Innovative Techniques in Underground Mining for the Prevention of Gas Dynamic Phenomena

In the last decades, rigorous research has been carried out with the end of understanding the gas dynamic phenomenon and although different preventive techniques have been employed, even today there are numerous accidents even with the loss of life. This work analyses an alternative and innovative method of fracturing and degassing coal, by generating CO2 with a pyrotechnic device called PYROC (Pyrotechnic Break Cartridges). Medium-scale tests of generation of CO2 into coal samples are carried out and their effect is analysed comparing the initial and final permeabilities of the coal samples once the generation of CO2 has finished. These permeabilities are calculated by injecting methane. Besides, the influence of different parameters as the length of the boreholes, the pressure of the gas or the initial permeability of the coal have been analysed with a numerical simulation of one face of one of the sublevels of a mine. The results show that the method increases the safety in mining operations because it fractures and degasses the coal, increases the permeability of the coal in the borehole of injection from 9.5 mD to 31 mD, decreases the methane gas pressure below pre-detonation levels for 1 min, achieves decompressed lengths between 8 and 10 m ahead of the face with pressures of injection of 50 MPa, relaxes the total length of the borehole for initial coal permeability values equal to or greater than 0.002 mD, and allows to work with low permeable coals with high induced stresses and high methane concentrations.

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Unitized Attachment Points of a Disk Tool for the Working Bodies of Shearers and Tunnelling Machines

MATEC Web of Conferences ◽

10.1051/matecconf/201929703008 ◽

2019 ◽

Vol 297 ◽

pp. 03008

Author(s):

Alexey Khoreshok ◽

Leonid Mametyev ◽

Valery Nesterov ◽

Aleksandre Tsekhin ◽

Andrey Borisov

Keyword(s):

Underground Mining ◽

Design Development ◽

Mining Operations ◽

Disk Tool ◽

Geological Conditions ◽

The Face ◽

Scientific Task ◽

Working Bodies ◽

Technical Solutions

An important task in the technological process of a mining enterprise is preparatory mine working performance, as effective operation of an entire mining complex depends on rate and quality of drilling. Therefore, the main factor affecting the performance of the process of underground mining is the correspondence of design and operating parameters of the working bodies of tunnelling machines to mining and geological conditions. The underground mining operations showed that rocks with a strength f ≤ 10 and high abrasiveness are to be destroyed with disc tools, providing higher strength, wear-resistant parameter and low dust formation in comparison with cutters. The usage of disk tools on the working bodies of tunnelling machines of selective action is a poorly studied task and requires special research of the questions of destruction, crushing and loading of rocks at reverse working modes. It has been established that researches aimed at design development of an attachment point of a disk tool for arrow-type working bodies of a tunnelling machines is an urgent scientific task. The original technical solutions for the design of the attachment points of disc and cutter tools are proposed to improve the processes of cutting of working bodies in the face massif, dust suppression, sealing and mounting-dismounting operations at the operation of shearers and tunnelling machines.

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REGULARITIES OF CHANGES IN THE GAS-DYNAMIC AND GEOMECHANICAL SITUATION AT POTASH MINES

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2021-13-3-426-432 ◽

2021 ◽

Vol 13 (3) ◽

pp. 426-432

Author(s):

Alexander ZEMSKOV ◽

◽

Maria LISKOVA ◽

Guzel SHARIPZYANOVA ◽

◽

...

Keyword(s):

Barometric Pressure ◽

Gas Content ◽

Mining Operations ◽

Gas Emissions ◽

Gas Dynamic ◽

Natural Factors ◽

Labor Safety ◽

Available Information ◽

Dynamic Phenomena ◽

Safe Working

Mining operations in potash and salt deposits are complicated by gas emissions and gas dynamic phenomena. The analysis of a large number of gas dynamic phenomena and intense gas emissions at potash mines in Russia and Belarus allowed the authors to identify some patterns. In particular, it was found that the maximum number of gas dynamic phenomena occurs in the 7–10 year of operation of the mines. The purpose of the study is to analyze and identify available information on the influence of heliophysical and manmade factors on the state of rock massifs, which will allow purposefully predicting and preventing the manifestations of these factors, increasing labor safety and efficiency of mining enterprises. Research methods: methods of a full-scale mine experiment to determine the gas content of rocks and the gas content of workings, as well as analysis of statistical data. The results of the study showed that the analysis of data on 84 cases of gas dynamic phenomena at the mines of PJSC Uralkali revealed an increase in the volume of gas emissions from the developed lavas spaces at the mines of JSC Belaruskali as a result of a drop in barometric pressure on the surface. In conclusion, it can be noted that the combination of natural factors together with a powerful man-made impact on the environment creates certain prerequisites for disasters of various scales, ranging from destructive earthquakes to subsidence of mountain pressure, gas dynamic phenomena and intense gas emissions in mines and mines. The set of established patterns formed the basis for the development of a number of preventive measures that increase the safe working conditions of miners and the efficiency of mining enterprises.

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Investigation of features of shock wave distribution in the rock massif at gas dynamic phenomena

Geo-Technical mechanics ◽

10.15407/geotm2020.152.234 ◽

2020 ◽

pp. 234-243

Author(s):

S.I. Skipochka ◽

◽

T.A. Palamarchuk ◽

L.V. Prokhorets ◽

V.P. Kurinnyi ◽

...

Keyword(s):

Shock Wave ◽

Wave Propagation ◽

Shock Waves ◽

Shock Wave Propagation ◽

Rock Massif ◽

Mining Operations ◽

Technological Factors ◽

Gas Dynamic ◽

Methane Mixture ◽

Dynamic Phenomena

When studying risk factors in coal mines, it is necessary, in the first place, to consider factors and properties of the rock massif occurred with the deepening of mining operations in the coal mines, and determine one of the main types of danger: risk of geodynamic phenomena. The geodynamic phenomena occur and develop under the influence of natural and technological factors. Natural factors determine the rock massif proneness of ato geodynamic manifestations or, in other words, its potential danger due to these phenomena. Occurrence of this danger depends on technological factors. Among the dangerous factors of underground coal production to which primarily belong the geodynamic phenomena, the main ones are gas-dynamic phenomena, which are the most complex by their nature and dangerous by consequences due to high dynamic power and release of great amount of gas during a short period of time. Their consequences can be accidents due to sudden gassing and blockage of workings by coal and rock, explosions of methane and coal dust, destruction of the roadway supports, damage of machines and mechanisms, equipment and devices. As the gas-dynamic phenomena in the rocks massif are accompanied by occurrence of various processes differed by their nature, therefore, risks caused by them should be taken into account at mining operations. When considering the gas-dynamic phenomena attention should be paid to the shock wave propagation, as it is one of the gas dynamic processes. Therefore, purpose of this research was to study specific features of the shock wave propagation in the rock massif in order to prevent dangerous consequences. In this article, the authors consider the processes which occur in the rock massif prone to dangerous gas-dynamic phenomena at the shock wave propagation. The methods of rock mechanics, mechanics of continuous media, gas and thermodynamics were used in the research. Analytical researches of processes and numerical analysis of the received results were carried out. It is shown that a sharp increase of thermodynamic parameters under the action of gas-dynamic phenomena can lead to occurrence of the shock waves. It is further established that an explosive air-methane mixture can be formed in cracks, cavities and pores of the face area. At opening the cavities and pores, cases of shock waves formation in air-methane mixture leading to its detonation are possible. Under adverse conditions, this phenomenon can lead to a fire in the roadway.

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Experimental Study on the Permeability of Weakly Cemented Rock under Different Stress States in Triaxial Compression Tests

Geofluids ◽

10.1155/2018/9035654 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Gangwei Fan ◽

Mingwei Chen ◽

Dongsheng Zhang ◽

Zhen Wang ◽

Shizhong Zhang ◽

...

Keyword(s):

Underground Mining ◽

Axial Strain ◽

Triaxial Compression ◽

Confining Pressure ◽

Initial Permeability ◽

Compression Tests ◽

Mining Operations ◽

Stress Strain ◽

Loading And Unloading ◽

Stress States

Mudstone and shaly coarse sandstone samples of Jurassic units in northwestern China were collected to study the seepage mechanism of weakly cemented rock affected by underground mining operations. Samples were studied using seepage experiments under triaxial compression considering two processes: complete stress-strain and postpeak loading and unloading. The results show that permeability variations closely correspond to deviatoric stress-axial strain during the process of complete stress-strain. The initial permeability is 7 times its minimum, contrasting with lesser differentials of initial, peak, and residual permeability. The magnitude of permeability ranges from 10−17 to 10−19 m2, representing a stable water-resisting property, and is 1 to 2 orders lower in mudstone than that in shaly coarse sandstone, indicating that the water-resisting property of the mudstone is much better than that of the shaly coarse sandstone. Permeability is negatively correlated with the confining pressure. In response to this pressure, the permeability change in mudstone is faster than that in shaly coarse sandstone during the process of postpeak loading and unloading. Weakly cemented rock has lower permeability according to the comparison with congeneric ordinary rocks. This distinction is more remarkable in terms of the initial permeability. Analyses based on scanning electron microscope (SEM) observations and mineral composition indicate that the samples are rich in clay minerals such as montmorillonite and kaolin, whose inherent properties of hydroexpansiveness and hydrosliming can be considered the dominant factors contributing to the seepage properties of weakly cemented rock with low permeability.

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Determination of the Parameters of Technological Schemes for the Development of Coal Seams Prone to Spontaneous Combustion using Computer Simulation

E3S Web of Conferences ◽

10.1051/e3sconf/201910501016 ◽

2019 ◽

Vol 105 ◽

pp. 01016

Author(s):

Sergey Meshkov

Keyword(s):

Computer Simulation ◽

Spontaneous Combustion ◽

Longwall Mining ◽

Underground Mining ◽

Fire Hazard ◽

Modern Technology ◽

Coal Seams ◽

Mining Operations ◽

Gas Dynamic ◽

Mining Coal

The study considers thr problem of endogenous fire hazard in underground mining of coal seams prone to spontaneous combustion. The main trends in the development of modern technology of underground coal mining are shown. The interaction of air-gas-dynamic and geomechanical processes in the development of coal seams by longwall mining is considered. The possibilities of computer simulation of air-gas-dynamic processes in the extraction districts of modern coal mines are considered. The significant influence of geological and mining conditions of mining operations on the distribution of air flow in extraction districts and the efficiency of gas emission control in the workings of the extraction districts are shown. The design scheme and the results of numerical studies (methane and oxygen concentration fields) are given. It is concluded that it is necessary to determine the rational parameters of the preparation, ventilation, isolated drainage and degassing schemes when developing gas-bearing coal seams that are prone to spontaneous combustion. Recommendations are given on improvement of the safety in mining coal seams that are prone to spontaneous combustion.

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Assessment of gas-dynamic danger of Krasnoslobodsky fracture zone of Starobinsky potash deposit

Proceedings of the National Academy of Sciences of Belarus Physical-Technical Series ◽

10.29235/1561-8358-2019-64-2-240-252 ◽

2019 ◽

Vol 64 (2) ◽

pp. 240-252

Author(s):

P. A. Vityaz ◽

I. I. Golovaty ◽

V. Ya. Prushak

Keyword(s):

Rock Mass ◽

Fault Zone ◽

Fracture Zone ◽

Functional System ◽

Geological Structure ◽

Gas Filtration ◽

Mining Operations ◽

Gas Dynamic ◽

Hydrodynamic Systems ◽

Dynamic Phenomena

Gas-dynamic danger of Krasnoslobodsky fracture zone in Starobin Deposit of potassium salts was investigated. The study was carried out taking into account the existing ideas about the mechanism of formation of foci of gas-dynamic phenomena in the salt rock mass of the field, as well as taking into account the results of seismic and hydrogeological studies of the fault zone and the revealed patterns of distribution of gas-dynamic phenomena over the field area. The features of the geological structure of Krasnoslobodsky fracture zone in the upper salt stratum containing layers of potash ore are established. The features of the mechanism of evolution of hydrodynamic systems in fault zones are revealed. It was found that the functional system of halogen metasomatosis in these zones of the rock mass was not shielded, so that the absorption zone of the hydrodynamic system was located in the rocks of the clay-marl strata located above the upper salt strata and horizons of possible mining operations, and fractured rocks of the fault zone provided gas filtration from the system of voids formed during the evolution of hydrodynamic systems. According to the results of the study, it was concluded that in Krasnoslobodsky fracture zone within the upper salt layer there were no conditions for the formation of dangerous foci of gas-dynamic phenomena, such as sudden emissions of salt and gas and collapse of roof rocks. Accordingly, there is a possibility of safe mining operations, such as the penetration of intersecting workings through the fault zone.

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On the issue of defining safe distances and overpressure under impact of shock air blast wave (Magnesitovaya mine)

E3S Web of Conferences ◽

10.1051/e3sconf/202019201027 ◽

2020 ◽

Vol 192 ◽

pp. 01027

Author(s):

Sergey Zharikov ◽

Vyacheslav Kutuev

Keyword(s):

Underground Mining ◽

Industrial Safety ◽

Safe Distance ◽

Mining Operations ◽

Mineral Development ◽

Short Period ◽

The Face ◽

Mine Workings ◽

Technological Methods ◽

Working Section

As the depth of mining increases, attention to the preservation of mine workings and mining blasting is steadily growing. Technological methods of effective mineral development are often limited by dynamic blasting impact causing short-period fluctuations in the rock mass. Therefore, correct explosion impact identification, to a great extent, determines effective mining trends. Some results of researches for minimum blasting impact on mining workings are given in the article. Calculation of safe distances and excess pressure at shock air impact of technological explosions on the Magnezitovaya mine personnel was made. The calculation was made for the 15.5 m mine working section, with two conditions of the total section of the mine workings adjacent to the face of 15.5 m and 31 m with distances of 50 m and 100 m. Overpressure was also calculated for a total cross-section of 15.5 m and distances of 150 and 200 m. It was determined that the safe distance for people under overpressure conditions at the shock air wave front, depending on breaking schemes, is in the range of 150-200 m. The urgency of this research is to ensure industrial safety of underground mining operations.

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