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Date submitted2022-02-24
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Date accepted2022-05-25
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Date published2022-07-26
Litsa uranium ore occurrence (Arctic zone of the Fennoscandian Shield): new results of petrophysical and geochemical studies
Mineralogical, petrophysical and geochemical studies have been carried out to determine the sequence and formation conditions of uranium mineralization within the Litsa ore occurrence (Kola Region). Mineralogical studies show the following formation sequence of ore minerals: uraninite – sulfides – uranophane, coffinite, pitchblende. Two stages of uranium mineralization are distinguished: Th-U (1.85-1.75 Ga) and U (400-300 Ma). The distribution of physical properties of rocks in the area is consistent with the presence of two temporal stages in the formation of mineralization with different distribution and form of uranium occurrence in rocks. The factors that reduce rock anisotropy are the processes of migmatization and hydrothermal ore mineralization, which heal pores and cracks. Fluid inclusions in quartz studied by microthermometry and Raman spectroscopy contain gas, gas-liquid and aqueous inclusions of different salinity (1.7-18.4 wt.% NaCl-eq.). According to homogenization temperatures of inclusions in liquid phase, the temperature of the Paleoproterozoic and Paleozoic stages of uranium mineralization at the Litsa ore occurrence is ~ 300 and 200 °С, respectively. Correlations of the spatial distribution of elastic anisotropy index with an elevated radioactive background allow using this petrophysical feature as one of the prognostic criteria for uranium and complex uranium mineralization when carrying out uranium predictive work.
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Date submitted2020-05-08
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Date accepted2020-06-12
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Date published2020-12-29
Gas-dynamic roof fall during the potash deposits development
In the development of practically all potash salt deposits, the study of gas-dynamic phenomena (GDP) is one of the most difficult tasks to ensure mining safety. Sudden salt and gas outbursts, dynamic breakdown, which are accompanied by intense gas release and possible broken rock carry-over into the mine workings, are associated with GDP. Geological preconditions for the GDP development are often the layered structure of the salt rock mass, the presence of interlayers and layers of salt clays. For the conditions of the Usolsky potash plant mine, complex studies of factors that characterize the possibility of gas-dynamic roof fall of the stoping rooms were carried out. In mine studies, free gases pressure and the initial velocity of gas release in the rocks of the roof workings were determined. The obtained experimental estimations were used as a parametric basis for mathematical modeling of geomechanical processes under conditions of a near-contact accumulation of free gas. The deformation of a layered salt mass produced by a room development system was described by the model of an ideal elastic-plastic medium with internal friction. The parabolic envelope of Mohr circles was used as a plasticity criterion in the compression area. In the numerical implementation, the deformation of clay contacts was modeled by Goodman contact elements. Based on the results of multivariate numerical calculations, it is established that the main factors determining the possibility of implementing GDP are the additional gas pressure at the contact, the width of the workingspan, and the distance from the roof to the first gas-containing contact. With multi-level lamination of roof rocks, there is a danger of large sources of GDP formation and the mechanism of successive fall of layers in an instant mode is implemented.
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Date submitted2013-07-16
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Date accepted2013-09-20
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Date published2014-03-17
Choice and valuation of similarity parameters for aero-gas-dynamic modeling with main roof collapse
- Authors:
- V. V. Smirnyakov
The article describes the necessary conditions for similarity parameters choosing for aero-gas-dynamic modeling with main roof collapse and it has been made analysis of them.
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Date submitted2009-07-21
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Date accepted2009-09-27
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Date published2010-04-22
Study of gas-and geodynamic state of technogenically changeable coal rock mass
- Authors:
- A. D. Ruban
Intensification and concentration of the mining works increases substantially the risk of geo- and gasdynamic effects arising within the coal mines. Herewith are presented the results of the analytic and experimental studies on stress-strain state of rock mass due to technogenic impact. Under such conditions a potential avalanche destruction of coal rock mass may occur. Some criteria for evaluation of gas-dynamic danger for rock mass, for active stopes and development faces are given. The computer-aided system for monitoring of hazard of gas- and geodynamic phenomena in mines is suggested.
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Date submitted2009-07-23
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Date accepted2009-09-09
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Date published2010-04-22
Physical modeling of energy exchange in rock mass
- Authors:
- E. V. Lodus
- E. V. Goncharov
The cause of manifestation of dangerous dynamic phenomena, such as rock bursts, earthquakes, etc., appears to be the energy exchange in rock mass. The inaccessibility of rock mass for carrying out the full-scale observations has stimulated to study this problem with using the methods of laboratory modeling. Description is given to the substance of energy exchange in situ, the principles of its physical modeling in the laboratory, to the test equipment as well as to some results of our investigations.
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Date submitted1958-03-11
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Date accepted1958-05-28
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Date published1958-05-09
ТРАНСГРЕССИВНЫЕ И РЕГРЕССИВНЫЕ ЯВЛЕНИЯ В ЦИКЛАХ УГЛЕНОСНЫХ ФОРМАЦИЙ
- Authors:
- Unknown
Вопрос о трансгрессивных и регрессивных явлениях при накоплении осадков вступил в новую фазу. Это произошло благодаря изучению угленосных формаций с учетом цикличности их строения. В литологических работах по Кузнецкому, Карагандинскому и другим бассейнам, а особенно по Донецкому, выяснилось значение осадочных циклов, состоящих из регрессивных и трансгрессивных частей. В дальнейшем было установлено, что регрессия не повторяет в обратном порядке пород и фаций трансгрессивной части цикла. Она характеризуется рядом фаций с особыми признаками, если даже они развиваются на тех же глубинах и тех же расстояниях от берега, что и трансгрессивные фации. Соответственные признаки пород также несут на себе черты отличий, которые все более и более выявляются.