Analysis of the efficiency of radiometric mineral processing methods for complex low-iron apatite-containing ores of the Kovdor deposit

This paper presents the results of applying radiometric methods to enrich complex, low-iron apatite-containing ores from the Kovdor deposit. Samples were categorized based on their mineralogical and petrographic characteristics, focusing on the presence or absence of the main ore minerals—apatite and magnetite. The samples were divided into three groups: predominantly magnetite, predominantly calcite, and predominantly silicate. The luminescent properties of apatite and calcite, the primary luminescent minerals in the ores, were studied in both their monomineral fractions and in lump material containing both minerals. Luminescence of apatite and calcite was induced using visible light (with a peak wavelength of 404 nm) and X-ray radiation sources. Analysis of the monomineral fractions revealed that X-ray exposure provides the clearest contrast between the luminescent properties of apatite and calcite, with the luminescence captured by a photomultiplier using SZS 22 optical glass. Further evaluation demonstrated that luminescence color does not effectively identify both apatite and calcite simultaneously, nor does it allow for sorting the minerals based on their concentration. In X-ray luminescence separation tests using a prototype separator, the threshold was optimized to maximize the apatite grade in the concentrate, especially from samples where apatite is the primary mineral, while minimizing contamination by non-apatite minerals. The separation process showed that 72 % of samples with apatite forming 30–50 % of the surface, and 33 % of samples with apatite covering 5–20 % of the surface (containing apatite inclusions ranging from 1–10 mm to <1 mm in size), were successfully concentrated into the apatite product. Samples without visible apatite were separated into the gangue product.