Photocorrosion of copper sulfides: Toward a solar mining industry

Copper sulfides such as chalcopyrite (CuFeS2), covellite (CuS) and chalcocite (Cu2S) are the most abundant, and thus mainly used, minerals in the copper mining industry worldwide. These metallic sulfides have semiconductor properties and they can be activated by sunlight. Some of them have been used as photocatalysts for water purification. However, photocorrosion phenomena decrease the photocatalytic activity and cause the leaching of metal ions into the solution. This phenomenon is undesirable for photocatalytic purposes, however, it could be used as a complementary method for sulfide minerals leaching. In this work, we studied photocorrosion assisted by solar light to evaluate the photoleaching of copper and iron from CuFeS2, CuS and Cu2S. In addition, heterogeneous photocatalysis using TiO2 was also evaluated. Copper and iron leaching was determined in sulfide mineral suspensions under visible light irradiation. For the first time, it is demonstrated that the photocorrosion of copper sulfides occurs under controlled conditions. This proof of concept demonstrates that photocorrosion and photocatalysis could be considered for copper leaching from copper sulfide minerals. This novel study could generate a new route for copper leaching using solar light under mild conditions with less environmental impacts.