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Date submitted2024-05-28
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Date accepted2024-11-07
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Date published2024-12-25
Methods of intensification of pipeline transportation of hydraulic mixtures when backfilling mined-out spaces
The paper presents an analysis of the advantages and limitations of additional measures to intensify the transportation of the backfill hydraulic mixture flow. The results of the analysis of the conditions for using pumping equipment to move flows with different rheological properties are shown. Generalizations of the methods for influencing the internal resistance of backfill hydraulic mixtures by means of mechanical activation, as well as increasing fluidity due to the use of chemical additives are given. The article presents the results of studies confirming the feasibility of using pipes with polymer lining, which has proven its efficiency in pumping flows of hydraulic mixtures with different filler concentrations. An analytical model of hydraulic mixture movement in the pipeline of the stowage complex has been developed. The trends in pressure change required to ensure the movement of hydraulic mixture in pipelines of different diameters are exponential, provided that the flow properties are constant. The effect of particle size on the motion mode of the formed heterogeneous flow, as well as on the distribution of flow density over the cross-section, characterizing the stratification and change in the rheological properties of the backfill hydraulic mixture, is assessed. An analytical model of centralized migration of the dispersed phase of the hydraulic mixture flow is formulated, describing the effect of turbulent mixing of the flow on the behavior of solid particles. An assessment of the secondary dispersion of the solid fraction of the hydraulic mixture, which causes a change in the consistency of the flow, was performed. The studies of the influence of the coefficient of consistency of the flow revealed that overgrinding of the fractions of the filler of the hydraulic mixture contributes to an increase in the required pressure in the pipeline system.
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Date submitted2023-07-05
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Date accepted2024-06-03
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Date published2024-12-25
Complete extraction of conditioned ores from complex-structured blocks due to partial admixture of substandard ores
- Authors:
- Bayan R. Rakishev
The paper presents mining-technological substantiation of complete extraction of conditioned ores from complex-structured blocks of benches by mixing a layer of substandard ores of certain sizes. The relevance of the work consists in the development of innovative methods of establishing the parameters of the substandard layer of ores to be added to the conditioned ores. The main problem is to ensure complete extraction of useful components into concentrate from shipped ore with acceptable deviations from the required ones. A new typification of complex-structured ore blocks of the bench has been carried out. Analytical dependences of mining and geological characteristics of complex-structured ore blocks were obtained. Theoretical dependences for determining the main indicators of mineral processing are derived. Analytical dependences for determination of the content of useful component in shipped ore α' – mixture of conditioned ore with the content of useful component α and admixed layer of substandard ore with the content of useful component α'' are offered. For the first time in mining science, a new approach of complete extraction of conditioned ores from complex-structured blocks of benches by grabbing a certain part of substandard ores during excavation, increasing the volume of extracted ore and expanding the extraction of useful components in the concentrate has been substantiated. The increment of useful components can reach 10-15 % of the total volume of extraction, which allows predicting a significant increase in the completeness of mineral extraction from the Earth's interior.
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Date submitted2023-01-16
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Date accepted2023-06-20
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Date published2024-04-25
Study on the thin layer drying and diffusion mechanism of low rank coal in Inner Mongolia and Yunnan
Coal is one of the world's most important energy substances. China is rich in coal resources, accounting for more than 90 % of all ascertained fossil energy reserves. The consumption share of coal energy reaches 56.5 % in 2021. Due to the high moisture content of low-rank coal, it is easy to cause equipment blockage in the dry sorting process. This paper considers low-rank coal coming from Inner Mongolia (NM samples) and Yunnan (YN samples). The weight loss performance of the samples was analyzed using thermogravimetric experiments to determine the appropriate temperature for drying experiments. Thin-layer drying experiments were carried out at different temperature conditions. The drying characteristics of low-rank coal were that the higher the drying temperature, the shorter the drying completion time; the smaller the particle size, the shorter the drying completion time. The effective moisture diffusion coefficient was fitted using the Arrhenius equation. The effective water diffusion coefficient of NM samples was 5.07·10–11 - 9.58·10–11 m2/s. The effective water diffusion coefficients of the three different particle sizes of YN samples were 1.89·10–11 - 4.92·10–11 (–1 mm), 1.38·10–10 - 4.13·10–10 (1-3 mm), 5.26·10–10 - 1.49·10–9 (3-6 mm). The activation energy of Inner Mongolia lignite was 10.97 kJ/mol (–1 mm). The activation energies of Yunnan lignite with different particle sizes were 17.97 kJ/mol (–1 mm), 33.52 kJ/mol (1-3 mm), and 38.64 kJ/mol (3-6 mm). The drying process was simulated using empirical and semi-empirical formulas. The optimal model for Inner Mongolia samples was the Two-term diffusion model, and Yunnan samples were the Hii equation was used.
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Date submitted2020-05-16
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Date accepted2020-07-30
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Date published2020-12-29
Results of the study of kinetic parameters of spontaneous combustion of coal dust
The article is devoted to the study of the problem of spontaneous combustion of energy grades of coal not only during storage, but also during transportation. As the main samples for the study, the energy grades of SS and Zh coals were selected. The main task of the scientific research was to study the rate of cooling and heating of coal depending on their thermophysical parameters and environmental parameters. To solve this problem, the authors used both the author's installations designed to study the thermophysical parameters of the spontaneous combustion process (the Ya.S.Kiselev method), and the NETZSCH STA 449 F3 Jupiter synchronous thermal analysis device, the NETZSCH Proteus Termal Analysis software package. On the basis of a complex study of the spontaneous combustion process, the authors of the article obtained the kinetic characteristics of the spontaneous heating process (activation energy and pre-exponential multiplier). Nomograms of the permissible size of coal density of different types and shapes of accumulation depending on the ambient temperature are presented, practical recommendations for the prevention (avoidance) of spontaneous combustion of coal fuel are given.
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Date submitted2019-05-24
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Date accepted2019-07-15
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Date published2019-10-23
Effective Power and Speed of Mining Dump Trucks in Fuel Economy Mode
- Authors:
- V. I. Alexandrov
- M. A. Vasileva
- V. Y. Koptev
Existing methods for determining the effective power, based on the calculation of the average indicator operation of the engine during the piston stroke, do not take into account the change in thermodynamic parameters and the polytropic operation of the engine, the value of which depends on the polytropic efficiency of the duty cycle. This is the reason that the calculation of the effective power leads to some error – the margin of the engine features. The identification of this stock allows us to review the entire line of dump trucks in the direction of increasing their pass- port effective capacity, which will lead to a reduction in capital purchase costs due to the choice of a previously un- derestimated and cheaper option, as well as a reduction in current operating costs due to a decrease in the specific fuel consumption rate. Taking into account the stochastic nature of the transport process and assessing the influence of all external and internal factors when calculating the rational mode of operation of a mining truck can further reduce specific fuel consumption by choosing the rational speed of its movement in loaded and empty directions.
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Date submitted2018-10-28
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Date accepted2018-12-30
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Date published2019-04-23
Development and research of formation technologies on specialized presses with subsequent sintering of high-density details from iron-based powders
- Authors:
- A. M. Dmitriev
- N. V. Korobov
- A. Zh. Badalyan
Creating shifts of the lyaers in a deforming workpieces improves the quality of the product produced by pressure treatment. qual-channel angular pressing and precipitations of a cylindrical billet with a rotating turnaround were developed by specialists earlier and became basic for scientists engaged in nanotechnology. One of the most modern schemes for creating nanostructures by processing on presses is the «Cyclic Extrusion Compression» scheme (in Russia – «Hourglass»), which has significant drawbacks. To date, research on the creation of layer shifts in compacted metal powders is substantially less than in compaction of compact blanks. The article developed compaction schemes for presses of blanks from iron-based powders that have a certain analogy with the «Hourglass», while lacking the disadvantages inherent in the named scheme and implemented on the created samples of specialized hydraulic presses. The results of the studies of density, strength and microhardness before sintering the samples molded from a number of domestic and imported powders on iron base, including those doped with carbon and other alloying components, are described. It has been established that with the use of the formation schemes for powders providing large shifts between particles, the density of the preforms increases on average by 10-12 %. With an average stress (16.32 MPa) of the transverse section of the molded specimen prior to its sintering, molding with shifts between particles increases this stress by 78 %. The strength after sintering of samples made using the compaction schemes developed by the authors of the article increases approximately by 2 times. Magnetic pulse treatment (MPT) of a molded sample prior to its sintering increases its resistance to shearing before sintering, regardless of the molding pattern. When MPT of both the powder and the molded sample is executed, the most uniform distribution of microhardness in the sample is achieved, and after subsequent sintering, the most uniform distribution of the mechanical characteristics of the product. The results of all studies are described by regression equations.
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Date submitted2018-09-10
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Date accepted2018-11-06
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Date published2019-02-22
Comparative analysis of zincand tin oxidation with acids at room temperatures
- Authors:
- S. D. Pozhidaeva
- L. S. Ageeva
- A. M. Ivanov
The paper analyses the parameters of deep oxidation of zinc and tin by copper (II) compounds and molecular iodine in the presence of molecular oxygen and hydrogen peroxide, as second oxidizers working synchronously with them in various media (aqueous, aqueous-organic and organic) with the participation of mineral and carboxylic acids close to room temperature. The contribution of the reactivity of the metal to its rate of consumption, especially the average, is often much less than the contribution associated with the release characteristics of the working surface, determined by the rates of accumulation of surface deposits of metal oxidation products, their strength and adhesion characteristics their destruction and shifting into the bulk phase.
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Date submitted2015-08-25
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Date accepted2015-10-24
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Date published2016-04-22
The modern technology of drilling and casing of well during the exploration of gas hydrates
- Authors:
- N. I. Nikolaev
- Lyu Tyanle
In the paper, the perspectives of exploration and completion of gas hydrate fields and the drilling problems in the gas hydrates of the northwest china are studied. It has been established, that the main reasons of complications in the Muli field are the secondary hydrate formation on the walls of the well and drilling assembly and ice formation inside the set cement during the well drilling and completion in permafrost. It has been shown, that in the areas with permafrost during the drilling of the layers containing gas hydrates, temperature and pressure changes can lead to the dissociation of hydrates. At the same time, pressure increase in the annular space due to the gas release, can lead to the secondary formation of gas hydrates, drill string stuck, ceasing of drilling fluid circulation, which is the reason of serious trouble in the wellbore. The results of the research on the development of drilling fluids compositions, which lower the drilling troubles of permafrost, are presented. Comparative experiments have been conducted to evaluate the effectiveness of thermodynamic and kinetic inhibitors, which prevent the repeated hydrate formation. It has been established, that the kinetic inhibitors have the clear advantage: they have good inhibiting effects even with low amounts of additives. In the laboratory conditions, the researches have been conducted to evaluate the phase equilibrium of gas hydrates during their reaction with the water solutions, containing kinetic inhibitor PVP. A thin clay drilling mud has been developed on the water base, providing the holding of the temperature in the level of –2 °С and its effectiveness for the gas hydrate fields in the PRC has been shown. Casing effectiveness of unstable rocks during the drilling in the conditions of negative temperatures inside the well largely depends on their physical-mechanical properties, composition and the technical indicators of cement materials. The authors suggest the composition of quick-setting cements based on aluminum binding materials. It has been established, that the analyzed compositions have the ability to considerably improve the results of cementing.
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Date submitted2015-08-09
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Date accepted2015-10-05
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Date published2016-04-22
Inorganic and organic vitreous foam materials and prospect of environmental cleaning from oil and oil products pollutions
- Authors:
- V. E. Kogan
The analysis of own experimental materials which are part of the new scientific direction – complex research of physical and chemical regularities of novel inorganic and organic vitreous sorbents and investigation of the oil and oil products absorption processes by that sorbents developed on department of the General and Physical Chemistry of National Mineral Resources University (Mining University) under the leadership of the author of this paper is provided. In particular, specifics of kinetic curves of oil absorption for sorbents with a vitreous surface are experimentally established and theoretically proved by the conducted researches.
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Date submitted2015-07-16
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Date accepted2015-09-28
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Date published2016-02-24
Examination of the raw materials and the products of the combustible shales processing
- Authors:
- N. K. Kondrasheva
- S. N. Saltykova
The reserves of combustible slates of Russia in shale oil and gas equivalent are more than the reserves of oil and natural gas. The formation of a large volume of ash is a major problem connected to the processing and the usage of the combustible slates. It is possible to look at this problem from a different angle of vision if a mineral part of slates is considered as a complex organo-mineral raw material where a mineral substance of the slates is the same raw material as the organic one. For this purpose, it is required to study in detail the physicochemical characteristics of the combustible slates and the behavior of the organic and the mineral parts of the slates during the heat treatment. This research focuses on the phase composition of Leningrad fuel shale and its changes on pyrolysis. They were studying the phase composition, the gas phase outlet, pyrolysis mass balance of combustible slates in the nitrogen atmosphere in the temperature range of 200-1000 °С, the porosity changes of combustible slate in the nitrogen atmosphere in the temperature range of 25-900 °С. It is determined that the main minerals of combustible slates are calcite (28 %), quartz (25 %), illite (17 %), and microcline (11 %). The temperature dependence of the shale porosity is studied in a nitrogen atmosphere and in air. The porosity changes in four stages: (I) 25-200 °C; (II) 200-400 °C; (III) 400-600 °C; (IV) 600-900 °C. The mass balance pyrolysis of combustible slates in a PTK_1.2_40 tube furnace is made up, in the nitrogen atmosphere of 200, 400, 600, 800 and 1000 °C.
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Date submitted2014-12-20
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Date accepted2015-02-13
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Date published2015-12-25
Design procedure of pressure losses for hydrotransport of the high concetration pulps
- Authors:
- V. I. Aleksandrov
- Pavel Vlasak
In the paper it is shown that application of standard design methods for hydrotransport used for slurry with small concentration of a solid phase and for hydrotransport of high concentration slurry leads to considerable divergences between practical values of pressure losses which are received as a result of calculation. A major factor, which defines errors of calculation of hydrotransport of slurry with high concentration of a solid phase by means of standard techniques, is that these techniques do not consider rheological characteristics and parameters substantially influencing the amount of spe-cific pressure losses. The offered model of a pulp movement and technique developed on the basis of this model allow to define hydrotransport parameters with a margin error no more than 0,1.
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Date submitted2010-07-06
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Date accepted2010-09-14
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Date published2011-03-21
Electromechanical processes in electric drives of mountain equipment on the basis of the synchronous electric motor
- Authors:
- A. O. Sviridenko
The description is given and the function chart of the bench installation is resulted, allowing to reproduce static and dynamic modes of adjustable electric drives of an alternating current. The modes considered during experimental researches of the electric drive on the basis of the synchronous electric motor, working in a mode of ventilniy electric motor are listed. Conclusions are drawn on character of course of dynamic modes, comparison of the electric drive to the synchronous electric motor and the electric drive of a direct current with the subordinated regulation is given.
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Date submitted2009-09-26
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Date accepted2009-11-21
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Date published2010-06-25
The measurements of emission parameters of tungsten thermo cathodes in plasma energetic equipments
Emission parameters and coefficients of reflection of heat electrons from tungsten thermo cathodes were investigated under nontraditional for emission electronic conditions, when the surface contacts with highly ionized plasma. For measurements plasma diode electron current-magnetic field strength relations were used. Parameter Dj, which characterizes cathode heterogeneity by work function, and coefficient of reflection for policrystallic tungsten and for face 110 tungsten single crystal were measured. Proportion entering in effective reflection coefficient of electrons, reflected immediately from the surface and from potential barrier of spots field was determinate.