Method of mineral separation by froth floatation

Claim 1

A froth flotation process for a mineral pulp having a first portion to be floated and a second portion to be separated, one of said portions being a desired mineral portion, said process comprising a. introducing said pulp into a cylindrical tank having a volume of at least 300 cubic feet and having a depth substantially equal to its diameter, said pulp containing between 7 and 50 percent by weight solids, at least 20 percent by weight of said solids being particles having a diameter less than 10 microns, b. mechanically agitating said pulp by means of an impeller centered in said tank and located at a distance above the bottom of said tank equal to between 10 and 25 percent of the height of said tank, and introducing air into said pulp at a location below said impeller and at a pressure just sufficient to overcome the pressure of the pulp in said tank, to maintain all of the particles of said pulp in suspension and to prevent their settling to the bottom of said tank, while floating at least a part of said first portion, said agitation and aeration being sufficient to float particles of said first portion of up to 1,000 microns diameter, c. the total power input to said pulp from said impeller and through said air being in the range between 0.010 and 0.035 horsepower per cubic foot of pulp, and the flow of said air being in the range between 0.05 and 0.30 cubic feet per minute per cubic foot of pulp, d. removing the floated part of said first portion from the surface of said pulp, e. and removing said second portion at a location substantially above said impeller but below the surface of said pulp, f. the feed rate of said pulp being at least 0.5 tons per day for each cubic foot of volume of said tank and the recovery of said mineral portion being at least 80 percent.