Characterisation of lithium-bearing minerals for dense media separation

Lithium-bearing minerals from a tantalite processing plant in Minas Gerais, Brazil, with a head grade of 1.06% Li 2 O, were characterised to evaluate the potential of dense medium separation for spodumene pre-concentration in the −850/+500 μm size fraction, selected to evaluate the suitability of dense media separation below the commonly investigated +850 μm size fraction. Physical, chemical, and mineralogical characterisation were conducted on samples from the spodumene processing plant feed. The particle size distribution showed a P 80 of 869 μm and a mean density of 2.86 g/cm 3 . Geochemical analysis indicated that Li 2 O grade decreased with particle size, from 1.58% in the +850 μm fraction to 0.77% in the −74 μm fraction. XRD identified quartz (33.9%), albite (44%), spodumene (13.2%), biotite (2.4%) and enstatite (6.5%). SEM-EDS revealed spodumene associations with feldspar and lithium-bearing micas. Heavy liquid separation tests (HLS) were conducted on the −850/+500 µm size fraction using methylene iodide at specific gravities ranging from 2.60 to 3.10 g/cm 3 . The −850/+500 μm size fraction represents 14.08% of the feed sample and contains 18.26% of the total Li 2 O. At a cut density of 2.80 g/cm 3 , HLS recovered approximately 71% of the contained Li 2 O, equivalent to 12.96% Li 2 O recovery of total Li 2 O, providing the best-performing condition among the tested densities. The HLS results demonstrated that dense media separation has potential in pre-concentrate lithium-bearing minerals in the −850/+500 μm size fraction, with a cumulative concentrate Li 2 O grade of 3.02%. Pilot-scale or industrial tests are required to validate the scalability of the HLS results and to evaluate complementary concentration operations.