process for selectively separating hydrophobic materials from hydrophilic. So a sulfidic copper ore consists only to some percent of valuable copper minerals but mainly of gangue. The gangue material is mainly oxidic. By a froth flotation process sulfidic and oxidic material are separated. The process is carried out in stirred vessels, where a slurry of milled ore is mixed with water and some chemicals (surfactants and additives). Then air is blown into the slurry forming a froth on the surface. As air and sulfides are hydrophobic the copper sulfide particles are attached to the air bubbles and float to the surface. Then the foam (froth) is separated and filtered and copper concentrate is formed. This contains only very small amounts of gangue and lead - in the case of chalcopyrite to a material with about 20-33 % Copper.
synonym:: froth flotation
note: In some cases a two stage flotation is used to separate not only copper sulfide from gangue but also molybdenum from copper.