Evaluation of Different Dispersants on the Dispersion/Sedimentation Behavior of Halloysite, Kaolinite, and Quartz Suspensions in the Enrichment of Halloysite Ore by Mechanical Dispersion

Abstract

In this study, the dispersion properties of pure halloysite, kaolinite, and quartz minerals in halloysite ore were determined in the absence and presence of dispersants (sodium silicate, STPP, SHMP). First of all, the samples were characterized by chemical, mineralogical, BET, FTIR, and TEM analyses. Afterward, the physico-chemical properties of these minerals were investigated by zeta potential measurements and dispersion/sedimentation experiments in the absence and presence of the dispersants. The zeta potential measurements showed that the surface charges of all minerals changed from negative to positive as the PH changed from basic to acidic. The presence of dispersants at natural pHs indicated that the mineral surface charges tended to become more negative as the concentration increased in the zeta potential measurements. SHMP showed the most effect on the zeta potential. In the dispersion/sedimentation experiments, settling was slowed down with the use of dispersants. Finally, the dispersion properties of halloysite ore in the presence of dispersants were explored using mechanical dispersion and pulp viscosity experiments based on the amount of material passing to <38 μm size and the chemical changes in the materials. As a result of the mechanical dispersion tests carried out in the presence of dispersants (sodium silicate, STPP, SHMP), 71.3% of the material with 30.8% Al2O3 and 50.5% SiO2 content passed to <38 μm size without using dispersant, and 73.2% of <38 μm sized material with 35.5% Al2O3 and 46.1% SiO2 content was gained in the use of 7.5 kg/ton SHMP, which was determined as the optimum within the scope of the study. In conclusion, dispersant use enhanced the mechanical dispersion effect for plastic clay mineral separation from hard minerals in an aqueous medium.