A method for selective leaching from crude cobalt hydroxide

Abstract

This invention discloses a method for selective leaching of crude cobalt hydroxide, comprising the following steps: S1, mixing crude cobalt hydroxide, ammonium leaching agent, and water, and adding an active additive to carry out an ammonium leaching reaction; after the reaction, performing solid-liquid separation to obtain a leachate and a leaching residue; S2, adding a sulfiding agent to the leachate to carry out a precipitation reaction; after the reaction, performing solid-liquid separation to obtain metal sulfides and demetallization wastewater; S3, mixing the leaching residue with water to form a slurry, then adding an acid leaching agent and a reducing agent to carry out an acid leaching reaction; after the reaction, performing solid-liquid separation to obtain a leachate rich in cobalt and manganese and a final residue; the method further includes a cyclic leaching step: using the demetallization wastewater as a regenerated ammonium leaching agent, reusing it for the ammonium leaching reaction in step S1; and repeating steps S1-S2 until the regenerated ammonium leaching agent reaches a predetermined number of regenerations. This invention achieves a total leaching rate of ≥99% for both cobalt and manganese through the selective complexation effect of the ammonium leaching agent.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, and particularly relates to a method for selective leaching of crude cobalt hydroxide. Background Technology

[0002] Crude cobalt hydroxide is a common intermediate product or secondary resource in hydrometallurgical processes. Its main components are hydroxides of cobalt and manganese, accompanied by various metallic impurities such as nickel, copper, iron, aluminum, calcium, and magnesium. This material is usually in an amorphous or microcrystalline state, with high chemical reactivity, but its composition fluctuates greatly, posing a challenge to its subsequent efficient and economical recovery of valuable metals.

[0003] Currently, the main methods for recovering valuable metals from such materials are acid leaching and ammonia leaching. Acid leaching (such as sulfuric acid leaching) typically uses an excess of inorganic acid, which can quickly and efficiently dissolve valuable metals such as cobalt and manganese at high temperatures. However, this process lacks selectivity, leading to the co-leaching of large amounts of impurity metals such as iron, aluminum, calcium, and magnesium, resulting in a complex leachate composition. Subsequent purification and separation processes are lengthy, reagent consumption is high, and overall costs are high. Ammonia leaching (such as the ammonia-ammonium carbonate system) utilizes the selective complexation of ammonia with nickel, cobalt, and copper, allowing impurities such as iron and aluminum to remain in the slag, resulting in a relatively pure leachate. However, free ammonia in this process is volatile, the operating environment is harsh, it is sensitive to the composition of the material (such as calcium and magnesium content), and the ammonia nitrogen wastewater treatment burden is heavy, limiting its widespread application. In contrast, using ammonium salts (such as ammonium chloride and ammonium sulfate) as leaching agents can significantly reduce the risk of ammonia volatilization while maintaining the selective complexation advantage, and provides a feasible way for the recycling and regeneration of leaching agents.

[0004] A common challenge with existing mineral leaching technologies lies in balancing "high-efficiency leaching" with "selective control," and "process economics" with "subsequent purification burden." Simply pursuing a high leaching rate often results in excessively high impurity concentrations in the leachate, making subsequent separation and purification processes lengthy and expensive. Conversely, strengthening preliminary purification during the leaching stage to alleviate subsequent purification pressure often requires sacrificing some leaching efficiency or introducing more complex process controls, leading to decreased recovery rates of valuable metals or increased process complexity.

[0005] Therefore, developing a novel, efficient, low-consumption cyclic leaching method for crude cobalt hydroxide materials, which can achieve preliminary impurity suppression or separation, is of great significance for simplifying the entire process, reducing overall costs, and improving the recovery rate of valuable metals such as cobalt and manganese. Summary of the Invention

[0006] The purpose of this invention is to provide a method for selective leaching of crude cobalt hydroxide, which solves the problem of difficulty in achieving both high efficiency leaching and selective control in the prior art. While ensuring high leaching rates of cobalt, manganese, etc., it effectively suppresses the leaching of impurities and significantly reduces the consumption of leaching agent, thereby reducing process costs.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for selective leaching of crude cobalt hydroxide, comprising the following steps: S1. Crude cobalt hydroxide, ammonium leaching agent and water are mixed and active additives are added to carry out ammonium leaching reaction. After the reaction is completed, solid-liquid separation is carried out to obtain the first leaching solution and the first leaching residue. S2. Add a sulfiding agent to the first leachate to carry out a precipitation reaction. After the reaction is completed, perform solid-liquid separation to obtain metal sulfides and demetallized waste liquid. S3. Mix the first leaching residue with water to form a slurry, then add acid leaching agent and reducing agent to carry out an acid leaching reaction. After the reaction is completed, perform solid-liquid separation to obtain a leaching solution and final residue rich in cobalt and manganese. The method further includes a cyclic leaching step: the demetallized waste liquid in step S2 is used as a regenerated ammonium leaching agent and reused in step S1 to react the first leaching residue obtained in step S3 with new crude cobalt hydroxide for ammonium leaching; and steps S1 to S2 are repeated until the regenerated ammonium leaching agent reaches the predetermined number of regenerations.

[0008] Preferably, in step S1, the crude cobalt hydroxide is crushed and then passed through a 100-200 mesh sieve; The crude cobalt hydroxide contains 25-35% cobalt by mass and 2-5% manganese by mass.

[0009] Preferably, in step S1, the ammonium leaching agent includes at least one of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, urea, and other solutions containing ammonium ions. And / or, in step S1, the active additive is selected from at least one of sodium hexametaphosphate, sodium tripolyphosphate, sulfate salt, TW-20 and disodium ethylenediaminetetraacetate; And / or, in step S2, the sulfiding agent is selected from at least one of sodium sulfide, ammonium sulfide, barium sulfide and calcium sulfide; And / or, in step S3, the acidic leaching agent is selected from at least one of sulfuric acid, hydrochloric acid, nitric acid and citric acid, and the reducing agent is selected from at least one of ammonium sulfite, sodium sulfite, sodium bisulfite and ferrous sulfate.

[0010] Preferably, in step S1, the mass ratio of the crude cobalt hydroxide, ammonium leaching agent, and water is 1:(2~8):(3.5~9); And / or, in step S1, the mass ratio of the crude cobalt hydroxide to the active additive is 1:(0.001-0.01).

[0011] Preferably, the temperature of the ammonium salt leaching reaction in step S1 is 30~120℃, the stirring speed is 300~600rpm, and the reaction time is 60~480min.

[0012] Preferably, in step S2, the ratio of the total mass of the sulfiding agent to the total mass of cobalt and manganese in the first leachate is (1.45~3):1; And / or, in step S3, the mass ratio of the first leaching residue, the acidic leaching agent, and the reducing agent is 1:(0.09-0.18):(0.002-0.05).

[0013] Preferably, the temperature of the precipitation reaction in step S2 is 20~70℃, and the reaction time is 60~480min.

[0014] Preferably, in step S3, the solid-liquid ratio of the acid leaching reaction is 1:(3-10), the reaction temperature is 30~90℃, the reaction time is 40~240min, and the stirring speed is 300~600rpm.

[0015] Preferably, the predetermined number of regenerations is at least 3 times.

[0016] First, the initial leaching uses ammonium leaching agent to establish a baseline leaching efficiency; the second leaching uses the regenerated waste liquid generated initially to verify the feasibility of waste liquid regeneration and recycling, and to begin utilizing residual ammonium salts; the crucial third and subsequent cycles are designed to fully exploit the potential of the regenerated ammonium leaching agent and achieve a substantial reduction in reagent consumption.

[0017] Preferably, in step S3, the total leaching rate of cobalt and manganese in the leachate is ≥99%.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: Ammonium leaching agent is used, which selectively complexes with cobalt and manganese. This improves the leaching rate of cobalt and manganese while effectively inhibiting the leaching of impurities such as iron, aluminum, calcium, and magnesium. Compared with the traditional acid leaching method, the purity of the leaching solution is significantly improved, reducing the burden of subsequent purification.

[0019] This invention achieves further extraction of cobalt and manganese remaining in the leaching residue by regenerating the demetallization waste liquid into ammonium leaching agent and recycling it. At the same time, the sulfide precipitation step can selectively precipitate cobalt and manganese in the leaching liquid into sulfide intermediate products, which facilitates subsequent processing.

[0020] The "leaching-precipitation-regeneration" recycling system constructed in this invention can realize the multiple recycling of ammonium leaching agent, reduce ammonium salt consumption and ammonium-containing wastewater discharge, and reduce reagent costs and environmental pressure. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a process flow diagram of the cyclic leaching method in this invention; Figure 2 The leaching rate curves of cobalt and manganese in the leachate obtained by the ammonium leaching reaction in Example 1 of this invention are shown. Figure 3 The leaching rate curves of cobalt and manganese in the leachate obtained by the ammonium leaching reaction in Example 2 of the present invention are shown. Detailed Implementation

[0023] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0024] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0026] It should be understood that in various embodiments of the present invention, the order of the above-mentioned processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0027] According to a first aspect of the present invention, the present invention provides a method for selective leaching of crude cobalt hydroxide, comprising the following steps: S1. Crude cobalt hydroxide, ammonium leaching agent and water are mixed and active additives are added to carry out ammonium leaching reaction. After the reaction is completed, solid-liquid separation is carried out to obtain the first leaching solution and the first leaching residue. S2. Add a sulfiding agent to the first leachate to carry out a precipitation reaction. After the reaction is completed, perform solid-liquid separation to obtain metal sulfides and demetallized waste liquid. S3. Mix the first leaching residue with water to form a slurry, then add acid leaching agent and reducing agent to carry out an acid leaching reaction. After the reaction is completed, perform solid-liquid separation to obtain a leaching solution and final residue rich in cobalt and manganese. The method further includes a cyclic leaching step: the demetallized waste liquid in step S2 is used as a regenerated ammonium leaching agent and reused in step S1 to react the first leaching residue obtained in step S3 with new crude cobalt hydroxide for ammonium leaching; and steps S1 to S2 are repeated until the regenerated ammonium leaching agent reaches the predetermined number of regenerations.

[0028] During the cyclic leaching process, the ammonium salts in the demetallized waste liquid are retained after sulfidation precipitation and can be directly reused as regenerated ammonium leaching agent. With increasing cycles, small amounts of impurities such as sulfate and sulfide ions may accumulate in the system. However, because the ammonium salt concentration remains at a high level (ammonium chloride content is above 81% in the examples), and the selective complexation leaching of cobalt and manganese has a certain tolerance to impurity ions, stable leaching efficiency can be maintained even after multiple cycles. In actual production, fresh ammonium leaching agent can be added appropriately based on the ammonium salt concentration detection results to maintain system activity.

[0029] This invention utilizes an ammonium leaching agent to selectively extract cobalt and manganese from crude cobalt hydroxide, thereby obtaining an ammonium leachate. A sulfiding agent is added to the ammonium leachate to precipitate cobalt, manganese, and other metallic elements, yielding metal sulfides and demetallization wastewater. The metal sulfides can be further processed to obtain high-purity cobalt and manganese products, while the demetallization wastewater can be reused as recycled ammonium leaching agent in the ammonium leaching process. This method effectively solves the problem of balancing high-efficiency leaching with selective control in existing technologies. Through the selective complexation effect of the ammonium leaching agent, high leaching rates of cobalt and manganese are achieved while significantly reducing the leaching rate of impurities. Furthermore, the recycling of the ammonium leaching agent and wastewater greatly reduces the consumption of ammonium leaching agent, lowering process costs.

[0030] In some embodiments of the present invention, in step S1, the crude cobalt hydroxide is crushed and then passed through a 100-200 mesh sieve; The crude cobalt hydroxide contains 25-35% cobalt by mass and 2-5% manganese by mass. For example, the cobalt content in the crude cobalt hydroxide can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, etc., and the manganese content can be 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, etc.

[0031] In some embodiments of the present invention, in step S1, the ammonium leaching agent includes at least one of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, urea, and other solutions containing ammonium ions. In some embodiments of the present invention, in step S1, the active additive is selected from at least one of sodium hexametaphosphate, sodium tripolyphosphate, sulfate salt, TW-20 and disodium ethylenediaminetetraacetate; In some embodiments of the present invention, in step S2, the sulfiding agent is selected from at least one of sodium sulfide, ammonium sulfide, barium sulfide and calcium sulfide; In some embodiments of the present invention, in step S3, the acidic leaching agent is selected from at least one of sulfuric acid, hydrochloric acid, nitric acid and citric acid, and the reducing agent is selected from at least one of ammonium sulfite, sodium sulfite, sodium bisulfite and ferrous sulfate.

[0032] The active additives of this invention mainly play the following synergistic role: taking sodium hexametaphosphate as an example, the phosphate group in its molecular structure can react with Ca in the solution. 2+ Mg 2+ The formation of stable soluble chelates effectively inhibits the formation of insoluble complex salts or adsorption / encapsulation of calcium and magnesium ions with cobalt and manganese, thereby improving the leaching efficiency of cobalt and manganese. Simultaneously, sodium hexametaphosphate disperses colloidal particles generated from the hydrolysis of iron and aluminum, reducing slurry viscosity, improving solid-liquid separation performance, preventing colloid coverage of the mineral surface, and ensuring the continuous and efficient leaching reaction. This invention preferably uses ammonium sulfide as a precipitant, which has the advantage that after the precipitation reaction is completed, the NH4+ in the solution... + and excessive S 2- The NH3 can be effectively removed by heating or ammonia stripping, and it can be recovered and recycled. Simultaneously, the resulting cobalt-nickel sulfide filter cake has high purity and is suitable for subsequent processes (such as oxidative acid hydrolysis or oxidative roasting). The amount added is adjusted appropriately based on the cobalt and manganese content in the first leachate.

[0033] In some embodiments of the present invention, in step S1, the mass ratio of the crude cobalt hydroxide, ammonium leaching agent and water is 1:(2~8):(3.5~9); In some embodiments of the present invention, in step S1, the mass ratio of the crude cobalt hydroxide to the active additive is 1:(0.001-0.01).

[0034] The active additive is a functional additive that accelerates the selective dissolution of cobalt and manganese, allowing for a more complete ammonium leaching reaction. The addition amount of the active additive is set to 0.1% to 1% of the mass of crude cobalt hydroxide because: at 0.1%, the active additive provides sufficient catalytic active sites, significantly reducing the reaction activation energy and promoting the selective leaching of valuable metals, while minimizing reagent costs and reducing the potential activation of impurities or subsequent separation burden due to excessive addition. At 1%, it can fully cover the active surface of the mineral and establish a stable catalytic or selective complexation environment to cope with materials with large fluctuations in composition and uneven reactivity, ensuring the high efficiency and stability of the leaching process.

[0035] In some embodiments of the present invention, the temperature of the ammonium salt leaching reaction in step S1 is 30~120℃, the stirring speed is 300~600rpm, and the reaction time is 60~480min.

[0036] The temperature range (30~120℃) is set because: at around 30℃, although the reaction rate is slower, it effectively suppresses the vigorous volatilization of ammonia, reduces losses, and improves the operating environment. It also helps maintain the selectivity of the ammonium salt complexation system and prevents the unnecessary dissolution of some impurities (such as some magnesium and calcium). Raising the temperature to 120℃ greatly accelerates the dissolution of solid materials and the complexation reaction of metal ions, overcomes diffusion resistance, and significantly shortens the time required to reach equilibrium. This is particularly suitable for processing materials with slightly lower activity or requiring high leaching rates.

[0037] The stirring speed range (300~600 rpm) is set because 300 rpm is usually the minimum effective stirring intensity, which is sufficient to prevent solid material sedimentation, maintain uniform solid-liquid suspension, and promote mass exchange at the reaction interface, which is a basic condition for ensuring a stable reaction. Increasing the stirring speed to 600 rpm can further enhance liquid-phase mass transfer, effectively reduce the thickness of the solid-liquid boundary layer, accelerate the transfer of reactants to the particle surface and the diffusion of products into the bulk solution, thereby improving the overall leaching rate.

[0038] The reaction time range (60~480 min) is set because: a 60 min reaction is suitable for situations with extremely high material activity, simple target metal occurrence states, or more aggressive reaction conditions, aiming to pursue rapid processing capacity and equipment turnover rate. A reaction time of up to 480 min, on the other hand, ensures the processing of complex materials, the achievement of sufficient leaching under mild conditions, or the guarantee that the reaction reaches complete equilibrium, thus helping to maximize the recovery rate of valuable metals.

[0039] In some embodiments of the present invention, the ratio of the sulfiding agent to the total mass of cobalt and manganese in the first leachate in step S2 is (1.45~3):1; In some embodiments of the present invention, in step S3, the mass ratio of the first leaching residue, the acidic leaching agent, and the reducing agent is 1:(0.09-0.18):(0.002-0.05).

[0040] In some embodiments of the present invention, the temperature of the precipitation reaction in step S2 is 20~70°C and the reaction time is 60~480 min.

[0041] The reaction temperature (20~70℃) is set as follows: Setting the temperature to 20℃ (close to room temperature) is mainly to reduce energy consumption and operating costs, and is suitable for generating phases that are thermodynamically easy to precipitate at low temperatures, such as oxalates, or for situations where high crystal particle size requirements are not required and complete precipitation is the primary goal. Setting the temperature to 70℃ is to accelerate the ion diffusion and nucleation process of the precipitation reaction, promote the formation of more stable and easier-to-filter coarse crystals (such as carbonates or hydroxides), and reduce the inclusion of impurity ions, thereby improving product purity.

[0042] The reaction time (60~480 min) is set because: setting the reaction time to 60 min ensures that the reaction system reaches sufficient supersaturation and completes the main nucleation and crystal growth processes, avoiding incomplete precipitation or the formation of difficult-to-filter fine colloids due to insufficient reaction time. Extending the upper limit to 480 min is to meet the needs of certain slow precipitation reactions or strict control of crystal growth, allowing sufficient time for crystal maturation, thereby obtaining a precipitated product with uniform particle size, low impurity content, and excellent filtration and washing performance.

[0043] In some embodiments of the present invention, the solid-liquid ratio of the acid leaching reaction in step S3 is 1:(3-10), the reaction temperature is 30~90℃, the reaction time is 40~240min, and the stirring speed is 300~600rpm.

[0044] The solid-liquid ratio (1:(3-10)) is set because: a solid-liquid ratio of 1:3 is the minimum requirement to ensure the formation of an effective stirring slurry. It provides sufficient liquid medium to dissolve the target metal ions, maintain the acidity of the system, and prevent uneven mixing, local overheating, or viscosity caused by excessive solid content. Setting the upper limit to 1:10 significantly increases the absolute amount of leaching agent, which not only helps to increase the reaction driving force and accelerate the leaching rate, but also helps to maintain a low impurity concentration in the later stages of the reaction, thereby suppressing certain side reactions. However, an excessively high liquid-solid ratio will dilute the concentration of valuable metals in the leachate, increase the volume of subsequent liquid-solid separation and the energy consumption of solution evaporation and concentration, and increase the consumption of fresh acid and water.

[0045] The reaction temperature (30~90℃) is set because: 30℃ is close to room temperature, suitable for highly chemically reactive amorphous hydroxide materials, or for energy-saving leaching under specific conditions. Although the reaction rate is slower, it effectively reduces acid mist volatilization and equipment corrosion. Raising the temperature to 90℃ significantly accelerates the ion diffusion process and chemical reaction rate, which is crucial for dissolving the more difficult-to-dissolve components after crystalline transformation or shortening the production cycle. This temperature range avoids the complexity and high cost of using an autoclave due to excessively high temperatures (e.g., >100℃).

[0046] The reaction time (40~240 min) is set because: 40 min is suitable for the rapid reaction stage of highly reactive materials under optimized conditions, at which point most of the metal has dissolved, and further extending the reaction time has limited effect on improving the leaching rate; pursuing shorter processing times can improve equipment utilization and production throughput. However, for materials with complex compositions or containing sparingly soluble phases, it is necessary to extend the reaction time to 240 min or even longer to ensure that the reaction reaches or approaches equilibrium, achieving full recovery of valuable metals.

[0047] The stirring speed (300~600 rpm) is set because 300 rpm is generally the minimum effective stirring intensity to ensure uniform suspension of solid particles, prevent sedimentation, and maintain basic solid-liquid contact. This is suitable for slurries that are not sensitive to shear or have low viscosity. Increasing the speed to 600 rpm can significantly enhance the renewal of the reaction interface and mass transfer, reduce the boundary layer thickness, thereby overcoming the diffusion control step and accelerating the overall leaching rate, which is especially beneficial for systems with fine particles or requiring rapid reactions.

[0048] In some embodiments of the invention, the predetermined number of regenerations is at least three.

[0049] In some embodiments of the present invention, in step S3, the total leaching rate of cobalt and manganese in the leachate is ≥99%.

[0050] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. Example 1

[0051] This embodiment describes a method for selective leaching of crude cobalt hydroxide, comprising the following steps: 1. Crude cobalt hydroxide and ammonium chloride, after passing through a 200-mesh sieve, are mixed with water at a mass ratio of 1:5.5:5 to form a leaching system. Sodium hexametaphosphate is added while heating to 90°C and stirring. The stirring speed is 450 rpm and the reaction time is 240 min. 2. After the reaction is completed, solid-liquid separation is performed to obtain the first leachate and the first leachate residue. Samples are taken to analyze the content of elements such as cobalt, manganese, nickel, aluminum, calcium, copper, iron, magnesium, and zinc in the leachate. 3. Add sodium sulfide to the first leachate to precipitate cobalt and manganese as sulfides. The precipitation reaction is carried out at 50°C with a stirring speed of 450 rpm for 120 min. The mass ratio of sodium sulfide added to cobalt and manganese in the first leachate is 1.63:1. After the reaction, solid-liquid separation is performed. The metal sulfide 1 precipitate is washed three times with water and dried at 60°C to obtain metal sulfide 1. 4. Analyze the ammonium chloride content of the demetallization waste liquid, return it to step 1 with the first leaching residue, and mix it again with fresh crude cobalt hydroxide, water and sodium hexametaphosphate. The crude cobalt hydroxide, ammonium chloride and water are added with ammonium chloride at a mass ratio of 1:5.5:5. The reaction is carried out at a constant temperature of 90℃ for 240 minutes. After the reaction is completed, filter it while hot to obtain the second leaching liquid and the second leaching residue. 5. Sample and analyze the cobalt and manganese content in the second leachate. Sodium sulfide was added to the second leachate at a mass ratio of 1.63:1 to the amount of sodium sulfide added. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 2. 6. Sampling and analyzing the ammonium chloride content in the demetallization waste liquid, adding ammonium chloride, and returning it to step 1 with the second leaching residue, mixing it again with new crude cobalt hydroxide, water and sodium hexametaphosphate, wherein the mass ratio of crude cobalt hydroxide, ammonium chloride and water is 1:5.5:5, and reacting at a constant temperature of 90℃ for 240 min. After the reaction is completed, filter while hot to obtain the third leaching solution and the third leaching residue. 7. Sample and analyze the cobalt and manganese content in the third leachate. Sodium sulfide was added to the third leachate at a mass ratio of 1.63:1 to the cobalt and manganese in the second leachate. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 3. 8. Sampling and analyzing the ammonium chloride content in the demetallization waste liquid, adding ammonium chloride, and returning it to step 1 with the third leaching residue, mixing it again with new crude cobalt hydroxide, water and sodium hexametaphosphate, wherein the mass ratio of crude cobalt hydroxide, ammonium chloride and water is 1:5.5:5, and reacting at a constant temperature of 90℃ for 240 min. After the reaction is completed, filter while hot to obtain the fourth leaching solution and the fourth leaching residue. 9. Sample and analyze the cobalt and manganese content in the fourth leaching solution. Sodium sulfide was added to the fourth leaching solution at a mass ratio of 1.63:1 to the cobalt and manganese in the second leaching solution. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 4. 10. Sampling and analyzing the ammonium chloride content in the demetallization waste liquid, adding ammonium chloride, returning it to the system with the fourth leaching residue, and mixing it again with new crude cobalt hydroxide, water and sodium hexametaphosphate, wherein the mass ratio of crude cobalt hydroxide, ammonium chloride and water is 1:5.5:5, and reacting at a constant temperature of 90℃ for 240 min. After the reaction is completed, filter while hot to obtain the fifth leaching solution and the fifth leaching residue. 11. Sample and analyze the cobalt and manganese content in the fifth leaching solution. Sodium sulfide was added to the fifth leaching solution at a mass ratio of 1.63:1 to the cobalt and manganese in the second leaching solution. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 5. 12. Mix the fifth leaching residue and water at a liquid-solid ratio of 1:6 to form a slurry. Then add sulfuric acid as an acid leaching agent and ammonium sulfite as a reducing agent. The mass ratio of the fifth leaching residue to sulfuric acid to ammonium sulfite is 1:0.18:0.04 for acid leaching reaction. The temperature is 50℃, the time is 120 min, and the stirring speed is 450 rpm. 13. After the reaction is complete, solid-liquid separation is performed to obtain acidic leachate and a small amount of final residue (yield less than 5%).

[0052] In summary, after five cycles of ammonium salt leaching and acid leaching treatment, the total leaching rate of cobalt in the crude cobalt hydroxide reached 99.61%, and the total leaching rate of manganese reached 99.12%. Example 2

[0053] This embodiment describes a method for selective leaching of crude cobalt hydroxide, comprising the following steps: 1. Crude cobalt hydroxide and ammonium chloride, after passing through a 200-mesh sieve, are mixed with water at a mass ratio of 1:2:4 to form a leaching system. Sodium hexametaphosphate is added under the condition of heating to 90℃ and stirring. The stirring speed is 450 rpm and the reaction time is 240 min. 2. After the reaction is completed, solid-liquid separation is performed to obtain the first leachate and the first leachate residue. Samples are taken to analyze the content of elements such as cobalt, manganese, nickel, aluminum, calcium, copper, iron, magnesium, and zinc in the leachate. 3. Add sodium sulfide to the first leachate to precipitate cobalt and manganese as sulfides. The precipitation reaction is carried out at 50°C with a stirring speed of 450 rpm for 120 min. The mass ratio of sodium sulfide added to cobalt and manganese in the first leachate is 1.45:1. After the reaction, solid-liquid separation is performed. The metal sulfide 1 precipitate is washed with water three times and dried at 60°C to obtain metal sulfide 1. 4. Analyze the ammonium chloride content of the demetallization waste liquid, return it to step 1 with the first leaching residue, and mix it again with new crude cobalt hydroxide, water and sodium hexametaphosphate. The crude cobalt hydroxide, ammonium chloride and water are added in a mass ratio of 1:2:4. The mixture is reacted at a constant temperature of 90℃ for 240 minutes. After the reaction is completed, it is filtered while hot to obtain the second leaching liquid and the second leaching residue. 5. Sample and analyze the cobalt and manganese content in the second leachate. Sodium sulfide was added to the second leachate at a mass ratio of 1.45:1 to the amount of sodium sulfide added. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 2. 6. Sampling and analyzing the ammonium chloride content in the demetallization waste liquid, adding ammonium chloride, and returning it to step 1 with the second leaching residue, mixing it again with new crude cobalt hydroxide, water and sodium hexametaphosphate, wherein the mass ratio of crude cobalt hydroxide, ammonium chloride and water is 1:2:4, and reacting at a constant temperature of 90℃ for 240 min. After the reaction is completed, filter while hot to obtain the third leaching solution and the third leaching residue. 7. Sample and analyze the cobalt and manganese content in the third leachate. Sodium sulfide was added to the third leachate at a mass ratio of 1.45:1 to the cobalt and manganese in the second leachate. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 3. 8. Sampling and analyzing the ammonium chloride content in the demetallization waste liquid, adding ammonium chloride, and returning it to step 1 with the third leaching residue, mixing it again with new crude cobalt hydroxide, water and sodium hexametaphosphate, wherein the mass ratio of crude cobalt hydroxide, ammonium chloride and water is 1:2:4, and reacting at a constant temperature of 90℃ for 240 min. After the reaction is completed, filter while hot to obtain the fourth leaching solution and the fourth leaching residue. 9. Sample and analyze the cobalt and manganese content in the fourth leaching solution. Sodium sulfide was added to the fourth leaching solution at a mass ratio of 1.45:1 to the cobalt and manganese in the second leaching solution. The reaction was carried out at room temperature for 120 min with a stirring speed of 450 rpm. After the reaction was completed, solid-liquid separation was performed. The metal sulfide precipitate was washed with water three times and dried at 60℃ to obtain metal sulfide 4. 10. Mix the fourth leaching residue and water at a liquid-solid ratio of 1:5 to form a slurry, then add sulfuric acid as an acid leaching agent and ammonium sulfite as a reducing agent. The fifth leaching residue: sulfuric acid: ammonium sulfite mass ratio is 1:0.15:0.05 for acid leaching reaction, with a temperature of 50℃, a time of 120 min, and a stirring speed of 450 rpm. 11. After the reaction is complete, solid-liquid separation is performed to obtain acidic leachate and a small amount of final residue (yield less than 5%).

[0054] In summary, after four cycles of ammonium salt leaching and acid leaching, the total cobalt leaching rate in the crude cobalt hydroxide reached 99.50%, and the total manganese leaching rate reached 99.14%.

[0055] Comparative Example 1 This comparative example describes a method for selective leaching of crude cobalt hydroxide, comprising the following steps: 1. Crude cobalt hydroxide and ammonium chloride that have passed through a 200-mesh sieve are mixed with water at a mass ratio of 1:5.5:5 to form a leaching system. The system is heated to 90°C and stirred at a stirring speed of 450 rpm for 120 min. 2. After the reaction is completed, solid-liquid separation is performed to obtain the first leachate and the first leachate residue. The content of elements such as cobalt, manganese, nickel, aluminum, calcium, copper, iron, magnesium, and zinc in the leachate is analyzed. 3. Mix the first leaching residue and water at a liquid-solid ratio of 1:5 to form a slurry, then add sulfuric acid as an acid leaching agent and ammonium sulfite as a reducing agent. The mass ratio of the first leaching residue to sulfuric acid to ammonium sulfite is 1:1.16:0.12. Carry out an acid leaching reaction at a temperature of 50℃ for 120 minutes and a stirring speed of 450 rpm. 4. After the reaction is complete, solid-liquid separation is performed to obtain acidic leachate and a small amount of final residue (yield less than 5%). 5. Sampling and analysis of the content of elements such as cobalt, manganese, nickel, aluminum, calcium, copper, iron, magnesium, and zinc in the first leachate and acid leaching solution.

[0056] In summary, after one ammonia leaching and acid leaching treatment, the cobalt leaching rate in crude cobalt hydroxide was 99.39%, and the manganese leaching rate was 99.28%.

[0057] Leaching rate test method: In this experiment, the precise content of metal elements in the raw materials and leachate was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The analyzed items were: Co, Mn, Ni, Al, Ca, Cu, Fe, Mg, and Zn.

[0058] The leaching rate is calculated as follows: The leaching rate of raw material metal (M) is calculated based on the weight of metal elements in the filtrate.

[0059] M (%) = (C2*V2*100) / (W1*X1) (1) In formula (1): W1 - Weight of the raw material sample, in grams; X1 - The mass percentage of the metallic element (M) in the raw material sample; V2 - Volume of filtrate, in liters (L); The concentration of metal (M) ions in the C2-filtrate is expressed in g / L.

[0060] The total leaching rate is the sum of the leaching rates from the ammonium leaching reaction stage and the acidic leaching reaction stage.

[0061] Table 1 shows the content of each element in the crude cobalt hydroxide raw material of Examples 1-2 and Comparative Example 1 of the present invention; Table 2 shows the content of each element in the leachate obtained after the leaching process of the crude cobalt hydroxide raw material in Example 1 of the present invention; Table 3 shows the content of each element in the leachate obtained after the leaching process of the crude cobalt hydroxide raw material in Example 2 of the present invention; Table 4 shows the content of each element in the leachate obtained after the leaching process of the crude cobalt hydroxide raw material in Comparative Example 1 of the present invention; Table 5 shows the content of each element in the mixed sample of metal sulfides 1-5 obtained from the leachate in Examples 1-2 of the present invention; Table 6 shows the proportion of ammonium sulfate in the recovered liquid obtained after sulfidation precipitation of the leachate in Example 1 of the present invention; Table 7 shows the proportion of ammonium sulfate in the recovered liquid obtained after sulfidation precipitation of the leachate in Example 2 of the present invention.

[0062] Table 1 Composition of Crude Cobalt Hydroxide Raw Material Table 2 Elemental content analysis of leachate in Example 1 Table 3 Elemental content analysis of leachate in Example 2 Table 4 Elemental content analysis of leachate in Comparative Example 1 Table 5 Elemental Analysis of Metal Sulfides Table 6. Percentage of ammonium sulfate content in the recovered solution in Example 1 Table 7. Percentage of ammonium chloride content in the recovered liquid in Example 2 The "leaching-regeneration-leaching" recycling system used in Examples 1-2 achieved a total cobalt and manganese leaching rate of 99%, similar to that obtained by the single-treatment method in Comparative Example 1. This recycling system uses sulfidation precipitation of the leachate to produce regenerated ammonium leaching agent, which is then recycled. After 4-5 cycles, the total cobalt and manganese leaching rate remains above 99%, demonstrating significant value in resource utilization and environmental protection. In terms of resource utilization, it significantly reduces the consumption of ammonium leaching agent, lowers production costs, and improves resource efficiency. In terms of environmental protection, it effectively reduces wastewater treatment volume, alleviates wastewater treatment pressure, and lowers the potential pollution risk to the environment. This recycling system provides an efficient, environmentally friendly, and sustainable method for the selective leaching of crude cobalt hydroxide, with broad prospects and significant promotional value in practical production applications.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for selective leaching of crude cobalt hydroxide, characterized in that, Includes the following steps: S1. Crude cobalt hydroxide, ammonium leaching agent and water are mixed and active additives are added to carry out ammonium leaching reaction. After the reaction is completed, solid-liquid separation is carried out to obtain the first leaching solution and the first leaching residue. S2. Add a sulfiding agent to the first leachate to carry out a precipitation reaction. After the reaction is completed, perform solid-liquid separation to obtain metal sulfides and demetallized waste liquid. S3. Mix the first leaching residue with water to form a slurry, then add acid leaching agent and reducing agent to carry out an acid leaching reaction. After the reaction is completed, perform solid-liquid separation to obtain a leaching solution and final residue rich in cobalt and manganese. The method further includes a cyclic leaching step: the demetallized waste liquid in step S2 is used as a regenerated ammonium leaching agent and reused in step S1 to react the first leaching residue obtained in step S3 with new crude cobalt hydroxide for ammonium leaching; and steps S1 to S2 are repeated until the regenerated ammonium leaching agent reaches the predetermined number of regenerations.

2. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S1, the crude cobalt hydroxide is crushed and then passed through a 100-200 mesh sieve; The crude cobalt hydroxide contains 15-60% cobalt by mass.

3. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S1, the ammonium leaching agent includes at least one of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, urea, and other solutions containing ammonium ions. And / or, in step S1, the active additive is selected from at least one of sodium hexametaphosphate, sodium tripolyphosphate, sulfate salt, TW-20 and disodium ethylenediaminetetraacetate; And / or, in step S2, the sulfiding agent is selected from at least one of sodium sulfide, ammonium sulfide, barium sulfide and calcium sulfide; And / or, in step S3, the acidic leaching agent is selected from at least one of sulfuric acid, hydrochloric acid, nitric acid and citric acid, and the reducing agent is selected from at least one of ammonium sulfite, sodium sulfite, sodium bisulfite and ferrous sulfate.

4. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S1, the mass ratio of the crude cobalt hydroxide, ammonium leaching agent, and water is 1:(2~8):(3.5~9); And / or, in step S1, the mass ratio of the crude cobalt hydroxide to the active additive is 1:(0.001-0.01).

5. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S1, the temperature of the ammonium salt leaching reaction is 30~120℃, the stirring speed is 300~600rpm, and the reaction time is 60~480min.

6. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S2, the ratio of the total mass of the sulfiding agent to the total mass of cobalt and manganese in the first leachate is (1.45~3):1; And / or, in step S3, the mass ratio of the first leaching residue, the acidic leaching agent, and the reducing agent is 1:(0.09-0.18):(0.002-0.05).

7. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S2, the precipitation reaction temperature is 20~70℃ and the reaction time is 60~480min.

8. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S3, the solid-liquid ratio of the acid leaching reaction is 1:(3-10), the reaction temperature is 30~90℃, the reaction time is 40~240min, and the stirring speed is 300~600rpm.

9. The method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, The predetermined number of regenerations is at least 3 times.

10. A method for selective leaching of crude cobalt hydroxide according to claim 1, characterized in that, In step S3, the total leaching rate of cobalt and manganese in the leachate is ≥99%.

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