Flotation separation of bastnaesite from monazite using depressant dextrin hydrate and its depression mechanism

Abstract

The flotation separation of bastnaesite and monazite is challenging due to their similar physicochemical properties and floatability. In this work, an environmentally friendly depressant, dextrin hydrate (DH), was introduced for the flotation separation of bastnaesite from monazite using caprylhydroxamic acid (CHA) as the collector. The flotation behavior of bastnaesite and monazite in the absence and presence of DH was studied by micro-flotation tests. The mechanism was investigated by Zeta potential, Fourier infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The flotation results showed that monazite recovery decreased by 68.47% when the pH was 9.0 ± 0.2 and the amount of DH was 2.2 mg/L. In contrast, the bastnaesite recovery only exhibited a slight reduction of 7.98% under these conditions. Zeta potential analysis showed that DH had a strong effect on the subsequent adsorption of CHA on the surface of monazite but a minor effect on bastnaesite. FTIR and XPS analysis further confirmed that the chemisorption of DH on the Ce sites of monazite occurred. For bastnaesite, the adsorption of CHA still could be detected, making the bastnaesite well floatable.Therefore, the efficient separation of bastnaesite from monazite could be achieved with the DH as a selective depressant.