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By M. Paczkowski

The use of inert gas systems to extinguish mine fires has been the subject of research for some time in the United States. In some European countries, it is an established practice. Tests were conducted with the CMI Inert Gas System (CMI), which is being used by the Polish mining industry. This system utilizes a modified jet aircraft engine and afterburner as a compact source of combustion products with a very low (less than one percent) oxygen content. Water injected into the combustion products stream provides evaporative cooling and forms a mist with a high cooling capacity. The CMI system was used under controlled conditions to extinguish coal pile fires at the U. S. Bureau of Mines Experimental Mine in Bruceton, Pennsylvania. The test results show that the CMI system can be used conveniently to extinguish fires quickly and to maintain an inert atmosphere in the fire zone to prevent re-ignition.

Jan 1, 1982

By Charles L. Kimbell

Following the pattern established in the 1989 edition of this study, the concept of data availability must be addressed, because there are perceptible changes from year to year, and the availability of accurately reported, precisely defined statistics and nonstatistical information provides the only sound basis for analytical studies of any type. As the countries of eastern Europe, including the numerous states that formerly comprised the U.S.S.R., undergo the transition from centrally planned economies' to market economies, there has been a perceptible increase in information availability for rather obvious reasons. Any industrial operation seeing economic assistance from government and/or private sources outside the country in which the facility is sited must provide some appraisal of its operations at the time it seeks assistance, as well as some information on previous performance to serve as tools in evaluating its potential under the proposed development scheme for which it seeks financial assistance. This situation, coupled with governmental recognition that concealment of much of the national mineral production, trade, and consumption data for purposes of national security probably never was really necessary and certainly proved unnecessary with the end of the so-called cold war, has led to the publication of increasing amounts of both statistical and nonstatistical information in the countries undergoing economic transition.

Jan 1, 1993

By G. W. Jones

"INTRODUCTION As part of its work in promoting safety, the Bureau of Mines is investigating various means of eliminating or mitigating the explosion hazards of combustible gases encountered in mining and industry. Information has been obtained and a procedure developed whereby the explosibility of many complex gaseous mixtures may be calculated in a rather simple manner without the necessity of performing laborious laboratory experiments. An earlier publication 3/ described the method of determining by calculation the limits of inflammability of gaseous mixtures, including methane, hydrogen, carbon monoxide, nitrogen, carbon dioxide, and oxygen. The information published in the above report permitted calculation of the limits of inflamnability of such gases as are liberated by mine fires, gases from explosives, automobile exhaust gases, gases present after mine explosions, blast-furnace gas, and other gases of similar type.Gases liberated in certain potash mines in the western part of the United States sometimes contain ethane, in addition to the gases named. An investigation was made to obtain data from which the limits of inflammability of such gaseous mixtures could be determined by calculation. 4/Similar data have been Published covering all types of natural gases containing wide ranges of concentration of nitrogen and carbon dioxide.5/"

Dec 1, 1944

By George S. Koch

Several methods of calculating ore grades by diamond-drill sampling in the Homestake mine, Lead, S. Dak., have been evaluated by statistical analyses of assay data. The natural distribution of gold particles, partly masked through sampling and assaying procedures, is probably lognormal. As a consequence of the gold particles being clustered rather than randomly distributed within the ore bodies, (1) more mine samples are needed to obtain a specified precision of mean grade than the number predicted by the standard-error-of-the-mean law; (2) the variance of gold values is not inversely proportional to sample volume, and, therefore, small-diameter drill core yields samples nearly as good as larger diameter core; and (3) sampling at 5-foot intervals provides nearly as good results as sampling at shorter intervals.

Jan 1, 1971

By B. W. Naugle

This report describes the carbonizing properties of coals from the principal beds in Cambria County, Pa. Samples of coals from Upper and Lower Freeport and Upper and Lower Kittanning beds having estimated minable reserves of 50-million tons or more were studied by the Bureau of Mines. Cambria County coals rank either as medium-or low-volatile bituminous. A preparation study indicated that all coals tested in this county, except one sample from the Lower Freeport bed, were responsive to cleaning and would yield a product with satisfactory chemical properties for metallurgical coal. All coals tested from Cambria County yielded strong coke; however, they expand excessively when carbonized singly, and should be used only as minor constituents in metallurgical coking blends when carbonized in slot-type ovens.

Jan 1, 1959

By W. H. Ode

Low-temperature distillation tests at 200°, 350°, and 500° C. were made on a subbituminous coal from Boulder County, Colo., and a subbituminous coal from Weld County, Colo., in connection with a survey of carbonizing properties of American coals4/ and. investigations of their chemical and physical properties.5/ The coal represented by the sample from weld County was reported to give off combustible volatile matter at unusually low temperatures when placed on a fuel bed. The yields of tar and oil and the composition of the gas from this coal, as obtained in the distillation tests, did not confirm this report. These yields and the gas composition of the Weld County coal differed but little from those obtained from the coal from Boulder County. Both coals yielded tar and gas in amounts considered to be normal for coals of their rank.

Jan 1, 1937

By Donald P. Schlick

Respirable dust provisions of the Federal Coal Mine Health and Safety Act of 1969 are designed to protect the most important resource of the coal mining industry--its workers. The Act imposes two respirable dust standards of 3.0 milligrams per cubic meter of air after June 30, 1970; and 2.0 milligrams per cubic meter of air after December 30, 1972. Under Federal regulations, each operator is required to carry out a dust sampling program established by the Secretary of the Interior and the Secretary of Health, Education, and Welfare, This program features the sampling of "high risk" face workers to establish that the exposure of each miner is below the dust standard, Mining sect ions, continuously in compliance with the regulations, may sample at less frequent intervals. In addition to requiring the mining company to take respirable dust samples, the Bureau of Mines will perform in-depth dust inspections twice a year, as well as frequent "spot inspections." The Bureau has established a semiautomatic computerized operation capable of processing over 1 million samples per year. This facility will be linked to various Bureau offices by a telecommunications system to provide automatic data printouts within hours after samples have been weighed.

Jan 1, 1970

By J. L. Holman

In conjunction with its research program on separation, recovery, and recycling of metal, mineral, and energy-based materials in urban refuse, the U.S. Bureau of Mines is developing means to reuse and recycle plastics discarded in raw municipal waste. Experimental work on plastic waste from a community collection has produced some guidelines for systematic methods of processing, including air classification, cleaning, separation, and use or disposal. Sink-float methods are a practical means of separation into types. Methods for final disposition of the plastic waste include refabrication, thermal decomposition, and incineration.

Jan 1, 1972

By Graham W. Marks

The general positions of the absorption maxima of aqueous solutions of the violet and green isomers of chromic sulfate the visible spectral region have long been known, but, to the knowledge of the writer, no comprehensive studies have ever been made. To gain further knowledge concerning these inorganic complexes and to investigate the possibilities of developing an analytical method for determining the concentrations of the violet and green isomers in a mixture, a more complete investigation was made in the spectral range from 325 to 850 millimicrons.

Jan 1, 1951

By P. B. Altringer

The Bureau of Mines conducted laboratory tests to devise a procedure for recovering a marketable grade of tungsten from the brine of Searles Lake, Calif. The brine contains only 56 parts per million of tungsten (70 parts per million of W03). Using ion exchange resins synthesized by Bureau chemists, 98 percent of the tungsten was extracted from the brine and 92 percent of the tungsten was recovered as a marketable iron-tungsten concentrate containing 44 percent tungstic oxide. Although major technical problems have largely been resolved, research is progressing to escalate testing in a process-development unit to provide more reliable data for an economic appraisal.

Jan 1, 1978

By T. M. Barczak

This U.S. Bureau of Mines report investigates shield mechanics and component stress development in a two-legged longwall shield for unsymmetric canopy and base contact configurations. Previous studies analyzed shield behavior for symmetric contact configurations. The goals of these efforts are to improve longwall support selection and design. This study provides vital information that will help develop improved procedures for performance testing of longwall supports and will benefit future research to improve support design through stress optimization and evaluation of failure mechanisms. Combinations of six canopy (three symmetric and three unsymmetric) and six base (four symmetric and two unsymmetric) contacts provided a total of 36 configurations for evaluation. Of these 36 configurations, 10 were eliminated because of fixture limitations or shield instability. Controlled vertical and horizontal displacements were applied by the Bureau's mine roof simulator to the remaining 26 configurations. Component responses were determined from pressure transducer and strain gage instrumentation in order to identify contact configurations and boundary displacements that produced maximum loading in each of the support components. This report describes these test results and provides conclusions relevant to critical contact configurations for performance testing of longwall supports.

Jan 1, 1990

By H. M. Thorne

The oil-shale deposits of the Puertollano basin in the Spanish province of Ciudad Real appear to have been give little consideration in discussions of oil-shale resources throughout the world. A small, integrated oil-shale operation has been conducted at Puertollano since about 1922 by a French company, Sociedad Mimora y Metalurgica de Penarroya, hereinafter referred to as "Penarroya", but only within recent years have the potentialities of the Spanish oil-shale deposits been recognized. Empresa Nacional "Calvo Sotelo" do Combustibles y Lubricantes, hereinafter designated as "Calvo Sotelo," which was created in 1942 by the National Industrial Institute of Spain to produce liquid fuels from oil shales, has made marked progress in the design and construction of a complete oil-shale plant at Puertollano. Penarroya is mainly a coal-mining company, and the oil-shale operations were on a small scale of approximately 220 tons a day in October 1947. It is an integrated operation comprising oil-shale mining and retorting and shale-oil refining. Motor gasoline, Diesel fuel oil, light burner fuel oil, lubricants, paraffin wax, cresols, and ammonium sulfate are manufactured.

Jan 1, 1950

By B. K. Shibler

During the investigation of the occurrence of manganese deposits in the Western United States, examining engineers of the Bureau of Mines collected 2-ton samples from five manganese properties near Golconda, Nev. Extensive laboratory tests were made to determine the amenability of these ores to standard ore-dressing methods of concentration. The Tom Major property, one of those sampled, is situated 12-1/2 miles south of Golconda, Humboldt County, Nev. The deposit is described as a bed about 5 feet thick in a thinly bedded shale and dolomite formation. The sample tested was obtained from the manganese bed, but the examining engineer reported: "The mining of an appreciable tonnage at reasonable cost would perhaps cut in half the grade represented by the sample."

Jan 1, 1951

By G. R. Hopkins

"A new record in fuel efficiency at petroleum refineries was achieved in 1935, when an average of only 615,000 B. t. u. was needed to refine a barrel of crude oil, compared with an average of 638,000 B. t. u. in 1934 and 829,000 B. t. u. In 1925. (See fig. 1.)Refiners have made almost uninterrupted progress in firing efficiency during the last decade although much of this gain was brought about by improved technique and greater use of heat exchangers and pipe stills, the determining factor was the trend in crude runs to stills. Most plants can increase their crude throughput materially with but small increase in fuel consumption. Consequently, in years in which crude runs have increased substantially, average requirements have declined; but in years in which crude runs have decreased, the average has tended upward. This conclusion is confirmed by figure 1, which shows that there has been but one minor exception to this rule in the last 10 years.Technical progress in fuel efficiency may be illustrated by comparing crude runs and total B. t, u. consumed. Between 1925 and 1935 crude runs to stills increased 31 percent, but the total quantity of heat required did not increase; in fact, it declined slightly.The trend of modern still construction is from shell stills, in which a large body of oil is heated, to tube stills, in which the heat comes into much closer contact with the oil. In 1935 the total capacity of operating pipe stills increased about 4 percent; this increase, though small, probably was related to the gain in average efficiency.The Increased use of heat exchangers and their role as fuel savers have been discussed in previous reports of this series. It is sufficient to say that refiners with insufficient exchange capacity added as much in 1935 as their budgets would permit."

Jan 1, 1937

By Steven J. Schatzel, William P. Diamond

Coalbed gas content measurements are commonly used in mine safety as well as coalbed methane resource assessment and recovery applications. Gas content determination techniques generally fall into two categories: (1) direct methods which actually measure the volume of gas released from a coal sample sealed into a desorption canister and (2) indirect methods based on empirical correlations, or laboratory derived sorption isotherm gas storage capacity data. Direct gas content determination techniques may be further. subdivided into quick-crushing and extended desorption methods. The quick-crushing methods are primarily used in mine safety applications outside the United States, but have also been used for resource recovery applications. Quick-crushing methods rely on crushing the coal sample soon after collection to release all the desorbable gas, thus significantly shortening the amount of time required for desorption measurements. However, some data useful for resource recovery applications are lost. Extended desorption techniques are most commonly used for resource assessment and recovery applications where information on desorption rates is useful for reservoir modeling, and for fundamental coalbed methane research. Extended desorption methods allow the gases in the coal sample to desorb under controlled laboratory conditions until a defined low desorption rate cutoff point is reached. The sample may then be crushed to measure the amount of gas remaining within the sample. Direct method techniques for gas content measurement are the focus of this paper.

By David E. Siskind

The Bureau of Mines has studied the fracturing and associated damage occurring in the vicinity of blastholes from five shots fired in the shale pillars in the White Pine copper mine, White Pine, Mich. Four types of explosives (AN-FO, commercial extra dynamite, ammonia gelatin dynamite, and a low-density, low-velocity permissible) were used. Cores were taken from the blast region and examined by ultrasonic and petrographic techniques. Pulse wave velocities were measured across the core diameters, and thin sections showing cracks and changes in lithology were examined in an attempt to establish zones of damage. Cores from the blast regions and areas near pillar free faces were found to have abnormally low pulse velocities. Petrographic study of the thin sections showed that the negative velocity anomalies were caused by cracks in the cores. Crushing and extensive fracturing prevented meaningful measurements on core fragments from the immediate blast vicinities. Compositional, changes and other rock nonuniformities, such as joints and preexisting fractures, tended to mask detailed damage differences among the four explosives; however, the two most energetic explosives (extra dynamite and ammonia gelatin dynamite) produced damage zones two to three times as large as the AN-FO and low-velocity permissible explosives.

Jan 1, 1973

By Lowell Stroud

A windowed-cell phase equilibrium apparatus was used to obtain equilibrium vapor- liquid data for a helium-bearing natural gas (Hogback) at temperatures from -100 to -250° F and pressures to 500 psia. Anomalous phase behavior resulting in the formation of two stable liquid phases occurred at tmperatures below -200° F and pressures above 200 psia. A review of the published literature on the occurrence of multiple-liquid phases included in the report indicates that the experimental results with Hogback gas are the first substantiated evidence of a vapor-liquid-liquid equilibria in a helium-containing natural gas.

Jan 1, 1963

By Robert A. Jankowski, Ellsworth R. Spencer, Jay F. Colinet

Longwall mining is the most productive method of under- ground coal mining in the United States (U.S.), and record levels of production have been reached in recent years. These ever-improving production levels have the potential to generate significantly higher quantities of respirable dust. Consequently, the longwall industry continues to struggle with controlling dust liberation and maintaining compliance with the federally-mandated respirable dust standard. In response, longwall operators have increased the application of primary dust controls, airflow and water flow, in an effort to improve respirable dust control and reduce worker exposure. Pittsburgh Research Center (PRC) personnel conducted dust surveys at 13 longwalls operating throughout the U.S. and collected information to: identify current operating practices on these longwalls, identify the types of dust controls in use, document the levels at which these controls are being applied, and measure the respirable dust levels present. This data was analyzed to quantify the dust levels generated by the major sources on the longwall section and to evaluate the relative effectiveness of the control technologies in use.

By E. C. Lane

During the past 15 years the Bureau of Mines has made and published several hundred analyses of typical petroleums and has developed a system of interpreting the analyses and of classifying crude oils. In describing crude petroleum frequent reference is made to the "base" of the oil, a usage the petroleum industry has found convenient. As part of its general study of the characteristics of crude oils, therefore, the Bureau of Mines has developed a system of classifying them according to "base." This system as first published in 19274 was limited to four classes and in its original form is no longer considered adequate. Since the system was first published the Bureau has analyzed a large number of crude oil-, including representative samples from nearly every important producing field in the world, and has found that the system of classification could be revised and amplified to advantage. The revised system is presented herein. Bulletin 2916 states that many oil producers and refiners use the word "base" much as it is used in pharmaceutical work. For example, the "base" or "basis" of an ointment or salve is the fatty material (lard, petroleum, or lanolin) used as a vehicle or carrier for the active medicinal principles. Apparently many of the pioneers in the petroleum industry considered crude oil similar in nature to these medicinal products in that it consists of a semisolid, nonvolatile base and 1 volatile portion can be distilled off to make gasoline, kerosene, and other products. Many crude oils when chilled slowly deposit a waxy material (paraffin); this fact may have been one reason for the use of the term "paraffin base" in referring to such oils. Almost all of the petroleum first discovered in the United States was of this nature; not until the oil industry was extended to California and along the Gulf coast was petroleum found that contained no wax but apparently did contain asphaltic material Accordingly, these oils were known as "asphalt-base" oils. The use of this term, however, seems unfortunate, as better-grade oils of this type contain little if any asphalt; the descriptive term "naphthene base" now seems to be a more desirable term than "asphalt base." The term "intermediate base" is also used commonly in referring to oils intermediate in oharacteristios between those of paraffin and naphthene base.

Jan 1, 1935

By Wm. W. Odell

In distributing natural and mixed gas, the industry is each year confronted with the problem of manufacturing gas in increasing amounts as the supply of natural gas becomes more nearly exhausted. The manufactured gas is now used in mixtures with the still available natural product, and will subsequently be used straight as a substitute gas. The gases that might be considered, and are producible by tried and developed processes, include water gas, carbureted water gas, and coal gas. Singularly, these gases can be used in this manner in ordinary appliances only when proportional amounts of them in the mixtures do not vary beyond rather definite limits, unless burner adjustments are made. The limits are defined by the specific gravity, content of inerts, and burning properties of the respective gases. Anticipating a future standard for city gas lower than that of natural gas during the period when considerable natural gas is available, there is justification for considering the possibility of re-forming natural gas and making a product that has substantially the same properties as other gases which can readily be generated. This report gives the results obtained during a series of tests made under a cooperative agreement by the U. S. Bureau of Mines with the Ohio Fuel Gas Co., re-forming natural gas at Toledo, Ohio, in full-scale operation in a water-gas generator having a grate area of 25.1 square feet. ACKNOWLEDGMENTS The Ohio Fuel Gas Co. constructed a special water-gas generator for the tests and provided men and the necessary funds for its operation. Appreciation is expressed for the general spirit of helpful cooperation which was evidenced in the activities of all those who took part in the work. Particular acknowledgment is made of the assistance rendered by C. W. Wallace, manager, and by C. F. Cramer, superintendent, and A. Upp, foreman of the plant.

Jan 1, 1929