Sample records for underhand longwall lful

  1. Longwall mining

    Energy Technology Data Exchange (ETDEWEB)



    As part of EIA`s program to provide information on coal, this report, Longwall-Mining, describes longwall mining and compares it with other underground mining methods. Using data from EIA and private sector surveys, the report describes major changes in the geologic, technological, and operating characteristics of longwall mining over the past decade. Most important, the report shows how these changes led to dramatic improvements in longwall mining productivity. For readers interested in the history of longwall mining and greater detail on recent developments affecting longwall mining, the report includes a bibliography.

  2. Surface Mines, Other - Longwall Mining Panels (United States)

    NSGIC Education | GIS Inventory — Coal mining has occurred in Pennsylvania for over a century. A method of coal mining known as Longwall Mining has become more prevalent in recent decades. Longwall...

  3. Longwall top coal caving. The next challenge in longwall mining?

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, P.; Kelly, M.; Poulsen, B. [CSIRO Exploration and Mining (Australia)


    This paper outlines the major challenges involved in implementing longwall top coal caving (LTCC) into Australian mines and provides a direction for tackling these issues through the use of proven scientific techniques and technological applications. Chinese knowledge and research on LTCC including ACARP project outcomes is used as a foundation for comparisons of Australian conditions and for highlighting the areas of required work for moving forward with an Australian LTCC operation. 6 refs., 10 figs., 1 tab.

  4. Longwall mining of thin seams

    Energy Technology Data Exchange (ETDEWEB)

    Curth, E A


    Thin seam operations pose a challenge to the ingenuity of mining engineers to overcome the factor of human inconvenience in the restricted environment and associated high cost production. Surprisingly, low seam longwalls in the Federal Republic of Germany in an average thickness of 35 in. and dipping less than 18/sup 0/ come close to achieving the average production rate of all German longwall operations. They are all plow faces, and a consistent production of 3300 tons per day and a productivity of 40 tons per man shift are reported from one of the thin seam longwalls. These results were attained by reliable high-capacity equipment and roof support by shields that can be collapsed to as low as 22 inches. Maximum mining height for plow operated faces lies at 31.5 inches. Technology for mechanized mining of flat lying coalbeds less than 31.5 inches in thickness without rock cutting is not available, and firmness of coal, undulation of the strata, coalbed thickness variation, and the necessity of cutting rock, particularly through faults, set limits to plow application. The in-web shearer can be used in firm coal to a minimum mining height of 40 inches, and a daily production of 1650 to 2200 tons is reported from a longwall in the Saar district of Germany equipped with such a shearer and shields. Numerous in-web shearers are employed in the United Kingdom; reports as to their success are contradictory. Also, experience in the United States, though limited, has been negative. The steady increase in output from single drum shearer faces in Pennsylvania is a remarkable achievement, and occasional record breaking peaks in production indicate the potential of such mining. Technology development for the future is discussed.

  5. Impact of longwall mining on groundwater above the longwall panel in shallow coal seams

    Directory of Open Access Journals (Sweden)

    Yang Li


    Full Text Available Since longwall mining causes subsidence through the overlying strata to the ground surface, the surface water and groundwater above the longwall panels may be affected and drained into the lower levels. Therefore, loss or interruption of streams and overburden aquifers is a common concern in coal industry. This paper analyzed the potential effects of longwall mining on subsurface water system in shallow coal seam. In order to monitor different water level fluctuations throughout the mining period, three water wells were drilled down to the proposed deformation zone above the longwall panel. A GGU-SS-FLOW3D model was used to predict water table contours for the periods of pre- and post-mining conditions. The field data from the three water wells were utilized to calibrate the model. The field test and numerical model can help to better understand the dewatering of shallow aquifers and surface waters related to ground subsidence from longwall mining in shallow coal seam.

  6. Analysis of longwall face-to-face transfers

    International Nuclear Information System (INIS)

    Patrick, C.; Topuz, E.


    A non-producing longwall costs the mine owner from $45 to over $100 per minute in lost production time. Face-to-face equipment transfers, which involve disassembling longwall equipment in a panel, transporting, and then reassembling it in a new longwall panel, are second only to system availability as a source of longwall non-productive time. This, in addition to a move cost of over $100,000, makes reduction and control of face transfer times essential. This paper will report a segment of on-going VPI research to analyze and model longwall transfers through the use of operations research techniques. The purpose is to reduce overall transfer time and the variation of transfer times among U.S. longwall operations. This research is expected to contribute to the longwall mining industry by offering an objective approach that can be used in the prediction, planning, preparation, and implementation of longwall face equipment transfers

  7. Prism adaptation of underhand throwing: rotational inertia and the primary and latent aftereffects. (United States)

    Blau, Julia J C; Stephen, Damian G; Carello, Claudia; Turvey, M T


    The effect of prism adaptation on movement is typically reduced when movement at test (with prisms removed) is different from movement at training. Previous research [J. Fernández-Ruiz, C. Hall-Haro, R. Díaz, J. Mischner, P. Vergara, J. C. Lopez-Garcia, Learning motor synergies makes use of information on muscular load, Learning & Memory 7 (2000) 193-198] suggests, however, that some adaptation is latent and only revealed through further testing in which the movement at training is fully reinstated. Movement in their training trials was throwing overhand to a vertical target with a mass attached to the arm. The critical test trials involved the same act initially without the attached mass and then with the attached mass. In replication, we studied throwing underhand to a horizontal target with left shifting prisms and a dissociation of the throwing arm's mass and moment of inertia. The two main results were that the observed latent aftereffect (a) depended on the similarity of training and test moments of inertia, and (b) combined with the primary aftereffect to yield a condition-independent sum. Discussion focused on a parallel between prism adaptation and principles governing recall highlighted in investigations of implicit memory: whether given training (study) conditions lead to good or poor persistence of adaptation (memory performance) at test depends on the conditions at test relative to the conditions at training (study).

  8. 30 CFR 75.813 - High-voltage longwalls; scope. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage longwalls; scope. 75.813 Section... AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.813 High-voltage longwalls; scope. Sections 75.814 through 75.822 of this...

  9. 30 CFR 75.215 - Longwall mining systems. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Longwall mining systems. 75.215 Section 75.215... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Roof Support § 75.215 Longwall mining systems. For each longwall mining section, the roof control plan shall specify— (a) The methods that will be used to maintain...

  10. Design of longwall mining system

    Energy Technology Data Exchange (ETDEWEB)

    Curth, E. A.


    A premining investigation includes core drill holes, seismic studies, satellite imagery and, where the underground is accessible, bearing strength tests of roof and floor, and residual stress determination. Longwall retreat is the preferred method in the USA. Exceptions are few. The objective of panel design is to maintain ground stability and to provide optimum resource recovery with the most cost-effective panel configuration. Environmental considerations, such as surface utilization, hydrology, oil and gas wells, affect panel location and layout. Roof support selection criteria stem from premining data. Prototype roof supports must satisfy an intensive testing program. Mining equipment, such as cutter loaders, face conveyors and stage loaders, is designed to match the production goal and anticipated face conditions. Coal clearance, power supply, men and supply transportation, communications, and equipment maintenance programs must be commensurate with the extraction potential. Face lighting must comply with mandatory standards. Operational monitoring and analysis include operational data extracted and summarized from shift and monthly records, and from ground control and subsidence observations.

  11. Top coal caving longwall maximizes thick seam recovery

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, G.; Sobey,. G.; Clarke, T.


    Austar's longwall system offers opportunities in coal seams thicker than 4.5 meters. The Longwall Top Coal Caving (LTCC) method was recently launched in Australia at Yancoal Australia's Austar mines in Hunter Valley, although 90 such longwalls already operate in China. The article describes the method and its installation at Austar. In September 2006 the LTCC face commenced production. The operation is described and measures to prevent spontaneous combustion are outlined. Future work on the longwall is mentioned. 11 figs.

  12. Effects of Longwall subsidence on escarpment stability

    International Nuclear Information System (INIS)

    Shea-Albin, V.R.


    Increasing pressure from State and Federal agencies to mitigate mining-induced subsidence damage to overlying structures has presented a unique problem to the coal industry in the western United States. Because sandstone escarpments are an environmental issue, millions of tons of coal reserves that underlie these escarpments risk being classified as unminable by regulatory agencies. At this time, the effect of subsidence on escarpments has not been well documented or characterized. The Bureau of Mines is using numerical modeling techniques to analyze escarpment response to longwall mining. Two- and three-dimensional finite element models have been constructed for a study area near Price, Utah, where longwall panels were mined near an escarpment. This paper includes preliminary results showing that the pattern of subsidence surrounding the escarpment can be simulated through numerical modeling

  13. Special considerations for vibration analysis on longwall equipment

    Energy Technology Data Exchange (ETDEWEB)

    Towles, B.


    West Elk Mine has included vibration analysis as a part of the longwall maintenance program since 1993. Longwall equipment presents several special problems which are not common to most vibration analysis applications: (1) Heavy construction of equipment damps some signals making machine condition determinations difficult, and (2) Complexity of longwall equipment; (3) Difficulty in isolating spectrum frequencies to individual machinery components; (4) Flexing of equipment frames and housings due to longwall face advance affects vibration spectrums; (5) Difficulty of obtaining necessary information on internal machinery components from longwall equipment suppliers; (6) Permissibility of data collection instruments. In spite of these difficulties, West Elk has had positive results in preventing catastrophic failures, predicting life expectancy of failing components, making general machinery improvements in cooperation with manufacturers and determining rebuild quality.

  14. Numerical modeling for longwall pillar design: a case study from a typical longwall panel in China (United States)

    Zhang, Guangchao; Liang, Saijiang; Tan, Yunliang; Xie, Fuxing; Chen, Shaojie; Jia, Hongguo


    This paper presents a new numerical modeling procedure and design principle for longwall pillar design with the assistance of numerical simulation of FLAC3D. A coal mine located in Yanzhou city, Shandong Province, China, was selected for this case study. A meticulously validated numerical model was developed to investigate the stress changes across the longwall pillar with various sizes. In order to improve the reliability of the numerical modeling, a calibration procedure is undertaken to match the Salamon and Munro pillar strength formula for the coal pillar, while a similar calibration procedure is used to estimate the stress-strain response of a gob. The model results demonstrated that when the coal pillar width was 7-8 m, most of the vertical load was carried by the panel rib, whilst the gateroad was overall in a relatively low stress environment and could keep its stability with proper supports. Thus, the rational longwall pillar width was set as 8 m and the field monitoring results confirmed the feasibility of this pillar size. The proposed numerical simulation procedure and design principle presented in this study could be a viable alternative approach for longwall pillar design for other similar projects.

  15. Stress analysis of longwall top coal caving

    Energy Technology Data Exchange (ETDEWEB)

    Alehossein, H.; Poulsen, B.A. [CSIRO Exploration & Mining, Brisbane, Qld. (Australia)


    Longwall top coal caving (LTCC) is a relatively new method of mining thick coal seams that is currently achieving high productivity and efficiency. The technique is similar to traditional longwall mining in that a cutting head slices coal from the lower section of the coal seam onto a conveyor belt installed in front of the hydraulic support near the cutting face. In modern LTCC an additional rear conveyor belt is located behind the support, to which the flow of the caved coal from the upper part of the seam can be controlled by a moveable flipper attached to the canopy of the support. The mining method relies on the fracturing of the top coal by the front abutment pressure to achieve satisfactory caving into the rear conveyor. This paper develops a yield and caveability criterion based on in situ conditions in the top coal in advance of the mining face (yield) and behind the supports (caveability). Yielding and caving effects are combined into one single number called caving number (CN), which is the multiplication result of caving factor (CF) and yield factor (YF). Analytical derivations are based on in situ stress conditions, Mohr-Coulomb and/or Hoek-Brown rock failure criteria and an on-associated elastoplastic strain softening material behaviour. The yield and caveability criteria are in agreement with results from both numerical studies and mine data. The caving number is normalised to mining conditions of a reference Chinese mine (LMX mine) and is used to assess LTCC performance at fourteen other Chinese working longwalls that have had varying success with the LTCC technology. As a predictive model, results of this analytical/numerical study are useful to assess the potential success of caving in new LTCC operations and in different mining conditions.

  16. Evaluate fundamental approaches to longwall dust control. Phase III report

    Energy Technology Data Exchange (ETDEWEB)

    Babbitt, C.; Bartlett, P.; Kelly, J.; Ludlow, J.; Mangolds, A.; Rajan, S.; Ruggieri, S.; Varga, E.


    The overall objective of the contract is to evaluate the effectiveness of available dust control technology for double-drum shearer longwall sections in a coordinated, systematic program at a few longwall test sections and to make the results available to the entire coal mining industry. This program is investigating nine different dust control techniques. These nine subprograms encompass a broad range of dust control measures ranging from administrative controls to new hardware. They span not only presently employed methods but also those recently adopted in the United States and those proposed for the future. This report documents the Phase III effort on each of the subprograms. For clarity, the report is divided in sections by subprogram as follows: Section 2, Subprogram A - passive barriers/spray air movers for dust control; Section 3, Subprogram B - practical aspects of deep cutting; Section 4, Subprogram C - stage loader dust control; Section 5, Subprogram D - longwall automation technology; Section 6, Subprogram E - longwall application of ventilation curtains; Section 7, Subprogram F - reversed drum rotation; Section 8, Subprogram G - reduction of shield generated dust; Section 9, Subprogram H - air canopies for longwalls; and Section 10, Subprogram I - mining practices. 43 figures, 11 tables.

  17. Subsidence interactions related to longwall mining of the upper and lower Kittanning coalbeds

    International Nuclear Information System (INIS)

    Chekan, G.J.; Bauer, E.R.


    The U.S. Bureau of Mines, in an effort to improve coal conservation and utilization, is currently investigating longwall panel layouts to maximize coal recovery and minimize interactive problems in multiple-seam operations. When longwalling coalbeds in ascending order, subsidence of the overlying strata is an interactive problem that may influence the stability of the gate roads and longwall panels in the upper mine. To control interactive problems, two fundamental design approaches involved either offsetting of superimposing the gate roads and longwall panels. This paper involves analytical predictions and underground observations of longwall development ground control problems at a south-central Pennsylvania coal mine where gate road superpositioning was practiced

  18. A fuzzy approach to selecting roof supports in longwall mining

    Directory of Open Access Journals (Sweden)

    Yetkin, M. E.


    Full Text Available As a decision-making problem, selecting proper machines and equipment plays a key role for mining sites and companies. Many factors affect this decision, and values belonging to these factors can be expressed numerically and/or non-numerically. In order to make the most appropriate decision, engineers must carry out an evaluation process that comprises all criteria that might affect decision-making. To achieve this, multi-criteria decision-making tools are used. As a result of technological developments, coal outputs in longwall mining have risen tremendously over the last decades, and longwall mechanisation has become unavoidable. The significance of powered roof supports in particular increases day- by-day, since the rate of roof support has to be in accordance with the rate of face advance in longwalls. In this study, an integrated fuzzy analytic hierarchy process and fuzzy goal programming model is used to select the most suitable powered roof supports. The procedure is applied to a real-life underground coal mine that is operated using the longwall method. Seven alternative powered roof supports are compared with each other, taking a total of 24 decision criteria under four main topics into account. In conclusion, the most suitable roof supports for the mine under study are determined and recommended to the decision-makers of the system.

  19. Development of subsidence profile functions for longwall mining associated with weak floor strata considering time effects

    International Nuclear Information System (INIS)

    Yu, Z.; Chugh, Y.P.; Yang, G.


    Subsidence profile functions for longwall mining in the Illinois Coal Basin were developed for both the headgate and tailgate sides based on field observations of surface subsidence over several longwall panels. One function was applied to predict the subsidence profile for a longwall panel in another Illinois Coal Basin mine, where a good correlation between the predicted and measured results was achieved. Attempts were also made to develop subsidence profile functions including time effect. 4 refs., 9 figs., 1 tab

  20. Subsidence resulting from multiple-seam longwall mining in the western United States

    International Nuclear Information System (INIS)

    Dyni, R.C.


    This paper details the investigation of multiple-seam longwall subsidence conducted by the U.S. Bureau of Mines from 1978 to 1989. A field investigation monitored ground surface movements over four upper seam longwall panels and six lower seam panels. The characteristics of the subsidence occurring as a result of mining these panels are examined: in particular, the angle of draw, subsidence development, total magnitude and areal extent, and critical width are evaluated and discussed. comparisons are also made between the characteristics of multiple-seam longwall subsidence and single-seam longwall subsidence that occurred at the same site

  1. Algorithm of probabilistic assessment of fully-mechanized longwall downtime (United States)

    Domrachev, A. N.; Rib, S. V.; Govorukhin, Yu M.; Krivopalov, V. G.


    The problem of increasing the load on a long fully-mechanized longwall has several aspects, one of which is the improvement of efficiency in using available stoping equipment due to the increase in coefficient of the machine operating time of a shearer and other mining machines that form an integral part of the longwall set of equipment. The task of predicting the reliability indicators of stoping equipment is solved by the statistical evaluation of parameters of downtime exponential distribution and failure recovery. It is more difficult to solve the problems of downtime accounting in case of accidents in the face workings and, despite the statistical data on accidents in mine workings, no solution has been found to date. The authors have proposed a variant of probability assessment of workings caving using Poisson distribution and the duration of their restoration using normal distribution. The above results confirm the possibility of implementing the approach proposed by the authors.

  2. How productive are Australia's longwalls?

    Energy Technology Data Exchange (ETDEWEB)

    Baird, G. [McAlpine-B (Australia)


    The Australian longwall industry is experiencing record growth in longwall output. But just how productive are Australian mines? One way of finding out is to compare the productivity of Australian mines with that of US mines. A 'US composite' mine (based on 19 mines) was compared with a five-day and a seven-day 'Australian composite' mine (based on 17 mines). In 2000, the US composite produced 4.8 Mt compared to 3.6 Mt and 4.5 Mt for Australian 5-day and 7-day composites respectively. An attempt is made to analyse reasons for these productivity gaps. The author concludes that Australian mines must achieve best practice utilization to match productivity of US mines. One step in achieving this is the successful implementation of techniques such as Total Quality Management (TQM), Reliability Centred Maintenance (RCM), Six Sixma, etc. 3 tabs.

  3. Application of longwall top coal caving to Australian operations

    Energy Technology Data Exchange (ETDEWEB)

    Y. Cai; Bruce Hebblewhite; U. Onder; B. Xu; Mick Kelly; Barry Wright [CSIRO Exploration & Mining (Australia)


    The aim of this project was to provide the Australian underground coal mining industry with an up to date, state of the art summary of the Longwall Top Coal Caving (LTCC) mining system and its potential for application in Australia. This project final report addresses the following issues: Update of previously developed Australian thick seam database. Provision of a literature review on the method and a critical evaluation of current published information on both the technology and the operational performance data for the method. The critical issues associated with the method, identified through a risk assessment approach, are highlighted and evaluated in terms of defining the problems and evaluating appropriate elimination or control strategies. The relative economics of an LTCC operation compared to a 4.5m high single pass longwall are developed through an operational and economic model. In terms of equipment innovation, the more recent Chinese developments have relocated the top coal draw points to the rear of the longwall supports. The Chinese equipment has a pivoting supplementary goaf or tail canopy behind the support. Beneath this is a retractable second AFC. With the rear AFC extended and the rear canopy lowered/retracted, caved top coal can be loaded onto the rear AFC, whilst production continues conventionally in front of the supports. In the retracted rear AFC position with the rear canopy raised, the supports and face operation can function conventionally. The Chinese industry reports averages of 15,000 to 20,000 tpd from an LTCC face; up to 75% recovery of 8m+ thick seams using a 3m operating height longwall; and +5 MTPA face production. There are now over 70 LTCC faces in China. A new semi-automated 300m long LTCC face installed at the Xinglongzhuang Colliery. This is heading towards producing 7 MTPA in 2002/2003.

  4. Experimental study on foam coverage on simulated longwall roof (United States)

    Reed, W.R.; Zheng, Y.; Klima, S.; Shahan, M.R.; Beck, T.W.


    Testing was conducted to determine the ability of foam to maintain roof coverage in a simulated longwall mining environment. Approximately 27 percent of respirable coal mine dust can be attributed to longwall shield movement, and developing controls for this dust source has been difficult. The application of foam is a possible dust control method for this source. Laboratory testing of two foam agents was conducted to determine the ability of the foam to adhere to a simulated longwall face roof surface. Two different foam generation methods were used: compressed air and blower air. Using a new imaging technology, image processing and analysis utilizing ImageJ software produced quantifiable results of foam roof coverage. For compressed air foam in 3.3 m/s (650 fpm) ventilation, 98 percent of agent A was intact while 95 percent of agent B was intact on the roof at three minutes after application. At 30 minutes after application, 94 percent of agent A was intact while only 20 percent of agent B remained. For blower air in 3.3 m/s (650 fpm) ventilation, the results were dependent upon nozzle type. Three different nozzles were tested. At 30 min after application, 74 to 92 percent of foam agent A remained, while 3 to 50 percent of foam agent B remained. Compressed air foam seems to remain intact for longer durations and is easier to apply than blower air foam. However, more water drained from the foam when using compressed air foam, which demonstrates that blower air foam retains more water at the roof surface. Agent A seemed to be the better performer as far as roof application is concerned. This testing demonstrates that roof application of foam is feasible and is able to withstand a typical face ventilation velocity, establishing this technique’s potential for longwall shield dust control. PMID:29563765

  5. Development of a high capacity longwall conveyor. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Sparks, C


    The objectives of this program were to develop, fabricate, and demonstrate a longwall conveying system capable of transporting coal at a rate of 9000 tons/day (1000 tons/hr) and capable of accommodating a surge rate of 20 tons/min. The equipment was required to have the structural durability to perform with an operating availability of 90%. A review of available literature and discussions with longwall operators identified the problem areas of conveyor design that required attention. The conveyor under this contract was designed and fabricated with special attention given to these areas, and also to be easily maintainable. The design utilized twin 300 hp drives and twin inboard 26-mm chain at 270 ft/min; predictions of capacity and reliability based on the design indicating that it would satisfy the program requirements. Conveyor components were critically tested and the complete conveyor was surface-tested, the results verifying the design specifications. In addition, an instrumentation system was developed with analysis by computer techniques to monitor the performance of the conveyor. The conveyor was installed at a selected mine site, and it was the intention to monitor its performance over the entire longwall panel. Monitoring of the conveyor performance was conducted over approximately one-third of the longwall panel, at which point further effort was suspended. However, during the monitored period, data collected from various sources showed the conveyor to have exhibited its capability of transporting coal at the desired rate, and also to have conformed to the program requirements of reliability and availability.

  6. Longwall Mining Stability in Take-Off Phase

    Directory of Open Access Journals (Sweden)

    María-Belén Prendes-Gero


    Full Text Available Mechanised longwall mining is one of the more commonly employed exploitation methods in underground mines in the north of Spain as well as in the rest of the world. It is continuously changing and evolving, with new techniques, technology, equipment, and face management practices and systems appearing for the purposes of improving aspects such as operational and financial performances and, above all, the safety of the miners. Despite its importance, there are no regulations for the mining of longwall coal seams. This work aims to contribute to an advance in the design and optimisation of the roof support in longwall mining, analysing the stability of the roof using a method based on the resistance of materials, which considers the characteristics of the properties of the roof materials. The influence of not only the individual elements of support but also the coalface, which is considered one more supporting element, is investigated. The longitudinal and transverse spacings of the support and the number of walkways constituting the exploitation panel are analysed. The proposed formulation is validated by information gathered in a mine located in the region of Castilla-Leon.

  7. 30 CFR 18.53 - High-voltage longwall mining systems. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage longwall mining systems. 18.53..., EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements § 18.53 High-voltage longwall mining systems. (a) In each high-voltage motor...

  8. Analysis of Availability of Longwall-Shearer Based On Its Working Cycle (United States)

    Brodny, Jaroslaw; Tutak, Magdalena


    Effective use of any type of devices, particularly machines has very significant meaning for mining enterprises. High costs of their purchase and tenancy cause that these enterprises tend to the best use of own technical potential. However, characteristics of mining production causes that this process not always proceeds without interferences. Practical experiences show that determination of objective measure of utilization of machine in mining company is not simple. In the paper methodology allowing to solve this problem is presented. Longwall-shearer, as the most important machine between longwall mechanical complex. Also it was assumed that the most significant meaning for determination of effectiveness of longwall-shearer has its availability, i.e. its effective time of work related to standard time. Such an approach is conforming to OEE model. However, specification of mining branch causes that determined availability do not give actual state of longwall-shearer’s operation. Therefore, this availability was related to the operation cycle of longwall-shearer. In presented example a longwall-shearer works in unidirectional cycle of mining. It causes that in one direction longwall-shearer mines, moving with operating velocity, and in other direction it does not mine and moves with manoeuvre velocity. Such defined working cycle became a base for determinate availability of longwall-shearer. Using indications of industrial automatic system for each of working shift there were determined number of cycles of longwall-shearer and availability of each one. Accepted of such way of determination of availability of longwall-shearer enabled to perform accurate analysis of losses of its availability. These losses result from non-planned shutdowns of longwall-shearer. Thanks to performed analysis based on the operating cycle of longwall-shearer time of its standstill for particular phase of cycle were determined. Presented methodology of determination of longwall

  9. A study of the relationship between saturated zone response and longwall mining-induced ground strain

    International Nuclear Information System (INIS)

    Trevits, M.A.; Matetic, R.J.


    The effects of longwall mining operations on near-surface water are not well understood. The sparse information that is available indicates a correlation between the proximity of the approaching longwall face and fluctuations in observation water wells. Furthermore, the magnitude of mining-induced subsidence appears to coincide with the degree of water level fluctuation. To provide additional information about these effects, the US Bureau of Mines has been installing well arrays over select longwall operations and observing the change as mining progresses through the area. Studies have been conducted at mine sites located in Pennsylvania and Ohio. The results of the research suggest that a relationship exists between water level fluctuations and the ground strain developed by the approaching longwall face. This paper explores research conducted at three mine sites and explains both the magnitude and timing of the observed water level fluctuations as a function of longwall mining-induced ground movement

  10. Hydrogeologic impacts of underground (Longwall) mining in the Illinois basin

    International Nuclear Information System (INIS)

    Booth, C.J.


    This paper reports that hydrogeological impacts of active longwall mining were studied at two sites in Illinois. At the site with the more transmissive sandstone aquifer, aquifer permeabilities increased an order of magnitude due to subsidence. Piezometric levels declined with subsidence due to increased porosity, and ahead of mining due to a transmitted drawdown. Levels recovered rapidly at first and fully over two years. At the site with the less transmissive aquifer, impacts were similar except that recovery has been limited. Local aquifer enhancement through increased yield can occur, but only where the aquifer is transmissive enough for recovery

  11. Analysis and Assessment of Parameters Shaping Methane Hazard in Longwall Areas

    Directory of Open Access Journals (Sweden)

    Eugeniusz Krause


    Full Text Available Increasing coal production concentration and mining in coal seams of high methane content contribute to its growing emission to longwall areas. In this paper, analysis of survey data concerning the assessment of parameters that influence the level of methane hazard in mining areas is presented. The survey was conducted with experts on ventilation and methane hazard in coal mines. The parameters which influence methane hazard in longwall areas were assigned specific weights (numerical values. The summary will show which of the assessed parameters have a strong, or weak, influence on methane hazard in longwall areas close to coal seams of high methane content.

  12. Electromechanical dynamic analysis for the drum driving system of the long-wall shearer

    Directory of Open Access Journals (Sweden)

    Changzhao Liu


    Full Text Available The drum driving system is one of the weakest parts of the long-wall shearer, and some methods are also needed to monitor and control the long-wall shearer to adapt to the important trend of unmanned operation in future mining systems. Therefore, it is essential to conduct an electromechanical dynamic analysis for the drum driving system of the long-wall shearer. First, a torsional dynamic model of planetary gears is proposed which is convenient to be connected to the electric motor model for electromechanical dynamic analysis. Next, an electromechanical dynamic model for the drum driving system is constructed including the electric motor, the gear transmission system, and the drum. Then, the electromechanical dynamic characteristics are simulated when the shock loads are acted on the drum driving system. Finally, some advices are proposed for improving the reliability, monitoring the operating state, and choosing the control signals of the long-wall shearer based on the simulation.

  13. Development of an illumination system for longwall coal mines. Report for 1973--1975

    Energy Technology Data Exchange (ETDEWEB)

    Friedline, G.; Gartley, M.; Ketler, A.; Pellmann, R.


    The report describes the development of a lighting system beginning with a prototype longwall mockup followed by the design, fabrication, and testing of the system in an operating coal mine. Details of the design, installation, operation, and performance are given. The results have provided the basic technology needed to illuminate longwall sections. The existence of the technology is part of the prerequisite to promulgation of illumination standards as required by the Coal Mine Health and Safety Act of 1969. (GRA)

  14. Methodological details of determining maximum single concentration of dust along scraper longwalls of coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Rubanov, G.P.; Grebtsov, E.M.; Kurnosov, V.K.; Tolstoi, G.I.


    Recommendations of 'Instructions on determining pneumoconiosis danger of mine work in coal mines' for choice of a basic point for measuring maximum single concentration of dust along scraper longwalls do not make it possible to objectively evaluate dust load at working places. In the Instructions, a point at 10 to 15 m from exit of longwall on the ventilation drift with an emergent stream of air is proposed for the dust probe. This designated point does not take into account the influence of the scheme of ventilation of the walls on formation of dust currents. Investigations of probes taken at different places along the longwall (at the beginning, 15 m from the begining, 15 m from the end, at the niche and transfer point of the longwal) using direct and reverse flow schemes of ventilation showed that the best point for determining maximum single concentratin of dust is a point in the middle of the longwall where dust currents are the same for both systems of ventilation, and use of a new method of calculating the dust load by testing at many different positions along the scraper longall makes it possible to determine the category of pneumonoconiosis danger for workers at scraper longwalls.

  15. Does longwall mining have a detrimental effect on shallow ground water sources?

    International Nuclear Information System (INIS)

    Matetic, R.J.; Trevits, M.A.


    Longwall mining typically affects the entire overburden rock mass from the unit immediately above the coalbed being mined to the ground surface. It is natural to assume that any water-bearing zones contained within this interval may be influenced to some degree. In some cases, a complete loss of water may be experienced and in others an increase in the hydrologic properties may occur. To address this apparent dichotomy, the US Bureau of Mines is conducting a comprehensive program of subsidence research in select mining areas of the United States. One such site was located in Vinton County, Ohio where two contiguous longwall panels were designated as a study area. The two longwall panels measured approximately 900 ft wide and 9,000 ft long. The thickness of the extracted coal was about 55 inches. The longwall panels were separated by five entries or approximately 350 ft. Overburden thickness in the study area varied from 200 to 350 ft. To evaluate the effects of mining, seven, 8 5/8-inch diameter observation wells were drilled at critical positions above the longwall panels. Water level fluctuations, surface subsidence and hydrologic properties were measured as mining progressed through the study area. Results of this study show mining of both longwall panels did not interrupt the hydrologic regime. This paper provides a detailed case study delineating the timing and effects of mining on local shallow ground water sources

  16. A new cavability assessment criterion for longwall top coal caving

    Energy Technology Data Exchange (ETDEWEB)

    Vakili, A.; Hebblewhite, B.K. [University of New South Wales, Sydney, NSW (Australia)


    This paper describes the main results of project aimed at developing a new cavability assessment criterion for top-coal, and improving the overall understanding of the caving mechanism in Longwall Top Coal Caving (LTCC) technology. The research methodology for this study incorporated a combination of analytical, observational and empirical engineering methods. The two major outcomes of the study were an improved understanding of the caving mechanics, and a new cavability assessment system, the Top-Coal Cavability Rating (TCCR). New conceptual models were introduced for better understanding of top coal caving mechanism. The results of the conceptual investigations suggest that six major parameters can influence the cavability of a typical coal seam, i.e. deformation modulus; vertical pre-mining stress; 3-sub-horizontal pre-mining stress; 4-seam thickness; spacing of sub-horizontal joints; and spacing of sub-vertical joints. The applicability of TCCR system was investigated by back analysing the cavability in earlier LTCC practices.

  17. Surface movement above an underground coal longwall mine after closure (United States)

    Vervoort, André


    The surface movement in an area of about 22 km2 above the underground coal mine of Houthalen was analyzed based on Interferometry with Synthetic Aperture Radar (InSAR) measurements. After its closure in 1992, a residual subsidence was observed over a period of several years, followed by an uplift of the surface above and around the past longwall panels, whereby the rate of movement was, in absolute terms, of the same order for the two types of movements. The processes behind these movements are different. The process of subsidence is caused by the caving of the roof above the mined-out area and is mainly a mechanical stress-deformation process, including time-dependent aspects. However, the process of uplift is most probably caused by the swelling of the clay minerals in the argillaceous rocks in the coal strata after the flooding of the underground workings. Hence, the areas in which there is the greatest risk of damage to the surface infrastructure are not the same for the hazards linked to subsidence and uplift. For example, the zone in which the maximum uplift occurs clearly is at a different location from that of the zone with the maximum residual subsidence. There is no clear sign that the amount of mining underneath affects the residual subsidence, and there is no indication that the process of uplift is linked directly to the mining characteristics. It is more likely that uplift as the result of flooding is initiated at, or close to, the vertical shafts.

  18. Numerical Simulation of Aerogasdynamics Processes in A Longwall Panel for Estimation of Spontaneous Combustion Hazards (United States)

    Meshkov, Sergey; Sidorenko, Andrey


    The relevance of a solution of the problem of endogenous fire safety in seams liable to self-ignition is shown. The possibilities of numerical methods of researches of gasdynamic processes are considered. The analysis of methodical approaches with the purpose to create models and carry out numerical researches of aerogasdynamic processes in longwall panels of gas mines is made. Parameters of the gob for longwall mining are considered. The significant influence of geological and mining conditions of conducting mining operations on distribution of air streams on longwall panels and effective management of gas emission is shown. The aerogasdynamic model of longwall panels for further research of influence of parameters of ventilation and properties of gob is presented. The results of numerical researches including distribution of air streams, fields of concentration of methane and oxygen at application of various schemes of airing for conditions of perspective mines of the Pechora basin and Kuzbass are given. Recommendations for increase of efficiency of the coal seams mining liable to selfignition are made. The directions of further researches are defined.

  19. Analysis of Influence of Goaf Sealing from Tailgate On the Methane Concentration at the Outlet from the Longwall (United States)

    Tutak, Magdalena; Brodny, Jaroslaw


    One of the most common and most dangerous gas hazards in underground coal mine is methane hazard. Formation of dangerous, explosive concentrations of methane occurs the most often in the region of crossing of longwall with the ventilation gallery. Particularly it applies to longwalls ventilated in „U from bounds” system. Outflow of gases from the goaf to the tailgate takes place through the boundary surfaces of this sidewalk with goaf. Main cause of this process is a phenomenon of air filtration through the goaf with caving. This filtration is a result of migration of the part of ventilation air stream supplied to the longwall. This air is released into the goaf on the entire longwall length; however, its greater amount gets to the goaf with caving space at the crossing of maingate with exploitation longwall. Albeit, the biggest outflow of air mixture and gases from the goaf occurs in top gate in upper corner of the longwall. This is a result of pressure difference in this region. This phenomenon causes that to the space of heading besides the air also other gases present in the goaf, mainly methane, are released. Methane is an explosive gas. Most often boundaries of explosive mixtures of methane, air and inert gases are described by the so-called Coward triangle explosion. Within the limits of the occurrence of the concentration of explosive methane explosion initials may be endogenous fire, blasting or sparks arising from friction of moving lumps of rock. Therefore, in order to decrease its concertation in this region, by limiting its outflow from the goaf with caving different actions are taken. One of such action is sealing of goaf from top gate side. Analysis of impact of sealing of these goaf on the methane concentration at the outlet of longwall is main aim of studies researches. Model of tested region, together with boundary conditions (including parameters of flowing air and the methane content) was developed on the base of real data from one of the

  20. Surface structural damage associated with longwall mining near Tuscaloosa, Alabama: a case history

    International Nuclear Information System (INIS)

    Isphording, W.C.


    Initially the paper examines the frequency of coal mine subsidence and the influence on surface subsidence of subsurface mining methods, i.e. room and pillar and longwall mining. A case study of the subsidence damage caused to a log house near Tuscaloosa, Alabama (USA), when a longwall panel passed beneath it is presented. The damage resulted in the homeowners suing the mining company for negligence. The article discusses information provided to the plaintiffs attorneys by the author. Aspects covered are: the subsidence and damage to the property; prediction of subsidence; the monitoring of subsidence; and the prevention of subsidence. An out-of-court settlement was agreed by the two parties. 15 refs., 5 figs

  1. Simulation of longwall top coal caving sequence and coal clearance system

    Energy Technology Data Exchange (ETDEWEB)

    Xu, B.; Hebblewhite, B.; Cai, Y. [University of New South Wales, Sydney, NSW (Australia). School of Mining Engineering


    The Longwall Top Coal Caving (LTCC) system of mining thick coal seams offers productivity and safety benefits, compared to the single pass operations used in Australia. The application of simulation modelling (AutoMod) to optimize caving sequences, predict throughput of a LTCC system, find and minimize slow-downs, and predict peak loading capacity of each conveyor section is described. Data sampled from an operating LTCC face in China is used to verify the model. 9 refs., 11 figs., 1 tab.

  2. An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining


    Manchao He; Yubing Gao; Jun Yang; Weili Gong


    Gob-side entry retaining (GER) is a popular non-pillar mining technique regarding how to reserve a gateroad for the use of next panel mining. When used in thick coal seams, the conventional entry retaining method requires a huge amount of filling materials and may cause entry (gateroad) accidents. Thus, an innovative non-pillar longwall mining approach is introduced. First, structural and mechanical models were built to explore the mechanism of the new approach. The modeling results indicate ...

  3. Modeling the effects of longwall mining on the ground water system

    International Nuclear Information System (INIS)

    Matetic, R.J.; Liu, J.; Elsworth, D.


    The objective of this US Bureau of Mines hydrologic-subsidence investigation was to evaluate the effects of longwall mining on the local ground water regime through field monitoring and numerical modeling. Field data were obtained from multiple-position borehole extensometers (MPBXs) that were used to measure subsurface displacements. Survey monuments were installed to measure mining-induced surface deformations. Numerous drawdown and recovery tests were performed to characterized hydrologic properties of the overburden strata. Coreholes were drilled above the study area to determine lithologic and strength characteristics of the overburden strata using the rock samples collected. Electronic recorders were installed on all monitoring wells to continuously monitor ground water levels in coordination with mining of the longwall panels. A combined finite element model of the deformation of overlying strata, and its influence on ground water flow was used to define the change in local and regional water budgets. The predicted effects of the postmining ground water system determined by the model correlated well with field data collected from the fieldsite. Without an infiltration rate added to the model, a static decrease of 3.0 m (10 ft) in water level would occur due to mining of both longwall panels and if an infiltration rate was inputted in the model, no predicted long-term effects would occur to the ground water system

  4. Foam property tests to evaluate the potential for longwall shield dust control. (United States)

    Reed, W R; Beck, T W; Zheng, Y; Klima, S; Driscoll, J


    Tests were conducted to determine properties of four foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with the Mine Safety and Health Administration's lower coal mine respirable dust standard of 1.5 mg/m 3 . Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used low-pressure air generated by a blower and water pressure using a foam generator developed by the U.S. National Institute for Occupational Safety and Health. Foam property tests, consisting of a foam expansion ratio test and a water drainage test, were conducted to classify foams. Compressed-air-generated foams tended to have low expansion ratios, from 10 to 19, with high water drainage. Blower-air-generated foams had higher foam expansion ratios, from 30 to 60, with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The test results eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control.

  5. Modeling the effect of seal leakage on spontaneous heating in a longwall gob area

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.C.; Yuan, L. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States). Office of Mine Safety and Health Research


    Three coal mines in the United States with a history of spontaneous combustion use a bleederless ventilation system as a control measure. In a bleederless system, one of the headgate entries is used as the tailgate entry of the succeeding panel and is isolated from the gob of the active panel by gob seals that are installed in the headgate entry as the face advances. An active longwall panel using a Y-type bleederless ventilation system was simulated in this study. As longwall mining progresses, some seals are known to leak. Computational fluid dynamics (CFD) simulations were performed to study the effect of seal leakage on spontaneous heating of coal in the longwall gob area. The simulation results showed that under typical bleederless ventilation conditions, the maximum temperature in the gob increased with an increase in leakage rate. The maximum temperature occurred at the headgate side corner at the back end of the panel. When only 1 or 2 seals were leaking, the maximum temperature occurred around the seal. The results demonstrate that complex interactions between pressure differential and gob permeability at different locations in the gob cause ventilation pathways. The interactions depend greatly on gob permeability and seal leakage rates. 8 refs., 1 tab., 14 figs.

  6. Estimation of the Change in Storage Capacity above Mined Longwall Panels. (United States)

    Tammetta, Paul


    Accurate estimation of the change in groundwater storage capacity (S) above mined longwall panels is vital for analysis of postmining void water level recovery in coal mines, and assessment of water quality impacts. At present, there is no generalized representation of the spatial distribution of changes in S around a panel. Current estimates are generally bulk averages with high uncertainty, precluding calculation of groundwater velocities in various parts of the subsurface. In this work, a recently published hydrogeological conceptual model of longwall caving is used in conjunction with observations from borehole extensometers, goaf height measurements, and pumping/drawdown records for mine pools to develop a subsurface spatial distribution of changes in S following longwall caving, with reduced uncertainty in their magnitudes. The assumption of saturation in the disturbed zone proved critical for obtaining accurate results and in reconciling widely varying published estimates of S. Results indicate that the goaf and collapsed zones each absorb over 30% of the mined volume, and about 20% is absorbed by the surface subsidence trough. The increase in S in the collapsed zone is inversely proportional to the amount of surface subsidence. The conceptual model is updated with these results to present the spatial distribution of S after caving. The results allow calculation of water velocities in various zones, and may provide greater accuracy in estimation of water level rebound and water quality processes. Most of the S participating in groundwater flows is provided by defects rather than the matrix. © 2016, National Ground Water Association.

  7. Voussoir beam model for lower strong roof strata movement in longwall mining – Case study

    Directory of Open Access Journals (Sweden)

    Chuang Liu


    Full Text Available The paper presents the influence of varying immediate roof thickness on the lower strong roof strata movement and failure pattern in longwall coal mining with large mining height. The investigation is based on 58 geological drill holes and hydraulic shield pressure measurements around the longwall Panel 42105 of the Buertai Mine in Inner Mongolia Autonomous Region, China. The longwall Panel 42105 is characterized by relatively soft immediate roof strata of varying thickness superposed by strong strata, herein defined as lower strong roof. A voussoir beam model is adopted to interpret the structural movement of the lower strong roof strata and shield pressure measurements. It is shown that when the immediate roof is relatively thick, the broken overlying lower strong roof tends to form a stable voussoir beam with previously broken layer, thus not exerting high pressure on the hydraulic shield and working face. When the immediate roof is relatively thin, the broken overlying lower strong roof tends to behave as a cantilever beam, thus exerting higher pressure on the hydraulic shield and working face. Comparison of model predictions with measured time-weighted average shield pressure (TWAP shows good agreement.

  8. Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport. (United States)

    Shahan, M R; Seaman, C E; Beck, T W; Colinet, J F; Mischler, S E


    Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. If deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8.

  9. An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining

    Directory of Open Access Journals (Sweden)

    Manchao He


    Full Text Available Gob-side entry retaining (GER is a popular non-pillar mining technique regarding how to reserve a gateroad for the use of next panel mining. When used in thick coal seams, the conventional entry retaining method requires a huge amount of filling materials and may cause entry (gateroad accidents. Thus, an innovative non-pillar longwall mining approach is introduced. First, structural and mechanical models were built to explore the mechanism of the new approach. The modeling results indicate that effective bulking of the gob roof and reasonable support of the entry roof were key governing factors in improving entry stabilities and reducing roof deformations. Accordingly, a directional roof fracturing technique was proposed to contribute to gob roof caving, and a constant resistance and large deformation anchor (CRLDA cable was used to stabilize the entry roof. Subsequently, the evolutionary laws of the roof structure and stresses were explored using numerical simulation. It was found that the structure of the surrounding rocks around the retained entry changed significantly after roof fracturing. The stress-bearing center was transferred to the gob area, and the entry roof was in a low stress environment after adopting the approach. Finally, the approach was tested on a thick coal seam longwall mining panel. Field monitoring indicates that the retained entry was in a stable state and the index of the retained entry met the requirement of the next mining panel. This work provides an effective and economical approach to non-pillar longwall mining in thick coal seams.

  10. Reducing dust at longwall shearers by confining the dust cloud to the face

    Energy Technology Data Exchange (ETDEWEB)

    Kissell, F.; Jayaraman, N.; Taylor, C.; Jankowski, R.


    The Bureau of Mines has developed the shearer-clearer dust control system for longwall shearers. The system partitions the airflow around the shearer into a clean split and a contaminated split. The dust cloud is confined to the vicinity of the coal face, while the shearer operators remain in the clean split on the gob side of the machine. The shearer-clearer operates on the principle that each water spray moves air like a small fan and can be positioned to direct the dustry air toward the face. The hardware is inexpensive and can be installed in a single shift. It consists of several strategically mounted water sprays and one or more passive barriers. Laboratory testing indicates reductions in shearer operator dust exposure as high as 97%. Preliminary results indicate that considerable dust reductions at the shearer may also be obtained. In conjunction with the development of the shearer-clearer, dust surveys were conducted in three other mines to determine if some shearer spray systems currently in use partition the flow in a manner similar to the shearer-clearer, and if so, whether this partially accounts for markedly cleaner conditions on some longwalls. Results indicate this to be the case: a feature of the cleaner longwalls was a downwind orientation of their water sprays, which is a key element of the shearer-clearer system. The shearer-clearer system described was designed for an Eickhoff EDW 300 shearer working a 7-foot coal seam. Testing to date has concentrated on cutting directions counter to the primary airflow. It is expected that different systems will be required to accommodate the range of conditions occurring underground. Application to conditions different than those described is not likely to produce the same results.

  11. Effect of the distance between disruptive disturbances on the output of powered longwall equipment sets

    Energy Technology Data Exchange (ETDEWEB)

    Kozel, K.K.; Seredyuk, V.L. (L' vovsko-Volynskaya GRE (USSR))


    Presents a statistical analysis of data on tectonic disturbances in the L'vovsk-Volynsk black coal basin and their effect on productivity. The effect of disjunctive disturbances on working face advance rate was analyzed on the basis of data on disturbances with stratigraphic amplitudes of 0.9{+-}0.21 m. Dependence of the coefficient of maintained production level on the distance between disjunctive disturbances is shown in graphs for the 1K-101 and GSh-68 longwall equipment sets. Recommendations are made for increasing the advance rate when crossing tectonic disturbances.

  12. Demonstration of shield-type longwall supports at York Canyon Mine of Kaiser Steel Corporation. Final technical report A

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, R.G.; King, R.


    This report represents work on a program that was originated by the USBM of the Department of the Interior and was transferred to the Department of Energy on October 1, 1977. A demonstration with the Government funded Hemscheidt 320 HSL caliper type shield supports was conducted at three longwall panels of Kaiser Steel Corporation's York Canyon Mine. The purpose of this longwall demonstration was to provide the US coal industry with information on all aspects of shield longwall mining in high seams. The demonstration provided a working model for the coal industry and during the project, 350 people from the industry, schools, and government agencies visited the demonstration. They were provided with a first hand knowledge of a working shield longwall. The demonstration showed that the control of large coal lumps may be a problem in the mining of coal seam thicker than 8 feet. Mining with shield type supports provided good working conditions and a safe working environment. The shield requires very little maintenance and has a high mechanical availability.

  13. Mechanical Characteristics of Superhigh-Water Content Material Concretion and Its Application in Longwall Backfilling

    Directory of Open Access Journals (Sweden)

    Xufeng Wang


    Full Text Available Superhigh-water content material (SCM has been widely utilized for goaf backfilling, grouting, and fire prevention and extinguishing. In this paper, the engineering mechanical characteristics of superhigh-water content material concretion (SCMC were studied for two types of backfilling technologies in longwall mining—open-type and pocket-type backfilling. The mechanical properties and responses of the SCMC were assessed under different cementation states, varying loading conditions and at different scales. The results indicate that: (1 the compressive and tensile strengths of SCMC specimens in different cementation states increase as the curing time increases—the SCMC formed by a mixture of SCM and gangues has higher strength than that of pure SCM; (2 the SCMC is under different loading and confinement conditions when different backfilling technologies is applied; however the strength of SCMC increases with curing time and decreases with water volume percentage; and (3 large-size specimens of pure SCMC enter into an accelerated creep state at a leveled load of 1.4 MPa. The effects of SCM backfilling on subsidence control has been verified by field applications. The results presented in this paper can provide data support for the optimization of backfill mining technology using SCM, as well as for the design of hydraulic supports parameters at longwall faces.

  14. Forecasts of methane concentration at the outlet of the longwall with caving area - case study (United States)

    Badura, Henryk; Bańka, Piotr; Musioł, Dariusz; Wesołowski, Marek


    This paper presents the characteristics of methane hazard and prevention undertaken in the N-6 longwall of seam 330/2 in “Krupiński" coal mine. On the basis of methane concentration measurements conducted with the use of telemetric system, time series of the average and maximum methane concentration at the outlet of the longwall area were generated. It was ascertained that they exhibit a strong autocorrelation. Based on a series of the average methane concentration, a time series of ventilation methane content was created and a total methane content was calculated with the use of methane flow rate measurements in the demethanization system. It was ascertained that dependence between methane concentration and output on the examined day and on the previous day is weak and also that the dependence between methane concentration and air flow rate is very weak. Dependencies between ventilation methane content, total methane content and demethanization efficiency were also investigated. Based on forecasting models [1] developed earlier by H. Badura, forecasts have been made to predict the average and maximum methane concentrations. The measured values f methane concentration show a high level of accordance with forecasted ones.

  15. Field trials of aquifer protection in longwall mining of shallow coal seams in China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D.S.; Fan, G.W.; Liu, Y.D.; Ma, L.Q. [State Key Laboratory of Coal Resource & Mine Safety, Xuzhou (China)


    The large-scale mining of shallow coal seams has a significant impact on the overlying aquifers and surface ecological environment. To protect the aquifers and maximize the coal resource recovery, field trials were undertaken during the operation of the LW32201 in Bulianta coal mine, Shendong, China. With a severely weathered rock (SWR) layer and two key strata (KS) in the overlying strata, aquifer protection in longwall mining (APLM) relies mainly on the rapid advance. In some localized zones, special measures should be taken to achieve the APLM, including lowering mining height, backfill and slurry injection. To further understand the mechanism and applicable conditions of the APLM and validate the effectiveness of the APLM, variation of the water table in the aquifer was observed as the longwall face passed through the zone. This paper also discusses the mechanism and basic requirements of the APLM and the relationship between the fall of the water table and the surface subsidence. The results of the field trials indicated that APLM in shallow coal seams could be successful under suitable conditions.

  16. Seismic monitoring of ground caving processes associated with longwall mining of coal

    International Nuclear Information System (INIS)

    Hatherly, P.; Luo, X.; Dixon, R.; McKavanagh, B.


    At the Gordonstone Coal Mine in Central Queensland, Australia, a microseismic monitoring study was undertaken to investigate the extent of ground failure caused by longwall mining. Twenty seven triaxial geophones were deployed in three vertical boreholes and over a six week period more than 1200 events were recorded. The seismicity correlated with periods of longwall production and occurred mainly within the 250 m wide mining panel. There was an arcuate zone of activity which extended from behind the face, at the sides of the panel and up to 70 m ahead of the face in the middle. There was lesser activity to a depth of about 30 m into the floor. The focal mechanisms show that reverse faulting was dominant. The presence of activity and reverse faulting ahead of the face was an unexpected result. However, piezometer readings at the time of the study and subsequent numerical modelling have supported this finding. This was the first detailed microseismic monitoring study of caving in an Australian underground coal mine. 9 refs., 6 figs

  17. Mine roof support and method in longwall mining of thick mineral seams

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, T.L.


    A bi-directional shearing machine mines a longwall face at the bottom of a thick mineral seam in a retreat operation under the protection of a row of adjacent powered roof supports each of which extends in a direction transverse to the solid face. Progressive advance of these roof supports allows the overlying mineral strata to cave. Each roof support is separated into articulated forward and aft units provided with separate sets of hydraulic props and having their solid canopies interfitted in end-to-end relation. The bases of the two units are interconnected with a push-pull hydraulic ram which enables relative longitudinal movement between the two units so that they may be advanced independently along a common axis toward the solid longwall face as the work progresses. During the advance of the forward units to provide face support, plowing and loading of carved mineral on the gob side may proceed without interruption. To accelerate caving, the aft units are independently advanced with an attached gob side chain conveyor and gob plow retracted beneath their canopies for protection. Starting from this retracted position, the gob conveyor and gob plow are allowed to load gradually out into the flushed coal.

  18. Effects of longwall coal mining on the hydrology of two appalachian stream valleys

    International Nuclear Information System (INIS)

    Johnson, K.L.


    In an effort to quantify the effects of longwall mining on local hydrology, an intensive data collection program was undertaken at two sites in the Northern Appalachian coal field where the depth of mining is 500-600 feet. Wells were drilled prior to mining at both sites so that water level, water quality, and aquifer transmissivity data could be obtained before and after mining. Streamflow measurements were also taken before and after mining to evaluate effects of mining on surface water. Water levels in wells dropped a maximum of 15 feet during undermining and then recovered to levels at or above premining levels. Groundwater quality was not degraded as a result of mining at either site. Aquifer transmissivity increased an order of magnitude after mining at both sites. Impacts of mining on streamflow at both sites were minimal

  19. Determination of Elastic Parameters of Near-Surface Layers Over Subsidence Trough Development During Longwall Exploitation (United States)

    Mendecki, Maciej J.; Jochymczyk, Krzysztof; Zuberek, Wacław M.; Tomaszewska, Radosława


    Seismic and geodetic studies were carried out before, during, and after underground exploitation of a coal bed in Katowice - Kleofas Coal Mine, located in the Upper Silesia Coal Basin, Poland. Development of a subsidence trough was completed approximately 3 months after passage of a longwall exploitation in the coal seam. This was the time required for the subsidence trough to appear on the surface, which was confirmed by levelling measurements. Sharp changes in the elastic parameters were observed on each profile during subsidence trough development. This observation can result from changing tension and compression forces caused by increase and/or decrease of the elastic parameters of the rock mass. After completion of subsidence trough development, the rock mass appeared to return to its isotropic state and the observed changes ceased. Some minor fluctuations were noted, but they probably resulted from changes in groundwater levels, which might have affected the measured parameters.

  20. Longwall mining “cutting cantilever beam theory” and 110 mining method in China—The third mining science innovation


    Manchao He; Guolong Zhu; Zhibiao Guo


    With the third innovation in science and technology worldwide, China has also experienced this marvelous progress. Concerning the longwall mining in China, the “masonry beam theory” (MBT) was first proposed in the 1960s, illustrating that the transmission and equilibrium method of overburden pressure using reserved coal pillar in mined-out areas can be realized. This forms the so-called “121 mining method”, which lays a solid foundation for development of mining science and technology in Chin...

  1. Comprehensive study on the deformation and failure characteristics of a mining-impacted deep double-longwall working face floor (United States)

    Zhu, Shuyun; Lu, Liangliang; Wu, Yun; Zhang, Tingting


    The key solution to the safe mining of coal over a deep confined aquifer is to obtain and understand the deformation and failure characteristics of the working face’s floor strata. In this work, we took a typical fully mechanized mining deep double-longwall working face floor of Chengjiao Coal Mine as a study case. Through in situ tests we established a three-range partition model for mining-induced underground pressure propagation in the coalbed floor to reveal the behavior of pressure propagation in both the vertical and horizontal directions of the floor strata. We found that the floor experienced consecutively three quantitative deformation ranges, and showed three different underground pressure behavior ranges the measured failure depth in the mining-induced double-longwall working faces floor was less than 27 m. In addition, the groups of rock mass were divided for mining the coal roof and floor, and we constructed a 3D engineering geological numerical model for the double-longwall working faces, and numerically simulated the plastic zone distribution features and the maximum vertical stress at different floor depths, finding that there were three stages for vertical stress along the mining coalbed floor depth. We also found that the failure depth of the floor was not more than 27 m by numerical simulation, consistent with the in situ measured result. All these results are of significance for the prevention and control of water inrush out of the double-longwall working face floor and for the support of their related roadways.

  2. Study on gob-side entry retaining technique with roadside packing in longwall top-coal caving technology

    Energy Technology Data Exchange (ETDEWEB)

    Hua, X. [China University of Mining and Technology, Beijing (China). Dept. of Resource and Safety Engineering


    The article points out some technical difficulties of gob-side entry retaining with roadside packing in longwall top-coal caving technology (LTCT), and analyzes the function mechanism of roadside filling body. Theory analysis shows the mechanical properties of high water material fit the feature of deformation of gob-side entry retaining in LTCT, and gob-side entry retaining in LTCT face is one of effective ways to increase the recovery ratio of the mining district. 3 refs., 1 fig.

  3. Determination of Particular Endogenous Fires Hazard Zones in Goaf with Caving of Longwall (United States)

    Tutak, Magdalena; Brodny, Jaroslaw


    Hazard of endogenous fires is one of the basic and common presented occupational safety hazards in coal mine in Poland and in the world. This hazard means possibility of coal self-ignition as the result of its self-heating process in mining heading or its surrounding. In underground coal-mining during ventilating of operating longwalls takes place migration of parts of airflow to goaf with caving. In a case when in these goaf a coal susceptible to selfignition occurs, then the airflow through these goaf may influence on formation of favourable conditions for coal oxidation and subsequently to its self-heating and self-ignition. Endogenous fire formed in such conditions can pose a serious hazard for the crew and for continuity of operation of mining plant. From the practical point of view, a very significant meaning has determination of the zone in the goaf with caving, in which necessary conditions for occurrence of endogenous fire are fulfilled. In the real conditions determination of such a zone is practically impossible. Therefore, authors of paper developed a methodology of determination of this zone basing on the results of modelling tests. This methodology includes a development of model of tested area, determination of boundary conditions and carrying out the simulation calculations. Based on the obtained results particular hazardous zone of endogenous fire is determined. A base for development of model of investigated region and selection of boundary conditions are the results of real tests. In the paper fundamental assumption of developed methodology, particularly in a range of assumed hazard criterion and sealing coefficient of goaf with caving were discussed. Also a mathematical model of gas flow through the porous media was characterized. Example of determination of a zone particularly endangered by endogenous fire for real system of mining heading in one of the hard coal mine was presented. Longwall ventilated in the „Y” system was subjected to the

  4. Reconciling longwall gob gas reservoirs and venthole production performances using multiple rate drawdown well test analysis

    Energy Technology Data Exchange (ETDEWEB)

    Karacan, C. Oezgen [National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory, Pittsburgh 15236, PA (United States)


    Longwall mining is an underground mining method during which a mechanical shearer progressively mines a large block of coal, called a panel, in an extensive area. During this operation the roof of the coal seam is supported only temporarily with hydraulic supports that protect the workers and the equipment on the coal face. As the coal is extracted, the supports automatically advance and the roof strata cave behind the supports. Caving results in fracturing and relaxation of the overlying strata, which is called ''gob.'' Due its highly fractured nature, gob contains many flow paths for gas migration. Thus, if the overlying strata contain gassy sandstones or sandstone channels, gas shales or thinner coal seams which are not suitable for mining, then the mining-induced changes can cause unexpected or uncontrolled gas migration into the underground workplace. Vertical gob gas ventholes (GGV) are drilled into each longwall panel to capture the methane within the overlying fractured strata before it enters the work environment. Thus, it is important, first to understand the properties of the gas reservoir created by mining disturbances and, second, to optimize the well parameters and placement accordingly. In this paper, the production rate-pressure behaviors of six GGVs drilled over three adjacent panels were analyzed by using conventional multi-rate drawdown analysis techniques. The analyses were performed for infinite acting and pseudo-steady state flow models, which may be applicable during panel mining (DM) and after mining (AM) production periods of GGVs. These phases were analyzed separately since the reservoir properties, due to dynamic subsidence, boundary conditions and gas capacity of the gob reservoir may change between these two stages. The results suggest that conventional well test analysis techniques can be applicable to highly complex gob reservoirs and GGVs to determine parameters such as skin, permeability, radius of investigation

  5. Optimization of daily output from a mechanized longwall face at the Bana Cigel mine

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, F.


    Briefly reviews history of mechanized longwall coal mining in Slovakia, where daily face output grew from 329 t in 1965 to 563 t in 1986, while average number of faces fell from 84.1 to 36.1. Discusses various mathematical models which may be used for calculating daily output from mechanized faces (IGD Skochinskii model) and output per shift (Konikevich and Moiseev model) and a model of mechanized extraction equipment developed by E.I. Rogov, and lists main steps in the method applied to the Bana Cigel mine: selection of suitable monitoring method, measuring time and speed of operation, writing a BASIC computer program to process data, calculation of basic statistical information, regression and correlation analysis and evaluation of results. Data were processed on a KRS-4200 computer (GDR) and results showed that the most useful relationship for determining optimum daily output was that between amount of daily output and total time of operation of mining machinery. Small dispersion variance of regression curves also meant that daily output could be determined in relation to geological and technical mine parameters. 1 ref.

  6. Probabilistic modeling using bivariate normal distributions for identification of flow and displacement intervals in longwall overburden

    Energy Technology Data Exchange (ETDEWEB)

    Karacan, C.O.; Goodman, G.V.R. [NIOSH, Pittsburgh, PA (United States). Off Mine Safety & Health Research


    Gob gas ventholes (GGV) are used to control methane emissions in longwall mines by capturing it within the overlying fractured strata before it enters the work environment. In order for GGVs to effectively capture more methane and less mine air, the length of the slotted sections and their proximity to top of the coal bed should be designed based on the potential gas sources and their locations, as well as the displacements in the overburden that will create potential flow paths for the gas. In this paper, an approach to determine the conditional probabilities of depth-displacement, depth-flow percentage, depth-formation and depth-gas content of the formations was developed using bivariate normal distributions. The flow percentage, displacement and formation data as a function of distance from coal bed used in this study were obtained from a series of borehole experiments contracted by the former US Bureau of Mines as part of a research project. Each of these parameters was tested for normality and was modeled using bivariate normal distributions to determine all tail probabilities. In addition, the probability of coal bed gas content as a function of depth was determined using the same techniques. The tail probabilities at various depths were used to calculate conditional probabilities for each of the parameters. The conditional probabilities predicted for various values of the critical parameters can be used with the measurements of flow and methane percentage at gob gas ventholes to optimize their performance.

  7. Mechanism and Prevention of a Chock Support Failure in the Longwall Top-Coal Caving Faces: A Case Study in Datong Coalfield, China


    Zhu Li; Jialin Xu; Shengchao Yu; Jinfeng Ju; Jingmin Xu


    Longwall chock support failures seriously restrain the safety and high-efficiency of mining of extra thick coal seams, as well as causing a great waste of coal resources. During longwall top-coal caving (LTCC), the influential effect of the properties and the movement regulation of top-coal on strata behavior cannot be ignored, since the top-coal is the medium through which the load of the overlying strata is transferred to the chock supports. Taking Datong coalfield as an example, the mechan...

  8. Satellite radar interferometry for monitoring subsidence induced by longwall mining activity using Radarsat-2, Sentinel-1 and ALOS-2 data (United States)

    Ng, Alex Hay-Man; Ge, Linlin; Du, Zheyuan; Wang, Shuren; Ma, Chao


    This paper describes the simulation and real data analysis results from the recently launched SAR satellites, ALOS-2, Sentinel-1 and Radarsat-2 for the purpose of monitoring subsidence induced by longwall mining activity using satellite synthetic aperture radar interferometry (InSAR). Because of the enhancement of orbit control (pairs with shorter perpendicular baseline) from the new satellite SAR systems, the mine subsidence detection is now mainly constrained by the phase discontinuities due to large deformation and temporal decorrelation noise. This paper investigates the performance of the three satellite missions with different imaging modes for mapping longwall mine subsidence. The results show that the three satellites perform better than their predecessors. The simulation results show that the Sentinel-1A/B constellation is capable of mapping rapid mine subsidence, especially the Sentinel-1A/B constellation with stripmap (SM) mode. Unfortunately, the Sentinel-1A/B SM data are not available in most cases and hence real data analysis cannot be conducted in this study. Despite the Sentinel-1A/B SM data, the simulation and real data analysis suggest that ALOS-2 is best suited for mapping mine subsidence amongst the three missions. Although not investigated in this study, the X-band satellites TerraSAR-X and COSMO-SkyMed with short temporal baseline and high spatial resolution can be comparable with the performance of the Radarsat-2 and Sentinel-1 C-band data over the dry surface with sparse vegetation. The potential of the recently launched satellites (e.g. ALOS-2 and Sentinel-1A/B) for mapping longwall mine subsidence is expected to be better than the results of this study, if the data acquired from the ideal acquisition modes are available.

  9. The Effect of Power Protection Equipment on Explosion Hazards and on the Reliability of Power Supply to Longwall Systems (United States)

    Boron, Sergiusz


    Operational safety of electrical machines and equipment depends, inter alia, on the hazards resulting from their use and on the scope of applied protective measures. The use of insufficient protection against existing hazards leads to reduced operational safety, particularly under fault conditions. On the other hand, excessive (in relation to existing hazards) level of protection may compromise the reliability of power supply. This paper analyses the explosion hazard created by earth faults in longwall power supply systems and evaluates existing protection equipment from the viewpoint of its protective performance, particularly in the context of explosion hazards, and also assesses its effect on the reliability of power supply.

  10. Three-dimensional experimental study of loose top-coal drawing law for longwall top-coal caving mining technology


    Wang, Jiachen; Zhang, Jinwang; Song, Zhengyang; Li, Zhaolong


    Based on the loose medium flow field theory, the loose top-coal drawing law of longwall top-coal caving (LTCC) mining technology is studied by using self-developed three-dimensional (3D) test device. The loose top-coal drawing test with shields and the controlled test without shields are performed in the condition without any boundary effect. Test results show that shields will cause reduction in drawing volume of coal in the LTCC mining. The deflection phenomenon of drawing body is also obse...

  11. Supporting technology of roadside in gob-side entry in 110 longwall mining method (United States)

    He, Manchao; Guo, Pengfei; Chen, Shangyuan; Gao, Yubing; Wang, Yajun


    To get better results of shaping roadside in 110 longwall mining method, the roadside support can be reasonably choose and designed through theoretical analysis, engineering test and other methods. The roadway support need to be designed based on the mining height and influence of mining pressure, and it is necessary to consider the "limited deformation" but also "given deformation". Because of the small mining high and short time under mining pressure effect in thin coal seam, roadside support can meet the requirements of block rock from gob using I-steel, but I-steel can't satisfy the deformation of roadway roof and easily lead to I-steel flexural buckling. In that condition we should use the U-steel that can compatible deformation with subsidence of roadway roof and enough torque in overlapping part between tow U-steel should be given when the U-steel is used to support gangue from gob and the U steel assembling two cards can coordinal deformation in dynamic pressure area keeping constant resistance with the deformation of roadway roof and can get a good effect. Through field test, due to the great impact force of the gangue from gob, single props and I-steel and U-steel are easily knocked down when the mining height is more than 4m. For large mining height, gangue blocking hydraulic support is designed and developed which can guarantee the stability and integrity of the roadway roof in the dynamic pressure area and can prevent the impact of gangue from gob. So it has better effect of forming roadway side using gangue from gob. According to above classification, the field experiments were carried out and obtained satisfactory results.

  12. Tactical and technological scheme of fire fighting in goaf left after longwall mining under conditions of methane combustion

    Energy Technology Data Exchange (ETDEWEB)

    Romanchuk, A.L.; Zrelyi, N.D.; Privalov, N.I.; Aleinikova, G.M.


    Presents recommendations on fire fighting in underground black coal mines. Situation when fire center is located in the goaf area left after longwall mining is analyzed. Fire fighting operations are divided into three stages: 1. fire fighting in the initial stage (installation of additional methane degassing means such as pipelines and pumps, pumping water, fire extinguishing foams or powders into fire center, ventilation, determining composition of the air in fire center), 2. intensification of fire fighting (increasing efficiency of degassing and fire extinguishing, improving ventilation of zone affected by the fire), 3. stage three occurs when fire extinguishing operations have been successful and consists in complete separation of the fire zone from the rest of the mine and from the ventilation system (changes in composition of fire gases and air are determined by automated instruments, injection of carbon dioxide or other inert gases, continuous deatatssing of the separated fire zone). Recommendations are listed in a detailed table. (In Russian)

  13. The design of a mechanical referencing system for the rear drum of the Longwall Shearer Coal Miner (United States)

    Jones, E. W.; Yang, T. C. H.


    The design of two systems which reference the position of a longwall shearer coal miner to the mine roof of the present cut and of the last cut are presented. This system is part of an automation system that will guide the rear cutting drum in such a manner that the total depth of cut remains constant even though the front drum may be following an undulating roof profile. The rear drum referencing mechanism continually monitors the distance from the mine roof to the floor for the present cut. This system provides a signal to control a constant depth of cut. The last cut follower mechanism continually monitors the distance from the mine roof of the prior cut to the cutting drum. This latter system provides a signal to minimize the step height in the roof between cuts. The dynamic response of this hydraulic-pneumatic and mechanical system is analyzed to determine accumulator size and precharge pressure.

  14. Application of MASW method in studies on changes of soil elastic parameters over subsidence trough development during longwall exploitation (United States)

    Mendecki, Maciej; Jochymczyk, Krzysztof


    The MASW method interpretation was applied to analyze 37 measurements which had been carried out to investigate spatial and temporal changes of elastic parameters in subsurface layers during extracting the coal bed. The seismic measurements were performed using the Terraloc apparatus containing 12 channels connected with 10 Hz geophones. 5 survey profiles were formed into a rosette with arms arranged relative about 45 degrees to each other. The research area was located in the Main Anticline, Upper Silesian Coal Basin, Southern Poland. The rosette was placed over the 201 longwall belonged to "Katowice - Kleofas" Coal Mine. Shallow geological structure consisted of subsurface soft layer (several meters) covered consolidated Carboniferous complex. Data interpretation were executed in winMASW software using the genetic algorithms to invert observed Rayleigh dispersion curve into S-wave velocity vertical profiles. In addition, the inversion allowed to determine parameters such as: density, thickness, shear modulus. The seismic study were carried out during total exploitation of the coal bed and for next 8 month after completion of mining works. Longer seismic observations than the mining works were due to a subsidence trough development over coal bed because the longwall face passage and subsidence trough development were shifted in time and it reached about 3 month. This time was needed to appear the subsidence trough on surface what was confirmed by leveling measurements. The longwall face had passed beneath the rosette in December, 1999 and in March, 2000 a sharp velocity drop on each profile was noticed. Next, a sudden velocity increase appeared in subsurface layer after the velocity drop. The changes of density and shear modulus was also remarked during the same period. At the beginning the sudden drop in velocity and other elastic parameters was associated with tension appeared on borders of subsidence trough. Then the geophysical profiles were in the compressive

  15. Powered supports for longwall mining systems using hydraulic or pneumatic stowing. Obudowy zmechanizowane do systemow wybierania scian z zastosowaniem podsadzki hydraulicznej i pneumatycznej

    Energy Technology Data Exchange (ETDEWEB)

    Pretor, W.; Sroka, H.; Trembaczewski, H. (Centrum Mechanizacji Gornictwa (Poland))


    Reviews Polish powered supports intended for equipment sets used at longwalls mined with hydraulic or pneumatic stowing. Specifications of powered supports of the FAZOS series are presented. Technical considerations and requirements met during development of subsequent modifications of the FAZOS supports are described. The first longwalls equipped with supports designed for mining with pneumatic stowing were put into operation in Poland in 1985. The supports used were the Polish FAZOS-17/277-POp, Hemscheidt BV-4700-13,5/26,5 and Czechoslovak MV-1 supports. The FAZOS supports developed in 1987 are also discussed. Stowing equipment used together with the various types of supports is described. Future developments are considered. Diagrammatic drawings of supports are presented.

  16. Observation measurement and analysis on strata pressure of fully mechanized longwall caving face in special thick seam

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.; Wu, J.; Li, B.; Liu, S.; Liang, J. [China University of Mining and Technology (China). Beijing Graduate School


    This paper introduces a fully mechanized longwall caving mining face in Weijiadi Mine, Gansu Province. The seam to be mined was a special thick seam with potential outbursts of coal and gas and spontaneous combustion. The average thickness of the seam was 12 m. The seam was mined with a one-pass method. Due to the softness of the coal body and the roof and floor, the strata support and bearing area of the coal face had to be moved in advance, slowly when the gateways became seriously deformed. The slow advancing had provided a condition for the spontaneous combustion of the residual coal in the goaf. Through observation, measurement and analysis of the strata in the coal face; the results revealed a rational support with hydraulic powered supports mainly to control the roof and the coal face, the distance of the periodical strata pressure was 20 to 35 m. The support resistance of the one-pass caving face was higher than the slicing mining face. The conveyor gateway of the caving face was seriously deformed and an advanced support of the gateway should have been made. 6 figs.

  17. Three-dimensional experimental study of loose top-coal drawing law for longwall top-coal caving mining technology

    Directory of Open Access Journals (Sweden)

    Jiachen Wang


    Full Text Available Based on the loose medium flow field theory, the loose top-coal drawing law of longwall top-coal caving (LTCC mining technology is studied by using self-developed three-dimensional (3D test device. The loose top-coal drawing test with shields and the controlled test without shields are performed in the condition without any boundary effect. Test results show that shields will cause reduction in drawing volume of coal in the LTCC mining. The deflection phenomenon of drawing body is also observed in the controlled test, which is verified that the deflection of drawing body is caused by shield. It is found that the deflection angle decreases with increasing caving height, with the maximum value of αtail and the minimum value of 0. In addition, the formula to calculate the drawing volume is proposed subsequently. The deflection of drawing body is numerically simulated using particle flow code PFC3D and the proposed formula to calculate drawing volume in LTCC is also verified.


    Directory of Open Access Journals (Sweden)

    Nikodem SZLĄZAK


    Full Text Available Underground fires in coal mines belong to the most common hazards, the exposure to which frequently requires long term and costly rescue operations. It is mainly connected with the specific character of underground excavations which have limited volume. This makes the maximum permissible concentration of harmful gases rapidly exceeded and may also cause changes in air flow direction. The most certain way of improving a safety situation in Polish coal mining indus-try is taking early prevention steps. One of the prevention methods is inertisation of the atmosphere in longwall goaf. These activities rely on partial or total replacement of air or combustible atmosphere by inert gas. Thanks to them the risk of spontaneous fires hazard and gas explosion decreases. The main reason for the use of inert gases is to reduce the oxygen content to a limit which prevents further development of fire. This article presents methods for assessing inert gas to replace oxygen in the atmosphere in goaf.

  19. Evaluation of the rockburst potential in longwall coal mining using passive seismic velocity tomography and image subtraction technique (United States)

    Hosseini, Navid


    Rockburst is a typical dynamic disaster in underground coal mines which its occurrences relate to the mechanical quality of coal seam and surrounding rock mass and also the condition of stress distribution. The main aim of this paper is to study the potential of rockburst in a longwall coal mine by using of passive seismic velocity tomography and image subtraction technique. For this purpose, first by mounting an array of receivers on the surface above the active panel, the mining-induced seismic data as a passive source for several continuous days were recorded. Then, the three-dimensional tomograms using simultaneous iteration reconstruction technique (SIRT) for each day are created and by employing the velocity filtering, the overstressed zones are detected. In addition, the two-dimensional seismic velocity tomograms in coal seam level by slicing the three-dimensional tomograms are obtained. Then the state of stress changes in successive days by applying the image subtraction technique on these two-dimensional tomograms is considered. The results show that the compilation of filtered three-dimensional tomograms and subtracted images is an appropriate approach for detecting the overstressed zones around the panel and subsequent evaluation of rockburst potential. The research conclusion proves that the applied approach in this study in combination with field observations of rock mass status can effectively identify the rockburst-prone areas during the mining operation and help to improve the safety condition.

  20. Evaluate fundamental approaches to longwall dust control: Subprogram A, Passive barriers/spray air movers for dust control

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, J.; Ruggieri, S.


    One method to control shearer-generated dust on longwall faces is to confine the dust cloud to the face area and keep it away from face personnel as it travels downstream over the shearer body and beyond. Passive barriers can help this process by partitioning the airflow around the shearer into a clean split and a contaminated split. In addition, water sprays used as air movers (such as the Shearer Clearer developed on another USBM contract) aid the air partitioning process. A variety of passive barrier designs were developed and evaluated in the laboratory, tested in conjunction with the Shearer Clearer. The results showed that a headgate splitter arm'' to begin the airsplitting process is a vital part of a passive barrier system, whether or not a spray air moving system is also used on the shearer. A simple gob-side passive barrier along the edge of the shearer was also shown to help partition the airflow. Underground evaluations were conducted on a combination passive barrier/spray air moving system. The results confirmed the importance of the headgate splitter arm and showed that a gob-side barrier was very effective when used on shearers with ineffective external spray systems. The gob-side barrier was unnecessary, however, on shearers equipped with effective external air moving systems such as the Shearer Clearer. 32 figs., 14 tabs.

  1. Application of underground microseismic monitoring for ground failure and secure longwall coal mining operation: A case study in an Indian mine (United States)

    Ghosh, G. K.; Sivakumar, C.


    Longwall mining technique has been widely used around the globe due to its safe mining process. However, mining operations are suspended when various problems arise like collapse of roof falls, cracks and fractures propagation in the roof and complexity in roof strata behaviors. To overcome these colossal problems, an underground real time microseismic monitoring technique has been implemented in the working panel-P2 in the Rajendra longwall underground coal mine at South Eastern Coalfields Limited (SECL), India. The target coal seams appears at the panel P-2 within a depth of 70 m to 76 m. In this process, 10 to 15 uniaxial geophones were placed inside a borehole at depth range of 40 m to 60 m located over the working panel-P2 with high rock quality designation value for better seismic signal. Various microseismic events were recorded with magnitude ranging from -5 to 2 in the Richter scale. The time-series processing was carried out to get various seismic parameters like activity rate, potential energy, viscosity rate, seismic moment, energy index, apparent volume and potential energy with respect to time. The used of these parameters helped tracing the events, understanding crack and fractures propagation and locating both high and low stress distribution zones prior to roof fall occurrence. In most of the cases, the events were divided into three stage processes: initial or preliminary, middle or building, and final or falling. The results of this study reveal that underground microseismic monitoring provides sufficient prior information of underground weighting events. The information gathered during the study was conveyed to the mining personnel in advance prior to roof fall event. This permits to take appropriate action for safer mining operations and risk reduction during longwall operation.

  2. A methodology for determining the evolution law of gob permeability and its distributions in longwall coal mines

    International Nuclear Information System (INIS)

    Zhang, Cun; Tu, Shihao; Zhang, Lei; Bai, Qingsheng; Yuan, Yong; Wang, Fangtian


    In order to understand the permeability evolution law of the gob by mining disturbances and obtain the permeability distribution of the fully compacted gob, comprehensive methods including theoretical analyses of monitoring data and numerical simulation are used to determine the permeability of gobs in the mining process. Based on current research, three zones of the vertical stress and permeability in the gob are introduced in this article, which are the caving rock mass accumulation zone, the gradually compacted zone and the fully compacted zone. A simple algorithm is written by using FISH language to be imported into the reservoir model. FISH language is an internal programming language in FLAC3D. It is possible to calculate the permeability at each zone with this algorithm in the mining process. Besides, we analyze the gas flow rates from seven gob gas ventholes (GGV) located on a longwall face operated in a mine of a Huainan coalfield in Huainan City, China. Combined with Darcy’s law, a calculation model of permeability around GGV in the gob is proposed. Using this model, the evolution law of permeability in the gob is deduced; the phases of permeability evolution are the decline stage and the stable stage. The result of the vertical stress monitoring data and good fitting effect of the permeability to the experimental data show that the permeability decline caused by the compaction of the gob is the principal reason for the decline stage. The stable stage indicates that the gob has been fully compacted, and the average period of full gob compaction is 47.75 d. The permeability in the middle of the compacted gob is much smaller than the permeability on the edge of the gob which presents an O shape trend. Besides, the little difference among the results of the numerical simulation, the permeability calculation model and other commonly used calculation models validate the correctness of the permeability calculation model and numerical simulation results

  3. Stochastic modeling of gob gas venthole production performances in active and completed longwall panels of coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Karacan, C. Oezgen [NIOSH, Office of Mine Safety and Health Research, Pittsburgh, PA (United States); Luxbacher, Kray [Virginia Tech, Dept. of Mining and Minerals Engineering, Blacksburg, VA (United States)


    Gob gas ventholes (GGVs) are an integral part of longwall coal mining operations, enhancing safety by controlling methane in underground workings. As in many disciplines in earth sciences, uncertainties due to the heterogeneity of geologic formations exist. These uncertainties, and the wide range of mining and venthole operation parameters, lead to performance variability in GGVs. Random variations in parameters affecting GGV performance and influencing parameters that cannot be quantified sufficiently due to lack of information limit deterministic GGV models and even introduce error in severe cases. Therefore, evaluation of GGV performance data and the uncertainty in input parameters is valuable for understanding the variability in GGV production and for designing them accordingly. This paper describes a practical approach for implementing stochastic determination of GGV production performances and for generalizing the prediction capability of deterministic models. Deterministic site-specific models were derived by using the GGV module in the recently developed MCP (Methane Control and Prediction) software suite. These models were generated using multi-parameter regression techniques and were then improved by inclusion of extra input parameters that eliminated the site dependency and improved the predictions. Statistical distributions of input parameters in these models were quantified and tested with the Kolmogorov-Smirnov goodness-of-fit technique. Next, Monte Carlo simulations were performed using these distributions and generalized results for GGV performances were generated. The results of this work indicate that this approach is a promising method of representing the variability in GGV performances and to improve the limited and site-specific character of the deterministic models. (author)


    Directory of Open Access Journals (Sweden)

    Jarosław BRODNY


    Full Text Available One of the most dangerous and most commonly present risks in hard coal mines is methane hazard. During exploitation by longwall system with caving, methane is emitted to mine heading from the mined coal and coal left in a pile. A large amount of methane also flows from neighboring seams through cracks and fissures formed in rock mass. In a case of accumulation of explosive methane concentration in goaf zone and with appropriate oxygen concentration and occur-rence of initials (e.g. spark or endogenous fire, it may come to the explosion of this gas. In the paper there are present-ed results of numerical analysis of mixture of air and methane streams flow through the real heading system of a mine, characterized by high methane hazard. The aim of the studies was to analyze the ventilation system of considered head-ing system and determination of braking zones in goaf zone, in which dangerous and explosive concertation of methane can occur with sufficient oxygen concentration equal to at least 12%. Determination of position of these zones is neces-sary for the selection of appropriate parameters of the ventilation system to ensure safety of the crew. Analysis of the scale of methane hazard allows to select such a ventilation system of exploitation and neighboring headings that ensures chemical composition of mining atmosphere required by regulation, and required efficiency of methane drainage. The obtained results clearly show that numerical methods, combined with the results of tests in real conditions can be suc-cessfully used for the analysis of variants of processes related to ventilation of underground mining, and also in the anal-ysis of emergency states.

  5. Blocking Underhand Attacks by Hidden Coalitions (Extended Version)


    Cristani, Matteo; Karafili, Erisa; Viganò, Luca


    Similar to what happens between humans in the real world, in open multi-agent systems distributed over the Internet, such as online social networks or wiki technologies, agents often form coalitions by agreeing to act as a whole in order to achieve certain common goals. However, agent coalitions are not always a desirable feature of a system, as malicious or corrupt agents may collaborate in order to subvert or attack the system. In this paper, we consider the problem of hidden coalitions, wh...

  6. The Detection and Characterization of Urbanization, Industrialization, and Longwall Mining Impacts on Forest Ecosystems Through the Use of GiS and Remote Sensing Techniques (United States)

    Pfeil-McCullough, Erin Kathleen

    Urbanization has far reaching and significant effects on forest ecosystems, directly through urban development and indirectly through supportive processes such as coal mining and agriculture. Urban processes modify the landscape leading to altered hillslope hydrology, increased disturbance, and the introduction of non-native forest pathogens. This dissertation addresses several challenges in our ability to detect these urbanization impacts on forests via geospatial analyses. The role of forests in urban hydrological processes has been extensively studied, but the impacts of urbanized hydrology on forests remain poorly examined. This dissertation documented impacts to hydrology and forests at variety of temporal and spatial scales: 1) A geospatial comparison of the historic and contemporary forests of Allegheny County, Pennsylvania revealed substantial shifts in tree species, but less change in the species soil moisture preference. These results document additional evidence that increased heterogeneity in urban soil moisture alters forest structure. 2) To examine soil moisture changes, impacts of longwall mine subsidence were assessed by using a Landsat based canopy moisture index and hot spot analysis tools at the forest patch scale. Declines in forest canopy moisture were detected over longwall mines as mining progressed through time, and results contradicted assumptions that the hydrological impacts overlying LMS recover within 4-5 years following subsidence of undermined land. 3) Utilizing a landslide susceptibility model (SINMAP), increases in landslide susceptibility were predicted in Pittsburgh, PA based on several scenarios of ash tree loss to the emerald ash borer (EAB), a bark beetle that rapidly kills ash trees. This model provides a tool to predict changes in landslide susceptibility following tree loss, increasing the understanding of urban forest function and its role in slope stability. Detecting how urbanized hydrology impacts forest health, function

  7. Mechanism and Prevention of a Chock Support Failure in the Longwall Top-Coal Caving Faces: A Case Study in Datong Coalfield, China

    Directory of Open Access Journals (Sweden)

    Zhu Li


    Full Text Available Longwall chock support failures seriously restrain the safety and high-efficiency of mining of extra thick coal seams, as well as causing a great waste of coal resources. During longwall top-coal caving (LTCC, the influential effect of the properties and the movement regulation of top-coal on strata behavior cannot be ignored, since the top-coal is the medium through which the load of the overlying strata is transferred to the chock supports. Taking Datong coalfield as an example, the mechanism of a chock support failure in the LTCC face was investigated. Research findings indicated that the hard top-coal and insufficient chock support capacity were primary reasons for chock support failure accidents. On account of the field-measured results, a new method to determine support capacity was proposed, which fully took the impact of the top-coal strength into consideration. The calculation revealed that the required support capacity had exceeded the existing production maximum, at about 22,000 KN. Since it was unrealistic to simply increase chock support capacity, other approaches, according to the theoretical analysis, were proposed, such as lowering the integrity and strength of the top-coal, and upgrading its crushing effect to weaken the support load effectively during the weighting period, which reduces the likelihood of chock support accidents occurring. Based on this, hydraulic fracturing for hard top-coal and optimization of the caving process (chock supports raised up and down repeatedly by manual operation before moving forward were presented. The proposed solutions were successfully applied in LTCC-west8101 for subsequent mining and achieved substantial benefits. The above research provides valuable references and ideas for the control of strata behavior to ensure safe and highly efficient mining in extremely thick and hard coal seams with the LTCC method.

  8. Development of ZL400 Mine Cooling Unit Using Semi-Hermetic Screw Compressor and Its Application on Local Air Conditioning in Underground Long-Wall Face (United States)

    Chu, Zhaoxiang; Ji, Jianhu; Zhang, Xijun; Yan, Hongyuan; Dong, Haomin; Liu, Junjie


    Aiming at heat injuries occurring in the process of deep coal mining in China, a ZL400 mine-cooling unit employing semi-hermetic screw compressor with a cooling capacity of 400 kW is developed. This paper introduced its operating principle, structural characteristics and technical indexes. By using the self-built testing platform, some parameters for indication of its operation conditions were tested on the ground. The results show that the aforementioned cooling unit is stable in operation: cooling capacity of the unit was 420 kW underground-test conditions, while its COP (coefficient of performance) reached 3.4. To address the issue of heat injuries existing in No. 16305 U-shaped long-wall ventilation face of Jining No. 3 coal mine, a local air conditioning system was developed with ZL400 cooling unit as the system's core. The paper presented an analysis of characteristics of the air current flowing in the air-mixing and cooling mode of ZL400 cooling unit used in air intake way. Through i-d patterns we described the process of the airflow treatment, such as cooling, mixing and heating, etc. The cooling system decreased dry bulb temperature on working face by 3°C on average and 3.8°C at most, while lowered the web bulb temperature by 3.6°C on average and 4.8°C at most. At the same time, it reduced relative humidity by 5% on average and 8.6% at most. The field application of the ZL400 cooling unit had gain certain effects in air conditioning and provided support for the solution of mine heat injuries in China in terms of technology and equipment.

  9. Modelling the behaviour of caving by the distinct element method: the case of longwall mining face. Modelisation du comportement du foudroyage par la methode des elements distincts: cas d'une longue taille

    Energy Technology Data Exchange (ETDEWEB)

    Al Heib, M.M.; Piguet, J.P.; Slimane, K.B. (INERIS, Nancy (France). Ecole des Mines de Nancy)


    The model simulates a longwall mining face. The behaviour of rock mass can be studied by using the distinct element methods. The authors are using numerical models for studying the interaction between the rock mass and the mining zone. The model particularly analyses the processes of the goaf phenomena but not the complete mechanism. The blocks' movement and the consequences to the environment (subsidence, stresses modification, etc...) are studied. The conditions for the first movement of goaf, the evolution and the concerned volume of rock are analysed. The methodology adopted follows three main steps: a consolidation phase without excavation in which the induced joints have a very high friction angle; simulation of longwall mining excavation; and the goaf processes. The joints of the goaf zone have a very small friction angle. The validation of the results is set up between the curve of in situ subsidence measurements and the values of a subsidence model. Thus, a comparison has been achieved between the results of finite element models and distinct element models. The results are encouraging for planification problems. 10 refs., 7 figs., 2 tabs.

  10. Inference of strata separation and gas emission paths in longwall overburden using continuous wavelet transform of well logs and geostatistical simulation (United States)

    Karacan, C. Özgen; Olea, Ricardo A.


    Prediction of potential methane emission pathways from various sources into active mine workings or sealed gobs from longwall overburden is important for controlling methane and for improving mining safety. The aim of this paper is to infer strata separation intervals and thus gas emission pathways from standard well log data. The proposed technique was applied to well logs acquired through the Mary Lee/Blue Creek coal seam of the Upper Pottsville Formation in the Black Warrior Basin, Alabama, using well logs from a series of boreholes aligned along a nearly linear profile. For this purpose, continuous wavelet transform (CWT) of digitized gamma well logs was performed by using Mexican hat and Morlet, as the mother wavelets, to identify potential discontinuities in the signal. Pointwise Hölder exponents (PHE) of gamma logs were also computed using the generalized quadratic variations (GQV) method to identify the location and strength of singularities of well log signals as a complementary analysis. PHEs and wavelet coefficients were analyzed to find the locations of singularities along the logs. Using the well logs in this study, locations of predicted singularities were used as indicators in single normal equation simulation (SNESIM) to generate equi-probable realizations of potential strata separation intervals. Horizontal and vertical variograms of realizations were then analyzed and compared with those of indicator data and training image (TI) data using the Kruskal-Wallis test. A sum of squared differences was employed to select the most probable realization representing the locations of potential strata separations and methane flow paths. Results indicated that singularities located in well log signals reliably correlated with strata transitions or discontinuities within the strata. Geostatistical simulation of these discontinuities provided information about the location and extents of the continuous channels that may form during mining. If there is a gas

  11. Chasing U-Boats and Hunting Insurgents: Lessons from an Underhand Way of War

    National Research Council Canada - National Science Library

    Breemer, Jan S


    .... Winston Churchill, then the Royal Navy's political head, was not willing to go quite that far, yet at one point during World War I, he ordered that captured U-boat crews be treated as criminals, not prisoners of war...

  12. Unique Project of Single-Cutting Head Longwall Shearer Used for Thin Coal Seams Exploitation / Projekt Jednoorganowego Kombajnu ŚCIANOWEGO O Specjalnej Konstrukcji Przeznaczonego do Eksploatacji POKŁADÓW Cienkich (United States)

    Bołoz, Łukasz


    Problem of thin hard coal seams exploitation, including chosen data related with their resources in Poland, has been discussed in the introduction of the present study. On the basis of actually operated machines the assumptions, which should be satisfied by the longwall shearer used for exploitation of thin hard coal seams, have been made. A project of such longwall shearer combined with band conveyor and mechanized longwall support, including description of the machine operation technology and analysis of possible day output achievement, have been presented. Polska dysponuje stosunkowo dużymi zasobami surowców energetycznych, a ciągle rosnące zapotrzebowanie na energię skłania do ich racjonalnego wykorzystywania. Jedną z możliwości takiego racjonalnego gospodarowania zasobami naturalnymi jest eksploatacja węgla kamiennego z pokładów cienkich. W związku z wybieraniem coraz cieńszych pokładów węgla, zalegających bardzo głęboko, w trudnych warunkach górniczo-geologicznych napotyka się na duże problemy związane z uzyskaniem wymaganej wydajności wydobycia przy użyciu stosowanych aktualnie metod. Przyjmuje się, ze pokłady cienkie to takie o miąższości od 1.0 m do 1.5 m i właśnie ta niewielka wysokość wyrobiska ścianowego powoduje szereg ograniczeń związanych z efektywną eksploatacją węgla. Na podstawie dostępnych danych określono, że ilości węgla kamiennego w cienkich pokładach wynosi około 600 mln Mg. Znaczna część pokładów cienkich w ostatnich latach została przeklasyfikowana na nieprzemysłowe, co pozwala stwierdzić, że rzeczywista ilość węgla w pokładach cienkich jest znacznie większa. Na podstawie analizy wad i zalet jak i danych technicznych produkowanych obecnie maszyn, określono wytyczne i założenia do nowego rozwiązania maszyny urabiającej przeznaczonej do wydobywania węgla w ścianach niskich. Kombajn do eksploatacji cienkich pokładów powinien spełniać następujące wymagania (Bołoz, 2012

  13. Geostatistical coal quality control in longwall mining

    Energy Technology Data Exchange (ETDEWEB)

    Hindistan, Mehmet Ali; Tercan, Abdullah Erhan; Uenver, Bahtiyar [Hacettepe University, Dept. of Mining Engineering, Beytepe, 06800 Ankara (Turkey)


    The coal quality is an important aspect of coal mine planning. This paper presents a case study in which an underground coal mine is faced with severe penalty cost because it does not consider in situ coal quality control at all. To help short term planning of the coal production the mean calorific values of the blocks inside the production panels are estimated by kriging. The estimated calorific values are compared with those obtained from actual production. The ratio of the calorific values of actual production to estimated values is found to be 0.73 in average due to adverse effect of dilution on the quality of run-of-mine coal. This study reveals the importance of geostatistical block modelling in short term mine planning. (author)

  14. An under-hand steering wheel grasp produces significant injury risk to the upper extremity during airbag deployment

    NARCIS (Netherlands)

    Hoof, J.F.A.M. van; Atkinson, P.; Telehowski, P.; Bir, C.


    Recent laboratory investigations suggest that a deploying airbag may fracture the forearm. These studies positioned the arm in an overhand grasp placing the forearm over the airbag module. However, there is little published data on how drivers grip the steering wheel and the general proximity of the

  15. Analysis and Optimization of Entry Stability in Underground Longwall Mining

    Directory of Open Access Journals (Sweden)

    Yubing Gao


    Full Text Available For sustainable utilization of limited coal resources, it is important to increase the coal recovery rate and reduce mine accidents, especially those occurring in the entry (gateroad. Entry stabilities are vital for ventilation, transportation and other essential services in underground coal mining. In the present study, a finite difference model was built to investigate stress evolutions around the entry, and true triaxial tests were carried out at the laboratory to explore entry wall stabilities under different mining conditions. The modeling and experimental results indicated that a wide coal pillar was favorable for entry stabilities, but oversize pillars caused a serious waste of coal resources. As the width of the entry wall decreased, the integrated vertical stress, induced by two adjacent mining panels, coupled with each other and experienced an increase on the entry wall, which inevitably weakened the stability of the entry. Therefore, mining with coal pillars always involves a tradeoff between economy and safety. To address this problem, an innovative non-pillar mining technique by optimizing the entry surrounding structures was proposed. Numerical simulation showed that the deformation of the entry roof decreased by approximately 66% after adopting the new approach, compared with that using the conventional mining method. Field monitoring indicated that the stress condition of the entry was significantly improved and the average roof pressure decreased by appropriately 60.33% after adopting the new technique. This work provides an economical and effective approach to achieve sustainable exploitation of underground coal resources.

  16. Particle velocity generated by rockburst during exploitation of the longwall and its impact on the workings

    Czech Academy of Sciences Publication Activity Database

    Holub, Karel; Rušajová, Jana; Holečko, J.


    Roč. 48, č. 6 (2011), s. 942-949 ISSN 1365-1609 Institutional research plan: CEZ:AV0Z30860518 Keywords : Ostrava-Karviná Coal Basin * rockburst * particle velocity * working damage Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.272, year: 2011

  17. Single-chip microcomputer based protection, diagnostic and recording system for longwall shearers

    Energy Technology Data Exchange (ETDEWEB)

    Heyduk, A.; Krasucki, F. (Politechnika Slaska, Gliwice (Poland). Katedra Elektryfikacji i Automatyzacji Gornictwa)


    Presents a concept of microcomputer-aided operation, protection, diagnostics and recording for shearer loaders. A two-stage mathematical model is suggested and explained. The model represents the thermal processes that determine the overcurrent protection of drive motors. Circuits for monitoring fuses, supply voltages, contacts, relays, contactors and electro-hydraulic distributors with the use of transoptors are shown. Recording characteristic operation parameters of a shearer loader during the 5 minutes before a failure is proposed. Protection, diagnosis and control functions are suggested as additional functions to the microcomputer-aided system of shearer loader control being developed at the Silesian Technical University. The system is based on the NECmicroPD 78310 microprocessor. 10 refs.

  18. Longwall mining and surface deformation – lessons learned from dInSAR measurements

    CSIR Research Space (South Africa)

    Engelbrecht, Jeanine


    Full Text Available including 1) subsidence related to mining and groundwater abstraction, 2) deformation following earthquake events, 3) monitoring of landslides and slope stability, 4) monitoring the stability of infrastructure and large engineering works, and 5) monitoring...

  19. Measurement and prediction of cutting forces and vibrations on longwall shearers

    Energy Technology Data Exchange (ETDEWEB)

    Bulent Tiryaki [CRCMining (Australia)


    CRCMining has developed the Cutting Head Performance Analysis Software (CPAS) to predict cutter motor power, ranging arm reaction forces, and vibrations for different drum designs, coal seams, and shearer operational conditions. This project describes the work on THE DBT EL3000 shearer at Beltana to validate/update CPAS by measuring the cutter motor power, ranging arm vibrations, and reaction forces through an online data acquisition system called Cutting Head Performance Monitoring System (CPMS). This system records the outputs of six strain gauge bridges, six accelerometers, and two pressure transducers on ranging arms during underground coal production. CPAS2 has then been developed in order to eliminate the needs for performing coal cutting tests for the target coal seam. CPAS2 simulations for cutter motor power, vertical reaction force, and vibrations were also close to those measured in the trials. CRCMining will release the CPAS code including fully functioning software code on CD to Australian coal mining industry.

  20. Comparison of coarse coal dust sampling techniques in a laboratory-simulated longwall section. (United States)

    Patts, Justin R; Barone, Teresa L


    Airborne coal dust generated during mining can deposit and accumulate on mine surfaces, presenting a dust explosion hazard. When assessing dust hazard mitigation strategies for airborne dust reduction, sampling is done in high-velocity ventilation air, which is used to purge the mining face and gallery tunnel. In this environment, the sampler inlet velocity should be matched to the air stream velocity (isokinetic sampling) to prevent oversampling of coarse dust at low sampler-to-air velocity ratios. Low velocity ratios are often encountered when using low flow rate, personal sampling pumps commonly used in underground mines. In this study, with a goal of employing mine-ready equipment, a personal sampler was adapted for area sampling of coarse coal dust in high-velocity ventilation air. This was done by adapting an isokinetic nozzle to the inlet of an Institute of Occupational Medicine (Edinburgh, Scotland) sampling cassette (IOM). Collected dust masses were compared for the modified IOM isokinetic sampler (IOM-MOD), the IOM without the isokinetic nozzle, and a conventional dust sampling cassette without the cyclone on the inlet. All samplers were operated at a flow rate typical of personal sampling pumps: 2 L/min. To ensure differences between collected masses that could be attributed to sampler design and were not influenced by artifacts from dust concentration gradients, relatively uniform and repeatable dust concentrations were demonstrated in the sampling zone of the National Institute for Occupational Safety and Health experimental mine gallery. Consistent with isokinetic theory, greater differences between isokinetic and non-isokinetic sampled masses were found for larger dust volume-size distributions and higher ventilation air velocities. Since isokinetic sampling is conventionally used to determine total dust concentration, and isokinetic sampling made a difference in collected masses, the results suggest when sampling for coarse coal dust the IOM-MOD may improve airborne coarse dust assessments over "off-the-shelf" sampling cassettes.

  1. A Study of Mining-induced seismicity in Czech Mines with longwall coal exploitation

    Czech Academy of Sciences Publication Activity Database

    Holub, Karel


    Roč. 43, č. 1 (2007), s. 32-39 ISSN 1062-7391 R&D Projects: GA ČR GA205/03/0999 Institutional research plan: CEZ:AV0Z30860518 Keywords : induced seismicity * rockburst hazard * coal mines Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.293, year: 2007

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

    Czech Academy of Sciences Publication Activity Database

    Taraba, B.; Michalec, Zdeněk


    Roč. 90, č. 8 (2011), s. 2790-2797 ISSN 0016-2361 R&D Projects: GA ČR GA105/06/0630 Grant - others:GA ČR(CZ) GA105/08/1414 Institutional research plan: CEZ:AV0Z30860518 Keywords : coal oxidation * spontaneous heating * CFD modelling * Fluent Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 3.248, year: 2011

  3. Stability Control of Retained Goaf-Side Gateroad under Different Roof Conditions in Deep Underground Y Type Longwall Mining

    Directory of Open Access Journals (Sweden)

    Zhiyi Zhang


    Full Text Available Stability of the retained goaf-side gateroad (RGSG is influenced mainly by the movements of the roof strata near coal seam after coalface passes by. To make effective controlling technology for the stability of the RGSG, we analyze the roof structure over the RGSG to illustrate the mechanism causing the RGSG instability under different roof conditions. We then examine the dynamic evolution of the deformation and abutment stress in the rock surrounding the RGSG during coal seam mining, using the FLAC3D numerical software to reveal the instability characteristics of the RGSG under different roof conditions. Next, corresponding stability controlling technologies for the RGSGs are proposed and tested in three typical deep underground coalmines. Results show that: sink and rotation of the roof cantilever over the RGSG impose severer influence on the stability of the RGSG. The RGSG suffers disturbances three times during the coal-seam mining, and the deformation and abutment stress in the rock surrounding the RGSG increase significantly when the main roof becomes thicker and the immediate roof becomes thinner. Staged support technology involving grout cable bolts has better controlling results of the RGSG stability than that composed of conventional rock bolts, when the RGSG is beneath weak immediate roof with large thickness. Roof structure optimizing technology involving pre-split technology can improve the stability of the RGSG effectively when the RGSG is covered by hard main roof with large thickness directly.

  4. 10th international conference on ground control in mining - proceedings

    International Nuclear Information System (INIS)

    Peng, S.S.


    36 papers are presented covering topics that include longwall pillar design, assessment of underground structural design, load and convergence measurements in longwall faces, shield strata interaction, longwall shield recovery, roof control in longwall mining, anchor resin system, thrust bolting, roof bolts, cable slings, roof support in retreat mining, coal bump prediction, delineation of abandoned workings, stability of coal mine openings, mining under rivers, rock strength determination, subsidence prediction and measurement, drag picks, measuring roof convergence, and finite element modelling of subsidence

  5. Impact of high-performance longwalls on the strata and on the surface; Der Einfluss von Hochleistungsstreben auf das Gebirge und die Tagesoberflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Sroka, A. [Technische Univ. Bergakademie Freiberg, Freiberg (Germany)


    In this article is presented an influence of high-performance long wall on the earth's surface and on the rock mass. The phenomenon of the mining-damage on the buildings, unsteady rock mass reaction and of mining-induced microseismics was described and analyzed. (orig.) [German] Im Beitrag wird der Einfluss der Hochleistungstreben auf die Objekte der Tagesoberflaeche und auf das Gebirge dargestellt. Es werden die Phaenomene der Bergschaeden an Gebaeuden, der unstetigen Bodenreaktionen und der abbauinduzierten Seismik beschrieben und analysiert.

  6. Estimating of aquifer parameters from the single-well water-level measurements in response to advancing longwall mine by using particle swarm optimization (United States)

    Buyuk, Ersin; Karaman, Abdullah


    We estimated transmissivity and storage coefficient values from the single well water-level measurements positioned ahead of the mining face by using particle swarm optimization (PSO) technique. The water-level response to the advancing mining face contains an semi-analytical function that is not suitable for conventional inversion shemes because the partial derivative is difficult to calculate . Morever, the logaritmic behaviour of the model create difficulty for obtaining an initial model that may lead to a stable convergence. The PSO appears to obtain a reliable solution that produce a reasonable fit between water-level data and model function response. Optimization methods have been used to find optimum conditions consisting either minimum or maximum of a given objective function with regard to some criteria. Unlike PSO, traditional non-linear optimization methods have been used for many hydrogeologic and geophysical engineering problems. These methods indicate some difficulties such as dependencies to initial model, evolution of the partial derivatives that is required while linearizing the model and trapping at local optimum. Recently, Particle swarm optimization (PSO) became the focus of modern global optimization method that is inspired from the social behaviour of birds of swarms, and appears to be a reliable and powerful algorithms for complex engineering applications. PSO that is not dependent on an initial model, and non-derivative stochastic process appears to be capable of searching all possible solutions in the model space either around local or global optimum points.

  7. Technological patterns of preventive relaxation of workings

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L.L.; Bakhtin, A.F.; Zel' vyanskii, M.Sh. (Donetskaya Proektnaya Kontora (USSR))


    Presents stress relaxation patterns of workings. The patterns are used at horizon layouts and panel development of mine-take in stone inclines, boundary entries, mine drainage galleries and main galleries. The stress relaxation variants are: stress relaxing longwalls with complete mining with two or three winning galleries, longwalls worked by long pillars on the strike, and longwalls worked with advance mining on the strike. The individual variants differ by the ventilation system adopted.

  8. 30 CFR 75.817 - Cable handling and support systems. (United States)


    ... High-Voltage Longwalls § 75.817 Cable handling and support systems. Longwall mining equipment must be provided with cable-handling and support systems that are constructed, installed and maintained to minimize... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Cable handling and support systems. 75.817...

  9. Coal mining equipment

    International Nuclear Information System (INIS)

    Stein, R.R.; Martin, T.W.


    The word in longwall components is big, and these larger components have price tags to match. The logic behind the greater investment is that it will yield high production rates and good uptime statistics. This is true in most cases. More important than single-shift tonnage records, average shift production continues to climb upwards. This paper reports on the quality, and more significantly, the quantity of service supplied for long-wall equipment, which has reached levels that would have been seen as unachievable when longwall mining was first introduced in the U.S. The school of thought then was that longwall would increase productivity in part by reducing the number of production units and thus reducing the number of personnel employed underground. The expectation of fewer employees turned out to be unrealistic. That was probably one reason that some early attempts to install longwall system looked more like failures than vision of the future

  10. Remotely Piloted Aircraft and War in the Public Relations Domain (United States)


    underhanded or de- ceitful. This article concerns itself with the genus of information, within which propaganda is a species, and therefore addresses all in... network may overlap (regarding a specific RPA strike, for example), that news network is not participating in al-Qaeda’s PR campaign. (Indeed, if it...the number of lives lost or the economic and social damage inflicted, but in the amount of media attention they are able to garner.”11 In what has

  11. 75 FR 34486 - Petitions for Modification (United States)


    ... setting will also be sealed or locked; (4) replacement instantaneous trip units, used to protect pump... and de-energize the longwall mining machine at 1.5% methane. Methane levels will also be monitored by...

  12. Mining machinery - bigger and better

    Energy Technology Data Exchange (ETDEWEB)



    The article describes the latest mining equipment available to meet the global demand for coal from some major manufacture - Atlas Copco, Caterpillar Global Mining, Joy Mining Machinery, Liebherr Great Britain Ltd., Longwall Associates and Sandvik. 6 photos.

  13. The possibilites of coal seam underground excavation in Republic of Macedonia with high productive excavation methods


    Despodov, Zoran; Doneva, Nikolinka; Mijalkovski, Stojance


    The paper presents mining and geology properties of coal deposits in R.Macedonia predetermined for underground exploitation. Also it will be shown the way of coal seams preparation and development for underground excavation with longwall mining methods. Based on mining and geology properties of coal and it’s caloric value it will be observed the possibilities for application on the longwall mining which is among excavation methods with highest production and capacity applied in the contemp...

  14. Schemes for development and mining of level coal seams without leaving support coal pillars

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, A.F.; Batmanov, Yu.K.; Taratuta, N.K.


    Methods are illustrated for longwall mining without leaving support pillars for strata control. Comparative evaluations in Soviet coal mines show that with increasing mining depth coal losses associated with support pillars increase. Use of support pillars also increases rock burst hazard and increases cost of support repairs in mine roadways. Proportion of coal from longwall mining without leaving coal support pillars increased from 36 % in 1976 to 52% in 1980. Two variants of longwall mining without support pillars are analyzed: with repeated use of longwall gate roads and without their repeated use. Comparative investigations show that longwall mining with the repeated use of the gates (one of the gate roads) is used in coal seams with the most convenient mining and geological conditions, whereas the second system is used under more difficult conditions. Schemes with repeated use are designed for thin coal seams, at a depth not exceeding 600 m, under conditions of stable roof and floor (when the floor consists of less stable rocks absence of water influx is the condition). Repeated use of gate roads is economical when, in spite of repeated gate road use, cost of support repair and maintenance is low. Fifteen schemes for longwall mining with and without repeated use of gateroads are compared. The results of evaluations are shown in a table. Recommendations on the most economical mining schemes are made.

  15. Neandertal humeri may reflect adaptation to scraping tasks, but not spear thrusting.

    Directory of Open Access Journals (Sweden)

    Colin N Shaw

    Full Text Available Unique compared with recent and prehistoric Homo sapiens, Neandertal humeri are characterised by a pronounced right-dominant bilateral strength asymmetry and an anteroposteriorly strengthened diaphyseal shape. Remodeling in response to asymmetric forces imposed during regular underhanded spear thrusting is the most influential explanatory hypothesis. The core tenet of the "Spear Thrusting Hypothesis", that underhand thrusting requires greater muscle activity on the right side of the body compared to the left, remains untested. It is unclear whether alternative subsistence behaviours, such as hide processing, might better explain this morphology. To test this, electromyography was used to measure muscle activity at the primary movers of the humerus (pectoralis major (PM, anterior (AD and posterior deltoid (PD during three distinct spear-thrusting tasks and four separate scraping tasks. Contrary to predictions, maximum muscle activity (MAX and total muscle activity (TOT were significantly higher (all values, p<.05 at the left (non-dominant AD, PD and PM compared to the right side of the body during spear thrusting tasks. Thus, the muscle activity required during underhanded spearing tasks does not lend itself to explaining the pronounced right dominant strength asymmetry found in Neandertal humeri. In contrast, during the performance of all three unimanual scraping tasks, right side MAX and TOT were significantly greater at the AD (all values, p<.01 and PM (all values, p<.02 compared to the left. The consistency of the results provides evidence that scraping activities, such as hide preparation, may be a key behaviour in determining the unusual pattern of Neandertal arm morphology. Overall, these results yield important insight into the Neandertal behavioural repertoire that aided survival throughout Pleistocene Eurasia.

  16. The Coast Artillery Journal. Volume 91, Number 2, March-April 1948 (United States)


    the globe and, by devious under- gr ?und and ’underhand methods, to penetrate and under- nune the established social systems of manv lands " In a...Mexican Garrison at Juarez, Mexico, Gen- eral Enrique Diaz Gonzalez. The second was a review and presentation of colors and awards on 13 February. On this...34is one more fact of life, and a decisive one." It seems to him that "the \\;talitv of our Western culture will receive its gr ~t test in the use it

  17. Growth vs. decline

    Energy Technology Data Exchange (ETDEWEB)

    Morey, M.T.; Eyster, J.M. [PHB Hagler Bailly (USA)


    Production of high quality, low sulphur coal from mines in the western USA is in over supply. This situation is the result of increased production capacity from installing longwall technology, poor demand in international markets and growing competition from Powder River Basin coals at many domestic customer outlets. These factors have driven prices down by 10% since the beginning of 1999. With more longwall systems coming on line, low prices are set to continue. This should allow western US producers to compete in the international market for thermal coal, but only for as long as exporters are willing to accept the resulting low margins. 2 figs., 5 tabs., 2 photos.

  18. Third symposium on underground mining

    Energy Technology Data Exchange (ETDEWEB)



    The Third Symposium on Underground Mining was held at the Kentucky Fair and Exposition Center, Louisville, KY, October 18--20, 1977. Thirty-one papers have been entered individually into EDB and ERA. The topics covered include mining system (longwall, shortwall, room and pillar, etc.), mining equipment (continuous miners, longwall equipment, supports, roof bolters, shaft excavation equipment, monitoring and control systems. Maintenance and rebuilding facilities, lighting systems, etc.), ventilation, noise abatement, economics, accidents (cost), dust control and on-line computer systems. (LTN)

  19. 76 FR 9374 - Proposed Extension of Existing Information Collection; Examinations and Testing of Electrical... (United States)


    ... Testing of Electrical Equipment, Including High Voltage Longwalls AGENCY: Mine Safety and Health... on the right of the homepage. On the next screen, select ``Paperwork Reduction Act Supporting...: Extension. Agency: Mine Safety and Health Administration. OMB Number: 1219-0116. Frequency: Daily, weekly...

  20. Personal gravimetric dust sampling and risk assessment.

    CSIR Research Space (South Africa)

    Unsted, AD


    Full Text Available installation. The first underground site was a highly mechanized, shallow mine, the second site was a shallow mine with conventional mini-longwalls and the third site was a deep mechanized mine. The fourth site was an assay and sample preparation laboratory...

  1. 78 FR 78390 - Petitions for Modification of Application of Existing Mandatory Safety Standards (United States)


    ... breaker as being suitable for protecting the cables. (4) Replacement circuit breakers and/or instantaneous... methane monitor(s) on the continuous mining machine or the longwall shear and face on the shift prior to... detector at least every 10 minutes from the time that mining with the continuous mining machine is within...

  2. Remote mining for in-situ waste containment. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Martinelli, D.; Banta, L.; Peng, S. [and others


    This document presents the findings of a study conducted at West Virginia University to determine the feasibility of using a combination of longwall mining and standard landfill lining technologies to mitigate contamination of groundwater supplies by leachates from hazardous waste sites.

  3. 30 CFR 75.823 - Scope. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Scope. 75.823 Section 75.823 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.823 Scope...

  4. 78 FR 66911 - Texas Eastern Transmission, LP; Notice of Intent To Prepare an Environmental Assessment for the... (United States)


    ... discuss the environmental impacts of the Emerald Longwall Mine Panel D1 Project in Docket No. CP14-4-000...) requires the Commission to take into account the environmental impacts that could result from an action... effects, reasonable alternatives, and measures to avoid or lessen environmental impacts. The more specific...

  5. Browse Title Index

    African Journals Online (AJOL)

    Items 1 - 50 of 132 ... N Uddin. Vol 39, No 2 (2003), Actual phenomenon of surface subsidence and bulking factor of caved rockmass in longwall panels of some coal mines in India, Details. SK Das. Vol 42, No 2 (2006), Aeromagnetic imaging of the basement morphology in part of the middle Benue trough, Nigeria, Abstract.

  6. Long-hole destress blasting for rockburst control during deep underground coal mining

    Czech Academy of Sciences Publication Activity Database

    Koníček, Petr; Souček, Kamil; Staš, Lubomír; Singh, R.

    -, č. 61 (2013), s. 141-153 ISSN 1365-1609 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : Ostrava - Karvina Coal basin * longwall mining * rockbursts * destress blasting Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 1.424, year: 2013

  7. 30 CFR 75.819 - Motor-starter enclosures; barriers and interlocks. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Motor-starter enclosures; barriers and...-Voltage Distribution High-Voltage Longwalls § 75.819 Motor-starter enclosures; barriers and interlocks. Compartment separation and cover interlock switches for motor-starter enclosures must be maintained in...

  8. System principles and evaluation criteria of reliability for optimization of technological parameters of coal deposits

    Directory of Open Access Journals (Sweden)

    A.О. Khorolskiy


    Full Text Available The article deals with solving the scientific problem of select mining equipment for selection longwall faces of mining venture. The main goal of the paper is to study technology of coal extraction of mining venture. The paper proposes a new approach to solve a problem of mining equipment selection for longwall faces of mining venture. The article describes new method for selection of mining equipment based on theory graph. Special attention is given to technological aspects; they are lenght of longwall faces, depth of coal stratum. Predictions obtained for daily production of mining equipment are compared with design outputs. Conclusions regarding the main reason of instability of longwall faces workings are made. It is found that to be able to use standard algorithms find the shortest path between vertices, you must perform matrix description of the constructed graphs that illustrate the structure of the interaction of different types of control equipment. Using classical optimization of method of discrete mathematics and algorithms for finding the shortest path between two vertices of network models obtained from the formalization of graphs with maximum results of specific types of equipment production chains, solved the problem of rational choice cleaning equipment for the new site with the cost parameters of the mining equipment and cost of mining coal. The authors developed effective and appropriate variants for the mine development for different coal deposits of mining venture.

  9. 30 CFR 75.342 - Methane monitors. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Methane monitors. 75.342 Section 75.342 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.342 Methane monitors. (a)(1) MSHA approved methane monitors shall be installed on all face cutting machines, continuous miners, longwall face...

  10. 30 CFR 75.325 - Air quantity. (United States)


    ... coal by simply energizing the equipment on the section. (c) In longwall and shortwall mining systems... utilizing diesel-powered equipment in underground coal mines shall submit to the appropriate MSHA district... SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.325 Air quantity. (a)(1) In bituminous and...

  11. 30 CFR 70.1900 - Exhaust Gas Monitoring. (United States)


    ... Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY HEALTH STANDARDS-UNDERGROUND COAL MINES DIESEL EXHAUST GAS MONITORING § 70.1900 Exhaust Gas... equipment on the longwall or shortwall face when mining equipment is being installed or removed; and (4) In...

  12. Remote mining for in-situ waste containment. Final report

    International Nuclear Information System (INIS)

    Martinelli, D.; Banta, L.; Peng, S.


    This document presents the findings of a study conducted at West Virginia University to determine the feasibility of using a combination of longwall mining and standard landfill lining technologies to mitigate contamination of groundwater supplies by leachates from hazardous waste sites

  13. Causes of falls of hangingwall over gullies adjacent to stabilizing strike pillars

    CSIR Research Space (South Africa)

    Turner, PA


    Full Text Available This report discusses the occurrence of falls of ground in strike gullies. Falls of hangingwall over strike gullies on the up-dip side of strike stabilizing pillars in longwall mining systems were investigated. Gullies were examined in both...

  14. Older people's reasoning about age-related prioritization in health care. (United States)

    Werntoft, Elisabet; Hallberg, Ingalill R; Edberg, Anna-Karin


    The aim of this study was to describe the reasoning of people aged 60 years and over about prioritization in health care with regard to age and willingness to pay. Healthy people (n = 300) and people receiving continuous care and services (n = 146) who were between 60 and 101 years old were interviewed about their views on prioritization in health care. The transcribed interviews were analysed using manifest and latent qualitative content analysis. The participants' reasoning on prioritization embraced eight categories: feeling secure and confident in the health care system; being old means low priority; prioritization causes worries; using underhand means in order to be prioritized; prioritization as a necessity; being averse to anyone having precedence over others; having doubts about the distribution of resources; and buying treatment requires wealth.

  15. Privacy with Public Access: Digital Memorials on QR Codes

    DEFF Research Database (Denmark)

    Gotved, Stine


    takes the departure in gravestones with QR-codes; objects at once physical and digital, underhandedly putting presumably private content within public reach. A plethora of issues of privacy and publicness are at play within the study's two connected but rather different empirical spaces: the physical......Digital memorials are part of a bigger picture of changing rituals for mourning, remembrance, and legacy. However, the focus of this presentation is how digital memorials perforate the (already uneasy) distinction between private and public, both in physical and emotional space. The ongoing study...... in the borderland between private and public is exemplified, and with the presentation, we are ensuring a continued discussion on privacy as well as legacy in our digital society....

  16. Method of gas emission control for safe working of flat gassy coal seams (United States)

    Vinogradov, E. A.; Yaroshenko, V. V.; Kislicyn, M. S.


    The main problems at intensive flat gassy coal seam longwall mining are considered. For example, mine Kotinskaja JSC “SUEK-Kuzbass” shows that when conducting the work on the gassy coal seams, methane emission control by means of ventilation, degassing and insulated drain of methane-air mixture is not effective and stable enough. It is not always possible to remove the coal production restrictions by the gas factor, which leads to financial losses because of incomplete using of longwall equipment and the reduction of the technical and economic indicators of mining. To solve the problems, the authors used a complex method that includes the compilation and analysis of the theory and practice of intensive flat gassy coal seam longwall mining. Based on the results of field and numerical researches, the effect of parameters of technological schemes on efficiency of methane emission control on longwall panels, the non-linear dependence of the permissible according to gas factor longwall productivity on parameters of technological schemes, ventilation and degassing during intensive mining flat gassy coal seams was established. The number of recommendations on the choice of the location and the size of the intermediate section of coal heading to control gassing in the mining extracted area, and guidelines for choosing the parameters of ventilation of extracted area with the help of two air supply entries and removal of isolated methane-air mixture are presented in the paper. The technological scheme, using intermediate entry for fresh air intake, ensuring effective management gassing and allowing one to refuse from drilling wells from the surface to the mined-out space for mining gas-bearing coal seams, was developed.

  17. Stability Control of Underground Roadways Subjected to Stresses Caused by Extraction of a 10-m-Thick Coal Seam: A Case Study (United States)

    Chen, Yong; Ma, Shuqi; Yu, Yang


    Extraction of a 10-m-thick coal seam in one single lift using the longwall top coal caving method caused severe deformations in underground roadways in Majialiang coal mine in Shanxi Province, China. Field monitoring of stress changes in the roof and in the coal pillar, and deformation of the 14202 tailgate, were carried out. The deformation monitoring found that the maximum floor heave of the 14202 tailgate was 1.85 m when the monitoring point was 250 m behind the longwall working face, while the maximum roof subsidence and the maximum rib-rib convergence was 0.93 and 1.14 m, respectively. The deformation rate of the 14202 tailgate increased dramatically when the monitoring point was at distances of 100-150 m behind the longwall working face, which reflected the fact that the tailgate underwent sharply increased loads within this range. Field monitoring of stress changes and the displacement of the 14202 tailgate revealed that the impact range of the mining-induced stresses in longitudinal direction (the same as the mining direction) was from 60 m ahead of the longwall face to 250 m behind the longwall face. Additionally, the mining impact range in transverse direction was more than 45 m, indicating that the coal pillar width should be larger than 45 m to avoid significant influences of mining-induced stresses. This finding was applied to the 14103 tailgate, which was subjected to similar mining and geological conditions as the 14202 tailgate. A coal pillar with width of 56 m was adopted in the 14103 tailgate, and displacement monitoring showed that large deformation was successfully controlled. The field investigations in this study provide a basis for design of a proper coal pillar width of underground roadways when subjected to large stresses induced by mining of thick coal seams in a single lift.


    Directory of Open Access Journals (Sweden)

    Bahri Gjinovci


    Full Text Available The aim of this study was to verify the current status of accuracy in volleyball for the students of the faculty of physical education and sports of the University of Prishtina, all the students have successfully passed the exam in volleyball. Also, another aim was to observe whether there are significant statistical differences between both generations of students. In the study were included 70 students (35 from the second academic year and 35 from the fourth academic year. To achieve the aim, were applied standard tests of accuracy in volleyball, such as the following: overhand pass, underhand pass, as well as underhand serve on the six positions and float (tactic serve on three positions. From the basic statistical parameters, it has been noticed that grouping of results from the students of forth academic year are more homogenous, and for this group showed that results are better than at students of first year of studying. While, in the variables is noticed that there are changes into the favour of students of fourth academic year, it has also been noticed that standard deviation is smaller with this group, which shows even more homogenous groups, for example, SFIP group 1 mean 21.65 ±6.48 SD, gr.2 mean 23.68 ±5.76 SD. The obtained results from T-test shows significant statistical changes in both applied tests. The best obtained results are a derivate of continuous professional work, as well as result of “selection”, due to continuous testing and completion of both exams of hand sports and volleyball as an elective subject.


    Directory of Open Access Journals (Sweden)



    Full Text Available The article discusses a concept of forecasting accident risk during longwall extraction in crump-risk conditions. In Polish mines rock burst hazard can be described as high compared to other mines around the world. It's related to increase of depth of longwall field operation, preparation works, including drilling of mine face pavements which leads to systematic deterioration of geological and mining conditions. Depletion of coal is also the reason why mines operate in high mining tremor risk conditions. Mines more and more often operate in decks, where there is large number of edges and remains of older decks. Rocks bursts still remain one of the most dangerous natural hazards and therefore are fundamental prob-lem and have the greatest impact on safety in mining industry. The proposed method for forecasting accidents and loss-es in people and goods can contribute to improvement of work organization methods and mine safety management system.

  20. Continuous lift piers: Damage repair and response during subsidence

    International Nuclear Information System (INIS)

    Drumm, E.C.; Bennett, R.M.; Raaf, D.B.; Daugherty, D.


    A series of test foundations damaged during a longwall mining operation were left with permanent tilt, curvature, and substantial cracking. Two of the foundations were releveled using continuous lift piers. The continuous lift piers removed the tilt and curvature and significantly reduced the width of the foundation cracks. Following the releveling of the foundations, an adjacent longwall panel was mined, resulting in additional subsidence, although of smaller magnitude. The response of the releveled foundations was monitored and compared with the response of a footing that was not releveled. Although the continuous pier system does not strengthen the structure and distortion was observed during the second event, the system permitted the deformations to be removed in a few hours

  1. Assessment of surface and subsurface ground disturbance due to underground mining

    International Nuclear Information System (INIS)

    Khair, A.W.


    This paper presents highlights of the research carried out at West Virginia University in order to assess surface and subsurface ground disturbance due to longwall mining. Extensive instrumentation and measurements have been made over three longwall mines in northern West Virginia during a three-year period. Various monitoring techniques including full profile borehole extensometer, full profile borehole inclinometers, time domain reflectometry, sonic reflection technique, a unique mechanical grouting method, photographic and visual observations, standard surveying, and water-level measurements were utilized. The paper's emphasis is first on surface ground movement and its impact on integrity of surface ground and structures and second on type and magnitude of subsurface ground movements associated with mine geometry and geology. A subsidence prediction model based on implementation of both mechanisms of ground movement around the excavation and the geologic and geotechnical properties of the rock/coal surrounding the excavation has been developed. 8 refs., 14 figs., 1 tab

  2. Preliminary report on LLNL mine seismicity deployment at the Twentymile Coal Mine

    International Nuclear Information System (INIS)

    Walter, W.R.; Hunter, S.L.; Glenn, L.A.


    This report summarizes the preliminary results of a just completed experiment at the Twentymile Coal Mine, operated by the Cyprus Amax Coal Company near Oak Creek, CO. The purpose of the experiment was to obtain local and regional seismic data from roof caves associated with long-wall mining activities and to use this data to help determine the effectiveness with which these events can be discriminated from underground nuclear explosions under a future Comprehensive Test Ban Treaty

  3. The largest US coal acquisition takes shape

    International Nuclear Information System (INIS)

    Carter, R.A.


    The midyear purchase of Arco's US coal properties for 1.14 billion dollars gave Arch coal, Inc. (ACI) a string of surface and underground mines stretching from Wyoming's Powder River Basin to the coalfields of central Utah. The transaction created a new entity, Arch Western Resources LLC. The article describes operations at Black Thunder and Coal Creek surface mines and SUFCO, Skyline, Dugout Canyon and West Elk longwall mines. 4 photos


    Energy Technology Data Exchange (ETDEWEB)

    Zvi H. Meiksin


    A temporary installation of Transtek's in-mine communications system in the Lake Lynn mine was used in the mine rescue training programs offered by NIOSH in April and May 2002. We developed and implemented a software program that permits point-to-point data transmission through our in-mine system. We also developed a wireless data transceiver for use in a PLC (programmed logic controller) to remotely control long-wall mining equipment.

  5. Dust-control for thick-seam wall mines.

    CSIR Research Space (South Africa)

    Belle, BK


    Full Text Available handler (Source: Long Airdox Australia) Longwall mining represents the most cost-effective way to mine the coal from both the manpower and extractive ratio standpoint. Like any other mining methods, the extraction of coal generates large quantities... pneumoconiosis is being eliminated. However, it is still uncertain whether other health effects, such as chronic bronchitis and obstructive lung disease, will also be well controlled. From the pneumoconiosis point of view, the NSW coal mining industry now...

  6. Cayirhan challenge

    Energy Technology Data Exchange (ETDEWEB)

    Walker, S. [Independent Editorial and Technical Services, Oxford (United Kingdom)


    Lignite accounts for around 30% of Turkey's electricity generating capacity, mostly from mines owned by Turkiye Komur Isletmeleri Kurumu (TKI), Alfin-Elbistan Enterprises and Park Holding. Park Teknik, owned by Park Holding and SaarTech, has successfully bid to develop the B and C fields of the Cayirhan deposit in the Beypazari lignite basin. The article describes the development plan and longwall equipment chosen for those seams. 2 photos.

  7. Evaluation of rock burst in deep coal mining by using forensic engineering


    Oraee-Mirzamani, B; Zandi, S


    Rock bursts remain an important problem in longwall coal mining. These bursts are due to a sudden and severe failure of rocks from a high stress concentration in deep underground excavations that occur with the instantaneous release of strain energy stored in the rocks. They can potentially cause irrecoverable damage to equipment and personnel, thus accurate rock burst prediction and control is expected to be carried out by the mine design engineer. As a result, this can constitute major chal...

  8. Comparison of Methane Control Methods in Polish and Vietnamese Coal Mines


    Borowski Marek; Kuczera Zbigniew


    Methane hazard often occurs in hard coal mines and causes very serious accidents and can be the reason of methane or methane and coal dust explosions. History of coal mining shows that methane released from the rock mass to the longwall area was responsible for numerous mining disasters. The main source of methane are coal deposits because it is autochthonous gas and is closely related with carbonification and forming of coal deposits. Degree of methane saturation in coal deposits depends on ...

  9. Study on the Overlying Strata Movements and Stability Control of the Retained Goaf-side Gateroad


    Zhang, Zhiyi; Shimada, Hideki; Sasaoka, Takashi; Kai, Wen


    Recently, Y type gateroad layout, which is based on a retained gob-side gateroad (RGG), is being widely used for the purposes of optimizing ventilation system, increasing coal recovery rate, etc. The RGG, however, suffers several engineering disturbances including roadway excavation and two adjacent longwall panels mining during its whole serving life, which makes the stability control of this kind of roadway is difficult. In order to have a deep insight of this issue, a novel simulation soft...

  10. Releveling and behavior of strap-retrofitted damaged test foundations exposed to mine subsidence

    International Nuclear Information System (INIS)

    Marino, G.G.


    Test foundation walls were constructed in an area of planned subsidence. These crawl space-sized block bearing walls were located in the tension zone of a longwall panel. The test walls were 1.2 m (40 ft) long and were vertically loaded on top with soil binds to simulate the weight of a house. As the longwall proceeded past these test foundations, subsidence movements damaged the test structures. These damaged foundations were then structurally and aesthetically repaired by using a steel strap retrofit and applying a cementitious surface coating. The repaired test foundations underwent significant subsequent subsidence as an adjacent longwall was mined beneath. The response of the repaired foundation is summarized in this paper. The steel straps were also used to relevel another set of the test foundations after they were tilted and damaged by subsidence. First, the straps were applied to the block bearing walls, and then wall jacks were used to lift the upper portion of the walls to a level position. This releveling procedure is outlined with the results

  11. Determination of Destress Blasting Effectiveness Using Seismic Source Parameters (United States)

    Wojtecki, Łukasz; Mendecki, Maciej J.; Zuberek, Wacaław M.


    Underground mining of coal seams in the Upper Silesian Coal Basin is currently performed under difficult geological and mining conditions. The mining depth, dislocations (faults and folds) and mining remnants are responsible for rockburst hazard in the highest degree. This hazard can be minimized by using active rockburst prevention, where destress blastings play an important role. Destress blastings in coal seams aim to destress the local stress concentrations. These blastings are usually performed from the longwall face to decrease the stress level ahead of the longwall. An accurate estimation of active rockburst prevention effectiveness is important during mining under disadvantageous geological and mining conditions, which affect the risk of rockburst. Seismic source parameters characterize the focus of tremor, which may be useful in estimating the destress blasting effects. Investigated destress blastings were performed in coal seam no. 507 during its longwall mining in one of the coal mines in the Upper Silesian Coal Basin under difficult geological and mining conditions. The seismic source parameters of the provoked tremors were calculated. The presented preliminary investigations enable a rapid estimation of the destress blasting effectiveness using seismic source parameters, but further analysis in other geological and mining conditions with other blasting parameters is required.

  12. Technology and feasibility of potential underground thick seam mining methods

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Hebblewhite; Y. Cai; A. Simonis [University of New South Wales, NSW (Australia)


    The objectives of this current research project were to conduct a detailed investigation into the overall mining system and technology components of the systems listed above, with emphasis on three methods: single pass longwall (SPL); multi-pass longwall (MPL); and hydraulic mining (HM). The investigations were to include: ability to up-scale production levels, productivity and hence the economic viability above current best practice for each method; identification of the detailed equipment requirements necessary to achieve the above objective. Geotechnical design studies on critical issues identified from previous ACARP project; critical review, economic evaluation and risk assessment of methods under review. However, during this project, the project team became aware of the significant advances being made in China with a modified version of the soutirage method, known as Longwall Top Coal Caving (LTCC) which had been omitted from the project. This method was identified as having not only the potential to be an alternative to soutirage, but as a top priority thick seam method, in comparison with all other options. It has been concluded that if this method to be considered in this country, there are still a number of issues that must be resolved. The problem of coal/goaf interface detection is of particular importance, if levels of dilution are to be reduced. In addition, environmental issues such as dust suppression and spontaneous combustion still need to be further examined.

  13. Study of the ‘lifeline’ as the measure allowing for safe self-rescue of miners in conditions of lack of visibility caused by underground fire (United States)

    Badura, Henryk; Grodzicka, Aneta; Musioł, Dariusz


    The article presents statistical data regarding the evacuation of miners affected by underground fire hazards. The data indicates that the hazard remains considerable. Due to the increasing lengths of escape routes, measures should be introduced in the longwall regions, which shall improve the safe evacuation of miners, especially in conditions of highly limited visibility or the lack thereof. Within the research project No. 12, entitled: ‘The development of orientation systems and systems for signalling the direction of crew withdrawal for escape routes in longwall gates’, which is a part of the Strategic Research Project entitled ‘The improvement of work safety in mines’ financed by the National Centre for Research and Development, a ‘lifeline’ was designed - that is, a measure that is very effective in the evacuation of staff. Subsequently, tests of time of passage were conducted in the ‘Krupiński’ coal mine in conditions of lack of visibility. The tests have confirmed the suitability of the ‘lifeline’ as the measure used for orientation towards the correct direction of evacuation, which increases the pace and the confidence while travelling through the escape route. The mean speed of passage through the heading with an upwards inclination of 11° was 22 m/min, while in case of a nearly horizontal longwall gate, it was 39 m/min.

  14. Economic assessment of utilizing protective properties of level coal seams

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, A.F.; Batmanov, Yu.K.; Gainutdinov, I.A.


    Increasing mining depth negatively influences mining efficiency and safety. At depths to 600 m 10% of coal comes from seams prone to rock bursts. At depths exceeding 600 m proportion of coal from seams prone to rock bursts increases to 40%. Investigations carried out in Ukrainian coal mines show that coal losses (due to rock burst hazard) in level seams mined by a longwall system amount to 4.6 Mt per year. Cost of rock burst prevention and repairs after rock bursts amounts to 12 million rubles per year. About 68% of coal from level coal seams comes from long coal pillars mined by a longwall system. In level coal seams prone to rock bursts this proportion is 40% lower (proportion of longwall mining is reduced due to increased rock burst hazards). Only 10% of coal seams prone to rock bursts are mined using a system of stress relaxation by cutting another overlying or underlying coal seam (utilizing protective properties of a coal seam). A method for economic analysis of protective properties of coal seams in seam groups is described. Using the method the optimum order of mining coal seams in a seam group is determined. Examples of the method's use are analyzed. (3 refs.) (In Russian)

  15. Assessment of mining horizontal seams at depth considering strata stress factor

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, A.F.


    This paper discusses systems of mining level coal seams at large depths in the light of increasing mining depth in the Donbass, where about 50% of mined coal comes from depths exceeding 600 m. Mining systems used in underground mining in the Donbass are evaluated: 77.4% of production is from long pillar mining, 8.6% from longwall mining and 14% from combined systems. Seventeen variants of long pillar mining and longwall mining schemes used in the Donbass are compared. Effects of strata movement and strata control in mine roadways on mining cost are analyzed. A mathematical model is used for comparative evaluations of mining cost at large depths. Analyses show that long pillar mining combined with repeated use of gate roads is associated with considerable cost of support repair and support replacement. Recommendations on support systems suitable for strata control in mine roadways influenced by longwall mining are made. When roof subsidence does not exceed 500 mm, use of three-element yielding arched supports is recommended. In mine roadways with strata subsidence from 500 to 1200 mm, yielding arched supports consisting of five elements should be used. When forecast roof subsidence exceeds 1200 mm, additional support systems (such as friction props or hydraulic props) should be used. (6 refs.) (In Russian)

  16. The influence of subsidence attributable to coal mining on the environment, development and restoration: some examples from western Europe and South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Bell, F.G.; Genske, D.D. [University of Natal, Durban (South Africa). Dept. of Geology & Applied Geology


    One of the consequences of coal mining is subsidence, and it is associated with past and present mine workings. Indeed, old abandoned coal mines worked by the room-and-pillar method, which occur at shallow depth, often present a potential hazard as pillars collapse or voids migrate to the surface. Frequently, the situation is compounded by the fact that such workings are unrecorded. Subsidence prediction in such cases is impossible. In longwall mining, the total extraction of panels takes place, the working face being supported, while support is removed from behind the working face allowing the roof to collapse. Subsidence consequent on longwall mining can be regarded as more or less contemporaneous with mining and is normally predictable. This means that it is possible to develop an area after subsidence due to longwall mining has occurred or to incorporate features into the design of buildings and structures that will accommodate ground movements generated by subsidence. The nature of subsidence can be affected by discontinuities in the surface strata or the presence of superficial deposits. Of course, subsidence can adversely affect existing buildings and structures which do not incorporate special design features. In severe cases of subsidence damage, buildings may have to be demolished. Important buildings may be restored. Another problem associated with subsidence is flooding due to notable lowering of the ground surface. Examples of such problems and solutions are highlighted by the examples given.


    Directory of Open Access Journals (Sweden)

    Saša Milenković


    Full Text Available The aim of this research is to define the scope of influences of program mes of volleyball and handball schooll on the ap pe a ran ce of sco li o tic bad po stu re in ac ti ve volleyball and hand ball fe ma le players. In or der to un der stand the pro blem in its unity we ha ve to po int out that in fl u en ce of sport and physi cal edu ca tion on su bjects ta king pla ce in it is not al ways by ru le po si ti ve one. In ca ses of un skil lful and un ca re full tra i ning process such physi cal aci ti vi ti es can harm physi o lo gi cal fun cti ons, body com po si tion and de ve lop ment of the who le ar ray of bi o mo to ric struc tu res. Al so it is ne ces sary to ma ke a dif fe ren ce bet we en bad po stu re and de for mi ti es of the spi ne. Bad po stu re is not a constant form of end gan ge red part of the body and it can be cor rec ted by ta king adap ted cor rec ted po stu re and sreng hte ning of the mu scles and de com pres sing of that part of the body. The se very sta tes pre sent a su bject of our re se arch and we call them po stu ral –fun cti o nal ones. Vol leyball and hand ball are sports which by the ir mo tor con tents act asi me tric on lo co mo tor ap pa ra tus of the at hle tes. Mo ve ments are con di ti o ned by tec hni cal, tac ti cal and physi cal abi li ti es of the op po nents. Ta king in to con si de ra tion asi me tric tre a ting of spe ci fi c mu scle re gi ons they can bring abo ut spe ci fi c body de for mi ti es known as po stu ral de for mi ti es.

  18. Cluster analysis and relative relocation of mining-induced seismicity using HAMNET data (United States)

    Wehling-Benatelli, S.; Becker, D.; Bischoff, M.; Friederich, W.; Meier, T.


    Longwall mining activity in the Ruhr-coal mining district leads to mining-induced seismicity. For detailed studies seismicity of the single longwall panel S 109 beneath Hamm-Herringen in the eastern Ruhr area was monitored between June 2006 and July 2007. More than 7000 seismic events with magnitudes -1.7 ≤ ML ≤ 2.0 are localized in this period. 70% of the events occur in the vicinity of the moving longwall face. Moreover, the seismicity pattern shows spatial clustering of events in distances up to 500 m from the panel which is related to remnant pillars of old workings and tectonic features. Two sources with common location and rock failure mechanism are expected to show identical waveforms. Hence, similar waveforms suggest similarity of source properties. Waveform similarity can be quantified by cross-correlation. Similarity matrices have been established and build the basis of a cluster analysis presented here. We compare two approaches for cluster definition: a single-linkage approach and excerpting clusters by visual inspection of the sorted similarity matrices. Clusters are found as areas of high inter-event similarity in the depicted matrix. In contrast, the single-linkage approach assigns an event to the cluster if the similarity threshold v sl = 0.9 is exceeded to at least one other member. This method is more restrictive and, in general, leads to clusters with less members than visual inspection. Both methods exhibit clusters which show the same properties. The largest clusters are built by low-magnitude events (around ML ≈-0.6) directly at the longwall face at the mining level. Other clusters include events with magnitudes as large as ML,max = 1.8. Their locations tend to lie above or below the mining level in load-bearing sandstone layers. Mining accompanying events show face-parallel near vertical fault planes whereas more distant clusters have typical solutions of remnant pillar failure with a medium dip angle. Relative relocation of the events

  19. Coal Mine Accidents in Bangladesh: Its Causes and Remedial Measures

    Directory of Open Access Journals (Sweden)



    Full Text Available Barapukuria coal mine (BCM is located at Dinajpur district, NW Bangladesh. Total area is about 6.68 km2 and coal was encountered at a depth ranging between 118 and 509 m. Six major coal seams (seam I to seam VI were identified at BCM, of which, thickest one is the seam-VI (~36 m. The estimated coal reserves is about 390 million tons and of this, nearly 64 million tons of coal is extractable. The annual production of coal is about 1 million ton. In this study several parameters were used to explore minimization of accidents and improvement of coal production in BCM. Considering the geological, hydrological and other technical parameters, longwall mining method is applied for extraction of coal. Longwall retreating mining method is also applied for extraction of coal from single face with the operational area protected by self-advancing hydraulic powered roof support (HPRS system. These supports are moved forward causing the roof behind them to form an extensive abandoned area named goaf, which may lead to collapse with air blast. Coal in BCM is extracted from seam VI, using a multislice Longwall top coal caving method. Average ventilated air composition is ~20.94% oxygen, ~79.00% nitrogen, ~0.04% carbon monoxide, and minor water steam with huge dust. Production of coal was completed from 12 Longwall faces of 1st slice from seam VI. During production period several accidents and troubles within BCM have occurred. Poisonous gases such as carbon monoxide were detected during/after development of 1110 Longwall face, which increases up to 6000 ppm, therefore, sealed-off the face with mining equipments. During the development of belt gate roadway of 1101 Longwall face, maximum temperature and humidity increases up to 37 oC and 100%, respectively. Miners of BCM experienced some difficulties to work in that adverse environment. Air return roadway temperature was always 40 to 41oC in 1101 Longwall face during production period, faces temperature 46o

  20. Hydrologic conditions and water-quality conditions following underground coal mining in the North Fork of the Right Fork of Miller Creek drainage basin, Carbon and Emery Counties, Utah, 2004-2005 (United States)

    Wilkowske, C.D.; Cillessen, J.L.; Brinton, P.N.


    In 2004 and 2005, the U.S. Geological Survey, in cooperation with the Bureau of Land Management, reassessed the hydrologic system in and around the drainage basin of the North Fork of the Right Fork (NFRF) of Miller Creek, in Carbon and Emery Counties, Utah. The reassessment occurred 13 years after cessation of underground coal mining that was performed beneath private land at shallow depths (30 to 880 feet) beneath the NFRF of Miller Creek. This study is a follow-up to a previous USGS study of the effects of underground coal mining on the hydrologic system in the area from 1988 to 1992. The previous study concluded that mining related subsidence had impacted the hydrologic system through the loss of streamflow over reaches of the perennial portion of the stream, and through a significant increase in dissolved solids in the stream. The previous study also reported that no substantial differences in spring-water quality resulted from longwall mining, and that no clear relationship between mining subsidence and spring discharge existed.During the summers of 2004 and 2005, the USGS measured discharge and collected water-quality samples from springs and surface water at various locations in the NFRF of Miller Creek drainage basin, and maintained a streamflow-gaging station in the NFRF of Miller Creek. This study also utilized data collected by Cyprus–Plateau Mining Corporation from 1992 through 2001.Of thirteen monitored springs, five have discharge levels that have not returned to those observed prior to August 1988, which is when longwall coal mining began beneath the NFRF of Miller Creek. Discharge at two of these five springs appears to fluctuate with wet and dry cycles and is currently low due to a drought that occurred from 1999–2004. Discharge at two other of the five springs did not increase with increased precipitation during the mid-1990s, as was observed at other monitored springs. This suggests that flowpaths to these springs may have been altered by

  1. Bribery and Its Ethical Implications for Aid Workers in the Developing World. (United States)

    Remer, J Scott


    Bribery is a complicated, multi-dimensional issue. Upon first glance, most westerners would immediately condemn it as an underhanded, unfair means of gaining an advantage in a competitive or legal situation, and so it is in virtually every case in the westernized world. However, the issue becomes much more complicated in the international context, particularly in developing nations, where giving and accepting bribes is often normal and expected. This paper serves to inform ethical decision-making in situations where the "right choice" is unclear with regards to bribery, primarily for individuals performing aid work in foreign countries with corrupt officials and police officers. In such contexts, a simple offering of food, money, or a small trinket may make the difference between a person being able to accomplish meaningful, life-changing work for the local populace or having that work significantly slowed at best and being thrown out of the country, robbed, or imprisoned in worse cases. The larger scale bribery issues in international business and the laws pertaining to them are also discussed.

  2. Proficiency deficiency: mastery of fundamental movement skills and skill components in overweight and obese children. (United States)

    Cliff, Dylan P; Okely, Anthony D; Morgan, Philip J; Jones, Rachel A; Steele, Julie R; Baur, Louise A


    The purpose of this observational study was to compare the mastery of 12 fundamental movement skills (FMS) and skill components between a treatment-seeking sample of overweight/obese children and a reference sample from the United States. Mastery of six locomotor and six object-control skills (24 components in each subdomain) were video-assessed by one assessor using the test of gross motor development-2 (TGMD-2). The 153 overweight/obese children (mean ± s.d. age = 8.3 ± 1.1 years, BMI z-score = 2.78 ± 0.69, 58% girls, 77% obese) were categorized into age groups (for the underhand roll and strike: 7-8 years and 9-10 years; all other FMS: 6-7 years and 8-10 years) and mastery prevalence rates were compared with representative US data (N = 876) using χ(2) analysis. For all 12 skills in all age groups, the prevalence of mastery was lower among overweight/obese children compared with the reference sample (all P movement patterns that could be targeted for improvement include positioning of the body and feet, the control or release of an object at an optimal position, and better use of the arms to maintain effective force production during the performance of FMS. Physical activity programs designed for overweight and obese children may need to address deficiencies in FMS proficiency to foster the movement capabilities required for participation in health-enhancing physical activity.

  3. Study of otoacoustic emissions in workers of various professional groups of the coal industry

    Directory of Open Access Journals (Sweden)

    Shydlovska T.A.


    Full Text Available Noise influence takes one of the leading roles in the development of sensorineural hearing loss (SHL. At the same time professional deafness steadily occupies the 5th place in the structure of occupational diseases in Ukraine over the past few years. Of special importance is the problem of pre-clinical and early diagnosis of occupational hearing deterioration, in sense of timely prophylactic and rehabilitation measures in “risk group” workers. The objective research methods play an important role in the diagnosis of auditory analyzer state. Many scientific studies have shown the diagnostic effectiveness of method of otoacoustic emissions recording in the early diagnosis of lesions of receptor part of auditory analyzer. It is known that SHL of noise genesis largely affects the receptor part of the auditory analyzer, for which the OAE method has great practical diagnostic significance. Objective: to study informativity indicators of otoacoustic emission for the diagnosis of sensorineural hearing loss in various occupational groups of coal workers in Ukrainian mines. Materials and Methods: Auditory function of 87 workers of the coal industry (drifters, miners and longwall miners with different levels of industrial noise and hygienic conditions in their workplaces was: 28 studied drifters (group 1, 25 miners (group 2 and 34 longwall miners (group 3. Work experience in noise in these groups was 17,9±1,0; 23,1±1,0 and 22,2±2,0 accordingly. Noise ratio in drifters was 93,6±4,9 dBA, in miners – 92,9±5,5 dBA and in longwall miners – 86,5±6,04 dBA accordingly, while the maximum permitted level is 80 dBA. The research was conducted on the analyzing system "Eclipse" "Interacoustics" (Denmark. All patients underwent registratiov of the caused OAE at frequency distortion product (DPOAE at frequencies 1-6 kHz. The results were rated using variation statistics Student's test. Results: The most prominent violation of the receptor part of the

  4. Grade Distribution Modeling within the Bauxite Seams of the Wachangping Mine, China, Using a Multi-Step Interpolation Algorithm

    Directory of Open Access Journals (Sweden)

    Shaofeng Wang


    Full Text Available Mineral reserve estimation and mining design depend on a precise modeling of the mineralized deposit. A multi-step interpolation algorithm, including 1D biharmonic spline estimator for interpolating floor altitudes, 2D nearest neighbor, linear, natural neighbor, cubic, biharmonic spline, inverse distance weighted, simple kriging, and ordinary kriging interpolations for grade distribution on the two vertical sections at roadways, and 3D linear interpolation for grade distribution between sections, was proposed to build a 3D grade distribution model of the mineralized seam in a longwall mining panel with a U-shaped layout having two roadways at both sides. Compared to field data from exploratory boreholes, this multi-step interpolation using a natural neighbor method shows an optimal stability and a minimal difference between interpolation and field data. Using this method, the 97,576 m3 of bauxite, in which the mass fraction of Al2O3 (Wa and the mass ratio of Al2O3 to SiO2 (Wa/s are 61.68% and 27.72, respectively, was delimited from the 189,260 m3 mineralized deposit in the 1102 longwall mining panel in the Wachangping mine, Southwest China. The mean absolute errors, the root mean squared errors and the relative standard deviations of errors between interpolated data and exploratory grade data at six boreholes are 2.544, 2.674, and 32.37% of Wa; and 1.761, 1.974, and 67.37% of Wa/s, respectively. The proposed method can be used for characterizing the grade distribution in a mineralized seam between two roadways at both sides of a longwall mining panel.

  5. Effects of torpedo blasting on rockburst prevention during deep coal seam mining in the Upper Silesian Coal Basin

    Directory of Open Access Journals (Sweden)

    Ł. Wojtecki


    Full Text Available In the Upper Silesian Coal Basin (USCB, coal seams are exploited under progressively more difficult geological and mining conditions (greater depth, higher horizontal stress, more frequent occurrence of competent rock layers, etc.. Mining depth, dislocations and mining remnants in coal seams are the most important factors responsible for the occurrence of rockburst hazards. Longwall mining next to the mining edges of neighbouring coal seams is particularly disadvantageous. The levels of rockburst hazards are minimised via the use of rockburst prevention methods. One active prevention method is torpedo blasting in roof rocks. Torpedo blastings are performed in order to decrease local stress concentrations in rock masses and to fracture the roof rocks to prevent or minimise the impact of high-energy tremors on excavations. The estimation of the effectiveness of torpedo blasting is particularly important when mining is under difficult geological and mining conditions. Torpedo blasting is the main form of active rockburst prevention in the assigned colliery in the Polish part of the USCB. The effectiveness of blasting can be estimated using the seismic effect method, in which the seismic monitoring data and the mass of explosives are taken into consideration. The seismic effect method was developed in the Czech Republic and is always being used in collieries in the Czech part of the coal basin. Now, this method has been widely adopted for our selected colliery in the Polish part of the coal basin. The effectiveness of torpedo blastings in the faces and galleries of the assigned longwall in coal seam 506 has been estimated. The results show that the effectiveness of torpedo blastings for this longwall was significant in light of the seismic effect method, which corresponds to the in situ observations. The seismic effect method is regularly applied to estimating the blasting effectiveness in the selected colliery.

  6. Analysis of Overlying Strata Movement and Behaviors in Caving and Solid Backfilling Mixed Coal Mining

    Directory of Open Access Journals (Sweden)

    Yanli Huang


    Full Text Available Based on techniques of close upper protective coal-rock layer mining, relieved gas extraction, and underground gangue washing-discharging-backfilling, this paper initiates the concept of mixed fully-mechanized coal mining, which combines a solid backfilling method and a caving method (hereinafter referred to as “backfill and caving mixed mining”. After the principle and key techniques are introduced, a physical simulation experiment and a numerical simulation are used to study the characteristics of the overlying strata’s fracture development, the main roof subsidence, the stress field and its influence area in the transition area with the length ratios of the backfilling section and the caving section, and the advancing distance of the mixed longwall face. Thus, the lengths of the caving section and the backfilling section, the parameters of the support system in the transition section, and the design process of the mixed longwall face are presented. In practice, the mixed longwall face Ji15-31010 in Ping-dingshan No. 12 Colliery proves that the designed lengths of 120 m and 100 m for the backfilling section and the caving section, respectively, are appropriate. The monitoring results of the hydraulic support working resistance show that the supports were working well in general; the maximum growth height of the overlying strata fracture is 18 m; the gas drainage efficiency is up to 80% and the average gas concentration is 0.1 g/m3; a large quantity of gangue generated in the Ji14 seam is disposed underground; coal and gas are extracted simultaneously; and significant environmental and economic benefits are realized.

  7. Application of multimedia in strategic management in engineering design associated with occupational hazards of dust

    Energy Technology Data Exchange (ETDEWEB)

    Atkins, A.S.; Aziz, N.I.; Rao, B.S. [Staffordshire University, Stafford (United Kingdom). School of Computing


    The paper deals with the application of Multimedia to synthesis the aerodynamic patterns of airborne dust flow along the longwall face in a coal mine. The use of multimedia enables modelling techniques to be illustrated using graphical and photographic information. The multimedia techniques permit design systems, linked to CAD/CAM, to be used to design control techniques and air velocity on respirable dust flow behaviour. Results from several field sites are used to demonstrate the effectiveness of multimedia linked to Executive Information System (EIS) to provide strategic system decision support. 9 refs., 4 figs.

  8. Subsidence monitoring program at Cyprus Coal's Colorado operations

    International Nuclear Information System (INIS)

    Stewart, C.L.; Shoemaker, J.E.


    Published subsidence data for the western United States is limited in comparison with data for the east. This paper summarizes the results of a subsidence monitoring program above two longwall panels at the Foidel Creek Mine located in northwest Colorado. The monitoring area is characterized by overburden ranging from 1000 ft to 1100 ft in thickness. the surface slope parallels the dip of the bedding at approximately 5 deg. Average mining height is 9 ft. Smax averaged 3.4 ft. Draw angles averaged 15 deg for up-dip ribsides and 19 deg for down-dip ribsides. A site-specific profile function is developed from the data

  9. No impediments to introducing LTCC to Australia: researchers

    Energy Technology Data Exchange (ETDEWEB)



    China has achieved significant production improvements in coal mining as a result of development and application of the Longwall Top Coal Caving (LTCC) method. The University of New South Wales has reviewed potential sites in Australia where LTCC could find application and is currently conducting research aimed at better geotechnical site characterization. Major benefits of the method include: operating cost reductions; resource recovery, mine financial performance and mine safety. The geological factors considered to be most important for implementation of LTCC in Australia are: coal seam capability/fragmentation; the effect of massive strata units in immediate/near seam roof; and the effect of high horizontal stress ratios. 1 ref., 1 fig.

  10. Mechanism of rigid overlaying of carboniferous strata failure in face mining in the case of multiseams deposit

    Czech Academy of Sciences Publication Activity Database

    Jiránková, E.; Staš, Lubomír; Kajzar, Vlastimil; Doležalová, Hana


    Roč. 10, č. 2 (2013), s. 189-195 ISSN 1214-9705 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MV VG20102014034 Institutional support: RVO:68145535 Keywords : subsidence trough * rock mass * overlaying strata * longwall mining * tensor stress measurement Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.667, year: 2013

  11. Shortwall mining with powered supports at Venkatesh Khani No. 7 incline - collating the experiences

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M.S.; Sastry, B.D. [Singareni Collieries Co. Ltd. (India)


    The Venkatesh Khani No. 7 mine has been worked by longwall techniques. An experiment was made with using shortwall mining to evaluate the feasibility of partial extraction with mechanisation by reducing the width of the face. Several blocks were selected and attention was paid to subsidence during shortwall working. Details are given of strata control, scientific investigations, instrumentation, measurement cycles, roof to floor convergence at the face, gateroad convergence, extensometry, experience with falls, and subsidence during this project. It is concluded that shortwall mining can be safely used below surface structures and for pillar extraction with zero ground movement. 2 refs., 10 figs., 4 tabs.

  12. High pressure water jet mining machine (United States)

    Barker, Clark R.


    A high pressure water jet mining machine for the longwall mining of coal is described. The machine is generally in the shape of a plowshare and is advanced in the direction in which the coal is cut. The machine has mounted thereon a plurality of nozzle modules each containing a high pressure water jet nozzle disposed to oscillate in a particular plane. The nozzle modules are oriented to cut in vertical and horizontal planes on the leading edge of the machine and the coal so cut is cleaved off by the wedge-shaped body.

  13. Use of ground penetrating radar in underground coal mining (United States)

    Ralston, Johnathon C.; Hainsworth, David W.


    This paper reports on a novel application of ground penetrating radar to a longwall steering problem in the coal mining industry. The main goal of the work was to determine whether a radar-based system could be used to detect coal-rock interfaces in order to establish a suitable mining horizon within the coal seam. We investigated the feasibility of the radar unit and determined that a positive correlation exists between the radar data and known coal-rock interface geology. We also highlight some of the unique challenges encountered when attempting to develop electrical equipment that is suitable for hazardous underground coal mining environments.

  14. Generalised empirical method for predicting surface subsidence

    International Nuclear Information System (INIS)

    Zhang, M.; Bhattacharyya, A.K.


    Based on a simplified strata parameter, i.e. the ratio of total thickness of the strong rock beds in an overburden to the overall thickness of the overburden, a Generalised Empirical Method (GEM) is described for predicting the maximum subsidence and the shape of a complete transverse subsidence profile due to a single completely extracted longwall panel. In the method, a nomogram for predicting the maximum surface subsidence is first developed from the data collected from subsidence measurements worldwide. Then, a method is developed for predicting the shapes of complete transfer subsidence profiles for a horizontal seam and ground surface and is verified by case studies. 13 refs., 9 figs., 2 tabs

  15. Coal output dependence on parameters of tectonic disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Kozel, K.K. (L' vovsko-Volynskaya GREh (USSR))


    Analyzes effects of tectonic dislocations of coal seams on output of longwall faces in 5 mines of the Chervonograd area with 4 coal seams. The seams are mined by KM97 face systems with the 1K101 shearer loader and the KM87 system with the GSh68 shearer loader. Fault length and throw in relation to coal panel dimensions and coal seam thickness are analyzed. Effects of tectonic dislocations on face advance rates and coal output per face are calculated. Correlations of tectonic dislocation parameters (fault throw and range) and coal output per face are determined. 4 refs.

  16. Finite element modeling of surface subsidence induced by underground coal mining

    International Nuclear Information System (INIS)

    Su, D.W.H.


    The ability to predict the effects of longwall mining on topography and surface structures is important for any coal company in making permit applications and anticipating potential mining problems. The sophisticated finite element model described and evaluated in this paper is based upon five years of underground and surface observations and evolutionary development of modeling techniques and attributes. The model provides a very powerful tool to address subsidence and other ground control questions. The model can be used to calculate postmining stress and strain conditions at any horizon between the mine and the ground surface. This holds the promise of assisting in the prediction of mining-related hydrological effects

  17. An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining


    Jianguo Ning; Jun Wang; Tengteng Bu; Shanchao Hu; Xuesheng Liu


    This study considered longwall working face No. 41101—located in a steeply inclined coal seam at the Awuzisu coal mine in Xinjiang, China—as an example in which macroscopic shear cracks had occurred in the cement-based filling body of the gob-side entry retention structure. A mechanical model of the support structure for the gob-side entry retention was first established. Then, field observations and laboratory tests were used to obtain the force exerted by the coal wall on the main roof, the...

  18. Profiles of noise exposure levels in South African mining

    CSIR Research Space (South Africa)

    Edwards, A


    Full Text Available in occupations in longwall sections of U.S.A. coal mines are exposed to levels in excess of exposure levels regarded as safe for the prevention of NIHL. Examples of the reported coal miners? exposure levels are that stageloaders are exposed to noise levels.... The results of other aspects of the study are reported elsewhere.15,16 METHODOLOGY The multi-task research design implemented by the Concawe Health Management Group (CHMG) that assessed gasoline vapour exposures of European petroleum industry employees...

  19. A new method to calculate permeability of gob for air leakage calculations and for improvements in methane control

    Energy Technology Data Exchange (ETDEWEB)

    Karacan, C.O. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States). Office of Mine Safety and Health Research


    Although longwall underground mining can maximize coal production, it causes large scale disturbances of the surrounding rock mass due to fracturing and caving of the mine roof as the mine face advances. The porosity and permeability of the longwall gob can affect the methane and air flow patterns considerably. Since methane is a major hazard in underground coal mining operations, extensive methane control techniques are used to supplement the existing mine ventilation system, such as gob gas ventholes (GGV). However, the gob is rarely accessible for performing direct measurements of porosity and permeability. Therefore, this study presented a fractal approach for calculating the porosity and permeability from the size distribution of broken rock material in the gob, which can be determined from image analyses. The fractal approach constructs flow equations and fractal crushing equations for granular materials to predict porosity for a completely fragmented porous medium. The virtual fragmented fractal porous medium is exposed to various uniaxial stresses to simulate gob compaction and porosity and permeability changes during this process. It was concluded that the use of this fractal approach will result in better predictions regarding the flow amount and flow patterns in the gob, and facilitate leakage calculations and methane control projections. 29 refs., 4 tabs., 5 figs.

  20. A section of a pacing mine timbering

    Energy Technology Data Exchange (ETDEWEB)

    Hodous, J.; Kubac, J.; Novak, Z.; Skrobalek, J.; Zajic, K.


    A section is proposed for a pacing mine support of the wall and supporting type, designed for reinforcing the operational space of a longwall. The support section differs from the known in that it has relatively large mobility with the use of single stage telescopic hydraulic uprights. The section has left and right skiis, to which the tunneling machine with an upper part is attached using a hinged link. One hydraulic upright is installed on each ski, while a device for advancing the support is installed between the skiis. It is linked using a trough with the longwall conveyor which is not shown in the figure. A complex shaped track is made on each ski with three support recesses located at a different height relative to the base of the ski. The hydraulic upright is linked by its fixed part with the upper part of with the heading machine. The support has controllable projections on two sides, each of which is inserted in a track. Moreover, the support is attached to a hydraulic power cylinder, which is hinged with one of the skiis.

  1. The peculiarities of structurizing enclosing rock massif while developing a coal seam (United States)

    Kozyreva, E. N.; Shinkevich, M. V.


    Different concepts of the development of geo-mechanical processes during longwall mining of a seam which are fundamentally different from the conventional ones are introduced in the article. Fundamental principles of the model for structurizing enclosing rock mass while longwall mining along the strike are described. The model was developed on the bases of non-linear geomechanical laws. According to the model, rock mass in the area of mining operation is organized as rock geomechanical layers with shifting arches. And the formation period of shifting arches in disintegrated rock mass is divisible by the length of the stope. Undulate characteristic of a massif as a peculiarity of man-made structurization of a massif is defined. It is shown that structuring the broken massif causes the formation of block-structured system and it can be detected while monitoring the ground pressure in powered support props. The results of the research allow decreasing the negative influence of a ground pressure and can be applied to specify parameters for controlling the roof, defining geometrical dimensions of a mining section and positioning of holing chute (face entry).

  2. Pushing up smoking incidence: plans for a privatised tobacco industry in Moldova. (United States)

    Gilmore, Anna B; Radu-Loghin, Cornel; Zatushevski, Irina; McKee, Martin

    Moldova, one of the former Soviet republics and Europe's poorest country, has so far resisted pressure to privatise its tobacco industry. This paper examines the policies pursued by the transnational tobacco companies in Moldova in order to inform the ongoing debate about tobacco industry privatisation. We analysed relevant internal industry documents made public through litigation. The documents suggest that although a competitive tender for the state owned monopoly was later announced, British American Tobacco (BAT) and the German manufacturer Reemtsma each initially sought to secure a closed deal, with BAT accusing Reemtsma of underhand tactics. Imperial Tobacco, which now owns Reemstma, was unable to comment on these allegations as it only acquired Reemstma after the events in question. BAT sought to acquire a monopoly position, bolstered by excise rules developed by the company that would uniquely favour its products. Despite hoping to establish a monopoly, it planned intensive marketing, as if in a competitive market, aiming to target young urban dwellers, particularly opinion leaders. In so doing it predicted that smoking uptake would increase, especially among women. The documents also suggest that BAT was aware of the sensitive nature of its plans to cull the processing workforce and aimed to present "sanitised" information on future employment levels to the Moldovans. The potential for tobacco industry privatisation to undermine tobacco control and promote cigarette consumption is highlighted and is consistent with economic theory. Countries planning tobacco industry privatisation should ensure a transparent and competitive privatisation process, seek to prevent the predicted increase in consumption by implementing effective tobacco control policies and consider the impacts on employment. Multilateral financial organisations promoting tobacco industry privatisation could ensure their loan conditions protect public health by making the implementation of

  3. Three year follow-up of an early childhood intervention: is movement skill sustained?

    Directory of Open Access Journals (Sweden)

    Zask Avigdor


    Full Text Available Abstract Background Movement skill competence (e.g. the ability to throw, run and kick is a potentially important physical activity determinant. However, little is known about the long-term impact of interventions to improve movement skills in early childhood. This study aimed to determine whether intervention preschool children were still more skill proficient than controls three years after a 10 month movement skill focused intervention: ‘Tooty Fruity Vegie in Preschools’. Methods Children from 18 intervention and 13 control preschools in NSW, Australia were assessed at ages four (Time1, five (T2 and eight years (T3 for locomotor (run, gallop, hop, leap, horizontal jump, slide and object control proficiency (strike, bounce, catch, kick, overhand throw, underhand roll using the Test of Gross Motor Development-2. Multi-level object control and locomotor regression models were fitted with variables time, intervention (yes/no and a time*intervention interaction. Both models added sex of child and retained if significant, in which case interactions of sex of child with other variables were modelled and retained. SPSS (Version 17.0 was used. Results Overall follow-up rate was 29% (163/560. Of the 137 students used in the regression models, 53% were female (n = 73. Intervention girls maintained their object control skill advantage in comparison to controls at T3 (p = .002, but intervention boys did not (p = .591. At T3, there were no longer intervention/control differences in locomotor skill (p = .801. Conclusion Early childhood settings should implement movement skill interventions and more intensively target girls and object control skills.

  4. Examination of motor skill competency in students: evidence-based physical education curriculum

    Directory of Open Access Journals (Sweden)

    Weiyun Chen


    Full Text Available Abstract Background Researchers found that children with a competent level of motor skill performance are more likely to be physically active. This study examined how well K-1 students demonstrated motor skill competency in relation to Physical Education Content Standard 1. Methods Participants were K-1 grade students (N = 1,223-1,588; boys = 568–857; girls = 526–695; Mean age = 5.5 yrs old who were enrolled in nine elementary schools. The K-1 students’ motor skill competency in running, weight transferring, hand dribbling, and underhand catching skills was assessed using four PE Metrics skill assessment rubrics in the intervention year 1 and year 2, respectively. Data were analyzed by means of descriptive statistics and independent sample t-tests. Results The students in the intervention year 1 and year 2 cohorts performed at the Competent Level or higher in the four skill assessments. The prevalence of the students’ demonstration of skill competency across the four skills was high in the two intervention years. The intervention year 2 cohort scored significantly higher than the intervention year 1 cohort in the four skill assessments. The boys significantly outperformed than the girls in the two manipulative skills in the intervention year 1 and in the two manipulative skills and the weight transferring skill in the intervention year 2. No gender differences in the running skill in either year were found. Conclusions The evidence-based CATCH PE play a critical role in developing and building K-1 students’ ability to demonstrate motor skill competency in four fundamental skills. Trial registration ID: NCT03015337 , registered date: 1/09/2017, as "retrospectively registered".

  5. Cost comparison of selected US and Polish coal mines, August 1993

    International Nuclear Information System (INIS)


    This report on the Polish coal industry is the fifth in a series of studies on coal exporting countries requested by the House Appropriations Committee. The committee requested that the basic differences in mining costs for U.S. and foreign mines be identified, especially those costs incurred in complying with health, safety, and environmental regulations. Basic costs in extracting raw coal are analyzed in this report for underground longwall mining operations, the only mining method employed in Poland for hard coal. In this report there is also a limited analysis of the relative market competitiveness of selected Polish and U.S. steam and metallurgical coal mines in the European electric utility and metallurgical coal markets

  6. The stability of structure's foundation rockmass over shallow abandoned mine goafs and its treatment - a case study

    International Nuclear Information System (INIS)

    Guo, G.; He, G.; Qiao, Z.; Yang, S.; Deng, K.; Gao, J.


    A heavy coal dressing plant is constructed on an area seriously damaged by underground longwall mining in one of China's collieries. The Southwest of the main dressing plant stands on the ground over shallow abandoned mine goafs. Using the methods of boring and geophysical exploration and mining subsidence analysis, this paper studies the 3D distribution of fracture zones caused by mining's influence. Combined with the result of FEM, the paper analyses the stability of the main building's foundation rock mass, advances and adopts some safety measures, such as grouting the mining the fractured rockmass to consolidate it, appropriately designing the building to improve its anti-deformation ability, etc. The inspection results of geophysical prospecting show that consolidation grouting has attained the expected results. The settlement observation indicates that the settlement of the main building is smooth. 4 refs., 4 figs

  7. Analysis characteristics determination of electrohydraulic control system operation to reduce the operation time of a powered roof support (United States)

    Szurgacz, Dawid


    The article discusses basic functions of a powered roof support in a longwall unit. The support function is to provide safety by protecting mine workings against uncontrolled falling of rocks. The subject of the research includes the measures to shorten the time of roof support shifting. The roof support is adapted to transfer, in hazard conditions of rock mass tremors, dynamic loads caused by mining exploitation. The article presents preliminary research results on the time reduction of the unit advance to increase the extraction process and thus reduce operating costs. Conducted stand tests showed the ability to increase the flow for 3/2-way valve cartridges. The level of fluid flowing through the cartridges is adequate to control individual actuators.

  8. Determination of intensity functions for predicting subsidence from coal mining, potash mining, and groundwater withdrawal using the influence function technique

    Energy Technology Data Exchange (ETDEWEB)

    Triplett, T.; Yurchak, D. [Twin Cities Research Center, Bureau of Mines, US Dept. of the Interior, Minneapolis, MN (United States)


    This paper presents research, conducted by the Bureau of Mines, on modifying the influence function method to predict subsidence. According to theory, this technique must incorporate an intensity function to represent the relative significance of the causes of subsidence. This paper shows that the inclusion of a reasonable intensity function increases the accuracy of the technique, then presents the required functions for case studies of longwall coal mining subsidence in Illinois, USA, potash mining subsidence in new Mexico, USA, and subsidence produced by ground water withdrawal in California, USA. Finally, the paper discusses a method to predict the resultant strain from a simply measured site constant and ground curvatures calculated by the technique. (orig.)

  9. Stress distribution characteristics in the vicinity of coal seam floor (United States)

    Cui, Zimo; Chanda, Emmanuel; Zhao, Jingli; Wang, Zhihe


    Although longwall top-coal caving (LTCC) has been a popular, more productive and cost-effective method in recent years, roadway floor heave and rock bursts frequently appear when exploiting such coal seams with large dip angle. This paper proposes addressing this problem by adopting three-dimensional roadway layout of stagger arrangement (3-D RLSA). In this study, the first step was to analyse the stress distribution characteristics in the vicinity of coal seam floor based on the stress slip line field theory. In the second step, numerical calculation using FLAC3D was conducted. Finally, an evaluation of the 3-D RLSA for solving this particular issue was given. Results indicate that for this particular mine the proposed 3-D RLSA results in 24% increase in the coal recovery ratio and a modest reduction in excavation and maintenance costs compared to the conventional LTCC method.

  10. Selected legal aspects of traumatism and the education system of workers

    Energy Technology Data Exchange (ETDEWEB)

    Latman, A.M. (Shakhta No 3 Velikomostovskaya (USSR))


    Analyzes legal aspects of responsibility for accidents in underground coal mines in the USSR. The existing system of classification of types of coal miner occupations (the EKTS job description system) introduces an excessively large number of occupational groups. Each group knows only one type of operation (e.g. only operations of a driver of a shearer loader, or control of powered supports at a longwall face). When a driver of a shearer loader advances powered supports and an accident occurs he has an automatic legal responsibility as he has performed operations exceeding his job description. The same situation occurs if a supervisor instructs a coal miner to participate in an emergency rescue operation which exceeds the standard job description of a miner. Such a system is found to be irrational; introducing changes in the system of job descriptions for coal miners in the USSR is recommended.

  11. The Pittsburgh seam: the beast of the East

    Energy Technology Data Exchange (ETDEWEB)

    Morey, M. [RDI Consulting, Arlington, VA (United States)


    The Pittsburgh seam region is made up of large underground mines in a small portion of northern Appalachia. Production from these mines rose to 80 million tons in the late 1990s. Most mines employ longwall technology. Resource Data International examined coal production on a quarterly basis at each of the mines working the Pittsburgh seam. The review showed that while output ranged between 18 to 21 million tons on a quarterly basis, mining efficiency has been recording steady gains. Productivity has increased to nearly 6 tons per worker-hour in the first quarter of 2001. The fairly diverse markets for Pittsburgh seam coal are discussed in the short article. 1 fig., 1 tab.

  12. Numerical Simulation of Squeezing Failure in a Coal Mine Roadway due to Mining-Induced Stresses (United States)

    Gao, Fuqiang; Stead, Doug; Kang, Hongpu


    Squeezing failure is a common failure mechanism experienced in underground coal mine roadways due mainly to mining-induced stresses, which are much higher than the strength of rock mass surrounding an entry. In this study, numerical simulation was carried out to investigate the mechanisms of roadway squeezing using a novel UDEC Trigon approach. A numerical roadway model was created based on a case study at the Zhangcun coal mine in China. Coal extraction using the longwall mining method was simulated in the model with calculation of the mining-induced stresses. The process of roadway squeezing under severe mining-induced stresses was realistically captured in the model. Deformation phenomena observed in field, including roof sag, wall convexity and failed rock bolts are realistically produced in the UDEC Trigon model.

  13. Model proposal for representing a deep coal mine spatial and functional structure

    Directory of Open Access Journals (Sweden)

    Sebastian Iwaszenko


    Full Text Available Underground coal mining usually requires the development of a set of underground corridors (workings. The workings fulfill many different functions. They are used for transportation, ventilation, dewatering and even escape pathways. The proposition of a formal representation of a working's structure for deep coal mining has been presented. The model was developed as a basis for the software system, support management and operational activities for longwall deep mine. The proposed solution is based on graph formalism along with its matrix representation. However, the idea of matrix representation is enhanced. Not only are the topological properties of workings structure considered, but also information about their functions and spatial characteristic. The object model was designed and implemented based upon the matrix idea.

  14. Economic baselines for current underground coal mining technology (United States)

    Mabe, W. B.


    The cost of mining coal using a room pillar mining method with continuous miner and a longwall mining system was calculated. Costs were calculated for the years 1975 and 2000 time periods and are to be used as economic standards against which advanced mining concepts and systems will be compared. Some assumptions were changed and some internal model stored data was altered from the original calculations procedure chosen, to obtain a result that more closely represented what was considered to be a standard mine. Coal seam thicknesses were varied from one and one-half feet to eight feet to obtain the cost of mining coal over a wide range. Geologic conditions were selected that had a minimum impact on the mining productivity.

  15. Shooting on shift: Conventional mining utilizing permissible explosives underground in southeastern Illinois

    International Nuclear Information System (INIS)

    Wooton, D.G.


    Presently, 98 percent of all underground coal mined in Illinois is produced by either continuous or longwall miner. Conventional mining had declined due to various factors. Conventional producing sections require one-third more personnel than continuous miner sections. Two additional pieces of equipment are required on a conventional section. More importantly, the limitations of using compressed air as a means of breaking down cut coal in Illinois left the industry behind the other states who use permissible explosives. The use of high pressure air unnecessarily exposed miners to the hazards of ruptured air lines and excessive exposure to a half-shot coal face, unsupported roof, and dusty conditions. For conventional mining to be considered safe and feasible, shooting-on-shift with permissible explosives is necessary

  16. Recent developments in coal mining technology and their impact on miners' health. (United States)

    Taylor, L D; Thakur, P C


    Advances in technology have significantly reduced the long-term health risks associated with underground coal mining. While the potential risks include exposure to hazardous substances and noise, the reduction of respirable dust in the workplace has been emphasized here because of the greater probability of exposure and the well-documented consequences. Since enactment of the Mine Health and Safety Act of 1969, great strides have been made in reducing worker exposure to respirable dust. As production rates continue to increase, particularly in longwall sections, continued advances in dust control technology will be required. These advances will be needed to meet existing, and perhaps even more stringent future, exposure limits. Mechanization has resulted in a significant reduction in exposure to hazards while increasing productivity. Use of remotely controlled equipment is also increasing rapidly, and efforts are underway to develop completely automated mining systems. These automated systems may further reduce the risk of health impairment due to the underground working environment.

  17. Electrical surveys in detection of seam displacements in mines of the L'vovsko-Volynskii basin

    Energy Technology Data Exchange (ETDEWEB)

    Matyuschechkin, V.F.; Karavaev, V.Ya.; Kozel, K.K.


    Tectonic dislocations are one of the major factors increasing mining cost in the L'vovsko-Volynskii basin. Three tectonic dislocations fall on each long pillar mined by longwall faces. Surveying methods used in the basin for forecasting faults and other tectonic dislocations are discussed. Electrical surveys used in the basin are characterized. Schemes for electric logging used in the basin are discussed: the TEhP-P sequential three-electrode electric logging, the EhDEhP-P sequential equatorial-dipole electric logging, the EhP-P sequential electric logging, the TEhP three-electrode electric logging, the EhDEhP equatorial-dipole electric logging, the EhP electric logging, and the SEhP symmetrical electric profiling. Electrode array in these methods is described. Efficiency of detecting low-amplitude tectonic dislocations using electric logging in the basin is high and amounts to about 80%.

  18. Parameters characterizing distribution of main lateral workings in destressed zones

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, A.F.


    Mine drivage in deep coal mines in the Donbass and site selection for level or inclined workings are comparatively evaluated. Optimizing position of a mine working in relation to working faces in the same seam and in other coal seams is analyzed. The optimization is aimed at reducing deformation of workings. Four schemes of mine working distribution are: main roadways of a mining level are driven in destressed strata; mine roadways are driven in rock strata prior to stress relaxation by mining; a combined scheme (one roadway, in most cases an incline, is driven in rock strata prior to stress relaxation; two roadways are driven at a later stage after destressing of the rock strata); a so-called joint scheme in which inclined mine roadways are driven in strata destressed by an advancing longwall face. Recommendations are made for the use of the four mine drivage schemes at mining depths to 1000 m and deeper. 7 references.

  19. Improving schemes for planning mining operations in deep mines in the Donbass. Sovershenstvovanie skhem planirovki gornykh rabot na glubokikh shakhtakh Donbassa

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, A.F.; Batmanov, Yu.K.


    This book discusses effects of increasing mining depth in the Donbass on schemes of underground mining and hazards associated with increasing strata stresses, methane emission and higher temperatures. Mining and geologic conditions in the Donbass are characterized: coal seam thickness, inclination, depth, methane emission, mechanical properties of rock strata surrounding coal seams, coal seam properties, water influx rates, temperature gradients. In the next 2 decades the average mining depth in the Donbass will increase to 850 m or 900 m while the maximum mining depth will increase to 1400 m or 1600 m. Effects of increasing depth on stresses, strata movement, roof subsidence and floor heave are analyzed. Methods for strata control efficient at large depths are comparatively evaluated: mining with caving, mining with stowing, partial stowing, mining without leaving support pillars. Three mining schemes are analyzed: longwall mining, long pillar mining and a combined scheme. Advantages of long pillar systems under conditions of great depth in the Donbass are evaluated. (20 refs.)

  20. Selection of development and working methods of coal seams in complicated mining and geological conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L.L.; Bakhtin, A.F.; Zel' vyanskii, M.Sh. (Donetskaya Proektnaya Kontora (USSR))


    Presents the design and technological patterns developed at the Donetsk Design Office for planning mining work in difficult mining conditions. The recommended patterns of working are based on the following principles. The most progressive panel development of mine-take and horizon layout methods are used. The main workings are driven as rock drifts with support pillars or they are driven in stress relaxed zones. Seams are worked with pillars or in a combined way. The pillarless technology is based on conducting workings with coal cutting along the excavated space or on repeated utilization of workings. Reduction in stone hoisting to the surface is achieved by execution of drifts that follow the longwalls. Variants of pillar systems with panel development of mine-take and horizon layout development are shown and described.

  1. Evaluation of the reliability and effectiveness of plans for finishing off seams influenced by overlying or underlying workings without the use of pillars

    Energy Technology Data Exchange (ETDEWEB)

    Batmanov, Iu.K.; Bakhtin, A.F.; Bulavka, E.I.


    The pillar-less plan for finishing off seams using longwalls above thick pillars influenced by overlying or underlying workings earlier without the use of pillars on productive (thicker) seams is effective both from the point of view of its reliability and from the economic point of view (even when present techniques are used, as well as under complex mining-geological conditions. The system described is used on the Ukrainian Donbass mines in a total of 13% of the cases out of the overall number of contiguous, gently sloping and inclined coal seams of various thicknessess; the improvement in the amount of coal obtained can be said to have increased by a factor of 2.

  2. Ground engineering principles and practices for underground coal mining

    CERN Document Server

    Galvin, J M


    This book teaches readers ground engineering principles and related mining and risk management practices associated with underground coal mining. It establishes the basic elements of risk management and the fundamental principles of ground behaviour and then applies these to the essential building blocks of any underground coal mining system, comprising excavations, pillars, and interactions between workings. Readers will also learn about types of ground support and reinforcement systems and their operating mechanisms. These elements provide the platform whereby the principles can be applied to mining practice and risk management, directed primarily to bord and pillar mining, pillar extraction, longwall mining, sub-surface and surface subsidence, and operational hazards. The text concludes by presenting the framework of risk-based ground control management systems for achieving safe workplaces and efficient mining operations. In addition, a comprehensive reference list provides additional sources of informati...

  3. Stress analysis of three-dimensional roadway layout of stagger arrangement with field observation (United States)

    Cui, Zimo; Chanda, Emmanuel; Zhao, Jingli; Wang, Zhihe


    Longwall top-coal caving (LTCC) has been a popular, more productive and cost-effective method for extracting thick (> 5 m) to ultra-thick coal seams in recent years. However, low-level recovery ratio of coal resources and top-coal loss above the supports at both ends of working face are long-term problems. Geological factors, such as large dip angle, soft rock, mining depth further complicate the problems. This paper proposes addressing this issue by adopting three-dimensional roadway layout of stagger arrangement (3-D RLSA). In this study, the first step was to analyse the stress environment surrounding head entry in the replacing working face based on the stress distribution characteristics at the triangular coal-pillar side in gob and the stress slip line field theory. In the second step, filed observation was conducted. Finally, an economic evaluation of the 3-D RLSA for extracting thick to ultra-thick seams was conducted.

  4. Degassification and methane drainage in thick and vertical coal seams worked by horizontal sublevel caving method; Drenaje y Desgasificacion de Grisu en Capas de Carbon Potentes y Verticales, Explotadas por subniveles Horizontales con sutiraje

    Energy Technology Data Exchange (ETDEWEB)



    The present trend of the working in spanish coal underground mines is directed towards the utilization, if the deposit characteristics permit it, of mining method by horizontal sublevels with caving. The application of this method involves an important coal volume in specific situations inside the workings cycle (shots, roof cavings, workings beginning, etc). Therefore, those considerable quantities of coal put into circulation, joined to high firedamp concentration desorbable of coal seam, produce in a instantaneous way large volumes of firedamp in the mine atmosphere with the consequent associated risk for the mine people, the stoppage of the works and its evacuation. These aforementioned risks could be avoided, or at least decreased to a great extent, through a methane capture before its circulation in openings caused by the mining works or by draining from accumulation rooms. During the last years, basically in EU countries, some researches have been accomplished about previous Degassification and methane capture in longwall faces of horizontal seams. In these researches have been studied the methane capture both from surface and from underground. In sublevel caving workings, substantially different from longwall faces workings, the techniques and capture systems utilized in the first one are not applicable to the second. The field works and measurements of this project have been mainly carried out in two mining companies located at the north of Spain, the Mina la Camocha S. A. and the S. A. Hullera Vasco Leonesa. Many methane capture tests by means of boreholes in coal seam have been carried out to determine the influence that capture boreholes exert in degassification of coal panel. Otherwise, many firedamp drainage tests in accumulation rooms have been also carried out, and a small-scale system that makes possible the capture in safe conditions have been defined and tested. (Author)

  5. Comparison of Methane Control Methods in Polish and Vietnamese Coal Mines

    Directory of Open Access Journals (Sweden)

    Borowski Marek


    Full Text Available Methane hazard often occurs in hard coal mines and causes very serious accidents and can be the reason of methane or methane and coal dust explosions. History of coal mining shows that methane released from the rock mass to the longwall area was responsible for numerous mining disasters. The main source of methane are coal deposits because it is autochthonous gas and is closely related with carbonification and forming of coal deposits. Degree of methane saturation in coal deposits depends on numerous factors; mainly on presence or lack of insulating layers in cover deposit that allow or do not on degasification and easily methane outflow into surroundings. Hence in coal mining there are coal deposits that contain only low degree of methane saturation in places where is lack of insulating layers till high in methane coal deposits occurring in insulating claystones or in shales. Conducting mining works in coal deposits of high methane hazard without using of special measures to combat (ventilation, methane drainage could be impossible. Control of methane hazard depends also on other co-occuring natural dangers for which used preventive actions eliminate methane hazard. Safety in mines excavating coal deposits saturated with methane depends on the correct estimation of methane hazard, drawn up forecasts, conducted observations, hazard control as well as undertaken prevention measures. Methane risk prevention includes identification and control methods of methane hazards as well as means of combating the explosive accumulation of methane in longwall workings. The main preventive actions in underground coal mines are: effective ventilation that prevents forming of methane fuses or placed methane accumulation in headings ventilated by airflow created by main fans and in headings with auxiliary ventilation, methane drainage using drain holes that are drilled from underground headings or from the surface, methanometry control of methane concentration in

  6. Comparison of Methane Control Methods in Polish and Vietnamese Coal Mines (United States)

    Borowski, Marek; Kuczera, Zbigniew


    Methane hazard often occurs in hard coal mines and causes very serious accidents and can be the reason of methane or methane and coal dust explosions. History of coal mining shows that methane released from the rock mass to the longwall area was responsible for numerous mining disasters. The main source of methane are coal deposits because it is autochthonous gas and is closely related with carbonification and forming of coal deposits. Degree of methane saturation in coal deposits depends on numerous factors; mainly on presence or lack of insulating layers in cover deposit that allow or do not on degasification and easily methane outflow into surroundings. Hence in coal mining there are coal deposits that contain only low degree of methane saturation in places where is lack of insulating layers till high in methane coal deposits occurring in insulating claystones or in shales. Conducting mining works in coal deposits of high methane hazard without using of special measures to combat (ventilation, methane drainage) could be impossible. Control of methane hazard depends also on other co-occuring natural dangers for which used preventive actions eliminate methane hazard. Safety in mines excavating coal deposits saturated with methane depends on the correct estimation of methane hazard, drawn up forecasts, conducted observations, hazard control as well as undertaken prevention measures. Methane risk prevention includes identification and control methods of methane hazards as well as means of combating the explosive accumulation of methane in longwall workings. The main preventive actions in underground coal mines are: effective ventilation that prevents forming of methane fuses or placed methane accumulation in headings ventilated by airflow created by main fans and in headings with auxiliary ventilation, methane drainage using drain holes that are drilled from underground headings or from the surface, methanometry control of methane concentration in the air; location

  7. Application of Elements of TPM Strategy for Operation Analysis of Mining Machine (United States)

    Brodny, Jaroslaw; Tutak, Magdalena


    Total Productive Maintenance (TPM) strategy includes group of activities and actions in order to maintenance machines in failure-free state and without breakdowns thanks to tending limitation of failures, non-planned shutdowns, lacks and non-planned service of machines. These actions are ordered to increase effectiveness of utilization of possessed devices and machines in company. Very significant element of this strategy is connection of technical actions with changes in their perception by employees. Whereas fundamental aim of introduction this strategy is improvement of economic efficiency of enterprise. Increasing competition and necessity of reduction of production costs causes that also mining enterprises are forced to introduce this strategy. In the paper examples of use of OEE model for quantitative evaluation of selected mining devices were presented. OEE model is quantitative tool of TPM strategy and can be the base for further works connected with its introduction. OEE indicator is the product of three components which include availability and performance of the studied machine and the quality of the obtained product. The paper presents the results of the effectiveness analysis of the use of a set of mining machines included in the longwall system, which is the first and most important link in the technological line of coal production. The set of analyzed machines included the longwall shearer, armored face conveyor and cruscher. From a reliability point of view, the analyzed set of machines is a system that is characterized by the serial structure. The analysis was based on data recorded by the industrial automation system used in the mines. This method of data acquisition ensured their high credibility and a full time synchronization. Conclusions from the research and analyses should be used to reduce breakdowns, failures and unplanned downtime, increase performance and improve production quality.

  8. Forecast and Prevention of Coal and Gas Outbursts in the Case of Application of a New Mining Method - Drilling of a Coal Pillar

    Directory of Open Access Journals (Sweden)

    Vlastimil Hudeček


    Full Text Available Coal and gas outbursts are one of risk factors accompanying the mining of coal in low seams in the Ostrava-Karviná Coalfield.At the use of the method of longwall mining, all coal reserves have not been mined out owing to tectonic faults. For mining outthe residual reserves, the application of a new mining method - drilling of a coal pillar was proposed.The method of mining of a coal seam utilizing long large diameter boreholes is verified in the Paskov Mine (company OKD, JSC –Czech Republic under conditions of rock mass with hazard of rock and gas outbursts in localities of residual pillars left in seams afterfinishing the mining operations performed with using the classical method of longwall working along the strike. [5]Forecast and preventive measures applied to the verification of the new method were based on previous experience withthe mining of seams with hazard of coal and gas outbursts. They accepted fully valid legislation, i.e. Ordinance of Ostrava RegionalMining Authority No. 3895/2002 and supplementary materials (Instructions and Guidelines. The proposed measures respectedthe character of the method being verified. [4]For all areas being mined, projects containing also chapters specifying the problems of ensuring the safety of mining worksand operation under conditions of hazard of coal and gas outbursts were prepared.In the contributions, basic proposals for the principles of coal and gas outburst forecast and prevention when applying the newmining method – drilling of a coal pillar are presented

  9. [Psychiatric aspects in workers subject to mobbing]. (United States)

    Bernabei, A; Gebhardt, Eva; Petrucci, Manuela


    Mobbing in the language of ethologists means a particular behaviour of a group of animals consisting of several members forming an alliance against a single animal, in order to eliminate this animal away from the group. This term has been adopted in current usage to mean a kind of relationship at the workplace that, by aggressive and underhand means, aims at influencing or expelling the person. The term "bossing" is used to indicate a negative action, under the meaning described above, made by one or more senior persons, or possibly by the employer. In the Italian Parliament, under the current legislature, several bills are pending regarding this problem. Besides the aspects of topical interest in the problem, there are first and foremost the different kinds of reaction-adaptation to mobbing, according to the type of individual internal working models in action, that can be anxious/avoiding, anxious/resistant or disorganised. The purpose of our study was a clinical evaluation of the different ways of adaptation-reaction to a mobbing-type relationship at the workplace, and of the type of internal working models found among the examined patients. A clinical interview was carried out with 40 patients who, over a period of 12 months of observation, came to request a clinical assessment, for medical-legal reasons, of their psycho-pathological state and ways to react to adverse situations at the workplace, such as a mobbing or bossing. Besides the psychological and relational effects of mobbing, the reactions of the examined subjects to mobbing are also described, considering also the different cognitive self-organization possibilities, according to the individual internal working model, regarding patterns of attachment in adult age. The most frequent internal working model seems to be the one related to resistant attachment, followed by the avoidance and lastly--rarely--the disorganized model. Furthermore we observed among these subjects a certain deficit in meta


    Directory of Open Access Journals (Sweden)

    Pizarro Hannia Cabezas


    Full Text Available Resumen:Este artículo es un estudio exploratorio que buscó identificar la presencia de conductas agresivas en escolares costarricenses. Se seleccionó una muestra intencional de 916 estudiantes de 9 a 14 años que cursan de tercero a sexto grado en diversos centros educativos del país, ubicados tanto en zonas rurales como urbanas y se aplicó una encuesta piloto. Del análisis de datos se desprende que un 14.3% de alumnos ha agredido de una u otra forma a sus iguales. Se concluye que la presencia de conductas agresivas en niños en edad escolar en la escuela costarricense es una realidad. De los datos se desprende que un 21% de los estudiantes que agreden a sus iguales son hombres y un 9% son mujeres. Los varones utilizan más la fuerza física y las mujeres acosan a sus iguales de forma solapada. Los datos se analizan porcentualmente en función de la incidencia del criterio que se pretende valorar.Abstract:This article was an exploratory study that seeks to identify the presence of aggressive behavior in Costa Rican school. We selected a purposive sample of 916 students from 9 to 14 years old enrolled in third through sixth grade in various schools in the country, located in both rural and urban areas. This was a pilot survey. Data analysis showed that 14.3% of students have been assaulted in one way or another to their peers. We conclude that the presence of aggressive behavior in school-age children in school in Costa Rica is a reality. Data showed that 21% of students who bully their peers were men and 9% were women. Males used more physical force while women harass their peers in an underhanded way. The data were analyzed based on the percentage incidence of the criteria that is intended to assess.

  11. Viral Management as a New Type of Enterprise Management in Coal Industry (United States)

    Garafonova, Olga; Grigashkina, Svetlana; Zhosan, Anna


    The article considers the evolution of the concept of "management". The Internet analysis of the concept of "viral management" was conducted, the results of which testify to the positive trend, the growing interest in scientific circles, the relevance of the chosen direction for further research and the increasing popularity of the viral management among business leaders. The indices of coal and brown coal extraction in Ukraine and Russia for 2010-2016 are analyzed. Among the problems that exist in the coal industry are the following: mine assets have a high degree of deterioration; the equipment is rather obsolete and does not correspond to the world level; among the existing face equipment, the specific weight of longwall mining equipment, road headers, loading machines, and belt conveyors of the new generation is only several percent. Five steps of introduction of the virus management at the enterprise are identified: opening, development, participation, diffusion, sustainability. The principles of introduction of the viral management in the enterprises of the coal industry are offered. It is established that the main idea of the viral management is to "infect" the organization and, mainly, employees with one or another "virus" in the form of a common idea or goal. It is indicated that the viral management assumes a certain automaticity of changes, internal "obsession" with this or other innovation, involvement of an informal personal factor.

  12. Strengthening Borehole Configuration from the Retaining Roadway for Greenhouse Gas Reduction: A Case Study (United States)

    Xue, Fei; Zhang, Nong; Feng, Xiaowei; Zheng, Xigui; Kan, Jiaguang


    A monitoring trial was carried out to investigate the effect of boreholes configuration on the stability and gas production rate. These boreholes were drilled from the retaining roadway at longwall mining panel 1111(1) of the Zhuji Coalmine, in China. A borehole camera exploration device and multiple gas parameter measuring device were adopted to monitor the stability and gas production rate. Research results show that boreholes 1~8 with low intensity and thin casing thickness were broken at the depth of 5~10 m along the casing and with a distance of 2~14 m behind the coal face, while boreholes 9~11 with a special thick-walled high-strength oil casing did not fracture during the whole extraction period. The gas extraction volume is closely related to the boreholes stability. After the stability of boreholes 9~11 being improved, the average gas flow rate increased dramatically 16-fold from 0.13 to 2.21 m3/min, and the maximum gas flow rate reached 4.9 m3/min. Strengthening boreholes configuration is demonstrated to be a good option to improve gas extraction effect. These findings can make a significant contribution to the reduction of greenhouse gas emissions from the coal mining industry. PMID:25633368

  13. Strengthening borehole configuration from the retaining roadway for greenhouse gas reduction: a case study.

    Directory of Open Access Journals (Sweden)

    Fei Xue

    Full Text Available A monitoring trial was carried out to investigate the effect of boreholes configuration on the stability and gas production rate. These boreholes were drilled from the retaining roadway at longwall mining panel 1111(1 of the Zhuji Coalmine, in China. A borehole camera exploration device and multiple gas parameter measuring device were adopted to monitor the stability and gas production rate. Research results show that boreholes 1~8 with low intensity and thin casing thickness were broken at the depth of 5~10 m along the casing and with a distance of 2~14 m behind the coal face, while boreholes 9~11 with a special thick-walled high-strength oil casing did not fracture during the whole extraction period. The gas extraction volume is closely related to the boreholes stability. After the stability of boreholes 9~11 being improved, the average gas flow rate increased dramatically 16-fold from 0.13 to 2.21 m3/min, and the maximum gas flow rate reached 4.9 m3/min. Strengthening boreholes configuration is demonstrated to be a good option to improve gas extraction effect. These findings can make a significant contribution to the reduction of greenhouse gas emissions from the coal mining industry.

  14. Viral Management as a New Type of Enterprise Management in Coal Industry

    Directory of Open Access Journals (Sweden)

    Garafonova Olga


    Full Text Available The article considers the evolution of the concept of “management”. The Internet analysis of the concept of “viral management” was conducted, the results of which testify to the positive trend, the growing interest in scientific circles, the relevance of the chosen direction for further research and the increasing popularity of the viral management among business leaders. The indices of coal and brown coal extraction in Ukraine and Russia for 2010-2016 are analyzed. Among the problems that exist in the coal industry are the following: mine assets have a high degree of deterioration; the equipment is rather obsolete and does not correspond to the world level; among the existing face equipment, the specific weight of longwall mining equipment, road headers, loading machines, and belt conveyors of the new generation is only several percent. Five steps of introduction of the virus management at the enterprise are identified: opening, development, participation, diffusion, sustainability. The principles of introduction of the viral management in the enterprises of the coal industry are offered. It is established that the main idea of the viral management is to “infect” the organization and, mainly, employees with one or another “virus” in the form of a common idea or goal. It is indicated that the viral management assumes a certain automaticity of changes, internal “obsession” with this or other innovation, involvement of an informal personal factor.

  15. Angles of total shifts and angles of maxumum crop during development of faces diagonal to seam strike directions

    Directory of Open Access Journals (Sweden)

    Н. А. Колесник


    Full Text Available When predicting deformations and determining measures to protect underworked objects, angular parameters are used: the boundary angles, the angles of total shift, the angle of maximum crop. The values of these angular parameters are given in the normative documents, but only for sections across and along the strike of the formation. However, at present, longwall face mining is mainly being carried out along a diagonal direction to the strike of the formation. In connection with this, the determination of the values of the angular parameters for such conditions is a topical task.The method of determination and the analytical dependences of the angles of total shifts and angles of maximum crop in sections of the longitudinal and transverse axes of coal-mining faces developed along diagonal directions to the strike of the formation are proposed. These angular parameters are used for prognosis of deformations of the earth's surface and for determining the characteristic zones of influence of mine workings on the local places.

  16. Possibility of using the smoothed spline functions in approximation of average course of terrain inclinations caused by underground mining exploitation conducted at medium depth (United States)

    Orwat, J.


    In this paper was presented an obtainment way of the average values of terrain inclinations caused by an exploitation of the 338/2 coal bed, conducted at medium depth by four longwalls. The inclinations were measured at sections of measuring line established over the excavations, perpendicularly to their runways, after the termination of subsequent exploitation stages. The average courses of measured inclinations were calculated on the basis of average values of measured subsidence obtained as a result of an average-square approximation done by the use of smooth splines, in reference to their theoretical values calculated via the S. Knothe’s and J. Bialek’s formulas. The typical values of parameters of these formulas were used. Thus it was obtained for two average courses after the ending of each exploitation period. The values of standard deviations between average and measured inclinations σI and variability coefficients of random scattering of inclinations MI were calculated. Then they were compared with the values appearing in the literature and based on this the possibility evaluation of use smooth splines to determination of average course of observed inclinations of mining area was conducted.

  17. The impact of changes in the rheological parameters of fine-grained hydromixtures on the efficiency of a selected industrial gravitational hydraulic transport system (United States)

    Popczyk, Marcin


    Polish hard coal mines commonly use hydromixtures in their fire prevention practices. The mixtures are usually prepared based on mass-produced power production wastes, namely the ashes resulting from power production [1]. Such hydromixtures are introduced to the caving area which is formed due to the advancement of a longwall. The first part of the article presents theoretical fundamentals of determining the parameters of gravitational hydraulic transport of water and ash hydromixtures used in the mining pipeline systems. Each hydromixture produced based on fine-grained wastes is characterized by specified rheological parameters that have a direct impact on the future flow parameters of a given pipeline system. Additionally, the gravitational character of the hydraulic transport generates certain limitations concerning the so-called correct hydraulic profile of the system in relation to the applied hydromixture characterized by required rheological parameters that should ensure safe flow at a correct efficiency [2]. The paper includes an example of a gravitational hydraulic transport system and an assessment of the correctness of its hydraulic profile as well as the assessment of the impact of rheological parameters of fine-grained hydromixtures (water and ash) produced based on laboratory tests, depending on the specified flow parameters (efficiency) of the hydromixture in the analyzed system.

  18. Twentieth anniversary of the fusion of the Wanda-Lech and Pokoj mines at Ruda Slaska

    Energy Technology Data Exchange (ETDEWEB)

    Pisarek, P.; Baranowski, Z.; Maczka, a.; Kowalski, Z.


    Presents the history of the Wanda-Lech and Pokoj mines until 1968 when they were fused, and development, technical progress and investment in the mines since 1968. Application of longwall equipment sets dates from 1965. The index of powered winning has reached 93.7% and that of powered loading - 97.4%. Seismoacoustic (1970/71) and microseismologic (1974) monitoring stations have been put into operation. The following investments have been realized since 1968: the main shaft Wanda and auxiliary shaft Lech II, two winning horizons, 3 main ventilation fans, a coal preparation plant, a bathhouse for 2,650 and a boiler house fuelled with run-of-mine methane. Mine communications, rail transport and storage facilitites have been modernized and extended. The mining area of the present Pokoj mine is shown in a scheme. Production before and after the take-over is compared: production increased from 1.969121 Mt in 1968 to 2.434740 Mt in 1987. A rehabilitation center (physical therapy, inhalation kinesthesia, hydrotherapy) cares for 2,000 patients annually. Further social services and facilities provided for the miners are described.

  19. Coal production, 1991

    International Nuclear Information System (INIS)


    Coal production in the United States in 1991 declined to a total of 996 million short tons, ending the 6-year upward trend in coal production that began in 1985. The 1991 figure is 33 million short tons below the record level of 1.029 billion short tons produced in 1990 (Table 1). Tables 2 through 33 in this report include data from mining operations that produced, prepared, and processed 10,000 or more short tons during the year. These mines yielded 993 million short tons, or 99.7 percent of the total coal production in 1991, and their summary statistics are discussed below. The majority of US coal (587 million short tons) was produced by surface mining (Table 2). Over half of all US surface mine production occurred in the Western Region, though the 60 surface mines in this area accounted for only 5 percent of the total US surface mines. The high share of production was due to the very large surface mines in Wyoming, Texas and Montana. Nearly three quarters of underground production was in the Appalachian Region, which accounted for 92 percent of underground mines. Continuous mining methods produced the most coal among those underground operations that responded. Of the 406 million short tons, 59 percent (239 million short tons) was produced by continuous mining methods, followed by longwall (29 percent, or 119 million short tons), and conventional methods (11 percent, or 46 million short tons)

  20. Integrated coal preparation

    International Nuclear Information System (INIS)

    Buchanan, D.J.; Jones, T.F.


    Perceptions of quality have changed over the years. The attributes of a certain coal (its rank, slagging propensity, ash content etc) are traditionally referred to as its quality. However, the subject of this paper is quality in a much wider sense: quality as fitness for purpose: and all that such a wide definition entails. British Standard BS 5750 (ISO 9000) Quality Systems defines a systems approach to quality, and includes both the supplier of raw materials and the final customer within this boundary. Coal preparation starts at the production face. The greater the proportion of dirt in run-of-mine product the greater the challenge in satisfying the customer's needs. Significant advances have been made in minimizing mined dirt. For example, the sue of vertical steering on longwall faces improves productivity and quality. Unfortunately modern mining methods produce large quantities of fines, despite efforts to reduce them at the point of production and during transportation to the surface. Coal preparation also produces further fines. It has been estimated that fine coal costs 2.5 times as much to clean as large coal, and the costs of handing wet fine coal product will inflate this estimate. Handling considerations rightly concern our customers and are part of the wider meaning of quality. In this paper the authors address some novel solutions to the challenge posed by fines

  1. Review of potential subsurface permeable barrier emplacement and monitoring technologies

    Energy Technology Data Exchange (ETDEWEB)

    Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.; Schwarz, R.M. [Ebasco Environmental, Richland, WA (United States); Cantrell, K.J. [Pacific Northwest Lab., Richland, WA (United States); Phillips, S.J. [Westinghouse Hanford Co., Richland, WA (United States)


    This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, or excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods.

  2. Modelling of strata movement with a special reference to caving mechanism in thick seam coal mining

    Energy Technology Data Exchange (ETDEWEB)

    Unver, B.; Yasitli, N.E. [Hacettepe University, Department of Mining Engineering, Beytepe 06532, Ankara (Turkey)


    Caving of top coal behind the face is the key factor affecting the efficiency of production at thick coal seams. During production of top coal by caving behind the face not only is a significant amount of coal lost in the goaf but also the coal drawn by means of caving is usually diluted considerably with surrounding rock. Therefore, it is not possible to carry out an efficient production operation unless caving of top coal behind the face is optimized. In this paper, results of 3-D modelling of the top coal caving mechanism at the M3 longwall panel of Omerler Underground Mine located at Tuncbilek (Turkey) are presented by using a finite difference code called FLAC{sup 3D}. According to modelling results, a 1.5-2.0-m-thick layer of coal just above the shield supports is well fractured. However, 3.0-3.5-m-thick layer of coal above the well-fractured part is either not fractured or fractured in the form of large blocks leading to obstruction of windows of shields during coal drawing. It is concluded that, in order to decrease dilution and increase extraction ratio and production efficiency, the top coal should be as uniformly fractured as much as possible. Hence, an efficient and continuous coal flowing behind the face can be maintained. A special pre-fracture blasting strategy just sufficient enough to form cracks in the top coal is suggested by means of comparing results from numerical modelling. (author)

  3. Time-dependent seismic hazard in Bobrek coal mine, Poland, assuming different magnitude distribution estimations (United States)

    Leptokaropoulos, Konstantinos; Staszek, Monika; Cielesta, Szymon; Urban, Paweł; Olszewska, Dorota; Lizurek, Grzegorz


    The purpose of this study is to evaluate seismic hazard parameters in connection with the evolution of mining operations and seismic activity. The time-dependent hazard parameters to be estimated are activity rate, Gutenberg-Richter b-value, mean return period and exceedance probability of a prescribed magnitude for selected time windows related with the advance of the mining front. Four magnitude distribution estimation methods are applied and the results obtained from each one are compared with each other. Those approaches are maximum likelihood using the unbounded and upper bounded Gutenberg-Richter law and the non-parametric unbounded and non-parametric upper-bounded kernel estimation of magnitude distribution. The method is applied for seismicity occurred in the longwall mining of panel 3 in coal seam 503 in Bobrek colliery in Upper Silesia Coal Basin, Poland, during 2009-2010. Applications are performed in the recently established Web-Platform for Anthropogenic Seismicity Research, available at

  4. On-Site Radon Detection of Mining-induced Fractures from Overlying Strata to the Surface: A Case Study of the Baoshan Coal Mine in China

    Directory of Open Access Journals (Sweden)

    Wei Zhang


    Full Text Available Large-scale longwall mining of shallow coal seams may cause mining-induced fractures that can project completely through to the surface. This could lead to a series of mine safety and environmental issues, further deteriorating the already fragile ecological environment in the Western mining areas in China. Therefore, an accurate and effective understanding of the spatiotemporal evolution law of mining-induced fractures in overlying strata and its relationship to upper aquifers is critical. In this paper, the application of the geophysical-chemical properties of radon in mining engineering is explored as a potential solution to the shortcomings of existing surveying methods. A radioactive measurement method is proposed for the detection of the development of mining-induced fractures from overlying strata to the surface in the Baoshan Coal Mine (BCM. The on-site test indicated that the first weighting step is approximately 60 m, the average periodic weighting step is approximately 20 m, and the influence coverage of the advanced abutment pressure is approximately 30 m. The presented method could be used as an indirect technical support to increase the safety of coal mining by acting as a simple, fast, and reliable method of detecting mining-induced fractures in overlying strata.

  5. The possibility of increasing the efficiency of accessible coal deposits by optimizing dimensions of protective pillars or the scope of exploitation (United States)

    Bańka, Piotr; Badura, Henryk; Wesołowski, Marek


    One of the ways to protect objects exposed to the influences of mining exploitation is establishing protective pillars for them. Properly determined pillar provides effective protection of the object for which it was established. Determining correct dimensions of a pillar requires taking into account contradictory requirements. Protection measures against the excessive influences of mining exploitation require designing the largest possible pillars, whereas economic requirements suggest a maximum reduction of the size of resources left in the pillar. This paper presents algorithms and programs developed for determining optimal dimensions of protective pillars for surface objects and shafts. The issue of designing a protective pillar was treated as a nonlinear programming task. The objective function are the resources left in a pillar while nonlinear limitations are the deformation values evoked by the mining exploitation. Resources in the pillar may be weighted e.g. by calorific value or by the inverse of output costs. The possibility of designing pillars of any polygon shape was taken into account. Because of the applied exploitation technologies the rectangular pillar shape should be considered more advantageous than the oval one, though it does not ensure the minimization of resources left in a pillar. In this article there is also presented a different approach to the design of protective pillars, which instead of fixing the pillar boundaries in subsequent seams, the length of longwall panels of the designed mining exploitation is limited in a way that ensures the effective protection of an object while maximizing the extraction ratio of the deposit.

  6. Geomechanics of subsidence above single and multi-seam coal mining

    Directory of Open Access Journals (Sweden)

    A.M. Suchowerska Iwanec


    Full Text Available Accurate prediction of surface subsidence due to the extraction of underground coal seams is a significant challenge in geotechnical engineering. This task is further compounded by the growing trend for coal to be extracted from seams either above or below previously extracted coal seams, a practice known as multi-seam mining. In order to accurately predict the subsidence above single and multi-seam longwall panels using numerical methods, constitutive laws need to appropriately represent the mechanical behaviour of coal measure strata. The choice of the most appropriate model is not always straightforward. This paper compares predictions of surface subsidence obtained using the finite element method, considering a range of well-known constitutive models. The results show that more sophisticated and numerically taxing constitutive laws do not necessarily lead to more accurate predictions of subsidence when compared to field measurements. The advantages and limitations of using each particular constitutive law are discussed. A comparison of the numerical predictions and field measurements of surface subsidence is also provided.

  7. Use of IT platform in determination of efficiency of mining machines (United States)

    Brodny, Jarosław; Tutak, Magdalena


    Determination of effective use of mining devices has very significant meaning for mining enterprises. High costs of their purchase and tenancy cause that these enterprises tend to the best use of possessed technical potential. However, specifics of mining production causes that this process not always proceeds without interferences. Practical experiences show that determination of objective measure of utilization of machine in mining enterprise is not simple. In the paper a proposition for solution of this problem is presented. For this purpose an IT platform and overall efficiency model OEE were used. This model enables to evaluate the machine in a range of its availability performance and quality of product, and constitutes a quantitative tool of TPM strategy. Adapted to the specificity of mining branch the OEE model together with acquired data from industrial automatic system enabled to determine the partial indicators and overall efficiency of tested machines. Studies were performed for a set of machines directly use in coal exploitation process. They were: longwall-shearer and armoured face conveyor, and beam stage loader. Obtained results clearly indicate that degree of use of machines by mining enterprises are unsatisfactory. Use of IT platforms will significantly facilitate the process of registration, archiving and analytical processing of the acquired data. In the paper there is presented methodology of determination of partial indices and total OEE together with a practical example of its application for investigated machines set. Also IT platform was characterized for its construction, function and application.

  8. Numerical Approach for Goaf-Side Entry Layout and Yield Pillar Design in Fractured Ground Conditions (United States)

    Jiang, Lishuai; Zhang, Peipeng; Chen, Lianjun; Hao, Zhen; Sainoki, Atsushi; Mitri, Hani S.; Wang, Qingbiao


    Entry driven along goaf-side (EDG), which is the development of an entry of the next longwall panel along the goaf-side and the isolation of the entry from the goaf with a small-width yield pillar, has been widely employed in China over the past several decades . The width of such a yield pillar has a crucial effect on EDG layout in terms of the ground control, isolation effect and resource recovery rate. Based on a case study, this paper presents an approach for evaluating, designing and optimizing EDG and yield pillar by considering the results from numerical simulations and field practice. To rigorously analyze the ground stability, the numerical study begins with the simulation of goaf-side stress and ground conditions. Four global models with identical conditions, except for the width of the yield pillar, are built, and the effect of pillar width on ground stability is investigated by comparing aspects of stress distribution, failure propagation, and displacement evolution during the entire service life of the entry. Based on simulation results, the isolation effect of the pillar acquired from field practice is also considered. The suggested optimal yield pillar design is validated using a field test in the same mine. Thus, the presented numerical approach provides references and can be utilized for the evaluation, design and optimization of EDG and yield pillars under similar geological and geotechnical circumstances.

  9. Study of Coal Burst Source Locations in the Velenje Colliery

    Directory of Open Access Journals (Sweden)

    Goran Vižintin


    Full Text Available The Velenje coal mine (VCM is situated on the largest Slovenian coal deposit and in one of the thickest layers of coal known in the world. The thickness of the coal layer causes problems for the efficiency of extraction, since the majority of mining operations is within the coal layer. The selected longwall coal mining method with specific geometry, increasing depth of excavations, changes in stress state and naturally given geomechanical properties of rocks induce seismic events. Induced seismic events can be caused by caving processes, blasting or bursts of coal or the surrounding rock. For 2.5D visualization, data of excavations, ash content and calorific value of coal samples, hanging wall and footwall occurrence, subsidence of the surface and coal burst source locations were collected. Data and interpolation methods available in software package Surfer®12 were statistically analyzed and a Kriging (KRG interpolation method was chosen. As a result 2.5D visualizations of coal bursts source locations with geomechanical properties of coal samples taken at different depth in the coal seam in the VCM were made with data-visualization packages Surfer®12 and Voxler®3.

  10. Impact of type of the roof rocks on location and range of endogenous fires particular hazard zone by in goaf with caving (United States)

    Tutak, Magdalena; Brodny, Jarosław


    Hazard of endogenous fires is one of the basic and common presented occupational safety hazards in coal mine in Poland and in the world. This hazard means possibility of coal self-ignition as the result of its self-heating process in mining heading or its surrounding. In underground coal-mining during ventilating of operating longwalls takes place migration of parts of airflow to goaf with caving. In a case when in these goaf a coal susceptible to self-ignition occurs, then the airflow through these goaf may influence on formation of favorable conditions for coal oxidation and subsequently to its self-heating and self-ignition. Endogenous fire formed in such conditions can pose a serious hazards for the crew and for continuity of operation of mining plant. From the practical point of view a very significant meaning has determination of the zone in the goaf with caving, in which necessary conditions for occurence of endogenous fire are fulfilled. In the real conditions determination of such a zone is practically impossible. The main aim of the analysis was to determine the impact of type of the roof rocks forming the goaf on the location and range of endogenous fires particular hazard zone by in these goaf. For determined mining-geological conditions, the critical value of velocity of airflow and oxygen concentration in goaf, conditioning initiation of coal oxidation process were determined.

  11. Geomechanical behaviour of laminated, weak coal mine roof strata and the implications for a ground reinforcement strategy

    Energy Technology Data Exchange (ETDEWEB)

    Hebblewhite, B.K.; Lu, T. [University of New South Wales, Sydney, NSW (Australia). School of Mining Engineering


    This paper describes a component of the results from an ARC-SPIRT funded collaborative research project between UNSW, Powercoal Pty Ltd. and Springvale Coal Pty Ltd. The research project was aimed at identifying strategies for appropriate ground control in particularly weak and soft roof strata in underground coal mining. A field investigation was undertaken at Angus Place Colliery in the Western Coalfield of New South Wales. The investigation incorporated a range of geotechnical instrumentation and was conducted over a period of time from the development face until the site was lost into the goaf of a retreating longwall panel. This paper describes the outcomes from the field investigation, together with a selection of supporting laboratory studies. The paper also presents a number of alternative presentation modes for extensometry data. The results clearly demonstrate the time and face-proximity related influences on roof integrity, and particularly demonstrated the distribution of deformation, bed separation and strata failure into the roof and across the full span of the roadway, together with reflection of this behaviour within the fully encapsulated roof bolt reinforcement system installed.

  12. The Development of Dewatering Predictions of the Velenje Coalmine

    Directory of Open Access Journals (Sweden)

    Željko Vukelić


    Full Text Available The complex hydro-geological situation, particularly in terms of groundwater, has been a constant threat to the mining carried out at the Velenje colliery since its inception. Of particular interest to the authors are the difficulties presented to the colliery by the adjacent sand aquifers, as the water pressure within these sands directly impacts mining safety, and the aquifers themselves are most directly affected by dewatering. In order to monitor water levels and estimate dewatering at the Velenje wells, multi-layered modelling using 3D Finite Difference Method (FDM has already been carried out. However, FDM is not optimal due to its greater dependence on cell size than on water flow. In 2017 in Velenje, a series of wells will be terminated as a result of mining and mining-induced subsidence, leading to dewatering and danger of flooding. As part of a plan to address this by replacing dewatering structures, a series of drive-in filters will be implemented around the entry and exit point tunnels of a longwall face. Because FDM seems to be inadequate for purposes of optimising this process, the Finite Elements Method (FEM was applied in this case. Based on such an application of FEM, a prediction of the optimisation of drive-in filters was carried out by the authors.

  13. Origin of acid mine drainage in Enugu

    International Nuclear Information System (INIS)

    Uma, K.O.


    Mine flooding is a serious problem in the Enugu Coal Mines and has led to the abandonment of two of the four mines. About 1800 m 3 of water is pumped out daily from the mines into the nearby streams. The source of this enormous volume of water has been established based on the hydrodynamics and hydrology of the area. Two prolific aquifers - an unconfined and a confined system - overlie the mines, but the mine water is derived principally from the unconfined aquifer. The pathway of flow is, provided by the numerous fractures connecting the two aquifers and the mine tunnel. The major hydrochemical activity resulting in pollution of the mine water occurs within the sumps in the floor of the longwalls. These sumps act as oxidation chambers where groundwater from the fractures mixes and subsequently reacts with sulfur-rich solutes released by coal mining. Contrary to general belief, the mine drainage has not seriously degraded the chemistry of receiving streams. The pH and electric conductivity, representing, the dissolved ions, were increased less than 10% of the values in the unaffected region

  14. Review of potential subsurface permeable barrier emplacement and monitoring technologies

    International Nuclear Information System (INIS)

    Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.; Schwarz, R.M.; Cantrell, K.J.; Phillips, S.J.


    This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, or excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods

  15. Pelletization of fine coals. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, K.V.S.


    Coal is one of the most abundant energy resources in the US with nearly 800 million tons of it being mined annually. Process and environmental demands for low-ash, low-sulfur coals and economic constraints for high productivity are leading the coal industry to use such modern mining methods as longwall mining and such newer coal processing techniques as froth flotation, oil agglomeration, chemical cleaning and synthetic fuel production. All these processes are faced with one common problem area--fine coals. Dealing effectively with these fine coals during handling, storage, transportation, and/or processing continues to be a challenge facing the industry. Agglomeration by the unit operation of pelletization consists of tumbling moist fines in drums or discs. Past experimental work and limited commercial practice have shown that pelletization can alleviate the problems associated with fine coals. However, it was recognized that there exists a serious need for delineating the fundamental principles of fine coal pelletization. Accordingly, a research program has been carried involving four specific topics: (i) experimental investigation of coal pelletization kinetics, (ii) understanding the surface principles of coal pelletization, (iii) modeling of coal pelletization processes, and (iv) simulation of fine coal pelletization circuits. This report summarizes the major findings and provides relevant details of the research effort.

  16. Review of subsidence and stabilization techniques

    International Nuclear Information System (INIS)

    Fernando, D.A.


    In Britain the damage caused by underground coal mining operations approximates to about 100 million pounds Sterling per annum, most of the damage resulting from longwall mining operations. Causes of subsidence can be attributed to the following factors: (1) roof failure (2) pillar failure (3) floor movements. Currently, in Britain, the mining industry is undergoing a state of decline for economic reasons. Consequently, the number of old coal sites available for development schemes has increased. Therefore, the problems associated with subsidence can be segregated into two parts. The first being the mitigation of the effects of subsidence on structures on actively mined areas. The second being the stabilization and rehabilitation of ground over and around old mine sites for new development schemes. In the former case the stabilization techniques employed may be local or global, depending on the problems encountered in any particular area. In the latter case, generally, grouting techniques are employed. This paper aims to review the causes of subsidence and the techniques used to minimize its effect on structures. Also, more economic alternative methods of ground stabilization techniques are described and proposed, to be used in this area of ground engineering

  17. Average course approximation of measured subsidence and inclinations of mining area by smooth splines

    Directory of Open Access Journals (Sweden)

    Justyna Orwat


    Full Text Available The results of marking average courses of subsidence measured on the points of measuring line no. 1 of the “Budryk” Hard Coal Mine, set approximately perpendicularly to a face run of four consecutively mined longwalls in coal bed 338/2 have been presented in the article. Smooth splines were used to approximate the average course of measured subsidence after subsequent exploitation stages. The minimising of the sum of the squared differences between the average and forecasted subsidence, using J. Bialek's formula, was used as a selection criterion of parameter values of smoothing an approximating function. The parameter values of this formula have been chosen in order to match forecasted subsidence with measured ones. The average values of inclinations have been calculated on the basis of approximated values of observed subsidence. It has been shown that by doing this the average values of extreme measured inclinations can be obtained in almost the same way as extreme observed inclinations. It is not necessary to divide the whole profile of a subsidence basin into parts. The obtained values of variability coefficients of a random scattering for subsidence and inclinations are smaller than their values which occur in the literature.

  18. Damages to the roadway tunnels in the coal mining area of Hebi, P.R. China: proposals to minimise damages and numerical analysis

    International Nuclear Information System (INIS)

    Fuchsberger, M.; Schweiger, H.F.


    The influence of a coal mining operation on the roadways constructed in the underlying rock strata is generally well known. In a joint research project between CCMRI (Beijing) and the Technical University Graz (Austria) the frequent damage to the roadways in the Hebi mining area resulting from the longwall mining operation of the overlying coal-seam were investigated. The likely cause of the damage was established and proposals were made to improve the tunnel performance by a modification of the cross-sectional geometry and of the driving operation of the tunnels whereby the principles of the New Austrian Tunnelling Method (NATM) were employed. The aim was to minimise or to avoid the damages caused by the mining operation and thus reduce the high cost of constant repairs. A well instrumented test section of the modified tunnel was constructed and its performance during the ensuing coal extraction was monitored. The paper describes the initial investigations, the NATM proposals, as well as a brief description and the interpretation of a FEM analysis made in this connection. 6 refs., 11 figs., 1 tab

  19. VRLane: a desktop virtual safety management program for underground coal mine (United States)

    Li, Mei; Chen, Jingzhu; Xiong, Wei; Zhang, Pengpeng; Wu, Daozheng


    VR technologies, which generate immersive, interactive, and three-dimensional (3D) environments, are seldom applied to coal mine safety work management. In this paper, a new method that combined the VR technologies with underground mine safety management system was explored. A desktop virtual safety management program for underground coal mine, called VRLane, was developed. The paper mainly concerned about the current research advance in VR, system design, key techniques and system application. Two important techniques were introduced in the paper. Firstly, an algorithm was designed and implemented, with which the 3D laneway models and equipment models can be built on the basis of the latest mine 2D drawings automatically, whereas common VR programs established 3D environment by using 3DS Max or the other 3D modeling software packages with which laneway models were built manually and laboriously. Secondly, VRLane realized system integration with underground industrial automation. VRLane not only described a realistic 3D laneway environment, but also described the status of the coal mining, with functions of displaying the run states and related parameters of equipment, per-alarming the abnormal mining events, and animating mine cars, mine workers, or long-wall shearers. The system, with advantages of cheap, dynamic, easy to maintenance, provided a useful tool for safety production management in coal mine.

  20. Continuous monitoring of mining induced strain in a road pavement using fibre Bragg grating sensors (United States)

    Whelan, B. E.; Brunton, M.; Nosenzo, Giorgio; Kay, Daryl; Buys, Henk


    This paper describes the application of Fibre Bragg Grating (FBG) based sensors for monitoring road pavement strains caused by mining induced ground subsidence as a result of underground longwall coal mining beneath a major highway in New South Wales, Australia. After a lengthy planning period, the risks to the highway pavement were successfully managed by the highway authority and the mining company through a technical committee. The technical committee comprised representatives of the mining company, the highway authority and specialists in the fields of pavement engineering, geotechnical engineering and subsidence. An important component of the management strategy is the installation of a total of 840 strain and temperature sensors in the highway pavement using FBG arrays encapsulated in glass-fibre composite cables. The sensors and associated demodulation equipment provide continuous strain measurements along the pavement, enabling on-going monitoring of the effects of mining subsidence on the pavement and timely implementation of planned mitigation and response measures to ensure the safety and serviceability of the highway throughout the mining period.

  1. Continuous monitoring of mining induced strain in a road pavement using fiber Bragg grating sensors (United States)

    Nosenzo, Giorgio; Whelan, B. E.; Brunton, M.; Kay, Daryl; Buys, Henk


    This paper describes the application of fiber Bragg grating (FBG) based sensors for monitoring road pavement strains caused by mining induced ground subsidence as a result of underground longwall coal mining beneath a major highway in New South Wales, Australia. After a lengthy planning period, the risks to the highway pavement were successfully managed by the highway authority and the mining company through a technical committee. The technical committee comprised representatives of the mining company, the highway authority and specialists in the fields of pavement engineering, geotechnical engineering and subsidence. An important component of the management strategy is the installation of a total of 840 strain and temperature sensors in the highway pavement using FBG arrays encapsulated in glass-fiber composite cables. The sensors and associated demodulation equipment provide continuous strain measurements along the pavement, enabling on-going monitoring of the effects of mining subsidence on the pavement and timely implementation of planned mitigation and response measures to ensure the safety and serviceability of the highway throughout the mining period.

  2. Variability of particle size-specific fractions of personal coal mine dust exposures. (United States)

    Seixas, N S; Hewett, P; Robins, T G; Haney, R


    This study estimated the ratio of the tracheo-bronchial dust fraction to the fraction collected by a respirable dust sampler for a variety of job classifications found in conventional, continuous, and longwall coal mining sections. The ratios could then be applied in epidemiologic studies to existing respirable dust measurements to estimate thoracic mass concentrations for evaluation of the relative importance of the respirable and thoracic dust fractions to obstructive lung disease. Data collected include particle size distributions from four U.S. underground coal mines using eight-stage personal cascade impactors. A total of 180 samples were examined by mine, occupation and occupations grouped by proximity to the mine face, and by mining technology. Several fractions--that collected by the 10-mm nylon cyclone, the American Conference of Governmental Industrial Hygienists respirable and thoracic particulate mass fractions, and the estimated alveolar and tracheo-bronchial deposition fractions--were estimated. These were not significantly different when grouped by occupation, by proximity of work to the mine face, or by the type of mining technology in use. Distributions from one mine varied from the others, perhaps because it used diesel equipment in the haulage ways, which contributed to the fine aerosol fractions. Results suggest that although the tracheo-bronchial dust fraction may contribute to the development of obstructive lung disease, occupation-specific tracheo-bronchial dust fractions are not likely to produce stronger exposure-response estimates than the historically collected respirable dust concentrations.

  3. Occupational safety and health implications of increased coal utilization. (United States)

    Bridbord, K; Costello, J; Gamble, J; Groce, D; Hutchison, M; Jones, W; Merchant, J; Ortmeyer, C; Reger, R; Wagner, W L


    An area of major concern in considering increased coal production and utilization is the health and safety of increased numbers of workers who mine, process, or utilize coal. Hazards related to mining activities in the past have been especially serious, resulting in many mine related accidental deaths, disabling injuries, and disability and death from chronic lung disease. Underground coal mines are clearly less safe than surface mines. Over one-third of currently employed underground miners experience chronic lung disease. Other stresses include noise and extremes of heat and cold. Newly emphasized technologies of the use of diesel powered mining equipment and the use of longwall mining techniques may be associated with serious health effects. Workers at coal-fired power plants are also potentially at risk of occupational diseases. Occupational safety and health aspects of coal mining are understood well enough today to justify implementing necessary and technically feasible and available control measures to minimize potential problems associated with increased coal production and use in the future. Increased emphasis on safety and health training for inexperienced coal miners expected to enter the work force is clearly needed. The recently enacted Federal Mine Safety and Health Act of 1977 will provide impetus for increased control over hazards in coal mining.


    International Nuclear Information System (INIS)

    Plis, M.N.; Rohrbacher, T.J.; Teeters, D.D.


    This paper highlights COALVAL, a coal property evaluation software package developed by the U.S. Bureau of Mines (USBM) on Lotus 1-2-3, version 2.2, spreadsheet. The software is also compatible with version 3.1, and provisionally with version 2.01. COALVAL is a menu-driven program that produces a prefeasibility-level cost analysis of mine-planned coal resources. The software contains cost models for each of five coal mining methods commonly employed in Appalachia: auger, contour strip, mountain top removal, continuous miner and longwall. COALVAL allows individuals to input resource data and the various production, operating, and cost variables that pertain to their property The program can evaluate up to 25 seams, each to be mined with up to 5 different mining methods, within a given area. Summary spreadsheet listing the cost per clean ton to mine the resources, F.O.B. The tipple, are produced for each property, seam, and mining method/seam combination

  5. Report on the FY 1995 basic survey for industrialization related to the survey of overseas geological structure (Pondok Labu East area, Indonesia); 1995 nendo kaigai chishitsu kozo nado chosa ni kakawaru kigyoka kiso chosa (Indonesia Pondok Labu higashi chiku) hokokusho

    Energy Technology Data Exchange (ETDEWEB)



    The survey was conducted based on 'Scope of work for detailed coal exploration in the Pondok Labu East area of East Kalimantan Province, Kalimantan, Indonesia' concluded on June 16, 1995 between NEDO and P.T. Tanito Harum which owns the mining right. The area for survey is approximately 10km west of Tenggarong city, the capital of Kabupaten Kutai, East Kalimantan Province which is northeast part of Kalimantan island of Indonesia. The field survey was divided into the geological/boring survey and the survey of conditions for underground mining development and the infrastructure. This survey made it clear that in the underground mining of PDL7A seam, assuming the minable coal reserve to be 6.81 million tons, it is possible to produce raw coal of 0.5 million tons/year by adopting the longwall pick mining. The raw coal is all prepared, and the yield is 80%. Accordingly, the production of product coal is 0.4 million tons/year. Attached were the boring log (JN9-94-0855), physical log (JN9940856), and BIP survey report (JN9940857). (NEDO)

  6. Experimental Research on Internal Behaviors of Caved Rocks under the Uniaxial Confined Compression

    Directory of Open Access Journals (Sweden)

    Yu-jiang Zhang


    Full Text Available As main composition of longwall gob, caved rocks’ behaviors and their impacts under compression crucially influence strata control, subsidence, associated resources extraction, and many other aspects. However, current researches are based on a whole sample, due to looseness of caved rocks and limitation of observation technology. In this paper, an experiment system was built to investigate internal behaviors of caved rocks’ sample, under the uniaxial confined compression, including movement and breakage behavior by the digital image processing technologies. The results show that the compression process of caved rocks could be divided into two stages by relative density. Boundary effect and changes of voids and contact pressure among caved rocks lead to different movement law in different position in sample’s interior. A stratification phenomenon of breakage was discovered, which presents breakage concentration in the middle of the sample. The nonlinear movement and shear dislocation induced by shifts among caved rocks are the reason of the breakage stratification phenomenon. This phenomenon would have an effect on the permeability and seepage research of similar medium.

  7. An Innovative Support Structure for Gob-Side Entry Retention in Steep Coal Seam Mining

    Directory of Open Access Journals (Sweden)

    Jianguo Ning


    Full Text Available This study considered longwall working face No. 41101—located in a steeply inclined coal seam at the Awuzisu coal mine in Xinjiang, China—as an example in which macroscopic shear cracks had occurred in the cement-based filling body of the gob-side entry retention structure. A mechanical model of the support structure for the gob-side entry retention was first established. Then, field observations and laboratory tests were used to obtain the force exerted by the coal wall on the main roof, the relationship between the axial bearing capacity and compression ratio of the rubble inside the gob, the supporting force exerted by the rubble and filling body, and the thrust of the rubble on the filling body. The shear stress experienced by the roadside filling body of the gob-side entry retention in working face No. 41101 was calculated to be 15.89 MPa. To meet the needs of roadside support, an innovative roadside backfill–truss support structure was adopted, with a 60° angle of inclination used for the anchor bolts of the gob-side entry retention structure. In this way, the ultimate shear strength was improved by 107.54% in comparison with the cement-based filling body.

  8. Shearer-mounted dust collection: evaluation of ventilated cutting drums. Open File Report (Final)

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, J.S.; Muldoon, T.L.


    Effective control of respirable dust is one of the most serious problems associated with longwall mining in the United States. This report describes the development and the underground evaluation of ventilated cutting drums, on a double ended ranging-drum shearer. The ventilated drum uses high pressure (1500 psi) water sprays to draw air (3500 cfm) through 12 airmoving tubes mounted in the drum hub. The sprays draw dusty air from the face side of the drum, scrub the air, and discharge the clean air on the gob side of the drum against a deflector plate. During a three-week underground evaluation, the cutting drums reduced shearer-generated dust levels at the shearer operators position by 40%, at the shield operators downwind of the shearer by 55%, and at the tailgate by 55%. Cutting and loading performance of the drums were superior to the mine's conventional drums. After the evaluation, the mine continued to use the ventilated drums to finish mining the panel.

  9. The forecast of mining-induced seismicity and the consequent risk of damage to the excavation in the area of seismic event

    Directory of Open Access Journals (Sweden)

    Jan Drzewiecki


    Full Text Available The Central Mining Institute has developed a method for forecasting the amount of seismic energy created by tremors induced by mining operations. The results of geophysical measurements of S wave velocity anomalies in a rock mass or the results of analytic calculations of the values of pressure on the horizon of the elastic layers are used in the process of calculating the energy. The calculation program which has been developed and adopted has been modified over recent years and it now enables not only the prediction of the energy of dynamic phenomena induced by mining but also the forecasting of the devastating range of seismic shock. The results obtained from this calculation, usually presented in a more readable graphic form, are useful for the macroscopic evaluation of locations that are potential sources of seismic energy. Forecasting of the maximum energy of seismic shock without prior knowledge of the location of the shock's source, does not allow shock attenuation that results from, for example, a distance of tremor source from the excavation which will be affected by seismic energy, to be taken into consideration. The phenomena of energy dissipation, which is taken into account in the forecasts, create a new quality of assessment of threat to the excavation. The paper presents the principle of a method of forecasting the seismic energy of a shock and the risk of damage to the excavation as a result of the impact of its energy wave. The solution assumes that the source of the energy shock is a resilient layer in which the sum of the gravitational stresses, resulting from natural disturbances and those induced by the conducted or planned mining exploitation, is estimated. The proposed solution assumes a spherical model for the tremor source, for which seismic energy is forecasted as a function of the longwall advance and the elementary value of seismic energy destroying the excavation. Subsequently, the following are calculated for the

  10. Coal-mining seismicity and ground-shaking hazard: A case study in the Trail Mountain area, Emery County, Utah (United States)

    Arabasz, W.J.; Nava, S.J.; McCarter, M.K.; Pankow, K.L.; Pechmann, J.C.; Ake, J.; McGarr, A.


    We describe a multipart study to quantify the potential ground-shaking hazard to Joes Valley Dam, a 58-m-high earthfill dam, posed by mining-induced seismicity (MIS) from future underground coal mining, which could approach as close as ???1 km to the dam. To characterize future MIS close to the dam, we studied MIS located ???3-7 km from the dam at the Trail Mountain coal mine. A 12-station local seismic network (11 stations above ground, one below, combining eight triaxial accelerometers and varied velocity sensors) was operated in the Trail Mountain area from late 2000 through mid-2001 for the dual purpose of (1) continuously monitoring and locating MIS associated with longwall mining at a depth of 0.5-0.6 km and (2) recording high-quality data to develop ground-motion prediction equations for the shallow MIS. (Ground-motion attenuation relationships and moment-tensor results are reported in companion articles.) Utilizing a data set of 1913 earthquakes (M ??? 2.2), we describe space-time-magnitude distributions of the observed MIS and source-mechanism information. The MIS was highly correlated with mining activity both in space and time. Most of the better-located events have depths constrained within ??0.6 km of mine level. For the preponderance (98%) of the 1913 located events, only dilatational P-wave first motions were observed, consistent with other evidence for implosive or collapse-type mechanisms associated with coal mining in this region. We assess a probable maximum magnitude of M 3.9 (84th percentile of a cumulative distribution) for potential MIS close to Joes Valley Dam based on both the worldwide and regional record of coal-mining-related MIS and the local geology and future mining scenarios.

  11. A Remote Sensing Approach to Environmental Monitoring in a Reclaimed Mine Area

    Directory of Open Access Journals (Sweden)

    Rajchandar Padmanaban


    Full Text Available Mining for resources extraction may lead to geological and associated environmental changes due to ground movements, collision with mining cavities, and deformation of aquifers. Geological changes may continue in a reclaimed mine area, and the deformed aquifers may entail a breakdown of substrates and an increase in ground water tables, which may cause surface area inundation. Consequently, a reclaimed mine area may experience surface area collapse, i.e., subsidence, and degradation of vegetation productivity. Thus, monitoring short-term landscape dynamics in a reclaimed mine area may provide important information on the long-term geological and environmental impacts of mining activities. We studied landscape dynamics in Kirchheller Heide, Germany, which experienced extensive soil movement due to longwall mining without stowing, using Landsat imageries between 2013 and 2016. A Random Forest image classification technique was applied to analyze land-use and landcover dynamics, and the growth of wetland areas was assessed using a Spectral Mixture Analysis (SMA. We also analyzed the changes in vegetation productivity using a Normalized Difference Vegetation Index (NDVI. We observed a 19.9% growth of wetland area within four years, with 87.2% growth in the coverage of two major waterbodies in the reclaimed mine area. NDVI values indicate that the productivity of 66.5% of vegetation of the Kirchheller Heide was degraded due to changes in ground water tables and surface flooding. Our results inform environmental management and mining reclamation authorities about the subsidence spots and priority mitigation areas from land surface and vegetation degradation in Kirchheller Heide.

  12. Gas Permeability Evolution Mechanism and Comprehensive Gas Drainage Technology for Thin Coal Seam Mining

    Directory of Open Access Journals (Sweden)

    Fangtian Wang


    Full Text Available A thin coal seam mined as a protective coal seam above a gas outburst coal seam plays a central role in decreasing the degree of stress placed on a protected seam, thus increasing gas permeability levels and desorption capacities to dramatically eliminate gas outburst risk for the protected seam. However, when multiple layers of coal seams are present, stress-relieved gas from adjacent coal seams can cause a gas explosion. Thus, the post-drainage of gas from fractured and de-stressed strata should be applied. Comprehensive studies of gas permeability evolution mechanisms and gas seepage rules of protected seams close to protective seams that occur during protective seam mining must be carried out. Based on the case of the LongWall (LW 23209 working face in the Hancheng coal mine, Shaanxi Province, this paper presents a seepage model developed through the FLAC3D software program (version 5.0, Itasca Consulting Group, Inc., Minneapolis, MI, USA from which gas flow characteristics can be reflected by changes in rock mass permeability. A method involving theoretical analysis and numerical simulation was used to analyze stress relief and gas permeability evolution mechanisms present during broken rock mass compaction in a goaf. This process occurs over a reasonable amount of extraction time and in appropriate locations for comprehensive gas extraction technologies. In using this comprehensive gas drainage technological tool, the safe and efficient co-extraction of thin coal seams and gas resources can be realized, thus creating a favorable environment for the safe mining of coal and gas outburst seams.

  13. A Model of Equilibrium Conditions of Roof Rock Mass Giving Consideration to the Yielding Capacity of Powered Supports (United States)

    Jaszczuk, Marek; Pawlikowski, Arkadiusz


    The work presents the model of interactions between the powered roof support units and the rock mass, while giving consideration to the yielding capacity of the supports - a value used for the analysis of equilibrium conditions of roof rock mass strata in geological and mining conditions of a given longwall. In the model, the roof rock mass is kept in equilibrium by: support units, the seam, goafs, and caving rocks (Fig. 1). In the assumed model of external load on the powered roof support units it is a new development - in relation to the model applied in selection of supports based on the allowable deflection of roof theory - that the load bearing capacity is dependent on the increment of the inclination of the roof rock mass and on the properties of the working medium, while giving consideration to the air pockets in the hydraulic systems, the load of the caving rocks on the caving shield, introducing the RA support value of the roof rock mass by the coal seam as a closed-form expression and while giving consideration to the additional support provided by the rocks of the goaf as a horizontal component R01H of the goaf reaction. To determine the roof maintenance conditions it is necessary to know the characteristics linking the yielding capacity of the support units with the heading convergence, which may be measured as the inclination angle of the roof rock mass. In worldwide mining, Ground Reaction Curves are used, which allow to determine the required yielding capacity of support units based on the relation between the load exerted on the unit and the convergence of the heading ensuring the equilibrium of the roof rock mass. (Figs. 4 and 8). The equilibrium of the roof rock mass in given conditions is determined at the displacement of the rock mass by the α angle, which impacts the following values: yielding capacity of units FN, vertical component of goaf reaction R01V and the horizontal component of goaf reaction R01H. In the model of load on the support


    Energy Technology Data Exchange (ETDEWEB)

    Jack C. Pashin; Richard E. Carroll; Richard H. Groshong, Jr.; Dorothy E. Raymond; Marcella McIntyre; J. Wayne Payton


    Sequestration of CO{sub 2} in coal has potential to reduce greenhouse gas emissions from coal-fired power plants while enhancing coalbed methane recovery. Data from more than 4,000 coalbed methane wells in the Black Warrior basin of Alabama provide an opportunity to quantify the carbon sequestration potential of coal and to develop a geologic screening model for the application of carbon sequestration technology. This report summarizes stratigraphy and sedimentation, structural geology, geothermics, hydrology, coal quality, gas capacity, and production characteristics of coal in the Black Warrior coalbed methane fairway and the implications of geology for carbon sequestration and enhanced coalbed methane recovery. Coal in the Black Warrior basin is distributed among several fluvial-deltaic coal zones in the Lower Pennsylvanian Pottsville Formation. Most coal zones contain one to three coal beds that are significant targets for coalbed methane production and carbon sequestration, and net coal thickness generally increases southeastward. Pottsville strata have effectively no matrix permeability to water, so virtually all flow is through natural fractures. Faults and folds influence the abundance and openness of fractures and, hence, the performance of coalbed methane wells. Water chemistry in the Pottsville Formation ranges from fresh to saline, and zones with TDS content lower than 10,000 mg/L can be classified as USDW. An aquifer exemption facilitating enhanced recovery in USDW can be obtained where TDS content is higher than 3,000 mg/L. Carbon dioxide becomes a supercritical fluid above a temperature of 88 F and a pressure of 1,074 psi. Reservoir temperature exceeds 88 F in much of the study area. Hydrostatic pressure gradients range from normal to extremely underpressured. A large area of underpressure is developed around closely spaced longwall coal mines, and areas of natural underpressure are distributed among the coalbed methane fields. The mobility and

  15. New Criteria to Assess Seismic and Rock Burst Hazard in Coal Mines / Nowe Kryteria Dla Oceny Zagrożenia Sejsmicznego I Tąpaniami W Kopalniach Węgla Kamiennego (United States)

    Mutke, Grzegorz; Dubiński, Józef; Lurka, Adam


    The paper presents new criteria of seismic and rock burst hazard assessment in Polish hard coal mines where longwall mining system is common practice. The presented criteria are based on the results of continuous recording of seismic events and analysis of selected seismological parameters: spatial location of seismic event in relation to mining workings, seismic energy, seismic energy release per unit coal face advance, b-value of Gutenberg-Richter law, seismic energy index EI, seismic moment M0, weighted value of peak particle velocity PPVW. These parameters are determined in a moving daily time windows or time windows with fixed number of seismic tremors. Time changes of these parameters are then compared with mean value estimated in the analyzed area. This is the basis to indicate the zones of high seismic and rock burst hazard in specific moment in time during mining process. Additionally, the zones of high seismic and rock burst hazard are determined by utilization of passive seismic tomography method. All the calculated seismic parameters in moving time windows are used to quantify seismic and rock burst hazard by four level scales. In practice, assessment of seismic and rock burst hazard is used to make daily decision about using rock burst prevention activities and correction of further exploitation of monitored coal panel. Zagrożenie sejsmiczne i związane z nim genetycznie zagrożenie tąpnięciem w dalszym ciągu należą do najgroźniejszych zagrożeń naturalnych występujących w polskich kopalniach węgla kamiennego. W ostatnich latach w kopalniach Górnośląskiego Zagłębia Węglowego (GZW) rocznie rejestrowano 1000÷1500 wstrząsów o energii sejsmicznej Es ≥ 1·105J (magnituda lokalna ML ≥ 1.7), a najsilniejsze z nich osiągały energię Es = 4 ·109J (ML = 4.1). W latach 1991-2010 odnotowano w GZW 101 tąpnięć, z których około 66% miało miejsce w wyrobiskach chodnikowych, powodując ich uszkodzenia lub całkowite zniszczenie, a w