Preparation method of high-purity cobalt sulfate solution

Abstract

The application provides a preparation method of high-purity cobalt sulfate solution, and the preparation method comprises the following steps: (1) mixing a cobalt sulfate solution containing impurities and sodium fluoride, performing a precipitation reaction, and obtaining a post-precipitation solution; (2) the post-precipitation solution in step (1) is sequentially subjected to nickel removal by a first resin and fluorine removal by a second resin, and a high-purity cobalt sulfate solution is obtained. The preparation method of high-purity cobalt sulfate solution provided by the application can realize efficient separation of impurities in the cobalt sulfate solution containing impurities, and can prepare high-purity cobalt sulfate solution.

Description

Technical Field

[0001] This invention relates to the field of separation and impurity removal technology, and in particular to a method for preparing a high-purity cobalt sulfate solution. Background Technology

[0002] The battery-grade cobalt sulfate required for the cathode material of ternary lithium batteries is mostly produced using nickel-cobalt hydroxide, an intermediate product of laterite nickel ore hydrometallurgy, or recycled crude cobalt hydroxide as raw material. These raw materials often contain impurity elements such as Ni, Fe, Mg, Al, Cr, Mn, Cu, Ca, Si, Pb, Zn, As, and Cd. Currently, the commonly used production process is sulfuric acid reduction leaching - solution extraction purification to remove impurities - extraction separation and enrichment of cobalt - evaporation crystallization.

[0003] Because the extraction and separation process used to remove impurities and enrich cobalt in the solution resulted in cobalt sulfate solution with excessive oil content, it often failed to meet battery-grade performance requirements in actual production due to excessive impurities. Given the current characteristics of long production processes and high purification costs caused by the diverse types and high content of impurities in raw materials, it is urgent to find a more efficient, simpler, and shorter process for producing high-purity cobalt sulfate solution to overcome the bottlenecks of existing technologies.

[0004] Therefore, it is necessary to provide a new method for producing high-purity cobalt sulfate solution. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a method for preparing a high-purity cobalt sulfate solution. First, sodium fluoride is used to remove calcium and magnesium precipitates, and then two types of resins are used in sequence to remove nickel and fluorine to obtain a high-purity cobalt sulfate solution. This method achieves efficient and selective removal of impurities such as calcium, magnesium and nickel from the cobalt sulfate solution.

[0006] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for preparing a high-purity cobalt sulfate solution, the method comprising the following steps: (1) Mix cobalt sulfate solution containing impurities and sodium fluoride to carry out precipitation reaction and obtain precipitated liquid.

[0007] (2) The precipitated liquid in step (1) is subjected to first resin adsorption to remove nickel and second resin adsorption to remove fluorine in sequence to obtain a high-purity cobalt sulfate solution.

[0008] The cobalt sulfate solution in this invention generally contains impurities such as nickel, calcium, magnesium, and copper. Since battery-grade cobalt sulfate requires extremely low impurity content, deep impurity removal is necessary. This invention first uses sodium fluoride to remove impurities such as calcium, magnesium, and copper, and then sequentially uses a first resin and a second resin to remove nickel and fluorine, thereby achieving the preparation of a high-purity cobalt sulfate solution. The process is simple, requires no organic solvents or extraction processes, and the resulting high-purity cobalt sulfate solution is free of oil and can be used as a battery-grade solution.

[0009] Preferably, the mass concentration of cobalt in the cobalt sulfate solution containing impurities in step (1) is 15~30 g / L, for example, it can be 15 g / L, 17 g / L, 19 g / L, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 27 g / L, 29 g / L or 30 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0010] Preferably, the cobalt sulfate solution containing impurities in step (1) includes impurity elements.

[0011] Preferably, the impurity elements include nickel, calcium, and magnesium.

[0012] Preferably, the mass concentration of nickel in the cobalt sulfate solution is 1~5 g / L, for example, it can be 1 g / L, 1.5 g / L, 1.9 g / L, 2.4 g / L, 2.8 g / L, 3.3 g / L, 3.7 g / L, 4.2 g / L, 4.6 g / L or 5 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] Preferably, the mass concentration of calcium in the cobalt sulfate solution is 0.1~3 g / L, for example, it can be 0.1 g / L, 0.5 g / L, 0.8 g / L, 1.1 g / L, 1.4 g / L, 1.8 g / L, 2.1 g / L, 2.4 g / L, 2.7 g / L or 3 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] Preferably, the magnesium concentration in the cobalt sulfate solution is 0.1~3 g / L, for example, it can be 0.1 g / L, 0.5 g / L, 0.8 g / L, 1.1 g / L, 1.4 g / L, 1.8 g / L, 2.1 g / L, 2.4 g / L, 2.7 g / L or 3 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the sodium fluoride in step (1) accounts for 1 to 5 wt% of the mass of the cobalt sulfate solution containing heterogeneous substances. For example, it can be 1 wt%, 1.5 wt%, 1.9 wt%, 2.4 wt%, 2.8 wt%, 3.3 wt%, 3.7 wt%, 4.2 wt%, 4.6 wt%, or 5 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the sodium fluoride in step (1) is added in the form of a sodium fluoride solid phase.

[0017] Preferably, the particle size D50 of the sodium fluoride solid phase is 5~15μm, for example, it can be 5μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm or 15μm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Sodium fluoride within this particle size range dissolves at a moderate rate when added to a cobalt sulfate solution containing impurities, thereby controlling the precipitation rate of fluoride impurities, reducing the entrainment of cobalt by the precipitate, and minimizing cobalt loss.

[0019] Preferably, the temperature of the precipitation reaction in step (1) is 30~50℃, for example, it can be 30℃, 33℃, 35℃, 37℃, 39℃, 42℃, 44℃, 46℃, 48℃ or 50℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the pH of the precipitation reaction is 2.5 to 3.0, for example, it can be 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the precipitation reaction time is 0.5 to 2 hours, for example, 0.5 hours, 0.7 hours, 0.9 hours, 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.7 hours, 1.9 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, in step (2), the first resin used for nickel adsorption includes Dusheng CH90Na type resin.

[0023] Dusheng CH90Na type resin contains iminodiacetic acid groups, which can capture impurities such as nickel and residual copper in the solution, thereby achieving the effect of nickel removal.

[0024] Originally, Dusheng CH90Na type resin also had a certain adsorption effect on cobalt. However, this application found that after introducing fluoride ions in the calcium and magnesium removal stage, the adsorption effect on cobalt significantly decreased during the first resin adsorption process for nickel removal, thus achieving selective adsorption of nickel. Research suggests that this phenomenon is caused by the possibility that fluoride ions may combine with trace metal impurities remaining in the framework structure of Dusheng CH90Na type resin, thereby reducing the actual adsorption pore size of the framework structure to a certain extent, ultimately leading to two theoretically selective adsorption processes. (1) Because nickel ions possess 3d 8 Electronic configuration. In an octahedral field, d 8 The configuration achieves a relatively high crystal field stabilization energy, meaning the ionic structure is very stable, with its electron cloud pulled more tightly by the atomic nucleus, resulting in a contraction of its ionic radius; while divalent cobalt ions possess 3d... 7 The electronic configuration, whose corresponding crystal field stabilization energy is lower than that of Ni 2+ Therefore, its binding of d electrons is relatively weak, resulting in a relatively large ionic radius. The reduced actual adsorption pore size of the Dusheng CH90Na type resin due to its framework structure makes it more susceptible to adsorption of Co with a larger ionic radius. 2+ The adsorption performance decreases, but it does not affect its adsorption of Ni. 2+ .

[0025] (2) Although Co 2+ The radius is larger, but Ni 2+ A smaller radius means it has a higher charge density, which makes Ni... 2+ The electrostatic interaction between nickel and the negatively charged sites of the functional group (iminodiacetic acid) on the resin is stronger, thus achieving selective adsorption of nickel.

[0026] Preferably, the flow rate of the liquid after nickel adsorption and removal by the first resin is 5~10 BV / h, for example, it can be 5 BV / h, 5.6 BV / h, 6.2 BV / h, 6.7 BV / h, 7.3 BV / h, 7.8 BV / h, 8.4 BV / h, 8.9 BV / h, 9.5 BV / h or 10 BV / h, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the temperature at which the first resin adsorbs and removes nickel is 30~45℃, for example, it can be 30℃, 32℃, 34℃, 35℃, 37℃, 39℃, 40℃, 42℃, 44℃ or 45℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] Preferably, step (2) further includes: using a first desorbent to perform a first desorption on the first resin after adsorption saturation.

[0029] Preferably, the first desorbent comprises sulfuric acid.

[0030] Preferably, the concentration of the sulfuric acid is 100~150 g / L, for example, it can be 100 g / L, 106 g / L, 112 g / L, 117 g / L, 123 g / L, 128 g / L, 134 g / L, 139 g / L, 145 g / L or 150 g / L, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] Preferably, the flow rate of the sulfuric acid is 0.1~0.5 BV / h, for example, it can be 0.1 BV / h, 0.15 BV / h, 0.19 BV / h, 0.24 BV / h, 0.28 BV / h, 0.33 BV / h, 0.37 BV / h, 0.42 BV / h, 0.46 BV / h or 0.5 BV / h, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the first desorption temperature is 60~70℃, for example, it can be 60℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0033] Preferably, in step (2), the second resin used for defluorination by the second resin includes a zirconium-loaded macroporous cation exchange resin.

[0034] Preferably, the zirconium content in the zirconium-supported macroporous cation exchange resin is 10-25 wt%, for example, it can be 10 wt%, 12 wt%, 14 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 22 wt%, 24 wt%, or 25 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] The present invention preferably selects resin with zirconium content within the above range for defluorination, which has a better fluorine removal effect and less loss of cobalt.

[0036] Preferably, the macroporous cation exchange resin supported on zirconium includes D001 resin and / or D002 resin.

[0037] The present invention preferably uses the above-mentioned resin for adsorption, which has a better selective adsorption effect of fluorine.

[0038] The present invention does not require a specific method for preparing the zirconium-loaded macroporous cationic resin; it can be prepared using conventional impregnation methods in the art.

[0039] Preferably, the flow rate of the precipitate after defluorination by the second resin adsorption is 2~5 BV / h, for example, it can be 2 BV / h, 2.4 BV / h, 2.7 BV / h, 3 BV / h, 3.4 BV / h, 3.7 BV / h, 4 BV / h, 4.4 BV / h, 4.7 BV / h or 5 BV / h, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the temperature at which the second resin adsorbs and removes fluoride is 20~50℃, for example, it can be 20℃, 24℃, 27℃, 30℃, 34℃, 37℃, 40℃, 44℃, 47℃ or 50℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Preferably, step (2) further includes: using a second desorbent to perform a second desorption on the second resin after adsorption saturation.

[0042] Preferably, the second desorbent comprises a sodium hydroxide solution.

[0043] Preferably, the concentration of the sodium hydroxide solution is 50~100g / L, for example, it can be 50g / L, 56g / L, 62g / L, 67g / L, 73g / L, 78g / L, 84g / L, 89g / L, 95g / L or 100g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the flow rate of the sodium hydroxide solution is 0.2~5 BV / h, for example, it can be 0.2 BV / h, 0.8 BV / h, 1.3 BV / h, 1.8 BV / h, 2.4 BV / h, 2.9 BV / h, 3.4 BV / h, 4 BV / h, 4.5 BV / h or 5 BV / h, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0045] Preferably, the second desorption temperature is 65~80℃, for example, it can be 65℃, 67℃, 69℃, 70℃, 72℃, 74℃, 75℃, 77℃, 79℃ or 80℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] As a preferred technical solution of the present invention, the method includes the following steps: (1) Mix a cobalt sulfate solution containing impurities and sodium fluoride powder with a particle size D50 of 5~15μm, wherein the sodium fluoride accounts for 1~5wt% of the mass of the cobalt sulfate solution containing impurities, and carry out a precipitation reaction for 0.5~2h at 30~50℃ and pH 2.5~3.0 to obtain a precipitated liquid; (2) The precipitate obtained in step (1) is subjected to first resin adsorption to remove nickel at 30~45℃ by Du Sheng CH90Na type resin. The flow rate of the precipitate is 5~10 BV / h. Then, it is subjected to second resin adsorption to remove fluoride at 20~50℃ by zirconium-loaded macroporous cation resin. The zirconium content in the zirconium-loaded macroporous cation resin is 10~25wt%. The flow rate of the precipitate in the second resin adsorption to remove fluoride is 2~5 BV / h, to obtain a high-purity cobalt sulfate solution. The first adsorption of the first resin after adsorption saturation was carried out at 60~70℃ using a sulfuric acid solution with a concentration of 100~150g / L, with a sulfuric acid flow rate of 0.1~0.5BV / h, to obtain a nickel sulfate solution. The second adsorption of the second resin after adsorption saturation was carried out at 65~80℃ using a sodium hydroxide solution with a concentration of 50~100g / L, with a sodium hydroxide flow rate of 0.2~5BV / h.

[0047] Compared with the prior art, the present invention has at least the following beneficial effects: The method for preparing high-purity cobalt sulfate solution provided by this invention involves sequential purification with sodium fluoride, adsorption with a first resin, and adsorption with a second resin. This method can remove impurities such as nickel, calcium, and magnesium from the high-purity cobalt sulfate solution and effectively reduce cobalt loss, thus showing broad application prospects. Detailed Implementation

[0048] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0049] It should be understood that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0050] Example 1 This embodiment provides a method for preparing a high-purity cobalt sulfate solution, the preparation method comprising the following steps: (1) A mixed cobalt sulfate solution containing impurities (cobalt mass concentration of 25 g / L, nickel mass concentration of 1.5 g / L, calcium mass concentration of 1.2 g / L, magnesium mass concentration of 0.8 g / L) and sodium fluoride powder with a particle size D50 of 10 μm were mixed, and the sodium fluoride accounted for 3.2 wt% of the mass of the cobalt sulfate solution containing impurities. The mixture was subjected to a precipitation reaction at 45 °C and pH 2.8 for 1 h to obtain the precipitated liquid. (2) The precipitate obtained in step (1) is subjected to first resin adsorption to remove nickel at 35°C by Du Sheng CH90Na type resin. The flow rate of the precipitate is 6 BV / h. Then, it is subjected to second resin adsorption to remove fluoride at 35°C by zirconium-loaded macroporous cation resin. The zirconium content in the zirconium-loaded macroporous cation resin (D001 resin) is 15 wt%. The flow rate of the precipitate in the second resin adsorption to remove fluoride is 3 BV / h, resulting in a high-purity cobalt sulfate solution. The first desorption was performed on the adsorption-saturated Du Sheng CH90Na type resin using a sulfuric acid solution with a concentration of 130 g / L at 65 °C, with a sulfuric acid flow rate of 0.2 BV / h, to obtain a nickel sulfate solution. The second desorption was performed on the adsorption-saturated zirconium-loaded macroporous cation exchange resin using a sodium hydroxide solution with a concentration of 70 g / L at 75 °C, with a sodium hydroxide solution flow rate of 3 BV / h.

[0051] Example 2 This embodiment provides a method for preparing a high-purity cobalt sulfate solution, the preparation method comprising the following steps: (1) A mixed cobalt sulfate solution containing impurities (cobalt mass concentration of 30 g / L, nickel mass concentration of 5 g / L, calcium mass concentration of 2.4 g / L, magnesium mass concentration of 3 g / L) and sodium fluoride powder with a particle size D50 of 5 μm, wherein the sodium fluoride accounts for 1 wt% of the mass of the cobalt sulfate solution containing impurities, is subjected to a precipitation reaction at 30 °C and pH 2.5 for 2 h to obtain a precipitated liquid; (2) The precipitated liquid in step (1) is subjected to first resin adsorption to remove nickel at 45°C by Du Sheng CH90Na type resin. The flow rate of the precipitated liquid is 10 BV / h. Then, it is subjected to second resin adsorption to remove fluoride at 20°C by zirconium-loaded macroporous cation resin. The zirconium content in the zirconium-loaded macroporous cation resin (D001 resin) is 25 wt%. The flow rate of the precipitated liquid in the second resin adsorption to remove fluoride is 2 BV / h, to obtain a high-purity cobalt sulfate solution. The first desorption was performed on the adsorption-saturated Du Sheng CH90Na type resin using a 100 g / L sulfuric acid solution at 70 °C, with a sulfuric acid flow rate of 0.1 BV / h, to obtain a nickel sulfate solution. The second desorption was performed on the adsorption-saturated zirconium-loaded macroporous cation exchange resin using a 100 g / L sodium hydroxide solution at 65 °C, with a sodium hydroxide flow rate of 5 BV / h.

[0052] Example 3 This embodiment provides a method for preparing a high-purity cobalt sulfate solution, the preparation method comprising the following steps: (1) A mixed cobalt sulfate solution containing impurities (cobalt mass concentration of 15 g / L, nickel mass concentration of 1 g / L, calcium mass concentration of 0.2 g / L, magnesium mass concentration of 0.4 g / L) and sodium fluoride powder with a particle size D50 of 15 μm were mixed, and the sodium fluoride accounted for 4.8 wt% of the mass of the cobalt sulfate solution containing impurities. The mixture was subjected to a precipitation reaction at 50 °C and pH 3.0 for 0.5 h to obtain the precipitated liquid. (2) The precipitate obtained in step (1) is subjected to first resin adsorption to remove nickel at 30°C by Du Sheng CH90Na type resin. The flow rate of the precipitate is 5 BV / h. Then, it is subjected to second resin adsorption to remove fluoride at 50°C by zirconium-loaded macroporous cation resin. The zirconium content in the zirconium-loaded macroporous cation resin (D001 resin) is 10 wt%. The flow rate of the precipitate in the second resin adsorption to remove fluoride is 5 BV / h, resulting in a high-purity cobalt sulfate solution. The first desorption was performed on the adsorption-saturated Du Sheng CH90Na type resin using a sulfuric acid solution with a concentration of 150 g / L at 60 °C, with a sulfuric acid flow rate of 0.4 BV / h, to obtain a nickel sulfate solution. The second desorption was performed on the adsorption-saturated zirconium-loaded macroporous cation exchange resin using a sodium hydroxide solution with a concentration of 50 g / L at 80 °C, with a sodium hydroxide solution flow rate of 0.5 BV / h.

[0053] Example 4 This embodiment provides a method for preparing a high-purity cobalt sulfate solution. Except for the particle size D50 of the sodium fluoride powder being 1 μm, the preparation method is the same as in Example 1, and will not be repeated here.

[0054] Example 5 This embodiment provides a method for preparing a high-purity cobalt sulfate solution. Except for the particle size D50 of the sodium fluoride powder being 25 μm, the preparation method is the same as in Example 1, and will not be repeated here.

[0055] Example 6 This embodiment provides a method for preparing a high-purity cobalt sulfate solution. The preparation method is the same as in Example 1, except that the Du Sheng CH90Na type resin is replaced with TP 207 type resin, and will not be described again here.

[0056] Example 7 This embodiment provides a method for preparing a high-purity cobalt sulfate solution. Except for the zirconium content in the zirconium-loaded macroporous cation exchange resin being 5 wt%, the preparation method is the same as in Example 1 and will not be repeated here.

[0057] Example 8 This embodiment provides a method for preparing a high-purity cobalt sulfate solution. Except for the zirconium content in the zirconium-loaded macroporous cation exchange resin being 30 wt%, the preparation method is the same as in Example 1 and will not be repeated here.

[0058] Comparative Example 1 This comparative example provides a method for preparing a high-purity cobalt sulfate solution. The preparation method is the same as that in Example 1 except that step (1) is omitted, and will not be repeated here.

[0059] Comparative Example 2 This comparative example provides a method for preparing a high-purity cobalt sulfate solution. Except for the first adsorption of fluorine with a second resin and the adsorption of nickel with a first resin, the preparation method is the same as in Example 1, and will not be repeated here.

[0060] Test method: The concentrations of cobalt, nickel, calcium, magnesium and fluorine in the high-purity cobalt sulfate solution obtained by ICP test step (2) were measured, and the total impurity concentration in the nickel sulfate solution was also measured.

[0061] The test results of the above embodiments and comparative examples are shown in Table 1.

[0062] Table 1 The following points can be observed from Table 1: (1) As can be seen from Examples 1-3, the method for preparing high-purity cobalt sulfate solution provided by the present invention achieves thorough impurity removal, high cobalt recovery rate, and extremely low impurity concentrations, with nickel concentrations below 0.002 mg / L, calcium concentrations below 0.002 mg / L, magnesium concentrations below 0.001 mg / L, and fluorine concentrations below 0.002 mg / L, meeting battery-grade standards. Moreover, the total impurity concentration in the nickel sulfate solution obtained by the present invention is below 0.61 mg / L, indicating high purity and broad application prospects.

[0063] (2) As can be seen from the combined examples 1 and 4-5, the present invention preferably controls the particle size of sodium fluoride powder within a reasonable range, which can better improve the cobalt recovery effect and the cobalt concentration in the obtained cobalt sulfate solution is higher.

[0064] (3) As can be seen from the combined examples 1 and 6, the present invention preferably uses Dusheng CH 90Na type resin, which has a better cobalt recovery effect and a better separation effect of calcium and magnesium, and the resulting cobalt sulfate solution has a higher purity.

[0065] (4) As can be seen from the combined examples 1 and 7-8, the zirconium content in the macroporous cation exchange resin loaded with zirconium is preferably within a specific range, which can better improve the recovery effect of cobalt and the purification effect of fluorine, and improve the purity of the final cobalt sulfate solution.

[0066] (5) In Comparative Example 1, the sodium fluoride precipitation step was not performed, and impurities such as calcium and magnesium were not effectively removed, which affected the nickel adsorption effect and resulted in high total impurities. In Comparative Example 2, the resin adsorption order was reversed, and fluoride ions affected the selectivity of the first resin for nickel, resulting in incomplete nickel removal and high fluoride residue.

[0067] In summary, the method for preparing high-purity cobalt sulfate solution provided by this invention sequentially removes impurities such as nickel, calcium, and magnesium from the cobalt sulfate solution through sodium fluoride purification, first resin adsorption, and second resin adsorption. Under preferred conditions, the concentrations of nickel, calcium, magnesium, and fluorine in the cobalt sulfate solution can be kept below 0.002 mg / L, 0.002 mg / L, 0.001 mg / L, and 0.002 mg / L, meeting battery-grade standards, and effectively reducing cobalt loss. Furthermore, the total impurity concentration in the nickel sulfate solution obtained by this invention is below 0.61 mg / L, indicating high purity and broad application prospects.

[0068] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high-purity cobalt sulfate solution, characterized in that, The preparation method includes the following steps: (1) Mix cobalt sulfate solution containing impurities and sodium fluoride to carry out precipitation reaction, and obtain the precipitated liquid; (2) The precipitated liquid in step (1) is subjected to first resin adsorption to remove nickel and second resin adsorption to remove fluorine in sequence to obtain a high-purity cobalt sulfate solution.

2. The preparation method according to claim 1, characterized in that, The mass concentration of cobalt in the cobalt sulfate solution containing impurities in step (1) is 15~30 g / L.

3. The preparation method according to claim 1 or 2, characterized in that, The cobalt sulfate solution containing impurities mentioned in step (1) includes impurity elements; Preferably, the impurity elements include nickel, calcium, and magnesium; Preferably, the mass concentration of nickel in the cobalt sulfate solution is 1~5 g / L; Preferably, the mass concentration of calcium in the cobalt sulfate solution is 0.1~3 g / L; Preferably, the magnesium concentration in the cobalt sulfate solution is 0.1~3 g / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The sodium fluoride mentioned in step (1) accounts for 1 to 5 wt% of the mass of the cobalt sulfate solution containing impurities.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The sodium fluoride mentioned in step (1) is added in the form of a sodium fluoride solid phase; Preferably, the particle size D50 of the sodium fluoride solid phase is 5~15μm.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The precipitation reaction in step (1) is carried out at a temperature of 30~50℃; Preferably, the pH of the precipitation reaction is 2.5 to 3.0; Preferably, the precipitation reaction takes 0.5 to 2 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that, In step (2), the first resin used for nickel adsorption includes Du Sheng CH90Na type resin; Preferably, the flow rate of the liquid after the first resin adsorbs and removes the nickel precipitate is 5~10 BV / h; Preferably, the temperature at which the first resin adsorbs and removes nickel is 30~45℃.

8. The preparation method according to any one of claims 1 to 7, characterized in that, Step (2) also includes: using a first desorbent to perform a first desorption on the first resin after adsorption saturation; Preferably, the first desorbent comprises sulfuric acid; Preferably, the concentration of the sulfuric acid is 100~150 g / L; Preferably, the flow rate of the sulfuric acid is 0.1~0.5 BV / h; Preferably, the temperature of the first desorption is 60~70°C.

9. The preparation method according to any one of claims 1 to 8, characterized in that, In step (2), the second resin used for defluorination by the second resin adsorption includes a zirconium-loaded macroporous cationic resin. Preferably, the zirconium content in the zirconium-supported macroporous cation exchange resin is 10-25 wt%. Preferably, the macroporous cation exchange resin supported on zirconium includes D001 resin and / or D002 resin. Preferably, the flow rate of the liquid after precipitation in the second resin adsorption and defluorination process is 2~5 BV / h; Preferably, the temperature at which the second resin adsorbs and removes fluoride is 20~50℃.

10. The preparation method according to any one of claims 1 to 9, characterized in that, Step (2) also includes: using a second desorbent to perform a second desorption on the second resin after adsorption saturation; Preferably, the second desorbent comprises a sodium hydroxide solution; Preferably, the concentration of the sodium hydroxide solution is 50~100g / L; Preferably, the flow rate of the sodium hydroxide solution is 0.2~5 BV / h; Preferably, the temperature of the second desorption is 65~80°C.

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