Some factors influencing the rheological properties of concentrated brown coal—oil suspensions on storage

Rheological properties of coal—oil suspensions are strongly dependent on the characteristics of coal and the medium of suspension. The variations in the rheological properties of brown coal—KC220 oil suspensions with storage time were strongly influenced by the moisture content in the coal, coal concentration, medium of suspension, and to a lesser degree, by the extent of mechanical agitation. The increase of both plastic viscosity and yield stress of the brown coal—KC220 oil suspension with storage time was due to an overall reduction of free oil in the suspension, particle aggregation, solvation and swelling. The increase of relative viscosity due to ageing in moist coal—KC220 oil suspensions could be an order of magnitude higher than a suspension of similar concentration, but containing only dry coal.