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By L. H. Adami

Heats of formation were obtained for four anhydrous crystalline sodium borates by hydrochloric acid solution calorimetry. The heats of formation at 298.15° K from the elements are NAB02, -233.2 ±0.6 kcal/mole; Na2B07, -786.4 ±1.0 kcal/mole; NaB305, -549.9 ±0.8 kcal/mole; and Na2B6013, -1,412.5 ±2.0 kcal/mole, The heats of formation from the constituent oxides are NaB02, -31.5 ±0.8 kcal/mole; Na2B407, -78.8 ±1.3 kcal/mole; NaB305, -44.1 ±0.8 kcal/mole; and Na2B8013, -96.7 ±1.5 kcal/mole.

Jan 1, 1968

By Theodore Christos

The Bureau of Mines sponsored an investigation of the thermal oxidative degradation characteristics of selected ingredients employed in the formulation and manufacture of conveyor belts. This work was done to supplement similar studies of samples from finished conveyor belts and thus provide basic data for correlation of the potential toxic behavior of a finished belt with that of the individual ingredients. This report covers the study of (1) basic polymers (styrene-butadiene, neoprene), (2) reinforcing fibers (Nylon 6,6, Dacron, viscose rayon), (3) flame-retardant plasticizers (tritolyl phosphate-isomeric mixture, tri-p-tolyl phosphate, tributyl phosphate, tris (dichloropropyl) phosphate), (4) plasticizers (diphenylphtha1ate, di-(2-ethylhexyl) sebacate), and (5) a vulcanization accelerator (2-mercaptobenzothiazole).

Jan 1, 1977

By Fred N. Kissell, J. E. Matta, J. C. LaScola

The Bureau of Mines made laboratory absorption measurements on oil shale samples, which showed that the amount of methane absorbed is proportional to pressure and oil yield, and can be much larger than would be predicted based solely on porosity. Oil shale cores collected in the field were also measured for their gas content using the Bureau of Mines direct method, Cores taken from deep locations and far from outcrops yielded more gas than cores from shallower locations or at outcrops, when taking into account variations in oil yield, and all data indicate that oil shale mines that are both deep and far from an out- crop will emit low levels of methane gas.

Jan 1, 1977

Improve the safety of mine workers by developing a means of forecasting impending roof falls in underground mines. Approach The Bureau of Mines, through in-house and contract research, has developed the Roof Fall Warning Device. This battery-operated, portable electronic system forecasts roof falls by detecting and interpreting high-frequency rock noise, The technology has shown potential for detecting stress-related failures in a variety of underground environments. How It Works All geologic materials produce high-frequency acoustic emissions when they encounter an increase in stress. These ultrasonic frequency range events ( >20kHz) are well above the audible range of human hearing, very small in amplitude and duration, and can only be detected with sophisticated electronic equipment.

Jan 1, 1990

By Charlie Wyche

Principal mineral products in the Dominion of Fiji were gold, silver, pit and quarry construction materials, and cement. In 1981, the combined value of these commodities accounted for about $11.6 million,2 over 85% of the total value of mineral output. Production of cement, sand and gravel, and quarry products increased substantially above the 1980 level. Mining bated on gold production was decreasing, and employment in the industry was declining. The better grade deposits in the one active mine were worked out, and only another 10 years' production at current rates was estimated to remain. While the high world gold price of 1979-80 led to intensive exploration, there has been little sum.

Jan 1, 1983

By Richard H. Singleton

Native asphalt was produced in 1980 by six companies in four States. Leading States were Texas and Utah. Output decreased 22% in 1980 to 1.25 million tons while value decreased 2% to $25.0 million. Bituminous limestone was produced by Whites Uvalde Mines and by Uvalde Rock Asphalt Co. in Uvalde County, Tex.; by Southern Stone Co. in Colbert, Ala.; and by Barton County Rock Asphalt Co. in Barton County, Mo. The product was used mainly in street and road repair. Gilsonite was produced by American Gilsonite Co. in Uinta County, Utah, and by Ziegler Chemical and Mineral Corp. in Weber County, Utah. This material was used for purposes other than road repair.

Jan 1, 1981

By Lloyd A. Morley

To reduce safety and production problems, it is essential that the electrical operating characteristics of coal mining equipment and their electrical subsystems be clearly understood. The Bureau of Mines and the Pennsylvania State University have developed techniques to monitor and analyze several of the critical parameters. A unique system for measuring traction locomotive consumption at the machine has been assembled and utilized. Conclusions from 27 continuous miners show that voltage levels are directly tied to machine efficiency. The Bureau of Mines and Pennsylvania State University, along with West Virginia University, are currently monitoring and accessing mine power transients. Results exhibit that voltage transients of three to five times the line -to-line value are common on underground distribution systems.

Jan 1, 1975

By Jack E. Fraley

Poor lubrication reduces the life of wire hoist ropes when they are used in corrosive environments. Although lubricants are added to ropes during the manufacturing process, these lubricants can deteriorate during use, and it is often necessary to add more lubricant to both the interior and exterior of the rope while it is in service. The U.S. Bureau of Mines evaluated the effectiveness of synthetic lubricants, using electromagnetic nondestructive testing (NDT) to measure deterioration in ropes while they were in service. For nonpressurized lubricant applications, synthetic lubricants appear superior to petroleum-based lubricants in their ability to penetrate to the interior of a rope. Therefore, the synthetics offer better wear and corrosion protection.

Jan 1, 1990

By Thomas P. Mucho, Dennis Dolinar, Christopher Mark

During the 1990s, the former U.S. Bureau of Mines conducted a number of field studies in which the performance of different types of roof bolts were evaluated in different geologic environments. The studies used a standard suite of measurements, including multipoint extensometers, strain-gauged roof bolts, and roof bolt load cells. The sites were chosen to investigate the effect of a variety of parameters, including installed tension, bolt capacity, grout annulus, and horizontal stress orientation. Although not fully successful, the measurements provided valuable insights into each of these issues. They also showed that instrumentation and monitoring have important advantages over observational methods for comparing the performance of different roof bolting systems.

Jan 10, 2000

By James M. Spear

The U.S. Bureau of Mines and the U.S. Geological Survey conducted a mineral survey of the Black Butte RARE (I area during the summer of 1981. The study area encompasses 17,800 acres [27.8 sq mi (7,233 ha)] along the course of the Black Butte River, 13 mi (22 km) southeast of Covello, California. No mineral deposits were identified by the U.S. Bureau of Mines during this survey. Assay results of samples taken in this area indicate only trace amounts of manganese, chromium, and nickel. No radioactive or fluorescent minerals were detected. No oil and gas, coal, or geothermal leases have been recorded for the study area.

Jan 1, 1982

By J. W. Miller

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and from the data developed to determine: 1. Which coals either as mined or after beneficiation by conventional preparation are chemically suitable under present standards for producing metallurgical coke. 2. Which coals require special and more intensive treatment in preparation than is now practiced. 3. Which coals cannot be considered potential sources of metallurgical coke, regardless of preparation by present-day methods. This report is one in this county series that describes the preparation characteristics of the coals of Lee County, Va.

Jan 1, 1957

By Donald N. H. Chi

This Bureau of Mines report is concerned with a theoretical study of the aerodynamic response of a single mine entry to flame-induced disturbance. The unsteady, one/dimensional, compressible flow equations were solved using the method of characteristics. This study was primarily undertaken to determine the feasibility of extending the method of characteristics to study the aero-dynamic response of complex mine networks. It was demonstrated that although the technique has merit in studying the complex wave interaction in single entries, it appears to be too unwieldly and too expensive for network analysis. Effort was also directed at a further study of the dispersion and filtering characteristic of aerodynamic disturbances in mine passageways.

Jan 1, 1975

By T. R. Jolley

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and, from the data developed, to determine: I. Which coals either as mined or after beneficiation by conventional preparation are chemically suitable under present standards for producing metallurgical coke. 2. Which coals require special and more intensive treatment in preparation than is now practiced. 3. Which coals cannot be considered potential sources of metallurgical coke, regardless of preparation by present-day methods. This report is one in the county series that describes the preparation characteristics of the coals of Bell County, Ky.

Jan 1, 1957

By J. T. May

The Federal Bureau of Mines investigated the extraction of lithium from hectorite-type clay deposits found on the Nevada-Oregon border. Two clay samples were used in the investigation; one contained 0.36 pct Li and the second contained 0.64 pct Li. The purpose of this laboratory-scale research was to determine how these clays responded to different extraction techniques. Extraction techniques investigated were sulfuric acid leach, sulfuric acid bake-water leach, and roast-water leach procedures with cholorides, sulfates, carbonates, and combinations of these reagents. The processing characteristics of the clay samples showed significant variations, and no one technique was effective for both materials. Lithium extractions near 90 pct were achieved during these exploratory studies.

Jan 1, 1980

By S. P. Kinney, A. C. Fieldner, S. H. Katz

"The regrettable death of James S. Cunningham, Foreman Miner, attached to Bureau of Mines Rescue Car No. 2, while wearing a half-hour type oxygen breathing apparatus in a gasoline storage tank at Trinidad, Colorado, raised the question as to the possibility of gasoline vapors permeating the rubberized fabric of the breathing bags of such apparatus.It is known that most gases and especially certain organic vapors permeate rubber, by solution or a similar process. The rubber becomes saturated with the gas and if a concentration of gas is maintained on one side of the rubber sheet it slowly gives off gas from the other side. It of course takes some time for the gas to diffuse through the rubber and the length of time before it reaches the other side is proportional to the thickness of the rubber. The amount of gas that passes through per unit of area in unit time increases with the concentration of gas and also varies with the structure and composition of the rubber.It has been suggested that the gasoline vapor could not have penetrated into the interior of an oxygen breathing bag because the pressure is greater on the inside, but this is not true as the process of permeation by solution in the rub¬ber is affected only by the difference in the partial pressures of gasoline vapor on the inside and outside of the bag. The positive oxygen pressure on the inside can only prevent the entrance of gasoline vapor through measurable holes, and has no effect on permeation by diffusion through the rubber.A sample of gasoline was obtained from the tank in which Cunningham met his death. Examination by Dr. E. W. Dean of the Petroleum Division of the Bureau of Mines gave the following results.This shows the gasoline to be heavy and typical of the gasolines sold throughout Colorado for motor fuel A. Salvus half hour oxygen apparatus was arranged with the breathing bag only in a gas tight box in which the space was kept saturated with the vapor of this gasoline. The main part of the apparatus was outside the box. Oxygen from the apparatus was breathed by a man in the usual manner. Gas samples were taken from the box at intervals to determine the concentration of gasoline vapor, also samples of the oxygen breathed were taken from a side tube in the mouthpiece. The room temperature was 75°F. The concentration of gasoline vapor in the box at the beginning of the test was 4.3%. The man breathing from the apparatus thought he detected gasoline in his oxygen in two minutes after starting the test. Analysis of the inspired oxygen at this time showed 0.03% gasoline vapor. The same man remained on the apparatus for 18 1/2 minutes without suffering any ill effects. His place vas then taken by another man who wore the apparatus until the oxygen was exhausted without noticing more than a trace of gasoline at any time. At the end of the test the inspired oxygen contained 0.07% gasoline vapor. The total time of test was 38 minutes."

Dec 1, 1919

By Robert H. Essenhigh

A stirred reactor (SR) combustion system has been developed to gather information on the mechanisms of ignition and flame propagation of coal dust under conditions similar to those found in coal dust explosion flames. The prime scaling variable considered in this study is that of rapid particle heating (between 105 and 106°K/sec) which is accomplished by means of turbulent mixing during combustion. The SR combustors tested in this study have consisted basically of spheres hollowed in the centers of refractory housings. Coal and air mixtures have been injected into the spherical combustion chambers through a single jet, two opposed jets or four opposed jets. The diameters of the jets have ranged from 0.63 to 0.22 cm. The volumes of the combustion chambers have ranged from 1.0 to 0.2 liters. The reactors have been equipped with thermocouples embedded in the combustion chamber wall as well as a thermocouple located in the exhaust gas stream. In the latter versions of the SR, provisions were made for both solid sampling and gas sampling of the reactant stream exiting from the combustion chamber. Experiments have been carried out using pulverized bituminous coal. The coal has been reacted in an SR in mixtures of air and air/nitrogen. These experiments have provided information on the mode of ignition of the coal as well as yielding information on the kinetics of coal pyrolysis through the use of SR theory. Ash tests performed on the reacted samples collected from the SR indicated that the majority of the values of weight loss percentage were between 60 and 70 percent. The percentages of weight loss were relatively unaffected by changes in temperature which varied between 1100 and 1700°K and by changes in residence time which varied between 10 and 20 millisec. Volatile matter tests performed on the samples indicated that the volatile matter left in the char ranged from 3 to 20 percent of the original content. By assuming that all the mass loss was due solely to pyrolysis with no combustion occurring at the particle surface, Q-factors for each test have been calculated. The results of these calculations indicate an average value of Q equal to 1.88. This finding shows that the majority of mass loss can be attributed to pyrolysis. The fact that the extent of reaction varies only slightly over the range of test conditions has been examined in the context of the two component hypothesis of coal constitution. This approach leads to the conclusion that the reaction of the "easily evolved" component VMI is extremely rapid and that the majority of it is removed from the coal in times less than the residence time in the system. This means that the volatile residue remaining in the char can be considered to consist of component II, VMII. If the mass fraction of VMI = 0, then an activation energy of 18.0 kcal is obtained for the pyrolysis reaction. If the mass fraction is assumed to be 0.75, the activation energy increases to 31.2 kcal.

Jan 1, 1978

By R. R. Sayers

The added hazards to mining incident to oil and gas wells penetrating the coal measures in proximity to mine workings , have long been recognized in those fields where the extraction of oil , gas , and coal , has been in progress for a number of years . The history of these fields is replete with stories of serious mine fires , explosions , and miraculous escapes from both fires and explosions due to either oil or gas finding its way into the mine workings through the strata , or by mining into an unknown or uncharted and abandoned oil or gas well that had not been properly plugged . The Director of the Bureau of Mines , in response to numerous requests from coal operators and oil and gas operators , called a meeting in 1913 to discuss necessary precationary measures to take when drilling oil or gas wells through workable coal beds and to try , if possible . to formulate a set of regulations that might serve as a guide to those persons preparing regulations covering the drilling of oil and gas wells in the various coal producing States . This meeting was attended by representatives of the coal , oil , and gas industries , State geologists , State mine inspectors , and representatives of the Bureau of Mines . A committee was appointed to prepare a set of regulations , which was later published as U.S.Bureau of Mines Technical Paper 53 ; the discussions and results of the meeting werepublished as U. S. Bureau of Mines Bulletin 65 . Later , the American Institute of Mining and Metallurgical Engineers appointed a committee to draft a model law for the use of the legislature of any State concerned . This committee made its report on April 27 , 1928 . Several of the coal mining States now have more or less comprehensive regulations governing the drilling of oil or gas wells through workable coal beds , others have regulations that are inadequate , while some have no regulations . The State of West Virginia recently enacted a law containing reg lations which are the result of a comprehensive and careful study of the problem .

Nov 1, 1929

By A. U. Miller

The added hazards to mining incident to oil and gas wells penetrating the coal measures in proximity to mine workings , have long been recognized in those fields where the extraction of oil , gas , and coal , has been in progress for a number of years . The history of these fields is replete with stories of serious mine fires , explosions , and miraculous escapes from both fires and explosions due to either oil or gas finding its way into the mine workings through the strata , or by mining into an unknown or uncharted and abandoned oil or gas well that had not been properly plugged . The Director of the Bureau of Mines , in response to numerous requests from coal operators and oil and gas operators , called a meeting in 1913 to discuss necessary precationary measures to take when drilling oil or gas wells through workable coal beds and to try, if possible . to formulate a set of regulations that might serve as a guide to those persons preparing regulations covering the drilling of oil and gas wells in the various coal producing States . This meeting was attended by representatives of the coal , oil , and gas industries , State geologists , State mine inspectors , and representatives of the Bureau of Mines . A committee was appointed to prepare a set of regulations , which was later published as U.S.Bureau of Mines Technical Paper 53 ; the discussions and results of the meeting werepublished as U. S. Bureau of Mines Bulletin 65 . Later , the American Institute of Mining and Metallurgical Engineers appointed a committee to draft a model law for the use of the legislature of any State concerned . This committee made its report on April 27 , 1928 . Several of the coal mining States now have more or less comprehensive regulations governing the drilling of oil or gas wells through workable coal beds , others have regulations that are inadequate , while some have no regulations . The State of West Virginia recently enacted a law containing reg lations which are the result of a comprehensive and careful study of the problem .

Nov 1, 1929

By D. J. Parker

Since the introduction of electricity into the mines of the United States , the hazards incident to the industry have increased materially in both coal and metal mines . For economic reasons the tendency at present , particularly in coal mining , is decidedly toward the adoption of electrical mine machinery , including alternating current machinery , on a more extensive scale than ever before . Obviously, the growing use of such equipment will result in an ever -increasing number of underground transformer stations . The principal electrical hazards in mines are threefold ; fire , explosion, and contact . Of these , fire is the greatest hazard involved in the use of electricity underground , and several fires have originated in underground transformer and motor generator set stations . The fire hazard due to improperly installed and poorly maintained underground transformer stations is an ever-present one , and failure to take the necessariman remedial action is likely to result , sooner or later, in the destruction of life and property . Upon suggesting the necessary corrective measures with respect to such installations , one is often confronted with the statement to the effect that even though this particular hazard has existed over a period of years , there have been no unfavorable results therefrom thus far . Frequently , the desirability for action is not apparent to the mine management until it is too late . Because a mine has a record free from fires , explosions , etc. , over a number of years of operation during which these hazards existed , such good fortune should not be taken as a guarantee that this or any other mine is immune from these common dangers . When the elements of an existing hazard are properly balanced or in the right proportion, the unfortunate combination must of necessity culminate in misfortune of one kind or another. The fire hazard due to underground transformer installations can be very definitely minimized by proper installation and maintenance . In coal mines the transformer banks , connected to 2,300 and occasionally to 4,400 volt circuits , are often found located in open- ended crosscuts , mounted on concrete or timber foundations , and in nonfireproof surroundings .

Jul 1, 1930

By F. J. Bailey

"In the fall of 1919, the U.S. Bureau of Mines began an inquiry as to the possibility of utilizing airplanes in conjunction with its rescue work, for quickly transporting engineers and oxygen rescue-apparatus to mine disasters.It was realised that this proposed use of airplanes has serious limitations, and if it were feasible, that the Bureau would have to rely on the cooperation of the established aviation fields of the U. S. Air Service for furnishing airplane service. Therefore Van. H. Manning, Director of the Bureau of Mines, under date of October 28, 1919, wrote the Director of Air Service outlining the rescue and first aid organization of the Bureau, the location of headquarters of district engineers, the distribution of safety cars and stations, and other essential details, and asking whether the Air Service could cooperate with the Bureau in the event of serious mine disasters. Major-General Charles T. Menoher, Director of Air Service, responded that the Air Service would be glad to cooperate insofar as possible, and designated those Air Service stations nearest the district engineers' headquarters, which might be best able to assist.The Bureau of Mines has ten mine rescue cars and eight mine safety stations distributed throughout the mining regions of the United States. The cars are each equipped with sets of oxygen mine-rescue breathing-apparatus and first-aid supplies. The car personnel consists of a mining engineer, surgeon, foreman, first-aid miner, clerk and cook. A foreman miner is in charge of each station and at five of the eight stations are mine safety trucks. The work of the cars and stations is two-fold; (1) Assisting in rescue and recovery work at mine disasters, and (2) training miners in mine rescue and first-aid methods, and in investigations looking to prevention of mine accidents. The country is divided into nine safety districts, with nine district engineers in charge."

Apr 1, 1920