Mining techniques can be divided intomon excavation types: surface mining and sub surface underground mining. Today, surface mining is muchmon, and produces, for example, 85 of minerals excludingm and natural gas in the United States, including 98 of metallic ores.
Targets are divided into two general categories of materials: placer deposits, consisting of valuable minerals contained within river gravels, beach sands, and other unconsolidated materials and lode dep
Coal extraction methods vary depending on whether the mine is an underground mine or a surface also called open cast mine. Additionally coal seam thickness and geology are factors in selection of a mining method. The most economical method of coal extraction for surface mines is the electric shovel or drag line. The most economical form of underground mining is the long wall, which is a shear blade that runs along sections of the coal seam. Many coals extracted from both surface and underground mines requir