Method for improving slow release property of magnesium oxide for precipitating cobalt and nickel and application

Abstract

The invention discloses a method for improving the slow release property of magnesium oxide for cobalt and nickel precipitation and application. The hydration inhibitor of a specific type and proportion is introduced in the magnesium oxide pulping stage, the hydration dissolution rate is effectively delayed, the alkaline slow release performance is remarkably improved, and co-precipitation of impurities such as manganese and magnesium caused by overhigh local pH of a reaction system is avoided; by accurately controlling the pH value of a precipitation system to be in an optimal interval, preferential selective precipitation of nickel and cobalt ions is guaranteed, the nickel precipitation rate is not lower than 91%, the cobalt precipitation rate is not lower than 95%, the magnesium content in the slag is reduced to 0.25% or below, and the nickel grade of the cobalt / nickel-rich slag reaches 44% or above. The process is simple and convenient, only a small amount of low-cost hydration inhibitor needs to be added in an existing slurrying process, complex equipment transformation is not needed, the method can be directly applied and popularized in an existing wet smelting production line, economic benefits are good, a new technical approach is provided for efficient and clean extraction of nickel and cobalt resources, and the method conforms to the improvement direction of a wet smelting process; the method has an important application value and a wide industrialization prospect.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to a method and application for improving the slow-release properties of magnesium oxide used in cobalt and nickel deposition. Background Technology

[0002] In the hydrometallurgical process of laterite nickel ore or copper-cobalt oxide ore, after acid leaching, the resulting sulfate medium often contains multiple valuable metals such as nickel, cobalt, manganese, and magnesium. The key separation process is to efficiently and selectively enrich nickel and cobalt from this sulfate medium. While sulfide precipitation is effective in traditional processes, it requires precise pH control to avoid the generation of toxic hydrogen sulfide gas. Furthermore, excessively high pH can lead to the precipitate being contaminated with too much manganese and magnesium impurities, making subsequent processing difficult. Neutralization precipitation using sodium hydroxide or sodium carbonate is prone to causing manganese and magnesium co-precipitation due to localized over-alkaliness, while also forming hydroxide colloids, resulting in low liquid-solid separation efficiency and introducing impurity ions such as sodium and ammonium, increasing the burden on subsequent purification.

[0003] Compared with traditional precipitants, activated magnesium oxide shows significant advantages in the selective precipitation of nickel and cobalt: its moderate alkalinity allows the pH to be adjusted to 7-8 in stages, so that nickel and cobalt (precipitation pH 7.1-8.2) are preferentially precipitated, while manganese and magnesium (precipitation pH >8.2) are retained in the solution, thereby achieving efficient and selective enrichment of nickel and cobalt.

[0004] However, magnesium oxide still suffers from disadvantages in practical applications due to its rapid hydration rate and low slow-release properties: its powder form dissolves too quickly in aqueous solutions, easily leading to uneven precipitation due to localized over-alkaliness, and potentially forming hydroxides, thus reducing separation efficiency. Existing patents optimize the structure and activity of magnesium oxide during its preparation stage for precipitation separation of cobalt / nickel-containing acidic leachates from laterite nickel ore and other materials in hydrometallurgical processes. For example, application number CN201810842791.0 discloses an active magnesium oxide, its preparation method, and its application, which mainly prepares highly active, high-bulk-density whisker-like magnesium oxide through reverse injection, dynamic gradient drying, and two-stage roasting. However, this approach to achieving efficient and selective enrichment of nickel and cobalt suffers from poor slow-release control flexibility. Based on this, this application focuses on optimizing the performance of magnesium oxide during its application stage by adding a hydration inhibitor (sodium citrate) during the magnesium oxide slurry preparation stage. By inhibiting the hydration rate of magnesium oxide, slow-release properties are achieved, thereby optimizing the cobalt / nickel precipitation effect. Summary of the Invention

[0005] Based on the above-mentioned technical problems, the purpose of this invention is to provide a method and application for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition.

[0006] This invention protects a method for improving the slow-release properties of magnesium oxide used in cobalt and nickel deposition, specifically comprising the following steps: Step 1: Mix magnesium oxide with water to form a pulp, and add a hydration inhibitor during the pulping process. After mixing and adjusting the pulp, a magnesium oxide slow-release pulp is obtained; the amount of the hydration inhibitor added is 2-6% of the mass of magnesium oxide. Step 2: Add the above-mentioned magnesium oxide slow-release slurry to the solution to be treated containing cobalt and / or nickel to carry out a precipitation reaction. After the reaction is completed, perform solid-liquid separation to obtain cobalt-rich / nickel slag and a solution containing impurity ions.

[0007] Furthermore, in step 1, the hydration inhibitor is sodium citrate; and the water is deionized water.

[0008] Further, in step 1, the slurry preparation involves stirring at 350 r / min for 1.5 h at room temperature.

[0009] Furthermore, in step 1, the solid content of the slurry in the pulping process is 5-20%.

[0010] Furthermore, in step 1, the amount of magnesium oxide added is 0.8 to 1.0 times the stoichiometric amount required for the theoretical precipitation of cobalt and / or nickel in the solution to be treated.

[0011] Furthermore, in step 2, the precipitation reaction temperature is 50~80℃, the reaction time is 1~5h, and the stirring speed is 50~150r / min.

[0012] Furthermore, in step 2, the solution to be treated is a sulfate solution produced by acid leaching of laterite nickel ore or copper-cobalt oxide ore, and the solution contains cobalt, nickel, manganese and magnesium ions; the final pH value of the precipitation reaction system is controlled at 7.0~8.2.

[0013] This invention also protects the application of the above method to the processes of wet cobalt deposition and wet nickel deposition.

[0014] Compared with existing technologies, the present invention has the following beneficial effects: The method of this invention effectively slows down the hydration and dissolution rate of magnesium oxide particles by introducing specific types and proportions of hydration inhibitors during the magnesium oxide slurry preparation stage, significantly improving its alkaline slow-release performance. This avoids the co-precipitation problem of impurity ions such as manganese and magnesium caused by excessively high local pH in the reaction system. By improving the slow-release properties of magnesium oxide, the pH environment of the precipitation reaction system is stabilized and controllable, ensuring that nickel and cobalt ions preferentially and selectively precipitate within the optimal pH range of 7.0 to 8.2, resulting in a nickel precipitation rate of no less than 91% and a cobalt precipitation rate of no less than 95%. Simultaneously, the magnesium content in the slag is significantly reduced to no more than 0.25%, effectively improving the product grade of cobalt-rich / nickel slag, with a nickel grade of no less than 44%. This method is simple, requiring only the addition of a small amount of hydration inhibitor to the existing slurry process, without the need for complex equipment modifications. The hydration inhibitor is inexpensive and requires only a small amount, making it easy to directly promote and apply in existing hydrometallurgical production lines, reducing reagent consumption and subsequent purification burden, and possessing good economic benefits. By optimizing the precipitation process, the slow-release performance of magnesium oxide was improved, enabling it to release alkalinity more stably and controllably in solution. This increased the recovery rate and product purity of the target metal, reduced impurity entrainment, and provided a new technical approach for the efficient and clean extraction of nickel and cobalt resources. It has become an important research direction for improving hydrometallurgical processes and has significant application value and broad industrialization prospects. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 A method for improving the sustained-release properties of magnesium oxide for cobalt and nickel deposition specifically includes the following steps: Step 1: Weigh 2.51g of active magnesium oxide and mix it with deionized water to prepare a slurry with a solid content of 5-20%. Add sodium citrate to the slurry as a hydration inhibitor, with an addition amount of 2% of the magnesium oxide mass, approximately 0.05g. Stir the slurry at 350r / min for 1.5h at room temperature to obtain magnesium oxide slow-release slurry. Step 2: Take 1000 mL of the simulated pre-solution containing nickel and cobalt (nickel ion concentration 3.83 g / L, cobalt ion concentration 0.36 g / L, magnesium ion concentration 6.8 g / L, initial pH ≈ 4.5) in a beaker, heat in a water bath and maintain the reaction temperature at 60℃. Under a stirring rate of 100 r / min, add all of the above magnesium oxide slow-release slurry to the reaction system. Control the final pH value of the precipitation reaction system at 7.0~8.2. The reaction is stopped after 3 hours. Then, vacuum filtration is performed to achieve solid-liquid separation. Collect the filtrate and analyze the residual concentrations of nickel, cobalt and magnesium using ICP-OES, and calculate the precipitation rate and nickel grade in the slag. The results show that the nickel precipitation rate is 94.08%, the cobalt precipitation rate is 96.99%, the magnesium content in the obtained nickel slag is 0.20%, and the nickel grade is 46.07%.

[0018] Example 2 A method for improving the sustained-release properties of magnesium oxide for cobalt and nickel deposition specifically includes the following steps: Step 1: Weigh 2.51g of active magnesium oxide and mix it with deionized water to prepare a slurry with a solid content of 5-20%. Add sodium citrate as a hydration inhibitor to the slurry, with an addition amount of 4% of the magnesium oxide mass, approximately 0.10g. Stir the slurry at 350r / min for 1.5h at room temperature to obtain magnesium oxide slow-release slurry. Step 2: Take 1000 mL of the simulated pre-solution containing nickel and cobalt (nickel ion concentration 3.83 g / L, cobalt ion concentration 0.36 g / L, magnesium ion concentration 6.8 g / L, initial pH ≈ 4.5) in a beaker, heat in a water bath and maintain the reaction temperature at 60℃. Under a stirring rate of 100 r / min, add all of the above magnesium oxide slow-release slurry to the reaction system. Control the final pH value of the precipitation reaction system at 7.0~8.2. The reaction is stopped after 3 hours. Then, vacuum filtration is performed to achieve solid-liquid separation. Collect the filtrate and analyze the residual concentrations of nickel, cobalt and magnesium using ICP-OES, and calculate the precipitation rate and nickel grade in the slag. The results show that the nickel precipitation rate is 91.86%, the cobalt precipitation rate is 95.54%, the magnesium content in the obtained nickel slag is 0.22%, and the nickel grade is 44.21%.

[0019] Example 3 A method for improving the sustained-release properties of magnesium oxide for cobalt and nickel deposition specifically includes the following steps: Step 1: Weigh 2.51g of active magnesium oxide and mix it with deionized water to prepare a slurry with a solid content of 5-20%. Add sodium citrate to the slurry as a hydration inhibitor, with an addition amount of 6% of the magnesium oxide mass, approximately 0.15g. Stir the slurry at 350r / min for 1.5h at room temperature to obtain magnesium oxide slow-release slurry. Step 2: Take 1000 mL of the simulated pre-solution containing nickel and cobalt (nickel ion concentration 3.83 g / L, cobalt ion concentration 0.36 g / L, magnesium ion concentration 6.8 g / L, initial pH ≈ 4.5) in a beaker, heat in a water bath and maintain the reaction temperature at 60℃. Under a stirring rate of 100 r / min, add all of the above magnesium oxide slow-release slurry to the reaction system. Control the final pH value of the precipitation reaction system at 7.0~8.2. The reaction is stopped after 3 hours. Then, vacuum filtration is performed to achieve solid-liquid separation. Collect the filtrate and analyze the residual concentrations of nickel, cobalt and magnesium using ICP-OES, and calculate the precipitation rate and nickel grade in the slag. The results show that the nickel precipitation rate is 94.35%, the cobalt precipitation rate is 97.27%, the magnesium content in the obtained nickel slag is 0.18%, and the nickel grade is 45.74%.

[0020] Comparative Example 1 To verify the improved effect of the method of the present invention, a control experiment was conducted under the condition of no hydration inhibitor. 2.51 g of active magnesium oxide from the same source as in Example 1 (the amount added was 0.85 times the theoretical amount) was weighed and directly prepared into a regular slurry with a solid content of 10%. Without slow release treatment, after slurry preparation for 1.5 h, a nickel precipitation experiment was immediately carried out under the same reaction conditions: reaction temperature 60℃, stirring speed 100 r / min, and reaction time 3 h.

[0021] Test results showed that due to the rapid hydration of magnesium oxide, hydroxides were generated, leading to an excessively high local pH in the early stages of the reaction, causing a large amount of magnesium impurities to co-precipitate. Measurements showed a nickel precipitation rate of 76.83% and a cobalt precipitation rate of 90.52%, but the resulting nickel slag contained a magnesium content as high as 4.13%, with a nickel grade of only 37.69%.

[0022] Compared with Comparative Example 1, Examples 1-3 of this invention significantly improved the slow-release performance of magnesium oxide by adding 2%-6% hydration inhibitor. Experimental results consistently show that, using the method of this invention, while maintaining high nickel and cobalt precipitation rates (nickel ≥ 91.86%, cobalt ≥ 95.54%), the magnesium impurity content in the slag can be effectively controlled at an extremely low level below 0.22%, significantly increasing the nickel grade of the precipitated product to ≥ 44.21%. This demonstrates that the hydration inhibitor, by delaying magnesium oxide hydration, avoids localized over-alkaliness, thereby achieving highly efficient and selective precipitation of nickel and cobalt, solving the key problem of severe impurity entrainment in traditional methods.

[0023] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the sustained-release properties of magnesium oxide used in cobalt and nickel deposition, characterized in that, Specifically, the steps include the following: Step 1: Mix magnesium oxide with water to form a pulp, and add a hydration inhibitor during the pulping process. After mixing and adjusting the pulp, a magnesium oxide slow-release pulp is obtained; the amount of the hydration inhibitor added is 2-6% of the mass of magnesium oxide. Step 2: Add the above-mentioned magnesium oxide slow-release slurry to the solution to be treated containing cobalt and / or nickel to carry out a precipitation reaction. After the reaction is completed, perform solid-liquid separation to obtain cobalt-rich / nickel slag and a solution containing impurity ions.

2. The method for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition according to claim 1, characterized in that, In step 1, the hydration inhibitor is sodium citrate; the water is deionized water.

3. The method for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition according to claim 1, characterized in that, In step 1, the slurry preparation involves stirring at 350 r / min for 1.5 h at room temperature.

4. The method for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition according to claim 1, characterized in that, In step 1, the solid content of the slurry in the pulping process is 5-20%.

5. The method for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition according to claim 1, characterized in that, In step 1, the amount of magnesium oxide added is 0.8 to 1.0 times the stoichiometric amount required for the theoretical precipitation of cobalt and / or nickel in the solution to be treated.

6. The method for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition according to claim 1, characterized in that, In step 2, the precipitation reaction is carried out at a temperature of 50-80°C, for a reaction time of 1-5 hours, and at a stirring speed of 50-150 r / min.

7. The method for improving the slow-release properties of magnesium oxide for cobalt and nickel deposition according to claim 1, characterized in that, In step 2, the solution to be treated is a sulfate solution produced by acid leaching of laterite nickel ore or copper-cobalt oxide ore, and the solution contains cobalt, nickel, manganese and magnesium ions; the final pH value of the precipitation reaction system is controlled at 7.0~8.

2.

8. An application of a method for improving the sustained-release properties of magnesium oxide in cobalt and nickel deposition, characterized in that, The application is the application of the method described in any one of claims 1-7, whereby the method is applied to the processes of wet cobalt deposition and wet nickel deposition.

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