Hard-brown coal mining

J. Siebel, ... Vermiculite for Prevention of Fire-Damp and Coal-Dust Explosions in Hard or Brown-Coal Mining , GerP 1241393 (1967) CA 67,83762 (1967) 3) I.I. Strizhevskii et... 

The phenomenon of leftover ashes in the burning of charcoal can be explained through a kind of contamination minerals like white sodium carbonate, white potassium carbonate ( potash ) and sulfur are, among others, contained in common coal. If connections are made to the historic development of brown coal or hard coal from the remains of plants, it appears to be quite clear, that coal extracted in mining cannot be a pure product. 

The LG. was part owner of brown coal and hard coal mines, and also acquired its own mines. The expansion of the Leuna plants resulted in shifting I.G. Farben s coal interests to central Germany. The biggest increase was obtained through the takeover of the A. Riebeck schen Montanwerke in 1924. ... 

Hard coal, representing over 50% of the fossil raw materials, is the carbonaceous material with by far the greatest availability. Confirmed world resources of hard coal are around 6,900 billion t of these, some 550 billion t can be recovered by current mining techniques. Brown coal deposits total some 6,500 billion t, of which 430 billion t are recoverable. In comparison with coal reserves, economically recoverable oil reserves are only 95 billion t, and natural gas deposits 90,000 billion m (around 72 billion t). 

There is extremely thick and hard stratum of reddish-brown fine-grained sandstone above the coal seam, and it is a critical stratum alfecting the recovery of working face. When face recovery reaches from 200 m to 450 m and forms doubleface square with Face 5306, the act of mining may have an impact on the upper hard-thick strata. 

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