VNIPIpromtekhnologii JSC, Moscow, Russia

N. A. Chernobrovkin, Chief Specialist, Chernobrovkin.N.A@vnipipt.ru
E. Yu. Meshkov, Head of Laboratory
D. V. Mainikov, Head of Laboratory, Candidate of Engineering Sciences
A. G. Ivanov, Chief Specialist, Candidate of Engineering Sciences, Corresponding Member of the Russian Academy of Natural Sciences

The article discusses the main causes and types of clogging, i.e. the decrease in filter efficiency in wells and casings, which is frequent in mining with in-situ leaching (ISL). The main cause of clogging is the formation of poorly soluble chemical compounds, primarily gypsum (CaSO₄×2H₂O), during interaction of a leaching agent with an ore-bearing stratum. A brief overview of the most common and promising methods for preventing chemical clogging and restoring productivity of clogged wells is given, and the known methods for dissolving clogging materials are considered with regard to their advantages and disadvantages in terms of their impact on the in-situ leaching process. Practical laboratory research of the declogging process was carried out as a case-study of treatment of a gypsum filter cake, taken from a well at a uranium deposits developed by in-situ leaching, with neutralizing reagents, complexing reagents and reducing reagents. Based on the results of the experiments, the optimal formulation of a declogging solution for removing gypsum filter cakes was determined, and the influence of such factors as the declogging solution temperature, the filter cake treatment duration, and the chloride ion content of the declogging solution on the effectiveness of dissolution was assessed. In laboratory conditions, the process of reactant treatment of a well was modeled, and the modeling results allowed proposing the optimal chemical treatment methods with regard to the amount of sediment formed in the well. The article suggests potentially possible options for further handling of declogging products.

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