Method for efficiently refining cobalt nickel hydroxide intermediate product

Abstract

The invention discloses a method for efficiently refining a cobalt nickel hydroxide intermediate product, and relates to the technical field of hydrometallurgy, the method comprises the following steps: step S1, alkaline pressurized oxidation; s2, carrying out solid-liquid separation and washing; s3, normal-pressure acid leaching is conducted, specifically, the oxidized cobalt nickel hydroxide intermediate product in the step S2 is subjected to normal-pressure leaching with sulfuric acid, and finally solid-liquid separation is conducted to obtain Ni / Co-containing leaching liquid and Mn-containing leaching residues; s4, neutralization and impurity removal, wherein the oxidized cobalt nickel hydroxide intermediate product obtained in the step S2 is added into the leachate obtained in the step S3 to serve as a neutralizer and an oxidizing agent; and S5, SO2 is subjected to low-temperature pressurization reduction leaching. According to the method, the alkaline pressurized oxidation and normal-pressure acid leaching processes of the nickel-cobalt hydroxide intermediate product are adopted, a series of problems of long subsequent manganese separation process, large wastewater discharge and the like caused by synchronous leaching of nickel, cobalt and manganese in the leaching process of the nickel-cobalt hydroxide intermediate product are solved, and favorable conditions are created for simplifying the refining process of the nickel-cobalt hydroxide intermediate product and reducing the production cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy, and particularly relates to a method for efficient refining of nickel-cobalt hydroxide intermediate product. BACKGROUND

[0002] In recent years, with the rapid development of electric vehicles, the demand for key raw materials of ternary power batteries, such as nickel, cobalt and manganese, has rapidly increased, leading to a growing shortage of nickel-cobalt mineral resources. At the same time, with the maturity of high-pressure acid leaching technology of laterite nickel ore, the production cost is gradually reduced, and the production line of laterite nickel ore high-pressure acid leaching wet metallurgy is rapidly expanding. Nickel-cobalt hydroxide intermediate product is an important intermediate product of the high-pressure acid leaching process of laterite nickel ore. During storage and transportation, manganese is partially oxidized to MnO2 which is insoluble in sulfuric acid.

[0003] The current nickel-cobalt hydroxide intermediate product refining mainly includes atmospheric reduction leaching method and direct conventional leaching method. The atmospheric reduction leaching method uses hydrogen peroxide, sodium sulfite or sodium sulfide as a reducing agent for atmospheric leaching. After leaching, compressed air or hydrogen peroxide is used to oxidize the residual Fe 2+ oxidized Fe 3+ , and sodium carbonate, sodium hydroxide or calcium carbonate is used to neutralize and remove iron. This method makes Ni, Co and Mn all enter the solution, the process is long, ≥6 wt % hydrogen peroxide is an explosive hazardous product, the utilization rate of oxygen and compressed air as oxidizing agent is low, and the introduction of sodium and calcium ions causes pipeline crystallization, extraction emulsification, and H2S and SO2 generated by sulfide reducing agent, which has prominent safety and environmental protection problems; the direct conventional leaching method does not add reducing agent, and the Mn leaching rate is still about 50 %. Subsequent extraction separation is needed, the process flow is complex, the metal direct recovery rate is low, and the dispersion of manganese elements is not conducive to the recovery rate. The addition of oxidizing agent and neutralizing agent has the same problems as the atmospheric reduction leaching method.

[0004] A Chinese patent with publication number CN118026297A discloses an oxidative leaching method and a preparation method of a sulfate salt, and the sulfate salt. The oxidative leaching method comprises the following steps: dispersing a nickel-cobalt-manganese-containing hydroxide intermediate product in water to obtain a slurry; adding an oxidizing agent to the slurry to perform oxidation treatment, so that divalent manganese in the slurry is oxidized to manganese higher than divalent manganese; performing acid leaching treatment on the slurry after the oxidation treatment, and then performing solid-liquid separation to obtain a leaching solution and a leaching residue. Since the manganese in the intermediate product is oxidized to manganese higher than divalent manganese before leaching, most of the manganese is retained in the residue phase during the leaching process, thereby simplifying the subsequent nickel-cobalt extraction and separation process of the leaching solution. However, the leaching solution obtained after the method still contains a high concentration of manganese ions. The reason may be that the oxidation of manganese in the hydroxide intermediate product in the normal pressure aqueous solution is not complete, so that the manganese in the intermediate product exists in the form of acid-soluble oxides such as MnO, Mn3O4 and Mn2O3, instead of being completely converted into acid-insoluble MnO2, resulting in that part of the manganese is dissolved into the leaching solution during the acid leaching process, thereby increasing the cost of the subsequent nickel-cobalt extraction and increasing the difficulty of manganese separation. SUMMARY

[0005] The purpose of the present application is to provide a method for efficiently refining a nickel-cobalt hydroxide intermediate product, in order to solve the problems raised in the above background.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solution: a method for efficiently refining a nickel-cobalt hydroxide intermediate product, comprising the following steps: Step S1, alkaline pressure oxidation: after the nickel-cobalt hydroxide intermediate product is dispersed and slurried, it is reacted under the conditions of oxygen concentration ≥ 90 vol%, temperature 60-120℃, pressure 200-400 kPa, and pH 7.5-9.5 for 2-6 h, so that Mn(OH)2 in it is oxidized to MnO2, and the manganese oxidation rate is ≥ 95%, to obtain an oxidized ore slurry; Step S2, solid-liquid separation and washing: the oxidized ore slurry produced in step S1 is filtered, and the filter residue is washed to obtain the oxidized nickel-cobalt hydroxide intermediate product, and the filtrate and washing liquid are returned to the slurring process in step S1 for recycling; Step S3, normal pressure acid leaching: the oxidized nickel-cobalt hydroxide intermediate product in step S2 is leached with sulfuric acid under normal pressure, and the leaching is carried out under the conditions of temperature 60-90℃ and end point pH value 1-3 for 2-4 hours, and finally solid-liquid separation is performed to obtain a leaching solution containing Ni / Co and a leaching residue containing Mn, and the Ni leaching rate is ≥ 99%, the Co leaching rate is ≥ 99%, and the Mn leaching rate is ≥ 95%; Step S4, neutralization and impurity removal: the oxidized nickel-cobalt hydroxide intermediate product in step S2 is added to the leaching solution in step S3 as a neutralizing agent and an oxidizing agent, and the temperature is controlled at 60-90℃, the end point pH is controlled at 4-5, and the time is controlled at 2-6 h, so that Fe 2+ is oxidized to Fe 3+The precipitate was then hydrolyzed and filtered to obtain a Ni / Co solution after iron removal. Step S5, SO2 low-temperature pressure reduction leaching: The Mn-containing leaching residue from step S3 is washed and filtered, and the resulting manganese slag is pulped. Then, SO2 gas is introduced, and the reaction is carried out for 2-6 hours under the conditions of temperature 10-80℃, pressure 100-300 kPa, and pH 1.5-3.0, so that MnO2 is reduced and leached to Mn. 2＋ The manganese leaching rate is ≥95%, the SO2 utilization rate is ≥90%, and the manganese sulfate solution is obtained by filtration.

[0007] Furthermore, the chemical composition of the nickel-cobalt hydroxide intermediate is as follows: Ni 35-42wt%, Co 3-6wt%, Mn 4-8wt%, Fe 0.05-0.1wt%, Mg 1-2wt%.

[0008] Furthermore, in step S1, sodium hydroxide is added during the initial pulping to adjust the pH value, and the alkali in the system is returned for recycling through the filtrate and washing liquid in step S2.

[0009] Furthermore, in step S4, the Ni / Co-containing leachate is sent for extraction to further remove impurities and separate nickel and cobalt, producing battery-grade nickel sulfate and battery-grade cobalt sulfate solutions.

[0010] Furthermore, in step S4, the filter residue obtained after filtration is washed and then returned to step S1 for pulping and oxidation.

[0011] Furthermore, in step S5, the SO2 gas concentration is ≥90 vol.

[0012] Furthermore, in step S5, the washing water from the washing and filtration of the Mn-containing leaching residue is returned to step S3 for leaching.

[0013] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. This invention employs alkaline pressure oxidation and atmospheric pressure acid leaching processes for nickel-cobalt hydroxide intermediates, which solves a series of problems such as the simultaneous leaching of nickel, cobalt and manganese during the leaching process of nickel-cobalt hydroxide intermediates, resulting in a long subsequent manganese separation process and a large amount of wastewater discharge. This creates favorable conditions for simplifying the refining process of nickel-cobalt hydroxide intermediates and reducing production costs. 2. The conventional leaching process after oxidation of nickel-cobalt hydroxide intermediates does not require the addition of a reducing agent, and manganese is separated simultaneously with the leaching of nickel and cobalt. This simplifies the leaching process and creates favorable conditions for efficient separation and purification of nickel, cobalt, and manganese, as well as for increasing the direct recovery rate. 3. Neutralization and impurity removal of nickel-cobalt leaching solution only requires the use of oxidized nickel-cobalt hydroxide intermediate as a neutralizing agent, without the need to add external neutralizing agents or oxidizing agents. This avoids the introduction of other impurities that could affect the extraction system and product quality, as well as the safety hazards caused by the addition of hazardous chemicals. The production process is safe, energy-saving, and environmentally friendly. 4. The pressurized low-temperature reduction leaching process for sulfur dioxide in leaching residue solves the safety hazards and environmental risks associated with reducing agents such as hydrogen peroxide and hydrogen sulfide, as well as the introduction of reducing agent impurities such as sulfites. The leaching rate is greater than 95%, and the utilization rate of sulfur dioxide is over 90%. At the same time, leaching under low-temperature conditions can ensure a high concentration of manganese ions in the leachate. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

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

[0016] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0017] Example 1: Step S1, alkaline pressure oxidation: The composition of the nickel-cobalt hydroxide intermediate is nickel 40.7wt%, cobalt 5.2wt%, manganese 4.6wt%, iron 0.08wt%, and magnesium 1.3wt%; after the nickel-cobalt hydroxide intermediate is dispersed and slurried, it is pumped into a pressure oxidation reactor, oxygen with a concentration of 99% is introduced, the temperature is controlled at 90℃, the pressure is 350Kpa, the pH value of the slurry is 8.5, and alkaline pressure oxidation is carried out for 4 hours. The manganese oxidation rate is 95.8%, and no alkali is consumed during the oxidation process; Step S2, solid-liquid separation and washing: The oxidized slurry produced in step S1 is filtered, and the filter residue is washed to obtain oxidized nickel-cobalt hydroxide intermediate. The filtrate and washing liquid are returned to the pulping process in step S1 for recycling, so as to realize the recycling of alkali solution. Step S3, Atmospheric Pressure Acid Leaching: The oxidized nickel-cobalt hydroxide intermediate from Step S2 is pulped and pumped into a leaching tank. The temperature is controlled at 80℃, and the final pH value is 1.5. Atmospheric pressure leaching is carried out for 3.5 hours. After leaching, liquid-solid separation is performed. The liquid is a nickel-cobalt sulfate solution, and the solid is washed with water to obtain manganese concentrate. In this step, the nickel leaching rate is 99.6%, the cobalt leaching rate is 99.2%, and the manganese slag inflow rate is 95.8%. Step S4, Neutralization and Impurity Removal: The oxidized nickel-cobalt hydroxide intermediate from Step S2 is added to the leachate from Step S3 as both a neutralizing agent and an oxidizing agent. The temperature is controlled at 80°C, and the final pH value is 4.8. Neutralization and impurity removal are carried out for 5 hours to allow Fe... 2+ Oxidized to Fe 3+ After hydrolysis and precipitation, and removal of impurities, liquid-solid separation is performed. The liquid is a purified nickel-cobalt sulfate solution. The filter residue is washed and returned to step S1 to be mixed with a new nickel-cobalt hydroxide intermediate for oxidation. The leaching solution containing Ni / Co is sent for extraction to further remove impurities and separate nickel and cobalt, producing battery-grade nickel sulfate and battery-grade cobalt sulfate solutions. After this step of impurity removal, the residual iron in the liquid is reduced to 18.3 mg / L. Step S5, SO2 low-temperature pressure reduction leaching: The Mn-containing leaching residue from step S3 is washed and filtered to obtain wash water and manganese slag. The wash water is returned to step S3 for leaching, and the manganese slag is pulped and pumped into a pressure leaching reactor. 98% sulfur dioxide gas is introduced, and the temperature is controlled at 40°C and the pressure at 200 kPa for 5 hours of low-temperature acidic sulfur dioxide pressure reduction leaching to reduce MnO2 to Mn. 2＋ The leaching slurry undergoes liquid-solid separation, and the leachate is a manganese sulfate solution. The leaching residue is washed and then sent to a slag storage. In this step, the manganese leaching rate is 98.1%, the sulfur dioxide utilization rate is 94.8%, and the manganese ion concentration in the leachate is 98.3 g / L.

[0018] Example 2: In this example, the composition of the nickel-cobalt hydroxide intermediate is 38.2 wt% nickel, 4.7 wt% cobalt, 7.1 wt% manganese, 0.07 wt% iron, and 1.6 wt% magnesium; The same alkaline pressure oxidation conditions as in Example 1 were used for treatment. After alkaline pressure oxidation, the oxidation rate of manganese in the nickel-cobalt hydroxide intermediate was 95.3%. The same leaching conditions as in Example 1 were used, and the leaching rates were 99.7% for nickel, 99.4% for cobalt, and 95.5% for manganese in the slag.

[0019] It is evident that the present invention can adapt to nickel-cobalt hydroxide intermediates with varying component contents within a certain range.

[0020] Example 3: In this example, the composition of the nickel-cobalt hydroxide intermediate is the same as in Example 1.

[0021] After being dispersed and slurried, the intermediate nickel-cobalt hydroxide was pumped into a pressurized oxidation reactor. 99% oxygen was introduced, and the temperature was controlled at 60℃, the pressure at 300 kPa, and the pH of the slurry at 7.5. Alkaline pressurized oxidation was carried out for 6 hours. After oxidation, liquid-solid separation was performed. The liquid was returned as nickel-cobalt hydroxide slurry, and the solid was washed with water to obtain oxidized nickel-cobalt hydroxide. The manganese oxidation rate in this step was 95.1%. No alkali was consumed during the oxidation process, and the alkali solution was recycled. The same leaching conditions as in Example 1 were used, and the leaching rates were 99.2% for nickel, 99.0% for cobalt, and 95.1% for manganese in the slag.

[0022] Example 4: In this example, the composition of the nickel-cobalt hydroxide intermediate is the same as in Example 1; After the intermediate nickel-cobalt hydroxide product is dispersed and slurried, it is pumped into a pressurized oxidation reactor, and oxygen with a concentration of 99% is introduced. The temperature is controlled at 80℃, the pressure at 200 kPa, and the pH of the slurry at 8.0. Alkaline pressurized oxidation is carried out for 6 hours. After oxidation, liquid-solid separation is performed. The liquid is returned as nickel-cobalt hydroxide slurry, and the solid is washed with water to obtain oxidized nickel-cobalt hydroxide. The manganese oxidation rate in this step is 95.2%. No alkali is consumed during the oxidation process, and the alkali solution is recycled. The same leaching conditions as in Example 1 were used, and the leaching rates were 99.3% for nickel, 99.1% for cobalt, and 95.3% for manganese in the slag.

[0023] Example 5: In this example, the composition of the nickel-cobalt hydroxide intermediate is the same as in Example 1; After being dispersed and slurried, the intermediate nickel-cobalt hydroxide product was pumped into a pressurized oxidation reactor. 99% oxygen was introduced, and the temperature was controlled at 110℃, the pressure at 380 kPa, and the pH of the slurry at 9.0. Alkaline pressurized oxidation was carried out for 2 hours. After oxidation, liquid-solid separation was performed. The liquid was returned as nickel-cobalt hydroxide slurry, and the solid was washed with water to obtain oxidized nickel-cobalt hydroxide. The manganese oxidation rate in this step was 95.8%. No alkali was consumed during the oxidation process, and the alkali solution was recycled. The same leaching conditions as in Example 1 were used, and the leaching rates were 99.7% for nickel, 99.6% for cobalt, and 95.9% for manganese in the slag.

[0024] Comparative Example 1: This comparative example differs from Example 1 in that no pressure was applied during the alkaline oxidation stage of the nickel-cobalt hydroxide intermediate. After alkaline oxidation, the oxidation rate of manganese in the nickel-cobalt hydroxide intermediate was 83.3%. The same leaching conditions as in Example 1 were used, and the leaching rates were 96.4% for nickel, 95.2% for cobalt, and 82.8% for manganese in the slag.

[0025] It is evident that the oxidation rate of manganese in the nickel-cobalt hydroxide intermediate significantly decreases under non-pressurized conditions during the alkaline oxidation stage, leading to a reduced manganese slag ingress rate during the subsequent leaching process. Some manganese dissolves into the solution, making it unsuitable for the extraction and separation of nickel and cobalt and the recovery of manganese in the subsequent leaching solution.

[0026] Comparative Example 2: The difference between this comparative example and Example 1 is that the pH value of the slurry was not adjusted during the pressure oxidation stage of the nickel-cobalt hydroxide intermediate, and the oxidation rate of manganese in the nickel-cobalt hydroxide intermediate after oxidation was 87.1%. The same leaching conditions as in Example 1 were used, and the leaching rates were 97.1% for nickel, 96.5% for cobalt, and 86.8% for manganese in the slag.

[0027] It is evident that the oxidation rate of manganese in the nickel-cobalt hydroxide intermediate is insufficient when the pH value is not adjusted to alkaline during the oxidation stage. This results in insufficient manganese input rate in the subsequent leaching process, with some manganese dissolving into the solution and not being utilized for the extraction and separation of nickel and cobalt and the recovery of manganese in the subsequent leaching solution.

[0028] Comparative Example 3: The difference between this comparative example and Example 1 is that no pressure was applied and the pH value of the slurry was adjusted during the oxidation stage of the nickel-cobalt hydroxide intermediate. The oxidation rate of manganese in the oxidized nickel-cobalt hydroxide intermediate was 78.4%. The same leaching conditions as in Example 2 were used, and the leaching rates were 95.2% for nickel, 93.6% for cobalt, and 77.9% for manganese in the slag.

[0029] It is evident that during the oxidation stage, without pressurization and pH adjustment to alkaline conditions, the oxidation rate of manganese in the nickel-cobalt hydroxide intermediate is significantly insufficient, leading to a substantial decrease in the manganese slag inflow rate during the subsequent leaching process. Some manganese dissolves into the solution, making it unsuitable for the extraction and separation of nickel and cobalt and the recovery of manganese in the subsequent leaching solution.

[0030] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for efficient refining of nickel-cobalt hydroxide intermediate product, characterized by, The method comprises the following steps: Step S1, alkaline pressure oxidation: after the nickel-cobalt hydroxide intermediate product is dispersed and slurried, the Mn(OH)2 in the product is oxidized to MnO2 under the conditions of oxygen concentration ≥ 90 vol%, temperature 60-120℃, pressure 200-400 kPa, pH 7.5-9.5, and reaction time 2-6 h, so that the manganese oxidation rate is ≥ 95%, and an oxidized slurry is obtained; Step S2, solid-liquid separation and washing: the oxidized slurry obtained in step S1 is filtered, and the filter residue is washed to obtain an oxidized nickel-cobalt hydroxide intermediate product, and the filtrate and washing liquid are returned to the slurring process in step S1 for recycling; Step S3, atmospheric acid leaching: the oxidized nickel-cobalt hydroxide intermediate product in step S2 is leached with sulfuric acid under atmospheric pressure, and the leaching is carried out under the conditions of temperature 60-90℃ and final pH value 1-3 for 2-4 hours, and finally, solid-liquid separation is carried out to obtain a Ni / Co-containing leaching solution and a Mn-containing leaching residue, the Ni leaching rate is ≥ 99%, the Co leaching rate is ≥ 99%, and the Mn leaching rate is ≥ 95%; Step S4, neutralization and impurity removal: add the oxidized nickel-cobalt intermediate product of step S2 to the leaching solution of step S3 as a neutralizing agent and oxidizing agent, control the temperature at 60-90 ℃, the final pH at 4-5, and the time at 2-6 h, so that Fe 2+ is oxidized to Fe 3+ and hydrolyzed and precipitated, and after filtration, a Ni / Co solution after Fe removal is obtained; Step S5, SO2 low-temperature pressure reduction leaching: the Mn-containing leaching residue of step S3 is washed and filtered, the obtained manganese residue is slurried, then SO2 gas is introduced, and the reaction is carried out at a temperature of 10-80℃, a pressure of 100-300 kPa, a pH of 1.5-3.0, and for 2-6 h, so that MnO2 is reduced and leached into Mn 2＋ , the manganese leaching rate is ≥95%, the SO2 utilization rate is ≥90%, and a manganese sulfate solution is obtained by filtration.

2. The method for efficient refining of nickel-cobalt hydroxide intermediate product according to claim 1, characterized in that: The chemical composition of the nickel-cobalt hydroxide intermediate product is: Ni 35-42wt%, Co 3-6wt%, Mn 4-8wt%, Fe 0.05-0.1wt%, and Mg 1-2wt%.

3. The method for efficient refining of nickel-cobalt hydroxide intermediate product according to claim 1, characterized in that: In step S1, sodium hydroxide is added to adjust the pH value during the first slurring, and the alkali in the system is recycled by returning the filtrate and washing liquid in step S2.

4. The process for efficient refining of nickel-cobalt hydroxide intermediate as claimed in claim 1 wherein: In step S4, the Ni / Co-containing leaching solution is sent to extraction for further impurity removal and nickel-cobalt separation, and battery-grade nickel sulfate and battery-grade cobalt sulfate solution are obtained.

5. The process for efficient refining of nickel-cobalt hydroxide intermediate as claimed in claim 1 wherein: In step S4, the filter residue obtained after filtration is washed and returned to step S1 for slurring and oxidation.

6. The process for efficient refining of nickel-cobalt hydroxide intermediate as claimed in claim 1 wherein: In step S5, the SO2 gas concentration is ≥ 90 vol%.

7. The process for efficient refining of nickel-cobalt hydroxide intermediate as claimed in claim 1 wherein the process is characterized by: In step S5, the washing water obtained by washing the Mn-containing leaching residue after filtration is returned to step S3 for leaching.

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