A pillar method of working suitable for seams 4 ft (1.2 m) and over in thickness. Three or more narrow headings are driven rapidly with machines at about 30-yd (10-m) centers with crosscuts for ventilation. The headings are 10 ft (3 m) or more wide and 5 to 6 ft (approx. 2 m) high or seam thickness. Upon reaching the boundary, the pillars formed by the headings are extracted, again with machines, on the retreat. This method is favored in the United States and the heading work is quite as productive, if not more so, than pillar working. See also: entry; longwall retreating. Nelson
Source: Dictionary of Mining, Mineral, and Related Terms












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