Effect of ultrasonic treatment on the surface roughness and floatability of magnesite and dolomite

Abstract

This study focuses on the effects of ultrasonic treatment on the surface roughness, flotation behavior, and flotation separation efficiency of magnesite and dolomite in a sodium oleate (NaOL) system. Flotation experiments show that ultrasonic treatment improves the flotation recovery and separation efficiency of these two minerals. We can achieve flotation separation of magnesite and dolomite using 4-mg/L sodium hexametaphosphate. After ultrasonic treatment, magnesite and dolomite achieved flotation recovery of 93.41% and 25.12%, respectively, with a float difference of 68.29%. Atomic force microscopy reveals that ultrasonic treatment increases the surface roughness of both magnesite and dolomite, but the increase is greater for the former. Adsorption capacity tests and contact angle measurements indicate that ultrasonic treatment increases the adsorption capacity of the minerals for NaOL as well as their contact angles in the NaOL system and promotes their flotation. X-ray photoelectron spectroscopy reveals that ultrasonic treatment increases the content of Mg exposed on the magnesite surface and contents of Ca and Mg exposed on the dolomite surface. NaOL is more easily adsorbed on the surface of ultrasonically treated magnesite than on the surface of dolomite. Turbidity analysis reveals that the turbidity of the mixed ore of ultrasonically treated magnesite and fine-grained dolomite is lower than that of the mixed ore of untreated magnesite and fine-grained dolomite; the covering effect of fine-grained dolomite on the surface of ultrasonically treated magnesite is stronger than on the surface of untreated magnesite. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses show that fine-grained dolomite undergoes mud covering on the magnesite surface. Ultrasonic treatment not only improves the covering of fine-grained dolomite on the magnesite surface but also affects the form of this covering.