Method for removing silicon from nickel sulfate solution preparation process

Abstract

The invention provides a method for removing silicon in a nickel sulfate solution preparation process, which comprises the following steps: a leaching process: carrying out acid leaching on a nickel raw material to obtain an acid-leached solution; an extraction and impurity removal process: performing extraction and impurity removal on the acid-leached liquid to obtain strip liquor containing impurities and raffinate containing nickel; an evaporative crystallization process: putting the raffinate into evaporation equipment for evaporative crystallization, and performing solid-liquid separation to obtain a crystallization mother solution and a first crystal containing nickel; a separation process: the first crystal is separated according to the particle size to obtain a second crystal and a third crystal, and the particle size of the second crystal is larger than that of the third crystal; and a post-treatment process: dissolving the second crystal, and carrying out solid-liquid separation to obtain a nickel-containing solution. According to the method for removing silicon in the preparation process of the nickel sulfate solution, provided by the embodiment of the invention, nickel can be gradually separated from silicon and other metals, and particularly, silicon impurities can be effectively removed, so that a nickel product with higher purity can be obtained.

Description

Technical Field

[0001] The present application relates to the technical field of nickel sulfate preparation, and in particular to a method for removing silicon from a nickel sulfate solution preparation process. Background Art

[0002] At present, the preparation process of nickel sulfate solution usually includes converting nickel in nickel raw materials into ionic form by leaching, thereby leaching nickel in nickel raw materials step by step to obtain nickel products. However, in the relevant technology for preparing nickel sulfate, other impurities such as silicon contained in nickel raw materials are still difficult to fully separate, which affects the quality of nickel products. Summary of the invention

[0003] The present application provides a method for removing silicon from a nickel sulfate solution preparation process, which can effectively separate nickel and silicon to facilitate obtaining a nickel product with higher purity.

[0004] The embodiment of the present application provides a method for removing silicon from a nickel sulfate solution preparation process, comprising the following steps: a leaching process, wherein the nickel raw material is subjected to acid leaching to obtain an acid leaching liquid, wherein the nickel raw material comprises at least one of high-matte nickel, low-matte nickel, nickel concentrate and a nickel sulfide intermediate; an extraction and impurity removal process, wherein the acid leaching liquid is subjected to extraction and impurity removal to obtain a stripping liquid containing impurities and a raffinate containing nickel; an evaporation and crystallization process, wherein the raffinate is placed in an evaporation device for evaporation and crystallization, and then subjected to solid-liquid separation to obtain a crystallization mother liquor and a first crystal containing nickel; a separation process, wherein the first crystal is separated and processed according to particle size to obtain a second crystal and a third crystal, wherein the particle size of the second crystal is larger than that of the third crystal; a post-treatment process, wherein the second crystal is dissolved and subjected to solid-liquid separation to obtain a nickel-containing solution.

[0005] The method for removing silicon from the nickel sulfate solution preparation process provided in the embodiment of the present application can leach out soluble components such as nickel, other metal cations, and silicates contained in the nickel raw material by first acid leaching the nickel raw material. Then, extraction and impurity removal and evaporation crystallization are carried out to gradually separate and remove other metal cation components other than nickel contained in the acid leaching solution, and at the same time, the silicic acid reacts to form silicon dioxide. Then, in the separation process, separation treatment is carried out according to particle size, and part of the silicon dioxide is removed by utilizing the characteristics of small silicon dioxide particle size and light weight, while nickel exists in the second crystal; then the second crystal is dissolved, and the slowly dissolving silicon dioxide is further removed by solid-liquid separation to obtain a nickel-containing solution. Thus, nickel can be gradually separated from silicon and other metals by the above method, especially silicon impurities can be effectively removed to facilitate obtaining a nickel product with higher purity.

[0006] In some embodiments of the present application, in the separation process, the separation treatment includes air separation and / or screening.

[0007] In some embodiments of the present application, the particle size of the second crystal is ≥50 mesh, and the particle size of the third crystal is <50 mesh.

[0008] In some embodiments of the present application, the soluble silicon content in the second crystal is ≤0.00038%.

[0009] In some embodiments of the present application, in the post-treatment step, the dissolving includes dissolving the second crystals in water.

[0010] In some embodiments of the present application, the dissolution time is ≤24h, preferably 10min-24h.

[0011] In some embodiments of the present application, the solid-liquid separation includes filtering through 500-5000 mesh and then filtering through 0.1-1 μm pore size.

[0012] In some embodiments of the present application, the silicon content of the nickel-containing solution is ≤2 mg / L.

[0013] In some embodiments of the present application, the leaching process includes: a normal pressure leaching process, subjecting the nickel raw material to normal pressure acid leaching to leach at least part of the nickel metal in the nickel raw material, obtaining normal pressure leaching residue and normal pressure leaching liquid, wherein the normal pressure leaching liquid is sent to the extraction and impurity removal process as the post-acid leaching liquid; a pressure leaching process, subjecting the normal pressure leaching residue to pressure acid leaching to leach the nickel contained in the normal pressure leaching residue, obtaining pressure leaching residue and pressure leaching liquid; a first circulation process, subjecting the pressurized leaching liquid to a first circulation treatment to obtain a circulating liquid containing ferrous ions, and the circulating liquid is returned to the normal pressure leaching process and used to mix with the nickel raw material for normal pressure acid leaching.

[0014] In some embodiments of the present application, in the first circulation step, the concentration of ferrous ions in the circulating liquid is 1 g / L to 20 g / L.

[0015] In some embodiments of the present application, the liquid-to-solid ratio of the circulating liquid mixed with the nickel raw material is (0.1-5) mL:1 g.

[0016] In some embodiments of the present application, in the atmospheric pressure leaching process, air or oxygen is introduced into the reaction environment of the atmospheric pressure acid leaching.

[0017] In some embodiments of the present application, the acid used in the atmospheric pressure acid leaching includes sulfuric acid.

[0018] In some embodiments of the present application, the reaction endpoint pH value of the atmospheric pressure acid leaching is adjusted to 5-6.

[0019] In some embodiments of the present application, the ratio of the silicon contained in the atmospheric pressure leaching residue to the sum of the mass of silicon contained in the nickel raw material and the circulating liquid is ≥90%.

[0020] In some embodiments of the present application, the method further includes: a sulfur scale washing step of washing the sulfur scale with an alkaline solution to remove sulfur attached to the evaporation equipment.

[0021] In some embodiments of the present application, the alkali in the alkali solution includes one or more of NaOH, Na2CO3, KOH, K2CO3, and NH3·H2O.

[0022] In some embodiments of the present application, the concentration of the aqueous solution of the alkali is 0.5% to 50%.

[0023] In some embodiments of the present application, the washing temperature is 60°C to 100°C.

[0024] In some embodiments of the present application, the washing time is 1 h to 36 h.

[0025] In some embodiments of the present application, the method further includes: a second circulation process, wherein the crystallization mother liquor is subjected to a second circulation treatment, saponification and soap conversion treatment to obtain nickel soap and nickel soap wastewater, the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the post-acid leaching liquid, and the silicon contained in the crystallization mother liquor is discharged along with the nickel soap wastewater.

[0026] In some embodiments of the present application, the second circulation treatment includes diluting the crystallization mother liquor with water, adjusting the pH value to 5-6, and separating the solid and liquid to obtain a treated liquid, and the treated liquid is used for saponification treatment to obtain nickel soap.

[0027] Additional technical solutions and advantages of the present application will be partially given in the following description, and partially become apparent from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A flow chart of a method for removing silicon from a nickel sulfate solution preparation process provided in some embodiments of the present application;

[0030] Figure 2A flow chart of a method for removing silicon from a nickel sulfate solution preparation process provided in some embodiments of the present application;

[0031] Figure 3 A flow chart of a method for removing silicon from a nickel sulfate solution preparation process provided in some embodiments of the present application;

[0032] Figure 4 A flow chart of a method for removing silicon from a nickel sulfate solution preparation process provided in some embodiments of the present application. DETAILED DESCRIPTION

[0033] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0034] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0035] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0036] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0037] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0038] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0039] In the present application, the nickel raw material may be high-matte nickel, low-matte nickel, intermediate nickel sulfide (nickel cobalt sulfide, MSP), nickel concentrate, etc., wherein high-matte nickel and low-matte nickel both refer to mixtures containing metal sulfides such as nickel, silicates, etc., such as NiS, Ni3S2, etc. The nickel content in high-matte nickel is usually above 60%, and the nickel content in low-matte nickel is usually below 40%. In some examples, high-matte nickel, low-matte nickel, and intermediate nickel hydroxide may all be intermediate products in the nickel smelting process, such as sulfides and silicates of metals such as nickel, copper, iron, and cobalt smelted by nickel concentrate through electricity and converters.

[0040] It should be noted that the water used in the examples of the present application can be pure water. Pure water generally refers to water with a conductivity less than or equal to 10 μS / cm, a total organic carbon less than or equal to 20 mg / L, metal ions (Na, K, Ca, Mg, etc.) less than or equal to 1000 μg / L, and other ions (Cl - 、NO3 - Water with a concentration of less than or equal to 2000 μg / L.

[0041] Solid-liquid separation refers to the process of separating solids and liquids, and the method of solid-liquid separation can be any method of separating solids and liquids known in the art. For example, in some embodiments, solid-liquid separation can be performed by centrifugation, tilting, filtration, etc., and the solid-liquid separation herein can be performed with reference to the above methods.

[0042] The liquid-to-solid ratio refers to the ratio of the volume of liquid to the mass of solid.

[0043] Soluble silicon refers to the silicon in nickel sulfate crystals that is dissolved into the solution within 24 hours when the nickel sulfate crystals are stirred with pure water.

[0044] Reference Figure 1 The present invention provides a method for removing silicon from a nickel sulfate solution preparation process, comprising the following steps:

[0045] S100, a leaching process, acid-leaching the nickel raw material to obtain an acid-leached liquid, wherein the nickel raw material includes at least one of high-grade nickel matte, low-grade nickel matte, nickel concentrate and nickel sulfide intermediate.

[0046] S200, extraction and impurity removal step, extracting and impurity removal the acid leaching solution to obtain a stripping solution containing impurities and a raffinate containing nickel.

[0047] S300, an evaporation crystallization step, placing the raffinate in an evaporation device for evaporation crystallization, and then obtaining a crystallization mother liquor and a first crystal containing nickel through solid-liquid separation.

[0048] S400, a separation step of separating the first crystal according to the particle size to obtain a second crystal and a third crystal, wherein the particle size of the second crystal is larger than that of the third crystal.

[0049] S500, a post-processing step, dissolving the second crystal, separating the solid from the liquid, and obtaining a nickel-containing solution.

[0050] The method for removing silicon from the nickel sulfate solution preparation process provided in the embodiment of the present application can leach out soluble components such as nickel, other metal cations, and silicates contained in the nickel raw material by first acid leaching the nickel raw material. Then, extraction and impurity removal and evaporation crystallization are carried out to gradually separate and remove other metal cation components other than nickel contained in the acid leaching solution, and at the same time, the silicic acid reacts to form silicon dioxide. Then, in the separation process, separation treatment is carried out according to particle size, and part of the silicon dioxide is removed by utilizing the characteristics of small silicon dioxide particle size and light weight, while nickel exists in the second crystal; then the second crystal is dissolved, and the slowly dissolving silicon dioxide is further removed by solid-liquid separation to obtain a nickel-containing solution. Thus, nickel can be gradually separated from silicon and other metals by the above method, especially silicon impurities can be effectively removed to facilitate obtaining a nickel product with higher purity.

[0051] For example, in some embodiments, the nickel raw material can be selected as high-matte nickel, which contains metals, nickel sulfide, ferrous sulfide, copper sulfide and other sulfides and silicates. When high-matte nickel is acid-leached to extract nickel, metal impurities such as iron, manganese, calcium, cobalt, and magnesium other than nickel may be leached, and the silicates contained therein may dissolve into the post-acid leaching solution, resulting in the introduction of silicon impurities. Therefore, when extracting nickel, the post-acid leaching solution needs to be further treated to remove metal impurities and silicon impurities to minimize the impact on the purity of the nickel product.

[0052] In some embodiments, different types of extractants can be used to separate different metal impurities in stages during the extraction and impurity removal process. For example, the P204 extractant can be used to separate nickel from impurities such as calcium, manganese, copper, and zinc, and the C272 extractant can be used to separate nickel from impurities such as cobalt and magnesium. In addition, nickel is precipitated in the first crystal form by evaporation crystallization, while other impurities enter the crystallization mother liquor, which is conducive to further removing impurities.

[0053] It should be noted that the silicic acid contained in the acid leaching solution may decompose into silicon dioxide under the high temperature conditions of the evaporation crystallization process. The specific reactions that may occur include:

[0054]

[0055] In the continuous nickel extraction process, SiO2 produced by the evaporation and crystallization step will be mixed into the first nickel-containing crystal, resulting in the influence of the purity of nickel. Therefore, the first crystal needs to be separated and post-processed to further remove silicon impurities.

[0056] Specifically, in the first crystal, since SiO2 crystal particles are small and light in weight, SiO2 is mainly attached to the surface of the first crystal after evaporation and crystallization, and the SiO2 can be separated and processed according to the particle size.

[0057] In some embodiments, in the separation process, the separation process includes air selection and / or screening. Among them, air selection refers to blowing away SiO2 particles with smaller particle sizes by wind force, and screening refers to filtering out SiO2 particles with smaller particle sizes by using a sieve. That is, after the first crystal is separated, the SiO2 particles mainly exist in the third crystal with a smaller particle size. Therefore, by air selection or screening, small particles of SiO2 in the first crystal can be separated to achieve the effect of silicon removal.

[0058] Further, in some embodiments, the particle size of the second crystal is ≥50 mesh, and the particle size of the third crystal is <50 mesh. It can be understood that if the particle size of the second crystal is too small, for example <50 mesh, this will cause SiO2 particles to easily mix into the second crystal, affecting the desiliconization effect; if the particle size of the third crystal is too large, for example ≥50 mesh, this will cause too much nickel to enter the third crystal, resulting in a reduction in the nickel yield. In the embodiment of the present application, by controlling the particle sizes of the second crystal and the third crystal within the above-mentioned appropriate range, it is beneficial to both desiliconization and ensuring the nickel yield.

[0059] In some embodiments, the soluble silicon content in the second crystal after separation is ≤ 0.00038%.

[0060] In order to reduce the silicon content of the second crystal, the second crystal after the separation treatment may be further treated in a post-treatment step.

[0061] Specifically, in the post-processing step, when the second crystal is dissolved, since the solubility of SiO2 is poor, the longer dissolution time of SiO2 can be used to remove silicon.

[0062] In some embodiments, in the post-treatment process, dissolving includes dissolving the second crystal in water, and silicon can be effectively removed by utilizing the characteristic that SiO2 dissolves slowly in water. Exemplarily, dissolving includes dissolving the second crystal in pure water.

[0063] In some embodiments, the dissolution time is ≤24h, preferably 10min-24h. For example, the dissolution time can be 1min, 5min, 10min, 30min, 1h, 2h, 4h, 6h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or any value ≤24h. Since SiO2 needs more than 24h to dissolve in large quantities, in the embodiments of the present application, the dissolution is controlled within 24h, and the undissolved SiO2 solid is removed by filtration.

[0064] In particular, in some embodiments, when the acid used in the acid leaching step of the leaching process is sulfuric acid, the nickel in the corresponding second crystal mainly exists in the form of nickel sulfate. The solubility of nickel sulfate crystals is significantly stronger than that of SiO2, and the dissolution time generally does not exceed 10 minutes. Therefore, when the dissolution time is selected within the range of 10 minutes to 24 hours, silicon can be effectively removed and nickel sulfate can be fully dissolved, so as to improve the nickel yield.

[0065] In some embodiments, the solid-liquid separation in the post-processing process includes filtering through 500 to 5000 meshes and then filtering through 0.1-1 μm pore size. Exemplarily, the solid-liquid separation in the post-processing process can be achieved by a filter press and a precision filter. Specifically, the dissolved second crystal solution is first passed through a filter press, the filter cloth mesh number of the filter press is 500 to 5000 meshes, and then passed through a precision filter, the pore size of the precision filter is 0.1-1 μm. Thus, by means of rapid dissolution and step-by-step filtration, on the one hand, the insoluble impurities such as SiO2 mixed with the second crystal can be removed, and on the other hand, a liquid nickel-containing solution can be obtained, such as a nickel sulfate solution, so that the obtained nickel sulfate solution can be directly applied in the battery field.

[0066] In some embodiments, the silicon content of the nickel-containing solution is ≤2 mg / L, and when the nickel-containing solution is a nickel sulfate solution, it can meet the requirements of a battery-grade nickel sulfate solution.

[0067] In addition, in some preferred cases, the leaching process can also be optimized.

[0068] Reference Figure 2 In some embodiments, the leaching step S100 includes:

[0069] S110, a normal pressure leaching process, subjecting the nickel raw material to normal pressure acid leaching to leach at least part of the nickel metal in the nickel raw material, to obtain normal pressure leaching residue and normal pressure leaching liquid, wherein the normal pressure leaching liquid is sent to the extraction and impurity removal process as the post-acid leaching liquid.

[0070] S120, a pressure leaching step, subjecting the atmospheric pressure leaching residue to pressure acid leaching to extract the nickel contained in the atmospheric pressure leaching residue, and obtaining pressure leaching residue and pressure leaching liquid.

[0071] S130, a first circulation process, wherein the pressurized leaching solution is subjected to a first circulation treatment to obtain a circulating solution containing ferrous ions, and the circulating solution is returned to the normal pressure leaching process and is used to be mixed with the nickel raw material for normal pressure acid leaching.

[0072] The method for removing silicon from the nickel sulfate solution preparation process provided in the embodiment of the present application is conducive to fully leaching the nickel contained in the nickel raw material by first subjecting the nickel raw material to atmospheric acid leaching and pressurized acid leaching in sequence. In addition, in the first circulation process, the pressurized leaching liquid is subjected to the first circulation treatment to obtain a circulating liquid containing ferrous ions, and the circulating liquid is returned to be mixed with the nickel raw material for atmospheric acid leaching, so that the atmospheric acid leaching reaction system contains an appropriate amount of ferrous ions; then, when acid leaching is performed in the atmospheric pressure leaching process, the Fe contained in the atmospheric pressure acid leaching reaction system is 2+ Can be oxidized to Fe under acidic conditions 3+ , using Fe 3+ With SiO3 2- The reaction generates Fe2(SiO3)3 precipitate. Possible reactions include:

[0073] 4Fe 2+ +4H + +O2=4Fe 3+ +H2O;

[0074] 2Fe 3+ +3SiO3 2- =Fe2(SiO3)3↓.

[0075] Through the above reaction, silicate can be converted into Fe2(SiO3)3 precipitate in a fixed form, while nickel still exists in the solution in the form of ions. Then, solid-liquid separation can be used to effectively separate nickel and silicon in the leaching stage. 2+ The pressurized leaching solution is recycled and mixed with nickel raw materials for atmospheric pressure acid leaching, which can effectively increase the Fe content in the atmospheric pressure acid leaching system. 2+ and Fe 3+ content, thereby improving the silicon precipitation efficiency, so as to achieve the effect of deep silicon removal during atmospheric pressure acid leaching and reduce the difficulty of silicon removal in subsequent processes. In addition, the present application also effectively recycles the Fe 2+ , no new impurities or hazardous chemicals are introduced during silicon removal, the processing volume is large, the production cost is low, and the silicon removal effect is stable.

[0076] It can be understood that the Fe contained in the pressure leaching solution 2+ The content may be insufficient or exceeded. At this time, if the pressurized leaching solution is directly mixed with the nickel raw material for atmospheric pressure acid leaching, the silicon removal effect is poor. Therefore, the pressurized leaching solution needs to be treated to make Fe 2+ The content is within a suitable range.

[0077] In some embodiments, in the first circulation step, the concentration of ferrous ions in the circulating liquid is 1 g / L to 20 g / L, and the circulating liquid can be obtained by diluting or concentrating the pressurized leaching liquid. For example, dilution can be obtained by adding a solvent such as water to reduce the concentration of Fe 2+ Concentration, concentration can be achieved by evaporating water to increase Fe 2+ concentration, thus obtaining Fe 2+ For example, the circulating liquid has an Fe 2+ The concentration may be 1 g / L, 2 g / L, 3 g / L, 5 g / L, 6 g / L, 8 g / L, 10 g / L, 12 g / L, 14 g / L, 15 g / L, 16 g / L, 18 g / L, 20 g / L or any value between 1 g / L and 20 g / L.

[0078] It should be noted that the Fe 2+ The concentration should not be too small. 2+If the concentration is too low, it will be difficult to meet the demand for sufficient silicon removal; Fe 2+ The concentration should not be too high. 2+ Too high a concentration will result in the introduction of too much Fe 2+ impurities, increasing the difficulty of purifying nickel products. In the embodiment of the present application, by controlling the Fe 2+ When the concentration is within the above-mentioned appropriate range, silicon can be effectively removed, which is beneficial for obtaining a nickel product with higher purity.

[0079] In some embodiments, the liquid-to-solid ratio of the circulating liquid to the nickel raw material is (0.1-5) mL: 1 g. Exemplarily, the liquid-to-solid ratio of the circulating liquid to the nickel raw material can be 0.1: 1, 0.5: 1, 1: 1, 1.5: 1, 2: 1, 2.5: 1, 3: 1, 3.5: 1, 4: 1, 4.5: 1, 5: 1 or any value between (0.1-5): 1. This is conducive to fully mixing the circulating liquid with the nickel raw material, and it is convenient to control the Fe 2+ The content is within the appropriate range.

[0080] In some embodiments, during the atmospheric pressure leaching process, air or oxygen is introduced into the reaction environment of the atmospheric pressure acid leaching. By adding air or oxygen to the reaction system of the atmospheric pressure acid leaching, it is beneficial to 2+ Oxidized to Fe 3+ , thereby utilizing Fe 3+ With SiO3 2- The reaction removes silicon and is also beneficial to improving the atmospheric pressure acid leaching effect and increasing the nickel leaching rate.

[0081] In some embodiments, the acid used for atmospheric pressure acid leaching includes sulfuric acid. In the embodiment of the present application, sulfuric acid is selected for atmospheric pressure acid leaching, and sulfate ions are introduced, so that the final leached nickel-containing solution is a nickel sulfate solution. The obtained nickel sulfate solution can be directly applied to the battery field and has good application prospects.

[0082] In some embodiments, the reaction endpoint pH value of atmospheric pressure acid leaching is adjusted to 5 to 6. For example, the reaction endpoint pH value of atmospheric pressure acid leaching is adjusted by adding alkali such as nickel hydroxide, and the reaction endpoint pH value of atmospheric pressure acid leaching can be 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6 or any value between 5 and 6. In the embodiment of the present application, by controlling the reaction endpoint pH value of atmospheric pressure acid leaching within the above suitable range, it is beneficial to promote Fe 2+ Oxidized to Fe 3+ , and it is beneficial to promote the formation of Fe2(SiO3)3 precipitation, thereby further improving the silicon removal effect.

[0083] In some embodiments, the ratio of the silicon contained in the atmospheric pressure leaching residue to the sum of the silicon masses contained in the nickel raw material and the circulating liquid is ≥90%, that is, the silicon precipitation efficiency of the leaching process in the embodiment of the present application is ≥90%, which is beneficial to reduce the difficulty of silicon removal in subsequent processes.

[0084] It should also be noted that, as mentioned above, a small amount of silicon impurities contained in the atmospheric pressure leachate may decompose to form silicon dioxide under the high temperature conditions of the evaporation crystallization process. In the continuous nickel extraction process, the evaporation equipment may cause silicon dioxide enrichment after long-term operation. The supersaturated precipitation of silicon dioxide will form silicon scale in the evaporation system, affecting the heat exchange effect, and these silicon scales may enter the first crystal containing nickel, resulting in the introduction of silicon impurities. Therefore, in some preferred cases, it is necessary to remove the silicon scale that may be generated.

[0085] Reference Figure 3 In some embodiments, the method for removing silicon from the nickel sulfate solution preparation process further comprises:

[0086] S600, a dirt washing process, washing the dirt with an alkaline solution to remove the silicon dioxide attached to the evaporation equipment.

[0087] In the embodiment of the present application, alkali solution is used to react with silicon dioxide, which can effectively remove the silicon scale attached to the evaporation equipment. In addition, during the continuous nickel extraction process, the alkali solution can be circulated to wash the silicon scale in the evaporation equipment regularly. For example, the alkali solution is used to circulate and wash the evaporation equipment every 3 to 12 months to dissolve the silicon scale, so as to ensure the heat exchange effect of the evaporation equipment, improve the thermal utilization rate of the evaporation equipment, and avoid the problem of silicon scale in the evaporation equipment affecting the evaporation energy consumption. At the same time, by removing the silicon scale, silicon impurities can be prevented from entering the first crystal containing nickel, thereby reducing the purity of the nickel product.

[0088] In some embodiments, the alkali in the alkali solution includes one or more of NaOH, Na2CO3, KOH, K2CO3, and NH3·H2O. For example, when sodium hydroxide is used as the alkali solution, the reactions that may occur under heating conditions include:

[0089] SiO2+2NaOH=Na2SiO3+H2O.

[0090] Through the above reaction, SiO2 can be converted into soluble silicate Na2SiO3, thereby effectively removing silicon scale and preventing SiO2 from entering the first crystal. In addition, during the evaporation crystallization process, Na2SiO3 enters the crystallization mother liquor, while nickel enters the first crystal, thereby effectively separating silicon impurities from nickel, achieving deep silicon removal, and no other impurities are introduced during the silicon removal process, which is conducive to ensuring the quality of nickel products.

[0091] In addition, alkali solution and washing conditions also affect the silicon removal effect, so the alkali solution and washing conditions can be optimized.

[0092] In some embodiments, the concentration of the aqueous solution of alkali is 0.5% to 50%. Exemplarily, the alkali concentration of the alkali solution can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any value between 0.5% and 50%. In some embodiments, the washing temperature is 60°C to 100°C. Exemplarily, the washing temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C or any value between 60°C and 100°C. In some embodiments, the washing time is 1h to 36h. For example, the washing time can be 1h, 3h, 6h, 9h, 12h, 15h, 18h, 21h, 24h, 27h, 30h, 33h, 36h or any value between 1h and 36h. By controlling the alkali solution and washing conditions within the above-mentioned suitable ranges, it is beneficial to further improve the silicon removal effect, and more than 90% of the silicon scale in the evaporation equipment can be removed, while saving alkali solution consumption, reducing the time consumption of the washing process, and improving the efficiency of nickel extraction.

[0093] Reference Figure 4 In some embodiments, the method for removing silicon from the nickel sulfate solution preparation process further comprises:

[0094] S700, the second circulation process, the crystallization mother liquor is subjected to the second circulation treatment and saponification treatment to obtain nickel soap and nickel soap wastewater, the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the post-acid leaching liquid, and the silicon in the crystallization mother liquor is released with the nickel soap wastewater.

[0095] In the embodiment of the present application, nickel soap is obtained by treating the crystallization mother liquor. For example, the crystallization mother liquor can be mixed with extractants such as P204 extractant and C272 extractant to obtain nickel soap. The extractants such as P204 extractant and C272 extractant can be reused to avoid the enrichment of impurities during the evaporation and crystallization process, and are beneficial to improving the quality of nickel products.

[0096] In some embodiments, the second cycle treatment includes diluting the crystallization mother liquor with water, adjusting the pH value to 5-6, and obtaining a treated liquid after solid-liquid separation, and the treated liquid is used for saponification treatment to obtain nickel soap. In the embodiment of the present application, by diluting the crystallization mother liquor with water and adjusting the pH value to 5-6, part of the silicon can be present in the form of SiO2, and then the part of the silicon can be removed by filtering, so as to reduce the silicon content in the crystallization mother liquor and avoid silicon enrichment.

[0097] For example, in some embodiments, 20%-40% of SiO2 in the crystallization mother liquor can be removed after solid-liquid separation in the second circulation process.

[0098] The following examples describe the disclosure of the present application in more detail, and these examples are only used for illustrative purposes, because it is obvious to those skilled in the art that various modifications and variations are made within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents and raw materials used in the examples are commercially available or synthesized according to conventional methods, and the instruments used in the examples are commercially available.

[0099] Example 1

[0100] This embodiment provides a method for removing silicon from a nickel sulfate solution preparation process, wherein the nickel raw material is high-grade nickel matte, and specifically comprises the following steps:

[0101] In the atmospheric pressure leaching process, Fe 2+ The circulating liquid with a concentration of 1g / L was mixed with high nickel matte in a liquid-to-solid ratio of 5:1, and acid leaching was carried out at atmospheric pressure under the conditions of sulfuric acid and oxygen. Ni(OH)2 was added to adjust the pH value to 5.5, and atmospheric pressure leaching residue and atmospheric pressure leaching liquid were obtained by filtration. The Si content of the atmospheric pressure leaching liquid was 30mg / L.

[0102] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and the pressure leaching residue and the pressure leaching liquid are obtained by filtration.

[0103] In the first circulation process, the pressurized leaching solution is subjected to the first circulation treatment to obtain Fe 2+ The circulating liquid with a concentration of 1g / L is returned to the normal pressure leaching process and used to mix with high-grade nickel matte for normal pressure acid leaching.

[0104] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to extraction and impurity removal by using P204 extractant and C272 extractant to obtain a stripping solution containing impurities and a raffinate containing nickel.

[0105] In the evaporation crystallization step, the raffinate is placed in an evaporation device for evaporation crystallization, and then filtered to obtain a crystallization mother liquor and a first crystal containing nickel. The Si content of the crystallization mother liquor is 120 mg / L, and the Si content of the first crystal is 0.001%.

[0106] In the separation process, the first crystals are air-dried in a fluidized bed dryer to obtain second crystals with a particle size greater than 50 mesh and third crystals with a particle size less than 50 mesh. The soluble Si content of the second crystals is 0.00024%, and the Si content of the third crystals is greater than that of the second crystals.

[0107] In the post-treatment process, the second crystal is quickly dissolved by adding water, and filtered through a filter press with a filter cloth mesh of 1000 mesh and a precision filter with a pore size of 0.1 μm within 24 hours to obtain a nickel sulfate solution with a Si content of 1.25 mg / L.

[0108] In the dirt washing process, the evaporation equipment is washed with alkaline solution to remove the silicon dioxide attached to the evaporation equipment. The evaporation equipment is circulated and washed with a NaOH solution of 0.5% concentration and 100°C for 36 hours.

[0109] In the second circulation process, the crystallization mother liquor is diluted with pure water, and then liquid alkali is added to adjust the pH value to 5.0, and the treated liquid with a Si content of 70 mg / L is obtained by filtration. Nickel soap is prepared from the treated liquid, and the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leaching solution.

[0110] Example 2

[0111] This embodiment provides a method for removing silicon from a nickel sulfate solution preparation process, wherein the nickel raw material is high-grade nickel matte, and specifically comprises the following steps:

[0112] In the atmospheric pressure leaching process, Fe 2+ The circulating liquid with a concentration of 20g / L was mixed with high nickel matte in a liquid-to-solid ratio of 0.5:1, and acid leaching was carried out at atmospheric pressure under the conditions of sulfuric acid and oxygen. Ni(OH)2 was added to adjust the pH value to 6.0, and atmospheric pressure leaching residue and atmospheric pressure leaching liquid were obtained by filtration. The Si content of the atmospheric pressure leaching liquid was 26mg / L.

[0113] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and the pressure leaching residue and the pressure leaching liquid are obtained by filtration.

[0114] In the first circulation process, the pressurized leaching solution is subjected to the first circulation treatment to obtain Fe 2+ The circulating liquid with a concentration of 20g / L is returned to the normal pressure leaching process and used to mix with high-grade nickel matte for normal pressure acid leaching.

[0115] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to extraction and impurity removal by using P204 extractant and C272 extractant to obtain a stripping solution containing impurities and a raffinate containing nickel.

[0116] In the evaporation crystallization step, the raffinate is placed in an evaporation device for evaporation crystallization, and then filtered to obtain a crystallization mother liquor and a first crystal containing nickel. The Si content of the crystallization mother liquor is 110 mg / L, and the Si content of the first crystal is 0.001%.

[0117] In the separation process, the first crystals are air-dried in a fluidized bed dryer to obtain second crystals with a particle size greater than 50 mesh and third crystals with a particle size less than 50 mesh. The soluble Si content of the second crystals is 0.00010%, and the Si content of the third crystals is greater than that of the second crystals.

[0118] In the post-treatment process, the second crystal is quickly dissolved by adding water, and filtered through a filter press with a filter cloth mesh of 5000 mesh and a precision filter with a pore size of 0.1 μm within 24 hours to obtain a nickel sulfate solution with a Si content of 0.5 mg / L.

[0119] In the dirt washing process, the evaporation equipment is washed with alkaline solution to remove the silicon dioxide attached to the evaporation equipment. The evaporation equipment is circulated and washed with a NaOH solution of 15% concentration and 60°C for 5 hours.

[0120] In the second circulation process, the crystallization mother liquor is diluted with pure water, and then liquid alkali is added to adjust the pH value to 6.0, and the treated liquid with a Si content of 50 mg / L is obtained by filtration. Nickel soap is prepared from the treated liquid, and the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leaching solution.

[0121] Example 3

[0122] This embodiment provides a method for removing silicon from a nickel sulfate solution preparation process, wherein the nickel raw material is high-grade nickel matte, and specifically comprises the following steps:

[0123] In the atmospheric pressure leaching process, Fe 2+ The circulating liquid with a concentration of 10g / L was mixed with high nickel matte in a liquid-to-solid ratio of 2:1, and acid leaching was carried out at atmospheric pressure under the conditions of sulfuric acid and oxygen. Ni(OH)2 was added to adjust the pH value to 5.0, and atmospheric pressure leaching residue and atmospheric pressure leaching liquid were obtained by filtration. The Si content of the atmospheric pressure leaching liquid was 32mg / L.

[0124] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and the pressure leaching residue and the pressure leaching liquid are obtained by filtration.

[0125] In the first circulation process, the pressurized leaching solution is subjected to the first circulation treatment to obtain Fe 2+ The circulating liquid with a concentration of 10g / L is returned to the normal pressure leaching process and used to mix with high-grade nickel matte for normal pressure acid leaching.

[0126] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to extraction and impurity removal by using P204 extractant and C272 extractant to obtain a stripping solution containing impurities and a raffinate containing nickel.

[0127] In the evaporation crystallization step, the raffinate is placed in an evaporation device for evaporation crystallization, and then filtered to obtain a crystallization mother liquor and a first crystal containing nickel. The Si content of the crystallization mother liquor is 115 mg / L, and the Si content of the first crystal is 0.001%.

[0128] In the separation process, the first crystals are air-dried in a fluidized bed dryer to obtain second crystals with a particle size greater than 50 mesh and third crystals with a particle size less than 50 mesh. The soluble Si content of the second crystals is 0.00030%, and the Si content of the third crystals is greater than that of the second crystals.

[0129] In the post-treatment process, the second crystal is quickly dissolved by adding water, and filtered through a filter press with a filter cloth mesh number of 3000 and a precision filter with a pore size of 1 μm within 24 hours to obtain a nickel sulfate solution with a Si content of 1.57 mg / L.

[0130] In the dirt washing process, the evaporation equipment is washed with alkaline solution to remove the silicon dioxide attached to the evaporation equipment. The evaporation equipment is circulated and washed with a 7% NaOH solution at a temperature of 80°C for 10 hours.

[0131] In the second circulation process, the crystallization mother liquor is diluted with pure water, and then liquid alkali is added to adjust the pH value to 5.5, and the treated liquid with a Si content of 60 mg / L is obtained by filtration. Nickel soap is prepared from the treated liquid, and the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leaching solution.

[0132] Example 4

[0133] This embodiment provides a method for removing silicon from a nickel sulfate solution preparation process, wherein the nickel raw material is high-grade nickel matte, and specifically comprises the following steps:

[0134] In the atmospheric pressure leaching process, Fe 2+ The circulating liquid with a concentration of 10g / L was mixed with high nickel matte in a liquid-to-solid ratio of 2:1, and acid leaching was carried out at atmospheric pressure under the conditions of sulfuric acid and oxygen. Ni(OH)2 was added to adjust the pH value to 6.0, and atmospheric pressure leaching residue and atmospheric pressure leaching liquid were obtained by filtration. The Si content of the atmospheric pressure leaching liquid was 25mg / L.

[0135] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and the pressure leaching residue and the pressure leaching liquid are obtained by filtration.

[0136] In the first circulation process, the pressurized leaching solution is subjected to the first circulation treatment to obtain Fe 2+ The circulating liquid with a concentration of 10g / L is returned to the normal pressure leaching process and used to mix with high-grade nickel matte for normal pressure acid leaching.

[0137] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to extraction and impurity removal by using P204 extractant and C272 extractant to obtain a stripping solution containing impurities and a raffinate containing nickel.

[0138] In the evaporation crystallization step, the raffinate is placed in an evaporation device for evaporation crystallization, and then filtered to obtain a crystallization mother liquor and a first crystal containing nickel. The Si content of the crystallization mother liquor is 112 mg / L, and the Si content of the first crystal is 0.001%.

[0139] In the separation process, the first crystals are air-dried in a fluidized bed dryer to obtain second crystals with a particle size greater than 50 mesh and third crystals with a particle size less than 50 mesh. The soluble Si content of the second crystals is 0.00034%, and the Si content of the third crystals is greater than that of the second crystals.

[0140] In the post-treatment process, the second crystal is quickly dissolved by adding water, and filtered through a filter press with a filter cloth mesh number of 4000 and a precision filter with a pore size of 0.1 μm within 24 hours to obtain a nickel sulfate solution with a Si content of 1.77 mg / L.

[0141] In the dirt washing process, the evaporation equipment is washed with alkaline solution to remove the silicon dioxide attached to the evaporation equipment. The evaporation equipment is circulated and washed with a 10% NaOH solution at a temperature of 70°C for 15 hours.

[0142] In the second circulation process, the crystallization mother liquor is diluted with pure water, and then liquid alkali is added to adjust the pH value to 5.5, and the treated liquid with a Si content of 55 mg / L is obtained by filtration. Nickel soap is prepared from the treated liquid, and the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leaching solution.

[0143] Comparative Example 1

[0144] The difference from Example 1 is that the first crystal is directly subjected to the post-processing step without going through the separation step.

[0145] The Si content of the obtained nickel sulfate solution was 3.4 mg / L.

[0146] Comparative Example 2

[0147] The difference from Example 1 is that the separation particle size in the separation process is different. Specifically, in the separation process, the first crystal is air-dried in a fluidized bed dryer to obtain a second crystal with a particle size of ≥80 mesh and a third crystal with a particle size of <80 mesh, and the soluble Si content of the second crystal is 0.0005%.

[0148] The Si content of the obtained nickel sulfate solution was 2.59 mg / L.

[0149] Comparative Example 3

[0150] The difference from Example 1 is that the dissolution time of the post-treatment process is different. Specifically, in the post-treatment process, the second crystal is quickly dissolved by adding water, and filtered through a filter press with a filter cloth mesh of 1000 mesh and a precision filter with a pore size of 0.1 μm within 48 hours to obtain a nickel sulfate solution with a Si content of 2.3 mg / L.

[0151] Table 1. Silicon removal effects of various embodiments and comparative examples

[0152]

[0153] Referring to Table 1, it can be seen from Examples 1 to 4 that the method for removing silicon from the nickel sulfate solution preparation process provided in the embodiments of the present application is adopted, and the Si content of the nickel sulfate solution is ≤2 mg / L, which meets the requirements of battery-grade nickel sulfate solution, and the obtained nickel sulfate solution can be directly used as a raw material for producing anode material precursors of batteries. In the comparative example, the nickel raw material is treated under reaction conditions different from those in the embodiments of the present application, and the Si content of the obtained nickel sulfate solution is significantly higher than that of the embodiment, indicating that silicon can be effectively removed under the conditions of the embodiments of the present application, so as to obtain a nickel product with better quality.

[0154] It can be seen that in the embodiment of the present application, by controlling the Fe 2+ Concentration, returning it to the atmospheric pressure leaching process and nickel raw material ingredients can increase the Fe 2+ and Fe 3+ Content, using Fe 3+ With SiO3 2- The reaction occurs to achieve deep silicon removal, which is beneficial to improving the silicon removal effect. In addition, the steps of opening the crystallization mother liquor, hot alkali circulation washing evaporation equipment, air separation or screening separation of SiO2, rapid dissolution and precision filtration are adopted to make the Si concentration of the nickel sulfate solution extremely low, and the silicon removal process does not introduce new impurities. The silicon removal effect is stable, the processing capacity is large, the wastewater output is small, the operating cost is low, and it has good application prospects.

[0155] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for removing silicon from a nickel sulfate solution preparation process, characterized in that: The following steps are involved: A leaching step, wherein the nickel raw material is subjected to acid leaching to obtain an acid leaching solution, wherein the nickel raw material comprises at least one of high-grade nickel matte, low-grade nickel matte, nickel concentrate and nickel sulfide intermediate; An extraction and impurity removal step, wherein the acid leaching solution is subjected to extraction and impurity removal to obtain a stripping solution containing impurities and a raffinate containing nickel; an evaporation crystallization step, wherein the raffinate is evaporated and crystallized, and then solid-liquid separation is performed to obtain a crystallization mother liquor and a first crystal containing nickel; A separation step, separating the first crystal according to particle size to obtain a second crystal and a third crystal, wherein the particle size of the second crystal is larger than the particle size of the third crystal; In the post-treatment step, the second crystals are dissolved and solid-liquid separated to obtain a nickel-containing solution.

2. The method for removing silicon from a nickel sulfate solution preparation process according to claim 1, characterized in that: In the separation process, the separation treatment includes air separation and / or screening; Optionally, the particle size of the second crystal is ≥50 mesh, and the particle size of the third crystal is <50 mesh; Optionally, the soluble silicon content in the second crystal is ≤0.00038%.

3. The method for removing silicon from a nickel sulfate solution preparation process according to claim 1, characterized in that: In the post-treatment step, the dissolving includes dissolving the second crystals in water; Optionally, the dissolution time is ≤24h, preferably 10min-24h; Optionally, the solid-liquid separation includes filtering through 500-5000 mesh and then filtering through 0.1-1 μm pore size; Optionally, the silicon content of the nickel-containing solution is ≤2 mg / L.

4. The method for removing silicon from a nickel sulfate solution preparation process according to claim 1, characterized in that: The leaching process comprises: A normal pressure leaching step, subjecting the nickel raw material to normal pressure acid leaching to leach at least part of the nickel metal in the nickel raw material, to obtain normal pressure leaching residue and normal pressure leaching liquid, wherein the normal pressure leaching liquid is sent to the extraction and impurity removal step as the post-acid leaching liquid; A pressure leaching step, wherein the atmospheric pressure leaching residue is subjected to pressure acid leaching to leach out the nickel contained in the atmospheric pressure leaching residue, thereby obtaining pressure leaching residue and pressure leaching liquid; In the first circulation step, the pressurized leaching solution is subjected to a first circulation treatment to obtain a circulating solution containing ferrous ions, and the circulating solution is returned to the normal pressure leaching step and used to be mixed with the nickel raw material for normal pressure acid leaching.

5. The method for removing silicon from a nickel sulfate solution preparation process according to claim 4, characterized in that: In the first circulation step, the concentration of ferrous ions in the circulating liquid is 1 g / L to 20 g / L; Optionally, the liquid-to-solid ratio of the circulating liquid mixed with the nickel raw material is (0.1-5) mL:1 g.

6. The method for removing silicon from a nickel sulfate solution preparation process according to claim 4, characterized in that: In the atmospheric pressure leaching process, air or oxygen is introduced into the reaction environment of the atmospheric pressure acid leaching; Optionally, the reaction endpoint pH value of the atmospheric pressure acid leaching is adjusted to 5 to 6; Optionally, the ratio of the silicon contained in the atmospheric pressure leaching residue to the sum of the mass of silicon contained in the nickel raw material and the circulating liquid is ≥90%.

7. The method for removing silicon from a nickel sulfate solution preparation process according to claim 1, characterized in that: The method further comprises: In the dirt washing process, the dirt is washed with an alkaline solution to remove the silicon dioxide attached to the evaporation equipment.

8. The method for removing silicon from a nickel sulfate solution preparation process according to claim 7, characterized in that: The alkali in the alkali solution includes one or more of NaOH, Na2CO3, KOH, K2CO3, and NH3·H2O; Optionally, the concentration of the aqueous solution of the alkali is 0.5% to 50%; Optionally, the washing temperature is 60°C to 100°C; Optionally, the washing time is 1 h to 36 h.

9. The method for removing silicon from a nickel sulfate solution preparation process according to claim 1, characterized in that: The method further comprises: In the second circulation step, the crystallization mother liquor is subjected to second circulation treatment, saponification and soap conversion treatment to obtain nickel soap and nickel soap wastewater. The nickel soap is returned to the extraction and impurity removal step and used to extract and remove impurities from the post-acid leaching liquid. The silicon in the crystallization mother liquor is released along with the nickel soap wastewater.

10. The method for removing silicon from a nickel sulfate solution preparation process according to claim 9, characterized in that: The second circulation treatment includes diluting the crystallization mother liquor with water, adjusting the pH value to 5-6, and separating the solid and liquid to obtain a treated liquid, and the treated liquid is used for soap conversion treatment to obtain nickel soap.

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