Frothers are added to stabilise bubble formation in the pulp phase, to create a reasonably stable froth to allow selective drainage from the froth of entrained gangue, and to increase flotation kinetics. The importance of the froth phase to flotation performance is being increasingly recognised and the factors affecting froth stability are being extensively researched (Harris 1982; Melo and Laskowski 2003, 2005; Hatfield et al., 2004; Barbian et al., 2005).

Plant practice involving frothers has been reviewed by Crozier and Klimpel (1989).

Frothers are in many respects chemically similar to ionic collectors, and, indeed, many of the collectors, such as oleates, are powerful frothers, being in fact too powerful to be used as efficient frothers, since the froths which they produce can be too stable to allow efficient transport to further processing. Froth build-up on the surfaces of thickeners and excessive frothing of flotation cells are problems occurring in many mineral processing plants. A good frother should have negligible collecting power, and also produce a froth which is just stable enough to facilitate transfer of floated mineral from the cell surface to the collecting launder.

Frothers are generally heteropolar surface-active organic reagents, capable of being adsorbed on the air-water interface. When surface-active molecules react with water, the water dipoles combine readily with the polar groups and hydrate them, but there is practically no reaction with the non-polar hydrocarbon group, the tendency being to force the latter into the air phase. Thus the heteropolar structure of the frother molecule leads...