Effect and Mechanism of Combined Inhibitor of Zn²⁺ and Sodium Humate on the Flotation Separation of Fluorite and Calcite

The common calcite−type fluorite ore is difficult to separate by flotation due to the similar physicochemical properties of the surface of calcite and fluorite. The effect of the combined inhibitors of ZnSO₄·7H₂O and sodium humate on the selective separation flotation of fluorite and calcite was investigated, and the mechanism was analyzed by adsorption measurement, XPS detection, infrared spectroscopy analysis, and solution chemistry calculation. The experimental results showed that compared with the single sodium humate inhibitor, under the conditions of the combined inhibitors dosage of 20 mg/L when the mass ratio of sodium humate to ZnSO₄·7H₂O was 3∶1, sodium oleate dosage of 1.5×10⁻⁴ mol/L and pH 7, the difference of fluorite and calcite flotation recovery was increased from 41.8% to 70.31%. the zinc humate generated by the chemical reaction between sodium humate and Zn²⁺ increased the humate adsorption of the calcite surface compared with the single inhibitor, decreased the humate adsorption of the fluorite surface, increased more active sites on the surface of the fluorite and the sodium oleate adsorption, resulting in improving the selective adsorption of the combination inhibitors on the surface of the two minerals and achieving the purpose of flotation separation.