Ultrasonic-enhanced selective sulfide precipitation of copper ions from copper smelting dust using monoclinic pyrrhotite

The sulfide passivation film produced on the surface seriously prevents further reaction in the process of using monoclinic pyrrhotite (MPr) to treat heavy metal ions in wastewater. Ultrasonic technology was introduced to assist MPr to recover the copper ions. XPS result proves that CuS products exist on the surface of MPr. XRD and SEM results show that the CuS on the particles' surface is stripped under ultrasonic condition. The kinetics results indicate that the reaction under both conventional and ultrasonic conditions conform to the Avrami model. The reaction process changes from diffusion control to chemical reaction control under the ultrasonic condition as the solid layer is stripped off. The presence of ultrasonic significantly reduces the acidity and temperature required for the reaction and enhances the utilization efficiency of MPr; by controlling the amount of MPr, the removal rates of copper and arsenic in copper smelting dust leachate exceed 99% and 95%, respectively.