Mineral Commodities Solid Earth System.

Mineral Commodities

Solid Earth System

Coal Mining Techniques

Mine was using ‘retreat mining’ where pillars of coal, originally left to hold up the mine’s roof, are removed, in order to recover the coal in them. The pillars near the back of the mine are removed first, hence the word ‘retreat’. Ideally, the roof collapses in a sequence of small events. But if collapse is delayed, it can be very energetic and dangerous.

Black Lung Disease

Mountaintop removal coal mining

Mine leachate near Ouray CO

froth flotation tank

pouring slag at night