Abstract: The present invention is a process for recovering valuable minerals using air lift concentration and progressive ore reduction. The ore is ground to a relatively coarse size, the ground ore is classified, and the underflow fraction floated to produce concentrate, middlings, and tailings fractions. The middlings fraction can be reground to liberate the valuable minerals and subjected to further air lift concentration. The classifier overflow fraction is passed through additional classifiers, the underflow fractions of which can be reground and refloated. The overflow fraction of the last classifier can be subjected to flotation to further enhance recovery.

Abstract: A mineral processing device for floating relatively large particles and middling particles is disclosed. The device provides a uniform upward flow of pulp in a flotation zone. Gas bubbles are introduced into the pulp with minimal agitation. Agitation in the flotation zone is also controlled by a plate with a multitude of holes of varying size. The upward flow velocity in the flotation zone is controlled by means of a variable speed impeller and an adjustable partition. Further, a flotation process utilizing uniform upward flow is provided.