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Date submitted2021-05-08
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Date accepted2022-07-21
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Date published2023-12-25
Technologies of intensive development of potash seams by longwall faces at great depths: current problems, areas of improvement
- Authors:
- Vladimir P. Zubov
- Denis G. Sokol
The results of the analysis of practical experience in the development of potash seams using longwall mining systems at the mines of OAO “Belaruskali” are presented. Positive changes in the technical and economic indicators of mines and an increase in the safety of mining operations were noted with the introduction of resource-saving technologies without leaving the pillars between the excavation columns or with leaving the pillars between the columns with dimensions at which they are destroyed by mining pressure in the goaf. It is noted that the use of mechanized stoping complexes characterized by high energy capacity, combined with large depths of development, is the main reason for the temperature increase in longwalls to values exceeding the maximum permissible air temperature regulated by sanitary standards. Based on production studies, it was concluded that the temperature regime along the length of the longwall face is determined by the temperature of rocks in the developed longwall space, heat emissions from the equipment of the power train, and the temperature of the rock mass ahead of the longwall. The conclusion has been drawn about the feasibility of using developed technological schemes in deep mining conditions, which provide a reduction in longwall temperature by 6-9 °C or more through isolated ventilation of longwall and power trains, as well as heat exchange between the airflow entering the longwall and the rocks in the developed space.
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Date submitted2021-10-14
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Date accepted2022-01-24
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Date published2022-04-29
Monitoring of compressed air losses in branched air flow networks of mining enterprises
Compressed air as a type of safe technological energy carrier is widely used in many industries. In economically developed countries energy costs for the production and distribution of compressed air reach 10 % of the total energy costs. The analysis of compressed air production and distribution systems in the industrial sector shows that the efficiency of the systems is at a relatively low level. This is due to the fact that insufficient attention is paid to these systems since the compressed air systems energy monitoring has certain difficulties – the presence of complex and branched air pipeline networks with unique characteristics; low sensitivity of the equipment which consumes compressed air; the complexity of auditing pneumatic equipment that is in constant operation. The article analyzes the options for reducing the cost of production and compressed air distribution. One of the promising ways to reduce the compressed air distribution cost is timely detection and elimination of leaks that occur in the external air supply network of the enterprise. The task is solved by hardware-software monitoring of compressed air pressure at key points in the network. The proposed method allows real-time detecting of emerging air leaks in the air duct network and sending commands to maintenance personnel for their timely localization. This technique was tested in the industrial conditions of ALROSA enterprises on the air pipeline network of the Mir mine of the Mirninsky Mining and Processing Plant and showed satisfactory convergence of the calculated leakage values with the actual ones. The practical significance of the obtained results is that the developed method for monitoring air leaks in the air duct network is simple, it requires an uncomplicated software implementation and allows to localize leaks in a timely manner, thereby reducing unproductive energy costs at the enterprises.
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Date submitted2020-12-16
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Date accepted2021-07-27
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Date published2021-10-21
Features of the thermal regime formation in the downcast shafts in the cold period of the year
In the cold period of the year, to ensure the required thermal regime in underground mine workings, the air supplied to the mine is heated using air handling systems. In future, the thermodynamic state of the prepared air flow when it is lowered along the mine shaft changes due to the influence of a number of factors. At the same time, the processes of heat and mass exchange between the incoming air and its environment are of particular interest. These processes directly depend on the initial parameters of the heated air, the downcast shaft depth and the presence of water flows into the mine shaft. Based on the obtained experimental data and theoretical studies, the analysis of the influence of various heat and mass transfer factors on the formation of microclimatic parameters of air in the downcast shafts of the Norilsk industrial district mines is carried out. It is shown that in the presence of external water flows from the flooded rocks behind the shaft lining, the microclimatic parameters of the air in the shaft are determined by the heat transfer from the incoming air flow to the underground water flowing down the downcast shaft lining. The research results made it possible to describe and explain the effect of lowering the air temperature entering the underground workings of deep mines
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Date submitted2020-10-26
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Date accepted2021-07-28
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Date published2021-10-21
Investigation of the influence of the geodynamic position of coal-bearing dumps on their endogenous fire hazard
The paper investigates the hypothesis according to which one of the factors influencing the spontaneous combustion of coal-bearing dumps is its geodynamic position, i.e. its location in the geodynamically dangerous zone (GDZ) at the boundary of the Earth crust blocks. This hypothesis is put forward on the basis of scientific ideas about the block structure of the Earth crust and the available statistical data on the location of burning dumps and is studied using computer modeling. A dump located in the area of Eastern Donbass was chosen as the object of research. The simulation results show that the penetration of air into the dump body from the mine through the GDZ, which crosses the mining zone, is possible at an excess pressure of 1000 Pa created by the main ventilation fans. The fire source appearance in the dump body causes an increase in the temperature of the dump mass and becomes a kind of trigger that "turns on" the aerodynamic connection between the dump and the environment, carried out through the GDZ. It is concluded that the establishment of an aerodynamic connection between the mine workings and the dump through the GDZ can be an important factor contributing to the endogenous fire hazard of coal-bearing dumps. The simulation results can be used in the development of projects for monitoring coal-bearing dumps and measures to combat their spontaneous combustion.
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Date submitted2019-06-29
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Date accepted2019-08-25
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Date published2019-12-24
New technical solutions for ventilation in deep quarries
- Authors:
- S. G. Shakhrai
- G. S. Kurchin
- A. G. Sorokin
The paper discusses the issues of ventilating in deep quarries caused by the intensification of blasting operations at great depths, the increased distance of ore truck transportation to the daylight area, constant change in the geometrical parameters of the quarry, its microrelief and direction of mining, and increased isolation of the mined space from the environment. We provide a brief analysis of the current tools for forced airflow in deep quarries, which showed that the use of forced ventilation is often challenging since it leads to high energy consumption, high level of noise exceeding the permissible parameters, and high speeds of forced air flows may blow the dust off the quarry surfaces. The article presents methods and tools developed at the Siberian Federal University for intensifying the natural airflow in deep quarries by changing the air density at the entrance and exit points of the pit, as well as heating the shady areas using mirrors and solar energy, which do not interfere with mining and blasting operations.
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Date submitted2019-01-03
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Date accepted2019-03-23
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Date published2019-06-25
Normalization of thermal mode of extended blind workings operating at high temperatures based on mobile mine air conditioners
Thermal working conditions in the deep mines of Donbass are the main deterrent to the development of coal mining in the region. Mining is carried out at the lower technical boundaries at a depth of almost 1,400 m with a temperature of rocks of 47.5-50.0 °C. The air temperature in the working faces significantly exceeds the permissible safety standards. The most severe climatic conditions are formed in the faces of blind development workings, where the air temperature is 38-42 °С. It is due to the adopted coal seam mining systems, the large remoteness of the working faces from the main air supply openings, the difficulty in providing blind workings with a calculated amount of air due to the lack of local ventilation fans of the required range. To ensure thermodynamic safety mine n.a. A.F.Zasyadko we accepted the development of a draft of a central cooling system with ground-based absorption refrigerating machines with a total capacity of 9 MW with the implementation of the three types of generation principle (generation of refrigeration, electrical and thermal energy). However, the long terms of design and construction and installation work necessitated the use of mobile air conditioners in blind development faces. The use of such air conditioners does not require significant capital expenditures, and the terms of their commissioning do not exceed several weeks. The use of a mobile air conditioner of the KPSh type with a cooling capacity of 130 kW made it possible to completely normalize the thermal working conditions at the bottom of the blind workings 2200 m long, carried out at a depth of 1220-1377 m at a temperature of host rocks 43.4-47.5 °С. It became possible due to the closest placement of the air conditioner to the face in combination with the use of a high-pressure local ventilation fan and ducts, which ensured the air flow produced by the calculated amount of air. The use of the air conditioner did not allow to fully normalize the thermal conditions along the entire length of the blind face but reduced the urgency of the problem of normalizing the thermal regime and ensured the commissioning of the clearing face.
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Date submitted2017-09-10
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Date accepted2017-11-10
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Date published2018-02-22
Research of heat generation indicators of gas engines
- Authors:
- O. N. Didmanidze
- A. S. Afanasev
- R. T. Khakimov
A comprehensive strategy for reviving the production of mining industry equipment and ensuring its competitiveness includes the wide use of gas engines for various purposes. Experimental studies of the working cycle of a gas engine are one of the main tasks in determining the heat generation characteristics. To this end, indicator charts were recorded in various modes, which were subjected to analysis in order to determine the key parameters characterizing intra-cylinder processes. According to the experimental program, the maximum cycle pressure, the rate of pressure build-up, the heat generation characteristic, the first heat generation phase, the duration of the second combustion phase, and the effect of the ignition advance angle for the ignition period were determined. The results of an experimental study of the influence of gas engine working process with allowance for the change in the ignition advance angle for the ignition period are described and the parameters of the maximum cycle pressure, the rate of pressure build-up, and the heat generation characteristics are determined. In the processing of data, integral charts are constructed, the working cycle parameters are calculated, and the dynamics of the engine heat generation is determined.
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Date submitted2016-11-07
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Date accepted2016-12-27
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Date published2017-04-14
Method of determining characteristics for air heating system in railway tunnels in harsh climatic conditions
- Authors:
- S. G. Gendler
- S. V. Sinyavina
The article describes climatic and mining-technical conditions influencing frost formation process. It was noted that the radical tools for preventing frost formation in winter periods is creation of positive temperature in tunnels by heating the incoming outside air. We formulated tasks, which solution will promote development of engineering calculation method for heating systems parameters. The article provides results of theoretical studies based on mathematical modelling and analytical solutions and data on field instrumental measurements, which were processed with similarity criteria. It compares mathematical modelling results on determining amount of tunnel incoming air flow with portal gates and calculations data from experimentally determined coefficient of local resistance. We proved the energy efficiency of placing the tunnel portal gates and validated the places of preheated air injection points and removal of cool air from this flow, which provides maximal energy effect.
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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 submitted2015-08-17
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Date accepted2015-10-25
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Date published2016-04-22
Ecological aspects of vehicle tunnels ventilation in the conditions of megalopolises
- Authors:
- S. G. Gendler
The characteristic of Russia and foreign vehicle tunnels are provided in paper and advantages of their placement in the conditions of the city are noted. It is shown that one of the main factors defining negative impact on environment in the period of tunnels driving is mine equipment, and at operation – vehicles. The analysis of essential differences of features of pollution of atmospheric air at construction of tunnels from its pollution at construction of buildings on a surface is given. The examples illustrating levels of negative impact of the upcast ventilation shaft airflow on atmospheric air are given and the ventilation schemes reducing this influence are offered. It is shown that during operation of road tunnels of pollution of the air environment can extend on considerable distances from tunnel portals. Numerical calculations of concentration of carbon oxides and nitrogen during removal of the upcast ventilation shaft airflow through portals and through the mines built near them are executed. Technical solutions on purifications of tunnel air by means of electrostatic filters are described.
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Date submitted2014-11-05
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Date accepted2015-01-24
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Date published2015-10-26
Use of geoinformation technologies for otpimized distribution of stations of atmospheric air quality monitoring
- Authors:
- M. V. Volkodaeva
The article deals with possible applications of modern geographic information systems for optimized distribution of stations of atmospheric air quality monitoring. Due to the fact that estimation of atmospheric pollutant concentrations is a reason for decisions to improve air quality, costly measures to protect the atmosphere and monitoring effectiveness of these actions, atmospheric air quality indicators, and therefore the proper distribution of monitoring stations, are of great importance. Results of model calculations of atmospheric air pollution, which have been recently developed in our country, in combination with GIS solutions, should be used for optimized distribution of stations of atmospheric air quality monitoring. One of the major factors of objective estimation of urban atmospheric air quality is proper reference of industrial and transport pollutant emission sources to the city’s topographic base (both in citywide and local coordinate systems), as well as distribution of stations of atmospheric air quality monitoring and selection of high-priority pollutants for a particular city district. Some recommendations for monitoring stations distribution and pollutants selection based on the GIS analysis of spatial distribution of maximum ground level concentrations of pollutants are given.