M. B. Chertok

A new method of reduction of core samples of uranium ore to their natural redox state is described. The results of laboratory experiments on agitated and filtration leaching of uranium from ore reduced by sulfide solution are considered in comparison with leaching of oxidized stored ore. The oxidation of ore samples during sampling and storage leads to the overestimation of the rate of uranium leaching from ore by sulfuric acid solutions. The more oxidized a sample, the higher the overestimation of this parameter in comparison with traditional borehole in situ leaching (ISL) with sulfuric acid. As is proved by determination of U and Fe species in reduced samples, the described technique of ore sample preparation for laboratory experiments enables the natural redox state of ore to be approached. The results of laboratory experiments with samples prepared according to the proposed technique are adequate to the real process of ISL with sulfuric acid at the Dalmatovo uranium deposit.

Geochemical properties of ore-bearing horizons composed of alluvial aluminosilicate terrigenous rocks have been compared at young and ancient hydrogenic uranium deposits. It has been shown that the li