-
Date submitted2024-06-17
-
Date accepted2024-07-17
-
Date published2024-10-03
Justification on the safe exploitation of closed coal warehouse by gas factor
The annual increase of coal production and its demand lead to the necessity in temporary storage places (warehouses) organization to accommodate raw coal materials before the shipment. It is noted that at the open method of coal storing the dust emission from loading/unloading operations and from the pile surface effects negatively the health of the warehouse workers and adjacent territories. An alternative solution is closed-type warehouses . One of the main hazards of such coal storage can be the release of residual methane from coal segregates into the air after degassing processes during mining and extraction to the surface, as well as transportation to the place of temporary storage. The study carries the analysis of methane content change in coal during the processes of extraction, transportation and storage. Physical and chemical bases of mass transfer during the interaction between gas-saturated coal mass and air are studied. It is determined that the intensity of methane emission depends on: the coal seam natural gas content, parameters of mass transfer between coal, and air and the ambient temperature. The dynamics of coal mass gas exchange with atmospheric air is evaluated by approximate approach, which is based on two interrelated iterations. The first one considers the formation of methane concentration fields in the air space of the bulk volume and the second accounts the methane emission from the pile surface to the outside air. It is determined that safety of closed coal warehouses exploitation by gas factor can be ensured by means of artificial ventilation providing volumetric methane concentration in the air less than 1 %. The flow rate sufficient to achieve this methane concentration was obtained as a result of computer modeling of methane concentration fields formation in the air medium at theoretically calculated methane emission from the pile surface.
-
Date submitted2022-03-17
-
Date accepted2022-06-20
-
Date published2022-11-03
Assessment of collecting activity of physically sorbed reagents on the example of easily floatable coking coal sludge
- Authors:
- Sergey A. Kondratev
- Tatyana A. Khamzina
The article presents one of the new approaches to theoretical assessment of collecting ability of reagents. The efficiency of reagents-collectors with different chemical composition used for flotation of coking coals was studied. A comparative assessment of the flotation activity of kerosene, mineral oil, thermal gas oil, KETGOL and FLOTEK is given. The criteria of collecting activity of the above reagents-collectors for coal sludge flotation were specified. A correlation was established between the indicators of coal sludge flotation by the above reagents and their physical parameters. It is shown that the rate of spreading over water surface can characterize the flotation activity of reagents. Based on dependence of the collecting activity of a reagent on its rate of spreading along the “gas – liquid” interface and surface pressure, the main approaches to determining the structure and composition of molecules of an effective flotation collector can be determined. A new concept of the function performed by a physically sorbed collector in the elementary act of flotation and a criterion for the flotation activity of reagents used in coal sludge beneficiation are proposed. It is shown that the collector used in coal flotation, in addition to hydrophobizing the surface of the extracted particles, should reduce the induction time and remove the kinetic constraint on formation of a flotation aggregate.
-
Date submitted2022-04-29
-
Date accepted2022-07-21
-
Date published2022-11-10
Deep structure, tectonics and geodynamics of the Sea of Okhotsk region and structures of its folded frame
The use of the zonal-block model of the earth's crust for the construction of regional tectonic schemes and sections of the earth's crust based on a complex of geological and geophysical data makes it possible to consider the resulting maps and sections as tectonic models. The main elements of such models are blocks with an ancient continental base and interblock zones formed by complexes of island arcs, an accretionary prism, or oceanic crust. The developed geotectonic model of the Sea of Okhotsk region reflects the features of the deep structure, tectonics, and geodynamics. The Cimmerian Novosibirsk-Chukotka, Verkhoyansk-Kolyma, Kolyma-Omolon, and Amur folded regions and the Alpides of the Koryak-Kamchatka and Sakhalin-Sikhote-Alin folded regions are developed along the northern, western, and southern boundaries of the Sea of Okhotsk megablock with a continental crust type. From the east, the megablock is limited by oceanic basins and island arcs.
-
Date submitted2016-09-02
-
Date accepted2016-11-08
-
Date published2017-02-22
Mathematical models of gas-dynamic and thermophysical processes in underground coal mining at different stages of mine development
- Authors:
- M. V. Gryazev
- N. M. Kachurin
- S. A. Vorobev
New trends have been traced and the existing ones refined regarding filtration and diffusive motion of gases in coal beds and surrounding rock, spontaneous heating of coal and transport of gas traces by ventilation currents in operating coal mines. Mathematical models of gas-dynamic and thermophysical processes inside underworked territories after mine abandonment have been justified. Mathematical models are given for feasible air feeding of production and development areas, as well as for the development of geotechnical solutions to ensure gas-dynamic safety at every stage of coal mine operation. It is demonstrated that the use of high-performance equipment in the production and development areas requires more precise filtration equations used when assessing coal mine methane hazard. A mathematical model of pressure field of non-associated methane in the edge area of the coal seam has been justified. The model is based on one-dimensional hyperbolic equation and takes into consideration final rate of pressure distribution in the seam. Trends in gas exchange between mined-out spaces of high methane- and CO 2 -concentration mines with the earth surface have been refined in order to ensure environmental safety of underworked territories.
-
Date submitted2015-07-11
-
Date accepted2015-09-17
-
Date published2016-02-24
The mechanism of rock burst leading to ground destruction of mine openings
- Authors:
- M. G. Mustafin
The article deals with the main issues of studying of one type of rock bursts which lead to gound destruction of coal mine openings. The research is focused on rock burst prediction. Some cases of rock bursts are analised. The paper points out factors affecting this kind of rock failure. It also presents some simulation models and numerical examples. The results of the research show that it is possible to plan safe mining operations under different mining and geological conditions.
-
Date submitted2014-12-28
-
Date accepted2015-02-21
-
Date published2015-12-25
Modeling of rock massif geomechanical state at gas extraction from coal seams
- Authors:
- M. G. Mustafin
The article describes the method of modeling a coal seam stress-strain state and an enclosing rock massif when degasified. An approach to defining the model input parameters, calculated with the porosity and gas pore pressure coefficient, was shown. The importance of preliminary calculations, indicating possible coal seam shrinkage and surface subsidence was underlined. It shows formation mechanism for coal seam zones with elevated gas pressure, where gas recovery is efficient.
-
Date submitted2014-11-01
-
Date accepted2015-01-18
-
Date published2015-10-26
On the design features of underground multiple gassy coal seam mining
- Authors:
- O. I. Kazanin
The analysis of the industry regulatory requirements and the world design experience of underground multiple coal seam mining is provided. The main problems of intensive longwall mining of multiple flat gassy coal seams as well as methods for determination of high rock pressure zone parameters and seams interaction are considered. The examples of a number of mines in the Kuzbass and Pechora coal basins show that the design of multiple seam mining and the choice of longwall panel parameters were often made without taking into consideration influence of surrounded seams that leads to essential complication of conditions for mining operations and decreases the technical and economic indicators of mining. The existing industry regulations do not allow considering complex influence of factors in multiple coal seams mining fully. On the basis of field, laboratory, and numeric research results it is noted that recommendations for pillar positioning in contiguous seams ensuring efficiency and safety of multiple seam longwall mining can significantly differ in case of liability of coal seams to spontaneous combustion, high natural gas content, influence of multiple seam mining onto daily surface, and difficult conditions of entries maintenance. The importance of having information on the stress-strain condition of the rock mass at a design stage and its changes in the process of multiple seam mining is shown. The need for industry regulations updating for the purpose of a more detailed definition of a form, size and a location of high rock pressure zones as well as stress parameters in these zones is noted. A set of recommendations for effective and safe multiple seam mining is developed.
-
Date submitted2014-07-12
-
Date accepted2014-08-24
-
Date published2014-12-22
The study of structural features of outburst coal seams
- Authors:
- V. N. Zakharov
- O. N. Malinnikova
A study of the structural features of outburst-dangerous and non-outburst dangerous coal layers was conducted. It was shown that coal taken from a sudden outburst zone has a significantly greater sorption surface than coal from the same layer which was not part of the sudden outburst. The size of the sorption surface of coal is affected by its history up to that point; thus the heating of the coal sample during its preparation enlarges its sorption surface. An electron microscope study of coal surfaces has shown that for coal from outburst-dangerous layers, a disturbed structure with a large quantity of fissures and partings the size of 1 micrometer is typical. Under the same enlargement, a coal structure from safe coal layers is much more uniform. The study of digital images of coal surfaces, taken with the help of an electron microscope, shows that the structural institution of surface elements may be presented by multifractal analysis, with its spectrum of fractal dimensions, which allows us to state quantitative distinctions in coal microstructures for outburst-dangerous layers. Coal from outburst-dangerous layers has a greater set of structural elements, and therefore a spectrum of fractal dimensions that is 1.5-2 times wider than for nonoutburst dangerous layers.
-
Date submitted2010-07-23
-
Date accepted2010-09-28
-
Date published2011-03-21
Sistaining mining in whole different rigidity
- Authors:
- L. K. Gorshkov
- S. G. Kokoev
Studies conducted in the mines «Rostovugol», showed that, for assessing the sustainability of preparatory excavations in the management of sewage treatment works is enough to determine the allowable values of convergence of the roof and ground-level workings and potential energy of elastic deformation of the pillars. These indicators can be used in the coal mines of other basins.
-
Date submitted2009-08-28
-
Date accepted2009-10-04
-
Date published2010-02-01
The integrated reloading point at the combined auto-railway transportation
- Authors:
- M. M. Yakubovskii
- G. A. Kholodniakov
In article it is considered the technology of creation and exploitation of reloading ore warehouse. As the reloading equipment it is offered to use a hydraulic backhoe excavator. At the combined transport the warehouse is an irreplaceable link in a technological chain. Basic difference from existing schemes of warehousing is that ore is housed not in a stack but in a concentration trench. The concentration trench is formed in immediate proximity from a face. It allows to prolong the operation term of the warehouse and to exclude rigid interdependence of the combined transport links.
-
Date submitted2009-07-24
-
Date accepted2009-09-19
-
Date published2010-04-22
Efficient assessment of stress state of coal seams liable to rock bursts
- Authors:
- F. P. Ivchenko
- N. V. Krotov
The article deals with the method for effective evaluation of stress state and rock burst hazard of sections of coal seams by the predicted output of drilling fines. The suggested engineer solution, i.e. the program modulus «Prediction» allows to represent the formation of the support pressure zone in the marginal part of the seam (or in a mine working) and to control the potential pattern of rock burst hazard manifestation in a mine working under various geological and mining conditions.
-
Date submitted2008-10-25
-
Date accepted2008-12-02
-
Date published2009-12-11
Composition of retrospective geological systems and significance of structural-tectonic factor in paleogeographic reconstructions
- Authors:
- V. P. Matveev
Models of geological objects are represented as the static, dynamic and retrospective systems. Paleogeographic reconstruction relates to a typical retrospective system. Its objective composition becomes possible on the basis of the lower rank systems: static and dynamic. Comparison between paleogeographic reconstructions in time shows the significance of tectonical factor in the forming of paleolandscape of the territory. Information on paleobiocoenosis is necessary for estimation of paleoclimate. The Author’s field investigation materials of the geological mapping on a scale of 1:200 000 at the Novaya Zemlya archipelago are taken as the basis of paleogeographic and paleofacies reconstructions.
-
Date submitted2008-10-22
-
Date accepted2008-12-14
-
Date published2009-12-11
Peculiarities of structure and comparative analysis of oil-and-gas basins in the Pacific segment of lithosphere
- Authors:
- V. B. Archegov
Comparative analysis was carried out for oil-and-gas-bearing basins of young and oldland platforms of the Pacific segment. Previously the same kind of analysis had been realized for the Atlantic segment of lithosphere. Obtained results confirm the unique geological structure and oil-and-gas capacity of Siberian platform, by these features it differs from all other cratons in the whole world.