Effect of acid corrosion on the surface roughness and floatability of magnesite and dolomite

Abstract

To modify surface roughness and improve flotation performance, hydrochloric acid etching pretreatment was performed on magnesite and dolomite. Flotation tests disclosed that acid corrosion improved the flotation kinetics and flotation recovery rates of magnesite and dolomite. Under pulp pH 10 and sodium oleate (NaOl) concentration 20 mg·L−1, the flotation recovery rates of magnesite and dolomite after acid etching increased by 31.05% and 29.20%, respectively, compared with those before acid etching. Adsorption density tests proved that the adsorption density of NaOl on magnesite and dolomite was higher after acid etching than before acid etching, implying that acid etching drives NaOl adsorption. Zeta potential analysis revealed that acid etching reduces the point of zero charge of magnesite and dolomite. Atomic force microscopy and X-ray photoelectron spectroscopy results demonstrated that acid corrosion modified the surface roughness of magnesite and dolomite, increasing the magnesium (Mg) content on the magnesite surface and the calcium and Mg contents on the dolomite surface. Contact angle measurements indicated that acid corrosion slightly reduced the contact angle between magnesite and dolomite. With NaOl present on the surface, the contact angles of magnesite and dolomite after acid etching significantly increased compared with those before acid etching. Therefore, acid etching is effective in improving the floatability of magnesite and dolomite.