Dalur JSC, Kurgan Region, Russia:

N. I. Lutsenko, Head of Production Department, lutsenko.n.i@dalur.ru
N. M. Ravshanov, Leading Engineer of Production Department

Dalur company produces uranium using the method of underground sulfuric acid leaching, and has both production and processing facilities. Underground leaching of uranium is a hydrometallurgical process based on controlled circulation of process solutions in an ore-bearing aquiferous stratum, selective in situ dissolution (leaching) of uranium from ore using chemical agents (sulfuric acid) and oxidizers (sodium nitrate, peroxide, aerial oxygen) and recovery of pregnant solutions to the ground surface via production wells. The key distinction of underground uranium leaching as against the conventional methods (opencast and underground mining) is dissolution of uranium and its transition to fluid state in place, without actual mining, by means of created pressure gradient and forced circulation of leaching solutions in an ore-bearing aquiferous stratum in the direction from injection wells to pumping-out wells. The subsequent processes are pumping out of pregnant solutions to the ground surface, processing of them and final production of natural uranium concentrate (ammonium polyuranate). As compared with the common methods of mining (opencast and underground), underground leaching is advantageous for: considerable reduction in drivage, no need to transport, crush, mill and treat ore; preservation of undistubed land; significantly shortened commissioning period of production facilities and accelerated development of design capacities; closed cycle of solutions; substantial reduction in environmental pollution, and some other factors. Access to a producing (ore-bearing) stratum is obtained using two basic schemes: line-drive rectilinear and hexagonal. Using the underground leaching method allows more complete utilization of mineral resources as the scope of this process embraces low-grade ore while the conventional mining and treatment of such ores is unprofitable. At all process stages, including access and preparation, there is no dust formation, and discharge of radioactive elements in air is reduced by 10 times. The incommensurable scaling down of processing circuit is achievable owing to elimination of ore intaking and ore pre-treatment operations from the process flow chart. In such a manner, at low labor costs and financing, in a short run (in 4–5 years) starting from the production commencement, lands are brought back to agricultural tenure without impairment of fertility. The underground leaching technology is well-developed, and offers a controllable, safe and ecology-friendly method of production, applicable even under the most stringent environmental standards.

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