Effects of Sodium Silicate on Flotation Separation of Sphalerite and Dolomite and Its Mechanism

Sphalerite often co-exists with dolomite, a carbonate mineral containing calcium and magnesium. In the flotation process of sphalerite, dolomite entering into the concentrate will have a considerable negative impact on the subsequent smelting. Therefore, the effects of sodium silicate on the flotation separation of sphalerite and dolomite and its mechanism were investigated in this study. It was found that alkaline conditions and the addition of sodium silicate were conducive to the flotation separation of sphalerite and dolomite. Under alkaline conditions, sodium silicate improved the hydrophobicity of sphalerite and the slurry turbidity. The yield stress and apparent viscosity were significantly reduced when dolomite was present in slurry. In addition, the surface electrical properties of dolomite shifted from positive to negative with an increase in the dosage of sodium silicate at pH 11, leading to electrostatic repulsion between sphalerite and dolomite. EDLVO results indicated that the total interaction energy between dolomite and sphalerite particles was repulsive when sodium silicate was present. This study provided a theoretical basis for the flotation separation of sphalerite and dolomite.