Adsorption and depression mechanism of an eco-friendly depressant dextrin onto fluorite and calcite for the efficiency flotation separation

Abstract In this work, dextrin, an effective and eco-friendly organic compound, was used to separate fluorite from calcite. The depression performance and adsorption mechanism of it on the calcite surface were investigated by flotation experiments, contact angle measurements, Fourier transform infrared spectroscopy (FTIR) measurements, and X-ray photoelectron spectroscopy (XPS) analyses. The results showed that fluorite can be selectively separated from calcite with 10 mg/L dextrin and 2×10-5 mol/L sodium laurylsulfonate (SLS). Additionally, the contact angle, FTIR and adsorption measurements indicated that the –OH group of dextrin might be adsorbed on Ca sites on the surface of calcite through chemical bonds. The inner electron binding energy of Ca2+ in fluorite is larger than the inner electron binding energy of Ca2+ in calcite, which makes it more difficult to form chemical bonds. Therefore, the chemical adsorption of dextrin on the surface of calcite is stronger than that on the surface of fluorite. Both SLS and dextrin can be adsorbed on the surface of calcite. Because dextrin is a strong hydrophilic compound, the hydrophilicity caused by dextrin is stronger than the hydrophobicity caused by SLS, so dextrin can selectively depress calcite.