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By Charles F. Weber

Premature blasts of charges of explosives have caused many deaths in anthracite mines, and the causes of many of the blasts were not determined satisfactorily. Investigators often found fairly high potential differences between such metallic objects as rails, pipes, conveyor lines, or sheet-iron chutes in the working place where an accident had occurred. At one mine where a premature blast occurred in a rock tunnel, one workman was killed and two others were injured, and several days later a potential difference large enough to explode an electric squib was detected between the compressed-air pipe and the track rail; the voltage fluctuated and appeared to change with the movement of a locomotive. At another mine, a. workman was killed when a primed cartridge that he was about to load in a blast hole exploded in his hand. During the investigation, a potential difference was found between the conveyor line and the sheet-iron chute. During a 5-year Period, 61 fatalities and 771 nonfatal injuries were caused by explosives accidents in anthracite mines, and one of the chief causes of these accidents was premature blasts.

Jan 1, 1950

By Joseph Cervik

Gas occurs in coalbeds in an adsorbed and a free gas state, Adsorbed gas is stored in the micropore structure and its transport is governed by Fick's law. The free gas occurs in the. fracture system and flows according to Darcy's law. These two modes of mass transport are interdependent. Production decline curves of coal-gas wells are of the constant percentage decline type and, thus, show no indications of flow characteristics peculiar to coal-gas reservoirs. The effectiveness of surface boreholes as a degasification scheme depends upon both good fracture permeability and a high fracture density. Conventional methods of reservoir engineering analysis are not applicable to coalbeds.

Jan 1, 1969

By F. D. DeVaney

An examination of the physical properties of manganese ores is being made at the Mississippi. Valley Station of the United States Bureau of Mines in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Missouri. The object of the study is to find out how much these ores can be beneficiated by such processes as jigging, tabling, magnetic separation, and flotation. Some. of the results were given in an earlier report.4 Eighty samples obtained from various prospects and mines throughout the country have been examined; this is a very small part of those that should be examined before the work can be a definite factor in-the appraisal of manganese ores or the guide in beneficiation which the operators seek. The ore deposits are not expected to reach to great depths vertically, after the manner of copper and gold, but in lateral distribution their greater extent is notable. This applies particularly to the residual and replacement deposits of manganese.

Jan 1, 1929

By H. S. Hardman, G. T. Adams, Will H. Goghill

"Usually a newly developed machine leaves the factory ""on a wing and a prayer."" The manufacturer hopes that the operator will hasten to report defects. In turn, when the suggestions arrive the manufacturer makes the required changes and maintains close collaboration with the operator. Thus the history of our machines of today is written.Laboratory concentration tables are exceptions to growth by experiment and collaboration. Their operation never enters directly into the cost sheet; they are seldom used for longer periods than 10 minutes; and the experimenter, while hurrying to another job, accepts the table, good or bad, for a quick test on his ore. Thus we go back about 50 years when we use the preset in factory-built laboratory table.The Southern Experiment Station, Bureau of Mines, in cooperation with the University of Alabama, recognized the existence of a tabling problem net usually considered. That is, instead of using the table to test the ore, the ore was used to test the table. In this critical examination of laboratory table six defects were encountered (and remedied). They are:"

Oct 1, 1945

By A. Z. Dimitroff

An improvised rock- dust disseminator, consisting of a 10-gallon galvanized metal milk can that dispenses rock dust in return air currents by the injection of compressed air has reduced the float dust explosion hazards at the Koehler coal mine, Koehler, N. Mex.

Jan 1, 1965

By Spencer P. Hwell, Charles E. Munroe

"Among the surplus explosives left on band with the War Department was a quantity of that styled Trojan Grenade Powder, which was especially designed during the war for use as a bursting charge in grenades and for which naturally there would be very little military use in time of peace. With a view to its disposal through use in civil projects a quantity was sent to the Bureau of Minas explosives experiment station, where analysis showed that its characteristic explosive ingredient was nitrostarcn and that the powder bad the following composition:Trojan Grenade Powder appears as a dark gray granular substance, part of which is slightly pulverulent. The granules fairly hard. The explosive is not at all dusty, and has the consistency of granulated sugar.Nitrostarch is a substance produced by treating starch with nitric and sulphuric acids and in appearance it looks very little different from powdered starch. It resembles nitrocellulose and nitroglycerin in its constitution and explosive properties and has been longer known than either, it having been prepared by Braconnet in 1833. Nitrostarch explosives have in recent years been developed for industrial use in this country, they having been used to an extent in blasting in the Canal Zone, yet as this grenade powder was a special composition it seemed desirable that a complete series of tests should be run upon it. This was done, and the results are reported in the following table in comparison with those previously obtained in testing ammonia dynamite."

Jun 1, 1920

By Andrew B. Cecala

The Bureau of Mines conducted laboratory and in-mine tests on the Racal airstream helmet (Model #AR21) to evaluate its protection efficiency. Laboratory tests indicated that as ambient air velocity increased, the protection offered by the helmet decreased. In tests conducted at several coal mine long-wall sections with face velocities under 400 fpm, the helmet was 84 pct effective at reducing respirable dust in the miner's breathing zone. However, at a high-velocity section, 1,200 fpm, the efficiency of the helmet was significantly reduced, confirming our laboratory results.

Jan 1, 1981

By Wilson Blake

The Bureau of Mines used a mathematical model based on the finite element method of stress analysis to calculate stresses and displacements surrounding an open pit mine in a gravity-loaded rock mass. Comparison of the finite element solution for a semicircular notch in a gravity-loaded plate with the theoretical solution for a semicircular notch in a plate under uniform compression parallel to the free boundary demonstrates the inapplicability of the latter method to openings at the free surface of a gravity-loaded medium. High stress concentrations are formed at irregularities along the boundary of an open pit in a gravity-loaded continuous competent rock; however, for this type of rock the magnitudes of the stresses are too low to be considered a major factor in open pit slope stability. High stress magnitudes will occur if, in addition to the gravity stress field, a large horizontal stress field exists.

Jan 1, 1967

By George McCaa, H. C. Howarth

"During recovery operations following a recent coal-mine explosion, 12 small fires were encountered near the break line of pillar extraction in a large panel. All of the fires except one were quickly extinguished by the rescue and recovery parties. This fire had found its way into a large quantity of loose material at a corner of the cut-through between two rooms, about 100 to 150 feet from the break line of an extensive goaf; had it been necessary to seal the fire, the inclusion of this break line not only would have made the work difficult but would have made the section hazardous as it probably would have given off gas. The fire covered a floor space of about 100 square feet and when discovered was burning briskly, with the flame extending to the roof at a height of 3 or 4 feet; it was the cause of much apprehension on the part of those in charge of the recovery operations and resulted in delaying the work considerablyThe object of this article is to describe in detail the method by which the fire was brought under control and finally extinguished, so that other persons encountering similar conditions may have the benefit of the experience.When the fire was discovered a request for rock-dust, fire extinguishers, and other fire fighting equipment was telephoned to headquarters on the surface. The promptness with which fire fighting equipment and material was provided was a big factor in finally extinguishing the fire and illustrates one of the many advantages of a good organization for fire-fighting. Material was transported in mine cars to a point on the main hauling road about 1,200 feet from the fire. It was then carried to the scene of activity by workmen. The first material to be delivered at the fire was a number of fire extinguishers of various types. The contents of 30 to 35 of these were discharged on the fire and with the aid of a small quantity of rock-dust were sufficient to smother the flame temporarily. It was the opinion of several persons who were present when the fire extinguishers were used that the acid-soda type of extinguisher gave more effective results than the two or three other types used.When the contents of all of the fire extinguishers had been exhausted the fire was temporarily smothered, but as there appeared to be danger that the flame would burst forth again, means for completely extinguishing the fire were"

Feb 1, 1929

By D. A. Wilson

A process was developed on a laboratory scale in which a solid waste byproduct from refining of secondary lead was converted into three valuable products. Roasted lead blast furnace matte was leached with water to recover copper. This was followed by brine leaching to recover lead. Residues were finally smelted to yield pig iron. Copper was precipitated as cement copper and the lead product obtained was a mixture of pure 3PbO.PbC12.xH20 and Pb(OH)C1. Copper recovery was 89 percent and lead recovery was 96 percent.

Jan 1, 1967

By Arnulf P. Hagen

This project was designed to explore the suitability of using fluorinated inorganic materials as solvents for the in situ mining of thin seamed, heavily overburdened coal; to build a data base for the selection of an inorganic solvent for use for coal cleaning; to determine if fluorinated solvents will reduce the organic and inorganic sulfur contents of the coal, as well as to lower the ash content. The coal samples have been combined with pure solvent, as well as with aqueous solutions at atmospheric pressure and at increased pressure. The increased pressure experiments are important since they duplicate the conditions anticipated for an in situ cleaning and mining operation. Trifluoroacetic, difluorphosphoric (phosphorodifluoroidic), and trifluoromethanesulfonic acids have been found to be effective for the cleaning of high sulfur, high ash coal at 300°C and at atmospheric pressure. At pressures up to 20,000 psi the effectiveness of these reagents is not decreased.

Jan 1, 1983

By Homer J. Ballinger

A multiple drill carriage or "jumbo," which is believed to be unique in both design and performance, was constructed and has been in use for the past year at the Bureau of Mines experimental oil-shale mine near Rifle, Colo. This jumbo mounts four long feed percussion drills and is so designed that two men can operate all four drills. Before the jumbo was placed in operation, a minimum of eight man-shifts was required to drill 72 fifteen-foot holes in headings 60 feet wide and 27 feet high. The sane round is now drilled by two men in about 6 hours. Over 500 feet of drilling per man shift is easily and consistently accomplished. Use of the jumbo has resulted in a 75 percent reduction in drilling labor and a substantially lower drilling cost.

Jan 1, 1950

By Oliver Bowles

It is noteworthy that 80 to 95 per cent of the gross production of all slate quarries in the United States is discarded as waste . In view of the loss involved in handling so much waste , and the consequent added cost of the finished product , the Bureau of Mines has undertaken a study of the slate industry for the purpose of devising the best means of reducing the proportion of waste , and of utilizing the unavoidable waste . The utilization of waste has received special attention , and the cooperation of many prospective purchasers of waste slate has been enlisted in testing its adaptability for various uses .

Mar 1, 1921

By D. G. RUNNER

Information Circular 6148R, " Selected Bibliography of Minerals and Their Identification ," was issued in June 1929 , revised in July 1937, and again in October 1938. The popularity of this circular , combined with the desire to make it more comprehensive , has occasioned the preparation of this compilation of references . Where possible , date of publication , publisher, current price , and number of pages are given, although prices are subject to change at intervals . The references are grouped under the following headings : minerals , gems , rocks , geology, geomorphology, engineering geology , prospecting, mining . engineering, microscopy, technical dictionaries , and miscellaneous . For ready reference, the authors ' names are arranged alphabetically under each grouping . This list is not comprehensive, but contains only those references in most common use and which are generally available in public college libraries .

Sep 1, 1949

By Charles Zahn

Gas chromatography is a method of separating mixtures of gases and volatile materials by entraining their vapors in a gas stream, which passes over an appropriate stationary phase. Two techniques are in common use: Gas-Liquid Chromatography, in which the stationary phase is a liquid supported on an inert solid, and Gas-Solid Chromatography, where the stationary phase is a solid adsorbent, such as charcoal or alumina. In both techniques components emerge from the column after a characteristic residence time. Gas chromatography is applicable as a qualitative or quantitative tool in a wide variety of problems in chemical research and processing. It may also be employed for purification and separation. A running bibliography on gas chromatography has been maintained at the Bureau of Mines synthetic liquid fuels laboratories, Bruceton, Pa., for several years for the benefit of research workers, who use chromatography as an analytical tool. Since the number of references grew and interest in the technique became more wide-spread, the Bureau is publishing this list rather than maintain it as a purely internal source.

Jan 1, 1958

By Donald P. Schlick

This report presents a representative cross section of methods success- fully used to ventilate continuous-miner places as well as various factors that should be considered when selecting auxiliary ventilating equipment. Line brattice can direct fresh air to the active face reasonably well, provided that adequate area for installation is available. Continuous mining equipment, however, often restricts clearances to such an extent that proper installation of line brattice is impossible. Consequently, in many instances face ventilation is inadequate; therefore, many methods of auxiliary ventilation for continuous-mining equipment have been developed and have been discussed in this study.

Jan 1, 1963

Graduate education is an integral part of the Center's research program. The scope of. work and the duration of each research project is calculated, in part, by taking into consideration the needs of the graduate research program and graduate training. Full development of student involvement, as demonstrated by the research practicum which is offered to qualified senior undergraduates at Penn State University and is designed to acquaint them with research methods and techniques and inform them of the opportunities available in this field. and the fulfillment of graduate program requirements are of the utmost concern. The Pennsylvania State University and West Virginia University have accredited mining engineering curricula and rank among the schools with the largest enrollment in this area in the nation. The number of undergraduate students enrolled in mining engineering at Penn State and West Virginia University account for nearly 20%, of the total undergraduate enrollment in this discipline in schools across the United States. The Pennsylvania State University. West Virginia University, Massachusetts Institute of Technology, University of Minnesota, and Michigan Technological University, have granted a total of thirty-five (35) doctorate and masters degrees which can be directly attributed to research conducted in the Center.' Of these graduates, fifteen(15) have found employment in the mineral sector of the economy, i.e., in private industry, with government agencies, and at various universities, worldwide. In addition, a number of those graduating with masters degrees are currently pursuing a doctorate degree.

Aug 31, 1989

By John C. Hartley

Three systems that monitor ventilating fans are described. These electronic monitoring systems automatically perform most of the operations required to conform with the provisions of the Federal Mine Safety Code in the event of fan failure or slowdown.

Jan 1, 1964

By G. J. Conroy

Cable whip occurring during normal movement of a shuttle car can result in a personnel hazard and excessive tensions in the cable. This Bureau of Mines report discusses preferred payout and reel-in torque settings to reduce cable whip. A simplified adjustment procedure is described.

Jan 1, 1974

By N. E. Hanna

The effect of small percentages of sodium chloride on the incendivity of permissible explosives was studied by the Bruceton up-and-down technique in gallery tests. Both the reduction in incendivity achieved by addition of sodium chloride and application of the test method to explosives evaluation are discussed. It is demonstrated that the up-and-down technique in gallery testing is suitable for distinguishing differences in incendivity between different explosive compositions and between lots of the same composition. The study also shows that addition of relatively small quantities of sodium chloride tends to reduce the incendivity of explosives to firedamp, but addition of sodium chloride cannot insure reduced incendivity. Any improvement attributable to the salt can be counteracted by undefined variations in the explosive. The need for experimental investigations of a number of factors that may affect the safety of permissible explosives is emphasized. ACKNOWLEDGMENTS Grateful acknowledgment is made of the assistance of Roy L. Grant in analyzing for normality of distribution of the data obtained by the up-and-down methods and to Harold E. Tubbs for numerous calculations.

Jan 1, 1959