Role of gas energy during coal outbursts

Valliappan, S.; Zhang, Wohua

doi:10.1002/(sici)1097-0207(19990310)44:7<875::aid-nme527>3.0.co;2-g

Cited by 100 publications

(33 citation statements)

References 6 publications

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“…Coal gas is a major contributor to coal mine outbursts (Valliappan and Zhang 1999;Jacek 2011) and can be exploited as a source of natural gas (Boyer and Bai 1998). A knowledge of coal gas adsorption characteristics is important for the control of gas disasters and the exploitation of coal gas.…”

Section: Introductionmentioning

confidence: 99%

The effect of small micropores on methane adsorption of coals from Northern China

Wang

et al. 2012

Adsorption

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In this study, the effect of coal micropores on the adsorption properties, especially the Langmuir pressure (P L ), was investigated by testing 11 coal samples from Northern China. The adsorption of CO 2 at 273 K was utilized to analyze the pore size distribution. The results of these coals show that micropore volume and micropore surface area are the major factors affecting the Langmuir volume (V L ) but have weaker effects on P L . Micropore filling theory considers that some smaller micropores with an obvious overlapping adsorption force cause volume filling adsorption. These micropores firstly reach saturated adsorption, controlling the adsorption volume at the low-pressure stage and thus have a great effect on P L . Four times the methane molecular diameter, 1.5 nm, was assumed as the critical pore size with obvious overlapping adsorption force. The relationship between P L and the proportion of the pore volume below 1.5 nm to the micropore volume was investigated, and it was found that the higher the volume proportion of these small micropores was, the smaller the P L was, though two data points deviated from this trend. The reason for the anomalous coal samples could be the deviation from the assumed critical pore size of 1.5 nm for volume filling and the effects of the various micropore surface properties, which await further study.The micropore surface increases with increasing coal rank, as does V L . The proportion of pore volume below 1.5 nm increases with coal rank, and P L reverses. However, these relationships are discrete.Keywords Langmuir volume · Langmuir pressure · Micropore filling theory · Pore size distribution · Coal rank Notation V L : Langmuir volume [mL/g] P L : Langmuir pressure [MPa] P : Pressure [MPa] V : Volume [mL] ad: air dried basis daf: dry ash-free basis R o,max : Mean maximum reflectance of vitrinite [%]

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Section: Introductionmentioning

confidence: 99%

The effect of small micropores on methane adsorption of coals from Northern China

Wang

et al. 2012

Adsorption

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“…This event was speculated as a mechanical vibration caused by experimental apparatus. Hz, and energy was 700 dBm/Hz at maximum (see 6). Comprehensive analysis shows no apparent changes in the energy and frequency of MS signals.…”

Section: Frequency Spectrum Analysismentioning

confidence: 94%

“…CGOBs are controlled by multiple factors, such as stress, gas, physical, and mechanical properties of coal [5][6][7][8][9][10][11][12]. Capturing characteristic information before the disaster occurs is crucial to achieve accurate and timely warning.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Investigation on the Relationship between MS Frequency Response and Coal and Gas Outburst

Zhu

Li²,

Feng

et al. 2018

Shock and Vibration

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Microseismic (MS) frequency response is an important part of high-efficiency data mining to achieve the aim of coal and gas outburst (CGOB) early warning. Based on the variation pattern of acoustic emission (AE) signal in the coal failure process, the experimental characteristics of MS activity and typical signals CGOB were obtained in this study. First, the AE behavior of coal failure experiment was studied, and an explanation of laws was provided as follows: the fracture behavior of coal sample exhibits certain characteristics of AE response in terms of AE event count, signal amplitude, and frequency; each stage has its own physical meaning during the process of loading test. Based on these laws, CGOB experiments were carried out using a large CGOB physical simulation system with a MS monitoring system. Notching filter and wavelet packet transform technique were used in the denoising and feature extraction of six typical MS events (signals). The features of each stage, including the time-frequency domain, were extracted and quantitatively expressed. We finally arrive at the following conclusions: (1) CGOB exhibits significantly periodic characteristics, and each CGOB stage corresponds to the significant response characteristics of MS. CGOB presents varying characteristics, such as "valley-peaks-valley". (2) From the incubation stage to happen stage of outburst, the spectrum significantly moved from extremely low frequency (100-200 Hz) to high-frequency band (approach to 1600 Hz). During the residual stage, MS frequency manifested the concentration distribution (50 Hz) and offered the advantage of energy concentration. (3) The phenomenon of signal energy also shows the trend of energy transform low to high and to low modes along with the process. Signals total energy distribution (42.81%, 1,437.5-1,812.5 Hz) in the happen stage are markedly larger than those of events in incubation stage (7.01%) and residual stage (1.44%). The methodology presented in this paper for CGOB signal analysis provides a new method to obtain MS response precursor and predict CGOB disaster. This approach can be useful for rockburst anticipation and control during mining in gas and highly stressed coal mines.

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“…So here, these nine parameters involved in outburst are selected as the main parameters to construct the interaction matrix and to establish the assessment system, and the suggested rating values of these nine parameters can be seen in Iable 2. According to the constructing principIes of interaction matrix described in Section 3.1, the nine main parameters are located along the diagonal elements and the interacting actions between each two parameters are placed in the corresponding off-diagonal elements, thus a 9 x 9 square interaction matrix including 9 diagonal terms and 81 off-diagonal terms is constructed (see Figure 3) to represent the outburst system, here the interaction matrix constructing was carried out mainly based upon the knowledge obtained fram the previous studies [60][61][62][63][64][65][66] and the author's experiences . For the coding of the established interaction matrix, here we also use the ESQ coding systems suggested by Hudson [3] (see Table 3).…”

Section: Formulating the Outburst Assessmentmentioning

confidence: 99%

Development of a quantitative assessment approach for the coal and gas outbursts in coal mines using rock engineering systems

Zhou

Herrera

Hidalgo

2017

International Journal of Mining, Reclamation and Environment

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ABSTRAeTIn this study, a new approach is proposed and developed for evaluating the comprehensive outburst index (range between Oand 100), which is a quantitative assessment approach and will enable us to better understand the risk degree of coal and gas outburst in coal mines. By selecting some typical risk-free and high-risk outburst mines from China as the evaluation targets, we assessed their comprehensive outburst indexes with the developed approach. The assessment results are fully consistent with the actual situations, which indicates that our new developed approach is reliable and can be recommended for applying in more coal mines.

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Role of gas energy during coal outbursts

Cited by 100 publications

References 6 publications

The effect of small micropores on methane adsorption of coals from Northern China

The effect of small micropores on methane adsorption of coals from Northern China

An Experimental Investigation on the Relationship between MS Frequency Response and Coal and Gas Outburst

Development of a quantitative assessment approach for the coal and gas outbursts in coal mines using rock engineering systems

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