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._ . <br />Mining in Canada <br />The dilution of ore and hanging up due to <br />sloughing when pulling shrinkage scopes is avoided. <br />Timber support required is kept to a minimum. <br />The poplar cribbed mill holes are cheap and easy <br />to erect. <br />Ventilation is comparatively simple due to <br />the small openings. <br />The method is chiefly applicable to narrow <br />veins where walls are slabby. <br />The chief disadvantages of the method arc: <br />Blastholes have to be closely spaced in order <br />to break [he ore separately, particularly in the <br />lenticular and folded sections. <br />Holes have to be drilled mostly in quartz. <br />Thus drilling and explosives costs are high. <br />The laying and re-laying of plank flwr is <br />expensive. <br />Some fines are lost through the floor, particu- <br />larly around the chutes, and some scaled ore is lost <br />when the floor is lifted. <br /> Cost per <br />.Mining Cartt ton brokrn <br />Drilling and Blasting _....-..----.---._.. ..--_.-'.-.-- $2.00 <br />'.1lucking and Tramming ____.__._..__... .....__._._... 1.86 <br />7imbering -......._..------------------....__.. ..------ ___ 1.13 <br />Steel and Bi[s ....._._._.___.__..._..-._.__...._._ _._........_._ .T9 <br />Drill Repairs ---'----'----------'----- ----"------- .13 <br />Hoisting -----------------------------'-'-- ------'------ .86 <br />Landing and Dumping __....__.._...____.._._ .__...__._..... .l0 <br />Drainage .-----------------".--'----'------ "-------------' 40 <br />Ventilation ---------------------._.....----- -'---------- .O9 <br />Assaying .------------'-------'-"------------- _.._........... ~ <br />Supervision ---------------'------------"-- -----'----- .36 <br />Pipe and Pipefitting .`---.-'_-..._`---. _-...--.....- .08 <br />Dfiner's Lamps ..----------'°--'-'---------'--"'- -------'------ .0a <br />General --"-----'-"-'-°-------......-'--------- -------"----- .l6 <br /> $S.l l <br />General Costs <br />Timber used per ton of ore broken .____. I1.8 FB1I <br />Powder used per ton of ore broken ..__._ 4.t lbs. <br />Feet drilled per ton of ore broken .__._. 9.5 ft. <br />Ore broken per drilling shift ____........_ 15.0 tons <br />Ore broken per man shift underground 2.36 tons <br />\ore: Inclades development crews, cage tenders, Jt11JILIJ, <br />etc. <br />204 <br />