Enhanced Hydrolysis of Aluminum Nitride from Secondary Aluminum Dross Through Combination of Wet-Stirred Milling and Alkaline Leaching

Deep hydrolysis for removing hazardous aluminum nitride (AlN) from secondary aluminum dross (SAD) remains a challenge nowadays. Enhanced hydrolysis of AlN from SAD through a combination of wet-stirred milling and alkaline leaching is investigated in the present study, which has not been reported before. SAD is activated during wet-stirred milling with water by reducing the grain size and increasing the active surface area. Leaching with NaOH dissolves the hydrolysis products (AlOOH, Al(OH) 3 ) to expose reactive sites of unhydrolyzed AlN, contributing to the enhanced hydrolysis process. Results indicate that by utilizing optimized conditions (10 min wet milling, 5 wt.% NaOH solution, L/S ratio of 2, 75 ℃ temperature, and 120 min duration), 98.3% of AlN is removed from SAD. The kinetic analysis indicates that the hydrolysis process is controlled by both diffusion and chemical reactions, with the activation energy calculated to be 31.0 kJ/mol. After undergoing this enhanced hydrolysis process, the residue, which consisted primarily of Al 2 O 3 and Al(OH) 3 ,can be recycled as Al concentrate. The technology has been already applied in a pilot plant and achieved a favorable effect in practical applications. Graphical Abstract