Black sands from the area of Loutra Eleftheron in Kavala, northern Greece, are known for their enrichment in rare earth element (REE) bearing minerals. REE are critical metals used in advanced applications and are of high demand in the European Union (EU). This work employs scanning electron microscopy (SEM), X-ray diffraction and XRF analysis to characterize the products from laboratory grain size separation and magnetic separation (high intensity magnetic separators - HIMS). The information gathered can be used to identify the optimum fraction for REE recovery which is essential for the design of a beneficiation process.
Mineralogical and geochemical analysis were performed on a composite sample. The studied sample consists of the following heavy minerals: mainly magnetite, ilmenite, rutile, zircon and allanite. Allanite is the major host mineral for light REE (LREE) and monazite is subordinate. Most of the allanites exhibit zoning, with the marginal areas of the grain showing relative depletion in REE. Specifically, the chemical composition of the peripheral zones indicates replacement of the allanite with zoisite and epidote.
Characterisation of the magnetic separation and grain size fractions allowed the following conclusions to be made: a) The magnetic fraction of the black sand is strongly enriched in the LREE, relative to the non-magnetic fraction, and is found 1.62 times higher than the bulk composition. Allanite is the major host mineral for LREE in the magnetic fraction. b) A combination of SEM/EDS and XRF analysis of the different grain size fractions showed LREE enrichment in the fractions – 0,425 +0,150 mm, and a maximum enrichment in the - 0,355, + 0,212 mm.