Effect of Grinding on Chemical and Coking Properties of a Highly Volatile Bituminous Coal and Its Size Fractions

Abstract

ABSTRACTCoal is a highly nonhomogenous material. Owing to the different inherent hardness of its various components, the weaker component has a tendency to segregate in the finer fractions and the others in the coarser fractions. These varied fractions would be expected to have different physical, rheological, and chemical properties. A high volatile U.S. coal when crushed and separated into six fractions using laboratory sieves showed varied properties. Noticeably, both the coarser (> 3.15 mm) and finer (< 0.5 mm) fractions have a higher ash % than the composite sample. The volatile-matter content shows a 3–6% variation. But the notable variation is observed in the total dilatation of the fractions. First the total dilatation increases with decreasing particle size then suddenly falls to a surprisingly low value (9%) compared to the composite sample. This may be due to the fact that with decreasing particle size, volatile matter escapes the matrix without sufficiently imparting swelling to the coal particle.