Surface Chemistry and Flotation Behaviors of Monazite–Apatite–Ilmenite–Quartz–Rutile–Zircon with Octanohydroxamic Acid

Global demand and consumption of rare earth elements and compounds have led to increasing research to further our understanding of their beneficiation and recovery. Monazite is the second-most important rare earth-bearing mineral that can be exploited. In this study, the surface chemistry of monazite in terms of zeta potential, adsorption density, and flotation responses using octanohydroxamic acid is determined. Apatite, ilmenite, quartz, rutile, and zircon are the minerals that frequently occur with monazite, and hence they were chosen as gangue minerals in this study. The isoelectric points of monazite, apatite, ilmenite, quartz, rutile, and zircon are 5.3, 8.7, 3.8, 3.4, 6.3, and 5.1, respectively. Thermodynamic parameters of adsorption were evaluated. Ilmenite has the highest driving force for adsorption. Adsorption density value shows that octanohydroxamic acid adsorbs onto monazite and its gangue minerals. This observation was further confirmed by microflotation experiments. Increasing the temperature to 80 °C raises the adsorption and floatability of monazite and gangue minerals, which does not allow for separation. Monazite is best recovered at a pH range of 7.5–10. Appropriate use of depressant is recommended in order to enhance the separation of monazite from its gangue.