Which factors determine whether a coal seam is mined at the surface or underground?

The choice between surface and underground mining for a coal seam is determined by a combination of technological, economic, and social factors.1

Technological Factors

Technological considerations dictate the feasibility of a specific mining method. Key factors include:
* Geology: The number, thickness, and steepness of the coal seams, as well as the nature and thickness of the strata overlying them.1
* Topography: The surface features and terrain influence whether area or contour mining is viable.12
* Stripping Ratio: This critical metric represents the amount of waste material (overburden) that must be removed to extract a given amount of coal. It is often the deciding factor in determining when surface mining becomes uneconomical and a transition to underground mining is required.13

Economic and Social Factors

While technology determines the method, economic and social factors often decide if a reserve is mined at all.1
* Economic: These include the market price of coal, production costs, transportation availability, and the cost of alternative energy sources.14
* Social: These involve labor availability, regional government support, and historical mining patterns in the area.1