EARTH

[1901-09-03] Hydrothermal Solidification of Arsenic Sulfide Sludge

○Hui Xu¹, Xiaobo Min^1,2, Yunyan Wang^1,2, Liwei Yao¹, Liyuan Chai^1,2 (1. Central South University, 2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution)

Chairman：Naoki Hiroyoshi（Hokkaido University）

Keywords:Hydrothermal treatment, Solidification, Arsenic sulfide sludge

Arsenic pollution has become a worldwide environmental challenge. In this study, solidification of arsenic sulfide sludge from a copper smelter by hydrothermal treatment has been proposed and investigated. Arsenic sulfide sludge was characterized by Inductively Coupled Plasma (ICP), Scanning Electron Microscope -Energy Dispersive Spectrometer (SEM-EDS), X-ray diffraction (XRD), et al. The results indicated that the main elements Arsenic and Sulfur contains were 35.1 wt% and 6.2 wt%, respectively, and the Arsenic leaching toxicity is 54 mg/L. Therefore it is classified as hazardous waste and must be consolidated and/or stabilized properly prior to final disposal. The parameters of the hydrothermal treatment were studied in detail. The optimal conditions were temperature of 16 ^oC, reaction time of 2 h, liquid-solid ratio of 1:1, the initial pH value of 2, the Arsenic leaching toxicity of the consolidated sludge decreased to less than 2 mg/L, which meets the Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes of China(GB18598-21.)