Atomredmetzoloto JSC, Moscow, Russia:

I. N. Solodov, Director of Innovative and Technological Development Programs, Doctor of Geological
and Mineralogical Science, INSolodov@armz.ru

VNIPIpromtekhnologii JSC, Moscow, Russia:

A. V. Gladyshev, CEO

Khiagda JSC, Chita, Russia:
E. A. Gurulev, Chief Engineer
A. V. Suvorov, Chief Geologist

The article describes the abundance of acidulous hydrocarbonate–magnesium groundwater at uranium deposits in Khiagda ore field (KOF). It is emphasized that the hydrogeochemical specifics of KOF complicates uranium production by the method of in-situ leaching (ISL) and dictates application of nonconventional mode feeding of diluted sulfuring leaching solutions in water-bearing strata using a system of injection wells. Usually, in uranium recovery from hydrogenic rock masses by ISL, the spotlight is on the content of groundwater components which have an adverse influence on uranium adsorption at ion-exchange resins during processing of pregnant solutions. Meanwhile the chemical composition of groundwater remains beyond the scope of attention. The accomplished hydro-geochemical studies in KOF detect uranium bodies with high content of hydrocarbonate and dissolved carbon dioxide. Furthermore, the mechanisms and processes of reservoir and borehole gas and solid phase mudding are predicted and described, and the method of reducing the impact of these mechanisms and processes on ISL of uranium is proposed. The discussed illustration of influence exerted by acidulous groundwater on uranium recovery efficiency by ISL proves the importance of the hydro-geochemical studies using not the conventional approaches when volatiles are studied at the outlet of air-lift or pumping hydrogeology wells but by in-situ investigation of groundwater. Nonetheless, even the underestimated data on content of HCO₃, as well as diluted and free СО₂ in groundwater allow foreseeing the adverse effect of these components on performance of ISL of uranium.

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