Process Flow of the Dry Separator for Spent Electrode Sheets

The process flow of the dry separator for spent electrode sheets is built around "pretreatment - core stripping - multi-stage sorting - post-treatment". Throughout the process, dry methods such as mechanical force and temperature control are used to separate the active material from the metal current collector, with no wastewater generated, meeting the requirements of environmentally friendly recycling. The detailed flow is as follows:

1. Pretreatment: this stage provides a good basis for subsequent stripping and directly affects stripping efficiency and product purity. First, the spent lithium batteries are fully discharged, typically by soaking in salt water, to avoid short circuits and explosions in later steps. The batteries are then disassembled to remove the electrode sheets; the positive and negative electrodes are sorted and impurities such as separators are removed. The electrodes are then cleaned to remove electrolyte residue. Some processes add special pretreatments, such as freezing the electrodes with liquid nitrogen at -80°C to embrittle the binder, or preheating the positive electrodes at a constant 80°C to soften the binder.

2. Feeding and primary crushing: the pretreated electrode sheets are cut into small pieces or strips and fed evenly into the dry separator by a conveyor belt. Once inside, they first pass through rotating blades or toothed rollers for primary crushing, breaking the sheets into smaller fragments to create contact conditions for the subsequent stripping.

3. Core stripping and powder removal: this is the key stage, and the machine works differently for positive and negative electrodes. Positive electrodes enter the corresponding zone and are precisely cut by ceramic blades so that the active material is released from the aluminum foil. Negative electrodes enter a flexible grinding zone where controllable-pressure rollers grind the graphite layer off the copper foil. At the same time, the hard alloy cutters on the high-speed stripping rotor continuously strike and rub the electrode fragments, further breaking the brittle active material layer off, while the tough metal foil only changes shape.

4. Multi-stage screening and sorting: the mixture of active powder and metal foil falls onto the vibrating screen at the bottom of the machine. Electrode powder below 100-200 mesh passes through the screen and is conveyed by air ducts to the cyclone separator and pulse dust collector, where gas and solids are separated and the powder is collected. Oversize fragments and metal foil pieces that were not fully stripped are returned by the negative pressure system to the stripping chamber for a second pass. Some machines are also equipped with ultrasonic vibrating screens or air classification to improve the separation accuracy of powder and metal foil.

5. Post-treatment and recycling: the collected electrode powder needs further fine screening to remove impurities, after which valuable metals such as lithium and cobalt can be extracted by hydrometallurgy. The separated aluminum and copper foil fragments can be briquetted into metal blocks and returned to production as raw material, closing the resource loop. The whole process is mostly carried out in a closed negative-pressure environment to prevent dust emissions and pollution.