Size segregation of component coals during pulverization of high volatile/low volatile blends
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Geosciences
- Pennsylvania Electric Co., Johnstown, PA (United States)
Samples of single high volatile (hvb) and low volatile (lvb) coals and binary blends in proportions ranging from 75%hvb/25%lvb to 25%hvb/75%lvb were pulverized in a Raymond 271 bowl mill and then screened into different size fractions. The ranks of two of the feed coals were sufficiently different that individual particles could be distinguished microscopically. This enabled the proportions of each feed coal in the various blend size fractions to be determined. The difference in rank and therefore grindability of the components (Hardgrove indices of 99 versus 50) was such that significant segregation resulted. For example, the 25%hvb/75%lvb blend, upon grinding, produced a +50 mesh (300 {micro}m) fraction with 30% lvb coal, and a {minus}325 mesh (45 {micro}m) fraction with 84% lvb coal. The effect of this segregation according to size was a notable progressive decrease in volatility towards the finer fractions, consistent with an increase in the proportion of lvb particles; differences in volatile matter (d.b.) between coarsest and finest fractions of up to 6.9% were encountered. Although most of the segregation is attributable to rank difference between the component coals, part appears to be due to the lower grindability of liptinite-rich lithotypes in the hvb coal.
- OSTI ID:
- 257050
- Report Number(s):
- CONF-950952--
- Country of Publication:
- United States
- Language:
- English
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