Process and mechanism of hydrothermal stabilization for arsenic sulfide sludge containing elemental sulfur
Hui Xu, Liwei Yao, Qiujing Xu, Yun-yan WANG, Xiaobo Min, Yong Ke, Yongjian Luo, Jin-yao TANG, Si-ang PENG, Limin Zhang, Jiali Du
Abstract
An optimized hydrothermal treatment was employed to stabilize the arsenic sulfide sludge (ASS). Under the optimal conditions (160 °C, 2 h, liquid-to-solid (L/S) ratio of 1:1, and initial pH of 2), the leaching concentrations of As and Cd decreased from 504.0 and 12.0 mg/L to 1.23 and 0.03 mg/L of the treated ASS, respectively. The results indicate that the stabilization of the ASS was achieved through structure transformation from the particles into a bulk and the speciation transformation of As and Cd. Besides, sulfur in the ASS could significantly improve the stabilization property due to its melting and polymerization.