froth flotation is a process for separating minerals from gangue by taking advantage of differences in their hydrophobicity. hydrophobicity differences between valuable minerals and waste gangue are increased through the use of surfactants and wetting agents. the selective separation of the minerals makes processing complex (that is, mixed) ores economically feasible. the flotation process is used for the separation of a large range of sulfides, carbonates and oxides prior to further refinement. phosphates and coal are also upgraded (purified) by flotation technology.