Abstract
Copper is an important metal in modern society and its contribution to sustainable development and the use of renewable energy is of great importance. As copper demand continues to increase while onshore resources are gradually declining, there is growing interest in offshore copper ores. Among the offshore resources, seafloor massive sulfides (SMS) deposits, which are found at water depths of 3000 m can be considered as a unique copper source. In the present study, an SMS sample from the Norwegian extended continental shelf was studied in laboratory scale and processed using a pyrometallurgical route to extract copper. It was found that the SMS sample consists mostly of chalcopyrite and contains ca. 17% Cu. The sample was first oxidatively roasted and then reduced using hydrogen gas at elevated temperatures. It was found that particle reduction of the oxide ore was possible, resulting in the formation of copper metal adjacent to unreduced iron oxide. Subsequent flux-smelting of the material at high temperatures yielded metallic copper that was well-separated from the non-metallic components of the reduced ore. The produced copper metal was found rich in copper, i.e. 98%, and contained minor amounts of impurities such as Fe, S. These results demonstrate the technical feasibility of hydrogen/based direct reduction combined with flux smelting as a promising low/carbon route for copper extraction from SMS ore.