A surface charge characterization device using sedimentation potential for single and mixed particle systems

An integrated device has been developed to measure sedimentation potential, conductivity and pH simultaneously of particulate systems. Maxwellʹs model was used to calculate volume fraction of solid from conductivity data. In this approach, all system variables are known and zeta potential can be calculated from the Smoluchowski equation. The technique is validated by comparing zeta potential vs. pH for alumina and silica suspensions with electrophoresis measurements. The technique was extended to mixed alumina/silica systems. Sufficient column height along with size difference between the two minerals allowed gravity fractionation during settling. Sedimentation potential measured over time identified the transition from one mineral to the next. XRD analysis supported the correlation between surface charge and sample composition. This is a step towards characterizing surface charge of mixed systems of interest in mineral processing.