Abstract: A flotation device (1) which includes a tank (2) to contain a slurry (3) incorporating minerals which are to be extracted. Aeration of the slurry (3) by suitable structure in the device produces a zone (11) of mineralised froth above the slurry (3). A launder (15) directs the mineralised froth away from the tank (2). At least one porous diffusion surface (16) in direct contact with the froth dispenses a washing liquid directly into the froth zone (11).