Effect of longwall face advance rate on spontaneous heating process in the gob area – CFD modelling

Fuel ◽  
2011 ◽  
Vol 90 (8) ◽  
pp. 2790-2797 ◽  
Author(s):  
Boleslav Taraba ◽  
Zdeněk Michalec
Keyword(s):  
Longwall Face ◽  
Heating Process ◽  
Face Advance ◽  
Spontaneous Heating ◽  
Cfd Modelling ◽  
Advance Rate ◽  
Gob Area

scholarly journals Development of oxidation heat of the coal left in the mined-out area of a longwall face: Modelling using the fluent software

2008 ◽  
Vol 44 (1) ◽  
pp. 73-81 ◽  
Author(s):  
B. Taraba ◽  
V. Slovak ◽  
Z. Michalec ◽  
J. Chura ◽  
A. Taufer
Keyword(s):  
Bituminous Coal ◽  
Three Dimensional ◽  
Longwall Face ◽  
Heating Process ◽  
Three Dimensional Model ◽  
Main Attention ◽  
Fluent Software ◽  
Laboratory Investigations ◽  
Gob Area

A commercial CFD software program, Fluent, was used to study oxidation processes in the longwall mined-out (gob) area. A three-dimensional model of the gob area with an advancing coal face has been developed. For the model, typical oxidation behavior of a bituminous coal from the Ostrava-Karvin? District was incorporated as resulted from laboratory investigations. The longwall gob area was designed on the basis of the actual longwall face district. Detailed measurements in the district then enabled re-verification of the model outputs with actual data in situ. The main attention was paid to modelling the effect of grain size of the coal left in the mined-out area on the oxidation heat and gases evolution. Numerical simulations confirmed the existence of an 'optimal' zone for intense development of the spontaneous heating process in the gob area.

Impact of coal output concentration on methane emission to longwall faces / Wpływ koncentracji wydobycia na wydzielanie metanu do wyrobisk ścianowych

2012 ◽  
Vol 57 (1) ◽  
pp. 3-21
Author(s):  
Nikodem Szlązak ◽  
Czesław Kubaczka
Keyword(s):  
Linear Regression ◽  
Bearing Capacity ◽  
Methane Emission ◽  
Linear Dependence ◽  
Longwall Face ◽  
Hard Coal ◽  
Face Advance ◽  
Daily Output ◽  
Methane Drainage ◽  
Non Linear

An increase in concentration of coal output in Polish hard coal mines contributes to a significant increase in absolute methane-bearing capacity in mining areas. Measurements of methane concentration were taken in selected longwall faces in order to estimate the influence of coal output on methane hazard. The measurements were taken from 2006 to 2008 in 8 longwalls in mines with high methane hazard. The parameters for longwalls where measurements were taken are presented in table 1. Average daily output ranged from 1380 to 2320 Mg: however the maximum daily output amounted to 5335 Mg. Absolute methane-bearing capacity ranged from 4.44 to 56.41 m3/min. Longwalls were ventilated with a U and Y system and their ventilation schemes are presented in figure 1. The period of measurements ranged from 29 to 384 days. The results obtained were used to determine the influence of changes in output on methane hazard. For each longwall under research statistical estimation of parameters, such as: ventilation air methane (VAM) emission, amount of methane captured by a drainage system, absolute methane-bearing capacity and an advance of longwall face was conducted. In order to determine the influence of a longwall face advance on methane-bearing capacity the probabilistic model of the distribution of those parameters on the basis of the measurement results was used. In order to determine the dependence between ventilation air methane emission, methane drainage, absolute methane-bearing capacity and longwall advance, the distribution of analysed variables was checked by means of Kolmogorow-Smirnov normality test. The results of this test are presented in table 2. Table 3 presents values for correlation co-efficient r(x,y). When analyzing the results presented in table 3 it must be observed that in case of most longwalls there is a high correlation between ventilation air methane emission, absolute methane-bearing capacity and longwall advance. However, in longwalls N-10 i W-5 the correlation between methane drainage capture and longwall advance is equally strong. In all other longwalls the correlation is average. In all cases the correlations were positive, which means that together with an increase in advance, there is also an increase in ventilation air methane emission, methane drainage capture and absolute methane-bearing capacity On the basis of determination co-efficient it can be concluded that in cases under consideration at least half (about 50%) of results, ventilation air methane emission, methane drainage capture and absolute methane-bearing capacity can be explained linearly by an influence of longwall advance, while this statement can be assumed with the probability close to 100%. It should also be added that the lack of very high or full correlations means that examined parameters do not fully show linear dependence; however there might be other functional correlations. Because of a complex character of phenomena happening during mining it is not possible to determine full correlations. However, the interpretation of results allows us to claim that an influence of wall advance on methane emission amounts to 30 to 70% depending on a given case. Therefore, other factors, for example geological ones, which were not taken into consideration, will contribute to the level of methane hazard. Table 4 presents determined co-efficients of linear regression. On the basis of the data in table 4, an equation describing the dependence of absolute methane-bearing capacity in a longwall on a longwall advance in the form (11) can be formed. Table 5 presents determined co-efficients of non-linear regression. On the basis of the data in table 5, an equation describing the dependence of absolute methane-bearing capacity in a longwall on a longwall advance in the form (13) can be formed. When comparing co-efficient R2 of the contribution of the explained variance in tables 4 and 5 it can be obcserved that non-linear dependence explains better the results of mining measurements. The similar dependence presenting methane emission as dependent on output is suggested by Myszor (1985). The conditions for safe mining can be given for a determined methane emission.

scholarly journals Evaluation of the face advance rate on ground control in the open face area associated with mining operations in Western China

2020 ◽  
Vol 17 (2) ◽  
pp. 390-398 ◽  
Author(s):  
Gaofeng Song ◽  
Zhenwei Wang ◽  
Kuo Ding
Keyword(s):  
Western China ◽  
Ground Control ◽  
Face Advance ◽  
Mining Operations ◽  
Movement Velocity ◽  
Strata Movement ◽  
Advance Rate ◽  
Hard Roof ◽  
Roof Fall ◽  
The Face

Abstract The modern longwall faces in coal bases in Western China are being mined at an increasingly faster rate, yet the consequences of the face advance rate on the ground control and strata movement require further investigation. In this study, two improved physical models with different advance rates are developed to evaluate the roof failure characteristics; the strata movement; the displacement of the strong, massive roof; and the roof movement velocity. The results show that: (i) regular falls of the immediate roof and major falls of the hard roof are observed with the progressive development of the longwall face. Massive fractures on the roof strata extending from the face to the ground surface develop on a major roof fall. (ii) Model I, which has a slower face advance rate, shows a major roof fall interval of 65 m, which is slightly less than the 70 m found by Model II, which advances at a faster rate. Larger strata fractures are observed in Model I, while the gob area of Model II is better filled with waste rock materials. (iii) The displacement and velocity of the hard roof are unnoticeable until a massive roof fall. Maximum displacement occurs on a major roof fall, which is 50 mm for Model I and 30 mm for Model II. The maximum roof movement velocity on a major roof fall is 4.6 cm per min and 5.9 cm per min for Models I and II, respectively.

scholarly journals Influence of face advance rate on geomechanical and gas-dynamic processes in longwalls in gassy mines

2018 ◽  
pp. 3-8 ◽  
Author(s):  
A. A. Sidorenko ◽  
◽  
Yu. G. Sirenko ◽  
S. A. Sidorenko ◽  
◽  
...  
Keyword(s):  
Dynamic Processes ◽  
Face Advance ◽  
Advance Rate ◽  
Gas Dynamic
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