VNIPIpromtekhnologii JSC (Moscow, Russia)
E. P. Bugrieva, Leading Researcher
D. V. Maynikov, Head of Laboratory, Candidate of Engineering Sciences, maynikov.d.v@vnipipt.ru
Khiagda JSC (Chita, Russia)
E. V. Korgun, First Deputy CEO—Chief Engineer
A. V. Suvorov, Chief Geologist
In 2021, exploration well V1.13-K1 was drilled to control the reserves of the Vershinnoe deposit and evaluate the effectiveness of uranium extraction by in-situ leaching (ISL) after more than three years of operation of the deposit. This article presents the results of studying the material composition of the core of the control well V1.13-K1, outlines the possible causes of under-recovery of uranium from rich ores, and examines the effect of humiс acids on extractability of uranium with solutions of mineral acids. As a result of the comprehensive analysis of the ore material sampled from three hypsometric core levels, it is determined that the uranium concentration increases from the upper to the lower interval from 0.399 to 0.885 %. Additionally, the amount of fraction with a grain size of <0.05 mm decreases from 24.1 to 17.9 %. It is worth noting that up to 80 % of all uranium is associated with the clay fraction, and up to 90 % exists in a form that is difficult to extract, which implies that no leaching process takes place in such material. Based on the studies conducted, the main causes of the under-recovery of uranium are identified. These include the relationship between uranium mineralization and organic matter, such as humic acids, which can bind up to 10 % of the metal in insoluble forms. Another factor is the presence of clay interlayers which make it difficult for leaching solutions to penetrate ore-bearing horizons. Additionally, the low redox potential in the area of ore deposition also contributes to the problem. To intensify the process of metal extraction into solution, it is necessary to implement a set of measures aimed at correcting geotechnical parameters. This includes the use of more severe leaching conditions and stronger oxidizing agents, as well as the increase in the time spent on block development.
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