Enhanced Chloride Leaching of Chalcopyrite Using Sodium Chloride and Sodium Chlorate as Oxidizing Agents

Chalcopyrite (CuFeS₂) is recognized as the most refractory copper sulfide mineral toward leaching, primarily due to the formation of a passivating surface layer that inhibits dissolution in sulfate media. To overcome this limitation, chloride ions have been widely introduced as catalytic additives to accelerate the dissolution process. In the present study, the chloride leaching behavior of chalcopyrite from a low-grade ore of the Sarcheshmeh copper mine was systematically investigated using sodium chloride and sodium chlorate as oxidizing agents in sulfuric acid solution. The effects of temperature (25, 40, and 50 °C), sodium chloride concentration (0, 0.5, and 1 M), and sodium chlorate concentration (0, 0.5, and 1 M) were evaluated. The results revealed that both temperature and oxidant concentration significantly affected copper recovery, increasing from 37% to 75% as the chlorate concentration rose from 0 to 0.5 M. These findings demonstrate the synergistic effect of chloride and chlorate ions in enhancing chalcopyrite dissolution under mild leaching conditions.