Process and mechanism of hydrothermal stabilization forarsenic sulfide sludge containing elemental sulfur
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China;
3.The High School Attached To Hunan Normal University, Changsha 410006, China)
2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China;
3.The High School Attached To Hunan Normal University, Changsha 410006, China)
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.
Key words: hydrothermal stabilization; arsenic sulfide sludge;elemental sulfur;structure transformation