Study on thermal behavior of hazardous substances in the process of preparing corundum from black aluminum dross

Abstract

The black aluminum dross (BAD) from aluminum recycling industry is considered to be a hazardous material due to containing a large amount of AlN and fluoride salt. The potential environmental problems caused by BAD restrict the sustainable development of the aluminum recycling industry. A calcining-leaching process for preparing α-Al2O3 by using BAD is proposed in this paper. The transformation mechanism of toxic substances is discussed in detail based on the analysis of TG-DTG-DSC&MS. The results show that the reaction between AlN and O2 occurs in the range of 500–1000 °C. Most of the gaseous products are N2, and there is also a small amount of NO. The average conversion rate is 0.087 mg/min. The average volatilization rate of chloride salt in BAD under Ar atmosphere is 0.065 mg/min, and the average volatilization rate under Ar + O2 atmosphere is 0.089 mg/min, which is slightly higher than that of pure Ar atmosphere. The BAD processed by calcination-leaching process contain more than 95 % corundum and magnesia-aluminum spinel, which can be used as high-quality raw materials for the preparation of refractory materials.