Optimizing hydrometallurgical strategies for the effective removal of aluminium nitride from secondary aluminium slag

This investigation systematically addresses the environmental impacts and treatment strategies for aluminium nitride (AlN) in secondary aluminium slag, a significant hazardous byproduct of aluminium recycling processes in the aluminium industry. This study evaluated the effectiveness of a hydrometallurgical process in which separate experiments were conducted using deionized water and an alkaline solution. Our findings indicate that while elevated temperatures of deionized water accelerate AlN hydrolysis by expediting the chemical reactions involved, the process remains suboptimal and incomplete. In contrast, the use of an alkaline solution markedly increases the hydrolytic efficiency. Notably, at 90°C and a 2:1 liquid-to-solid ratio, significant 95.4 % AIN removal was achieved with an additional 10 wt% sodium hydroxide within 180 min. Additionally, the kinetic analysis suggested that AlN hydrolysis operates under a mixed control mechanism, which indicates that the reaction rate is influenced by both chemical reaction rates and mass transfer processes, as confirmed by kinetic fitting data. These insights have profound implications for the sustainable management of hazardous waste in the aluminium industry while promoting improved environmental conservation and contributing to more efficient resource recycling strategies.