Method for improving fluidity of magnesium oxide for cobalt precipitation and application
By using a brine-ammonia-lime combined method to prepare magnesium oxide in hydrometallurgy and adding a flow promoter, the problem of poor flowability of magnesium oxide was solved, achieving a synergistic improvement in high flowability and high cobalt precipitation rate, thus enhancing the stability and economy of the hydrometallurgical cobalt extraction process.
Patent Information
- Application Number
- CN202511553309.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-29
- Publication Date
- 2026-02-06
AI Technical Summary
Magnesium oxide prepared by chemical methods suffers from poor fluidity, difficulty in pH control, and low cobalt recovery rate due to agglomeration and surface roughness in hydrometallurgy, which affects the stability and economy of the hydrometallurgical cobalt extraction process.
Industrial-grade magnesium hydroxide was prepared using a brine-ammonia-lime combined method and then mixed with flow promoters such as calcium stearate or sodium hexametaphosphate to form a high-flowability magnesium oxide cobalt precipitant. The flowability was improved by adjusting the particle size and the amount added.
It significantly improves the fluidity of magnesium oxide by 20%-40%, ensures feeding stability and reaction control, increases the cobalt precipitation rate to over 97%, reduces magnesium residue in cobalt slag, and improves cobalt recovery rate and process efficiency.
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Figure CN121472590A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a method and application for improving the flowability of magnesium oxide used in cobalt precipitation. Background Technology
[0002] In hydrometallurgical cobalt extraction processes, magnesium oxide (MgO) is commonly used as a highly efficient precipitant. Compared to traditional alkaline agents (such as sodium hydroxide), magnesium oxide exhibits a milder reaction, is easier to process, and demonstrates superior cobalt precipitation performance. Furthermore, its wide availability, low cost, and environmental friendliness make it an irreplaceable material in hydrometallurgical cobalt recovery processes, and a key material for achieving efficient and green cobalt resource recovery.
[0003] The raw materials for magnesium oxide used in cobalt precipitation mainly fall into two categories: solid mineral sources and liquid mineral sources. Solid mineral sources mainly include natural ores such as magnesite (MgCO3) and dolomite (CaMg(CO3)2), which are obtained through processes such as high-temperature calcination. Liquid mineral sources include salt lake brine, underground brine, and seawater, which are rich in magnesium ions. They need to first synthesize precursors such as magnesium hydroxide (Mg(OH)2) through precipitation reactions, and then convert them into magnesium oxide through high-temperature calcination.
[0004] Currently, the chemical preparation of magnesium oxide from salt lake magnesium resources is an important approach in the industry. A typical process involves first synthesizing high-purity magnesium hydroxide via a brine-ammonia method, then calcining it at a suitable temperature. The resulting magnesium oxide is then finely ground to achieve the desired particle size. However, to achieve high reactivity and reaction rates, industry commonly uses magnesium oxide smaller than 10 micrometers. This characteristic presents significant challenges during storage, transportation, and feeding: the extremely high surface energy makes particles easily agglomerate due to van der Waals forces and electrostatic attraction, forming difficult-to-disperse agglomerated particles; simultaneously, magnesium oxide smaller than 10 micrometers requires fine grinding, resulting in irregular edges and rough surfaces, leading to significant friction. This makes feeding difficult and results in poor flowability; furthermore, poor dispersibility leads to low magnesium oxide utilization and high magnesium residue in cobalt slag.
[0005] The poor flowability of chemically prepared magnesium oxide is a key technical bottleneck restricting the improvement of cobalt extraction performance in hydrometallurgical processes. Therefore, developing effective flowability improvement strategies is urgently needed. Although traditional methods such as physical granulation have applications in other fields, they significantly inhibit the key precipitation properties (dissolution rate, ion exchange) of magnesium oxide under the harsh conditions of hydrometallurgy, as well as the economic viability for large-scale applications. Therefore, it is essential to address the flow behavior of chemically prepared magnesium oxide in hydrometallurgical applications and explore and develop novel modification technologies that balance high flowability with excellent precipitation properties, providing solid theoretical and technical support for improving the stability and economy of hydrometallurgical cobalt extraction processes. Summary of the Invention
[0006] This invention addresses the technical shortcomings of chemically prepared magnesium oxide in wet cobalt extraction processes, such as poor fluidity due to agglomeration and surface roughness, difficulty in pH control, and low cobalt recovery rate. It provides a simple, low-cost method for preparing high-fluidity magnesium oxide cobalt precipitant and its application, which can simultaneously improve precipitation effect.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for improving the flowability of magnesium oxide used in cobalt deposition, the method comprising the following steps: Step 1: The industrial-grade magnesium hydroxide prepared by the brine-ammonia-lime combined method is calcined and finely ground to obtain magnesium oxide for cobalt precipitation. The magnesium oxide for cobalt precipitation is mixed with a flow promoter in a certain proportion to obtain a high-flow magnesium oxide cobalt precipitation agent.
[0008] Step 2: Weigh a certain amount of high-fluidity magnesium oxide based on the cobalt ion content in the pre-precipitation solution, add water to form a magnesium oxide slurry with a solid-liquid ratio of 10%. After mixing for a period of time, slowly add it to the pre-precipitation solution. After reacting for a period of time, solid and liquid separate, indicating the end of the reaction. Measure the volume of the filtrate using a graduated cylinder and perform elemental analysis (ICP) on the filtrate. Calculate the cobalt precipitation rate and cobalt grade by analyzing the changes in the volume of the cobalt solution and the cobalt ion concentration before and after precipitation.
[0009] Further, in step 1, industrial-grade magnesium hydroxide is prepared using magnesium chloride from salt lake resources as raw material via a brine-ammonia-lime combined method, with a particle size range of 40-50 micrometers. Magnesium oxide used for cobalt precipitation has a particle size of less than 10 micrometers, typically 3-5 micrometers, and an angle of repose greater than 40°. The main components of the flow promoter include, but are not limited to, calcium stearate and sodium hexametaphosphate, with an addition amount of 0.5%-3% of the magnesium oxide weight. The high-flowability magnesium oxide cobalt precipitation agent is magnesium oxide for cobalt precipitation after being treated with the flow promoter; using the angle of repose as a flowability evaluation index, the flowability is improved by 20%-40%.
[0010] Furthermore, in step 2, the cobalt precipitation process is carried out at room temperature and pressure, with the magnesium oxide slurry conditioning time being 0.1-3 h and the cobalt precipitation time being 0.5-10 h.
[0011] Preferably, the amount of flow promoter (calcium stearate, sodium hexametaphosphate) added in step 1 is 1%-2% of the weight of magnesium oxide.
[0012] Furthermore, the method described in this invention can be extended to the wet nickel plating process.
[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention modifies the flowability of magnesium oxide used for cobalt deposition, significantly reducing its angle of repose from greater than 40° and improving powder flowability by 20%-40%. This effectively alleviates the problems of easy agglomeration and poor feeding of magnesium oxide for cobalt deposition prepared by chemical methods during storage, transportation and feeding.
[0014] This invention introduces specific types and proportions of flowability improvers (such as calcium stearate and sodium hexametaphosphate) to achieve precise, stable, and continuous feeding and reaction control without significantly altering the high reactivity of magnesium oxide. This avoids the co-precipitation of impurities caused by local over-alkaliness or pH fluctuations, thereby ensuring the stability of the cobalt precipitation process and the purity of the product.
[0015] This invention maintains the excellent reactivity and selectivity of modified magnesium oxide, ensuring a cobalt precipitation rate of no less than 97%, with an optimal increase of 6.5 percentage points. While improving fluidity, it effectively guarantees precipitation efficiency, achieving synergistic optimization of process efficiency and resource utilization.
[0016] This invention uses a low-cost, low-volume flow promoter (only 1% to 2%), and the process is simple, requiring no complex equipment. It can be directly applied in existing wet cobalt extraction processes, while reducing subsequent processing costs and achieving good economic benefits.
[0017] This invention provides a new technical approach for the efficient and clean extraction of cobalt resources in hydrometallurgy by taking into account process feasibility, economy and environmental friendliness, and has important application value and broad industrialization prospects. Attached Figure Description
[0018] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation
[0019] The technologies in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.
[0020] Example 1: Reference Figure 1 This embodiment provides a method for improving the flowability of magnesium oxide used in cobalt deposition, the specific steps of which are as follows: Step 1: Select industrial-grade magnesium hydroxide (particle size range 40–50 μm) obtained from magnesium chloride minerals from salt lakes via a brine-ammonia-lime combined process. After calcination and fine grinding, obtain magnesium oxide for cobalt precipitation (particle size D50 of 4.8 μm, angle of repose of approximately 42°). Weigh 5 g of this cobalt precipitation magnesium oxide and add 0.05 g of calcium stearate (1% of the weight of magnesium oxide). Place the mixture in a 50 mL centrifuge tube and mix at 24 rpm for 10 min with the assistance of a rod mill to obtain a high-flowability magnesium oxide cobalt precipitation agent. Step 2: Weigh 1.21 g of high-fluidity magnesium oxide cobalt precipitation agent, disperse it in deionized water, and prepare a magnesium oxide slurry with a solid content of 10%. Let it stand for hydration for 30 min. Under room temperature conditions, slowly add 500 mL of pre-precipitation liquid (cobalt ion concentration 2.850 g / L, manganese ion concentration 0.95 g / L, initial pH=5.0) dropwise at a constant rate, while maintaining a stirring speed of 300 r / min. The reaction is stopped after 6 h. After the reaction, solid-liquid separation is performed to obtain filtrate and crude cobalt hydroxide precipitate. The volume of filtrate is measured using a graduated cylinder, and the elemental content in the filtrate is analyzed (ICP-OES). Based on the changes in cobalt liquid volume and cobalt ion concentration before and after the reaction, the cobalt precipitation rate and the grade of crude cobalt hydroxide slag are calculated.
[0021] In this embodiment, the angle of repose of the modified magnesium oxide powder after step 1 was measured to be 28.49° using the angle of repose method, which improved the fluidity by 31.68% compared to the unmodified magnesium oxide (angle of repose 41.7°). The concentration of residual metal ions in the filtrate was analyzed by ICP-OES, and the cobalt precipitation rate was calculated to be 99.29%.
[0022] Example 2: This embodiment is basically the same as embodiment 1, except that: The amount of calcium stearate added in step 1 is 0.5% of the weight of magnesium oxide (i.e., 0.025 g / 5 g magnesium oxide).
[0023] According to the test results, in this embodiment, the angle of repose of the modified magnesium oxide was 31.8°, and the fluidity was improved by 23.74%. The concentration of residual metal ions in the filtrate was analyzed by ICP-OES, and the cobalt precipitation rate was calculated to be 97.6%.
[0024] Example 3: This embodiment is basically the same as Embodiment 1, except that the amount of calcium stearate added in step 1 is 3% of the weight of magnesium oxide (i.e., 0.15 g / 5 g magnesium oxide).
[0025] The modified magnesium oxide was found to have an angle of repose of 24.57° and a fluidity improvement of 41.08%. The concentration of residual metal ions in the filtrate was analyzed by ICP-OES, and the cobalt precipitation rate was calculated to be 96.5%.
[0026] Example 4: Reference Figure 1 This embodiment provides a method for improving the flowability of magnesium oxide used in cobalt deposition, the specific steps of which are as follows: Step 1: Select industrial-grade magnesium hydroxide (particle size range 40–50 μm) obtained from magnesium chloride minerals from salt lakes via a brine-ammonia-lime combined process. After calcination and fine grinding, obtain magnesium oxide for cobalt precipitation (particle size D50 of 4.8 μm, angle of repose of approximately 42°). Weigh 5 g of this cobalt precipitation magnesium oxide and add 0.05 g of sodium hexametaphosphate (1% of the weight of magnesium oxide). Place the mixture in a 50 mL centrifuge tube and mix at 24 rpm for 10 min with the assistance of a rod mill to obtain a high-flowability magnesium oxide cobalt precipitation agent. Step 2: Weigh 1.21 g of high-fluidity magnesium oxide cobalt precipitation agent, disperse it in deionized water, and prepare a magnesium oxide slurry with a solid content of 10%. Let it stand for 30 min to hydrate. At room temperature, slowly add 500 mL of pre-precipitation liquid (cobalt ion concentration 2.850 g / L, manganese ion concentration 0.95 g / L, initial pH=5.0) dropwise at a constant rate, while maintaining a stirring speed of 300 r / min. The reaction is stopped after 6 h. After the reaction, solid-liquid separation is performed, and the filtrate and crude cobalt hydroxide precipitate are separated. The volume of the filtrate is measured using a graduated cylinder, and the elemental content in the filtrate is analyzed (ICP-OES). Based on the changes in the volume of cobalt liquid and the cobalt ion concentration before and after the reaction, the cobalt precipitation rate and the grade of the crude cobalt hydroxide slag are calculated.
[0027] Tests and Results: In this embodiment, the angle of repose of the modified magnesium oxide powder after step 1 was measured to be 32.35° using the angle of repose method, which improved the fluidity by 22.42% compared with the unmodified magnesium oxide (41.7°); the concentration of residual metal ions in the filtrate was analyzed by ICP-OES, and the cobalt precipitation rate was calculated to be 97.56%.
[0028] Example 5: This embodiment is basically the same as embodiment 4, except that the amount of sodium hexametaphosphate added in step 1 is 2% of the weight of magnesium oxide (i.e., 0.10 g / 5 g magnesium oxide).
[0029] Test results: The angle of repose of the modified magnesium oxide was 30.8°, and the fluidity was improved by 26.14%. The concentration of residual metal ions in the filtrate was analyzed by ICP-OES, and the cobalt precipitation rate was calculated to be 98.2%.
[0030] Example 6: This embodiment is basically the same as embodiment 4, except that the amount of sodium hexametaphosphate added in step 1 is 0.5% of the weight of magnesium oxide (i.e., 0.025 g / 5 g magnesium oxide).
[0031] Test results: The angle of repose of the modified magnesium oxide was 34.1°, and the fluidity was improved by 18.22%; the concentration of residual metal ions in the filtrate was analyzed by ICP-OES, and the cobalt precipitation rate was calculated to be 97.2%.
[0032] Comparative example: To verify the improved effect of the method of this invention, a control experiment was conducted under conditions without a flow promoter. 5 g of magnesium oxide (particle size D50 of 4.8 μm) for cobalt precipitation was weighed and its flowability was determined using the angle of repose method. Then, 1.21 g of magnesium oxide was weighed and dispersed in deionized water to prepare a magnesium oxide slurry with a solid content of 10%, which was allowed to stand for 30 min to hydrate. At room temperature, this slurry was added to 500 mL of pre-precipitation cobalt solution (cobalt ion concentration 2.850 g / L, manganese ion concentration 0.95 g / L, initial pH = 5.0), and the reaction was maintained at a stirring speed of 300 r / min for 6 h. After the reaction, solid-liquid separation was performed, and the cobalt ion concentration in the filtrate was measured.
[0033] Test results: The angle of repose of magnesium oxide was 41.7°, and the cobalt deposition rate was 92.74%.
[0034] Compared with the comparative examples, the angle of repose of the high-flowability magnesium oxide cobalt precipitating agents obtained in Examples 1–6 of this invention were significantly reduced. Using the angle of repose as a flowability evaluation index, the powder flowability was improved by 20%–40%, effectively solving the problem of feeding difficulties caused by agglomeration and poor feeding of magnesium oxide prepared by chemical methods. At the same time, the cobalt precipitation rate increased from 92.74% in the comparative examples to the range of 96%–99%, with the cobalt precipitation rate of Example 1 reaching 99.29%, significantly improving the cobalt recovery efficiency and the grade of crude cobalt hydroxide slag.
[0035] Therefore, it can be seen that by introducing a small amount of flow promoter into magnesium oxide, the present invention can maintain high reactivity while taking into account both powder flowability and cobalt precipitation performance, which is significantly better than the unmodified comparative example, and has outstanding practical value and promotion prospects.
[0036] Example 7: This embodiment provides an experimental method for improving the flowability of magnesium oxide for nickel plating by using calcium stearate as a flow promoter. The process steps are basically the same as those in Example 1, except that the pre-cobalt plating solution is replaced with the pre-nickel plating solution.
[0037] Step 1: Same as in Example 1, industrial grade magnesium hydroxide is calcined and finely ground to obtain magnesium oxide for nickel immersion, and then 0.25 g of calcium stearate (1% of the weight of magnesium oxide) is added and mixed evenly to obtain high-flowability magnesium oxide nickel immersion agent.
[0038] Step 2: Weigh 2.51 g of high-fluidity magnesium oxide nickel precipitation agent, disperse it in deionized water, and prepare a magnesium oxide slurry with a solid content of 10%. Stir and adjust the slurry for 20 min. Under room temperature conditions, slowly add the slurry dropwise at a constant rate to 500 mL of pre-precipitation nickel solution (nickel ion concentration 3.83 g / L, cobalt ion concentration 0.36 g / L, manganese ion concentration 2.5 g / L, magnesium ion concentration 6.8 g / L, initial pH=4.5), while maintaining a stirring speed of 300 r / min. The reaction is stopped after 3 h, followed by solid-liquid separation to obtain filtrate and crude nickel hydroxide precipitate. Collect the filtrate and determine the metal ion concentration to calculate the nickel precipitation rate.
[0039] Tests and Results: In this embodiment, the angle of repose of the high-flowability magnesium oxide powder was measured to be 28.49° using the angle of repose method, indicating a flowability improvement of approximately 32% compared to unmodified magnesium oxide (41.7°). The residual nickel ion concentration in the filtrate was analyzed using ICP-OES, and the calculated nickel deposition rate was 87.78%, which is 3.5% higher than that of magnesium oxide used for cobalt deposition without added flow promoters. The results demonstrate that this method is also applicable to nickel deposition systems, significantly improving the flowability of magnesium oxide powder while maintaining excellent nickel deposition performance.
Claims
1. A method for improving the flowability of magnesium oxide used in cobalt deposition, characterized in that, Includes the following steps: Step 1: Industrial-grade magnesium hydroxide prepared by the brine-ammonia-lime combined method is calcined and finely ground to obtain magnesium oxide for cobalt precipitation. The magnesium oxide for cobalt precipitation is mixed with a flow promoter in a certain proportion to obtain a high-flow magnesium oxide cobalt precipitation agent. The flow promoter includes any one of calcium stearate and sodium hexametaphosphate. The amount of the flow promoter added is 0.5%-3% of the weight of the magnesium oxide for cobalt precipitation. Step 2: Weigh a certain amount of high-fluidity magnesium oxide according to the cobalt ion content in the pre-cobalt precipitation solution, add water to form a slurry with a solid content of 10%, mix for a period of time and then slowly add it to the pre-cobalt precipitation solution. After reacting for a period of time, the solid and liquid are separated. Measure the volume of the filtrate with a graduated cylinder and analyze the element content in the filtrate. Calculate the cobalt precipitation rate and cobalt grade by the changes in the volume of the cobalt solution before and after precipitation and the cobalt ion concentration.
2. The method for improving the flowability of magnesium oxide for cobalt deposition according to claim 1, characterized in that, The industrial-grade magnesium hydroxide mentioned in step 1 is prepared using magnesium chloride from salt lake resources as raw material and a brine-ammonia-lime combined method, with a particle size range of 40-50 micrometers.
3. The method for improving the flowability of magnesium oxide for cobalt deposition according to claim 1, characterized in that, The magnesium oxide particles used for cobalt deposition in step 1 have a particle size of less than 10 micrometers, typically 3-5 micrometers, and an angle of repose greater than 40°.
4. The method for improving the flowability of magnesium oxide for cobalt deposition according to claim 1, characterized in that, The high-flowability magnesium oxide cobalt precipitation agent mentioned in step 1 is magnesium oxide for cobalt precipitation after being treated with a flow promoter. The flowability is improved by 20%-40% with the angle of repose as the flowability evaluation index.
5. The method for improving the flowability of magnesium oxide for cobalt deposition according to claim 1, characterized in that, The reaction process in step 2 is carried out at room temperature and pressure, wherein the slurry conditioning time is controlled at 0.1-3 h and the cobalt precipitation time is controlled at 0.5-10 h.
6. The method for improving the flowability of magnesium oxide for cobalt deposition according to claim 1, characterized in that, The amount of flow promoter added in step 1 is 1%-2% of the weight of magnesium oxide.
7. The method for improving the flowability of magnesium oxide for cobalt deposition according to any one of claims 1 to 6, characterized in that, The cobalt recovery rate is no less than 97%.
8. The method for improving the flowability of magnesium oxide for cobalt deposition according to claim 7, characterized in that, The method is applicable to wet nickel plating.