Efficient AlN decomposition and Al species transformation in secondary aluminum dross by co-sintering with waste sodium acetate

Secondary aluminum dross (SAD) poses a significant risk due to its high AlN content, while simultaneously offering a rich source of recyclable aluminum. Therefore, to reduce environmental risks during aluminum extraction process, the thorough removal of AlN becomes a prerequisite. Meanwhile, the intricate aluminum components and expensive additives also pose challenges to the process. In this study, waste sodium acetate (WSA) is proposed as an environmentally friendly additive for the deep removal of AlN and the enhanced extraction of aluminum from SAD. Due to the exothermic decomposition of NaAc, the reaction can occur at as low as 850 oC. The AlN removal efficiency reached an impressive 94.19% after sintering, while the Al leaching efficiency in the subsequent leaching process attained 93.55%. Compared with the control, these efficiencies were significantly increased by 41.80% and 391.33%, respectively. The favorable results were contributed to the comprehensive transformation of aluminum species. The formation of soluble phases Na1.95Al1.95Si0.25O4 occurred during the destruction of Al2O3 layer surrounding AlN and the transformation of other aluminum components. Simultaneously, the exposed AlN underwent decomposition under the action of NaAc. Therefore, this study utilizes the decomposition properties of NaAc to provide an efficient and environmentally friendly new route for the removal of AlN and extraction of Al from SAD.