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By H. A. Watson

Fluorine-containing polymers are comparatively new materials that exhibit very desirable characteristics not usually found in non-fluorine containing polymers. Among these characteristics are heat and flame resistance, desirable electrical properties, and chemical inertness. Polytetrafluoroethylene and polymonochlorotrifluoroethylene are examples of such polymers commercially available. In practical applications it is reasonable to expect thermal position of these materials if they are subject to high enough temperatures. The temperatures at which thermal decomposition takes place and the nature of the gaseous products of decomposition are considered pertinent data in intelligent use of these materials. The purpose of the tests discussed herein was to determine: (1) The temperatures at which gases were produced when small specimens of the two polymers were located and (2) determine the identity of the major constituents of gaseous products.

Jan 1, 1950

By G. W. Jones, R. E. Kennedy

Most gasolines and naphthas are mixtures of paraffin- series hydrocarbons and comprise such substances as pentane , hexane , heptane , octane , and others up to perhaps dodecane . Many of these hydrocarbons , when mixed with the proper proportions of air and ignited , are highly explosive . It is due to this characteristic that gasoline has become so important as a fuel in internal -combustion engines . Gasoline and naphtha also are used in the industry as solvents and cleaning agents . Because of their explosive properties they are dangerous to use unless the composition is so chosen that the vapor pressure of the mixture is not high enough to produce explosive mixtures with air at the temperature at which they are used . Hydrocarbon mixtures may be made less hazardous by adding some incombustible liquid , such as carbon tetrachloride . Barrier reports the amount of carbon tetrachloride that must be added to different naphthas to render such mixtures free from fire and explosion hazards . He found that the amount of carbon tetrachloride that must be present in the final mixture of naphtha and carbon tetrachloride varied with the density of the naphtha . Of the naphthas tested the amount of carbon tetrachloride necessary to render such mixtures free from fire and explosion hazards ranged from 30 to 70 percent . .. Determination of the fire and explosion hazards of carbon tetrachloridehydrocarbon mixtures would be easy if the boiling points and vapor pressures of the two were the same at any given temperature . The fact that carbon tetrachloride boils at 76° C. while the boiling points of the hydrocarbons found in gasoline and naphtha may range from 37° , the boiling point of pentane ,

Nov 1, 1934

By H. B. Humphrey, J. J. Forbes

"In accident prevention, a study of statistical data is necessary to determine primary causes of accidents to devise means to eliminate causes at the original sources. Explosions in coal mines of the United States during the 10 years ending December 31, 1931, ranked third in the causes of fatal accidents; they constituted 16.2 per cent of all fatal accidents in bituminous mines and 8.4 per cent of all fatal accidents in anthracite mines. A study of coal-mine explosions in Pennsylvania, with approximately 160,000 men employed in anthracite mines and about 145,000 in bituminous mines or about 205,000 out of -the approximately 525,000 men employed in all coal mines of the United States, should give information of value to all persons endeavoring to reduce or eliminate coal-mine explosions. This circular reviews explosions of gas or dust or of both in the coal mines of Pennsylvania to show the hazard of gas and dust, to point out the influence of certain factors in causing explosions, and to emphasize the efficacy of explosion-preventive measures.The data published annually by the State Department of Mines and of the United States Bureau of Mines were used in compiling the tables of explosions. Through the cooperation of W. H. Glasgow, secretary, Department of Mines of Pennsylvania, and his assistants, many doubtful cases were clarified, so that as far as recorded the history is comparatively complete. Figures used in compiling some of the tables were furnished by W. W. Adams, chief statistician, demographical division, United States Bureau of Mines.Anthracite in the Wyoming Basin of Pennsylvania was used locally by gunsmiths in 1755, by blacksmiths in 1769, and as domestic fuel in 1808.Mining and shipments developed slowly between 1806 and 1812, but more rapidly after that.Early mining along the outcrops gave essentially no trouble from gas, but by 1870, when State inspection was established, explosions were frequent; ventilation was crude and accumulations of gas were generally ""brushed"" or burned out.Table 1 lists 1,232 ignitions and explosions of gas in anthracite mines from 1870 to 1932, inclusive, every one of which was accompanied by loss of life. Some details are given of 110 representative cases in which five or more lives were lost or in which it appeared that some violence was present.During the period 1870 to 1932, inclusive, gas explosions caused 2,213 fatalities, or an average of about two deaths for each ignition or explosion. Records are not available as to the number injured in these and in other explosions where no deaths occurred, but from a study of explosion reports it appears probable that the number injured exceeds the number killed. In the 110 cases described, 599 were killed and 294 were injured. As shown in Table 2, fatalities from gas explosions averaged 8.3 percent of the total fatalities in Pennsylvania anthracite mines from 1870 to 1931, varying from 6.0 percent in 1931 to 13.1 percent in 1927."

May 1, 1933

By John S. Berber

Tar produced as a byproduct from low-temperature carbonization of coal contains only small amounts of valuable lower boiling tar acids but relatively high percentages of high-boiling tar acids. These high-boiling tar acids are characterized by a high degree of alkylation and can be converted into the lower boiling homologs by catalytic treatment to remove the alkyl groups or decrease their chain lengths.

Jan 1, 1965

By R. Barany

The heat of formation at 298.15 ° K of muscovite was determined by solution calorimetry . The value obtained for the heat of formation from the elements was -1,421.2 ± 1.3 kcal / mole , and the value for the heat of formation from the oxides was -55.9 ± 1.3 kcal /mole .

Jan 1, 1964

By R. L. Crosby

The effect of indium on the solid solubility of calcium and of silicon in magnesium was studied using metallographic, X-ray diffraction, and electrical resistivity techniques. The addition of 2 weight-percent or more of indium reduced the solid solubility of calcium in magnesium by forming a compound containing indium and calcium. Indium additions have no perceptible effect on the solid solubility of silicon in magnesium.

Jan 1, 1963

By R. V. Lundquist

The specific conductance of solutions of sodium hydroxide and of sodium aluminate was directly proportional to the temperature. The specific conductance of sodium aluminate solutions with identical sodium ion concentration and at constant temperature decreased with increase in aluminum concentration. The aluminate ion population in solution was shown to consist of a mixture of monovalent and polyvalent ions. Aluminate ions did not influence the temperature dependence of pH in caustic solutions containing sodium aluminate. The density and viscosity of a solution was inversely proportional to the temperature and directly proportional to the concentrations of sodium and aluminate ions.

Jan 1, 1965

By N. Kumar Kittusamy, Richard E. Miller

This field study evaluated a newer and older dozer at a construction site. Both dozers performed similar activities in the same location within the construction site. Two operators participated in this study. One operator used the older equipment and the other operator used the newer equipment. Jolting and jarring measurements were taken at the seat/operator interface and at the floor of the cab. The result of this field study indicates that the newer dozer was better than the older dozer.

By T. A. Henrie, D. C. Fleck, D. G. Kesterke

Uranium metal was electrowon from uranium dioxide dissolved in fluoride melts . The UO₂ was fed directly to the cell in a continuous manner . Electrolysis was performed at 1 , 200 ° to 1,300 ° C in electrolytes composed of UF4 , LiF , and BaFa . A single regulus of metal was collected in a confined area of the crucible . Product purity of 99.8 percent was attained . Carbon was the major contaminant . Compartmented cells were studied as a means of confining the oxide feed to the vicinity of the anodes .

Jan 1, 1964

By Victor Himel

This report documents a systematic approach towards implementing an improved ensemble for the mine rescue team system that will protect against the hazards of mine rescue and recovery and will also afford improved performance through increased comfort and maneuverability, lighter burdens, and improved human engineering designs. In the first part (Task 1) the mine rescue team's protective needs were defined along with the test methods required to evaluate whether a particular piece of gear met these needs. Task 2 assessed existing gear against performance criteria and standards developed in Task 1. Task 3 consisted of the conceptual design and construction phases of the MRPE program. Special consideration was given to advanced concepts, materials, and equipment.

Jan 1, 1982

By L. W. Higley

Procedures were developed for reclaiming high-temperature alloy scrap in the form of standard cobalt-base alloy. A cobalt-base, multicomponent, high- temperature alloy, such as S-816, can be successfully melted from scrap, and its specified chemical composition can be retained. Induction furnace melting in a controlled atmosphere was used to obtain ingots that were subsequently fabricated by impact forging to provide specimens for heat treatment and testing. Of the numerous metal elements in S-816 alloy, only small quantities of molybdenum were lost in the melting operation as finally developed. Test results indicated that the scrap material, after melting, forging, and heat treatment, was equivalent in room-temperature tensile strength, in high-temperature creep and stress-rupture properties, and in chemical composition to commercially produced S-816 alloy made from virgin material.

Jan 1, 1963

By E. G. King

The work described in this Bureau of Mines report was undertaken to fill a need of industry for high-temperature heat-content data for uranium tetrafluoride. Without such data, heat balance evaluations of processes involving this substance are seriously hampered. Measurements of the heat content of uranium tetrafluoride were conducted at temperatures from 298° to 1,350° K. The melting point and heat of fusion were determined. The results are presented in suitable tabular form, and representative heat-content equations are included.

Jan 1, 1961

By Sathit Tandanand

This report presents a Bureau of Mines study on the time-dependent behavior of coal measure rocks for future implementation in stability analysis and safety evaluation of in-mine rock structures. This initial study focused on moisture adsorption rate and strength degradation of shales in Pennsylvanian coal-bearing strata in the Illinois Basin. A reaction of clay minerals in Illinois shales with atmospheric water vapor was hypothesized as the adsorption and strength degradation mechanism. Part of energy exchange between shales and the environment was attributed to a free energy controlled by pore pressure of the rock and partial pressure in the environment. The relationships between adsorption versus time and strength degradation versus moisture content were derived and correlated with the experimental data. Partial saturation at various levels of relative humidity occurs within approximately 2 weeks at room temperature. The strength of shales tested decreases linearly with increasing moisture content. When the moisture exceeds 7 pct of the dry weight, these Illinois shales become unstable. To this end, the moisture content is a good predictor of rock strength for shales.

Jan 1, 1987

By Earl R. Maize

This is the first of a series of reports dealing with development of a method of strengthening bituminous-coal-mine roof. Later reports will describe the progress made with injecting high cohesive and adhesive bonding agents into bedding planes and mine tests of roof strata strengthened by the bonds formed. The concept of strengthening roof strata in coal mines by inserting steel rods in the form of bolts has been widely accepted by the coal industry. The benefits of increased production and safety derived from this type of roof support has more than justified the increased cost of roof bolting. However, not all coal-mine roof structure is amenable to this type of support, and failures occur owing to the heterogeneity and variable character of mine-roof strata.3/

Jan 1, 1957

By Frank D. Lamb

Pyrophyllite, a hydrous aluminum silicate (Al2 Si4O10 (OH)2 ) has been mined in North Carolina and marketed without beneficiation for the past 100 years, but recent demands for higher-grade material indicate that an economical concentration method is needed for at least a part of the pyrophyllite production. Past production has depended upon selective mining and hand sorting, which is often unsatisfactory because of the finely disseminated character of the ores. The major impurity in North Carolina pyrophyllite ores is quartz, which accounts for the abrasiveness of the commercial product. Since pyrophyllite is only slightly heavier than quartz, those ores cannot be beneficiated by simple gravity-concentration methods. Some separation can be attained by differential grinding and air classification because of the difference in hardness of the two minerals) but the separation is not sharp. Froth flotation of pyrophyllite from Quartz has never been attempted commercially, but if the demand for high-grade material is sufficient, it would seem that this process offers the most premise of being economically feasible.

Jan 1, 1950

By Neil B. Young

Analytical results for nahcolite, dawsonite, total extractable alumina, and oil yield are presented for samples representing Green River Formation oil shales in the saline section of two cores from Colorado's Piceance Creek basin. Analyses are also reported for samples extending the analyzed section of Colorado corehole No. 3 beyond that reported previously. These data permit evaluation of the deposit for possible production of three coproducts--shale oil, alumina, and sodium carbonates--from the saline section of the formation at these sampled points.

Jan 1, 1970

By John C. Holtz

The Bureau of Mines studied air contamination caused by diesel exhaust in a 10,000-ft ventilated tunnel. Sequential air samples were taken at the ends and middle of the tunnel during an operating cycle. Observed and calculated results for carbon dioxide, carbon monoxide, and nitrogen oxides were essentially in agreement. Nitrogen dioxide was present only in trace amounts. It was found that contamination was related to the volume of ventilating air, the number of haulage trips, train speed, and engine load.

Jan 1, 1968

By C. C. Shale

A semicommercia1, high-temperature electrostatic precipitator and adjunct equipment are described, and operating characteristics at 1,470° F and 80 psig are presented for both positive and negative polarity. Removal efficiency for negative corona waS about 91 to 96 percent while that for positive corona was only about 75 to 77 percent. Results are compared with those from bench-scale investigations, and equipment limitations are discussed. Theoretical aspects of the precipitation process are related to the operating characteristics.

Jan 1, 1969

By E. J. Kloos

Two self-contained breathing apparatus of the closed-circuit compressed-oxygen type were evaluated for performance at 32° to -25° F. Low-temperature effects of oxygen and carbon dioxide concentration, visual properties of the facepiece, and mechanical operation of the apparatus were studied. Although operation varied with the wearer, his breathing rate, the apparatus precooling time, and the temperature, results suggest that general use of currently approved compressed-oxygen closed-circuit breathing apparatus be limited to temperatures above 32° F.

Jan 1, 1968

Develop a new method for coal mint pillar stability evaluation and design based on pillar load measurements. Approach A novel approach to chain pillar stability evaluation and design for longwall coal mining panels has been developed by the Bureau of Mines. The evaluation approach uses an INTEGRITY FACTOR as the criterion for stability. Hydraulic borehole pressure cells developed by the Bureau are used to measure stresses in a pillar for stability evaluation. The results are used to improve the pillar design.

Jan 1, 1989