A method for preparing battery-grade nickel sulfate with a short process and low cost

Abstract

The present invention belongs to the technical field of non-ferrous metal hydrometallurgy, and specifically discloses a method for preparing battery-grade nickel sulfate in a short process and at a low cost. The raw material crude nickel hydroxide is placed in a tank, and acid is added to carry out an acidic leaching reaction; after the leaching reaction, sulfur dioxide gas is introduced into the tank for a reduction leaching reaction; after the reduction leaching, the filtrate is pressed, and the obtained filtrate is subjected to a neutralization and iron removal reaction; after the neutralization and iron removal reaction, the filtrate is pressed, and the obtained press filtrate is extracted and impurities are removed using a P507 extractant, and the obtained liquid is a pure nickel sulfate solution; the obtained pure nickel sulfate solution is sequentially demagnetized, evaporated and crystallized to obtain qualified battery-grade nickel sulfate. Compared with the traditional method of separating nickel, cobalt and manganese by multiple extraction lines, the present invention extracts impurity metals and does not extract main metals to obtain qualified battery-grade nickel sulfate hexahydrate products, which is a short process, low-cost and effective method for preparing battery-grade nickel sulfate.

Description

1. Technical field:

[0001] The invention belongs to the technical field of nonferrous metal hydrometallurgy, and in particular relates to a method for preparing battery-grade nickel sulfate with a short process and low cost. 2. Background technology:

[0002] Under high temperature and high pressure conditions, sulfuric acid is used as a leaching agent to extract the nickel, cobalt, iron, aluminum and other oxide elements from laterite nickel ore into the solution, and then the pH of the solution is adjusted to remove impurities such as iron and aluminum. A precipitant is added to obtain a relatively pure intermediate product, crude nickel hydroxide (Mixed Hydroxide Precipitate). The methods for preparing battery-grade nickel sulfate by MHP are mainly as follows: ① Acid leaching-impurity removal-extraction process, in which crude nickel hydroxide is slurried with water, and sulfuric acid solution is added in a certain proportion. After acid leaching, lime milk is added to precipitate impurities. The nickel sulfate solution obtained after impurity removal, aging and filtration is extracted and impurities are removed using extractants such as P204, P507, and C272 to obtain a high-purity nickel sulfate solution; this process can effectively leach nickel, and the product quality is stable, which can meet the requirements of battery-grade nickel sulfate, but the process is long, involves multiple steps, and has a high production cost. ② Oxidation roasting-acid leaching process, oxidizing and roasting the crude nickel hydroxide at a certain temperature to convert it into nickel oxide, and then acid leaching with sulfuric acid solution to dissolve the nickel to form a nickel sulfate solution, and then filtering and removing impurities to obtain a nickel sulfate solution that meets battery grade requirements; this process changes the structure and properties of nickel hydroxide, making the acid leaching process more efficient, improving the nickel leaching rate, and removing some organic matter and volatile impurities, reducing the difficulty and cost of subsequent processing, but it requires a lot of energy for roasting, which increases energy consumption costs. In addition, the roasting process may cause the oxidation state of some nickel to change, affecting the subsequent leaching and purification effects, and the roasting conditions need to be precisely controlled. ③ High-pressure acid leaching process: under high temperature and high pressure conditions, crude nickel hydroxide is acid-leached with sulfuric acid as the leaching agent, so that nickel is efficiently dissolved in the solution. At the same time, by controlling the reaction conditions and adding suitable catalysts, the leaching efficiency and selectivity are improved, and the leaching of impurities is reduced. The leaching solution undergoes subsequent purification, impurity removal, concentration and crystallization processes to produce battery-grade nickel sulfate. This process has high acid leaching efficiency and can achieve a high nickel leaching rate in a relatively short time. It can also improve the leaching selectivity, reduce the leaching of impurities, and reduce the difficulty and cost of subsequent purification by controlling the reaction conditions and adding catalysts. However, it has high requirements for equipment, and requires high temperature, high pressure and corrosion-resistant equipment, with high investment costs. In addition, the high temperature and high pressure operating conditions have certain safety risks, requiring strict safety management and monitoring measures. 3. Summary of the invention:

[0003] The technical problem to be solved by the present invention is: in view of the technical problems such as high cost and complicated operation process in the existing process of preparing battery-grade nickel sulfate using crude nickel hydroxide, the present invention provides a method for preparing battery-grade nickel sulfate with a short process and low cost. The technical scheme of the present invention uses the relatively pure intermediate product crude nickel hydroxide (with the characteristics of high content, relatively pure, and few types of impurities) produced by high-pressure acid leaching process of laterite nickel ore, passes sulfuric acid + sulfur dioxide for acid leaching and reduction leaching, and uses neutralization and iron removal and then extraction and impurity removal technology to prepare a pure nickel sulfate solution, and evaporates and crystallizes after demagnetization to become qualified battery-grade nickel sulfate. Compared with the traditional multiple extraction lines for separating nickel, cobalt, and manganese, the present invention extracts impurity metals and does not extract the main metal to obtain a battery-grade nickel sulfate hexahydrate product. It is a short process, low-cost, and effective method for preparing battery-grade nickel sulfate.

[0004] In order to solve the above problems, the technical solution adopted by the present invention is:

[0005] The present invention provides a method for preparing battery-grade nickel sulfate with a short process and low cost, the method comprising the following steps:

[0006] 1) placing crude nickel hydroxide in a tank and adding acid to carry out an acid leaching reaction;

[0007] 2) After the leaching reaction, sulfur dioxide gas is introduced into the tank to carry out a reduction leaching reaction;

[0008] 3) After the reduction leaching reaction, filter pressing is performed, and the obtained filtrate is subjected to a neutralization and iron removal reaction;

[0009] 4) After the neutralization and iron removal reaction, filter pressing is performed, and the obtained filtrate is extracted with a P507 extractant to remove impurities, and the obtained liquid is a pure nickel sulfate solution;

[0010] 5) demagnetizing the obtained pure nickel sulfate solution;

[0011] 6) The nickel sulfate solution obtained after demagnetization is evaporated and crystallized to obtain qualified battery-grade nickel sulfate.

[0012] According to the above-mentioned short-process and low-cost method for preparing battery-grade nickel sulfate, the crude nickel hydroxide in step 1) is the intermediate product crude nickel hydroxide produced after laterite nickel ore is treated by a conventional high-pressure acid leaching process.

[0013] According to the above short-process and low-cost method for preparing battery-grade nickel sulfate, the acid in step 1) is at least one of sulfuric acid, hydrochloric acid and nitric acid; the initial acidity when the acid is added is 65 to 85 g / L.

[0014] According to the above short-process and low-cost method for preparing battery-grade nickel sulfate, during the acid leaching reaction in step 1), the temperature is controlled to be between room temperature and 80° C., and the leaching time is between 0.5 and 2.5 hours.

[0015] According to the above-mentioned short-process and low-cost method for preparing battery-grade nickel sulfate, during the reduction leaching reaction in step 2), the leaching temperature is room temperature to 80° C., and the leaching time is 1 to 3 hours; the amount of sulfur dioxide gas introduced is 1.05 to 1.15 times the theoretical value.

[0016] When the raw materials are exposed to the air, the divalent nickel is inevitably oxidized to trivalent nickel. This part of the trivalent nickel acid cannot be dissolved and needs to be reduced with sulfur dioxide gas. During this reduction process, the theoretical consumption of sulfur dioxide is according to the reaction equation 2Ni 3+ +SO2+2H2O=2Ni 2+ +SO4 2- +4H + Perform calculations.

[0017] According to the above-mentioned short-process and low-cost method for preparing battery-grade nickel sulfate, the specific process of neutralizing and removing iron from the filtrate obtained in step 3) is as follows: hydrogen peroxide is first added to the obtained filtrate, and then a neutralizing agent is added to control its end point pH value to 4.0-5.5, and the neutralization and iron removal reaction is carried out at a temperature of 70-90°C for 0.5-2h.

[0018] According to the above-mentioned short-process and low-cost method for preparing battery-grade nickel sulfate, the amount of hydrogen peroxide added is 1.1 to 1.5 times the theoretical amount; and the neutralizing agent is at least one of calcium carbonate, calcium hydroxide and nickel hydroxide.

[0019] Calculation method of theoretical dosage of hydrogen peroxide: Calculate the theoretical dosage of hydrogen peroxide according to the content of divalent iron in the leaching solution. The reaction equation is: 2Fe 2+ +H2O2+2H + =2Fe 3+ +2H2O.

[0020] According to the above-mentioned short-process and low-cost method for preparing battery-grade nickel sulfate, in step 4), during the extraction process of the filtrate using P507 extractant, the O / A ratio is 2.2-3:1, and the volume ratio of sulfonated kerosene to P507 extractant is 2.5-4.5:1; the saponification rate of the organic phase is 55-65%, 25-35% liquid alkali is used for saponification, nickel conversion to soap is 6-8 levels, extraction level is 7-11 levels; washing is 11-14 levels; the stripping acidity is 2-3 mol / L, and the stripping level is 5-9 levels.

[0021] According to the above short-process and low-cost method for preparing battery-grade nickel sulfate, during the demagnetization in step 5), a magnetic bar with a surface magnetic field of 10,000 to 30,000 Gauss is selected for stirring for 25 to 35 minutes.

[0022] According to the above short-process and low-cost method for preparing battery-grade nickel sulfate, the evaporation in step 6) adopts a rotary evaporator, and the evaporation is carried out for 2 to 3 hours and then recrystallized for 5 to 7 hours.

[0023] The positive beneficial effects of the present invention are:

[0024] 1. In the preparation method of the present invention, the operation of each step is very simple, the equipment requirements are low, and it is conducive to large-scale application and promotion.

[0025] 2. In the preparation method of the invention, sulfuric acid + sulfur dioxide is used for acid leaching and reduction leaching, which can effectively leach valuable metals in the raw materials.

[0026] 3. In the extraction process of the technical solution of the present invention, an extractant is used and a semi-extraction method is adopted to extract impurity elements other than nickel in the liquid, which can effectively shorten the preparation steps of battery-grade nickel sulfate. The stripping liquid can be returned to the existing cobalt sulfate system, with a short process and low cost. 4. Description of the drawings:

[0027] Figure 1 A schematic diagram of the process flow of the method for preparing battery-grade nickel sulfate in a short process and at low cost according to the present invention. V. Specific implementation methods:

[0028] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the technical solution of the present invention is not limited thereto.

[0029] The crude nickel hydroxide used in the following examples is the intermediate product produced by a certain enterprise after treating laterite nickel ore with a conventional high-pressure acid leaching process.

[0030] Calculation method of theoretical amount of sulfur dioxide in step 2): When the raw material is exposed to air, divalent nickel is inevitably oxidized to trivalent nickel. This part of trivalent nickel acid cannot be dissolved and needs to be reduced with sulfur dioxide gas. During this reduction process, the theoretical consumption of sulfur dioxide is calculated according to the reaction equation 2Ni 3+ +SO2+2H2O=2Ni 2+ +SO4 2- +4H + Perform calculations.

[0031] In step 3), during the neutralization and iron removal reaction of the leaching solution, the theoretical amount of hydrogen peroxide used is calculated according to the content of divalent iron in the leaching solution. The reaction equation is: 2Fe 2+ +H2O2+2H + =2Fe 3+ +2H2O.

[0032] Embodiment 1:

[0033] The method for preparing battery-grade nickel sulfate with a short process and low cost of the present invention has the following detailed steps:

[0034] 1) Crude nickel hydroxide produced by a certain enterprise (the crude nickel hydroxide contains 34.6% nickel, 3.8% cobalt, 4.4% manganese and 1.1% zinc) is placed in a reaction tank, sulfuric acid is added, the initial acid concentration is 70g / L, and the acid leaching reaction is carried out at 70°C for 2h;

[0035] 2) After the leaching reaction, sulfur dioxide gas was introduced into the reaction tank at 70°C for 2 hours to carry out reduction leaching reaction (so that the concentration of sulfur dioxide in the leaching solution was 8.15%);

[0036] 3) After the reduction leaching reaction, the filter press is performed, the filtrate is heated to 85°C, 1.5 times the theoretical amount of hydrogen peroxide is added, and then nickel hydroxide is added to neutralize to a pH value of 4.5, and the neutralization and iron removal reaction is carried out under this condition for 1.5 hours;

[0037] 4) After the neutralization and iron removal reaction, the filter press is performed, and the obtained filtrate enters the extraction system, and the P507 extractant is used for extraction to remove impurities. During the extraction process: the O / A ratio is 2.5:1; the volume ratio of sulfonated kerosene to P507 extractant is 2.7:1; the organic phase saponification rate is 55%, 25% liquid alkali is used for saponification, nickel conversion to soap 7 levels, extraction level 9 levels, washing 12 levels, stripping acidity 2.5 mol / L, stripping level 8 levels, and the obtained stripping liquid is a pure nickel sulfate solution;

[0038] 5) the obtained pure nickel sulfate solution was stirred and demagnetized for 35 minutes using a magnetic bar having a surface magnetic field of 12000 Gauss;

[0039] 6) The nickel sulfate solution obtained after demagnetization is evaporated by a rotary evaporator for 2.5 hours and then crystallized for 6 hours to obtain qualified battery-grade nickel sulfate.

[0040] Embodiment 2:

[0041] 1) Crude nickel hydroxide produced by a certain enterprise (the crude nickel hydroxide contains 36.7% nickel, 1.8% cobalt, 2.4% manganese and 1.7% zinc) is placed in a reaction tank, sulfuric acid and hydrochloric acid are added, the initial acid concentration is 80g / L, and the acid leaching reaction is carried out at 50°C for 2.5h;

[0042] 2) After the leaching reaction, sulfur dioxide gas was introduced into the reaction tank at 50°C for 3 hours to carry out reduction leaching reaction (so that the concentration of sulfur dioxide in the leaching solution was 7.8%);

[0043] 3) After the reduction leaching reaction, filter press is performed, the obtained filtrate is heated to 70°C, 1.3 times the theoretical amount of hydrogen peroxide is added, and then calcium hydroxide and calcium carbonate are added to neutralize to a pH value of 5.5, and the neutralization and iron removal reaction is carried out under this condition for 2 hours;

[0044] 4) After the neutralization and iron removal reaction, the filter press is performed, and the obtained filtrate enters the extraction system, and the P507 extractant is used for extraction to remove impurities. During the extraction process: the O / A ratio is 3:1; the volume ratio of sulfonated kerosene to P507 extractant is 3.5:1; the organic phase saponification rate is 60%, 30% liquid alkali is used for saponification, nickel conversion to soap is 8 levels, extraction level is 11 levels, washing is 11 levels, stripping acidity is 2.0 mol / L, stripping level is 9 levels, and the obtained stripping liquid is a pure nickel sulfate solution;

[0045] 5) the obtained pure nickel sulfate solution was stirred and demagnetized with a magnetic bar having a surface magnetic field of 11000 Gauss for 25 minutes;

[0046] 6) The nickel sulfate solution obtained after demagnetization is evaporated by a rotary evaporator for 2 hours and then crystallized for 5 hours to obtain qualified battery-grade nickel sulfate.

[0047] Embodiment 3:

[0048] 1) Crude nickel hydroxide produced by a certain enterprise (the crude nickel hydroxide contains 35.9% nickel, 3.8% cobalt, 3.4% manganese and 1.5% zinc) is placed in a reaction tank, sulfuric acid and nitric acid are added, the initial acid concentration is 75g / L, and the acid leaching reaction is carried out at 80°C for 1h;

[0049] 2) After the leaching reaction, sulfur dioxide gas was introduced into the reaction tank at 80°C for 1 hour to carry out a reduction leaching reaction (so that the concentration of sulfur dioxide in the leaching solution was 8.3%);

[0050] 3) After the reduction leaching reaction, the filter press is performed, the obtained filtrate is heated to 80°C, 1.2 times the theoretical amount of hydrogen peroxide is added, and then nickel hydroxide and calcium hydroxide are added to neutralize to a pH value of 5.0, and the neutralization and iron removal reaction is carried out under this condition for 1 hour;

[0051] 4) After the neutralization and iron removal reaction, the filter press is performed, and the obtained filtrate enters the extraction system, and the P507 extractant is used for extraction to remove impurities. During the extraction process: the O / A ratio is 2.8:1; the volume ratio of sulfonated kerosene to P507 extractant is 4:1; the organic phase saponification rate is 55%, 25% liquid alkali is used for saponification, nickel conversion to soap is 6 levels, extraction level is 10 levels, washing is 13 levels, stripping acidity is 2.8 mol / L, stripping level is 8 levels, and the obtained stripping liquid is a pure nickel sulfate solution;

[0052] 5) stirring the obtained pure nickel sulfate solution with a magnetic bar having a surface magnetic field of 14,000 Gauss to demagnetize it for 30 minutes;

[0053] 6) The nickel sulfate solution obtained after demagnetization is evaporated by a rotary evaporator for 2.5 hours and then crystallized for 5.5 hours to obtain qualified battery-grade nickel sulfate.

[0054] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the essence of the technical solution of the present invention without departing from the technical solution of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing battery-grade nickel sulfate with a short process and low cost, characterized in that: The method comprises the following steps: 1) placing crude nickel hydroxide in a tank and adding acid to carry out an acid leaching reaction; 2) After the leaching reaction, sulfur dioxide gas is introduced into the tank to carry out a reduction leaching reaction; 3) After the reduction leaching reaction, filter pressing is performed, and the obtained filtrate is subjected to a neutralization and iron removal reaction; 4) After the neutralization and iron removal reaction, filter pressing is performed, and the obtained filtrate is extracted with a P507 extractant to remove impurities, and the obtained liquid is a pure nickel sulfate solution; 5) demagnetizing the obtained pure nickel sulfate solution; 6) The nickel sulfate solution obtained after demagnetization is evaporated and crystallized to obtain qualified battery-grade nickel sulfate.

2. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: The crude nickel hydroxide in step 1) is the intermediate product crude nickel hydroxide produced after laterite nickel ore is treated by conventional high-pressure acid leaching process.

3. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: The acid in step 1) is at least one of sulfuric acid, hydrochloric acid and nitric acid; when the acid is added, the initial acidity is 65-85 g / L.

4. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: During the acid leaching reaction in step 1), the temperature is controlled to be between room temperature and 80° C., and the leaching time is between 0.5 and 2.5 hours.

5. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: During the reduction leaching reaction in step 2), the leaching temperature is room temperature to 80° C., and the leaching time is 1 to 3 hours; the amount of sulfur dioxide gas introduced is 1.05 to 1.15 times the theoretical value.

6. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: Step 3) The specific process of neutralizing and removing iron from the obtained filtrate is as follows: hydrogen peroxide is first added to the obtained filtrate, and then a neutralizing agent is added to control its end point pH value to 4.0-5.5, and the neutralization and iron removal reaction is carried out at a temperature of 70-90° C. for 0.5-2 hours.

7. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 6, characterized in that: The amount of hydrogen peroxide added is 1.1 to 1.5 times the theoretical amount; the neutralizing agent is at least one of calcium carbonate, calcium hydroxide and nickel hydroxide.

8. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: Step 4) In the process of extracting the filtrate with P507 extractant, the ratio of O / A is 2.2-3:1, the volume ratio of sulfonated kerosene to P507 extractant is 2.5-4.5:1; the saponification rate of the organic phase is 55-65%, 25-35% liquid alkali is used for saponification, nickel conversion to soap is 6-8 levels, extraction level is 7-11 levels; washing is 11-14 levels; the stripping acidity is 2-3 mol / L, and the stripping level is 5-9 levels.

9. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: Step 5) During the demagnetization, a magnetic bar with a surface magnetic field of 10,000 to 30,000 Gauss is used for stirring for 25 to 35 minutes.

10. The method for preparing battery-grade nickel sulfate with a short process and low cost according to claim 1, characterized in that: Step 6) The evaporation is carried out using a rotary evaporator, and the evaporation is carried out for 2 to 3 hours and then the crystallization is carried out for 5 to 7 hours.

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