Selective flotation of chalcopyrite and molybdenite: A review of depressant applications

Copper and molybdenum are critical strategic metals essential to emerging industries and national defense. They are primarily extracted from chalcopyrite (CuFeS 2 ) and molybdenite (MoS 2 ), respectively. Efficient and selective flotation of Cu–Mo sulfide ores—a key step in developing porphyry deposits—relies on the targeted modification of chalcopyrite and molybdenite surface properties by depressants. These depressants are generally classified as either inorganic or organic. To clarify the fundamental mechanisms of flotation and depression, this review examines the surface physicochemical properties of chalcopyrite and molybdenite. It also critically evaluates recent advances in depressant development, including inorganic agents, organic agents, and eco-friendly alternatives such as polysaccharides. The active components of current depressants are categorized, and a comprehensive analysis of their separation performance, toxicity, and cost in Cu–Mo sulfide ore flotation is presented. Finally, this review proposes a forward-looking framework for designing next-generation depressants through a multidisciplinary approach grounded in green chemistry. This perspective addresses current challenges while promoting sustainable and efficient exploitation of Cu–Mo resources.