Transactions . g drillholes 8 ft. long. Just enough ore was now mucked into the chutes toallow another cut to go up the cone. This was repeated until four cutshad been taken. Then the stope was mucked clean, the chutes raised20 ft. ( m.) and enough fill put in to again reach the back. There W. ROGERS WADE AND ALFRED WANDTKE 403 was a slight amount of fill that had to be hand spread between the chutesand the outer walls of the orebody. The accompanying illustrationsshow two stages of operating this stope. The advantages of this method are: several cuts are taken beforefilling; 20 ft. of ore
Transactions . g drillholes 8 ft. long. Just enough ore was now mucked into the chutes toallow another cut to go up the cone. This was repeated until four cutshad been taken. Then the stope was mucked clean, the chutes raised20 ft. ( m.) and enough fill put in to again reach the back. There W. ROGERS WADE AND ALFRED WANDTKE 403 was a slight amount of fill that had to be hand spread between the chutesand the outer walls of the orebody. The accompanying illustrationsshow two stages of operating this stope. The advantages of this method are: several cuts are taken beforefilling; 20 ft. of ore is broken all over the stope, so that no floor is neededover the waste fill, the bottom of the ore only being raked down over thewaste cone once. If fill were put in after each cut, too much wastewouH get mixed with the ore; if the cone were floored with plank, theextreme hardness of the Pilares ore, and the large pieces weighing 3 or 5tons into which it breaks, would make it practically impossible to maintain. Fig. 12.—Section through shrinkage stope. the floor without great breakage. The expense of installing a floor overa large cone for every 7-ft. cut would make quite an addition in the stopingcost. We figure that the amount of fines lost on top of the waste fill isnegligible because the waste cone is scraped down very carefully, and1 or 2 in. of waste filling mixed in with 20 ft. of broken ore has no ap-preciable effect in lowering the grade. As the cone of such a stope isonlj^ cleaned down five times during 100 ft. of stoping, it is possible todo this work carefully without adding too much expense to the costper ton of ore distributed over the life of the stope. A stope of this sizerun on this method in the extremely hard ore of the Pilares mine willproduce 9000 tons per month. Shrinkage Slopes.—During the earlier days, the ore was mined in 404 GEOLOGY AND MINING METHODS AT PILARES MINE large shrinkage stopes. In some of the larger orebodics they were laidout across
Size: 1815px × 1377px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
