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The overburden from the first strip is deposited in an area outside the planned mining area and referred to as out-of-pit dumping.Overburden from subsequent strips are deposited in the void left from mining the coal and overburden from the previous strip. It is often necessary to fragment the overburden by use of explosives.The overburden is then removed by draglines or by shovel and truck.Once the coal seam is exposed, it is drilled, fractured and thoroughly mined in strips.The choice of mining method depends primarily on depth, density, overburden and thickness of the coal seam; seams relatively close to the surface, at depths less than approximately 180 ft (55 m), are usually surface mined. coal that occur at depths in excess of 200 ft (60 m) are mined by the open pit methods, due to thickness of the seam 60–90 feet (20–25 metres).Coal that occurs at depths of 180 to 300 ft (55 to 90 m) are usually deep mined, but in some cases surface mining techniques can be used. Coals occurring below 300 ft (90 m) are usually deep mined.Coal mining processes are differentiated by whether they operate on the surface or underground.
Globally, about 40 percent of coal production involves surface mining.
This overburden is put into the previously mined (and now empty) strip.
When all the overburden is removed, the underlying coal seam will be exposed (a 'block' of coal).
In Canada (BC), Australia and South Africa, open cast mining is used for both thermal and metallurgical coals.
In New South Wales open casting for steam coal and anthracite is practiced.
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Strip mining exposes coal by removing earth above each coal seam.