Recovery of coarse particles in the froth phase – A case study

This study explores the role of the froth phase in the collection of particles that are introduced into the froth layer in a flotation cell. A bench-scale flotation cell was tested at an operating concentrator, using a feed taken directly from the plant. The equipment was constructed so that dropback from the froth phase was separated from the pulp phase. A stream taken from the plant cleaner feed was floated in the apparatus, thus creating a stable froth layer. A separate sample was taken from the feed to the plant rougher cells, and added directly into the froth layer in the experimental apparatus. The performance of the test cell was evaluated, in terms of the copper grade and recovery on a size-by-size basis. The experimental variables were the superficial gas velocity, the froth depth and the location of the feed distributor relative to the overflow lip of the test cell. The results show that the froth is an effective medium for the recovery of coarse particles that are poorly recovered in conventional flotation cells. This was especially evident when the particles were just introduced below the froth surface.