Some aspects of the behaviour of inorganic constituents of two Australian brown coals during hydroliquefaction

Abstract An examination has been made of the changes taking place in the mineral and other inorganic matter contained in two Australian brown coals as a result of hydroliquefaction of the coal in tetralin and hydrogen at 25 MPa and 395 °C. Iron sulphides were found to be reduced to pyrrhotite, whereas iron carboxylates decomposed mainly to magnetite. Calcium carboxylates formed predominantly vaterite, whereas when coals were subjected to low-temperature ashing calcite was formed. Amorphous tin oxide, precipitated onto the coal by hydrolysis of stannous chloride solution, was largely reduced during hydrogenation to liquid tin, some of which reacted with hydrogen sulphide to form herzenbergite.