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The Mine Safety and Health Administration (MSHA) defines an independent contractor as "any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine." Contractors that perform specific types of work are required to report the number of employees who perform work at coal mines and at noncoal mines.

Feb 1, 2005

By N. S. Dalal, W. Irr, X. Shi, V. Vallyathan

"Inhalation of crystalline silica is associated with a biphasic biologic response of acute cell injury and chronic pulmonary fibrosis. Dust induced cell membrane injury leading to the release of lysosomal enzymes and cell death has been implicated as the initial important biologic event triggering the fibrosis. However, it ls also possible other biologic reactions could alternatively, or in addition to these enzyme related cytotoxicity reactions, alter the normal functioning of cells. It is well known that phagocytic activation results in the production of oxygen radicals which are highly cytotoxic to cells. In healthy - lung, protection against the toxic effects of the normal balanced ·biologic reactions are provided by a number of defen1e systems including antioxidants. In disease or condition of overproduction of oxygen radicals, biochemical protection may be overwhelmed with resultant cellular injury.Our recent observations have shown that reactive oxygen radicals (ROR) are generated during grinding of crystalline silica. We hypothesized that these newly generated RORs may cause cell injury, lipid peroxidation, or even damage to macromolecules such as DHA. Biochemical aberrations caused by the inhalation of crystalline silica with ROR at occupational settings might overwhelm cellular and antioxidant defense systems of the lung leading to injury and subsequent fibrosis.To test this hypothesis, we have investigated the generation and decay of ROR produced by crystalline silica using electron spin resonance (ESR) and investigated its toxicity with conventional biologic tests at various time intervals after grinding. We also studied the decay of these newly generated RORs in buffer and the effect of antioxidants and scavengers in the abolition of cellular damages."

Jan 1, 1989

By John Gross

"Introduction.Southern Illinois and Kentucky are credited with approximately 90% of the fluorspar production of the United States. A small amount of high-grade acid, spar is obtained from the ore by band sorting; the greater part, however, is recovered by jigs and tables as gravel spar containing approximately 85% calcium fluoride. In the jigging and tabling operations, galena is recovered, and enough silica and calcite are removed to raise the calcium fluoride content of the gravel spar to 85%. However, the removal of silica and calcite results in a large loss of spar. With increasing depth in the mines, zinc sulphide, sphalerite, is encountered in increasing quantity and the removal of this has become a serious problem. While the sphalerite can be fairly well removed from the spar by present milling methods, a marketable zinc concentrate can not be made. The experiments described below were made on fluorspar ore from Southern Illinois, by the mining experiment station of the U. S. Bureau of Mines, at Rolla, Mo., in cooperation with the Missouri School of Mines and Metallurgy.The ore tested contained. 7.3% lead, 27.9% zinc, 35.7% calcium fluoride, 9.5% silica and 4.7%. calcite.Tests and Results. In some preliminary tests it was noticed that a portion of the finely crushed ore adhered strongly to the sample pans, and upon investigation it was found that the adhering material was practically clean spar. By utilizing this property of adhesion 46.8% of the spar was recovered as a product containing 98.3% calcium fluoride. This suggested the possibility of using electrostatic separation."

Jul 1, 1921

By K. Rubow, Z. Zhlqun, V. Marple

A theoretical technique has been developed and verified experimentally for determining the aerodynamic diameter of irregular shaped particles. The aerodynamic diameter of a particle is a very important property in determining where that particle deposits in the respiratory tract. Many instruments, such as impactors and cyclones, will determine the aerodynamic size distributions of aerosol particles but few analyze the particles individually. The theoretical approach of our technique is to solve, by use of high speed computers, the three dimensional Navier-Stokes equations to obtain the flow field around an irregular shaped particle of any contour. The computer program will then determine the drag on the particle, and thus the aerodynamic diameter of the particle can be calculated. The experimental approach has been to pass the particles through a centrifuge and collect the particles upon a collection foil. The position of a particle on the foil is an indication of its aerodynamic diameter. These particles were then shadowed in two orthogonal directions and inspected under an SEM. The top view of the particle in the SEM plus the views of the two orthogonal shadows allows one to determine the three dimensional shape of the particle. Studies have been performed on silica, coal and talc particles with aerodynamic diameters in the 1 to 4 um size range. The three dimensional shape, as is determined from SEM analysis was used in the theoretical computer program and the results compared. It was found that in most 'cases the agreement between the experimentally and theoretically determined aerodynamic diameters was within 5%.

Jan 1, 1988

By C. L. Wright

In 1904 the Government began a series of fuel-testing investiga- tions at its fuel-testing plant at St. Louis, Mo. These investigations, which were placed under the supervision of the United States Geo- logical Survey, included chemical analyses, steaming tests, gas- producer tests, briquetting tests, coking tests, and washing tests of samples collected from the various coal fields of the country. The specific purpose of the investigations was to analyze and test the coals and lignites in the United States, in order to deternime their fuel values and the most efficient methods of utilizing them for different purposes. Part of the fuel-testing plant, including the briquetting equipment, was moved to Norfolk, Va., in 1907, and the fuel-testing investiga- tions were made one of the divisions of the technologic branch of the Geological Survey. In 1908, after the close of the Jamestown Exposition, most of the fuel-testing equipment was removed to its present location at the Pittsburgh experiment station, Fortieth and Butler Streets, Pittsburgh, Pa. In 1910, an act of Congress, effective July 1, established the Bureau of Mines in the Department of the Interior and authorized the transfer to this bureau of the fuel-testing investigations that had been carried on by the technologic branch. Bulletins presenting the results of various inquiries and investiga- tions relating to briquetting have been published by the Geological Survey and the Bureau of Mines. As the supply of some of these bulletins is exhausted, the Bureau of Mines has decided, instead of reprinting them, to publish the more important facts they contain

Jan 1, 1913

By D. Harrington

Examination of numberous disasters , such as fires or explosions , and the evidence at coroner's inquests following such disasters in several States , have shown the writer how frequently men in charge of the operation and safety of mines have forgotten, or have failed to learn , details of safe mining practices , After securing a position of trust as superintendent , or a certificate of competency to act as shot -firer , fire boss , or mine foreman, some men seem to have felt it unnecessary to keep safety principles in mind , or to keep abreast of current progress in safety ; they have concentrated on getting out maximum tonnage at minimum cost . • In coroner's inquests , the testimony after disasters has shown that firebosses , foreman , and coal -mine superintendents are noticeably lacking in knowledge of the provisions of the State mining law relating to fans or doors , frequency of crosscuts , nature of stoppings necessary , electrical equipment , records of daily mine examinations , quantity of air required , or splitting and overcasting .

Jul 1, 1922

By Lloyd A. Morley, Robert Stefanko

Table

Jan 1, 1974

To concentrate coarse mica particles using a dry beneficiation technique. Approach Concentrate coarse, II berated mica particles using a Bureau-designed system of crushers, screens, and a two-stage zigzag air classifier. How It Works Because mica has a flat plate-like crystalline structure, mica particles are significantly lighter than blocky gangue particles of the same size fraction. Thus an air classification technique can separate the flat, light mica particles from the heavier gangue particles. The ore, which Is first run through a standard jaw crusher, a roll crusher, and a hammer mill to liberate the mica, enters the rougher Zig-zag section through a rotating air lock. See photograph and diagram of a 2-stage air classifier. Airflow through the classifier can be varied according to the size of the particles being separated. The gangue material falls through the airstream of the rougher zigzag section and is discarded as tailings. The mica flakes are carried by the air-stream to the cyclone shown on the right side of the diagram, where they are collected. This rougher mica concentrate is fed to the cleaner zigzag section through another rotating air lock. The mica particles are again carried by the airstream but they are now collected In the cyclone on the left side. The cleaner concentrate leaves the left-side cyclone through a third rotating air lock and is rescreened to remove under-size material missed by the first screening. The final product of this pneumatic process is generally a high-grade mica concentrate. A generalized flow diagram for the pneumatic concentration method Is shown In the second diagram.

Jan 1, 1981

By Walter O. Snelling, C. G. Storm

Although descriptions of the methods of analysis of explosives are to be found in many books on explosives, and in works on engineer- ing chemistry or chemical analysis, most of these descriptions are incomplete and lacking in details. The methods of analysis employed in the laboratories of most explosives factories are frequently treated as trade secrets, and very little information is published from such laboratories. This bulletin outlines the methods of analysis that are used by the Bureau of Mines in the examination of certain classes of explo- sives. The present form of most of these methods has been worked out in the bureau's explosives laboratory. The methods employed by Prof. C. E. Munroe were taken as a basis, and were elaborated to meet the demands incident to the treatment of complicated mix- tures and to the development of the explosives art. A subsequent bulletin will discuss the methods of analysis of "permissible" explosives, many of the latter being of decidedly complicated char- acter and requiring special treatment. This bulletin presents the methods of analysis of "ordinary" dynamite, and the ammonia, gelatin, low-freezing, and granular dynamites, and the common grades of black gunpowder and black blasting powder. The bulletin is published by the bureau for the information of all persons inter- ested in explosives and their safe and efficient use in mining work. As the term "ordinary" dynamite, though much used, has no conventional meaning, and may be used to cover a wide variety of compositions of matter, it may be noted that the standard dynamite used at the Pittsburgh testing station is a good example of the "ordinary" dynamite known in this country. This testing station dynamite has the following composition:

Jan 1, 1913

By Launa G. Mallett, Robert H. Peters, Barbara Fotta

Due to variations in the thickness of U.S. coal seams, there is great variability in the height of the roof where underground miners work. Restrictions imposed by low seam heights have important safety consequences. As the height of their workplace decreases, miners must stoop, duck walk, or crawl, and their vision, posture, and mobility become increasingly restricted. Low seam height also places important restrictions on the design of mobile equipment and other mining machinery. Using the employment and injury data reported to the Mine Safety and Health Administration (MSHA) from 1990 to 19% small underground bituminous coal mines with less than 50 employees were stratified by average coal seam height according to the following categories: low (? 42"), medium (43"60N), and high (? 61"). Injury rates for both nonfatal days lost and fatality cases were examined by seam height and leading type of injury incidents. The leading types of Incidents associated with fatalities were roof falls and powered haulage equipment. In comparison to high-seam mines, miners working in low or medium seams are at higher risk of being killed by powered haulage equipment, roof bolting machines, and falls of unsupported roof. The leading types of incidents associated with nonfatal injuries were handling materials and powered haulage. As mining height decreases, miners are at increasingly higher risk of having a nonfatal injury from incidents involving roof bolting machines, load-haul-dump equipment, personnel carriers, and powered haulage conveyors. As mining height increases, miners are at increasingly higher risk of having a nonfatal injury from slips and falls and incidents involving shuttle cars and roof and rib falls. Knee injuries are a particularly severe problem in low- seam mines. The rate of injuries to miners while crawling or kneeling is 10 times higher in low seams than in high seams

By John A. Davis, Karl L. Kithil

The principal deposits of carnotite, so far as now known, are con- fined to a well-defined area lying in the southwestern part of Colo- rado and the southeastern part of Utah (see Pl. I). Approxi- mately, this area is bounded as follows: On the east by a line ex- tending from a few miles east of the southwest corner of the State of Colorado, to a point about 6 miles west of Naturita, thence di- rectly north to the San Miguel River, thence along the course of this river and the Dolores River to Mesa Creek, thence toward the head- waters of Mesa, Blue, and Calamity Creeks on the south side of the Uncompahgre Mountains; on the north by a line extending from the last-named point westerly to the San Rafael Swell near Green River, Utah; on the west by a line extending from San Rafael Swell to the Henry Mountains, and on the south by a line extending from the Henry Mountains toward the southeast corner of the State of Utah. This area includes the main districts wherein carnotite has been found, claims have been located, and the ore produced. There are of course, extensive tracts within this area which do not contain carnotite in paying quantities. In places the carnotite beds have been entirely eroded or are not present, or lie so deep that mining is not practicable. The main deposits of carnotite within the area lie in different districts which in Colorado are as follows: Summit and Bush Canyons in Dolores and San Miguel Counties; McIntyre, Gypsum Valley, and Bull Canyon districts; the Paradox Valley, La Sal Creek, Roc Creek, Long Park, Hieroglyphic, Saucer Basin, and Hydraulic districts in Montrose County; Mesa, Blue, and Calamity Canyon districts and the Gateway area in Mesa County. The included dis- tricts in Utah are as follows: The Green River and San Rafael Swell district in Garfield County; the Thompson deposits in Grand County; the Dry Valley, Yellow Wash, and Lisbon Valley districts in San Juan County; the district around the Henry Mountains in Garfield County; and the deposits recently reported in Montezuma Canyon (south of Monticello) in San Juan County. Outside of the area described there are scattered deposits north of the Denver & Rio Grande Railroad at Coal Creek, near Meeker, Rio Blanco County; along Skull Creek and Red Wash, near Rangely, Routt County; on Horse Mountain, near Eagle, Eagle County, and in South Park, near Garos, in Park County, Colo. The claims leased from the Crucible Steel Mining & Milling Co. by the National Radium Institute are situated on the north side of East Paradox Valley, in the Long Park and Hydraulic districts. The National Radium Institute has mined no ore except from its leased claims in the Long Park district. For information regarding the general geology of the region, the probable origin of the ores, and descriptions of other carnotite deposits, the reader is referred to the literature on these subjects. The carnotite of the area described is deposited in a light-colored, cross-bedded sandstone that lies almost horizontal between the La Plata formation below and the Dakota sandstone (conglomerate) above, and is included in the McElmo formation, which is of Jurassic age. Underlying the white sandstone of the La Plata is the Dolores formation, or "Red Beds," which is plainly visible along and just below the rim rocks of the steep canyon walls in many of the carnotite districts. Along such canyons the ore crops out at different places, so that prospecting is comparatively easy. For ore on the benches and on the mesa prospecting is more difficult, especially where the ore lies at some depth and no surface indications are visible. The carnotite deposits are flat, lenticular, and irregular, varying greatly in extent and thickness. The carnotite itself forms incrustations on exposures of the white sandstone, in joints and fractures of the rock, and is deposited around and between individual sand grains, replacing the original cement. The Utah and Colorado carnotite is amorphous, and to the naked eye appears as a very fine yellow pow- der. It is often granular, and as a rule can be readily separated from the individual sand grains.

Jan 1, 1917

By D. J. Parker

Du.ring the past two years a number of oases of successful first-aid treatn . .)nt have been reported by or through the employees of the O. s. Bureau of -anes safety cars and stations. Among such cases are the following: At Benbush, w. Va., a boy or 16 years of age who ba.d just started to work in the mines was trained in first-aid by the crew of Bureau of Mines car 8. The local rr.ine superintendent afterwards reported tba.t a few dS¥s later this boy, Melvin Hollingsworht, found droming in a spring a. baby about three years old who bad wandered away fron.. har.e alone. The boy rescued the baby and perf'oxmed artificial re­suscitation upon it, thu.s saving the child's life. The Schaefer method of resuscitation bad bean ta"Ugbt the boy as a routine art of the regular first-aid course.

May 1, 1922

"Reports are sometimes heard of one ill effects of pneumatic tools on the hands of workmen. In consequence of such reports, Dr. Francis M. Barnes, Jr., M..D. of St. Louis, Missouri, was retained by the operators to make an investigation of conditions in the Bedford, Indiana, region, and the result of this investigation was published the Journal of the Missouri State Medical Association, Volume 16, February 1919. A brief review of this report may be of interest to all users of pneumatic tools, or operators of plants where such tools are employed.The investigation was made during December 1917, and involved an examination of general working conditions, and a careful physical examination of stoneworkers who had long used pneumatic tools. As the Bedford district is the most important structural limestone producing center in the country, the results of this investigation may be regarded as fairly conclusive as to the general effect of pneumatic tools on limestone workers."

Jan 1, 1920

By George D. Dub, FREDERICK G. MOSES

The Bureau of Mines, in connection with the investigations of war minerals it conducted, examined the graphite deposits of this country, studied the methods of mining and preparation used, and sought to devise more efficient methods for the preparation of do- mestic graphite, and to standardize the quality of the product. The graphite investigations covered three general phases, as follows: 1. An examination of the deposits in Alabama and other States, and a survey of the methods of mining and preparation used. In this connection methods of sampling and analysis were noted and ex- periments made to determine a standard method of sampling and a rapid but accurate method of analysis. 2. Experimental work on the concentration and refining of domes- tic crucible graphite to improve the quality of the product and to lessen waste. 3. Experimental work in crucible manufacture to determine the properties of domestic flake and the maximum proportions that might be used without impairing the quality of the crucibles. This work was accompanied by photomicrographic study of crucible structure. In this bulletin are presented the results obtained in the first two phases of the work outlined above. The bulletin is in two parts. The first part describes the methods of mining and milling used, suggests a standard method of sampling finished graphite, and de- scribes a rapid and convenient method of analysis developed at the Pittsburgh station of the Bureau of Mines, to which had been as- signed the analytical and microscopic work. The second part describes experiments on the concentration and milling of graphite, which were made at the Salt Lake City, Utah, station. As soon as the reports incorporated in this bulletin were ready, mimeograph copies were distributed to those persons most interested in order to make the results immediately available. The experimental work on crucible manufacture, assigned to the Columbus, Ohio, station, yielded results which were made known to the industry. Á report on this work will be published later as a separate bulletin.

Jan 1, 1920

By E. J. HOFFMAN, L. A. SCHOLL, J. c. W. FRAZER

The danger from coal dust in mines has been thoroughly demon- strated by experiment, and consequently the study of the inflam- mability of coal dust suspended in air, that is, the readiness with which a cloud of coal dust inflames, is of decided importance to those engaged in coal mining. Much knowledge has been gained from the work done in the large galleries constructed at official and semiofficial stations in this country and abroad, but the study of the coal-dust problem in these galleries requires so much time and is so costly that there is need of a reliable laboratory method for obtaining a classi- fication of the great variety of dusts that occur in mines. The investigation described in this paper was an attempt to devise such a method. It was a preliminary investigation, and work in the same direction is being continued by the Bureau of Mines. As Mr. Frazer has severed his connection with the bureau, it is deemed advisable to publish the results of his study substantially as he prepared them, with little attempt to draw conclusions or to show the bearing of the results on other studies now in progress. The results of these studies and a full discussion of the significance of the laboratory investiga- tions will be published in future reports of the Bureau of Mines. The reader should remember that any laboratory method, since it involves conditions that differ so greatly from those of actual mining, should be thoroughly tested, and the results obtained by it should be confirmed by experiments conducted on a scale simulating mining conditions before final conclusions are drawn. The need of a laboratory method has long been felt, and several investigators have devised apparatus and methods. The work done by Vital, Holtzwart and Von Meyer, Bedson and Widdas, Le Chate- lier, and that of the British Coal Dust Commission is of great interest in this connection. Bureau of Mines Bulletin 20 contains a sum-

Jan 1, 1913

By Herbert M. Wilson

The act (36 Stat., 369) that established the Bureau of Mines in the Department of the Interior defined as part of the bureau's province and duty the making of "diligent investigation of the methods of mining, especially in relation to safety of miners and the appliances best adapted to prevent accidents," and it authorized the bureau from time to time to make such public reports of its work and investiga- tions as the Secretary of the Department of the Interior may direct, with the recommendations of the bureau. The national mine-rescue and first-aid conference was projected in the hope that it would be a factor in increasing safety in the mining industry through the recommendation of better and safer methods of conducting mine-rescue operations, more efficient methods of extend- ing and giving training in the use of artificial-breathing apparatus, and approved and more effective methods of administering first aid to injured miners and of training miners in first-aid work. The bureau feels warranted in publishing the resolutions adopted by the conference as a guide to mine workers and others concerned in obtaining greater safety in mining, and in presenting such extracts from the discussion as indicate the reason for the adoption of any particular method. In issuing this bulletin, however, the bureau does not indorse these resolutions in whole or in part as a final ex- pression of its views regarding the best method or procedure in any case. It does believe, however, that the resolutions furnish an excel- lent starting point from which to develop a standard code of pro- cedure in mine-rescue and first-aid work. It will be noted that in some important cases further information is necessary before any standard procedure can be recommended, par- ticularly as regards types of bandages, methods of resuscitation, the use of stimulants, the cumulative effect of poisonous gases, the diet of men engaged in rescue work, the physiologic effect of the pressure

Jan 1, 1913

By Charles Enzian

This report is issued by the Bureau of Mines as one of a series dealing with methods of increasing safety and efficiency in mining operations. It is intended purely as a preliminary statement of the present development of hydraulic mine filling as conducted in the anthracite region of Pennsylvania. A discussion of different methods, their variations and modifications, as well as their probable extension as a result of amplified tests of the various roof-supporting materials, will be presented in a future bulletin. The history of the development of the anthracite-mining industry, from the time when the Indian tribes in the Wyoming and Lacka- wanna Valleys first discovered the existence of "stone coal," on through subsequent events-the purchase of lands containing enor- mous deposits of coal for insignificant sums of money, the develop- ment of the first mine, the formation of the first company, the build- ing of canals and railroads-up to the present time when the industry has become of such tremendous importance to the prosperity of north- eastern Pennsylvania and of the Nation itself, is intersprinkled with romance, tragedy, and pathos. The great economic lessons to be learned from a study of mining operations in the anthracite region suggest to the person interested in the efficient utilization of natural resources the need of applying such methods as will make possible the conservation to posterity of this invaluable deposit of coal that has resulted from the operation of the processes of nature during probably hundreds of millions of years. It is the opinion of many prominent mining men familiar with mining operations in the United States and abroad that under certain conditions the most practical way of preventing loss of unmined coal in pillars and of protecting surface property from damage by sub- sidence is by filling the workings with refuse material. This bulletin aims to present a general discussion of hydraulic mine filling, its origin, development, and practicability in anthracite mining.

Jan 1, 1913

By Frederick L. Hoffman

Miners' nystagmus is the result of a peculiar form of eyestrain, which often results in impairment of vision and a consequent diminu- tion of the wage-earning capacity of the workman. Historically it has been pointed out by Shufflebotham that "This disease was first recognized by Gillett, of Sheffield, about 1854, although no case was mentioned in medical literature until 1861, when the symptoms were described by De Conde, a Belgian physician. Cases were reported by Pepp Müller as early as 1860, by Von Graefe in 1873, and by Bell Taylor, of Nottingham, and by Nieden in 1874. In this country (England) we are indebted to a very large extent to the observations and writings of the late Simeon Snell and for his pioneer work on this many-sided disease; in France Dransart occupies a similar position." In the treatise on "The Effects of Arts, Trades, and Professions," by C. Turner Thackrah, published in London in 1832, it is stated that- The complexion of the colliers, even after the removal of the dirt, is generally sallow and unhealthy. Their eyes, from the swelling of the lids, appear small, are affected with chronic inflammation and intolerant of full light. * Sickness and vomiting sometimes affect persons at their commencing the employ; and many, after a few years' trial, are obliged, by the injury which their health has sustained, and especially by the weakness of their eyes, to leave the mine. According to Greer, an authority on industrial diseases and acci- dents, miners' nystagmus occurs in 5 per cent of all miners, but it is quite probable that the reference is to European coal miners rather than to men employed in all branches of the mineral industry. According to the same authority, miners' nystagmus "is associated with a twitching of the eyelids and with considerable diminution of the range of movement of the eyes, and is particularly liable to occur in patients whose vision is subnormal owing to errors of refraction, especially astigmatism. It causes much inconvenience to those suf- fering from it and prevents them from following their usual occupa- tion as, owing to the movements of the eyes, everything at which they look appears to be in a state of perpetual motion, and in conse-

Jan 1, 1916

By George H. Ashley

Character The bituminous coals of Pennsylvania range from low volatile to high volatile, but are all low moisture coals The coals are of three types caking of coking, noncaking or splint, and cannel The percentage of volatile matter in all kinds changes from low at the east to high at the west This change is thought to be due to the pies sure and folding to which the coals along with the other rocks have been subjected In the Broad Top field, and in Somerset, Cambric, Clearfield, Centre, and other counties to the northeast, most coals contain from 3 to 5 times as much fixed carbon as volatile matter, the fixed carbon ranging from 67 to 75 per cent, and the volatile mattes from 16 to 24 per cent These coals are classed as lovol coals In the line of counties just west of those listed the coals are of the medium volatile class (midvols) This includes the famous Connellsville coking coal Still farther west, covering most of Washing ton and Westmoreland counties, and the counties to the north of them are high volatile coals of gas coals (hivols) This is discussed in Part I on the geology of the coals of Pennsylvania, where is given in isocaib map Cannel coals ale found in many par is of the bituminous coal field of Pennsylvania, but in particular in Beaver Butler, Armstrong, Indiana, and Clear field counties The cannels of Beaver and Butler. counties are typical high volatile cannels, many of which have been used in times past for oil distillation The cannels of Armstrong and Indiana counties are medium volatile cannels, and while main taming the physical character of cannels, have no more volatile neat ten than the coals around them The cannels of Clearfield County tie low volatile Splint coals of noncakmg coals are not abundant in Pennsylvania. The Sharon coal, formerly mined in Mercer County, was a noncaking or splint or block coal, and was formerly used in the raw state in non smelting Uses STEAM COAL Practically all of the coals of Pennsylvania are steam coals, though many coals in the Commonwealth, because of high ash, are not good steam coals The coal of the Pittsburgh district has long been famous

Jan 1, 1928

By Jeanne A. Zimmer, Charles D. Taylor, Edward D. Thimons

On a continuous miner coal face methane concentrations are affected by the quantity of fresh intake air reaching the face. When mining the box cut on a 12.2-m (40-ft) two-pass extended cut face, the continuous miner is always at the point of deepest penetration, and operation of the machine-mounted dust scrubber and water spray system improve the flow of fresh air to the end of the box cut. However, when the continuous miner leaves the box cut to begin cutting the 40-ft slab, little is known about how much ventilation air reaches the end of the box cut. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health conducted a full-scale study to answer this question. Tests were run to determine how much ventilation air reaches the end of the box cut with the continuous miner at three locations in the 40-fttwo-pass extended cut mining sequence; at the end of the 40-ft box cut, at the start of the 40-ft slab cut, and 6.1 m (20 ft) into the slab cut. During these tests, methane gas was uniformly released at the end of the 40-ft box cut. Methane concentrations measured0.3 m (1 ft) from the roof and face of the box cut were used to estimate face airflow quantities. Fresh air flow rates of 1.89and 4.72 m/sec (4,000 and 10.000 cfm), scrubber flow rates of 0, 4,000 and 10,000 cfm, water spray pressures of 0 and3827 kPa (0 and 120 psi), and a blowing curtain setback position of 15.2m (50 ft) were used during these tests. To improve ventilation to the end of the 40-ft box cut when the continuous miner was starting the 40-ft slab cut and 20 ft into the slab cut, the blowing curtain was advanced from its 50-ft setback to locations 40-ft and then 8.5 m (28 ft) from the face. KEYWORDS: Face ventilation, Extended cut, Methane, Box cut, Continuous miner, Scrubber