Why is froth flotation used for some gold-bearing sulfide ores?

Froth flotation is used for gold-bearing sulfide ores because it allows for the effective concentration of the sulfide mineral fraction in which gold is often highly disseminated.1

In many endogenetic deposits, gold is trapped within base metal sulfide minerals, making it difficult to recover through simple gravity separation alone. By utilizing froth flotation, processors can take advantage of the specific physicochemical surface properties of these minerals—specifically their wettability—to separate them from other materials.123

This process is particularly important for managing refractory ores. These ores often contain sulfide minerals like pyrite, pyrrhotite, or arsenopyrite, which can interfere with subsequent extraction methods like cyanidation by consuming reagents or physically shielding the gold particles. By concentrating the sulfide fraction through flotation, the gold can be more efficiently isolated and subsequently liberated using oxidizing processes, such as roasting or pressure oxidation in autoclaves, before the gold is finally extracted.41