A method for improving the mass of nickel-cobalt hydroxide

Abstract

The present application relates to a kind of nickel cobalt hydroxide mass promotion method, the present application directly uses sulfur dioxide and air oxidation after removing iron aluminum, manganese in the liquid after removing iron aluminum, directly convert into manganese dioxide and other manganese oxides, remove manganese first, save the cost of continuous reducing agent;After removing manganese, the liquid is treated to form conversion alkali crystal slurry, itself contains little manganese, and the insoluble and non-reactive manganese oxide caused by excessive alkali problem will not be brought, so that the manganese content in nickel cobalt hydroxide product is reduced, and the quality of nickel cobalt hydroxide product is improved.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgy, specifically to a method for improving the quality of nickel-cobalt hydroxide. Background Technology

[0002] Existing patents and processes, when used to achieve large-scale production of nickel-cobalt hydroxide, can lead to problems such as poor product quality control and high pretreatment costs.

[0003] For example, patent CN104140130B discloses a nickel-cobalt hydroxide product and its preparation method. The core idea is to use sodium hydroxide as a precipitant to precipitate nickel-cobalt hydroxide, followed by a conversion process, with continuous conversion and crystal reversion in a cycle. During large-scale production, the conversion process can lead to localized over-alkali formation, producing high-valence manganese oxides (such as manganese dioxide and manganese tetroxide). Consequently, the nickel-cobalt hydroxide product produced using the conversion slurry precipitation contains a significant amount of high-valence manganese oxides, severely affecting the dry Ni content of the nickel-cobalt hydroxide product. Patent CN114854987B discloses a method for nickel-cobalt precipitation in laterite nickel ore acid leaching solution for removing iron and aluminum. The core idea is to add a reducing agent before nickel-cobalt precipitation to maintain a reducing atmosphere in the solution, preventing manganese from being oxidized into high-valence insoluble oxides during the over-alkali process. However, in large-scale production, due to the huge volume of liquid during the alkali conversion and re-crystallization processes, manganese is continuously recycled in the solution, requiring a continuous addition of large amounts of reducing agent, increasing costs (based on a production capacity of 90 metric tons of nickel per day, at least 30,000 cubic meters of 3 g / L nickel solution are needed). 3 Furthermore, when the liquid volume and reaction vessel are large, local over-alkaliness is more likely to occur, weakening the effect of the reducing agent and requiring a larger dosage, which further increases production costs.

[0004] Therefore, there is a need to develop a method to fundamentally solve the problems of high production costs of nickel-cobalt hydroxide and high manganese content in the immersion nickel-cobalt process. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a method for improving the quality of nickel-cobalt hydroxide, thereby solving the technical problems of high production cost and high manganese content in nickel-cobalt hydroxide products in the prior art.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a technical solution for improving the quality of nickel-cobalt hydroxide, comprising the following steps: S1, the liquid after iron and aluminum removal is treated with a mixture of SO2 and air to remove manganese, obtaining a manganese oxide product and a first manganese-removed liquid; S2, precipitant A is added to the first manganese-removed liquid to carry out a first-stage nickel-cobalt precipitation reaction, and after concentration separation, an underflow and a first overflow are obtained. The underflow is divided into a first underflow and a second underflow, wherein the first underflow is washed and filtered to obtain a nickel-cobalt hydroxide product; S3, the first overflow undergoes a second-stage nickel-cobalt precipitation reaction, and the reactants of the second-stage nickel-cobalt precipitation reaction are concentrated to obtain a third underflow and a second overflow; S4, the second overflow is first mixed with precipitant B to carry out an alkali conversion reaction, and then mixed with the second underflow to obtain an alkali conversion slurry. The alkali conversion slurry is returned to step S2 to replace precipitant A for a first-stage nickel-cobalt precipitation reaction.

[0007] Compared with the prior art, the beneficial effects of the present invention include:

[0008] This invention directly uses sulfur dioxide and air oxidation to oxidize the manganese in the liquid after iron and aluminum removal, converting it directly into manganese oxides such as manganese dioxide. This first removal of manganese eliminates the cost of continuously adding reducing agents. After treatment, the liquid after manganese removal forms a alkali-converting slurry, which itself contains less manganese. This avoids the problem of insoluble and non-reactive manganese oxides caused by excessive alkali, thereby reducing the manganese content in nickel-cobalt hydroxide products and improving their quality. Attached Figure Description

[0009] Figure 1 This is a process flow diagram of the present invention;

[0010] Figure 2 This is a process flow diagram of the two-stage manganese removal process used in this invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0012] See Figure 1 To reduce production costs and simultaneously decrease the manganese content in nickel-cobalt hydroxide products, fundamentally addressing the high manganese content issue, this invention provides a method for improving the quality of nickel-cobalt hydroxide. This method is applicable to hydrometallurgical processes for preparing nickel-cobalt precipitates and specifically includes the following steps:

[0013] S1, the liquid after iron and aluminum removal, first undergoes a manganese removal process: SO2 produced by a sulfuric acid plant is mixed with air, and the manganese in the liquid after iron and aluminum removal is oxidized and removed within a pH range of 4-5, resulting in manganese oxide products and the first liquid after manganese removal.

[0014] S2, after the first manganese removal, precipitant A is added to the liquid to carry out a nickel-cobalt precipitation reaction; the reactants after the first nickel-cobalt precipitation reaction are concentrated and separated to obtain the underflow and the first overflow. The underflow is divided into two parts: the first underflow and the second underflow. The first underflow is washed and filtered to obtain the nickel-cobalt hydroxide product.

[0015] S3, the first overflow undergoes a two-stage nickel-cobalt precipitation reaction, the reactants from the two-stage nickel-cobalt precipitation reaction are concentrated and separated to obtain a third underflow and a second overflow; the third underflow enters the neutralization section for circulating leaching.

[0016] S4, the second underflow is used as a seed crystal and goes to the seed crystal tank; the second overflow and precipitant B are mixed first to carry out a mixed alkali conversion reaction, and then enter the seed crystal tank together with the second underflow to obtain alkali conversion slurry. The alkali conversion slurry is returned to a first-stage nickel-cobalt immersion reaction tank for a first-stage nickel-cobalt immersion reaction.

[0017] In step S1, the solution after removing iron and aluminum is an acid leaching solution for removing iron and aluminum from laterite nickel ore, which mainly contains nickel 2.5-6 g / L, cobalt 0.1-0.5 g / L, manganese 1-4 g / L, magnesium 3-15 g / L and other components.

[0018] Preferably, in step S1, the pH value is adjusted to 4-5 using sodium hydroxide.

[0019] Preferably, the volume ratio of SO2 to air in step S1 is 1:(20-100), more preferably 1:(20-50).

[0020] Preferably, the removal rate of manganese in step S1 is controlled at 10-50%, more preferably 30-40%, to avoid excessive removal of manganese while losing a large amount of nickel and cobalt.

[0021] Preferably, in step S2, precipitant A is added only during the first stage of the nickel-cobalt precipitation reaction; the total molar amount of nickel and cobalt in the solution after the first manganese removal is equal to the amount of OH in precipitant A. - The molar ratio is 1:(1.4 to 2.4), preferably 1:(1.8 to 2).

[0022] Preferably, the separation ratio of the first underflow and the second underflow in step S2 is 1:(1~10), further preferably 1:(2~10); and most preferably 1:(6~8).

[0023] Preferably, the two-stage nickel-cobalt precipitation reaction in step S3 specifically includes: adding lime slurry to the first overflow to adjust the pH to 7.8-8.

[0024] Preferably, in step S4, the Mg in the second overflow is controlled. 2+ The ratio of the molar amount of nickel to the total molar amount of nickel and cobalt in the first manganese removal solution is (0.6 to 1.2):1, and more preferably 0.8 to 0.9:1.

[0025] Preferably, in step S4, the precipitant B is sodium hydroxide, and the total molar amount of nickel and cobalt in the first manganese removal solution (the first stage of nickel-cobalt precipitation feed) is related to the amount of OH in the precipitant B. - The molar ratio is 1:(1.4 to 2.2), and more preferably 1:(1.6 to 1.8).

[0026] See Figure 2 In a preferred embodiment, in step S4, the second overflow undergoes a manganese removal process to obtain a manganese oxide product and a second manganese-removed liquid. The second manganese-removed liquid is then used to replace the second overflow and mixed with precipitant B for an alkali conversion reaction. The manganese in the second manganese-removed liquid is further reduced compared to the second overflow, essentially removing all manganese.

[0027] Main mechanism of action of this invention:

[0028] This invention first uses a mixture of SO2 and air to oxidize the manganese in the liquid after iron and aluminum removal into manganese oxides such as manganese dioxide, thereby removing manganese;

[0029] Mn 2+ +SO₂ + O₂ + 2H₂O → MnO₂ + SO₄²⁻ 2- +4H +

[0030] In the initial reaction, a two-stage nickel-cobalt precipitation reaction is carried out by adding precipitant A, which provides OH-. - Nickel-cobalt hydroxide is produced;

[0031] The conversion to alkali occurs through the second overflow (obtained from the two-stage nickel-cobalt precipitation reaction) in step S4 and the precipitant B (strong alkali such as NaOH). The alkali formed at this time is mainly magnesium hydroxide, which is a process of converting a strong alkali to a weak alkali.

[0032] 2NaOH + Mg 2+ →Mg(OH)₂ + 2Na +

[0033] The underflow obtained from the first stage of nickel-cobalt immersion reaction is then used as a seed crystal and mixed with the reactants after the alkali conversion reaction to obtain a alkali-converted slurry after manganese removal. This slurry is then returned to the first stage of nickel-cobalt immersion reaction. On the one hand, the alkali-converted slurry itself has less manganese, so it will not produce insoluble and non-reactive manganese oxides due to excessive alkali, thus reducing the manganese content in the nickel-cobalt hydroxide product. On the other hand, magnesium hydroxide acts as a precipitant in the first stage of nickel-cobalt immersion reaction. At the same time, magnesium hydroxide is a weak alkali, which effectively avoids the local over-alkali phenomenon that is easily caused by the traditional direct use of strong alkali as a precipitant.

[0034] The present invention also has the following advantages:

[0035] 1. Adding manganese to the first stage of nickel-cobalt plating eliminates the cost of continuously adding reducing agent;

[0036] 2. The overflow liquid after the second stage of nickel-cobalt precipitation is converted to alkali, that is, the liquid after manganese removal is converted to alkali. This can eliminate insoluble manganese oxides caused by local over-alkali and further reduce the manganese content of nickel-cobalt hydroxide products.

[0037] 3. Opening the manganese circuit increases the production of some manganese products, offsetting or reducing the cost of the open circuit treatment;

[0038] 4. By utilizing alkali conversion, the actual precipitant for nickel-cobalt is weak alkali magnesium hydroxide. By controlling the amount of seed crystals, the particle size distribution range of nickel-cobalt hydroxide can be effectively reduced, the filtration and washing performance of nickel-cobalt hydroxide can be increased, and the moisture content of nickel-cobalt hydroxide products can be reduced.

[0039] The method of this invention achieves the preparation of high-quality nickel-cobalt precipitates by optimizing precipitation conditions and controlling the precipitation process.

[0040] The present invention will be further described in detail below through specific embodiments.

[0041] To avoid redundancy, the following liquids, excluding iron and aluminum, all use nickel 3.5g / L, cobalt 0.33g / L, manganese 2.75g / L, and magnesium 5.67g / L.

[0042] Example 1

[0043] This invention discloses a method for improving the quality of nickel-cobalt hydroxide, comprising the following steps:

[0044] S1, the liquid after iron and aluminum removal, first undergoes a manganese removal process: SO2 produced by a sulfuric acid plant is mixed with air at a volume ratio of 1:30, and the liquid after iron and aluminum removal is introduced into the solution within a pH range of 4-5. The reaction time is controlled to oxidize and remove about 40% of the manganese in the liquid after iron and aluminum removal, resulting in manganese oxide product and the first manganese removal liquid.

[0045] S2, the solution after the first manganese removal undergoes a further nickel-cobalt precipitation reaction. Sodium hydroxide is added during the first reaction. The total molar amount of nickel and cobalt in the solution after the first manganese removal is related to the amount of OH. - The molar ratio of the two is 1:1.8; the reactants after the nickel-cobalt precipitate reaction are concentrated and separated to obtain the underflow and the first overflow. The underflow is divided into two parts: the first underflow and the second underflow. The separation ratio of the first underflow and the second underflow is 1:6. The first underflow is washed and filtered to obtain the nickel-cobalt hydroxide product.

[0046] S3, lime slurry is added to the first overflow to adjust the pH to 7.8-8, and a second-stage nickel-cobalt precipitation reaction is carried out. The reactants of the second-stage nickel-cobalt precipitation are concentrated and separated to obtain a third underflow and a second overflow. The third underflow enters the neutralization section for circulating leaching to recover the residual nickel and cobalt in the slag phase. The second overflow is then used to remove residual manganese to obtain a second manganese-removed liquid.

[0047] S4, the second manganese-removed solution is first mixed with sodium hydroxide to carry out a mixed-alkali conversion reaction. Here, the ratio of the amount of sodium hydroxide to the total molar amount of nickel and cobalt in the first manganese-removed solution is 1.8:1. The Mg content in the second manganese-removed solution is controlled. 2+ The ratio of the molar amount of nickel to the total molar amount of nickel and cobalt in the first manganese-removed liquid is 0.8:1; then it is added together with the second underflow into the seed tank to obtain the alkali-converted crystal slurry, which is returned to the first nickel-cobalt precipitation reaction tank for a first nickel-cobalt precipitation reaction.

[0048] Example 2

[0049] The only difference from Example 1 is that the separation ratio of the first underflow and the second underflow is adjusted to 1:4. The other steps and conditions are the same as in Example 1. The specific ratios and test results are shown in Table 1 below.

[0050] Example 3

[0051] The only difference from Example 1 is that the separation ratio of the first underflow and the second underflow is adjusted to 1:8. The other steps and conditions are the same as in Example 1. The specific ratios and test results are shown in Table 1 below.

[0052] Example 4

[0053] The only difference from Example 1 is that the separation ratio of the first underflow and the second underflow is adjusted to 1:10. The other steps and conditions are the same as in Example 1. The specific ratio and test results are shown in Table 1 below.

[0054] Example 5

[0055] The only difference from Example 1 is that the separation ratio of the first underflow and the second underflow is adjusted to 1:2. The other steps and conditions are the same as in Example 1. The specific ratio and test results are shown in Table 1 below.

[0056] Table 1. Separation ratios and test results of different first and second bottom currents.

[0057]

[0058]

[0059] As shown in Table 1, the separation ratio of the first underflow and the second underflow can control the particle size distribution range of nickel-cobalt hydroxide particles. The preferred separation ratio of the first underflow and the second underflow in this invention is 1:(2-10), and the most preferred ratio is 1:(6-8).

[0060] Example 6

[0061] The only difference from Example 1 is that the manganese removal rate of the first manganese removal is adjusted to 20%. The other steps and conditions are the same as in Example 1. The specific proportions and test results are shown in Table 2 below.

[0062] Example 7

[0063] The only difference from Example 1 is that the manganese removal rate of the first manganese removal is adjusted to 30%. The other steps and conditions are the same as in Example 1. The specific proportions and test results are shown in Table 2 below.

[0064] Table 2. Results of different manganese removal rates and product testing.

[0065]

[0066] As shown in Table 2, the content of Mn in nickel-cobalt hydroxide products can be controlled by adjusting different manganese removal rates. The preferred manganese removal rate in this invention is 40%.

[0067] Comparative Example 1

[0068] The only difference from Example 1 is that the manganese removal step S1 is omitted, while the other steps and conditions are the same as in Example 1.

[0069] The results showed that the dry basis Ni content of the nickel-cobalt hydroxide product was 38.42%, the Mn content was 8.63%, and the moisture content was 54.32%.

[0070] Comparative Example 2

[0071] The only difference from Example 1 is that the removal rate of manganese in step S1 is controlled at 50%, while the other steps and conditions are the same as in Example 1.

[0072] The results showed that if the manganese removal rate was too high, the loss of nickel and cobalt would increase. Therefore, in this invention, it is preferable to control the manganese removal rate at 30-40%.

[0073] Compared with existing technologies, this invention directly uses sulfur dioxide and air-oxidized manganese after removing iron and aluminum, directly converting them into manganese oxides such as manganese dioxide. This first removes manganese, saving the cost of continuously adding reducing agents. The alkali crystal slurry after manganese removal itself has a low manganese content, and will not produce insoluble and non-reactive manganese oxides due to excessive alkali. This reduces the manganese content in nickel-cobalt hydroxide products and improves the quality of nickel-cobalt hydroxide products.

[0074] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the quality of nickel-cobalt hydroxide, characterized in that, Includes the following steps: S1, the iron and aluminum removal solution is treated with a mixture of SO2 and air to remove 30-40% of the manganese, yielding a manganese oxide product and a first manganese removal solution; the iron and aluminum removal solution mainly includes nickel, cobalt, manganese and magnesium; the iron and aluminum removal solution is an acid leaching solution for removing iron and aluminum from laterite nickel ore, mainly containing 2.5-6 g / L nickel, 0.1-0.5 g / L cobalt, 1-4 g / L manganese and 3-15 g / L magnesium; S2, precipitant A is added to the first manganese-removed liquid to carry out a nickel-cobalt precipitation reaction. After concentration separation, underflow and first overflow are obtained. The underflow is divided into two parts: first underflow and second underflow. The first underflow is washed and filtered to obtain nickel-cobalt hydroxide product. The separation ratio of the first underflow and the second underflow is 1:(6-8). S3, the first overflow undergoes a two-stage nickel-cobalt precipitation reaction, and the reactants from the two-stage nickel-cobalt precipitation reaction are concentrated and separated to obtain a third underflow and a second overflow; S4, the second overflow is first mixed with precipitant B to carry out the alkali conversion reaction, and then mixed with the second underflow to obtain alkali conversion slurry. The alkali conversion slurry is returned to step S2 to replace precipitant A for a nickel-cobalt precipitation reaction.

2. The method for improving the quality of nickel-cobalt hydroxide according to claim 1, characterized in that, In step S1, the pH of the solution after removing iron and aluminum is adjusted to 4-5 using sodium hydroxide before manganese removal.

3. The method for improving the quality of nickel-cobalt hydroxide according to claim 1, characterized in that, In step S1, the mixing ratio of SO2 to air is 1:(20-100).

4. The method for improving the quality of nickel-cobalt hydroxide according to claim 1, characterized in that, In step S2, the precipitant A is sodium hydroxide; the total molar amount of nickel and cobalt in the first manganese-removed solution is related to the amount of OH in the precipitant A. - The molar ratio is 1:(1.4~2.4).

5. The method for improving the quality of nickel-cobalt hydroxide according to claim 1, characterized in that, In step S3, the two-stage nickel-cobalt precipitation reaction specifically includes: adding lime slurry to the first overflow to adjust the pH to 7.8-8.

6. The method for improving the quality of nickel-cobalt hydroxide according to claim 1 or 5, characterized in that, In step S3, the third underflow enters the neutralization section for leaching.

7. The method for improving the quality of nickel-cobalt hydroxide according to claim 1, characterized in that, In step S4, the precipitant B is sodium hydroxide; the total molar amount of nickel and cobalt in the first manganese-removed solution is related to the amount of OH in the precipitant B. - The molar ratio is 1:(1.4~2.2).

8. The method for improving the quality of nickel-cobalt hydroxide according to claim 7, characterized in that, The total molar amount of nickel and cobalt in the first manganese-removed solution and the OH content in precipitant B - The molar ratio is 1:(1.6 to 1.8).

9. The method for improving the quality of nickel-cobalt hydroxide according to claim 7, characterized in that, In step S4, the second overflow undergoes a manganese removal process to obtain a manganese oxide product and a second manganese-removed liquid. The second manganese-removed liquid is then mixed with precipitant B to undergo an alkali conversion reaction.

10. The method for improving the quality of nickel-cobalt hydroxide according to claim 1, characterized in that, Controlling Mg in the second overflow 2+ The ratio of the molar amount of nickel to cobalt in the first manganese-removed liquid is (0.6-1.2):1.

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