The effect of breakage mechanism on the mineral liberation properties of sulphide ores

The effect of particle-bed breakage mechanisms on the liberation properties of ores remains unclear. Surprisingly few studies have been published in this area and limitations in liberation measurement techniques previously used have prevented definitive conclusions from being reached regarding whether particle-bed breakage enhances the liberation properties of mineral ores relative to conventional grinding mechanisms. In this study, two sulphide ores of differing textures were comminuted to various size distributions using impact and particle-bed breakage mechanisms in a hammer mill and a piston–die compression unit respectively. The liberation properties of the various discharge samples were then characterised using a mineral liberation analyser – a mineralogical characterisation system based on automated scanning electron microscopy. It was found that the size-by-size liberation properties of both valuable and gangue mineral phases were independent of both the method used to comminute the samples, as well as the particle size distribution of the final products. These effects are discussed in terms of how they may be exploited in liberation modelling and characterising comminution circuit performance.