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Gold/Mining/Energy : Gold and Silver Juniors, Mid-tiers and Producers
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To: E. Charters who wrote (30249)1/19/2007 12:44:50 PM
From: hank2010  Read Replies (1) of 78419
 
I worked for IOC in Labrador, long after the jet piercers were parked. The old drillers told me some stories of them, including some hairy ones. The piercers were replaced with the rotary drill rigs when the new drill bit technology overcame the dificulties of drilling the hard taconites in the Minn. Mesabi Range, and could drill cheaper.

One advantage of the jet piercers was that a good driller could crater out the toe of the drill hole thus enabling a much higher powder factor at the toe of the hole, which as you know, is the most difficult area to break.
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