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By W. J. Fene

It is often desired to obtain samples of air in places where collection by ordinary methods is not feasible, as in shafts amore means of descent or ascent are not provided, in sewer manholes, in gas or water wells, in empty oil tanks, and in sealed areas in mines. Heretofore, when such sampling was required, it was necessary to utilize the aspirating method, which was not always satisfactory; and to obtain samples of air in deep shafts, it was necessary to use long sections of rubber tubing, which was not always available. DESCRIPTION OF NEW DEVICE A new method or "device" employs a common snap-type mousetrap to break the neck of a vacuum tube at the place where it is desired to collect the sample (see fig. 1). A mousetrap is mounted on one end of a block of wood 11-3/4 by 3 by 3/4 inches in such camper that a lead weight attached to the trigger hall spring the trap when the device is given a sharp jerk. A vacuum tube is placed on the other end of the block and held in place by a strong rubber band. A strip of corrugated rubber is placed on each side of the grooved block to prevent the tube from clipping when the sample is taken. An adjustable shoulder, provided with a rubber cap, is pieced se that the neck of the vacuum tube will rest on it. The shoulder is made adjustable to accommodate various sizes of tubas and to keep the neck of the tube from breaking tee far back from the point. A metal handle is fastened to one end of the block, with a hole in the end through which the brass wire used for lowering the device is tied. The device is enclosed by a strong wire-gauge covering, hinged on one side and so arranged that it can be locked shut on the other side. This covering prevent: breaking of the tube while it is being lowered or raised in a shaft or other place. Brass wire of not less than 22 gage should be used for lowering the device. A detailed drawing of the device is shown in figure 2.

Jan 1, 1940

By F. W. Benn

The Bureau of Mines investigated flotation methods for recovering fluorite and byproducts from two samples of the Fish Creek deposit in Eureka County, NV. The preferred method for tre.ating a fluorite-beryllium sample included (1) fluorite rougher and cleaner flotation, (2) desliming at 20 um, (3) muscovite flotation, (4) silicate flotation, (5) sodium hypochlorite wash of silicate concentrate, and (6) beryllium rougher and cleaner flotation from the silicate concen-trate. Laboratory results showed that over 94 pct of the fluorite was recovered in a recleaner concentrate containing 98 pct CaF2, Beryllium flotation produced concentrates containing in excess of 5 pct BeO with recoveries over 70 pet. The preferred method used for a fluorite-mica sample consisted of (1) fluorite rougher and cleaner flotation, (2) desliming at 20 um, and (3) mica flotation using an anionic-cationic collector system. Laboratory results showed that 84 pct of the fluorite was recovered in a recleaner concentrate containing 96 pct CaF2, Mica flotation produced a concentrate containing 95 pct mica at 85-pct recovery.

Jan 1, 1986

By George S. Rice

There have appeared, from time to time, comparisons of various features of coal mining practice in the United States and Great Britain. A recent, article, appearing in a British journal, points out that the American miner produces 3 1/2 times as much coal per shift as the miner, at one-half the cost, and proceeds to explain the natural industrial, and engineering causes which lead to this result. Amon« he reasons advanced. is that the American coal miner enjoys the advantage of more easily worked seams of coal, due to the fact that the coal mining industry in the United States is of more recent date than in Great Britain. The latter qualification is not correct, because where these advantages exist, they will persist. The coal beds of the United States are not buried deeply, except in the remote parts of the country, as in the Uinta Basin of Utah. The article referred to states that many of our miners are still employed on out seams reached by "adits", (which we term entries), or by vertical shafts of moderate depth. It is probable in fact that the great bulk of the coal of the United States is taken out from a depth of less than 400 feet.

Mar 1, 1920

By A. E. Wells

"When the United States entered the World War, the heavy requirements for sulphuric acid in the manufacture of explosives made necessary a definite knowledge of the sulphuric acid capacity of the country. The Bureau of Mines, under the authority conferred by the explosives regulation act, made a thorough survey of the sulphuric acid situation. In this work, which was personally directed by the writer, comprehensive data were collected on the situation and capacities of the various acid plants, sources of supply of raw materials (brimstone, pyrite, pyrrohotite, zinc ores and concentrates, waste sulphur dioxide gases from copper smelting, and spent oxide from gas works), the principal points in regard to manufacturing processes (chamber and contact) and the uses of the acid. The results of this investigaion have recently been published by the Bureau of Mines, as Bulletin 184, entitled ""The Manufacture of Sulphuric Acid in the United States"" by A. E. Wells and D. E. Fogg. The following paragraphs on the uses of sulphuric acid are abstracted from this bulletin.Sulphuric acid is one of the most important of all chemicals, not only because of the large quantities manufactured but also because of the wide use of the acid in many different industrial works. Sulphuric acid is to the chemical industry what iron is to metallurgy. The general public, however, does not realize this fact, for sulphuric acid does not appear in the finished product as does iron and steel, but is only a means to an end. It is essential in many industries, such for example as in the manufacture of phosphate fertilizers, explosives, dyes and petroleum products. In recent years in the United States, especially in the East, the demand for sulphuric acid for chemical and metallurgical industries has been an accurate and sensitive barometer of the general business conditions. This demand for acid responds much more quickly to a general slump or boom in the industrial world than does the demand for iron and steel."

Oct 1, 1920

By Martin H. Stanezyk

The Bureau of Mines investigated leaching of selected copper sulfide minerals and a composite of impure flotation concentrates at elevated temperatures and pressures with ammoniacal solutions. Copper 1 (tractions of 96 percent were obtained by leaching chalcopyrite at 75° C under oxidizing conditions for 60 minutes. An extraction of 99 percent of the copper contained in the composite concentrate was obtained by leaching the product for 90 minutes at 75° C. In tests of bornite, chalcocite, and covellite, 90 to 97 percent of the copper was extracted at 20° C provided an 8-hour reaction period was used. At 75° C essentially complete dissolution of the copper from these three minerals was accomplished in 60 minutes. Additions of ammonium sulfate to the leach solutions were required to obtain high-percentage extractions of the copper from bornite, chalcocite, and covellite. Although ammonium sulfate was not required when digesting chalcopyrite, copper extraction was enhanced and less free ammonia was required when ammonium sulfate was added to the leach pulps. The chemistry of leaching copper minerals was studied. It was C, termined that chalcocite altered to covellite as one step in the dissolution When leaching iron-bearing copper sulfides, hydrated iron oxide formed on the mineral surfaces, indicating that a diffusion process prevailed. No evidence of covellite was detected.

Jan 1, 1966

By Stuart R. Zimmerley, John Gross

"In the study of ball-mill grinding at the Intermountain Experiment Station of the United States Bureau of Mines at Salt Lake City, Utah, it was desirable to measure the work input to a ball mill at the mill itself so that consideration of motor efficiency and transmission losses would be eliminated.The device adopted is essentially that used by Prof. H. E. T. Haultain4 in measuring work input to rolls. The mechanism was changed only so as to adapt it to a ball mill.Figure 1 is a diagrammatic sketch of the apparatus.The pulley which rotates the mill is loose on the mill shaft and is equipped with ball bearings. This pulley is connected by means of three tangential springs to the driving plate, which is solid on the mill shaft. Power applied to the loose pulley is transmitted to the driving plate, and hence to the mill, by the three springs; the greater the resistance of the mill, the greater the spring extension. The extension of the springs is transmitted by the steel extension tape to the differential integrating meter.The integrating meter is operated by two friction wheels in contact with the integrator disk which revolves at a definite ratio of speed to that of the mill. The friction wheels are held in contact with the disk by the spring suspension of the integrator and are connected to a differential gear cage, the revolutions of which are recorded on a counter such as is used in gas meters. Due to the differential gears the c e is stationary when the two friction wheels revolve at the same speed in opposite directions; this condition exists when the integrator is centered on the disk and corresponds to no load or to a zero spring extension. As the lead is applied, the springs extend and move the integrator from the center or zero point, resulting in a difference of speed between the two friction wheels. Due to the revolution of the differential cage this change in. speed is transmitted to the counter. The integrator and extension tape system is kept taut by means of a light spring attached to the integrator, the spring having just enough tension to assure that the integrator returns to zero when the load becomes zero."

Feb 1, 1931

To improve the level of hearing protection by providing workers with an inexpensive, easy-to-use device to check earplug fit. Background Approximately 30 million workers are exposed to hazardous noise on the job, placing them at risk of permanent hearing loss, tinnitus, and other disorders. Although the preferred solution is to eliminate noise through engineering controls or to reduce noise exposure through administrative controls, hearing protectors are critical when noise is unavoidable. Studies of hearing protector users have shown that average protection values in the real world are much lower than the labeled noise reduction ratings determined in laboratories with trained and motivated subjects. Even worse, many hearing pro­tector users get virtually no protection at all because of poor fit. The studies also show that users have a harder time achieving adequate protection levels with earplugs than with earmuffs. It?s difficult for users to tell if earplugs are working well just by looking at them. A more accurate approach is to check how much they block or ?attenuate? noise. Earplugs vary in their attenuation characteristics, with most providing a maximum of 20?35 decibels of noise reduction when worn correctly. Any earplug that?s suitable for use in noisy settings will attenuate noise by at least 15 decibels. Personal fit testing is an effective way to help hearing protector users improve the fit and protection levels of the devices. However, existing fit-testing systems are expensive and unsuitable for use at many industrial worksites.

Dec 1, 2008

"Initiated as a part of the Bureau of Mines program for development of strategic minerals for national defense, various mines in the Poughkeepsie Gulch and Mineral Point mining districts were examined by C. R. Wilfley, W. R. Hamilton, .and N. E. Wvvlwy, Jr., Bureau Of 'Mines engineers, in July and August 1943, July 1944, and September 1945. In a subsequent report a proposal was made to evaluate this isolated area 'of some 15 square miles located in Ouray and San Juan Counties, Colo.Reconnaissance work in the area was begun in June 1946. Mapping and sampling were begun in July and was completed in Pougkeepsie Gulch and extended westward to include the Hendrick Gulch area of the east side of Ironton Park. Project work was recessed for the winter on October 15, 1946 after approximately 6 square miles of the Poughkeepsie Gulch,district been mapped and 801 samples had been taken.In this report the physical features, climate, and ore deposits districts are described, and a brief history of mining and production lead, zinc; and silver is given.The individual mines and prospects in, the area are described in detail.A list of patented claims and ownerships is given in appendix I, and analyses of samples are tabulated in appendix II.The San Juan preliminary project was directed by Paul T. Allsman, chief, Salt Lake City Branch, Mining Division and was supervised by William M. Traver, Jr., supervising engineer, Colorado Field. Office.Chemical analyses were made by the Salt Lake City laboratory under the direction of H.E. Peterson, chemist, and S. R. Zimmerley, chief, Salt Lake City Branch, Metallurgical Division.Harold A. Waddington, president, Great Divide Mining & Milling Corp., and Ernest Miller, owner, Como Consolidated Mines, were particularly cooperative in making available maps and data concerning their properties."

Sep 1, 1949

By H. H. Schrenk

[A calorimetric method3/ for the determination of benzene in amounts as low as 0.001 m has been developed recently at the U.S. Bureau of Mines Pittsburgh Experiment Station by the authors, with the assistance of chemical personnel from the Allegheny County (Pa.) Relief Works Division. The method is based on the direct nitration of either liquid or gas - phase benzene, followed by neutralization, extraction with butanone, and final treatment with sodium hydroxide which produces a violet color. The color is matched with color standards of known values. Although the method is adaptable to many conditions the primary objective was a procedure that would be suitable for hygienic investigations.]

Jan 1, 1935

By L. B. Pankratz

The heat content above 298.15° K was determined for crystalline vanadium silicide of the composition V3Si. This substance has a minor thermal anomaly (probably a heat-capacity maximum) near 560° K; the extra heat absorption is about 50 cal/mole. The original heat-content data are presented, and smooth values of the heat content and the corresponding entropy increments are listed for the temperature range from 298.15° to 1,500° K. Equations representing the heat- content values and derived heat capacities are also included.

Jan 1, 1963

By H. H. Schrenk

[A colorimetric method5/ for the determination of benzene in amounts as low as 0.001 mg has been developed recently at the U.S. Bureau of Mines Pittsburgh Experiment Station by the authors, with the assistance of chemical personnel fro a the Allegheny County (Pa.) Relief Works Division. The method is based on the direct nitration of either liquid - or gas - phase benzene, followed by neutralization, extraction with butanone, and final treatment with sodium hydroxide which produces a violet color. The color is matched with color standards of known values. Although the method is adaptable to many conditions the primary objective was a procedure that would be suitable for hygienic investigations. The development worth included a study of possible interference by chemicals that be present in those situations in which the method. would be employed. In this study it was found that a specimen of hexane prepared by the Gulf Research Laboratory, Pittsburgh, by fractionation of West Virginia natural gas gave positive result for benzene, whereas a specimen of pentane prepared in the same manner showed only a trace, and specimens of n -heptane and octane (2,2,4 trimethylpentane) supplied by Eastman Kodak Co. save a negative result. According to information obtained from the Eastman Kodak Co. the latter two compounds were highly purified, the n-heptene being prepared from line and the octane synthesized in the laboratory. On nitration of a larger amount of tae natural hexane a visible quantity, of needlelike crystals which resembled those of m-dinitrobenzene was obtained. The hexane from this nitration was recovered by distillation and again nitrated, but no crystals or colorimetric indication of benzene was obtained. This imitated that the specimen of natural hexane contained a substance which at least had the chemical behavior of benzene.]

Jan 1, 1935

"Fire fighting in metal mines under the best of conditions is a dangerous, a slow, and a difficult task. Certain gases generated from combustible material burning in restricted areas are poisonous, even in small quantities, and can not be breathed without serious and often fatal results. In addition to poisonous gases, smoke is given off which obscures the vision of the fire fighter and frequently prevents him from gaining access to the fire area. Many fire-fighting crews have had to turn back because their vision was so impaired by the dense smoke that the fire area could not be located and there was danger of them becoming lost in the mine.In mines having mechanically controlled ventilation - that is, mines not dependent entirely upon natural air currents - the gas and smoke can be forced ahead of the fire-fighting crews, thereby facilitating exploration of the mine and saving the time, energy and oxygen of the mine rescue apparatus crews.Where currents of fresh air can be circulated up to points near the fire without danger of seriously spreading the fire, fresh air bases can be established in the immediate vicinity, and a more intelligent campaign for fighting or controlling the fire can be mapped out.Positive air currents through forced ventilation may also result in saving the lives of miners who otherwise might have been trapped in smoke and poisonous gases.It is generally known that comparatively few metal mines have attempted to regulate or control air currents, with the result that when a fire occurs underground, the normal ventilation may be reversed, short circuited, or the air current may be in one direction one minute and in the opposite direction the next; or, generally speaking, the ventilation can not be depended upon, and smoke and poisonous gases may accumulate in any part of the mine or ""drift"" on the fire-fighters or on the miners endeavoring to escape."

Apr 1, 1921

By Oliver C. Fursman

The Bureau of Mines undertook this investigation to study methods of utilizing red mud residues from production of alumina from bauxite. Pilot-plant tests were conducted using Jamaican and Surinam red muds. Both the carbon-lime-soda sinter process and electric-arc smelting with coke and limestone were employed to recover iron and alumina. Alumina recoveries of 85 to 90 percent were obtained by the sinter process; although iron recovery was about 80 percent, the magnetic product was finely divided and difficult to separate from the gangue. Smelting red muds in the electric-arc furnace produced a pig iron with 98-percent recovery of iron; up to 84 percent of the A1203 was recovered by leaching the calcium aluminate slag with Na2C03 solution. A titania product assaying 96 percent TiO2 was recovered from the nonmagnetic portion of Surinam red mud sinter by extraction with H2SO4. Leached calcium aluminate slags and brown mud (from the combination Bayer process) are possible raw materials in the manufacture of portland cement.

Jan 1, 1970

By Charles Sabine

The 27,960-acre Newberry Mountains Wilderness Study Area (WSA) is located in the Mojave Desert, 17 miles east-southeast of Barstow. In 1983, the U.S. Bureau of Mines, in conjunction with the U.S. Geological Survey, investigated mineral resources of the area as part of the wilderness review process. The Newberry Mountains are underlain by Paleozoic metamorphic rocks, Mesozoic plutonic rocks, and Tertiary volcanic rocks. Eleven mines and prospects were examined. Of the seven sites within the WSA, only the Northrup Prospect is mineralized. Only a few tons of manganese-bearing rock, containing 49% manganese oxide (MnO), are exposed, but exploration may disclose larger deposits. The Azucar Mine, a past producer of gold, is the only site examined outside the area that appears mineralized. Sample data from quartz veins exposed at the surface do not indicate that resources are present; however, the occurrence could not be fully evaluated because underground workings were not accessible. Sand, gravel, and stone are plentiful in the WSA, but alternate sources outside the WSA are available.

Jan 1, 1985

By J. H. Maysilles

The Bureau of Mines, U.S. Department of the Interior, is investigating several types of low-grade uranium deposits. Projections indicate that an increased percentage of future production will be derived from such sources. One material studied was from the Coso Mountains of California; this material contained 0.04 to 0.12 percent U3O8. The deposit contains at least two distinct types of mineralization. The material representing the bulk of this deposit was amenable to acid leaching; 80 to 85 percent U308 extraction resulted from leaching with 20 to 40 pounds per ton of sulfuric acid. No oxidizing agent was required. This ore fraction could be treated by either agitation or percolation leaching. Uranium recovery and purification from the acid leach solution was accomplished using anion exchange followed by precipitation with hydrogen peroxide and ammonia. The second type of mineral was very refractory to acid leaching; a maximum extraction of only 44 percent was obtained with sulfuric acid. Nitric and hydrochloric acids were ineffective also.

Jan 1, 1978

By K. O. Bennington

The thermodynamic properites of petalite (Li2A12Si8O20) were determined by the Bureau of Mines. The enthalpy of formation was determined by hydro-fluoric acid solution calorimetry. The values from the elements and from the oxides are ?Hf°298.15 = 2,335.8 ± 3.0 kcal/mole and ?H°295 (from oxides) = -50.60 ± 1.20 kcal/mole. Low-temperature heat capacities were determined by adiabatic calorimetry from 10.69 to 302.11 K. The derived standard entropy is S°298.15 = 111.0 ± 1 cal/deg-mole. Enthalpy increments above 298 K were measured by copper block calorimetry from 298 K to 1,193.6 K. The various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of the measurements. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature from the elements and constituent oxides. The Gibbs energy of formation is ?G°f298.15 = 2,203.8 kcal/mole.

Jan 1, 1980

By C. J. Chindgren

The Bureau of Mines investigated the technical problems involved in recovering commercial-grade vanadium products from alkaline solutions of low vanadium content. Conditions were defined for precipitating calcium vanadates from sodium vanadate solutions with calcium chloride and calcium hydroxide and for dissolving the precipitates with acid, sodium carbonate, and sodium bicarbonate to obtain vanadium-enriched solutions from which either red cake or ammonium metavanadate was recovered. Calcium vanadates with CaO:V205 mole ratios of 2, 3, and 4 were produced with recoveries of 93 to 100 percent. Optimum recovery of the low-lime variety of calcium vanadate was obtained by employing excess calcium chloride and adjusting the pH to a range of 8.0 to 8.5. High vanadium extractions were obtained in concentrated solutions by dissolving the calcium vanadate precipitates with any of the reagents tested. The resulting extracts contained 25 to 125 grams V205 per liter. Conventional procedures used to precipitate either red cake or ammonium metavanadate from the enriched solutions gave excellent vanadium recoveries.

Jan 1, 1967

By Frank D. Lamb

Pyrophyllite, a hydrous aluminum silicate (Al2 Si4O10 (OH)2 ) has been mined in North Carolina and marketed without beneficiation for the past 100 years, but recent demands for higher-grade material indicate that an economical concentration method is needed for at least a part of the pyrophyllite production. Past production has depended upon selective mining and hand sorting, which is often unsatisfactory because of the finely disseminated character of the ores. The major impurity in North Carolina pyrophyllite ores is quartz, which accounts for the abrasiveness of the commercial product. Since pyrophyllite is only slightly heavier than quartz, those ores cannot be beneficiated by simple gravity-concentration methods. Some separation can be attained by differential grinding and air classification because of the difference in hardness of the two minerals) but the separation is not sharp. Froth flotation of pyrophyllite from Quartz has never been attempted commercially, but if the demand for high-grade material is sufficient, it would seem that this process offers the most premise of being economically feasible.

Jan 1, 1950

By J. W. Town

The Bureau of Mines studied the effects of reducing gas composition, tem-perature, and superficial gas velocity on the regeneration rate of alkalized alumina. Regeneration was assumed to follow the simple first order reaction for removal of sorbed S02: dµ/dt = -Kµ. An Arrhenius relationship can be plotted, which shows an activation energy of about 75 kcal/mole for simulated reformed propane. The general effects of the individual gases can be described as follows: (1) CO and H2 produced rates proportional to their con-centrations, up to about 5 percent for each; (2) addition of CO2 had no effects on the regeneration rate by CO; (3) the regeneration rate by H2 was lowered by the addition of H2O while the regeneration rate by CO was increased by 0 addition; (4) H2S showed a positive effect up to concentration levels of about 2 percent and then produced a rapid negative effect; (5) carbonyl sulfate (COS) increased the sulfur content; and (6) propane was as effective in regenerating the loaded pellets as was simulated reformed propane.

Jan 1, 1971

By A. T. Iannacchione

Underground stone mining represents an emerging sector for the U.S. mining industry. As this expansion takes mines under deeper cover and as more efficient mining methods are utilized, adequate stone pillar design methods will become more important. It is the purpose of this paper to examine current design practices and to discuss issues for safe mine layouts so that a rational first approach towards balancing the demands for increased production can be weighed against increased risk to worker safety from rib instabilities and pillar failures. Seventy-two stone mine pillar designs were examined. Pillars with width-to- height ratios below 1.5 and subjected to excessive stress levels appear more likely to fail. When width-to- height ratios fall below 1 .O, defects in the pillars, such as through-going discontinuities, can have a significant influence on stability. Discontinuity persistence, dip, material properties, and orientation are important factors controlling pillar strength. The influence of discontinuity dip, a characteristic easily identified in the field, was examined so that its presence could be accounted for in developing generalized guidelines for pillar design.