Search Documents

By R. V. Ramani, R. Bhaskar

"The control of respirable dust in mines has been given paramount importance due to the health and safety implications associated with fine dust. The understanding of the temporal and spatial behavior of dust has been recognized as essential for increasing the efficiencies of the existing control techniques and for developing new control strategies. Mining-related studies in this area are, in general, limited. They are also mostly experimental. Some mathematical and computer analyses have been attempted. In this paper, first a review of the mathematical studies performed in the last three decades in this area is presented. Second, a mathematical model for analyzing dust flow in mines is proposed. The model takes into account a number of factors affecting dust transport. It incorporates varying dust generation source strengths and dispersion, deposition, and coagulation of dust in mine airways. Finally, application areas for the model are discussed. A computer program based on the mathematical model has been developed. The program will output the dust concentration in the mine atmosphere as a function of time and distance from the source. The amount of dust deposited on the sides, roof, and floor of the airway is also determined.IntroductionAn airborne dust cloud is a complex system containing particles of varied size, density, shape and state of aggregation. The behavior of the particles is dependent on a number of complex physical mechanisms, often opposing in nature. The net interaction results in the ambient concentration. This size dependent behavior of particles contrasts with that of gases, an area quite widely studied.The term aerosol is used to describe clouds of microscopic and submicroscopic particles in air such as chemical smoke or particulate matter released from smoke stacks. An aerosol system can be regarded as an arbitrary element of volume filled with gas and suspended particles of possible highly variable physiochemical nature. The parameters that are used to describe an aerosol system include concentration, mass average velocity and particle mass and radius. In characterizing such systems, several assumptions are made. Among these is the assumption that particles are smooth, inert and rigid spheres. Again, for example, when the particles are in transport, the possibility of collision exists. As a result of the collision, the particles may coalesce to form larger particles. The probability of sticking is considered a known quantity (lady, 1970). In this paper, the application of the principles used in aerosol systems is explored for the study of the transport and deposition of fine coal dust in underground mines."

Jun 1, 1988

By C. P. Bowie

For years many oil producers have believed that often low-pressure oil- and gas-bearing strata have been over coked in fields where the rotary system of drilling has been used. Collom3/ gave as a reason for this condition that because the mud fluid was thick, the oil or gas stratum was plastered and sealed as the tools passed through it and no oil showed at the surface. Although this observation was made 15 years ago, it may often still be true notwithstanding modern developments in coring and electrical logging. Operators have believed, also, that mud fluid does not solidify behind the casing. Lewis and McMurray4/ stated: "All the evidence obtainable from practical experience points to the fact that the mud fluid properly mixed and employed does not solidify behind the casing, even in deer wells and after long periods."

Jan 1, 1937

By L. S. Sundae

The Bureau of Mines conducted a series of tests to compare the cutting forces required by radial and point-attack bits when making similar cuts. Three radial and four point-attack bits were tested in two coal mines using the Bureau's in-seam tester to measure coal-cutting forces in situ. Tests were also conducted to investigate the effects of weathering and cleating. The test results show that in each case, at a specific clearance angle, the radial bits required less tangential and much less normal force than the point-attack bits. The resultant of the cutting forces for some types of cut was 50 pct less at mine 1 for radial cuts compared to cuts with the best point-attack bit, and 40 pct less at mine 2. There was some difference between three types of radial bits, but it was not as significant as the difference between each type of point-attack bit. Cutting coal perpendicular to the cleat planes required less cutting and normal force than the same type of cuts parallel to the cleat planes. Test results showed no effect due to weathering on cutting force data. Cutting parallel increased forces only because cuts were made in the rock band.

Jan 1, 1987

By L. C. Brichta

During a study of the Badger-Peacock area from October 1950 to June 1953, the Federal Geological Survey and the Federal Bureau of Mines completed nearly 98 miles of resistivity profiling and drilled 96 test holes aggregating 17,628 feet of bore, In addition, seismic profile measurements were made along 8 traverse lines for an aggregate length of about 16,600 feet. The geophysical surveys were conducted by the Geophysics Branch of the Geological Survey; the drilling was done by the Bureau of Mines. Electrical-resistivity measurements disclosed 21 low-resistivity anomalies and 1 high-resistivity anomaly. Correlation of the resistivity data with the geological information revealed by the drilling disclosed that the low-resistivity anomalies indicated either slumped shale deposits in limestone sinks or undisturbed deposits of shale lying in erosional depressions in the limestone. The high-resistivity anomaly indicated hard, undisturbed limestone at or near the surface.

Jan 1, 1958

By Valois R. Shea-Albin

Ground control problems are an important factor affecting safety, production, and efficiency in underground coal mines. A major portion of ground control problems encountered in underground coal mines can be attributed to geologic features in the strata surrounding the extracted coal seam. The U.S. Bureau of Mines has compiled information from numerous sources on the geological features that contribute to ground control problems in underground coal mines. The compilation includes (1) sedimentary features such as paleochannels, crevasse splays, clastic dikes, mold-and-cast structures, concretions, and lithologic factors, and (2) structural features such as folds, fractures, joints, cleat, and faults. The compiled information will aid in identifying the features, predicting their occurrence in advance of mining, and controlling or minimizing roof failure when these features are encountered in an underground coal mine.

Jan 1, 1993

Lignite constitutes approximately 97 percent of the near-surface coal resources in Texas. The most significant bituminous resources are in the north-central and southern parts of the state. Coal reserves in Texas are estimated to be 13.7 billion tons, about three percent of U.S. coal reserves. The average thickness of coal seams mined in Texas is approximately eight feet. Texas gained primacy when its regulatory program was conditionally approved February 16, 1980; the program was fully approved June 18,1980. The state's Abandoned Mine Lands program was approved June 23,1980.

Jan 1, 1992

By J. A. Taylor, H. F. Yancey

"INTRODUCTION Froth flotation as applied to coal is a process for separating desirable carbonaceous material from undesirable inorganic matter. In general, the feed must be finer than one eighth inch in size. The principal use of the process in the preparation of coal appears to be in the treatment of the fine sizes produced by breakage during mining and preparation.The Bureau of Vines in Information Circular 6714 has published general information on coal flotation, summarized investigative studies of the process, and described operating plants throughout the world with their tonnage, reagent consumption and operating costs.4ACKNOWLEDGMENTSThe present study of means for depressing pyrite and reducing ash ty froth flotation was conducted at the Northwest Experiment Station of the United States Bureau of Wines in cooperation with the College of vines. University of Washington, under the general direction of A. C. Fieldner, chief engineer, Experiment Stations Division, Bureau of Wines. Grateful acknowledgment is made for suggestions and criticisms received from W. H. Coghill, supervising engineer, U.S. Bureau of Mines Mississippi Valley Experiment Station, Rolla, Mo.; J. B. Morrow, and R. E. Zimmerman, of the Pittsburgh Coal Co.; and Dean Milnor Roberts and Prof. Joseph Daniels, of the College of Mines, University of Washington.FLOTATION AND DEPRESSIONA substance will tend to float if its surface attracts a gas film more strongly than it does a liquid film when both air and liquid are competing for this attraction. On the other hand, a substance will not float if its surface attracts a liquid film more strongly than it does a gas film. All theories of depression depend upon this fact. A wetted particle of floatable size most likely will be found in the tailings after the flotation process has been completed.The crux of flotation is the selective wetting of the undesirable material that tends to float. Two general methods 5, 6, 7 of depression are in use: One combines a chemical substance with the surface to form a wettable compound, and the other employs some colloidal or ionic substance which the surface selectively adsorbs, thereby forming a wettable surface."

Jan 1, 1935

By Ted C. Briggs

A special high-pressure Burnett-type compressibility apparatus was constructed and used to determine compressibility factors for pure helium, pure nitrogen, and nine helium-nitrogen mixtures containing 89.47, 79.04, 69.69, 60.09, 49.24, 41.02, 30.99, 20.53, and 10.67 mole-percent helium. A total of 161 runs were made consisting of 2,355 observed pressures. Data were obtained at 0°, 25°, and 50° C and at pressures to 1,000 atmospheres. A power series in the reciprocal volume, commonly called a Leiden series, is used to represent the compressibility factors. Three parameters in the series are required to represent helium, five parameters to represent nitrogen, and from three to five parameters to represent the mixtures. Compressibility factors are believed to be accurate to better than 0.1 percent over the entire pressure, temperature, and composition range.

Jan 1, 1972

By C. C. Popoff

The Dunkleberg district is in the Flint Creek Range of the northern Rocky Mountains, about 45 miles northwest of Butte, Mont. Silver - lead and zinc mineralization occurs over an area 4 miles long from north to south and 1 to 2 miles wide from west to east. Ore in appreciable quantity has been produced, mostly from the Forest Rose group of mines in the southern part of the district. The Forest Rose mine was the largest producer of lead and the Wasa mine, a mile farther south, the main producer of zinc. The total output of ore from these properties during World War II was 113,000 tons, or 98.2 percent of the total recorded production of the district. The Wasa mine was examined by a Bureau of Mines engineer2/ in 1944. Subsequent investigations during 1946, 1947, and 1948 included trenching and drilling Fn the Wasa area and examination of the Forest Rose and other mines.

Jan 1, 1953

By W. H. Young

THE DOMEST[C bituminous coal and lignite industry remained fairly steady in 1959 compared with 1958. Although mechanization continued to expand and production increased slightly, consumption, average value, exports, and employment decreased. The percentage of underground production mechanically loaded, the percentage of total production mined by stripping, and tonnage per man per day were at their highest levels. Production.-The output of bituminous coal and lignite in 1959-412 million tons-was 0.4 percent greater than the 410.4 million tons produced in 1958. Production was retarded in 1959, largely owing to the steel strike and reduced exports.

Jan 1, 1960

7133. Clewell, D. H. The Gravimeter. Prec. and Trans. Texas Acad. Science 1941, Austin, Tex., vol. 25, 1942, pp. 86-88. Static gravimeters, unastatized and. astatized, are considered to be the most practical for oil exploration. One gravimeter is described using a beam whose moment about a pivotal axis is elastically balanced. Magnetic or electric fields are deemed unsatisfactory for balancing gravitational force because they cannot easily be kept constant. The gravimeter described is capable of detecting a change in altitude of 3 inches and a change in latitude of about 150 feet. V. S.

Jan 1, 1944

By Iain Finnie

This report is in three parts. The first part presents a review of theoretical models which have been developed to study removal operations for various types of materials. In the second part, a brief summary is given of coal cutting research. The majority of this work has been carried out in Britain using chisel type bits rather than the conical picks which are in general use in this country. However, a comparison of specific energies measured for conical picks in the laboratory and in the mine shows very encouraging correspondence. In the third part of the report, analytical models for coal cutting by picks are suggested. An extension of the British "tensile breakage" theory, developed for chisels, is given for picks. The role of crushing and cutting in coal removal is discussed as a theory which combines the two processes is shown to give reasonable predictions for specific energy requirements. Finally, directions in which the existing theory could be improved are presented and the need for further research is emphasized.

Jan 1, 1977

By Eldon K. Stanek

The material presented in this chapter is a review of the work done during the period from June 23, 1972 to June 22, 1973 which was reported in detail in the first annual report for Grant No. 60122088 which was submitted on June 29, 1973. This report has appeared in the National Technical Information Service as bulletin number PB230 972/AS. 1.2 ANALYTICAL PREDICTIONS OF INDUCED VOLTAGES AND CURRENTS The basic building block in this analytical work is the development of an equivalent circuit. The equivalent circuit for the cable depends on all of the distributed parameters of the cable, although the series inductance and resistance are of primary importance. The cable resistances are generally available from handbooks or from cable manufacturers. On the other hand, the cable inductances are not usually available from either handbooks or the manufacturer's published data. Thus, it is useful to present the results of the derivation of the inductance matrix and a few intermediate steps.

Jan 1, 1975

By Richard P. Cislo

The evaluation of the effectiveness of the time domain Coal Interface Detector developed by the General Electric Company under contract H0155120 is the subject of this report. The sensor utilizes differences in the time characteristics of shearer vibrations as sensed by an accelerometer mounted on the ranging arm to discriminate the cutting of coal and rock. Pour identical time domain sensors were supplied by the Bureau for field evaluation. The performance of the time domain sensor was evaluated by an extensive field test and data collection program that included four longwall mines and a total of nine mine visits. The intent was to determine the sensor's applicability to a wide range of mining conditions and to document its limitations. Results of the extensive field tests indicate that shearer vibration data processed by GE's time domain signal processing algorithm cannot be used to reliably detect when the cutting drum crossed the coal/rock interface.

Jan 1, 1987

By H. B. Brunot, L. C. IlsLey, E. J. Gleim

"INTRODUCTION To supply inspectors, safety engineers, and others with detailed information as to the safety features of the various electrically operated machines that have been approved as permissible by the Bureau of Mines, three bulletins and five reports of investigations have been published dealing with the various classes of approved machines:Bull. 313, Permissible Storage-Battery Locomotives and Power Trucks.Bull, 343, Permissible Coal-Handling Equipment Approved from January 1926 to December 1930, inclusive.Bull. 382, Permissible Coal-Cutting Equipment Approved Prior to July 1, 1932.Rep. of Investigations 3309, Permissible Electrically Operated. Air Compressors.Rep. of Investigations 3326, Permissible Electrically Operated Room Hoists.Rep. of Investigations 3345, Permissible Electrically Operated Rock-Dust Distributors.Rep. of Investigations 3363, Permissible Electrically Operated Hand-Held Coal Drills.Rep. of Investigations 3391, Permissible Electrically Operated Post Drills and Drilling Machines.The present paper gives similar information relative to the mine pumps approved before October 1, 1939."

Mar 1, 1940

By John J. Mulligan

Since 1941 the Federal Bureau of Mines has been conducting an intermit-tent program of placer and lode investigations to evaluate the potential tin resources of the western Seward Peninsula tin belt. Previous investigations were made in the Potato, Cape, Brooks (Lost River), and Ear Mountain areas. As part of this program the Bureau made a reconnaissance of reportedly tin-bearing stream gravels in areas adjacent to the previously worked tin deposits at Lost River and Potato Mountain. The objective of the reconnaissance was to determine if additional areas might be favorable for lode or placer exploration. The work was begun late in the fall of 1956 and completed during the following summer. The streams sampled were the Lost River and York Creek in the Brooks Mountain area and the Anikovik River and Kigezruk and Baituk Creeks in the York area. Samples were obtained by churn-drilling methods employing conventional placer-evaluation procedures. Holes were drilled at wide intervals at sites chosen as being representative of drainage areas rather than of individual gravel deposits. Minor to trace amounts of tin were found in the gravels of all these streams, but the highest grade was 0.35 pound of tin per cubic yard in the gravels of Lost River below the mouth of Tin Creek. Small amounts of gold were found on Baituk Creek and in one hole on the Anikovik River; the highest grade did not exceed 10 cents per cubic yard. Traces of scheelite and barite were found on York Creek, chromite was encountered in one hole on the Anikovik River, and minor amounts of titanium minerals (probably derived from basaltic intrusives) were found in the York area.

Jan 1, 1959

By James J. Scott

Workshops were held in eight states during the period from December 12. 1975. through June 25, 1976, under U. S. Bureau of Mines Contract to the University of Missouri-Rolla. The workshops were designed to help define the Bureau's research and development priorities. At each workshop a summary of the current Bureau mine reclamation research was presented which was followed by identification of problems associated with mine land reclamation in the state where the meeting was being held. Discussions included the seriousness of problems locally and how the Bureau could best undertake research to assist the state in solving the problems identified. Participants included representatives of state agencies, educational institutions, and companies involved in surface mining. Attendance at these workshops totaled 201 persons who displayed a wide variety of opinions and ideas as to what should be done In government research and development efforts. A breakdown of these attendees is as follows: 91 state and Federal employees; 69 mine operators, equipment manufacturers and consultants; 33 educators and researchers; and 8 others representing such varied interests as environmental and conservation groups, news media and students .

Jan 1, 1976

By A. L. Service

In 1965 the Western phosphate industry ranked third after Florida and Tennessee in total mine and marketable production of phosphate rock and phosphate rock products. It has become an important regional industry and, since the close of World War II, it has become important in the national phosphate economy. This report includes an evaluation of the trends and outlook for the Western phosphate industry through 1975 as part of the Bureau's program to determine the rate at which the Nation's mineral resources are being utilized. The first part of this report is concerned with the relationship between the Western phosphate industry and that of the United States and the world. It describes the principal phosphate deposits and discusses production, export, and import of phosphate rock and marketable products. The second part of the report is concerned with the Western phosphate industry and discusses trends and outlook through 1975. Projections for the utilization of phosphate rock, phosphate fertilizers, and elemental phosphorus have been developed and extended through 1975 in an effort to provide data and information pertaining to the rate of depletion of the Nation's phosphate resources.

Jan 1, 1967

By L. E. Cardwell

This publication contains routine analyses and related source data for 390 natural gas samples from 22 States and five foreign countries. Of this total, 385 samples were collected during calendar year 1969. The remaining five analyses are of samples collected during previous years, but releases granting permission to publish the results were not received until 1969. All samples were collected as part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus which are described in Bureau of Mines Bulletins 4863 and 576.4 Eleven previous publications have presented the results of 8,660 gas analyses made by the Bureau of Mines Helium Activity prior to 1969. The first three, Bulletins 486,6 576,6 and 617,7 contain analyses and related source

Jan 1, 1970

By Ronald B. Stotelmeyer

This report summarizes studies of 28 National Forest roadless areas in Montana completed by the U.S. Bureau of Mines (USBM) in the period 1974-1993. It also briefly describes 20 areas for which field studies have not been conducted. All 48 of these roadless areas have been recommended for addition to the National Wilderness Preservation System or proposed as special management areas by the U.S. Forest Service (USFS) or the Montana congressional delegation. The Bureau studies indicate which parts of the roadless areas have a high likelihood for mineral-resource development. They also show where mineral production has occurred in the past and where abandoned mine workings (possible hazards) would be encountered. The number of mine and prospect workings found are a measure not only of surface disturbance, but of areas not wilderness in character. For the purposes of this report, mine refers to a property which produced (or is currently producing) a mineral commodity, a prospect is a property which has been explored but has no record of production.

Jan 1, 1994