However, in thick coal seams, it may be necessary to mine the seam in benches (for example benches of 10 metres height). In these cases the seam file is set up as a set of benches such as BEN1, BEN2 etc, and compositing occurs across the bench.
For thick banded seams, for example Indian coal, it is often difficult to correlate all the bands and build a detailed ply model. In this case the model can be built from the thicker unit, and variables can be composited across the unit representing the thickness of coal and the thickness of separable parting.
This parting is defined with a minimum thickness criteria. The Coal Partings menu defines the coal lithologies and these thickness criteria. The valid coal in this example is:
CD CINDERED COAL
CN COAL INFERIOR
CW WEATHERED COAL
CY SOOTY COAL
The below image illustrates the effect of setting coal partings. Here, the thick shale SH and CA define the two partings and the parting thickness. Other non coal rock-types are too thin to be separated.