Method for removing thiosulfate from nickel sulfate solution preparation process

Abstract

The present application provides a method for removing thiosulfate from a nickel sulfate solution preparation process. The method comprises the following steps: a slurrying procedure: 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 ore concentrate, and a nickel sulfide intermediate product; an atmospheric pressure leaching procedure: performing atmospheric pressure acid leaching on the slurry to leach out at least part of the metal nickel from the nickel raw material, to obtain an atmospheric pressure leaching residue and an atmospheric pressure leaching solution; a pressurized leaching procedure: performing pressurized acid leaching on the atmospheric pressure leaching residue to leach out nickel contained in the atmospheric pressure leaching residue, to obtain a pressurized leaching residue and a pressurized leaching solution; and a first recycling procedure: performing a first recycling treatment on the pressurized leaching solution to obtain a recycled solution having a copper ion concentration of 2-40 g / L, and returning the recycled solution to the atmospheric pressure leaching procedure for mixing with the slurry for atmospheric pressure acid leaching. The method provided in embodiments of the present application can effectively separate nickel from impurities such as thiosulfate, thereby obtaining a nickel product having better quality.

Description

Methods for removing thiosulfate ions during the preparation of nickel sulfate solution

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411216417.1, filed on August 30, 2024, entitled “Method for removing thiosulfate from nickel sulfate solution during preparation”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of nickel sulfate preparation technology, and more particularly to a method for removing thiosulfate ions from the preparation process of nickel sulfate solution. Background Technology

[0004] Currently, the preparation process of nickel sulfate solution typically involves leaching the nickel raw material to convert it into an ionic form, thereby separating the nickel from other components such as sulfides, and then leaching the nickel from the raw material in stages to obtain the nickel product. However, in these related technologies, some impurities may be mixed into the nickel product, resulting in poor quality. Summary of the Invention

[0005] This application provides a method for removing thiosulfate ions during the preparation of nickel sulfate solution. This method can effectively separate impurities such as nickel and thiosulfate ions, thereby facilitating the production of nickel products with better quality.

[0006] This application provides a method for removing thiosulfate ions during the preparation of nickel sulfate solution, comprising the following steps: a slurrying step, wherein the nickel raw material is slurried 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; an atmospheric pressure leaching step, wherein the slurry is subjected to atmospheric pressure acid leaching to leach at least a portion of the nickel in the nickel raw material, to obtain atmospheric pressure leaching residue and atmospheric pressure leaching solution; a pressure leaching step, wherein the atmospheric pressure leaching residue is subjected to pressure acid leaching to leach the nickel contained in the atmospheric pressure leaching residue, to obtain pressure leaching residue and pressure leaching solution; and a first circulation step, wherein the pressure leaching solution is subjected to a first circulation treatment to obtain a circulating liquid with a copper ion concentration of 2 g / L to 40 g / L, the circulating liquid being returned to the atmospheric pressure leaching step and used to mix with the slurry for atmospheric pressure acid leaching.

[0007] The method for removing thiosulfate ions during the preparation of nickel sulfate solution provided in this application embodiment facilitates the complete leaching of nickel from the nickel raw material by first slurrying the nickel raw material, followed by atmospheric pressure acid leaching and pressurized acid leaching. Furthermore, in the first cycle step, the pressurized leaching solution is processed to obtain a circulating solution with a copper ion concentration of 2 g / L to 40 g / L. This circulating solution is then mixed with the nickel raw material slurry for atmospheric pressure acid leaching. This ensures that the atmospheric pressure acid leaching reaction system maintains an appropriate amount of Cu in the continuous nickel sulfate preparation process. 2+ Therefore, Cu is utilized 2+ With S2O3 2 - The reaction produces CuS precipitate and SO4. 2- After solid-liquid separation, atmospheric pressure leaching residue containing CuS and residue containing Ni can be obtained. 2+ The atmospheric pressure leachate is beneficial for preparing S2O3 removal solution. 2- The resulting nickel products are of even higher quality.

[0008] In some embodiments of this application, the concentration of copper sulfide in the atmospheric pressure acid leaching reaction system is 3 g / L-50 g / L.

[0009] In some embodiments of this application, in the first cycle step, the first cycle treatment includes diluting or concentrating the pressurized leachate to obtain a circulating liquid with a copper ion concentration of 2 g / L to 40 g / L.

[0010] In some embodiments of this application, the volume ratio of the circulating liquid to the slurry is (0.5-10):1.

[0011] In some embodiments of this application, in the pulping process, nickel raw materials are mixed with water and pulped to obtain a slurry.

[0012] In some embodiments of this application, the solid content of the slurry is 20% to 50%.

[0013] In some embodiments of this application, air or oxygen is introduced into the atmospheric pressure acid leaching reaction environment during the atmospheric pressure leaching process.

[0014] In some embodiments of this application, the acid used for the atmospheric pressure acid leaching includes sulfuric acid.

[0015] In some embodiments of this application, the method further includes: an extraction and impurity removal step, in which the atmospheric pressure leachate is extracted and impurities are removed to obtain an extract containing impurities and a raffinate containing nickel; and 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 nickel-containing crystals.

[0016] In some embodiments of this application, the method further includes a sulfur scale washing step, in which the sulfur scale is washed with an alkaline solution to remove the sulfur adhering to the evaporation equipment.

[0017] In some embodiments of this application, the alkaline solution includes one or more of NaOH, Na2CO3, KOH, K2CO3, and NH3·H2O.

[0018] In some embodiments of this application, the alkaline solution is an aqueous solution of alkali with a mass percentage concentration of 0.5% to 50%.

[0019] In some embodiments of this application, the washing temperature is 60°C to 100°C.

[0020] In some embodiments of this application, the washing time is 1 hour to 36 hours.

[0021] In some embodiments of this application, the method further includes: a second cycle step, in which the crystallization mother liquor is saponified 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 leachate.

[0022] In some embodiments of this application, the method further includes a post-processing step, in which the crystal is dissolved and subjected to solid-liquid separation to remove trace amounts of water-insoluble matter, thereby obtaining a nickel-containing solution.

[0023] In some embodiments of this application, the dissolution includes dissolving the crystal in water.

[0024] Additional technical solutions and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 is a flowchart of a method for removing thiosulfate ions from the preparation process of nickel sulfate solution according to some embodiments of this application;

[0027] Figure 2 is a flowchart of a method for removing thiosulfate ions from the preparation process of nickel sulfate solution provided in some embodiments of this application. Detailed Implementation

[0028] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0030] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0031] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0032] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0033] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: 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).

[0034] In this application, nickel raw material refers to a mixture containing nickel sulfide and a nickel metal eutectic. In some examples, nickel raw material can be high-grade nickel matte, low-grade nickel matte, nickel concentrate, nickel sulfide intermediates (nickel cobalt sulfide, MSP), etc. High-grade nickel matte and low-grade nickel matte both refer to mixtures containing nickel and other metal sulfides, such as NiS and Ni3S2. The nickel content in high-grade nickel matte is typically above 60%, while the nickel content in low-grade nickel matte is typically below 40%. In some examples, both high-grade and low-grade nickel matte can be intermediate products in the nickel smelting process, such as a eutectic melt of nickel, copper, iron, cobalt, and other metal sulfides obtained by smelting nickel concentrate in an electric or converter furnace.

[0035] It should be noted that the water used in the embodiments of this application can all be pure water. Among them, pure water generally refers to water with an electrical conductivity of less than or equal to 10 μS / cm, total organic carbon of less than or equal to 20 mg / L, metal ions (Na, K, Ca, Mg, etc.) of less than or equal to 1000 μg / L, and other ions (Cl-, NO3-, etc.) of less than or equal to 2000 μg / L.

[0036] Solid-liquid separation refers to the process of separating solids and liquids. The method for solid-liquid separation can be any method well known in the art for separating solids and liquids. For example, in some embodiments, solid-liquid separation can be performed by centrifugation, tilting, filtration, etc., and the solid-liquid separation described herein can be performed with reference to the above methods.

[0037] Referring to Figure 1, this application provides a method for removing thiosulfate ions from the preparation process of nickel sulfate solution, comprising the following steps:

[0038] S100, Slurrying process, which slurries nickel raw materials to obtain slurry, wherein the nickel raw materials include at least one of high-grade nickel matte, low-grade nickel matte, nickel concentrate and nickel sulfide intermediate.

[0039] S200, Atmospheric pressure leaching process, the slurry is subjected to atmospheric pressure acid leaching to leach at least part of the nickel metal from the nickel raw material, to obtain atmospheric pressure leaching residue and atmospheric pressure leaching solution.

[0040] S300, Pressure Leaching Process: The atmospheric leaching residue is subjected to pressure acid leaching to leach out the nickel contained in the atmospheric leaching residue, resulting in pressure leaching residue and pressure leaching solution.

[0041] S400, First Circulation Process: The pressurized leachate is processed through the first circulation to obtain a circulating liquid with a copper ion concentration of 2g / L to 40g / L. The circulating liquid is returned to the atmospheric pressure leaching process and used to mix with the slurry for atmospheric pressure acid leaching.

[0042] The method for removing thiosulfate ions during the preparation of nickel sulfate solution provided in this application embodiment facilitates the complete leaching of nickel from the nickel raw material by first slurrying the nickel raw material, followed by atmospheric pressure acid leaching and pressurized acid leaching. Furthermore, in the first cycle step, the pressurized leaching solution is processed to obtain a circulating solution with a copper ion concentration of 2 g / L to 40 g / L. This circulating solution is then mixed with the nickel raw material slurry for atmospheric pressure acid leaching. This ensures that the atmospheric pressure acid leaching reaction system maintains an appropriate amount of Cu in the continuous nickel sulfate preparation process. 2+ Therefore, Cu is utilized 2+ With S2O3 2 - The reaction produces CuS precipitate and SO4. 2- After solid-liquid separation, atmospheric pressure leaching residue containing CuS and residue containing Ni can be obtained. 2+ The atmospheric pressure leachate is beneficial for preparing S2O3 removal solution. 2- The resulting nickel products are of even higher quality.

[0043] 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. During atmospheric pressure acid leaching of high-grade nickel matte, the nickel sulfide it contains may be oxidized; incomplete oxidation of some of the nickel sulfide will generate S2O3. 2- Therefore, it is necessary to remove S2O3 during the preparation of nickel sulfate. 2- In order to minimize the impact on the purity of nickel products.

[0044] Specifically, in the process of preparing nickel sulfate solution from high-grade nickel matte, a circulating liquid with a copper ion concentration of 2 g / L to 40 g / L is mixed with the slurry in the first cycle step, followed by acid leaching under normal pressure. During the mixing process, Cu... 2+ It will undergo a displacement reaction with a large amount of sulfides in the slurry. Possible reactions include: FeS + Cu 2+ →Fe 2+ +CuS↓; NiS+Cu 2+ →Ni 2+ +CuS↓.

[0045] Through the above reaction, on the one hand, some nickel is converted into Ni. 2+This is beneficial for improving nickel recovery rate. On the other hand, it can increase the CuS content in the mixture of circulating liquid and slurry, meaning the CuS content in the atmospheric pressure acid leaching reaction system is higher. During atmospheric pressure leaching, CuS is relatively difficult to dissolve; specifically, its solubility is FeS (Ksp = 4.9 × 10⁻⁶). -18 NiS(Ksp=2.8×10) -21 CuS(Ksp=8.9×10) -35 Therefore, under normal pressure oxygen leaching conditions, FeS and NiS leach first, followed by CuS. The possible leaching reactions include: FeS + 2O₂ → Fe 2+ +SO4 2+ NiS + 2O2 → Ni 2+ +SO4 2+ CuS + 2O₂ → Cu 2+ +SO4 2+ .

[0046] As mentioned above, in this application, a suitable concentration of copper ions is recycled for atmospheric pressure acid leaching in the first cycle process, resulting in a sufficiently high CuS content in the reaction system. This allows a certain amount of Cu to be produced after the CuS is oxidized and leached. 2+ These copper ions can react with S2O3. 2- The reaction removes S2O3 2- It can also react with sulfides such as NiS to facilitate nickel leaching. Possible reactions include: Cu 2+ +S2O3 2- +H₂O→CuS↓+SO₄ 2- +2H + NiS+Cu 2+ →Ni 2+ +CuS↓.

[0047] Therefore, in the continuous nickel sulfate preparation process, by using Cu-containing... 2+ The pressurized leachate is recycled and reused to mix with the slurry for atmospheric pressure acid leaching, thereby improving the Cu content. 2+ The content is adjusted to facilitate deep removal of S2O3 during acid leaching under normal pressure. 2- While achieving the desired effect, it can also make Cu 2+ CuS precipitate is formed to separate it from nickel in the solution, ensuring the purity of the nickel product. Furthermore, this application also effectively recovers Cu from the pressure leaching solution. 2+ In the removal of S2O3 2- It does not introduce other impurities or hazardous chemicals, has low production costs, and high production safety.

[0048] To facilitate understanding of the technical solution of this application, high-grade nickel matte can be used as an example for the nickel raw materials in the following embodiments.

[0049] Because the acid leaching system under normal pressure may contain a high concentration of S2O3. 2- CuS is difficult to dissolve to form Cu 2+ This leads to Cu 2+ The low content affects S2O3 2- The removal effect is significant. Therefore, the CuS content in the atmospheric pressure acid leaching system should be maintained within a suitable range to facilitate the continuous generation of sufficient Cu. 2+ In order to remove as much S2O3 as possible 2- .

[0050] In some embodiments, the concentration of copper sulfide in the atmospheric pressure acid leaching reaction system is 3 g / L-50 g / L. For example, the concentration of copper sulfide in the atmospheric pressure acid leaching reaction system can be any value between 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 2 g / L-50 g / L.

[0051] Exemplarily, in some embodiments, the S2O3 in the reaction system of acid leaching under normal pressure 2- It may reach 100-3000 mg / L, while the reaction system can react with S2O3. 2- Free Cu in the reaction 2+ Extremely small amounts, approximately 0.1-5.0 mg / L, are insufficient to remove S2O3 in a single step. 2- At this point, CuS needs to be continuously added to the reaction system so that CuS reacts to form more free Cu. 2+ Therefore, the embodiments of this application will contain a suitable concentration of Cu. 2+ The circulating liquid is mixed with the slurry for atmospheric pressure acid leaching, which ensures that the CuS content in the reaction system is within the appropriate range mentioned above, thus facilitating the removal of S2O3 as much as possible. 2- .

[0052] It is understandable that the copper ion content in the pressure leachate may be insufficient or excessive. In this case, if the pressure leachate is directly mixed with the slurry for atmospheric pressure acid leaching, it will affect the S2O3 content. 2- The removal effect is not good, so the pressure leachate needs to be treated to keep the copper ion content within a suitable range.

[0053] In some embodiments, in the first cycle step, the first cycle treatment includes diluting or concentrating the pressure leachate to obtain a circulating liquid with a copper ion concentration of 2 g / L to 40 g / L. Exemplarily, dilution can be achieved by adding a solvent such as water to reduce the copper ion concentration, while concentration can be achieved 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 any value between 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, or 3 g / L to 40 g / L.

[0054] It should be noted that the copper ion concentration in the circulating solution should not be too low; otherwise, it will be difficult to achieve sufficient removal of S2O3. 2- The requirements are met; the copper ion concentration in the circulating liquid should not be too high, as excessive copper ion concentration will introduce too many copper ion impurities, increasing the difficulty of purifying nickel products. In this embodiment, by controlling the copper ion concentration in the circulating liquid within the aforementioned suitable range, S2O3 can be effectively removed. 2- This is beneficial for obtaining nickel products with higher purity.

[0055] In some embodiments, the volume ratio of the circulating liquid to the slurry is (0.5-10):1. Exemplarily, 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 facilitates thorough and uniform mixing of the circulating liquid and the slurry, and makes it easier to control the CuS content within a suitable range after mixing.

[0056] In some embodiments, during the slurrying process, the nickel raw material is mixed with water and slurried to obtain a slurry. Exemplarily, the water can be pure water. Preparing a slurry by adding water facilitates thorough mixing of the nickel raw material with the circulating liquid, which is beneficial for subsequent nickel leaching and removal of S2O3. 2- .

[0057] In some embodiments, the solid content of the slurry is 20% to 50%. Here, solid content refers to the total mass of solids in the slurry divided by the total mass of the slurry, that is, the mass percentage of the slurry remaining after drying. Exemplarily, the solid content of the slurry can be any value between 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 20% to 50%. The embodiments of this application control the solid content of the slurry within a suitable range, further enabling more uniform mixing of the nickel raw material and the circulating liquid, which is beneficial for the removal of S2O3. 2- .

[0058] Furthermore, in order to improve the leaching effect of atmospheric pressure acid leaching, the atmospheric pressure leaching process can be optimized.

[0059] In some embodiments, air or oxygen is introduced into the reaction environment of the atmospheric pressure acid leaching process. Supplementing the reaction system with air or oxygen at atmospheric pressure improves the leaching effect and increases the nickel leaching rate.

[0060] In some embodiments, the acid used for atmospheric pressure acid leaching includes sulfuric acid. In this application embodiment, sulfuric acid is selected for atmospheric pressure acid leaching, introducing sulfate ions so that the final leached nickel product is nickel sulfate. The resulting nickel sulfate can be directly applied in the battery field and has good application prospects.

[0061] Since atmospheric pressure leachate may contain impurities other than nickel, it can be further processed to remove other impurities as much as possible in order to improve the purity of nickel products.

[0062] Referring to Figure 2, in some embodiments, the method for removing thiosulfate ions from the preparation process of nickel sulfate solution further includes:

[0063] S500, Extraction and Impurity Removal Process: After the atmospheric pressure leachate is extracted and impurities removed, an extract containing impurities and a raffinate containing nickel are obtained.

[0064] S600, Evaporation and Crystallization Process: After evaporating and crystallizing the raffinate, solid-liquid separation is performed to obtain the mother liquor and nickel-containing crystals.

[0065] This application embodiment separates nickel from other metallic cationic impurities by extracting and evaporating the atmospheric pressure leachate, thus obtaining a nickel product with higher purity. Specifically, when the nickel raw material is high-grade nickel matte, other metallic impurities such as iron, manganese, calcium, cobalt, and magnesium may be leached during acid leaching. The corresponding extraction and impurity removal process can use different types of extractants to separate different metallic impurities in stages. For example, using P507 extractant can separate nickel and iron impurities, using P204 extractant can separate nickel from manganese and calcium impurities, and using C272 extractant can separate nickel from cobalt and magnesium impurities. Furthermore, evaporation and crystallization cause nickel to precipitate in crystalline form, while other impurities enter the crystallization mother liquor, which is beneficial for further impurity removal.

[0066] It should be noted that the atmospheric pressure leachate contains trace amounts of S2O3. 2- A disproportionation reaction may occur during the evaporation and crystallization process to generate elemental sulfur. Specifically, trace amounts of S₂O₃ may be produced. 2- Reactions that may occur when the sample enters the evaporation equipment under the high-temperature operating conditions include:

[0067] S2O3 2-+2H + =S↓+SO2↑+H2O.

[0068] In continuous nickel sulfate production processes, prolonged operation of the evaporation equipment can lead to the accumulation of elemental sulfur, forming sulfur scale that affects heat exchange efficiency. Furthermore, elemental sulfur may enter nickel-containing crystals, introducing impurities. Therefore, in some preferred applications, it is necessary to control the sulfur content of S2O3. 2- Any sulfur that may be generated is removed.

[0069] Referring again to Figure 2, in some embodiments, the method for removing thiosulfate ions from the preparation process of nickel sulfate solution further includes:

[0070] S700, sulfur scale washing process, uses alkaline solution to wash sulfur scale to remove sulfur adhering to the evaporation equipment.

[0071] In this embodiment, the reaction between alkaline solution and elemental sulfur (i.e., sulfur) effectively removes sulfur scale adhering to the evaporation equipment. Furthermore, in the continuous nickel sulfate preparation process, the alkaline solution can be periodically circulated to wash the sulfur scale within the evaporation equipment, for example, every 3 to 12 months, to dissolve the elemental sulfur, ensuring the heat exchange efficiency of the evaporation equipment, improving its thermal utilization rate, and preventing sulfur scale from affecting evaporation energy consumption. Simultaneously, removing the sulfur scale prevents sulfur impurities from entering nickel-containing crystals, thus avoiding a reduction in the purity of the nickel product.

[0072] In some embodiments, the alkaline solution includes one or more of NaOH, Na₂CO₃, KOH, K₂CO₃, and NH₃·H₂O. For example, when sodium hydroxide is selected as the alkaline solution, the possible reactions include:

[0073]

[0074] The above reaction converts elemental sulfur into soluble sulfides Na₂S and sulfites Na₂SO₃, effectively removing sulfur scale while preventing elemental sulfur from entering nickel-containing crystals. Furthermore, during the evaporation and crystallization process, Na₂S and Na₂SO₃ enter the mother liquor, while nickel enters the crystals, effectively separating sulfur impurities from nickel. This achieves deep desulfurization without introducing other impurities, thus ensuring the quality of nickel products.

[0075] In addition, the alkaline solution and washing conditions also affect the desulfurization effect, so the alkaline solution and washing conditions can be optimized.

[0076] In some embodiments, the alkali solution is an aqueous solution of alkali with a mass percentage concentration of 0.5% to 50%. Exemplarily, the concentration of the aqueous alkali solution can be any value between 0.5% and 50%, including 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 0.5% to 50%. In some embodiments, the washing temperature is 60°C to 100°C. Exemplarily, the washing temperature can be any value between 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or 60°C to 100°C. In some embodiments, the washing time is 1 hour to 36 hours. For example, the washing time can be any value between 1 hour, 3 hours, 6 hours, 9 hours, 12 hours, 15 hours, 18 hours, 21 hours, 24 hours, 27 hours, 30 hours, 33 hours, 36 hours, or 1 hour to 36 hours. By controlling the alkali solution and washing conditions within the above-mentioned suitable ranges, it is beneficial to further improve the desulfurization effect, while saving alkali solution consumption, reducing the time spent in the washing process, and improving the preparation efficiency of nickel sulfate.

[0077] Referring again to Figure 2, in some embodiments, the method for removing thiosulfate ions from the preparation process of nickel sulfate solution further includes:

[0078] S800, the second cycle process, the mother liquor of crystallization is treated with saponification to obtain nickel soap, the nickel soap is returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leachate.

[0079] In this embodiment, nickel soap is obtained by treating the mother liquor of crystallization. For example, the mother liquor of crystallization can be mixed with extractants such as P204 extractant and C272 extractant to obtain nickel soap. This allows for the reuse of the mother liquor of crystallization, avoids the accumulation of impurities during the evaporation and crystallization process, and helps to improve the quality of nickel products.

[0080] Referring again to Figure 2, in some embodiments, the method for removing thiosulfate ions from the preparation process of nickel sulfate solution further includes:

[0081] S900, post-processing step, dissolves the crystal, and then separates it into solid and liquid to remove trace amounts of water-insoluble matter, resulting in a nickel-containing solution.

[0082] In this embodiment, nickel-containing crystals are dissolved and then separated into solid and liquid components. This process removes insoluble impurities from the crystals and produces a liquid nickel-containing solution, such as a nickel sulfate solution, which can then be directly applied in the battery field.

[0083] In some embodiments, dissolution includes dissolving the crystals in water. Exemplarily, dissolution includes dissolving the crystals in pure water.

[0084] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents and raw materials used in the embodiments are commercially available or synthesized by conventional methods, as are the instruments used in the embodiments.

[0085] Example 1

[0086] This embodiment provides a method for removing thiosulfate ions from the preparation process of nickel sulfate solution, wherein the nickel raw material is high-grade nickel matte, and specifically includes the following steps:

[0087] The pulping process involves mixing high-grade nickel matte with pure water to produce a pulp with a solid content of 20%.

[0088] The atmospheric pressure leaching process is used to leach Cu 2+ A circulating liquid with a concentration of 3 g / L was mixed with the slurry at a volume ratio of 10:1. The mixture was then subjected to atmospheric pressure acid leaching under sulfuric acid and oxygen-bearing conditions. Filtration yielded atmospheric pressure leaching residue and atmospheric pressure leaching solution. The main components of the atmospheric pressure leaching residue were Ni, Cu, and Fe, while the atmospheric pressure leaching solution contained S2O3. 2- The content is 1.0 mg / L.

[0089] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and then filtered to obtain pressure leaching residue and pressure leaching solution. The main component of the pressure leaching residue is iron slag.

[0090] In the first cycle process, the pressurized leachate is processed to obtain Cu. 2+ The circulating liquid with a concentration of 3 g / L is returned to the atmospheric leaching process and used to mix with the slurry for atmospheric acid leaching.

[0091] The method for removing thiosulfate ions during the preparation of nickel sulfate solution in this embodiment may further include the following steps:

[0092] In the extraction and impurity removal process, the atmospheric pressure leachate is extracted and impurities are removed using a P507 extractor to obtain a raffinate containing nickel.

[0093] In the evaporation and crystallization process, the raffinate is placed in an evaporation device for evaporation and crystallization, and then filtered to obtain the mother liquor and nickel-containing crystals.

[0094] The washing process involves circulating and washing the evaporation equipment with a 15% NaOH aqueous solution at 60°C for 5 hours.

[0095] In the second cycle, the mother liquor from the crystallization process is used to prepare nickel soap. The nickel soap is then returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leachate.

[0096] In the post-processing step, the nickel-containing crystals are dissolved in water and filtered to obtain a nickel sulfate solution.

[0097] Example 2

[0098] This embodiment provides a method for removing thiosulfate ions from the preparation process of nickel sulfate solution, wherein the nickel raw material is high-grade nickel matte, and specifically includes the following steps:

[0099] The pulping process involves mixing high-grade nickel matte with pure water to produce a pulp with a solid content of 50%.

[0100] The atmospheric pressure leaching process is used to leach Cu 2+ A circulating liquid with a concentration of 40 g / L was mixed with the slurry at a volume ratio of 0.5:1. The mixture was then subjected to atmospheric pressure acid leaching under sulfuric acid and oxygen-bearing conditions. Filtration yielded atmospheric pressure leaching residue and atmospheric pressure leaching solution. The main components of the atmospheric pressure leaching residue were Ni, Cu, and Fe, while the atmospheric pressure leaching solution contained S2O3. 2- The content is 0.1 mg / L.

[0101] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and then filtered to obtain pressure leaching residue and pressure leaching solution. The main component of the pressure leaching residue is iron slag.

[0102] In the first cycle process, the pressurized leachate is processed to obtain Cu. 2+ The circulating liquid with a concentration of 40 g / L is returned to the atmospheric leaching process and used to mix with the slurry for atmospheric acid leaching.

[0103] The method for removing thiosulfate ions during the preparation of nickel sulfate solution in this embodiment may further include the following steps:

[0104] In the extraction and impurity removal process, the atmospheric pressure leachate is extracted and impurities are removed using a P507 extractor to obtain a raffinate containing nickel.

[0105] In the evaporation and crystallization process, the raffinate is placed in an evaporation device for evaporation and crystallization, and then filtered to obtain the mother liquor and nickel-containing crystals.

[0106] The washing process involves circulating and washing the evaporation equipment with a 15% NaOH aqueous solution at 60°C for 5 hours.

[0107] In the second cycle, the mother liquor from the crystallization process is used to prepare nickel soap. The nickel soap is then returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leachate.

[0108] In the post-processing step, the nickel-containing crystals are dissolved in water and filtered to obtain a nickel sulfate solution.

[0109] Example 3

[0110] This embodiment provides a method for removing thiosulfate ions from the preparation process of nickel sulfate solution, wherein the nickel sulfide-containing material is high-grade nickel matte, and specifically includes the following steps:

[0111] The pulping process involves mixing high-grade nickel matte with pure water to produce a pulp with a solid content of 35%.

[0112] The atmospheric pressure leaching process is used to leach Cu 2+ A circulating liquid with a concentration of 30 g / L was mixed with the slurry at a volume ratio of 1.5:1. The mixture was then subjected to atmospheric pressure acid leaching under sulfuric acid and oxygen-bearing conditions. Filtration yielded atmospheric pressure leaching residue and atmospheric pressure leaching solution. The main components of the atmospheric pressure leaching residue were Ni, Cu, and Fe, while the atmospheric pressure leaching solution contained S2O3. 2- The content is 0.01 mg / L.

[0113] In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching, and then filtered to obtain pressure leaching residue and pressure leaching solution. The main component of the pressure leaching residue is iron slag.

[0114] In the first cycle process, the pressurized leachate is processed to obtain Cu. 2+ The circulating liquid with a concentration of 30 g / L is returned to the atmospheric leaching process and used to mix with the slurry for atmospheric acid leaching.

[0115] The method for removing thiosulfate ions during the preparation of nickel sulfate solution in this embodiment may further include the following steps:

[0116] In the extraction and impurity removal process, the atmospheric pressure leachate is extracted and impurities are removed using a P507 extractor to obtain a raffinate containing nickel.

[0117] In the evaporation and crystallization process, the raffinate is placed in an evaporation device for evaporation and crystallization, and then filtered to obtain the mother liquor and nickel-containing crystals.

[0118] The washing process involves circulating and washing the evaporation equipment with a 15% NaOH aqueous solution at 60°C for 5 hours.

[0119] In the second cycle, the mother liquor from the crystallization process is used to prepare nickel soap. The nickel soap is then returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leachate.

[0120] In the post-processing step, the nickel-containing crystals are dissolved in water and filtered to obtain a nickel sulfate solution.

[0121] Comparative Example 1

[0122] The difference from Example 1 is that Cu 2+A circulating liquid with a concentration of 1 g / L was mixed with slurry at a volume ratio of 0.4:1. The resulting atmospheric pressure leachate contained S2O3. 2- The content is 1200 mg / L.

[0123] Comparative Example 2

[0124] The difference from Example 1 is that Cu 2+ At a concentration of 50 g / L, crystallization occurs in the system, and a large amount of Cu is carried away by the pressure leaching residue, preventing the system from forming an effective Cu cycle.

[0125] Table 1. Process conditions for each embodiment and comparative example

[0126] Referring to Table 1, it can be seen from Examples 1 to 3 that, using the method for removing thiosulfate ions during the preparation of nickel sulfate solution provided in this application, the S2O3 content of the nickel-containing atmospheric pressure leachate is reduced. 2- The content is ≤1mg / L, of which S2O3 2- It has virtually no impact on the quality of nickel. Furthermore, S2O3 can be removed by further treatment of the atmospheric pressure leaching solution. 2- Other metal cation impurities yield S2O3 2- A nickel sulfate solution with lower impurity content and higher purity can be directly used as a raw material for producing battery cathode material precursors. In the comparative example, different reaction conditions were used to treat the nickel raw material compared to the embodiments of this application, resulting in an atmospheric pressure leachate with lower S2O3 content. 2- The content of S2O3 was much higher than that in the example. 2- The content indicates that S2O3 can only be effectively removed under the conditions specified in the embodiments of this application. 2- This is to facilitate obtaining nickel products of better quality.

[0127] As can be seen, in the embodiments of this application, the Cu in the pressurized leaching solution is controlled. 2+ Increasing the concentration of CuS and returning it to the atmospheric pressure leaching process and nickel feedstock can increase the CuS content in the atmospheric pressure acid leaching system, allowing CuS to leach and form Cu. 2+ Utilizing free Cu 2+ With S2O3 2- The reaction achieves deep desulfurization, which helps ensure the purity of nickel products and significantly reduces the sulfur scaling problem in the subsequent evaporation and crystallization process. In addition, the desulfurization process does not consume additional auxiliary materials, only using "self-produced" pressurized leaching solution, resulting in low desulfurization costs and no introduction of other impurities. Furthermore, the regular use of alkaline solution to circulate and wash the sulfur scale on the evaporation equipment ensures the heat exchange effect of the evaporation equipment and avoids the problem of sulfur scale in the evaporation equipment affecting evaporation energy consumption.

[0128] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for removing thiosulfate ions from the preparation of nickel sulfate solution, comprising the following steps: The pulping process involves pulping nickel raw materials to obtain a slurry, wherein the nickel raw materials include at least one of high-grade nickel matte, low-grade nickel matte, nickel concentrate, and nickel sulfide intermediates. In the atmospheric pressure leaching process, the slurry is subjected to atmospheric pressure acid leaching to partially leach out the nickel metal contained in the nickel raw material, resulting in atmospheric pressure leaching residue and atmospheric pressure leaching solution. In the pressure leaching process, the atmospheric pressure leaching residue is subjected to pressure acid leaching to leach out the nickel contained in the atmospheric pressure leaching residue, resulting in pressure leaching residue and pressure leaching solution; In the first cycle process, the pressurized leachate is processed to obtain a circulating liquid with a copper ion concentration of 2g / L to 40g / L. The circulating liquid is returned to the atmospheric pressure leaching process and used to mix with the slurry for atmospheric pressure acid leaching.

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

3. The method for removing thiosulfate ions from the preparation process of nickel sulfate solution according to claim 1, wherein, 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 ions from the preparation process of nickel sulfate solution according to claim 1, wherein, In the pulping process, the solid content of the pulp is 20% to 50%.

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

6. The method for removing thiosulfate ions from the preparation process of nickel sulfate solution according to claim 5, the method further comprising: The sulfur scale washing process involves washing the sulfur scale with an alkaline solution to remove the sulfur adhering to the evaporation equipment.

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

8. The method for removing thiosulfate ions from the preparation process of nickel sulfate solution according to claim 7, wherein, The alkaline solution is an aqueous solution of alkali, with a mass percentage concentration of 0.5% to 50%. Optionally, the washing temperature is 60℃~100℃; Optionally, the washing time is 1 hour to 36 hours.

9. The method for removing thiosulfate ions from the preparation process of nickel sulfate solution according to claim 5, the method further comprising: In the second cycle, the mother liquor of crystallization is treated with saponification to obtain nickel soap, which is then returned to the extraction and impurity removal process and used to extract and remove impurities from the atmospheric pressure leachate.

10. The method for removing thiosulfate ions from the preparation process of nickel sulfate solution according to claim 5, the method further comprising: In the post-processing step, the crystal is dissolved and subjected to solid-liquid separation to remove trace amounts of water-insoluble matter, resulting in a nickel-containing solution.

Images