Why can flotation separate copper, lead, zinc, and pyrite from complex ores?

Flotation is the primary method for separating complex ores containing copper, lead, zinc, and pyrite because it exploits the distinct physicochemical surface properties of these minerals, specifically their wettability.1

Unlike gravity, magnetic, or electric separation methods, flotation allows for the precise manipulation of these surface conditions. By adding specific chemical reagents to a pulp of finely ground ore and water, processors can selectively alter the surfaces of mineral particles to be either hydrophobic (water-repelling) or hydrophilic (water-attracting).12

When air is bubbled through the mixture, the hydrophobic particles adhere to the air bubbles and rise to the surface as a froth, which is then skimmed off as a concentrate. Conversely, hydrophilic minerals remain in the pulp and sink. Through the use of these reagents, metallurgists can induce specific minerals to float while others remain submerged, enabling the separation of complex, intergrown ores into individual, high-grade concentrates that were previously difficult or impossible to process.21