Preparation method of battery-grade nickel sulfate solution

Abstract

The invention provides a preparation method of a battery-grade nickel sulfate solution, and belongs to the technical field of hydrometallurgy, and the battery-grade nickel sulfate solution is prepared by sequentially performing leaching, iron and aluminum removal, P204 impurity extraction, P507 cobalt extraction, P507 or C272 magnesium extraction, nickel sulfate evaporative crystallization and re-dissolution treatment on a nickel hydroxide cobalt raw material. The requirement on the impurity content in the nickel sulfate solution obtained in the extraction and purification process is low, the indexes in the extraction process are easier to realize, and the requirement on impurity ions in the extraction process is reduced; the requirements of the extraction section are reduced, the stage number of the extraction process can be reduced, the backwashing ratio of the extraction process can be reduced, the productivity of unit equipment is improved, and the acid-base consumption of the whole preparation process is reduced compared with the prior art, so that the production cost is effectively reduced; silicon, fluorine, phosphorus, COD (Chemical Oxygen Demand) and the like are left in the crystallization mother liquor, so that the quality of the battery-grade nickel sulfate solution is improved; and the method provided by the invention has the advantages of reduced sodium sulfate wastewater generation amount and good environmental protection benefit.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and more particularly to a method for preparing a battery-grade nickel sulfate solution. Background Art

[0002] With the rapid development of the new energy vehicle industry, the demand for lithium-ion batteries containing nickel, cobalt and manganese has increased significantly, driving the rapid growth of battery-grade nickel sulfate consumption. The preparation of battery-grade nickel sulfate solution using nickel cobalt hydroxide (MHP) as raw material has become a hot topic today.

[0003] At present, the main processes for preparing battery-grade nickel sulfate solution using MHP as raw material are as follows:

[0004] The first method involves leaching MHP, removing iron and aluminum, extracting impurities with P204, extracting cobalt and magnesium with P507, and then stripping them in stages to produce pure cobalt sulfate solution. This process, which consumes large amounts of liquid caustic soda and sulfuric acid during the complete extraction and stripping process, is costly and requires significant investment.

[0005] The second type: MHP is treated by leaching - iron and aluminum removal - P204 extraction - P507 cobalt extraction - P507 / C272 magnesium extraction to obtain nickel sulfate solution and cobalt sulfate solution respectively. Since the nickel sulfate solution is a raffinate, a small amount of impurities such as silicon and fluorine in the leaching process cannot be effectively removed in various purification processes, and the extractant and diluent used in the extraction process will cause the nickel sulfate solution to contain a small amount of impurities such as phosphorus and COD. These impurities will affect the product quality of the ternary precursor. At the same time, since the raffinate is directly used as the raw material for the synthesis of the ternary precursor, the requirements for impurities in the solution are high, so the number of stages of the extraction process is long, the investment is large, or the backwash ratio of the extraction process is larger, the production capacity of the unit equipment is reduced, the acid and alkali consumption of the process is large, the economic benefits are poor, the amount of wastewater generated is large, and the environmental benefits are poor.

[0006] In summary, the current process of preparing battery-grade nickel sulfate solution through nickel cobalt hydroxide has problems such as high production cost, large investment, large amount of wastewater generated, and poor environmental benefits.

[0007] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0008] In view of the above problems, the purpose of the present invention is to provide a method for preparing a battery-grade nickel sulfate solution, so as to solve the problems in the prior art of preparing a battery-grade nickel sulfate solution by nickel cobalt hydroxide, such as high production cost, large amount of wastewater generated, and poor environmental benefits.

[0009] The present invention provides a method for preparing a battery-grade nickel sulfate solution, comprising the following steps:

[0010] Acid leaching is performed on the nickel-cobalt hydroxide raw material, and nickel-containing solution and leaching residue are obtained after filter pressing;

[0011] adding an alkaline substance to the nickel-containing solution to remove iron and aluminum, and obtaining an iron- and aluminum-removed solution and iron-aluminum slag after filter pressing;

[0012] performing cooling and fine filtration on the solution after iron and aluminum removal to obtain a cooled and finely filtered solution;

[0013] Using P204 to extract and remove impurities from the cooled fine filtration solution to obtain a first raffinate;

[0014] extracting cobalt from the first raffinate using P507 to obtain a second raffinate;

[0015] extracting magnesium from the second raffinate using P507 or C272 to obtain a third raffinate;

[0016] The third raffinate is subjected to deoiling and fine filtration in sequence, and then evaporation-cooling crystallization is performed to obtain wet nickel sulfate and crystallization mother liquor;

[0017] Pure water is used to dissolve the wet nickel sulfate to obtain a battery-grade nickel sulfate solution.

[0018] In addition, a preferred solution is that, in the process of subjecting the nickel-cobalt hydroxide raw material to acid leaching and obtaining the nickel-containing solution and leaching residue after filter pressing,

[0019] Sulfuric acid solution is used as the leaching agent;

[0020] The acid leaching treatment has a leaching temperature of 60-85° C., a leaching time of 2-4 hours, a pH value at the leaching end point of 1-2, and a liquid-to-solid ratio of 3-6:1.

[0021] In addition, a preferred solution is that, in the process of adding alkaline substances to the nickel-containing solution to remove iron and aluminum, and obtaining the iron-aluminum-removed solution and iron-aluminum slag after filter pressing,

[0022] The time for the iron and aluminum removal treatment is 4-8 hours; the temperature is 80-90° C.; and the end point pH value is 4.5-5.5.

[0023] In addition, a preferred solution is that the alkaline substance is sodium carbonate or MHP slurry.

[0024] In addition, a preferred embodiment is that the cooling and fine filtering of the solution after the iron and aluminum removal to obtain the cooled fine filtered solution comprises:

[0025] The temperature of the solution after iron and aluminum removal is reduced to 35-55°C;

[0026] The solid in the cooled solution after iron and aluminum removal is finely filtered to obtain a cooled finely filtered solution.

[0027] In addition, a preferred solution is that the process of extracting and removing impurities from the cooled fine filtration solution using P204 to obtain the first raffinate further includes:

[0028] Performing a first washing treatment on the first loaded organic obtained after the extraction and impurity removal treatment;

[0029] performing valuable metal stripping treatment on the first washed organic phase obtained after the first washing treatment;

[0030] The first stripping solution obtained by the valuable metal stripping treatment is subjected to a valuable metal precipitation treatment to obtain valuable metals.

[0031] In addition, a preferred solution is that the process of extracting cobalt from the first raffinate using P507 to obtain a second raffinate further includes:

[0032] performing a second washing treatment on the second loaded organic phase obtained after the cobalt extraction treatment;

[0033] performing a cobalt stripping treatment on the second washed organic phase obtained after the second washing treatment;

[0034] The second stripping solution obtained by the stripping of cobalt is sequentially subjected to deoiling and fine filtration treatments to obtain a battery-grade cobalt sulfate solution.

[0035] In addition, a preferred solution is that the process of extracting magnesium from the second raffinate using P507 or C272 to obtain a third raffinate further includes:

[0036] performing a third washing treatment on the third loaded organic obtained after the magnesium extraction treatment;

[0037] Performing a magnesium stripping treatment on the third washed organic obtained after the third washing treatment;

[0038] The third stripping solution obtained by the stripping magnesium treatment is subjected to a magnesium recovery treatment step.

[0039] In addition, a preferred solution is that the step of subjecting the third raffinate to deoiling and fine filtration in sequence and then adopting an evaporation-cooling crystallization method to obtain wet nickel sulfate and crystallization mother liquor comprises:

[0040] Pre-deoiling the third raffinate by clarification, flotation or coalescence;

[0041] performing deep deoiling on the third raffinate after the pre-deoiling treatment by means of activated carbon adsorption;

[0042] performing fine filtration on the third raffinate after deep oil removal;

[0043] The third raffinate after the fine filtration is concentrated by an MVR or multi-effect evaporation process, and the concentrated solution obtained after the concentration is sent to a crystallization kettle for intermittent cooling crystallization or to a continuous crystallizer for continuous cooling crystallization to obtain nickel sulfate slurry after cooling crystallization;

[0044] The nickel sulfate slurry after cooling and crystallization is centrifuged to separate the nickel sulfate slurry into solid and liquid, thereby obtaining wet nickel sulfate and crystallization mother liquor.

[0045] In addition, a preferred solution is that after the third raffinate is subjected to deoiling treatment and fine filtration treatment in sequence and then subjected to evaporation-cooling crystallization to obtain wet nickel sulfate and crystallization mother liquor, the process further comprises:

[0046] The crystallization mother liquor is returned to the extraction and impurity removal process as the impurity extraction stock solution, or is returned to the extraction and impurity removal process as the pre-soap conversion liquid in the extraction and impurity removal process, or is returned to the cobalt extraction process as the pre-soap conversion liquid in the cobalt extraction process, or is returned to the magnesium extraction process as the pre-soap conversion liquid in the magnesium extraction process.

[0047] From the above technical scheme, it can be seen that the preparation method of the battery-grade nickel sulfate solution provided by the present invention is to prepare the battery-grade nickel sulfate solution by sequentially leaching the nickel hydroxide cobalt raw material, removing iron and aluminum, extracting impurities with P204, extracting cobalt with P507, extracting magnesium with P507 or C272, evaporating and crystallizing the nickel sulfate, and re-dissolving the nickel sulfate raw material. The impurity content in the nickel sulfate solution obtained in the extraction and purification process is low, and the indicators of the extraction process are easier to achieve. The magnesium ion content required in the conventional extraction process is generally less than 10ppm. However, the present invention prepares the nickel sulfate solution by evaporating and crystallizing the nickel sulfate and re-dissolving the nickel sulfate after extraction, achieving The crude nickel sulfate solution is further purified, and the magnesium ion content in the solution after extraction is required to be less than 100 ppm. Since the requirements for the extraction section are reduced, the number of stages in the extraction process can also be reduced, thereby reducing investment. The backwash ratio in the extraction process can be reduced, thereby increasing the production capacity of the unit equipment, and reducing the acid and alkali consumption in the entire preparation process compared with the prior art, thereby effectively reducing production costs. Silicon, fluorine, phosphorus, COD, etc. are retained in the crystallization mother liquor, thereby improving the quality of the battery-grade nickel sulfate solution. In addition, the method provided by the present invention reduces the amount of sodium sulfate wastewater generated, and has the advantage of good environmental benefits.

[0048] In order to achieve the above and related purposes, and one or more aspects of the present invention include the features described in detail below. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all of these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] By referring to the following description in conjunction with the accompanying drawings, and with a more complete understanding of the present invention, other objects and results of the present invention will become more apparent and easily understood.

[0050] Figure 1 The figure is a flow chart of a method for preparing a battery-grade nickel sulfate solution according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may be practiced without these specific details.

[0052] In view of the problems of high production cost and large amount of wastewater generated, resulting in poor environmental benefits, in the process of preparing battery-grade nickel sulfate solution by nickel cobalt hydroxide in the above-mentioned prior art, a method for preparing battery-grade nickel sulfate solution is proposed.

[0053] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] To illustrate the preparation method of the battery-grade nickel sulfate solution provided by the present invention, Figure 1 The flowchart of the method for preparing a battery-grade nickel sulfate solution according to an embodiment of the present invention is shown.

[0055] The method for preparing a battery-grade nickel sulfate solution provided by the present invention comprises the following steps:

[0056] Step S1: Acid leaching treatment is performed on the nickel cobalt hydroxide raw material, and nickel-containing solution and leaching residue are obtained after filter pressing.

[0057] As a preferred embodiment of the present invention, in the process of subjecting the nickel-cobalt hydroxide raw material to acid leaching treatment and obtaining the nickel-containing solution and leaching residue after filter pressing,

[0058] Sulfuric acid solution is used as the leaching agent;

[0059] The leaching temperature of the acid leaching treatment is 60-85°C; the leaching time is 2-4 hours; the pH value at the leaching end point is 1-2, and the leaching liquid-solid ratio is 3-6:1.

[0060] Specifically, sulfuric acid solution is used as the leaching agent, and other impurities will not be introduced; the leaching temperature of the acid leaching treatment is preferably 60-85°C, for example, 60°C, 70°C, 80°C, 85°C, etc.; the leaching time is preferably 2-4h, for example, 2h, 3h, 4h, etc.; the pH value at the leaching endpoint is preferably but not limited to 1-2, and the liquid-to-solid ratio of the leaching is preferably but not limited to 3-6:1.

[0061] Step S2: adding an alkaline substance to the nickel-containing solution to remove iron and aluminum, and obtaining an iron- and aluminum-removed solution and iron-aluminum slag after filter pressing.

[0062] As a preferred embodiment of the present invention, in the process of adding alkaline substances to the nickel-containing solution to remove iron and aluminum, and obtaining the iron-aluminum-removed solution and iron-aluminum slag after filter pressing,

[0063] The time for iron and aluminum removal treatment is 4-8 hours; the temperature is 80-90°C; and the end point pH value is 4.5-5.5.

[0064] As a preferred embodiment of the present invention, the alkaline substance is sodium carbonate or MHP slurry.

[0065] Specifically, an alkaline substance is added to the nickel solution to remove iron and aluminum from the solution. For example, an alkaline MHP slurry is used to remove iron and aluminum from the nickel solution. This process consumes virtually no other alkali and simultaneously utilizes the acidity of the solution to achieve cyclic leaching of MHP. Sodium carbonate can also be used to remove iron and aluminum from the nickel solution, ensuring that the final iron-aluminum slag contains low levels of valuable metals such as nickel and cobalt.

[0066] It should be noted that the time for the iron and aluminum removal treatment is preferably, but not limited to, 4-8 hours; the temperature is preferably, but not limited to, 80-90° C.; and the endpoint pH value is preferably, but not limited to, 4.5-5.5.

[0067] Step S3: Cool and finely filter the solution after removing iron and aluminum to obtain a cooled finely filtered solution.

[0068] As a preferred embodiment of the present invention, the solution after iron and aluminum removal is subjected to cooling and fine filtration to obtain a cooled and finely filtered solution, comprising:

[0069] Lower the temperature of the solution after iron and aluminum removal to 35-55°C;

[0070] The solid in the cooled solution after iron and aluminum removal is finely filtered to obtain a cooled finely filtered solution.

[0071] Specifically, the cooling fine filtration treatment is to reduce the temperature of the solution after iron and aluminum removal to 35-55°C. The fine filtration is to filter a small amount of solids in the solution to reduce the solids, silica gel, etc. from entering the subsequent extraction system, thereby reducing their impact on the subsequent extraction process.

[0072] Step S4: using P204 to extract and remove impurities from the cooled fine filtration solution to obtain a first raffinate.

[0073] As a preferred embodiment of the present invention, the process of extracting and removing impurities from the cooled fine filtration solution using P204 to obtain the first raffinate further includes:

[0074] Performing a first washing treatment on the first loaded organic obtained after the extraction and impurity removal treatment;

[0075] performing valuable metal stripping treatment on the first washed organic solution obtained after the first washing treatment;

[0076] The first stripping liquid obtained by the valuable metal stripping treatment is subjected to a valuable metal precipitation treatment to obtain the valuable metal.

[0077] Specifically, P204 is di(2-ethylhexyl) phosphate; used as an organic solvent, it is an acidic extractant and an intermediate in organic synthesis. It exists in kerosene as a hydrogen-bonded dimer structure to mask its polar phosphate groups, and typically reacts in a dimerized form when complexed with metal ions. P204 is used to extract and remove impurities from the cooled fine filtration solution, yielding a first loaded organic solution containing impurities (typically valuable metals such as copper, manganese, and zinc) and a first raffinate containing nickel. The first loaded organic solution is washed to yield a first washed organic solution, which undergoes valuable metal stripping and precipitation to yield valuable metals. For example, stripping copper and manganese to yield a stripped copper and manganese solution, which is then subjected to copper-manganese precipitation to yield copper-manganese. Stripping zinc and aluminum from the stripped copper and manganese organic solution yields a stripped zinc and aluminum solution, which is then subjected to zinc-aluminum precipitation to yield zinc and aluminum, thereby increasing yields and reducing costs.

[0078] Step S5: using P507 to extract cobalt from the first raffinate to obtain a second raffinate.

[0079] As a preferred embodiment of the present invention, the process of extracting cobalt from the first raffinate using P507 to obtain the second raffinate further includes:

[0080] Performing a second washing treatment on the second loaded organic obtained after the cobalt extraction treatment;

[0081] Performing a cobalt stripping treatment on the second washed organic obtained after the second washing treatment;

[0082] The second stripping solution obtained by stripping cobalt is subjected to deoiling and fine filtration in sequence to obtain a battery-grade cobalt sulfate solution.

[0083] Specifically, P507 is an extractant, and its full name is 2-ethylhexyl mono-2-ethylhexyl phosphate. It is a colorless or slightly yellow oily transparent liquid that is soluble in organic solvents such as alcohol, benzene, and ketone, but insoluble in water. The first raffinate is subjected to cobalt extraction with P507 to obtain a second loaded organic solution containing cobalt and a second raffinate containing nickel. The second loaded organic solution containing cobalt is subjected to a second washing treatment to obtain a second washed organic solution, and the second washed organic solution is subjected to a cobalt stripping treatment to obtain a second stripping solution. The second stripping solution is then subjected to pre-degreasing treatment by clarification or ultrasonication (flotation) or coagulation or other degreasing methods, and then deep degreasing treatment is performed by activated carbon adsorption. After filter pressing and fine filtration, a cobalt sulfate solution is obtained, which can be used as a battery precursor raw material. This further reduces costs and increases profits.

[0084] Step S6: extracting magnesium from the second raffinate using P507 or C272 to obtain a third raffinate.

[0085] As a preferred embodiment of the present invention, the process of extracting magnesium from the second raffinate using P507 or C272 to obtain a third raffinate further includes:

[0086] Performing a third washing treatment on the second loaded organic obtained after the magnesium extraction treatment;

[0087] Performing stripping magnesium treatment on the third washed organic obtained after the third washing treatment;

[0088] The third stripping solution obtained by stripping magnesium is subjected to a magnesium recovery process.

[0089] Specifically, C272, or C272 extractant, is primarily composed of di(2,4,4-trimethylpentyl)phosphonic acid, which is completely soluble in aromatic and aliphatic diluents and is stable under heating, acidic, and alkaline conditions. The second raffinate is treated with P507 or C272 to extract magnesium, producing a third organic solvent containing magnesium and a third raffinate containing nickel. The third organic solvent is then washed and stripped for magnesium, resulting in a third stripping solution that is then fed into a magnesium recovery process to produce metallic magnesium, thereby increasing profitability.

[0090] Step S7: The third raffinate is subjected to deoiling treatment and fine filtration treatment in sequence, and then an evaporation-cooling crystallization treatment method is adopted to obtain wet nickel sulfate and crystallization mother liquor.

[0091] As a preferred embodiment of the present invention, the third raffinate is subjected to deoiling treatment and fine filtration treatment in sequence, and then an evaporation-cooling crystallization method is used to obtain wet nickel sulfate and a crystallization mother liquor, which comprises:

[0092] Pre-deoiling the third raffinate by clarification, flotation or coalescence;

[0093] The third raffinate after the pre-deoiling treatment is subjected to deep deoiling treatment by means of activated carbon adsorption;

[0094] Performing fine filtration on the third raffinate after deep oil removal;

[0095] The third raffinate after fine filtration is concentrated by using an MVR or multi-effect evaporation process, and the concentrated solution obtained after the concentration treatment is sent to a crystallization kettle for intermittent cooling crystallization or sent to a continuous crystallizer for continuous cooling crystallization to obtain nickel sulfate slurry after cooling crystallization;

[0096] The nickel sulfate slurry after cooling and crystallization is centrifuged to separate the nickel sulfate slurry into solid and liquid to obtain wet nickel sulfate and crystallization mother liquor.

[0097] Step S8: dissolving the wet nickel sulfate with pure water to obtain a battery-grade nickel sulfate solution.

[0098] As a preferred embodiment of the present invention, after the third raffinate is subjected to deoiling treatment and fine filtration in sequence, and then subjected to evaporation-cooling crystallization to obtain wet nickel sulfate and crystallization mother liquor, the process further comprises:

[0099] The crystallization mother liquor is returned to the extraction and impurity removal process as the impurity extraction stock solution, or is returned to the extraction and impurity removal process as the pre-soap conversion solution in the extraction and impurity removal process, or is returned to the cobalt extraction process as the pre-soap conversion solution in the cobalt extraction process, or is returned to the magnesium extraction process as the pre-soap conversion solution in the magnesium extraction process.

[0100] Specifically, the present invention prepares a battery-grade nickel sulfate solution by evaporating, crystallizing, and then re-dissolving the raffinate, thereby not only separating the valuable metal nickel from impurities such as silicon, fluorine, phosphorus, and COD in the raffinate, but also improving the product quality of the nickel sulfate solution. At the same time, the requirements for the impurity content in the extraction process are reduced, and the indicators of the extraction process are easier to achieve. In this way, the number of extraction stages can be reduced and the investment is lowered. By sending the crystallization mother liquor to the extraction process, the impurities in the evaporation and crystallization process are discharged, thereby ensuring the smooth progress of the crystallization process.

[0101] In the above steps, P204, P507, and C272 generally need to be saponified with sodium hydroxide solution. The saponified organic can be soaped using the diluted crystallization mother liquor, and the high-concentration sodium sulfate solution produced by soaping can be sent to the sodium sulfate solution pretreatment process. The organic after soaping is countercurrent extracted with the extraction solution. The organic containing impurities can be first washed with sulfuric acid to obtain the washing liquid after nickel is incorporated into the extraction solution. The organic after washing is then stripped with sulfuric acid, and the stripping liquid is sent to chemical precipitation, deoiling and fine filtration and other processing steps. After stripping of P204 and P507, the organic uses dilute hydrochloric acid to remove iron, and after stripping iron, the organic uses pure water to wash chlorine. The organic after washing chlorine is saponified and recycled. After stripping C272, the organic uses dilute sulfuric acid to remove iron, and after stripping iron, the organic uses pure water to wash sulfur. The organic after washing sulfur is saponified and recycled.

[0102] A battery-grade nickel sulfate solution is prepared by sequentially subjecting nickel hydroxide and cobalt raw materials to leaching, iron and aluminum removal, P204 extraction, P507 cobalt extraction, P507 or C272 magnesium extraction, nickel sulfate evaporation and crystallization, and re-dissolution treatment. The impurity content in the nickel sulfate solution obtained in the extraction and purification process is required to be low, and the extraction process indicators are easier to achieve. The conventional extraction process generally requires a magnesium ion content of less than 10 ppm. However, the present invention prepares the nickel sulfate solution by nickel sulfate evaporation and crystallization-re-dissolution after extraction, thereby achieving further purification of the crude nickel sulfate solution. The magnesium ion content in the solution after extraction is required to be less than 100 ppm. Since the requirements of the extraction section are reduced, the number of extraction stages can also be reduced, thereby reducing investment. The backwash ratio of the extraction process can be reduced, thereby increasing the production capacity per unit equipment, and reducing the acid and alkali consumption of the entire preparation process compared to the prior art, effectively reducing production costs. Silicon, fluorine, phosphorus, COD, etc. are retained in the crystallization mother liquor, thereby improving the quality of the battery-grade nickel sulfate solution. In addition, the method provided by the present invention reduces the amount of sodium sulfate wastewater generated and has the advantages of good environmental benefits.

[0103] In order to better explain the preparation method of the battery-grade nickel sulfate solution provided by the present invention and the technical effects achieved thereby, specific examples are carried out to verify the following:

[0104] In the following specific embodiments of the present invention, MHP (i.e., nickel cobalt hydroxide) is used as a raw material, and the nickel sulfate solution is prepared using the method for preparing a battery-grade nickel sulfate solution provided above. The main elemental composition of the MHP (dry basis) raw material used in the present invention is shown in Table 1, and the content of each element is expressed in %.

[0105] element Ni Co Cu Fe Zn Mn Al Ca content% 38.0 3.6 0.1 0.2 0.85 5.9 0.1 0.15 element Mg Si S Sc F Cl Na content% 2.0 0.7 5.02 0.04 0.05 0.04 0.2

[0106] Table 1

[0107] The only difference between the examples is the extraction conditions shown in Table 2 below; all other parameters are the same.

[0108] Parameters under different conditions Example 1 Example 2 Example 3 P507 magnesium extraction series 4 8 6 P507 magnesium extraction washing series 4 8 6 P507 magnesium extraction backwash ratio 0.25 0.1 0.2 P507 Magnesium ion concentration in magnesium extraction residue 95 93 80 Nickel sulfate crystallization rate 0.6 0.62 0.55 Ratio of nickel to impurities in nickel sulfate solution 5500 5600 5700 Parameters under different conditions Example 4 Example 5 Example 6 C272 magnesium extraction series 3 6 5 C272 magnesium extraction washing series 3 6 5 C272 magnesium extraction backwash ratio 0.25 0.1 0.2 C272 Magnesium ion concentration in magnesium extraction residue 96 90 78 Nickel sulfate crystallization rate 0.65 0.6 0.6 Ratio of nickel to impurities in nickel sulfate solution 5400 5550 5750

[0109] Table 2

[0110] It should be noted that the above specific embodiments are only for the purpose of illustrating the effectiveness of the method for preparing the battery-grade nickel sulfate solution provided by the present invention in an actual experimental process, and do not limit the technical solution provided by the present invention.

[0111] It can be seen from the above specific embodiments that the preparation method of the battery-grade nickel sulfate solution provided by the present invention is to prepare the battery-grade nickel sulfate solution by sequentially leaching the nickel hydroxide cobalt raw material, removing iron and aluminum, extracting impurities with P204, extracting cobalt with P507, extracting magnesium with P507 or C272, evaporating and crystallizing the nickel sulfate, and re-dissolving the nickel sulfate raw material. The requirements for the impurity content in the nickel sulfate solution obtained in the extraction and purification process are low, the indicators of the extraction process are easier to achieve, the requirements for impurity ions in the extraction process are reduced, and silicon, fluorine, phosphorus, COD, etc. are retained in the crystallization mother liquor, thereby improving the quality of the battery-grade nickel sulfate solution; since the requirements for the extraction section are reduced, the number of stages of the extraction process can also be reduced, thereby reducing investment; and the backwash ratio of the extraction process can be reduced, thereby increasing the production capacity of the unit equipment, and reducing the acid and alkali consumption of the entire preparation process compared to the prior art, thereby further reducing the production cost; and the method provided by the present invention reduces the amount of sodium sulfate wastewater generated, and has good environmental benefits.

[0112] The method for preparing a battery-grade nickel sulfate solution according to the present invention has been described above by way of example with reference to the accompanying drawings. However, those skilled in the art will appreciate that various modifications may be made to the method for preparing a battery-grade nickel sulfate solution according to the present invention without departing from the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a battery-grade nickel sulfate solution, characterized in that: The steps include: Acid leaching is performed on the nickel-cobalt hydroxide raw material, and nickel-containing solution and leaching residue are obtained after filter pressing; adding an alkaline substance to the nickel-containing solution to remove iron and aluminum, and obtaining an iron- and aluminum-removed solution and iron-aluminum slag after filter pressing; performing cooling and fine filtration on the solution after iron and aluminum removal to obtain a cooled and finely filtered solution; Using P204 to extract and remove impurities from the cooled fine filtration solution to obtain a first raffinate; extracting cobalt from the first raffinate using P507 to obtain a second raffinate; extracting magnesium from the second raffinate using P507 or C272 to obtain a third raffinate; The third raffinate is subjected to deoiling and fine filtration in sequence, and then evaporation-cooling crystallization is performed to obtain wet nickel sulfate and crystallization mother liquor; Pure water is used to dissolve the wet nickel sulfate to obtain a battery-grade nickel sulfate solution.

2. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein In the process of subjecting the nickel-cobalt hydroxide raw material to acid leaching and obtaining the nickel-containing solution and leaching residue after filter pressing, Sulfuric acid solution is used as the leaching agent; The acid leaching treatment has a leaching temperature of 60-85° C., a leaching time of 2-4 hours, a pH value at the leaching end point of 1-2, and a liquid-to-solid ratio of 3-6:

1.

3. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein In the process of adding alkaline substances to the nickel-containing solution to remove iron and aluminum, and obtaining the iron- and aluminum-removed solution and iron-aluminum slag after filter pressing, The time for the iron and aluminum removal treatment is 4-8 hours; the temperature is 80-90° C.; and the end point pH value is 4.5-5.

5.

4. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein The alkaline substance is sodium carbonate or MHP slurry.

5. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein The cooling and fine filtering of the solution after the iron and aluminum removal to obtain the cooled fine filtered solution comprises: The temperature of the solution after iron and aluminum removal is reduced to 35-55°C; The solid in the cooled solution after iron and aluminum removal is finely filtered to obtain a cooled finely filtered solution.

6. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein The process of using P204 to extract and remove impurities from the cooled fine filtration solution to obtain a first raffinate further includes: Performing a first washing treatment on the first loaded organic obtained after the extraction and impurity removal treatment; performing valuable metal stripping treatment on the first washed organic phase obtained after the first washing treatment; The first stripping solution obtained by the valuable metal stripping treatment is subjected to a valuable metal precipitation treatment to obtain valuable metals.

7. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein The process of extracting cobalt from the first raffinate using P507 to obtain a second raffinate further includes: performing a second washing treatment on the second loaded organic phase obtained after the cobalt extraction treatment; performing a cobalt stripping treatment on the second washed organic phase obtained after the second washing treatment; The second stripping solution obtained by the stripping of cobalt is sequentially subjected to deoiling and fine filtration treatments to obtain a battery-grade cobalt sulfate solution.

8. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein: The process of extracting magnesium from the second raffinate using P507 or C272 to obtain a third raffinate further includes: performing a third washing treatment on the third loaded organic obtained after the magnesium extraction treatment; Performing a magnesium stripping treatment on the third washed organic obtained after the third washing treatment; The third stripping solution obtained by the stripping magnesium treatment is subjected to a magnesium recovery treatment step.

9. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein: The method of subjecting the third raffinate to deoiling and fine filtration in sequence and then adopting an evaporation-cooling crystallization method to obtain wet nickel sulfate and a crystallization mother liquor comprises: Pre-deoiling the third raffinate by clarification, flotation or coalescence; performing deep deoiling on the third raffinate after the pre-deoiling treatment by means of activated carbon adsorption; performing fine filtration on the third raffinate after deep oil removal; The third raffinate after the fine filtration is concentrated by an MVR or multi-effect evaporation process, and the concentrated solution obtained after the concentration is sent to a crystallization kettle for intermittent cooling crystallization or to a continuous crystallizer for continuous cooling crystallization to obtain nickel sulfate slurry after cooling crystallization; The nickel sulfate slurry after cooling and crystallization is centrifuged to separate the nickel sulfate slurry into solid and liquid, thereby obtaining wet nickel sulfate and crystallization mother liquor.

10. The method for preparing a battery-grade nickel sulfate solution according to claim 1, wherein: After the third raffinate is subjected to deoiling and fine filtration in sequence, and then evaporation-cooling crystallization is used to obtain wet nickel sulfate and crystallization mother liquor, the method further includes: The crystallization mother liquor is returned to the extraction and impurity removal process as the impurity extraction stock solution, or is returned to the extraction and impurity removal process as the pre-soap conversion liquid in the extraction and impurity removal process, or is returned to the cobalt extraction process as the pre-soap conversion liquid in the cobalt extraction process, or is returned to the magnesium extraction process as the pre-soap conversion liquid in the magnesium extraction process.

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