Deepest operating mine in Illinois, Jefferson No. 20 (formerly Nason) has been mechanized with loading machines and shuttle cars following its reopening in 1938; with coal 5 1/2 to 8 1/2 ft thick under 740 ft of cover, thick pillars are left on advance and split on retreat; seam is broken down with Cardox shells; sketch of panel, showing method of working rooms and splitting pillars.
Loaders and shuttle cars
Coal Age
Coal Age ; 45 , n 4
1940
4 pages
Aufsatz (Zeitschrift)
Englisch
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Extraction of stoops by shuttle cars and loaders
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