Uranium in-situ recovery (ISR) is a mining technique that allows the extraction of ore from the mineral matrix and facilitate its recovery at the surface. This technique utilises a series of injection and extraction wells to pump a leachate into a mineralized aquifer, resulting in ore dissolution, and to pump back the metal bearing solution to the surface for further processing. ISR is considered advantageous over traditional mining techniques involving mechanical crushing and grinding because, among others, it requires lower operational costs and can be applied to relatively low-grade ores. This alternative to conventional mining has been conducted in the former Soviet Block and the United States for the exploitation of uranium ores since the 1960’s and is mainly applied to sandstone-hosted roll-front uranium deposits in confined aquifers. Nowadays, this strategy accounts for almost half of uranium production worldwide.
Alternative remediation strategies involved in the remediation of ISR legacies are similar to those applied to acid mine drainage (AMD). As such however, inherent difficulties linked with the depth of the mined aquifer make classical technical solutions inoperable. For deep aquifers, in-situ biostimulation of the microbial communities would be preferred. Our activities focus on the development of stimulation methods using columns experiments. The autochthonous bacterial communities are exposed to diluted ISR fluids (pH 5) mimicking the intrusion of an acidic plume into pristine sections of an aquifer. Columns are designed to assess the mitigation effect induced by the injection of an organic carbon source, as well as to measure the capacity of this system to immobilize mobile uranium.
Research partners
Alexandre Guyonnet, Daniel Beaufort : Institut de Chimie des Milieux et Matériaux, University of Poitiers, France
Rizlan Bernier-Latmani : Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne, Switzerland
Michael Descostes, Hélène De Boissezon : ORANO Mining, R&D Dpt., Paris, France