Method for recovering valuable metals from lithium ion battery cathode materials

Abstract

The application discloses a method for recycling valuable metals in lithium ion battery positive materials, and belongs to the technical field of resource recycling. The method comprises the following steps: mixing the lithium ion battery positive material, a zinc-containing sulfidizing agent and a reducing agent, and then roasting; controlling the volume fraction of oxygen in the roasting atmosphere to be lower than 5%; then water leaching the roasting product; and finally performing solid-liquid separation to obtain leaching liquor and leaching residue, wherein the leaching liquor is a lithium-containing solution, and the leaching residue contains cobalt and / or nickel sulfides. The application can simultaneously process high-value metals such as cobalt and nickel in the battery, does not introduce new impurities to reduce the burden of subsequent separation and impurity removal, realizes the effect of short-flow lithium extraction, and the obtained sulfides can be used as high-quality nickel matte raw materials for nickel smelting enterprises to enter the smelting system for separation and recovery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling, and more particularly relates to a method for recycling valuable metals in a positive electrode material of a lithium ion battery. BACKGROUND

[0002] Lithium ion batteries are widely used in electric vehicles, communications, electronic devices and other fields due to their long cycle life, large capacity, light weight and other characteristics. With the rapid increase in the use of lithium ion batteries, it is estimated that the number of waste lithium ion batteries will reach a peak in 2025. The waste lithium ion batteries contain toxic electrolytes and organic separators, which can cause irreversible damage to the soil and water quality. In addition, they contain a large amount of strategic and critical metals Li (2-3%), Co (5-30%), Ni (0.02-10%), and Cu (7-17%), and if not recycled, it will cause great waste of resources. Therefore, developing a green and efficient recycling process for valuable elements in waste lithium ion batteries not only helps to solve the problem of environmental pollution, but also can alleviate the global energy metal resource shortage. Pyrometallurgy has strong raw material adaptability, short process, high recovery rate of cobalt, nickel and copper, large processing capacity, but the slag phase lithium grade is low and difficult to recover; hydrometallurgy has low investment, flexible production, good comprehensive recovery effect of metals, high product purity, but long process, complex process, high cost of waste water and waste residue treatment, and the recovery of lithium is usually placed in the last step, resulting in a large amount of lithium loss. The sulfidation method combines the advantages of pyrometallurgy and hydrometallurgy. The existing sulfidation recovery method mainly has the following two types: selective recovery of lithium by sulfate and selective recovery of lithium by sulfide.

[0003] After searching, the patent application file with the Chinese patent application number 201710500482.0 and the application publication date of September 29, 2017 discloses a method for recovering lithium from waste lithium batteries. The method mixes and calcines the positive electrode powder of the waste lithium battery with a sulfidation agent, and then performs solid-liquid separation to obtain a lithium-containing aqueous solution. However, the sulfidation agent used in this process enters the solution on the one hand, which will adversely affect the subsequent separation and purification of lithium, and on the other hand, the sulfide ore used as a sulfur source introduces new metal impurities, which is not conducive to the recovery of Co and the purification of the product.

[0004] The patent application file with Chinese patent application number 202110552481.7 and publication date of August 20, 2021 discloses a method for recovering lithium from waste lithium ion battery positive electrode material. The method mixes waste lithium ion battery positive electrode material with (NH4)2SO4 for sulfuric acid roasting, destroys the layered structure of the positive electrode material to make lithium ions smoothly escape, and then performs water leaching on the roasting product to obtain a lithium-rich leaching solution and a transition metal oxide residue phase. After impurity removal and purification, ammonium carbonate is added to the leaching solution, lithium is recovered in the form of Li2CO3 precipitation at a certain temperature, and the lithium precipitation solution is evaporated and crystallized to prepare (NH4)2SO4, realizing the recovery of lithium from waste lithium ion battery positive electrode material and the recycling of (NH4)2SO4. At the same time, the lithium-containing residue can be recycled in the water leaching stage. To avoid the decomposition of ammonium carbonate, the reaction temperature is relatively low, the lithium precipitation time is relatively long, and the lithium precipitation is not complete. Although the remaining lithium will be brought into ammonium sulfate and the residual liquid returns to the closed-loop system, the low lithium precipitation efficiency will increase the cost.

[0005] The patent application file with Chinese patent application number 202310395906.7 and publication date of July 11, 2023 discloses a method for selectively recovering lithium from lithium batteries. The patent method is as follows: way one, roasting a mixture of lithium battery pole powder, sulfur ammonium and carbon powder, and then leaching the roasting product to obtain a lithium leaching solution; or, way two, roasting a mixture of lithium battery pole powder and sulfur ammonium, and then adding an alkali solution to the leaching product to remove impurities and obtain a lithium leaching solution; or, way three, roasting a mixture of lithium battery pole powder, sulfur ammonium and carbon powder, and then adding an alkali solution to the leaching product to remove impurities and obtain a lithium leaching solution. This process uses sulfur ammonium as a sulfidizing agent, which not only causes corrosion to electrical equipment, but also generates a large amount of ammonia-containing wastewater.

[0006] Therefore, a new method for recovering valuable metals from lithium ion battery positive electrode material is proposed to improve the recovery process cycle and efficiently recover valuable metals, which is a problem that needs to be solved at present. SUMMARY

[0007] 1. Problem to be solved

[0008] To solve the problems of existing lithium ion battery positive electrode material sulfidation method, such as high degree of equipment corrosion, generation of a large amount of waste gas, and difficulty in separating introduced impurities, the present invention provides a method for recovering valuable metals from lithium ion battery positive electrode material. By optimizing the formula of the recovery system, high-value metals such as cobalt and nickel in the battery can be processed simultaneously, new impurities are not introduced to reduce the burden of subsequent separation and impurity removal, the effect of short process lithium extraction is achieved, and the sulfide obtained can be used as high-quality nickel matte raw material for nickel smelting enterprises to enter their smelting system for separation and recovery.

[0009] 2. Technical solution

[0010] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0011] The method for recovering valuable metals from lithium-containing residues comprises the following steps:

[0012] S1, roasting process:

[0013] The lithium ion battery positive electrode material, the zinc-containing sulfidizing agent and the reducing agent are mixed and roasted, the volume fraction of oxygen in the roasting atmosphere is controlled to be less than 5%, and a roasted product and zinc oxide dust are obtained.

[0014] Since cobalt and nickel, which are the most valuable in the positive electrode material, belong to sulfur-loving elements, they are extremely easy to form water-insoluble sulfides (Co3S4, CoS, NiS) with negative divalent sulfur, and lithium in the positive electrode powder is more oxygen-loving, which can form water-soluble sulfates in the sulfidation process. Thus, the separation of lithium and cobalt and nickel is realized.

[0015] The reducing agent has two functions, one is to maintain the sulfur combined with cobalt and nickel as negative divalent sulfur, and at the same time, when the sulfidizing agent added is a sulfate, it can also reduce the sulfate radical to negative divalent sulfur to combine with cobalt and nickel; the other is to reduce the metal zinc in the sulfidizing agent to make it become zinc vapor and volatilize into flue gas, without introducing new metal impurities.

[0016] The purpose of controlling the oxygen content is to maintain a relatively weak reducing atmosphere, which can promote the zinc vapor generated by reduction to be oxidized to zinc oxide in the flue gas for recovery on the one hand, and make lithium and the like into sulfates, which is beneficial to subsequent leaching and recovery on the other hand; if the oxygen content is too low, it is easy to cause the consumption of the reducing agent to increase, and at the same time, it is difficult for the zinc vapor to change into safe and stable zinc oxide dust, if it is liquefied or even solidified in the flue gas system, it is extremely easy to corrode and block the equipment.

[0017] S2, lithium extraction process:

[0018] The roasted product of step S1 is water leached, and solid-liquid separation is performed to obtain a leaching solution and a leaching residue, wherein the leaching solution is a lithium-containing solution, and the leaching residue contains sulfides of cobalt and / or nickel.

[0019] Further, in step S1, the lithium ion battery positive electrode material can be a positive electrode powder obtained by disassembling at least one of lithium cobaltate batteries, lithium nickelate batteries, lithium manganate batteries, lithium nickel-manganese batteries, lithium nickel-cobalt batteries, lithium nickel-cobalt-manganese ternary batteries, and lithium nickel-cobalt-aluminum ternary batteries, but is not limited thereto, and is preferably at least one of lithium cobaltate batteries, lithium nickelate batteries, and lithium nickel-cobalt-manganese ternary batteries.

[0020] Further, in step S1, the zinc-containing sulfidizing agent is at least one of ZnS, zinc blende, zinc sulfate, and basic zinc sulfate, and is preferably at least one of ZnS, zinc blende, and anhydrous zinc sulfate.

[0021] Further, in step S1, the reducing agent is a hydrogen or carbon-containing reducing agent, including but not limited to at least one of H2, graphite, carbon powder, coke, and coal powder.

[0022] Further, in step S1, the mass ratio of the reducing agent to the zinc-containing sulfidizing agent is (0.5-1.5):1.

[0023] Further, in step S1, the mass ratio of the zinc-containing sulfidizing agent to the lithium ion battery cathode material is (1-3):1, preferably (1.5-2.5):1.

[0024] Further, in step S1, the calcination temperature is 600-1250°C, preferably 1000-1200°C; the calcination time is 0.5-3h, preferably 1.5-2h. The effects of the calcination temperature are as follows: (1) it affects the reaction rate, thereby affecting the production efficiency; the higher the temperature, the faster the reaction rate and the better the production efficiency, but too high a temperature will greatly increase the energy consumption; (2) it affects the state of zinc; zinc is a low-melting-point and easily-volatile metal (melting point 420°C, boiling point 907°C), and when the temperature exceeds 800°C, liquid zinc begins to violently evaporate into zinc vapor.

[0025] Further, in step S1, the control means for controlling the oxygen volume fraction in the calcination atmosphere to be less than 5% is adjusting the flow rates of oxygen and / or air and inert gas nitrogen of the aeration device.

[0026] Further, in step S2, the water immersion temperature is 10-80°C, the leaching time is 2min-2h, and the liquid-solid ratio is (3-50):1mL / g. Preferably, the temperature is 40-60°C, the time is 10-30min, and the liquid-solid ratio is (10-20):1mL / g.

[0027] Further, in step S2, the concentrations of impurities Co, Ni, Zn, and Mn in the leaching solution are all less than 0.1mg / L, and the leaching recovery rate of lithium is >98%.

[0028] Further, in step S2, the main components in the leaching residue are Co content 15-55wt%, Ni content 10-63wt%, and S content 20-35wt%, and the sulfidization recovery rates of cobalt and nickel are both >95%.

[0029] The method for recovering valuable metals from the lithium-containing residue can be applied to recover the positive electrode material of a lithium ion battery. The method can solve the problems of existing sulfurization methods for waste lithium ion batteries, such as high corrosion degree of equipment, generation of a large amount of waste gas, and difficulty in separating introduced impurities, and can simultaneously process high-value metals such as cobalt and nickel in the battery. Since the sulfides of lithium, cobalt and nickel have a wider property difference band than oxides, they are easier to achieve deep separation. In view of this, the present application proposes a new method for selectively extracting lithium by applying the sulfurization method of the positive electrode material of the waste lithium ion battery based on the ore-forming principle of sulfide ore. Specifically, the positive electrode material of the waste lithium battery is used as raw material, the zinc-containing sulfidation agent, the positive electrode material of the waste lithium battery and the reducing agent are mixed and roasted according to a certain proportion, and then the roasted residue is water leached to obtain a lithium-containing solution with low impurity content. The high-value metals such as nickel and cobalt form sulfides that are insoluble in water and can be sent to a nickel smelting plant as matte products. Zinc is further oxidized to zinc oxide by zinc vapor, and enters the flue dust. Lithium, cobalt and nickel can be separated by one-step reduction sulfidation roasting, realizing the effect of short-flow lithium extraction. At the same time, the sulfide obtained can be used as high-quality nickel ice as raw material into the smelting system of the nickel smelting enterprise for separation and recovery.

[0030] 3. Beneficial effects

[0031] Compared with the prior art, the beneficial effects of the present application are:

[0032] (1) Good selectivity

[0033] Based on the significant difference in the affinity of lithium and cobalt, nickel for sulfur, the affinity of cobalt and nickel for sulfur is stronger in the reduction sulfidation roasting process, forming sulfides that are insoluble in water, and the recovery rate of cobalt and nickel sulfide is greater than 95%. For lithium, it is more oxygenophilic, and finally changes into soluble lithium sulfate or lithium oxide. After water leaching, the concentration of impurities such as cobalt, nickel and manganese in the obtained lithium-containing leaching solution is less than 0.1 mg / L, and the leaching rate of lithium is more than 98%. For zinc, the zinc-containing compounds are first volatilized into flue gas in the form of zinc vapor in the reducing atmosphere during the reduction sulfidation roasting process, but will continue to be oxidized to zinc oxide by the flue gas containing carbon dioxide and exist stably in the flue dust, and will not enter the cobalt and nickel sulfide products and the lithium-containing leaching solution, without affecting the purity of the products.

[0034] (2) Low-cost and easily accessible zinc-containing compounds

[0035] The present application can use the widely existing sphalerite in nature or zinc sulfate as the sulfidation agent, and the raw material is low in price and easy to obtain. The raw material is the positive electrode material obtained after disassembling the waste lithium ion battery. In addition, the sulfide is a zinc-containing compound, which is widely available in addition to chemical products, and can also use the widely existing zinc sulfide concentrate in nature.

[0036] (3) Wide subsequent use of the obtained products

[0037] The cobalt-nickel sulfide product obtained by this method is a high-quality "nickel matte," which can be used as a premium intermediate material in nickel smelting enterprises. It can be incorporated into the "nickel matte" blowing process, minimizing the cost of developing independent wet separation technologies for cobalt and nickel, and enabling the co-processing of lithium-containing waste batteries with existing typical heavy metals. For lithium, the Li-containing solution obtained after simple sulfide roasting-water leaching has low impurity ion concentrations; the concentrations of Ni, Co, Al, Si, and Mn are all below 0.1 ppm. No subsequent complex separation processes are required, and it can be used as a high-quality lithium-containing raw material. After simple impurity removal, concentration, and crystallization, high-purity Li₂CO₃ can be produced by introducing CO₂ or adding potassium or sodium carbonates. Attached Figure Description

[0038] Figure 1 This is a process flow diagram of the recycling method of the present invention;

[0039] Figure 2 The XRD pattern of the leaching residue in Example 15;

[0040] Figure 3 This is a SEM image of the leaching residue from Example 15. Detailed Implementation

[0041] The present invention will be further described below with reference to specific embodiments.

[0042] Examples 1-26

[0043] like Figure 1 As shown, the method for recovering valuable metals from lithium-containing slag includes the following steps:

[0044] S1. Calcination process:

[0045] Waste battery cathode materials from different sources were mixed with different sulfiding agents and different reducing agents according to the amounts shown in Table 1, and then calcined. The oxygen content in the atmosphere was maintained, with the remainder being N2. The calcination temperature and calcination time are shown in Table 2. The calcination products and zinc oxide dust were obtained.

[0046] S2, Lithium extraction process:

[0047] The roasted product from step S1 was leached in water at a temperature of 60°C for 2 hours, with a liquid-to-solid ratio of 20:1 mL / g. Solid-liquid separation was then performed to obtain leachate, leachate residue, and zinc oxide dust. The leachate was a lithium-containing solution with cobalt, nickel, zinc, and manganese contents all below 0.1 ppm. The leachate residue contained cobalt and / or nickel sulfides. The recovery rates of lithium, nickel, and cobalt are shown in Table 2. Figure 2 and Figure 3 The images shown are XRD and SEM images of the leaching residue from Example 15.

[0048] It should be noted that, for nickel cobalt manganese lithium sulfidation roasting, there will be no manganese in the solution, mainly because: although manganese is also oxygen, but the oxide or sulfide of manganese is insoluble in water, even if the sulfidation process generated manganese sulfate, but in water leaching manganese will hydrolysis into manganese hydroxide precipitate into the leaching residue, realize the separation with lithium.

[0049] Table 1 lithium ion battery anode material, the type of zinc-containing sulfidation agent and reducing agent, the amount of addition

[0050]

[0051]

[0052] Table 2 roasting parameters and valuable metal recovery rate

[0053]

[0054]

[0055] It is worth mentioning that the reaction conditions of the above examples are the best reaction conditions, the reaction conditions within the scope of the claims can also synthesize the complexes of the present application, in order to avoid repetition, here will not be illustrated; in addition, the skilled person in the art according to the general formula of the complex of the present application and the relevant solvents, catalysts and other reagents listed can reproduce the present application, since too many examples are listed, here selects a few representative examples, enough to prove that the complex of the present application has excellent luminescent efficiency and low oxygen quenching rate, so here will not be repeated.

Claims

1. A method for recovering valuable metals from lithium-ion battery cathode materials, characterized in that: The positive electrode material of lithium-ion battery, zinc-containing sulfide and reducing agent are mixed and calcined, and the oxygen volume fraction in the calcination atmosphere is controlled to be less than 5%. The calcined product is then leached with water, and finally solid-liquid separation is performed to obtain leaching solution and leaching residue. The zinc-containing sulfide is at least one of ZnS, zinc sphalerite, zinc sulfate and basic zinc sulfate. The leaching solution is a lithium-containing solution. The leaching residue contains cobalt and / or nickel sulfides.

2. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The positive electrode material of lithium-ion batteries is the positive electrode material of waste lithium-ion batteries, including positive electrode powder obtained by dismantling at least one of lithium cobalt oxide batteries, lithium nickel oxide batteries, lithium manganese oxide batteries, lithium nickel manganese batteries, lithium nickel cobalt batteries, ternary lithium nickel cobalt manganese batteries, and ternary lithium nickel cobalt aluminum batteries.

3. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The reducing agent is a reducing agent containing hydrogen or carbon.

4. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The mass ratio of reducing agent to zinc-containing sulfiding agent is (0.5~1.5):

1.

5. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The mass ratio of zinc-containing sulfide agent to lithium-ion battery cathode material is (1~3):

1.

6. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 5, characterized in that: The mass ratio of zinc-containing sulfiding agent to lithium-ion battery cathode material is (1.5~2.5):

1.

7. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The roasting temperature is 600~1250℃; the roasting time is 0.5~3 h.

8. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 7, characterized in that: The roasting temperature is 1000~1200℃, and the roasting time is 1.5~2 h.

9. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The roasting atmosphere also contains inert gases.

10. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 1, characterized in that: The water immersion temperature is 10~80℃, the immersion time is 2min~2h, and the liquid-to-solid ratio is (3~50):1mL / g.

11. The method for recovering valuable metals from lithium-ion battery cathode materials according to claim 10, characterized in that: The water immersion temperature is 40~60℃, the immersion time is 10~30min, and the liquid-to-solid ratio is (10~20):1mL / g.

12. The method for recovering valuable metals from lithium-ion battery cathode materials according to any one of claims 1 to 11, characterized in that: The concentrations of impurities Co, Ni, Zn, and Mn in the leachate are all less than 0.1 mg / L, and the lithium leaching recovery rate is >98%. The main components of the leaching residue are Co content of 15~55wt%, Ni content of 10~63wt%, and S content of 20~35wt%, and the cobalt and nickel sulfide recovery rates are both >95%.

Images