Applied sciences

Archives of Mining Sciences

Content

Archives of Mining Sciences | 2018 | vol. 63 | No 3 |

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Abstract

This paper describes the concept of controlling the advancement speed of the shearer, the objective of which is to eliminate switching the devices off to the devices in the longwall and in the adjacent galleries. This is connected with the threshold limit value of 2% for the methane concentration in the air stream flowing out from the longwall heading, or 1% methane in the air flowing to the longwall. Equations were formulated which represent the emission of methane from the mined body of coal in the longwall and from the winnings on the conveyors in order to develop the numerical procedures enabling a computer simulation of the mining process with a longwall shearer and haulage of the winnings. The distribution model of air, methane and firedamp, and the model of the goaf and a methanometry method which already exist in the Ventgraph-Plus programme, and the model of the methane emission from the mined longwall body of coal, together with the model of the methane emission from the winnings on conveyors and the model of the logic circuit to calculate the required advancement speed of the shearer together all form a set that enables simulations of the control used for a longwall shearer in the mining process. This simulation provides a means for making a comparison of the output of the mining in the case of work using a control system for the speed advancement of the shearer and the mining performance without this circuit in a situation when switching the devices off occurs as a consequence of exceeding the 2% threshold limit value of the methane concentration. The algorithm to control a shearer developed for a computer simulation considers a simpler case, where the logic circuit only employs the methane concentration signal from a methane detector situated in the longwall gallery close to the longwall outlet.
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Authors and Affiliations

Wacław Dziurzyński
Andrzej Krach
Teresa Pałka
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Abstract

In view of the permanent increase of the municipal solid waste incineration (MSWI) residues amount, the numerous attempts to find a way of their recovery have been undertaken. In this paper the idea of the recovery of the MSWI residues in Kłodawa salt mine is presented. The idea is to fill the waste in underground workings, close and/or backfill the underground excavations with self-solidifying mixture prepared on the basis of MSWI grained solid residues. Two techniques are proposed: 1) hydraulic backfill technique (HBT) where the mixture is prepared in the surface installation and pumped down into the underground workings through shaft and the pipelines and 2) dry waste technique (DWT), where dry grained waste is dropped into the mine by pneumatic pipeline transport, then supplied to the underground mixture-preparing- installation and pumped as a thin liquid or paste into the selected workings. The description of the technology is preceded by general characteristic of the hardening backfill in underground mines and by characteristic of MSWI residues, drafted on the basis of the literature review.
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Authors and Affiliations

Waldemar Korzeniowski
Krzysztof Skrzypkowski
Katarzyna Poborska-Młynarska
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Abstract

The article contains considerations on possible actions directed at increasing productivity of hard coal mining industry. It is necessary to improve the state of the industry, and ensure its survival. Basic definitions and measures concerning productivity and management were presented to illustrate examples referring to a mining enterprise. Then, basing on organizing, one of the management functions, the issue of productivity in a mining enterprise and its influence on improving effectiveness of operational management, was analysed. An assumption was presented that solutions concerning identification of sources and volume of costs, hitherto existing in mining enterprises, ought to be complemented with the planning function following process approach. It can be the starting point for decisions of economic feasibility of given deposits, seams or parts of them, before mining operations start, and to control incurred costs in process approach. The article is summed up with a process algorithm of cost management.
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Authors and Affiliations

Stanisław Prusek
Marian Turek
Józef Dubiński
Izabela Jonek-Kowalska
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Abstract

The brake linkage of a hoisting machine is a very important component determining the safety of the hoisting machine’s entire braking system. It is subject to weekly inspections. However, an efficiency test of brake performance is carried out every 6 months. Once every 3 years, a test must be carried out by an appraiser who pays particular attention to the executive and control components of the brakes as well as the strain - brake system and brake release components. The legal provisions regulating the testing of braking system linkages are not precise. So far, the control has been based on random measurement of strains using electrical resistance strain gauges stuck to the surface of the linkage. A new method for measuring the strains of the linkage has been proposed in the work. It is based on fibre optic strain sensors with Fibre Bragg Gratings (FBG). They are mounted using specially designed and tested holders for mounting on the brake linkage. They provide quick assembly and the measurement of strain in the direction parallel to the axis of the linkage. The structure of the holder also allows for the measurement in 4 positions turned every 90 relative to one another. Such a measurement enables a comprehensive analysis of strains and stresses in the brake linkage. In the work, it was shown that there is a complex state of strain and stress in the brake linkage. The previous procedures for linkage testing are inadequate in relation to this condition. An experimental and numerical method was proposed to assess the state of linkage stress. It should constitute the basis for the decision of the appraiser to allow the linkage for further use. The method proposed in the work also allows for continuous measurements of linkage strains as well as dynamic braking tests.
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Authors and Affiliations

Janusz Juraszek
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Abstract

The technology for gob-side entry retaining in steep coal seams is still in the development stage. The analysis results of the caving structure of main roof, low influence of gateway’s stability because of long filling distance and weak dynamic effect of the gateway, and the low stress redistribution environment indicate that using this technology in steep coal seams has significant advantages. Moreover, to reinforce the waste rock and the soft floor and to better guard against the impact of the waste rock during natural filling, a rock blocking device and grouting reinforcement method were invented, and theoretical calculations result show that the blocking device has high safety factor. In addition, we also developed a set of hydraulic support devices for use in the strengthening support zone. Furthermore, because the retaining gateway was a systematic project, the selection of the size and shape of the gateway cross section and its support method during the initial driving stage is a key step. Thus, first, a section the size of bottom width and roof height of a new gateway was determined to meet any related requirements. Then, according to the cross sections of 75 statistical gateways and the support technique, it chosen a trapezoidal cross section when the dip of the coal seam is 35° < α ≤ 45°, a special and an inclined arch cross section when 45° < α ≤ 55°. Eventually, a support system of bolts and cables combined with steel mesh and steel belts was provided. The support system used optimized material and improved parameters, can enhanced the self-bearing ability of the surrounding coal and rock masses.
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Authors and Affiliations

Hongyun Yang
Shugang Cao
Guisong Zhou
Yuan Zhao
Guodong Li
Yong Li
Yingchong Fan
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Abstract

In the process of coal extraction, a fractured zone is developed in the overburden above the goaf. If the fractured zone is connected with an aquifer, then water inrush may occur. Hence, research and analysis of the height of overburden fractured zone (HOFZ) are of considerable significance. This study focuses on the HOFZ determination in deep coal mining. First, general deformation failure characteristics of overburden were discussed. Second, a new method, numerical simulation by orthogonal design(NSOD), have been proposed to determinate the HOFZ in deep coal mining. Third, the validity of NSOD is verified in the practical application, compared with empiric al formula in Chinese Regulations and in-situ test. These three methods were applied to determine the HOFZ of working face No. 111303 in No. 5 coal mine. The pre dicted HOFZ of NSOD is found to be similar to the result of the in-situ test (8.9% relative error), whereas the HOFZ calculated by the empirical formula has extremely large error (25.7% relative error). Results show that the NSOD can reliably predict the HOFZ in deep coal mining and reduce time and expenses required for in-situ test.
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Authors and Affiliations

Han Yangchun
Cheng Jiulong
Huang Qisong
Zou D.H. Steve
Zhou Jin
Huang Shaohua
Long Yun
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Abstract

The paper presents results of research on cobalt and nickel ions removal from monocomponent solutions using Purolite ion exchange resins. It has been shown that C 160 ion exchange resin has the best sorption properties for both ions (Qe – 72.5 mg Co/g and 88.2 mg Ni/g). Regeneration process of this ion exchanger has high efficiency, achieving about 93% for cobalt ions and about 84% in case of nickel ions. It has been shown that the use of ion exchange method with suitable ion exchange resins guarantees effective removal of cobalt and nickel ions from solutions with very high concentrations corresponding to contents of these metals in industrial wastewaters (e.g. galvanic). In case of C 160 ion exchange resin, after the sorption process is carried out in one 50 minute cycle, the cobalt concentration decreased from about 30 000 mg/L to about 9 500 mg/L (approx. 68%), whereas nickel concentration reached about 6 300 mg/L (approx. 79%). Studied chelating resins don’t have such high sorption capacities. In their case, it is required to convert cobalt and nickel ions into complex forms. The kinetics of studied processes were described by pseudo-second order equations.
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Authors and Affiliations

Agnieszka Monika Bożęcka
Stanisława Sanak-Rydlewska
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Abstract

For most precious metal mines, cemented tailings backfill slurry (CTBS) with different cement-sand ratio and solid concentration are transported into the gobs to keep the stability of the stope and mitigate environmental pollution by mine tailing. However, transporting several kinds of CTBS through the same pipeline will increase the risk of pipe plugging. Therefore, the joint impacts of cement-sand ratio and solid concentration on the rheological characteristics of CTBS need a more in-depth study. Based on the experiments of physical and mechanical parameters of fresh slurry, the loss of pumping pressure while transporting CTBS with different cement-sand ratio, flux and solid mass concentration were measured using pumping looping pipe experiments to investigate the joint impacts of cement-sand ratio and solid concentration on the rheological characteristics of CTBS. Meanwhile, the effect of different stopped pumping time on blockage accident was revealed and discussed by the restarting pumping experiments. Furthermore, Fluent software was applied to calculate the pressure loss and velocity distribution in the pipeline to further analysis experimental results. The overall trends of the simulation results were good agreement with the experiment results. Then, the numerical model of the pipeline in the Sanshandao gold mine was conducted to simulate the characteristics of CTBS pipeline transportation. The results show that the pumping pressure of the delivery pump can meet the transportation requirements when there is no blockage accident. This can provide a theoretical method for the parameters optimizing in the pipeline transportation system.
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Authors and Affiliations

Xiao Siyou
Liu Zhixiang
Jiang Yuanjun
Li Cheng
Sun Changning
Su Lijun
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Abstract

This article presents the use of a multi-criterion Analytic Hierarchy Process (AHP) method to assess geological and mining condition nuisance in longwall mining operations in selected coal mines in Poland. For this purpose, a methodology has been developed which was used to calculate the operational nuisance indicator (WUe) in relation to the cost of mining coal in individual longwalls. Components of the aggregate operational nuisance indicator include four sub-indicators: the natural hazards indicator (UZN), an indicator describing the seam parameters (UPZ), an indicator describing the technical parameters (UT) and an environmental impact indicator (UŚ). In total, the impact of 28 different criteria, which formed particular components of the nuisance indicators were analysed. In total 471 longwalls in 11 coal mines were analysed, including 277 longwalls that were mined in the period of 2011 to 2016 and 194 longwalls scheduled for exploitation in the years 2017 to 2021. Correlation analysis was used to evaluate the relationships between nuisance and the operating costs of longwalls. The analysis revealed a strong correlation between the level of nuisance and the operating costs of the longwalls under study. The design of the longwall schedule should therefore also take into account the nuisance arising from the geological and mining conditions of the operations. Selective operations management allows for the optimization of costs for mining in underground mines using the longwall system. This knowledge can also be used to reduce the total operating costs of mines as a result of abandoning the mining operations in entire longwalls or portions of longwalls that may be permanently unprofitable. Currently, underground mines do not employ this optimization method, which even more emphasizes the need for popularizing this approach.
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Authors and Affiliations

Eugeniusz Jacek Sobczyk
Michał Kopacz
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Abstract

Recalling the body of experience gathered in the collieries of the Upper Silesian Coal Basin, the increased risk of seismicity and rockburst occurrences in confined conditions including the exploitation of remnants were identified. This study investigates geomechanical aspects of longwall mining in the areas affected by old excavations aimed at relaxation of a multi-bed deposits within a thick coal seam or a group of seams. It is assumed that high-energy seismicity is another factor determining the rockburst hazard alongside the state of stress. A case study is recalled, describing a colliery where mining-induced seismic activity of a de-stressed coal seam remained at the level comparable to or higher than it was experienced in the de-stressed seam operations. An analytical model was used to study the stress state and potential loss of structural continuity of an undisturbed rock body surrounding the longwall panel being mined beneath or over the abandoned workings. Recalling the developed model of the system involving nonlinear functions demonstrating the existence of abandoned mine workings within the rock strata, computer simulations were performed to evaluate the rockburst hazards along the face area. Discussions of results are based on observations of immediate roof convergence and the vertical stress concentration factor at the longwall face zone. Computational data of the modelled mining situations demonstrates that despite using the de-stressing method of mining, the occurrence of events impacting on mine working beneath and over abandoned workings cannot be precluded. Here the scale of rockburst hazards is determined by local mining and geological conditions, such as the type and extent of abandoned workings, their age and vertical distance between them and the coal seam currently mined.
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Authors and Affiliations

Zbigniew Burtan
Andrzej Zorychta
Dariusz Chlebowski
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Abstract

Households are the most significant group of consumers in the municipal and household sector in Poland. In 2010-2016, households consumed annually from 8.9 to 10.8 million Mg of coal (77-81% share in this sector). As of the beginning of 2018, seven voivodships in Poland have already introduced anti-smog resolutions, one has its draft, three are considering introduction of such resolutions. In the face of introducing anti-smog resolutions, the analysis of coal consumption by households was conducted for a situation where anti-smog resolutions will be introduced in all voivodships in Poland. A forecast of hard coal consumption by Polish households in 2017-2030 was presented in the article. Two scenarios differentiated in terms of calorific value of coal were taken into account: (i) concerned coal with a calorific value of 24 MJ/kg (min. Q for eco-pea coal: grain size 5.0-31.5 mm), (ii) – coals with a calorific value of 26 MJ/kg (Q recommended for use by producers of class 5 boilers). In the perspective of 2030, the largest decrease in hard coal consumption can be expected (jointly) in the voivodships of Śląskie, Dolnośląskie, Opolskie and Lubuskie. Under the assumptions made, in relation to 2016, it may be reduced by half and fall from 2.8 to the level of 1.4-1.5 million Mg. The smallest decreases in consumption may occur (jointly) in the Małopolskie, Lubelskie, Podkarpackie and Świętokrzyskie voivodships – decrease by 16-22% and fall from 2.6 to approximately 1.9-2.0 million Mg. On a national scale, coal consumption may decrease from the current 10.4 (2016) to around 6.3-6.8 million Mg (a decrease of 30-35%). Despite the decrease in hard coal consumption in the 2030 perspective, one should expect an increase in demand for high quality coal dedicated to modern boilers (usually pea assortments) as well as qualified coal fuels (mainly eco-pea coal).
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Authors and Affiliations

Katarzyna Stala-Szlugaj
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Abstract

Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and subsequent fires caused by coal dust can result in significant property damage, loss of life in underground coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted research on coal dust explosions until 1996 when it was dissolved. In the following years, the American Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard test method characterizing the “explosibility” of particulate solids of combustible materials suspended in air. The research presented herein investigates the explosive characteristic of Pulverized Pittsburgh Coal dust using the ASTM E1226-12 test standard. The explosibility characteristics include: maximum explosion pressure, (Pmax); maximum rate of pressure rise, (dP/dt)max; and explosibility index, (Kst). Nine Pulverized Pittsburgh Coal dust concentrations, ranging from 30 to 1,500 g/m3, were tested in a 20-Liter Siwek Sphere. The newly recorded dust explosibility characteristics are then compared to explosibility characteristics published by the Bureau of Mines in their 20 liter vessel and procedure predating ASTM E1126-12. The information presented in this paper will allow for structures and devices to be built to protect people from the effects of coal dust explosions.
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Authors and Affiliations

Jacob Miller
Jay Schafler
Phillip Mulligan
Robert Eades
Kyle Perry
Catherine Johnson
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Abstract

The evaluation of threats connected with the presence of methane in coal seams is based on our knowledge of the total content of this gas in coal. The most important parameter determining the potential of coal seams to accumulate methane is the sorption capacity of coal a. It is heavily influenced by the degree of coalification of the coal substance, determined by the vitrinite reflectance R0 or the content of volatile matter V daf. The relationship between the degree of coalification and the sorption capacity in the area of the Upper Silesian Coal Basin (USCB) has not been thoroughly investigated, which is due to the zonation of methane accumulation in this area and the considerable changeability of methane content in various localities of the Basin. Understanding this relationship call for in-depth investigation, especially since it depends on the analyzed reflectance range. The present work attempts to explain the reasons for which the sorption capacity changes along with the degree of coalification in the area of Jastrzębie (the Zofiówka Monocline). The relationship between parameters R0 and V daf was investigated. The authors also analyzed changes of the maceral composition, real density and the micropore volume. Furthermore, coalification-dependent changes in the sorption capacity of the investigated coal seams were identified. The conducted analyses have indicated a significant role of petrographic factors in relation to the accumulation properties of the seams located in the investigated area of USCB.
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Authors and Affiliations

Katarzyna Godyń
Barbara Dutka
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Abstract

The coal exploitation in the Upper Silesia region (along the Vistula River) triggers the strata seismic activity, characterized by very high energy, which can create mining damage of the surface objects, without any noticeable damages in the underground mining structures. It is assumed that the appearance of the high energy seismic events is the result of faults’ activation in the vicinity of the mining excavation. This paper presents the analysis of a case study of one coal mine, where during exploitation of the longwall panel no. 729, the high energy seismic events occurred in the faulty neighborhood. The authors had analyzed the cause of the presented seismic events, described the methods of energy decreasing and applied methods of prevention in the selected mining region. The analysis concluded that the cause of the high energy seismic events, during the exploitation of the longwall panel no. 729 was the rapid displacements on the fault surface. The fault’s movements arose in the overburden, about 250 m above the excavated longwall panel, and they were strictly connected to the cracking of the thick sandstone layer.
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Authors and Affiliations

Krzysztof Tajduś
Antoni Tajduś
Marek Cała
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Abstract

Geodesic measurements of mining area deformations indicate that their description fails to be regular, as opposed to what the predictions based on the relationships of the geometric-integral theory suggest. The Knothe theory, most commonly applied in that case, considers such parameters as the exploitation coefficient a and the angle of the main influences range tgβ, describing the geomechanical properties of the medium, as well as the mining conditions. The study shows that the values of the parameters a = 0.8 and tgβ = 2.0, most commonly adopted for the prediction of surface deformation, are not entirely adequate in describing each and every mining situation in the analysed rock mass. Therefore, the paper aims to propose methodology for determining the value of exploitation coefficient a, which allows to predict the values of surface subsidence caused by underground coal mining with roof caving, depending on geological and mining conditions. The characteristics of the analysed areas show that the following factors affect surface subsidence: thickness of overburden, type of overburden strata, type of Carboniferous strata, rock mass disturbance and depth of exploitation. These factors may allow to determine the exploitation coefficient a, used in the Knothe theory for surface deformation prediction.
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Authors and Affiliations

Katarzyna Kryzia
Tadeusz Majcherczyk
Zbigniew Niedbalski
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Abstract

One of the main purpose of accurate blasting in open pit mining is to achieve optimum rock fragmentation. The degree of rock fragmentation plays a significant role in order to control and minimise the overall production cost including loading, hauling and crushing. In the present paper, the application of a Number-Size (N-S) fractal model is intended to classify the blast fragmentation size in the Jalal-Abad iron mine, SW Iran, using GoldSize image analysis software for four blasting with the obtained result being compared with Kuz-Ram curves. To do this, the fractal dimensions via N-S log-log plots were generated based on the output of the GoldSize software. The results indicated that the fragmented rocks have a multifractal nature with four/five different fragmented populations in terms of size namely; the fine rocks with the size of less than 16 cm, Mean-fragment values between 16 and 45 cm, In-range between 45 and 70 cm and finally, oversize larger than 70 cm.
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Authors and Affiliations

Nikzad Mohammadreza
Ahmad Asadi
Ahangaran Daryoush Kaveh
Yasrebi Amir Bijan
Andy Wetherelt
Afzal Peyman

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Archives of Mining Sciences (AMS) is concerned with original research, new developments and case studies in all fields of mining sciences which include:

- mining technologies,

- stability of mine workings,

- rock mechanics,

- geotechnical engineering and tunnelling,

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- mining and engineering geology,

- mining geophysics,

- mining geodesy

- ventilation systems,

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Papers are welcomed on all relevant topics and especially on theoretical developments, analytical methods, numerical methods, rock testing, site investigation, and case studies.

AMS publishes research and review articles, technical notes.

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References

A bibliography without numbering, arranged alphabetically according to the author’s last name, should include all positions referring in the text. In case of more than one article from the same year, the articles should be differentiated as follows: 1985a, 1985b, etc. The following order is required: last name and initials of all co-authors, year, title, type of publications, (journal, conference material, collection of monograph articles, unpublished texts) with the page numbers used.

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Name(s) of the author(s) should be provided in parentheses. e.g.: (Brandt, 1993), (Crosdale & Beamish, 1994). (Dziurzynski et al., 1990) in the case of one, two or more than two authors, respectively. If the name(s) of the author(s) is included in the text, then the reference should be cited as follows e.g.: „According to Brandt (1993)...”

Example of bibliography.

Brandt, J., 1993. Neuere Erkentnisse auf dem Gebiet der Gasausbruchprognose. Glückauf Forschungshefte 54, 5, 228-233.

Crosdale, P. J., Beamish, B.B., 1994. Methane sorption studies at South Bulli (NSW) & Central (QLD) collieries using a high-pressure microbalance. 28 Newcastle Symposium on „Advances in the study of Sydney Basin”, Newcastle, NSW, Australia, 15-17 April, 118-125.

Dziurzynski, W., Trutwin W., Tracz J., 1990. Symulacja komputerowa przepływu powietrza i gazów powyrzutowych w sieci wentylacyjnej kopalni. J. Litwiniszyn (Ed.), Górotwór jako ośrodek wielofazowy; Wyrzuty skalno-gazowe. Wydawnictwo AGH, Kraków, Vol. II, 743-758.

Lama R. D., Bodziony, J., 1996. Outbursts of gas, coal and rock in underground mines. Publisher Lama & Associates, 130 Brokers Road, Mt. Pleasant, NSW 2519, Australia.

Nekrasovski, Ya. E., 1951. Razrabotka plastov podverzhennykh vnezapnym vybrosam ugla i gaza. Ugletekhizdat, Moskva.

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