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By Robert H. Merrill

A method of determining the strength of a mine roof layer in place is described in this report. The method was tested on a limestone roof layer 50 feet wide, 100 feet long, and 20 inches thick. In place measurements were accomplished by introducing air under pressure into a separation between the layer and the overlying roof, and as pressure was increased, the corresponding strain and deflection of the roof layer were measured until the roof failed. The ultimate strength of the roof agreed with the tensile strength of the roof rock (modulus of rupture) as determined in the laboratory; the modulus of elasticity as measured in place did not agree with the laboratory-determined values; the deflection and tensile strain in the layer in place showed good agreement with the theory of a body-loaded beam clamped at both ends. This procedure for determining the strength of a mine-roof layer is safer and less costly than successively widening a roof to failure. For example, it would have been necessary to mine the room to a width of 114 feet and a length of 228 feet to produce failure in this roof layer. The method is not necessarily limited to limestone; any thinly bedded rock type can be tested by this procedure when there is an open parting over the mined area.

Jan 1, 1958

By E. L. Litchfield

This report of work by the Federal Bureau of Mines has two primary objectives: A survey of the present status and usefulness of the minimum ignition-energy concept, and the presentation of recent data that are believed to bear on the safety problem associated with the ignition of combustible gases by electric discharges. The minimum ignition-energy concept has widespread applicability, especially to safety. The primary obstacle in making theoretical calculations of the requisite ignition energy is the lack of data on chemical kinetics and flame hydrodynamics. The new data on electrical ignition are representative of the great increase in knowledge that can be achieved by proper utilization of geometrical and electrical characteristics associated with the ignition source. CONCEPT OF MINIMUM IGNITION ENERGY The basic concept of a minimum ignition energy (the minimum amount of energy required to cause ignition) follows quite naturally from general physical principles and from the stability (lack of chemical reaction) of the gaseous mixture under the initial conditions. It also follows that if, as a first condition, lossless, instantaneous, and spatially localized energy can be injected and, as a second condition, the relaxation time for conversion of this type of energy to the type required for the reaction is short compared to some characteristic time scale of the ignition phenomenon, the energy requirements will be essentially independent of the type of energy source. Even if condition one cannot be fulfilled, it is sometimes possible to estimate the energy content of the gas required for ignition, and under these circumstances, condition one is fulfilled in effect. There are several instances where results can be interpreted for circumstances that effectively satisfy conditions one and two; these will be discussed later.

Jan 1, 1960

By E. J. Kloos

The Bureau of Mines developed a test for evaluating gas masks designed to protect against phosphine gas; phosphonium iodide is used as a source of phosphine. Gas masks approved by the Bureau for respiratory protection against phosphine include the GMC-SS-1, Mine Safety Appliances Co.; the LG-10 and LG-10G, Willson Products Division, The Electric Storage Battery Co.; and the 084-PHOV-R, Acme Protection Equipment Co.

Jan 1, 1966

By J. M. Stuve

Provisional values for the heat of formation of europium trichloride and europium sesquioxide were determined by solution calorimetry utilizing europium metal of more than 99-percent purity. The resulting values for the heats of formation of Eu203 (cubic) and EuCls (hexagonal) were -386,970 ±l,200 cal/mole and -218,740 ±650 cal/mole, respectively, measured at 298.15° K.

Jan 1, 1965

By S. D. Maksimovic

The Bureau of Mines identified and evaluated major sources of quartz dust during overburden drilling at a surface coal mine, The relative contribution of each source to the total dust hazard was estimated, using personal gravimetric and instantaneous dust-sampling devices. No attempt was made to determine actual dust generation rates. The major sources of dust at the drill rig during dry drilling opera-tions were the collector dump, drill shroud leakage, and drill stem seal leakage, These sources contributed 90 pct of the respirable dust and 89 pet of the respirable quartz dust generated during drilling, The collector dump cycle (21.6 pct of total drilling time) accounted for 38 pct of the respirable dust and 41 pct of the respirable quartz dust, with peak dust concentrations reaching 68 mg/m3. Shroud and drill stem leakage contributed 28 and 24 pct of the respirable dust and 32 and 16 pct of the respirable quartz dust, respectively. A dragline and second drill rig contributed the remaining 10 pct of dust and 11 pct of quartz dust. Gravimetric dust samples collected inside the drill cab and outside, near the cab door, averaged 1.65 and 1.43 mg/m3, respectively, with 6 pct respirable quartz.

Jan 1, 1985

By T. F. Anstett

The Bureau of Mines investigated the availability of platinum from known major deposits in market economy countries. Fifteen of these deposits contain demonstrated resources totaling 302 million troy ounces of platinum. Detailed geologic, engineering, and cost evaluations were performed on each deposit to determine its potential for platinum production. There are large amounts of demonstrated platinum potentially available from market economy deposits that were not analyzed owing to lack of adequate data or to technological limitations. These include 297 million troy ounces contained in the UG2 and Platreef of the Bushveld Complex, South Africa. This analysis indicates that about 11 0 million troy ounces (2.3 million ounces annually) of platinum are potentially available at the January 1980 producer price of $420 per troy ounce, nearly all from South Africa. An additional 85 million troy ounces occurring in Zimbabwean deposits would become available only through more than a quadrupling of that price. In order to meet projected world demand of 3.5 million troy ounces in 1990, platinum price may have to increase. Only one domestic deposit, the Salmon River in Alaska, is capable of producing platinum at $420 per troy ounce. Regardless of price, at assumed production capacities, domestic deposits could supply less than 10 percent of annual U.S. requirements.

Jan 1, 1982

By Richard J. Mainiero, Harry C. Verakis

The Bureau of Mines has conducted research to determine whether the total elapsed delay time for blasting bituminous coal in underground mines could be safely expanded beyond the present 500-ms limitation without igniting a methane or methane-coal dust atmosphere. The results indicated that the increase of total delay from 500 to 1,000 ms had no detectable effect on safety relative to incendivity as long as permissible practices were observed in all other aspects. Research was also conducted to evaluate the safety of 18-in hole spacing for delay blasting in coal relative to misfires. For a variety of permissible explosives, misfires were observed for about 50 pct of the holes at 18-in spacing. Based on this observation, the Bureau has recommended that the new regulations prohibit hole spacings of less than 24 inches in underground coal mines. Misfires were also observed for 24-in spacing, but the number of misfires and test shots was too small to sup- port any firm conclusions.

By R. V. Ramani, R. Bhaskar

"One of the primary means of control of health hazards from respirable contaminants in mine atmospheres is through design and operation of mines to meet mine health and safety regulations and recommended practices. A U.S. National Academy of Sciences study concluded that for significant progress in coal mine dust control, research should be directed more toward obtaining fundamental understanding of the origin, transport and characteristics of respirable coal mine dust. Theoretical and experimental studies on transport of dust · in mine airways, particularly coordinated efforts to validate theory with practice, are scarce. Some empirical models, developed on the basis of experimental data, are available but these models cannot be applied to new conditions. The purpose of this paper is to present the results of theoretical and experimental studies on the transport and deposition of dust in mine airways. This study is a part of an ongoing research project in the Generic Mineral Technology Center on Respirable Dust.In the paper, the assumptions of the modeling phase of the project and the development of a convectiondiffusion equation for dust transport in mine airways are outlined. The important aspect of the modeling effort is the capture of the deposition phenomenon. The experiments performed under controlled conditions in a typical mine airway, as well as under normal mine operating conditions, are discussed. The comparison of the model predictions with experimental results are made to identify critical areas of agreements and deviations. The implications of the findings and areas for further research and development are presented."

Jan 1, 1990

By John Fitzpatrick

In this Bureau of Mines investigation a device was developed that permits the determination of the modulus of elasticity of the stress-relief cores obtained in the process of making in situ stress measurements. This determination is made by hydraulically loading the external surface of the stress-relief cores and by measuring the corresponding borehole deformation. The theoretical relationship between the borehole deformation, the applied pressure, and the modulus of elasticity is presented. Also, experimental results obtained from measurements on a simulated stress-relief core made of aluminum and on a limestone stress-relief core are given. Because of the symmetrical loading obtained with this device, the isotropy of the core material can be evaluated. With this device it is also possible to study the effect of eccentricity, that is, the effect within cores in which the inner hole is not coincident with the long axis of the specimen.

Jan 1, 1962

By Forrest T. Moyer

In conjunction -with the statistical survey of the lime industr-.r in 1939, by the Bureau of Hines, producing companies reported the lime-fuel ratios attained in their plants according to type of kiln and kind of fuel. Each ratio, expressed as the number of pounds of lime burned by a unit quantity of fuel, was weighted according to the tonnage of quicklime pro- . duced at the reporting plant and grouped with similar data from other plants, so that an average ratio for each type of fuel and,kiln could be calculated. By this method the variables trat affect ratios of individual plants are more or less equalized, and the computed average lime-fuel ratios provide a fair measure of kiln and fuel efficiencies during 1939.

May 1, 1941

By David W. Wisecarver

This report describes a tool to engage and/or place a Bureau of Mines type gage to measure borehole deformation in a horizontal , 1½ - inch - diameter , stress relief borehole . The tool was successfully used at a borehole depth of 105 feet . Practical usage up to borehole depths of 200 feet might be realized . The tool was designed to work inside EX- size ( 1½ - inch ID ) diamond - drill drive casing used as drill rod and through which the deformation gage is guided into an EX- size stress relief borehole . Through laboratory experiments it was found that by exercising a reasonable amount of care the deformation gage could be placed at a point within a ± .01 foot distance of a predetermined depth in a horizontal EX- size hole and that the deformation measuring piston or plunger of the gage could be oriented in the borehole within 0.5 ° of a preselected angle of orientation in a vertical plane .

Jan 1, 1964

By Jerry W. Ramsey

The Bureau of Mines studied two Pennsylvania anthracites using low-temperature carbon dioxide adsorption. A modified form of the Brunauer-Emmett-Teller equation was used to calculate specific surface areas. Two mesh sizes of each anthracite were used to determine how gamma irradiation at 106 and 108 rads, both in vacuum and in the presence of air, affected the carbon dioxide surface areas. Results show that anthracites have a system of pores that are essentially all interconnected rather than isolated; that anthracites differ from one another in specific surface, which may correlate with density; and that irradiation in vacuum has no discernible effect on specific surface of anthracite, but irradiation in air does produce changes in specific surface.

Jan 1, 1966

By A. J. Barry

Two methods of testing anchorages of headed expansion-type mine roof bolts were investigated by the Federal Bureau of Mines to determine whether they are acceptable for general use. In both methods a load was applied to a tightened bolt with a hydraulic jack. A total of 80 tests, 40 using each method, was conducted in 4 test areas in 3 commercial coal mines. Electric resistance strain gages were used in all tests to indicate true bolt load as the bolt was tightened and when an additional load was applied with the hydraulic jack. The results indicate that: 1. The relationship between the true bolt load and the jack load will vary according to the test method until the two loads become equal. The bolt load-jack load relationship below this point can be determined only with strain gages. 2. The point at which the two loads become equal can be estimated by noting the load when the hardened washer becomes loose in one method, and when the bearing plate becomes loose from the roof in the other. It also can be approximated for either method of testing by noting the load when the first abrupt change in the slope of the jack load-bolt displacement curve occurs. 3. The anchorage characteristics of the test bolt can be determined from the data obtained from either method by examining the slope of the jack load-bolt displacement curve above the point at which the true bolt load is equal to the jack load.

Jan 1, 1960

By Thomas V. Falkie, R. Venkataramani

The method of analysis was to test a large model containing potentially significant variables and on the basis of the results obtained, to reduce the model to one containing only the essential significant variables. This stepwise procedure of "scanning" a large proposed model and subsequently condensing the model consisted of two cycles of the same series of computational procedures. Data Preparation A majority of the variables measured were continuous over a specific range of values; for example, the variable "Width Ratio" varied in practice from 0.25 to 1.00. However, "dummy" values were assigned to certain operational variables in order that these varia¬bles would have numerical expression. The following variables were described in this manner. Variable "Dummy" Value x3: Development/Pillaring 0, if pillar extraction was being done 1, if development mining was being done x4: Boxcut/Open Cut 0, if a box cut was being made 1, if an open cut was being made The variables under consideration are represented symbolically as follows: Y: Loading rate (tons per minuts): TONS/MIN x1: Ratio, width of cut/width of cutter: WDRATIO x2: Ratio, height of cut/diameter of cutter: HTRATIO x3: Development or pillaring: D/P

Jan 1, 1972

By J. H. East

The occurrence of hydrogen sulfide in the gas in solution in the oil produced from the Tensleep sandstone in the Elk Basin oil field in Wyoming constitutes a serious hazard to persons working in, that field. Aware of the general conditions because of petroleum reservoir studies being conducted in that field by its engineers, the Bureau of Mine's willingly agreed to a request of the Petroleum Administration for War to publicize the hazard and the measures for overcoming it. In October 1943 and November 1944, the Bureau of Mines investigated the method's used in handling the oil and in disposing of the hydro¬gen sulfide that occurs with it. This circular reports the results of these observations. HYDROGEN SULFIDE OCCURRENCE IN THE. ELK BASIN OIL FIELD The Elk Basin oil field is in Park County, Wyo., and Carbon County, Mont. It is about 18 miles north of Powell and 12 miles west of Frannie, Wyo. The original Elk Basin oil and gas field was situated in an eroded depression surrounded by an inner rimrock about 200 feet high with a bordering higher plateau about 500 feet above the basin floor.

Jan 1, 1945

By J. F. Barkley

During the present war emergency, under the urge of the Federal Government to store coal, the following questions are frequently asked by coal users: (a) Will the coal lose any, of its heating value in storage? (b) Will it slack and give a smaller-size coal? (c) Will its burning characteristics change in any way? (d) Will it catch fire from spontaneous combustion? (e) What precautions should be taken when coal is stored? DISCUSSION (a) Loss of Heating Value Studies by the Bureau of Mines show that the loss of heating value of coal in storage commonly has been overestimated. Various types of storage tests were made on New River, Pocahontas, Pittsburgh gas, and Sheridan (Wyo.) coals. The following is quoted from Bureau of Mines Bulletin 136, Deterioration in the Heating Value of Coal During Storage, by H. C. Porter and F. K. Ovitz (p. 8):

Jan 1, 1943

By Paul E. Loustaunau, Devah Galloway, Catherine Wetherby

This report describes a project in which Development of a Supervisory and Management Training Program for the Underground Coal Mining Industry was developed and evaluated. The project was carried out in two phases. The first phase was a research effort to develop specifications for the program. The second phase was a development and evaluation effort. In the second phase, training programs for first-line supervisors (section foremen) and for middle managers (mine/shift foremen and mine superintendents) were prepared in accordance with the specifications and evaluated by members of the industry. This report describes the project and presents the conclusions drawn there from.

Jan 5, 1983

By L. B. Berger

In this investigation, the ampoule type of carbon-monoxide (CO) detector which is manufactured under license of U. S. Patent 1,644,014 (October 4, 1927) was tested for sensitivity and reliability. This detector was devised primarily for examining the air of manholes and sewers for possible dangerous contamination with CO before workman enter those places, but dine to the simplicity of the device it may have a more general usage for examination of atmospheres which are known or suspected to be contaminated with CO. Some of the suggested uses are the examination of the air in garages, tunnels, mines, around blast furnaces, gas plants, and in the home.

Jan 1, 1930

By John L. Hill

"The Bureau of Mines is conducting research on the causes and methods for control of cutter roof failure in underground coal mines. This hazardous ground control problem exposes miners to the danger of falling roof rock and frequently results in massive roof failure. This report outlines the probable causes of cutter roof failure, which are proposed based on field investigations, numerical model analysis, and in-mine observations. Traditional methods of control are presented, as well as innovative methods based on mining concepts developed during earlier years of coal mining history. The report can be useful to a mine operator for assessing the causes of cutter roof failure on a site-by-site basis and for predicting the probability of its occurrence. A process is presented for selecting an optimum control method that includes both traditional and innovative control techniques for each of the various causes of cutter roof failure. INTRODUCTIONGround control research conducted by the Bureau of Mines is designed to develop technology that will aid in reducing the frequency of accidents associated with poor ground control conditions. Cutter roof failure often poses a safety hazard to miners and causes delays in production while massive roof falls are cleaned up and unstable roof is resupported. Implementation of control measures reduces the threat of injury to miners and prevents production delays.The definition of cutter roof failure used in this report separates this unique type of failure from other ground control problems, to aid in the analysis of the causes and in the development of control methods. The definition is as follows:Cutter roof failure in mine roof rock is a failure process that initially begins as a fracture plane in the roof rock parallel to, and located at, the roof-rib intersection. The fracture propagates upward into the roof over the mine opening at an angle usually steeper than 60° from the horizontal.The mappable extent of cutter failure may range in length from only a few feet to several hundred feet and may traverse entry-crosscut intersections without change in direction. Once initiated along the roof-rib line, a cutter may propagate away from the roof-rib line of one side of a room, cross the roof span, and continue along the other side of the room. It is important to note that this definition excludes a similar type of failure (sometimes referred to as ""kink roof') that has comparable characteristics but occurs in the center of the entry. (The reasons for this distinction are discussed in the ""Background"" section.) Researchers refer to the cutter failure discussed in this report as ""classic"" cutter roof failure; except for short deviations across intersections and entries, initial failure is confined to the roof-rib intersection."

Jan 1, 1986

By E. J. Kloos

The Bureau of Mines evaluated all previously approved gas masks to determine their ability to provide respiratory protection against each of the following six selected amines: ethylenediamine, diethylamine, n-butylamine, ethylamine, methylamine, and hydrazine. Minimum requirements were a 24-minute service life at a flow rate of 64 liters per minute (32 liters per minute for hydrazine) and an amine concentration of 1.0 volume-percent (0.5 volume- percent for hydrazine). The three masks meeting these requirements were the LG4, Willson Products Division, The Electric Storage Battery Co.; the GMD-SS, Mine Safety Appliances Co.; and the 084-PHOV-R, Acme Protection Equipment Co.

Jan 1, 1966