Method for improving quality of nickel-cobalt hydroxide

Abstract

The present invention relates to a method for improving the quality of nickel-cobalt hydroxide. In the present invention, iron and aluminum are removed, then sulfur dioxide and air are directly used to oxidize manganese in iron- and aluminum-removed liquid, to directly convert manganese into manganese oxides such as manganese dioxide; manganese is removed first, so that the costs of continuous addition of a reducing agent are saved; and manganese-removed liquid is treated to be an alkali-converted crystal mush of which the manganese content is reduced, and insoluble non-reactive manganese oxides would not be produced due to excessive alkali, so that the manganese content in nickel-cobalt hydroxide products is reduced, and the quality of the nickel-cobalt hydroxide products is improved.

Description

A method for improving the quality of nickel cobalt hydroxide Technical Field

[0001] The present invention relates to the field of hydrometallurgy, and in particular to a method for improving the quality of nickel cobalt hydroxide. Background Art

[0002] Existing patents and usage processes will bring about problems such as poor quality control of nickel cobalt hydroxide products and high pre-treatment costs when realizing large-scale production of nickel cobalt hydroxide.

[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, then perform a alkali-transfer process, and continuously cycle alkali-transfer and re-crystallization. In large-scale production, the alkali-transfer process can lead to local over-alkali, producing high-valent manganese oxides (such as manganese dioxide and manganese tetraoxide). As a result, the nickel-cobalt hydroxide product produced by alkali-transfer crystal slurry precipitation contains a large amount of high-valent manganese oxides, which seriously affects the dry ore Ni content of the nickel-cobalt hydroxide product. Patent CN114854987B discloses a nickel-cobalt precipitation method for the acid leaching of laterite nickel ore to remove iron and aluminum. The core idea is to add a reducing agent before precipitating nickel and cobalt to keep the solution in a reducing atmosphere, thereby preventing manganese from being oxidized to high-valent insoluble oxides during the alkalinity process. However, in large-scale production, due to the huge amount of liquid in the alkalinity conversion and re-crystallization process, manganese is constantly recycled in the solution, requiring the continuous addition of a large amount of reducing agent, which increases costs (based on a production capacity of 90 tons of nickel metal per day, at least 30,000 ml of nickel solution of 3 g / L is required). 3 ), and when the liquid volume and the reaction container are large, it is easier to locally over-alkali, the effect of the reducing agent is weakened, and the dosage needs to be increased, which further increases the production cost.

[0004] Therefore, it is necessary to develop a nickel-cobalt precipitation method that fundamentally solves the production cost of nickel-cobalt hydroxide and the high manganese content of the product.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the above technical deficiencies, provide a method for improving the quality of nickel cobalt hydroxide, and solve the technical problems of nickel cobalt hydroxide production cost and high manganese content in the prior art.

[0007] To achieve the above 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, thereby obtaining a manganese oxide product and a first liquid after manganese removal; S2, adding a precipitant A to the first liquid after manganese removal to carry out a one-stage nickel-cobalt precipitation reaction, and after dense separation, obtaining an underflow and a first overflow, and dividing the underflow into two parts, 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 is subjected to a two-stage nickel-cobalt precipitation reaction, and the reactants of the second-stage nickel cobalt precipitation are densely separated to obtain a third underflow and a second overflow; S4, the second overflow is first mixed with a precipitant B to carry out a alkali-transfer reaction, and then mixed with the second underflow to obtain an alkali-transfer slurry, and the alkali-transfer slurry returns to step S2 to replace the precipitant A to carry out a one-stage nickel-cobalt precipitation reaction.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] The present invention directly uses sulfur dioxide and air to oxidize manganese in the liquid after iron and aluminum removal, and directly converts the manganese into manganese oxides such as manganese dioxide. Manganese is removed first, saving the cost of continuously adding a reducing agent. The liquid after manganese removal is treated to form an alkali-transforming crystal slurry, which itself contains less manganese and will not produce insoluble and non-reactive manganese oxides due to the problem of excessive alkali. Therefore, the manganese content in the nickel cobalt hydroxide product is reduced, and the quality of the nickel cobalt hydroxide product is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Fig. 1 is a process flow chart of the present invention;

[0011] FIG2 is a process flow chart of the present invention using two steps of manganese removal. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0013] Referring to FIG1 , in order to reduce production costs and simultaneously reduce the manganese content in nickel cobalt hydroxide products, thereby fundamentally solving the problem of high manganese content, the present invention provides a method for improving the quality of nickel cobalt hydroxide, which is applicable to a hydrometallurgical process for preparing nickel cobalt precipitates, and specifically comprises the following steps:

[0014] S1, the liquid after iron and aluminum removal, first undergoes a manganese removal process: SO2 produced by the sulfuric acid plant is mixed with air, and the manganese in the liquid after iron and aluminum removal is oxidized and removed within the pH range of 4-5 to obtain a manganese oxide product and the first manganese-removed liquid.

[0015] S2, adding precipitant A to the first manganese-removed liquid to perform a nickel-cobalt precipitation reaction; performing dense separation on the reactants after the first nickel-cobalt precipitation reaction to obtain an underflow and a first overflow, dividing the underflow into a first underflow and a second underflow, wherein the first underflow is washed and filtered to obtain a nickel-cobalt hydroxide product;

[0016] S3, the first overflow undergoes a second-stage nickel-cobalt precipitation reaction, and 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 stage for cyclic leaching;

[0017] S4, the second bottom flow is used as a seed crystal and goes to the seed crystal tank; the second overflow and the precipitant B are first mixed to perform a mixed alkali-transfer reaction, and then enter the seed crystal tank together with the second bottom flow to obtain an alkali-transfer slurry, and the alkali-transfer slurry returns to the first-stage nickel-cobalt precipitation reaction tank for a first-stage nickel-cobalt precipitation reaction.

[0018] The iron-deoxidized aluminum solution in step S1 is an iron-deoxidized aluminum solution obtained by acid leaching of laterite nickel ore, which mainly contains 2.5-6 g / L nickel, 0.1-0.5 g / L cobalt, 1-4 g / L manganese, and 3-15 g / L magnesium.

[0019] Preferably, in step S1, the pH value is adjusted to 4-5 by sodium hydroxide.

[0020] Preferably, the volume ratio of the mixture of SO2 and air in step S1 is 1:(20-100), preferably 1:(20-50).

[0021] Preferably, the manganese removal rate in step S1 is controlled to be 10-50%, more preferably 30-40%, to avoid excessive manganese removal and loss of nickel and cobalt.

[0022] Preferably, in step S2, the precipitant A is added only when the nickel-cobalt precipitation reaction is first performed; the total molar amount of nickel and cobalt in the first manganese removal solution is equal to the total molar amount of OH in the precipitant A. - The molar ratio of is 1:(1.4-2.4), preferably 1:(1.8-2).

[0023] Preferably, the separation ratio of the first underflow to the second underflow in step S2 is 1:(1-10), more preferably 1:(2-10), and most preferably 1:(6-8).

[0024] Preferably, the second-stage nickel-cobalt precipitation reaction in step S3 specifically includes: adding lime milk to the first overflow to adjust the pH to 7.8-8.

[0025] Preferably, in step S4, the Mg in the second overflow is controlled 2+ The ratio of the molar amount of nickel and cobalt to the total molar amount of nickel and cobalt in the first manganese-removed liquid is: (0.6-1.2):1, and more preferably 0.8-0.9:1.

[0026] Preferably, in step S4, the precipitant B is sodium hydroxide, and the total molar amount of nickel and cobalt in the first manganese-removed liquid (the first stage of nickel and cobalt precipitation feed) is equal to the molar amount of OH in the precipitant B. - The molar ratio of is 1:(1.4 to 2.2), and more preferably 1:(1.6 to 1.8).

[0027] Referring to FIG. 2 , as 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 mixed with precipitant B in place of the second overflow to perform a alkali-transfer reaction. The manganese content in the second manganese-removed liquid is further reduced relative to the second overflow, and substantially all manganese is removed.

[0028] The main mechanism of action of the present invention:

[0029] The present 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;

[0030] Mn 2+ +SO2+O2+2H2O→MnO2+SO4 2- +4H +

[0031] In the first reaction, a two-stage nickel-cobalt precipitation reaction is carried out by adding precipitant A, which provides OH - , generating nickel cobalt hydroxide;

[0032] The second overflow in step S4 (obtained from the second-stage nickel-cobalt precipitation reaction) and the precipitant B (strong base such as NaOH) are used for alkali conversion. The alkali formed at this time is mainly magnesium hydroxide, which is a process from a strong base to a weak base:

[0033] 2NaOH+Mg 2+ →Mg(OH)2+2Na +

[0034] Part of the underflow obtained from the first-stage nickel-cobalt precipitation reaction is then used as a seed crystal and mixed with the reactants after the alkali transfer reaction to obtain the alkali transfer crystal slurry after manganese removal, and then returned to the first-stage nickel-cobalt precipitation reaction: on the one hand, the alkali transfer crystal slurry itself has less manganese and will not produce insoluble and non-reactive manganese oxides due to the problem of over-alkali, thereby reducing the manganese content in the nickel-cobalt hydroxide product; on the other hand, magnesium hydroxide acts as a precipitant in the first-stage nickel-cobalt precipitation. At the same time, magnesium hydroxide is a weak base, which effectively avoids the local over-alkali phenomenon that is easily caused by the traditional direct use of strong base as a precipitant.

[0035] The present invention also has the following advantages:

[0036] 1. Add manganese to open the circuit before the first stage of nickel and cobalt precipitation to save the cost of continuous adding reducing agent;

[0037] 2. After the second stage of nickel and cobalt precipitation, the overflow liquid is alkali-converted, that is, the manganese-removed liquid is used for alkali-converting, which can eliminate the insoluble manganese oxides caused by local over-alkali and further reduce the manganese content of the nickel and cobalt hydroxide product;

[0038] 3. Manganese open circuit increases some manganese products to offset or reduce the cost of open circuit processing;

[0039] 4. By using alkali transfer, the actual nickel and cobalt precipitation agent is the weak base magnesium hydroxide, and by controlling the amount of returned crystal seeds, the particle size distribution range of nickel and cobalt hydroxide particles can be effectively reduced, the filtering and washing performance of nickel and cobalt hydroxide can be increased, and the water content of the nickel and cobalt hydroxide product can be reduced.

[0040] The method of the invention realizes the preparation of high-quality nickel-cobalt precipitates by optimizing precipitation conditions and controlling precipitation process.

[0041] The present invention is further described in detail below through specific examples.

[0042] To avoid redundancy, the following iron and aluminum removal liquids all use 3.5g / L nickel, 0.33g / L cobalt, 2.75g / L manganese, and 5.67g / L magnesium.

[0043] Example 1

[0044] The present invention provides a method for improving the quality of nickel cobalt hydroxide, comprising the following steps:

[0045] S1, the de-ironing and de-aluminizing liquid, first undergoes a manganese removal process: SO2 produced by a sulfuric acid plant is mixed with air in a volume ratio of 1:30, and the de-ironing and de-aluminizing liquid is introduced into the liquid at a pH value within the range of 4-5. The reaction time is controlled to oxidize and remove about 40% of the manganese in the de-ironing and de-aluminizing liquid to obtain a manganese oxide product and a first de-ironing and de-manganizing liquid.

[0046] S2, the first manganese-removed liquid is subjected to a nickel-cobalt precipitation reaction, and sodium hydroxide is added during the first reaction. The total molar amount of nickel and cobalt in the first manganese-removed liquid is 1. - The molar ratio of the first underflow and the second underflow is 1:1.8; the reactants after the first nickel-cobalt precipitation reaction are concentrated and separated to obtain an underflow and a first overflow, and the underflow is divided into a first underflow and a second underflow. The separation ratio of the first underflow and the second underflow is 1:6, and the first underflow is washed and filtered to obtain a nickel-cobalt hydroxide product;

[0047] S3, lime milk 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 densely separated to obtain a third underflow and a second overflow; the third underflow enters the neutralization stage for cyclic leaching to recover the residual nickel and cobalt in the slag phase; the second overflow is used to remove residual manganese to obtain a second manganese-removed liquid;

[0048] S4, the second manganese-removed liquid is mixed with sodium hydroxide to perform a mixed alkali reaction. Here, the ratio of the amount of sodium hydroxide to the total molar amount of nickel and cobalt in the first manganese-removed liquid is 1.8:1, and the Mg content in the second manganese-removed liquid is controlled. 2+ The ratio of the molar amount of nickel and cobalt in the first manganese removal liquid to the total molar amount of nickel and cobalt is 0.8:1; and then added to the seed tank together with the second bottom flow to obtain the alkali-transformed slurry, and the alkali-transformed slurry is returned to the first nickel-cobalt precipitation reaction tank for a first nickel-cobalt precipitation reaction.

[0049] Example 2

[0050] 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 those in Example 1. The specific ratios and test results are shown in Table 1 below.

[0051] Example 3

[0052] 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 those in Example 1. The specific ratios and test results are shown in Table 1 below.

[0053] Example 4

[0054] 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 those in Example 1. The specific ratios and test results are shown in Table 1 below.

[0055] Example 5

[0056] 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 those in Example 1. The specific ratios and test results are shown in Table 1 below.

[0057] Table 1 Separation ratios and test results of different first underflows and second underflows

[0058] As can be seen from Table 1, the separation ratio of the first underflow and the second underflow can regulate the particle size distribution range of the nickel cobalt hydroxide particles. In the present invention, the preferred separation ratio of the first underflow and the second underflow is 1: (2 to 10), and the most preferred ratio is 1: (6 to 8).

[0059] Example 6

[0060] 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 those in Example 1. The specific ratios and test results are shown in Table 2 below.

[0061] Example 7

[0062] 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 those in Example 1. The specific ratios and test results are shown in Table 2 below.

[0063] Table 2 Different manganese removal rates and product test results

[0064] As shown in Table 2, the Mn content in the nickel cobalt hydroxide product can be regulated by adjusting different manganese removal rates. The preferred manganese removal rate of the present invention is 40%.

[0065] Comparative Example 1

[0066] The only difference from Example 1 is that the manganese removal process in step S1 is removed, and the other steps and conditions are the same as those in Example 1.

[0067] 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%.

[0068] Comparative Example 2

[0069] The only difference from Example 1 is that the manganese removal rate in step S1 is controlled at 50%, and the other steps and conditions are the same as those in Example 1.

[0070] The results show that an excessively high manganese removal rate results in increased nickel and cobalt losses, and therefore, in the present invention, the manganese removal rate is preferably controlled at 30-40%.

[0071] Compared with the prior art, the present invention directly uses sulfur dioxide and air to oxidize manganese after removing iron and aluminum, and directly converts it into manganese oxides such as manganese dioxide. Manganese is removed first, saving the cost of continuously adding a reducing agent; the alkali-transformed slurry after manganese removal contains less manganese itself, and will not produce insoluble and non-reactive manganese oxides due to the problem of excessive alkali, thereby reducing the manganese content in the nickel cobalt hydroxide product and improving the quality of the nickel cobalt hydroxide product.

[0072] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the quality of nickel cobalt hydroxide, characterized in that: The following steps are involved: S1, the iron-dealuminum-removed liquid is treated with a mixture of SO2 and air to remove manganese, thereby obtaining a manganese oxide product and a first manganese-dealuminum-removed liquid; the iron-dealuminum-removed liquid mainly includes nickel, cobalt, manganese and magnesium; S2, adding a precipitant A to the first manganese-removed liquid to carry out a nickel-cobalt precipitation reaction, and obtaining an underflow and a first overflow through dense separation, and dividing the underflow 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 is subjected to a second-stage nickel-cobalt precipitation reaction, and the reactants of the second-stage nickel-cobalt precipitation are subjected to dense separation to obtain a third underflow and a second overflow; S4, the second overflow is first mixed with the precipitant B to perform a alkali conversion reaction, and then mixed with the second underflow to obtain a alkali conversion slurry, and the alkali conversion slurry is returned to step S2 to replace the precipitant A to perform 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 iron-aluminum-removed liquid is an iron-aluminum-removed solution of laterite nickel ore acid leaching.

3. The method for improving the quality of nickel cobalt hydroxide according to claim 1, characterized in that: In step S1, the pH value of the liquid after iron and aluminum removal is adjusted to 4-5 by sodium hydroxide and then manganese removal is performed.

4. 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).

5. The method for improving the quality of nickel cobalt hydroxide according to any one of claims 1 to 4, characterized in that: In step S1, the liquid after iron and aluminum removal is passed through a mixture of SO2 and air to remove 10-50% of manganese.

6. 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 liquid is equal to the molar amount of OH in the precipitant A. - The molar ratio is 1:(1.4~2.4).

7. The method for improving the quality of nickel cobalt hydroxide according to claim 1 or 6, characterized in that: In step S2, the separation ratio of the first underflow and the second underflow is 1:(1-10).

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

9. The method for improving the quality of nickel cobalt hydroxide according to claim 1 or 8, characterized in that: In step S3, the third bottom flow enters the neutralization section for cyclic leaching.

10. 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 liquid is equal to the molar amount of OH in the precipitant B. - The molar ratio is 1:(1.4~2.2).

11. The method for improving the quality of nickel cobalt hydroxide according to claim 10, characterized in that: The total molar amount of nickel and cobalt in the first manganese removal solution and the OH content in the precipitant B - The molar ratio is 1:(1.6~1.8).

12. The method for improving the quality of nickel cobalt hydroxide according to claim 10, characterized in that: In step S4, the second overflow is subjected to a manganese removal process to obtain a manganese oxide product and a second manganese-removed liquid, and the second manganese-removed liquid is mixed with a precipitant B to perform a alkali conversion reaction.

13. The method for improving the quality of nickel cobalt hydroxide according to claim 1, characterized in that: The liquid after iron and aluminum removal includes 2.5-6 g / L nickel, 0.1-0.5 g / L cobalt, 1-4 g / L manganese and 3-15 g / L magnesium.

14. The method for improving the quality of nickel cobalt hydroxide according to claim 1 or 13, characterized in that: Control the Mg in the second overflow 2+ The ratio of the molar amount of nickel and cobalt in the first manganese-removed liquid is (0.6-1.2):1.

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