Modes of occurrence of trace and minor elements in some Australian coals

The modes of occurrence of the trace elements in six Australian coals are reported, together with the nature and percentages of the minerals present. The trace elements studied were As, B, Be, Bi, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Th, Tl, U and Zn, as well as the minor elements S and Fe. The modes of occurrence were determined chemically by sequential extraction. For comparison, X-ray absorption fine structure (XAFS) and near edge structure (XANES) spectroscopies were used to determine the modes of occurrence of As, Pb, Ni, S and Zn in four of these six coals and 57Fe Mössbauer spectroscopy was used to estimate the Fe-species (or forms) occurring in the same four coals. The results obtained were compared with those published on coals generally in the literature. The integrated results provide the most extensive set of information published to-date on the modes of occurrence of trace elements in Australian coals. ► This paper contains the most extensive set of information published to-date on the modes of occurrence of trace elements in Australian coals. ► The modes of occurrence of As, B, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, S, Sb, Th, Tl, U and Zn were determined by sequential extraction of six Australian coals. ► For comparison, X-ray absorption fine structure (XAFS) spectroscopy was used to determine the modes of occurrence of As, Pb, Ni, S and Zn in four of the coals. ► Again for comparison, 57Fe Mössbauer spectroscopy was used to estimate the forms of Fe occurring in the same four coals. ► The data obtained, including mineral content and the mineral type were compared with those published on coals generally in the literature.