Search Documents

By V. L. Ketellapper

This paper discusses the technical issues and stakeholder collaborative processes which resulted in achieving a balance between the reclamation of abandoned mine sites, providing affordable housing, and preservation of open space at the French Gulch Site. Through this process, it was discovered that mine site reclamation would need to be conducted in conjunction with two priorities for community sustainable development: providing affordable housing for locals who work in the resort town of Breckenridge, and open space preservation. It was found that conducting these activities concurrently would result in providing resources necessary to complete mine site reclamation. The first phase of the affordable housing development is almost completed. This development resulted in redevelopment of mining impacted lands and was recognized by the U.S. Environmental Protection Agency (EPA) with a National Smart Growth Award in 2002.Negotiations are also underway to preserve the remaining 1,800 acres of land held by the mining company as open space. This transaction will in turn provide resources to address water quality issues associated with mine discharges.

Jan 1, 2004

"Australia’s largest rail freight network operator, the Australian Rail Track Corporation (ARTC), has selected GE Transportation’s Movement Planner solution as the key technology enabler for its Hunter Valley-focused network control optimization program.ARTC’s Newcastle-based network control, is the nerve center of Hunter Valley rail operations, where locally based train control professionals make thousands of decisions every day to safely support the annual movement of more than 24 kt/h (26,400 stph) of freight, and tens of thousands of coal, freight, grain and passenger trains each year.ARTC plans to transform its train control function by integrating and then building on Movement Planner, an advanced software solution by GE Transportation that provides real-time rail traffic planning and optimization to enable freight to move more efficiently. “The Hunter Valley rail network is one of the busiest and most complex in the country, supporting the largest coal export port in the world,” ARTC managing director and chief executive officer John Fullerton said.“As bulk freight demands grow, rail operators like ARTC and supply chains like the Hunter Valley coal network need to be creative in the way they respond so the Australian economy doesn’t miss out. That’s why we have conducted a worldwide search to find globally proven solutions that will improve our network productivity and efficiency,” Fullerton said.The Movement Planner solution considers multiple factors including train schedules, trafficcontrol systems and train movements relative to each other and then develops an optimized traffic plan for the trains throughout the network. Existing GE customers have benefited from increased visibility of network operations, higher velocity, less dwell times, and improved on-time performance across their networks."

Jan 1, 2018

By D. J. Kennedy, A. W. Stokes, W. G. Klinowski

Sulphur hexafluoride (SF6) has become an accepted standard in the field of mine ventilation tracer gas studies. It has a wide variety of uses for defining mine ventilation flows that cannot be adequately described using conventional instruments such as anemometers and smoke tubes. The Cape Breton Coal Research Laboratory (CBCRL), Energy, Mines and Resources Canada, has been using SF for the past 4 years and has developed numerous release and sampling systems to increase its versatility. The CBCRL has also completed a successful field trial of an automated rapid sequential SF6 analyzer (which gives a pseudo real-time readout) that can be used underground. In doing this work, the authors recognised the potential of being able to use more than one tracer gas simultaneously in an underground study. Two alternative tracer gases (Freon-13B1 and Freon-12) have already been used by CBCRL in some of their underground work. These gases can be measured by gas chromatography utilising an electron capture detector in a similar manner to SF6. A description of these gases, the methods for 6' their handling, release and sampling are given in this paper together with a brief outline of the analytical system used to measure them. Their suitability to mining applications is compared with SF6. A study in which these three gases were used together is discussed and the results and conclusions given. Some of the additional uses for multiple tracer gases to assist the mine ventilation engineer in resolving problems and improving his day-to-day monitoring are discussed. Finally, a brief analysis of developments which can be expected in the near future is outlined.

Jan 1, 1987

By Richard P. Killmeyer, Carl P. Maronde, W. W. Wen, Peter J. Suardini

Under a cost-shared Department of Energy contract, awarded as part of the Coal Preparation Program&apos;s High Efficiency Preparation subprogram, Custom Coals International will be installing and testing a 227 kglhr micronized-magnetite cycloning circuit in PETC&apos;s Coal Preparation Process Research Facility. The project includes the design, construction, testing, and decommissioning of a fully integrated circuit complete with feed coal classification to remove the minus-30-micron material, dense-medium cycloning of the 300 by 30 micron feed coal using micronized magnetite (<10 microns), and medium recovery via drain & rinse screening and various stages and types of magnetic separation. This paper will describe the micronized-magnetite beneficiation technology and the scope of work for this project including an update on the status of the project, the circuit, and the proposed test plan.

Jan 1, 1995

By H. M. Garrett

Dr. Ft: L. Handy of Iowa State University&apos;s Engineering Experiment Station very handily reduced the relatively complex cement making process to ultimate simplicity: "Take two cups of crushed limestone; add one-half cup of clay or pulverized shale (plus perhaps some sandstone or iron ore; depending); mix thoroughly and grind up fine. Bake in white-hot oven at about 2,600 F. Cool. Add a tablespoon of gypsum: and, again, grind very fine. If you can do this for about a penny a pound, you can almost compete.&apos; Before Dr. Handy&apos;s time, is the early days of the U. S. Cement Industry, from 1817 when the Erie Canal was started to 1895 when the first rotary kiln was built, this was the recipe, more or less. Dr. Handy&apos;s raw materials were deposited in a natural "cement rock" found in the Hudson, New York and Lehigh, Pennsylvania valleys. At first the natural rock was pulverized (not ground fine) and interlayed with wood for "baking" at about 1,800° F in a batch process vertical shaft kiln or beehive oven; then the calcined pozzalonic (lime and silica) product was cooled and ground fine for shipment in wooden barrels. Later, in 1871, true portland cement was made. The same natural rock was ground fine to make briquettes; interlaced with wood or coal in the "Beehives"; and baked at a clinkering temperature of about 2,6000 F to produce clinker (calcium silicates) which was ground fine for sale. In those days, the crude cements dropped in price from over 1 cent to 1/2 cent per pound. In 1895 the rotary kiln introduced-continuous instead of batch processing. The countercurrent process allowed the same raw materials (now finely ground to about 80% minus 200 mesh like face powder) to be fed at one end of the rotary kiln. Heat from a coal burner was introduced with combustion air at the other end to produce the requisite clinkering temperature. The clinker product was discharged for atmospheric cooling, mixed with gypsum, and again ground fine as face powder. The cement was sold primarily in barrels, later in jute or cloth bags, then paper bags, and now primarily in bulk truck and barge carriers. The price dropped to a 1/4 cent per pound by 1910, but with recent inflation it now sells for 2 cents per pound.

Jan 1, 1978

By Roger S. Dewey

1.1. INTRODUCTION Despite indications of a general economic recovery in the U.S. during the mid-19801s, mine operators have not generally shared in the benefits of these reported better times. Budgets have not rebounded, borrowing is tougher, parent companies&apos; pockets are not as deep as in previous years, and margins are not any better -- if there is any left over at all. Managing capital equipment budgets is always a challenge, and the last five years of stretched equipment lives make these decisions more tenuous. Delays and avoidance of replacements due to tough times inevitably makes those decisions increasingly difficult and usually more expensive The purposes of this paper are to present. a brief refresher outline of the fundamentals of equipment replacement analysis, to suggest a number of papers where analysis methods are explained in greater detail. and to recommend the use of a widespread microcomputer software capability (1-2-3) as the easiest path to a much-needed solution for a very difficult, and usually under-supported management decision problem 2. REPLACEMENT DECISION POLICY Investments in equipment replacements must compete for capital with all other investment alternatives. Capital for replacements of ten represents a greater commitment than do the new projects which a company might handle in a given year. But. sadly, formal policies for standardized analysis of replacements rarely exist, even in major companies. Yet this policy can be very significant in determining the competitiveness of a firm. Whereas many replacement decisions are based on cost minimization, economists and financial analysts agree that wealth maximization or return on investment is the superior criterion. Though the difference may seem slight, agreement on a firm&apos;s financial objective is vital. Replacement policy should be straight- forward. have a logical basis, and a proper level of sophistication. There are several reasons to develop a policy for replacement decision-making: [I] 1 - equipment&apos;s optimal economic life is nearly always shorter than its physical life; 2 - mine life often exceeds equipment life, so management must face these decisions routinly 3 - replacement capital costs, on an undiscounted basis, can run 25 to 75% of original capital 4 - technological changes may result in a newer machine or system which can operate more efficiently, more safely. or less expensively 5 - estimates should be made consistently in the fundamental areas of life expectancy, availability, utilization. price escalation, taxes 6 - long-term and short-term budgeting without decent data and analytical capability is nearly impossible, or at least ineffective Policy development assumptions which must be considered include: the planning horizon, cost patterns, interest rates, availability of capital, replacement vs. expansion, technology advances.

Jan 1, 1987

By Howard N. Egan

EASTERN COAL CORPORATION is located in the heart of the Appalachian Mountain area of extreme Eastern Kentucky, The mountains are of sedimentary origin, and have been deeply eroded by streams as the area has been thrust up during geologic time. There are many seams of coal interspersed between beds of shale and sandstone. While some of the seams are thin, there are a number that can be economically mined. We are mining the Pond Creek, or No. 2 Gas Seam, at a rate in excess of 6,000 tons per day. Our central preparation plant utilizes tromp baths for the plus 3/8" size and Rheolaveur for the minus 3/8" portion. No provision was made to recover the fine coal, which was included with the plant effluent pumped to a 12 acre refuse pond. The pond is impounded behind the coarse refuse dump. This pond rose 15 feet last year. Obviously, no pond could stand many years at this rate. Limited pond space in this rugged area of steep hills and narrow valleys dictated a revised disposal method. Our first thought was that it would be necessary to dry the fine refuse sufficiently to permit inclusion with the coarse refuse, which is hauled uphill by monitor and then trucked to final disposal.

Jan 1, 1967

By R. S. Conti, M. R. Krump, C. P. Lazzara Ph. D., R. L. Derick, L. L. Chasko

A mine fire is one of the most challenging safety issues facing a mine operator and can occur at any location underground. The National Institute for Occupational Safety and Health (NIOSH) and the Twentymile Coal Mine, CO, conducted in-mine experiments to determine the capability of high-expansion foam for addressing underground fires. The tests were conducted in sloping entries with high-capacity diesel-powered foam generators. The following results were observed: a well-designed, maintained and properly operated high-expansion foam generator can propagate a foam plug hundreds of feet in steep upward-sloping (20%) multiple entries against a ventilation pressure; stoppings and partitions designed to contain the foam plug in upward-sloping entries must be substantially constructed; and the predicted quantity of foam concentrate can be significantly less than the actual amount used, due to foam losses, such as bubble breakage on dry surfaces. This paper describes the production of high-expansion firefighting foam and discusses the in-mine experimental tests and results.

Jan 1, 2010

By S. Meng, R. Jin, W. Hu

In alkaline pulp, galena is depressed by sodium carboxymethyl cellulose (NaCMC), while Cu(II) -activated sphalerite exhibits a high floatability so that satisfactory separation can be achieved. In addition to hydrogen bonding, chemical bonding of NaCMC with galena is confirmed by infrared (IR) spectra; only hydrogen bonding is involved between NaCMC and Cu(II)-activated sphalerite. It is also found that the greater the degree of substitution and polymerimtion of NaCMC, the stronger the depressive effect of NaCMC and that lower stirring speed favors the depression.

Jan 1, 1988

New Mexico?s active coal mines have reclamation challenges that are being successfully resolved through the application of geomorphic grading methods. Soils and overburden material are often of poor quality, and annual precipitation is low. Revegetation on south and west aspect slopes often failed to persist. The New Mexico Mining and Minerals Division had therefore been encouraging topographic diversity on reclamation to improve water harvesting and reduce the percentage of south aspect slopes. Steeply dipping, multiple coal seams may be mined by open pit methods. Structurally-controlled trellis drainage patterns that exist premine have to be replaced with dendritic drainage patterns on reclamation where the overburden had been pulverized. Sodic spoil material is prone to differential settling and the creation of piping features in areas where runoff ponds, which may lead to downslope instability. In each of these scenarios, the approximation of natural drainage patterns on the reclamation has reduced erosion and sedimentation by creating shorter slopes with correct profiles, and by improving conditions for revegetation establishment.

Jan 1, 2010

By F. L. Pirkle

A heavy mineral deposit about 1.6 km (1 mile) in length, 0.13 km (0.08 mile) in width and averaging about 3 m (10 ft) in thickness is exposed approximately 130 km (80 miles) east of Denver, along Interstate 70, in Elbert county, CO near the town of Limon. The deposit is exposed in a geomorphic feature known locally as Titanium ridge. The dominant heavy minerals, accounting for about 70% of the total heavy-mineral suite by weight, are ilmenite, garnet and zircon. The mineralized zone appears in a series of visually interpretable facies that are stacked vertically and represent subtidal, forebeach, backbeach, washover fan and aeolian depositional environments. These paleoenvironments are analogous to depositional environments represented by a modern heavy-mineral bearing facies tract on St. Catherines Island, Ga. Thus, Titanium ridge provides evidence that heavy-mineral accumulation models for late cenozoic deposits in the Georgia and Florida coastal plains are applicable to heavy-mineral deposits of the Western Interior subsurface and, by implication, the Western Interior Seaway, extending from Mexico to the Canadian Arctic.

Jan 1, 2012

By Joe Hachey, Jerry Dorn, Jeff Schutt, Derek Penrice

"Sound Transit’s East Link Project, a $3.7 billion (2015 $), 14-mile light rail extension, will connect downtown Seattle with the rapidly developing east side cities of Bellevue and Redmond. Among the most technically challenging aspects of the Project is the 2,435 foot long Downtown Bellevue Tunnel (DBT), which will be constructed through the central core of Bellevue underneath 110th Avenue NE using a combination of Sequential Excavation Methods (SEM) and cut and cover tunneling. The 1,980 foot long central SEM component of the DBT will be mined at shallow depth through challenging and complex geology, comprised of glacially overconsolidated soils, containing both regional and perched groundwater conditions and in close proximity to existing high rise buildings. The paper shares lessons learned from the planning decisions and risk based approach to the investigation, design and procurement processes which shaped the DBT configuration and enabled a successful transition to the project’s construction stage. INTRODUCTION The East Link Project is a voter-approved $3.7 billion (2015 $), 14-mile extension of the existing Sound Transit (ST) light rail transit (LRT) system from downtown Seattle, across Lake Washington via I-90, to the cities of Bellevue and Redmond on the east side of Lake Washington. With targeted completion in 2023, East Link will provide riders with an efficient and reliable connection between the largest population and employment centers on the east side and downtown Seattle. The project alignment is indicated in Figure 1 below.ST completed the Preliminary Engineering (PE) phase of the East Link project in late 2011. Subsequently the final design contract for the easternmost seven miles of the project was awarded to the H-J-H Team, a joint venture comprised of HNTB, Jacobs Engineering and Hatch Mott MacDonald in February 2012. H-J-H’s final design scope includes approximately 7 miles of double-track LRT between the east end of the I-90 East Channel Bridge and the Overlake Transit Center Station. While the project scope is extensive and diverse, the focus of this paper is the DBT. The DBT is located immediately north of the East Main Station, and travels approximately one half mile through downtown Bellevue under 110th Avenue NE between Main Street and NE 6th Street; terminating at the Downtown Bellevue Transit Center (BTC) Station. The location and extent of the DBT is indicated in Figure 2."

Jan 1, 2016

By T. Guler

Turkey has important celestite reserves in Sivas. These reserves have gypsum and/or calcite as gangue minerals. Celestite-calcite ore cannot be concentrated by gravity methods due to the low efficiency of gravity methods in fine sizes. Research was tried to concentrate celestite to a market grade by flotation. Parameters such as pH, particle size, dosage and types of collector and depressant were examined. Cyanamid A-845 and Na-oleate combination as collector, sodium silicate as depressant, and Aerofroth-65 as frother were found as the optimum flotation reagents. By applying 3-stage cleaning, a concentrate assaying 95,34 % SrS04 was obtained with 84,93 % recovery.

Jan 1, 1999

By R. D. Auten

This paper is primarily a report on the process of using oolitic aragonite, as received from Marconi& Ocean Industries, Ltd. without further processing, for a major portion of the raw feed to a rotary kiln producing cement clinker. Oolitic aragonite is a high purity calcium carbonate material, dust free, with the appearance of a course, white sand. It is farmed when under the right conditions of temperature ocean currents, and ocean floor topography. The calcium carbonate will precipitate into small spherical particles on the ocean floor. These oceanic conditions are correct to cause precipitation of the calcium carbonate near Ocean Cay in the Bahama Island chain. The present growing deposit near Ocean Cay is in the billions of tons and is mined by a relatively shallow-operation hydraulic dredge. The aragonite thus formed is en orthorhombic crystaline form of calcium carbonate with a specific gravity of approximately 2.9. At a temperature of 505°C. (940F), the aragonite converts to the hexagonal crystal of calcite with a specific gravity of 2.6 to 2.7. This change in specific gravity weakens the structure of the particles but the individual pieces are still fairly hard. When the material is then calcined at 900°C (1650°F), the particles retain their shape but become soft and will break up under finger pressure.

Jan 1, 1978

By Jacob Petersen, Jon J. Kellar, Samuel Kessinger, Kiran Green

 The paper demonstrates that Belle Fourche Shale (BFS), an abundant shale, can be transformed into a ceramic through careful characterization and thermal processing. The study explores the potential of BFS ceramics for use as refractories and thermal energy-storage devices, highlighting their high thermal storage capacity, good thermal shock resistance, and cost-effectiveness.

Dec 1, 2023

By H. Douglas Dahl

Thank you, Don Gentry, for your generous introduction. It is not adequate simply to say that I appreciate very much the vote of the Award Committee putting forth my name as the winner of the 1992 Daniel C. Jackling Award. To look at the list of previous Jackling Award winners is a humbling experience. The Society for Mining, Metallurgy, and Exploration has been blessed with some exceptional members over the years, and I feel privileged indeed to be included among the Jackling Award winners. During the years of my education at Penn State, my field of specialization was mining engineering, with particular emphasis in my master&apos;s and Ph.D. work on rock mechanics. But my career has not been quite so tightly focused as that. I have been involved with coal mining in all its variety - its technical aspects, both theory and practice; and its business side, dealing with management and labor, accountants and lawyers, politicians and environmentalists. And I have also been involved with related fields - construction; exploration; barges, railroads, ships and docks; supply houses; the coke business; you name it. Coming from that practical background, I believe it is most appropriate that I talk with you today about some practical matters. But I will not advise you today how to mine coal or protect roof in a hard-rock mine. You fellows know how to do that. The practical matters that I have in mind relate to policy - national policy. I will acknowledge immediately that national policy is often much less than practical, but bear with me as we explore the subject together. I am reminded of a supervisor I had early in my career. He very strongly advised me, back in 1961, to "get involved in the political process," for without objectivity injected into our national policy making, we will become a second-rate economic power. I have selected as the subject of my remarks today, "Coal and the de facto National Energy Policy." There is an energy policy relating to coal, a de facto one, and it&apos;s the one we see as a result of regulation, attitudes and culture from our nation&apos;s capital. This de facto policy is the one we in the coal business live with every business day. My thesis is very simple - Coal is, in fact, a vital part of our national energy policy and will remain so, as a practical matter, no matter what politicians may do to us, or not do to us. Coal will prevail - that will be the happy ending to my story in which, of course, we are the good guys in the black hard hats. But first, I must flesh out the plot with some other characters and with some threatening activities. There are five main characters in my story: in order of appearance - Perpetual Politics, Rampant Regulation, Selective Science, Electrification and Confident Coal. The time: the present. Perpetual Politics is always a threat to coal. When you cross the Capital Beltway into Washington, D.C., check your wallet and your gold fillings, because you&apos;re not likely to run into any friends. On Feb. 20, 1991, just over one year ago, President Bush presented to Congress his National Energy Strategy. It&apos;s a thick document of more than 260 pages, with discussions on securing our future energy supplies, increasing energy effi-

Jan 1, 1993

By Andrew B. Allen, Charles W. Robinson, Robert L. Schneider

In April, the US Synthetic Fuels Corp. broke a three-year silence and made its first financial award by approving a $820,750 loan for the First Colony peat-to-methanol project in North Carolina (ME, May, page 403). Peat Methanol Associates (PMA), a partnership between Koppers Co., ETCO Methanol Inc., Transco, Peat Methanol Co., and l. B. Sunderland, broke ground at First Colony last year and plans to begin production in Dec. 1985. Although the award is only a small part of Synthetic Fuels Corp.&apos;s $15-billion budget, it does signal the corporation&apos;s intention to move aggressively ahead. It also is a positive indication that First Colony will be completed and operated successfully. This article describes the methods and equipment that will be used to harvest peat at First Colony, as well as how the peat will be converted to methanol. Introduction Peat deposits found along North Carolina&apos;s coastal plain contain high-quality fuel-grade peat with an average heating value of more than 23.3 MJ/kg (10,000 Btu/lb) (dry), with a low sulfur and ash content. The deposits differ from other US peats in that they contain large, sound Atlantic White Cedar and Cypress logs, stumps, and roots that may extend throughout the full depth of the deposit. A second difference is that these deposits are much more highly decomposed and, in the raw state, have the appearance and feel of a heavy, reddish-brown grease. These factors make it impractical to use standard production equipment so a new line was developed. Also, because of these conditions, techniques were modified to facilitate production. First Colony Farms, located near Creswell, NC, developed and evaluated a milled peat program. Equipment for this production method was designed and built, production rates were established from field operations, drying rates were established, weather data were analyzed, and total operating and capital costs were estimated. The method depends on the sun and wind for drying peat to the desired moisture content, in this case around 40%. Therefore, field preparation is actually the construction of a large solar collector to dry the peat so it can be harvested and stockpiled. It is essential that this collector be properly profiled initially and maintained during production to prevent precipitation from ponding. Initial Field Preparation Initial field preparation includes cleaning existing canals and constructing ditches and water control structures for proper drainage of rainwater run-off, building adequate roads for site access, removing surface vegetation, and profiling and sloping the fields. At First Colony, the 60.7-km2 (15,000-acre) harvesting area was divided into 129.5-hm2 (320-acre) blocks about 1.6 km (1 mile) long and 805 m (0.5 mile) wide. This was accomplished by cleaning main outfall canals with adjacent roads built from canal spoil at 1.6-km (1-mile) intervals. Existing intermediate canals that feed into main outfall canals at 805-m (0.5-mile) intervals also are cleaned. Headland roads are constructed from canal spoil along each side of each intermediate canal. This 129.5-hm2 (320-acre) block is then divided into 32 harvest strips by small V-ditches constructed at 50-m (165-ft) intervals. At the end of the field with the lowest elevation, corrugated steel pipe culverts are installed under the headland road in each V-ditch to control rainwater runoff into intermediate canals. Runoff water from the fields is diverted to a holding pond to prevent any increase in peak water runoff rates and to allow for more uniform drainage rate than experienced to date. After the drainage system is installed, harvest strips are ready for grinding and sloping operations. Surface vegetation, made up of small, waxy-leafed shrubs such as Gallberry, Bayberry, Magnolia, and scattered pond pine, can be effectively ground and incorporated into the upper surface of the peat layer. Here, it will rapidly decompose and have little effect on overall peat quality, thus eliminating the standard practice of pushing the vegetation and upper wood layer into long windrows with bulldozers and hauling this debris from the fields. Incorporating vegetation into the upper surface is known as the initial 102-mm (4-in.) surface vegetation grind and is accomplished by using a modified Bros Rota Mixer. Following this operation, and by using the same unit, a sec¬ond grind with a depth of 200-255 mm (8-10 in.) is made. This reduces the debris to a finer consistency, mixes it with the upper peat layer, and grinds any wood found in the upper 200-255 mm (8-10 in.). After initial grinding operations are completed, the augering or sloping operations can be accomplished with little or no hin-

Jan 7, 1983

By A. Juganda, Jr. Bogin, S. Saki, R. Gilmore, J. Brune, J. Grubb, S. Lolon

"In longwall mines, atmospheric or barometric pressure fluctuations can disturb the pressure balance between the gob and the ventilated working area of the mine, resulting in a phenomenon known as “gob breathing”. Gob breathing triggers a gas flow across the gob and the working areas and may result in a condition where a methane accumulation in the gob flows into the face area forming an explosive mixtures. This paper discusses results of Computational Fluid Dynamics (CFD) modeling carried out to analyze this phenomenon and its impact on the explosive mixture development under a bleeder-ventilated longwall gob panel scheme. Modeling results indicate that the gas inflow and outflow across the gob and the formation of Explosive Gas Zones (EGZs) are directly affected by the barometric pressure changes. Methane gas and EGZs in the gob expand out toward the face and bleeder entries during the falling barometric pressure. Where methane zones interface with mine air, EGZ fringes may form along the face and in the bleeder entries. When the atmospheric pressure increases, an ingression of oxygen into the gob is observed that can also increase EGZs in volume. The findings from this study help assess the methane ignition and explosion risks associated with fluctuating atmospheric pressures. INTRODUCTION Methane explosions continue to be a daunting risk for underground coal miners, although the number of related fatalities and injuries in the U.S. coal mining industry has steadily decreased since the establishment of the U.S. Bureau of Mines in 1910. Still, the consequences of a methane explosion are often disastrous with multiple fatalities and property damage often leading to permanent shutdown of the mine. Methane is formed during the coalification process and is released from the coal seam to the mine atmosphere when the coalbed is disturbed by mining or natural causes such as earthquakes. If not properly diluted by appropriate mine ventilation, this methane may accumulate in the active mine workings and gob areas. Researchers at the Colorado School of Mines have developed numerical models showing how and where explosive methane may accumulate in gob areas. Historical mine explosions appear to show a connection between mine explosions and fluctuating barometric pressure as a result of stormy weather. McIntosh (1957), Boyer (1964), and Kissell et al. (1973) studied the influence of barometric drops on major coal mine disasters in the United States prior to 1970. Their statistical analyses found that a majority of these disasters occurred in the fall and winter months when the barometric pressures were influenced by unstable weather conditions and noted increased methane content in the mine workings during times of falling pressure. Studies conducted by Fauconnier (1992) and Hemp (1994) found similar connections between methane explosions and barometric pressure fluctuations in a majority of gas explosions in South African mines. Ten out of twelve major mine explosions with five or more fatalities in the U.S. after 1970 were found to have occurred during the months of November through April when barometric pressure swings were more abrupt and intense (Lolon et al., 2015)."

Jan 1, 2016

By J. A. Organiscak

Data on dust-control practices, mining conditions and occupational exposures were gathered for approximately 80 underground continuous mining units. Despite silica contents on dust samples in excess of 5%, nearly forty units successfully maintained silica concentrations at or below 100 µg/m3 on a majority of occupational dust samples, while the remainder had difficulty maintaining this level. These two sample sets were termed Group A operations and Group B operations, respectively. This data was compared to identify causes of high occupational silica dust exposures. Analyses of dust-control parameters and geologies revealed only minor differences between these two groups. However, subsequent comparisons of face ventilation design showed considerable differences in silica exposure and silica content between Group A and Group B at the continuous mining machine and roof bolter operator occupations. These differences were minimal when using exhaust curtain ventilation with a dust scrubber. This face ventilation system can benefit operations having difficulty controlling silica dust exposure and silica dust content. The collected data also showed that occupational samples from Group B operations possessed generally higher silica exposures and silica content than similar samples from Group A. The single head roof bolter (helper) possessed among the highest silica exposures and silica contents in both groups.

Jan 1, 2002

By Amoussou Coffi Adoko, Shevaune Zeng, Sebastian D’Hyon, Gareth Kennedy, Eleonora Widzyk-Capehart

Inertization of coal dust with stone dust is a common control implemented within underground coal mines to mitigate the hazard of a coal dust explosion. To achieve adequate inertization, the total incombustible content (TIC) of the coal/stone dust mixture is required to meet certain percentages depending on the risk and relevant legislation. Current methods for determining the TIC of a mixture involves laboratory analysis, colorimetric comparison, or the use of portable instruments. This paper provides preliminary analysis of determination of a sample’s TIC in real-time with chemometric modelling, using portable instruments employing near-infrared (NIR).

Feb 1, 2024