Effects of Pressure upon the Isothermal Plastic Behavior of High-Volatile Bituminous Kentucky Coals

The plastic character of six high-volatile bituminous coals has been examined by using a Gieseler plastometer under 0.1-2.8 MPa (15–400 psia) of helium, measuring in an isothermal manner and at uniform torque. For all coals studied, the maximum fluidities increase with increasing pressure, attaining values ranging from 9-fold to 620-fold greater than the corresponding maximum fluidities at atmospheric pressure. Fluidities increase most sharply over the first megapascal of superatmospheric pressure and then flatten out smoothly with further increases of pressure, approaching asymptotic values. Melting slopes very similarly with pressure; coking slopes are nearly independent of pressure in this range. These observations are consistent with the view that, for these coals, the predominant pyrolysate fraction is a liquid with significant vapor pressure in the vicinity of 400 °C.