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By Zabetakis M. G.

This Bureau of Mines report presents a brief summary of the explosion trends in United States coal mines for the past 160 years. These trends show that in spite of the overall improvements in mine safety, the number of fatalities from ignitions of methane has actually increased in recent years. Suggestions are made of procedures that can be utilized to reverse this trend.

Jan 1, 1973

By R. R. Brown

The solubility and the activity of aluminum chloride hexahydrate, A1C13?6H2O, in aqueous solutions were determined as a part of the Bureau of Mines, U.S. Department of the Interior, research to improve mineral processing technology for recovering alumina from low-grade domestic resources. The solubility of A1C13 in pure water was found to be 31.09 and 31.77 wt-pct at 25° and 85° C, respectively, and decreased drastically to 10 and 0.1 wt-pct when the respective amounts of 20.3 and 37 wt-pct hydrochloric acid (HCI) were added in solution. The equilibrium constant for the solubility of hexahydrate, activities, and activity coefficients of A1C13 and H2O were calculated and compared with the results from the available methods of estimation. The results were shown to be useful in leaching nonbauxitic ores for extraction of alumina by changing the solubilities of component salts upon addition of HC1. Simultaneous solubilities of A1C13, FeC13, KC1, and NaC1 in solutions of HC1-H2O were also determined and their effects on the purity of A1C13?6H20 crystallized from mixed salt solutions are briefly discussed.

Jan 1, 1979

By Ben E. Lindsly

The study of "bottom-hole samples follows in natural sequence the study of samples obtained under high pressures at the well heads of flowing wells. The principal object of this phase of gas-solubility research, started actively in January, 1930, was to gain a more accurate knowledge of the physical and chemical characteristics of the oil-gas mixtures that exist in natural reservoirs.. In possession of actual data regarding the condition of the oil; the quantity of gas liberated from solution upon dimunition of pressure; and the relative volumetric proportions of gas to oil at various pressures throughout the flow string in a well, it should be possible to predict, with a fair degree of accuracy, That physical changes these mixtures would undergo throughout the life of a pool. Such information not only is important in designing flow strings in flowing Tells but is important also in solving problems relating to pumping efficiency and the power required for pumping. Although certain fundamental data were obtained in the study of samples taken at the well head, "bottom-hole" samples are more representative of subsurface mixtures of oil and gas because they are obtained at reservoir temperatures, and before the oil has had the opportunity of intermingling with extraneous gas; that is, gas which either was not in solution originally, or which was liberated from solution at higher pressure, and later became mixed with the original undissolved gas.

Jan 1, 1933

By J. P. Capp

This experiment, one of a series on underground gasification of coal, was an investigation by the Federal Bureau of Mines of hydraulic fracturing as a means of increasing the air acceptance of a coalbed to permit introducing combustion air and removing product gases. Specific objectives of the investigation included: (1) Fracturing a coalbed; (2) determining the distance the coal was physically affected; (3) ascertaining the effect of the fracture on air acceptance of the coalbed; and (4) gasifying the coal. The coal was fractured with a fluid consisting of 15,000 lb. of sand mixed with 10,000 gal. of fuel oil and 5,000 gal. of kerosine, injected at pressures up to 900 p.s.i.g. and rates up to 425 g.p.m. The oil served as the fracturing medium, and the sand as a propping agent to hold the fracture open. From the fracture point, (the place in the bed where the fluid was injected), the fracture extended 200 ft. or more along the face cleats, somewhat less along the butt. cleats, and was confined to the coalbed. At the fracture point, the bed accepted about 500 std. c.f.m. of air, which was an etghtyfold increase. Fracture effects were extensive, as airflow was noted from old mine workings and outcrops 600 to 800 ft. from the fracture point. It is probable the actual fracture was much less than 600 ft. and that normal coalbed permeability beyond the fracture limits was responsible for this flow. This indicated that effects of the fracture extended beyond the area of coal physically affected. Although no attempt was made to gasify coal more than 200 ft. away, these effects plus the natural permeability of the bed likely would permit combustion beyond the outer limit of the fracture. As these experiments continued for more than 2 years, and greater air acceptance due to the fracture was observed at the beginning of each test, it is apparent that the effects of the fracturing persist for a considerable time.

Jan 1, 1960

By Clarence O. Babcock

In this report, the Bureau of Mines presents a method for reducing the complexity of designing room-and-pillar mining systems by treating them as anisotropic soft inclusions in the surrounding ore or host rock. Theoretical models were derived for the calculation of the effective Young's moduli for these systems. The predicted behavior of the plate-type elements used in these models agreed well with test results from 21 plates each with 49 holes spaced on a 7 X 7 Cartesian grid. The plates behaved as anisotropic solids, the effective Young's moduli of which could be predicted from the scaled hole size and spacing. Actual hole shape was insignificant. The effective Young's moduli for simple mining systems are calculated in sample problems. This approach should provide information about field stress in the mining region and the stress distribution in the surrounding ore or host rock when the actual mining configuration is replaced by an anisotropic inclusion in a finite element analysis. The field stress within the inclusion can then be applied to the actual opening shape to determine the stress distribution within the mining region.

Jan 1, 1970

By R. M. Santmyers

"Quartz and silica not only occur in diversified forms in nature but find a multiplicity of uses in industry. The purpose of the present paper is to assemble brief summaries of the many widely differing industries engaged in the production and preparation of these minerals in their principal commercial forms. Due to the scope of the subject it was though advisable to divide the paper into three parts. Part I deals with the subject of quartz and silica in general. It also contains a flow sheet of silica from deposit to consumer (fig. 1). Part II covers the uses and other economic factors of quartz, quartzite, and sandstone, the varieties of silica found in consolidated form. Part III deals with sand and miscellaneous silicas such as tripoli and diatomite. A chart showing the major ramifications of these industries is presented herewith as an introduction to the more detailed discussion that follows.For a more intensive study of many branches of the quartz and silica industries the reader is referred especially to Bulletin 263 of the United States Bureau of Mines, Technology and Uses of Silica and Sand by W. M. Weigel. For annual statistics relative to silica and its products in the United States he is referred to the annual chapters of Mineral Resources of the United States, entitled ""Silica,"" ""Sand and Gravel,"" and ""Abrasives."" With respect to diatomite reference is made to Diatomite, by Paul Hatmaker, recently issued by the U. S. Bureau of Mines as Information Circular 6391. In preparing this paper the author has drawn freely from these sources as well as Marketing of Metals and Minerals, by J. E. Spurr and F. E. Wormser; Non-Metallic Minerals, Occurrence, Preparation and Utilization, by Raymond B. Ladoo; and Abrasives - Part I, Siliceous Abrasives, by V. L. Eardley-Wilmot, Report 573, Mines Brand, Department of Mines, Ottawa, 1927.Acknowledgment is also made to the Foote Mineral Co., which has published in Foote-Prints (vol. 2 of 1929 and vol. 1 of 1930), comprehensive reviews of the uses of crystal quartz in the optical industry and as piezo¬electric crystals.The various forms of silica have attracted attention from the earliest times, and the water-clear crystallized variety was known to the Greeks as""krystallos"" (clear ice), being supposed by them to have been formed from water by the intense cold of the Alps; hence the name ""crystal"" or more commonly ""rock crystal,"" applied to this variety. The name quartz is an old German word of uncertain origin used by G. Agricola in 1529.Silica or silica dioxide (Si02) either free or in combination with other elements constitutes 59.08 per cent of the lithosphere, and quartz alone represents fully 12 per cent` of all rocks. Next to the feldspar group quartz is the most abundant mineral in the earth's crust; and it appears in a greater number of varieties and modes of occurrence than any other mineral. Silica or quartz occurs in crystalline, cryptocrystalline, microcrystalline, and amorphous forms. The most common, however, is the crystalline form, which occurs as three minerals, quartz, tridymite, and crystobalite, and of these three tridymite and crystobalite are quite rare in nature."

Aug 1, 1931

By M. H. Stanczyk, I. L. Feld

Dewatering of typical Florida phosphate rock slime by electro - osmotic techniques was investigated to determine if a compacted , plastic solid product could be obtained with simultaneous recovery of the water for re - use . Tests with porous cathodes and rod - type anodes imbedded in dilute slime charges of up to 4 tons in weight showed that the slime could be dewatered to about 35 percent solids . The dewatered products had the consistency of modeling clay . In the large - scale tests using 2.5 - foot electrode spacings , about 21 kilowatthours of power were consumed per ton of water removed in thickening the slime from 17 to 25 percent solids , but the rate of water removal was so slow that the process was not considered commercially feasible . Other tests made with electrode spacings of from 2.5 to 8 feet showed that more rapid dewatering could be obtained but that the power required was excessive . However , for special uses such as stabilizing slime pond dikes where the cost of dewatering might not be a prime requisite , high voltages could be used to rapidly remove the water . Tests of 400 - pound slime charges using a combination of electroosmosis and vacuum filtration showed that the rate of dewatering could be expedited . The average power required to thicken a ton of slime from 15 to 35 percent solids was 5 and 50 kilowatt - hours when operating the electroosmotic filtration cell at potentials of 20 and 100 volts , respectively . calculated filtration area of about 10 square feet per ton of slime treated per day was required to thicken the slime from 15 to 35 percent solids .

Jan 1, 1964

As part of the United States Department of the Interior, Bureau of Mines Health and Safety Research Program, Walter C. McCrone Associates, Incorporated has examined 71 samples of airborne mine dusts using the techniques of x-ray diffraction, electron microprobe analysis and light microscopy. This report details the procedures which were used in this work and documents the results which were obtained.

Jan 1, 2011

By D. Harrington

The record of fatalities from mine explosions in the United States during the past 3 years has been the best in the history of the mining industry. During these 3 fiscal years, mine explosions have resulted in an average of 4I0 deaths per year, as compared with an average of 153 deaths per year for the preceding; 5 years; an average of 542 deaths per year for the 3-year period 1907-09, inclusive, just before the organization of the U. S. Bureau of Mines; and a yearly average of 265 deaths per year for the 20-year period prior to 1929. This remarkable reduction in deaths from mine explosions demonstrates clearly that mine explosions can be controlled; in fact, they can be prevented when or if the mining people of the United States see fit to take the readily available precautions necessary to bring about this desirable objective. Several large coal-producing States, which in the past have had numerous disastrous explosions, have been free from such disasters for continuous periods of as much as 6 years or even longer. The bituminous mines of Pennsylvania, the largest coal-producing State, give a good example of what can be done to prevent explosions; this State has had only one major explosion (and it resulted in 7 fatalities) during the past 6 years, and no explosion occurred in the several hundred bituminous-coal mines of the State during the past fiscal year. This is a truly remarkable record when compared with past performance in any year in the operation of coal mines in Pennsylvania.

Jan 1, 1936

By J. B. Zadra, H. J. Heinen

Electrowinning molybdenum from oxide feed materials dissolved in a variety of molten baths was investigated . A NaCl - NaF - Na₂ B₁ O -Mo0, system operating at 1,000 ° C in a cell without a protective atmosphere gave the best current efficiency , metal - to - cathode adherence , and purity of electrowon Technical - grade molybdic oxide , containing associated impurities of aluminum , iron , copper , silicon , and tungsten in combined quantities of 10 percent , was used as feed material to produce dendritic crystals of molybdenum metal containing less than 0.5 percent total base metal , carbon , and oxygen impurities . Arc - melting molybdenum electrowon from either chemically pure or commercial - grade Mo0, produced ingots that contained less than 0.1 percent total impurities and had hardness readings of 168 to 200 Vhn .

Jan 1, 1964

By A. C. Fieldner

[The Sectional Committee on Classification of Coals, functioning under the sponsorship of the American Society for Testing Materials and the rules of the American Standards Association, in its 1934 report recommended to the American Society for Testing-Materials that Specifications for Classification of Coals by Rank be adopted as tentative. These specifications, slightly modified as recommended by the Sectional Committee, in its 1935 report,6 wore approved as tentative standards by the society in 1935. The specifications rover the classification of coals according; to their degree of metamorphism, or progressive alteration, in the natural eerie s from lignite to anthracite. The basic scheme of classification is according to fired carbon and calorific value (expressed in B.t.u.) calculated to the mineral-matter-free basis. The higher-rank coals are classified according to fixed carbon on the dry basis, and the lower-rank coals according to B.t.u. on the moist basis, that is, containing its natural bed moisture but free of visible surface moisture. Agglutinating and weathering indices arc used to differentiate between certain adjacent groups.]

Jan 1, 1935

By P. L. Woolf

Seven evaluation tests with blast furnace iron bearing burden materials are described. The effects of pellet strength, fines in the burden, decreasing slag volume, pellet size, eliminating stone with superfluxed sinter, and eliminating stone by prefluxing the pellets were determined. Fluxed pellets and fluxed sinter made with the same ore fines were compared. The tests were conducted under cooperative agreements between the Bureau of Mines and North American steel companies. The objectives were to improve blast furnace practice, expand and develop understanding of the operation and theory, quantify the effects of changes, and explore the limitations of operability. This work was part of an extensive program of blast furnace research in experimental blast furnaces at Bruceton, PA conducted in the years 1958 to 1967.

Jan 1, 1984

By Tim F. Dyson

Feasibility of employing automated processing and detection techniques in the mine disaster communications problem is demonstrated. Efficient processing methods are developed. These methods have been demonstrated both in a laboratory and in a field environment. Evalua¬tion of existing computer capacity is given along with recommendations for expansion.

Jan 1, 1981

By Robert M. Busche

[Recent developments in the gasification of coal, both by the Bureau of Mines and American industry, have intensified interest in the thermodynamic and kinetic principles necessary for understanding the reaction mechanism and rates and the physical changes that take place. In the course of a Bureau of Mines study of the kinetics of coal gasification at the Synthetic Liquid Fuels Demonstration Plant, Louisiana, Mo., a bibliography of approximately two references was compiled. They are listed n this publication and refer both to American and foreign sources.]

Jan 1, 1952

By Charles L. Kimbell

This study summarizes and amalgamates much information collected, compiled, and utilized by the Bureau of Mines numerous country specialists and branch chiefs for inclusion in their country and regional reports that comprise the five other volumes of the international studies of the Minerals Yearbook. Because of the plethora of sources used in preparing these regional studies, it is impossible to cite all sources of information used in preparing this summary, but some recognition seems due. Generally speaking, the preparation of this study, and its related detailed studies on countries and areas, would be impossible without the efforts of the personnel of our counterpart agencies throughout the world. Information that they collect, compile, and then publish, either in their own volumes or in publications of central statistical agencies in their countries, are the foundations upon which this work rests. Thus, we must begin by expressing our appreciation to the multitude of persons employed by these agencies for their contributions.

Jan 1, 1992

By R. A. Isberg, D. A. Parrish, H. Kramer

This report describes the design and implementation of UHF radio and closed-circuit television systems in the Black River room and pillar limestone mine near Butler, Pendleton County, Kentucky. Prior to designing the radio system, measurements of signal attenuation on 812 and 466 mHz were made in the slope tunnel and in the straight and level crosscuts in the mine. Two distributed antenna systems fed by two sets of base stations provide approximately 75% coverage of the mine. Passive reflectors are used for extending signals into intersecting crosscuts and two-way signal boosters will be used to extend signals to the perimeter and obstructed areas of the mine. Fourteen mine vehicles were equipped with mobile radios equipped with digital identification, alarm and status encoders. Fifteen portable transceivers also were used. Six closed-circuit television cameras provide surveillance of critical transfer points of the belt conveyor system, and the loading dock at the base of the slope and an ash disposal area in the mine. Two-way radio communication and closed-circuit television have saved considerable man. hours, increased production, reduced maintenance costs and enhanced safety. Innovative developments were the use of passive reflectors and two-way signal boosters for extending signals into intersecting crosscuts, development of lightweight signal margin measuring equipment, modifications of mobile digital encoders to automatically send status information from mine vehicles such as numbers of loads of ore delivered, hot engine, etc., and the use of CATV technology for multiplexing audio, digital and video signals onto coaxial cables from the surface to the mine.

Jan 3, 1981

The 53 countries that constituted Africa in 1992 accounted for a significant portion of total world output of a number of mineral commodities. However, the continent's total output for a number of major mineral commodities declined relative to the volume produced during 1991. (See tables 1 and 2.) The most conspicuous declines in mineral production from 1991 to 1992 were for cobalt and copper (declines of 28.6 % and 23.4 %, respectively), which could be partially attributed to mining and metal processing difficulties caused by political and economic disruptions in Zaire and for uranium (12 % drop), for which much of the continental production decline was ascribed to Namibian cutbacks in response to lower world prices. The severe regional drought also adversely affected the mineral industry in a number of sub-Saharan nations.

Jan 1, 1994

By Ben E. Lindsly

The study of "bottom-hole' samples follow,-is in natural sequence the study of samples3 obtained under high pressures at the well heads of flowing wells. The principal object of this phase of gas-solubility research, started actively in January, 1530, was to gain a more accurate knowledge of the physical and chemical characteristics of the oil-gas mixtures that exist in natural reservoirs. In possession of actual data regarding the condition of the oil; the quantity of gas liberated from solution upon dimunition of pressure; and the relative volumetric proportions of gas to oil at various pressures throughout the flow string in a well, it should be possible to predict, with a fair degree of accuracy, what physical changes these mixtures would undergo throughout the life of a pool. Such information not only is important in designing flow strings in flowing wells but is important also in solving problems relating to pumping efficiency and the power required for pumping. Although certain fundamental rata Mere obtained in the stud of samples taken at the well head, "bottom-hole" samples are more representative of subsurface mixtures of oil and gas because they are obtained at reservoir temperatures, and before the oil has had the opportunity of intermingling with extraneous gas; that is, gas which either was not in solution originally, or which was liberated from solution at some higher pressure, and later became mired with the original undissolved gas.

Jan 1, 1933

By NIOSH Publication

In 2004, a total of 7,074 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA).

Sep 1, 2007

By M. Hertzberg

The Bureau of Mines measured the energy requirements for the spark ig-nition in air of Pittsburgh seam bituminous coal dust, lycopodium spores, and polyethylene powder with a 1.2-L furnace and 8-L and 20-L chambers. Thermal autoignition temperatures of the same dusts were mea-sured in the 1.2-L furnace. Electrical ignition requirements are given in terms of both effective spark gap energies, [ ] and stored circuit energies, 1/2 CE2. The measured order of electrical ignitability for the three dusts is consistent with the data of other researchers; however, the absolute values are systematically higher, probably because of higher flow and turbulence levels in the chambers used and lower electrical efficiency in the circuit used here. The temperature dependence of the lean limit of flammability for lyco-podium was measured wi th the 1.2-L sys tem, and those measurements con--firm the applicability of the modified Burgess-Wheeler law to a dust. Due to experimental complexities, the minimum ignition energies for dusts may not reflect intrinsic flammability behavior. However, some valuable information may be obtained from the relative ignition energies of various dusts at ambient and elevated temperatures. In addition, the concept of minimum electrical ignition energies for homogeneous gas mixtures is reevaluated theoretically.

Jan 1, 1985