Stabilization of ferric arsenate sludge with mechanochemically prepared FeS2/Fe composites
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Central South University, Changsha 410083, China)
2. National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Central South University, Changsha 410083, China)
Abstract: FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge (FAS). The effects of preparation parameters on stabilization performance were investigated. The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5, milling time of 2 h, ball-to-material mass ratio of 15:1 and milling with stainless steel ball. Then, the composites were characterized by XRD, SEM, FTIR, etc. The physicochemical properties of FeS2/Fe mixture change dramatically, which is responsible for its excellent performance. Finally, the stabilization process of FAS was optimized. When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min, the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.
Key words: arsenic; ferric arsenate sludge; stabilization; mechanical milling; FeS2/Fe composites