Abstract
Experiments were conducted to obtain relationships between the yield of respirable dust from the continuous mining process and coal seam properties. This study was based on an in-mine sampling strategy, and both dust and coal samples were collected during the coal-cutting process from 7 coal seams over 44 shifts of operation. Observed levels of respirable dust concentration were converted to a generated mass of dust per ton mined and normalized to adjust for the impact of cutting time and ventilation quantity. Statistical analyses were used to determine the relationships among the normalized respirable dust (NRD) generated and various coal seam properties obtained from proximate analyses (as-received basis) of run-of-mine (ROM), upper-channel, and lower-channel samples. A consistent improvement in the strength of the correlation between normalized respirable dust and coal seam constituents was observed along the vertical seam profile. The lower-channel sample constituents, being structurally more consistent, showed the highest correlation compared to the upper-channel sample constituents. High-rank (i.e., high fixed carbon) coals are generally associated with higher levels of respirable dust, while high-ash coals generally yield lower levels of respirable dust. The role of extraneous moisture (ROM moisture), used in dust suppression, is evident in the consistent inverse relationship obtained with normalized respirable dust. The exponential of the fuel ratio, the ratio of fixed carbon content to volatile matter content and an index of coal strength, correlated well with NRD and was a significant variable in regression modeling for each of the coal seam samples. Multiple regression analyses yielded models which explained 43.1, 73.4, and 41.0 percent of the variation in NRD by coal properties from the upper-channel, lower-channel, and ROM samples, respectively.