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Stress-state monitoring of coal pillars during room and ...

Stress-state monitoring of coal pillars during room and pillar extraction . Abstract . Current mining activities of the OKD mines are primarily focused on coal seams within the Karvina Formation in the Karvina sub-basin. A considerable amount of coal reserves are situated in protection pillars that lie under built-up areas. The longwall mining method is not applicable in these areas because ...

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Coal Extraction Revenue and Spending: A Comparison Among ...

generated from coal extraction and how the revenues are spent by state and local governments, and how much each state sets aside in permanent savings. Summary Findings • How states collect and spend coal revenue varies widely. We identify 15 sources of coal production revenue in the six states, including value-based and volume-based taxes and royalties paid to by federal, state, and local ...

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coal - Deutsch-Übersetzung – Linguee Wörterbuch

coal extraction n — Kohlegewinnung f ... stresses that it cannot accept such a passive role, which is contradictory to present-day requirements of transparency and accountability; considers that the legislative acts laying down the multiannual financial and technical guidelines of the Coal and Steel Research Fund should be brought under ...] the co-decision procedure, [...] whereby the ...

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Fracturing of an Euler-Bernoulli beam in coal .

The paper models the first stage of the process of pillar extraction in a coal mine. The problem of understanding how a coal mine roof collapses after secondary cutting of the supporting pillars to create small supporting snooks is considered. The fracture of the roof is considered when a set of snooks have failed and the roof must support itself between two pillars. Models that account for ...

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An explanation of large-scale coal and gas outbursts in ...

relief gas extraction, and strengthening gas extraction in ad-vance, are the main technical approaches in China (Cheng and Yu, 2007). Protecting seam exploitation is the preferred approach for coal seam group. For efficient resource utiliza-tion and atmospheric environment protection, co-extraction of coal and methane has become a widely accepted idea in recent years (Guo et al., 2012 ...

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Recent Trends in Strata Control Research For Coal Mines

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Horizontal stresses affect a number of US coal mines (Mucho, et al., 1995). To address the effects of the stress field and to control its potentially damaging effects, a number of control strategies have been developed, such as reorientation of the retreat direction, stress shadowing of the key openings, and altering the mining cut sequence ...

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Stress-state monitoring of coal pillars during room and ...

Stress-state monitoring of coal pillars during room and pillar extraction . Abstract . Current mining activities of the OKD mines are primarily focused on coal seams within the Karvina Formation in the Karvina sub-basin. A considerable amount of coal reserves are situated in protection pillars that lie under built-up areas. The longwall mining method is not applicable in these areas because ...

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The Redistribution of Stresses Around Longwall Extraction ...

Ross Seedsman, The Redistribution of Stresses Around Longwall Extraction Panels in Bedded Rock Masses, in Naj Aziz and Bob Kininmonth (eds.), Proceedings of the 2018 Coal Operators' Conference, Mining Engineering, University of Wollongong, 18-20 February 2019 https://ro.uow.edu.au/coal/691 Research Online is the open access institutional repository for the University of Wollongong. For .

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MISG 2011, Problem 1: Coal Mine pillar extraction

stress Group 1 Coal Mine pillar extraction January 14, 2011 15 / 30. Buckling of a Strut Buckling of a Strut v p p x y • Two equations for the bending moment at point x along the strut EI d2v dx2 = M(x), M(x) = −pv(x). (18) • These equations gives d2v dx2 + p EI v(x) = 0. (19) • Solving (19) with the corresponding boundary conditions v(0) = 0, v(L) = 0, gives v(x) = Asin(nπ L x), n ...

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Strata Control | Introduction | underground COAL

In order to analyse strata reactions, properties such as strength (tensile and compressive), modulus of elasticity, Poisson's ratio, etc are required, as well as details of the likely stress fields to which they will be subjected. If these are not known or cannot be measured it will be necessary to assume values with excessively conservative designs likely to result.

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PARAMETRIC STABILITY ANALYSIS OF ROOM AND PILLAR .

The same value can be obtained through extraction ratio: ( ) ( ) MPa Table 2 summarizes the calculated and predicted (e.g., from numerical modelling) pillar stress. The simulation result depicts the maximum pillar stress at various K-values is shown in Figure 6 below. Fig. 6. Maximum pillar stress at various K-values Table 2. Summary of the calculated and predicted pillar stress at various K ...

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EVALUATION OF UNDERGROUND COAL PILLAR DESIGN

Mining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or (coal) seam. Mining involves different processes like prospecting for ore bodies, analysing the feasibility of extraction, profitability of the operation, extraction of the desired materials. One of such methods is the Bord and Pillar method of mining which is one of ...

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Toward Pillar Design to Prevent Collapse of Room-and ...

extraction ratio will put pillar stress close to peak strength and provide ample expansion room for the failed pillar material. (2) Width-height ratios of pillars are always less than 3 for coal mine failures, usually much less than 1 in metal-mine failures, and less than about 2 for nonmetal mine failures. A low width-height ratio ensures that the failed pillar material can easily expand into ...

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SiOtong

Figure 10.2 shows the observing borehole locations and layout in Xingtai coal mine. In-situ stresses in this area were: V v = 7.4 MPa, V h = 4.5 MPa. The roadway in Fig. 10.2 was located 36 m below the mining face and four boreholes were drilled at different angles. The water injection instrument described in Fig. 10.1 was applied to measure the flowrate of water injection pre- and post-mining ...

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House panel suggests coal extraction from .

24.06.2009 · bdnews24, DHAKA A parliamentary watchdog, Estimate Committee, has suggested immediate extraction of coal from the five mines including the much-talked about Phulbari coal field. But the committee, which makes estimates on public affairs, made no recommendations on the mining methods-open-pit or underground. "The committee has recommended that coal from our five mines .

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ACARP Reports for Category

Coal Extraction Drilling & Blasting Environment General Geology Highwall Mining ... Self Heating of Spoil Piles from Open Cut Coal Mines. 1301-C1301 Stress Control Methods for Optimised Development... Stress Control Methods for Optimised Development and Extraction Operations . 0033-C1356 Commissioned Report: Australian Thermal Coals... Commissioned Report: Australian Thermal Coals .

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In‐site investigation of regional outburst .

In this study, based on zonal disintegration characteristics of deep surrounding rock, a regional strip outburst prevention method, called strip stress relief combined with gas extraction through stress‐relief floor roadway, was proposed, and relevant in‐site investigations were carried out in the Qujiang coal mine in China. Our results show that the zonal disintegration phenomenon occurs ...

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Depillaring: Arrangement, Precautions and Pillar ...

During extraction of coal a rib about 1 metre thick is left against the goaf. When all the slices are removed, and the area is to be abandoned, the rib coal is "robbed" to the maximum extent possible. When no more coal is extractable from the stooks, without endangering safety, props and roof supports are withdrawn and the area is then abandoned. Chocks are erected at goaf edges and the ...

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Coal mining in Brazil - Wikipedia

Coal mining in Brazil is the country's largest source of non-renewable energy, and is an important part of Brazil's energy economy.Brazil is the tenth largest energy consumer and the third largest in the Western Hemisphere, Coal accounts for approximately 5.8 percent of the country's total primary energy supply.

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Hydraulic flushing in soft coal sublayer: Gas .

After hydraulic flushing in the soft sublayer, stress‐unloading and plastic failure could be achieved in the overlying and underlying hard coal masses, which significantly improves their gas extraction condition. Moreover, stress concentration occurs in the soft sublayer; thus, its permeability decreases notably. Under this special gas extraction condition, interlayer gas flow is the main ...

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In situ identification of high vertical stress areas .

01.09.2015 · Before coal extraction, this in situ panel is an island panel which the largest principal stress may be relieved because of previous mined out voids. Therefore, the vertical stress of its overlying load became the dominant stress component. Because of the relief of maximum horizontal stress on the main roof and coal bed, this small scale graben is extended along the E–W direction. .

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