A novel method for dearsenization from arsenic-bearing waste slag by selective chlorination and low-temperature volatilization.

Abstract

Because of the widespread presence of arsenic in various smelting waste slags, it not only hinders the recycling and utilization of waste slag, but also causes serious pollution to the ecological environment. In this study, As2O3, the main form of arsenic in non-ferrous metal smelting slag, was used as the research object, and FeCl3 was used as the chlorination agent. As2O3 was selectively chlorinated to low-boiling-point AsCl3 gas which was easy to be volatilized and removed by chlorination roasting. According to the thermodynamic calculation results, the feasibility of FeCl3 as the chlorination agent for selective chlorination and low-temperature volatilization of dearsenization was analyzed. The TG-DTA diagram was analyzed by thermogravimetric experiment, and the mass change, endothermic and exothermic behaviors of the As2O3-FeCl3 system during the linear heating process were studied. The effects of roasting temperature, roasting time, and molar ratio of reactants on the chlorination-volatilization of the As2O3-FeCl3 system were investigated. The optimal chlorination roasting conditions were determined with a roasting temperature of 290-300 ℃, a roasting time of 50min, and a reactant FeCl3/As2O3 molar ratio of 4:1. The results of this study provided a novel idea for the removal of arsenic from smelting slag and dust, but the mechanism and process conditions of chlorination still need to be further studied and optimized.