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Theses and Dissertations--Mining Engineering

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Static And Dynamic Discrete Element Modelling Of Slender Coal Pillars, Michael J. Raffaldi Jan 2015

Static And Dynamic Discrete Element Modelling Of Slender Coal Pillars, Michael J. Raffaldi

Theses and Dissertations--Mining Engineering

Highwall mining is a mining method used in surface coal operations that involves driving a series of parallel entries into the exposed coal seam at the highwall face under an unsupported roof leaving behind a series of long, but very slender coal pillars. Highwall mining often occurs simultaneously with production blasting taking place in other areas of the mine. Although no failures of highwall pillars have been attributed to nearby blasting, numerical modelling presents an inexpensive means of investigating the possible effects of strong ground motion on the stability of these pillars. This thesis documents the development of a discrete ...


Analysis Of The Armps Database Using Flac3d; A Pillar Stability Comparison For Room And Pillar Coal Mines During Development, Ali Soltani Jan 2015

Analysis Of The Armps Database Using Flac3d; A Pillar Stability Comparison For Room And Pillar Coal Mines During Development, Ali Soltani

Theses and Dissertations--Mining Engineering

Designing a safe and economical mining activity is the main goal of every mine design engineer. With the rise of computer modeling in mine design there is a need for a standardized method to use geologic characterization of rocks in engineering design. In this research, first a review of empirical methods will be conducted and after that a step-by-step method is presented to adequately use FLAC3D, for development pillars, in room and pillar mine in development stage. ARMPS database is used to evaluate the FLAC3D model results. ARMPS database consists of 645 case study in room and pillar mines. 170 ...


Sustainable Disposal Of Coal Processing Waste Streams, Mohammad Rezaee Jan 2015

Sustainable Disposal Of Coal Processing Waste Streams, Mohammad Rezaee

Theses and Dissertations--Mining Engineering

Modern coal preparation facilities incorporate a wide array of solid-solid and solid-liquid separation processes for rejecting mineral matter to meet market specifications. The coarse mineral matter is typically placed into engineered refuse piles whereas the fine refuse is either stored in impoundments or co-disposed with the coarse refuse. The discharge water from the refuse material represents an environmental concern due to the potential release of trace elements, and the subsequent elevation of total dissolved solids and conductivity. The research findings reported in this dissertation addresses sustainable coal processing waste disposal through using strategies aimed at minimizing the environmental impacts. To ...


Ultra Clean Coal Production Using Dense Medium Separation For The Silicon Market, Seyed Hassan Amini Jan 2014

Ultra Clean Coal Production Using Dense Medium Separation For The Silicon Market, Seyed Hassan Amini

Theses and Dissertations--Mining Engineering

The production of high quality silicon requires the use of ultraclean coal containing less than 1.5% ash. The magnetite used to clean the coal in a dense medium process is a contaminant that seriously impacts the quality of the final silicon product. As such, research has been conducted to evaluate the potential to substitute the magnetite with fine silica–based alternative material generated during the silicon production process. Dense medium cyclone tests were performed based on a statistically designed program to determine the optimum conditions that maximize organic efficiency and minimize probable error and low–density bypass. The results ...


Active Current Injection Method For Limiting Ground Fault Current Harmonics In Underground Coal Mines, Yigong Zhang Jan 2014

Active Current Injection Method For Limiting Ground Fault Current Harmonics In Underground Coal Mines, Yigong Zhang

Theses and Dissertations--Mining Engineering

Current practice in U.S. underground coal mine high-voltage distribution systems is to attempt to limit ground fault current to 25 Amperes and de-energize the circuit at 10 Amperes. However, the significant amount of system capacitance due to the use of shielded cables can cause ground fault current to be two or three times the intended ground fault limit. Consequently, this practice can cause several issues such as ground fault currents significantly exceeding the neutral grounding resistor current limit, loss of relay selectivity in the distribution system, and transient overvoltages in certain ground fault situations. These issues are solved to ...


Multiscale Modeling Of The Mine Ventilation System And Flow Through The Gob, William Chad Wedding Jan 2014

Multiscale Modeling Of The Mine Ventilation System And Flow Through The Gob, William Chad Wedding

Theses and Dissertations--Mining Engineering

The following dissertation introduces the hazard of methane buildup in the gob zone, a caved region behind a retreating longwall face. This region serves as a reservoir for methane that can bleed into the mine workings. As this methane mixes with air delivered to the longwall panel, explosive concentrations of methane will be reached.

Computational fluid dynamics (CFD) is one of the many approaches to study the gob environment. Several studies in the past have researched this topic and a general approach has been developed that addresses much of the complexity of the problem. The topic of research herein presents ...


Development Of Industry Oriented Cfd Code For Analysis / Design Of Face Ventilation Systems, Todor P. Petrov Jan 2014

Development Of Industry Oriented Cfd Code For Analysis / Design Of Face Ventilation Systems, Todor P. Petrov

Theses and Dissertations--Mining Engineering

Two of the main safety and health issues recognized during deep cut coal mining are methane and dust hazards. Advances in continuous miner technology have improved safety and productivity. However, these advances have created some environmental problems, notably more dust and methane being generated at the face during coal extraction.

Results of studies performed in the last three decades concerning the face ventilation for deep cut mining showed very complicated airflow behavior. The specifics of flow patterns developed by the face ventilation systems presents significant challenge for analytical description even for equipment-free entry. Fortunately, there are methods, such as numerical ...


Status Of Communication And Tracking Technologies In Underground Coal Mines, Alexander D. Douglas Jan 2014

Status Of Communication And Tracking Technologies In Underground Coal Mines, Alexander D. Douglas

Theses and Dissertations--Mining Engineering

In 2006, Congress passed the MINER Act requiring mine operators to submit an emergency response plan that included post-accident communications and tracking systems to MSHA within three years of the Act. These systems were required to be designed for maximum survivability after a catastrophic event, such as a fire or explosion, and to be permissible (meets MSHA criteria for explosion-proof). At that time, no commercially available systems existed that met these standards. Several companies undertook developing new, or enhancing existing, technologies to meet these requirements. This research presents the results of a study that was conducted to determine the present ...


Fragmentation Analysis In The Dynamic Stress Wave Collision Regions In Bench Blasting, Catherine E. Johnson Jan 2014

Fragmentation Analysis In The Dynamic Stress Wave Collision Regions In Bench Blasting, Catherine E. Johnson

Theses and Dissertations--Mining Engineering

The first step in many mining operations is blasting, and the purpose of blasting is to fragment the rock mass in the most efficient way for that mine site and the material end use. Over time, new developments to any industry occur, and design and implementation of traditional techniques have to change as a consequence. Possibly the greatest improvement in blasting in recent years is that of electronic detonators. The improvements related to safety and increased fragmentation have been invaluable. There has been ongoing debate within the explosives industry regarding two possible theories for this. Shorter timing delays that allow ...


Evaluation Of Overpressure Wave Transition By Airblast Overpressure And Shock Wave Attenuation Analysis Using A Small Black Powder Charge, William R. Weitzel Jan 2014

Evaluation Of Overpressure Wave Transition By Airblast Overpressure And Shock Wave Attenuation Analysis Using A Small Black Powder Charge, William R. Weitzel

Theses and Dissertations--Mining Engineering

Eight flush mount pressure sensors were used in a series of 3 test sequences to measure air overpressure produced by a firecracker. Overpressure was recorded at a range of 1 inch to 21 inches away from detonation, and charge weight was determined to be 0.1mg of black powder. Air overpressure prediction equations were developed from test series then compared to collected data for subsequent tests. Overpressure wave velocity was measured using wave arrival time and distance between sensors. This wave velocity was compared to calculated wave velocity using overpressure and ideal gas law. Overpressure and wave velocity are directly ...


Experimental Comparison Study Of The Response Of Polycarbonate And Laminated Glass Blast Resistant Glazing Systems To Blast Loading, Joshua Calnan Jan 2013

Experimental Comparison Study Of The Response Of Polycarbonate And Laminated Glass Blast Resistant Glazing Systems To Blast Loading, Joshua Calnan

Theses and Dissertations--Mining Engineering

This thesis recounts the experimental study of the dynamic response of polycarbonate blast resistant glazing systems to explosive loading through the use of triaxial load cells, pressure sensors, and a laser displacement gauge. This instrumentation captured the response of the glazing systems to blast loading over three phases of testing. The first phase of testing characterizes the load distribution around the perimeter and the second phase examines the repeatability of the results. The final phase of testing pushes the samples to failure. The results are then compared to HazL, a commonly used blast resistant glazing system analysis software tool. The ...


A Framework For Understanding The Public's Perspectives Of Mining Applied To The Kentucky Coal Industry, Joshua M. Hoffman Jan 2013

A Framework For Understanding The Public's Perspectives Of Mining Applied To The Kentucky Coal Industry, Joshua M. Hoffman

Theses and Dissertations--Mining Engineering

People’s perceptions of mining are heavily based on the media they consume and the messages therein. News outlets ordinarily report on mining only when there is an accident or environmental concern. When messages that the public is exposed to are negative, it is no wonder that there are negative perceptions about mining.

Current public relations campaigns on the behalf of specific companies or select sectors do exist; however, this is often a reactionary move in response to recent shifts in the socio-political environment. The details of these campaigns are often tied up in proprietary information or withheld by public ...


Characterizing The Variability In Respirable Dust Exposure Using Johnson Transformation And Re-Examining 2010 Proposed Changes To The U.S. Underground Coal Mine Dust Standard, Al I. Khan Jan 2013

Characterizing The Variability In Respirable Dust Exposure Using Johnson Transformation And Re-Examining 2010 Proposed Changes To The U.S. Underground Coal Mine Dust Standard, Al I. Khan

Theses and Dissertations--Mining Engineering

Coal workers’ pneumoconiosis (CWP), commonly referred to as black lung, is a chronic lung disease that results from the inhalation and deposition of coal dust in the lungs. While this disease continues to afflict coal miners, its prevalence has steadily declined over three decades since 1970. Based on a voluntary X-ray surveillance program, conducted by the National Institute for Occupational Safety and Health (NIOSH), this downward trend, however, ended in 2000 and has actually begun to rise. The Mine Safety and Health Administration (MSHA) instituted a Comprehensive Initiative to “End Black Lung” to combat the reported upturn in black lung ...


Modeling Of An Air-Based Density Separator, Tathagata Ghosh Jan 2013

Modeling Of An Air-Based Density Separator, Tathagata Ghosh

Theses and Dissertations--Mining Engineering

There is a lack of fundamental studies by means of state of the art numerical and scale modeling techniques scrutinizing the theoretical and technical aspect of air table separators as well as means to comprehend and improve the efficiency of the process. The dissertation details the development of a workable empirical model, a numerical model and a scale model to demonstrate the use of a laboratory air table unit.

The modern air-based density separator achieves effective density-based separation for particle sizes greater than 6 mm. Parametric studies with the laboratory scale unit using low rank coal have demonstrated the applicability ...


Development Of 15 Psi Safe Haven Polycarbonate Walls For Use In Underground Coal Mines, Rex Allen Meyr Jr. Jan 2013

Development Of 15 Psi Safe Haven Polycarbonate Walls For Use In Underground Coal Mines, Rex Allen Meyr Jr.

Theses and Dissertations--Mining Engineering

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by MSHA and required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. The following research was performed in response to NIOSH’s call for the investigation into new refuge alternatives. A 15 psi safe haven polycarbonate wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics. The successful design was tested multiple times in both half-scale and small scale using a high explosive ...


Cavitation Nanobubble Enhanced Flotation Process For More Efficient Coal Recovery, Ahmed S. Sayed Ahmed Jan 2013

Cavitation Nanobubble Enhanced Flotation Process For More Efficient Coal Recovery, Ahmed S. Sayed Ahmed

Theses and Dissertations--Mining Engineering

Froth flotation is a widely used, cost effective particle separation process. However, its high performance is limited to a narrow particle size range, e.g., between 50 µm and 600 µm for coal and between 10 µm and 100 µm for minerals. Outside this range, the efficiency of froth flotation decreases significantly, especially for difficult-to-float particles of weak hydrophobicity (e.g., oxidized coal).

Nanobubbles integrated into a specially designed column flotation expanded the particle size range for efficient froth flotation as a result of increased probabilities of particle- bubble collision and attachment and reduced probability of detachment.

The major advantages ...


Froth Flotation Performance Enhancement By Feed Cavitation And Magnetic Plastic Particle Addition, Mehmet Saracoglu Jan 2013

Froth Flotation Performance Enhancement By Feed Cavitation And Magnetic Plastic Particle Addition, Mehmet Saracoglu

Theses and Dissertations--Mining Engineering

Froth flotation is the most commonly used process to recover and upgrade the portion of the coal preparation plant feed that has a particle size smaller than 150 microns. Problems that occur when employing froth flotation in the coal industry include i) coal surfaces that are weakly-to-moderately hydrophobic, and ii) flotation systems that are overloaded and limited by insufficient retention time.

Research was performed to evaluate techniques that could be implemented to improve flotation performance under the aforementioned scenarios. Pre-aeration of flotation feed using a cavitation system was extensively evaluated in laboratory and full-scale test programs. The benefits of adding ...


Enhanced Phosphate Flotation Using Novel Depressants, Lingyu Zhang Jan 2013

Enhanced Phosphate Flotation Using Novel Depressants, Lingyu Zhang

Theses and Dissertations--Mining Engineering

Froth flotation is the most efficient method for phosphate separation, which is a physic-chemical separation process based on the difference of surface properties between the valuable minerals and unwanted gangue minerals. However, the presence of clay slimes in the slurry after grinding consumes a large amount of reagents, decreases the collision probability between bubbles and minerals, prevents phosphate particle attachment to air bubbles, and thus considerably reduces flotation recovery and concentrate grade. Georgia Pacific Chemical, LLC has recently developed novel depressants, i.e., clay binders, which are a series of low molecular weight specialty polymers to help improve phosphate flotation ...


Collectors For Enabling Flotation Of Oxidized Coal, Raghav M. Dube Jan 2012

Collectors For Enabling Flotation Of Oxidized Coal, Raghav M. Dube

Theses and Dissertations--Mining Engineering

The coalburg seam coal is an example of difficult to float bituminous coal. Laboratory tests conducted on coalburg flotation feed sample revealed recovery values around 28% with 15% product ash when using fuel oil as collector under natural pH conditions. A detailed study showed that increasing pH from natural value of 5.6 to 7.5 provided a significant improvement in recovery of approximately 32 absolute percentage points. The improvement is believed to be result of the release of humic acids from the surface and the dispersion of clay particles thereby leaving a more hydrophobic surface.

Based on the tests ...


Development Of Strategies To Minimize The Release Of Trace Elements From Coal Waste Sources, Mohammad Rezaee Jan 2012

Development Of Strategies To Minimize The Release Of Trace Elements From Coal Waste Sources, Mohammad Rezaee

Theses and Dissertations--Mining Engineering

To assess strategies aimed at minimizing the release of trace elements and the impact of disposal of coal waste materials on the environment, two long-term leaching experiments of up to five months duration were performed using waste materials from two plants cleaning high and low sulfur bituminous coal. The tests evaluated the mobility of major trace elements under different disposal scenarios: (i) a static leaching test designed to simulate the quiescent conditions encountered by coal waste material stored under water in a stable impoundment, and (ii) a dynamic test to simulate waste materials exposed to the atmosphere, either in variable ...