VTechWorks Repository :: Browsing by Author "Karmis, Michael E."

Browsing by Author "Karmis, Michael E."

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Analysis and optimization of coalbed methane gas well production
Holman, Travis Scott (Virginia Tech, 1996-07-15)
Coalbed methane wells have been used for many years as a viable means of extracting quantities of methane gas for use as a clean and efficient energy source. However, there is a limited understanding of many of the factors involved during the extraction process. As the more easily attainable reservoirs are depleted, it is imperative to gain a greater comprehension of these factors in order to develop techniques to efficiently collect economical quantities of methane gas in the future. For this investigation, an extensive database was compiled, consisting of a large set of parameters pertaining to the development of coalbed methane gas wells. Using the information contained in this database, a statistical analysis was performed in order to gain a better understanding of the relationships between the many factors involved in extracting quantities of methane gas from the ground. The results of this analysis showed that the majority of the parameters shown to have the greatest impact on methane production were heavily dependent upon the geology of the region. As a result, any attempt to exploit them for optimization exercises would be extremely difficult. Of the parameters shown to have the least dependence on naturally occurring phenomena, the amount of proppant sand used to hold fractures open within the well system after stimulation was shown to have the most impact During the well stimulation procedure, the proppant sand is carried into the fractures in the strata by a foam fracturing fluid. The sand acts to support the fracture system, increasing the permeability of formation, and allowing the methane gas to flow to the wellbore. By treating the sand particles with certain reagents, it is possible to render them hydrophobic, making it possible for them to stick to the bubbles within the foam and be carried deeper into the formation. Results of an investigation of sands treated to different degrees of hydrophobicity have shown that such treatments significantly increase the amount of sand distributed over a greater distance.
Analysis of Seismic Signatures Generated from Controlled Methane and Coal Dust Explosions in an Underground Mine
Murphy, Michael M. (Virginia Tech, 2008-11-07)
Examination of seismic records during the time interval of the Sago Mine disaster in 2006 revealed a small amplitude signal possibly associated with an event in the mine. Although the epicenter of the signature was located in the vicinity where the explosion occurred, it could not be unequivocally attributed to the explosion. More needs to be understood about the seismicity from mine explosions in order to properly interpret critical seismic information. A seismic monitoring system located at NIOSH's Lake Lynn Experimental Mine has monitored nineteen experimental methane and dust based explosions. The objective of the study was to analyze seismic signatures generated by the methane and dust explosions to begin understanding their characteristics at different distances away from the source. The seismic signatures from these different events were analyzed using standard waveform analysis procedures in order to estimate the moment magnitude and radiated seismic energy. The procedures used to analyze the data were conducted using self-produced programs not available with existing commercial software. The signatures of the explosions were found to be extremely complex due a combination of mine geometry and experimental design, both of which could not be controlled for the purposes of the study. Geophones located approximately 600 m (1970 ft) and over from the source collected limited data because of the attenuation of the seismic waves generated by the methane explosion. A combination of the methods used to characterize the seismic signatures allowed for differentiation between experimental designs and the size of the explosion. The factors having the largest impact on the signatures were the mine geometry, size of the methane explosion, construction of the mine seal and location of the mine seal. A relationship was derived to correlate the radiated seismic energy to the size of the explosion. Recommendations were made, based upon the limitations of this study, on methods for better collection of seismic data in the future.
Application of water mist to fuel-rich fires in model coal mine entries
Loomis, Ian Morton (Virginia Tech, 1995-03-05)
As the nature of coal mInmg changes, to higher production associated with higher mechanization, the way in which mine safety is approached must also change. This situation was clearly shown in a very devastating coal mine fire in late 1984. In the absence of effective fire-fighting procedures and equipment the affected mine was quickly rendered helpless. Of particular concern with coal mine fires is the possibility of entering a fuel-rich state. In this state current practices have proven to be of little use in gaining control over the conflagration. Recent experiences with the application of water mist to industrial fires has shown that use of fog can be an efficacious agent in controlling large scale fires. The postulations of this phenomenon concern the ability of the water, as a fog, to get deeply within the fire structure. In this manner it works to remove the three legs of the fire triangle~ heat, oxygen, and fuel. The research contained in this thesis dwells in three associated areas. These are: the general theory of water mist application relative to current practices~ the design and construction of a fire tunnel for experimental work; and the results obtained from experiments with fuel-rich fires in the simulated coal mine entry. The results of this research are most encouraging, not only for the more devastating fuelrich fires, but also for application from the onset of fire fighting activities in the coal mine environment.
Applications and Development of Intelligent UAVs for the Resource Industries
Bishop, Richard Edwin (Virginia Tech, 2022-04-21)
Drones have become an integral part of the digital transformation currently sweeping the mining industry; particularly in surface operations, where they allow operators to model the terrain quickly and effortlessly with GPS localization and advanced mission planning software. Recently, the usage of drones has expanded to underground mines, with advancements in drone autonomy in GPS-denied environments. Developments in lidar technology and Simultaneous Localization and Mapping (SLAM) algorithms are enabling UAVs to function safely underground where they can be used to map workings and digitally reconstruct them into 3D point clouds for a wide variety of applications. Underground mines can be expansive with inaccessible and dangerous areas preventing safe access for traditional inspections, mapping and monitoring. In addition, abandoned mines and historic mines being reopened may lack reliable maps of sufficient detail. The underground mine environment presents a multitude of unique challenges that must be addressed for reliable drone flights. This work covers the development of drones for GPS-denied underground mines, in addition to several case studies where drone-based lidar and photogrammetry were used to capture 3D point clouds of underground mines, and the associated applications of mine digitization, such as geotechnical analysis and pillar strength analysis. This research also features an applied use case of custom drones built to detect methane leaks at natural gas production and distribution sites.
Applications of Close-Range Terrestrial 3D Photogrammetry to Improve Safety in Underground Stone Mines
Bishop, Richard (Virginia Tech, 2020-05-22)
The underground limestone mining industry is a small, but growing segment of the U.S. crushed stone industry. However, its fatality rate has been amongst the highest of the mining sector in recent years due to ground control issues related to ground collapses. It is therefore important to improve the engineering design, monitoring and visualization of ground control by utilizing new technologies that can help an underground limestone company maintain a safe and productive operation. Photogrammetry and laser scanning are remote sensing technologies that are useful tools for collecting three-dimensional spatial data with high levels of precision for many types of mining applications. Due to the reality of budget constraints for many underground stone mining operations, this research concentrates on photogrammetry as a more accessible technology for the average operation. Despite the challenging lighting conditions and size of underground limestone mines that has previous hindered photogrammetric surveys in these environments, over 13,000 photographic images were taken over a 3-year period in active mines to compile these models. This research summarizes that work and highlights the many applications of terrestrial close-range photogrammetry, including practical methodologies for implementing the techniques in working operations to better visualize hazards and pragmatic approaches for geotechnical analysis, improved engineering design and monitoring.
ARIES Executive Summary
Jong, Edmund C.; Boardman, Gregory D.; Karmis, Michael E. (Virginia Tech. Virginia Center for Coal and Energy Research, 2019-07-30)
The following document contains an executive summary of key findings from the Appalachian Research Initiative for Environmental Science (ARIES). Further details for these findings may be found in the referenced peer-reviewed publications and project reports. The ARIES body of work was developed from 2011 to 2016. Thus, published ARIES results will not reflect any evolutions in policy and research that occurred after this timeframe. Although some issues may be different today, the breakthrough research conducted by the ARIES community continues to provide invaluable insights into these areas of interest.
ARIES Research Summary
Jong, Edmund C.; Boardman, Gregory D.; Karmis, Michael E. (Virginia Tech. Virginia Center for Coal and Energy Research, 2019-01-03)
In the mid-2000s, concerns were raised about the impact of Appalachian coal mining and especially mountaintop mining. These concerns were prompted by various research studies that alleged a direct link between coal mining and various negatively trending aspects of community health. Some studies related coal mining to higher rates of cancer and infant mortality. Other investigations claimed that coal mining perpetuated poverty and harms community character. These alarming reports prompted a significant public outcry that resulted in litigation and regulatory attention toward the coal industry. In response, a number of meetings and strategic sessions were held in 2009 and 2010 to address these concerns. Major Appalachian coal producers, coal associations, and essential coal infrastructure companies participated in these conferences. After rigorous debate, the participants decided to form an independent research program designed to address community concerns through objective, focused research. This program was designated the Appalachian Research Initiative for Environmental Science (ARIES). ARIES would be a research consortium designed to elicit the participation of major research universities across the U.S. The primary objective of this research collaboration would be to investigate the impacts of coal mining and energy production on Appalachian communities. To support this goal, ARIES adopted a research paradigm that delivered objective, robust, and transparent results though the support of industry. This paradigm was composed of four core principles: 1. Independent research conducted at universities 2. Wide dissemination of results through peer-reviewed publications 3. Realistic timeframes for research and reporting 4. Applying sound scientific principles
Assessment of the Risks Associated with Thin Film Solar Panel Technology
Reynolds, William T. Jr.; Karmis, Michael E. (Virginia Tech. Virginia Center for Coal and Energy Research., 2019-03-08)
This report reviews the environmental risk profile of utility-scale cadmium telluride (CdTe) photovoltaic installations with relevant information from the scientific literature and an audit of the manufacturing and recycling facilities of a domestic manufacturer. Current photovoltaic technologies are described, and the environmental and health issues associated with CdTe are identified. Solubility measurements, bioavailability, acute aquatic toxicity, oral and inhalation toxicity, and mutagenicity studies all confirm CdTe has different physical, chemical, and toxicological properties than Cd. The CdTe compound is less leachable and less toxic than elemental Cd. The risks to the environment arising from broken solar panels during adverse events are considered by reviewing experimental results, theoretical worstcase modeling, and observational data from historical events. In each case considered, the potential negative health and safety impacts of utility-scale photovoltaic installations are low. The need for end-of-life management of solar panels is highlighted in the context of recycling to recover valuable and environmentally sensitive materials. Based upon the potential environmental health and safety impacts of CdTe photovoltaic installations across their life cycle, it is concluded they pose little to no risk under normal operating conditions and foreseeable accidents such as fire, breakage, and extreme weather events like tornadoes and hurricanes.
Bump control design protocol for room-and-pillar retreat mining
Campoli, Alan A. (Virginia Tech, 1994-05-08)
A stress control design protocol was developed to minimize coal mine bumps, which are the explosive failure of highly stressed pillars. The protocol was developed for room-and-pillar retreat mining conducted with available continuous miner technology. The inability of existing coal pillar equations to accurately represent the wide total extraction pillars required, forced the development of the pseudoductile coal pillar strength model. A confined pillar core is assumed to reach a maximum stress when surrounded by a yielded perimeter. The width of the yielded perimeter is assumed to increase linearly with increased coalbed thickness. The pseudoductile model was employed in the development of supercritical and subcritical width section design criteria. The supercritical design procedure assumes an infinitely long pillar line, composed of uniformly sized pillars, extracted against an infinitely wide gob area. Tributary area theory was combined with a linear shear angle concept to estimate the loads applied to total extraction pillars adjacent to gob areas. The boundary element code MULSIM/NL was utilized in the development and implementation of a systematic subcritical design procedure to apply the stress shield concept to retreat room-and-pillar coal mining, under bump hazard. The complex distribution of gob side abutment load between the side abutment pillars and the chain pillars in the total extraction zone made computer simulation a necessity. Section layouts were determined for the mining of a 6 ft thick coalbed under overburden up to 2,200 ft thick. The sections consist of total extraction areas separated by continuous abutment pillars. A spreadsheet program LAYOUT was created to summarize and provide for efficient utilization of the bump control design protocol. Based on overburden thickness, coalbed thickness, abutment load linear shear angle, and pillar dimensions entered by the user, LAYOUT calculates a stability factor for the first and second pillar row outbye the expanding gob for supercritical width sections. If the overburden and coalbed thickness conditions do not allow a supercritical section design, LAYOUT develops a subcritical design.
Carbon Dioxide Storage in Coal Seams with Enhanced Coalbed Methane Recovery: Geologic Evaluation, Capacity Assessment and Field Validation of the Central Appalachian Basin
Ripepi, Nino Samuel (Virginia Tech, 2009-08-03)
The mitigation of greenhouse gas emissions and enhanced recovery of coalbed methane are benefits to sequestering carbon dioxide in coal seams. This is possible because of the affinity of coal to preferentially adsorb carbon dioxide over methane. Coalbed methane is the most significant natural gas reserve in central Appalachia and currently is economically produced in many fields in the Basin. This thesis documents research that assesses the capacity of coal seams in the Central Appalachian Basin to store carbon dioxide and verifies the assessment through a field validation test. This research allowed for the first detailed assessment of the capacity for coal seams in the Central Appalachian Basin to store carbon dioxide and enhance coalbed methane recovery. This assessment indicates that more than 1.3 billion tons of carbon dioxide can be sequestered, while increasing coalbed methane reserves by as much as 2.5 trillion cubic feet. As many of the coalbed methane fields are approaching maturity, carbon sequestration and enhanced coalbed methane recovery has the potential to add significant recoverable reserves and extend the life of these fields. As part of this research, one thousand tons of carbon dioxide was successfully injected into a coalbed methane well in Russell County, Virginia as the first carbon dioxide injection test in the Appalachian coalfields. Research from the field validation test identified important injection parameters and vital monitoring technologies that will be applicable to commercial-scale deployment. Results from the injection test and subsequently returning the well to production, confirm that fractured coal seams have the potential to sequester carbon dioxide and increase methane production. It was demonstrated through the use of perfluorocarbon tracers that there is a connection through the coal matrix between the injection well and surrounding producing gas wells. This connection is a cause for concern because it is a path for the carbon dioxide to migrate to the producing wells. The thesis concludes by presenting options for mitigating carbon dioxide breakthrough in commercial-scale injection projects.
A Characterization and Determination of the Coal Reserves and Resources of Southwest Virginia
Westman, Erik C. (Virginia Tech, 1999-04-14)
Coal mining and timber are the two primary industries supporting the people of Southwest Virginia. Coal mining has occurred for more than 100 years, but production has dropped since reaching a peak in 1990. In order to properly plan with remaining coal production a study was conducted to characterize and estimate coal resources. Seam thickness was found to be the parameter which most influenced resource levels. An economic model was developed to determine which portion of the reserves could economically be extracted. It was found that 3.95 billion tons, or 14% of the remaining resource, is economic under current mining conditions. More than 60% of these reserves, however, are in deep seams which require shafts to be constructed prior to initiation of mining.
Characterization and scale-up of microbubble generation in column flotation
Davis, Van Leslie (Virginia Tech, 1990-04-05)
Recent hydrodynamic studies suggest that small air bubbles can be used to improve the performance of column flotation. Tests carried out at Virginia Tech during the past several years have shown that various types of inline motionless (or static) mixers can successfully produce microbubbles for column flotation. Unfortunately, few guidelines exist for selecting the proper size and type of motionless mixer for generating microbubbles. In the present work, the mean bubble size produced by various types of in-line motionless mixers has been experimentally determined over a wide range of operating conditions and generator geometries. Test results indicate that generator performance is described by a series of expressions derived from a dimensional analysis. These expressions demonstrate that bubble diameter is primarily determined by the generator geometry and a dimensionless term known as the Weber number. Tests have also been conducted to determine the reduction in the performance of centrifugal pumps under air admitting conditions. A semi-empirical pump model has been utilized which allows the proper size of pump to be selected for microbubble generation. This information should prove useful for the design and operation of microbubble generation circuits on an industrial scale.
Coal Mining Outlook: International, National, and Virginia Trends
Karmis, Michael E.; McDowney, Preston; Ripepi, Nino; Schafrik, Steven J.; Weisiger, Sean; Walton, Daniel; Kostic, Dennis (Virginia Tech. Virginia Center for Coal and Energy Research., 2000-11)
Coal mining serves an important role as the economic catalyst for Southwest Virginia, providing high paying jobs in an area crippled by unemployment. There are numerous support industries in existence only because of coal mining. The ripple effects of mining are experienced throughout the state. Every ton of coal mined in Virginia contributes $27.11 to Virginia's economy, while every dollar paid to a miner has a $4.64 impact on Virginia's economy. The tax credit has had a pronounced effect on coal production in Virginia. After the tax credit was enacted, the declining trend in coal production has slowed down, and the production levels are higher than projected. As a result of these higher production levels, an additional $394 million in total impact has been generated, millions in severance and income taxes have been produced, and numerous coal mining jobs have been preserved.
Computer aided blast fragmentation prediction
Exadaktylos, George E. (Virginia Tech, 1988-11-15)
The complex and non-linear nature of blast fracturing have restricted common blast design mostly to empirical approaches. The code developed for this investigation avoids both empiricism and large memory requirement in order to simulate the pattern of interacting radial fractures from an array of shotholes, at various burdens and spacings, and in simultaneous and delayed modes. The resultant pattern is analyzed and a fragment size distribution calculated. The rules governing the distribution of radial cracks and the way in which they interact are based on model scale experiments conducted by various investigators. Calculated fragment size- distribution agree with data from the field. Powder factor dependence of fragmentation results is also well described by the model. The effect of discontinuities on rock fragmentation by blasting is also incorporated into the model. Discontinuities which are open and filled with air or soil-like material affect destructively the transmission of strain waves and propagation of cracks in the rock mass. These discontinuities can be incorporated into the simulation by inserting cracks to represent them. The cracks representing discontinuities will then terminate the cracks produced by blasting where they intersect. On the other hand, tight joints without filling material or with filling material but with a high bond strength and acoustic impedance close to that of the medium do not affect in a negative way the transmission of shock waves in the rock mass. A mathematical model was developed to treat these discontinuities which was based on principles from Linear Elastic Fracture Mechanics theory and Kuznetsov's equation which relates the mean fragment size obtained to the blast energy, hole size and rock characteristics.
Control of Surface Chemistry of Gold, Pyrite and Pyrrhotite
Chen, Xianguo (Virginia Tech, 1997-08-23)
Removing pyrite from coal and pyrrhotite from pentlandite play a critical role in coal and nickel production, respectively, to meet the stringent restriction on SO2 emission. The present project investigates first the mechanism of xanthate adsorption on gold using Atomic Force Microscope (AFM), then the depression of pyrite and pyrrhotite using the synthetic polymers developed by Cytec Industries. The results show that for xanthate/gold system, dixanthogen is the only species that renders the surface hydrophobic. Chemisorbed xanthate is observed on the gold surface but is hydrophilic. The synthetic polymers may adsorb on pyrite and pyrrhotite possibly through the hydrophobic interaction between the hydrophobic moiety of the polymer and the mineral surface that has been hydrophobized by collector adsorption. The hydrophilic moieties of the polymer are exposed to the aqueous phase and render the surface hydrophilic.
A Data-Driven Approach for the Development of a Decision Making Framework for Geological CO2 Sequestration in Unmineable Coal Seams
Miskovic, Ilija (Virginia Tech, 2011-12-14)
In today's energy constrained world, carbon capture and sequestration can play an essential role in mitigating greenhouse gas emissions, while simultaneously maintaining a robust and affordable energy supply. This technology is an end-of-pipe solution that does not contribute to a decrease of the production of greenhouse gases, but is very useful as a transition solution on the way towards other sustainable energy production mechanisms. This research involves the development of a comprehensive decision making framework for assessing the techno-economic feasibility of CO2 sequestration in unmineable coal seams, with the Central Appalachian Basin chosen for analysis due to the availability of empirical data generated through recent characterization and field validation studies. The studies were conducted in order to assess the sequestration capacity of coal seams in the Central Appalachian Basin and their potential for enhanced coal bed methane recovery. The first stage of this research involves assessment of three major sequestration performance parameters: capacity, injectivity, and containment. The assessment is focused on different attributes and reservoir properties, characteristic of deep unmineable coal seams in the Central Appalachian Basin. Quantitative and qualitative conclusions obtained through this review process are used later in the identification of the minimum set of technical information necessary for effective design and development of CO2 storage operations. The second section of this dissertation analyzes economic aspects of CO2 sequestration. This segment of the research uses a real options analysis to evaluate the impact of major sources of uncertainty on the total cost of developing and operating a CCS project in a regulatory environment that expects implementation of carbon taxes, but with uncertainty about the timing of this penalty. Finally, all quantitative and qualitative information generated in the first two stages of this research were used for development of a decision making framework/matrix that summarizes the interactions between major technical and economic parameters and constraints, on the other hand, and their impact on overall feasibility of CO2 sequestration in unmineable coal seams. This framework will provide user with capability to address complex problems in a more systematic way and to analyze the most efficient way to utilize available resources.
Design Criteria for Wireless Mesh Communications in Underground Coal Mines
Griffin, Kenneth R. (Virginia Tech, 2009-05-01)
The Mine Improvement and New Emergency Response (MINER) Act of 2006 was enacted in response to several coal mining accidents that occurred in the beginning of 2006. The MINER Act does not just require underground mines to integrate wireless communication and tracking systems, but aims to overall enhance health and safety in mining at both surface and underground operations. In 2006, the underground communication technologies available to the mining industry had inherent problems that limited communication capabilities. Since the passage of the MINER Act, there have been several developing applications for underground wireless communications. Underground wireless communications allow signals to propagate and take multiple paths to destinations providing a survivable, redundant, and adaptable means of communication and tracking. An underground wireless communications allow underground and surface personnel to directly correspond to one another without being as restricted as hardwired systems. Communication systems also allow miners to be tracked underground to provide a real-time or last known post-accident position, and ensure a more efficient rescue operation. In order to increase the overall efficiency of developing communication systems there is a need for modeling of wireless signal propagation in underground mines. Research, modeling, and analysis of wireless signal propagation in underground mines ongoing and developing with underground communications systems as the systems progress. The work on this project is based upon the Accolade system from L-3 Communications Global Security and Engineering Solutions but applies to all underground wireless mesh systems currently available. A general approach is taken to solving underground wireless communications networks to allow the design criteria to be adaptable to other communication systems belong the Accolade system. The data is based upon measurements and field work that took place July 2007 through December 2008 in International Coal Group's Sentinel Mine in Philippi, West Virginia. Comms, a computer method developed at the Virginia Center for Coal and Energy Research at Virginia Tech, allows underground mine communication networks to be solved and analyzed. Comms was developed to solve and analyze underground wireless communication networks. The method which Comms solves communication networks is not mine specific and may be adapted to predict the performance of a system(s) in another mine. The developed model discussed in Chapters 3 and 4 highlights the general signal loss parameters that are encountered by wireless signals in a mine. The model predicted the signal strength observed when encountering those categorized signal losses within 16 percent of the data measured during a mine survey. The model has been developed in a general manner to allow future investigation and pinpointing of additional interferences that occur within the underground environment. Wireless communications have proven to be the way of the future and will continue to be integrated into underground coal mines as mandated by the MINER Act. Wireless communications systems are a redundant and survivable means of communication that will be utilized in not only emergency and rescue efforts but daily operational communication as well.
Determining the size and life of underground coal mines
Li, Zhongxue (Virginia Tech, 1987-05-15)
The determination of mine design variables such as mine shaft locations, mine field dimensions, mine design capacity, and mine service life under various mining conditions is of primary importance to the economics of developing and subsequently operating an underground coal mine. However, the problem has received little academic attention in the United States. Solutions to the problem tend to be subjective and based upon personal experience and managerial judgment rather than objective and based upon some quantitative criteria. The purpose of this research was to conduct a quantitative study on the problem of evaluating these mine design variables and to develop a mathematical modeling approach that permits a quantitative determination of the design variables and facilitates the analysis of effects of input parameters such as seam an gle, seam thickness, seam depth, underground traveling speed of men, mine recovery, plant recovery, average productivity~ and interest rate on the size of underground coal mine operations and the unit cost of coal. In formulating the problem, relationships among mining costs, main shafts location, section production per shift, number of production sections in mines, mine output, and mine field dimensions were analyzed. Thereby, the unit cost of coal was expressed as a function of mine field dimensions, mine design ca pacity, and mine service life. The problem was then formulated as a nonlinear optimization model in terms of minimizing the unit cost of coal subject to certain constraints, and solved analytically for flat seams and numerically for inclined seams. Possible extensions of the formulation were also discussed. The methodology developed in the research was intended to be an important step toward the increased application of quantitative methods in designing underground coal mines. The results obtained from the study are expected to serve as useful aids in establishing logical mining units (LMU) or dividing a deposit into blocks for development, locating mine shafts within a mine field, planning annual mine production rates, and projecting the lifetime of an underground coal mine.
Development and Evaluation of a Permeation Plug Release Vessel (PPRV) for the Release of Perfluoromethylcyclohexane (PMCH) in Underground Mine Tracer Gas Studies
Jong, Edmund Chime (Virginia Tech, 2014-01-20)
The use of sulfur hexafluoride (SF6) as a tracer gas for analyzing underground mine ventilation systems has been practiced for over 30 years. As a result, the methods used to release, sample, and analyze SF6 are well accepted. Although improvements are still being made to enhance the analysis of this tracer, the overall technique remains largely the same. However, as the complexity and size of underground mine ventilation networks increase, coupled with steadily rising SF6 background levels, the ability of a single gas to function as a convenient, rapid means of analysis diminishes. The utilization of multiple tracer gases can mitigate these problems by allowing for a more comprehensive evaluation using multi-zone techniques. A well-documented alternative in HVAC studies to SF6 as a tracer are perfluorocarbon tracers (PFT). Many PFTs exist as volatile liquids at room temperature and pressure. This characteristic prevents a PFT from being released using the same technique as SF6. This paper introduces a passive release method for PMCH. Details about the development of the permeation plug release vessel (PPRV) from creating a GC calibration curve for vapor PMCH to the final field evaluation are presented. The following study successfully developed a mine-scale PPRV. The PPRV is designed to passively deploy PMCH vapor at linear. An equation was derived in this study that allows the prediction of the release rate as a function of temperature and plug thickness. Details regarding the development of the PPRV from preliminary laboratory studies to final field evaluations are provided.
Development of a remote analysis method for underground ventilation systems using tracer gas and CFD
Xu, Guang (Virginia Tech, 2013-04-04)
Following an unexpected event in an underground mine, it is important to know the state of the mine immediately to manage the situation effectively. Particularly when part or the whole mine is inaccessible, remotely and quickly ascertaining the ventilation status is one of the pieces of essential information that can help mine personnel and rescue teams make decisions. This study developed a methodology that uses tracer gas techniques and CFD modeling to analyze underground mine ventilation system status remotely. After an unanticipated event that has damaged ventilation controls, the first step of the methodology is to assess and estimate the level of the damage and the possible ventilation changes based on the available information. Then CFD models will be built to model the normal ventilation status before the event, as well as possible ventilation damage scenarios. At the same time, tracer gas tests will be designed and performed on-site. Tracer gas will be released at a designated location with constant or transient release techniques. Gas samples will be collected at other locations and analyzed using Gas Chromatography (GC). Finally, through comparing the CFD simulated results and the tracer on-site test results, the general characterization of the ventilation system can be determined. A review of CFD applications in mining engineering is provided in the beginning of this dissertation. The basic principles of CFD are reviewed and six turbulence models commonly used are discussed with some examples of their application and guidelines on choosing an appropriate turbulence model. General modeling procedures are also provided with particular emphasis on conducting a mesh independence study and different validation methods, further improving the accuracy of a model. CFD applications in mining engineering research and design areas are reviewed, which illustrate the success of CFD and highlight challenging issues. Experiments were conducted both in the laboratory and on-site. These experiments showed that the developed methodology is feasible for characterizing underground ventilation systems remotely. Limitations of the study are also addressed. For example, the CFD model requires detailed ventilation survey data for an accurate CFD modeling and takes much longer time compared to network modeling. Some common problems encountered when using tracer gases in underground mines are discussed based on previously completed laboratory and field experiments, which include tracer release methods, sampling and analysis techniques. Additionally, the use of CFD to optimize the design of tracer gas experiments is also presented. Finally, guidelines and recommendations are provided on the use of tracer gases in the characterization of underground mine ventilation networks.

Browsing by Author "Karmis, Michael E."

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