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. ~,..- ._ <br />• <br />ofocoal using yorauhc sho els'and a twin augei VerS five seams <br />blasted. Holes are drilled on a 15x15-tt pattern with an <br />Ingersoll-Rand D3000 drill to the top of the coal. The <br />5-in.-dia holes are then loaded with ANFO, cast primers <br />and Primacord_ ANFO is used at a rate of 0.61b per cu yd <br />of overburden to be blasted. Each row of holes is delayed <br />from the next row with 25 millisecond dela}~s. CEC uses <br />the a-eights-and distance tables to determine the amount <br />of material to be blasted or detonated within any millise- <br />cond time period. Once blasted, the overburden is <br />removed with the h}~draulic shovels and trucks. <br />The top of the coal seam is cleaned prior to ripping by <br />dozers. This method, which requires no blasting, breaks <br />[he coal sufficiently fora 12-cu•yd Caterpillar 922 front- <br />end loader to load on-highway and off-highway trucks <br />aif'11 ease. Coal is hauled to the coal-handling facility, <br />where it is crushed to produce stoker and slack products <br />that are stockpiled by a series of belt conveyors or loaded <br />directly into on-highway trucks for delivery to custom- <br />ers. <br />0.uger takes up the slack <br />GEC Minerals began auger-mining in January, using a <br />.ompton Model 28 equipped with twin 29-in.-dia augers. <br />Coal is mined to a depth of I50 tt in horizontal seams <br />from the last open highwall of the surface operation. The <br /> <br />per 150 It of advance. Penetration distance mae 38 tons of coat <br />y be increased. <br />