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By Dale W. Richardson

Ductile hafnium was not obtained consistently by the conventional Kroll process. The bimetal reduction modification produced a more ductile hafnium by lowering the impurities, especially oxygen, in the sponge metal. Hafnium oxide was chlorinated in the presence of carbon to form anhydrous hafnium tetrachloride, which was reduced by sodium and magnesium in an inert atmosphere to produce sponge hafnium metal. After vacuum distillation to remove the byproducts, the sponge was arc-melted into ingot and rolled into strip. Metallic impurities were decreased by evaporating the hafnium tetrachloride from a fused salt. An excessive amount (over 1,200 parts per million (p.p.m.)) of aluminum was contained in some of the hafnium oxide, much of which remained as aluminum chloride in the hafnium tetrachloride during chlorination. Evaporation of the hafnium tetrachloride from a fused NaCI-KCI mixture during the Mg-Na reduction greatly lowered its aluminum content, as most of the aluminum and some of the other metallic impurities were retained by the fused salt.

Jan 1, 1961

By Don Conrad, Tom Friend, Bill Wiehagen, Lynn Rethi

On-the-job training (OJT) is a very common method of teaching job skills. Much of the training is done by experienced workers. This paper discusses small investments that can help improve the effectiveness of OJT. Effective OJT involves some structure and planning in the transfer of responsibility for task performance from the trainer to the novice. Assisting the OJT trainer could involve helping develop up-to-date job analyses and offering strategies for teaching and evaluating job skills. The scope of this paper addresses (1) organizational considerations supporting structured OJT, (2) general strategies for structuring OJT, (3) a typical approach for conducting OJT, (4) characteristics and duties of OJT trainers, and (5) limitations of OJT as a teaching method. Health, safety, and operational skills can be connected through training. Haul truck operator training is used to illustrate some of the concepts discussed in this paper.

Jan 1, 2002

By James D. Noll, M. Eileen Birch

A monitoring method for diesel particulate matter was published as Method 5040 by the National Institute for Occupational Safety and Health (NIOSH). Organic and elemental carbon are determined by the method, but elemental carbon (EC) is a better exposure measure. The US Mine Safety and Health Administration (MSHA) proposed use of NIOSH 5040 for compliance determinations in metal and nonmetal mines. MSHA also published a rule making for coalmines, but no exposure standard was provided. A standard based on particulate carbon is not considered practical because of coal dust interference. Interference may not be a problem if an appropriate size-selective sampler and EC exposure standard are employed. Sub micrometer dust concentrations found in previous surveys of nondieselized, underground coal mines were relatively low. If a large fraction of the sub micrometer dust is organic and mineral matter, sub micrometer EC concentrations would be much lower than sub micrometer mass concentrations. Laboratory and ?eld results reported here in indicate the amount of EC contributed by sub micrometer coal dust is minor. In a laboratory test, a sub micrometer EC concentration of 31µg m 3 was found when sampling are spirable coal dust concentration over three times the US compliance limit (2mg m3). Laboratory results are consistent with surveys of nondieselized coal mines, where EC results ranged from below the method limit of detection to 18µg m 3 when size-selective samplers were used to collect dust fraction shaving particle diameters below 1.5µm sub micrometer EC concentrations were ?7µg m3. In dieselized mines, sub micrometer EC concentrations are much higher.

By Yumi Nakashima, Setsuo Maeda

Vibration magnitude and frequency of the z-axis vehicle seat are time-variant, which are influenced by not only vehicle vibration characteristics themselves but also road surfaces, speeds and the human body. There is little in the current reporting about evaluating and analyzing automobile seat vibration that focuses on the time-variant. Yaguchi et al.1 has proposed a method to evaluate automobile seat vibration that is based on judgments using a subjective mental state. Their method focuses on the time-variant magnitude of the peak frequency on a power spectrum density. However, their method has no consideration of all the frequency contents of the discomfort, nor comparison between different peak frequency vibrations. Suzuki2 has emphasized that the vehicle vibration should be judged by a series of vibration stimuli to evaluate, because the vehicle vibration is time-variant, which isn’t a matter of the relationship between a single vibration stimulus and a subjective response. He clarified that the human sensation to the vehicle vibration discomfort changes every moment showing the relationship between the frequency-weighted r.m.s. acceleration calculated every 5 seconds and the category judgment to vehicle vibration discomfort every 5 seconds. However, his study doesn’t show what parameter connects to the subjective final judgment to vehicle vibration. Therefore, we applied the method similar to ISO100563 considering the time-variant to the vehicle seat z-axis vibration evaluation. The new method for the vehicle seat vibration considering the time-variant was examined on the hypothesis that the final subjective evaluation must be conducted from the judgment summarizing a series of vibration stimuli. Methods The vibration bench system, which reproduces the movement of a vehicle floor, was used for the experiment with the single-axis (vertical direction) four-post road simulator system, which is usually used for a car, as shown in Fig.1. The experiment was done on the right side of the vibration bench using the floor vibration which was 5.5 minutes, 0.822 m/sec2 (Wk) over the range 0.5-20Hz with 4 male subjects (age ave21.5, SD0.5, weight ave75kg, SD7.91kg, height ave166.8cm, SD5.2cm) and 4 suspension seats. As Fig.2 shows, subjects evaluated the degree of discomfort every 5 seconds to each seat vibration measuring the seat z-axis vibration acceleration. [ ]

Jan 6, 2006

By Luis v. Coppa

Since its inception in 1910, the Bureau of Mines has been the principal Federal agency involved in ore reserve estimations, using such traditional methods as polygons of influence and variations of inverse distance weighting While adequate for estimating the average are grades in a mining block or section, these methods do mot, however, provide a consistent way of quantifying the reliability of the estimates. This report describes a technique for enhancing ore reserve estimations using geostatistics, the methodology of which combines the spatial and random aspects of geologic phenomena into a formal theoretical framework for deriving the estimation variance of ore reserves. Correctly used, geostatistics enables confidence intervals to be placed around ore reserve estimates calculated from drill hole data. A geostatistical software system was obtained -From the U.S. Geological Survey and installed, aster slight modifications, on the Bureau's Wang computer. System testing and validation was conducted using a simple cast-book-type example. This was then followed by variogram analysis, point kriging and block kriging of data from a previously worked section of a uranium mine.

Jan 1, 1984

By Edward L. McHugh, Stanley M. Miller, Jeffrey K. Whyatt

The point estimation method can be applied to the safety factor (SF) equation for any specified rock slope failure mode (such as plane shear, step path, or wedge) to obtain reliable estimates of the mean and standard deviation of the SF probability distribution. A gamma probability density function is recommended for modeling this probability distribution, because it allows only for positive values and is flexible enough to provide symmetrical shapes and right-skewed, exponential-type shapes for the SF distribution. The mean and standard deviation define this distribution, which then can be integrated numerically from 0 to 1 to obtain the probability of sliding, PS (portion of the SF distribution where SF < 1.0). The overall probability of failure, PF, for the potential slope failure mass is the joint probability that the rock discontinuities are long enough to allow kinematic failure (PL) and that sliding occurs along the rock discontinuities (PS); that is, PF = PSPL. This method for estimating the probability of sliding is extremely efficient computationally, and thus, expedites slope stability simulation routines used by NIOSH software to stochastically describe rock slope behavior and assist the engineer in designing catch benches for large rock slopes. Enhanced bench design translates into increased operational efficiency and safer working conditions in open pit mines and quarries.

By William W. Adams

Progress made by the quarrying and related industries of the United States during 1939 included increases in the number of men employed and the number of man-hours worked and reductions in the death and injury rates per million man-hours of exposure to risk. Forty-seven States reported quarries in operation; in each of 26 States the industry employed 1,000 or more men. Of these 26 States, 16 reported lower accident rates than in 1938. Among the operations of various types for which separate figures are published in this bulletin, the limestone, lime, and cement groups reported lower accident rates. During 1939, 79,449 men were employed in the quarrying industries. The period of operation of the plants averaged 236 clays per employee, with a total working time that equaled nearly 144 million man-hours. Accidents at the plants resulted in 48 deaths and 5,204 disabling injuries among the workers. Expressed as frequency rates, the accidents represented 0.33 fatality and 36.18 injuries for each million man-hours of work performed during the year. The major cause of fatal accidents inside the quarries was falls or slides of rock or overburden; nine deaths were reported from this cause. Four men were killed by explosives and four by falls of persons. Nonfatal injuries inside the quarries were clue chiefly to handling materials; about one-sixth of the total number at all operations in connection with quarries and related plants were in this class. Flying objects also caused numerous injuries, although only about one-half as many as did handling materials. Next in numerical importance were injuries from falls of persons. Then followed accidents caused by falls or slides of rock or overburden and accidents caused by machinery.

Jan 1, 1941

This paper has peen translated from the Russian by the United States Bureau of Mines and is issued as one of a series of circulars dealing with mining methods and costs in connection with a general study of this subject sponsored by the bureau. The paper presents some interesting features in connection with the methods employed in Russia and describes certain variations in standard methods which might conceivably be applied to a limited extent in this country.

Jan 1, 1930

By E. D. Gardner

"Trolley lines used in connection with electric haulage in mines are a source of danger and many lives have been lost by men accidentally coming in contact with the wires. Usually the wires in metal mines are sufficiently guarded to prevent men from touching them with their person or by pieces of steel which they may be carrying or their shoulders, while walking along the level. However, it is difficult to guard effectively the wires at loading chutes along the haulage ways and in spite of safe guards, chute tappers have been electrocuted through loading bars accidentally touching the trolley line.To overcome this danger the Calumet & Arizona Mining Co., at Lowell, Arizona formely used a hinged V-shaped trough made of 1-inch by 6-inch lumber, that was dropped over the wire in front of the chute, when the cars were being loaded. This arrangement interfered with the easy operation of the chute, and a cut-out device for the trolley line was devised by W. R. Gibson, chief electrician for the company. This cut-out is efficient easily constructed and roes not interfere with the operations at the chutes or with the motors operating on the same level.When the cut-out is open the electric current is carried past the gap by an insulated wire on the opposite side of the drift. A hinged board drops down over the ends of the trolley guard when the slide is open and Prevents anything touching the live wires. About ninety of these cut-outs are now in use in the mine,The levels under the scopes are timbered with drift sets placed 5 feet apart, and the loading chutes take up the space between two sets. All trolley wires in. the company's mines are carried 6 feet above the rails and guarded by two 1/2 by 6-inch boards placed on either side of the wire."

May 1, 1921

By Charles Vaught, Kathleen M. Kowalski

Safety and health professionals from all sectors of industry recognize that training is a critical element of an effective safety and health program. A major concern in the mining industry is how to train both an aging workforce and the expected influx of new miners and mine managers as older workers retire. Thus, a review of some of the basic principles of adult learning may be helpful to mine trainers. This paper discusses the principles of adult learning based on research in education and psychology. It stresses the importance of taking a systems approach to training, focusing on the relationship between the environment and technology, and understanding how workers interact with both. The authors argue that the principles of adult learning and a systems approach are fundamental to the delivery of effective training in the mining industry. Examples of training programs developed by the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health are presented within two broad performance domains: routine and nonroutine skills. Basics of curriculum development are also briefly presented to provide the mine trainer with a template for program development.

Jan 1, 2002

By A. C. Fieldner

This report, the third of a series of annual reports of research and technologic work on coal by the Technologic Branch to be released in this form, covers the fiscal year July 1, 1937, to June 30, 1938. Ever-increasing demands for information on the chemical and physical properties of coals, their proper classification rind adaptability for various uses, their economic evaluation in the complex relationships between the costs of production, distribution, and selling, and their beneficiation and amenability to conversion to more valuable and. new products of commerce have necessitated an appropriate and flexible program. To most these requirements, initiation of new projects and new physical facilities has been made.

Jan 1, 1939

By William W. Adams

The quarrying and related industries of the United States improved their safety record in 1938 by reducing their accident-frequency rate to a lower acid more favorable position than it has occupied at any time except 1935 since comparable accident statistics became available in 1916. The rates for 1935 and 1938 were identical. The number of men employed in 1938, although smaller than in 1936 and 1937, was larger than in any other year since 1930. Volume of employment, as measured by the number of man-hours worked in the industry as a; whole, likewise was larger than in any year since 1930 except 1936 and 1937. Reports from operating companies to the Bureau of Mines, United States Department of the Interior, showed that 77,497 men were employed in 1938, a decrease of 6,597 compared with 1937. This figure represents the average number of employees for the period during which the quarries and plants were active during the year, which in 1938 averaged 223 workdays per employee compared with 241 in 1937. A total of 17.3 million man-days or 133.8 million man-hours of work was shown for the industry as a whole, which indicated a weighted average of 7.75 hours per man-shift. Reports for 1937 showed a total of 158.3 million man-hours for the entire industry and an average workday of 7.81 hours. Accidents resulted in the death of 82 employees, 5 more than in 1937, and in 5,027 nonfatal injuries involving disability for more than the remainder of the day on which the injuries were received. The number of nonfatal injuries was 1,321 less than in 1937. As the number of deaths and injuries was reduced more, proportionately, than man-hours of employment, the accident-frequency rate per million man-hours of work declined, the rate for 1938 being 38.19 compared with 40.59 for 1937. In other words, accident occurrence to the average employee was 6 percent more favorable in 1938 than in 1937 on the basis of actual number of accidents and actual number of man-hours worked during the 2 years.

Jan 1, 1940

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60 percent and 40 percent, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert, and a rigid insert for cleaning the roof bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the coveralls when using either of the inserts.

By Donald O. Capstick

A mineral resource evaluation of the Coyote-Southeast RARE II area (No. 5033) was performed jointly by the U.S. Bureau of Mines and the U.S. Geological Survey in 1981 for the U.S. Forest Service RARE II program. Bureau of Mines personnel conducted a mineral resource inventory of the study area&apos;s mines, prospects, claims, and mineralized outcrops. The study area&apos;s boundaries encompass 51,700 acres on the east flank of the Sierra Nevada and are within Inyo National Forest southeast of the city of Bishop in east-central California. Cretaceous granite underlies most of the area; the remainder of the rocks are metasedimentary. At the contact of the two, tactites formed at many places where carbonate rocks were present; replacement processes produced local scheelite (calcium tungstate) occurrences.

Jan 1, 1983

By Radford B. Langston, John A. Marjerison, Graham C. Howell, Hendrik A. D. Kirsten

Probabilistic design is gaining wider acceptance in the rock engineering community since it allows more rigorous determination of risk relating to ground fall or excavation instability. Risk analysis can be conducted by various means, but the basis is formed by either objectively or subjectively determining probability of occurrence of an event. In the case of rock engineering, this event is either instability or excavation failure. Rock mass classification systems provide objective analysis of data collected on a typically subjective basis that also relate closely to excavation stability. A probabilistic analysis technique is presented that uses statistical distributions of rock mass and material properties, ground support fixture specifications, stress conditions, opening geometry, and ground support installation quality to more rigorously determine probability of failure for an underground opening and the subsequent risk to personnel.

Jan 5, 2007

By John Rusnak, Christopher Mark

Point load testing is used to determine rock strength indexes in geotechnical practice. The point load test apparatus and procedure enables economical testing of core or lump rock samples in either a field or laboratory setting. In order to estimate uniaxial compressive strength, index-to-strength conversion factors are used. These factors have been proposed by various researchers and are dependent upon rock type. This study involved the extensive load frame and point load testing of coal measure rocks in six states. More than 10,000individual test results, from 908 distinct rock units, were used in the study. Rock lithologies were classified into general categories and conversion factors were determined for each category. This allows for intact rock strength data to be made available through point load testing for numerical geotechnical analysis and empirical rock mass classification systems such as the Coal Mine Roof Rating (CMRR).

To alleviate the hazard to personnel and danger to equipment caused by fires on large, mobile vehicles. The Approach: A system which automatically senses a fire at its early stage of development, warns the driver of the danger, and activates fire extinguishers in the zone of combustion, How It Works: The automatic fire protection system utilizes both thermal and optical sensors to detect the heat or light given off by a fire in the area of concern (Fig. 1). The system warns the driver of the hazard and then automatically extinguishes the fire with pressurized S-C class powder. The system can also be activated manually from the operator&apos;s cab or from ground level. Further, the automatic sequencing of the system can be manually overridden by the driver if he determines that the fire sensors have malfunctioned to cause a false alarm.

Jan 1, 1974

By N. I. Jayaraman

High-pressure shrouded sprays were first tested on a bench to determine air-moving capability and dust collection efficiency. The bench-scale tests indicated that at 500 psi and above, the dust collection efficiency, when sampled downstream of a water eliminator, was about 99 pet for two types of nozzles. However, for the same water flow, the induced airflow was about three times greater in one type than in another. Since the only difference in the nozzles was the spray angle, this factor was important in air movement through a shrouded spray. Full-scale model mine tests were then conducted to determine the reduction in dust concentration behind the line curtain and at the operator position produced by high-pressure sprays in a shroud. The shroud was mounted on top of the boom of a model continuous miner, and high-pressure (greater than 500 psi) sprays were installed inside the shroud. The inlet of dusty air to the shroud was open toward the face and the outlet toward the exhaust line curtain. The high-pressure sprays were compared with conventional sprays mounted at the head of the continuous miner and directing water toward the face. The difference at the operator position (opposite side of brattice) was significant in that, under certain conditions, with conventional sprays an increase in respirable dust concentration of 471 pet was noticed compared with dry operation due to rollback from face. High-pressure shrouded sprays, on the other hand, decreased the dust concentrations at the operator position (opposite side of brattice) by 28.2 pct.

Jan 1, 1981

By R. H. Grau, R. B. Krog

The National Institute for Occupational Safety and Health (NIOSH) has investigated the unique ventilation requirements of large-opening mines to help identify and evaluate the effectiveness of various fan types to improve the ventilation and air quality in the underground workplace. Large-opening mines, with their low airflow resistance factors, can be ventilated with free-standing auxiliary fans because airflow pat-terns in these mines are primarily controlled by airflow momentum. The flow characteristics of both vane-axial and propeller fans were investigated and tested at four large-opening mines to assess the effects of fan location on recirculation and entrainment. Each fan type has its own airflow, entrainment and penetrating air-flow characteristics, and operating costs that are advantageous for specific applications. Either fan type can be used for most auxiliary applications. However, this research has shown that the optimum placement and use criteria for propeller fans differ from those promulgated by the U.S. Bureau of Mines (USBM) for vane-axial fans Brechtel et al. (1985)

By Jeffrey M. Listak

The National Institute for Occupational Safety and Health (NIOSH) conducted field tests to evaluate the effectiveness of a wet head continuous mining machine for reducing dust exposure for continuous miner operators. Wet head technology delivers water via sprays to the continuous miner&apos;s cutter head as opposed to traditional standard sprays located on the boom and body of the mining machine. The sprays, positioned directly behind each bit on the cutter head, deliver water at the point of attack, serving to cool the bits during mining to reduce the potential for frictional ignitions. The sprays also flood the coal with water to potentially suppress dust generation. Dust surveys were conducted at several mines to evaluate the wet head&apos;s effectiveness to control respirable dust exposure at the continuous miner operator location and in the immediate return. Results show that the wet head miner improved air quality at both locations to varying degrees in some cases and not in others when compared to a continuous miner with a standard spray system.

Jan 1, 2010