Selective leaching of arsenic from enargite concentrate using alkaline leaching in the presence of pyrite

Alkaline leaching is a promising treatment to extract arsenic from enargite. This study investigates the feasibility of leaching enargite concentrate in the presence of pyrite in alkaline solution with sodium hydroxide only. Single factor and orthogonal experiments were performed to determine the effect of sodium hydroxide concentration, temperature, leaching time and liquid-to-solid ratio on enargite dissolution and to optimize leaching conditions. The results indicate that sodium hydroxide concentration has the greatest effect on arsenic dissolution from enargite, while the liquid-to-solid ratio has the smallest effect. Finally, over 99% of arsenic was removed using optimal conditions. Characterization of the leach residue by XRD and SEM-EDS analyses showed that enargite was converted into non-arsenic copper sulfides such as anilite (Cu7S4), geerite (Cu8S5) and djurleite (Cu31S16). This research is applicable to solving problems related to arsenic pollution.