Efficient Leaching Arsenic and Recovering Antimony from High-Arsenic Soot

A method for removing arsenic (As) from high-As soot and recovering antimony (Sb) is proposed. The process consists of two stages: leaching As and Sb from high-As soot with sodium sulfide-sodium hydroxide; and adding aluminum (Al) sheet to the leachate to recover Sb, and treating the solution after recovering Sb by the lime-precipitation method. Under the conditions of 1.1 sodium sulfide excess factor, 25 degrees C temperature, 15 g/L sodium hydroxide, 6:1 liquid to solid ratio, and 2-h reaction time, the leaching rates of As and Sb were 95.11% and 75.28%, respectively. Furthermore, under the conditions of 1 g Al sheet addition, 35 degrees C temperature, and 2-h reaction time, Sb recovery achieved 98%, while Sb concentration in recovered Sb slag exceeded 85%. After recovering Sb, an adequate amount of lime was added to the solution to precipitate aluminide and arsenide. The kinetics of As leaching in high-As soot were also investigated, and the apparent activation energy was found to be 4.062 kJ/mol, indicating that As leaching was a solid film internal diffusion process.