Mineral-content and particle-size effects on the colloidal properties of concentrated lateritic suspensions

The rheological behavior of concentrated lateritic suspensions from Cuba is affected by mineral composition and particle size. Electrophoretic mobility and yield stress were considered. The lateritic samples were found to be mostly composed of mixtures of serepentine and goethite in varying proportions. The flow properties of the lateritic suspensions are strongly affected by the mineral composition and particle size. This result was determined by comparison of flow properties of the bulk sample and the colloidal fraction. The electrokinetic curves suggest that heterocoagulation is present in all samples, with a zeta potential minimum at the isoelectric point (IEP), which varies with the serpentine to goethite ratio. A relationship between yield stress (tau(0)) and the sample volume fraction (phi) and particle size (d) was obtained at the IEP from the expression tau(0) = k phi(3)/d(0.5), With the constant k dependent on the sample serpentine to goethite ratio.