Effects of the Cooling Rate on the Solidified Structure and Toxic Leaching of an Arsenic Matte

The conversion of arsenic-containing waste residues into arsenic matte can be an important direction for arsenic treatment. In this paper, different parts of factory samples were first taken for study, and it was found that the leaching amount of arsenic at the chilling layer is noticeably low. Then, the effects of the cooling rate on the phase, microstructure, and chemical compositions and the subsequent toxicity leaching of the arsenic matte were studied. The results show that the alloy structure was obviously refined and the cavity size was also significantly reduced with an increase in cooling rate. Many large-strip FeS and arsenic-containing iron solid solutions were embedded in the matrix (Fe2As) of the furnace-cooled and air-cooled samples; additionally, the Fe–As–S phase was probably caused by an insufficient phase separation of FeS from Fe2As in the rapid cooling process of die cooling and water cooling. FeS in the factory samples was dissolved in the leaching solution, while Fe2As could resist the corrosion of the leaching solution; therefore, it was speculated that the dissolution of arsenic was caused by the dissolution of FeS. The leaching mechanism was also discussed in this paper. The cooling rate affects phase, microstructure, and chemical compositions and toxicity leaching of the arsenic matte, which speculated that the dissolution of arsenic was caused by the dissolution of FeS