Using CaO to stabilize arsenic sulfide slag by moderate temperature calcination

• DOI: 10.1007/s12665-017-6566-0
• Publication Date: 2017-03-27T03:32:11Z
• Authors: Qiong Lu; Hongxia Xiao; Ying Du; Dongyun Du
• Keywords: 01 natural sciences; 6. Clean water; 0105 earth and related environmental sciences

This study was conducted to investigate the stabilization of arsenic sulfide slag (ASS) with CaO calcinations at moderate temperature, including the effects of calcination temperature and different As/Ca molar ratios on arsenic leaching concentration. In the process of calcination for arsenic-contained waste, 90.95–97.23% of arsenic was reserved and the original waste was transformed into a dense and liquation state, which could physically wrap arsenic and reduce its leaching concentration. Meanwhile, the decrease in the As/Ca molar ratios was conducive to the formation of Ca5(AsO4)3(OH). When As/Ca molar ratio was less than 1:8, there was excessive CaO and the ASS samples stopped reacting with CaO. The results showed that the leaching concentration of arsenic was 4.08 mg/L when As/Ca molar ratio was 1:8 and the ASS sample was calcined for 2 h at temperature of 550 °C. In the process, arsenic’s chemical reaction and physical wrapping resulted in a remarkable decrease in its leaching concentration.