Rheological properties of concentrated lateritic suspensions

Abstract

The rheological and surface properties of concentrated suspensions of lateritic minerals from Cuba have been studied. The physicochemical analyses indicated that the samples were mainly composed by different proportions of serpentine-goethite mixtures. The rheology of each lateritic suspension was determined as function of solid concentration and pH. Flow curves for samples containing 25 to 36% by weight of solid were interpreted following the Bulkley Hershel or Casson models. For each sample, the maximum in the yield stress and viscosity occurs at pH values close to the isoelectric point (IEP), which takes place between 4 and 9 depending on the serpentine-goethite ratio. This wide range in stability with pH explains the variability observed in the suspensions depending on their mineralogical composition. At pH values outside the IEP a low viscosity is obtained in each sample and the suspensions are well dispersed.