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

To: marcos who wrote (23687)	10/27/2006 2:28:57 PM
From: E. Charters	Respond to of 78413

Mills are pretty hard to make totally portable of any size because of horsepower requirements. Ball Mills are heavy. Iron media in a 10'X8' ball mill is 67 thousand pounds. Tanks for dewatering and surge need size. A 1500 ton/day mill processes fluid slurry that would fill an 18 foot by 20 foot tank in one hour. An outfit I know has been working on high pressure hydraulic rolls to grind ore at rates of up to 5,000 tons per hour. Sort an offshoot of the old Cornish Roll brought up to date. They would not be small. I have an idea to make centrifugal force work in grinding to possibly reduce floor space in comminution units. I don't really know yet if it would do that. Have to experiment with output. Principle works and was used as far back as 1920. (Patent on the centrifugal concentrator touted today as the new thing was 1934 and the Alimak rail raise climber was first developed in the 1930's.) Bottom line is one could make a crushre-grinder portable for certain regimes, but I think 200 tpd for now is the max you are going to semi into the outback. And that is not one one semi from my envelope, but there are still wrinkles to finkle here. A 30 to 50 tpd outfit fits on one semi to two, depending. I have access to one such outfit. Another consideration which develops is the olde environmental rule bridge. Some of that stuff requires a sort of fixed installation overhead that makes a fixed mill fit the whole logistical picture more firmly. On the other hand total portability does lower costs, and also fits the envi desirability in some ways. Unitary piece skid mills were planned by U of T engineers for hinterland foreign mining ventures and far north thingies way back when. I have a model work up on such a concept from their mining department from an unknown era. (1970's) RMKL's 200 tpd mill would take several semis to haul away. Like about 20. I worked in a 300 tpd flotation gold mill not far from that mill, and I would say you could haul it out with about 12 semis. You could make 1 to 5 ton per hour one stage grinders (I mean pea gravel to 100 mesh) that would fit on a five ton. When you get to 50 tons per hour, that is ten of them. Scaling to 50 tons per hour for one unit would mean you are as big on floor space as a ball mill, though not as heavy by a wide margin. Something to work on. The engineer's heuristic imagination cap must sit in dream mode for a while to fit these needs to workable solutions. And about 100,000 to 1 million in trial and terror to get a working model with bugs on the outside. Ten million more in marketing and trials with brave new outfits and it would sell. I don't think even Denver has has the circular grinding media to try it yet. What stopped Dominion and Gardner Denver from going further with small mills development such as their conical past the 1930's was the economics of small mining, i.e. less than 1000 tpd. Gold price. Innovation in mining tech of that kind stagnated from 1940 to 1980. And it has not yet picked back up. Burgeoning industries produce radical offshoots. Government choked enterprise rationalizes heavily with tried and true, and suffers accordingly. EC<:-}