Search Documents

By R. R. Schehl

The Bureau of Mines analyzed the structure of a high-grade metallurgical coke, carbonized at different temperatures in the range 500° to 1,000° C, through X-ray diffraction studies. Growth in the crystallite size with increasing coking temperature was calculated from profile analysis and compared with values obtained from the radial distribution function. The carbonization temperature appeared to have little influence upon the stack height, whereas the layer diameters more than doubled in size between 500° and 1,000° C. These results are comparable to those obtained from other studies of poorer quality cokes.

Jan 1, 1974

By Travis Q. Lyday

During 1981, Ecuador's gross domestic product (GDP) increased by a reported 4.8% in real terms, a slight improvement over that of 1980. In current prices, the CDP in 1981 was estimated at $13.7 billion.2 The inflation rate increased to 15.6% according to official figures, above that of 1980. Ecuador's production of petroleum increased 3% in 1981 compared with that of 1980. The consortium of Corporación Estat al Petrolera Ecuatoriana (CEPE), the state oil company, and Texaco, Inc., produced almost 98% of the total from their Putumayo Basin operations in Oriente, the eastern jungle region. In sharp contrast, output from the Santa Elena Peninsula Fields, where oil was first produced commercially in 1921, continued to decline, producing only 510,000 barrels, a decrease of almost 8% compared with that of 1980.

Jan 1, 1983

Pillars with width to height ratios of less than 1.0 are frequently created in underground hard rock mines. The strength of slender pillars can be estimated using empirically developed equations. However, the equations can provide variable results when the width-to-height ratios approach 0.5. This paper investigates some of the issues affecting pillar strength at low width-to-height ratios in hard brittle rock. The investigation includes an evaluation of empirical pillar strength data presented in the literature and observations of pillar performance in underground limestone mines in the eastern United States, supplemented by numerical modeling in which failure processes and sensitivity of slender pillars to variations in rock mass properties are evaluated. The results showed that the strength of slender pillars is more variable than that of wider pillars. The numerical model results demonstrated the increasing role of brittle rock failure in slender pillar strength. The absence of confinement in slender pillars can result in a fully brittle failure process, while wider pillars fail in a combined brittle and shearing mode. The onset of spalling in slender pillars occurs at or near the ultimate strength, while this is not the case for wider pillars. Slender pillars are shown to be more sensitive to the presence of discontinuities than wider pillars, which can partly explain the increased variability of slender pillar strength. Two examples are presented, which illustrate failure initiation by brittle spalling and the sensitivity of slender pillars to the presence of discontinuities.

By Susan M. Moore

Many challenges are faced by workers in lower-seam (42 inches or less) mines. The lower-seam heights confine mine workers to their knees as they perform their daily tasks such as installing roof bolts, delivering supplies, repairing belt, or cutting coal. Miners working in these lower seams often consider kneepads to be their only line of defense against knee injuries. However, healthy knees do not start and stop with kneepads. Other interventions such as changing postures, proper hygiene, and work station design may also be used to reduce mine workers? risks for developing knee injuries. Incorporating these and many other interventions into a mine worker?s ?way of life? is an important step to ensuring a long, healthy career and retirement. Keeping knees healthy is also a key aspect to reducing costs in low-seam mines as the industry battles rising health care costs, and training/recruitment of replacement workers is time-consuming and costly. Educating the workforce about the possible interventions to reduce knee injury risk is a primary objective for the National Institute for Occupational Safety and Health?s (NIOSH) Pittsburgh Research Laboratory (PRL). Therefore, NIOSH researchers, along with industry and academia, developed a training package to educate the mining community about some possible interventions beyond kneepads that may be used to help decrease knee injury rates. Increased awareness and simple changes are the first steps to reducing knee injuries.

May 1, 2008

By Charlie Wyche

In 1980, gold, silver, and pit and quarry construction materials were the principal minerals produced in the Dominion of Fiji. The combined value of these minerals totaled some $7.2 million,2 over 85% of all mineral production, Production of cement, sand and gravel, and quarry products continued to increase, but gold and silver production from Fiji's only operating mine declined slightly from the previous year's level. Mineral exploration has been carried out by U.S., Australian, British, Canadian, West German, and South African companies since the early 1960's, and a high level of activity was maintained throughout 1980. At the end of 1980, some 40 mineral prospecting licenses covering over 4,300 square kilometers were in force, and 19 applications were under consideration by the Mineral Resources Department. Total expenditures by mining companies on land base projects exceeded $6 million in 1980.

Jan 1, 1982

By Jr. Smith

The equilibrium compositions of product gases for mixtures of air with methane, propane, or ethylene at and around flame temperatures are reported. For each hydrocarbon, compositions are given for five fuel-to-air ratios--two lean, two rich, and one stoichiometric--at five pressures, from 1 to 20 atmospheres, and at an ambient temperature of 25° C.

Jan 1, 1965

By Kung-Lee Wang

SUSTAINED growth characterized the U.S. economy in 1964. Many new peaks were achieved in production, sales, employment, employee earnings, and business profits. At the end of 1964, the economy had experienced 4 years of uninterrupted expansion, and the greatest net gains in output for all postwar cyclical advances had been registered. There were no indications of the various weaknesses which have previously characterized advanced stages of business expansion. Both gross national product (GNP) and national income were 6.7 percent higher than in 1963. In 1964 GNP totaled $628.7 billion, a gain of $39.2 billion over the 1963 figure. On an overall basis, prices rose 1.75 percent in 1964. The real volume of output of goods and services (GNP in constant dollars) increased by 5.0 percent ill 1964; this was more than the 3.8-percent gain in 1963 but less than the 6.6 percent gain in 1962. The 1964 output gain also exceeded the average 3.7 percent annual increase for the postwar period. Congress authorized a two-stage tax reduction designed to further stimulate economic growth and employment. The tax cut favorably affected the 1964 economy in the following ways: By helping to boost personal income, corporate profits, and industrial production; by accelerating the pace of consumer spending and business capital expansion; and by increasing employment, thereby reducing unemployment to 5 percent. Three major problems remained unsolved. These were unemployment of 3.7 million persons, poverty conditions among more

Jan 1, 1965

Objective To develop safety training tools for mine safety and health trainers that can be used for both new-miner training and annual refresher training. Background For the past 3 years, NIOSH has been developing training materials for mine safety trainers in response to gaps identified during stakeholder meetings. Most materials have been directed to the hazards of underground mines, but the recent passage of Part 46 of CFR 30 required new-miner and annual refresher training in aggregate operations. One result was the identification of another audience needing basic information about safety in mining. Trainers characterized trainees in this segment of the industry primarily as young males, many of whom had little work experience. Approach Training specialists from the Arizona State Mine Inspector’s Office approached NIOSH researchers early in2002 about the possibility of a collaborative project to develop safety training materials for new trainees in aggregate operations. A preliminary search of MSHA accident statistics identified over a dozen common hazards that could be targeted in a training video. A storyline was developed for review by safety specialists in the aggregate industry, and a script was written to cover the selected hazards. Although the target audience was primarily new hires, the finished video was also to be relevant to more experienced workers.

Jan 1, 2003

By John H. Hild

"INTRODUCTION Alunite occurs within a radius of 10 miles of Marysvale, Piute County, Utah, in veins and as replacements of igneous rocks. A number of each type of deposit was explored by the Bureau of Mines, in cooperation with the Geological Survey, under the Strategic Minerals program during 1942. The exploratory work comprised geologic and topographic mapping, diamond drilling,,bulldozer and hand trenching, sinking test pits, rehabilitation of old workings, sampling alunite exposures, and constructing and repairing roads.ACKNOWLEDGNENTSIn its program of exploration 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 exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches-are under the supervision of Dr. R. S. Dean, assistant director.With particular reference to this publication, acknowledgment is given to Richard E. Mieritz and William E. Young, who assisted on the project at various times; P. T. Allsman, chief. Salt Lake Division, Mining Branch, who advised on exploratory problems and gave valuable assistance in preparing the report and illustrations; A. P. T. Schumann, for preparing the illustrations; and to Gordon L. Bell, Max Willard, and Eugene Callaghan, of the Geological Survey, who cooperated as representatives of that agency."

Nov 1, 1946

By Travis Q. Lyday

Mineral production in Fiji, a group of 322 volcanic islands and atolls of Melanesia in the southern Pacific Ocean, continued to be dominated by gold. However, the Fijian mineral sector remained a minor factor as a source of export earnings, Government revenues, and employment, generating only 1% of the gross domestic product (GDP), estimated as $1.2 billion.2 The largest and most important mining operation was the Vatukoula gold mine on the north side of Viti Levu, the main island. The Vatukoula Mine has been in prduction since 1932, producing about 3.8 million troy ounces of gold and 1.3 million troy ounces of silver to date. In April 1983, the large Australian mining firm, Western Mining Corp. (WMC), assumed operation of the mine in a joint venture with Emperor Gold Mining Co. Ltd., which operated the mine previously. The WMC takeover of the mine management was expected to bring in additional capital and technological expertise in order to modernize operations, increasing both efficiency and output. During the year, rate of recovery was only about 75% of the gold contained in the ore and only 40% of the contained silver. Mining at the Vatukoula Mine was done using bath opencut and underground methods, with about 60% of the ore mined attributed to the underground operations.

Jan 1, 1985

By Lulie H. Crump

Salient historical data on consumption of fuels and energy have been summarized by State and census district for the years 1960 through 1972. This Information Circular covers States west of the Mississippi, and Information Circular 8704 covers States east of the Mississippi. These data replace previously published compilations of energy consumption statistics by States and districts. Future annual studies are planned using the same Btu conversion factors applied in these two Information Circulars.

Jan 1, 1976

By D. A. Reynolds, L. P. Rockenbach

"The method of analyzing light oil for benzene is fully described by Fieldner and others 4/ and Kester and Kolmes 5/. In this procedure, benzene is determined by shaking 20 cc. of the 79º to 81º C. boiling point cut from the fractionation of the refined light oil with 3 volumes of 98—percent sulfuric acid in an A. S. T. M. separator funnel of the type used for determining water in bitumi¬nous materials. After the mixture has been shaken 5 minutes it is allowed to settle at least half an hour and the acid is drawn off; the residual oil is reported as paraffins and the decrease in volume as benzene. The method has been found satisfactory for light oils from coals carbonized at 5000, 600°, and 7000 C. but does not give accurate, reproducible results for oils from the 800° C. tests.The content of benzene of the 790 to 81° C. cut is high, 90 to 95 percent, for 800° C. light oils, whereas for lower—temperature light oils it is considerably less. Benzene is the most difficult of the aromatics to sulfonate, hence the acid concentration must be maintained above 95 percent to insure complete sulfonation. Sulfuric acid (98 percent) reacts with benzene, but its reaction with paraffins at ordinary temperatures is negligible; however, more concentrated acid will attack paraffins and give erroneous yields of benzene. The reaction between benzene and sulfuric acid forms water that will dilute the acid. The effect of this dilution may be overcome by increasing the acid-to-oil ratio or increasing the strength of the acid. The latter, however, must not be used, because the stronger acid reacts with paraffins."

Mar 1, 1942

In 2005, a total of 739 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). These mines (e.g., potash, gypsum, salt) comprised 5.0% of all operations. ? Mines producing common clay comprised 26.9% (n=199) of all nonmetal mining operations. ? Nonmetal mining operations were located in all states and territories except Alaska, Delaware, Hawaii, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands.

Jan 1, 2008

By R. A. Franks, G. F. Friel, J. C. Edwards, L. Yuan

Five mine fire experiments were conducted in a 2.08m high and 2.90m wide, ventilated mine entry in the National Institute for Occupational Safety and Health (NIOSH)'s Safety Research Coal Mine (SRCM) to determine the effect of the dispersion of carbon monoxide (CO) on mine fire detection. CO measurements were made at distances from 7.6 m to 45.2 m downwind from the fire with diffusion mode CO sensors positioned near the roof. For small intensity fires, less than 30 kW heat release rate, generated by 14 kg coal in a 0.61 m square tray, it was determined that air flow and sensor spacing were significant for fire detection at the 10 ppm CO alarm level. Within 15.0 m downwind distance from the fire, 10 ppm CO alarm values occurred for volumetric air flows less than 11.5 m3/s. However, the 10 ppm CO alarm value did not occur 30.0 m downwind from the fire for air quantities greater than 6.2 m3/s due to dilutive mixing of the CO in the air stream. The criterion that the mine fire alarms occur within 15 min of the onset of flaming combustion could not be consistently met with the 10 ppm CO alarm. This suggests the use of lower CO alarm values, or reduced CO sensor spacings for mine fire protection. It is demonstrated how computational fluid dynamics (CFD) can be used to model the CO dispersion downwind from the fire in support of a plan to optimize sensor spacings.

By H. C. Verakis, M. L. Harris, M. J. Sapko, K. L. Cashdollar

In underground mines, coal dust explosions are prevented by the addition of rock dust sufficient to render the coal dust inert. The National Institute for Occupational Safety and Health (NIOSH) has developed a hand-held instrument that uses optical reflectance to measure the explosibility of a rock dust and coal dust mixture. This instrument is called the Coal Dust Explosibility Meter (CDEM). In this study, NIOSH personnel accompanied Mine Safety and Health Administration (MSHA) inspectors on their routine band surveys in five and three underground coal mines in MSHA District 2 (PA) and District 11 (AL), respectively. While underground, NIOSH personnel and MSHA inspectors used the CDEM to assess the explosibilities of the dust samples. The values of percent incombustible content (% IC) determined by the CDEM agreed well with those obtained later by low temperature ashing (LTA) in both MSHA and NIOSH laboratories. Further, the meter identified some samples as potentially explosible that LTA analysis had found to possess sufficient rock dust for inerting. The CDEM provides more information on the hazards in the mine. Rapid identification of areas with explosible dust mixtures using the CDEM allows for immediate intervention rather than a wait of several weeks for laboratory analysis.

By Russell R. Trengove

In order to extend or delimit the known ore reserves adjacent to the Comet Coalition property on the western slope of the Highland Peak Range about 8 airline miles west of Pioche, Nev., the Bureau of Mines undertook an exploration project of diamond drilling. Production figures from this property, formerly known as the Schodde, are not available, but it has been reported that small amounts of rich silver and gold ore were Shipped by wagon to a smelter in the Salt Lake valley during 1900-1910. Small shipments were reported for the period 1915-1927, also. A study of the Pioche District by the Federal Geological Survey in 1942 and 1943 was the basis for the exploration program of the Bureau of Mines in 1947 This program consisted of diamond-drilling three holes. The total footage was 2,967 feet. No. 1 hole was drilled 1,260 feet, a record depth for diamond drilling in the Pioche District. Silver-bearing lead-zinc sulfide ores are found in the Combined Metals limestone, known locally as the C.M. bed, These deposits have been formed by replacement of the limestone that is inclosed in the Pioche shale.

Jan 1, 1949

By Eugene Frey

"INTRODUCTION The ti taniferous-iron deposits in the Iron Mountain area of the Laramie Range, and particularly the Shanton deposit, were examined by several engineers. 3/ of the Bureau of Mines during 1942, 1943, and 1944. A dip-needle survey also was made early in 1945. 4/ Interest in this property has increased as a result of the exploratory work completed by the Bureau in 1944 on the Iron Mountain deposit, 6 miles northeast of the Shanton property.ACKNOWLEDGEMENTSIn its program of exploration 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 exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Special acknowledgment is due to Paul T. Allsman, chief, Salt Lake City Division, Mining Branch; James A. Marsh, district engineer; Paul E. Pesonen, Frank L. Wideman, and Frank H. Gunnell, Bureau of Mines engineers; and to S. R. Zimmerley, chief, Salt Lake City Division, Metallurgical Branch, for analyses of samples."

Aug 1, 1946

By E. C. Westman

Three-dimensional velocity tomograms were generated on a daily basis to image mining-induced changes to the overburden above a longwall mine. The hypothesis was that a coherent redistribution of seismic velocity, due to the development of high-stress zones, could be imaged at the mine scale. Seam depth was 360 m and source location depth varied from 100 to 1000 m. Sixteen geophones were distributed over a 600 by 600 m square area on the surface above the mine. More than 12,500 events were recorded over an 18 day period. The recorded seismicity provided input for the local-earthquake tomography code, SIMULPS. Eighteen tomograms were generated and high-velocity regions correlated well with high abutment stresses. Additionally, the high-velocity regions were observed to redistribute as the longwall face retreated. These results indicate that velocity tomography can be used to provide a better understanding of temporal changes within a rock mass, and can potentially be used to produce a better understanding of the mechanisms that lead to unanticipated ground failures.

Jan 1, 2008

By Gerald T. Homce, James C. Cawley

This paper updates an earlier report by the authors that studied electrical injuries from 1992 to 1998. The previous information is expanded and supplemented with fatal and nonfatal injury rates and trends through 2002. Injury numbers and rates were used to compare and trend electrical injury experience for various groups and categories. This information allowed identification of at-risk groups that could most benefit from effective electrical safety interventions. The data presented in this paper are derived from the U.S. Labor Department’s Bureau of Labor Statistics’ Census of Fatal Occupational Injuries (CFOI), Survey of Occupational Illnesses and Injuries (SOII) and Current Population Survey (CPS). Between 1992 and 2002, 3,378 workers died from on-the-job electrical injuries. Electricity remained the sixth leading cause of injury-related occupational death. From 1999 through 2002, 4.7% of all occupational deaths were caused by electricity, down from 5.2% in the 1992 to 1998 time period. The cause of death was listed as electrocution in 99.1% of fatal cases. Contact with overhead power lines was involved in 42% of all on-the-job electrical deaths. The construction industry accounted for 47% of all electrical deaths between 1992 and 2002, but showed overall improvement from 1995 through 2002 by reducing its electrical fatality rate from 2.2 to 1.5 per 100,000 workers. An additional 46,598 workers were nonfatally injured by electricity. Contact with electric current of machine, tool, appliance, or light fixture and contact with wiring, transformers, or other electrical components accounted for 36% and 34% of nonfatal electrical injuries, respectively. Contact with underground, buried power lines was involved with 1% of fatal injuries and 2% of nonfatal injuries. NIOSH research aimed at evaluating commercially available overhead power line proximity warning alarms is described. This research is expected to be the initial step for eventual development of a performance standard for such systems.

By Thomas E. Lobb, Harry C. Verakis

This article examines the factors related to injuries due to inadequate blasting shelters and blast area security, and identifies mitigation techniques. The key concepts are:(a) accurate determination of the bounds of the blast area, (b) clearing employees from the blast area, (c) effective access control, (d) use of adequate blasting shelters, (e) efficient communications, and (f)training. Fundamentals are reviewed with an emphasis on analyzing task elements and identifying root causes for selected blasting accidents. Mitigating techniques are presented along with discussions and examples.