Maximizing the recovery and throughput of a rougher flotation bank by improving the recovery of composite particles

Abstract

With decreasing ore grades, the cost of mineral processing has been escalating due to the high costs associated with grinding larger volumes of ores for liberation. To minimize the embodied cost, mined ores are usually coarse ground for rougher flotation, in which much of the waste (or ‘dead’) rocks are removed before regrinding the rougher concentrate to obtain the final product. Thus, the feed to a rougher flotation bank frequently consists of coarse particles that are poorly liberated and, hence, are not hydrophobic enough to be collected by air bubbles in the pulp phase and survive the froth phase without being detached.In the present work, we explored the possibility of improving the flotation of composite particles using Super Collectors that can increase the water contact angles (θ) of the copper-bearing mineral grains well above 90°. The efficacy of this approach has been tested in laboratory flotation tests, followed by a series of simulations using a flotation model. The model has been derived from first principles using the surface forces in wetting films as kinetic parameters. The major input to the simulator was the liberation matrix (mij) of a flotation feed and the various operating parameters. The simulations were carried out to obtain the grade vs. recovery curves for a low-grade (0.24 %Cu) porphyry copper ore feed with d80 = 288 µm. The simulations were carried out using a Super Collector that can increase θ of the chalcopyrite grains to 150°. The grade vs. recovery curves obtained from the simulation showed that the Super Collector can substantially increase the recovery of composite particles over the case of using potassium amyl xanthate (PAX) as a collector at approximately 40 % shorter retention times. The simulation results also showed that Super Collectors help minimize bubble coarsening and hence contribute to improving the coarse particle recovery.