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Abstract
The rheological behaviour of galena, sphalerite and gibbsite mineral particle suspensions has been studied using a concentric cylinder rheometer. The influence of pulp density, pH, salt concentration and processing reagents on the rheology and particle interaction behaviour is reported. The Bingham or extrapolated yield value is used to characterise particle interactions in both a qualitative and quantitative manner. For many mineral suspensions, over a wide range of conditions, the rheological behaviour can be described in terms of electrostatic and dispersive interactions, i.e., DLVO behaviour. In some circumstances however, non-DLVO interactions are observed, the sign and magnitude of these depend primarily on the mineral particle surface chemistry.
For ultrafine galena (PbS) particle suspensions an attractive, non-DLVO interaction is observed which increases with decreasing pH. This finding correlated with flotation behaviour and a hydrophobic interaction was confirmed. For colloidal gibbsite (Al(OH)3) suspensions a repulsive non-DLVO interaction becomes apparent at pH values greater than 10. Hydration or steric interactions are thought to be responsible for this behaviour.
