air is introduced for the second time, stirring is performed, and the reaction is performed for 1-3 h, thereby obtaining a second hydroxylated solution and zinc removal residue.

[0027] The reaction principle of the second introduction of compressed air is to promote the selective hydroxyl precipitation of zinc ions in a high-temperature oxygen environment, and the specific principle is as follows: after the first hydroxylated iron removal, the solution still contains Zn 2+ impurities. By introducing compressed air for the second time at 70-90°C, an oxidation condition is provided and the dissociation of water or the hydrolysis of β-hydroxyl nickel oxide to generate hydroxyl (-OH) is promoted, so that Zn 2+ forms a hardly soluble zinc hydroxyl compound (such as Zn(OH)2 or ZnO(OH)) precipitate, and Ni 2+ has a weak binding ability with hydroxyl under this temperature and pH condition, and can remain in the solution, thereby realizing the directional removal of zinc and avoiding the problem of nickel loss caused by the close solubility product of NiS and ZnS in the traditional zinc removal by sulfuration.

[0028] Preferably, the temperature of the second introduction of compressed air is 75-85°C.

[0029] In some embodiments, after the sodium fluoride solution is added, the reaction temperature is 80-90°C, and the reaction time is 2-3 h.

[0030] In some embodiments, the mass ratio of P204 and light white oil is 20-30:70-80.

[0031] P204 is diisooctyl phosphate (an acidic phosphate extractant), light white oil is mineral oil (mainly composed of alkanes and cycloalkanes, used to adjust the viscosity and extraction performance of the organic phase) as diluent. After mixing in proportion, the two are treated with sodium soap and nickel soap to form the organic phase used for extracting impurity ions.

[0032] Preferably, the temperature of sodium soap and nickel soap is 45-55℃. This temperature range can promote the neutralization reaction of sodium hydroxide (sodium soap reagent) and P204 / P507 extractant, and the complexation reaction of nickel sulfate (nickel soap reagent) and extractant, improve the saponification rate, and ensure that the active groups of the organic phase are fully converted. The temperature of subsequent extraction processes (such as first-stage extraction and second-stage extraction) is also controlled at about 50℃. Matching the saponification temperature with the extraction temperature can avoid changes in the viscosity of the organic phase caused by temperature fluctuations, ensuring stable and efficient extraction process.

[0033] In some embodiments, the mass ratio of P507 to light white oil is 15-25:70-85.

[0034] In some embodiments, during the first-stage extraction, the O / A is 1:0.5-1.5, preferably 1:0.7-0.9.

[0035] In some embodiments, during the second-stage extraction, the O / A is 1-5:1, preferably 1-3:1.

[0036] In some embodiments, the process further includes the preparation of β-hydroxyl nickel oxide, the specific steps being: adding sodium hydroxide and sodium hypochlorite to the impurity removal solution, stirring and reacting to obtain β-hydroxyl nickel oxide. The β-hydroxyl nickel oxide is used for first-stage hydroxyl iron removal. The above process specifically occurs the following reaction: .

[0037] The application will be further described below with reference to the examples.

[0038] Example 1 Table 1 Composition of crude nickel sulfate, %

[0039] A preparation method of nickel sulfate for power batteries, as shown in Figure 1 , includes the following steps: (1) First-stage hydroxyl iron removal. 200g of crude nickel sulfate is added to a beaker, 400ml of pure water is added, the temperature is raised to 83℃, and stirring is performed for 1 hour. The filter residue is washed to obtain 1000ml of dissolved solution. The dissolved solution is added to a beaker, the temperature is raised to 80℃, compressed air is passed through the beaker while stirring, and the reaction time is 3 hours. 50g of β-hydroxyl nickel oxide (β-NiO(OH)) is slurried and added to the beaker, the pH is adjusted to 2, stirring is performed, the reaction time is 1 hour, the filter residue is washed to obtain 1000ml of first-stage hydroxyl solution and 120.6g of iron residue.

[0040] Table 2 Composition of crude nickel sulfate solution, mg / L

[0041] (2) Second stage hydroxylation to remove zinc. The first stage hydroxylated solution was added to a beaker, heated to 80°C, and stirred with compressed air for 2.5 hours at pH 5. The filtrate was washed to obtain 1000 ml of second stage hydroxylated solution and 68.73 g of zinc removal residue.

[0042] Table 3 Composition of hydroxylated solution, mg / L

[0043] (3) Impurity removal. The second stage hydroxylated solution was added to a beaker, heated to 85°C, and stirred with 16 g of sodium fluoride solution for 2.5 hours. The solution was allowed to settle for 1 hour, and then filtered to obtain 1000 ml of impurity removal solution and 12.25 g of impurity removal residue.

[0044] Table 4 Composition of impurity removal solution, mg / L

[0045] (4) Preparation of β-hydroxyl nickel oxide. 1000 ml of impurity removal solution was added to a beaker, 50 g of sodium hydroxide and 200 ml of sodium hypochlorite solution were added, and the mixture was stirred for 0.5 hours. The β-hydroxyl nickel oxide (β-NiO(OH)) precipitate was filtered and washed, and then dried to obtain 55.5 g of β-hydroxyl nickel oxide (β-NiO(OH)) which was used for first stage hydroxylation to remove iron.

[0046] (5) First stage extraction. P204 and light white oil were mixed in a mass ratio of 30:70, and then 30% sodium hydroxide solution was added to the organic phase at a reaction temperature of 50°C and a phase ratio of O / A=20:1 to perform sodium saponification, with a saponification rate of 50%. Nickel saponification was performed using nickel sulfate solution containing 50 g / L of nickel at a reaction temperature of 50°C and a phase ratio of O / A=10:1 to obtain nickel saponified organic phase which was added to the impurity removal solution to perform extraction at a reaction temperature of 50°C and a phase ratio of O / A=1:0.8 to obtain first stage raffinate. Organic back-extraction was performed to obtain first stage back-extraction solution. The purified organic phase after back-extraction was reused, and the back-extraction solution was returned to the crude nickel sulfate solution for combined treatment. The first stage extraction was performed in 3 stages.

[0047] Table 4 Composition of each solution in first stage extraction, mg / L

[0048] (6) Two-stage extraction of impurities. P507 and light white oil are mixed uniformly at a mass ratio of 20:80, and the organic phase is subjected to sodium soap with 30% sodium hydroxide at a reaction temperature of 50°C and a phase ratio of O / A=15:1, and the saponification rate is 50%. Nickel sulfate containing 50g / L of nickel is used to carry out nickel soap at a temperature of 50°C and a phase ratio of O / A=6:1, and the obtained nickel soap containing phase is added to the P204 raffinate to carry out extraction at a reaction temperature of 50°C and a phase ratio of O / A=2:1, and a two-stage extraction raffinate is obtained. The organic back-extraction is obtained. The two-stage extraction is 2 stages. The two-stage extraction raffinate is a nickel sulfate solution. The purified organic phase after back-extraction is reused, and the back-extraction liquid is a nickel sulfate solution containing impurities, which is returned to the crude nickel sulfate solution for combined treatment. The nickel sulfate solution is evaporated and crystallized to obtain nickel sulfate for power batteries.

[0049] Table 5 Composition of each solution in two-stage extraction of impurities, mg / L

[0050] The nickel sulfate for power batteries meets the refined nickel sulfate standard of GB / T26524.

[0051] Table 6 Nickel sulfate for power batteries, %

[0052] Example 2 A method for preparing nickel sulfate for power batteries, comprising the following steps: Table 7 Composition of crude nickel sulfate, %

[0053] (1) One-stage hydroxylated iron removal. 200g of crude nickel sulfate is added to a beaker, 400ml of pure water is added, the temperature is raised to 85°C, stirring is carried out for 40 minutes, filtration is carried out, the filter residue is washed, and 1000ml of dissolved solution is obtained. The dissolved solution is added to a beaker, the temperature is raised to 85°C, compressed air is passed through the beaker while stirring, and the reaction time is 3 hours. 50g of β-hydroxylated nickel oxide (β-NiO(OH)) is slurried and added to the beaker, the pH is adjusted to 2.5, stirring is carried out, the reaction time is 1 hour, filtration is carried out, and the filter residue is washed to obtain 1000ml of one-stage hydroxylated solution and 76.3g of iron removal residue.

[0054] Table 8 Composition of crude nickel sulfate solution, mg / L

[0055] (2) Two-stage hydroxylated zinc removal. The one-stage hydroxylated solution is added to a beaker, the temperature is raised to 80°C, compressed air is passed through the beaker while stirring, the reaction time is 3 hours, the pH is 4.5, and filtration is carried out to wash the filter residue to obtain 1000ml of two-stage hydroxylated solution.

[0056] Table 9 Composition of hydroxylated solution, mg / L

[0057] (3) Impurity removal. The second-stage hydroxylated solution was added into a beaker, and the temperature was raised to 87°C. A sodium fluoride solution was prepared, and the amount of sodium fluoride added was 16 g. The solution was stirred for 3 hours, and the precipitation time was 1 hour. Filtration was performed to obtain 1000 ml of an impurity removal solution.

[0058] Table 10 Composition of the impurity removal solution, mg / L

[0059] (4) Preparation of β-hydroxyl nickel oxide. 1000 ml of the impurity removal solution was added into a beaker, and 50 g of sodium hydroxide and 200 ml of sodium hypochlorite solution were added. The solution was stirred for 1 hour, and filtration was performed to obtain β-hydroxyl nickel oxide (β-NiO(OH)) precipitate. The β-hydroxyl nickel oxide (β-NiO(OH)) precipitate was washed and dried, and then used for iron removal in the first-stage hydroxylation.

[0060] (5) First-stage extraction. P204 and light white oil were mixed in a mass ratio of 30:70, and sodium soap was prepared by using 30% sodium hydroxide at a reaction temperature of 55°C and a phase ratio of O / A=25:1. The saponification rate was 53%. Nickel soap was prepared by using nickel sulfate containing 50 g / L of nickel at a reaction temperature of 53°C and a phase ratio of O / A=8:1. The obtained nickel soap organic phase was added to the impurity removal solution to perform extraction at a reaction temperature of 50°C and a phase ratio of O / A=1:0.9 to obtain a first-stage raffinate. Organic back-extraction was performed to obtain a first-stage back-extraction solution. The back-extraction organic phase was reused, and the back-extraction solution was a mixed nickel sulfate solution which was returned to the crude nickel sulfate solution for combined treatment. The first-stage extraction was performed for 3 stages.

[0061] Table 11 Composition of each solution in the first-stage extraction, mg / L

[0062] (6) Second-stage extraction of impurities. P507 and light white oil were mixed in a mass ratio of 25:75, and sodium soap was prepared by using 30% sodium hydroxide at a reaction temperature of 50°C and a phase ratio of O / A=15:1. Nickel soap was prepared by using nickel sulfate containing 50 g / L of nickel at a temperature of 50°C and a phase ratio of O / A=5:1. The obtained nickel soap organic phase was added to the first-stage raffinate to perform extraction at a reaction temperature of 50°C and a phase ratio of O / A=2:1 to obtain a second-stage raffinate. Organic back-extraction was performed to obtain a second-stage back-extraction solution. The back-extraction organic phase was reused, and the back-extraction solution was a mixed nickel sulfate solution which was returned to the crude nickel sulfate solution for combined treatment. The second-stage extraction was performed for 2 stages. The second-stage raffinate was a nickel sulfate solution. The nickel sulfate solution was evaporated and crystallized to obtain nickel sulfate for power batteries.

[0063] Table 12 Composition of each solution in the second-stage extraction of impurities, mg / L

[0064] The nickel sulfate for power battery meets the refined nickel sulfate standard of GB / T26524.

[0065] Table 13 Nickel sulfate for power battery,

[0066] Example 3 A preparation method of the nickel sulfate for power battery comprises the following steps: Table 14 Component of the crude nickel sulfate,

[0067] (1) One-stage hydroxylation to remove iron. 200 g of the crude nickel sulfate is added into a beaker, 400 ml of pure water is added, the temperature is raised to 75 DEG C, and stirring is performed for 1 hour, then filtration is performed, and the filter residue is washed to obtain 1000 ml of a dissolved solution. The dissolved solution is added into a beaker, the temperature is raised to 75 DEG C, compressed air is introduced for stirring, and the reaction time is 2 hours. 50 g of β-hydroxyl nickel oxide (β-NiO(OH)) is slurried and added into the beaker, the pH is adjusted to 2.5, stirring is performed, the reaction time is 1 hour, then filtration is performed, and the filter residue is washed to obtain 1000 ml of a one-stage hydroxylation solution and 40.1 g of iron removal residue.

[0068] Table 15 Component of the crude nickel sulfate solution, mg / L

[0069] (2) Two-stage hydroxylation to remove zinc. The one-stage hydroxylation solution is added into a beaker, the temperature is raised to 80 DEG C, compressed air is introduced for stirring, the reaction time is 3 hours, the pH is 4.7, then filtration is performed, and the filter residue is washed to obtain 1000 ml of a two-stage hydroxylation solution.

[0070] Table 16 Component of the hydroxylation solution, mg / L

[0071] (3) Impurity removal. The two-stage hydroxylation solution is added into a beaker, the temperature is raised to 82 DEG C, a sodium fluoride solution is prepared, the addition amount of the sodium fluoride is 16 g, stirring is performed, the reaction time is 3 hours, the sedimentation time is 1 hour, then filtration is performed, and 1000 ml of an impurity removal solution is obtained.

[0072] Table 17 Component of the impurity removal solution, mg / L

[0073] (4) Preparation of β-hydroxyl nickel oxide. 1000 ml of the impurity removal solution is added into a beaker, 50 g of sodium hydroxide and 200 ml of sodium hypochlorite solution are added, stirring is performed for 1 hour, then filtration is performed to obtain β-hydroxyl nickel oxide (β-NiO(OH)) precipitate, and the β-hydroxyl nickel oxide (β-NiO(OH)) precipitate is washed and dried, and then used for one-stage hydroxylation to remove iron.

[0074] (5) First-stage extraction. P204 and light white oil are mixed uniformly at a mass ratio of 30:70, and the organic phase is subjected to sodium saponification with 30% sodium hydroxide at a reaction temperature of 51°C and a phase ratio of O / A=23:1. The nickel saponification is performed with a nickel sulfate solution containing 50 g / L of nickel at a reaction temperature of 55°C and a phase ratio of O / A=8:1, and the obtained nickel saponification organic phase is added to the impurity removal liquid to perform extraction at a reaction temperature of 50°C and a phase ratio of O / A=1:0.9 to obtain a first-stage raffinate. The organic phase after purification of the back-extraction is reused, and the back-extraction liquid is a nickel sulfate solution containing impurities, which is returned to the crude nickel sulfate solution and treated. The first-stage extraction has 3 stages.

[0075] Table 18 Composition of each solution in the first-stage extraction, mg / L

[0076] (6) Second-stage extraction of impurities. P507 and light white oil are mixed uniformly at a mass ratio of 25:75, and the organic phase is subjected to sodium saponification with 30% sodium hydroxide at a reaction temperature of 50°C and a phase ratio of O / A=15:1. The nickel saponification is performed with a nickel sulfate solution containing 50 g / L of nickel at a temperature of 50°C and a phase ratio of O / A=5:1, and the obtained nickel saponification organic phase is added to the first-stage raffinate to perform extraction at a reaction temperature of 50°C and a phase ratio of O / A=2:1 to obtain a second-stage raffinate. The organic phase after purification of the back-extraction is reused, and the back-extraction liquid is a nickel sulfate solution containing impurities, which is returned to the crude nickel sulfate solution and treated. The second-stage extraction has 2 stages. The second-stage raffinate is a nickel sulfate solution. The nickel sulfate solution is evaporated and crystallized to obtain a nickel sulfate for power batteries.

[0077] Table 19 Composition of each solution in the second-stage extraction of impurities, mg / L

[0078] The nickel sulfate for power batteries meets the refined nickel sulfate standard of GB / T26524.

[0079] Table 20 Nickel sulfate for power batteries, %

[0080] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing nickel sulfate for power batteries, characterized in that: The method comprises the following steps: The crude nickel sulfate is dissolved in water, and impurities are removed by filtration. Then, compressed air is introduced into the solution for the first time at a set temperature, and the solution is stirred for a set time. Then, the β-hydroxyl nickel oxide is slurried and added into the solution, and the solution is reacted for a set time. After filtration, a first hydroxylated solution and iron removal residue are obtained. The first hydroxylated solution is heated to a set temperature, and compressed air is introduced into the solution for the second time. After reaction, the solution is filtered to obtain a second hydroxylated solution and zinc removal residue. The second hydroxylated solution is heated, and a sodium fluoride solution is added into the solution. After reaction for a set time, the solution is filtered to obtain a removal solution and removal residue. P204 and light white oil are mixed in a certain proportion, and sodium soap and nickel soap are prepared. The obtained nickel soap organic phase is added into the removal solution to perform a first extraction, and a first extraction residue is obtained. P507 and light white oil are mixed in a certain proportion, and sodium soap and nickel soap are prepared. The obtained nickel soap organic phase is added into the first extraction residue to perform a second extraction, and a second extraction residue is obtained. The second extraction residue is evaporated and crystallized to obtain the nickel sulfate for power batteries.

2. The preparation method of nickel sulfate for power batteries according to claim 1, characterized in that: The temperature for introducing the compressed air for the first time is 70-90℃, and the reaction time is 1-3h. Preferably, the temperature for introducing the compressed air for the first time is 75-85℃.

3. The preparation method of nickel sulfate for power batteries according to claim 1, characterized in that: After the β-hydroxyl nickel oxide is slurried and added into the solution, the pH value is adjusted to 1-3, and the solution is stirred for 0.5-1.5h.

4. The preparation method of nickel sulfate for power batteries according to claim 1, characterized in that: The temperature for heating the first hydroxylated solution is 70-90℃, and the compressed air is introduced for the second time. After stirring for 1-3h, the solution is filtered to obtain a second hydroxylated solution and zinc removal residue. Preferably, the temperature for introducing the compressed air for the second time is 75-85℃.

5. The method for preparing nickel sulfate for power batteries according to claim 1, characterized in that: After the sodium fluoride solution is added, the reaction temperature is 80-90℃, and the reaction time is 2-3h.

6. The method for preparing nickel sulfate for power batteries according to claim 1, characterized in that: The mass ratio of P204 and light white oil is 20-30:70-80.

7. The method for preparing nickel sulfate for power batteries according to claim 1, characterized in that: The temperature for preparing the sodium soap and the nickel soap is 45-55℃.

8. The method for preparing nickel sulfate for power batteries according to claim 1, characterized in that: The mass ratio of P507 and light white oil is 15-25:70-85.

9. The method for preparing nickel sulfate for power batteries according to claim 1, characterized in that: During the first extraction, the O / A is 1:0.5-1.5, and preferably 1:0.7-0.

9.

10. The method for preparing nickel sulfate for power batteries according to claim 1, characterized in that: During the second extraction, the O / A is 1-5:1, and preferably 1-3:1.

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