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Production: winning coal
Where coal is not available on or near the surface, miners dig shafts to underground seams. There are several different methods of extracting ore, but the process is always one of controlled collapse. Miners inscribe a line across the coal face, or drill and dynamite, until it fractures and spalls.
The room and pillar method leaves about half the seam in place in the form of support pillars. Two or three miners excavate individual pockets, or breasts, until the useable ore is extracted.
Longwall mining exposes a cross-section, which is stripped off in layers. Although it requires initial tunneling, the longwall method allows most of the coal seam to be extracted.
Early methods of ventilating mines relied on the chimney affect of furnaces that burned continuously at the bottom of the main shaft. Children competed for the job of "door boy": opening and closing canvas brattices that directed air through the active workings underground.6 More reliable techniques for avoiding explosions and collapses required safety lamps, separate ventilation shafts, increased stoping and pillar supports for the excavated areas.
All these methods cost time and money for the colliery operators. Miners too were anxious to get directly to paydirt. Quoting Anthony Wallace from his book on St. Clair7, " …maximum profit could only be achieved by spending no more than the minimum on casualty prevention; maximum safety could only be secured by accepting less than maximum profit."
Today, the methods have changed, but the aim is the same. The search for low sulfur, high BTU grade coal requires a large investment of money, time and some risk. The big customers, utilities, demand a minimum of about 8,500 BTU per pound from the coal they buy.9 The market is cyclical, i.e. unpredictable, and accidents do happen.
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