토착미생물과 비시안 용매제를 이용한 정광내 존재하는 Au 품위향상 및 회수

Abstract

In order to up grade the Au content in gold ore through biooxidation, indigenous bacteria were collected from Goldensun mine water sites, and to optimize the gold leaching process from Goldensun gold concentrate, a chlorine-hypochlorite solution with varying concentrations and temperatures were applied to salt-roasted concentrate. The indigenous bacteria from Goldensun mine were grown in a subculture-medium. In order to increase the bacteria's tolerance to heavy metals, the indigenous acidophilic bacteria was repeatedly subcultured in an adaptation-medium containing Cu 382.98 mg/l for a 2nd period of 21 days. The adapted bacteria were inoculated into Goldsun mine gold ore, and then the bioleaching experiment was carried out for 30 days at 32℃. As the adaptation experiment proceeded with the Goldensun bacteria, the more the pH value was decreased, the more adapted the bacteria became. In decreasing the pH value in the adaptation-medium, it was identified that the indigenous acidophilic bacteria became adapted to the Cu ions, and that these bacteria have a tolerance potential with heavy metals. In SEM analysis, numerous acidic indigenous bacteria were observed in the adaptation-medium. The result of the bioleaching experiment with Goldensun bacteria, the Cu and Zn content was much greater in the non-adapted bacterial sample than in the control sample, As well these contents were greater in the adapted bacterial sample than in the non-adapted bacterial sample. In SEM observation, the rod-shaped indigenous bacteria having sizes ranging from 0.5×0.6 ㎛ to 0.5×1.7 ㎛, were attached to the surface of the ore in the leaching-medium, and were observed in the leaching-solution. It is confirmed that these bacteria attaching to the surface of the ore can be a evidence of a direct contact oxidation mechanism, whereas with these bacteria in solution there can be an indirect contact oxidation mechanism. The gold concentrate consisted of pyrite, chalcopyrite, covellite, sphalerite and galena, which were turned into hematite through air-roasting at 750℃. Also these concentrates were changed into hematite and nantokite(CuCl) through salt (NaCl)- roasting at 750℃. The results of the gold leaching experiments showed that the best gold leaching parameters were obtained when the hydrochloric acid-sodium hypochlorite mix was at a ratio of 1 : 2, the added concentration was 1.0 M concentration, the pulp density was 1.0%, and the leaching was done at a 60℃ leaching temperature. The leaching rate for gold was much greater in the roasted concentrate than in the raw concentrate. The leaching rate was greater in the salt-roasted concentrate than in the plain roasted concentrate too. From XRD analysis, quartz was found in the salt roasted concentrate and in the solid residue from the chlorine-hypochlorite leaching solution at 60℃.