A study on Thermoplastic Property of Strongly Caking Coals and Its Influence on Coke Structures.

According to the coking mechanism, the physical extension of the metaplast during the thermoplastic phase will directly affect the pore and pore wall structures of the coke, however, there was no corresponding thermoplastic characteristic expressing this property. In this paper, several strongly caking coals were selected as samples. It was found that the morphologies of the resulting coking products with a similar rank can be divided into expansion and spreading morphology through a crucible carbonization test for vitrinite particles, which verified the difference of metaplast physical extension during thermoplastic phase. This study proposed a new thermoplastic property, i.e., surface tension of metaplast, and considered it was the internal factor affecting the degree of physical extension. The surface tensions of metaplast for different strongly caking coals were characterized through mobility and ductility experiments, the results showed that metaplast with a lower surface tension would perform a higher mobility and a ductility. To studied the effects of metaplast surface tension on the structure of coke, a carbonized test was carried out. The result suggested that strongly caking coals with a low surface tension was likely to form a coke structure with a higher porosity, larger average pore diameter, and higher proportion of thinner pore walls, indicating that the ratio of strongly caking coal with a low surface tension to coal blending should be minimized. Moreover, through the study of the conventional thermoplastic index for different strongly caking coals, it could simply judge the difference of metaplast surface tension by its logMF/TD. [ABSTRACT FROM AUTHOR]