| الوصف: |
Apatite vein-type rare earth element (REE) ore from Mushgia Khudag, South Gobi, Mongolia, was studied in the field and laboratory during a joint research and development project of GTK Finland and CGL Mongolia in 2012–2014. Samples were examined by mineral liberation analysis, X-ray diffraction, electron probe micro-analysis (EMPA), X-ray fluorescence, and inductively coupled plasma mass spectrometry. Besides apatite veins, the deposit contains carbonatite; both rock types are associated with Mesozoic, ca. 140 Ma, syenite magmatism. The main REE carrier in the studied samples was apatite, with an average total REO content of 14.7% and the highest values reached 20.8%, accompanied by minor amounts of other REE phases such as monazite, cheralite, parisite, and synchysite. Apatite was typically found to occur as idiomorphic to hypidiomorphic grains varying from 0.1 to 4.0 mm in diameter. The whole rock REE concentrations range from 2.2% to 8.3%. In order to gain the knowledge for processing an extremely REE-enriched igneous-hydrothermal ore type, beneficiation studies by flotation were carried out at GTK and CGL for an apatite-syenite composite sample, with a modal apatite content of 11.7% and a total REE concentration of 1.8%. Flotation parameters, including the collector type and dosage, depressant type and dosage, and grinding size were tested. A concentrate with the contents of REE 9.3% and apatite 85.0% at REE recovery of 84.8% was obtained. |
