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Gold/Mining/Energy : Gold and Silver Juniors, Mid-tiers and Producers

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To: Condor who wrote (38008)	4/10/2007 10:32:42 PM
From: hank2010	Read Replies (1) of 78428

Millisecond delays for stope blasts, slashes etc. For development rounds you have to slow down to allow the rock to move before the next hole fires. Rock will not start to move in the first 25 milliseconds, so 2nd hole will fire before the cut clears, "freezing" the cut. In the old days using electric they were called SPs (short period) and LPVs long period. Denison in Elliot Lake was only Canadian company I knew of that allowed use of ANFO with electric caps (danger of static electricity from blowing ANFO setting the caps off). In the US many cos used electric plus ANFO, ensuring that Anoloader was properly grounded and anti-static (semi-conductive with orange stripe) hose was used. Before nonels all other Cdn mines used tape fuse (burnt at 40 sec per foot) and igniter cord to tie in the tape fuse (10 sec per foot???). Anodets were similar to Nonels but cord contained 4 grains per foot PETN which explodes to carry the ignition from the "B-line (23 grains per foot PETN) to the delay element in the detonator. The 4 grains per foot could detonate dynamite (unreliably) and could therefore short circuit the timing in your detonator. Therefore you used a high strength cap without a primer cartridge. Wet holes could be a problem as ANFO is not waterproof. Some of the first non-nitroglcerine cartridges made by CIL contained TNT as a sensitizer and/or (another chemical that should remain nameless) and could be set off by the anodet cord also. DuPont used NBL-380 and could be used with Anodets. This provided an impetus for CIL to develop the Nonels. In Nonels there is only a mist of a sensitizer (which should remain nameless) on the inside walls of the cord. when it explodes, one could hold it in his hand (not recommended) as the cord itself does not even get destroyed. Therefore Nonel line would not detonate the explosive column in the borehole, maintaining the integrity of the blast timing. In the US Austin had developed different non-electric systems which I am not familiar with. What sets off the safety bags in vehicles? Has to be similar to a blasting cap to get them to inflate in time to do any good.

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