Risk analysis of coal self-ignition in longwall gob: A modeling study on three-dimensional hazard zones

Abstract Coal self-ignition in longwall gob (mined-out) areas has caused serious personal casualties and economic losses. Effective determination of coal self-ignition hazard zones in longwall gob areas can enable more targeted fire prevention. In this paper, the effects of ventilation mode and working face dip on the oxygen supply for coal self-ignition were studied. A three-dimensional dip-adjustable physical model of the longwall gob was developed to study the coal self-ignition hazard zones at different dip angles varying from −45° to +45° with respect to the horizontal plane. In addition, the coal self-ignition risk was analyzed through the position, width and space range of the hazard zones. The results demonstrate that the hazard zone features “S”-types both in the dip and the advanced directions of the working face, with a dip angle ranging from +5° to +15° the hazard zone primarily locates on the lower air intake side close to the middle when the angle exceeds +25°. With an angle ranging from −5° to −45°, the hazard zone scope is reduced along the direction from the upper side to the lower side and gradually concentrates at the lower air return side. Being different from the probability of coal self-ignition, the hazard severity may reduce with dip angle regardless of ventilation mode. A risk analysis method based on three-dimensional physical modeling is proposed and applied to analyze the coal self-ignition in the longwall gob. This analysis is of great significance for both fire safety and miners' health.

[1]  John Carras,et al.  Self-heating of coal and related materials: Models, application and test methods , 1994 .

[2]  Tongqiang Xia,et al.  A fully coupled hydro-thermo-mechanical model for the spontaneous combustion of underground coal seams , 2014 .

[3]  Boleslav Taraba,et al.  Effect of longwall face advance rate on spontaneous heating process in the gob area – CFD modelling , 2011 .

[4]  Deming Wang,et al.  Numerical Study on Thermal Environment in Mine Gob Under Coal Oxidation Condition , 2013 .

[5]  Yuehua Deng,et al.  Feasibility analysis of gob-side entry retaining on a working face in a steep coal seam , 2014 .

[6]  Liming Yuan,et al.  The effect of ventilation on spontaneous heating of coal , 2012 .

[7]  Zenghua Li,et al.  Effects of low molecular weight compounds in coal on the characteristics of its spontaneous combustion , 2015 .

[8]  C. Karacan,et al.  Monte Carlo Simulation and Well Testing Applied in Evaluating Reservoir Properties in a Deforming Longwall Overburden , 2011 .

[9]  Feng Gao,et al.  Evolution of coal self-heating processes in longwall gob areas , 2015 .

[10]  Deming Wang,et al.  Kinetics characteristics of coal low-temperature oxidation in oxygen-depleted air , 2015 .

[11]  Zhang Dongpo,et al.  Distribution law of gas and change rule of "three zones" in the goaf of fully mechanized top-coal caving working face under the continuous nitrogen injection , 2011 .

[12]  C. Özgen Karacan,et al.  Prediction of Porosity and Permeability of Caved Zone in Longwall Gobs , 2010 .

[13]  C. Özgen Karacan,et al.  A new methane control and prediction software suite for longwall mines , 2011, Comput. Geosci..

[14]  Jun Deng,et al.  Quantitative Determination for the“Three Zones”of Coal Spontaneous Combustion in Gobs based on Probability Function , 2013 .

[15]  Bo Tan,et al.  Numerical study on effects of air leakages from abandoned galleries on hill-side coal fires , 2014 .

[16]  Howard L. Hartman,et al.  Mine ventilation and air conditioning , 1961 .

[17]  Fudong Ge,et al.  Analysis of stability of support and surrounding rock in mining top coal of inclined coal seam , 2014 .

[18]  Pang Xu-fen.  Study on Simulation Experiment of Overburden Strata Migration Law for Backfill Mining in Steep Inclined Seam , 2014 .

[19]  Yuanping Cheng,et al.  New technological partition for “three zones” spontaneous coal combustion in goaf , 2013 .

[20]  Maria Izquierdo,et al.  Influence of soil cover on reducing the environmental impact of spontaneous coal combustion in coal waste gobs: A review and new experimental data , 2011 .

[21]  Chae Hoon Sohn,et al.  A novel method to suppress spontaneous ignition of coal stockpiles in a coal storage yard , 2012 .

[22]  Akbar Esfahanipour,et al.  Human health and safety risks management in underground coal mines using fuzzy TOPSIS. , 2014, The Science of the total environment.

[23]  Shengqiang Yang,et al.  Coal spontaneous combustion prediction in gob using chaos analysis on gas indicators from upper tunnel , 2015 .

[24]  Bogdan Z. Dlugogorski,et al.  Coal oxidation at low temperatures: oxygen consumption, oxidation products, reaction mechanism and kinetic modelling , 2003 .

[25]  Jishan Liu,et al.  Simulation of coal self-heating processes in underground methane-rich coal seams , 2015 .

[26]  Lizhong Yang,et al.  The inclination effect on CO generation and smoke movement in an inclined tunnel fire , 2012 .