| 摘要 |
Uranium ore deposits which contain certain proportions of other metals and elemental components, such as are present in redox roll front ore deposits, are selectively leached in situ by passing therethrough relatively dilute aqueous leach solutions comprising essentially from about 0.5 to 5 grams per liter of ammonium bicarbonate and from about 0.1 to 3 grams per liter of peroxide, preferably introduced as aqueous H2O2, and sufficient ammonia to bring the solution to a pH of from about 7.4 to 9, and preferably from 7.5 to 8.5, thereafter withdrawing from the ore deposit the aqueous leach solution enriched in uranium which it preferentially extracts along with a generally lower proportion of other metals and elements as compared to their respective ratios in the ore deposit, and contacting the enriched leach solution with a strong base anion exchange material to strip the uranium from the leach solution. The uranium is eluted by treating the base anion exchange material with an aqueous eluant, and finally the uranium is recovered from the uraniferous eluate by first acidifying it and then treating with ammonia to produce a precipitate of relatively pure ammonium diuranate. The stripped leach solution is separated from the base anion exchange material and the stripped leach solution is recirculated through the ore deposit after adjusting it with more ammonium bicarbonate, peroxide and ammonia. After the uranium in the ore deposit is removed to the extent economically practicable, the leach solution is replaced with an aqueous reducing solution which is passed into the ore deposit in order to precipitate and render insoluble any uranium and elements such as vanadium, molybdenum and selenium. The process produces above ground a very low volume of impurities and waste solutions requiring disposal, and causes no significant or material contamination or deterioration of the underground deposits or any aquifer associated therewith. |
