Discarded waste lithium batteries contain a significant amount of non-renewable heavy metal resources with high economic value. The positive electrode material of lithium batteries is lithium cobalt oxide powder. The negative electrode material is graphite powder. Both electrodes contain substantial quantities of metals such as cobalt, nickel, manganese, copper, and aluminum.
Effective recycling and processing of discarded or unqualified lithium batteries can not only alleviate the environmental pressure. It can also prevent the wastage of valuable heavy metals like cobalt, nickel, and manganese. Consequently, countries worldwide place great importance on the recycling of waste lithium batteries. This is due to resource limitations and the need for environmental governance.
1. Dry recycling and wet recycling
In the process of recycling and treating waste lithium batteries, two main technologies are utilized: dry recycling and wet recycling. Wet recycling technology involves a long process route, requires significant investment, and demands numerous pieces of equipment. It is unable to recycle aluminum metal, and it cannot treat the PVDF in lithium batteries.
On the other hand, dry recycling technology is mainly divided into high-temperature (~800°C) and low-temperature (~400°C) dry processes. Dry recycling technology features a shorter process route and fewer equipment requirements. It can effectively treat PVDF, but it has high energy consumption and requires substantial heat. The dry treatment process inevitably produces acidic gas HF (or other hydrogen halide gases) and organic cracking waste gases. This must be treated separately to avoid significant environmental impact, necessitating a large investment in environmental protection facilities.
Lithium battery recycling and processing equipment typically includes a disassembly line. It is (for repurposing) + grinding and crushing air separation line + extraction (re-extraction) production line. The grinding and crushing air separation line is the core of the complete lithium battery recycling and processing equipment.
However, many manufacturers still use a specific process. This process involves shredding + secondary crushing, grinding + air separation (external high and medium temperature furnaces). This process fails to address the flammable and explosive issues associated with live waste lithium batteries at the source. It results in processing costs approaching 3,000 yuan per ton.
We have introduced advanced foreign technology and implemented technological reforms. The feeding mechanism of our self-produced high-temperature pyrolysis furnace is designed with variable frequency speed regulation. That is to create a high-temperature vacuum belt, effectively solving the fire and explosion risks associated with shredders.
This innovation significantly reduces equipment production and operation costs. Additionally, this unique lithium battery recycling and processing equipment production line does not require nitrogen or other oxygen-isolating gases. It further lowers production and operational expenses.
2. Waste Lithium Battery Recycling and Processing System
This system includes waste lithium battery recycling and processing equipment, as well as waste gas treatment equipment. The waste lithium battery recycling and processing equipment consists of a lithium battery recycling pre-processing shredding device, a pyrolysis device, and a post-processing device (including secondary crushing, grinding, and air separation equipment) connected in sequence.
The pyrolysis device includes a pyrolysis furnace, a variable frequency air volume control device, a production pre-processing device, a dry rotary kiln integration, and a post-processing device, all connected sequentially.
The exhaust port of the dry rotary kiln is three-dimensionally connected to the discharge port of the pre-processing shredding device and the production environmental protection device. The cracking waste gas outlet of the pyrolysis furnace is connected to the environmental protection device. To address the issue of high energy consumption in the dry-process recycling of waste lithium batteries, the complete set of equipment also includes an external heat exchanger, installed on the outside of the pyrolysis furnace.
The air inlet of the external heat exchanger is connected to the high-temperature flue gas discharge port of the environmental protection device. The connecting pipe between the cracking waste gas outlet of the pyrolysis furnace and the dry-process rotary kiln is equipped with an insulation sleeve; one of the branch pipes is connected to the air inlet of the external heat exchanger, and a flow regulating device is installed at the high-temperature flue gas discharge port.
The waste gas generated by the dry-process rotary kiln enters the external heat exchanger of the pyrolysis device through the high-temperature flue gas discharge port of the environmental protection device, serving as a heat source for the pyrolysis furnace.
3. Flow Regulating Device Purpose
The flow regulating device at the high-temperature flue gas discharge port is designed to control the volume of high-temperature flue gas entering the branch pipe. By adjusting the air volume through this device, the temperature of the flue gas entering the air inlet of the external heat exchanger can be maintained within the range of 400°C to 1000°C.
Ideally, this temperature should be controlled between 500°C and 650°C. This creates a vacuum zone, ensuring that the shredder and pyrolysis furnace operate in an oxygen-free environment, effectively addressing fire and explosion prevention in lithium battery recycling from the source.
After being shredded, the waste lithium batteries are fed into the pyrolysis furnace, where the organic materials within the batteries undergo pyrolysis. During this process, the binder PVDF, lithium hexafluorophosphate, and organic solvents present in the waste lithium batteries decompose due to the heat, generating cracking waste gas. This cracking waste gas is then burned, resulting in the production of carbon dioxide, water, HF, and other gases.
The nano-sized calcium oxide in the waste gas treatment device is highly active at operating temperatures. It rapidly reacts with HF to form calcium fluoride, preventing HF from entering the atmosphere. Similarly, any remaining hydrogen halide gases combine with calcium to form calcium halide, while the carbon dioxide and water are treated by the cement production environmental protection device, ensuring they meet emission standards.
