Green and pollution-free method for extracting metal elementary substance from metal compound
By using a supercritical carbon dioxide system in the cathode material of lithium-ion batteries, the metal compounds are converted into metal element under high temperature and high pressure conditions, solving the problem of high contamination in the extraction process in the prior art, and achieving a green and pollution-free metal element extraction method.
Patent Information
- Application Number
- CN202411780018.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art has a problem of high contamination in the extraction process of metal compounds in the positive electrode materials of lithium-ion batteries, and there is a lack of a green and pollution-free extraction method.
Using a supercritical carbon dioxide system, the metal compound was placed under conditions of 450-800°C and 0.7-300MPa, and the heat was insulated for 3-24 hours, and the metal element was obtained after natural cooling.
The direct transformation of metal compounds into metal elemental substances is achieved without the need for addition of solutions or chemical substances. The entire process is environmentally friendly and pollution-free, and the recycling process is simple and efficient.
Smart Images
Figure CN119592797A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of preparation and processing of chemical raw materials, and in particular relates to a green and pollution-free method for extracting metal elements from metal compounds. Background Art
[0002] Lithium-ion batteries are mainly composed of four main materials and related auxiliary materials, including positive electrode materials such as lithium cobalt oxide, lithium iron phosphate, and ternary materials; electrolytes composed of lithium salts, organic solvents, and additives; negative electrode materials such as natural graphite, mesophase carbon microspheres, and artificial graphite, as well as diaphragms. Depending on the different models and actual working conditions, its service life is about 3-8 years, and the number of charge and discharge times can reach 500-2000 times. With the advent of the retirement of early new energy vehicles, there will be a huge amount of lithium-ion batteries that need to be recycled and reused. Among them, the positive electrode materials contain metal materials such as nickel, iron, lithium, and aluminum, especially cobalt precious metal raw materials and lithium, a core lithium battery basic raw material with relatively low global reserves. Recycling and reuse of them is often more valuable and has a broader market prospect.
[0003] The recycling process of lithium-ion batteries is mainly divided into dry recycling and wet recycling. The dry recycling process is simple, but it consumes a lot of energy and emits toxic gases, which is not very friendly to the environment. The cost of wet recycling is lower, but it will use various chemical reagents, produce wastewater and various hazardous wastes, and also have certain environmental pressures. For the extraction and recovery of metals from metal compounds such as cobalt, manganese, nickel, and chromium in the positive electrode materials of lithium-ion batteries, the existing technology does not provide an effective green and pollution-free extraction method. Summary of the invention
[0004] The purpose of the present invention is to provide a green and pollution-free method for extracting metal elements from metal compounds to solve the problem of high pollution in the extraction of metals from metal compounds in positive electrode materials of lithium-ion batteries.
[0005] The purpose of the present invention can be achieved through the following technical solutions:
[0006] A green and pollution-free method for extracting a metal element from a metal compound comprises the following steps:
[0007] The metal compound is placed in a supercritical carbon dioxide (sc-CO2) system, and reacted at a temperature of 450-800°C and a pressure of 0.7-300MPa for 3-24 hours, and then naturally cooled to room temperature (25-30°C) to obtain a metal element.
[0008] Furthermore, the metal chemical is one or more combinations of metal carbonates, metal carbides or metal oxides.
[0009] Furthermore, the metal carbonate (MCO3) includes one or more combinations of cobalt carbonate, basic cobalt carbonate, nickel carbonate, basic nickel carbonate, manganese carbonate, basic manganese carbonate, chromium carbonate, and basic chromium carbonate.
[0010] Furthermore, the metal carbide (M2C) includes one or more combinations of cobalt carbide, nickel carbide, manganese carbide, and cobalt carbide.
[0011] Furthermore, the metal oxide (M x O y ) includes one or more combinations of cobalt oxide, nickel oxide, manganese oxide, and cobalt oxide.
[0012] Furthermore, the supercritical carbon dioxide is any one of dry ice and high-pressure carbon dioxide gas.
[0013] Furthermore, the amount of supercritical carbon dioxide used is 5-100 times the amount of the metal compound used, ensuring that the reaction system reaches the corresponding supercritical condition.
[0014] Compared with the prior art, the present invention has the following beneficial effects:
[0015] 1. The present invention provides a green and pollution-free method for extracting metal elements from metal compounds. Based on a supercritical carbon dioxide system, a raw metal compound is converted into a metal element under a certain temperature, pressure and reaction time and then incorporated into a supercritical carbon dioxide reaction system. Finally, the metal element is discharged or recovered with the carbon dioxide gas without any liquid or solid residue. The entire reaction can directly realize the transformation of metal carbonates, metal carbides or metal oxides into corresponding metal elements. The recovery process is simple and efficient, and the present invention is a green and pollution-free method for extracting metal elements.
[0016] 2. Supercritical carbon dioxide system has the characteristics of strong solubility and high diffusivity, low surface tension and low viscosity, especially the special reaction ability under high temperature and high pressure conditions. As a reaction solvent, it can directly convert MCO3 (M is transition metals such as Co, Mn, Ni, Cr) metal carbonate into the corresponding metal element. At a lower temperature, MCO3 will be converted into M2C (metal carbide) or the corresponding M x O y (Metal oxide) and its mixture, further increasing the reaction temperature can obtain the corresponding metal element. After the reaction is completed, the carbon dioxide will be discharged or recovered in the form of gas, and there will be no liquid or solid residue. The entire reaction process can directly realize the transformation of metal compounds into corresponding metal elements. The recovery and extraction process is simple and efficient, and the green and pollution-free extraction of metal monomers is realized.
[0017] 3. The preparation method of the present invention is simple, scientific, efficient, green and pollution-free. Different from the existing dry and wet methods, no solution, acid, alkali or other chemical substances need to be added during the entire reaction process. Only supercritical carbon dioxide needs to be used as the reaction system. After the reaction, carbon dioxide is discharged in the form of gas, and no wastewater, solid hazardous waste or other by-products that are difficult to handle are generated, which reduces the environmental pressure. If the carbon dioxide gas after the reaction is further recycled and reused, no waste will be generated, which is a truly green and pollution-free preparation method.
[0018] 4. In the present invention, the sources of metal elements are diverse. Since cobalt, nickel, manganese and chromium are all transition metals, they have high atomic numbers, can form stable multivalent ions, and show similar properties in chemical reactions; taking CoCO3 as an example, several types of substances such as CoCO3, Co / CoCO3 / Co2O3 mixed phase, Co / CoCO3 / Co2O3 mixed phase can be obtained under different temperature conditions, and finally the corresponding metal elements can be extracted. As the source of metal elements, its raw materials can be metal carbonates, metal carbides or metal oxides and mixtures thereof, all of which can be converted into corresponding metal elements under high temperature and high pressure conditions of supercritical carbon dioxide system. This method not only provides a new solution for the extraction of corresponding metal elements, but also provides a technical solution for the recycling of metal elements in common positive electrode materials in lithium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present invention will be further described below in conjunction with the accompanying drawings.
[0020] Figure 1 is the XRD spectrum of the product obtained by CoCO3 in the s-CO2 system in Example 1 of the present invention;
[0021] Figure 2 is a SEM image of the product obtained by CoCO3 in the s-CO2 system in Example 1 of the present invention;
[0022] Figure 3 is the XRD spectrum of the product obtained by CoCO3 in the s-CO2 system in Example 2 of the present invention;
[0023] Figure 4 is a SEM image of the product obtained by CoCO3 in the s-CO2 system in Example 2 of the present invention;
[0024] Figure 5 is the XRD spectrum of the product obtained by CoCO3 in the s-CO2 system in Example 3 of the present invention;
[0025] Figure 6 is a SEM image of the product obtained by CoCO3 in the s-CO2 system in Example 3 of the present invention;
[0026] Figure 7 It is the XRD spectrum of the product obtained by CoCO3 in the s-CO2 system in Comparative Example 1 of the present invention;
[0027] Figure 8 It is a SEM image of the product obtained by CoCO3 in the s-CO2 system in Comparative Example 1 of the present invention;
[0028] Fig. 9 It is a schematic diagram of the present invention using different metal compounds to transform into corresponding metal elements. DETAILED DESCRIPTION
[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0030] A green and pollution-free method for extracting a metal element from a metal compound comprises the following steps:
[0031] The metal compound powder is added into a 25 mL stainless steel reactor, wherein the stainless steel reactor has an open quartz glass tube with a volume of 10 mL, and the metal compound powder is placed in the quartz glass tube, on the one hand to avoid the metal compound powder contacting the inner wall of the stainless steel reactor during the reaction to induce side reactions and cause the appearance of impurities, and on the other hand to facilitate the collection of the product after the reaction is completed;
[0032] Supercritical carbon dioxide (sc-CO2) is added into the reactor as a reaction solvent, and the reactor is quickly closed to ensure that the carbon dioxide gas does not leak out during the entire reaction process. The reactor is placed in a muffle furnace and heated to 450-800°C at a heating rate of 10°C / min, and the reaction is kept warm for 3-24 hours. The entire reaction is carried out under the pressure of the reactor itself, and the supercritical regulation of the carbon dioxide system is fully achieved, wherein the pressure is 0.7-300MPa;
[0033] After the reaction is completed, the mixture is naturally cooled to room temperature, the reactor is opened to collect or disperse the carbon dioxide, and then the product in the quartz glass tube is taken out to obtain the corresponding metal element.
[0034] In a specific implementation case, the metal compound includes but is not limited to cobalt carbonate.
[0035] In a specific implementation case, the supercritical carbon dioxide is any one of dry ice and high-pressure carbon dioxide gas; wherein dry ice can be obtained by freezing carbon dioxide gas by liquid nitrogen, or by directly purchasing finished dry ice, crushing it and adding it to the reactor; high-pressure carbon dioxide gas can be obtained by compressing carbon dioxide gas by conventional means.
[0036] Example 1
[0037] This embodiment provides a green and pollution-free method for extracting a metal element from a metal compound (cobalt carbonate), comprising the following steps:
[0038] 0.5 g of cobalt carbonate powder was added into a 25 mL stainless steel reactor, wherein the stainless steel reactor had an open quartz glass tube with a volume of 10 mL, and the metal compound powder was placed in the quartz glass tube, on the one hand to avoid the metal compound powder from contacting the inner wall of the stainless steel reactor during the reaction to induce side reactions and cause the appearance of impurities, and on the other hand to facilitate the collection of the product after the reaction was completed;
[0039] 12.00±0.01g of dry ice was added into the reactor as the reaction solvent system, and the reactor was quickly closed to ensure that the carbon dioxide gas would not leak out during the entire reaction process. The reactor was placed in a muffle furnace and heated to 600°C at a heating rate of 10°C / min, and the reaction was kept warm for 5 hours. The entire reaction was carried out under the pressure of the reactor itself, and the carbon dioxide system was completely supercritically regulated, with a pressure of 150±3MPa;
[0040] After the reaction is completed, the mixture is naturally cooled to room temperature, the reactor is opened to dissipate the carbon dioxide, and the product in the quartz glass tube is taken out to obtain the corresponding metal element cobalt.
[0041] The product obtained in this example was characterized by X-ray diffraction (XRD). Figure 1 As shown, from Figure 1 It can be seen that the XRD diffraction peaks of the product correspond to the (111) and (200) diffraction peaks of metal cobalt (Co), and its standard diffraction (PDF) card number is 15-0806;
[0042] Scanning electron microscopy (SEM) was used to characterize the morphology of the product. Figure 2 As shown, from Figure 2 It can be seen that the particles are irregular nanoparticles with a size of about 200 nm. The reason for the smaller size distribution of the product is that the raw material of the cobalt carbonate powder is a nano-scale powder made in the laboratory.
[0043] Example 2
[0044] This embodiment provides a green and pollution-free method for extracting a metal element from a metal compound (cobalt carbonate). The difference from Embodiment 1 is that after the reaction kettle is sealed, it is placed in a muffle furnace and heated to 550° C. at a heating rate of 10° C. / min, and the insulation reaction time is 4 hours; the other steps and parameters remain the same.
[0045] The XRD results of the product obtained in this example are as follows Figure 3 As shown, its XRD diffraction peaks correspond to three products, namely cobalt carbonate (CoCO3), cobalt carbide (Co2C) and metallic cobalt (Co), and the standard PDF card numbers are 78-0209, 05-0704 and 15-0806, respectively. That is, at this temperature, cobalt carbonate is decomposed to a certain extent, but an intermediate product such as cobalt carbide appears in the product, and cobalt carbonate is not completely decomposed, and the reaction temperature and reaction time need to be further increased;
[0046] The appearance of the product is Figure 4 As shown, these are irregular micron-sized particles formed by tiny nanoparticle clusters.
[0047] Example 3
[0048] This embodiment provides a green and pollution-free method for extracting a metal element from a metal compound (cobalt carbonate). The difference from Embodiment 1 is that after the reaction kettle is sealed, it is placed in a muffle furnace and heated to 500° C. at a heating rate of 10° C. / min, and the insulation reaction time is 4 hours; the other steps and parameters remain the same.
[0049] The XRD results of the product obtained in this example are as follows Figure 5 As shown, its XRD diffraction peaks correspond to three products, namely cobalt carbonate (CoCO3), cobalt oxide (Co2O3) and metallic cobalt (Co), and the standard PDF card numbers are 78-0209, 02-0770 and 15-0806, respectively. The intermediate product in the product becomes cobalt oxide, and the reaction temperature and reaction time also need to be further increased.
[0050] The appearance of the product is Figure 6 As shown, the nanoparticles are cross-linked, which further indicates that the reaction is not complete at this temperature.
[0051] Comparative Example 1
[0052] The difference between this comparative example and Example 1 is that after the reactor is sealed, it is placed in a muffle furnace and heated to 400° C. at a heating rate of 10° C. / min, and the insulation reaction time is 5 hours; the other steps and parameters remain the same.
[0053] The XRD results of the product obtained in this comparative example are as follows Figure 7As shown, its XRD diffraction peak corresponds to cobalt carbonate (CoCO3), and the standard PDF card number is 78-0209, indicating that the composition of the raw materials has not changed under the reaction conditions, and the reaction temperature needs to be further increased.
[0054] The appearance of the product is Figure 8 As shown, it is mainly rod-shaped cobalt carbonate nanomaterials made in the laboratory, with a relatively smooth surface and no obvious signs of decomposition.
[0055] In Examples 1 to 3 and Comparative Example 1, the components of cobalt carbonate decomposed in a supercritical carbon dioxide reaction system at different temperatures are shown in Table 1.
[0056] Table 1
[0057] Temperature(℃) Product components Example 1 600 Co Example 2 550 <![CDATA[Co、Co2C、CoCO3]]> Example 3 500 <![CDATA[Co、Co2O3、CoCO3]]> Comparative Example 1 400 <![CDATA[CoCO3]]>
[0058] As can be seen from Table 1, the reaction temperature has an effect on the decomposition products of cobalt carbonate in the supercritical carbon dioxide reaction system.
[0059] During the reaction, different metal compounds are converted into corresponding metal elements. Fig. 9 As shown in the figure, different types of intermediate products can be obtained under different experimental conditions, and the corresponding metal elements can be obtained by further increasing the reaction temperature. When CoCO3 is used as the raw material, several different substances such as CoCO3, Co / CoCO3 / Co2O3 mixed phase, Co / Co2C / CoCO3 mixed phase, and Co element are obtained in the process of gradually increasing the temperature. The reaction temperature and holding time are the key factors for the transformation of these components.
[0060] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.
[0061] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A green and pollution-free method for extracting metal elements from metal compounds, characterized in that: The following steps are involved: The metal compound is placed in a supercritical carbon dioxide system, and reacted at a temperature of 450-800°C and a pressure of 0.7-300MPa for 3-24 hours, and then naturally cooled to room temperature to obtain a metal element.
2. A green and pollution-free method for extracting metal elements from metal compounds according to claim 1, characterized in that: The metal chemical is one or more combinations of metal carbonates, metal carbides or metal oxides.
3. A green and pollution-free method for extracting metal elements from metal compounds according to claim 2, characterized in that: The metal carbonate includes one or more combinations of cobalt carbonate, basic cobalt carbonate, nickel carbonate, basic nickel carbonate, manganese carbonate, basic manganese carbonate, chromium carbonate, and basic chromium carbonate.
4. A green and pollution-free method for extracting metal elements from metal compounds according to claim 2, characterized in that: The metal carbide includes one or more combinations of cobalt carbide, nickel carbide, manganese carbide and cobalt carbide.
5. A green and pollution-free method for extracting metal elements from metal compounds according to claim 2, characterized in that: The metal oxide includes one or more combinations of cobalt oxide, nickel oxide, manganese oxide and cobalt oxide.
6. A green and pollution-free method for extracting metal elements from metal compounds according to claim 1, characterized in that: The supercritical carbon dioxide is any one of dry ice and high-pressure carbon dioxide gas.
7. A green and pollution-free method for extracting metal elements from metal compounds according to claim 1, characterized in that: The amount of the supercritical carbon dioxide used is 5-100 times the amount of the metal compound used.