Flotation of nickel-copper sulphide ore : optimisation of process parameters using Taguchi method

Abstract

Froth flotation is widely used for concentration of base metal sulphide minerals in complex ores. One of the major challenges faced by flotation of these ores is the ever varying grade and mineralogy. This therefore calls for a continual characterisation and optimisation of flotation parameters such that concentrator performance as a whole is always maintained. In this study, the robust Taguchi experimental design method was used to determine the optimum conditions for the flotation of nickel, copper and cobalt from a nickel-copper sulphide ore. The parameters investigated include collector dosage, percentage solids, depressant dosage and pH. The effects of these parameters at three different levels on the recovery of Ni, Cu and Co were investigated using an L9 Taguchi orthogonal array. The optimum conditions for the recovery of the base metals are collector dosage, 80g/t; pH, 10.15; %solids, 25; and depressant dosage, 100g/t. Relative significance of flotation parameters (based on difference between max and min. values) indicates that pH has the most significant effect on the recovery of nickel, copper and cobalt during flotation. Analysis of variance showed that pH and depressant dosage were the most significant parameters affecting the recovery of Ni, while collector dosage and percentage solids were insignificant. None of the tested parameters significantly affected copper recovery whilst pH was found to also significantly affect cobalt recovery