Beneficiation Studies of a Rare Earth Ore from the Olserum Deposit

Abstract

The Olserum deposit located in Sweden hosts an indicated mineral resource of 4.5 million tonnes at 0.6% total rare earth oxides (TREO), exhibiting a relatively high proportion of heavy rare earth elements (HREE). The mineralogy and beneficiation of a composite drill core sample from the Olserum deposit were studied. Monazite and xenotime were found by the mineralogical analyses to be the target minerals for beneficiation of REEs and most (96.9%) of REEs in the ore are carried by monazite (68.5%) and xenotime (28.4%). Because xenotime carries 84.7% of heavy REEs (Y, Gd, Dy) in the ore it is more valuable mineral than monazite. A beneficiation process was developed which includes grinding, wet low intensity magnetic separation (WLIMS) for removal of magnetite and REEs flotation consisting of one stage of roughing and two stages of cleaning. Selective flotation collector of REE minerals and suitable grinding size of feed material were determined by testwork. The REE concentrate and tailings were chemically and mineralogically characterized. The studies of process mineralogy showed that the REE-bearing minerals , monazite and xenotime , and apatite were successfully enriched from the concentrations of 0.6%, 0.31% and 2.6% in the feed to those of 17.0%, 8.9% and 65.0% in the concentrate with the recoveries of 79.0%, 81.3% and 71.0%, respectively.