Extractive removal of divalent cations in brown coal at room temperature using aq. acetic acid or aq. ammonium acetate.

Calcium and magnesium ions in Morwell brown coal were found to be almost completely removed by the extraction at room temperature for lh with aq. 1M ammonium acetate or aq. 0.1M acetic acid. Although the removal of ferric ions was rather limited, the improved carbonization properties of the coal in the co-carbonization with A240 or HA240 were comparable with those of the same coal treated with 1N hydrochloric acid.Such a weakly acidic or neutral solution is suitable for the practical process, since neither corrosion or carrier-over of unfavourable anions takes place, although amounts of ammonium ions were included in the treated coal.Such treatment removed the divalent cations from higher ranking coals to a variable extent, improving their carbonization properties, although their whole ash content was hardly diminished.Complexation of acetic anion and better wettability of such a organic acid against the hydrophobic surface of coals may be a reason for the effective extraction of cations in the coal.