7TH EUROPEAN COKE AND IRONMAKING CONGRESS - ECIC 2016

The Sapozhnikov plastometer is an integral part of the classification system for coking coal in China. While there have been many studies of the Sapozhnikov plastometer over a long period of time, the interpretation of the results of the procedure remain heuristic. We have developed a detailed model of the Sapozhnikov plastometer, based upon the mechanistic effects occurring during the carbonisation process. These include gas evolution in coal particles, bubble growth, bubble coalescence and bursting, gas transport through softened particles, and in the spaces between particles. During operation of the plastometer, all the different phases of carbonisation can exist at the same time – semicoke, plastic phase and the original coal. We present comparisons of our mechanistic model with plastometer results measured for coking coals across a range of rank. We show that the model can reasonably replicate the experimental results over the whole range of coals studied. Also, we provide a plausible mechanism for the oscillations that are observed in the results, particularly for higher fluidity coals. These results point to an important issue with interpretation of the plastometer results, which must be taken into account when using them for evaluation of coking coal.