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Foam Injection Leaching Process for Fragmented Ore.
U S Pat 4 080 419 1978 Mar; :
This invention relates to a process for leaching broken or fragmented ore or metal value-containing bodies with a reagent- carrying foam. The foam is generated by adding a surfactant to a leaching solution and passing air or other gas through the solution to generate relatively stable foam bubbles, which are propelled through the fragmented mass by gas pressure. The foam can be injected in cycles, allowing drain time, or can be injected continuously with the leachant drainage taking place at the periphery of the ore mass and removed continuously. Thus, a sloping, fragmented ore vein was simulated by a plastic tube (6 in diam x 6 ft long) set at a 30 deg angle with the horizontal and filled 3/4 full of -2 in +1 in native copper ore fragments. The void volume was determined to be about 10 liters. A 0.2 Molar ammoniacal ammonium carbonate leach solution was mixed with 1 pct by weight of a foaming-type surfactant, tergitol npx (a nonyl-phenol- polyethylene oxide surfactant containing an average of 10-1/2 c2h4o units per molecule and distributed by Union Carbide Corp.). A measured volume of leachant was added to the tube and allowed to flow to the bottom. Air was admitted to the bottom of the tube through a 1/4 in fitting and bubbled through the solution to cause foaming. The minimum amount of solution that would fill the void spaces with foam was 200 ml, with 400 ml being preferred. These amounts are only 2 to 4 pct of the volume required for full-flood leaching. After seven cycles of successive foam injection-foam drain down, the leachant contained 1,080 ppm cu.
U.S. Pat. 4,080,419, Mar. 21, 1978, Chem. Abstr. Not Found
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