THE PREDICTION OF THE FUSIBILITY OF COAL BLENDS

Procedures are outlined by which the thermoplastic properties of coal blends - fluidity, as measured by Gieseler plastometry, and extent of fusion, as measured by proton magnetic resonance thermal analysis (PMR TA) - can be predicted from those of their component coals on the assu mption that the thermoplastic properties of the blend are the appropri ately weighted average of the properties of the component coals at eve ry temperature. Account is taken of the influence of inert material on measured fluidity in the Gieseler plastometry model and thus the mode l can be applied to blends which have inert material added. The extent to which the observed thermoplastic behaviour of a blend deviates fro m these linear models is in principle a measure of any interactive eff ects that occur. Blends involving four Australian bituminous coals of different rank and fusibility were prepared so that the effect of a wi de range of of thermoplastic behaviour of the component coals on blend properties could be more clearly delineated. The coals and their blen ds were characterised by Gieseler plastometry and PMRTA. The maximum f luidity and PMRTA maximum fusion of the blends of coals of different r ank were predicted by the models to be less than the weighted average of the component coals, and generally agreed with observation. The flu idity and fusibility of blends containing the higher rank, high fluidi ty coal and the two lower rank coals were significantly greater than e xpected by the model which is interpreted as evidence of an interactiv e effect between these coals that increases the fusibility of blends f ormed from them.