Beneficiation of parisite-rich rare earth ore from the Nam Xe South deposit, Vietnam

Parisite-rich rare earth element (REE) ores from the Nam Xe deposit in northern Vietnam were beneficiated on a lab scale. Beneficiation experiments included, amongst others, sensor-based sorting, magnetic separation and flotation. Particular analytical focus during all experiments was set on the grain size, association and intergrowth of of the main REE carrier mineral parisite, which is finely intergrown with minerals of the barite-celestine solid solution series. All experiments were accompanied by mineral liberation analysis and chemical assays in order to be able to provide direction towards an optimal beneficiation strategy for this REE ore with its rather unique mineralogy. Special focus was set on the grain characteristics of the main REE carrier mineral parisite, which is finely intergrown above all with minerals from the barite-celestine solid solution series.
A multi-stage flotation technique was developed that uses an ambient rougher and a hot cleaner stage. Concentrates with 40% TREO grade with a total recovery of about 80% were achieved. It was shown that a combination with a sensor-based pre-sorting prior to the flotation can increase the input grade for flotation considerably by a nearly loss-free rejecting of virtually barren bed rock. The process combination developed holds good potential for further improvements.