. Transactions. by running the discharged water for a fraction of the time into a tinpail, in which the sludge settles out. The Rossland rock is very hard on diamonds. The War Eagleand Centre Star companies employ a skilled bit setter to keep the bitsin running order. For the smaller sized bits eight diamonds are used,six on the face and two on the outside. Those on the face are set sothat half of them have a cutting edge extending to the outside of the i Milling in the Rossland District. 455 face, while the other half cut the inside clearance for the core to passup. Whenever the drill is with
. Transactions. by running the discharged water for a fraction of the time into a tinpail, in which the sludge settles out. The Rossland rock is very hard on diamonds. The War Eagleand Centre Star companies employ a skilled bit setter to keep the bitsin running order. For the smaller sized bits eight diamonds are used,six on the face and two on the outside. Those on the face are set sothat half of them have a cutting edge extending to the outside of the i Milling in the Rossland District. 455 face, while the other half cut the inside clearance for the core to passup. Whenever the drill is withdrawn from the hole the bit is alwayscarefuliy examined, and if any of the diamonds are found to be looseor the metal worn away, the metal is recaulked around them. Whenthe bit is so badly worn that the diamonds are greatly exposed, theyare cut out and reset in a new metal blank. The wear of carbons is somewhat less than 1/64 karat per foot ofhole drilled. Each bit will only drill about 12 feet before Le Roi Offices. To remove a bit that has been broken off in the^hole, it is sometimesnecessary, if other devices fail, to ream out the whole with a new bit,large enough to enclose the stuck bit and recover it in the core barrel. SHAFT SINKING, The Centre Star shaft is 18 ft. 4 in. x 7 ft., outside to outside oftimbers, and is on an incline of nearly 70°. The accompanying figureshows the position of the drill holes for sinking. The whole round isdrilled before any blasting is done, the machine drills being set up asshown by the location of the two bars. Four men work the twomachines, and it usually takes two shifts to drill the round of 18 machine men do their own loading and blasting, as it is imprac- 456 The Canadian Mi?iins Institute. ticable to have a separate gang for blasting in the shaft as in the stopesand drifts. In the Centre Star shaft the rock is hoisted, during sinking, by abucket let down from a sheave in the ladder compartment by a smallOttumwa
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Keywords: ., book, bookcentury1800, booksubjectmineralindustries, bookyear1895
