Clean energy infrastructure depends on chalcopyrite: the mineral that contains 70% of the world’s copper reserves, as well as a range of precious and critical metals. Smelting is the only commercially viable route to process chalcopyrite, where the oxygen-rich environment dictates the distribution of impurities and numerous upstream and downstream unit operations to manage noxious gases and by-products. However, unique opportunities to address urgent challenges faced by the copper industry arise by excluding oxygen and processing chalcopyrite in the native sulfide regime. Through electrochemical experiments and thermodynamic analysis, gaseous sulfur and electrochemical reduction in a molten sulfide electrolyte are shown to be effective levers to selectively extract the elements in chalcopyrite for the first time. We present a new process flow to supply the increasing demand for copper and byproduct metals using electricity and an inert anode, while decoupling metal production from fugitive gas emissions and oxidized by-products.

The promise of deploying green electric power faces the challenge of intermittency and integration within existing infrastructure. Meanwhile the global demand for metals, whether from primary or recycled sources, is steadily growing. The processes of the latter sector are not currently able to utilize a surge in inexpensive, clean electricity while being a large energy consumer (of the scale of 20 to 100MW). A window of opportunity exists where metal processing technologies can be re-designed to act as an electricity consumer or producer, depending on the electricity market conditions. In this work, we analyze and discuss conditions in which high temperature electrolysis techniques can fulfill this role.