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

ABSTRACT

Coal 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.

KEYWORDS:

• Highly volatile coal
• particle size
• coking coal
• Arnu-Audibert dilatation
• Crucible swelling number
• coal crushing

Acknowledgment

Authors acknowledge the support of colleagues who helped in capturing and helping with the analysis.

Funding

Authors acknowledge Tata Steel management for the funding and approval to publish this work.