Abstract
This article examines one of the promising gold ore areas of the Orenburg Urals region (the suture zone between the East Ural uplift and the Magnitogorsk trough), which has a developed gold-quartz and gold-sulfide-quartz formations in carbonaceous shales. The Kumak deposit is confined to a rift graben comprised of Ordovician carbon-terrigenous-carbonate and Lower Carboniferous deposits and containing 1 to 9 % of organic matter and 2 to 5% of sulfides. The authors established how the accumulations of carbonaceous particles are positioned to the suture zones of deep faults, which control an extended zone of the dyke belt experiencing quartz-sericite alteration, silicification and volcanism. The Kumak deposit falls under the category of gold ore deposits that, considering the depth of formation, the concentration of gold and other parameters, cannot offer economic feasibility when processed using conventional techniques. What would work well for such deposits is the in-situ leaching process, avoiding actual ore mining and other costly operations. Relevance: The drillhole in-situ leaching process can be successfully implemented at the Kumak deposit, enabling to develop gold deposits for which mechanical mining does not prove economically feasible. Ore-grade gold is confined to the fractured zones of metamorphosed shales and is unevenly disseminated localized as steeply inclined ore shoots, along which the leaching process is designed to take place. This technique is one of the most promising geotechnologies in gold mining and should be put into practice as soon as possible. Originality: Using the case study of the Kumak gold deposit, this paper reveals the potential industrial relevance of small deposits of the Orenburg region.
Keywords
East Ural uplift, Magnitogorsk trough, Orenburg Urals region, Kumak ore field, remaining reserves, black shale type, drillhole in-situ leaching, gold, New Orenburg stratum.
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