Liberation-limited grade/recovery curves for auriferous pyrite ores as determined by high resolution x-ray microtomography

As in all flotation separations, the separation efficiency for the flotation of pyrite from auriferous pyrite ores depends on the flotation conditions and the particle properties of the feed ore. Liberation and texture are particle properties that refer to release of valuable minerals from gangue waste minerals during size reduction and the arrangement of these mineral phases within the particles. Separation efficiency may be impacted significantly by variation in liberation and the texture of locked particles, even with locked particles having the same overall composition. Not all locked particles of the same composition will have the same flotation response. Their flotation response will also depend on their texture. Now, analysis of liberation and texture is possible using High Resolution X-ray Microtomography (HRXMT). This analytical technique can provide quantitative information on liberation and exposure (texture) for each particle in a given particle population. Products from the flotation of two types of auriferous pyrite ores, both batch scale experiments and plant operations, were analyzed by HRXMT. In this way, the degree of liberation of the pyrite grains was determined. The liberation-limited grade/recovery curves were calculated for each ore. The liberation-limited grade/recovery curves are used to determine the limits of the separation efficiency. Also, the characteristic texture of particles in each flotation product was determined and the effect of these textural features on the flotation separation efficiency discussed. It was found that the separation efficiency of auriferous pyrite was controlled principally by factors other than liberation. In general the texture analysis revealed that the pyrite-containing particles with a high exposure of pyrite grains at the particle surface have a better possibility of being recovered in the concentrate during flotation.