Question

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4. Two ways of coal mining are​

Answer 1

Answer:

Surface mining and deep underground mining are the two basic methods of mining. 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 55 m (180 ft), are usually surface mined

Explanation:

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Answer 2

Answer:

Surface mining and deep underground mining are the two basic methods of mining.