Effective Removal of Arsenic from Copper Matte by Sodium Carbonate

Residual arsenic in copper matte is a source of arsenic contamination in subsequent processes in the smelting section of copper pyrometallurgy. In order to solve the impact of arsenic in copper matte on the subsequent process of smelting, this study removes arsenic from copper matte by adding an arsenic removal agent to the molten copper matte. The results show that the most difficult arsenic phase in copper matte is the residual arsenic in copper-arsenic alloys, based on which sodium carbonate was selected as the arsenic removal agent. The arsenic content in the copper matte was reduced by 98% under the optimal experimental conditions of a reaction temperature of 1250 °C, 4% sodium carbonate addition, and a reaction time of 60 min. The experimental results of the reaction mechanism show that sodium carbonate plays two main roles in the process of removing the intractable residual arsenic in copper matte. One is that sodium carbonate has a low melting point, which enhances the fluidity of the reactants. The other is that it can provide oxygen to the reaction system and convert arsenic in the copper-arsenic alloy into gaseous arsenic and arsenate. This study can provide new ideas for controlling arsenic pollution in copper pyrometallurgy.