Method for reducing water content of MHP product of laterite-nickel ore and increasing manganese content thereof

Abstract

Disclosed in the present invention is a method for reducing the water content of an MHP product of laterite-nickel ore and increasing the manganese content thereof. The method comprises the following steps: (1) using concentrated sulfuric acid to adjust the pH of a solution obtained after two-stage neutralization for iron-aluminum removal to 2-4.5; (2) adding hydrogen peroxide to the system of step (1) for reaction, upon completion of the reaction, adding an alkali to adjust the pH of the system to 6.5-7.5, and performing primary nickel-cobalt precipitation, so as to obtain a primary nickel-cobalt precipitate solution; and (3) settling in a thickener the primary nickel-cobalt precipitate solution of step (2), and performing pressure filtration on a bottom flow obtained after the thickening, so as to obtain an MHP product. By means of jointly controlling the pH of the solution obtained after two-stage neutralization for iron-aluminum removal and the amount of hydrogen peroxide, the present invention can obviously increase the manganese content in MHP; additionally, the method will not additionally introduce other impurities and can obviously reduce the water content of the MHP product, thus reducing the volume and freight charges, and solving the industrial technical problem of high water contents of MHP.

Description

A method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content Technical Field

[0001] The invention belongs to the field of metallurgy, and in particular relates to a method for reducing the moisture content of a laterite nickel ore MHP product and increasing its manganese content. Background Art

[0002] In the context of the dual-carbon era, the rapid development of new energy vehicles has driven the development of NCM batteries. Consequently, laterite nickel ore has become a key nickel resource for development in various countries. Limonite, the primary target of hydrometallurgy, undergoes high-pressure leaching and secondary neutralization to remove iron and aluminum. A precipitation process then extracts and enriches the intermediate nickel-cobalt product, MHP. Following acid dissolution of MHP, battery-grade nickel-cobalt-manganese salt crystals are obtained through an extraction process. The nickel-cobalt precipitation step, which produces the MHP product grade, directly determines the manganese recovery rate from laterite nickel ore. The manganese precipitation rate in this step is generally only around 10%. The remaining manganese is precipitated with lime milk and disposed of as waste slag in landfills.

[0003] Manganese carbonate and rhodochrosite are two common types of manganese ore resources, primarily used in the production of electrolytic manganese. However, global manganese ore resources are unevenly distributed, with limited reserves and complex deposit composition. Exploration and development still face challenges, such as high mining costs and low utilization rates. Therefore, the question of how to fully recover manganese from laterite nickel ore is a non-negligible issue. Furthermore, the current MHP product derived from laterite nickel ore has a high moisture content, posing a technical challenge in reducing the volume and transportation costs of MHP.

[0004] Summary of the Invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content.

[0006] This invention proposes to further effectively increase the manganese content and manganese recovery rate in the laterite nickel ore MHP product by adjusting the pH of the solution after the second-stage neutralization and de-ironization and aluminum removal, as well as the amount of hydrogen peroxide added, before the first-stage alkaline precipitation of nickel and cobalt. The manganese content in the MHP can be regulated by controlling the pH of the solution after the second-stage neutralization and de-ironization and aluminum removal, as well as the amount of hydrogen peroxide used. Notably, this method does not introduce additional impurities and significantly reduces the moisture content of the MHP product, reducing volume and shipping costs, thus resolving the industry's technical challenge of high moisture content in MHP.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for reducing the moisture content of a laterite nickel ore MHP product and increasing its manganese content comprises the following steps:

[0009] (1) Use concentrated sulfuric acid to adjust the pH of the second-stage neutralization solution after iron and aluminum removal to 2-4.5;

[0010] (2) adding hydrogen peroxide to the system of step (1) to carry out a reaction, adding alkali after the reaction is completed, adjusting the pH of the system to 6.5-7.5, and performing a nickel-cobalt precipitation to obtain a nickel-cobalt precipitation solution;

[0011] (3) The nickel-cobalt precipitation solution in step (2) is settled in a thickener, and the bottom flow after concentration is filtered to obtain the MHP product.

[0012] Preferably, the concentration of the concentrated sulfuric acid in step (1) is 98%.

[0013] Preferably, the volume ratio of the hydrogen peroxide in step (2) to the liquid after the second-stage neutralization and removal of iron and aluminum is 0.1 to 10:120.

[0014] Preferably, the volume ratio of the hydrogen peroxide in step (2) to the liquid after the second-stage neutralization and removal of iron and aluminum is 1 to 2:120.

[0015] Preferably, the time for reacting with the hydrogen peroxide in step (2) is 1 to 60 minutes.

[0016] Preferably, the concentration of the hydrogen peroxide in step (2) is 5-30%.

[0017] Preferably, the alkali in step (2) is at least one of a liquid alkali solution and lime milk.

[0018] Preferably, the concentrations of the liquid caustic soda solution and lime milk are both 5-32%.

[0019] Preferably, the time for the nickel-cobalt precipitation in step (2) is 0.5 to 3 hours.

[0020] Preferably, the overflow after thickening in the thickener in step (3) is subjected to a two-stage nickel and cobalt precipitation operation as needed.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention further effectively increases the manganese content in the laterite nickel ore MHP product and increases the manganese recovery rate by jointly adjusting the pH of the second-stage neutralization solution after iron and aluminum removal and the amount of hydrogen peroxide added therein.

[0023] (2) The present invention does not introduce any additional impurities, can significantly reduce the moisture content of MHP products, reduce volume and freight, and solve the industry technical problem of high moisture content of MHP. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a flow chart of the method for reducing the moisture content and increasing the manganese content of a laterite nickel ore MHP product according to the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the 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.

[0026] The concentration of the hydrogen peroxide in the embodiment is 30%, the concentration of the concentrated sulfuric acid is 98%, and the concentration of the liquid caustic soda is 15%.

[0027] The composition of the liquid after the second stage neutralization and removal of iron and aluminum is shown in Table 1.

[0028] Table 1 List of components of the liquid after the second stage neutralization and removal of iron and aluminum

[0029] Comparative Example 1

[0030] The pH value of the liquid after the second-stage neutralization and de-ironization and aluminum removal was 4.9. Concentrated sulfuric acid was not added before nickel and cobalt precipitation to keep the liquid after the second-stage de-ironization and aluminum removal unchanged, and hydrogen peroxide was not added. The pH value of the liquid after the second-stage de-ironization and aluminum removal was directly adjusted to 6.8 with a liquid alkali solution. The reaction was carried out for 1 hour, and then the liquid was settled in a thickener. The bottom flow after thickening was filtered to obtain the MHP product. The composition of the obtained MHP product is shown in Table 2.

[0031] Table 2: List of ingredients of the MHP product obtained in Comparative Example 1

[0032] Comparative Example 2

[0033] The pH of the liquid after the second-stage neutralization and de-ironization and aluminum removal was 4.9. The pH of the liquid after the second-stage neutralization and de-ironization and aluminum removal was adjusted to 3 with concentrated sulfuric acid. Without adding hydrogen peroxide, the pH of the liquid after the second-stage de-ironization and aluminum removal was directly adjusted to 6.8 with liquid alkali. The reaction was carried out for 1 hour, and then the liquid was settled in a thickener. The bottom flow after thickening was filtered to obtain the MHP product. The composition of the obtained MHP product is shown in Table 3.

[0034] Table 3: Composition of the MHP product obtained in Comparative Example 2

[0035] Comparing Comparative Examples 1 and 2, it can be seen that when the pH of the liquid after the second stage of iron and aluminum removal is adjusted to 3, the content of the main metal element nickel in the MHP product decreases, the Mn content also decreases, and the water content increases.

[0036] Comparative Example 3

[0037] Without adjusting the pH of the liquid after the second-stage neutralization and de-ironing, hydrogen peroxide was directly added. The volume ratio of hydrogen peroxide to the liquid after the second-stage de-ironing was 1:120. The reaction was carried out for 20 minutes. Then, the pH of the liquid after the second-stage de-ironing was adjusted to 6.8 with liquid alkali. The reaction was continued for 1 hour. The liquid was then settled in a thickener. The bottom flow after thickening was filtered to obtain the MHP product. The composition of the obtained MHP product is shown in Table 4.

[0038] Table 4: Composition of the MHP product obtained in Comparative Example 3

[0039] Combined with Tables 2 and 3, we can see from Table 4 that there is no significant change in the moisture content and Mn content of the MHP product.

[0040] Example 1

[0041] A method for reducing the moisture content of a laterite nickel ore MHP product and increasing its manganese content comprises the following steps:

[0042] On the basis of Comparative Example 2, hydrogen peroxide was added, wherein the volume ratio of hydrogen peroxide to the liquid after the second stage iron and aluminum removal was 1:120, and the reaction was carried out for 20 minutes. Then, the pH of the liquid after the second stage iron and aluminum removal was adjusted to 6.8 with liquid alkali, and the reaction was carried out for 1 hour. Then, the liquid was settled in a thickener, and the bottom flow after thickening was filtered to obtain the MHP product. The composition of the obtained MHP product is shown in Table 5.

[0043] Table 5: Composition of the MHP product obtained in Example 1

[0044] It can be seen from Table 5 that the manganese content in the MHP product increased significantly and the moisture content also decreased.

[0045] Example 2

[0046] In order to further increase the manganese content in MHP and further reduce the water content of MHP, the amount of hydrogen peroxide was increased on the basis of Comparative Example 2, wherein the volume ratio of hydrogen peroxide to the liquid after the second stage iron and aluminum removal was 2:120, and the reaction was carried out for 20 minutes. Then, the pH of the liquid after the second stage iron and aluminum removal was adjusted to 6.8 with liquid caustic soda, and the reaction was carried out for 1 hour. Then, the liquid was settled in a thickener, and the underflow after thickening was filtered to obtain the MHP product. The composition of the obtained MHP product is shown in Table 6.

[0047] Table 6: Composition of the MHP product obtained in Example 2

[0048] From Table 6, we can see that with increasing the amount of hydrogen peroxide added, the manganese content in MHP increased significantly, reaching 11.53%, while the water content decreased to 43.96%.

[0049] Example 3

[0050] Based on Example 2, the pH of the liquid after the second-stage neutralization and removal of iron and aluminum was reduced to 2 using concentrated sulfuric acid, and other process parameters remained unchanged. The components of the obtained MHP are shown in Table 7 below.

[0051] Table 7 Composition of the MHP product obtained in Example 3

[0052] From Table 7 we can see that the manganese content in MHP further increased and the moisture content further decreased.

[0053] 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 claims of the present invention.

Claims

1. A method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content, characterized in that, it comprises the following steps: (1) Adjust the pH of the solution after secondary neutralization for iron and aluminum removal to 2 - 4.5 with concentrated sulfuric acid; (2) Add hydrogen peroxide to react in the system of step (1), and after the reaction ends, add alkali to adjust the pH of the system to 6.5 - 7.5 for primary nickel and cobalt precipitation to obtain a primary nickel and cobalt precipitation solution; (3) The primary nickel and cobalt precipitation solution described in step (2) is settled by a thickener, and the thickened bottom flow is filtered by a filter press to obtain the MHP product.

2. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to claim 1, characterized in that, the volume ratio of the hydrogen peroxide described in step (2) to the solution after secondary neutralization for iron and aluminum removal is 0.1 - 10:

120.

3. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to claim 2, characterized in that, the volume ratio of the hydrogen peroxide described in step (2) to the solution after secondary neutralization for iron and aluminum removal is 1 - 2:

120.

4. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to any one of claims 1 - 3, characterized in that, the reaction time for adding hydrogen peroxide to react in step (2) is 1 - 60 min.

5. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to claim 4, characterized in that, the concentration of the hydrogen peroxide described in step (2) is 5 - 30%.

6. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to any one of claims 1 - 3, characterized in that, the concentration of the concentrated sulfuric acid described in step (1) is 98%.

7. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to claim 1, characterized in that, the alkali described in step (2) is at least one of liquid caustic soda solution and lime milk.

8. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to claim 7, characterized in that, the concentrations of both the liquid caustic soda solution and the lime milk are 5 - 32%.

9. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to any one of claims 1 - 3, characterized in that, the time for primary nickel and cobalt precipitation in step (2) is 0.5 - 3 h.

10. The method for reducing the moisture content of laterite nickel ore MHP product and increasing its manganese content according to claim 1, characterized in that, the overflow after thickening by the thickener in step (3) is subjected to secondary nickel and cobalt precipitation operation as required.

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