Coal Mining (1978) / Chapter Skim
Currently Skimming:
UNDERGROUND COAL MINING TECHNOLOGY
UNDERGROUND COAL MINING TECHNOLOGY
Pages 25-34
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 25... ...
Room-and-pillar coal mining can be classified further as conventional or continuous depending on the method of extraction at the face. In conventional mining, the mining cycle consists of cutting, drilling, blasting, loading, hauling, and roof bolting, and specially designed machines are utilized for each step.
|
From page 26... ...
The unit operations of the mining cycle with continuous miners consist of the following steps: approxiirately 20 feet of entry is mined; the mining machine is iroved to another entry; the area just mined is roof bolted; and the exposed coal and floor is rock dusted. Only about 20 feet of advance per cycle is possible due to the requirement that the operator not advance beyond the roof support line.
|
From page 27... ...
3. Ventilation and Methane Control Methods Ventilation has become an important factor in the design and operation of underground coal mines as regulation concerning allowable methane and dust levels have become 27
|
From page 28... ...
Coal mine emissions of methane, although frequently representing huge amounts, occur in a highly diluted form in the discharged ventilation streams, usually substantially less than 1 percent methane. There is no technology available today that could economically concentrate this methane into a form useful as commercial pipeline gas once it has been mixed with air.
|
From page 29... ...
While backfilling may provide limited control in abandoned mines and in active mines that use longwall or partial recovery mining methods, it has not been demonstrated as an economic possibility for underground mining on a large scale.2 In some situations, a solution to the problem of subsidence may be the use of longwall mining or complete extraction roomand-pillar mining since the surface is allowed to subside permanently in a planned and controlled manner.
|
From page 30... ...
This change in personnel exposure underground has important safety implications since exposure is a key element in underground mining safety. USBM and MESA data for 1975 reveal that 115 of 140,000 underground coal miners employed lost their lives (or one out of 1,200)
|
From page 31... ...
^ in o 08 10 4J co in • O .
|
From page 32... ...
Since the mining machine is capable of 10 tons per minute, roof bolting or, more generally, roof control is an obvious bottleneck to production. During the cycle, the mining machine discharges coal into a shuttle car that travels back and forth to some discharge point.
|
From page 33... ...
Capital is tied up without return for those years; therefore, larger margins are required in later years for equivalent discounted cash flow rates. An additional major item in mine development is shaft sinking, and faster, safer, lower cost methods are desirable.
|
From page 34... ...
The development of methods for efficient mining and recovery of thick underground coal REFERENCES 1. Appalachian Regional Commission, Acid Mine Drainage in Appalachia, (Washington, D.C.: Appalachian Regional Commission, 1969)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.