An environmental-friendly method for recovery of aluminum droplets from aluminum dross: Mechanical activation and super-gravity separation

Aluminum dross produced from the smelting process of aluminum is a toxic solid waste that easily hydrolyzes and releases poisonous gases in contact with water, which contains large numbers of fine oxidized aluminum droplets. In this study, an environmental-friendly method for efficient recovery of aluminum droplets from aluminum dross was proposed through mechanical activation and super-gravity separation. Firstly, the aluminum dross with different particle sizes of 8.0-50.0 mm, 4.0-8.0 mm, and < 4.0 mm was mechanically activated, and the oxidized films of metallic aluminum droplets were greatly destructed via milling. However, the driving force of gravity was not sufficient to drive the molten aluminum droplets to detach from the oxidized films at high temperatures. With the enhancement of the super-gravity field, almost all of the aluminum droplets efficiently escaped from the oxidized films and fully recovered from the aluminum dross within 5 min with a high recovery ratio of 97.14% and a high purity of 99.17 wt%. Compared to the conventional process of separating aluminum, this study provides an environmental-friendly method to efficiently recover aluminum droplets from aluminum dross without the problems of secondary aluminum dross production, dust pollution, and gas pollution.