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By D. E. Wolfson

As a part of its overall program of coal carbonization, the Bureau of Mines is studying the coking properties of coals that may be used for metallurgical purposes. The objectives of this study were given in detail in a previous report The inherent suitability of coal for metallurgical purposes depends primarily on (1) chemical composition, (2) preparation characteristics, and (3) carbonization behavior. The first two factors, Be well as the amount of available reserves, are considered in selecting coals for carbonization tests. The selection of coal beds in Harlan County, Ky., for coking tests was based, in part, on recent studies of coal reserves by Wallace,3/ who estimated the recoverable reserves in beds 28 inches or more thick, in tons, as follows:

Jan 1, 1956

By Robert W. Metcalf

Since the spread of the European war virtually cut off imports from Denmark, Belgium, and France, the Bureau of Mines has had numerous inquiries as to domestic sources of grinding pebbles and silex or other types of ball mill liners. USES Flint pebbles and tube-rill liners are used by grinders of certain ceramic materials to prevent contamination of the finished product by iron abraded from steal baler and liners. The feldspar industry is one of the largest users of flint grinding mediums; they are employed also by curtain grinders of talc and soapstone, ground sand and sandstone, quartz, and chalk. Some paint materials, such as lithopone, have been ground in pebble Flint pebbles have been used more or less in the past, especially by cement manufacturers, and, for fine grinding of gold, copper, or other ores in which iron contamination is not especially deleterious.

Jan 1, 1940

By Th. G. Sahama

This paper contains some new thermodynamic data for silicates in the series Mg2SiO4-Fe2SiO4 and MgSiO3-FeSiO3 and Lives the result: of a thermodynamic attack on the problems of stability end paragenoses. Although some data are lacking, satisfactory agreement with mineralogical and petrological observations is indicated.

Jan 1, 1949

By Robert Lundquist

REAM is a unique method of rock breaking using high energy projectile impact. This report-describes the most recent in a series of tests demonstrating mining applications for the REAM method. In an underground limestone mine at Greer, West Virginia, REAM was used to drive a short tunnel and drill a large diameter borehole. Along with breakage data from these tests the goal of the program was to examine environmental problems which might result from the use of cannons under-ground. A total of 103 shots was used to advance a 14-l/2-feet high by 10-feet-wide face a distance of 5-1/2 feet. It is estimated that the 9.3-pound-concrete projectiles launched at 5000 feet per second will break an average of 0.78 tons of limestone or 67 percent of the 1.125 tons of granodiorite broken in previous tests. The 9-inch-diameter borehole was drilled horizontally by repeated axial impact for 7 feet, 2-1/2 inches by 21 shots giving an average of 4.12 inches per shot. Scaling this result to compressible impact energy yields an estimated 5.8 inches per shot for a 12.8-inch-diameter hole compared to 8 inches per ~hot for a 16-inch-diameter hole in granodiorite. Noise measurements indicate that a silenced cannon can be used within a few hundred feet of mine personnel in a room and pillar mine within the legal limit of 140 dB impulse without additional protection. Some fume measurements were made with satisfactory results, even though the military propellants used produce much greater quantities of toxic fumes than the liquid propellant proposed for the future.

Jan 1, 1976

By R. C. Corey

GERMANIUM is an element that has come into widespread use in the electronics industry in recent, years. So far this increasing demand has been, met by ample supply: however, the future balance is uncertain, and the need has been recognized to discover additional domestic sources of germanium. This investigation was conducted to study the possibility of obtaining a potential supply of germanium from coal or coal ash. It has been known for some time that coal contains germanium; the discovery that By ash from coal-fired boilers often contains appreciably more germanium than the original coal suggested the possibility that coal ash might be an abundant and economical source of this element. In this study the concentration of germanium was determined in numerous samples of coal and ash. A number of miscellaneous waste materials also were examined in the course of the investigation; the results are reported as a matter of general interest. The methods and equipment employed are discussed in detail. Sample-preparation and analytical techniques are described in the appendix. Spectrographic analyses were made on a total of 639 samples, including coal, coal ash, slap ash from lignite and peat, wood ash, and various inorganic materials. Qualitative analyses were run on all samples, and quantitative determinations were made on those samples that contained enough germanium to be measured by this method The lower limit at which germanium can be determined quantitatively by spectrographic analysis is 50 parts per million (p. p. m.), but concentrations of less than 20 p. p. m. can be detected qualitatively.

Jan 1, 1959

By V. F. Parry

[Approximatel~r 7-1/2 illion tOlls of subb1tnminous coals are mined an-nuall in Colorado, Wyo~ing, and Montana, of which 50 percent probably reaches dome ,-tic conswno:os. r:L'he moi s t'_re of the se subbi t1.Uninous coal sis high, averae;:t.:ug about 25 :!,)ercent \-Then they are :nined. T'ne coals are non-caking d ~~ack to a vari ble degree when exposed to nornal atmospheric conditions. ~hey a~e gpod domestic fuels, are considered to be smokeless in most furn~ces, and have been used. f, r f!1an: y ars in hand-fired domestic furnaces in hich tnc practice i~ to e~ploy large lureps for efficient com-]

Jan 1, 1941

By Robert H. Ridgway

Chromite has been produced commercially for slightly more than a century. Developed, at one time, chiefly as a chemical pigment raw material, it has subsequently found extensive application in other chemical industries - as a refractory material for furnace linings and as the sole source of the metal chromium. For some years prior to 1914, its use as a refractory predominated; but post-war development in alloy steels, principally stainless steels, enhanced the metallurgical demand in the form of ferrochrome with a consequent increase in the demand for chromite. More recently direct reduction of chromite in alloy-steel manufacture has been applied to a limited extent. Alloy steels containing varying amounts of chromium, with or without other alloying elements, now find extensive use in a ride variety of ways - in structural material, machines, industrial equipment transportation by land, sea, and air, sanitary equipment, food preservation, and a multitude of other uses. In recent years chromium plating has had wide application and has become important. industrially, but the amount of raw material consumed

Jan 1, 1936

By Beatrice Lukens, David Schlain, John D. Prater

"The electrolytic manganese process4/ developed by the Bureau of Mines involves the electrolysis of a solution of manganese sulfate and ammonium sulfate in a diaphragm-type cell. Metallic manganese is deposited on the cathodes, and sulfuric acid is produced at the anodes. The spent electrolyte contains, in addition to the sulfuric acid, approximately 40 percent of the manganese sulfate and most of the ammonium sulfate originally present in the feed solution. This spent solution is used to leach fresh ore that has previously been subjected to a reducing roast. The resulting leach liquor is purified and returned to the cell.Manganese of very high purity is produced by the electrolytic process. The properties of this metal are so different from those of the best grade of manganese that can be made by any other commercially feasible process that it is virtually a new material. Electrolytic manganese has been used in the preparation of new high-manganese alloys with valuable properties.3/ and further developments are to be expected. The electrolytic manganese process not only results in a product of superior qualities, but is applicable to large tonnages of domestic ores that are unsuitable for direct use in producing ferromanganese.The future industrial use of electrolytic manganese is of course, related to its cost. Decreases in the cost of production will lead to wider use of the metal; conversely, increases in the volume of production made possible by greater demand will bring further .decreases in cost."

May 1, 1946

By G. B. Atkinson

The Bureau of Mines investigated a method for increasing the leaching rate of bulk superalloy scrap to facilitate recycling and recovery of critical metals such as Ni, Co, and Cr. Three superalloys were investi- gated, the cast-nickel-base superalloy IN-738, the wrought-nickel-base superalloy Rene-41, and the cast-cobalt-base superalloy Mar-M-509. Superalloys melted with 20, 30, 40, and 50 pct Al metal to form inter- metallic compounds were easily crushed to a convenient particle size and reacted rapidly with acid solutions which dissolved the metals. For example, leaching 1/2-in pieces of unalloyed IN-738 with excess 6N HC1 at 95° C for 2 h dissolved about 0.5 pct, while leaching 10 g of minus 20-mesh 30 pct Al-70 pct IN-738 with excess 6N HC1 at 95° C for 2 h dis- solved 96.2 pct.

Jan 1, 1983

By F. G. Miller, H. C. Miller

Petroleum technologists and progressive operators constantly are striving to increase the percentage of oil that may to recovered from reservoir rocks through wells. The exhaustive studies that have been made of the function of natural as in the production of oil, for example, have aided operators greatly in increasing the quantity of oil recovered from reservoirs. Natural gas dissolved in and otherwise associated under pressure with oil in reservoir rocks, however, is not the only source of energy available for moving oil through sands to wells. In becoming "reservoir—energy conscious" engineers have learned that in many petroleum reservoirs the edgewater flanking the oil accumulation constitutes a potential source of energy capable, through proper control, of increasing oil—recovery efficiencies materially. No longer is the encroachment of water into the oil— and gas—filled tart of the reservoir considered as an evil to be combatted by devious methods but rather a natural consequence, incident to the withdrawal of nil and as from the wells, that may be used advantageously in lengthening the flowing life of wells and increasing the economic recovery of oil and gas.

Mar 1, 1938

By James L. Elder

Field-scale experiments were conducted at Gorgas, Ala., from 1951 to 1954. Three reaction paths were formed by electrolinking-carbonization, using electrode spacings of 150, 152, and 155 feet. The coal along these reaction paths was gasified, using air, oxygen, and steam separately or in various combinations. At the conclusion of operation, a drilling survey was conducted to determine the location and approximate area of the reaction zones. During the applications of the electrolinking-carbonization technique the maximum limitation on electrode spacing was not determined. Initial tests were conducted at 60-foot spacing. Successful path-preparation tests were made at 150-, 152-, and 155-foot spacings, and the indications were that much longer spacings were possible. The potential requirements appear to be constant, regardless of path length, while the gross power required probably will increase with path length. During the carbonization phase gas was produced that is similar in quality to coke-oven gas produced at low to intermediate temperatures.

Jan 1, 1957

By D. H. Zellers

Since its inception the United States Bureau of Mines has fostered the development of portable mine lamps. Although there is still much to be desired with respect to illumination in coal and metal mines and the replacement of open lights has been slow the Bureau has been given credit for assisting materially in the development and introduction of the safe and efficient portable mine-lighting equipment available today. Much of the work conducted by the electrical section of the Bureau entails approval tests of various types of electrical equipment, including lamps; to be used in atmospheres that may contain methane or coal dust in explosive proportion. If a can lamp meets the requirements-for safety, efficiency, and adequacy, as published in Schedule 6B,4 it is approved and is generally known as a "permissible" lamp. The terms "approved" and '"permissible' often are used interchangeably. The manufacturer must put an approval plate on each approved lamp, showing it has mot the schedule requirements. The approval plate is not a guarantee that the lamp is safe. However, if the lamp, once in service, has not had any parts changed or improperly assembled or if carts that wear out or depreciate have been properly replaced it should still, be safe, efficient, and adequate for the service intended. Virtually all electric cap lamps in service today in the United States and a great many that have been sent to foreign countries bear the approval plate of the United States Bureau of Mines. Although many explosions have been attributed to open lights none has been charged against the permissible cap lamp. Nystagmus, a disease of the eye attributed to working under insufficient illumination, is practically unknown among; American miners, although it is quite prevalent among European miners.

Jan 1, 1935

By G. W. Grove

The wearing of self-contained oxygen breathing apparatus, although relatively safe if proper precautions are taken, is dangerous if defective apparatus -is worn, if men with inadequate training, experience, and physical requirements are used, or if improper procedure is followed. This is proved by the fact that at least 26 men are known to have lost their lives while wearing-oxygen breathing apparatus since its introduction in this country about 35 years ago. Self-contained oxygen breathing apparatus, commonly called "mine rescue apparatus" and sometimes improperly referred to as "oxygen helmets," is the only equipment that can be used for respiratory protection against poisonous mine gases, regardless of concentration or against an atmosphere containing little or no oxygen.3/ Apparatus of this type was introduced in this country in 1907, and since that time it has been widely used in conducting rescue and recovery work after mine fires and explosions and in some other work. All oxygen breathing apparatus used in this country before 1918 was imported from Europe, and although this equipment provided safer, more rapid means of conducting recovery work after mine disasters, there were many mechanical deficiencies in the apparatus which resulted in the death of some of the wearers. This led to the research and experimental work by the Bureau of Mines that resulted in the development and manufacture of more reliable and efficient types of apparatus in this country.

Jan 1, 1944

By Jay F. Colinet

Longwall mining in lower seam heights may necessitate the use of single-drum shearers to overcome size constraints associated with standard double-drum shearers. To avoid the operational problem of clearance in the tailgate entry with one single-drum shearer, two single-drum machines can be operated on the same face, with each shearer responsible for mining a predefined portion of the face. However, utilization of two shearers on the same face necessitates the positioning of one shearer operator and a jacksetter in the return air of the upwind shearer, thus complicating respirable dust control on the longwall. In an effort to evaluate the unique dust control problems associated with this type of mining, the U.S. Bureau of Mines conducted dust surveys on two multiple-machine longwall operations. Sampling was done to quantify major sources of respirable dust and to identify potential solutions to problem areas. Sampling results indicate that the cutting sequences utilized on multiple-machine faces may have to be designed to minimize dust exposure, as opposed to optimizing productivity or facilitating operational requirements. Also, state-of-the-art dust control techniques typically found on double-drum shearer longwalls must be employed to help minimize the exposure of all face personnel to traditional dust sources.

Jan 1, 2010

By M. E. Adam

This report describes the construction and testing of large (30 ft high by 55 ft wide) stopping and overcast structures in an oil shale mine. The work was undertaken to develop construction techniques and cost data, and to measure leakage rates on full scale structures in an oil shale mine. A design data base was developed by reviewing industry practice, oil shale industry plans, and technical literature. Alternate layouts for room and pillar mining were examined to find ways to reduce the size and number of ventilation control structures. Six full size stoppings and one overcast were built in the Colony Pilot Mine. Leakage rates were measured using both SF6 tracer gas techniques and the ?brattice window? method. The leakage was measured both before and after a full scale face blast. Blast air pressures were measured across two of the stoppings. Cost and leakage data were used to evaluate the projected overall performance of various combinations of the stoppings in a two-panel oil shale mine.

Jan 1, 1986

By Thomas J. Peters

In 1979 and 1980, the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral survey of the 15,600 acre (6,310 ha) Freel Peak RARE II area (No. 5271) in the Lake Tahoe Management Unit. This study by the Bureau of Mines indicates that potential for economic mineral resources in the area is slight. The only mineralized structures in the area consists of two quartz veins. One quartz vein, at the Mountain Top Mine (fig. 1), located by Fred Denner in 1932, is estimated to contain 2,000 tons (1,800 t) of silver and copper-bearing resources. Chip samples from the vein averaged 0.61 oz silver per ton (20.91 g/t), and 1.59 percent copper. The narrow vein is not economically mineable. The other quartz vein is poorly exposed and contains traces of molybdenum. A second reported molybdenum occurrence could not be substantiated.

Jan 1, 1982

By Felix duBreuil

The present sampling procedure for evaluating the rock dusting conditions in a coal mine is time consuming. This study considers means by which this procedure could be simplified. Surveys were conducted in six coal mines in Pennsylvania to determine the in¬combustible content of the deposited dust. Some 2,000 samples were analyzed and statistically evaluated. It is suggested that the mean incombustible content could be obtained with fewer samples and smaller samples without greatly increasing the sampling error.

Jan 1, 1972

By Robert F. Pettit

This paper on methods and costs of mining and milling iron ore at the Iron Mountain mine of Ozark Ore Co., St, Francois County, Mo., is one of a series of Bureau of Mines reports on methods, practices, and costs of mining and milling throughout the United States. The Iron Mountain operation is notable for its successful transition from open-pit to underground mining, for use underground of large earth-moving equipment, and for development of a multilevel room-and-pillar mining method. Milling methods also have undergone transitions - from hand sorting and log washing in the early days to gravity concentration. Milling ultimately may include flotation to recover additional iron from products now discarded as tailing,

Jan 1, 1957

By O. T. Barrett, R. F. Aberethy, H. N. Cooper, Thomas Fraer, William L. Crentz

"INTRODUCTION The object of the techniques described in this report is to determine the possibilities of separating the components of a raw coal into such grades as may be necessary to recover some exceptionally clean functions for special purposes.To do this commercial gravity methods would require separation at very low specific gravities, entirely outside the range of conventional practice. Hence, a technique has been developed for breaking down cool ample, into very close fractions within the gravity range of the (-lean coal matter as well as for separating it from the refuse and particles.Such data on the fundamental specific-gravity consist of the clean-coal matter will serve to appraise the difficulty of the problem and to chow be accomplished if and when effective methods of making such separations commercially are developed."

May 1, 1945

By Russell Griffin

The current state of the art of fire and smoke detection technology is reviewed from the standpoint of suitability for use in under- ground metal and nonmetal mines. Detection modes, fire signatures, and environmental considerations are included. Preliminary results of long- term, in-mine tests are presented.