Rheology as a diagnostic tool in the study of particle interactions relevant to mineral flotation

Abstract

The rheological behaviour of colloidal silica and fine sphalerite particles has been studied to improve our understanding of particle interactions within mixtures of particles having different size and surface properties. The objective of the present study was to develop a tool that can be used to explain particle interactions, especially those that are detrimental to flotation performance, such as interactions between hydrophilic gangue (e.g., silica) and hydrophobic valuable mineral (e.g., sphalerite). The influence of solids volume fraction, pH and reagent additions was investigated for both silica and sphalerite, individually as single minerals and in mixtures of these minerals. For the single minerals studies, it was observed that the maximum aggregation was achieved at a pH value close to the pHiep of each mineral, as predicted by DLVO theory. Copper (II) is extensively used as an activator to enhance surface hydrophobicity of sulphide minerals, hence improving flotation performance. It was observed that copper (II) addition steadily increased sphalerite yield value, but that it had no effect on silica slurries. The addition of 2400 g/t of copper sulphate increased fine sphalerite yield value by approximately 69% from its value in the absence of copper (II). The same trend was observed for collector addition, on which sphalerite yield value increased by 21% when 1000 g/t of sodium isopropyl xanthate was added.