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To: koan who wrote (94431)	10/7/2007 10:43:42 PM
From: E. Charters	Respond to of 313057

The Beal people used buried pipe. According to H, it did not work that well in the grip of the bad global warming winters (they are more severe to make up for lost cold) -- but that may have been a site access problem more than freezing pipes. If you bury the pipes well before the frost line and warm it in plant, then they water should go to no more than +55 degrees F at the sprinkler. Temp drop and heat of reaction of the solution are unknown to me. One could experiment by putting an 'air bag' quonset like pump-up enclosure over the heaps. On the other hand, that takes some innovation. If you circulate air from a ramp into the ground it will stabilize at a fairly high temp, possibly above freezing even. You can pump hill heated waters/slurry 3 miles in fairly small high speed, say 9 inch lines to tailings ponds. The water will not freeze at -70 F, and neither will the tailings pond which has good thermal inertia. But don't try to pump slurry/water from the cold Tailings Pond back to a mill 3 miles in a 40 below winter. It won't go. Gotta start out at room temp to make it and pump really high speed at that. Wooden pipes were often used elevated above ground. Tailings thickeners are outside usually and retention time is significant. They 'steam' some in the winter. I am not sure what the temp is on exit. A lot of hydroxide reaction going on in the tailings thickener, as they are trying for metal precip there, so some heat of reaction exists. Slurry has a significantly lower freezing point than water. Pipe friction and pumping energy adds some heat. It is probably true that the freezing point depression of the cyanide solution is negligible. The classic measure of water pumping over distance at these temps is diamond drilling experience. Pumping a half a mile from a lake with one point five inch hose at 40 below at 25 gpm will require two or three propane coil heaters and burying the line in snow. Water pipe below the frost line into mobile homes under skirts in Red Lake freeze now and then. They require heating tape, but may freeze anyway. You are talking cold tap water. At one point in the equation obviously you have to add energy to the water cheaply. The earth is the obvious source of heat. If you are connected to sufficient mass of earth heated water or air, you can supply heat fairly cheaply. No fair sized underground air system ever is below 55 degrees in the winter. The problem is how much contact at what depth is required to get effect. That is probably why our ancestors were cavemen. They were fairly advanced in thermodynamics. EC<:-}