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By Robert H. Merrill

This report contains a summary of the various studies made to determine the structural design of the production mine area of the Oil-Shale mine, Rifle, Colo. Prior to this investigation, it had been determined from a study of the geology, the structure of the deposit, and mining costs that the deposit should be mined by open stoping. The problem remained to determine the maximum safe roof span, the optimum extraction ratio, and the size of the pillars. These factors were determined from a study of the geologic structure of the deposit, the physical properties of the oil shale, and the magnitude and distribution of the stress around proposed underground openings. The latter was determined from both theoretical calculations and model studies. Safe roof spans, pillar sizes, pillar contours, and optimum extraction ratios were calculated from elastic theory and the physical properties of the mine rock. Safe roof spans, pillar sizes; and time effects were determined by Wright and Bucky by testing mine models in a centrifuge. The models were made from rock specimens taken from the proposed mine roof and pillars. The results from both studies agreed.

Jan 1, 1954

By C. J. Walker

The ever-increasing use off natural underground formations for storing natural gas has focused attention on the behavior of such storage formations under varying operating conditions. The need for a means of evaluating in¬dividual wells and groups of wells has become manifest. It is essential that industry and others be able to determine the rates of flow that can be ex¬pected from a given well or group of wells under different conditions and to ascertain whether certain wells are deteriorating. Such questions need more exact answers now than ever before because of the vital role underground gas storage plays in the industrial and domestic consumption of natural gas. The Bureau of Mines--in cooperation with the American Gas Association--has main¬tained an active interest in gas-well testing because of the implications of such test procedures on the consumption and efficient production of natural gas. A basis for testing gas wells was provided by the back-pressure method of Rawlins and Schellhardt (12).4/ They showed that for normal gas wells there is a consistent relationship between rates of delivery of gas and corresponding pressures when the formation pressures are used as the basis of interpretation, The equation for this relationship is as follows: Q = C (Pf2 - Ps2)n where; Q = rate of flow, generally expressed in cubic feet per 24 hours. C = a coefficient.

Jan 1, 1960

By Oliver Bowles

Accidental explosions in coal mines are due to various causes, but many of them can be directly attributed to coal dust; others that probably in no way depend on dust as a primary cause are propagated, greatly intensified, and made more disastrous by the presence of coal dust. The fact that coal dust in a bituminous mine will explode as a result of a fire-damp explosion has been generally accepted for many years, but the belief has also been held by many that coal dust is not in itself dangerous when unmixed with an explosive gas. Therefore, in past years little attention was given to dust in mines free from fire damp, and many disastrous explosions have resulted from lack of knowledge of the danger from coal dust. In the explosives gallery and experimental mine of the Bureau of Mines experiment station, Pittsburgh, Pa., it has been proved repeatedly and conclusively that coal dust will explode violently when no inflammable gas is present. PROPAGATION OF DUST EXPLOSIONS A coal-dust explosion is an extremely rapid burning or combustion of the coal particles. Their burning consists essentially of the combination of the hydrocarbons in the coal with the oxygen of the air, a process that generates heat and flame and produces hot gases and water vapor. These gases and vapors have a volume many times that of the original coal particles; thus they exert an outward motion and pressure which constitute the explosive wave. When fine particles of coal are suspended in the air, each particle is surrounded by the oxygen of the air, and thus is well placed to oxidize or burn rapidly whenever the temperature is high enough. If some particles are ignited from any cause they will fire others, and the combustion will extend from particle to particle with extreme rapidity wherever enough coal dust of sufficient purity is present.

Jan 1, 1925

By D. L. Hollis

An arc plasma reactor, constructed and used for studying extractive metallurgical processing, was adapted by the U.S. Bureau of Mines to separate gases of different masses by using the high rate of plasma rotation. With argon and helium as input gases, peripheral reactor outlet ports had a measured average increase of about 10 pet in argon concentration relative to helium with the plasma on compared with plasma off for the same gas inlet concentrations in both cases. Approximately the same average increase in argon concentration occurred from the peripheral outlet port compared with a central outlet probe with the plasma on. There was no difference with the plasma off.

Jan 1, 2010

By R. R. Sayers

Under compuision of the present urgency to implement the President's promise to make the United States the arsenal for the democracies there is a tendency to demand a relaxation of restrictions on hours of labor and to speed up all industrial processes. The pressure is the more insistent with growing realization of the importance of the time factor in the success- ful prosecution of the war effort and the lack of skilled workers due to (2) operation of the draft, lack of an apprentice system in industry, and loss of skill by workers unemployed for long periods during the depression. With "total" war such as it is today the probabilities are that everyone will be required to exert greater effort (in many instances in activities to which they are unaccustomed) for longer periods than ever before has been necessary. The question arises, "What will be the aftereffects as well as the immediate effects on health, safety, and efficiency?" A review of the literature leaves the impression that this question has not been an- swered completely, especially as regards the ultimate effects. Mechanization, speeding up of industrial processes, mass produc- tion, and the small industrial concerns present many problems to indus- trial medicine. Does the tendency to expect the worker to produce at full speed all the time he is on the job decrease the effectiveness of the shorter working hours and cause undue fatigue, loss of efficiency, and increased accident proneness? The answer is important as this condition is likely to be intensified by the exigencies of the present emergency. According to Viteles (1)3, The increased tension under such conditions of work appears to offset the savings in muscular force made pos- sible by the machine. The tension, the speed, the subject- tion to specialization of work and a rhythm uncontrolled by the individual promote fatigue, characterized by a "decrease in the power to work, a decrease in pleasure taken in work, and a decrease in the enjoyment of the hours spent away from work."' The crowding of workers in temporary structures without proper provision for comfort and health may add greatly to the general fatigue factors already present in many industrial establishments. In 1932 Lockhart (2) stated that the production and maintenance of a healthy, satisfied industrial population is the most urgent necessity, involving problems so serious as to constitute a national task too great economically to be relegated to industrial concerns. If this was true in 1932, it must be doubly so today.

Jun 1, 1942

By Ren G. Dong, Thomas W. McDowell, John Z. Wu, Chris Warren, Dan E. Welcome, Chun L. Dong

Hand forces are important factors for risk assessment of hand-arm vibration syndrome (HAVS).1 Grip force is one of the most important force components in the operation of powered hand tools. A considerable number of studies on grip force have been reported. It is well known that the grip force applied on a cylindrical handle is not uniformly distributed on each axis across the center of the handle cross-section.2 Therefore, maximum and minimum orientations of grip force exist around the handle. Such orientations have not been clearly identified. In a recently proposed international standard (ISO/CD 15230, 2005),3 it is stated that “the direction of the main gripping force is generally parallel to the z-axis defined in ISO 8727.” 4 This assertion is questionable, and further examinations are required. The objective of this study was to establish a fundamental theory on the distribution of the grip force around cylindrical handles. Methods As shown in Fig. 1, the grip force is defined as a vector composed of normal and shear components (FN & FT) in this study. Fig. 2 shows the hand coordinate system defined in this study, together with the ISO systems.1,4 Based on this novel grip force definition, we derived four fundamental properties and a theorem. More significantly, we formulated a novel hypothesis: similar to Mohr’s circle of stress, the normal and shear components can be represented approximately using an ellipse on the plane of the two force coordinates, as shown in Fig. 3. The maximum and minimum grip normal forces are termed as the first principal grip force (F1) and the second principal grip normal force (F2), respectively. Their corresponding orientations are termed as the first principal grip angle (a1) and the second principal grip angle (a2). A series of experiments were conducted to test this hypothesis. Twelve

Jan 6, 2006

By D. R. Tesarik

As part of its research program to investigate ways of improving resource recovery and reducing subsidence, researchers from the U.S. Bureau of Mines placed instruments in the B-North ore body of the Cannon Mine, Wenatchee, WA, to monitor cemented backfill and rock deformation during mining. The vibrating-wire gauges proved to be reliable and versatile, and approximately half of the instruments are providing data after 2 years of use. A two-dimensional, finite-element model was used to analyze the Cannon Mine's multilevel bench cut-and-fill mining method and predict rock and backfill displacements. The model accurately predicted rock displacements, but the predicted and measured displacements in cemented backfill had a correlation coefficient near zero, indicating that the model should only be used to predict rock displacements and not backfill displacements. A finite-difference model was also used to evaluate the stability of a cemented backfill pillar. Results can be used to conservatively predict backfill stresses, but on-site observation of pillar failures coupled with in situ measurements are needed to make more accurate predictions. An ongoing evaluation of the mining system has indicated that filling the primary stopes tight to the back with cemented backfill allowed these pillars to carry overburden loads soon after the cemented backfill was placed.

Jan 1, 2010

By Joel N. Van Sant

The rapidly expanding economy of the West, with its growth of heavy industry, and increased steel production, is primarily responsible for the refractory clay industry's concern over the adequacy of the clay supply in States of the Great Plains and Rocky Mountains. Hence, the investigation by the Federal Bureau of Mines of the occurrence and use of refractory clays in North Dakota, South Dakota, Nebraska, Wyoming, Colorado, Utah, New Mexico, and Arizona has been encouraged by the major consumers and producers of this commodity. The Wyoming investigation is a part of the national program devised to close gaps in the domestic supply of specific types of clays to determine their characteristics and properties and to provide information that will assist the refractory-clay industry. Forty-two locations of clay-bearing rock in 17 areas in Wyoming were examined (fig. 1). Location 3 was not examined during this survey. Its description was taken from an earlier report. Locations 20, 21, and 22 were previously reported but were, also, examined by the Bureau. No samples were collected from these locations because field examination indicated that the shales were not refractory grade. The Hulett, Aladdin, and Newcastle areas are discussed in the section on the Black Hills district; the other 14 areas are described separately.

Jan 1, 1961

By R. E. Head

This paper embodies the data obtained by a detailed statistical, microscopic analysis of the composite mill feed concentrate, and tailing, from the Magne and Arthur mills of the Utah Conger Co. for 1 month in 1929. It is one of a series of papers by the same authors dealing with the mineralogical characteristics of the ore and concentration products from various well-known plants. The work was done in the cooperative microscopic service laboratory at Salt Lake and represents the results of cooperation between the United States Bureau of Mines, the Utah Copper Co., and the University of Utah.

Jan 1, 1935

By R. E. Head

[This paper embodies the data obtained by a detailed statistical, microscopic analysis of the composite mill feed concentrate, and tailing from the Magne and Arthur mills of the Utah Conger Co. for 1 month in 1929. It is one of a series of papers by the same authors5 dealing with the mineralogical characteristics of the ore and concentration products from various well-known plants. The work was done in the cooperateive microscopic service laboratory at Salt Lake and represents the results of cooperation between the United States Bureau u of Mines, the Utah Copper Co. and the University of Utah.]

Jan 1, 1935

By Yumi Nakashima, Setsuo Maeda

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

Jan 6, 2006

By James P. Ludwig

This report provides the results of a two year study of the projected time and cost requirements for new mine development in Wisconsin and is based on a unique blend of information from mining company officials, state regulatory agency officials and contractor experience. Through formal cooperative and review agreements with Kennecott Copy per Corporation, Exxon Minerals Co., U.S.A. and Noranda Mines Ltd., and the Wisconsin Department of Natural Resources plus informal arrangements with knowledgeable Wisconsin persons, lists of the tasks and subtasks required to plan a new mine in Wisconsin were developed. Times and costs were assigned to all tasks and subtasks and these data reviewed by all cooperators. Critical Path Method Diagrams were then developed for a generalized mining project. Total time and cost for the premine planning process was estimated to be 25..1 years and 223 person-years of professional time excluding public affairs effort respectively. By eliminating redundancies in the process and by increasing project efficiency through early public review and participation, recom¬mendations were made to lessen the time and lower the cost of premine planning. The streamlining recommendations could shorten the overall critical path length to 18.16 years and lower the cost to 208 person-years of professional time excluding public affairs effort. The estimated distribution of professional effort (cost) for mine planning in Wisconsin approximates 50.5% for traditional mine engineering tasks, 36.6% for environmental-regulatory tasks and 12.9% for traditional geological-exploration tasks.

Jan 1, 1979

By J. J. Shields

With the increased use of mechanized equipment in mining bituminous coal, production panels are mined out rapidly. To keep current with the rapid completion of production panels, development work must be speeded up also. Although the same type of equipment usually is employed in development as in production places in the same mine, past output per man for development usually was less than from production panels. A study of development practices in 14 mines reveals a tendency toward equalization of the output per man between development and production.

Jan 1, 1957

By M. A. Elliott

Diesel-powered haulage equipment has recently been tested and approved for permissibility by the Bureau of Mines for use in mining in the United States. Achievement of this advance in safety involved extensive studies, both in the testing station (2, 3, 20, 21, 22, 23, 24, 25, 26, 27)3/ and in the field 1, 4, 13, 30), of the operating characteristics of diesel engines in relation to the toe of such engines underground. The results of these studies formed the basis for establishing the requirements that should be met by diesel-powered haulage equipment approved for permissibility. Considerable interest has been manifested in the development of diesel-powered haulage equipment fur mines. The purpose of this paper is to retrace briefly the course of this development and to answer such questions as: What is the history of the use of diesel engines underground? Why has the Bureau of Mines been interested in the development of diesel-powered haulage equipment for use in mines?

Jan 1, 1953

By W. W. Adams

Two important facts stand out as features of the metal- and nonmetal-mining4 industry of the United States in 1941 as compared with 1940: First, the number of employees and man-days of employment increased; second, accident-frequency rates, both fatal and nonfatal, decreased. Reports from mining companies to the Bureau of Mines covering underground, open-pit, and surface operations for 1941 re¬vealed the largest number of men employed since 1926 and the largest number of man-days worked since 1929. The combined fatal and non¬fatal accident-frequency rate for 1941, calculated on a basis of one mil¬lion man-hours of exposure to hazard, was (except for 1931 and 1932) the lowest since 1911, the earliest year for which figures are available. During this 31-year period, only 1938 and 1939 showed lower fatality rates, and only 1931 and 1932 had lower nonfatal-injury rates. Operating companies reported that 9,620 mines were active during all or some part of the year. These employed 125,290 men, an increase of more than 4 percent over 1940. The total volume of work performed at all mines, measured in terms of man-shifts, increased to nearly 32 million, a gain of 10 percent; man-hours of employment rose to almost 254 million, an increase of 10 percent over the 231 million man-hours worked in the previous year. The year's operations resulted in an average work-year of 255 days per man, an increase of 13 days per employee over the average working time in 1940. Although the 8-hour day prevails generally at most mines, the industry as a whole averaged 7.94 hours per shift, as in 1940.

Jan 1, 1944

By Ann G. Kim

The Bureau of Mines estimated the methane content of a coal, which depends primarily upon rank and pressure, from the adsorption equation V kpn, where k and n are constants related to rank. By incorporating corrections for moisture, ash, and temperature, and estimating pressure and temperature as a function of depth, the methane content of coal in place can be estimated from the following equation: [ ] Values calculated with this equation generally are in reasonable agreement with direct determinations. By assuming a standard moisture and ash content, and using the hydrostatic head to estimate pressure, a graph of rank and depth versus gas content was constructed. Although estimated values were consistently high for several high-volatile bituminous coals from an area where the pressure is known to be less than hydrostatic, the estimated methane content for most coals shows reasonable agreement with values determined by the direct method.

Jan 1, 1977

By Scott Turner

The present rapid growth of coal stripping in the United States is a curious reversal of the tendency of mining to proceed from outcrop to depth. A combination of technical and economic factors bas stimulated the use of stripping methods until today many million tons of coal We being recovered by open cuts from sites that an earlier generation of engineers would have passed by as not commercially mineable or, if workable at all, only by underground methods. The total quantity of bituminous coal and lignite mined in the United States by stripping in 1928, the latest year for which detailed figures are available, was 19,789,000 short tons. Of this, 71,000 tons came from small workings not equipped with power shovels and 587,000 tons from properties in which stripping and underground work were carried on at the same mine; but as neither of these types is representative of modern stripping practice, they will be omitted in the discussion that follows. The total from strip pits proper in 1928 was 19,131,000 tons, produced by 176 pits employing 385 steam or electric shovels.3 Figures by States are given in Table 1. Detailed statistics will be found in Economics of Strip Coal Mining; a study by O. E. Kiessling, to be published by the United States Bureau of Mines.

Jan 1, 1930

By Louis H. Berkelhamer

"INTRODUCTION ""Free silica"" includes all free forms of silicon dioxide, such as quartz, chalcedony, tridymite, cristbbalite, opal, diatomaceous earth, and lechatelierite. The term, has been used rather loosely however, as synonymous with quartz, as quartz is the most abundant form of free silica. ""Combined silica,"" on the other hand, has been reserved to denote silica combined with other elements as silicates.Improvements in methods for the determination of free silica, and quartz in particular, have been the subject of considerable interest during the past decade, owing mainly to the accented and increased knowledge concerning quartz as a causative factor in silicosis. Analysis for quartz, however, is of importance in many other fields, including the determination of quartz in ceramic raw materials, such as feldspar and clay; the evaluation of a beneficiation procedure by the ore dresser, such as in the concentration of iron ore; control studies of a manufactured product, such as silica brick; and routine analysis of rock, mineral, and ore samples by chemists and petrographers."

Jul 1, 1944

By Elaine T. Bowers

The Sunnyside single-entry project pioneered the use of single entries for longwall development in this country. During the 10-year course of the project, an immense amount of information was gathered. Over three miles of entries were observed primarily through instrument groupings placed in strategically located areas or "rooms." Nearly 1,200 instruments were monitored to gain information on the behavior of coal entries during development stages and through the mining of two longwall panels. This was one of the most extensively documented projects undertaken by the Bureau, The data gathered has a great potential for scientific research especially in the area of longwall mining. This Bureau of Mines report presents the ground control data gathered, in the form of computerized plots. Roof-to-floor deformation and load on cribs and roof bolts make up the bulk of the data, which is presented as load or deformation versus time. The plots are organized, generally, by the three main entries involved and, specifically, by the individual areas or rooms in those entries. No major attempt will be made, in this paper, to analyze the data other than to identify its source arid its history.

Jan 1, 1983

By Stephen C. Tadolini, Gabriel S. Esterhuizen, Anthony T. Iannacchione

A Major Hazard Risk Assessment (MHRA) was developed in Australia after a series of mine disasters in the 1990’s. A MHRA is used to help prevent major hazards, i.e. fire, explosion, wind-blast, outbursts, spontaneous combustion, roof instability and chemical and hazardous substances, from injuring miners. A MHRA is a structured process that identifies the characteristics of major hazards, assesses and ranks the risk they present, and evaluates engineering and administrative controls to mitigate them. These controls typically consists of a broad spectrum of prevention, monitoring, first response, and emergency response techniques and helps to move an operation from a reactive to a proactive approach towards safety. This paper documents a MHRA performed at an underground mine where strata instabilities and fire hazards may threaten the condition of its escapeways. The objective of this MHRA is to 1) identify what hazards could affect the egress through the mine’s escapeways, 2) determine what unwanted events pose the greatest threat for the mine, and 3) recommend a plan to prevent or recover from the potential disruption of egress through the escapeway. The plan provides information on the key existing controls that should be monitored and audited, and makes recommendation of new potential controls to further reduce related risks. By documenting the use of MHRA to this specific ground control issue, this paper provides a framework for others to judge the merits of this approach and to help design and perform these activities.