Method for removing thiosulfate radicals in nickel sulfate solution preparation process

Abstract

The invention provides a method for removing thiosulfate radicals in a nickel sulfate solution preparation process, and the method comprises the following steps: a slurrying process: slurrying a nickel raw material to obtain slurry, the nickel raw material comprising at least one of high nickel matte, low nickel matte, nickel concentrate and a nickel sulfide intermediate product; a normal-pressure leaching process: carrying out normal-pressure acid leaching on the slurry to leach at least part of nickel metal in the nickel raw material to obtain normal-pressure leaching residues and a normal-pressure leaching solution; a pressure leaching process: performing pressure acid leaching on the atmospheric pressure leaching residues to leach nickel contained in the atmospheric pressure leaching residues to obtain pressure leaching residues and a pressure leaching solution; and a first circulation process: carrying out first circulation treatment on the pressure leaching liquid to obtain circulation liquid with the copper ion concentration of 2g / L-40g / L, returning the circulation liquid to the normal-pressure leaching process, and mixing the circulation liquid with the slurry to carry out normal-pressure acid leaching. According to the method provided by the embodiment of the invention, impurities such as nickel and thiosulfate radicals can be effectively separated, so that a nickel product with better quality 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 thiosulfate from a nickel sulfate solution preparation process. Background Art

[0002] At present, the preparation process of nickel sulfate solution generally includes converting the nickel raw material into ionic form by leaching to separate the nickel from other components such as sulfide, thereby leaching the nickel in the nickel raw material step by step to obtain a nickel product. However, in the related art, some impurities are doped into the nickel product, resulting in poor quality of the nickel product. Summary of the invention

[0003] The present application provides a method for removing thiosulfate from a nickel sulfate solution preparation process, which can effectively separate nickel and impurities such as thiosulfate, so as to obtain a nickel product with better quality.

[0004] An embodiment of the present application provides a method for removing thiosulfate from a nickel sulfate solution preparation process, comprising the following steps: a slurrying step, slurrying a nickel raw material to obtain a slurry, wherein the nickel raw material comprises at least one of high-matte nickel, low-matte nickel, nickel concentrate and a nickel sulfide intermediate; a normal pressure leaching step, subjecting the slurry to normal pressure acid leaching to leach at least part of the nickel in the nickel raw material, to obtain normal pressure leaching slag and normal pressure leaching liquid; a pressurized leaching step, subjecting the normal pressure leaching slag to pressurized acid leaching to leach the nickel contained in the normal pressure leaching slag, to obtain pressurized leaching slag and pressurized leaching liquid; a first circulation step, subjecting the pressurized leaching liquid to a first circulation treatment to obtain a circulating liquid having a copper ion concentration of 2 g / L to 40 g / L, the circulating liquid being returned to the normal pressure leaching step and used to be mixed with the slurry for normal pressure acid leaching.

[0005] The method for removing thiosulfate from the nickel sulfate solution preparation process provided in the embodiment of the present application is to first slurry the nickel raw material, and then sequentially perform atmospheric acid leaching and pressurized acid leaching, which is conducive to fully leaching the nickel in the nickel raw material. In addition, in the first circulation process, the pressurized leaching liquid is subjected to the first circulation treatment to obtain a circulating liquid with a copper ion concentration of 2g / L to 40g / L, and the circulating liquid is mixed with the nickel raw material slurry for atmospheric acid leaching, so that in the continuous nickel sulfate preparation process, the atmospheric acid leaching reaction system can maintain a proper amount of Cu 2+ . Thus, using Cu 2+ With S2O3 2- The reaction generates CuS precipitate and SO4 2- After solid-liquid separation, atmospheric pressure leaching residue containing CuS and Ni 2+ The atmospheric pressure leaching solution is conducive to the removal of S2O3 2- The resulting nickel product is of better quality.

[0006] In some embodiments of the present application, the copper sulfide concentration contained in the atmospheric pressure acid leaching reaction system is 3g / L-50g / L.

[0007] In some embodiments of the present application, in the first circulation step, the first circulation treatment includes diluting or concentrating the pressurized leaching solution to obtain a circulating solution with a copper ion concentration of 2 g / L to 40 g / L.

[0008] In some embodiments of the present application, the volume ratio of the circulating liquid to the slurry is (0.5-10):1.

[0009] In some embodiments of the present application, in the slurrying process, the nickel raw material is mixed with water to obtain a slurry.

[0010] In some embodiments of the present application, the solid content of the slurry is 20% to 50%.

[0011] 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.

[0012] In some embodiments of the present application, the acid used in the atmospheric pressure acid leaching includes sulfuric acid.

[0013] In some embodiments of the present application, the method further includes: an extraction and impurity removal step, in which the atmospheric pressure leachate is subjected to extraction and impurity removal to obtain an extract containing impurities and a raffinate containing nickel; an evaporation and crystallization step, in which the raffinate is placed in an evaporation device for evaporation and crystallization, and then solid-liquid separation is performed to obtain a crystallization mother liquor and crystals containing nickel.

[0014] 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.

[0015] In some embodiments of the present application, the alkali solution includes one or more of NaOH, Na2CO3, KOH, K2CO3, and NH3·H2O.

[0016] In some embodiments of the present application, the concentration of the aqueous solution of the alkali is 0.5% to 50%.

[0017] In some embodiments of the present application, the washing temperature is 60°C to 100°C.

[0018] In some embodiments of the present application, the washing time is 1 h to 36 h.

[0019] In some embodiments of the present application, the method further includes: a second circulation step, wherein the crystallization mother liquor is subjected to saponification treatment to obtain nickel soap, and the nickel soap is returned to the extraction and impurity removal step and used to extract and remove impurities from the atmospheric pressure leaching solution.

[0020] In some embodiments of the present application, the method further comprises: a post-processing step of dissolving the crystals, filtering out trace water-insoluble matter through solid-liquid separation, and obtaining a nickel-containing solution.

[0021] In some embodiments of the present application, the dissolving comprises dissolving the crystals in water.

[0022] 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

[0023] 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.

[0024] Figure 1 A flow chart of a method for removing thiosulfate from a nickel sulfate solution preparation process provided in some embodiments of the present application;

[0025] Figure 2 A flow chart of a method for removing thiosulfate from a nickel sulfate solution preparation process provided in some embodiments of the present application. DETAILED DESCRIPTION

[0026] "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.

[0027] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] In the present application, nickel raw material refers to a mixture containing nickel sulfide and nickel metal eutectic. In some examples, the nickel raw material can be high matte nickel, low matte nickel, nickel concentrate, nickel sulfide intermediate (nickel cobalt sulfide, MSP), etc., wherein high matte nickel and low matte nickel both refer to mixtures containing metal sulfides such as nickel, 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 and low matte nickel can both be intermediate products in the nickel smelting process, such as sulfide eutectics of metals such as nickel, copper, iron, and cobalt smelted by nickel concentrate through electricity and converter.

[0033] 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.

[0034] 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.

[0035] Reference Figure 1 The present invention provides a method for removing thiosulfate from a nickel sulfate solution preparation process, comprising the following steps:

[0036] S100, a slurrying process, slurrying the nickel raw material to obtain a slurry, wherein the nickel raw material includes at least one of high-grade nickel matte, low-grade nickel matte, nickel concentrate and nickel sulfide intermediate.

[0037] S200, a normal pressure leaching process, subjecting the slurry 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.

[0038] S300, a pressure leaching step, wherein the normal pressure leaching residue is subjected to pressure acid leaching to leach out the nickel contained in the normal pressure leaching residue, thereby obtaining pressure leaching residue and pressure leaching liquid.

[0039] S400, a first circulation step, wherein the pressurized leaching solution is subjected to a first circulation treatment to obtain a circulating solution having a copper ion concentration of 2 g / L to 40 g / L, and the circulating solution is returned to the normal pressure leaching step and used to be mixed with the slurry for normal pressure acid leaching.

[0040] The method for removing thiosulfate from the nickel sulfate solution preparation process provided in the embodiment of the present application is to first slurry the nickel raw material, and then sequentially perform atmospheric acid leaching and pressurized acid leaching, which is conducive to fully leaching the nickel in the nickel raw material. In addition, in the first circulation process, the pressurized leaching liquid is subjected to the first circulation treatment to obtain a circulating liquid with a copper ion concentration of 2g / L to 40g / L, and the circulating liquid is mixed with the nickel raw material slurry for atmospheric acid leaching, so that in the continuous nickel sulfate preparation process, the atmospheric acid leaching reaction system can maintain a proper amount of Cu 2+ . Thus, using Cu 2+ With S2O3 2- The reaction generates CuS precipitate and SO4 2- After solid-liquid separation, atmospheric pressure leaching residue containing CuS and Ni 2+ The atmospheric pressure leaching solution is conducive to the removal of S2O3 2- The resulting nickel product is of better quality.

[0041] For example, in some embodiments, the nickel raw material can be selected as high-grade nickel matte, which contains sulfides such as nickel sulfide, ferrous sulfide, and copper sulfide. When the high-grade nickel matte is subjected to normal pressure acid leaching, the nickel sulfide contained therein may be oxidized, and some of the nickel sulfide may not be completely oxidized to generate S2O3. 2- Therefore, S2O3 needs to be removed during the preparation of nickel sulfate. 2- , so as to avoid affecting the purity of nickel products as much as possible.

[0042] Specifically, in the process of preparing nickel sulfate solution from high nickel matte, the circulating liquid with a copper ion concentration of 2g / L to 40g / L is mixed with the slurry through the first circulation process and then subjected to normal pressure acid leaching. 2+ It will undergo a replacement reaction with a large amount of sulfide in the slurry. The reactions that may occur at this time include:

[0043] FeS+Cu 2+ →Fe 2+ +CuS↓;

[0044] NiS+Cu 2+ →Ni 2+ +CuS↓.

[0045] Through the above reaction, part of the nickel is converted into Ni 2+, which is beneficial to improve the nickel recovery rate. On the other hand, it can increase the CuS content in the mixture of circulating liquid and slurry, that is, the CuS content of the reaction system of atmospheric pressure acid leaching is higher. During atmospheric pressure leaching, since CuS is difficult to dissolve, the specific solubility is FeS (Ksp = 4.9 × 10 -18 )>NiS(Ksp=2.8×10 -21 )>CuS(Ksp=8.9×10 -35 ), therefore, under normal pressure oxygen leaching conditions, FeS and NiS are oxidized and leached first, and CuS is leached later. The possible leaching reactions at this time include:

[0046] FeS+2O2→Fe 2+ +SO4 2+ ;

[0047] NiS+2O2→Ni 2+ +SO4 2+ ;

[0048] CuS+2O2→Cu 2+ +SO4 2+ .

[0049] As mentioned above, in the present application, the copper ions of appropriate concentration are recycled for atmospheric pressure acid leaching through the first circulation process, so that the CuS content of the atmospheric pressure acid leaching reaction system is high enough, so that a certain amount of Cu can be produced after the CuS is oxidized and leached. 2+ These copper ions can react with S2O3 2- Reaction to remove S2O3 2- , and can also react with sulfides such as NiS to facilitate nickel leaching. The reactions that may occur at this time include:

[0050] Cu 2+ +S2O3 2- +H2O→CuS↓+SO4 2- +2H + ;

[0051] NiS+Cu 2+ →Ni 2+ +CuS↓.

[0052] Therefore, in the continuous nickel sulfate preparation process, by 2+ The pressurized leaching solution is recycled and mixed with the slurry for atmospheric pressure acid leaching, thereby increasing the Cu 2+ content, so as to facilitate deep removal of S2O3 during normal pressure acid leaching 2- The effect of Cu 2+ The CuS precipitate is formed to separate from the nickel in the solution, ensuring the purity of the nickel product. In addition, the present application also effectively recycles the Cu in the pressurized leaching solution.2+ , in the removal of S2O3 2- No other impurities or hazardous chemicals are introduced, the production cost is low and the production safety is high.

[0053] In order to facilitate the understanding of the technical solution of the present application, the nickel raw material in the following embodiments can all be selected from high-matte nickel as an example.

[0054] Since the atmospheric pressure acid leaching system may contain a high concentration of S2O3 2- , while CuS is difficult to dissolve to form Cu 2+ , resulting in Cu 2+ The content is low, thus affecting S2O3 2- Therefore, the CuS content in the atmospheric pressure acid leaching system should be maintained within an appropriate range to facilitate the continuous production of sufficient Cu 2+ , thereby removing S2O3 as much as possible 2- .

[0055] In some embodiments, the copper sulfide concentration contained in the reaction system of atmospheric pressure acid leaching is 3 g / L-50 g / L. For example, the copper sulfide concentration contained in the reaction system of atmospheric pressure acid leaching can be 3 g / L, 5 g / L, 8 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L, 20 g / L, 22 g / L, 25 g / L, 28 g / L, 30 g / L, 32 g / L, 35 g / L, 38 g / L, 40 g / L, 42 g / L, 45 g / L, 48 g / L, 50 g / L or any value between 2 g / L and 50 g / L.

[0056] For example, in some embodiments, the S2O3 in the reaction system of atmospheric acid leaching 2- It may reach 100-3000mg / L, and the reaction system can react with S2O3 2- Reaction of free Cu 2+ Extremely small amount of about 0.1-5.0 mg / L, not enough to remove S2O3 at one time 2- At this time, it is necessary to continuously add CuS to the reaction system so that CuS reacts to form more free Cu 2+ Therefore, in the present embodiment, the appropriate concentration of Cu 2+ The circulating liquid is mixed with the slurry for atmospheric pressure acid leaching, so that the CuS content in the atmospheric pressure acid leaching reaction system can be ensured to be within the above-mentioned appropriate range, which is conducive to removing S2O3 as much as possible. 2- .

[0057] It is understandable that the copper ion content of the pressurized leaching solution may be insufficient or excessive. At this time, if the pressurized leaching solution is directly mixed with the slurry for atmospheric pressure acid leaching, the S2O3 2-The removal effect is poor, so the pressurized leaching solution needs to be treated to make the copper ion content within an appropriate range.

[0058] In some embodiments, in the first circulation process, the first circulation treatment includes diluting or concentrating the pressurized leachate to obtain a circulating liquid with a copper ion concentration of 2g / L to 40g / L. Exemplarily, dilution can be performed by adding a solvent such as water to reduce the copper ion concentration, and concentration can be performed by evaporating water to increase the copper ion concentration, thereby obtaining a circulating liquid with a suitable copper ion concentration. Exemplarily, the copper ion concentration of the circulating liquid can be 5g / L, 8g / L, 10g / L, 12g / L, 15g / L, 18g / L, 20g / L, 22g / L, 25g / L, 28g / L, 30g / L, 32g / L, 35g / L, 38g / L, 40g / L or any value between 3g / L and 40g / L.

[0059] It should be noted that the copper ion concentration of the circulating fluid should not be too small. If the copper ion concentration is too small, it will be difficult to fully remove S2O3. 2- The copper ion concentration of the circulating liquid should not be too high. If the copper ion concentration is too high, it will lead to the introduction of too many copper ion impurities, increasing the difficulty of purifying nickel products. In the embodiment of the present application, by controlling the copper ion concentration of the circulating liquid within the above-mentioned appropriate range, S2O3 can be effectively removed. 2- , which is conducive to obtaining nickel products with higher purity.

[0060] In some embodiments, the volume ratio of the circulating liquid to the slurry is (0.5-10): 1. For example, the volume ratio of the circulating liquid to the slurry can be 0.5: 1, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1 or any value between (0.5-10): 1. This is conducive to fully mixing the circulating liquid and the slurry, and is convenient for controlling the CuS content after the circulating liquid and the slurry are mixed within a suitable range.

[0061] In some embodiments, in the slurrying process, the nickel raw material is mixed with water to obtain a slurry. For example, the water can be pure water. Adding water to obtain a slurry is conducive to the full mixing of the nickel raw material and the circulating liquid, so as to facilitate the subsequent leaching of nickel and remove S2O3 2- .

[0062] In some embodiments, the solid content of the slurry is 20% to 50%. The solid content refers to the total mass of the solids in the slurry divided by the total mass of the slurry, that is, the mass percentage of the remaining portion of the slurry after drying. Exemplarily, the solid content of the slurry can be 20%, 25%, 30%, 35%, 40%, 45%, 50% or any value between 20% and 50%. The embodiment of the present application controls the solid content of the slurry within a suitable range, further making the nickel raw material and the circulating liquid mix more evenly, which is conducive to the removal of S2O3 2- .

[0063] Furthermore, in order to improve the leaching effect of atmospheric pressure acid leaching, the atmospheric pressure leaching process can also be optimized.

[0064] 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 atmospheric pressure acid leaching reaction system, it is beneficial to improve the atmospheric pressure acid leaching effect and increase the leaching rate of nickel.

[0065] In some embodiments, the acid used for atmospheric pressure acid leaching includes sulfuric acid. In the embodiment of the present application, sulfuric acid is used for atmospheric pressure acid leaching, and sulfate ions are introduced, so that the final leached nickel product is nickel sulfate. The obtained nickel sulfate can be directly applied to the battery field and has good application prospects.

[0066] Since the atmospheric pressure leaching solution may contain other impurities besides nickel, in order to improve the purity of the nickel product, the atmospheric pressure leaching solution may be further treated to remove other impurities as much as possible.

[0067] Reference Figure 2 In some embodiments, the method for removing thiosulfate from the nickel sulfate solution preparation process further comprises:

[0068] S500, extraction and impurity removal step, extracting and impurity removal the atmospheric pressure leaching solution to obtain an extract containing impurities and a raffinate containing nickel.

[0069] S600, an evaporation crystallization step, after evaporating and crystallizing the raffinate, a crystallization mother liquor and nickel-containing crystals are obtained through solid-liquid separation.

[0070] The embodiment of the present application extracts and removes impurities and evaporates and crystallizes the atmospheric pressure leachate, so that nickel can be separated from other metal cation impurities, which is conducive to obtaining a nickel product with higher purity. Specifically, when the nickel raw material is high-matte nickel, metal impurities such as iron, manganese, calcium, cobalt, and magnesium other than nickel may be leached during acid leaching. The corresponding extraction and impurity removal process can use different types of extractants to separate different metal impurities in stages. Exemplarily, the use of P507 extractant for extraction can separate impurities such as nickel and iron, the use of P204 extractant can separate nickel from impurities such as manganese and calcium, and the use of C272 extractant can separate nickel from impurities such as cobalt and magnesium. In addition, nickel is precipitated in the form of crystals through evaporation and crystallization, while other impurities enter the crystallization mother liquor, which is conducive to further removing impurities.

[0071] It should be noted that the atmospheric pressure leaching solution contains trace amounts of S2O3 2- The disproportionation reaction may occur during the evaporation and crystallization process to produce sulfur. Specifically, trace amounts of S2O3 2- Entering the evaporation equipment, the reactions that may occur under the high temperature conditions of evaporation include:

[0072] S2O3 2- +2H + =S↓+SO2↑+H2O.

[0073] In the continuous nickel sulfate preparation process, the evaporation equipment may cause sulfur to accumulate in the evaporation equipment after long-term operation to form sulfur scale, which affects the heat exchange effect. In addition, sulfur may enter the nickel-containing crystals and introduce impurities. Therefore, in some preferred cases, it is necessary to 2- Any sulfur that may be generated is removed.

[0074] Refer to Figure 2 In some embodiments, the method for removing thiosulfate from the nickel sulfate solution preparation process further comprises:

[0075] S700, sulfur scale washing process, using alkaline solution to wash the sulfur scale to remove the sulfur attached to the evaporation equipment.

[0076] In the embodiment of the present application, alkali solution is used to react with sulfur element (i.e., sulfur), which can effectively remove the sulfur scale attached to the evaporation equipment. In addition, in the continuous nickel sulfate preparation process, the alkali solution can be circulated to wash the sulfur 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 sulfur element, 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 sulfur scale in the evaporation equipment affecting the evaporation energy consumption. At the same time, by removing the sulfur scale, sulfur impurities can be prevented from entering the nickel-containing crystals, thereby reducing the purity of the nickel product.

[0077] In some embodiments, 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 include:

[0078]

[0079] Through the above reaction, sulfur can be converted into soluble sulfide Na2S and sulfite Na2SO3, thereby effectively removing sulfur scale and preventing sulfur from entering the crystals containing nickel. In addition, during the evaporation and crystallization process, Na2S and Na2SO3 enter the crystallization mother liquor, while nickel enters the crystals, thereby effectively separating sulfur impurities from nickel, achieving deep desulfurization, and no other impurities are introduced during the desulfurization process, which is conducive to ensuring the quality of nickel products.

[0080] In addition, alkali solution and washing conditions also affect the desulfurization effect, so the alkali solution and washing conditions can be optimized.

[0081] In some embodiments, the concentration of the aqueous solution of alkali is 0.5% to 50%. Exemplarily, the concentration of the aqueous solution of alkali 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% to 50%. In some embodiments, the temperature of washing is 60°C to 100°C. Exemplarily, the temperature of washing 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 to 100°C. In some embodiments, the time of washing 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 the washing conditions within the above-mentioned suitable ranges, it is beneficial to further improve the desulfurization effect, save alkali solution consumption, reduce the time consumption of the washing process, and improve the preparation efficiency of nickel sulfate.

[0082] Refer to Figure 2 In some embodiments, the method for removing thiosulfate from the nickel sulfate solution preparation process further comprises:

[0083] S800, the second circulation process, the crystallization mother liquor is subjected to saponification treatment to obtain nickel soap, 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.

[0084] 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.

[0085] Refer to Figure 2 In some embodiments, the method for removing thiosulfate from the nickel sulfate solution preparation process further comprises:

[0086] S900, post-processing step, dissolving the crystals, filtering out trace water-insoluble matter through solid-liquid separation, and obtaining a nickel-containing solution.

[0087] In the embodiment of the present application, the nickel-containing crystals are dissolved and then separated into solid and liquid. On the one hand, the insoluble impurities contained in the crystals can be removed, and on the other hand, a liquid nickel-containing solution can be prepared, for example, a nickel sulfate solution, so that the obtained nickel sulfate solution can be directly used in the battery field.

[0088] In some embodiments, dissolving comprises dissolving the crystal in water. Exemplarily, dissolving comprises dissolving the crystal in pure water.

[0089] 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.

[0090] Example 1

[0091] This embodiment provides a method for removing thiosulfate from a nickel sulfate solution preparation process, wherein the nickel raw material is high nickel matte, and specifically comprises the following steps:

[0092] In the slurrying process, high-grade nickel matte is mixed with pure water to obtain a slurry with a solid content of 20%.

[0093] In the atmospheric pressure leaching process, Cu 2+ The circulating liquid with a concentration of 3g / L was mixed with the slurry in a volume ratio of 10:1, and acid leaching was carried out under the conditions of sulfuric acid and oxygen. The atmospheric leaching residue and atmospheric leaching liquid were obtained by filtration. The main components of the atmospheric leaching residue were Ni, Cu, and Fe, and the S2O3 of the atmospheric leaching liquid was 2- The content is 1.0mg / L.

[0094] 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, wherein the main component of the pressure leaching residue is iron slag.

[0095] In the first circulation step, the pressurized leaching solution is subjected to the first circulation treatment to obtain Cu 2+ The circulating liquid with a concentration of 3g / L is returned to the atmospheric pressure leaching process and used to mix with the slurry for atmospheric pressure acid leaching.

[0096] The method for removing thiosulfate from the nickel sulfate solution preparation process in this embodiment may also include the following steps:

[0097] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to P507 extraction and impurity removal to obtain a raffinate containing nickel.

[0098] In the evaporation and crystallization step, the raffinate is placed in an evaporation device for evaporation and crystallization, and then filtered to obtain a crystallization mother liquor and crystals containing nickel.

[0099] In the washing process, the evaporation equipment was circulated and washed with a 15% NaOH aqueous solution at a temperature of 60°C for 5 hours.

[0100] In the second circulation process, the crystallization mother liquor is used to prepare nickel soap, 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.

[0101] In the post-treatment step, the nickel-containing crystals are dissolved in water and filtered to obtain a nickel sulfate solution.

[0102] Example 2

[0103] This embodiment provides a method for removing thiosulfate from a nickel sulfate solution preparation process, wherein the nickel raw material is high nickel matte, and specifically comprises the following steps:

[0104] In the slurrying process, high-grade nickel matte is mixed with pure water to obtain a slurry with a solid content of 50%.

[0105] In the atmospheric pressure leaching process, Cu 2+ The circulating liquid with a concentration of 40g / L was mixed with the slurry in a volume ratio of 0.5:1, and acid leaching was carried out under the conditions of sulfuric acid and oxygen. The atmospheric leaching residue and atmospheric leaching liquid were obtained by filtration. The main components of the atmospheric leaching residue were Ni, Cu, and Fe, and the S2O3 of the atmospheric leaching liquid was 2- The content is 0.1mg / L.

[0106] 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, wherein the main component of the pressure leaching residue is iron slag.

[0107] In the first circulation step, the pressurized leaching solution is subjected to the first circulation treatment to obtain Cu 2+The circulating liquid with a concentration of 40 g / L is returned to the atmospheric pressure leaching process and used to mix with the slurry for atmospheric pressure acid leaching.

[0108] The method for removing thiosulfate from the nickel sulfate solution preparation process in this embodiment may also include the following steps:

[0109] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to P507 extraction and impurity removal to obtain a raffinate containing nickel.

[0110] In the evaporation and crystallization step, the raffinate is placed in an evaporation device for evaporation and crystallization, and then filtered to obtain a crystallization mother liquor and crystals containing nickel.

[0111] In the washing process, the evaporation equipment was circulated and washed with a 15% NaOH aqueous solution at a temperature of 60°C for 5 hours.

[0112] In the second circulation process, the crystallization mother liquor is used to prepare nickel soap, 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.

[0113] In the post-treatment step, the nickel-containing crystals are dissolved in water and filtered to obtain a nickel sulfate solution.

[0114] Example 3

[0115] This embodiment provides a method for removing thiosulfate from a nickel sulfate solution preparation process, wherein the nickel sulfide-containing material is high nickel matte, and specifically comprises the following steps:

[0116] In the slurrying process, the high-grade nickel matte is mixed with pure water to obtain a slurry with a solid content of 35%.

[0117] In the atmospheric pressure leaching process, Cu 2+ The circulating liquid with a concentration of 30g / L was mixed with the slurry in a volume ratio of 1.5:1, and acid leaching was carried out under the conditions of sulfuric acid and oxygen. The atmospheric leaching residue and atmospheric leaching liquid were obtained by filtration. The main components of the atmospheric leaching residue were Ni, Cu, and Fe, and the S2O3 of the atmospheric leaching liquid was 2- The content is 0.01mg / L.

[0118] 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, wherein the main component of the pressure leaching residue is iron slag.

[0119] In the first circulation step, the pressurized leaching solution is subjected to the first circulation treatment to obtain Cu 2+ The circulating liquid with a concentration of 30 g / L is returned to the atmospheric pressure leaching process and used to mix with the slurry for atmospheric pressure acid leaching.

[0120] The method for removing thiosulfate from the nickel sulfate solution preparation process in this embodiment may also include the following steps:

[0121] In the extraction and impurity removal process, the atmospheric pressure leaching solution is subjected to P507 extraction and impurity removal to obtain a raffinate containing nickel.

[0122] In the evaporation and crystallization step, the raffinate is placed in an evaporation device for evaporation and crystallization, and then filtered to obtain a crystallization mother liquor and crystals containing nickel.

[0123] In the washing process, the evaporation equipment was circulated and washed with a 15% NaOH aqueous solution at a temperature of 60°C for 5 hours.

[0124] In the second circulation process, the crystallization mother liquor is used to prepare nickel soap, 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.

[0125] In the post-treatment step, the nickel-containing crystals are dissolved in water and filtered to obtain a nickel sulfate solution.

[0126] Comparative Example 1

[0127] The difference from Example 1 is that Cu 2+ The circulating liquid with a concentration of 1g / L was mixed with the slurry in a volume ratio of 0.4:1, and the S2O3 2- The content is 1200mg / L.

[0128] Comparative Example 2

[0129] The difference from Example 1 is that Cu 2+ When the concentration was 50 g / L, crystallization occurred in the system, and a large amount of Cu was taken away by the pressurized leaching residue, and the system could not form an effective Cu cycle.

[0130] Table 1. Process conditions of various embodiments and comparative examples

[0131]

[0132] Referring to Table 1, it can be seen from Examples 1 to 3 that by using the method for removing thiosulfate from the process of preparing nickel sulfate solution provided in the examples of the present application, the S2O3 content of the nickel-containing atmospheric pressure leaching solution is 2- Content ≤1mg / L, including S2O3 2- The quality of nickel is basically not affected. In addition, S2O3 can be removed by further treating the atmospheric pressure leaching solution. 2- and other metal cation impurities to obtain S2O3 2- The nickel sulfate solution with lower impurity content and higher purity can be directly used as a raw material for producing battery positive electrode material precursors. In the comparative example, the nickel raw material was treated under different reaction conditions from those in the embodiment of the present application, and the S2O3 2-The content is much higher than that of S2O3 in the embodiment 2 - content, indicating that S2O3 can be effectively removed under the conditions of the present embodiment. 2- , in order to obtain nickel products with better quality.

[0133] It can be seen that in the embodiment of the present application, by controlling the Cu 2+ concentration, returning it to the atmospheric pressure leaching process and nickel batching can increase the CuS content in the atmospheric pressure acid leaching system, so that CuS is leached to form Cu 2+ , using free Cu 2+ With S2O3 2- The reaction achieves deep desulfurization, which is beneficial to ensure the purity of nickel products and greatly reduces the sulfur scaling problem in the subsequent evaporation and crystallization process. In addition, the desulfurization process does not consume additional auxiliary materials, only uses "self-produced" pressurized leaching solution, the desulfurization cost is low and no other impurities are introduced. In addition, alkaline solution is regularly used to circulate and wash the sulfur scale on the evaporation equipment, which ensures the heat exchange effect of the evaporation equipment and avoids the problem of sulfur scale in the evaporation equipment affecting evaporation energy consumption.

[0134] 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.

[0135] 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 thiosulfate from a nickel sulfate solution preparation process, characterized in that: The following steps are involved: A slurrying step of slurrying a nickel raw material to obtain a slurry, wherein the nickel raw material comprises at least one of high-grade nickel matte, low-grade nickel matte, nickel concentrate and a nickel sulfide intermediate; A normal pressure leaching step, wherein the slurry is subjected to normal pressure acid leaching to partially leach the nickel metal contained in the nickel raw material to obtain normal pressure leaching residue and normal pressure 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 having a copper ion concentration of 2 g / L to 40 g / L. The circulating solution is returned to the normal pressure leaching step and is used to be mixed with the slurry for normal pressure acid leaching.

2. The method for removing thiosulfate from the nickel sulfate solution preparation process according to claim 1, characterized in that: The reaction system of the atmospheric pressure acid leaching contains copper sulfide at a concentration of 3 g / L-50 g / L.

3. The method for removing thiosulfate from the nickel sulfate solution preparation process according to claim 1, characterized in that: In the atmospheric pressure leaching process, air or oxygen is introduced into the reaction environment of the atmospheric pressure acid leaching; And / or, the volume ratio of the circulating liquid to the slurry is (0.5-10):

1.

4. The method for removing thiosulfate from a nickel sulfate solution preparation process according to claim 1, characterized in that: In the slurrying process, the solid content of the slurry is 20% to 50%.

5. The method for removing thiosulfate from a nickel sulfate solution preparation process according to any one of claims 1 to 4, characterized in that: The method further comprises: An extraction and impurity removal step, wherein the atmospheric pressure leachate is subjected to extraction and impurity removal to obtain an extract containing impurities and a raffinate containing nickel; In the evaporation crystallization step, the raffinate is evaporated and crystallized, and then solid-liquid separation is performed to obtain a crystallization mother liquor and nickel-containing crystals.

6. The method for removing thiosulfate from the nickel sulfate solution preparation process according to claim 5, characterized in that: The method further comprises: The sulfur scale washing step uses an alkali solution to wash the sulfur scale to remove the sulfur attached to the evaporation equipment.

7. The method for removing thiosulfate from the nickel sulfate solution preparation process according to claim 6, characterized in that: The alkali in the alkali solution includes one or more of NaOH, Na2CO3, KOH, K2CO3, and NH3·H2O.

8. The method for removing thiosulfate from the nickel sulfate solution preparation process according to claim 7, characterized in that: 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 thiosulfate from the nickel sulfate solution preparation process according to claim 5, characterized in that: The method further comprises: In the second circulation step, the crystallization mother liquor is subjected to saponification treatment to obtain nickel soap, and the nickel soap is returned to the extraction and impurity removal step and used to extract and remove impurities from the atmospheric pressure leaching solution.

10. The method for removing thiosulfate from a nickel sulfate solution preparation process according to claim 5, characterized in that: The method further comprises: In the post-treatment process, the crystals are dissolved, and a trace amount of water-insoluble matter is filtered out through solid-liquid separation to obtain a nickel-containing solution.

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