Two-stage uranium in situ leaching process
AssigneeMobil Oil Corporation
InventorTsoung-Yuan Yan
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Abstract
A two-stage in situ uranium leaching process is described wherein H.sub.2 SO.sub.4 /oxidant is used as the principal leaching solution. Prior to leaching, the formation is treated with a dilute solution of hydrochloric acid, carbonic acid, or other acid (without oxidant) capable of removing the most accessible portions of CaCO.sub.3. The pretreatment improves the permeability of the formation and precludes plugging with CaSO.sub.4. The invention is particularly advantageous when applied to ores which cannot readily be leached with alkaline solutions.
Claims7
A process for the in situ leaching of uranium values from calcite-containing formations wherein the formation is penetrated by at least one injection well and at least one production well in communication with the injection well, which comprises;
- (a) a first step wherein labile calcite in the formation is removed by pumping through, and removing from, the formation a carbonic acid solution that attacks and dissolves a substantial portion of said labile calcite, wherein the carbonic acid solution has a pH not less than 3;
- and
- (b) a second subsequent step wherein the uranium values are leached from the formation by pumping through, and removing from, said formation an aqueous leaching solution containing about 0.1 to 1% by weight sulfuric acid and an oxidant.
Dependencies are inferred from the claim text.