Abstract: Finely-divided ore is beneficiated in a froth floation process carried out in a closed vessel containing a medium on which a froth is formed as a result of the injection into the bottom of the vessel of a gasified slurry which percolates upwardly and circulates in the medium. A lighter fraction of the ore froths on the surface of the medium and is conveyed hydraulically into a receiver wherein the gaseous component is separated from the froth and is recycled through a compressor for mixing with an ore slurry supplied to mixing nozzles which inject the slurry into the medium. A heavier fraction of the ore sinks into the medium and is collected by and exhausted from the vessel through an underflow siphon located between the surface of the medium and the mixing nozzles. A wet scrubber flows a series of fluid jets in a horizontal grid pattern underneath the surface of the medium for limiting the upward percolation of the heavier fraction to the surface.