Method for deeply and selectively separating MnO from Ni-Co-MnO-G series mixture

Abstract

The invention discloses a method for deeply and selectively separating MnO from a Ni-Co-MnO-G series mixture, and belongs to the technical field of resource utilization of solid wastes of lithium ion batteries. The method comprises the following steps: dissolving acid, water and a reducing agent to obtain an acid leachate; the method comprises the following steps: mixing Ni-Co-MnO-G series mixtures, grinding and sieving the Ni-Co-MnO-G series mixtures to obtain fine powder, adding the fine powder into an acid leaching solution for leaching, and finally carrying out solid-liquid separation and washing to realize separation of MnO. According to the method, the MnO in the Ni-Co-MnO-G system is selectively leached through the acid leaching solution, complete leaching of the MnO is achieved, meanwhile, leaching of Ni and Co is avoided to the maximum extent, meanwhile, a by-product MnOOH is eliminated in the low-concentration acid leaching process of the MnO, and deep selective leaching of Mn is achieved.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization technology of lithium-ion battery solid waste, specifically relating to a method for deep selective separation of MnO from a Ni-Co-MnO-G mixture. Background Technology

[0002] Ni and Co, as key strategic metals, are widely used in lithium-ion batteries, high-temperature alloys, and corrosion-resistant materials. my country's dependence on imports for both metals exceeds 90%. To achieve sustainable resource recycling and safeguard national strategic security, the recycling of Ni and Co is imperative. Currently, cutting-edge research on the recycling of cathode materials from retired lithium-ion batteries mainly focuses on selective lithium extraction. After selectively leaching Li from the cathode material using a carbothermal reduction-carbonization leaching coupled process, the remaining leaching residue is primarily treated with wet leaching to extract all valuable metal ions into the solution system. Then, the valuable metals are separated and recovered using a traditional stepwise precipitation method. The vast majority of Ni and Co in the leaching residue exist in alloy form. Converting the alloy back to metal ions using traditional acid leaching methods is undoubtedly a waste of resources. Furthermore, the treatment of waste acid and tail gas from traditional acid leaching has consistently hindered the further application of this method.

[0003] The Ni-Co-MnO-G system mixture is characterized by small particle size, high mixing degree, and tight adhesion, making it impossible to separate the components using traditional physical methods such as crushing, flotation, and gravity / magnetic separation. Previous studies attempting to separate the Ni-Co alloy using solvent refining and the graphite using selective ablation methods failed due to interference from MnO. Therefore, prioritizing the removal of MnO is crucial for the successful separation of the components in this system.

[0004] Currently, there is no research on the selective separation of valuable metals in the leaching residue after selective lithium extraction via carbothermal reduction coupled with carbonization and water leaching of retired lithium-ion battery cathode materials. According to literature from other fields such as mineral processing, selective leaching of MnO generally uses concentrated hot NH4Cl solution. The basic principle is to use the large amount of HCl decomposed from concentrated hot NH4Cl as an acidic leaching agent and NH3 as a complexing agent to achieve selective leaching and complexation separation of Mn. In the Ni-Co-MnO-G system, Ni and Co, as active metals, can also be leached into their corresponding ions and enter the solution phase. If the concentration of acid in the leaching agent is reduced, MnO in a humid environment will be oxidized by O2 to MnOOH, which is difficult to react with acid. This not only causes Mn contamination in the leaching residue system but also significantly reduces the Mn recovery rate. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this invention provides a method for the deep selective separation of MnO from a Ni-Co-MnO-G mixture. Generally, after selective lithium extraction using carbothermal reduction coupled with carbonization and water leaching of retired ternary lithium-ion battery cathode materials, the resulting leaching residue is a mixture of Ni-Co alloy, MnO, and graphite bonded together, i.e., a Ni-Co-MnO-G mixture. This invention targets the aforementioned Ni-Co-MnO-G mixture by preparing an acidic leaching solution using a non-oxidizing strong acid, a reducing agent, and water in a specific ratio. This solution is then mixed with the aforementioned Ni-Co-MnO-G mixture in a suitable ratio and thoroughly leached. The reaction of MnO with the acidic leaching solution yields MnO. 2+ Upon entering the solution, due to the unique acidic leaching solution and leaching process of this invention, the dissolution rates of Ni, Co, and MnO show significant differences, with only a small amount of Ni and Co dissolving into Ni. 2+ and Co 2+ Upon entering the solution, graphite does not react with the acidic leachate at all, and the intermediate product MnOOH is removed, achieving deep selective separation of MnO. This invention treats secondary waste generated from lithium-ion battery cathode materials, not only achieving efficient separation of the valuable metal Mn in the mixture system but also simplifying this system, which is beneficial for the resource-based recycling of secondary waste generated from retired lithium-ion batteries.

[0006] This invention provides a method for highly selectively separating MnO from a Ni-Co-MnO-G mixture, comprising the following steps: (1) Dissolve the acid, water and reducing agent to obtain an acidic leachate; (2) Grind and sieve the Ni-Co-MnO-G mixture to obtain fine powder, then add the fine powder to an acidic leaching solution for leaching, and finally perform solid-liquid separation and washing to achieve the separation of MnO.

[0007] Preferably, the acid is sulfuric acid or hydrochloric acid; the reducing agent is H2O2 or a soluble sulfite.

[0008] Soluble sulfites are Na2SO3 or K2SO3 Preferably, the pH value of the acidic leachate is 0.03-1.24, and the concentration of the reducing agent in the acidic leachate is 0.10-0.59 mol / L.

[0009] Preferably, the Ni-Co-MnO-G mixture is a leaching residue containing Ni-Co alloy, MnO and graphite obtained after selective lithium extraction by carbothermal reduction coupled carbonization water leaching of retired lithium-ion battery cathode materials.

[0010] The cathode material of the retired lithium-ion battery is lithium nickel cobalt manganese oxide (NCM), or a mixture thereof with one or more cathode materials selected from lithium nickel oxide (LNO), lithium cobalt oxide (LCO), and lithium manganese oxide (LMO).

[0011] Preferably, the solid-liquid ratio of the fine powder to the acidic leachate is 10-50 g / L.

[0012] Preferably, the leaching temperature is 20~90 °C and the leaching time is 2~15 min.

[0013] This invention achieves selective leaching of MnO in the Ni-Co-MnO-G system by controlling the type and amount of acid and reducing agent in the acidic leachate, as well as controlling the leaching temperature and time to create differences in the dissolution rates of Ni, Co, and MnO. The byproduct MnOOH generated simultaneously in the solution is reduced to MnO under the action of the reducing agent and then leached out, thereby achieving deep selective recovery of Mn.

[0014] The technical solution provided by this invention has the following beneficial effects: This invention uses acidic leaching solution to selectively leach MnO in the Ni-Co-MnO-G system, achieving complete leaching of MnO while minimizing the leaching of Ni and Co, and simultaneously eliminating the byproduct MnOOH during the low-concentration acid leaching process, thus achieving deep selective leaching of Mn. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for the deep selective separation of MnO from a Ni-Co-MnO-G mixture. Detailed Implementation

[0016] Example 1 A method for highly selective separation of MnO from Ni-Co-MnO-G mixtures (see...) Figure 1 The specific steps are as follows: (1) Take 0.093 mol HCl, 0.059 mol H2O2 and 86 mL deionized water, mix them thoroughly to obtain 100 mL acidic leachate with a pH of 0.03.

[0017] (2) 5.00 g of Ni-Co-MnO-G mixture (Ni-Co-MnO-G is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. Then, it was added to 100 mL of acidic leaching solution and leached for 15 min at room temperature (20 °C). After vacuum filtration and washing the filter residue three times with deionized water, 3.44 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH, and graphite in the filter residue were 61.82 wt.%, 24.79 wt.%, 0.17 wt.%, and 13.22 wt.%, respectively. The filtrate was diluted to 500 mL, and ICP analysis showed that Ni... 2+ Co 2+ and Mn 2+ The concentrations were 0.024 g / L, 0.013 g / L, and 2.393 g / L, respectively.

[0018] Example 2 A method for highly selective separation of MnO from Ni-Co-MnO-G mixtures (see...) Figure 1 The specific steps are as follows: (1) Take 0.058 mol HCl, 0.049 mol H2O2 and 90 mL deionized water, mix them thoroughly to obtain 100 mL acidic leachate with a pH of 0.24.

[0019] (2) 5.00 g of mixture (Ni-Co-MnO-G system is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. It was added to 100 mL of acidic leaching solution and leached at 90 °C for 5 min. After vacuum filtration and washing the filter residue three times with deionized water, 3.41 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH and graphite in the filter residue were 61.77 wt.%, 24.86 wt.%, 0.05 wt.% and 13.32 wt.%, respectively. The filtrate was diluted to 500 mL and analyzed by ICP to determine the Ni content. 2+ Co 2+ and Mn2+ The concentrations were 0.057 g / L, 0.020 g / L, and 2.399 g / L, respectively.

[0020] Increasing the leaching temperature can significantly shorten the time required to leach MnO. While reducing the amount of HCl used and increasing the pH of the solution will promote the hydrolysis of MnO to MnOOH, the extent of this hydrolysis is mainly limited by the dissolved oxygen content in the acidic leachate. In this embodiment, improvements to the leaching time, temperature, and composition of the acidic leachate effectively reduce the leaching losses of Ni and Co, thereby improving the purity of Mn in the leachate.

[0021] Example 3 A method for highly selective separation of MnO from Ni-Co-MnO-G mixtures (see...) Figure 1 The specific steps are as follows: (1) Take 0.058 mol HCl, 0.098 mol H2O2 and 485 mL deionized water, mix them thoroughly to obtain 500 mL acidic leachate with a pH of 0.93.

[0022] (2) 5.00 g of mixture (Ni-Co-MnO-G system is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. It was added to 500 mL of acidic leaching solution and leached at 90 °C for 12 min. After vacuum filtration and washing the filter residue three times with deionized water, 3.39 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH and graphite in the filter residue were 61.86 wt.%, 24.70 wt.%, 0.03 wt.% and 13.41 wt.%, respectively. The filtrate was diluted to 1000 mL and analyzed by ICP to determine the Ni content. 2+ Co 2+ and Mn 2+ The concentrations were 0.041 g / L, 0.022 g / L, and 1.200 g / L, respectively.

[0023] By increasing the deionized water content in the acidic leachate, the concentrations of HCl and H₂O₂ in the leachate are reduced, resulting in a significant extension of the leaching time. Furthermore, the amount of MnOOH generated is related to the dissolved oxygen content in the acidic leachate, and in this embodiment, the amount of MnOOH generated is significantly increased. To ensure sufficient leaching of MnOOH, the amount of H₂O₂ added is increased accordingly. Simultaneously, due to the increased volume of the leachate, the filtration time is extended, and the residence time of Ni and Co in the leachate is also prolonged, leading to a corresponding increase in the leaching loss of Ni and Co.

[0024] Example 4 A method for highly selective separation of MnO from Ni-Co-MnO-G mixtures (see...) Figure 1 The specific steps are as follows: (1) Take 0.037 mol H2SO4, 0.049 mol Na2SO3 and 98 mL deionized water, dissolve them completely to obtain 100 mL of acidic leachate with a pH of 0.13.

[0025] (2) 5.00 g of mixture (Ni-Co-MnO-G system is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. It was added to 100 mL of acidic leaching solution and leached at 60 °C for 10 min. After vacuum filtration and washing the filter residue three times with deionized water, 3.42 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH and graphite in the filter residue were 61.83 wt.%, 24.81 wt.%, 0.08 wt.% and 13.28 wt.%, respectively. The filtrate was diluted to 500 mL and analyzed by ICP to determine the Ni content. 2+ Co 2+ and Mn 2+ The concentrations were 0.043 g / L, 0.019 g / L, and 2.398 g / L, respectively.

[0026] Example 5 A method for highly selective separation of MnO from Ni-Co-MnO-G mixtures (see...) Figure 1 The specific steps are as follows: (1) Take 0.006 mol HCl, 0.025 mol H2O2 and 97 mL deionized water, mix them thoroughly to obtain 100 mL acidic leachate with a pH of 1.24.

[0027] (2) 5.00 g of Ni-Co-MnO-G mixture (Ni-Co-MnO-G is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material by carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. Then, it was added to 100 mL of acidic leaching solution and leached at 40 °C for 2 min. After vacuum filtration and washing the filter residue three times with deionized water, 3.43 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH, and graphite in the filter residue were 61.83 wt.%, 24.79 wt.%, 0.13 wt.%, and 13.25 wt.%, respectively. The filtrate was diluted to 500 mL, and ICP analysis showed that Ni... 2+ Co 2+ and Mn 2+ The concentrations were 0.032 g / L, 0.016 g / L, and 2.396 g / L, respectively.

[0028] Comparative Example 1 A method for highly selective separation of MnO from Ni-Co-MnO-G mixtures (see...) Figure 1 The specific steps are as follows: (1) Take 0.093 mol HCl and 92 mL deionized water, mix them thoroughly to obtain 100 mL acidic leachate with a pH of 0.03.

[0029] (2) 5.00 g of Ni-Co-MnO-G mixture (Ni-Co-MnO-G is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. Then, it was added to 100 mL of acidic leaching solution and leached for 15 min at room temperature (20 °C). After vacuum filtration and washing the filter residue three times with deionized water, 3.48 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH, and graphite in the filter residue were 61.26 wt.%, 24.59 wt.%, 1.11 wt.%, and 13.04 wt.%, respectively. The filtrate was diluted to 500 mL, and ICP analysis showed that Ni... 2+Co 2+ and Mn 2+ The concentrations were 0.005 g / L, 0.004 g / L, and 2.353 g / L, respectively.

[0030] Comparative Example 2 A method for highly selectively separating MnO from a Ni-Co-MnO-G mixture, comprising the following steps: (1) Take 0.093 mol HCl, 0.009 mol H2O2 and 91 mL deionized water, mix them thoroughly to obtain 100 mL acidic leachate with a pH of 0.03.

[0031] (2) 5.00 g of Ni-Co-MnO-G mixture (Ni-Co-MnO-G is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. Then, it was added to 100 mL of acidic leaching solution and leached for 15 min at room temperature (20 °C). After vacuum filtration and washing the filter residue three times with deionized water, 3.48 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH, and graphite in the filter residue were 61.31 wt.%, 24.61 wt.%, 1.02 wt.%, and 13.06 wt.%, respectively. The filtrate was diluted to 500 mL, and ICP analysis showed that Ni... 2+ Co 2+ and Mn 2+ The concentrations were 0.006 g / L, 0.004 g / L, and 2.357 g / L, respectively.

[0032] Comparative Example 3 A method for highly selectively separating MnO from a Ni-Co-MnO-G mixture, comprising the following steps: (1) Take 0.093 mol HCl, 0.490 mol H2O2 and 42 mL deionized water, mix them thoroughly to obtain 100 mL acidic leachate with a pH of 0.03.

[0033] (2) 5.00 g of Ni-Co-MnO-G mixture (Ni-Co-MnO-G is a leaching residue containing Ni-Co alloy, MnO and graphite obtained from the selective lithium extraction of retired nickel cobalt manganese oxide lithium-ion battery cathode material through carbothermal reduction coupled carbonization water leaching; wherein the mass contents of Ni, Co, MnO and graphite are 42.74 wt.%, 17.17 wt.%, 31.00 wt.% and 9.09 wt.%, respectively) was thoroughly ground in an agate mortar and passed through a 200-mesh sieve. Then, it was added to 100 mL of acidic leaching solution and leached for 15 min at room temperature (20 °C). After vacuum filtration and washing the filter residue three times with deionized water, 3.48 g of filter residue was obtained. ICP analysis showed that the mass fractions of NiO, CoO, MnOOH, and graphite in the filter residue were 45.93 wt.%, 35.15 wt.%, 0.00 wt.%, and 18.92 wt.%, respectively. The filtrate was diluted to 500 mL, and ICP analysis showed that Ni... 2+ Co 2+ and Mn 2+ The concentrations were 2.067 g / L, 1.645 g / L, and 2.401 g / L, respectively.

[0034] Comparative Example 4 The method for deep selective separation of MnO from a Ni-Co-MnO-G mixture described in this comparative example differs from that in Example 1 only in that the leaching temperature was 100 °C and the leaching time was 20 min. 3.36 g of filter residue was obtained. ICP analysis showed that the mass fractions of Ni, Co, MnOOH, and graphite in the filter residue were 61.82 wt.%, 24.61 wt.%, 0.03 wt.%, and 13.54 wt.%, respectively. The filtrate was diluted to 500 mL, and ICP analysis revealed that Ni... 2+ Co 2+ and Mn 2+ The concentrations were 0.124 g / L, 0.065 g / L, and 2.400 g / L, respectively.

[0035] Currently, there is no research on the selective separation of valuable metals from the leaching residue obtained after selective lithium extraction via carbothermal reduction coupled with carbonization and water leaching of cathode materials from retired lithium-ion batteries. The industry standard practice is to add strong acid to the leaching residue after lithium extraction to fully dissolve the valuable metals, and then separate them through a stepwise precipitation process. While the core principle of this invention is also acid leaching, by controlling the acid concentration, Ni and Co are minimized from entering the solution system, significantly reducing acid consumption. Simultaneously, by introducing a reducing agent, the byproduct MnOOH in the system is reduced and leached, achieving deep selective leaching of Mn, which has potential for future industrial applications.

[0036] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for the deep and selective separation of MnO from a Ni-Co-MnO-G mixture, characterized by: The method comprises the following steps: (1) dissolving acid, water and a reducing agent to obtain an acidic leaching solution; (2) grinding and sieving a Ni-Co-MnO-G mixture to obtain fine powder, then adding the fine powder into the acidic leaching solution for leaching, and finally performing solid-liquid separation and washing to realize separation of MnO.

2. The process for the deep selective separation of MnO from a Ni-Co-MnO-G mixture according to claim 1, characterized in that: The acid is sulfuric acid or hydrochloric acid; and the reducing agent is H2O2 or soluble sulfite.

3. The process for the deep selective separation of MnO from a Ni-Co-MnO-G mixture according to claim 1, characterized in that: The pH value of the acidic leaching solution is 0.03-1.24, and the concentration of the reducing agent in the acidic leaching solution is 0.10-0.59 mol / L.

4. The process for the deep selective separation of MnO from a Ni-Co-MnO-G mixture according to claim 1, characterized in that: The Ni-Co-MnO-G mixture is an immersion residue obtained after retired lithium ion battery positive electrode material is subjected to carbon thermal reduction coupling carbonization water immersion selective lithium extraction, and the immersion residue contains Ni-Co alloy, MnO and graphite.

5. The process for the deep selective separation of MnO from a Ni-Co-MnO-G mixture according to claim 1, characterized in that: The solid-liquid ratio of the fine powder to the acidic leaching solution is 10-50 g / L.

6. The process for the deep selective separation of MnO from a Ni-Co-MnO-G mixture according to claim 1, characterized in that: The leaching temperature is 20-90 DEG C, and the leaching time is 2-15 min.

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