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Date submitted2022-05-20
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Date accepted2023-04-03
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Date published2024-02-29
Impact of carbon dioxide on the main geotechnical quality criteria and preparation cost of cemented paste backfill
There is a global upsurge in the use of cemented paste backfill (CPB) for various mining functions. However, the cost of the Portland cement binder is prohibitive, thus warranting strategies to reduce cement usage without overly diminishing the CPB quality. Since carbon dioxide is used for patented sand moulding processes, this study is premised on that physicochemical ability of CO2 to enhance the curing of consolidated inorganic materials. It evaluated the impact of carbon dioxide on the uniaxial compressive strength UCS and preparation cost of CPB standard samples (ASTM C109). The preparation cost was delimited to the purchase cost of the Portland cement. The backfill material was silica sand tailings with 4.5 wt.% Portland cement binder and a water-cement ratio of 7.6. Distilled water of pH 5.4 was used for the control samples while variable amounts of carbon dioxide were dissolved in distilled water to generate carbonated mixing water with pH values of 3.8; 4 and 4.2. The lower the carbonated water pH, the higher is the CO2 concentration. UCS tests were conducted on the samples after curing for 3, 7, 28, and 90 days. There was an observable increase in the UCSs and reduction in curing time with increasing carbon dioxide. Samples prepared with carbonated water of pH 3.8 had almost double the strength of those prepared with pure distilled water of pH 5.4, implying that more dissolved CO2 corresponds to higher CPB strength. This is supported by the trendline equations for the graphical simulation of strength on curing time. Thus, CPB with much less binder can be expected to attain the requisite UCS if carbon dioxide is incorporated. The average reduction in Portland cement consumption was 0.61 %, which translates to a cost saving of the same percentage points. If calculated over the operational life of a mine, this is a massive saving of millions of dollars.
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Date submitted2021-01-18
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Date accepted2021-05-21
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Date published2021-09-20
Improving the efficiency of the technology and organization of the longwall face move during the intensive flat-lying coal seams mining at the Kuzbass mines
The reasons for the lag of the indicators of the leading Russian coal mines engaged in the longwall mining of the flat-lying coal seams from similar foreign mines are considered. The analysis of the efficiency of the longwall face move operations at the JSC SUEK-Kuzbass mines was carried out. A significant excess of the planned deadlines for the longwall face move during the thick flat-lying seams mining, the reasons for the low efficiency of disassembling operations and the main directions for improving the technology of disassembling operations are revealed. The directions of ensuring the operational condition of the recovery room formed by the longwall face are considered. The recommended scheme of converged coal seams mining and a three-dimensional model of a rock mass to justify its parameters are presented. Numerical studies using the finite element method are performed. The results of modeling the stress-strain state of a rock mass in the vicinity of a recovery room formed under conditions of increased stresses from the boundary part of a previously mined overlying seam are shown. The main factors determining the possibility of ensuring the operational condition of the recovery rooms are established. It is shown that it is necessary to take into account the influence of the increased stresses zone when choosing timbering standards and organizing disassembling operations at a interbed thickness of 60 m or less. A sufficient distance from the gob of above- or undermined seams was determined to ensure the operational condition of the recovery room of 50 m, for the set-up room – 30 m. Recommendations are given for improving technology and organization of the longwall face move operations at the mines applied longwall mining of flat-lying coal seams with the formation of a recovery room by the longwall face.
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Date submitted2020-06-11
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Date accepted2020-06-11
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Date published2020-06-30
Mathematical model of the liquefied methane phase transition in the cryogenic tank of a vehicle
In order to increase the efficiency of using vehicles (VEH) in mining and quarrying conditions, it is necessary to improve the components of gas equipment (cryogenic tank, gas nozzles, fuel supply cryogenic tubes, etc.) for supplying liquefied natural gas to the engine, as well as storage of liquid methane in a cryogenic tank with a long service life. For this, it is necessary to consider the process of heat and mass transfer of liquefied natural gas in a two-phase liquid-gas medium, taking into account the phase transition in the closed volume of the cryogenic tank under consideration. The article presents a model of unsteady heat and mass transfer of a two-phase liquefied methane medium in a developed two-tank cryogenic tank using a Cartesian coordinate system with fractional control volumes in space. The experimental data confirm the efficiency of using a cryogenic tank on the VEH platform, in which the run on liquefied methane compared to standard fuels is tripled, the shelf life of liquefied gas in the proposed cryogenic tank is 2-2.5 times longer than in the standard one.
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Date submitted2019-07-09
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Date accepted2019-09-07
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Date published2020-04-24
Promising model range career excavators operating time assessment in real operating conditions
The development prospects of the mining industry are closely related to the state and development of modern mining machinery and equipment that meet the technical and quality requirements of mining enterprises. Enterprises are focused on a quantitative assessment – the volume of mineral extraction, depending on the functioning efficiency of a promising series of mining machines, which include modern mining excavators. Downtime and unplanned shutdowns of mining excavators directly depend on the operating conditions of the mining machine, which has negative influence on the machine as a whole and its technical condition, which entails a decrease in the efficiency of using expensive mining equipment and economic losses of the mining enterprise. The rationale for external factors that affect the operating time and technical condition of mining excavators is given. For a more detailed assessment of the influence of external influences on the efficiency of operation of mining machines, the influencing factors are divided into two groups: ergatic, directly related to human participation, and factors of a natural-technogenic nature, where human participation is minimized. It was revealed that factors of a natural-technogenic nature have the greatest influence. An algorithm is proposed for a comprehensive assessment of the technical condition and forecasting of operating time both in nominal and in real operating conditions, taking into account factors of a natural and technogenic nature. It is proposed, based on the developed program for planning and evaluating the life of a mining excavator, to adjust the schedules for maintenance and repair (MOT and R) in order to minimize the number of unplanned downtime of a mining excavator and maintain it in good condition.
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Date submitted2018-12-25
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Date accepted2019-03-08
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Date published2019-06-25
Determination of the operating time and residual life of self-propelled mine cars of potassium mines on the basis of integrated monitoring data
Statistical data on the reliability of self-propelled mine cars (SPMC), operating in the potassium mines of the Verkhnekamskoye potassium and magnesium salts deposit are analyzed. Identified the main nodes that limit the resource SPMC. It has been proven that the most common failures of self-propelled cars are the failure of wheel hubs, bevel gears and traveling electric motors. The analysis of the system of maintenance and repair of mine self-propelled cars. It is indicated that the planning and preventive system of SPMC repairs is characterized by low efficiency and high material costs: car maintenance is often carried out upon the occurrence of a failure, which leads to prolonged downtime not only of a specific haul truck, but of the entire mining complex. A method for assessing the technical condition of the electromechanical part of a mine self-propelled car by the nature of power consumption is proposed. This method allows you to control the loading of the drives of the mine self-propelled car, as well as to assess the technical condition of the drives of the delivery machines in real time. Upon expiration of the standard service life of a mine propelled car specified in the operational documentation, its further operation is prohibited and the car is subject to industrial safety expertise. As part of the examination, it is necessary to determine the operating time and calculate the service life of a mine self-propelled car outside the regulatory period. A method has been developed for determining the residual service life of mine car on the basis of instrumentation control data in the conditions of potash mines.
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Date submitted2018-07-21
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Date accepted2018-09-14
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Date published2018-12-21
Natural ventilation of gas space in reservoir with internal floating roof
- Authors:
- M. G. Karavaichenko
- N. M. Fathiev
The article deals with safe operation issues of vertical steel reservoirs with an internal floating roof when storing volatile oil products. The purpose of the work is to study the influence of ventilation openings area and wind speed on the duration of explosive state of vertical reservoirs with an internal floating roof. The influence of ventilation pipes' dimensions and the wind speed on the duration of explosive state of the reservoir has been studied. Method for calculating this time is proposed. It is shown that natural ventilation of the reservoir gas space is caused by the effect of two forces, which are formed due to: 1) the density difference between the vapor-air mixture in the reservoir and outside air; 2) wind pressure occurring on the roof of the reservoir. An algorithm for calculating the duration of reservoir being in an explosive state with wind pressure and no wind is obtained. The greater the difference in geodetic marks of the central and peripheral nozzles, the more efficient the ventilation. This distance will be greatest if the lower ventilation pipes are located on the upper belt of the reservoir or the reservoir is equipped with an air drain. Increase in wind speed of more than 10 m/s does not significantly affect the duration of the reservoir being in an explosive state. Increasing the diameter of the central nozzle from 200 to 500 mm can significantly reduce the duration of the reservoir degassing in windless weather.
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Date submitted2017-12-28
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Date accepted2018-03-03
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Date published2018-06-22
Special features of a structure of technical operations for peat excavation with stage dewatering
- Authors:
- E. A. Kremcheev
A method of development of a technology of peat extraction for intensifying of dewatering which involves drying of peat raw materials in thick layers with a layer-by-layer harvesting into large-sized roll with further delivery to the field storage unit of the enlarged sizes is presented in the paper. Throughout the year storage raw materials may be transported to the customer or to the shopfloor for further processing. Considering dimension and mass characteristics, a crumbed peat of various moisture capacity is a major type of products to be of high demand. On the basis of the results of scientific studies regarding gravity dewatering of peat and its drying in field environment, the ways of intensifying of field dewatering of peat for extraction at shallow-peat lands and fine-limit fields are proposed. The presented results of the experimental performance of a technology of peat drying in thick layers with a layer-by-layer harvesting indicate an increase of seasonal harvesting and a decrease of the influence of unfavorable meteorological factors on the stability of the extraction process. Performed investigations allowed to develop a structure of technical operations for peat excavation with the stage dewatering in spreading and intermediate storage units providing rational state of the extraction process regarding a complex of technical factors. A suggested scheme of a process area for a primary and secondary period of deposit exploitation by a technology of peat excavation is considered.
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Date submitted2017-11-08
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Date accepted2018-01-20
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Date published2018-04-24
Major trends in efficiency upgrading of the economic activity in the Arctic zone of Russian Federation
Organization of efficient economic activity in the Arctic zone requires development of human potential, transport infrastructure, exploitation of natural resources under the conditions of greatest possible environmental safety. In order to choose preferable trends of economic development and to provide efficiency of operations in the Arctic zone it is crucial to perform research in the areas of industrial efficiency upgrading and rational use of fuel, energy, mineral, chemical and biological resources of the Ocean and littoral areas of Russian Arctic. The paper analyzes major trends in the research on increasing economic efficiency of operations aimed at territory development in the Arctic zone. The authors justify the need to examine economic problems of rational resource use in the Arctic zone of Russia based on the proposed system of resource-estimation indicators and their application in establishing a mechanism of rational resource use with a due regard to protection of the marine environment. The paper also focuses on methodological problems of the target programme approach to complex development of the Arctic zone, creation of target programmes, industrial development and rational use of natural resources. The authors give rationale for the key task in this area – development of methodological principles of forming federal and regional target programmes, aimed at exploration, exploitation and rational use of natural resources in the Arctic zone of Russian Federation. An analysis is provided that focuses on the problems of creating a scientifically justified hierarchical system of programmes and regional regulations, creation of a scientific information data bank and other methodological issues.
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Date submitted2015-12-17
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Date accepted2016-03-01
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Date published2016-12-23
Anomalous geochemistry of zircon from the Yastrebetskoe rare metal deposit (SIMS- and TOF-study)
- Authors:
- S. G. Skublov
- S.-Kh. Li
A detailed isotopic geochemical study (secondary ions mass-spectrometry – SIMS, time-of-flight mass-spectrometry – TOF) of zircon from ore-bearing syenites of the Yastrebetskoe rare metal-rare earth deposit (the Ukrainian Shield) has yielded proofs of magmatic genesis of the deposit: unaltered central parts of zircon grains typically feature characteristic magmatic spectra of REE distribution, their values of δ 18 O staying somewhat higher than the mantle value (6.5 ‰, on the average). During the final stage of forming the deposit the role of fluorine-water-bearing fluids enriched with Y, REE, Nb, Ве and heavy oxygen had increased, as directly reflected in the anomalous isotopic-geochemical characteristics of zircon rims and zones of zircon alteration (the contents of Y reaches 61874 ppm, that of Nb – 7976 ppm, Be – 1350 ppm, δ 18 O reaches 12.42‰, F – 0.7 % mass, H 2 O – 4% mass).
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Date submitted2015-08-23
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Date accepted2015-10-26
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Date published2016-04-22
Low-voltage electrical apparatus
- Authors:
- S. M. Apollonskii
- Yu. V. Kuklev
The article describes the main trends in the development of low-voltage electrical appliances and related accessories, as well as issues of efficiency, reliability and safety. According to the authors, the main trends in the development of low-voltage apparatus can be considered: the transition from the use of certain devices to the system devices, unified by the process of installation and running in standard modules and comply with all the functional requirements of control systems; improving the standardization and normalization of the EA on an international scale; unification of constructive elements of the EA; increase the volume of production of complete device management and contactless application logic control systems and specialized computers for management purposes; increase the proportion of contactor relay equipment DC, performs a variety of control functions. Improved security service low voltage, through the use of low voltage (24 V DC, 110 V AC), voltage presence signaling devices; increase the proportion of and the use of combined control and protection devices as well as devices for the automation of recruitment and duty cycles of machines: differentsequencer, track control devices, relays, pulse counting, and so on. n.
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Date submitted2009-09-03
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Date accepted2009-11-05
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Date published2010-06-25
Multimedia presentations as an element of lecturer work in technical higher school
- Authors:
- N. A. Egorenkova
This article is devoted to methodological aspects of modern computer technologies introduction to liberal arts teaching in technical higher school. Question of reasonability of lectures accompaniment by multimedia presentation is depicted. The experience of Russian Language and Culture of Speech lectures multimedia presentation creation is described in the article, recommendations to blocks of presentation preparation are given, some methods of working with Microsoft PowerPoint program with the help of which studying process could be done more effective, multisided, attractive, dynamic, possible to stimulate students’ creative activity are described.
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Date submitted2009-09-23
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Date accepted2009-11-23
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Date published2010-06-25
Experience of mediatext in social culture teaching creating
- Authors:
- I. V. Trofimova
This article is devoted a problem of creation of the mediatext as new format for presentation of the scientific information. On a material of culture of the 1930 which have marked transition from avant-garde to totalitarianism, the (video) picture reflecting leading tendencies of an epoch and the form of their artistic realisation is built.
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Date submitted2009-08-02
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Date accepted2009-10-29
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Date published2010-02-01
Forecasting the power consumption of mines on the basis of stochastic time-series models
- Authors:
- A. A. Chernysh
- O. B. Shonin
The paper is devoted to building up time series models to forecast the power consumption of a mine. The results discussed are obtained using various linear filter models and artificial neural network. The wavelet transform of the raw time series is shown to be an efficient technique to increase the forecasting accuracy.
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Date submitted2008-10-26
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Date accepted2008-12-14
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Date published2009-12-11
MODEM 3D new software for the interpretation of IP-affected 3D tem data
- Authors:
- M. I. Ivanov
- V. A. Kateshov
- I. A. Kremer
- M. I. Epov
MODEM 3D software is presented, which is intended for direct modeling of formation processes of electromagnetic fields created by compound inductance-galvanic type sources (earthed horizontal electrical line) in time domain. Numerical stability of used algorithms is displayed on the example of medium, which contains nonstructural oil pool.