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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 G. L. Oldright

This paper is the thirteenth of the series on Smelting in the Lead Blast furnace, and the third of the series on Handling Zinciferous Charges. Two other papers have been written on the Rate of Descent of the Stock Column, and Formation of Accretions. These are Reports of Investigations 2963 and 3094, for the Tooele plant and the Bunker Hill plant, respectively.

Jan 1, 1934

By E. J. Gleim

"Information gathered during recent months by field men of the U. S. Bureau of Mines shows that in one State alone there have been 71 fatalities from electrical causes during the last 51/2 years, of which 55 were from contact with mine trolley wires operated at 250 volts or less, direct current. The 1928 law relating to the guarding of trolley wires in the-mines of this particular State reads: ""All trolley wires carrying a voltage of class 2 must be properly shielded except where the same are at least 61/2 feet above top of rail."" Class 2 voltage is defined as being ""between 300 volts and 600 volts direct current, or 240 volts and 480 volts alternating current."" From this it may be inferred that no guards are required, for 250-volt trolley wires, and the natural conclusion to be drawn is that the lack of guards or shields must be held responsible for these fatalities. To prevent fatalities from this source, it has been advocated that every foot of trolley wire in mines should be guarded. While some such drastic step may appear to be amply justified, a closer examination of the records shows that lack of guards is not entirely responsible but rather that carelessness and neglect in the observance of certain well-established simple rules concerning installation and location of trolley wires must also bear a share in the responsibility. In -other words, if trolley wire is installed carelessly and its maintenance neglected, failure may be expected of any guards that have been put up.There are a-number of factors affecting safety as related to trolley wires in mines, among which the following may be enumerated.1. Installation relative to track and passageways.2. Guarding.3. Maintenance.4. Discipline.Acknowledgment is made to D. Harrington and K. L. Marshall of the safety division of the bureau for assistance given in securing data on cost of installing guards for trolley wires.The statement that fatalities should not be charged in every case to lack of guards is supported by the following example: A man operating a locomotive was electrocuted when the trolley wheel jumped the 250-volt trolley wire and allowed it to sag against his shoulder. He was sitting in the regular place provided in the locomotive, but the wire was 11 inches inside of the rail and only 39 inches above it where the wire touched him, or 11 inches from the roof at a distance of 12 feet from the nearest hanger. The accident occurred between two hangers 44 feet apart, and the trolley wire was inside the rail over the entire distance, being 2 inches inside at one hanger and 10 inches inside at the other hanger. A bolt in the roof indicated that there had been a hanger at one time between the two on the 44-foot span.This example is a violation of good practice in the installation and maintenance of trolley wire. In the first place the wire should have been outside instead of inside the rail. In the second place there should have been at least one intermediate hanger so that the span would not be so great and the sag would be reduced. Furthermore, it is possible that the wire was not taut enough even when the intermediate hanger was in place.To provide a degree of safety for men in the mines certain coal-mining States, recognizing the need, have enacted laws to regulate the installation of trolley wires. These limit the distance that the wire must be kept outside and above the rail. Thus, the 1927 mining laws of Ohio specify that:"

Apr 1, 1932

The general nature of the special constructional features that are required to provide safety from explosion hazards on machines approved as permissible by the Bureau of Mines is fairly well known to mining men who are at all interested in safety. These requirements are outlined in the schedules under the provisions of which the investigations of such machines are conducted. Also, the method of conducting inspections and tests of such machines has been described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine Type Electrical Equipment for Permissibility, published in 1929. A more detailed knowledge of the special safety features of a particular machine is often useful and sometimes essential for inspectors, safety engineers, maintenance men, and engineers in selecting machines for a particular application. Three bulletins that give information of this nature have been-published by the bureau, viz., Bulletin 313, Permissible Storage-Battery Locomotives and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 382, Permissible Coal-Cutting Equipment. Report of Investigations 3309, Permissible Electrically Operated Air Compressors, which contains similar information, was issued in August 1936, and a Report of Investigations 3326, Permissible Electrically Operated Room Hoists, was issued in January 1937. Thus, the present paper is the third to give detailed information concerning permissible machines of types not included in bulletins, and covers all the rock-dust distributors approved prior to October 1, 1936.

Jan 1, 1937

By P. E. King

The U.S. Bureau of Mines is conducting an ongoing research project to better understand the phenomena involved within electric arcs utilized in electric furnace steelmaking. With a better understanding of the physical and electrical characteristics involved, dynamic or predictive control of electric arc furnaces may be possible. A mathematical model is presented, but not solved, and the system of coupled equations is analyzed. Characteristic parameters are used to determine relative importance. In this manner, significant quantities are dermed. The parameters found to contribute little to the system of equations of motion are ignored. A resultant simplified system is identified, and directions for further study are indicated toward control of electric arc furnaces.

Jan 1, 1990

By Michael S. Miller

During U.S. Bureau of mines mineral investigations, in 1981 and 1983, no mines, prospects, or mineral resources were identified in the Little Sand Spring Wilderness Study Area (WSA). Placer gold values in near-surface samples from alluvial fans within or near the WSA contained no more than 66 cents gold per cu yd, at $400 per troy ounce gold price. Sand and gravel and carbonate rocks occur in large quantities, but transportation costs to distant markets preclude their classification as resources. Nitrogen, lithium, clay, pumice, perlite, aragonite, and agate occurrences in the WSA are small or low-grade. The Silvia Mine, adjacent to the WSA contains gold-, silver-, copper-, and lead-bearing shear zones which strike toward the WSA. INTRODUCTION The Little Sand Spring WSA, encompassing 33,500 acres, is approximately 56 mi east of Big Pine, California, by paved and graded dirt roads (fl;. 1). Elevations range from 2,600 ft in Death Valley Wash to 5,600 ft along the California-Nevada boundary. The nearest permanent facilities are at Grapevine Ranger station and Scotty's Castle (Death Valley Ranch), about 9 and 11 mi, respectively, south in Death Valley National Monument.

Jan 1, 1983

By H. F. Yancey

A relatively large proportion of the coal produced 1n the State of Washington, especially in the coking coal areas is of fine size; hence washing by means or coal-washing tables to reduce the ash content is commonly practiced. For this reason the program of research in coal washing conducted jointly by the U. S. Bureau of Mines and the College of Mines, University of Washington, has given special attention to the mechanism or the separation of coal from its impurities as effected by the coal-washing table with the object of increasing its efficiency. Previous work has evaluated the role of stratification the influence of size, specific gravity and respective shapes of particles in the feed, and the affect of hindered-settling classification of the feed prior to tabling.

Jan 1, 1931

By P. W. Jeran, C. M. McCulloch, Maurice Deul

The natural vertical fracture sys tem in bituminous coalbeds is called cleat. Cleat orientation commonly controls the direction of mining with major development paralleling the face cleat. Previous researchers have categorized the origin of cleat as endogenetic, relating the origin of cleat to compaction and coalification, and exogenetic, relating the origin of cleat to tectonic forces. In the coalbeds studied for this report it was found that tectonic forces were the controlling factor of cleat formation. Face cleats were formed as extension fractures during structural deformation, and butt cleats, as release fractures during erosion and uplift. The face cleat of the Pittsburgh coalbed rotates from N 80° W in north- western West Virginia to N 57° W in southwestern Pennsylvania ; the face cleat maintains a perpendicular orientation to the shifting axial trend of local structures . Cleat orientation in other bituminous coalbeds in Virginia, Utah, Oklahoma, and Central Pennsylvania showed a similar relationship to local structure. Directional permeability of coal is directly related to cleat. Holes drilled perpendicular to the face cleat yield from 2.5 to 10 times the amount of gas released as compared with holes drilled perpendicular to the butt cleat.

Jan 1, 1974

By Edward L. McHugh

In 1986, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 5-acre Zwagg Island Wilderness Study Area (OR-12-14) in order to evaluate its identified mineral resources. The study area is located in Curry County, OR, immediately west of Brookings. There is no evidence of mining activity on or near Zwagg Island, and no mineral resources were identified. The steep-sided, flat-topped island is normally accessible from the mainland by way of a sandy beach. The island consists mainly of marine sandstone, mudstone, and conglomerate of the Jurassic Dothan Formation. Dothan Formation sandstone has been used locally as construction material. Rock along the coast has also been used for construction of jetties to improve harbor access; additional work has been proposed at the port of Brookings. Although suitable for other construction uses, stone from Zwagg Island would probably not meet physical requirements for jetty stone. Development of a stone resource on the island is unlikely.

Jan 1, 1987

By Paul L. Campbell

Investigations by the Federal Bureau of Mines of methods of upgrading tar obtained by low-temperature carbonization of lignite showed that ß,ß?-oxydipropionitrile, ß,ß?-iminodipropionitrile, and ß,ß'-thiodipropionitrile were effective solvents for extracting aromatics (aromatic hydrocarbons plus polar compounds) from coal-tar neutral distillate fractions. Batch extraction showed that these solvents extracted approximately the same percentage of aromatics from various neutral oil fractions boiling between approximately 170° and 350° C. In continuous countercurrent extractions using oxydipropionitrile and iminodipropionitrile, approximately 30 to 35 vol.-pct, and 65 to 70 vol.-pct, of the aromatics in 170° to 350° C. neutral distillate oil were extracted at room temperature when solvent-to-oil ratios were 2:1 and 12:1, respectively. As the concentration of aromatics in the neutral distillate oil fraction decreased, the capacities and, to some extent, the selectivities of these solvents for the remaining aromatics decreased. Aromatics were isolated from the extracts and the solvents recovered by washing the extract fractions with a low-boiling paraffinic hydrocarbon such as heptane, using hydrocarbon-to-extract ratios of at least 2:1. The heptane wash removed most of the aromatics but only part of the polar compounds (compounds containing oxygen, sulfur, and nitrogen) from the extracts. The recovered oxydipropionitrile and iminodipropionitrile, containing polar compounds, were effective in extracting aromatics from neutral distillate oils. The contaminated solvents showed essentially the same capacities and selectivities as the pure solvents.

Jan 1, 1961

By Frank E. Chase, Deno M. Pappas, Christopher Mark

Multiple seam interactions are a major ground control hazard in many U.S. underground coal mines. The two most common types are: • Undermining, where stress concentrations caused by previous full extraction in an overlying seam is the primary concern, and; • Overmining, where previous full extraction in an underlying seam can result in stress concentrations and rock damage from subsidence. The National Institute for Occupational Safety and Health (NIOSH) has completed a major study aimed at helping to identify the location and likely severity of these interactions. In the course of field visits to mines throughout the U.S., more than 300 multiple seam case histories were assembled into the largest data base of multiple seam case histories ever collected. These data were analyzed with the multivariate statistical technique of logistic regression. The study also employed LaM2D to estimate the multiple seam stresses, ALPS and ARMPS to determine pillar stability factors, and the CMRR to measure roof quality. The study resulted in the development of a computer program, called Analysis of Multiple Seam Stability (AMSS), which can help mine planners to evaluate each potential interaction and take steps to reduce the risk of ground control failure. AMSS first evaluates pillar design by calculating the single seam Stability Factor (SFSS) using ALPS or ARMPS. It also automatically generates a LaM2D analysis that provides the additional multiple seam stress so that the final, multiple seam SFMS can be determined. The second part of the AMSS procedure builds upon the statistical findings that overmining is much more difficult than undermining, isolated remnant pillars cause more problems than gob-solid boundaries, and weaker roof significantly increases the risk of multiple seam interactions. AMSS quantifies these effects and predicts the outcome in terms of three levels of risk: GREEN (where a major multiple seam interaction is considered unlikely), YELLOW (where adding a pattern of cable bolts or other equivalent supplemental support could greatly reduce the probability of a major interaction.), or RED (a major interaction should be considered likely, and it may be desirable to avoid the area entirely).

By R. A. Isberg, D. A. Parrish, H. Kramer

This report describes the design and implementation of UHF radio and closed-circuit television systems in the Black River room and pillar limestone mine near Butler, Pendleton County, Kentucky. Prior to designing the radio system, measurements of signal attenuation on 812 and 466 mHz were made in the slope tunnel and in the straight and level crosscuts in the mine. Two distributed antenna systems fed by two sets of base stations provide approximately 75% coverage of the mine. Passive reflectors are used for extending signals into intersecting crosscuts and two-way signal boosters will be used to extend signals to the perimeter and obstructed areas of the mine. Fourteen mine vehicles were equipped with mobile radios equipped with digital identification, alarm and status encoders. Fifteen portable transceivers also were used. Six closed-circuit television cameras provide surveillance of critical transfer points of the belt conveyor system, and the loading dock at the base of the slope and an ash disposal area in the mine. Two-way radio communication and closed-circuit television have saved considerable man. hours, increased production, reduced maintenance costs and enhanced safety. Innovative developments were the use of passive reflectors and two-way signal boosters for extending signals into intersecting crosscuts, development of lightweight signal margin measuring equipment, modifications of mobile digital encoders to automatically send status information from mine vehicles such as numbers of loads of ore delivered, hot engine, etc., and the use of CATV technology for multiplexing audio, digital and video signals onto coaxial cables from the surface to the mine.

Jan 3, 1981

By A. B. Hooker

All State mining laws require that flame safety lamps be used in gassy mines; the laws of some States require that safety lamps be kept for emergencies at every coal mine, whether gassy or nongassy. The use of the flame safety lamp has been widespread because it is the only defice readily available for detecting both the presence of methane and deficiency of oxygen. This paper reports the results of an investigation by the Electrical Section, in cooperation with the Gas Section, of the Pittsburgh Experiment Sta¬tion relative to the behavior of permissible flame safety lamps in mine atmospheres deficient in oxygen and the effects of methane5 on the detection of Oxygen deficiency.

Jan 1, 1937

By Virgil J. Stachura

The Bureau of Mines has investigated techniques and instrumentation that measure accurately the airblast overpressures from surface mine blasting. The results include equivalencies between broadband research instrumentation and commercially available impulse precision sound levels meters measuring: root-mean-square, peak, fast, slow, impulse, A and C weighting, C-weighted sound exposure level (CSEL), and "linear" (flat) response. These values were obtained from field measurements and broadband FM tape recordings of production blasts at area and contour coal mines, limestones quarries, and iron mines. Frequency response was determined for 14 commercial systems.

Jan 1, 1981

By Laurance L. Oden, Jack C. White, Alan D. Hartman

The U.S. Bureau of Mines, under a Memorandum of Agreement with the American Society of Mechanical Engineers (ASME), established design criteria for a facility to field residues from municipal waste combustion. This facility, which is available to potential users on a cost-sharing basis, is also applicable to a variety of inorganic waste materials from smelting or melting operations. The design consists of a mechanical feed handling system, electric arc melting furnace, fume-off gas handling system, and thermal oxidizer for final off gas treatment. Screw conveyors and a bucket elevator deliver up to 2,000 Ib/h of minus I-in material to a three-phase electric arc melting furnace. This unique 800-kVe A furnace has a water-cooled shell and roof to minimize interaction of the melt with the refractory lining. The volume of the hearth below the slag taphole is approximately 1.2 st of steel. The furnace is sealed, allowing atmosphere control within the furnace and fume duct by nitrogen or inert gas injection. A jet-pulsed baghouse removes particulate from the off gas and serves as an acid gas scrubber. The clean off gas is heated to 1,800' F for 1 s in a propane-fired thermal oxidizer before being vented to the atmosphere.

Jan 1, 1993

By Albert W. Deurbrouck

This report describes the preparation characteristics of 23 coal samples collected from nine of the more significant coalbeds of Fayette County, W. Va. In 1963 almost 5.4 million tons of medium to high volatile B coals of excellent quality for metallurgical and steam markets were produced in Fayette County. Of the 23 coal samples collected 11 would require some upgrading to pro-vide metallurgical quality products, 11 were acceptable as received, and 1 was a noncaking coal. Cleaning these coals to metallurgical standards would require only the removal of the sink 1.58 specific gravity material which would be quite easy as very little near-separating-gravity material was present at this gravity.

Jan 1, 1965

By F. D. DeVaney

The low-grade deposits of manganese ores along the Missouri River near Chamberlain, S. Dak., are known to contain one of the largest reserves of manganese in the United States. Manganese occurs as concretionary nodules ranging in size from 13 inches in their longest dimension to particles finer than 65-mesh. The nodules are embedded in soft, wet shale, which contains little manganese. The removal of nodules from the low-grade shale is a simple mechanical problem; the question is primarily to determine the lowest-cost method of separation. This report purposes to present data acquired by experimenting with samples of the ore, which form a basis for suggesting methods of concentrating manganese nodules.

Jan 1, 1942

By F. D. DeVaney

The low-grade deposits of manganese ores along the Missouri River near Chamberlain, S. Dak., are known to contain one of the largest reserves of manganese in the United States. Manganese occurs as concretionary nodules ranging in size from 13 inches in their longest dimension to particles finer than 65-mesh. The nodules are embedded in soft, wet shale, which contains little manganese. The removal of nodules from the low-grade shale is a simple mechanical -problem; the question is primarily to determine the lowest-cost method of separation. This report purposes to present data acquired by experimenting with samples of the ore, which form a basis for suggesting methods of concentrating manganese nodules.

Jan 1, 1942

By By Staff

"This publication summarizes, for potential contractors and all other interested parties, the research, development, and demonstration of in-house and contract projects programmed by the Bureau of Mines for fiscal year 1982(October 1, 1981-September 30, 1982) under its Minerals Health and Safety Technology program. The objective of these projects is to provide an ordered and sequenced series of advance toward the Bureau's overall goal of providing the systems technology required to create a more healthful and safer working environment for the Nation's mining and minerals processing workersINTRODUCTION The Bureau of Mines conducts a balanced, continuing in-house research and development program to accelerate systematic improvements in health and safety conditions in U.S. mines. Part I of this report outlines the Bureau's present in-house effort to all interested parties; in particular, potential contractors can refer to it when submitting USP's (unsolicited proposals), thus avoiding proposing research that duplicates work being performed by the Bureau.It is the policy of the Bureau of Mines to utilize as fully as possible the capabilities of the private sector in minerals research, and to that endPart II of this report outlines the Bureau's current projected contract research needs.The projects presented were planned at the beginning of the fiscal year and are subject to change based on emerging priorities and availability of funds. Contingencies may require that a significant portion of the program be deferred into fiscal year 1983 (FY 83) or beyond. It is important to realize that since this is a summary document, the project descriptions related to a design, fabrications, and demonstration effort do not necessarily imply total package procurement."

Jan 1, 1982

By Rudolf E. Greuer

This study concerns itself with two topics of the mine ventilation - mine fire interface which, when the work for this study began, did not seem to receive sufficient attention. Section 1: Comments on Spontaneous Combustion of Coal in Mines It is attempted to describe heat generation, heat and oxygen transport, in such a way that existing experimental data for U.S. coals can be used to assess conditions inducive to spontaneous heatings quantitatively. Investigated are, in particular, critical air velocities, minimum sizes of coal accumulations, moisture contents and the influence of mining factors. An extensive, practice oriented literature survey is included. Section 2: The Early Detection of Mine Fires by Assessment. of Mine Gases The suitability of the major constituents of combustion products for an early detection of fires is discussed. The same is done for gas concentration ratios. Since it was felt (at least at the time when this report section was written) that the value of the carbon monoxide/oxygen deficiency ratio was overestimated, the usefulness of monitoring this ratio as compared to monitoring CO concentrations was critically investigated. The state of art concerning instrumentation and organization of fire detection systems is reviewed also.

Jan 1, 2011