The air classifier is a device that separates materials based on differences in specific gravity, and it is positioned after the crushing step. Its working principle is as follows: the crushed mixed material enters the sorting chamber, where it is subjected to an upward air flow. The lighter fractions, such as separator fragments and electrode powder, are carried away by the air stream and discharged from the upper outlet, while the heavier particles, such as copper and aluminium granules, overcome the air resistance and settle to the bottom for discharge. This achieves the separation of light and heavy materials. The separation accuracy can be controlled by adjusting the air velocity and airflow rate to obtain products of different purities. The entire machine operates under a closed negative‑pressure system to prevent dust leakage.