Flotation of fine-grained materials

A process for treating a fine mineral consisting substantially completely of particles smaller than 50 microns equivalent spherical diameter in order to separate therefrom mineral impurities, which process comprises the steps of (a) conditioning the fine mineral in the form of an aqueous slurry, having a solids content of at least 30 percent by weight and containing a deflocculant, for a time sufficient to dissipate therein at least 25 horsepower hours of energy per ton of mineral solids;

• (b) mixing with the aqueous mineral slurry before or during the conditioning thereof a collector;
• (c) introducing the conditioned mineral slurry into a froth flotation cell having a central, internal, submerged impeller which comprises a base plate, to which there are attached a plurality of blades in radial arrangement, and a stationary cover plate separated from the tips of the blades by a small clearance;
• and (d) thereafter subjecting the conditioned aqueous mineral slurry to a pumping action in a froth flotation process in which the impeller of said froth flotation cell has a peripheral speed of at least 2,000 feet/minute and in which the aeration rate is at least 0.8 cubic feet of air per minute per cubic foot of froth flotation cell volume.