Mineralogy and geochemistry of density-separated Greek lignite fractions

In this study, lignite samples were collected from the Ptolemais region, northern Greece, homogenized, crushed to less than I nun, and separated in three density fractions using heavy media. The mineralogical investigation of the density fractions showed a predominance of pyrite in the light fractions, a fact that might be related to either the poor separation or pyrite being trapped between relatively large pure coal particles during the density fractionation. The geochemical analysis revealed that arsenic (As) and boron (B) tend to concentrate in the lighter fractions, while iron (Fe), magnesium (Mg), nickel (Ni), cobalt (Co), manganese (Mn), lead (Pb), and chromium (Cr) are associated with the heavier fractions. No clear indications were drawn for calcium (Ca), selenium (Se), copper (Cu), zinc (Zn), and phosphorus (P).