Selective flocculation of celestite from celestite-calcite fines

Abstract

In this study, selective hydrophobic flocculation of celestite with sodium dodecyl sulphate (SDS) from the mixtures of celestite and calcite was investigated using sodium silicate as inorganic dispersant. Prior to the selective flocculation process, the critical surface tension of wetting (c) values of these minerals were determined as a function of SDS concentration. A significant difference between the c values of celestite and calcite was found at concentrations around 20 mg/dm³, indicating that celestite particles can be selectively flocculated from the mixtures at these concentrations. Then, the effects of pH, dispersant concentration, flocculation and settling times on the selective flocculation of celestite mineral were studied. Experiments carried out with sodium silicate at optimum conditions yielded a concentrate, which is flocculated material, assaying 85% SrSO₄ with a recovery 90% and separation index of 0.90 from a mixture containing 50% SrSO₄.