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By Aarne Visnapuu

Experimental modifications have been made by the Bureau of Mines on standard pneumatic rock drills to reduce the noise of the air exhaust, drill steel resonance noise, and noise radiated by the drill body. A close-fitting case and muffler around the drill body, consisting of a metallic honeycomb skeleton filled with viscoelastic absorber on the inside and a durable outer shell, provide both exhaust and drill body noise muffling and absorption. Drill steel resonance noise is reduced by a constrained-layer treatment consisting of a tubular metal cover bonded to the ouside of the rod by a viscoelastic filler. Damping alloy components have been developed to reduce metallic resonance noise. Combined, these modifications have reduced the drilling noise level in granite from 115 dbA to 97 dbA. Data are presented on the individual and combined effects of these modifications on drilling noise and performance.

Jan 1, 1975

By W. E. Miller, John Campbell, W. P. Yant, G. W. Jones

"Because of its interest in accident prevention, the U.S. Bureau of Mines cooperates with city officials and utilities in investigating the causes of explosions in sewers, manholes, and other underground openings and in developing means for preventing such explosions. For several years this Bureau has been cooperating with the Edison Electric Illuminating Co. of Boston and the Boston Consolidated Gas Co. in detecting and eliminating combustibles and physiologically harmful gases in manholes in the city of Boston and adjacent territory.These Bureau of Mines investigations° have shown that combustible gases from the usual sources — leakage from gas—distributing systems and from underground tanks and gasoline wastes — can be located and the dangerous conditions remedied by a well—planned, adequately supervised, systematic, and continuous manhole survey. However, other types of gas, which are termed here ""soil"" gases, also occur in manholes and are more difficult to eliminate because they have no fixed origin and because seasonal and barometric changes affect their production and passage into the manhole space. These gases appear to be produced by bacterial and fermentation or through reactions of entrapped air in the soil. Soil usually abnormally high in carbon dioxide and low in oxygen, and contain varying amounts of methane. They are especially clangorous to men entering manholes because they lack sufficient oxygen to support life. Owing to the difficulty of constructing gastight manholes the most feasible method for eliminating soil gases from manholes is by ventilation. Consequently the Bureau of Mines initiate 4 study of natural ventilation methods for the removal of these gases from manholes and also for taking care of unforeseen accumulations of combustible gases and vapors.The following factors were considered by the Bureau to be important to the natural ventilation of manholes: (1) Relation of area of ventilation opening* to the capacity of the manholes, (2) size and shape of the manhole, (3) design of the ventilation opening (4) and velocity, and (5) weather conditions."

Jun 1, 1936

By C. K. Rose

A hydraulic scaling rig was placed in operation at the Bureau of Mines oil-shale mine near Rifle, Colo., in 1953. The rig consists of a self-leveling platform mounted on a hydraulic-powered boom. The boom is mounted on the bed of a diesel truck. The equipment provides a movable work platform from which two men can work in safety and comfort while barring loose rock from the backs and walls of the rooms, pillars, and haulageways. INTRODUCTION As a part of its synthetic liquid fuels program the Bureau of Mines has developed a mine in the richer oil-shale beds of the Green River formation near Rifle, Colo. An important part of the work of the Oil-Shale Mining Branch is investigation of techniques for low-cost mining of oil shale on a commercial basis. It is evident that scaling loose rock from the high backs and walls of the mine represents a portion of the direct mining cost. This paper describes the development of a scaling rig for operation in the upper heading of the mine, which is 39 feet high.

Jan 1, 1954

By Phyllip Worley, Frank E. Chase, Christopher Mark

The Harris No. 1 Mine, located in Boone County, WV, has been longwalling the Eagle Coalbed for over 30 years. Harris has experienced numerous interactions associated with the extensive room-and-pillar and longwall mining operations which have been conducted in the overlying No. 2 Gas Coalbed. The problems have included roof falls, excessive rib sloughage, and gateroad and bleeder entry closure. A detailed evaluation of the multiple seam experiences at Harris No. 1 Mine was conducted as part of the National Institute for Occupational Safety and Health (NIOSH) nation-wide multiple seam mining case history data base. One observation from the Harris gateroad case histories was that smaller, critically loaded, upper seam pillars seemed to cause more severe ground conditions than did wider pillars. The LaModel program was used to investigate this supposition, and the results confirmed that “critical” sized pillars do transmit the highest amounts of stress to adjacent seams. In addition, the data suggest that the probability of a major multiple seam mining interaction increases when the depth of cover is 1,000 ft or greater and when the Eagle seam pillars have a Analysis of Longwall Pillar stability factor less than 1.50.

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.

By T. J. Driscoll

In this Bureau of Mines investigation, the electrochemical polarization behavior of Fe and Fe-1BCr has been characterized in rigorously controlled 1[N] H2S04 solutions stirred with oxygen or an inert gas. Samples that under-went various levels of corrosion or passivation were examined using Auger electron spectroscopy (AES) and ion sputtering. Passivation of iron occurred at a potential of approximately 0.6 volt (1) in poorly stirred, oxygen-saturated solutions for forward polarization (scanning from cathodic to anodic potentials); (2) in pH-adjusted (increased), well-stirred, oxygen-saturated solutions for forward polarization; and (3) in well~ and poorly stirred, oxygen-and helium-saturated solutions for reverse polarization. Passivation of Fe-18Cr occurred at a potential of approximately -0.1 volt in helium-, nitrogen-, and oxygen-saturated solutions for all cases of forward polarization and most cases of reverse polarization. Elemental depth profiles obtained from AES sputtering measurements indicated that films or adsorbed species were present on iron samples in solution subjected to open-circuit, active, and transpassive corrosion, cathodic reduction, and passivation. This conclusion was reached by considering the distribution of the solution species, primarily sulfur, in the films, which were composed primarily of iron and oxygen. Sulfur was present throughout the films on actively corroding samples, in the outer regions of films of passive and transpassive samples, and on the film surfaces of open-circuit and cathodically reduced samples. For Fe-18Cr, sulfur was found on the surfaces of films on passive samples only, indicating that only the passive samples had films on their surfaces in solution. The films on electropolished and passive Fe-1BCr samples had the largest chromium concentrations, estimated to be approximately 45 at. pct, with less chromium in films of cathodically reduced, active, and open-circuit samples, in that order.

Jan 1, 1979

By Donald P. Blasko

The Bureau of Mines investigated two areas of the Alaska Peninsula (Iniskin Peninsula and Becharof Lake) where oil and gas seeps were known to occur in an attempt to determine (1) whether the seeps are still active and (2) the amount of bitumen contained in the drainage leaving the seeps. The oil, water, oil-water, and gas were sampled and analyzed. Five oil samples were taken at four separate oil seeps. The API gravity of the oil ranged from 8.90 to 21.4° and the sulfur content was from 0.12 percent to 0.59 percent. Four of the seven gas samples obtained revealed fair high caloric values, ranging from 746 to 924 Btu/cu ft, and averaging 844 Btu/cu ft. A total of 44 water samples were obtained. Bitumen content of the water was as high as 9,773 mg/l at one seep, but averaged less than I mg/l where the seep-drainage water entered the Gulf of Alaska.

Jan 1, 1976

By W. A. Cole

This report covers the preliminary phase of an investigation of clays, shales, and certain rocks in Wisconsin to determine the feasibility of processing lightweight aggregate in the State. The study was extended to include rotary-kiln testing of a limited number of shale samples, and to an appraisal of the Maquoketa shale resources in eastern Wisconsin. A total of 45 samples of clays, shales, and other argillaceous rocks of Wisconsin were tested. The lower Maquoketa shale is the only material found to date that offers possibilities as a source of material that can be processed in a rotary kiln for lightweight aggregate. Bedrock occurrences of the Maquoketa shale are found in the eastern and southwestern parts of the State. The populous southeastern region of Wisconsin presents a large potential marketing area for lightweight aggregate. For this reason special study was directed to the Maquoketa shale in the eastern district.

Jan 1, 1961

By J. J. Demeter

Anthracite from the four producing regions in Pennsylvania was both ashed in the laboratory and burned on a chain-grate stoker to determine the sulfur-retention properties of its ash. The retention of sulfur in laboratory-prepared anthracite ash was shown to be related to ashing temperature and to the amounts of sulfur and calcium present in the coal. At the usual laboratory ashing temperature of 750° C sulfur retention ranged from 0.8 to 13.2 percent of the total coal sulfur. Sulfur retention in the ash was negligible, o to 0.3 percent, at 1,200° C, which is the thermal decomposition temperature of calcium sulfate; thus calcium sulfate does not form and cannot serve as a sulfur-retaining agent. In several tests the anthracite was mixed with 6 or 10 percent dolomite prior to firing in the chain-grate stoker. The dolomite did not improve sulfur retention owing to the high temperature in the fuel bed. Sulfur retention was, however, related to the unburned carbon in the ash. The relationship of the percentage of original coal sulfur retained in the ash (Y) to the percentage of the original carbon in the coal remaining in the ash (X) is expressed by Y = -0.579 + 0.914X. The percentage of sulfur retained is almost directly proportionate to the percentage of original coal carbon in the ash.

Jan 1, 1968

By Kung-Lee Wang

The 1963 performance of the United States economy was impressive. The year was one of continued growth unmarred by a recession. By the end of 1963 the economy's expansion had already lasted almost as long as the 1954-57 upswing, and the net gain in output since the trough in activity in early 1961 compared favorably with most earlier postwar cyclical advances. There was no indication of any slow- down at yearend. Both gross national product (GNP) and national income in 1963 were 5 percent higher than in the previous year. GNP totaled $584 billion, a gain of $28 billion over 1962. Real output of goods and services rose 3.4 percent over the year. Price increases continued to be moderate. Production, employment, personal income, and corporate profits all registered new but unemployment continued high at 5.5 percent and the prospects for improvement remained poor. The economy again failed to use its full potential. Current value of mineral production kept pace with the economy. The constant dollar value of mineral production gained more than real GNP because of the relatively stable price of minerals. Mining production achieved a new high in 1963. Steel production totaled 110 million tons, 12 million tons above 1962, making 1963 the first 100- million-ton year since 1957 and lifting the steel-associated minerals group upward. The gain in ferrous metals mining was insufficient to compensate for the decline of nonferrous metals mining resulting in an insignificant decline in the metal mining total as a whole. The upsurge of construction material minerals output, with an assist from chemical and fertilizer minerals, accounted for peak production of

Jan 1, 1964

By Steven J. Page

The increasing concern for dust control in metal and nonmetal mining prompted the Bureau of Mines to investigate the dust suppression technique of applying foam to face drilling and crushing operations in a gypsum mine. Previous attempts to achieve effective dust control on face drills using other techniques, such as dry collection and boom-mounted external water sprays, have not been successful. The largest problem encountered when using these techniques has been the lack of sustained effective dust capture at the face. Results for two faces studied show that injection of the foam through the drill steel provided an average dust reduction of 95 pct. However, the use of foam on the crusher provided no dust reduction at the operator's position (because of good local ventilation) and a 27-pct average dust reduction for two feeders at a location midway between the operator's position and the crusher. The conclusions obtained from this study are that (1) foam can be an extremely effective dust control technique when used on localized dust sources such as dust generated within a blasthole during drilling, and (2) foam is only marginally effective as a dust control technique when used on nonlocalized dust sources such as dust generated during the feeder-and-crusher operation.

Jan 1, 1981

By M. J. Mechling, H. J. Sloman

"INTRODUCTION The practicability of providing safer methods of underground transportation for mine workmen and officials has been given much thought in recent years by advocates of safety, health, and efficiency. Numerous fatalities and disabling injuries have resulted from falls of roof, personal contact with both electrical conductors and timbers, and improper position or conduct of passengers while they were in man-trips. Unfavorable atmospheric exposure due to high-velocity air currents and sudden changes in temperature may adversely affect the health of mine workmen if they are transported in unprotected Cars.Recent installations of protected, man-trip cars, wherein such cars have been utilized to haul men to and from their stations in the mine, have resulted in a large reduction in exposure to haulage hazards. Where special-built cars have been used the probability of injuries to men during transportation in man-trips has been decreased, and the morale of the employees has been improved. A number of man-trip cars are in service in the coal-mining regions; those described in this circular are typical examples of a few installations."

Feb 1, 1948

By J. D. Davis

From the chemist's point of view it would be ideal if specifications for coke for any stated purpose could be written on the basis of chemical composition and burning characteristics. Unfortunately this is not possible. In fact, the physical properties of a coke are often of such major importance as to render any specified chemical requirements totally inadequate to show the quality of coke desired. For example, a furnace coke may admirably fill all chemical requirements, such as for low phosphorus, sulphur, moisture, and high fixed carbon, and still be too soft to support the burden of the furnace without excessive crushing. Again, a domestic coke though a good fuel as judged from Chemical analysis, may be of unmarketable size. Thus one can not define the quality of a coke for a specified purpose without taking into account both its chemical and physical characteristics even when this has been done the specification may fail because neither coke user nor producer can accurately define by quantitative tests the qualities most desired. In other words, there is need of accurate test methods for measuring the properties of coke and, what is equally important, for correlating the results with the behavior of the coke in use. Coke quality is determined by the kind of coal used, the coking process, and the type of equipment used in the coking process. Chemical analysis of the coals, together with small-scale coking tests, will give a good indication of their suitability; but, in general, coke must be produced on an industrial scale and tested in the equipment for which it is intended before conclusive information as to its quality is obtained.

Jan 1, 1928

By J. P. Conway

The yielding-rock-bolt concept, as developed in South Africa, consists of a smooth-bore die or collar fitted to a standard rock bolt. Laboratory testing at the Bureau of Mines Spokane Mining Research Center under slow and fast strain rates showed that extrusion loads can be controlled by varying the configuration of the die bore and that theoretical analysis (using basically Sachs' theory of wire drawing) predicts extrusion loads of the different die-bore configurations. A derived equation, based on this research, can be used for designed die-thread combinations for any desired extrusion load. Dynamic loading resulted in slightly higher loads (15 percent) than static loading. The strain hardening effect, which increases yield and ultimate strength, was partly offset by adiabatic heating of the threads, which decreases strength.

Jan 1, 1975

Active and abandoned mine sites can be an irresistible- - and sometimes deadly - - draw for outdoor enthusiasts, particularly children and young adults. Despite repeated warnings, posted signs, and fencing, tragedies involving accidents on active and abandoned mine property continue to make headlines, especially with the arrival of warmer weather and the summer months ahead. Over the last few years, there have been dozens of tragic incidents involving children and adults ventur­ing onto active and abandoned mine property. They include: A 16-year-old youth suffered fatal injuries after his all-terrain vehicle became airborne in an accident at a gravel mine near Albany, New York. A young boy was electrocuted when he contacted a high-voltage power line while sliding down a stockpile at a sand and gravel mine in Grand Island, Nebraska during its off-shift hours.

Jan 1, 1999

By Samuel P. Harteis, Eric S. Weiss

The National Mining Association and the Mine Safety and Health Administration requested that the National Institute for Occupational Safety and Health (NIOSH) conduct full-scale evaluations of a recently developed carbon fiber-reinforced polymer (CFRP) reinforcement technique for upgrading existing mine ventilation seals to withstand an explosion pressure of 50 psi or greater. The evaluation was conducted in the NIOSH Pittsburgh Research Laboratory’s Lake Lynn Experimental Mine (LLEM) near Fairchance, PA. The purpose of the evaluation was to determine the blast resistance of the CFRP reinforcement technique, designed to increase the strength of two types of existing 20-psi-rated in situ mine ventilation seals. Two candidate ventilation seals were selected to represent the 20-psi alternative seal designs typical of those used in mines prior to July 2006. Installed within the LLEM were (1) a 4-ft-thick pumpable cementitious foam seal using material with a designed 150- to 200-psi average compressive strength at 28 days and (2) a 24-in-thick, low-density cementitious block seal with a center pilaster and keyed to the floor and ribs. The materials necessary for the CFRP reinforcement technique were then installed on the outby (active) side of each seal, and the seals were subjected to explosion overpressures. Both seals with the CFRP reinforcement retrofit successfully withstood explosion pressures of 60 psi or greater during the full-scale evaluations in the LLEM.

Jan 1, 2008

By Allen D. Look, Alan A. Sharp

"Churn drills for blast-hole drilling are important to the operation of most open-pit metal mines, but certain hazards are created through their use that cause fatal and nonfatal accidents.2/ The purpose of this circular is to present a code of safe practice prepared and followed at a large Arizona open-pit copper mine, where safety is recognized as a definite operating problem. Such a code, based upon a thorough study of available published information as well as practical experience gained from accidents and near accidents, is the result of considerable effort and monetary expenditure. It is hoped that other operations using churn drills may benefit by the code presented, either in comparison with existing rules or in the preparation of new operating instructions.The code presented is in use at the Morenci Branch of the Phelps Dodge Corn., Morenci, Ariz. Similar codes are used at the New Cornelia Branch, Ajo, Ariz., and in the waste-pit operation at the United Verde Branch, Jerome, Ariz.The authors gratefully acknowledge the cooperation of the Phelps Dodge Corp., whose personnel made: possible the collection of information included in this circular. Special acknowledgment is due Paul Simmons, safety engineer, and 3. U. Larsen, general drilling and blasting foreman, Morenci Branch, Morenci, Ariz.The importance of churn drills in Arizona mining is apparent when it is realized that at all the open-pit copper mines blast holes are drilled with this equipment. At Morenci, approximately 98 percent of the ground is broken by primary blasting of churn-drill holes.There has been a growing tendency in Arizona's copper-mining industry to change from underground to open-pit mining, with consequent increase in the use of churn-drill blast holes for primary blasting.3/Thirty-three churn drills are in use at Morenci for blast-hole drilling. The drills operate with 440-volt alternating current, and trailing drill cables, in 500-foot sections, connect with the portable drill transformer station.4/ Three Diesel-driven churn drills for drilling prospect holes also are in use. About 25 churn-drill shifts are operated currently on a three-shift basis. Ordinarily, a two-man crew is assigned to each drill; however, with prospect-drill crews a third man is added to handle the sampling.Benches are carried at a uniform height of 50 feet. Churn-drill holes are 9 or 12 inches in diameter and about 60 feet deep. The holes are 18 feet apart in hard waste and 21 feet in soft waste and ore, with toes from 11 to 13 yards at the shovel grade. Both the hole spacing and the toe have been increased gradually, until they are now 2 yards longer than in 1940. The average ground broken per hole is 3,500 tons, or 60 tons of ore per foot of hole drilled. The holes are drilled 10 feet below the bench to avoid leaving hard bottom, which requires secondary drilling and blasting.Starting with a 12-inch casing, the prospect holes average 1,200 to 1,500 feet in depth and terminate with 6-inch casing; the deepest hole drilled to date went to 1,735 feet.In addition, churn-drills are used at Morenci to drill blast holes in the silica pit, limestone quarry, and the tailings dam. Other irregular applications are the drilling of holes to set trolley roles and for concrete piling in building foundations."

Jan 1, 1950

By E. C. Lane

This report on properties of commercial motor fuels is the twelfth in a series made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the United States Department of the Interior. The first report contained data on motor gasolines sold during the winter of 1935-36.V The -present report, covering the summer of 1941, presents analytical data for 1,857 samples, representing the products of approximately 135 companies. As in previous surveys, these companies include both large and small suppliers. In addition, the Pacific coast is represented by data averaged by the Pacific Coast Technical Group before being submitted, and these data are published exactly as they were received. Conforming to previous surveys, the data cover three groups of samples -- regular-price, premium-price, and third-grade gasolines -- and each group has been aver aged separately. The number of samples, items, and brands comprising each group, exclusive of those of the Pacific coast, are as follows: Regular price, 1,010 samples, 291 items, and 86 brands; premium price, 577 samples, 263 items, and 78 brands; third-grade gasoline, 270 samples 159 items, and 74 brands. The meanings of these terms as used in the surveys are as follows: Sample: The individual supply of gasoline obtained at the filling station and analyzed in the laboratory.

Jan 1, 1942

By N. F. LeJeune, Earl C. Lane

This is the third of a series of reports on a survey of petroleum prod- ucts manufactured on the Pacific Coast from California crude oils. California crudes differ in many characteristics from the petroleum produced in the other parts of the United States, and the claim has been made that some of the present Federal Specifications for petroleum products tend to discriminate against Cali- fomia products. The purposes of the present survey are to determine what par- ticular specification requirements Califomia petroleum products characteristical ly fail to meet, how widely the products deviate from these requirements, and if possible to show whether the fault lies with the specifications or the products, or along what lines investigation to determine this question should proceed. The first report of the series gave the physical and chemical properties of the samples of gasoline and mineral spirits. A second report**, gave the physical and chemical properties of samples of lubricating oils. The present report deals entirely with burning and fuel oils. The refin ing companies have continued their very cordial and helpful cooperation. Seven samples of kerosene, four samples of Diesel fuel and eight samples of fuel oil were obtained. The methods of analysis used are those adopted by the Interdepartmental Petroleum Specifications Committee, published by the Bureau of Mines in Technical Paper No. 323. The specifications used for corparison are those officially adopted by the Federal Specifications Board for the use of the various Depart- ments and Independent Establishments of the Government, effective February 3, 1923, and published by the Bureau of Mines in Technical Paper No. 323, Part 1. Specific gravity, degrees A.P.I., viscosity and other special tests al- though not required by the specifications have been given for comparison. All temperatures are recorded in degrees Fahrenheit. Tables have been prepared giving data on physical and chemical propertios of the individual samples. Before each table the classification and specifica- tions for the particular class of oil considered in the table are given. Follow- ing each table, brief notes show wherein samples deviate from specification re- quirements.

Aug 1, 1923

By Steve Iverson, Jeffrey C. Johnson, Henry Rodriguez, Rene Rodriguez, Michael Lhamond

To reduce fatalities resulting from personnel falling into voids formed above feeders in coal piles, the National Institute for Occupational Safety and Health at the Spokane Research Laboratory established a project to monitor coal surge piles to detect the formation of voids. A resistivity imaging method has been developed by GECOH Exploration, of Lexington, KY, in which a geophysical technique known as vertical electrical sounding (VES) is used to scan for these voids. VES operates by measuring the electrical field produced by a current in the ground at the bottom of the coal pile. This paper summarizes the results obtained from a field-scale test and shows that mapping voids within a coal pile is possible.