Rheological properties of selected bituminous coals

The rheological behaviour of several bituminous coals has been evaluated by means of a constant torque Gieseler plastometer, utilizing both steadily increasing (3 °C min⁻¹) and isothermal (410 °C) temperature conditions. The results indicated that under either thermal treatment, the coals investigated showed predominantly pseudoplastic behaviour. The greatest degree of non-Newtonian behaviour occurred at or near the temperature of maximum fluidity for coals heated at 3 °C min⁻¹, or within the early stages of melting when isothermal heating was used. Empirical relationships relating the Gieseler fluidities to apparent viscosity were derived from the data.