2007-03-10 13:29:13 · 3 answers · asked by Molly P 1 in Science & Mathematics ➔ Earth Sciences & Geology
One very efficient method is called longwall mining. A horizontal hole 800 feet long is cut through the seam. Machinery is installed, consisting of several elements. One is a conveyor belt. Another is a coal cutter. The cutter chews a several feet deep path through the coal, traveling from one end of the conveyor to the other. All the while, the conveyor is carrying coal to one end, where it is loaded onto another conveyor or some other means of transportation to the outside. A third mechanism is designed to hold the roof in place while the longwall miner is working. At the end of the cut, the conveyor and cutter move forward, ready to make the next cut. At the same time, the mechanism holding up the roof moves too. After a few cuts, the roof where cutting first took place starts to cave in. For a single day, one long wall miner extracted 10,000 tons of coal.
You can see more at www.umwa.org/mining/lwmine.shtml
2007-03-10 15:24:50 · answer #1 · answered by Ed 6 · 0⤊ 0⤋
Same as it did 100 years ago, except machines do most of the digging today and rail cars carry the loads. And strip mining with giant earth movers and bulldozers.
2007-03-10 22:24:03 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Wikipedia has a good summary:
http://en.wikipedia.org/wiki/Mining
and here's a link to the U.S. Department of Labor; Career Guide to Industries
It has some interesting info
http://www.bls.gov/oco/cg/cgs004.htm#nature
2007-03-10 22:10:29 · answer #3 · answered by GatorGal 4 · 0⤊ 0⤋