Reaction mechanism and distribution behavior of arsenic in the bottom blown copper smelting process

Abstract

The control of arsenic, a toxic and carcinogenic element, is an important issue for all copper smelters. In this work, the reaction mechanism and distribution behavior of arsenic in the bottom blown copper smelting process (SKS process) were investigated and compared to the flash smelting process. There are obvious differences of arsenic distribution in the SKS process and flash process, resulting from the differences of oxygen potentials, volatilizations, smelting temperatures, reaction intensities, and mass transfer processes. Under stable production conditions, the distributions of arsenic among matte, slag, and gas phases are 6%, 12%, and 82%, respectively. Less arsenic is reported in the gas phase with the flash process than with the SKS process. The main arsenic species in gas phase are AsS (g), AsO (g), and As2 (g). Arsenic exists in the slag predominantly as As2O3 (l), and in matte as As (l). High matte grade is harmful to the elimination of arsenic to gas. The changing of Fe/SiO2 has slight effects on the distributions of arsenic. In order to enhance the removal of arsenic from the SKS smelting system to the gas phase, low oxygen concentration, low ratios of oxygen/ore, and low matte grade should be chosen. In the SKS smelting process, no dust is recycled, and almost all dust is collected and further treated to eliminate arsenic and recover valuable metals by other process streams.