A study of flotation characteristics of monazite, hematite, and quartz using anionic collectors

Rare earth element (REE) minerals found in most South Australian ore deposits are in complex association with gangue minerals, typically hematite and quartz. Monazite, a phosphate mineral containing mainly light REEs, is one of the principal minerals found in South Australian REE-bearing deposits. Froth flotation, which exploits the differences in the physicochemical properties of minerals, has proven to be effective in the beneficiation of REE minerals. The physicochemical properties of monazite, hematite, and quartz including zeta potential, contact angle, and floatability were determined in this investigation. Sodium oleate, sodium dodecyl sulphate, and hydroxamic acid were employed as collectors. Electroacoustic zeta potential measurements were used to identify the interaction between monazite, hematite, and quartz and the selected collectors. The capillary rise method was used to determine the contact angle of the three minerals. Single mineral flotation using Denver microflotation cell was carried out to confirm physicochemical properties measured. It is shown that the contact angle of the minerals is dependent on the collector type used. The isoelectric point (IEP) of monazite, hematite, and quartz occurred at pH of 6.5, 6.9, and 2.2, respectively. The zeta potential results also suggest that the collectors chemisorb onto monazite and hematite surfaces with a corresponding change in IEP values. Single mineral flotation results demonstrated that monazite and hematite could be floated by the selected collectors; however, low or no quartz flotation was observed in some cases. Results from electrokinetic and contact angle measurements are consistent with that of the floatability of monazite, hematite, and quartz.