RE: Question: how many miners does a mine this size usually have underground at any one time? is it as little as three as posted elsewhere? or twenty? or what...
A: I have personally produced coal in the numbers they're talking about here with 4 other miners and myself. I have also produced less coal than they're talking about here with 13 others and myself. Geology and general mining conditions have a lot to do with production.
If the immediate roof above the coal is solid, and it's not making water, there's not much to it. Just cut it, load it, bolt it, and start over. Big numbers with few workers.
If the immediate roof above the coal is fractured, and it is making water, production slows down. In my example above with the 13 other workers, we would take a 10 ft. cut of coal, back out and wait for the roof to fall in, go back and finish the cut, so on and so forth. It was a long shift, but within a couple of days, the roof conditions changed, and we were back to good numbers.
My experience is that the immediate roof conditions will often change weekly (kind of like weather), but with competent advance core drilling, the operators know where the bad top and water is, and will map their plans accordingly.
AI
