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Date submitted2021-12-20
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Date accepted2024-05-02
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Date published2024-08-26
A new formula for calculating the required thickness of the frozen wall based on the strength criterion
- Authors:
- Mikhail А. Semin
- Lev Yu. Levin
The study delves into the elastoplastic deformation of a frozen wall (FW) with an unrestricted advance height, initially articulated by S.S.Vyalov. It scrutinizes the stress and displacement fields within the FW induced by external loads across various boundary scenarios, notably focusing on the inception and propagation of a plastic deformation zone throughout the FW's thickness. This delineation of the plastic deformation zone aligns with the FW's state of equilibrium, for which S.S.Vyalov derived a formula for FW thickness based on the strength criterion. These findings serve as a pivotal launchpad for the shift from a one-dimensional (1D) to a two-dimensional (2D) exploration of FW system deformation with finite advance height. The numerical simulation of FW deformation employs FreeFEM++ software, adopting a 2D axisymmetric approach and exploring two design schemes with distinct boundary conditions at the FW cylinder's upper base. The initial scheme fixes both vertical and radial displacements at the upper base, while the latter applies a vertical load equivalent to the weight of overlying soil layers. Building upon the research outcomes, a refined version of S.S.Vyalov's formula emerges, integrating the Mohr – Coulomb strength criterion and introducing a novel parameter – the advance height. The study elucidates conditions across various soil layers wherein the ultimate advance height minimally impacts the calculated FW thickness. This enables the pragmatic utilization of S.S.Vyalov's classical formula for FW thickness computation, predicated on the strength criterion and assuming an unrestricted advance height.
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Date submitted2024-04-11
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Date accepted2024-06-03
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Date published2024-07-04
Assessment of the efficiency of acid mine drainage purification (using the example of copper-pyrite mines in the Middle Urals)
According to the results of the anti-rating of regions with extreme pollution of watercourses in the Sverdlovsk region, the largest number of polluted rivers has been recorded in recent years – more than a quarter of all high and extremely high pollution. One of the sources of pollution of natural water bodies in the Middle Urals are closed and flooded copper-pyrite mines, where acidic mine drainage continue to form and unload to the surface. Several of them have organized collection and a two-stage acidic drainage purification system, including neutralization with lime milk and settling in a clarifier pond. Despite the identical schemes, different indicators of pollutants are recorded during discharge into water bodies. The aim of the work is to evaluate the effectiveness of the applied acid mine drainage purification system and identify the parameters affecting the quality of treated mine water. Laboratory studies were performed using methods of flame emission spectrometry, flame atomic absorption, atomic absorption spectrometry, mass spectrometry with ionization in inductively coupled plasma, potentiometric, etc. It has been established that the existing mine drainage purification system at the Degtyarskii mine makes it possible to significantly reduce the concentrations of most toxic components of mine waters to almost standard values. At the Levikhinskii mine, the multiplicity of exceeding the maximum permissible concentrations reaches hundreds and thousands of times. To achieve a higher degree of purification, it is necessary that the duration of passive purification is sufficient for the reactant to interact with acidic waters. However, to ensure this possibility, it will require the creation of a cascade of ponds with an area of several thousand hectares. If the current two-stage system is quite effective for the Degtyarskii mine, then for Levikhinskii it is necessary to switch to the use of more modern systems, including three stages of purification.
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Date submitted2024-04-22
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Date accepted2024-06-13
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Date published2024-07-04
Comprehensive utilization of urban wastewater sludge with production of technogenic soil
The article presents the analysis of the existing approach to wastewater sludge treatment and justifies the selection of the most promising management technology that allows maximum use of wastewater sludge resource po-tential. To obtain a useful product (biocompost) suitable for use as part of technogenic soil, experimental studies of aerobic stabilization of organic matter of dehydrated urban wastewater sludge with the addition of other waste by using passive composting technology were carried out. The technology is included in the list of best available technologies (BAT). The selection of the most optimal components for the mixture was based on the results of determining the C and N content, humidity and pH of the components used that ensured the composting of organic waste. The results of laboratory studies of the obtained biocompost according to the main agrochemical and sanitary-epidemiological indicators are presented. Testing was carried out according to the criterion of toxicity of the biocompost’s aqueous extract. The assessment of the technogenic soil was performed when using biocompost in its composition for compliance with existing hygienic requirements for soil quality in the Russian Federation. Based on the results of the vegetation experiment, optimal formulations of the technogenic soil were determined, i.e., the ratio of biocompost and sand, under which the most favorable conditions for plant growth are observed according to a combination of factors such as the number of germinated seeds, the maximum height of plants and the amount of biomass. The conducted research makes it possible to increase the proportion of recycled urban wastewater sludge in the future to obtain soils characterized by a high degree of nutrient availability for plants and potentially suitable for use in landscaping, the biological stage of reclamation of technogenically disturbed lands, as well as for growing herbaceous plants in open and protected soil.
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Date submitted2022-10-29
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Date accepted2023-10-25
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Date published2024-04-25
Assessment of rock massif sustainability in the area of the underground research laboratory (Nizhnekanskii Massif, Enisei site)
The study presents the results of the research on geodynamic and geological conditions of the Enisei site (Krasnoyarsk Krai), chosen for the construction of an underground research laboratory. The laboratory is being built at a depth of 500 m to assess the suitability of the rock mass for burying high-level radioactive waste. The rocks consist of weakly fractured gneisses, granites, and dikes of metadolerites. Field observations were conducted on bedrock outcrops. They included the determination of rock mass quality indicators, measurement of rock fracturing, and a rating classification of stability using N.Barton's method. GNSS observations were also made to monitor surface deformations. These data were used to develop a three-dimensional structural model, including lithology, fault disruptions, intrusive bodies, elastic-strength properties of rocks, and the sizes of zones influenced by faulting. It will serve as a basis for boundary conditions and the construction of three-dimensional variational models of stress-strain states, identifying zones of concentration of hazardous stresses, and planning in situ geomechanical experiments in underground mines of the laboratory. The obtained values of the modified QR index for the main types of rocks allowed their classification as stable and moderately stable, corresponding to strong and very strong rocks on Barton's scale and the massif rating according to geomechanical classification.
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Date submitted2022-05-17
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Date accepted2022-09-06
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Date published2022-11-03
Methodological substantiation of the choice for optimal modes of equipment operation during the stage-wise concentrate removal in iron ores beneficiation
- Authors:
- Alexandr S. Opalev
- Svetlana A. Alekseeva
The urgent task of improving the quality of iron ore concentrates was studied. We propose to use the stage-wise removal of the concentrate by combining fine screening, regrinding, and magnetic-gravity separation. Exemplified by magnetite ore from the Stoilensky GOK, a scientific and methodological approach to the search for optimal separation parameters and modes was substantiated. It includes several stages: studying the particle size distribution and release of useful components in the feed product to select classification parameters; a series of experiments on grinding oversize products to diverse sizes; beneficiation of the obtained products by MG separation. To select the optimal parameters of ore preparation, an analysis of the beneficiation efficiency was used, which is calculated according to the Hancock – Luyken criterion. The results of the research are experimental dependences that connect the process parameters of beneficiation with those of fine vibratory screening. For the studied ferruginous quartzite ore processed at the Stoilensky GOK, the obtained dependences can be described by a second-order polynomial with a high accuracy of approximation. The best performance is achieved with a particle size of 0.1 mm: Fe tot content in the concentrate is 69.7 %, recovery is 85 %, classification efficiency is 80.4 %. The top size of the product in this case is 0.076 mm, which corresponds to 70-73 % grinding size of –0.045 class.
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Date submitted2022-04-14
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Date accepted2022-07-21
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Date published2022-11-03
In-situ leaching of molybdenum and uranium by percarbonate and chloride-hypochlorite solutions
In-situ leaching of molybdenum and uranium is becoming an increasingly common process. The features of the material composition of ores, leading to a decrease in their filtration properties, were considered. Activation leaching with leaching solutions that have undergone electrophotochemical activation before contact with the ore mass were studied. Activation preparation of leaching solutions promotes the synthesis of clustered water molecules with collectivized protons and hydroxyl ions, as well as active forms of oxygen and hydrogen. Cell leaching of molybdenum from mature tailings of the Shakhtaminsk deposit was studied experimentally. After pre-oxidation with an active carbonate solution, a model borehole leaching was carried out with a chloride-hypochlorite solution. Molybdenum extraction on resin a was 85 % in 30 days. Experiments on the percolation leaching of uranium from the ores of the Uchkuduk and Sugraly deposits confirmed the potential possibility of a significant increase in the extraction of uranium by electrophotoactivated percarbonate solutions relative to aqueous solutions of sodium and ammonium carbonate. When leaching with carbonate solutions without an additional oxidizing agent, the extraction of uranium from the Sugraly deposit ore sample was 52 and 59 % (sodium carbonate and ammonium carbonate). The use of hydrogen peroxide as an oxidizing agent made it possible to achieve 87-88 % extraction into pregnant solutions in 21 days without pre-oxidation. The performed studies confirm the processing capability of extracting uranium and molybdenum by percolation leaching in columns and borehole leaching.
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Date submitted2022-06-02
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Date accepted2022-07-21
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Date published2022-10-05
Substantiation of the optimal performance parameters for a quarry during the stage-wise development of steeply dipping ore deposits
- Authors:
- Sergey I. Fomin
- Maxim P. Ovsyannikov
The use of stage-wise schemes in the development of deep quarries is one of the ways to increase the economic efficiency of mining a deposit and determining the optimal stage parameters remains an urgent task. Such parameters are stage depth, bench height, block length, etc. However, there is a wide range of values for these parameters. Therefore, to select the optimal values and evaluate the effectiveness of design solutions, it is advisable to use the net present value, which is an international notion. As a result of the analysis of data on deposits, a large number of variable indicators can be identified that presumably affect the efficiency of mining. The article proposes to divide all parameters of the quarry mining into two types: mine engineering and economic. The importance of each of them is determined by the measure of influence on the net present value. Thus, to assess the measure of influence of mining indicators, the average values of each of them are taken, and as a result of the alternating change of one parameter under study, the measure of its influence on the discounted income received is estimated. The results of the analysis of relevant factors, their evaluation and comparative analysis are important indicators that significantly affect the design decisions made and the effectiveness of the investment project.
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Date submitted2022-01-24
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Date accepted2022-04-26
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Date published2023-04-25
Forecast of radionuclide migration in groundwater of the zone affected by construction drainage at the Leningrad NPP-2
The distribution of natural (at the level of global background) and technogenic radionuclides in groundwater of the industrial zone in Sosnovy Bor town, where several nuclear power facilities are operating, was analyzed. The main technogenic radionuclides recorded in groundwater samples are cesium ( 137 Cs), strontium ( 90 Sr), and tritium isotopes. The first two aquifers from the surface are subject to contamination: the Quaternary and the upper zone of the Lomonosov aquifer. Based on extensive material on the engineering and geological studies of the work area, a 3D geological model and hydrodynamic and geomigration models of the industrial zone were constructed. By means of modeling, the extent and nature of changes in hydrogeological conditions of area resulting from the construction and operational drainage of the new stage of the Leningrad Nuclear Power Plant (LNPP-2) were determined. The “historical” halo of radioactive contamination of groundwater forming (1970-1990) at the site adjacent to the NPP, where the storage facility of low- and medium-level radioactive waste is located, falls into the zone of influence. Interpretation of monitoring data allowed obtaining the migration parameters for predictive estimates. Modeling has shown that during the time of the LNPP-2 operation there was no intake of contaminated water by the drainage system of the new power plant.
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Date submitted2021-05-31
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Date accepted2022-03-24
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Date published2022-07-13
Mathematical model of linear and non-linear proppant concentration increase during hydraulic fracturing – a solution for sequential injection of a number of proppant types
It is known that much of the technology aimed at intensifying fluid inflow by means of hydraulic fracturing involves the use of proppant. In order to transport and position grains in the fracture, a uniform supply of proppant with a given concentration into the fracturing fluid is ensured. The aim of the operation is to eliminate the occurrence of distortions in the injection program of proppant HF. A mathematically accurate linear increase of concentration under given conditions is possible only if the transient concentration is correctly defined. The proposed approach allows to correctly form a proppant HF work program for both linear and non-linear increase in proppant concentration. The scientific novelty of the work lies in application of a new mathematical model for direct calculation of injection program parameters, previously determined by trial and error method. A mathematical model of linear and non-linear increase of proppant concentration during HF was developed. For the first time, an analytical solution is presented that allows direct calculation of parameters of the main HF stages, including transient concentrations for given masses of the various types of proppant. The application of the mathematical model in formation of a treatment plan allows maintaining correct proppant mass distribution by fractions, which facilitates implementation of information and analytical systems, data transfer directly from a work program into databases. It is suggested to improve spreadsheet forms used in production, which would allow applying mathematical model of work program formation at each HF process without additional labour costs. The obtained mathematical model can be used to improve the software applied in the design, modelling and engineering support of HF processes.
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Date submitted2021-03-18
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Date accepted2021-11-30
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Date published2021-12-27
Deformations assessment during subway escalator tunnels construction by the method of artificial freezing of soil for the stage of ice wall formation
- Authors:
- Evgenii M. Volokhov
- Diana Z. Mukminova
The work is devoted to the study of the processes of displacement and deformation of the surface during the escalator tunnels construction of the subway by the method of artificial freezing of soils. The features of the construction and freezing technology, the rocks characteristics in which the escalator tunnels made are considered. The data of specially organized, full-scale surveying observations of deformations on the earth surface are presented. The main factors influencing deformation processes in the frozen strata of a layered inhomogeneous rock mass with inclined tunneling are determined, the complexity of the predictive task and the need to simplify the design scheme are shown. The work is focused on the assessment of the least studied geomechanical processes of soil heaving-uplifts and deformations during the periods of active and passive freezing stages. When studying the displacements processes of the earth surface and rock mass, the finite element method and analysis of the obtained data using field observations of displacements were used. A simplified calculation scheme is proposed for modeling, which allows taking into account the uneven influence of frozen rocks of an inhomogeneous layered rock mass with a large inclined tunneling. The satisfactory convergence of the data of field surveying observations on the earth surface and the results of modeling geomechanical processes for the period of active and passive freezing stages is shown. The proposed calculation scheme is recommended for the prediction of deformation at the stages of underground construction, characterized by the development of the most dangerous tensile deformations of buildings and structures on the surface.
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Date submitted2021-03-16
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Date accepted2021-07-27
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Date published2021-10-21
Allocation of a deep-lying brine aquifer in the rocks of a chemogenic section based on the data of geophysical well logging and 2D seismic exploration
Advancement in the production of potassium fertilizers is an important strategic task of Russian agricultural industry. Given annually growing production rates, the reserves of discovered potassium-magnesium salt deposits are noticeably decreasing, which creates the need to ensure stable replenishment of the resource base through both the discovery of new deposits and the exploitation of deep-lying production horizons of the deposits that are already under development. In most cases, deposits of potassium-magnesium salts are developed by underground mining. The main problem for any salt deposit is water. Dry salt workings do not require any additional reinforcement and can easily withstand rock pressure, but with an inflow of water they begin to collapse intensively – hence, special attention is paid to mine waterproofing. Determination of spatial location, physical and mechanical properties of the aquifer and water-blocking stratum in the geological section represent an important stage in the exploration of a salt deposit. The results of these studies allow to validate an optimal system of deposit development that will minimize environmental and economic risks. On the territory of Russia, there is a deposit of potassium-magnesium salts with a unique geological structure – its production horizon lies at a considerable depth and is capped by a regional aquifer, which imposes significant limitations on the development process. To estimate parameters of the studied object, we analyzed the data from CDP seismic reflection survey and a suite of methods of radioactive and acoustic well logging, supplemented with high-frequency induction logging isoparametric sounding (VIKIZ) data. As a result of performed analysis, we identified location of the water-bearing stratum, estimated average thickness of the aquifers and possible water-blocking strata. Based on research results, we proposed methods for increasing operational reliability of the main shaft in the designed mine that will minimize the risks of water breakthrough into the mine shaft.
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Date submitted2021-03-30
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Date accepted2021-05-26
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Date published2021-09-20
Improving the efficiency of autonomous electrical complexes of oil and gas enterprises
- Authors:
- Boris N. Abramovich
- Ivan A. Bogdanov
In accordance with the Energy Strategy until 2035, the possibility of increasing the efficiency of energy use of secondary energy resources in the form of associated oil and waste gases has been substantiated by increasing the energy efficiency of the primary energy carrier to 90-95 % by means of cogeneration plants with a binary cycle of electricity generation and trigeneration systems with using the energy of the waste gas to cool the air flow at the inlet of gas turbine plants. The conditions for maintaining the rated power of the main generator with variations in the ambient temperature are shown. An effective topology of electrical complexes in a multi-connected power supply system of oil and gas enterprises according to the reliability condition is presented, which allows increasing the availability factor by 0.6 %, mean time between failures by 33 %, the probability of failure-free operation by 15 % and reducing the mean time of system recovery by 40 %. The article considers the use of parallel active filters to improve the quality of electricity and reduce voltage drops to 0.1 s when used in autonomous electrical complexes of oil and gas enterprises. The possibility of providing uninterrupted power supply when using thyristor systems for automatic reserve input has been proven. A comparative analysis was carried out to assess the effect of parallel active filters and thyristor systems of automatic transfer of reserve on the main indicators of the reliability of power supply systems of oil and gas enterprises.
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Date submitted2020-05-16
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Date accepted2021-03-02
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Date published2021-04-26
Study of drive currents for lifting bridge cranes of metallurgical enterprises for early diagnosis of load excess weight
The article discusses an approach based on the analysis of the drive motor currents to create an additional means of protection against emergency situations during the operation of bridge cranes associated with lifting a load with a mass exceeding the permissible one . A mathematical model of an overhead crane drive is described, as well as the results of computer simulation. It is shown that in the process of lifting up, before the stage of lifting the load, the stator current of the drive electric motor does not depend of the load mass, but when the load is detached, already for several periods of the mains voltage after the rope is pulled, when the mass of the load is exceeded, a measurable excess of the amplitude value of the current is recorded. This pattern has been confirmed for a number of cranes of various lifting capacities used at metallurgical enterprises. The possibility of diagnosing excess weight of the lifted load with a higher speed than existing mechanical methods of overload control is demonstrated, at the same time it is not required to make changes to the structural elements of overhead cranes.
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Date submitted2020-05-26
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Date accepted2020-06-10
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Date published2020-06-30
Theoretical analysis of frozen wall dynamics during transition to ice holding stage
Series of calculations for the artificial freezing of the rock mass during construction of mineshafts for the conditions of a potash mine in development was carried out. Numerical solution was obtained through the finite element method using ANSYS software package. Numerical dependencies of frozen wall thickness on time in the ice growing stage and ice holding stage are obtained for two layers of the rock mass with different thermophysical properties. External and internal ice wall boundaries were calculated in two ways: by the actual freezing temperature of pore water and by the temperature of –8 °С, at which laboratory measurements of frozen rocks' strength were carried out. Normal operation mode of the freezing station, as well as the emergency mode, associated with the failure of one of the freezing columns, are considered. Dependence of a decrease in frozen wall thickness in the ice holding stage on the duration of the ice growing stage was studied. It was determined that in emergency operation mode of the freezing system, frozen wall thickness by the –8 °C isotherm can decrease by more than 1.5 m. In this case frozen wall thickness by the isotherm of actual freezing of water almost always maintains positive dynamics. It is shown that when analyzing frozen wall thickness using the isotherm of actual freezing of pore water, it is not possible to assess the danger of emergency situations associated with the failure of freezing columns.
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Date submitted2019-03-31
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Date accepted2019-08-25
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Date published2020-02-25
Cascade frequency converters control features
The structures of systems with high-voltage cascade frequency converters containing multi-winding transformers and low-voltage low-power converters connected in series at each output phase of the load are considered. Low-voltage blocks contain three-phase diode or active rectifiers, DC capacitor filters, single-phase stand-alone voltage inverters and block disconnecting devices in partial modes (in case of failure when part of the blocks are disconnected). The possibilities of operation of cascade converters are determined, equations for correcting tasks to units in partial modes are given, tables of correction of tasks with estimates of achievable load characteristics are proposed. The results of experiments on the model of a powerful installation with a cascade frequency converter are presented, confirming the possibility of ensuring the symmetry of the load currents when disconnecting part of the blocks and the asymmetry of the circuit.
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Date submitted2019-02-01
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Date accepted2019-09-16
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Date published2020-02-25
Priority parameters of physical processes in a rock mass when determining the safety of radioactive waste disposal
- Authors:
- V. S. Gupalo
Consideration of geodynamic, hydrogeochemical, erosion and other quantitative characteristics describing evolutionary processes in a rock mass is carried out when choosing a geological formation for the disposal of radioactive waste. However, the role of various process parameters is not equal for safety ensuring and additional percentages of measurement accuracy are far from always being of fundamental importance. This makes it necessary to identify various types of indicators of the geological environment that determine the safety of radioactive waste disposal for their detailed study in the conditions of the burial site. An approach is proposed to determine the priority indicators of physical processes in the rock mass that determine the safety of disposal of various types of radio active waste and require increased attention (accuracy, frequency of measurements) when determining in - situ conditions. To identify such factors, we used the sensitivity analysis method that is a system change in the limits of variable values during securty modeling in order to assess their impact on the final result and determine the role of various physical processes in ensuring safety.
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Date submitted2020-01-09
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Date accepted2020-01-17
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Date published2020-02-25
Methodology for Calculating the Stability of the Polymer Operating String in Permafrost
- Authors:
- V. A. Stetukha
- I. I. Zheleznyak
The goal of this paper is to develop a methodology for calculating the stability of an annular cross-section string casing made of polymer material used for the development of mineral deposits by underground leaching in permafrost formations. The aim was to determine the geometric parameters of the casing and to ensure its operational reliability. The relevance of the research is associated with the peculiarities of external influences on the string, for example, a geotechnological well operating in permafrost formation under conditions of additional exposure to ice pressure during freezing of water in the borehole annulus. This effect is usually accompanied by deformation of the casing due to ice pressure, which can lead to string collapse, abnormal operation and the risk of contamination of the geological environment. The proposed calculation method for a polymer casing is based on simulation of objects using the finite element method. We used the spatial finite elements to model the interaction of key elements of the geotechnological natural-technogenic complex: a polymer casing, ice in the annulus space and homogeneous or heterogeneous rock masses adjacent to the well. The results of the study are presented in the form of tables and patterns of displacements, which reflect stresses and strains in the elements of the calculation scheme. The analysis of the obtained results confirms the possibility of using polymer casings of different technological purposes in various conditions of permafrost formation, including extreme ones. The results of the redistribution of pressure created by ice during the freezing of water in the borehole annulus to the rock mass and the string are evaluated. Interdependent deformations of the rock mass and operating string during freezing of water in the borehole annulus are determined. The necessity of considering the properties of the rock mass in determining the pressure on the string is established. The conditions for the collapse of the string with a different combination of its parameters are revealed.
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Date submitted2019-05-07
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Date accepted2019-07-13
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Date published2019-10-23
Improving the Energy Efficiency of the Electromechanical Transmission of an Open-pit Dump Truck
- Authors:
- A. E. Kozyaruk
- A. M. Kamyshyan
The article analyzes the existing systems of electromechanical transmission of mining trucks BelAZ. The influence of the load nature created by the uncontrolled rectifier on the power factor and mass-dimensional indicators of the electromechanical transmission isassessed. Variants of modernization of the AC-electromechanical transmission system are proposed, which provide power factor correction. The influence of the proposed options on the overall dimensions of the electromechanical transmission is considered. Based on the assessment, a modernization option was chosen that provides the required power factor with minimal impact on the overall dimensions of the electromechanical transmission. The results of modeling the operation of the existing electromechanical transmission and the modernized electromechanical transmission system using the most promising modernization option are presented.
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Date submitted2019-04-30
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Date accepted2019-07-16
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Date published2019-10-23
Salt Rock Deformation under Bulk Multiple-Stage Loading
- Authors:
- I. L. Pankov
- I. A. Morozov
The paper presents experimental justification of the possibility to use bulk multiple-stage loading to study the process of salt rock deformation in the laboratory conditions. Results of comparative tests between bulk multiple- stage and single-stage loading of salt rock samples are demonstrated. The paper contains results of research on the rate of lateral pressure and its impact on strength limit and residual strength limit of sylvinite, estimated using single- stage and multiple-stage methods. Research results demonstrate how the rate of lateral pressure impacts dilatancy boundary of salt rocks. Analysis of how the loading method influences certificate parameters of Mohr-Coulomb strength of sylvinite has been carried out. The dynamics of elastic modulus in the process of salt rock deformation is analyzed depending on the rate of lateralpressure. It is demonstrated how the method of multiple-stage loading adequately reflects the processes of salt rock de- formation and decomposition, and facilitates not only lowering impact of sample’s inner structure heterogeneities on the experimental results, but also significant reduction in the required amount of rock material.
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Date submitted2019-01-11
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Date accepted2019-03-17
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Date published2019-06-25
Improving methods of frozen wall state prediction for mine shafts under construction using distributed temperature measurements in test wells
- Authors:
- L. Yu. Levin
- M. A. Semin
- O. S. Parshakov
Development of mineral deposits under complex geological and hydrogeological conditions is often associated with the need to utilize specific approaches to mine shaft construction. The most reliable and universally applicable method of shaft sinking is artificial rock freezing – creation of a frozen wall around the designed mine shaft. Protected by this artificial construction, further mining operations take place. Notably, mining operations are permitted only after a closed-loop frozen section of specified thickness is formed. Beside that, on-line monitoring over the state of frozen rock mass must be organized. The practice of mine construction under complex hydrogeological conditions by means of artificial freezing demonstrates that modern technologies of point-by-point and distributed temperature measurements in test wells do not detect actual frozen wall parameters. Neither do current theoretical models and calculation methods of rock mass thermal behavior under artificial freezing provide an adequate forecast of frozen wall characteristics, if the input data has poor accuracy. The study proposes a monitoring system, which combines test measurements and theoretical calculations of frozen wall parameters. This approach allows to compare experimentally obtained and theoretically calculated rock mass temperatures in test wells and to assess the difference. Basing on this temperature difference, parameters of the mathematical model get adjusted by stating an inverse Stefan problem, its regularization and subsequent numerical solution.
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Date submitted2018-10-27
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Date accepted2019-01-04
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Date published2019-04-23
Application of an active rectifier used to mitigate currents distortion in 6-10 kV distribution grids
The paper addresses issues of using the active rectifier in partially loaded variable frequency drive as active filter in the conditions of non-sinusoidal current and voltage disturbances caused by the presence of high-power non-linear load in the grid. The topology of transformless three-level converter for 6-10 kV suitable for proposed solution has been presented and its mathematical model has been de-rived. Based on the model, the direct power control algorithm with ability to compensate non-linear currents has been designed. The investigation of active rectifier efficiency was performed depending on the relation between linear and non-linear load currents of the grid node, as well as on active power load of the active rectifier. Efficiency analysis was based on the developed computer model of the grid node with connected non-linear load simultaneously with the variable frequency drive with active rectifier.
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Date submitted2018-09-04
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Date accepted2018-11-18
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Date published2019-02-22
Operation experience of centrifugal single-stage pumps in «ALROSA» Joint Stock Company
- Authors:
- N. P. Ovchinnikov
When mining diamond-bearing raw materials and further extracting diamonds from it in the joint-stock company ALROSA, which is a city-forming enterprise in the north-east of the Russian Federation, various pumping equipment is used, in particular, centrifugal single-stage pumps. In the present work, it is noted that the least reliable in terms of absence of failures of centrifugal single-stage pumps used in the joint-stock company ALROSA are the impellers, seals and bearing assemblies. Using linear correlation and regression analysis, it was found that the durability of the seals and bearing assemblies of the investigated pumps largely depends on the durability of their impellers. In the course of research, it was found that unbalancing the pump rotor due to excessive hydroabrasive wear of the impeller also leads to deformation and fracture of the shaft. In general, residual deformations and destructions are characteristic of the shafts of domestic pulp pumps of GrAT, GrT and Gr types. The most loaded sections of shafts of centrifugal single-stage pumps are installed. The most effective from the point of view of application among the pulp (ground, slurry and sand) pumps are pulp pumps of the Finnish company «Metso». When working on highly mineralized water (brines), the «X» type pumps have proven to be the best among centrifugal single-stage pumps.
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Date submitted2016-08-30
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Date accepted2016-10-30
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Date published2017-02-22
Gas-dynamic processes affecting coal mine radon hazard
- Authors:
- V. I. Efimov
- A. B. Zhabin
- G. V. Stas
The paper focuses on vertical migration of radon in surrounding rocks described by Fick's first law as well as by the continuity equation for diffusion flow, with allowance for sorption and radioactive decay processes. Taking into account special characteristics of vertical radon diffusion, the process can be considered stable. It is demonstrated that for productive areas it is feasible to consider one-dimensional convective diffusion, as diffusive transport of radon by the air of productive areas occurs at steady-state conditions. Normally the factor of radon emissions prevails if atmospheric pressure is constant. Amount of air, calculated using this factor, by 20-30 % exceeds the one needed to dilute carbon dioxide to maximum allowed concentration (MAC).
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Date submitted2015-12-10
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Date accepted2016-02-16
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Date published2016-12-23
Research into the innovative potential of an oil and gas company at different stages of field development
- Authors:
- A. E. Cherepovitsyn
- A. Kraslavski
The paper presents an overview of research into the methods and principles used to assess the innovative potential of an oil and gas company. The validation is provided for the conceptual framework of the innovative potential, which is characterized by a combination of resources having a specific value for the oil and gas sector. The paper gives a detailed overview of the resources, which determine the innovative potential of the oil and gas company. A system of indicators for assessing the innovative potential of the oil and gas company, including six indicator groups, has been proposed. Key distinctive features of the oil and gas company technological development have been determined based on the use of potential for innovation at different stages of the field development. Technical and economic indicators of the oil field development at different stages are described. A concept of Intelligent Field technology is outlined, representing an innovative system, implementation of which determines a level to which the potential for innovation of the oil and gas company is tapped.
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Date submitted2015-08-12
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Date accepted2015-10-05
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Date published2016-04-22
Energy efficient electromechanical systems of mining andtransport machines
- Authors:
- A. E. Kozyaruk
The problems of selecting the type and the structure of mining and transport machines elec-tromechanical control system, providing energy efficiency and performance. The conclusion about the most admissibility of variable frequency drives with induction motors and power semiconduc-tor converters was made. The methods and technical means of improving the energy efficiency of asynchronous electric motors due to the choice of increased power characteristics motors, design of special motor control algorithms and applying of semiconductor converters with active rectifi-ers, providing high power factor and improving of the electricity supply quality were reviewed. To improve the operational characteristics prompted use of diagnostic systems and residual life as-sessment of electrical equipment. Implementation of designs tied to the excavator-transport sector. The schemes of the excavator power drive, mining truck and implemented complex picture at coal mine are shown.