VNIPIpromtekhnologii, Moscow, Russia

A. G. Ivanov, Chief Specialist, Candidate of Engineering Sciences, ivanov.a.g@vnipipt.ru
D. S. Saveliev, Chief Specialist

Weatherford, Moscow, Russia
D. A. Ivanov, Engineer

In-situ leaching is applied to mining of hydrogenous mineral deposits adjacent to permeable water-bearing strata composed of different-coarseness sands. The most common design of ISL wells is a single string well structure with putting down the filter section in the ore-composed interval in the water-bearing pay stratum on the flow string made of polymeric tubes, and with hydraulic sealing of the annular space. Hydraulic sealing of the annular space commonly uses cement grout. A brief review of experience gained in hydraulic sealing of the annular space in ISL wells shows that the modern stage of development lacks accessible and cheap materials which flatly ensure prevention of flow of process solutions in the annular space. The main requirement for such materials is their ability to catch and neutralize acid solutions with formation of insoluble residues which mud crossflow channels. The main components of such materials are oxides of alkaline metals, which react with solution of H₂SO₄ with formation of metal sulfates, for example, Al₂O₃, CaO, MgO, FeO, Fe₂O₃ etc. Such materials can be water solutions of fly ash from power generating plants, using minimal ash fractions to ensure their maximal penetrability in pores and channels of solution flow in the annular space of process wells. The applicability of fly ash in construction, repair and closure of in-situ leach wells in uranium mines is justified. The chemical composition and sorption properties of ash meet the clarification requirements of different solutions containing either acids or different composition anions. Availability and cheapness of ash make it possible to reach great cost saving in well construction and repair.

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