Method for recycling lithium and cobalt in waste lithium battery by using kitchen waste pyrolysis gas
By utilizing the pyrolysis gas of food waste for layered pyrolysis and carbon thermal reduction, the problems of low efficiency and high cost in the recovery of lithium and cobalt from waste lithium batteries were solved, efficient recovery was achieved, CO2 emissions were reduced, and sustainable development was promoted.
Patent Information
- Application Number
- CN202510897224.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-10-03
AI Technical Summary
Existing methods for recovering lithium and cobalt from waste lithium batteries are inefficient and costly, and the carbon thermal reduction process requires an external carbon source or reducing gas, which increases costs and produces carbon dioxide gas that needs to be treated.
The pyrolysis gas of food waste is used for layered pyrolysis and carbon thermal reduction of lithium and cobalt in waste lithium batteries. The reducing gases CO, H2, CH4, etc. generated by food waste are used for carbon thermal reduction to reduce the external carbon source. The carbonic acid water leaching process is combined to recover lithium and cobalt and reduce CO2 emissions.
It improves the recycling efficiency of lithium and cobalt, reduces recycling costs, and realizes the harmless, reduced and resource-based treatment of food waste, reduces CO2 emissions, and promotes sustainable development.
Smart Images
Figure CN120738490A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solid waste resource utilization, and in particular to a method for recovering lithium and cobalt from waste lithium batteries by utilizing pyrolysis gas from kitchen waste. Background Art
[0002] Lithium batteries are widely used due to their excellent energy efficiency and green energy strategy. However, due to their limited lifespan, a large amount of spent lithium batteries enters municipal waste streams. Spent lithium cobalt oxide batteries contain abundant resources, including valuable cobalt and lithium. The scarcity and uneven distribution of lithium and cobalt minerals further increase the importance of recycling these resources. Therefore, recovering lithium and cobalt from spent lithium batteries is essential to promoting a circular economy and green manufacturing in the lithium battery industry.
[0003] Among the recycling methods for waste lithium batteries, carbon thermal reduction technology has the characteristics of simple process flow and easy operation, so it has received more attention. Carbon thermal reduction technology achieves the reduction conversion of positive electrode materials by heating in a vacuum environment, and then selectively recovers lithium carbonate by water immersion. However, relying solely on vacuum heating means that the reduction time is too long, the battery reduction efficiency is not high, and it is easy to cause the reduction temperature to be too high. In order to improve the reduction efficiency, it is often necessary to add an external carbon source and introduce reducing gases such as CO and H2, but this will greatly increase the cost of battery recycling. In addition, carbon dioxide gas will be produced during the carbon thermal reduction process. In order to reduce gas emissions, the carbon dioxide produced by carbon thermal reduction also needs to be treated for carbon reduction. Summary of the Invention
[0004] The technical problem to be solved by the present invention is that the existing method for recovering lithium and cobalt from waste lithium batteries has low recovery efficiency and high recovery cost.
[0005] To this end, the present invention provides a method for recovering lithium and cobalt from waste lithium batteries by utilizing pyrolysis gas from kitchen waste.
[0006] The technical solution adopted by the present invention to solve its technical problem is:
[0007] A method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste, comprising the following steps:
[0008] Step 1: pre-processing the food waste to extract the solid residue in the food waste;
[0009] Step 2: Processing waste lithium batteries to obtain waste lithium cobalt oxide powder;
[0010] Step 3: placing the kitchen waste solid residue and the waste lithium cobalt oxide powder in a container for layered pyrolysis, wherein the kitchen waste solid residue is located below the waste lithium cobalt oxide powder, and the pyrolysis gas generated by the kitchen waste solid residue performs carbothermal reduction on the waste lithium cobalt oxide powder;
[0011] Step 4: taking out the waste lithium cobalt oxide powder after carbothermal reduction and leaching it with carbonic acid water;
[0012] Step 5: After the carbonated water leaching is completed, solid-liquid separation is performed to obtain a Li-containing leachate and a Co-containing leachate residue, respectively. The Li-containing leachate is evaporated and crystallized at high temperature to obtain high-purity lithium carbonate, and the Co-containing leachate residue is dried to obtain a CoO and Co mixture.
[0013] By adopting the above technical solution, the waste lithium cobalt oxide powder is subjected to carbon thermal reduction treatment using the reducing pyrolysis gas generated by kitchen waste residues, thereby achieving waste treatment with waste. In the process of carbon thermal reduction treatment of the waste lithium cobalt oxide powder, there is no need to add an external carbon source or introduce reducing gases such as CO and H2, thereby reducing the cost of recycling the waste lithium cobalt oxide powder and improving the recycling efficiency of the waste lithium cobalt oxide powder.
[0014] Furthermore, in step three, nitrogen is introduced from the bottom of the container to heat the container so that the temperature in the furnace is 400-800° C. and the pyrolysis time is 5-90 minutes.
[0015] Furthermore, in step three, the mass ratio of waste lithium cobalt oxide powder to waste kitchen waste solid residue is 1:2-1:10.
[0016] Furthermore, in step three, the mass ratio of waste lithium cobalt oxide powder to waste kitchen waste solid residue is 1:4-1:8.
[0017] Furthermore, in step 4, the waste lithium cobalt oxide powder after carbon thermal reduction is taken out and placed in a beaker filled with water, and the CO2 generated by pyrolysis in the container and the CO2 generated by the carbon thermal reduction reaction are introduced into the beaker for carbonated water immersion.
[0018] By adopting the above technical solution, the CO2 generated by pyrolysis and carbon thermal reduction can be fully utilized and used in water immersion, thereby reducing CO2 emissions.
[0019] Furthermore, the temperature range of the carbonated water immersion is from room temperature to 80° C., and the time of the carbonated water immersion is from 30 min to 180 min.
[0020] Furthermore, the temperature range of the carbonated water immersion is from room temperature to 50° C., and the carbonated water immersion time is 1-2 hours.
[0021] Furthermore, the solid-to-liquid ratio between the mass of the waste lithium cobalt oxide powder after carbothermal reduction and the volume of water is 10 g / L-50 g / L.
[0022] Furthermore, the solid-to-liquid ratio between the mass of the waste lithium cobalt oxide powder after carbothermal reduction and the volume of water is 20 g / L-40 g / L.
[0023] Furthermore, during the carbonated water soaking, the mixed solution in the beaker was stirred at a stirring speed of 400-600 rpm.
[0024] The present invention has the beneficial effect of providing a method for recovering lithium and cobalt from spent lithium batteries using pyrolysis gas from food waste. This method utilizes various reducing gases, such as CO, H2, and CH4, in the pyrolysis gas generated by pyrolysis of food waste to promote the carbon thermal reduction of the positive electrode materials in spent lithium batteries, thereby reducing the cost of recycling spent lithium batteries and improving the reduction efficiency of spent lithium batteries.
[0025] Pyrolysis technology can render food waste harmless, reduce its volume, and recycle it into a resource. The pyrolysis gas, biochar, and pyrolysis oil produced by pyrolysis can all be processed and recycled. Pyrolysis gas, primarily composed of CO, CO2, H2, and CH4, is typically reused as fuel. However, this use suffers from issues such as low quality and inefficiency.
[0026] The carbon thermal reduction of batteries has low requirements for the purity of the pyrolysis gas. Therefore, this application innovatively proposes to use the generated pyrolysis gas for the carbon thermal reduction of batteries, which not only improves the utilization rate of kitchen waste recycling, but also reduces the cost of battery recycling, realizing waste treatment with waste and coordinated resource processing of solid waste.
[0027] The CO2 in the pyrolysis gas and the CO2 generated during the carbothermal reduction process are fully utilized in the carbonated water leaching process of the lithium carbonate in the reduction product, while simultaneously recovering Li and Co, thereby reducing CO2 emissions during the recovery process. This not only solves the environmental pollution problems caused by food waste and waste lithium batteries, but also achieves efficient utilization of food waste pyrolysis gas and avoids CO2 emissions, achieving waste treatment with waste, synergistic resource processing of solid waste, promoting sustainable development, and contributing to the realization of my country's "dual carbon" goals. The method of the present invention has a lithium and cobalt recovery rate of over 97%, a simple process, and is easy to industrialize and apply, making it a clean production process. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The present invention will be further described below with reference to the accompanying drawings and examples.
[0029] Figure 1 This is a flow chart of the method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste in the present invention. DETAILED DESCRIPTION
[0030] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.
[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.
[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.
[0033] A method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste, comprising the following steps:
[0034] Step 1: Dehydrate the food waste to obtain food waste solid residue and oil-water mixture. In one embodiment of the present invention, the device used in the food waste dehydration pretreatment process in this step is a squeeze dehydrator.
[0035] Step 2: Discharging, disassembling, and separating the used lithium batteries pre-processes to obtain used lithium cobalt oxide powder. Specifically, in one embodiment of the present invention, the used lithium cobalt oxide battery discharge, disassembly, and separation process involves immersing the used lithium cobalt oxide battery in a saturated sodium chloride solution for more than 12 hours, dehydrating the battery under vacuum at 90°C, and then transferring the battery to a glove box for manual disassembly and separation to obtain the used lithium cobalt oxide powder.
[0036] Step three, performing layered pyrolysis on the solid residue of kitchen waste obtained in step one and the waste lithium cobalt oxide powder obtained in step two to obtain kitchen waste pyrolysis gas, pyrolysis carbon and waste lithium cobalt oxide battery reduction products, respectively.
[0037] In one embodiment of the present invention, the device used for layered pyrolysis is a multi-layer vertical tube furnace, which is an existing device. The waste lithium cobalt oxide powder is placed on the top and the solid residue of food waste is placed at the bottom. The mass ratio M of the waste lithium cobalt oxide powder to the solid residue of waste food waste is 1:2-1:10, preferably, M is 1:4-1:8.
[0038] Nitrogen is introduced into the multi-layer vertical tube furnace from the bottom thereof, and the multi-layer vertical tube furnace is heated to a temperature of 400-800° C. and a pyrolysis time of 5-90 minutes.
[0039] The pyrolysis gas (CO, CO2, H2, CH4, etc.), biochar and pyrolysis oil produced by the pyrolysis of food waste can be recycled after treatment. The CO, H2 and CH4 produced by pyrolysis rise, promoting the carbon thermal reduction process of the positive electrode material of waste lithium batteries.
[0040] Step 4: taking out the waste lithium cobalt oxide powder after carbon thermal reduction and leaching it in carbonic acid water.
[0041] It should be noted that the waste lithium cobalt oxide powder after carbon thermal reduction is taken out and placed in a beaker filled with water. During the water immersion, the CO2 in the pyrolysis gas obtained in step 3 and the CO2 generated by the carbon thermal reduction reaction are passed into the reaction device for carbonic acid water immersion. The tubular furnace outlet is connected to the beaker through a hose. The temperature of the carbonic acid water immersion is room temperature to 80°C, the time of the carbonic acid water immersion is 30min-180min, the solid-liquid ratio (the mass of the waste lithium cobalt oxide battery reduction product to the volume of water) is 10g / L-50g / L, and the stirring speed is 300-700rpm. Preferably, the temperature of the carbonic acid water immersion is room temperature to 50°C, the carbonic acid water immersion time is 1-2h, the solid-liquid ratio is 20g / L-40g / L, and the stirring speed is 400-600rpm.
[0042] Step 5: After the carbonated water leaching is completed, solid-liquid separation is performed to obtain Li-containing leaching solution and Co-containing leaching residue respectively.
[0043] The Li-containing leachate is subjected to high-temperature evaporation and crystallization to obtain high-purity lithium carbonate. The instrument for high-temperature evaporation and crystallization of the Li-containing leachate is an electric heating plate. The evaporation and crystallization temperature is 80-100°C, preferably, the evaporation and crystallization temperature is 90-100°C.
[0044] The Co-containing leaching residue is further dried to obtain a CoO / Co mixture. The drying equipment for the Co-containing leaching residue is a vacuum drying oven. The drying temperature is 50-90° C. and the drying time is 1 h-5 h. Preferably, the vacuum drying temperature is 60-80° C. and the drying time is 2-3 h.
[0045] Example 1
[0046] The kitchen waste was pre-treated by dehydration using an extrusion dehydrator to obtain kitchen waste solid residue and an oil-water mixed liquid. The waste lithium cobalt oxide battery was immersed in a saturated sodium chloride solution for more than 12 hours, then dehydrated under vacuum conditions at 90°C, and then transferred to a glove box for manual disassembly and separation to obtain waste lithium cobalt oxide powder. The kitchen waste solid residue and waste lithium cobalt oxide powder were placed in a multi-layer vertical tube furnace for layered pyrolysis, wherein the waste lithium cobalt oxide powder was placed at the top and the kitchen waste solid residue was placed at the bottom. The pyrolysis gas was nitrogen, the pyrolysis temperature was 500°C, the pyrolysis time was 30 minutes, and the mass ratio M of the waste lithium cobalt oxide powder to the waste kitchen waste solid residue was 1: 5. The pyrolysis gas of the kitchen waste, the pyrolysis carbon and the reduction product of the waste lithium cobalt oxide battery are obtained respectively; the reduction product of the waste lithium cobalt oxide battery is placed in a beaker, and the pyrolysis gas is introduced into the beaker for carbonated water leaching, the carbonated water leaching temperature is 50° C., the carbonated water leaching time is 90 min, the solid-liquid ratio (the mass of the waste lithium cobalt oxide battery reduction product to the volume of water) is 30 g / L, the stirring speed is 400 rpm, and then solid-liquid separation is performed to obtain a Li-containing leachate and a Co-containing leachate residue, respectively; finally, the Li-containing leachate is evaporated and crystallized at 90° C. to obtain high-purity lithium carbonate, and the Co-containing leachate residue is dried in a vacuum drying oven at 60° C. for 3 h to obtain a CoO / Co mixture.
[0047] Example 2
[0048] In this example, the pyrolysis time in Example 1 was replaced with 10 min, and other conditions were exactly the same as in Example 1.
[0049] Example 3
[0050] In this embodiment, the pyrolysis temperature in Example 1 is replaced with 600° C., and other conditions are exactly the same as those in Example 1.
[0051] Example 4
[0052] In this embodiment, the mass ratio M of waste lithium cobalt oxide powder to waste kitchen waste solid residue in Example 1 is replaced with 1:8, and other conditions are exactly the same as those in Example 1.
[0053] Example 5
[0054] In this example, the carbonated water immersion time in Example 1 was replaced with 60 min, and other conditions were exactly the same as in Example 1.
[0055] Example 6
[0056] In this example, the carbonated water immersion temperature in Example 1 was replaced with room temperature, and other conditions were exactly the same as in Example 1.
[0057] Example 7
[0058] In this example, the solid-to-liquid ratio in the carbonated water leaching process in Example 1 was replaced with 10 g / L, and other conditions were exactly the same as in Example 1.
[0059] The high-purity Li2CO3 and CoO / Co mixture obtained in Examples 1-7 was digested and then detected by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the recovery rates of Li and Co were calculated.
[0060] The calculation formulas for Li and Co recovery are as follows:
[0061]
[0062] The recoveries of Li and Co according to the methods described in Examples 1-7 are shown in Table 1.
[0063] Table 1 Recovery rates of Li and Co
[0064]
[0065] In summary, this invention proposes, for the first time, a method for recovering lithium and cobalt from spent lithium batteries using pyrolysis gases from food waste. This method utilizes reducing gases such as CO, H₂, and CH₄ in the pyrolysis gases generated by food waste pyrolysis to promote the carbothermal reduction of the cathode materials in spent lithium batteries. Furthermore, the CO₂ in the pyrolysis gases and the CO₂ generated during the carbothermal reduction process are fully utilized in the carbonic acid water leaching of the lithium carbonate in the reduction product, simultaneously recovering both lithium and cobalt.
[0066] This application not only solves the environmental pollution problem caused by food waste and used lithium batteries, but also reduces CO2 emissions during the recycling process, achieving efficient utilization of food waste pyrolysis gas and avoiding CO2 emissions. This achieves waste treatment with waste, synergistic resource processing of solid waste, promotes sustainable development, and contributes to the realization of my country's "dual carbon" goals. The method of the present invention achieves lithium and cobalt recovery rates of over 97%, a simple process, and is easy to industrialize, making it a clean production process.
[0067] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical spirit of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste, characterized in that: The following steps are included: Step 1: pre-processing the food waste to extract the solid residue in the food waste; Step 2: Processing waste lithium batteries to obtain waste lithium cobalt oxide powder; Step 3: placing the kitchen waste solid residue and the waste lithium cobalt oxide powder in a container for layered pyrolysis, with the kitchen waste solid residue located below the waste lithium cobalt oxide powder, and the pyrolysis gas generated by the kitchen waste solid residue performs carbothermal reduction on the waste lithium cobalt oxide powder; Step 4: taking out the waste lithium cobalt oxide powder after carbothermal reduction and leaching it with carbonic acid water; Step 5: After the carbonated water leaching is completed, solid-liquid separation is performed to obtain a Li-containing leachate and a Co-containing leachate residue, respectively. The Li-containing leachate is evaporated and crystallized at high temperature to obtain high-purity lithium carbonate, and the Co-containing leachate residue is dried to obtain a CoO and Co mixture.
2. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 1, characterized in that: In step three, nitrogen is introduced from the bottom of the container to heat the container so that the temperature in the furnace is 400-800° C. and the pyrolysis time is 5-90 minutes.
3. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 1, characterized in that: In step three, the mass ratio of waste lithium cobalt oxide powder to waste kitchen waste solid residue is 1:2-1:
10.
4. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 3, characterized in that: In step three, the mass ratio of waste lithium cobalt oxide powder to waste kitchen waste solid residue is 1:4-1:
8.
5. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 1, characterized in that: In step 4, the waste lithium cobalt oxide powder after carbon thermal reduction is taken out and placed in a beaker filled with water, and the CO2 generated by pyrolysis and carbon thermal reduction reaction in the container is introduced into the beaker for carbonated water immersion.
6. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 1, characterized in that: The temperature range of the carbonated water immersion is from room temperature to 80°C, and the time of the carbonated water immersion is from 30 minutes to 180 minutes.
7. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 6, characterized in that: The temperature range of the carbonated water immersion is from room temperature to 50°C, and the carbonated water immersion time is 1-2 hours.
8. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 1, characterized in that: The solid-to-liquid ratio between the mass of the waste lithium cobalt oxide powder after carbothermal reduction and the volume of water is 10g / L-50g / L.
9. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 8, characterized in that: The solid-to-liquid ratio between the mass of the waste lithium cobalt oxide powder after carbothermal reduction and the volume of water is 20 g / L-40 g / L.
10. The method for recovering lithium and cobalt from waste lithium batteries using pyrolysis gas from kitchen waste according to claim 1, characterized in that: During the carbonated water soaking, the mixed solution in the beaker was stirred at a stirring speed of 400-600 rpm.