Design and operation characteristics of an improved laboratory flotation cell

Abstract

An improved laboratory froth flotation cell has been designed which eliminates many of the inadequacies of previous cells, and also allows the study of froth effects in flotation. Details of its design and functional features are discussed herein.The performance of the new cell is evaluated from results of replicate batch flotation tests, carried out by using china clay slurries. This evaluation indicates that reproducibility of results is satisfactory, the maximum deviation of cumulative recovery from the mean being only about six percent in the replicate tests.Hydrodynamic collision theories suggest that to float fine or colloidal particles, eg. china clay particles, it is necessary, first of all, to flocculate the particles so that optimum-size flocs form for attachment to bubbles in a flotation cell, which are typically 1–2 mm in diameter.Equilibrium floc size in a flotation cell depends on the shear rate distribution introduced by the impeller. Hence the shear rate distribution has been computed based on a three-zone distributed shear rate model, using measured value of power input to the cell. The results demonstrates that shear rates decline rapidly away from the impeller tip, allowing the formation of stable flocs.