Flotation studies of monazite and dolomite

Rare earth elements (REE) are key components of many emerging green technologies. This leads to an increase in demand for REE, hence to the development of new deposits, such as the Niobec carbonatite rare earth deposit in Quebec, Canada. One of the valuable minerals in this deposit is monazite, one of the primary sources of REE. Although there has already been previous research investigating monazite flotation, most of these are focused on monazite from heavy mineral deposits. Since minerals from different deposits may behave differently, it is important to investigate the flotation behavior of monazite from carbonatites as well. This work investigates the surface properties of monazite from carbonatite deposit through zeta potential analyses. Electrophoretic zeta potential measurements were conducted to identify the interaction of monazite and dolomite, a gangue mineral commonly associated with carbonatites, with different collectors (namely sodium oleate, organic phosphoric acid and benzohydroxamic acid). Floatability of the minerals were analyzed through microflotation tests, to obtain the potential conditions for effective separation. Zeta potential measurements of monazite and dolomite showed that the isoelectric point (IEP) for both minerals occur at a pH of approximately 5. Sodium oleate, benzohydroxamic acid and Flotinor 1682 (organic phosphoric acid) have been shown to adsorb on to monazite at pH 7. The results suggest that benzohydroxamic acid can be selective at neutral pH condition, sodium oleate can be potentially used in reverse flotation of monazite in acidic condition and Flotinor 1682 (organic phosphoric acid) can be a potential collector for monazite. However, the use of reagents such as activators and depressants is suggested to achieve a more selective separation.