Abstract
Coke strength is mainly determined by pores and cracks that cause the fracture of cokes. Cracks around inertinite textures form in the contracting process after re-solidification. In this study, inertinite and reactive concentrated coals were prepared by the density fractionation and the differences in contraction behaviors of them were measured. Moreover, by the use of the measurement results, the thermal stress and the thermal strain energy around inertinite textures were calculated and the formation mechanism of cracks was investigated. The results were follows.
(1) The contraction rate of inertinite is found to be 5-6 points lower than that of reactive (vitrinite and exinite) within the extent of coking or semi-soft coking coal usually used in coke making plants.
(2) At the boundary of inertinite and reactive textures, the maximum tensile stress is generated in the tangential direction.
(3) It is estimated that the critical inertinite size that cracks may form around inertinite textures is about 0.1mm when the temperature reaches 950°C.
