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By B. H. Eccleston

The Bureau of Mines, in cooperation with the American Petroleum Institute, studied the effect of fuel volatility and front-end fuel composition on the amount and photochemical reactivity of automobile exhaust and fuel-system evaporative emissions. The study involved six gasolines--the base fuel, three fuels of varied volatility, and two fuels differing from the base and from each other in front-end olefin content. Data were obtained from 16 vehicles operated on a chassis dynamometer using a speed-load-time cycle that approximated a typical urban trip. Tests were made at ambient temperatures of 20°; 45°, 70°, and 95° F, using a climate-controlled dynamometer room. The amount of hydrocarbon emission and its probable photochemical effect, a potential contribution to pollution, is expressed as weight (reactivity equivalent) of a moderately reactive material, ethylene. Emissions of oxides of nitrogen, car-bon monoxide, and aldehydes were also observed. Results showed that reduction of volatility from currently typical levels serves to reduce both the amount and the reactivity equivalent of evaporative losses with a slight penalty by way of higher exhaust emissions. Alternatively, reducing the amount of light (low boiling) olefin in the fuel had no effect on the amount of hydrocarbon pollutant but did significantly reduce the reactivity equivalent of the emissions. Neither volatility change nor chemical changes to the fuel significantly affected the nonhydrocarbon emissions.

Jan 1, 1970

By Earl L. Phillips

The Bureau of Mines conducted laboratory tests on samples of pozzolanic-cement concrete to develop a low-strength backfill. Results show that support costs can be lowered by replacing a portion of the portland cement in mine backfill with pozzolan (fly ash) and lime. Unconfined compression tests on various ratios of fly ash to cement in 84 samples produced compressive-strength curves that can be used to estimate the best backfill mix for any mine.

Jan 1, 1981

By J. L. Ambs

The U.S. Bureau of Mines (USBM) Diesel Research Program emphasizes the development and evaluation of emission control devices to reduce exposure of miners to diesel exhaust pollutants. Studies by the USBM have shown that diesel exhaust aerosol (DEA) contributes a substantial portion of the respirable aerosol in underground coal mines using diesel equipment not equipped with emission controls. The USBM and the Donaldson Co., Inc., Minneapolis, MN, have developed a low-temperature, disposable diesel exhaust filter (DDEF) for use on permissible diesel haulage vehicles equipped with waterbath exhaust conditioners. These were evaluated in three underground, mines, to determine their effectiveness in reducing DEA concentrations. The DDEF reduced DEA concentrations from 70 to 90 pct at these mines. The usable life of the filter ranged from 10 to 32 h, depending on factors that affect DEA output, such 'as mine altitude, engine type, and duty-cycle. Cost per filter is approximately $40.

Jan 1, 2010

By Edmond Chin

Mineral production was of minor importance to the country's economy, and Bangladesh was not a ranking world producer of any mineral commodity in 1980. Natural gas was the most important mineral exploited, and reserves were sufficient to allow a significant increase in its use. A greater proportion of the domestic heat and electrical energy needs could be filled by increased production and distribution of natural gas. Also, the export of natural gas was feasible either by pipeline to India or in the form of liquefied natural gas (LNG). Some nonmetallic minerals could be developed, as well as coal and peat, given sufficient capital investment. Bangladesh's strongly agricultural economy made fair progress in 1979.80.1 The major harvest of November-December 1979 turned out to be better than had been anticipated after an early drought left poor planting conditions. Secondary crops (harvested in February-March 1980 and June- July 1980) were excellent. There were prospects for a record harvest in fiscal year

Jan 1, 1982

By Sean Gallagher, Thomas R. Battenhouse, August J. Kwitowski, John R. Bartels, Dean H. Ambrose

Problem: Incident investigation reports do not usually contain enough information to aid in studying boom arm vertical speed for roof bolting machines to determine the impact that appendage speed had on an operator's risk of experiencing a contact. Laboratory experiments with human subjects are also not feasible because of safety and ethical issues. Method Researchers successfully developed a three-dimensional computer model that uses virtual human simulation software as the primary means to gather contact data when the boom arm touches the operator's hand, arm, head, or leg. Results: Data analysis of roof bolter simulations shows that the speed of the boom arm is the most important factor in determining the risk of an operator making contact. Regardless of other variables, contact incidents were always greater when the bolter arm was moving up, greater on the hand, and greater for the boom arm part of the machine. The reason why the subject experiences more contacts when the boom arm is moving up rather than down is that more risky behaviors occur during drilling and bolting when the boom arm is ascending. Based on the data collected, boom speeds greater than 13 in/sec result in a substantial increase in risk to the roof bolter operator of making contact. Speeds less than or equal to 13 in/sec are associated with a more modest relative risk of making contact, which represents a decrease in potential hazard. Impact on Industry: The use of such information can be quite helpful in making recommendations to machine design and task procedures to reduce the likelihood that roof bolter operators will experience injury due to contact with a moving roof bolting machine's boom arm.

By D. S. Kingery

The practice of using doors to control main ventilating currents in bituminous-coal mines is common throughout the industry. When doors are erected in pairs to form air locks, they are usually accepted as satisfactory by both State and Federal coal-mine-inspection agencies. A review of the contributing factors in recent methane ignitions showed that interrupted ventilation (often caused by doors latched open, destroyed, or damaged) was the principal cause of methane accumulations that subsequently were ignited.

Jan 1, 1958

By R. L. Grayson, W. E. Wallace, J. W. Stephens, M. D. Attfield, P. S. Brower, V. Vallyathan, M. J. Keane, J. C. Harrison

Pure respirable quartz is a known pathogenic agent for lung disease. However, for mixed dusts, neither mineralogical nor in vitro cytotoxicity assays unequivocally predict the contribution of quartz to their pathogenic potential.First, although Coal Workers' Pneumoconiosis (CWP) and Progressive Massive Fibrosis (PMF) prevalence have been found to correlate with total respirable coal mine dust exposure, and with coal rank (Attfield and Morring, 1992), epidemiological studies generally have not found the quartz component of coal mine dust as measured by X-ray diffraction or infrared spectroscopy (each of which essentially measures the mass-percent quartz in a bulk sample) to be clear predictors of CWP prevalence or incidence (Walton et al., 1971). Second, the properties which distinguish the extreme fibrogenic potential of quartz are not revealed by conventional in vitro bioassay comparison with other silicate mineral dusts. As an example, quartz and kaolin (aluminosilicate) clay in vitro cytotoxicities are comparable for lavaged primary pulmonary macrophages.The studies discussed here address these two anomalies from a general hypothesis that the pathogenic activity of respired quartz particles is associated with properties of, and interactions with, the particle surfaces. One factor in the expression of toxic activity by a particle surface is the biological availability of that surface. Anomalous lack of correlation of disease prevalence with mass percent quartz in exposures to some mixed composition respirable-sized dusts suggests that individual particle surface features, invisible by bulk sample mass analysis, may alter the biological availability of a fraction of quartz particles in a dust. For pure-surfaced mineral particles, the comparably strong prompt membranolytic activities of quartz and kaolin in vitro suggest that upon deposition of such particles in the lung there must be other interactions with particle surfaces which distinguish quartz. This might be due to toxic surface-associated sites specific to silica, or to interactions of other sites on other mineral particles which affect the biological availability of their toxic functional groups. For example, alurninol groups on clays affect the availability or activity of adjacent silanol groups. Surface activities which distinguish quartz pathogenici ty might be manifest in one or more of the sequential interactions upon deposition in the lung; first with the pulmonary surfactant system, then with extracellular and phagolysosomal enzymatic digestive processes, or with subsequent cytotoxic processes.

Dec 1, 1995

By Ted C. Briggs

The Bureau of Mines is evaluating the thermodynamic properties of helium and helium-containing mixtures. Twenty-two compressibility runs were made with helium at 0° C and pressures to 800 atmospheres using a Burnett-type apparatus. Data from the 22 runs were treated simultaneously and as separate runs while different functional forms and weighting factors were used. A fourth-degree-polynomial equation in the pressure gives a statistically satisfactory representation of the compressibility factor when the data are treated simultaneously and a weighting factor of Pr-3/4 is used. The second virial coefficient of helium at 0° C from this investigation is 11.997±0.015 cm3 mole-1. The stated uncertainty is the random error standard deviation. Compressibility factors determined by this investigation are precise to better than 0.01 percent and are believed to be accurate to better than 0.02 percent.

Jan 1, 1969

By Douglas Pollock, John Organiscak

Water spray characteristics, including droplet size and velocity, airborne dust capture potential, and induced airflow quantity for various spray nozzle designs were evaluated to provide basic information for improving spray applications. Water droplet size and velocity characteristics were initially measured by a Phase Doppler Particle Analyzer (PDPA) for hollow cone, full cone, flat fan, and air atomized spray nozzles at similar operating parameters. Airflow inducement and dust capture experiments were also conducted under the same operating parameters to examine any salient features of the spray nozzle type, droplet characteristics, induced airflow, and airborne dust capture. Test results indicate that there are trade offs between airflow inducement and dust capture efficiency. A spray nozzle with a wider discharge angle was observed to induce more airflow, but at reduced dust capture efficiencies. Increasing spray nozzle fluid pressure(s) generally reduced water droplet sizes with concurrent increases in droplet velocity, airflow inducement, and airborne dust capture. Placing a three-sided barrier around the spray nozzles normally reduced spray air induction and increased dust capture efficiency. A direct relationship between airborne dust capture efficiency and spray input power normalized per unit of airflow induced was ob- served. This information can be utilized to improve the performance of water sprays for reducing airborne dust levels.

By David F. Gearhart, Thomas M. Barczak

This U.S. Bureau of Mines report examines the roof and floor contact pressure provided by the interaction of a shield with the surrounding strata. Controlled forces were applied to an 800-ton two-leg shield in the Bureau's mine roof simulator; the distribution of forces acting on the canopy and base of the shield were measured with 24 hydraulic pressure cells. Several influential factors that affect the load distribution were investigated: (1) the magnitude of loading (leg pressure); (2) the profile of the canopy, principally the upward-sloping tip; (3) the base-lifting device; (4) horizontal load acting on the shield; and (9 compliancy of the immediate roof and floor. It was concluded that the shield does not develop full canopy or base contact without deformation of the strata. Maximum contact pressures are developed at the rear of the canopy and on the toes of the base. Less than 10 pct of the available shield capacity is developed at the canopy tip despite the design intention to ensure tip contact. Horizontal loading reduced the toe pressure acting on the base by as much as 75 pct. The base-lifting device exaggerated the inherently high toe loading, increasing the contact pressure by more than 200 pct.

Jan 1, 1992

By Howard C. Turnage, Dana T. Updyke

An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system evaluated was installed in a typical metal/non-metal room and pillar mine and utilized UHF repeaters connected to a unique distributed antenna and passive reflector system which provided mine-wide communications. A microprocessor controlled data collection system was assembled and installed for the evaluation. Data consisting principally of times and durations of messages and identities of the originating transceivers was collected between February and August of 1982 (6 mos.). Analysis of the data shows that the principal benefits are reduction in time required for unscheduled maintenance and repair, enhancement of safety, and better coordination of production activities. A cost benefit analysis shows a net benefit over cost, although it is also concluded that the capacity of the system is greater than can be justified by current activity in the mine.

Jan 2, 1983

By M. M. Fine

A satisfactory mean: of beneficiating a Brazilian phosphate rock was developed in a mineral-dressing-research study by the Bureau of Mines. High-grade concentrates well ever the specified minimum grade of 70 percent tricalcium phosphate, were produced, with goad recoveries by agglomerate tabling and flotation. A lower gads but usable secondary product was recovered by sedimentation of the minus-200-mesh fraction of the ore. The ore wan representative of an extensive deposit recently discovered near Recife in the State of Pernambuco, Brazil, which will be exploited in a plant planned to eventually produce at the rate of 500,000 tons of concentrate annually. Although Brazil has been reported to Lave a substantial reserve of phosphate rock,3/ the country has never been more than a small producer of this commodity. From 1945 to 1950 the highest production of phosphate rock attained in Brazil amounted to 10,421 tons. Production in 1949, the most recent year for which figures are available, was 4,553 tons.4/

Jan 1, 1954

By Oliver Bowles

[In an endeavor to promote greater efficiency in the lime industry, the United States Bureau of Mines is preparing a series of preliminary reports dealing with particular problems of the industry. Through the circulation of these reports, it is hoped that sufficient interest may develop among lime-plant operators to prompt them to discuss with the bureau their our experiences with these problems. By such an interchange of ideas, it is believed that conclusion may be reached which will be of practical benefit to try entire industry. The first report, "Stripping problems it Limestone quarries of the Shenondoah Valley", Serial No. 2401, was issued during October, 1922. This report t is the second of the series. It is hoped that may operators will contribute additions to the information now at hand.]

Jan 1, 1922

By C. J. Thompson

In the course of the work currently conducted by the Bureau of Mines in cooperation with the American Petroleum Institute Research Project 48 on identifying sulfur compounds in petroleum, a micromethod was developed (12)5 for catalytically removing the sulfur atom from sulfur compounds. The product is the residual portion of the molecule; the structure otherwise was unaltered except for hydrogenation of any unsaturated bonds that were present in the original compound. Positive identification of sulfur compounds isolated from crude oils is a difficult problem. Direct comparison of properties of the unknown with those of reference compounds is often impossible because of the limited number of reference sulfur compounds available. However, a relatively large number of pure hydrocarbons is available, and the conversion of the sulfur compound to a hydrocarbon enhances the possibility of identification. The technique also can be used to prepare microquantities of scarce hydrocarbons by hydrogenating compounds that are readily available.

Jan 1, 1962

By Raymond F. Helinski, Linda J. McWilliams, Sean Gallagher, Thomas R. Battenhouse, August J. Kwitowski, John R. Bartels, Dean H. Ambrose

This report examines the boom arm vertical speed for roof bolting machines to study a moving boom arm appendage at different speeds during different work scenarios. The goal of this study is to determine the impact of the appendage speed on the likelihood of the operator's hand, arm, head, or leg making contact, such as touching the moving appendage. The overall research goal is to reduce workers' risks to injury from exposure to underground mining machinery. Accident investigation reports from the Mine Safety and Health Administration do not usually contain enough information to aid in studying this problem, and lab experiments with human subjects are not feasible because of safety issues. As an alternative, researchers used a unique computer simulation model that uses a virtual human, vision tracking, and generates random virtual human motions and risky work behaviors. By using specialized software to simulate the computer model, researchers accurately identified potential hazards of tasks where it is not possible to perform experiments with human subjects. Results of a frequency distribution analytic approach show that, regardless of other variables, contact incidents were always greater when the boom was moving up, always greater on the hand, and always greater or the boom arm part of the machine. The reason why the subject experiences more contacts when the boom arm is moving up rather than down is that more risky behaviors occur during drilling and bolting when the boom is ascending. Results of a cross-tabulation analytic approach show that the 25th-percentile operators experienced more contacts than other operator sizes and had most of their contacts during a boom speed of 13 in/sec. The hand-on-boom behavior during drilling and bolting tasks experienced more contacts than other work behaviors, and both tasks had most of their contacts during speed 13 in/sec. The 60-in seam experienced more contacts than other seam heights and had most of the contacts during speed 16 in/sec. For univariate logistic regression models, seam height is the most important predictor of the probability of a contact. However, a multivariate logistic regression model predicted contacts are more likely with the both-knee work posture in the 60-in seam, a 25th-percentile operator compared to a 55th-percentile operator, and speeds 16 and 22 in/sec compared to 7 in/sec. Results of a survival analytic approach suggest that controlling the boom speed is the most important factor in determining the risk of an operator making contact. Based on the data collected, boom speeds greater than13 in/sec result in a substantial increase in risk to the roof bolter operator making contact. Speeds less than or equal to 13 in/sec are associated with a more modest relative risk of making contact, which represents a decrease in potential hazard. Virtual operator's response time has little effect on the number of contacts experienced. The mining industry can use the information in this study to reduce the likelihood that roof bolter operators will experience injury due to contact with a moving roof bolting machine's boom arm.

Jan 5, 2005

By John A. Breslin

Three scale models of coal mine entries and mining machines were constructed by the Bureau of Mines to study the effects of ventilation parameters on dust concentrations where mining personnel would be working. A one-fifth-scale model of a coal mine entry with a drum-type continuous-mining machine and a one-sixth-scale model of an entry with a twin-borer-type machine were used as well as a one-fifth-scale model of a longwall face with a double-drum shearer. Methane was used as a tracer gas to simulate respirable dust in the models. The distance of the end of the brattice or tubing from the face was found to be more important than the airflow rate for the drum-type machine. Dust reductions greater than 90 pct were shown to be possible with a secondary ventilation system used with the twin borer and a dust collector mounted on the longwall shearer. Cutting-head speed had a significant effect on concentrations at typical positions of miners with the drum-type machine and longwall shearer but not for the twin borer.

Jan 1, 1976

By B. P. Martinez

This report presents the results of a research and development program in recovering waste-rolling oils conducted by the Bethlehem Steel Co., before 1954 at its Sparrows Point plant, Sparrow Point, Md., with the cooperation of the Bureau of Mines, U. S. Department of the Interior, College Park, Md. The objective of the program was twofold: First, to recover oil for reuse in the plant; and second, to stop pollution, by oil, of the stream and harbor areas in the immediate vicinity of the plant. The sequence of the investigations was laboratory and pilot plant studies on sedimentation, simple aeration, and flotation for the separation of oil and water; and construction of a production unit using standard flotation equipment. This work was only preliminary for the Bethlehem Steel Co. and it has continued research on this problem. Recent progress indicates that new, improved processes will soon replace the flotation units described in this report. The first efforts to separate oil and water by simple sedimentation were unsuccessful. To establish the cause of this failure, microscope examinations and measurements were made on cold-reduction rolling mill cooling-water effluents containing oil in suspension. It was discovered that an average oil globule, held in suspension, was only 0.001 inch in diameter and would not coagulate with other globules for normal sedimentation at room temperature. The next step in the sequence of studies was to coagulate the oil suspension by simple aeration with air under slight pressure. The aeration methods studied were effective in removing up to 68 percent of the total oil but were approaching flotation in principle. The final investigation of the series was flotation of the oil in conventional laboratory-size flotation cells. The small-bubble method, without reagents, floated up to 89 percent of the total oil held in suspension and was the process selected for pilot-plant development.

Jan 1, 1959

By W. N. Poundstone, W. M. Merritts, B. A. Light

A joint investigation by the Bureau of Mines and the Christopher Coal Co. at the Humphrey No. 7 mine, operating in the Pittsburgh coalbed in northern West Virginia, was undertaken to gain more insight concerning the hazardous emission of methane gas in mining. This report describes the equipment, procedure, and results. Horizontal bleeder holes drilled in the faces drained large quantities of methane, eliminating downtime of mining equipment. Also, larger quantities of methane were removed by forcing 14 to 25 g,.p.m. water at 25 to 200 p.s.i. 5 pressure into the bleeder holes. In one infusion test a fluorescein dye was added to the infusion water; in later mining operations, the infusion water was traced for a distance of 1,500 feet. With vacuum pump applied to the horizontal hole the gas-flow rate increased, and the methane content decreased. Tests indicated that methane and water infused in bleeder holes traveled along the bedding planes of the Pittsburgh coalbed at a faster rate than across the planes. Methane associated with coalbeds is produced by the slow decomposition of carbonaceous material in the absence of air and the presence of water. It is lighter than air and, depending on its concentration, forms an inflammable or explosive mixture with air. It is believed that methane is entrapped in and around the pores of the coal and adjacent strata--often under great pressure. In many cases where the strata have been disturbed by geologic movements the

Jan 1, 1962

By B. K. Cantrell, K. L. Rubow

"Quantifying exposure to diesel exhaust aerosol in an underground coal mine depends on the ability to measure this component of respirable mine aerosol separately from coal dust. Such measurement is complicated by the carbonaceous nature of both the diesel and coal dust particulate that make up the respirable aerosol. Hence, special sampling and analytical techniques must be used to distinguish between these two aerosol components.As part of a continuing study of diesel exhaust aerosol characteristics, the U.S. Bureau of Mines has applied size selective sampling together with gravimetric analysis to separate and measure respirable diesel exhaust and coal dust aerosol concentrations in diesel-equipped underground coal mines. This technique is based on the premise that the diesel portion of the aerosol is predominantly submicrometer and the mineral dust portion is mostly greater than 1 µm in size. In the study, chemical mass balance (CMB) modeling, based on the distribution of chemical elements in aerosol and aerosol source material samples, is used to referee the analysis of diesel exhaust and mineral dust aerosol concentrations from the size selective sampling results.Based on the results of the study, the Bureau, in cooperation with the University of Minnesota and the U.S. Mine Safety and Health Administration (MSHA), have developed a prototype personal diesel exhaust aerosol sampler for underground coal mines. The sampler has three stages: a preclassifier stage to select for respirable aerosol, an inertial impaction stage with an aerodynamic diameter(d) size cut at 0.8 µm to separate diesel aerosol from mineral dust and collect the mineral dust, and a final filtration stage to collect the diesel fraction of the sample. The sampler has been evaluated in both laboratory and field experiments conducted by the Bureau, MSHA, and the Generic Minerals Technology Center for Respirable Dust (GMTC-RD)."

Mar 1, 1992

By Robert A. Jankowski, Ellsworth R. Spencer, Jay F. Colinet

Longwall mining is the most productive method of under- ground coal mining in the United States (U.S.), and record levels of production have been reached in recent years. These ever-improving production levels have the potential to generate significantly higher quantities of respirable dust. Consequently, the longwall industry continues to struggle with controlling dust liberation and maintaining compliance with the federally-mandated respirable dust standard. In response, longwall operators have increased the application of primary dust controls, airflow and water flow, in an effort to improve respirable dust control and reduce worker exposure. Pittsburgh Research Center (PRC) personnel conducted dust surveys at 13 longwalls operating throughout the U.S. and collected information to: identify current operating practices on these longwalls, identify the types of dust controls in use, document the levels at which these controls are being applied, and measure the respirable dust levels present. This data was analyzed to quantify the dust levels generated by the major sources on the longwall section and to evaluate the relative effectiveness of the control technologies in use.