ABSTRACT
All techniques or methods of separation, whether physical or chemical, are based on differences in the properties of the materials. Flotation is a process of separation and concentration based on differences in the physicochemical properties of interfaces. Flotation can take place, in principle, either at a liquid-gas, a liquid-liquid, a liquid-solid or a solidgas interface. The latter possibilities are less investigated, but a number of examples are known. These include oil flotation, which takes place on the interface between oil and water, and carrier flotation, in which colloidal particles attach themselves onto the surface of larger particles (carrier minerals) and float together with the carrier minerals. Froth flotation, and film (skin) flotation are the best examples of flotation taking place on a liquid-gas interface. In froth flotation hydrophobic particles, which may be molecular, colloidal, or macro-particulate in size, are selectively adsorbed or attached to and remain on the surface of gas bubbles rising through a suspension, and are thereby concentrated or separated from the suspension in the form of froth. Film flotation takes place on a free water surface. In this flotation process hydrophobic particles float on the free surface and are thereby separated from nonfloatable hydrophilic particles, which sink into the liquid phase.
