Auger Mining

Once the hill slope prevents further cutting into the hillside, miners often switch to a technique known as auger mining to extract more coal along the contour. 

Auger mining analogous to wood drilling is employed and the coal is extracted from a seam (which outcrops to the surface) by the use of large-diameter augers. 

This particular method for the recovery of coal was developed mainly in the period following World War II. An attractive aspect of the method is the relatively low cost of the equipment since the technique essentially involves boring a series of parallel horizontal holes into a coal seam. 

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Auger mining is a supplementary method used to reach coal in stripped areas where the overburden has become too thick to be removed economically. Large augers are operated from the floor of the surface mine and bore horizontally into the coal face to produce some reserves not otherwise minable. This technique is frequently used to supplement coal recovery from contour mining. 

Surface mining techniques are used when the coal is present near the surface, and the overburden is thin enough. These techniques include contour mining, strip mining, and auger mining. 

The commercial value of a clay deposit depends on market trends, competitive materials, transportation faciflties, new machinery and processes, and labor and fuel costs. Naturally exposed outcrops, geological area and stmcture maps, aerial photographs, hand and power auger drills, core drills, earth resistivity, and shallow seismic methods are used ia exploration for clays (32). Clays are mined primarily by open-pit operation, including hydraulic extraction however, underground mining is also practiced. 

It is commonly accepted in the explosive and mining industry that at least 40-50 percent emulsion is required to protect the Heavy ANFO blend from borehole water intrusion. Pumped explosive blends with 60-80 percent emulsion can even be used when severe water conditions are encountered. These products can be pumped through a loading hose, which can be lowered to the bottom of the borehole and displace the water during loading. Trucks similar to that shown in Fig. 37.9 can be used for these products. Most Heavy ANFO products are more simply mixed and loaded through an auger into the top of boreholes. For Heavy ANFO products... 

Fused basalt is utilized chiefly in the manufacture of floor tiles, castings for cyclone and other separators, nozzles, augers and grate bars the centrifugal casting technology is used in the production of conveyor pipings for mines, mill corps, etc. A special case is represented by the application of fused basalt for the incorporation of radioactive wastes. Fused rocks are dealt with in the extensive series of studies by Voldan (1955 — -1976). 

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