Improvements in Froth Flotation Apparatus

1,172,928. Mixing and aeration apparatus. RESEARCH & DEVELOPMENT PTY. Ltd. 19 Dec.. 1967. No. 57655/67. Headings B1C and B2H. Froth flotation apparatus comprises a rotor 1 mounted on a hollow shaft 2 down which gas is induced or forced to form a liquid-free zone 21 surrounded by a mixing zone 23. Fixed baffles 11 and radially adjustable baffles 12 are mounted on the cell bottom whereby mixture flows inwardly from the mixing zone 23 to form a secondary circulation 26 (see also Fig. 3, not shown), as well as outwardly. The vanes 11, 12 may be curved in plan (see Fig. 2, not shown); the outer edges of the vanes 12 are displaced rearwardly with reference to the direction of rotation of the rotor. They have a height of about 1/6 and clearance of 1/20 of the lower diameter of the rotor; the diameters of the circles on which their outer and inner edges lie are about 0.65 and 1.1 thereof; and the angle of their sloping edges is about 40 degrees to the horizontal. The circulation flows will take the form of a torcus in which each fluid element traces a helical path.