scholarly journals Prediction of Gas Emission from Floor Coalbed of Steeply Inclined and Extremely Thick Coal Seams Mined Using the Horizontal Sublevel Top-Coal Caving Method

2019 ◽  
Author(s):  
Yanwei Hu ◽  
Gang Wang ◽  
Jianqiang Chen ◽  
Zhiyuan Liu ◽  
Cheng Fan
Keyword(s):  
Numerical Simulation ◽  
Prediction Model ◽  
Coal Mine ◽  
Integration Method ◽  
Prediction Methods ◽  
Coal Seams ◽  
Gas Emission ◽  
Mining Operations ◽  
Finite Element Numerical Simulation

In the steeply inclined and extremely thick coal seams (SIETCS) mined using the horizontal sublevel top-coal caving (HSTCC) method, the uncertainty of gas emission is a safety threat to the mining operations. In order to reduce the occurrence of accidents, the determination of gas emission is crucial. In this paper, we first proposed a prediction model for workers at the floor coalbed to calculate gas emission on site. We then put forward a finite element numerical simulation for researchers to predict gas emission from the floor coalbed. At last, we measured gas emitted from the floor coalbed of SIETCS in Wudong Coal Mine in a specific mining period and used the data to verify the applicability and accuracy of these two gas-emission prediction methods. The results showed that the gas emission from Wudong Coal Mine was 1.08 m3/min calculated based on the prediction model and 1.07 m3/min obtained using the user-defined integration method. Both methods have their own advantages, disadvantages and applicable objects, and are important in predicting gas emission from SIETCS mined using HSTCC method.

INFLUENCE OF ANALYSIS RESULTS OF ANALYTICAL COAL SAMPLES ON THE PREDICTION ACCURACY OF HAZARDOUS PROPERTIES OF COAL SEAMS

2021 ◽  
pp. 176-186
Author(s):  
Yevhen Rudniev ◽  
◽  
Vyacheslav Galchenko ◽  
Elvira Filatieva ◽  
Mykhailo Filatiev ◽  
...  
Keyword(s):  
Coal Mine ◽  
Calorific Value ◽  
Mining Area ◽  
The State ◽  
Coal Seams ◽  
Initial State ◽  
Mining Operations ◽  
Mineral Components ◽  
Scientific Substantiation

Purpose: to establish possible quantitative errors in determining the values of some indicators of the degree of metamorphism without attracting the content of total moisture and mineral impurities to predict the hazardous properties of coal mine layers during mining. Methodology: based on the use of initial data on the quality indicators and properties of coals for specific coal seams, given in the reference sources, with the subsequent recalculation of the state of samples from their dry ashless or ashless state to the raw state. Comparison of the samples of indicators were determined, respectively, using analytical samples and based on the results of recalculation to the initial state (close to the production state), conclusions were drawn about possible errors in the case of using the analysis results of the analytical samples to predict hazardous properties of mines. Results: The analytical state of the samples for dry ashless state (daf) or wet ashless state (af) does not correspond to the state of coal in the working area of mining operations (r), which most accurately characterizes the manifestation of mine hazardous properties. The indicators of the release of volatile substances during thermal decomposition of coals, which are used to predict the hazardous properties of mine coal seams, do not directly reflect changes in the elemental composition of coals during metamorphic transformations. Methods for preparing analytical samples provide for grinding to small fractions, removing external moisture and enriching to ash content less than 10%, which does not correspond to the state of coal (r) in the mining area. The use of indicators set for dry ashless combustible (organic) mass excludes the possibility of analyzing the influence of moisture and mineral impurities on the manifestation of the hazardous properties of coal seams. The use of such indicators to predict the hazardous properties of mine coal seams can lead to errors in their determination of 45 ÷ 50%. The hazardous properties of coal seams can be adequately characterized only by the combined composition and properties of organic matter and mineral impurities in a state close to the presence of coal in the mining area. Using the example of possible significant errors in the calorific value, in the case of its use to characterize the hazardous properties of coal mine seams, the expediency of scientific substantiation of a set of indicators for a reliable forecast of a specific hazardous property for a specific seam formation was proved. Scientific novelty: hazardous properties of coal seams are reliably predicted on the basis of the composition and properties of organic and mineral components, reduced to conditions close to the state during mining operations. Practical value: the results obtained give grounds to scientifically substantiate the selection of the necessary indicators for predicting a specific hazardous property of coal seams and make proposals for improving the regulatory framework for the safe conduct of mining operations.

Features of Jianshanchong Klippe and its Control to Gas Geology at Qingshan Coal Mine, Jiangxi Province

2012 ◽  
Vol 164 ◽  
pp. 501-505
Author(s):  
Zhi Gen Zhao ◽  
Jia Chen ◽  
Jia Ping Yan
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Emission Rate ◽  
Coal And Gas Outburst ◽  
Jiangxi Province ◽  
Coal Seams ◽  
Gas Emission ◽  
Gas Outburst ◽  
Transverse Profile ◽  
Tectonic Coal

The coal and gas outburst is serious at Qingshan Coal Mine of Jiangxi Province, so it is of significance to research the features of Jianshanchong klippe and its control to gas geology. The research reveals that: Jianshanchong klippe is distributed from the east boundary of Qingshan Coal Mine to No. 45 Exploration Line, its transverse profile is like a funnel while its longitudinal profile is like a wedge, northwest side of the klippe is thicker and deeper while southeast side is thinner and more shallow. Because of the cover and insert of Jianshanchong klippe, the structure of coal-bearing strata is more complex, some secondary folds are formed, and also, the coal seam is changed greatly, the tectonic coal is well developed and the coal seam is suddenly thickening or thinning. Due to the effect of Jianshanchong klippe, the coal and gas outbursts occur in the area of secondary folds, thicker coal seams or tectonic coals. Concerning the prediction of gas geology in deep area, in view of the facts including simpler structure, stable coal seam and decreased thickness, the gas emission rate and the coal and gas outburst will decrease in Fifth and Sixth Mining Level than that in Second and Third Mining Level

The Study on Roadway Layout in Coordination of Mining Coal Seams Base on Failure of Floor Strata

2014 ◽  
Vol 889-890 ◽  
pp. 1362-1374 ◽  
Author(s):  
Yong Zhang ◽  
Chun Lei Zhang ◽  
Chun Chen Wei ◽  
Ya Dong Liu ◽  
Shi Qing Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Simulation Software ◽  
Coal Seams ◽  
Group Coordination ◽  
Mining Coal ◽  
Two Sides

In order to make sure the reasonable roadway layout in lower seam of close coal mining group coordination in Lijiahao coal mine, firstly, applying the theoretical analysis and geological radar detection to get the influence depth of mining from the up coal seam 2-2 to the floor is about 20m, the results show that the thickness of complete strata is about 15m, then determining to use the outward alternate entries in lower seam roadway by using theoretical analysis. At last, determining the distance of outward alternate entries is 12-14m by using FLAC3D numerical simulation software to simulate the change of stress and displacement in roof floor and two sides of roadway.

DEVELOPMENT DEPTH AS COMPLICATION FACTOR OF WORKING OFF CONDITIONS OF COAL SEAMS

2021 ◽  
pp. 37-50
Author(s):  
Serhii Nehrii ◽  
◽  
Tetiana Nehrii ◽  
Ruslana Shepelenko ◽  
Mykyta Kachalov ◽  
...  
Keyword(s):  
Coal Mining ◽  
Practical Significance ◽  
Natural Phenomena ◽  
Coal Seams ◽  
Mining Operations ◽  
Scientific Approach ◽  
Different Depths ◽  
The Impact ◽  
Dynamic Phenomena

Purpose: development of a scientific approach to clarify the areas of technologies application for mining roadways protection on the depth of mining operations. Methodology. Analysis and generalization of the results of scientific and technical research on the impact of natural phenomena on the process of coal mining. Graphoanalytical establishment of application and areasand determination of critical depths for protection mining roadways technologies. Results. Was studied and generalized the information on the influence of natural phenomena on the process of coal mining with the transition of mining to great depths. The necessity of determining the critical depths, exceeding which complicate the conditions of coal seams development due to the negative manifestations of natural phenomena, which requires changes in the technology of mining. Critical depths for different conditions, phenomena and technologies are different. For gas-saturated seams, they are determined by the methane-bearing capacity of seams, production intensity and ventilation conditions of underground roadways, for seams prone to gas-dynamic phenomena – they are determined by the stress-strain state (SSS) and strength of surrounding rocks. The critical depth in the application of protection roadways technologies also depends on the SSS of rocks and their strength. Therefore, a scientific approach has been developed to clarify the areas of application of technologies for the protection of mining roadways on the depth of mining. The critical depths are determined by the strength conditions of the rocks according to the relevant criteria. It based on the Ncr/Rc criterion, graphoanalytical method for determining the areas of application and determining the critical depths for different technologies of protection mining roadways was proposed. Scientific novelty: was developed a scientific approach to clarify the areas of application of protection mining roadways technologies on the depth of mining. Practical significance: the proposed approach to clarify the areas of application for the protection of mining roadways technologies at different depths simplifies the search for effective engineering solutions during planning mining operations.

ON THE INFLUENCE OF MINERAL IMPURITIES ON THE MANIFESTATION OF DANGEROUS PROPERTIES OF COAL SEAMS

2021 ◽  
pp. 85-95
Author(s):  
Yevhen Rudniev ◽  
◽  
Mykola Antoshchenko ◽  
Elvira Filatieva ◽  
Julia Romanchenko ◽  
...  
Keyword(s):  
Coal Mine ◽  
Regulatory Framework ◽  
Plastic Layer ◽  
Coal Seams ◽  
Mining Operations ◽  
Combined Use ◽  
Mineral Components ◽  
Main Components ◽  
Fossil Coals

Purpose: to establish a possible correspondence between metamorphic processes with artificial thermal destruction of coals and their ashing in order to identify the components of mineral impurities that can affect the manifestation of the hazardous properties of coal mine seams. Methodology is based on a comparison of metamorphic processes that took place at a certain temperature mode in the bowels of the Earth and the production of artificial coals and their ashing. Results: The research made it possible to reveal the important role of mineral impurities in the formation of the hazardous properties of coal seams. This is due to both the significant possible content of mineral impurities in fossil coals, and the simultaneous presence of the main components that determine the hazardous properties of coal seams (carbon, hydrogen, sulfur, oxygen and moisture), both in the organic and in the mineral parts of fossil coals. To improve the regulatory framework for the safe conduct of mining operations, it is necessary to take into account features of the properties of fossil coals due to the presence of mineral impurities in them. In modern regulatory documents on the safe conduct of mining operations, in general, several indicators are used without proper scientific justification: the mass yield of volatiles during the thermal decomposition of coal, the volumetric yield of volatile substances, the thickness of the plastic layer and the logarithm of the electrical resistivity of anthracites. Their values are related to the dry ash-free mass of organic matter only. This excludes consideration of the influence of mineral impurities on the manifestation of the hazardous properties of coal mine seams during mining operations. In many cases, the content of moisture and sulfur is a criterion for the manifestation of hazardous properties of coal seams. They belong to the integral components of both organic and mineral constituents of fossil coals. The share of mineral impurities in the coals of individual coal seams can be more than 40%. The presence of oxygen, hydrogen, sulfur and moisture in mineral impurities significantly affects the manifestation of the hazardous properties of coal seams during mining. The content of mineral impurities in fossil coals in engineering calculations can be determined on the basis of the ash content of coals according to known empirical relationships, corrected for the content of total sulfur and, in some cases, carbon dioxide. Scientific novelty: the significant influence of mineral impurities in fossil coals on the manifestation of hazardous properties of coal seams during mining operations has been proved. Practical value: the results obtained allow substantiating the methodology for the combined use of the composition of organic and mineral components of fossil coals for a reliable forecast of the manifestation of hazardous properties of coal seams and improving the regulatory framework for their safe mining.

Coal Mine Gas Prediction Model Based on Ant Colony Neural Network

2012 ◽  
Vol 546-547 ◽  
pp. 3-7 ◽  
Author(s):  
Jia Tang Cheng ◽  
Hui Zhang
Keyword(s):  
Neural Network ◽  
Prediction Model ◽  
Coal Mine ◽  
Prediction Accuracy ◽  
Ant Colony Algorithm ◽  
Ant Colony ◽  
Gas Emission ◽  
Bp Network ◽  
Coal Mine Gas ◽  
Mine Gas

In order to improve the prediction accuracy and prediction speed of coal mine gas emission, ant colony algorithm combining with neural network is used for prediction models design. Choose an important factor influencing gas emission, establish of its neural network prediction model. Select the network mean square error as the objective function, through the ant colony algorithm iteration achieve optimal BP network weights, and use the optimized BP network for gas emission prediction. Simulation results show that the method has high fitting prediction accuracy.

scholarly journals Gas Emission Prediction Model of Coal Mine Based on CSBP Algorithm

2016 ◽  
Vol 7 ◽  
pp. 09006 ◽  
Author(s):  
Yan Xiong ◽  
Jia-Tang Cheng ◽  
Zhi-Mei Duan
Keyword(s):  
Prediction Model ◽  
Coal Mine ◽  
Gas Emission

scholarly journals Study on Gas Control Methods Optimization for Mining Safety

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Liwen He ◽  
Yingcheng Dai ◽  
Sheng Xue ◽  
Chunshan Zheng ◽  
Baiqing Han ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Control Measures ◽  
Coal Seams ◽  
Gas Emission ◽  
Gas Drainage ◽  
Geological Conditions ◽  
Mining Safety ◽  
Gas Control ◽  
Outburst Hazard

Effective gas control is of significance for safe efficient coal mining in Haizi Coal Mine and other mines with similar geological conditions. This study concentrates on gas control theories and techniques in multiple coal seams of Haizi Coal Mine (No. 7, No. 8, No. 9, and No. 10 coal seam from top to bottom). To minimize risk of high gas emission and outburst hazard, No. 10 seam was mined first as a protective seam prior to the mining of its overlying outburst-prone No. 7, No. 8, and No. 9 seam. Four gas drainage measures were determined for gas control, including cross-measure boreholes into overlying coal seams, surface goaf wells, roof boreholes, and roof gas drainage roadway. These gas control measures, if implemented through entire coal seam extraction, would be possibly uneconomic. An investigation was undertaken to analyze effects of those four measures on gas emission, methane concentration, and gas drainage quantity in No. 2 1024 mining panel of No. 10 seam. Results indicate that the highly expensive gas drainage measure of a roof roadway has poor drainage performance and could be effectively replaced by roof boreholes. When adopting the optimized combination of gas drainage measures, drainage efficiency of No. 7 seam, No. 8 seam, and No. 9 seam could reach 58.64% and decrease gas pressure to be below 0.74 MPa. Outcomes of this study could provide beneficial guidance not only for gas drainage design optimization in Haizi Coal Mine but also for other multiple-seam mines with similar mining and geological conditions, for increasing gas drainage efficiency and guaranteeing mining safety.

scholarly journals The Determination of the Methane Content of Coal Seams Based on Drill Cutting and Core Samples from Coal Mine Roadway

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 178
Author(s):  
Nikodem Szlązak ◽  
Marek Korzec ◽  
Kazimierz Piergies
Keyword(s):  
Coal Mine ◽  
Standard Procedure ◽  
Methane Content ◽  
Gas Content ◽  
Hard Coal ◽  
Coal Seams ◽  
Drill Cuttings ◽  
Mine Roadway ◽  
Drill Cutting

The determination of methane content of coal seams is conducted in hard coal mines in order to assess the state of methane hazard but also to evaluate gas resources in the deposit. In the world’s mining industry, natural gas content in coal determination is usually based on direct methods. It remains the basic method in Poland as well. An important element in the determination procedure is the gas loss that occurs while collecting a sample for testing in underground conditions. In the method developed by the authors, which is a Polish standard, based on taking a sample in the form of drill cuttings, this loss was established at a level of 12%. Among researchers dealing with the methane content of coal, there are doubts related to the procedures adopted for coal sampling and the time which passes from taking a sample to enclosing it in a sealed container. Therefore, the studies were designed to evaluate the degree of degassing of the sample taken in the form of drill cuttings according to the standard procedure and in the form of the drill core from a coal mine roadway. The results show that the determinations made for the core coincide with the determinations made for the drill cutting samples, with the loss of gas taken into account.

scholarly journals DETERMINATION OF METHANE DESORPTION ZONE FOR THE DESIGN OF A DRAINAGE BOREHOLE PATTERN (CASE STUDY: E4 PANEL OF THE TABAS MECHANIZED COAL MINE, IRAN)

2021 ◽  
Vol 36 (1) ◽  
pp. 61-75
Author(s):  
Ali Hosseini ◽  
Mehdi Najafi
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Methane Emissions ◽  
Gas Content ◽  
Coal Seams ◽  
Mining Operations ◽  
Methane Drainage ◽  
Tabas Coal Mine ◽  
Drainage Borehole

Underground coal mining is known as one of the major sources of methane emissions which mainly occurs after underground coal extraction. Rock strata in-situ methane can potentially be the most significant hazard in coal mining operations. To prevent or minimize the risks of methane emissions, methane drainage approaches have been adopted by coal mines. Rock mass methane drainage is the most efficient and effective approach toward controlling methane hazards as it prevents and reduces the frequency of methane emissions, outflows into the working area and sudden outbursts of methane and rocks. The method includes drilling boreholes from the tailgate side to the unstressed zone in the roof and floor strata above and below a working coal seam. The coal seam gas content in Tabas Parvadeh I is estimated to be about 16 m3 /t, which is relatively high. Based on exploration data, five distinct coal seams have been identified (B1, B2, C1, C2 and D) at the coal deposit and currently C1 is being worked. Considering the high value of C1 gas content and surrounding rocks, the Methane Drainage System (MDS) has been utilized for gas drainage. This paper tries to determine the desorption area which is essential and helpful for the selection of an effective drilling pattern into the adjacent coal seams. In this study, the methane drainage zone in the E4 panel of the Tabas coal mine was calculated using experimental equations and a drainage borehole pattern was determined.

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