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By J. M. Kuchta

The Bureau of Mines used laminar hot air jets of l/8- to 3/4-inch diam-eter to determine the hot gas ignition temperatures of various combustible vapor-air mixtures. The combustibles were n-hexane, n-octane, n-decane, a hydrocarbon jet fuel (JP-6), and an adipate ester aircraft engine oil (MIL-L- 7808). Minimum ignition temperatures occurred at a fuel to air weight ratio of about 0.5 and were not greatly sensitive to variations of fuel concentra¬tion. Moderate variations of jet velocity also had little influence on these ignition temperatures. However, these temperatures decreased with increase in heat source dimensions (jet diameter). The hot gas ignition temperatures of the combustibles were not necessarily much greater than corresponding autoignition and wire ignition temperatures when the size (,F the heat source and the ignition criterion were the same.

Jan 1, 1966

By D. F. Scott

The purpose of this study was to determine if miners were at risk from exposures to chemicals used in the mining industry and determine the nature and sources of the illnesses and injuries. The U.S. Mine Safety and Health Administration?s (MSHA) employment and accident, injury and illness database was reviewed. There were 2,705 cases of chemical-related injuries and illnesses reported from 1999 through 2006, involving 66 different chemicals. The main source (cause) of chemical-related cases was acids/alkalis (about 39%). The primary nature (effect) of chemical-related cases was chemical burns (about 57%). The job classification where workers incurred the most chemical-related injuries and illnesses was cleaning plant operator/media operator/boney preparation plant operator/crusher worker (cleaning plant operators are responsible for maintenance of plants, media operators are responsible for handling reagents, boney preparation plant operators oversee removal of ?bone? from coal, and crusher workers use large crushers to break mined material). From 1999 through 2006, the rate of ?nonfatal days lost? and ?no days lost? (resulting from injuries) did not change significantly; however, the rate of illnesses decreased significantly. Chemical burns accounted for a large number of injuries; mining companies should carefully examine their personal protective equipment (PPE) requirements, training methods and safety culture to ensure that their workers are protected.

Jan 1, 2009

By Allen D. Look

Uninterrupted shaft operations are an important economic factor in mine operation, and good shaft support is an important aid in preventing accidents and interruptions. More permanent supports can cut the hazards, costs, and delay incident to replacement of conventional timbers, especially where subject to decay. Installation of prestressed, precast concrete shaft supports in 100 feet of shaft at the Banner mine, Lordsburg, N. Mex., nave a satisfactory permanent installation in a section of shaft that had given trouble with conventional timbering. Use of rock bolts supporting gunited wire netting around the rock walls of the shaft prevented sloughing. No attempt was made in this paper to arrive at comparative costs of installation of various types of support. However, it was indicated that use of a lighter weight aggregate would be desirable in further use if prestressed precast members as placed in the Banner mine.

Jan 1, 1957

By Jr. Driscoll

The thermoelectric properties of yttrium monoarsenide, yttrium monoanti-monide) and ternary materials from the Y-As-Se and Y-Sb-Te systems were investigated by the Bureau of Mines from room temperature to 1,000° C. The maximum calculated figure of merit for yttrium monoarsenide and yttrium monoantimonide was 2 x 10-5 ° C-1. YAs and YSb were semimetallic conductors with low Seebeck coefficients and electrical resistivities. The values of the Seebeck coefficient and electrical resistivity of the Y-As-Se and Y-Sb-Te materials were between those of the yttrium selenides and tellurides and of YAs and YSb, respectively. The maximum power factor calculated for the Y-As-Se materials was 2 X 10-5 watt/cm ° C2 which yielded an estimated figure of merit of 6 X 10-4 0 C-1. Most of the Y-As-Se compounds had high Seebeck coefficients and moderately low electrical resistivities. The Y-Sb-Te materials were degenerate semiconductors with power factors of 6 X 10-8 watt/cm ° C2.

Jan 1, 1967

By Martin A. Elliott

"INTRODUCTION During the recent war the Bureau of Mines was requested to obtain in¬formation on the temperature at which ammonium nitrate mixed with certa: contaminants would react rapidly. This information was desired in connection with an investigation of an explosion that had occurred during the evaporation, by air agitation, of volutions containing ammonium nitrate in which compressor oil that might have passed the filters was suspected of being a contaminant.During the course of this work it was found that mixtures of ammonium nitrate and zinc reacted rapidly at comparatively low temperatures: and since zinc could not positively be eliminated as a contaminant in the explosion in question, a series of tests was carried out, not only with mixtures of ammonium nitrate and compressor oil but also ammonium nitrate and zinc with and without oil. A few experiments were made with metals other than zinc.The investigation was not as extensive as might have been desired, owing to limitations -in time. The results are presented at this time in view of their current interest in connection with the Texas City disaster, in which a large quantity of ammonium nitrate detonated in the holds of two ships."

Mar 1, 1948

By John W. Taber

"INTRODUCTION AND SUMMARYDiscovery of these unusual fluorite deposits was brought to the attention of the Bureau of Mines late in 1951, shortly after the first locations were made. A brief investigation of the deposits by the Bureau revealed seven principal outcrops of fluorite in two areas. The smallest outcrop continuously exposes massive fluorite over an area 25 by 55 feet; the largest outcrop is a similar exposure 180 by 240 feet. The deposits, appear to be sharp-walled, low-angle, tabular ore bodies in granite and are at least 10 feet thick.The Bureau investigation of the deposits included bulldozer strip-trenching, drilling and blasting rock cuts, and channel sampling across three of the largest outcrops. This sampling indicated an average grade of 97.2 percent CaFp and 1.44 percent SiO2.Preliminary metallurgical tests on the ore indicate that it can be concentrated to acid-grade specifications by simple gravity methods. One laboratory test recovered 78.4 percent of the fluorite in a product containing 98.7 percent CaF2, 0.25 percent SiO2, and 0.10 percent Fe2O3."

Oct 1, 1952

By Webster S. Anderson

Bureau of Mines planer mining tests on the phosphate bed of the Douglas mine, near Drummond, Mont., indicated that a competent bed with a Mohs' scale hardness of 3 to 4 cannot be mined economically with the planer. Although planer mining was feasible where the bed was fractured enough for a 4-inch depth of cut to be consistently maintained, the depth of cut in the competent beds at the Douglas mine did not exceed 0.5 inch. Average production rates were 0.15 ton per minute and 9 tons per man-shift.

Jan 1, 1966

By A. B. Hooker, L. C. IlsLey

"Field inspections and data relative to the use of rubber-sheathed trailing cables in mines show that much cable is ruined or its probable life shortened by being overheated in service.The length of cable required to make connection from a source of supply to a machine at the face workings may be 100 to 500 feet. As a rule, the cable is carried on a reel and unreeled as required; and thus in most cases soma of the cable is not removed from the reel. The overheating generally occurs in that part of the cable which is left on the reel.Factors that determine the heating of trailing cables are:1. The size of the conductors in the cable.2. The maximum energy to be supplied through the cable, based upon the horsepower of the motor and the degree to which the motor is loaded.3. The voltage of the supply and the variation of the voltage at the receiving end.4. The time length of current flow and whether continuous or intermittent.5. The kind of current (direct or alternating).6. The amount of ca· le left or the reel.7. The type of cable used.8. The kind of reel used.In connecti0n with an investigation of the general performance of rubber-sheathed trailing callas, the Bureau of Mines has made a limited study of some of these factors, including the following points:"

Jul 1, 1931

By O. Q. Leone

Composite diaphragms were used in the investigation of electrowinning Ti from TiC14 in a fused LiCl-KCI-TiC'2 electrolyte. Composite diaphragms tested were of two general classes--those consisting of two or more solid materials, and those which contained, in addition, a loose material. An electrowinning cell using a flat diaphragm is described. The maximum current density for these diaphragms was 300 amp per ft2. Lower currents permitted longer operation times. The composite diaphragms gave electrode efficiencies that averaged approximately 60 percent, and the electrowon titanium was of good quality--some Brinell hardnesses were as low as 68.

Jan 1, 1972

By Joseph M. Pugliese

The U.S. Bureau of Mines has produced a generic in situ copper mine design manual, which contains a computerized cost model for in situ copper oxide mining. The model specifies (1) site-specific parameters, which must be quantified for mine design, (2) a method for minesite design based on those parameters, and (3) a procedure for assessing economic viability for the mine design. The menu-driven computer program performs calculations for developing commercial mine design specifications, as well as capital and operating costs. The default values are based on 1986 dollars, and indices for updating costs are included. The program also provides discounted-cash-flow rate of return (DCFROR) and allows for sensitivity analyses for an in situ mining operation at any specific undisturbed copper oxide deposit. This report is to be used with the 1990 version of the computer program, which has been made user friendly. It describes the flies, tutorial, input phase, help function, and monitor display of all calculated values and of the DCFROR table. The monitor-displayed discounted initial value of investment and annual operating costs are defined. The dual rate-of-return situation and sensitivity analyses are also briefly discussed. Information is provided on obtaining the computer program on diskette.

Jan 1, 1991

By F. G. Scott

This document is a proposed program plan for mining environmental research to be conducted by the U.S. Bureau of Mines in support of industrial oil shale mining and processing. This program plan is one of three research alternatives being considered by the Bureau, each based on a different level of anticipated funding. This report documents the high funding level program plan.

Jan 1, 1980

By Frank C. Andreuzzi

The Federal Bureau of Mines conducted a demonstration project to reclaim 125 acres of abandoned strip-mined land in Lackawanna County, Pa., for public recreational, historical, and educational use as a park. The Bureau was involved in the development of the general site plan, and engineered and supervised the basic land rehabilitation. The park's Facilities include outdoor recreational activities, picnic grounds, children's play areas, primitive overnight camping, and winter sports. A major attraction is the Anthracite Museum constructed by the Pennsylvania Historical and Museum Commission The project may serve as a prototype for reclaiming existing and future surface-mined lands.

Jan 1, 1976

By Lulie H. Crump

U.S. supply and demand data for dry natural gas by source, form, and major consuming sectors--within and between States and defined regions--were tabulated for the years 1960 and 1965. State-by-State quantitative data are provided for the natural gas industry that can be arranged into regional groupings and used to determine regional flow patterns. The tables show the derivation of the total supply of gas available for consumption from total marketed production. The tables also report the distribution of the supply among the major consuming sectors (household and commercial, industrial, transportation, and electricity generation, utilities). The summarized data show an increase in the absolute demand for natural gas in all regions for the period 1960-65, although the relative posit ions of the various subregions, with respect to national consumption, remained about the same. To enable comparison of data on dry natural gas with data on other energy sources, quantities in terms of million cubic feet were converted to British thermal unit (Btu) equivalents.

Jan 1, 1969

By Russell E. Griffin

Dielectric constants and dissipation factors were measured for six rocks over the 20-to 100-megahertz frequency range by means of the susceptance-variation method. Results for both dry and moist specimens are presented and compared with data reported by others. Loss factors calculated from the data presented are important to the Bureau's study of rock fragmentation by means of dielectric heating.

Jan 1, 1967

By T. M. Barczak

This report describes Bureau of Mines research to develop methods to evaluate loading on longwall roof supports to permit better design and more efficient utilization of these structures in compliance with the geological conditions in which they are employed. The resultant vertical and horizontal force acting on the canopy of a shield can be determined, either from a statically determinate solution assuming rigid-body mechanics and elimination of certain unknowns, or from an elastic solu-tion by analysis of the load-displacement relationship of the shield structure. A two-dimensional rigid-body model is presented that determines resultant shield forces by measurement of leg, canopy capsule, and lemniscate link forces. An elastic solution is presented, in the form of an elastic stiffness model with two degrees of freedom, which describes the load-displacement relationship from the stiffness of the shield structure as determined in the Bureau's Mine Roof Simulator (MRS). The ability of both models to determine resultant forces acting on the shield canopy are evaluated from full-scale tests in the MRS. More advanced numerical models are also discussed as part of the Bureau's continuing effort in the evaluation of roof support structures.

Jan 1, 1987

By W. P. Yant

Canister-type gas masks have become an essential part of the equipment of many industries not only for use in emergencies, but also in performing normal operations of industrial processes and procedures, particularly where ventilation is not practically or economically feasible. They are also used widely for enhancing safety of operations which previous to the development of gas masks had been performed in harmful atmospheres. Since the inception of industrial gas masks the Bureau of Mines has been actively engaged in endeavoring to increase the efficiency and safety of these devices and this bureau has become a source of advice to manufacturers in producing devices of good quality and to industry in the proper selection and use of these devices. In order to give first-hand information and keep current with the demands and needs of industry it is necessary to perform investigations from time to time. This report deals with tests of certain types of commercial gas-mask canisters for protection against mercury vapor.

Jan 1, 1932

By G. W. Birge

The Bureau of Mines investigated the effect of temperature on the mechanical strength of cokes of the type normally used in blast furnace operations. Eight samples of industrially produced cokes were subjected to ASTM tumbler tests at temperatures as high as 1,100° C (2,012° F); these temperatures had no significant effect on tumbler results for cokes with stability indexes of 40.6 to 59.9. Two foundry cokes which were tested at only one elevated temperature (900° C) decreased slightly in tumbler stability. Iron are pellets made from a variety of ores and by various industrial methods were not significantly affected by temperature when tested in an oxidizing atmosphere at 1,000° C (1,832° F) by the tentative standard ASTM method.

Jan 1, 1966

By D. Harrington

During the 5-year period 1906-10 inclusive, 84 major disasters (a major disaster being one in which 5 or more lives are lost) occurred in the coal mines of the United States, or an average of 17 per year, and the total number of fatalities from coal-mine gas and dust explosions (major plus minor) for the 5 years aggregated 2,338 or 477.6 per year. The monotonous continuance of coal-mine disasters month by month aroused the people of the United States to such an extent that it was felt necessary for the Federal Government to try to do something looking to the avoidance of the admittedly excessive loss of life in our coal mines, and this was one of the deciding factors in the establishment of the United States Bureau of Mires in 1910. That results have been obtained in this particular cause of coal-mine accidents may be seen from the fact that for the year 1933 but one major explosion disaster occurred in the coal mines of then united States and the total number killed in that disaster was 7. Unquestionably the coal-mining industry through use of oaf or mining practices and aided by the various kinds of work of the Bureau of Mines looking to the prevention of mine fires and explosions is in large part responsible for this very creditable change. If the gas and dust explosion fatality rate of 1.059 per million tons of coal produced during the period 1906-10 inclusive had continued to the first of January 1934, instead of the 6,373 deaths which actually occurred due to gas and dust explosions, there would have been 13,480. Hence, during the 23 years existence of the Bureau of Mines there has apparently been a saving of about 7,102 probable deaths, or an average of more than 300 per year, from gas and dust explosions as against the number which would have occurred had the 1.059 gas and dust explosion fatality rate for the period 1906-10 continued. Thirty-nine persons were killed in all kinds of explosions (both major and minor) in the coal mines of the United States in 1933; if the 1.059 gas and dust fatality rate of the 1900-10 period had been in effect in 1933, about 400 persons world have been killed. Unquestionably, the various teachings of the U.S. Bureau of Mines looking to the avoidance of explosions and fires in mines have had a vital influence in reducing the number of explosions and fires and also in decreasing their destruction in case they occur.

Jan 1, 1934

By Irving Hartmann

Modern mechanized mining with high-speed machines, multiple-entry systems, multiple blasting, high-velocity air currents, and rapid haulage has brought many economic benefits and has on the whole enhanced safety in the coal-mining industry. It has, however, also introduced some added hazards, the control of which requires concerted effort and ingenuity. Mechanized mining has greatly increased the production and dissemination of fine coal seam or in mine entries. Use of high-speed machines has increased the probability of formation of incendive sparks, which are produced by frictional contact between moving metals and certain mineral substances in the coal seam or in the adjoining rock strata. In gassy seams rapid extraction of coal has increased the rate of gas evolution. These facts have made more urgent the need of preventing the ignition of coal dust and the development of widespread mine explosions. The ignition hazard can be controlled best by eliminating all potential igniting sources and by careful attention to ventilation designed to prevent accumulation of gas capable of triggering a coal-dust explosion. Frictional spark ignition by mining machines and suggested safeguards are discussed in a recent publication. Extensive research and long experience have shown conclusively that the propagation of coal-dust flames can be arrested and the development of widespread explosions prevented by properly applied, generalized rock dusting.

Jan 1, 1956

By C. L. Brown

Among the more recent developments for breaking coal in mines is the Airdox system, in which high-pressure compressed air is conducted to the points of application by means of heavy-duty steel and copper tubing. Stray electric currents can be detected on y of the compressed-air lines, and evidence of such currents is rev led, by arcs and sparks when contact is made between the tubing and mine track or other equipment forming a current path with the track. Explosive gas is liberated in many coal mines; therefore, from the standpoint of safety, it is desirable to eliminate all possible sources of gas ignition, including stray electric currents. The purpose of this report is to reveal the source, magnitude, and possible methods of controlling stray currents in compressed-air lines that are used in connection with Airdox systems. Stray electric currents have been studied in most coal-mining localities in the United. States where Airdox equipment is used. The information given in this report is based on the find of these studies.

Jan 1, 1949