Satpaev Kazakh National Research Technical University, Almaty, Kazakhstan:

Kh. A. Yusupov, Professor, Doctor of Engineering Sciences
E. A. Elzhanov, Associate Professor, Candidate of Engineering Sciences

Euroasian Economic Commission, Moscow, Russia

S. B. Aliev, Deputy Director of Department, Doctor of Engineering Sciences

Semyzbay U, Astana, Kazakhstan
D. A. Dzhakupov, Geotechnical Engineer, danik_757@mail.ru

The major requirement imposed on the method of underground leaching of uranium is continuous service of wells (from 1–2 to 3–5 years) at the preserved production output (well yield). At the same time, one of the main causes of well yield reduction in underground uranium leaching is mud fill of filters and near-filter zones in water-bearing strata, which induces increased flow friction and reduces infl ow of pregnant solution in wells. In this article, the authors are focused on the recovery of flow rate in pumping-out wells by means of efficient methods aimed to prevent colmatage in terms of Semyzbay deposit development in Kazakhstan. Operation of wells shows that the primary problem is chemical colmatage due to high content of silicium compounds in rocks. The standard approaches (swabbing, airlift pumping with compressed air, etc.) aimed at the flow rate enhancement have had no weighty result. The success has been only achieved with the studies into the mud fill prevention using ammonium bifluoride. The tested method consists in filling dry ammonium fluoride in a pumping well and then addition of sulfuric acid solution in it. As a result of the chemical reaction, fluohydric acid is generated in the nearfilter zone of a well and dissolves hardly soluble compounds of silicium, which diminishes colmatage of filters.
The authors appreciate participation of M. B. Salkynbaev, Director, Semyzbay U, in this study.

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