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By E. R. Gibson

It is quite generally conceded that the coal mining industry is among the most progressive in the adoption of modern and efficient equipment and mining methods, but most woefully antiquated in many respects in the matter of systematic accounting. The cause of this condition is problematical, but is usually thought to be due to false economy. We realize that those who do not understand accounts, or like accounting, are inclined to be disdainful of accounts and statistics, and to under-estimate the benefits derived from the expense and labor involved in proper accounting. The business that is run without a proper accounting system is subject to haphazard financing and courts disaster. Furthermore, the operator who disposes of his product without due regard to the requirements of the industry as a whole, as reflected in the cost of doing business, is an unfair competitor. No one will deny that the possible production of coal in the United States is much in excess of the demand. While it is true there is an occasional shortage in certain localities, it is due to temporary abnormal conditions which are overcome in a short period of time, when the mines are again obliged to take idle time, and herein lies the danger, not alone to the operator who neglects to keep informed as to operating costs; but to his competitor as well. While physical conditions and operating methods differ materially, accounting methods must likewise differ in some respects, but irrespective of how the result may be obtained, a true statement of cost is absolutely essential. Daily cost statements may be preferred by some, but have proven unsatisfactory, generally speaking, because of variation in production as well as in both labor and material expense from day to day; therefore, we will confine our attention to a monthly cost statement. To be most effective, operating cost statements should be prepared and submitted to the officers as soon after the close of the month's busi¬ness as possible, to enable them to remedy any defects in the operations that might be discovered by an analysis thereof. Opinions differ materially with respect to the most efficient method of compiling and the distribution of labor and material. The writer believes that a time book which provides space in which to enter the number of hours worked each day of the month by each employe, together with distribution thereof, is the most accurate, simple and complete. This record will show the service performed by an employe each day of the month and the account to which same is properly chargeable. This, of course, refers only to the employe working by the-day or month. While there can be but little said concerning the compiling and distribution of miners' wages, as the weighman's bulletin used almost

Jan 1, 1921

By d&apos, L. R. Fletcher, Andrea. D. V., M. A. Peltier

The Bureau of Mines analyzed coal mine blasting accident data obtained from the Mine Safety and Health Administration (MSHA), U.S. Department of Labor. The data were examined to determine the causes, frequency, and severity of accidents in an effort to point out the most dangerous aspects of coal mine blasting. Accident data for the 14 years from 1971 through 1984 show that there has been a total of 43 fatal and 926 nonfatal blasting accident victims in surface and under- ground coal mining. This is an average of 3.1 fatal and 66.1 non- fatal injuries each year. Underground coal mining accounted for 60.5% of the fatal and 78.7% of the nonfatal accidents involving explosives and breaking agents in coal mining. In addition, since 1970 there have been 53 fatal and 20 nonfatal injuries that occurred when explosives were the ignition source for dust and/or methane explosions in underground mines. Abstracts from 297 accidents that occurred from 1978 through 1984 were also examined to determine accident causes. Most accidents occur during scheduled blasting, and failure of the blast area security system is the leading cause. Blast area security problems in surface mining are failure to clear the blast zone, failure of personnel to follow instructions, inadequate guarding, and failure to retreat to a safe location and/or take adequate cover. Other common causes in surface mining include premature blasts, excessive flyrock, and misfires. In addition to the above causes, accidents in underground coal mining can be due to rockfalls triggered by the blast, unexpected breakthroughs, fumes, and incidents associated with Airdox-type systems.

Jan 1, 1986

By Jürgen F. Brune, William H. Schiffbauer

Communication problems are not new. Research in this area goes back as far as 7922 when the US Bureau of Mines performed experiments to detect radio signals from inside their experimental mine in Bruceton, Pennsylvania. Many improvements to mine communications have been made over the years but for any number of reasons the underground coal mining industry has been behind in implementing advances. Present communications systems far underground mines can be hard-wired or wireless. Both types of systems can fail when faced with fires, roof falls, explosions, and power or battery failure. Currently installed wireless communications systems usually employ a special antenna cable called a "leaky feeder" Fiber optic cables are also used in some applications to form a "backbone" for wireless transceivers. Through-the-earth (TTE) and wireless radio systems are less common. Except for TTE systems, most wireless systems require some wire-bound components, which are susceptible to failure during disasters as cable breakage interrupts communications.

By Wm. Moorhead

Safety Measures Employed at the Dawson Mines Preventive measures for eliminating and localizing explosions is a subject of special interest to Coal Mining operators at the present time. I shall endeavor in this paper to present the practical methods which have been developed at the mines of the Stag Canon Branch of the Phelps-Dodge Corporation, Dawson, New Mexico. Adobe Dusting Adobe is used for practically all dusting on the main haulage roads. It is obtainable in sufficient quantities adjacent to the mines. Loaded into railroad cars by a clam-shell loading crane, and transferred to the mine pit cars at the nearest available point, it is readily distributed along the motor roads by means of the mine locomotives. Of first consideration for adobe dusting is the preparation of the roadway. It is essential that all loose coal and dust be removed, at least to a depth of three or four inches below the top of the rails. The adobe, in a more or less moist condition is unloaded by hand from the pit cars and stored along the previously prepared roadway, to be later scattered to a depth of several inches over the floor, and over the ribs and roof such as is possible by the use of a shovel. The adobe soon loses its moisture and becomes pulverized. Due to the disturbance caused by passing motor trips, men and animals, the dust is effectively scattered along the ribs and roof of the roads. The velocity of the intake air aids materially in sustaining the suspension of this inert matter. Another scheme for distributing the fine dust in use is to chain the top of a pine tree to the rear of the trips, both empty and loaded. Dragging it along the motor roads stirs up the dust and aided by the intake air it is carried for long distances into the workings. The adobe is continually loosened and raked, all rock, coal, etc., being collected in piles and later loaded out in pit cars. One man is employed for each six thousand feet of entry. Dusting Main Return Air-Courses The air-courses are first thoroughly cleaned. All the loose coal and rock is loaded out, the ribs and roof washed down several times. Every five or six hundred feet, the stoppings between the main and return entries are broken through and small doors installed. Blowers are used to force the fine dust into the return air-courses through these openings. Thus suspended the dust travels a considerable distance before it is deposited on the floor, ribs and roof. The material used is chiefly adobe, sun dried, and screened on the outside. A two ton car load of this dust will cover several hundred feet of airway as very little loss occurs, often depositing from 2 to 6 pounds per running foot of entry. Methods of Insertion Blowers are used to force the dust into the main returns. One unit consists of a small Buffalo blower mounted on a truck with a two H. P. motor. A six-inch pipe is attached to the blower and runs the full length of the truck with a projection over the end. A hopper is built over the pipe and connected. Stove pipe or canvas tubing is led from the pipe through door in stopping. When the blower is started dust is fed into the

Jan 1, 1924

By Frank E. Chase

During the past quarter century, coal mine geologists have evolved from providing a qualitative description of drill core and coal reserves into quantitative geotechnical specialists who bridge the gap between geology and engineering. In the late 1970?s and early 1980?s, hazard prediction mapping was in its infancy. At best, hazard maps identified rudimentary structures and conditions such as stream valley locations, sandstone/shale transition zones, and lineaments. A ?technical disconnect? had existed between geologists and mining engineers as each profession operated largely independent of each other. Engineers did not readily integrate geology and geologic conditions, with the exception of coal thickness, into mine planning. Geologists were relied upon for reserve estimates and did not participate in mine planning or design. The employment and market slump of the 1980?s and 1990?s combined with mining more challenging reserves mandated that this gap be bridged and forced geologists to learn to speak more ?numerically? to engineers so they could be understood. The purpose of this paper is to describe the procedures and thought processes used by coal mine geologists when determining various mineability and reserve extraction feasibility issues. The paper will also address underground geologic hazard mapping and prediction techniques. To achieve these objectives, the opinions and experiences of leading coal mine geologists, geotechnical and strata control specialists across the United States were solicited.

Jan 1, 2006

By Frank E. Chase, John Rusnak, David Newman

During the past quarter century, coal mine geologists have evolved from providing a qualitative description of drill core and coal reserves into quantitative geotechnical specialists who bridge the gap between geology and engineering. In the late 1970’s and early 1980’s, hazard prediction mapping was in its infancy. At best, hazard maps identified rudimentary structures and conditions such as stream valley locations, sandstone/shale transition zones, and lineaments. A “technical disconnect” had existed between geologists and mining engineers as each profession operated largely independent of each other. Engineers did not readily integrate geology and geologic conditions, with the exception of coal thickness, into mine planning. Geologists were relied upon for reserve estimates and did not participate in mine planning or design. The employment and market slump of the 1980’s and 1990’s combined with mining more challenging reserves mandated that this gap be bridged and forced geologists to learn to speak more “numerically” to engineers so they could be understood. The purpose of this paper is to describe the procedures and thought processes used by coal mine geologists when determining various mineability and reserve extraction feasibility issues. The paper will also address underground geologic hazard mapping and prediction techniques. To achieve these objectives, the opinions and experiences of leading coal mine geologists, geotechnical and strata control specialists across the United States were solicited.

By James R. Aggson

This paper summarizes the research effort that was conducted as part of a cooperative agreement between the U.S. Bureau of Mines, Denver Mining Research Center and the Pittston Company. The objective of this investigation was to further the understanding of the floor heave ground control problems that have plagued underground mining of the Beckley coalbed in southern West Virginia. Floor heave is both economically and structurally undesirable. Floor heave is accompanied by a redistribution of stresses and loads that are associated with an underground opening. This redistribution of stresses may cause roof or pillar problems that otherwise would not have occurred. The floor heave that occurs in the Beckley coalbed is not cons1dered to be caused by "squeezing" or plastic flow of the materials involved. The "squeezing" type floor heave is normally associated with relatively weak floor members that contain significant amounts of clay mineralization. The floor members in the Beckley coalbed are competent, relatively strong materials which fail in a manner that can best be described by the term "buckling." This buckling-type failure is indirectly related to the time-dependent deformation properties of the materials involved, but is considered to be more of a slender column, or panel, type failure than a "squeeze" or "flow"-related failure. The Beckley coalbed has had a history of floor heave ground control problems. The Glen Rogers mine, which opened in the 1920's, experienced extensive floor heave. In a report dated April 1929, James P. Keatley of the West Virginia State Department of Mines described the floor heave in the Glen Rogers mine. Several observations listed in the Glen Rogers report that appear to be consistent with current observations follow: 1. Water plays no apparent part in the floor heave process. 2. No evidence of gas has been found in the floor. 3. The thickness of the overburden, which varies from 183 to 396 m (600 to 1300 ft), has no relationship to the floor heave. In the conclusions of the 1929 report on the Glen Rogers mine, Keatley states, "A statement in brief as to the cause (of floor heave) would lie that an undetermined natural condition doubtless augmented by former and present mining methods causes the bottom to heave." As this report will show, Mr. Keatley's insight into the problem was most accurate. The "undetermined natural condition" is the existence of a biaxial, horizontal, compressive stress field. This stress field is in excess of that which would be expected from gravity loading. This stress field and the material properties of the floor rock combine to cause the floor heave that has been experienced. The floor heave that occurs in the Beckley seam generally occurs as arching, with a tension fracture, near the center of the floor span or as a break near the rib followed by vertical deflection (of the floor) at the rib and sloping of the floor across the entry. Examples of the floor heave are shown in Figures 1 and 2. The two types of floor heave are merely different manifestations of the same basic failure mechanism. When the entries experiencing floor heave were identified on a map of the mine under investigation, it was apparent that there was a relationship between the floor heave and the direction of the entries. The main entries, which are used for ventilation and haulage, experienced the majority of the floor heave. This directional relationship suggested a directionally related loading mechanism, or more specifically, a biaxial, horizontal stress field that exceeds what would be expected by gravity loading. Since the main entries were oriented at a bearing of N25oW, it was hypothesized that the maximum compressive component of the horizontal stress field was at 90° to these entries or at a bearing of N65oE. An in Situ testing program was developed to test this hypothesis and investigate the floor heave problem.

Jan 1, 1978

By Raymond T. Moore

The Federal Coal Mine Health and Safety Act of 1969 (FCMHSA) begins with this statement: "Congress declares that the first priority and concern of all in the coal mining industry must be the health and safety of its most precious resource -- the miner; . . ." At the Federal level this responsibility is shared by the Department of the Interior and the Department of HEW. The health research and standard setting activities under the Act are largely the responsibility of the Department of HEW, and with the exception of Title 4, Black Lung Benefits, have been delegated to our Institute, which I will refer to henceforth as NIOSH. In addition, we bear certain joint responsibilities with the Department of the Interior. These include dust sampling and respirator approval. To complete the picture, the Department of Labor has recently assumed Black Lung Benefit respon¬sibilities from the Social Security Administration under Title 4 of the Act.

Jan 1, 1974

By M. A. Trevits, I. R. Houlison, A. C. Smith, T. P. Mucho

Timely and rapid intervention to underground combustion events (fires, explosions, and spontaneous combustion) is the key to the successful control of the mine atmosphere and restoring of a coal mine to production. The focus of this paper is the utilization of a GAG 3A jet engine system to combat either large out-of-control fires or to render an entire mine inert when access to problem areas is difficult or impossible. This system is based upon a Soviet designed agricultural jet engine which consumes aviation fuel with oxygen (O2) from the intake air and exhausts combustion gases, primarily carbon dioxide (CO2) and water (H2O), along with the nitrogen (N2) from the air and small amounts of carbon monoxide (CO) and hydrogen (H2). The system is designed to approach stoichiometric combustion (ideally, pure burning that scavenges all the oxygen from the intake air). Therefore, these exhaust gases are almost entirely “inert gases”- i.e., gases which do not contribute to, and in fact, can suppress the combustion process due to the lack of oxygen. Other methods to inert mine areas have been used in the US and internationally, but these methods usually use low flow inertisation equipment or methods. Use of these low-flow inertisation equipment and methods has been successful in proactively rendering gob areas inert and has the ability to inert the entire mine workings. Due to the low flow rate, however, a substantial period of

By Jayne Somers

Methane (CH4) is a potent greenhouse gas, accounting for 15 percent of all global greenhouse gas emissions in 2005. Since methane has a much shorter atmospheric lifetime than carbon dioxide (CO2), reducing methane emissions can achieve considerable climate benefits over the next 25 years. Coal seams often contain significant quantities of methane and CH4 released to the atmosphere from gassy mines during coal extraction is a major source of greenhouse gas emissions. Methane (CH4) emissions from coal mining activities constitute approximately 6% of total global human-related methane emissions. Coal mines around the world have recognized that methane is a clean energy resource that can be captured and used productively. Coal mine methane (CMM) is currently utilized for power generation, natural gas pipeline injection, vehicle fuel, industrial process feed stocks, on-site mine boilers, mine heating, and home heating distribution systems. Upgrading mine degasification systems can often improve gas quality and create favorable project economics. The United States has been a leader in coal mine methane (CMM) recovery and use since the 1990?s. There are now 15 projects at active underground mines in the U.S., as well as 26 abandoned mine methane projects. Recovery and use projects at active underground U.S. mines reduced methane emissions by approximately 49 Billion cubic feet in 2010. In an exciting new development, a ventilation air methane (VAM) mitigation project at the CONSOL McElroy mine in West Virginia was installed by Verdeo. Operational since September 2012, this is the first commercial-scale VAM project in the U.S. and the project will reduce methane emissions by an estimated 920 MMCF/yr. As part of the U.S. Greenhouse Gas Reporting Program, actual data on methane emissions from underground coal mines was collected for the first time in 2011 and reported to U.S. EPA in September 2012. The data collected will help inform stakeholders, particularly the underground coal mining industry, of CMM emission sources on public and private lands. The detailed data will also shed light on the specific sources of methane from active underground coal mines and highlight project opportunities for the U.S. coal industry. The paper will cover U.S. coal mine methane emissions, U.S. CMM utilization and destruction projects, Federal policies and State incentives for CMM capture and utilization. 2011 CMM data from the U.S. Greenhouse Gas Reporting Program Subpart FF will be analyzed and compared with previous U.S. Greenhouse Gas Inventory estimates. Other developments, including the voluntary carbon market, will be discussed.

Aug 1, 2013

By C. R. Nailler

Two recently published papers describing the use of psychological tests for selection and placement of coal mine personnel have created considerable interest within the Coal Industry, one paper, published in the April 1957 "Mining Congress Journal," entitled "Personnel Evaluation and Training," discusses the use of tests by the Christopher Coal Company, The second paper, published in the "West -Virginia Coal Mining Institute's 1957 Report" and in the September 1957 "Coal Age," entitled "Testing to Select Better Personnel for Coal Mining Today," outlines Hanna Coal Company's test and selection procedures. Since these rather detailed sources are readily available, and to avoid repetition of the material in them, we will confine this paper to a very brief review of the essential steps already taken by these companies and a more extensive look at newer material. Briefly, the Personnel Managers, Mr. Harold L, Durrett and Mr. Albert M,. Rowe, of the Hanna Coal Company and Christopher Coal Company, in conjunction with Dr. Quin F, Curtis, Head of the Psychology Department of West Virginia University, developed two different groups oftests for coal mine personnel, The first group oftests was designed to assist in the selection of supervisors. These tests of the supervisory group were "The California Short Form Test of Mental Maturity - Advanced Series," which gave an I.Q. rating, and the second test is known as "The Minnesota Multiphasic Personality Inventory," which measures several personality characteristics, These tests must be given, grade, and interpreted by a person trained in psychological testing. As a result of testing all of Christopher's supervisory employees (seventy in number) by this method, and then comparing the individual results with the individual ratings of the foremen on the job, a so-called foremen's scale was developed. If this resulting foremen's scale had been used to select the foremen who were rated as, the best men in on-the-job performance, it would have correctly identified seventy-four percent of that group.

Jan 1, 1958

By R. C. Gilmore, J. F. Brune

"Pulverized limestone rock dust used in United States underground coal mines to prevent and suppress coal dust explosions must easily disperse by forces of a methane or coal dust explosion. Moisture in the mine environment causes caking of the dust. Colorado School of Mines researchers performed dispersibility tests in a full-size explosion test drift. Tests included conventional, hydrophobized, and rock dust approved for German mines. Conventional and German standard rock dust products partially agglomerate, which may not be effective in suppressing a coal dust explosion, while hydrophobic rock dust retains better dispersibility.INTRODUCTIONA coal dust explosion devastated the Upper Big Branch mine in 2010 resulting in the death of 29 miners, the worst mining accident in the United States since 1972. The explosion propagated through approximately 65 km of active mine workings, but was extinguished in areas that had been properly rock dusted (Page, 2011). Researchers have long studied and established the ability of inert limestone rock dust to suppress coal dust explosions, see Richmond et al. (1975), Cybulski (1975), and Sapko et al. (2000).To be effective, rock dust must contribute to a total inert content of > 80% by weight and 100% of rock dust particles must pass through an 850 µm sieve, while 70% of the rock dust must be finer than 74 µm. This is established in US regulations 30 CFR §75.2. Dry rock dust is a nuisance that prevents mining work downwind from rock dusting activities. To overcome this problem, dust manufacturers have proposed applying the rock dust as a wet slurry or foam. After drying, manufacturers expected the slurry or foam-applied dust to have the same explosion suppression capabilities as dry-applied rock dust.Researchers at the Colorado School of Mines (CSM) designed and built a full-scale, underground Explosion Test Facility (ETF) at the CSM Edgar Experimental Mine in Idaho Springs, Colorado about 20 miles west of the CSM Golden, Colorado campus. To disperse the different rock dust products, researchers produced an air pressure pulse using a mesh array of PETN detonation cord. This method is simpler, more reproducible and safer than other methods considered, including methane-air explosions and a compressed air cannon. The detonation cord blasts produce a wind velocity of 30 to 50 m/s, the minimum velocity at which coal dust explosions can propagate, based on research by Nagy (1981) and Cybulski (1975)."

Jan 1, 2019

By R. L. Wooten

When discussing what Coal Mine Safety in the future will be, it is important to examine three areas which at present provide significant parameters to the industry. These three areas are: 1) Safety improvements in mining equipment; 2) Labor-management relations; and, 3) The politics of coal mine safety. EQUIPMENT Over the past several decades significant safety improvements have been made in the types of equipment now in use in most operations. Many of these improvements have evolved through mandates from either the U. S. Bureau of Nines, MESA, MSHA; and in some instances, the states. Cabs and canopies are examples of federal mandates while the use of ATRS initially was a state mandate.

Jan 1, 1985

By E. J. Onuscheck

Coal mine safety of the past was plagued by disasters that took the lives of thousands of miners. Through the years new mining methods, improved laws, and a commitment from the mining industry has reduced the frequency of such incidents to a minimum. History tells us that coal was mined in the early 1700's in Virginia primarily for use by blacksmiths -- most of that mining was done in the Richmond area. It was in those mines that methane was encountered; as workings became more extensive, methane explosions became more frequent. In the early 1800's the first recorded explosion occurred near Richmond, Virginia -- 40 men were killed.

Jan 1, 1985

By Jack E. Fraley, Robert E. Simpson

INTRODUCTION Spokane Mining Research Center (BuMines) is researching sealants for underground coal mines to: 1. Reduce sloughing of shale roofs. 2. Reduce sloughing of coal ribs. 3. Seal block stoppings against air losses. 4. Construct stoppings by spraying over jute cloth or metal lath. 5. Render incombustible in-place polyurethane foam. Originally the work was directed towards reducing sloughing of shale roofs. Many underground coal mines have shale directly over the coal which weathers severely after exposure to the mine atmosphere. Lab investigations(l, 2, 3, 4) have shown that many shales separate into layers when immersed in water or stored in a high relative humidity environment. Upon drying or after removal from high humidity, the shales continue to separate. Underground coal mines become wet in the warmer months from condensation of the ventilating air. Conversely, the mines become dry in the cooler months from evaporation. The mines experience severe shale break-up during the summer and much less break-up during the winter. Figs. 1, 2 and 3 show weathered shale roofs. in underground coal mines. Fig. 4 shows fallen shale on the entry floor. Sealing the shale reduces this sloughing problem.

Jan 1, 1974

Provide coal mine shafts/slopes with an optimum coal mine shaft fire and smoke protection system composed of reasonably-priced, reliable hardware. Approach Accident and injury data indicate that a relatively low percentage (5%) of underground coal mine fires occur in shafts or slopes. Nevertheless, shaft or slope fires are extremely serious because they block critical escape routes for miners. That also can happen when combustion products resulting from fires in other mine areas contaminate shahs and slopes. Seeking the optimum configuration for a shaft/slope fire and smoke protection systems, the Bureau of Mines gathered data on the performance of existing fire detection devices and signal telemetry systems In several mines, and analyzed the generic protection needs of the U.S. underground coal mining industry. The optimum system developed by the Bureau provided an adequate number of detectors, a wide area of coverage, and an extensive data acquisition, analysis, display, and storage capability. This system. recommended for fabrication and in-mine testing, consisted of a microcomputer-controlled master panel located in the test mine's slope hoist room, and four remote units. Two of the remote units were placed on the surface atop upcast ventilation shafts, a third was situated underground near the slope bottom, and a fourth was installed at the slope top in intake air.

Jan 1, 1986

By James A. Pendleton

The Legislature of the State of Colorado adopted House Bill 1223, "The Colorado Surface Coal Mining Reclamation Act" (The State Act), in 1979. This Act provided for the creation of a state regulatory program as accommodated within Public Law 95-87, "The Surface Mining Control and Reclamation Act of 1977" (SMCRA). Section 34-33-121(2)(a) of the Colorado Revised Statutes (CRS) and Section 516(b) of Public Law 95-87, identically require the underground coal mine operator to "Adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mined stability, and maintain the value and reasonably foreseeable use of such surface lands, except in those instances where the mining technology used requires planned subsidence in a predictable and controlled manner..." On July 23, 1980, the Colorado Mined Land Reclamation Board adopted regulations to administer and enforce the State Act. Amendments to the Rules, including the subsidence regulations were adopted by the Board in August of 1981. These regulations require the prediction, monitoring and mitigation of "material damage" caused by subsidence.

Jan 1, 1985

By Keith A. Heasley

Historically, the surface subsidence over underground coal mines has been predicted using empirical profile or influence functions which have little or no connection to the actual mechanics of the subsidence. Without a mechanistic basis, establishing the exact site-specific parameters to use in these empirical methods has been problematic. A practical subsidence predictive method based on mechanics has the appealing capability of allowing the determination of site-specific parameters from fundamental properties of the overburden with minimal field calibration work. This paper presents several case studies where a mechanics-based, boundary-element program is used to back-calculate the surface subsidence associated with various panels at several Northern Appalachian coal mines. The program used in this case study is called LAMODEL, and it incorporates a frictionless, laminated overburden into a general purpose displacement-discontinuity code primarily designed for calculating the stresses and displacements in coal mines or other thin scam or vein type deposits. In this paper, the program is used to calculate both the underground convergence and the resulting surface subsidence at five longwall panels and a room-and-pillar section. The fitted subsidence from the model is compared with the field measurements and analyzed. The results from the case studies in this paper demonstrate that the laminated model with calibrated properties can easily provide moderately accurate subsidence predictions and is fairly flexible for fitting measured subsidence. However, additional subsidence predictive case studies arc recommended in order to ultimately evaluate the potential of the laminated overburden model for practical subsidence prediction

Jan 1, 1999

By Joseph B. de Hart

Two papers recently published on the subject of mine ventilation: "The Theory of Ventilation," by Douglas Hay. and "The True Effect of Natural Ventilation in Deep Mines," by Robert Clive, form the first and second reports respectively of the committee on the Ventilation of Mines appointed by the Midland Institute of Mining Engineers. The purpose of the present paper is to draw attention to these two papers and the discussion thereon. The theory of ventilation as taught in our schools is based on Atkinson's formula, which is a variation of Chezy's formula for the flow of water in pipes. The formula depends on two assumptions : 1. That air is an incompressible fluid within the limits ordinarily encountered, and; 2. That the pressure required to produce ventilation varies as the square of the rate of flow. The Atkinson formula has been assumed to hold good over the entire range of conditions met with in mines.

Jan 1, 1924

By M Parcell

"Ventilation risks in an underground mine have essentially remained the same for centuries, yet theevidence suggests that there are many coal mines that have failed to adequately control these risks.The conduit for the knowledge learned by previous generations exists in the mining legislation. In an ideal world, mines would not need legislation to tell them what to do; they would resolve the risks to an acceptable level so as to protect the safety of persons in the mines based on the acquired knowledge. There will be some who have been personally aff ected by a mining disaster but for the majority they will be remembered as a vague recollection of an event from long ago. The mining legislation is the repository for the knowledge and outcomes from inquiries of past disasters. The challenge for the current generation, and the generations to come is to appreciate the legislation that exists, so as to not ælearn the hard wayÆ. In reviewing most disasters there is comment or discussion on the adequacy of the legislation, which ultimately results in some amendment to the law. For each person, there is an increasing responsibility to ensure that the same mistakes are not repeated. Understanding the legislation, its history and its purpose is the fi rst step in ensuring thatventilation risks are eff ectively managed. Failing to do this will be disastrous. This paper discussesthe relevance, importance and potential pitfalls of coal mine ventilation regulation."

Jun 1, 2012