Coal Mining. Fight My Ignorance.

Why is coal harvested the way it is? Why can’t it be blasted out of the side of the mountain the way other stone is in quarries. Tunneling deep under the ground to get it just seems like asking for trouble to me.

This is called “strip mining”.

“Strip Mining” is bad.
Leaves huge ares barren & contaminated.
Bad for Birdies!
Bad for Bees-ies!
Bad for kids &
Climbing tree-sies!

In some cases it is done just like a rock quarry (open pit or strip mining). My WAG as to why it’s not done that way all the time is because of the nature of the coal seams or the location of the mine. Presumably Una will be along shortly to provide the definative answer.

It is, but when it’s deeply buried, that may be the only economical way to get it.

When coal is near the surface, it’s quite commonly strip mined. This can be very cost-effective, though it has its own problems (like the cost of restoring the land to an acceptable state once the mining is done). This Wiki article has some info.

The current hot controversy seems to be mountaintop removal mining. It also has a wiki page, of course:

http://en.wikipedia.org/wiki/Mountaintop_removal

Strip mining requires you to take out more material than just the vein of coal. When you get 1500 feet deep you have to have a huge chunk of the surface removed to support the mining operations at the heart of the vein.

If you think of the coal vein as the Colorado river, you’d have an excavation the size of the Grand Canyon. Moving that much earth isn’t efficient for the amount of coal down there.

The industry prefers the term “open pit” mining now, please.

Here is a good visual on why different types of mining are used. The size of the coal seams is also a consideration: in the east, it’s very possible to have a coal seam that is only a foot or two thick, so how much dirt do you want to move to get at those thin veins of coal, especially if they are deep underground? In the West, seams are usually much bigger and closer to the surface, so surface mining operations are much, much more common.

I visited a coal mine a few years ago in Pennsylvania. The mining operation was deep underground (can’t remember how deep exactly) and stretched over an area of miles, including under an interstate freeway. There’s no way surface mining could work there.

Plus, coal and coal gas are flammable. I don’t know that blasting would be as safe as it would be with quarrying stone.

In the North East of England some coal seams continue under the sea, so the tunnels were extended out to get at the coal.

That’s pretty much it in a nutshell. Coal, like oil and gas, is typically hundreds if not thousands of feet deep, and occurs in long, typically narrrow seams. Open pit mining of coal isn’t usually viable, and of course would create a hell of a mess.

Someday, we’ll hopefully be past the point of mining up desiccated vegetative matter for energy. Until then, people will have to risk life and limb digging it out of caves.

Stranger

Strip mining and open-pit mining are two different things.

Coal mining has been shifting steadily to the large open-pits of the West since the late 1970’s. This has been a benefit for several reasons - worker safety is increased greatly, and coal mine profits are as well due to productivity increases. Open-pit is feasible in places like the PRB of Wyoming because as people stated, the coal is in huge, thick veins, and it’s close to the surface. In many places in Wyoming the coal used to lay bare on the surface, or just inches underneath. The earliest settlers came across areas of the State where the coal (being PRB and thus pyrophoric) had spontaneously combusted, leaving large smoky areas of smoldering fires.

Coal veins in the PRB can be enormously thick. I have photos of veins that are more than 100 feet thick, and have seen ones that are scores of feet thick myself. Ironically, if these veins were found underground it would be difficult to mine them, due to the very high cost of supporting a ceiling to high above. While you could create different galleries on different levels, this is often very hazardous due to coal’s weakness as a structural material. IIRC the early workings of the Pocahontas mine (which was an underground mine featuring coal seams 13 feet thick in areas) were pretty nerve-wracking, as the coal was very high quality (and very valuable), but it was hard to extract it all and maintain a safe roof.

As Q.E.D. showed you, wrong again.

You can blast very safely with coal and in coal mines, depending on the methane situation. Sometimes it’s the only way you can clear access to set up a new longwall miner. The rock stability is often the main worry - in some mines, the roofs are extremely predictable and blasting is easy. In Utah…not so much.

Does anyone know how they were planning to mine the coal on Utah’s Kaiparowits plateau (before they were forestalled by Clinton creating the Escalante Grand Staircase NM)?