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Gold/Mining/Energy : Gold and Silver Juniors, Mid-tiers and Producers -- Ignore unavailable to you. Want to Upgrade?

To: hank2010 who wrote (30237)	1/19/2007 12:21:00 PM
From: E. Charters	Read Replies (1) \| Respond to of 78419

Mullankski invented the commercial app of jet-pack thermal fragmentation on one of his numerous trips to Mars. It was first oberved by NASA however as a curiosity on their Apollonic mission when the lunar lander made its own crater. His board stopped him from hopping from outcrop to outcrop with his jet-pack, as his principle use of the technique was to collect field samples by landing on rocks. He had accidentally? fried one of the field assistants to a crisp who had been taking samples the conventional way. I knew one of the guys who did some of the field work for Campbell on their forays in experimentation in this area. Campbell was aiming for an 80% results with thermal, and he said because of the way it was being used, it got about 60%. Campbell abandoned it for the time being. My contact averred that there could be a way to improve yield. Thermal is an extension of the kerosene jet drill. The drill was advanced for oil drilling back in the fifties. It worked well and was fairly efficient. It did not catch on as hole size control was hard to maintain. Often it would make a large crater instead of a 6 inch hole, when it encountered certain conditions. You cannot see the results. InGaAs detectors could improve feedback for the drill unit, but because of rock spray they are hard to protect. It would not be impossible to shutter them, but it would not be easy. There could be some kind of hardened edge detection system, even physical probe that might work to improve that situation. I have talked to some related parties about possibly trying some other related non gas expansive methods to get breakage. They are tried in true in other areas, just have to be applied to non secondary mass rock situations. Obviously they should be combined with some kind of intrusion to get leverage. Pressure to break across faces is easy to obtain. Gas expansion gets to about 20,000 to 50,000 PSI. It would be relatively easy to get pressures of 50K to 100K against small areas, and depend on fracture, and z-factor stress development across areas to obtain bending failure rather than shear. This works against tensile. The efficiency of thermal cannot be understimated. Spalling works on tension, against which rock is 10 or more times weaker than in compression. If one could invent comminution by tensile strain efficiency could be multiplied by large factors, and cost to grind would come down dramatically. This is why blasting is so marvelously efficient. Grinding is 3 time cheaper per energy unit than dynamite, yet breakage by powder is 5 times less costly than grinding. (Grinding is only 1% efficient on average. It is the area where invention promise to save the most money in milling, hence the money put into research in microwave tech etc..) It follows that blasting is 15 times more efficient than the applied hammer force of grinding. This is because blasting works on tensile stress on the particle, rather than shear. Intense short burst microwaves have some promise in the field of sulfide reduction as sulfides respond well to radio waves, heating and expanding more than rock. Suilfides are a devil to grind often as well. Disseminated sulfides may be economic to tackle by short burst microwave techniques. If you have ever panned a tailings pond you will not that the sulfides are markedly larger than the silicates, giving a gritty feel. They are sometimes incredibly tough and drive heat and energy in mills to prohibitive levels when you attempt to reduce them for mineral release. Yet often they contain the desired minerals in fine array to the atomic level. I favour heat and catalysis for the further reduction, but microwaves may be a valuable adjunct. As a further conclusion to the above, it obviously pays to use more powder, not less to bring grinding costs down. More microfractures promote grindability and reduce costs. The only bottleneck here is the number of holes you have to drill to get fine breaking and the fines losses incurred. A fine balance has to be met. EC<:-}