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By Susan B. Bealko

Mining provides a large part of the energy and raw materials that feed this Nation's economy. Copper pipe, concrete, and window glass serve as well known examples of the reliance on minerals in modern society. Less appreciated, but as important, are the hundreds of mined commodities that are an integral and necessary part of everyday products, ranging from medicines and computers to carpet and paper. Coal is a major portion of the country's energy mix today, as it will likely continue to be in a future hydrogen-based economy. The domestic mining industry also provides strategic minerals that are important for the Nation's security. The processes to recover these mineral commodities are among the most demanding and complex in an industrial society, and this inherently dangerous industry has historically had the highest risks of fatality and injury. The mining industry has been undergoing some trying and challenging times because of the recent mine disasters in the coal fields. These events have been alarming in light of the strong and encouraging safety record that has characterized mining in the United States for most of the past decade. While mining communities deal with their grief, mine operators, government regulators, and other safety personnel, set about trying to determine why these fatalities occurred. Subsequently, the mining industry is currently experiencing changes in legislation at an unusually rapid pace. The most recent regulatory changes are the Mine Improvement and New Emergency Response Act of 2006 (MINER Act) and the temporary emergency standard for mine seals. The new mine safety laws call on the nation's mines to adopt certain procedures and safety technologies immediately, or as soon as they become commercially available. Putting all the provisions in place from these new laws is a major undertaking, and will necessitate strong collaborations and partnerships among mine operators, manufacturers, regulatory and research agencies, labor unions, and community groups. It is against this background that Prevention through Design (PtD) components for the Mining Sector are recommended.

Jan 1, 2008

By E. J. Kloos

The Bureau of Mines evaluated all previously approved gas masks to determine their ability to provide respiratory protection against each of the following six selected amines: ethylenediamine, diethylamine, n-butylamine, ethylamine, methylamine, and hydrazine. Minimum requirements were a 24-minute service life at a flow rate of 64 liters per minute (32 liters per minute for hydrazine) and an amine concentration of 1.0 volume-percent (0.5 volume- percent for hydrazine). The three masks meeting these requirements were the LG4, Willson Products Division, The Electric Storage Battery Co.; the GMD-SS, Mine Safety Appliances Co.; and the 084-PHOV-R, Acme Protection Equipment Co.

Jan 1, 1966

By H. E. Camargo

In an effort to decrease noise-induced hearing loss (NIHL) in coal preparation plant employees, the National Institute for Occupational Safety and Health (NIOSH) is conduct­ing research to identify and control dominant noise sources in vibrating screen (VS) machines. To this end, acoustic measurements of the noise radiated by a dewatering VS were conducted at the Pittsburgh Research Laboratory (PRL) using microphone phased-array technology. These measurements allowed for the identification of the screen as the dominant source in the 250 Hz 1/3-octave band. The sidewalls are the major contributors in the 315 and 400 Hz bands, whereas the eccentric mechanisms and the electric motor are the dominant sources in the 800 and 1,000 Hz bands, respectively.

Jan 1, 2009

By J. E. Gebhardt

External control of the electrochemical potential of a bed of mineral particles has been investigated by the Bureau of Mines as a method for controlling particle inter-action with organic collectors and thus, flotation response. A cylindrically shaped, 200-to 300-g bed of sulfide mineral particles was used as the working electrode to examine the potential distribution in the bed. The dissolved oxygen concentration of the electrolyte had a significant effect on the potential profile across the mineral bed. Low oxygen levels were necessary to achieve uniform electrochemical potential distributions. Flotation separation of a chalcocite-pyrite mineral mixture by controlled potential was achieved using ethylxanthate, but the flotation behavior of chalcocite and pyrite from the mixture does not follow the flotation behavior of the individual minerals. That is, the presence of another sulfide mineral alters the flotation behavior with ethylxan-thate. Galvanic interaction due to mineral-to-mineral contact between chalcocite and pyrite contributes to differences in the recovery. Chalcocite dissolution products had a deleterious effect on pyrite flotation by activating flotation below -0.1 V (saturated calomel electrode) and depressing flotation above -0.1 V. Pyrite dissolution products had no effect on chalcocite flotation.

Jan 1, 1985

By D. A. O'Keefe, M. M. Wong

To obtain beryllium metal of higher purity , flakes produced from electrorefining scrap metal were used as cell feed for a second cycle of electrore fining at 500 ° C in an electrolyte composed of 51.7 mole - percent LiCl , 36.9 molepercent KC1 , and 11.4 mole - percent BeC¹ · Metallic impurities in the flakes totaled more than 108 ppm , the metallic impurities in the metal obtained from the two - cycle electrorefining were , with the exception of 35 ppm of calcium , below the spectrographic determination limits .

Jan 1, 1964

By H. Carroll

An ozone detector was built and evaluated for its applicability in smog-chamber studies. The detection method is based on the reaction of ozone with ethylene and the measurement of resultant chemiluminescence. In the first phase of evaluation, the detector's response to ozone was studied as a function of several instrument parameters, and optimum conditions were defined for the maximum and most stable responses to ozone. In subsequent evaluations, the method was checked for sensitivity, precision, and interferences and was compared with two alternative methods. Results showed the chemiluminescence method to be acceptably sensitive and precise for smog-chamber studies and superior to the Mast ozone meter and KI (colorimetric 1 percent neutral-potassium iodide method) methods in that it is specific for ozone.

Jan 1, 1972

By M. F. Dunn

A handbook to provide a quick reference guide for selecting and using jet fans in a variety of conditions was prepared. The document is intended for use by front-line supervision, ventilation engineers, and mine planners. Included are discussions of jet fan characteristics, selection and use critieria, and do's and don't's for easier operation, safety, and performance. The handbook is based on research at three underground metal/nonmetal mines having cross-sectional areas of 900 to 2,000 ft2.

Jan 1, 1983

Provide a low-maintenance, reliable means of generating bubbles and controlling bubble size for column flotation. Approach Commercial sparger systems used in flotation columns to process minerals provide only limited means of controlling the size of bubbles generated and the rate of air injection. Generally, these limitations are a detriment to flotation performance, particularly in recovering coarse or fine mineral particles. In addition, conventional bubble generation systems require frequent maintenance, often requiring shut-down of the column itself for repairs. To permit greater control of the bubble size generated in the flotation column and to eliminate the counter-productive problems associated with the operation of current air sparger systems, the Bureau of Mines investigated alternative methods for generating bubbles. Based on the investigation, an external bubble generation system was designed, developed, and laboratory and commercially tested.

Jan 1, 1987

Establish a procedure for reliably determining cation exchange parameters at an in situ mining site. The Problem Predicting the movement rates of pollutants from waste disposal sites requires reliable measurements of cation exchange parameters since cation exchange can retard pollutant movement. Reliable measurements of these parameters are also required for predicting the length of time needed to restore groundwater quality after in situ mining. Cation exchange is otten the controlling mechanism for the replacement of leach solution cations by the cations in the returning ground-water. Unfortunately, laboratory measurements using core samples are of minimal reliability. The uneven clay distribution at most sites produces a high variability in laboratory results. In addition the flow pattern in the laboratory tests is different from that in the field. Approach Bureau of Mines research has developed a field-test procedure that is quick and yields reliable and representative data. A corresponding data analysis procedure was also established in order to verify the' applicability of the computer simulation model of cation exchange used in the analysis, and of the general analysis procedure, with actual field data.

Jan 1, 1986

Although haulage truck collisions account for only a small percentage of haulage accidents, the likelihood of severe injury, or even death is very high when such a collision does occur. Most rear-end collisions also result in considerable equipment damage, creating a need for expensive repairs. To improve collision protection, some southwestern surface mines have, for several years, been fabricating and using extended bumpers. In cooperation with these mines, the Bureau of Mines has worked to improve this technology by evaluating the structural requiremnts of extended bumpers. How Extended Bumpers Help The Bureau found that when one large rear-dump haulage truck collides with the rear of another an extended bumper protects the driver of the vehicle that is struck by dissipating the impact energy into the rear tires and pushing the whole vehicle forward. An extended bumper also prevents the box on the truck that is hit from penetrating the cab of the other truck-a typical and serious collision hazard. A further advantage derives from the wide design of the extended bumper which helps prevent damage to truck ladders, thereby minimizing any entry or exit problems. Extended bumpers also provide safe work platforms at the front of large haulage vehicles.

Jan 1, 1984

By M. K. Larson, J. P. Dunford, E. G. Zahl, T. M. Brady

Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health, Spokane, WA, have collaborated with three Western longwall coal mines in an on going effort to develop technologies that will aid in providing safe and stable working areas. The goal of the research described here is to develop a stress monitoring system that will provide immediate information to mine managers for making daily safety decisions as areas of poor ground are mined through. Initial work has focused on answering preliminary questions regarding the reliability and use of stress change patterns. Research is concentrated on monitoring horizontal stress because horizontal stress is transmitted over long distances through stiff strata, thus allowing an extended length of entry to be monitored. This paper presents an explanation of the concept, key results from field tests at two mine sites, and a proposed process for implementing a monitoring system. System design layouts, instrument use, data collection and interpretation methods, and processes to present findings to mine staff are described. Additional validation and correlation with actual failure mechanisms are required before this approach can be recommended at ongoing operations. However, initial results indicate that this approach shows promise in mines prone to bumps and roof falls associated with large stress changes. In particular, analyses of measured changes in horizontal stresses appear useful.

Prevent the propagation of a fire and control the spread of smoke and toxic gas in underground mines. Approach A fire door suitable for large openings in underground noncoal mines and providing protection for openings requiring 11/2 hours of fire resistance, a 250°F maximum temperature rise, and high pressure differentials was de-signed, laboratory tested, and in-mine tested. How It Works The door is a double-acting swing type. Its two panels. connected by an overhead linkage, open in opposite directions. Consequently, high pressure differentials across the door have little effect on the force required to open and close the door. The door is constructed of 14-gauge sheet steel skins welded to both sides of a 5-inch-wide steel channel frame. The frame is rein-forced with 5-inch-wide steel channels in a horizontal and diagonal pattern. The voids between the reinforcing members are filled with a ceramic fiber insulation material to limit the surface temperature rise of the unexposed side of the door during a fire. A fire -resistant neoprene-coated fabric is used to seal around the edges of the door panels. The door is opened and closed by an air cylinder, attached to the over-head linkage and operated by lanyards on either side of the door. The door design includes an optional airlock manway for drifts of adequate width.

Jan 1, 1983

By Oliver Bowles

"Rhodesian asbestos is of high quality and is much in demand by American consumers. Production in Rhodesia was first reported in 1909. The production for this and each succeeding year is shown in the following table:The serious curtailment in production for the years 1912 and 1913 was occasioned by transportation difficulties. In 1914 a railway was projected to Victoria and thereafter production increased greatly. Up to 1916 asbestos was obtained,from the Victoria district only, but thereafter the Bulwayo district became an important,producer with minor quantities from Gwelo.In the Bulawayo district the productive area is about 2 1/2 miles long, with Shebanie mine at the north-west end, the Nil Desperandum at the south end, and the Birthday claims between them."

Oct 1, 1920

By R. Karl Zipf

A method is presented for creating realistic numerical models for practical coal mine ground control. The method includes procedures to collect the necessary mechanical input parameters from a geologic core log, procedures to set up a model, and procedures to interpret calculation results. The input parameters come from a detailed geologic core log and extensive point load tests of estimate rock layer strength. A suite of material property input parameters is proposed that allows the user to go from core log to numerical model inputs. Rock bolt anchorage properties are also linked to the material properties of each geologic layer in the model. Following this procedure leads to very realistic calculations of the rock failure process and rock support system behavior. These calculations in turn enable realistic comparison of the effectiveness of alternative rock support systems.

Jan 5, 2007

By James C. Cawley

The Bureau of Mines has empirically determined ignition probability versus current for resistive circuits in an 8.3% methane-air atmosphere. Simple ignition probability, defined as the number of ignitions divided by the total number of sparks, was determined, and the corresponding currents were recorded. The experiment was designed to minimize the probability of not observing an ignition that should occur during a series of tests. For resistive circuits in 8.3% methane-air mixtures, the experimental results indicate that ignition was not achieved below 2,000 rnA at 20 V dc, 350 rnA at 30 V dc, 150 rnA at 40 V dc, and 175 rnA at 50 V dc. The simple probability of ignition corresponding to these currents is esti-mated to be, respectively, 1.0 x 10-6, 1.7 x 10-7, 3.0 x 10-7, and 1.0 x 10-5 The ignition mechanism seems to break down below this point, implying that a threshold current value exists below which spark ignition does not occur.

Jan 1, 1987

By R. F. Abernethy

A chemical method of determining microgram quantities of arsenic in coal was investigated by the Bureau of Mines to supplement a semiquantitative spectrographic method of determining arsenic in coal ash. In accordance with a method recommended by the International Organization for Standardization, 1-gram samples of coal are decomposed by wet oxidation with boiling sulfuric acid (H2S04) and nitric acid (HN03) to remove the organic matter. After heating to fumes of SO3 to remove HN03, the arsenic is separated as arsine by the action of zinc in H2S04 solution. The arsine is absorbed in dilute iodine solution in which the arsenic is determined colorimetrically by the molybdenum-blue reaction. Two modifications of the method for obtaining the arsenic in solution, in addition to the wet oxidation method, give satisfactory results. The modifications are (1) furnace ashing with MgO added to the coal, followed by treatment with H2S04, and (2) extraction of arsenic from the coal by dilute HNO3 without ashing. Float-and sink-tests show that arsenic is associated mainly with mineral matter in the three coals examined. High-temperature ashing tests show that very little arsenic is volatilized from coal ash below 1,000° C, but it is virtually all removed from the ash at 1,300° C.

Jan 1, 1968

By A. D. Mah

Thermodynamic data on compounds of arsenic and sulfur were critically evaluated by the Bureau of Mines. Changes of standard enthalpy and Gibbs energy, and logarithms of the equilibrium constants were tabulated as a function of temperature for reactions involving these compounds.

Jan 1, 1982

By Sarkis G. Ampian

The Bureau of Mines has developed a method for identifying fine particles of beryl in mineral samples by preferentially staining the beryl grains. The sample is first subjected to a heated sodium hydroxide solution to etch the beryl particles, which are subsequently stained an intense blue color in a boiling alkaline solution of quinalizarin. Positive identification of beryl grains permits quantitative analyses by microscopic techniques. INTRODUCTION Beryl, a beryllium aluminum Silicate, is the principal ore mineral of beryllium. The only known commercial concentrations of this mineral are found in pegmatite dikes of granitic composition. Normally beryl is associated with muscovite mica, quartz, and the sodium-and potassium-bearing feldspars (orthoclase, microcline, and albite). Other beryllium-bearing minerals which are found occasionally in minor amounts with beryl are phenacite, a beryllium silicate, and chrysoberyl, a beryllium aluminate.

Jan 1, 1962

By W. K. Tolley

This report presents data collected during research by the Bureau of Mines on corrosion of grinding media. Corrosion rates of eight alloys commonly used in grinding media were tested in synthetic mill water using an ultrasonic grinding device especially designed for this work. Electro-chemical measurements showed variations in corrosion rates for these alloys between 9.8 mpy for medium-carbon steels and 0.14 mpy for high chromium white irons. Bureau data are discussed along with data from the literature to indicate that corrosion causes less than 10 pct of the wear of grinding media in commercial grinding mills. A comparison of corrosion rates for various types of grinding media shows that alloying elements and electrochemically active inclusions in steel affect the corrosion behavior of the media.

Jan 1, 1984

Prevent collisions between large mine-haulage trucks and smaller vehicles parked in areas not visible to the haulage-truck operator, Approach Two electronic systems were developed to detect the presence of vehicles in the blind areas of a parked haulage truck. The systems can warn haulage truck operators of presence of vehicles that are blocked from view. The systems do not apply for trucks in travel. How It Works The systems use electronic transmitting techniques-one system is based on low-frequency radio waves and the other on very-high-frequency radio waves. Each system requires that a signal transmitter be mounted on the smaller vehicle to be detected. Continuous signals from this transmitter are sensed by receiving antennas mounted on the right front and rear of the large haulage truck. Upon receiving a signal, the receiver energizes warning lights and a buzzer in the cab of the haulage truck, alerting the operator to a possible collision hazard. Detection distance is adjustable, depending upon the size of the haulage truck, but a minimum of 30 feet was the design goal.

Jan 1, 1990