Interparticle Forces Arising from Chemical Additives used in the Flotation of Zinifex Century Mineral Slurries
A range of additives such as conditioning, wetting, resurfacing, activating, depressing and flotation agents are added to mineral slurries in order to achieve selective flotation of a certain minerals. In the flotation of ZnS minerals, some of the additives used are copper sulphate activator, lime pH conditioning agent and sodium isopropyl xanthate (SIPX) collector. These additives adsorbed and produced a significant effect on the nature and strength of the surface forces interacting between the particles in the slurry. With fine mineral slurries flotation, a strong interparticle attractive force may increase greatly the strength of the froth structure carrying the floated mineral particles. This is undesirable as the structure of strong froth will not breakup easily under the weight of the mineral particles and this caused the froth to flow over the collector vessel built the around the flotation cell. Cu(II) and Ca ions formed hydrolysis products that adsorbed readily. Cu(II) formed such products at pH>5 and is also believed to form insoluble CuS on the mineral particle surface. Ca (II) formed hydrolysis product in the alkaline region. Adsorbed hydrolysis products are known to give rise to bridging and enhanced van der Waals attractions. In this study, the results showing the effect of Cu(II), Ca(II) and SIPX on the yield stress of mineral slurries from Zinifex Century mine were discussed. Yield stress is a indirect measure of the strength of the interparticle attractive forces. The yield stress was determined as a function of additive concentration and pH