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The Bureau of Mines believes that all coal mines are potentially gassy; for the purpose of administration in the prevention of explosions and fires, the Bureau recommends: That any coal mine wherein methane or other combustible gas can be detected in amounts as much as 0.27 of 1 percent or more by frequent systematic searches shall be classified as a gassy mine. Permissible methane-indicating detectors such as are given in I.C. 7110 or subsequent lists of Bureau approved methane-indicating detectors, or conventional methods of sampling and analysis of required accuracy may be used. The concentration referred to in the decision is percent by volume.

Jan 1, 1941

By Allen Q. Howard

An approximate solution to the electromagnetic boundary value problem consisting of a horizontal cylindrical conductor buried in a lossy half-space and excited by an arbitrarily oriented magnetic dipole is found using an iterative perturbation technique in a double Fourier transform space. This model is used to gain insight into the anomalous fields due to strong scatterers such as pipes or tracks which would be in close proximity to an EM mine rescue operation. The novel, three-dimensional aspect of the problem (i.e., the source) imposes the complexity that the current in the cylinder is not uniform. The field expressions are ideally suited to evaluation using FFT algorithm.

Jan 1, 1973

Founded in 1994 through a joint effort between Underwriters Laboratories Inc. (UL), the U.S. Consumer Product Safety Commission (CPSC) and the National Electrical Manufacturers Association (NEMA), the Electrical Safety Foundation International (ESFI) is North America?s only non-profit organization dedicated exclusively to promoting electrical safety in the home, school and workplace. ESFI is a 501(c)(3) organization funded by electrical manufacturers and distributors, independent testing laboratories, utilities, safety and consumer groups, and trade and labor associations. ESFI sponsors National Electrical Safety Month each May, and engages in public education campaigns and proactive media relations to help reduce property damage, personal injury and death due to electrical accidents. The Foundation does not engage in code or standard writing or lobbying and does not solicit individuals.

Jan 1, 2004

By Charles L. Kimbell

In overview, the world's mineral industry in 1989 registered gains over its 1988 performance, but these gains were by no means as pronounced as had been those of 1988. The traditional statistical measures of mineral industry performance, namely production, trade, and consumption levels, reflected significant growth in most industry sectors from crude material extraction through the gamut of down- stream processing. Growth in market economy countries generally exceeded growth in the centrally planned economy countries as a result of a variety of causes that will be covered subsequently, but even among the centrally planned countries there were some upturns. In contrast to these measures of the soundness of the industry, the situation for nonfuel mineral and metal prices was less satisfactory than in 1988, and low crude oil prices continued as a problem for the all-important petroleum sector, despite some gains during the year. The oil price situation mitigated against price increases for competitive fuels. Although this was unfavorable for fuel producers, it remained advantageous to consumers, including nonfuel mineral producers, processors, and transporters. Thus it cannot be viewed as a negative factor for the whole of the global mineral industry. Global crude mineral output value was estimated at nearly $1,420 billion in current dollars, an increase of 9% over the 1988 level, and an increase in current dollar terms for the seventh consecutive year. Measured in terms of constant dollars, however, adjusting for inflation, the increase was only 4.7% compared with the 1988 level. Despite the prolonged growth trend, the 1989 crude mineral output value level was still 3.2% below the record high set in 1980, which was $1,467 billion in terms of 1989 dollars.

Jan 1, 1992

At the present time many coal preparation plants handle coal-clay wastes in one of two methods. In one method, the waste is processed in a thickener, followed by further dewatering through filtration, and subsequent blending with coarse waste refuse from the preparation plant. The resulting mixture is then disposed by stacking it in available storage locations. The coal-clay waste is often reslurried by rain or water from other sources, causing a potentially unsafe situation such as mud flows. The other method often used requires thickening and impoundment of the thickened slurry behind earthen dams which poses safety risks if structural failure of the dams occurs. To overcome these two problems, a flocculation method was developed which produces a stable agglomerated material resistant to reslurrying. How It Works The new method involves treating coal-clay waste with lime to raise the pH and flocculating the slurry with a nontoxic polymer of polyethylene oxide. The resulting floes are dewatered on a static screen and agglomerated. For extremely fine waste, further dewatering of the material is accomplished on a rotary trammel screen. The dewatered material may be ponded or mixed with coarse waste from the preparation plant to produce a stable mixture that can be stacked.

Jan 1, 1985

By B. W. Madsen

Bureau of Mines research to recover arsenic from mining industry waste material and process streams is reported. Batch and column approaches were investigated for adsorbing arsenic from acid leach solutions and ion-exchange eluate solutions with hydrated titanium dioxide granules. A method for producing hydrated titanium dioxide granules was devised to provide material suitable for use in a packed adsorption tower. Selective adsorption of arsenic from acidic leach solutions was achieved. The loading capacity of arsenic on the granules was 14 wt-pct when synthetic solutions were used, but lower when actual leach solutions were used. Other elements in the leach solution were Zn, Cd, and In. The granules were used in an attempt to lower the arsenic content in a solution containing 0.95 g/l W and 0.027 g/l As from a process devised by the Bureau of Mines to treat Searles Lake brine. The arsenic content was lowered to less than 0.001 g/l, but unacceptable amounts of tungsten also were adsorbed by the granules. Adsorbed tungsten was partially stripped with pH 11.5 NaOH, and both tungsten and arsenic were completely stripped with 5M NaOH solution. Repeated loading and stripping of the granules had no effect on the loading capacity for arsenic.

Jan 1, 1983

By B. W. Jong

The U.S. Bureau of Mines investigated anhydrous chlorination and caustic-acid leaching processes to recover Ni, Co, Mo, and W from waste hydroprocessing catalysts. In batch laboratory-scale equipment, the chlorination process extracted 61 to 99 pet of the metals. Final recovery was 65 to 99 pct. The caustic-acid leaching process extracted 81 to 98 pct of the metals. Final recovery was 36 to 99 pct. Chlorination processing included roasting, chlorination, hydrolysis of metal chlorides for recovering Mo or W, water leaching of Ni or Co from the spent charge, purification, and solvent extraction or precipitation of Ni or Co from the purified solutions. Caustic-acid leach processing included NaOH leaching, solvent extraction of Mo or W from the NaOH leach liquor, H2S04 leaching of the NaOH leach residue, purification, and solvent extraction or precipitation of Ni or Co from the purified solution. The estimated fixed capital cost for a commercial-scale plant processing 39,000 Ibid of waste Ni-Mo-AI catalyst was $8 million for the chlorination process and $9.6 million for the caustic-acid leaching process. The estimated operating cost was about $0.20 and $0.40 per pound of the waste catalyst, respectively, for the two processes.

Jan 1, 1989

By David F. Smith, F. A. Hartgen

"Incidental to a cooperative investigation with the Carnegie Institute of Technology and the International Combustion Engineering Corporation on the burning characteristics of a powdered coal and the powdered semi-coke therefrom, the U. S. Bureau of :alas has determined the relative temperatures at which rapid self-heating occurs in these two fuels. Determinations were made on various screen sizes of the two fuels. Chemical analyses on different sizes were made in the bureau's Coal Analysis Laboratory, of which H. M. Cooper is in charge. The true densities were determined b the method given in Bureau of Mines Technical Paper 8.4The apparatus used in the determination of the temperatures for rapid self-heating was similar to that used by Wheeler A 10-gram sample of the fuel was placed upon a screen in a glass tube enclosed in a vertical electric furnace. The tube was surrounded with sand. One thermocouple -as imbedded in the sand and another in the fuel. Measurements of the temperatures were obtained at regular intervals with a recording potentiometer, as the furnace temperature was uniformly raised. Dry air was passed down through the fuel samples at a uniform rate of 123 c. c. per minute; the temperature of the air was substantially that of the furnace."

Oct 1, 1929

By Robert C. Hickman

"INTRODUCTION The Cline mine has been worked intermittently for copper and gold since 1895. Scheelite has recently been detected with the aid of a ""Mineralite"" on the old waste dumps of the mine. Four diamond-drill holes were drilled by the Bureau of Mines from August 13 to September 25, 1946. Results of this drilling showed the vein to pinch at depth and to carry no mineralization of economic importance.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigation work, and prepares the final report. The Metallurgical Branch, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The project was under the general supervision of Mitchell H. Kline, chief, Raleigh Division, Mining Branch.Acknowledgment is due Dr. Jasper L. Stuckey, State geologist, for logging the drill core and to J. B. Zadra and associates, Metallurgical Branch, College Park, Md., for analytical determinations."

Feb 1, 1948

The twelve latexes listed in Table XI penetrated A horizon soil as shown by elution through a laboratory soil column and gave good sealing efficiency. See details in Table XII. High elution through laboratory soil columns of 4 to 6 inches depth is desirable because it predicts penetration of latex to a greater depth in the field. No definite correlation was evident between penetrating ability and particle size, surface tension, or pH. Most of the materials, however, were characterized by low surface tensions in the 36 to 53 dynes/cm range while particle sizes were usually in the intermediate range of about 1500 to 2500 Å. Naugatex J-3471 (a highly crosslinked styrene-butadiene copolymer) was the most promising of this group for stability, penetrating ability; and sealant efficiency. It also showed utility with [B] profile soil. Many of the other latexes tested in this investigation showed good sealing efficiency but were judged unsatisfactory because they gave low penetration or formed surface films with & horizon top soil. In general, latexes containing cationic surfactants were not satisfactory because they formed a heavy surface film. This is due to neutralization of the positive latex charge by the negatively charged soil particles.

Jan 1, 1972

By L. C. IlsLey, H. B. Freeman

In connection with the approval of coal-cutting machines for service in gaseous mines , the engineers of the Bureau of Mines have been somewhat concerned as to the type of trailing cables that could safely be used on permissible outfits . While no final action has been taken on this question ( tentative approvals having been granted pending investigations ) , the Bureau has been endeavoring to collect data and information on this question which would permit a fair , yet safe , ruling to be made . For this purpose cooperative arrangements were made with three coal companies to visit certain of their mines , making inspections inside the mines to observe the cables and cutting machines in operation . In all , twenty mines were visited . A questionnaire covering the operations of trailing cables was filled out at each of these mines . In a few instances no personal inspection was made , the information being supplied by mine officials after conferences with the Bureau's engineer . At other mines the information given by mine officials was supplemented by personal observation inside the mines , usually at a time when the cutting machines were in operation .

Jul 1, 1923

By P. L. Swanson, S. Billington, F. M. Boler, L. H. Estey

Stabiity analyses of fractured and faulted rock masses require delineation of the position, extent, and orientation of geologic discontinuities. The size of the smallest active discontinuity that may potentially be resolved using the spatial distribution of microseismic event locations is limited by the accuracy and precision of the location methods. At a hard-rock mine in the Coeur D'Alene mining district of northern Idaho, two data sets consisting of calibration blast signals from a known source site and origin time and microseismic event signals were recorded using a stope-wide accelerometer array. These seismic signals are used to quantify various sources of error in event location. Five factors influencing source location errors are examined in this US. Bureau of Mines study: (1) biases of the numerical source location techniques, (2) receiver array geometries, (3) uncertainties in receiver positions, (4) errors in picking arrival times, and (5) uncertainties in seismic velocity structure, including the effect of mine openings. In addition, synthetic data (accelerometer positions, travel-time picks and wave velocity) are used to determine the effect of known systematic and random errors on source location calculations. It is shown that the commonly accepted association of minimum travel-time residuals with the best location solution does not necessarily hold true when there is a systematic error in seismic velocity. Recommendations are made for increasing the accuracy and precision of locations of microseismic events detected under similar field conditions.

Jan 1, 1992

By Ralph L. Brown

The chemical properties of the unsaturated members of the aliphatic series of hydrocarbons are such as to render them " made to order" starting points or basic . materials for the synthesis of hundreds of important organic chemicals . The tremendous quantities of these unsaturated compounds that are being produced daily in the various coal carbonization and oil refining processes , and which at present have little value other than that of fuel , render a survey of the identity and ex- tent of occurrence of these compounds important from the viewpoint of economic utilization and resource conservation The increased need of liquid fuel and the relatively early exhaustion of petroleum resources will eventually require every utilization of liquid fuel products obtainable directly or indirectly from coal . Accordingly , the Bureau of Mines took advantage of an opportunity for examining the gaseous unsaturated hydrocarbons found in the gas obtained when a mixture of water- Collection of the material gas tar and coal is distilled in a gas-making retort . for examination was made possible through the courtesy of the Trent Process Corporation , Washington , D.C. , which was at that time carrying on at the Georgetown Gas Works , distillation of " amal gams " prepared from various coals and oils by the Trent process for cleaning coals . Kanawha gas coal ( 70%) and water gas tar ( 30 % ) from the Washington Gas Light plant were used in the " amal gam" being distilled at that time . The results obtained in this examination are presented here .

Feb 2, 1922

To improve electrical safety and lengthen light bulb life on trolley haulageways. Approach A resistor inserted in series with each pair of light bulbs, decreases the voltage applied to the bulbs and eliminates heavy arcing when voltages rise. How It Works Under certain conditions, incandescent light bulbs connected directly to a 300-volt d-c trolley wire can be a hazard, particularly during weekends when electrical equipment is nut in use. When little electrical power is being used, the voltage (on the trolley lines and at the substation) can rise to a value which will destroy the bulb filament, cause arcing, and damage the bulb holder. In one coal mine where light bulbs in certain locations fre¬quently failed, the problem was overcome by inserting a 100-ohm, 50-watt resistor in series with each pair of light bulbs. The light bulbs are rated at 300-volts and 100-watts. Figure 1 shows the light bulbs and resistor circuit. This resistance was added in order to reduce the current through a short circuited bulb holder, from several hundred amperes to a much safer value of 3 amperes. However, the resistor in series with each pair of light bulbs, also reduces the voltage across the lighted bulbs to approximately 240 volts during periods when the trolley line voltage is up to 300 volts. With this arrangement, no light bulb failures occurred over a 6-month period. The resulting light reduction has not been objectionable.

Jan 1, 1976

By Roberta L. Hudak, Ellsworth R. Spencer, Eric R. Bauer, Adam K. Smith

The National Institute for Occupational Safety and Health (NIOSH) is conducting research with the objective of preventing hearing loss in the mining industry. Longwall mining is one sector that has received considerable attention. Studies involving the monitoring of worker noise exposures, characterizing equipment sound levels and dominant noise sources, evaluating engineering noise controls, analyzing hearing protection device (HPD) effectiveness, and testing of improved sound level monitoring techniques specifically for longwall mining systems, are being conducted. The research efforts revealed that stageloader operators are the most exposed longwall workers, with the discharge end being the noisiest location along the stageloader. In addition, the studies have shown that using stationary dosimeters, coupled with observational data of the cutting cycle and worker habits, has the potential for improved monitoring of the effectiveness of engineering noise controls. To address the ineffective use of soft foam earplugs, a simplified 3-step method was developed for inserting soft foam earplugs. Results indicate a 9 dB greater attenuation after training subjects on the 3-step method. Finally, muff type HPDs are being evaluated for effects of speech intelligibility in noise. The combined results of these studies illustrates that much can and has been done to prevent noise-induced hearing loss (NIHL) in the mining industry, especially with respect to longwall mining workers. This paper presents an overview of ongoing studies, a progress report of results, and the implications for reducing worker noise exposures and preventing NIHL in longwall mining workers.

By C. P. Lazzara, R. A. Franks, G. F. Friel, J. C. Edwards, J. J. Opferman

A fire detection research program conducted at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Research Laboratory (PRL) recently demonstrated the advantage of multiple fire sensors for early fire detec¬tion and nuisance alarm discrimination in underground coal mines. As an example, research has shown that an appropriate combination of smoke, CO, and metal oxide semiconductor (MOS) sensors has the capa¬bility to detect a smoldering conveyor belt fire which produces low visibility due to smoke, but CO concentrations too low for an early fire alarm. Such a sensor combina¬tion has the additional advantage of being able to distinguish a nuisance alarm event such as those produced by diesel engines or acetylene torches from mine fire products¬-of-combustion (POC) produced by a real tire. Research has also shown that the problem of hydrogen (H2) gas cross-interference with chemical CO sensors at battery-charging operations in diesel-emissions backgrounds can be resolved with a smoke sensor and a MOS sensor sensitive to NOx associated with diesel emissions. Other underground conditions, such as rock dust, exacerbate the problems with sensors. NIOSH has developed a neural network that takes many of these variables into account as it assesses real-time sensor data to discriminate nuisance alarms.

By Oliver Bowles

"The manufacture of asbestos paper began commercially about 40 years age but its principal development has taken place during the past twenty-five years. The asbestos used by the ancients, termed amiantus by Pliny was used for winding sheets, tablecloths and other fabrics. It was probably chrysotile fiber and was a woven and not a felted product, and there¬fore is not to be confused with asbestos paper. There are, however, some early references to paper manufacture that are of interest. Pontoppidian, Bishop of Bergen, in his Natural History of Norway, published in 1750, refers to paper made from asbestos found in the parish of Waldens. He states that this paper did not burn when thrown in the fire, but the writing on it totally disappeared. This indicates that the primary ob¬ject was to obtain an indestructible writing paper. About 100 years later, further efforts were made with the same object in view. In 1853, a patent was issued for a process of making paper from a mixture of asbestos and alum. Many experiments were made to manufacture suitable asbestos printing paper. Some such papers contained only about one-third asbestos, the remainder being of combustible material. Such papers would burn, but would leave a white residue which retained its shape and preserved the written characters. On account of the difficulty of obtaining a smooth and even surface, and the tendency for the material to absorb ink like blotting paper, asbestos paper is not well adapted for writing or printing purposes. Other early uses of asbestos paper were for ornamental wall-paper and carpet linings. None of the uses mentioned above have developed to anything of importance in a practical way, but the manufacture of asbestos paper has become a very important industry, and it has found extensive uses in ways that were never dreamed of by the early investigators.It is recorded that the first sheet of asbestos paper made in America was manufactured in 1876 by John Roberts & Son Company, in a mill near Waltham, Mass. The material first used was a long-fibered amphibole asbestos from Italy. About three years later, Canadian fiber was introduced and proved to be very satisfactory. The shorter grades of fiber which would otherwise be wasted were used for the manufacture of paper and board. For several years, the product of this mill was sold through Rice Kendall of Boston, Mass. From 1881 to 1900, the H. W. Johns Company, of New York, took the entire product which was 30C to 700 tons per year. The latter company built their own asbestos paper mill at Brooklyn in 1900. Keasbey & Mattison Company, of Ambler, Pennsylvania, began to manufacture in 1897. Other early manufacturers were: the Asbestos Paper Company, at Baldwinsville, Mass„ and Mr. B. S. Binney, at Shirley, Mass. The number of manufacturers gradually increased until at present asbestos paper is manufactured by the following ten companies:"

Nov 1, 1919

To develop a business case that promotes adoption of noise controls by reducing barriers to industry acceptance and enhancing drivers that foster their implementation. Background Over 75% of the U.S. mining workforce is exposed to hazardous noise, putting them at risk of noise-induced hearing loss (NIHL). Consequently, coal miners suffer high rates of hearing impairment that increase to 70%-90% by retirement age. To address the noise problem for coal miners, researchers from the National Institute for Occupational Safety and Health (NIOSH) first determined that the continuous mining machine (CMM) ranked first among machines associated with reported coal noise overexposures. Further studies found that most CMM noise is generated by three component systems on the machine: dust collection, cutting, and conveying. Of these systems, the on-board chain conveyor was found to be a dominant noise source. Noise generated by the conveying system was addressed through the development of a urethane-coated flight bar chain. The coated chain, shown in Figure 1, has demonstrated an 8-hour time-weighted average (TWA) reduction of operator exposure by 3 dB(A). It has since been accepted by the Mine Safety and Health Administration (MSHA) as a "technologically achievable" noise control for CMM operators who are exposed to noise that exceeds the MSHA permissible exposure level. Having demonstrated the noise reduction performance of the coated chain, NIOSH has assembled information into a business case that can be used by operations considering adopting the chain at their worksite.

Dec 1, 2009

By L. C. IlsLey

The observations made by Bureau of Mines engineers of permissible equipment installed in about 40 mines have indicated a chance for improvement in designs calling for the use of bolts , screws , studs , etc. , especially with respect to bolt sizes and protection from mechanical injury .

May 1, 1931

By J. J. Rutledge, C. A. Herbert

In 1916 the Bureau of Mines, the Illinois Geological Survey, and the University of Illinois, working under a cooperative agreement, began an investigation of the subsidence of the surface above coal- mining operations. Four widely separated places where mining was in progress were selected as observation stations-one in the northern Illinois longwall coal field, one in the central Illinois coal field where the room-and- pillar panel system of mining was being used, and two in the thick coal of southern Illinois where the room-and-pillar panel system of mining was employed. These four points of mining activity gave a rather wide opportunity for observing subsidence when different mining methods were used. The four places selected for investigation of surface subsidence due to coal mining have been designated as follows: 1. A, in the northern Illinois longwall coal field, where the coal company has been operating coal mines for 30 years and where long- wall advancing is the only method of mining. 2. B, in Perry County, where panel room-and-pillar mining of a thick seam of coal is in progress and where mining operations have been carried on about 40 years. 3. C, in Macoupin County, where the coal company has been min- ing coal by the panel room-and-pillar method for about 15 years. 4. D, in Franklin County, where the coal company has been mining coal for 10 years by the panel room-and-pillar method.

Jan 1, 1927