Volatilization Mechanization and Behaviors of Arsenic from High Arsenic-Containing Copper Smelting Ash by Sulfurization Roasting.

Arsenic species in copper smelting ash have an important effect on recovery of valuable metals and ecological conservation. In this study, a new process for removing and collecting As by sulfurization roasting and then shock cooling was proposed. The Ellingham diagrams of the reactions among arsenic species, sulfuric acid and carbon and the As-O-S system isothermal dominance zone diagram were developed using HSC 6.0. They indicate that temperature and atmosphere were important for removal of As. XPS results show that As, Zn, Bi and Pb mainly existed in the form of oxides and sulfates in the ash. TG–DSC results indicate that the ash had four stages of thermogravimetry and heating rate affected the removal of As. The addition of sulfuric acid and anthracite, time and temperature had important effects on As removal. The optimum conditions were as follows: 350°C, 3 h, 10% anthracite and sulfuric 0.3 ml/g acid addition. Under these conditions, > 95% of As was volatilized and > 99% of As was collected. XRD result of the roasted slags shows that the diffraction peaks of As-related phases were disappeared. SEM/EDS results of off-gases condensates show that the condensates were cubic crystals of As₂O₃ containing 64.7 ± 0.6% As. [ABSTRACT FROM AUTHOR]