Thiourea-assisted selective removal of arsenic from copper smelting flue dusts in NaOH solution

The selective removal of arsenic from copper smelting flue dusts is of great significance for environmental protection and resource recycling. This study employed thiourea assisted alkaline leaching to selectively extract arsenic from copper smelting flue dusts. The effects of NaOH concentration, thiourea concentration, temperature, leaching time and pulp density on the dissolution of arsenic, zinc, lead, copper and antimony in NaOH solution were studied. The results show that the addition of thiourea can effectively promote extraction of arsenic while inhibiting the leaching of zinc, lead and copper in copper smelting flue dust. Under the optimized leaching conditions, the leaching efficiencies of arsenic and antimony were 98.5% and 1.62%, respectively, while zinc, lead and copper were not leached. X-ray diffraction (XRD) analysis suggested that the addition of thiourea promoted the dissolution of insoluble arsenate minerals. The combined results of scanning electron microscopy (SEM), mineral liberation analysis (MLA), and X-ray photoelectron spectroscopy (XPS) demonstrated that thio-urea prevented sulfide products from forming a coating on arsenic surface. This work has important implications for the development of processing technologies for arsenic-containing materials.