Pre-concentration of REE values from nepheline syenite rocks of western Odisha, India

Abstract

The rare-earth elements (REEs) have gained enormous economic and scientific attention due to their distinct properties and new applications. Nepheline syenite rock is an important primary source of rare earth minerals. The nepheline syenite rocks from the Rairakhol area, western Odisha, have been characterized for their rare earth mineralogical and textural characteristics. Preliminary beneficiation studies of these rocks were carried out to upgrade the REE values using falcon gravity separation and floatation technique. Hornblende, biotite, K-feldspar, albite, and nepheline are the major mineral constituents of the nepheline syenite where REE-bearing minerals occur as accessory minerals. The REE mineral phases present are zircon, sphene, apatite, allanite, britholite, and REE phosphate, with grain sizes ranging from 10 to 50 microns. Allanite and britholite occupy the intergranular spaces of major mineral phases and occur as thin lines or veins whereas sphene and zircon occur as inclusions within major mineral phases. The flotation study shows that the total REE content of the froth product could be enriched to 1696 ppm, which is three times more than the total REE content (563 ppm) of the feed sample.