Method for recycling metal in positive electrode through calcium sulfate sulfuration roasting

Abstract

The invention provides a method for recycling metal in a positive electrode by using calcium sulfate sulfating roasting. The method comprises the following steps: pretreating a mixture composed of a positive electrode material and carbon by using an alkaline solution; mixing the NCM material with calcium sulfate or gypsum slag, and then roasting; adding water into the roasted product to carry out water leaching treatment, then carrying out suction filtration to obtain a lithium sulfate solution and water leaching residues, and carrying out evaporation treatment on leachate; and drying the water leaching slag, mixing the water leaching slag with a slag former, and then smelting to obtain high-grade matte nickel and manganese-rich slag. According to the method, the recovery rate of Li can reach 97%, the recovery rate of Co can reach 95% or above, the recovery rate of Ni can reach 96% or above, and compared with an existing wet recovery process, the method has the great cost advantage.

Description

Technical Field

[0001] The invention relates to a method for recovering metal in a positive electrode, in particular to a method for recovering metal in a positive electrode by sulfation and roasting with calcium sulfate. Background Art

[0002] With the rapid development of the electric vehicle industry, the consumption of lithium-ion batteries has increased dramatically, and the average service life of lithium-ion batteries is 5-8 years, resulting in a large number of waste batteries. At the same time, environmental and resource shortage issues are becoming increasingly prominent, and the recycling of waste resources has become an important way to promote the construction of ecological civilization. x Co y Mn 1-x-y O2, commonly known as NCM, is one of the most widely used positive electrode materials for lithium-ion batteries. Although the rapid development of lithium-ion batteries has brought many conveniences to people's lives, the life cycle of batteries is relatively short. With the rapid growth of the world's population and the rapid development of the economy, a large number of waste lithium batteries have been generated, and the amount of waste has continued to grow over time. Against the background of the rapid development of the new energy vehicle industry, lithium (Li), nickel (Ni) and cobalt (Co), as the key raw materials for the positive electrode of ternary lithium batteries, are increasingly facing a shortage of resources. In response to this challenge, the present invention explores an innovative recycling method that can not only solve the problem of large-scale recycling of waste batteries, but also solve the problem of insufficient nickel ore resources. By comprehensively analyzing the importance of Li, Ni and Co in the new energy vehicle industry, we emphasize the importance of recycling these metals to promote the circular development of the industry. This method can not only effectively extract Li, Ni and Co from ternary batteries, but also provide a new way for the large-scale recycling of waste batteries. The advantage of this method is that it is not only suitable for processing small-scale samples, but more importantly, it can be expanded to large-scale production to process large amounts of battery materials. This study not only provides an effective way to solve the shortage of Ni and Co resources, but also provides strong support for the sustainable development of the new energy vehicle industry.

[0003] The preparation process of NCM is Ni x Co y Mn 1-x-y (OH)2 or NixCoy Mn 1-x-yThe CO3 precursor is mixed with a lithium source and calcined at high temperature. The preparation of low-nickel ternary materials usually adopts the method of sintering the precursor with Li2CO3 in an air atmosphere, while the high-nickel ternary materials are more often sintered with lithium hydroxide monohydrate in an oxygen atmosphere. Since the ternary materials form strong metal-oxygen bonds (Me–O bonds) in the lattice structure, the discarded ternary materials show high oxidizability, which leads to higher acid consumption and leaching temperature during metal leaching, and prolonged leaching time. Given the complexity of battery materials, combining physical and chemical processes for recycling has become a widely used method. Physical processes, including disassembly, crushing, screening, heat treatment and mechanochemical treatment, can effectively improve the metal recovery rate. Chemical processes are divided into pyrometallurgy and hydrometallurgy. Among them, pyrometallurgy is simple and efficient, while hydrometallurgy provides milder reaction conditions and stronger metal selectivity, showing a broader application prospect. At present, there are many methods for recovering valuable metals from discarded lithium batteries, among which there are mainly three methods: (1) mechanochemical treatment; (2) pyrometallurgy; (3) hydrometallurgy.

[0004] Mechanochemical method: It is an innovative recycling method that uses mechanical means, such as ultrasound or ball milling, to induce chemical reactions. The core mechanism of the mechanochemical method is to enhance the chemical activity of substances by reducing particle size, increasing specific surface area and changing particle structure, thereby promoting chemical reactions. In the recycling process of waste lithium-ion battery positive electrode materials, the mechanochemical method mainly works in two ways: first, destroying the crystal structure of the positive electrode material to improve the leaching efficiency of specific elements in the subsequent leaching process; second, promoting reactions between different substances to form soluble compounds.

[0005] Hydrometallurgy: Hydrometallurgy is a mainstream method in the field of metal recovery, and it plays a key role in the smelting process of many metals. The advantages of this technology include relatively mild reaction conditions, low tail gas emissions and high metal recovery rate. In the traditional hydrometallurgical process, key processes include leaching, separation and purification. In the leaching process, it is usually necessary to select a suitable leaching agent, such as sulfuric acid, sodium hydroxide, salt solution, etc. Depending on the selected leaching agent, there are mainly acid leaching, alkaline leaching, ammonia leaching, biological leaching and electrochemical leaching. Although there are many types of leaching agents, they are mainly divided into two categories: full leaching type and selective leaching type. In the separation and purification process, commonly used technologies include precipitation, extraction, electrolysis and adsorption.

[0006] Pyrometallurgy: Pyrometallurgy technology, as a traditional metallurgical recovery process, mainly recovers or refines valuable metals from waste lithium-ion batteries through physical or chemical transformation at high temperatures. In the early smelting process, the smelting temperature usually reached about 1000°C, and the products obtained were mostly common alloys, such as nickel-cobalt alloys, iron alloys, etc. In this high-temperature environment, lithium mainly enters the slag phase and requires subsequent treatment to recover, resulting in a relatively low lithium recovery rate and high cost. The current pyrometallurgical recovery process mainly uses the method of roasting and leaching. This process involves first adding a certain amount of substance as a roasting agent for roasting, and then leaching and separating the roasted product to obtain different metal products.

[0007] At present, the treatment process of waste lithium batteries is mainly sulfuric acid leaching, adjusting the pH value to remove impurities, extracting, separating and purifying to obtain solutions of cobalt sulfate, nickel sulfate and manganese sulfate. This method has problems such as large amount of slag, difficult waste slag treatment, high acid and alkali consumption, long process and low metal recovery rate. Summary of the invention

[0008] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for recovering lithium by sulfating, roasting and leaching with calcium sulfate, and then recovering nickel and cobalt by slag making and smelting from the lithium extraction material to make matte and smelt, aiming to reduce process complexity, reduce production costs, and improve metal recovery rate, which is conducive to large-scale production.

[0009] To achieve the above object, the technical solution provided by the method of the present invention is:

[0010] A method for recovering metal in a positive electrode by sulfating and roasting with calcium sulfate comprises the following steps:

[0011] 1) pretreating a mixture of a cathode material and a carbon source with an alkaline solution, and filtering to obtain an NCM material and an aluminum-containing filtrate;

[0012] 2) mixing the NCM material with calcium sulfate or gypsum slag in a mass ratio of 1:1.4-2, then placing the mixture in a vacuum reactor or a reactor filled with nitrogen, argon or other inert gases, and calcining the mixture at 600-800° C. to obtain a calcined product;

[0013] 3) adding water to the roasted product at a mass volume ratio of 1:5-15 g / mL for water leaching, then filtering to obtain a lithium sulfate solution and water leaching residue, and evaporating the leaching solution to complete the recovery of metal Li;

[0014] 4) Drying the water-leached slag, mixing it with a slag-forming agent in a mass ratio of 100:10-100, and then placing it in a high-temperature container for smelting to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co.

[0015] Furthermore, the alkaline solution in step 1) includes one or more of NaOH, KOH, Ca(OH)2, and ammonia water.

[0016] Furthermore, the concentration of the alkaline solution is 1-5 mol / L, and the mass volume ratio of the mixture to the alkaline solution is 1:10-100 g / mL.

[0017] Further, by mass, the components of the mixture include Ni: 15-80%, Co: 5-30%, Mn: 5-30%, Li: 2-10%, Al: 0-5%, Ca: 0-3%, Mg: 0-3%, Fe: 0-3%, Cu: 0-3%, and C: 15-20%.

[0018] Furthermore, the calcination time is 30-180 min.

[0019] Furthermore, the immersion treatment time is 1-3 hours.

[0020] Furthermore, the temperature of the immersion treatment is 20-40°C.

[0021] Furthermore, the slag-forming agent is silica (SiO2).

[0022] Furthermore, the smelting temperature is 1200-1600°C

[0023] Furthermore, the smelting time is 30-150 min.

[0024] Furthermore, the carbon source includes at least one of waste battery negative electrode materials and carbon powder.

[0025] The present invention creatively finds that pre-treating the ternary electrode material with an alkaline solution will promote the removal of Al, Cu, and Fe, reduce their influence on Li during the sulfurization roasting and impregnation steps, and thus improve the recovery rate of Li. Based on the system of the present invention, the alkaline solution should be selected from one or more of NaOH, KOH, Ca(OH)2, and ammonia water, and the concentration of the alkaline solution should be controlled to be more advantageous at 1-5 mol / L. When the concentration is lower than 1 mol / L, the impurity removal effect is poor, but too high a concentration will increase the cost.

[0026] The present invention creatively finds that calcium sulfate and NCM are used for sulfation roasting under vacuum. On the one hand, calcium sulfate provides a sulfur source for the sulfidation reaction to react with lithium ions to generate lithium sulfate that is highly soluble in water, thereby promoting the separation and extraction of lithium ions. On the other hand, the calcium ions in calcium sulfate react with C to generate calcium carbonate before lithium ions, inhibiting the combination of lithium ions with C and O to generate lithium carbonate that is slightly soluble in water, thereby further helping the lithium ions in NCM to generate substances that are highly soluble in water with sulfate ions, that is, further improving the recovery rate of lithium ions. At the same time, this also helps to reduce the water consumption of the water leaching process of lithium, as well as the energy consumption of the subsequent evaporation and drying process, greatly reducing the recovery cost. Furthermore, the most valuable sulfur element in calcium sulfate is fully utilized in the first step of the sulfidation process, and after the sulfidation is completed, the calcium element mainly exists in the form of calcium carbonate, which can be used as a slag-making agent in the subsequent slag-making and melting process. The method can make full use of the calcium element therein, so the method can fully utilize the gypsum slag, a metallurgical solid waste, to maximize the residual value of this solid waste, and is an efficient solid waste collaborative smelting technology. Based on the system of the present invention, when the mass ratio of NCM to calcium sulfate is higher than 1:2, calcium sulfate is excessive, and calcium sulfate is slightly soluble in water, which will cause a part of calcium sulfate to enter the lithium sulfate solution, affecting the recovery of lithium, while causing the waste of calcium sulfate, and even affecting the subsequent slag melting process. Therefore, in the present invention, the mass ratio of NCM to calcium sulfate is determined to be not higher than 1:2, and further, when the mass ratio of NCM to calcium sulfate is lower than 1:1.4, lithium will not be completely sulfated, and a part will exist in the form of lithium carbonate, reducing the overall solubility of lithium salts, increasing the water consumption of the water immersion process, and the energy consumption of the subsequent evaporation process, increasing additional costs. Therefore, in the present invention, the mass ratio of NCM to calcium sulfate is further preferably 1:1.4-2.

[0027] The present invention creatively finds that by mixing appropriate carbon in the calcined material, not only can calcium sulfide with sulfurization ability be prepared by reacting with calcium sulfate, but also the reaction temperature required for the sulfurization reaction can be reduced to make the sulfurization process more efficient. In addition, the presence of carbon also enhances the selectivity of sulfurization roasting, which helps to convert transition metals into water-insoluble metal sulfides. Based on the system of the present invention, when the amount of carbon added in the NCM material is insufficient, the prepared calcium sulfide is insufficient, and nickel and cobalt cannot be fully sulfurized, which will affect the subsequent recovery of nickel and cobalt. When the amount of carbon added in the NCM material is too high, the excess carbon will promote the combination of lithium and carbon oxygen to form lithium carbonate, affecting the recovery of lithium, and will also have an inhibitory effect on the sulfurization of nickel and cobalt, affecting the recovery of nickel and cobalt, and will increase additional costs. Therefore, the amount of carbon source added should meet the carbon content in the mixture of 15-20%, and more preferably 16-18%.

[0028] The present invention creatively discovered that by drying the leached slag after immersion in water and mixing it with a slag-forming agent, slag melting and recovery of Ni and Co at a high temperature of 1200-1600°C, Ni and Co can be recovered in the form of high-matte nickel, and at the same time, impurities such as calcium, magnesium, and aluminum can be allowed to enter the slag phase, achieving the effect of separating nickel and cobalt from impurity elements. The slag melting temperature is further optimized to 1400-1600°C, the smelting time is 30-150min, further optimized to 60-120min, and the slag-forming agent is silica (SiO2). The mass ratio of the dried leached slag to the slag-forming agent is 100:10-100, and more preferably 100:20-60.

[0029] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0030] (1) The present invention utilizes the carbon in the positive electrode material and the introduced carbon source, which can not only react with calcium sulfate to prepare calcium sulfide with sulfurization ability, but also make the sulfurization process more efficient by reducing the reaction temperature required for the sulfurization reaction. The presence of carbon also enhances the selectivity of sulfurization roasting, which helps to convert transition metals into water-insoluble metal sulfides, and at the same time promotes the conversion of lithium into water-soluble lithium sulfate; in addition, by introducing calcium sulfate for sulfurization roasting, on the one hand, calcium sulfate can provide a sulfur source for the sulfurization reaction to react with lithium ions to generate water-soluble lithium sulfate and thus promote the separation and extraction of lithium ions. On the other hand, the calcium ions in calcium sulfate will react with C to generate calcium carbonate before lithium ions, thereby further helping the lithium ions in NCM to generate water-soluble substances with sulfate ions, promoting the effective separation of Li from metal elements such as Co, Ni, and Mn, that is, further improving the recovery rate of lithium ions. Through the effective ratio of carbon, calcium sulfate and ternary positive electrode materials of the present invention and the sulfurization roasting reaction, the recovery rate of Li can reach 97%.

[0031] (2) The present invention achieves efficient resource recovery and utilization through the coordinated smelting of two solid wastes, waste ternary positive electrode and gypsum slag. First, in the process of treating the waste ternary positive electrode material, high-value metals such as lithium, nickel and cobalt are effectively recovered. At the same time, the sulfur element in the gypsum slag is fully utilized in the first step of the sulfidation process, and the generated sulfide promotes the separation and extraction of lithium, significantly improving the recovery rate of lithium. After the sulfidation reaction is completed, the calcium element mainly exists in the form of calcium carbonate and is used as a slag-forming agent in the subsequent slag-forming and melting process, further improving the efficiency of resource utilization. This coordinated treatment method not only maximizes the residual value of gypsum slag, a metallurgical solid waste, but also reduces the negative impact of solid waste on the environment. By combining the treatment of two solid wastes, the present invention provides an innovative and efficient solid waste coordinated smelting technology, which provides new ideas and solutions for resource recycling and environmental protection.

[0032] (3) The present invention slags and melts the lithium-extracted material after drying it, and achieves good slag-gold separation effect, which can achieve a Co recovery rate of more than 95% and a Ni recovery rate of more than 96%. It also has a great cost advantage over the existing wet recovery process.

[0033] (4) The final Ni and Co recovery products of the present invention are high-matte nickel. High-matte nickel is a highly competitive nickel-cobalt-containing industrial product that occupies an important position in modern industrial production. High-matte nickel is an excellent nickel-cobalt-containing industrial product that can be used as a raw material for electrolytic nickel and as a raw material for the positive electrode of power batteries, and has a wider range of industrial uses. The advantages of high-matte nickel include its high purity and good conductivity, which enable it to perform well in industrial applications that require high-purity materials and high-efficiency conductive properties. The excellent corrosion resistance of nickel and cobalt enables high-matte nickel to maintain its structure and performance stability in harsh chemical environments, extending the service life of equipment and materials. High-matte nickel is not only widely used in electrolytic nickel and power batteries, but also in many fields such as stainless steel, special alloys, catalysts and electronic components to meet the needs of various industries for high-performance materials. In the application of power batteries, high-matte nickel can increase the energy density of batteries, extend the cruising range of equipment such as electric vehicles, and meet the market demand for high-performance batteries. The versatility and wide application of high-matte nickel make it have a high economic value in the market, bringing significant economic benefits to production companies.

[0034] (5) The process flow involved in the present invention has a lot in common with the production lines of existing nickel ore smelting enterprises. This method helps nickel ore smelting enterprises adapt to changes in the battery industry, find new economic growth points, and provide more cost-effective recycling solutions. Traditional nickel ore smelting enterprises have economies of scale and are more likely to form large-scale operations and have competitive advantages than emerging battery recycling companies. Through large-scale recycling, these manufacturers can better utilize existing equipment and technological advantages to meet diverse market demands. In short, this method not only has advantages in terms of economy, but also helps in the recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The reaction flow chart of the present invention is DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the present invention, a specific embodiment is described as follows, wherein the calculation method for the recovery rate is the mass of the metal element (Li, Ni, Co) in the raw material / the mass of the metal element (Li, Ni, Co) in the recovered product:

[0037] Example 1

[0038] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0039] 1) Pretreating a mixture of positive and negative electrode materials and carbon powder of waste ternary batteries with a 3 mol / L NaOH solution, and obtaining NCM material and aluminum-containing filtrate after filtration, wherein the contents of metal elements and C in the mixture are Co: 14%, Ni: 27%, Mn: 17%, Li: 4%, Al: 4%, Cu: 0.03%, Fe: 0.04%, and C: 17.5%; and the mass volume ratio of the mixture to the NaOH solution is 1:30 g / ml;

[0040] 2) mixing the NCM material and calcium sulfate in a mass ratio of 1:1.6, placing the mixture in a vacuum reactor, and calcining the mixture at 700° C. for 120 minutes to obtain a calcined product;

[0041] 3) adding water to the calcined product at a mass volume ratio of 1:5 g / mL and performing an impregnation treatment at 25° C. for 2 h, then filtering to obtain an impregnation solution and a water-impregnated residue, and evaporating the leaching solution to complete the recovery of the metal Li;

[0042] 4) Dry the water-leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 2:1, and then place it in a high-temperature container and smelt it at 1600°C for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0043] It was determined that the recovery rates of Li, Co, and Ni were 98.7%, 97.2%, and 97.6%, respectively.

[0044] Example 2

[0045] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0046] 1) Pre-treating a mixture of positive and negative electrode materials and carbon powder of waste ternary batteries with a 1 mol / L NaOH solution, and filtering to obtain NCM material and aluminum-containing filtrate. The contents of metal elements and C in the mixture are Co: 14%, Ni: 26%, Mn: 16%, Li: 5%, Al: 3%, Cu: 0.03%, Fe: 0.04%, C: 17.5%; the mass volume ratio of the mixture to the NaOH solution is 1:80 g / ml;

[0047] 2) The NCM material and calcium sulfate were mixed in a mass ratio of 1:1.5, and then placed in a reactor with an air atmosphere, and calcined at 650° C. for 60 minutes to obtain a calcined product.

[0048] 3) adding water to the calcined product at a mass volume ratio of 1:10 g / mL and performing an impregnation treatment at 25° C. for 2 hours, then filtering to obtain an impregnation solution and water-impregnated residue, and evaporating the leaching solution to complete the recovery of the metallic Li.

[0049] 4) Dry the water-leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 2:1, and then place it in a high-temperature container and smelt it at 1500°C for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0050] It was determined that the recovery rates of Li, Co, and Ni were 97.7%, 95.4%, and 96.2%, respectively.

[0051] Example 3

[0052] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0053] 1) Pre-treating a mixture of positive and negative electrode materials and carbon powder of waste ternary batteries with a 4 mol / L NaOH solution, and filtering to obtain NCM material and aluminum-containing filtrate. The contents of metal elements and C in the mixture are Co: 16%, Ni: 25%, Mn: 18%, Li: 6%, Al: 2%, Cu: 0.04%, Fe: 0.03%, C: 17%; the mass volume ratio of the mixture to the NaOH solution is 1:20 g / ml;

[0054] 2) The NCM material and calcium sulfate were mixed in a mass ratio of 1:1.5, and then placed in an argon-protected reactor, and calcined at 750° C. for 150 minutes to obtain a calcined product.

[0055] 3) adding water to the calcined product at a mass volume ratio of 1:12 g / mL and performing an impregnation treatment at 30° C. for 2 hours, then filtering to obtain an impregnation solution and water-impregnated residue, and evaporating the leaching solution to complete the recovery of the metallic Li.

[0056] 4) Dry the water-leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 2:1, and then place it in a high-temperature container for smelting at 1550° C. for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0057] It was determined that the recovery rates of Li, Co, and Ni were 98.1%, 95.3%, and 96.2%, respectively.

[0058] Example 4

[0059] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0060] 1) Pre-treating a mixture of positive and negative electrode materials and carbon powder of waste ternary batteries with a 3 mol / L NaOH solution, and filtering to obtain NCM material and aluminum-containing filtrate. The contents of metal elements and C in the mixture are Co: 15%, Ni: 28%, Mn: 18%, Li: 5%, Al: 3%, Cu: 0.05%, Fe: 0.03%, C: 17%; the mass volume ratio of the mixture to the NaOH solution is 1:30 g / ml;

[0061] 2) The NCM material and calcium sulfate were mixed in a mass ratio of 1:1.4, and then placed in a nitrogen-protected reactor, and calcined at 750° C. for 100 minutes to obtain a calcined product.

[0062] 3) adding water to the calcined product at a mass volume ratio of 1:8 g / mL and performing an impregnation treatment at 32° C. for 1.5 hours, then filtering to obtain an impregnation solution and water-leached residue, and evaporating the leaching solution to complete the recovery of the metallic Li.

[0063] 4) Dry the water-leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 3:1, and then place it in a high-temperature container and smelt it at 1600°C for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0064] It was determined that the recovery rates of Li, Co, and Ni were 97.6%, 95.5%, and 97.1%, respectively.

[0065] Example 5

[0066] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0067] 1) Pre-treating a mixture of waste ternary battery positive and negative electrode materials and carbon powder with a 2 mol / L NaOH solution, and filtering to obtain NCM material and aluminum-containing filtrate. The contents of metal elements and C in the mixture are Co: 13%, Ni: 30%, Mn: 17%, Li: 4%, Al: 2%, Cu: 0.04%, Fe: 0.03%, C: 17.5%; the mass volume ratio of the mixture to the NaOH solution is 1:40 g / ml;

[0068] 2) The NCM material and calcium sulfate were mixed in a mass ratio of 1:1.6, and then placed in a vacuum reactor, and calcined at 700° C. for 90 minutes to obtain a calcined product.

[0069] 3) adding water to the calcined product at a mass volume ratio of 1:6 g / mL and performing an impregnation treatment at 30° C. for 2 hours, then filtering to obtain an impregnation solution and a leached residue, and evaporating the leached solution to complete the recovery of the metallic Li.

[0070] 4) Dry the leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 5:2, and then place it in a high-temperature container and smelt it at 1550°C for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0071] It was determined that the recovery rates of Li, Co, and Ni were 97.5%, 95.8%, and 97.2%, respectively.

[0072] Comparative Example 1

[0073] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0074] 1) Pre-treating a mixture of positive and negative electrode materials and carbon powder of waste ternary batteries with a 3 mol / L NaOH solution, and filtering to obtain NCM material and aluminum-containing filtrate. The contents of metal elements and C in the mixture are Co: 14%, Ni: 27%, Mn: 17%, Li: 4%, Al: 4%, Cu: 0.03%, Fe: 0.04%, C: 17.5%; the mass volume ratio of the mixture to the NaOH solution is 1:30 g / ml;

[0075] 2) mixing the NCM material and calcium sulfate in a mass ratio of 1:1.2, placing the mixture in a vacuum reactor, and calcining the mixture at 700° C. for 120 minutes to obtain a calcined product;

[0076] 3) adding water to the calcined product at a mass volume ratio of 1:5 g / mL and performing an impregnation treatment at 25° C. for 2 h, then filtering to obtain an impregnation solution and a water-impregnated residue, and evaporating the leaching solution to complete the recovery of the metal Li;

[0077] 4) Dry the water-leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 2:1, and then place it in a high-temperature container and smelt it at 1600°C for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0078] The recovery rates of Li, Co and Ni were 85.3%, 95.4% and 96.2%, respectively. It can be seen that compared with Example 1, due to the insufficient addition of calcium sulfate, Li could not be completely sulfated, which affected the recovery rate of Li.

[0079] Comparative Example 2

[0080] A method for recovering metal in a positive electrode by sulfidation roasting with calcium sulfate comprises the following steps:

[0081] 1) Pre-treating a mixture of positive and negative electrode materials and carbon powder of waste ternary batteries with a 3 mol / L NaOH solution, and filtering to obtain NCM material and aluminum-containing filtrate. The contents of metal elements and C in the mixture are Co: 14%, Ni: 27%, Mn: 17%, Li: 4%, Al: 4%, Cu: 0.03%, Fe: 0.04%, C: 17.5%; the mass volume ratio of the mixture to the NaOH solution is 1:30 g / ml;

[0082] 2) mixing the NCM material and calcium sulfate in a mass ratio of 1:1.6, placing the mixture in a vacuum reactor, and calcining the mixture at 700° C. for 120 minutes to obtain a calcined product;

[0083] 3) adding water to the calcined product at a mass volume ratio of 1:5 g / mL and performing an impregnation treatment at 25° C. for 2 h, then filtering to obtain an impregnation solution and a water-impregnated residue, and evaporating the leaching solution to complete the recovery of the metal Li;

[0084] 4) Dry the water-leached slag to a water content of 1%, mix it with a slag-forming agent in a mass ratio of 2:1, and then place it in a high-temperature container and smelt it at 1000°C for 90 minutes to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co. The slag-forming agent is SiO2.

[0085] The recovery rate of Li was 98.1%, the recovery rate of Co was 0%, and the recovery rate of Ni was 0%. It can be seen that compared with Example 1, the recovery of metal Ni and Co could not be completed in this comparative example due to insufficient smelting temperature.

[0086] It should be noted that, according to the above embodiments of the present invention, those skilled in the art can fully realize the full scope of the independent claims and dependent rights of the present invention, and the implementation process and method are the same as the above embodiments; and the part not described in detail in the present invention belongs to the well-known technology in the field. However, the protection scope of the present invention is not limited to this, and any changes or substitutions that can be easily thought of by any person familiar with the field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for recovering metals in a positive electrode by sulfating and roasting with calcium sulfate, characterized in that: The steps include: 1) pretreating a mixture of a cathode material and a carbon source with an alkaline solution, and filtering to obtain an NCM material and an aluminum-containing filtrate; 2) mixing the NCM material with calcium sulfate or gypsum slag in a mass ratio of 1:1.4-2, then placing the mixture in a vacuum reactor or a reactor filled with nitrogen, argon or other inert gases, and calcining the mixture at 600-800° C. to obtain a calcined product; 3) adding water to the roasted product at a mass volume ratio of 1:5-15 g / mL for water leaching, then filtering to obtain a lithium sulfate solution and water leaching residue, and evaporating the leaching solution to complete the recovery of metal Li; 4) Dry the water-leached slag, mix it with a slag-forming agent in a mass ratio of 100:10-100, and then place it in a high-temperature container for smelting at 1200-1600°C to obtain high-matte nickel and manganese-rich slag, thereby completing the recovery of metal Ni and Co.

2. The method according to claim 1, characterized in that In terms of mass, the components in the mixture include Ni: 15-80%, Co: 5-30%, Mn: 5-30%, Li: 2-10%, Al: 0-5%, Ca: 0-3%, Mg: 0-3%, Fe: 0-3%, Cu: 0-3%, and C: 15-20%.

3. The method according to claim 1 or 2, characterized in that The alkaline solution in step 1) includes one or more of NaOH, KOH, Ca(OH)2, and ammonia water.

4. The method according to claim 1 or 2, characterized in that: The concentration of the alkaline solution is 1-5 mol / L, and the mass volume ratio of the battery positive electrode material to the alkaline solution is 1:10-100 g / mL.

5. The method according to claim 1, characterized in that The calcination time is 30-180 min.

6. The method according to claim 1, characterized in that The immersion treatment time is 1-3 hours and the temperature is 20-40°C.

7. The method according to any one of claims 1 to 6, characterized in that: The slag-forming agent is silica.

8. The method according to any one of claims 1 to 6, characterized in that: The smelting time is 30-150 min.

9. The method according to any one of claims 1 to 6, characterized in that: The carbon source includes at least one of a negative electrode material of waste batteries and carbon powder.

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