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Show ( SUB-LEVEL STOPING Nece ssary Char acter istics of ore body accor ding to Peele : Type of depo sits mined by sub-s topin g are gene rally free from slips , and stron g enoug h for backs to stand after trimm ing and bench es to stand under their own weigh t. Walls must be firm or they will cave and mix with ore. Over lying ore or cappi ng s shoul d b.e stron g enoug h so as to perm it stopi ng of large panel Deve lopin g main shaft and impo rtant haula ge level s shoul d be outsi de of the ore body, as minin g even tually cause s walls to cave. In 25-40 ft. ore bodie s raise alter nate on op- or block s. posit e sides of haula ge drift , some wider bodie s have 2 para llel haula ge drift s conne cted at inter vals by cross cuts to facil itate At end of depo sit (or at end of panel to be stoped) a raise is put throu gh to level above . Lowest nib level is at top of chute raise s; verti cal inter val betwe en sub-l evels are motor haula ge. 20 to 25 ft; they a.re close r in soft than in hard ore. Stopi ng a. sub-l evel usua lly cons ists of a singl e drift The drift start ing from a main ladde rway and conne cting with a raise from which stopi ng is start ed. Where ore is less than 40 ft. wide, the first sub-l evel is first in middl e of the depo sit. widen ed to the depo sit wall; a breas t stope about 12 ft. wide and the same heigh t resul ts. Down holes drill ed aroun d tops of chute raise s gives a funne l shape to top of raise s. retre ats towar d the ladde rway. The stope On the secon d level opera tions are repea ted but are deft. layed until the faces on the first level have reced ed 10 to 12 -22- |
