scholarly journals THEORY AND PRACTICE OF DETERMINING THE CATEGORY HAZARD OF COAL MINES BY THE GAS FACTOR

2021 ◽  
Author(s):  
Elvira Filatieva ◽  
◽  
Aleksandr Oleinichenko ◽  
Mykhailo Filatiev ◽  
Valerii Sokolenko ◽  
...  
Keyword(s):  
Experimental Data ◽  
Coal Mines ◽  
Field Studies ◽  
Theory And Practice ◽  
Gas Release ◽  
Coal Seams ◽  
Working Face ◽  
Gas Bearing ◽  
Enclosing Rocks ◽  
Safe Mining

A comparative analysis of the theoretical and practical definition of the category hazard of coal mines by gas factor based on experimental data obtained in real conditions of mining gas-bearing coal seams is presented. The mine's hazard category by gas factor is determined in accordance with the current regulatory document. The processing of experimental data obtained in field studies leads to contradictions in the requirements for the safe mining of gas-bearing coal seams. The necessity of changing the regulatory framework for predicting methane release and establishing the category hazard of mines by gas factor is substantiated, as well as the theoretical part of the research is experimentally confirmed and practical proposals are given to improve the requirements of regulatory documents for the safe mining of gas-bearing coal seams. The gas release from seven possible sources, the exposed surface of the working face, the undermined adjacent seams and their enclosing rocks, the overworked adjacent seams and enclosing rocks, the worked-out space of the stopped lavas, are accepted for consideration. The studies have shown that by removal the bottom from cut and the area of the mined-out space of the operated section and the wing of the mine field, taking into account the stopped longwalls, it is possible to predict the processes of rock displacement that determine the absolute gas release from the undermined sources.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals Methane Content Estimation in DuongHuy Coal Mine

2018 ◽  
Vol 35 ◽  
pp. 01005 ◽  
Author(s):  
Van Thinh Nguyen ◽  
Waldemar Mijał ◽  
Vu Chi Dang ◽  
Thi Tuyet Mai Nguyen
Keyword(s):  
Experimental Data ◽  
Coal Mining ◽  
Coal Mine ◽  
Coal Mines ◽  
Methane Content ◽  
Underground Coal Mining ◽  
Coal Seams ◽  
Underground Coal Mine ◽  
Different Depths ◽  
Quang Ninh

Methane hazard has always been considered for underground coal mining as it can lead to methane explosion. In Quang Ninh province, several coal mines such as Mạo Khe coal mine, Khe Cham coal mine, especially Duong Huy mine that have high methane content. Experimental data to examine contents of methane bearing coal seams at different depths are not similar in Duong coal mine. In order to ensure safety, this report has been undertaken to determine a pattern of changing methane contents of coal seams at different exploitation depths in Duong Huy underground coal mine.

scholarly journals DYNAMICS OF GAS EMISSION FROM EXPOSED SURFACE OF GAS-BEARING COAL SEAMS HAVING MEDIUM THICKNESS

2021 ◽  
Vol 13 (3) ◽  
pp. 441-448
Author(s):  
Nikolai KACHURIN ◽  
◽  
Galina STAS ◽  
Alexander KACHURIN ◽  
◽  
...  
Keyword(s):  
Coal Seam ◽  
Mathematical Models ◽  
Driving Forces ◽  
Mathematical Physics ◽  
Gas Release ◽  
Coal Seams ◽  
Excessive Pressure ◽  
Methane Release ◽  
Mine Workings ◽  
Gas Bearing

The goal of the research was to clarify the regularities of the dynamics of gas release from the surface of the outcrop of the developed coal seam. The main research methods were theoretical methods of mathematical physics and non-equilibrium thermodynamics. Gas-bearing coal seams are usually mined underground. When driving development workings, outcropping surfaces of gas-bearing coal seams appear and gases in the seams under excessive pressure are released into the atmosphere of the mine workings. Gas-bearing coal seams are usually mined underground. When driving preparatory workings, surfaces of outcropping of gas-bearing coal seams arise and gases that are in the seams under excessive pressure are released into the atmosphere of the mine workings. The most important gas-dynamic characteristic of this process is the rate of gas release, which represents the volume of gases released from a unit area of exposure of a coal seam per unit of time. A generalized law of resistance for gas filtration in a rock mass is recommended, and a fairly rigorous thermodynamic substantiation is given. It is shown that the densities of gas mass flows in accordance with the postulate of their linear relationship with the driving forces are determined by the Onsager relation. The results obtained and their discussion is presented. Mathematical models are proposed for engineering calculations of the dynamics of methane release from the outcropping surface of medium-thick coal seams. The error of the adopted approximations does not exceed 3%. The intensity of methane release is directly related to the planogram of work in the working face. Analysis of this dependence indicates that during the extraction cycle, methane release increases due to an increase in the area of the gas-release surface. The main conclusions are as follows: mathematical modeling of the processes of gas movement in a porous sorbing medium using approximate mathematical models representing linearized equations of mathematical physics; the regularities of the dynamics of the rate of gas release from the surface of the outcrop of a gas-bearing coal seam is the theoretical basis for the mathematical description of the process of gas release; the use of a linearized hyperbolic filtration equation most accurately describes the processes of methane release from the outcropping surface of mined coal seams.

Features of Borehole Degassing of the Outburst-prone Coal Seams

2020 ◽  
pp. 74-78
Author(s):  
V.S. Zaburdayev ◽  
◽  
Yu.А. Filippov ◽  
Keyword(s):  
Coal Seams ◽  
Strength Factor ◽  
Mining Areas ◽  
Coal Layer ◽  
Methane Extraction ◽  
Working Face ◽  
Underground Workings ◽  
Coal Reserves ◽  
Gas Bearing ◽  
Coal Strength

The conditions and features are given concerning the degassing of outburst-prone coal seams by wells drilled from the underground workings in the plane of the mined seam. Technological schemes for the location of wells in the mining areas during the preparation and development of the coal seams prone to sudden outbursts of coal and gas were substantiated taking into account the coal strength determined using the method of M.M. Protodyakonov. The scheme of coal seams degassing by wells oriented to the working face line is recommended with a coal strength factor f ≥ 1.3, the degassing scheme with crossed wells — at f < 1.3. The wells are drilled parallel to the working face line and oriented to it. The schemes are implemented in the shallow mines of Karaganda (Kazakhstan), Ukraine and China. Degassing of coal seams not unloaded from the rock pressure by crossing wells ensured an increase in methane production from 1 ton of coal by 0.4–4.8 m3 in the conditions of seams with different coal strength. The highest indicators were achieved in the powerful outburst-prone seams with a coal strength factor of f = 0.3–0.8 in the conditions of the mines of Karaganda Basin, where the volumes of methane extraction by crossing wells were 5.0–5.6 m3 per ton of the degassed coal reserves in the working areas. In the conditions of the outburst-prone shallow seams of Ukraine, the volumes of methane extraction from 1 ton of the degassed coal reserves on the medium density seams amounted to 2.5–4.4 m3 with a coal strength factor of f = 0.6–1.1. 2-2.3 m3 of methane was removed from 1 ton of coal at the Dziulishan mine (China) at a strongly crushed coal layer II1 with a strength factor f = 0.3–0.6. The use of degassing schemes for gas-bearing and outburst-prone coal seams ensures an increase in the productivity of working faces and, as a result, high economic indicators.

Use of Destressing Drilling to Ensure Safety of Donbass Gas-bearing Coal Seams Extraction

2019 ◽  
pp. 7-11
Author(s):  
V.S. Brigida ◽  
◽  
Yu.V. Dmitrak ◽  
O.Z. Gabaraev ◽  
V.I. Golik ◽  
...  
Keyword(s):  
Coal Seams ◽  
Gas Bearing

Numerical analysis of aerogasdynamic processes for justification of parameters of longwall panels development at intensive mining of thick flat gas-bearing coal seams

2019 ◽  
Vol 4 (6) ◽  
pp. 93-103
Author(s):  
O.I. Kazanin ◽  
◽  
A.M. Cherdancev ◽  
A.A. Sidorenko ◽  
V.Y. Alekseev ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Coal Seams ◽  
Gas Bearing

The nature of entrepreneurial orientation strength: the impact of shared values on firm performance

2021 ◽  
pp. 1-21
Author(s):  
Laurence G. Weinzimmer ◽  
Eric J. Michel ◽  
Jennifer Robin
Keyword(s):  
Firm Performance ◽  
Entrepreneurial Orientation ◽  
Convergent Validity ◽  
Field Studies ◽  
Theory And Practice ◽  
Interactive Effects ◽  
Revenue Growth ◽  
Entrepreneurship Theory ◽  
The Impact ◽  
Strong Culture

Abstract Drawing on Wales, Monsen, and McKelvie's (2011, Entrepreneurship Theory and Practice, 35(5), 895–923) model of entrepreneurial orientation pervasiveness and the strong culture hypothesis (Denison, 1984, Organization Dynamics, 13, 4–22), this study investigates how entrepreneurial orientation (EO) strength, defined as the level of agreement in the shared perceptions of EO, serves as a boundary condition of the EO–firm performance relationship. Four field studies provide evidence for a valid and reliable 10-item multidimensional measure of entrepreneurial orientation, the EO-10, which in turn, may be used to assess EO strength. We establish content and construct validity of the EO-10 (study 1; n = 447 employees), criterion-related validity with revenue growth and sales growth (study 2; n = 412 employees in 43 profit centers), and convergent validity with Covin and Slevin's (1989, Strategic Management Journal, 10, 75–87) 9-item measure (study 3; n = 291 employees). Finally, in study 4 (n = 853 employees nested in 22 organizations), we demonstrate the interactive effects of EO and EO strength on profit growth and revenue growth. In sum, this study provides conceptual and empirical evidence for the importance of EO strength as a moderator of the EO–firm performance relationship.

Measurement of Angular Acceleration of a Rigid Body Using Linear Accelerometers

1975 ◽  
Vol 42 (3) ◽  
pp. 552-556 ◽  
Author(s):  
A. J. Padgaonkar ◽  
K. W. Krieger ◽  
A. I. King
Keyword(s):  
Experimental Data ◽  
Rigid Body ◽  
Simple Procedure ◽  
Three Dimensional ◽  
Angular Acceleration ◽  
Theory And Practice ◽  
Body Segments ◽  
Impact Biomechanics ◽  
The Stability ◽  
Definition Of

The computation of angular acceleration of a rigid body from measured linear accelerations is a simple procedure, based on well-known kinematic principles. It can be shown that, in theory, a minimum of six linear accelerometers are required for a complete definition of the kinematics of a rigid body. However, recent attempts in impact biomechanics to determine general three-dimensional motion of body segments were unsuccessful when only six accelerometers were used. This paper demonstrates the cause for this inconsistency between theory and practice and specifies the conditions under which the method fails. In addition, an alternate method based on a special nine-accelerometer configuration is proposed. The stability and superiority of this approach are shown by the use of hypothetical as well as experimental data.

Development of designing and implementation method of magnetic execution unit of downhole valve for the bottomhole assembly

2020 ◽  
pp. 38-44
Author(s):  
I.Y. Shirali ◽  
◽  
V.Yu. Tsivilitsin ◽  
İ.B. Bondar ◽  
R.A. Hasanov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Calculation Methods ◽  
Well Drilling ◽  
Power Characteristics ◽  
Drilling Tools ◽  
Execution Unit ◽  
Implementation Method ◽  
Oil Gas ◽  
Gas Bearing

The structure of two types of magnetic valve is offered and the calculation methods of their pull-in force developed as well. The formulas of calculation of pull-in force in the main area of valves’ power characteristics are obtained. Experimental data are in alignment with theoretical calculations. Power characteristics of offered structures of magnetic valves may be changed in terms of the offered structural execution of magnetic valves. Experimental test of obtained formulas has been carried out. The ways of changing the power characteristics of magnetic valves in accordance with the requirements of certain applications are presented. The structures of magnetic reversing valves for drilling tools used in well drilling in various oil-gas bearing areas of SOCAR have been developed.

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