A method for removing calcium and magnesium from cobalt-nickel hydroxide raw materials

Abstract

The present invention discloses a method for removing calcium and magnesium from cobalt-nickel hydroxide raw materials, which relates to the technical field of hydrometallurgy. First, the cobalt-nickel hydroxide raw materials are slurried with deionized water, and the slurry is used to wash away residual water-soluble calcium / magnesium by pressurized stirring with carbon dioxide at room temperature, and this process is the first impurity removal; subsequently, ferrous sulfate is used as an auxiliary bleaching agent to further wash away calcium / magnesium, which is the second impurity removal; the material after the second impurity removal is then dissolved with a mixture of sulfuric acid and ammonium phosphate, and after adjusting the pH value with ammonia water, most of the remaining calcium / magnesium ions are complexed to form calcium phosphate / magnesium ammonium precipitate and precipitate out. At this time, the cobalt-nickel material after filtration realizes the third purification and impurity removal. The nickel-cobalt material after three times of pre-removing calcium / magnesium can significantly reduce the impurity concentration in the acid dissolution solution, laying a solid foundation for shortening the extraction stage number, reducing the extraction workload, lowering the extraction input cost, and improving the product quality in the subsequent extraction production line.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and specifically to a method for pre-removing calcium and magnesium from cobalt-nickel hydroxide raw materials. Background Art

[0002] The mixed nickel-cobalt hydroxide raw material is an important raw material for producing battery-grade nickel sulfate and cobalt sulfate. With the rapid development of the new energy industry, the demand for ternary batteries mainly composed of nickel sulfate and cobalt sulfate has gradually increased. Therefore, preparing high-purity nickel sulfate and cobalt sulfate is a new requirement for the development of the industry.

[0003] Currently, in the process of preparing battery-grade nickel sulfate and cobalt sulfate by hydrometallurgy, extraction and chemical precipitation methods are usually used to remove calcium and magnesium. Among them, the extraction method uses P204 to extract and separate calcium, and C272 to extract and separate magnesium. This method has obvious disadvantages. When using P204 to extract and separate calcium, a large amount of calcium sulfate crystals are likely to block the extraction tank, and it is necessary to clean and remove the slag regularly, which affects normal production. When using C272 to extract and separate magnesium, a long extraction stage is required, the extraction is difficult, the equipment requirements are high, and the production cost is high. The chemical precipitation method generally uses fluoride as the precipitant, but the toxicity of fluoride will endanger human health and cause environmental pollution. Some researchers use a mixed solution of oxalic acid, sodium oxalate, and ammonium oxalate as the precipitant to remove calcium and magnesium. Although it avoids the use of toxic fluorides, it introduces new impurities, and these impurities are not easy to remove. Therefore, it is of great significance to select a non-toxic precipitant that does not introduce new impurities to remove calcium and magnesium impurities. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for removing calcium and magnesium from cobalt-nickel hydroxide raw materials to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solution: A method for removing calcium and magnesium from cobalt-nickel hydroxide raw materials, comprising the following preparation steps:

[0006] (1) Take 50 g of cobalt-nickel hydroxide raw materials, add 250 - 400 mL of deionized water, maintain the temperature at 10 - 50 °C, keep the carbon dioxide pressure at 0.30 - 0.65 MPa, stir at a speed of 240 - 650 rpm for 30 - 60 min, filter out the water-soluble calcium and magnesium solution, and send the nickel-cobalt filter residue to the next purification step;

[0007] (2) According to the residual calcium and magnesium content in the slag, add 1 - 2 g of solid ferrous sulfate; adjust the pH to 5 with dilute sulfuric acid, react for 2 - 8 h, perform solid-liquid separation to obtain a filtrate and a filter residue, and wash the filter residue with water spray; put the washed filter residue into an oven for drying to obtain a secondary impurity removal filter residue;

[0008] (3)Tertiary impurity removal: Acidify the secondary impurity removal filter residue with sulfuric acid - ammonium phosphate at a volume ratio of 1:0.5 - 1.5, control the temperature at 65 - 80 °C for 1 - 2.5 h, then add deionized water 2 - 3 times the weight of the first impurity removal filter residue and leach for 1 - 2 h to obtain an intermediate product solution; Add ammonia water to adjust the pH to 5.5 and react for 1 - 4.0 h. After the reaction, filter off the calcium phosphate / magnesium ammonium precipitate under a negative pressure of -0.075 Mpa to obtain an impurity-removed and purified nickel-cobalt solution. After vacuum filtration under negative pressure for 4 - 6 h, filter off the precipitate after the reaction to obtain the final impurity-removed raw material solution.

[0009] Further, the component ratio of the cobalt-nickel hydroxide raw material in step (1) is: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr.

[0010] Further, the concentration of the dilute sulfuric acid in step (2) is 25 - 50 wt%.

[0011] Further, the liquid-solid ratio of the spray washing water to the filter residue in step (2) is 5:1.

[0012] Further, the drying oven in step (2) dries at 80 °C for 2 h.

[0013] Further, the concentration of the sulfuric acid in step (3) is 85%.

[0014] Further, the concentration of the ammonium phosphate in step (3) is 15%.

[0015] Further, the concentration of the ammonia water in step (3) is 0.01 mol / L.

[0016] Further, the negative pressure filtration pressure in step (3) is -0.075 MPa.

[0017] Further, the filtration temperature in step (3) is 65 - 80 °C.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] First, the cobalt-nickel hydroxide raw material and deionized water are slurried according to a certain solid-liquid ratio. At room temperature, a carbon dioxide pressurized stirring device is used to wash the water-soluble calcium / magnesium in the material. Then, ferrous sulfate is used as an auxiliary calcium / magnesium removal reagent for secondary impurity removal. The secondary impurity removal has a high calcium / magnesium removal rate, a short reaction time, the introduced iron element is easy to remove, and the pressure on the subsequent extraction section is small. Using ferrous sulfate as an auxiliary precipitant to remove calcium and magnesium avoids the use of toxic fluorides and oxalate solutions that will introduce new impurities as precipitants, reducing environmental pollution. It avoids the impact on the system by using extractants to remove calcium and magnesium. Moreover, the newly introduced iron element can be hydrolyzed and precipitated into iron slag through the third impurity removal in the subsequent purification process, realizing the comprehensive recovery and utilization of resources.

[0020] Secondly, a sulfuric acid / ammonium phosphate / ammonia water system is used to perform a deeper third purification of the cobalt-nickel hydroxide after secondary impurity removal, precipitating the remaining calcium / magnesium / iron ions as calcium phosphate / magnesium ammonium and ammonium iron alum, etc., and effectively separating them from the cobalt / nickel solution. After the third impurity removal, the calcium concentration in the filtrate is <0.001 g / L, and the magnesium concentration is <1.0 g / L.

[0021] The calcium and magnesium removal rate in the cobalt-nickel hydroxide raw material after three purification treatments of the present invention can reach more than 85%, providing quality assurance for each process from raw material preparation, acid leaching to extraction. It has great reference value especially for optimizing the extraction process operation, reducing manual labor intensity, and lowering investment costs. The production cost of the present invention is low, and it has the prospect of industrial application. Specific Embodiments

[0022] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] Embodiment 1; (1) The component ratio of the cobalt-nickel hydroxide raw material is: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr. Take 50 g of the cobalt-nickel hydroxide raw material, add 250 mL of deionized water, stir and react at a rotation speed of 240 rpm for 30 min at room temperature of 11°C and a carbon dioxide autoclave pressure of 0.3 MPa, and then filter to obtain the primary purified cobalt-nickel slag.

[0024] (2) After stirring, perform impurity removal once: Calculate according to the calcium and magnesium content, and add 2 g of ferrous sulfate solid; adjust the pH to 5 with 25 wt% dilute sulfuric acid, react for 8 h, perform solid-liquid separation to obtain a filtrate and a filter residue, wash the filter residue by water spraying, and the liquid-solid ratio of water to the filter residue is 5:1; put the washed filter residue into a drying oven and dry it at 50 °C for 2 h to obtain the filter residue after the first impurity removal.

[0025] (3) Tertiary impurity removal: Mix the filter residue after secondary impurity removal and ammonium sulfate-phosphate in a volume ratio of 1:0.5, the concentration of sulfuric acid is 85%, then add deionized water twice the weight of the filter residue after the first impurity removal and stir to form a slurry, control the temperature at 65 °C, and carry out leaching reaction for 1.5 h to obtain a mixed solution of multi-metal ions; at this time, use ammonia water with a concentration of 1 mol / L to adjust the pH to 5.5, continue to react for 1.0 h, and then use a vacuum negative pressure of -0.075 MPa to filter the calcium phosphate / magnesium ammonium precipitate slag formed in the slurry to obtain a relatively pure cobalt-nickel solution.

[0026] Example 2; (1) The component ratio of the cobalt-nickel hydroxide raw material is: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr; Take 50 g of the cobalt-nickel hydroxide raw material, add 350 mL of deionized water, heat up to 23 °C, and stir and react at a speed of 350 rpm for 40 min under the condition of a carbon dioxide autoclave pressure of 0.4 MPa, and then filter to obtain the cobalt-nickel slag after the first purification.

[0027] (2) After stirring, perform impurity removal once: Calculate according to the calcium and magnesium content, and add 1.5 g of ferrous sulfate solid; adjust the pH to 5 with 35 wt% dilute sulfuric acid, react for 5 h, perform solid-liquid separation to obtain a filtrate and a filter residue, wash the filter residue by water spraying, and the liquid-solid ratio of water to the filter residue is 5:1; put the washed filter residue into a drying oven and dry it at 50 °C for 2 h to obtain the filter residue after the first impurity removal.

[0028] (3) Tertiary impurity removal: Mix the filter residue after secondary impurity removal and ammonium sulfate-phosphate in a volume ratio of 1:0.55, the concentration of sulfuric acid is 85%, then add deionized water twice the weight of the filter residue after the first impurity removal and stir to form a slurry, control the temperature at 69 °C, and carry out leaching reaction for 1.4 h to obtain a mixed solution of multi-metal ions; at this time, use ammonia water with a concentration of 1 mol / L to adjust the pH to 5.5, continue to react for 1.5 h, and then use a vacuum negative pressure of -0.075 MPa to filter the calcium phosphate / magnesium ammonium precipitate slag formed in the slurry to obtain a relatively pure cobalt-nickel solution.

[0029] Example 3; (1) The raw material composition ratio of cobalt-nickel hydroxide is as follows: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr; Take 50 g of cobalt-nickel hydroxide raw material, add 400 mL of deionized water, stir and react at a speed of 430 rpm for 30 min under the conditions of heating to 32 °C and a carbon dioxide autoclave pressure of 0.5 MPa, and then filter to obtain the primary purified cobalt-nickel slag;

[0030] (2) After the stirring is completed, perform the first impurity removal: Calculate according to the calcium and magnesium content, and add 1 g of ferrous sulfate solid; Adjust the pH to 5 with 50 wt% dilute sulfuric acid, react for 2 h, perform solid-liquid separation to obtain the filtrate and the filter residue, and wash the filter residue by water spraying. The liquid-solid ratio of water to the filter residue is 5:1; Put the washed filter residue into the drying oven and dry it at 80 °C for 2 h to obtain the secondary purified filter residue;

[0031] (3) The third impurity removal: Mix the secondary purified filter residue with sulfuric acid-ammonium phosphate in a volume ratio of 1:0.6, the concentration of sulfuric acid is 85%, then add deionized water 2.5 times the weight of the first impurity removal filter residue and stir to form a slurry, control the temperature at 72 °C, and leach and react for 1.3 h to obtain a mixed solution of multi-metal ions; At this time, use ammonia water with a concentration of 1 mol / L to adjust the pH to 5.5, continue to react for 2.0 h, and then filter the calcium phosphate / magnesium ammonium precipitate slag formed in the slurry under a vacuum negative pressure of -0.075 MPa to obtain a relatively pure cobalt-nickel solution.

[0032] Example 4; (1) The raw material composition ratio of cobalt-nickel hydroxide is as follows: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr; Take 50 g of cobalt-nickel hydroxide raw material, add 250 mL of deionized water, stir and react at a speed of 520 rpm for 30 min under the conditions of heating to 41 °C and a carbon dioxide autoclave pressure of 0.55 MPa, and then filter to obtain the primary purified cobalt-nickel slag;

[0033] (2) After the stirring is completed, perform the first impurity removal: Calculate according to the calcium and magnesium content, and add 1.5 g of ferrous sulfate solid; Adjust the pH to 5 with 35 wt% dilute sulfuric acid, react for 6 h, perform solid-liquid separation to obtain the filtrate and the filter residue, and wash the filter residue by water spraying. The liquid-solid ratio of water to the filter residue is 5:1; Put the washed filter residue into the drying oven and dry it at 50 °C for 2 h to obtain the first impurity removal filter residue;

[0034] (3) Tertiary impurity removal: The secondary impurity removal filter residue is mixed with sulfuric acid - ammonium phosphate in a volume ratio of 1:0.65. The concentration of sulfuric acid is 85%. Then, deionized water 3.0 times the weight of the primary impurity removal filter residue is added and stirred to form a slurry. The temperature is controlled at 75 °C, and the leaching reaction is carried out for 1.2 h to obtain a mixed solution of multi-metal ions. At this time, ammonia water with a concentration of 1 mol / L is used to adjust the pH to 5.5, and after continuing the reaction for 2.5 h, calcium phosphate / magnesium ammonium precipitate slag formed in the slurry is filtered under a vacuum negative pressure of -0.075 MPa to obtain a relatively pure cobalt-nickel solution.

[0035] Example 5; (1) The component ratio of the cobalt-nickel hydroxide raw material is: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr. Take 50 g of the cobalt-nickel hydroxide raw material, add 380 mL of deionized water, and stir and react at a speed of 630 rpm for 30 min under the conditions of the temperature rising to 46 °C and the carbon dioxide autoclave pressure of 0.60 MPa, and then filter to obtain the primary purified cobalt-nickel slag.

[0036] (2) After the stirring is completed, primary impurity removal is carried out: According to the calcium and magnesium content, 2 g of ferrous sulfate solid is added; the pH is adjusted to 5 with 35 wt% dilute sulfuric acid, and the reaction is carried out for 4.5 h. Solid-liquid separation is carried out to obtain a filtrate and a filter residue. The filter residue is washed by water spraying, and the liquid-solid ratio of water to the filter residue is 5:1. The washed filter residue is put into a drying oven and dried at 50 °C for 2 h to obtain the primary impurity removal filter residue.

[0037] (3) Tertiary impurity removal: The secondary impurity removal filter residue is mixed with sulfuric acid - ammonium phosphate in a volume ratio of 1:0.70. The concentration of sulfuric acid is 85%. Then, deionized water 3.5 times the weight of the primary impurity removal filter residue is added and stirred to form a slurry. The temperature is controlled at 80 °C, and the leaching reaction is carried out for 1.0 h to obtain a mixed solution of multi-metal ions. At this time, ammonia water with a concentration of 1 mol / L is used to adjust the pH to 5.5, and after continuing the reaction for 3.5 h, calcium phosphate / magnesium ammonium precipitate slag formed in the slurry is filtered under a vacuum negative pressure of -0.075 MPa to obtain a relatively pure cobalt-nickel solution.

[0038] Comparative Example 1; The difference between Comparative Example 1 and Example 3 lies in step (1). Step (1) is changed to: The component ratio of the cobalt-nickel hydroxide raw material is: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, 0.0099% Cr. Take 50 g of the cobalt-nickel hydroxide raw material, add 400 mL of deionized water, filter after heating to 32 °C and keeping warm for 30 min to obtain the primary purified cobalt-nickel slag. The remaining steps are the same as those in Example 3.

[0039] Comparative Example 2; The difference between Comparative Example 2 and Example 3 lies in step (3). Step (3) is changed to: Mix the secondary impurity removal filter residue and ammonium sulfate - phosphate in a volume ratio of 1:0.6 and add them. The concentration of sulfuric acid is 85%. Then add deionized water 2.5 times the weight of the once - removed impurity filter residue and stir to form a slurry. Control the temperature at 72°C and carry out the leaching reaction for 1 h / 20 min to obtain a relatively pure cobalt - nickel solution; the remaining steps are the same as those in Example 3.

[0040] Effect Example

[0041] The following Table 1 gives the performance analysis results of removing calcium and magnesium from a cobalt - nickel hydroxide raw material using Examples 1 - 5 and Comparative Examples 1 - 2 of the present invention.

[0042] Table 1

[0043]

[0044] From the comparison of the experimental data of the examples and comparative examples, it can be found that after three - stage pre - purification and impurity removal, the calcium content in the nickel - cobalt filter residue is <0.003%, and the magnesium content is <1%. The removal rate of calcium and magnesium after treating by this method can reach over 85%, and the loss rate of cobalt and nickel is controlled within 0.1%. It can achieve the removal of impurities such as calcium and magnesium in the stock - preparation stage, greatly reducing the calcium, magnesium, iron and other impurities in the solution flowing into the extraction line, and significantly reducing the load on the extraction equipment and the working pressure of manual operation.

[0045] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above - mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claimed rights.

Claims

1. A method for removing calcium and magnesium from cobalt nickel hydroxide raw materials, characterized in that: The method comprises the following preparation steps: (1) Take 50g of cobalt nickel hydroxide raw material, add 250-400mL of deionized water, maintain the temperature at 10-50°C, maintain the carbon dioxide pressure at 0.30-0.65MPa, stir at 240-650rpm for 30-60min, filter out the water-soluble calcium and magnesium solution, and send the nickel-cobalt filter residue to the next step of purification; (2) According to the residual calcium and magnesium content in the residue, add 1-2g of solid ferrous sulfate; adjust the pH to 5 with dilute sulfuric acid, react for 2-8h, separate the solid and liquid to obtain filtrate and residue, and wash the residue with water spray; put the washed residue into a drying oven to dry to obtain a secondary impurity-removed residue; (3) Three times of impurity removal: acidify the filter residue from the second impurity removal with sulfuric acid-ammonium phosphate in a volume ratio of 1:0.5-1.5, control the temperature at 65-80°C, and leach for 1-2.5 hours, then add deionized water 2-3 times the weight of the filter residue from the first impurity removal, and leach for 1-2 hours to obtain an intermediate product solution; add ammonia water to adjust the pH to 5.5 and react for 1-4.0 hours. After the reaction is completed, filter out the calcium phosphate / ammonium magnesium precipitate under a negative pressure of -0.075 MPa to obtain a purified nickel-cobalt solution, and filter out the precipitate under negative pressure for 4-6 hours. After the reaction is completed, filter out the precipitate to obtain the final impurity-removed raw material solution.

2. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: The proportion of the raw material components of cobalt nickel hydroxide in step (1) is: 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn, 0.011% Ca, 6.57% Mg, 0.41% Na, 0.0011% Cd, and 0.0099% Cr.

3. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: The concentration of dilute sulfuric acid in step (2) is 25-50wt%.

4. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: In the step (2), the liquid-to-solid ratio of the spray washing water to the filter residue is 5:

1.

5. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: In step (2), the mixture is dried in a drying oven at 80° C. for 2 h.

6. The method for removing calcium and magnesium from a cobalt-nickel hydroxide raw material according to claim 1, characterized in that: The concentration of sulfuric acid in step (3) is 85%.

7. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: The concentration of ammonium phosphate in step (3) is 15%.

8. The method for removing calcium and magnesium from a cobalt-nickel hydroxide raw material according to claim 1, characterized in that: The concentration of ammonia water in step (3) is 0.01 mol / L.

9. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: The negative pressure filtration pressure in step (3) is -0.075 MPa.

10. The method for removing calcium and magnesium from a cobalt nickel hydroxide raw material according to claim 1, characterized in that: The filtration temperature in step (3) is 65-80°C.

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