Roll-front deposits uranium mobility

DEUTSCH AND SERNE Uranium Mobility and Roll-Front Deposits... 

A consideration of other elements associated with roll-front deposits improves the accuracy and confidence in locating favourable trends (Fig. 9). Sulphate concentration and conductivity increase toward the redox front and then decrease abruptly owing to precipitation of iron sulphide, followed by calcium carbonate. High values of bicarbonate and selenium also contribute to identification of the zone of uranium mobilization on the oxidized side of the front. Molybdenum concentrations are normally associated with sandstone deposits, but haloes in the groundwater may be to the side of or farther down-dip than the centre of the geochemical cell. Arsenic is most valuable for its regional halo around areas of mineralization. 

Data from in-situ leach mining and restoration of roll-front uranium deposits also provide information on the potential mobility of the waste if oxidizing ground water should enter the repository. Uranium solids probably will be initially very soluble in carbonate ground water however, as reducing conditions are re-established through water/rock interactions, the uranium will reprecipitate and the amount of uranium in solution will again equilibrate with the reduced uranium minerals ... 

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