Minimization and stabilization of smelting arsenic-containing hazardous wastewater and solid waste using strategy for stepwise phase-controlled and thermal-doped copper slags.

Abstract

Minimization and stabilization of arsenic-containing smelting wastewater and residue is of crucial issue to resolve the arsenic contamination. Calcium arsenate is a typical precipitate produced from disposal of smelting acid wastewater. However, it suffers from poor stability and large quantity in the aqueous environment. Copper slags, as for rich-iron species materials, are disposed of in landfills or open-air tailing ponds, which are another waste material that have not been effectively utilized for reuse application. In this study, strategy for sequence of phase-controlled and thermal-doped copper slag technique was used as the efficient means of minimization and stabilization of arsenic-bearing resides. Detailed results were showed that stepwise phase precipitation significantly reduced the formation of hazardous solid waste; the total solid waste was reduced 47.0 wt% because the gypsum was separated from arsenic calcium residues through two-step methods. Subsequently, solid waste stabilization was achieved by using thermal-doped slag, and the high yield of magnetite (75.6 wt%) and fayalite (22.7 wt%) was produced from copper slags. It was proved that these iron-rich species displayed the remarkable performance to stabilize arsenic due to the formation of Fe-As-Ca-O complex; compared with the raw solid waste, the arsenic leachability was decreased from 280.75 to 1.05 mg/L via copper slag stabilization process. The immobilized arsenic content was 25.0 wt%. Overall, the proposed strategy for stepwise phase-controlled and thermal-doped copper slags was a potentially effective strategy for reducing emissions and pollution of arsenic-containing wastewater and residue.