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By P. M. Gruzensky

In view of some of the outstanding properties of chromium, considerable effort has been made in recent years to prepare the high-purity metal in ductile form. The object of this investigation was to obtain such metal by electrolysis of chromic acid solutions and to determine the conditions that yield optimum results. The apparatus is described, as well as the parameters that received consideration. Ion-exchange resins were employed to remove cation impurities from the electrolyte. Tensile specimens prepared from the electrodeposits by arc melting, press forging, swaging, and drawing, were ductile at room temperature. INTRODUCTION Metallic chromium displays an exceptionally high resistance to corrosion, oxidation, and wear at elevated temperatures. Although these properties are utilized to some extent when chromium is alloyed with other metals, such as in stainless steels, high-chromium alloys and pure chromium are not employed as engineering materials because of a serious lack of ductility and impact resistance at room temperature. Because high-chromium alloys appear promising as refractory metals for applications such as in gas turbines, much interest has been shown recently in the preparation of uniformly ductile chromium and in determining which factors contribute to its brittleness.

Jan 1, 1957

By H. R. Babitzke

The purpose of this investigation was to evaluate the potential of columbium-hafnium alloys as structural materials for use at elevated temperatures. The work described in this report was conducted to determine the properties of columbium-hafnium alloys and to select the more promising ones for further improvement. Properties determined in this report were machinability, hardness, workability, tensile strength, and oxidation resistance. Ten ingots, ranging from 100 percent columbium to 70 atomic-percent hafnium, were prepared and subjected to tests. The test results showed that the alloys with 33 and 50 atomic-percent hafnium were superior in workability, strength, and oxidation resistance. For the alloy series tested, the strength and hardness values increased with the increasing hafnium content. Maximum values were reached with 50 atomic-percent hafnium. The oxidation resistance was poorest at the 1 atomic-percent hafnium level but improved with increasing hafnium content through 70 atomic-percent. Eight of the ten ingots were fabricable at room temperature. The two remaining ingots, those with 5 and 10 atomic-percent hafnium, required hot-working.

Jan 1, 1962

By William E. Wallace, S. J. Page, B. L. Razzaboni, C. A. Hill, Pamela Mike, P. Bolsaitis, M. J. Keane, Val Vallyathan

"Respirable quartz cytotoxicity, as measured by erythrocyte hemolysis and pulmonary macrophage release of lactate dehydrogenase in vitro, is neutralized by boiling in water in glass test tubes for 10 to 40 minutes. The cytotoxicity is reduced to near zero by boiling l to IO mg quartz per milliliter water. For greater concentrations of quartz in water the hemolytic potential after 40 minutes of boiling approaches that of native quartz. Replacing the medium with fresh water midway through boiling results in full detoxification through 20 mg quartz per milliliter water. Pre-boiling the medium with silica reduces the detoxification effect. Detoxification persists after mild drying at l 10°C for 8 hours, and persists after three days of resuspension in water at room temperature.INTRODCJCTIONResearch underway to determine interactions of quartz and other mineral dust surfaces with pulmonary fluids and alveolar macrophages in culture led to the observation that when dusts were autoclaved in aqueous suspension, their cytotoxic effects on macrophages were suppressed, in some cases fully and even after several days incubation with the cells. This finding was in direct contradiction to earlier results from both short term macrophage lysosmal enzyme release assays, as well as longer term cytotoxicity assays from macrophages in culture; in those studies, dusts were steam autoclaved at 121°C with no liquid water but with steam present. 1.2 However detoxification under boiling conditions has been reported in other research. 3 It was decided to use the hemolysis assay to further investigate these findings, because of its sensitivity simplicity and cost.RESCULTS AND DISCCISSIONRespirable quartz dust used in this study was taken from a stock of crystalline silica, Min-U-Sil; obtained from Pennsylvania Sand Glass Corporation, fractionated in air with a particle classifier. The small size fraction retained for use was 80% less than S micrometer particle diameter, with an area equivalent median diameter of 1.24 micrometers as estimated by automated image analysis. The silica was at least 98.S mass percent silica as determined by X-ray energy spectrometric analysis; and the crystalline form was alpha-quartz as determined by X-ray diffraction. It's specific surface area was 3.97 square meters per gram as determined by nitrogen adsorption isotherm methods. I"

Jan 1, 1990

By H. S. Caldwell

This report describes work by the Bureau of Mines on the vacuum distilla¬tion of some of the more volatile metals such as cadmium, zinc, and magnesium from lead and tin. Evacuation within a distillation apparatus allows rapid diffusion of vapor away from the evaporation surface and prevents reaction of the vapor with residual gases. A reduction of pressure to several tenths of a millimeter makes possible practicable distillation rates, at temperatures for which the partial pressure of the metal vapor exceeds 10-3 atmosphere. The rate and selectivity of distillation depend primarily on the volatility and molal ratios of the alloy metals, and their chemical activity to each other. For very rapid evaporation or low concentration of the more volatile constituent, the rate is determined by the rate of diffusion of the evaporating metal, to the surface of the melt. Cadmium, zinc, magnesium, and tellurium were found to volatilize readily from both lead and tin. Tellurium appears to volatilize as an intermetallic compound rather than the pure metal. Antimony could not be removed from lead at 1,000° C.; the condensate was nearly all lead. Antimony, bismuth, and lead were removed from tin.

Jan 1, 1960

By Lucia Kuizon

The Morongo Wilderness Study Area (WSA) is in south central San Bernardino County, California. U.S. Bureau of Mines examined the area during the fall of 1983. No mines, prospects, leases, or mining claims were found in the WSA. There are no known mineral deposits within the study area boundaries. Sand and gravel in the area is suitable for many types of construction uses, but similar and larger deposits outside the WSA are closer to markets. No energy resources have been identified in the WSA.

Jan 1, 1984

To develop and design a bit that will rapidly drill smooth and precise instrumentation holes in soft rock. Approach Use a one-piece bit made by combining a drag bit and a diamond bit. Because a smooth-walled borehole with a precise diameter is needed for borehole pressure cells (BPC) and other borehole instruments, a diamond bit is usually used. However, diamond bit drilling is slow, and the bit will tend to bind when squeezing ground is encountered. On the other hand, the drag bit will cut faster, but the walls of the drill hole will be rough and the diameter will not be as precise. The combination will provide a bit which penetrates as rapidly as a drag bit, but retains the smooth-wall and precise borehole diameter of a diamond bit. How It Works A three-foot-length of EW-size drill rod is centered in a diamond bit by welding it to three equally-positioned spacers at each end of the bit. A drag bit is attached to the EW rod with a standard EW-to-drag bit adapter as shown in the diagram. Three equally-spaced diamond inserts are set to the desired hole size and welded to the diamond bit barrel behind the crown. These inserts increase the smoothness and precision of the hole by cut-ting away any hole closure. Three equally-spaced shims are set approximately 0.020-inch under the overall insert diameter size and welded to the rear of the diamond bit barrel. The combination bit should be used on a diamond drill with either water, mist or air as the coolant.

Jan 1, 1982

By George S. Rice

A novel method of extinguishing a mine fire in a stowed or gob-filled area by employing liquid carbon dioxide under high pressure eras used recently with success at the President (Prasident) coal mine, Bochum, Germany, as reported by P. Cabolet in Gluckauf (Apr. 24, 1937, p. 393) The use of carbon dioxide gas as a fire-fighting agent in surface plants and in ships is now general practice in the United. States, but when it has been tried for extinguishing fires in mines in large areas more or less confined by stoppings it has not been successful. Examples of the latter method of attempting to fight mine fires are given in Bureau of Mines Bulletin 229, Fifty-Nine Coal-Mine Fires; How They Were Fought and That They Teach, by G. S. Rice, J. VT. Paul, and 14. VT. von Bernewitz (1927). The reason for its nonsuccess may be either that the stoppings are not tight or that the roof and pillars are more or less fissured and enough air passes into the area to sustain a slow fire, whether of spontaneous origin or produced by gas explosion or other source of ignition.

Jan 1, 1937

"The major thrust of this research is directed towards a better undstanding of the behavior of airborne dust particles in underground mine airways. Figure 61 shows a schematic of dust flow in mine airway. The work included development of a mathematical model of dust behavior in mine airways, experimental study of the behavior of dust clouds and comparison of computer model output and experimental results. Re-entraiment is a secondary source of dust in mine airways and factors affecting re-entrainment are being identified.Investigations have encompassed both experimental and theoretical research into the behavior of dust in mine airways. Experiments were performed in mine airways under both controlled and normal operating conditions (Figure 62). The controlled experiments included the documentation of the concentration and desposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using real-time aerosol monitors (RAM-1) (Figure 63).On the theoretical front, a convection-diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion. Comparative analyses of results of the controlled experiments with the predictions of the mathematical model were carried out. In addition to the overall validity, the adequacy of the individual components of the model, such as deposition in the total and respirable range, and dispersion were examined in light of the experimental observations."

Nov 1, 1988

Continuously separate mixture of non-magnetic materials (such as scrap, precious metals, or certain ores) at a reasonable cost. Approach Nonmagnetic materials of different densities are rapidly float/sink separated by an augmented lifting force produced In a magnetic fluid (liquid) by the effect of an external magnetic field. The magnetic fluid is a colloidal suspension of magnetite In kerosene, prepared by a low-cost process. How It Works Separation is accomplished in an open trough filled with magnetic fluid. A magnetic field is established in the fluid, by energizing an electromagnet having poles on each side of the trough. Due to the design of the magnet poles and air gaps, the magnetic field is strongest at the bottom, about 10,000 oersteds, and uniformly decreases in strength to about 2,000 oersteds at the top of the fluid. Therefore, the magnetic field gradient increases with depth. The magnetic force attracts the entire separation medium (magnetic fluid) creating a reaction force of equal magnitude and acting in the opposite direction. This reaction created within a magnetic fluid/magnetic field combination is called a magnetic levitation force. It increases with the field strength. In this case because the magnetic field is strongest at the bottom of the trough, the magnetic levitation force will quickly float lighter material while heavier material sinks.

Jan 1, 1980

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

SUMMARY The objective of this program was to develop a system to extinguish coal mine fires by remote sealing of the underground passageways. The system developed had to be versatile enough to function under a wide range of operating conditions, including large variations in passageway geometry, depth of mine, water conditions, both in the mine and at the surface, and rubble in the mine passage. The system developed had to include instrumentation for the remote probing of the passageway prior to sealing, a system for sealing the mine passages, and instrumentation for remote monitoring of the quality of the seal during and after construction. These objectives were successfully achieved during this program. The remote mine sealing capability of the system was satisfactc rely demonstrated in a field test conducted at the Eastern Associated Coal Corporation Federal No. 1 Mine in Grant Town, West Virginia. The remote sealing consists of: (1) A sonar initial probing system which can operate satisfactorily even in the presence of dense smoke. The system is capable of determining both the local passageway geometry, identifying the presence of cribs and other obstructions, and the position of the borehole in the mine passage. (2) A mine sealing material system which utilizes fly ash for making the complete seal or as a bulk filler in conjunction with a urethane, froth foam, seal topping system. The choice of using fly ash alone or fly ash with foam topping depends on a number of factors, such as quality of seal desired, time available per seal, depth of borehole, passageway geometry, and water holding require¬ment. The fly ash-foam seal is a better seal, capable of sealing against a higher water head than fly ash alone. The fly ash sealing

Jan 1, 1973

By J. L. Ambs

The U.S. Bureau of Mines (USBM) Diesel Research Program emphasizes the development and evaluation of emission control devices to reduce exposure of miners to diesel exhaust pollutants. Studies by the USBM have shown that diesel exhaust aerosol (DEA) contributes a substantial portion of the respirable aerosol in underground coal mines using diesel equipment not equipped with emission controls. The USBM and the Donaldson Co., Inc., Minneapolis, MN, have developed a low-temperature, disposable diesel exhaust filter (DDEF) for use on permissible diesel haulage vehicles equipped with waterbath exhaust conditioners. These were evaluated in three underground, mines, to determine their effectiveness in reducing DEA concentrations. The DDEF reduced DEA concentrations from 70 to 90 pct at these mines. The usable life of the filter ranged from 10 to 32 h, depending on factors that affect DEA output, such 'as mine altitude, engine type, and duty-cycle. Cost per filter is approximately $40.

Jan 1, 2010

By Paul T. Allsman

Iron-ore deposits in southwestern Utah, as the major source of iron ore for western steel plants, were investigated by the Bureau of Mines in 1942-45 in cooperation with property owners and operators and with the assistance of the United States Geological Survey with a view to determining and extending the known reserves. The factual data resulting from that project were presented in a previous report and in a report on the geophysical surveys now in course of publication. The present report has been prepared in response to expressed public interest in the ore reserves of Iron County. Mining began in the district in 1871} but. did not become important until 41 1923. From 1923 to 1946, inclusive) production totaled 10,139,500 long tons. In 1945 the district yielded 1,931,749 long tons containing 52.84 percent iron; in 1946 the corresponding figures were 1,317,671 and 53.75. The deposits lie .in a narrow, 23-mile long belt extending northeasterly from Washington 'County into Iron County along a line of mountains, chief of which are Iron Mountain, Granite Mountain, 'and Three Peaks in Iron. County. The deposits are hematite-magnetite bodies, chiefly in limestone near its contact with the monzonite of the mountain masses, but with a few important veinlike bodies in the monzonite or at the contact. They range in size from small pods to several millions of tons, and in depth from surface or near-surface to a known maximum of 1,300 feet:

Jan 1, 1948

By K. R. Farley

A simplified method for the atomic absorption determination of antimony is described. Samples are dissolved in hydrobromic acid and diluted to volume with water. Solutions can be ready for analysis in about 10 minutes and are stable for at least 24 hours. The spectral line at 231 nanometers is used, and there is no effect on absorption resulting .from the presence of any concentration of HBr. Absorbance is linear with antimony concentrations up to 120 micrograms per milliliter. Sensitivity is 1.48 micrograms per milliliter per 0.0044 absorbance. Relative errors on National Bureau of Standards Standard Reference Materials were 3 percent or less, and relative standard deviations on 12 determinations of each of three flue dust samples were 4 percent or less (95-percent confidence limit).

Jan 1, 1980

By Jerry W. Ramsey

The Bureau of Mines studied two Pennsylvania anthracites using low-temperature carbon dioxide adsorption. A modified form of the Brunauer-Emmett-Teller equation was used to calculate specific surface areas. Two mesh sizes of each anthracite were used to determine how gamma irradiation at 106 and 108 rads, both in vacuum and in the presence of air, affected the carbon dioxide surface areas. Results show that anthracites have a system of pores that are essentially all interconnected rather than isolated; that anthracites differ from one another in specific surface, which may correlate with density; and that irradiation in vacuum has no discernible effect on specific surface of anthracite, but irradiation in air does produce changes in specific surface.

Jan 1, 1966

Decrease the dust concentrations at the shearer and reduce downtime associated with spray system maintenance. Approach Increase the quantity and quality of the water supply on longwall faces by decreasing pressure losses, Increasing pump capacity, and installing a "non-clogging" filtration system. How It Works Water sprays and ventilation are two of the primary methods of dust control on longwall operations. Increasing the quantity and quality of the water supply to spray systems is one of the more effective and least costly dust control methods that operators have at their disposal, yet this method is largely ignored. Poorly positioned spray nozzles operating at low pressures (and flows) which plug frequently cannot be effective. Water supply system Improvements should be a fundamental part of all longwall dust control plans. Upgrading a water supply system may require one or more of the following improvements depending upon where a particular system may be deficient: Increasing pump capacity for additional flow and pressure; increasing line sizes to decrease pressure losses: and, decreasing maintenance downtime and Improving water quality by installing a "non-clogging" filtration system.

Jan 1, 1981

By Roy C. Bartholomae

This U.S. Bureau of Mines study found that the performance of the active noise cancellation hearing protector in a reverberant field was mixed. The performance varied when the conditions changed from ideal to nonideal. The active noise cancellation (ANC) component provided substantial additional noise reduction from 125 to 500 Hz for all testing conditions (broadband noise or pure tones both with and without safety glasses). While the ANC under ideal conditions provided additional attenuation from 500 Hz and below, under nonideal pink noise conditions the ANC amplified noise below the 125-Hz third octave band. There was a middle band of frequencies at which the ANC amplified noise levels ranging from 630 to 4,000 Hz. The results for pure tones showed that attenuations were higher but that they followed the same general trend.

Jan 1, 2010

By Richard J. Bielicki

Poor mixing of methane and air at coal mine working faces causes fluctuating methane concentrations. If these fluctuations are large enough, methane levels can periodically exceed safe limits, even though the time average methane concentration may be satisfactory. Concentration fluctuations measured underground can result both from variations in methane emission rate and poor mixing. The present paper reports on a statistical analysis of fluctuations at a constant methane emission rate, that is, on fluctuations due only to poor mixing. A full-scale model of a working face was used. Both peak heights and elapsed times between peaks were evaluated. Good mixing was indicated by normal, Poisson, and exponential distributions while poor or incomplete mixing was indicated by log-normal or gamma distributions.

Jan 1, 1974

By John W. Brown

Electrical resistivity surveys were conducted at three sites in Wyoming in an attempt to detect underground rubble zones in oil shale and to determine their size and resistivity contrast. The zones were detected at Rock Springs sites 4 and 5, but none were detected at Green River site 1. The resistivity of the rubble zones at sites 4 and 5 is greater than that of the surrounding rock. The zones at sites 4 and 5 are concluded to be roughly ovaloid in shape, with a horizontal diameter of 33 m and a vertical thickness of 24 m. Both rubble zones and the blasting that created them are considered to be centered at a depth of 24 m.

Jan 1, 1972

By E. C. Lane

The motor gasoline that is being marketed in the United States this winter (1928-29) is slightly more volatile than that gold a year ago. This characteristic is shown by a slight lowering of the distillation temperatures, particularly at the average initial and 20 per cent boiling points. Daring the past mine and a half years the Bureau of Mines has made semi annual surreys of the gasoline marketed in the United States; the Survey just completed is the nineteenth in the series. The 12 cities in which samples have been collected were chosen as representative of the more important marketing territories, as it was obviously impracticable to obtain a sample of every gasoline sold in the entire country.

Jan 1, 1929

Detect fires in or near mine shafts, isolate smoke filled areas, and remotely extinguish fire. Approach A system (of sensors, automatic alarms, an aboveground control console, remotely operated ventilation doors, and sprinklers) has been built from off the-shelf components, and fire, tested in two mines. How It Works The system uses three different kinds of sensors that can detect the heat or smoke of a fire and automatically actuate alarms. When the alarm sounds in the control center on the surface, water sprays in the mine shaft and shaft station areas can be remotely turned on to deluge both the inside and the outside of the mine shaft's wooden support structure. To protect miners from toxic fumes, smoke control doors can be closed or opened, either remotely from the control center or directly by miners using the manual or electrical actuators at the door locations. Man doors built into each ventilation door allow persons to pass without opening the main door.

Jan 1, 1977