Effect of Microlithotype Maceral Distribution on Coke Quality

Abstract

The coking behavior of coal is an important facet in utilization of coal in metallurgy and in other industries. The carbonization behavior of coal mainly depends on coal rank, petrographic composition, ultimate composition and rheology of coal. Coal petrography has become very useful technique for establishment between formulation of coal blend composition and coke quality prediction. It is generally established that blend containing optimal reactives produces the coke of maximum strength. The coking properties of coal not depend only on the macerals composition, but also on the way in which the macerals are distributed among one another, forming preferential associations called microlithotypes. The measurements of relative proportion of microlithotypes are called microlithotype analysis. In present work, distribution of macerals (microlithotype) in coal samples were studied and correlated with the coke quality. Beneficiation by wet method were carried out (only indigenous coal) by washing media of specific gravity 1.30 to 1.40 to achieve <10% ash level. Coal microlithotypes plays an important role on coke quality. Bi-maceral and tri-macerals microlithotype distribution (vitrinertite and duroclarite and clarodurite) in coal samples act as a vital role for coke quality. Inter-growth of internite within vitrinite macerals has also significant role on coke quality. Therefore, the combined analysis of maceral and microlithotype distribution is important for coke quality. Distribution of bi-maceral and tri- maceral in coal improved coke quality (M40 and M10 indices). The microlithotype distribution measurement by petrography analysis gave considerable correlations with M40, M10, Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR) parameters. It gave details the adaptability of Indian coke quality in favor of macerals assemblages in coal.