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By John W. Adams, W. D. Bensema, Motohisa Kanda

Two different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating coal mine, Robena No. 4, located near Waynesburg, Pennsylvania. One technique measures noise over the entire electromagnetic spectrum of interest for brief tine periods. With present instrumentation, the spectrum can be covered from 40 Hz to 400 kHz. It is recorded using broad-band analog magnetic tape, and the noise data are later transformed to give spectral plots. The other technique records noise envelopes at several discrete frequencies for a sufficient amount of tine to provide amplitude probability distributions. The specific measured results are given in a number of spectral plots and amplitude probability distribution plots. The general results are that at frequencies below 10 kHz, power line noise within the mine is severe. Impulsive noise is severe near arcing trolleys, and at lower frequencies near any transmission line. Carrier trolley phone signals and harmonics are strong throughout the mine whenever the trolley phone is in operation. Additional information beyond that included in this report may be obtained from the authors, who are with the Electromagnetics Division of the National Bureau of Standards.

Jan 4, 1974

By L. A. Haas

The feasibility of removing sulfur dioxide by carbon monoxide reduction in a fixed-bed catalytic reactor was investigated by the Bureau of Mines. The reduction rate of sulfur dioxide with carbon monoxide was significantly dependent upon the iron and alumina content of the mixed catalyst. Maximum catalytic activity was obtained with about 40 percent iron-alumina mixture with a nominal gas mixture of 10 percent carbon monoxide, 5 percent sulfur dioxide, and the balance nitrogen. The synergistic effect of this catalyst mixture was explained by a dual reaction site mechanism, with both iron and alumina augmenting their specific sites at their interparticle contacts. The catalytic activity also increased with decreasing catalyst pellet size. With O.7-mm pellets, the entire pellet appeared to be catalytically active in a 2-gram catalyst bed. The apparent activation energy of the reaction was 18.3 kcal per mole in the temperature range of 350° to 600° C. Carbonyl sulfide (COS) was produced by the interaction of carbon monoxide and sulfur. The amount decreased with decreasing CO concentration. The ratio of COS formed per SO2 removed reached a maximum at about 400° C. The reaction rate appeared to be independent of S02 concentration in the range of 0.2 to 16 percent. The rate, however, increased directly with the CO concentration in the range of 5 to 20 percent. The presence of CO2 (<15 percent) had no appreciable effect on the rate. However, not over 0.5 percent oxygen could be tolerated. This method appears feasible for removing S02 from waste gas if the oxygen is removed prior to the catalytic S02 reduction process.

Jan 1, 1971

By Raymond B. Ladoo

"The recent discovery and exploitation of petroleum territory have resulted in the enactment of new petroleum laws in most of the South American Republics. The activities in the discovery of these new fields were engendered by the knowledge of the fact that present producing fields must within well defined periods be exhausted. Oil operators were willing to take the initial steps in exploitation in the absence of legislation that applied strictly to petroleum operations. The enactment of modern legislation in many of these Republics encouraging and protect¬ing exploitations may cause tremendous oil activities in these countries, and the results may be comparable with the magnitude of the undertakings and the prestige of the companies now entering this territory.These, oil fields are admirably located for convenient distribution of petroleum by water to all the Nations using oil as fuel for shipping and industrial concerns. The oil markets of the western coast of South America will derive immense benefits from the Panama Canal. This navigation route brings these markets into direct ocean shipment with the Atlantic coasts of the Western and Eastern Hemispheres.One deterrent to oil production in the Republics of South America is the want of inland. transportation facilities, but the recent laws of these Republics without exception provide for acquiring rights of way for pipe lines and other modes of transportation; and doubtless the great interests and. syndicates already operating in these regions will, as production increases, provide ample pipe line transportation sufficient to convey to the coast the oil produced. It way be assumed, from the legal guarantees afforded, and from operating equipment and machinery that are now being concentrated that refineries will be erected at shipping points for the purpose of making these petroleum products accessible to the world."

May 1, 1921

By Noel N. Moebs

The Bureau of Mines investigated severe coal mine roof support problems along a section of main entries in the Pittsburgh coalbed in southwestern Pennsylvania to identify the causative factors. The mine roof was examined in detail, and various sedimentary structures are described that contributed directly to irregular and unstable roof. Small-scale paleochannels, scours, and related slickensides were identified as the leading cause of bad roof, and isopach maps were prepared to illustrate a method whereby the presence of these structures could be inferred in advance of mining. Probably second in importance was the occurrence of relatively incompetent flaggy, poorly cemented sandstone, weakened by coal and micaceous laminea. No effect of in situ stresses on roof stability was detected.

Jan 1, 1977

By Bernard Porter, E. A. Brown

Electrical conductivities and densities of the LiF- UF , LiF- ThF4 , NaF - C1F4 , and NaF - ThF systems were measured as functions of composition and temperature . The specific conductance and density varied linearly with temperature . Molar and equivalent volumes , as well as heats of activation for conductance , were calculated from the experimental data . At 1,000 ° C , the molar volumes ranged from 16 to 40 cubic centimeters per mole and the specific conductance ranged from 9.8 to 2.5 per ohm- centimeter as the actinide metal fluoride concentration changed from 0 to 60 mole - percent . Heats of activation for conductance were 3 to 7 kcal per mole . The data are interpreted on the basis of a semilattice model for the melts .

Jan 1, 1964

By Ben E. Argyle

"The tungsten area in southern Mecklenburg County, Virginia, was studied by the Bureau of Mines during the period August 1944 to March 1945. The explorations were an expansion of the work done by the Bureau in 1943 in the tungsten area of Vance County, North Carolina, which joins Mecklenburg County on the south.3/Outcrops of quartz veins in the area were searched for and examined, and the only Promising showing found (a vein on the Gladys N. Taylor tract) was explored by trenching, test pitting, and diamond drilling (fig. 1).Mecklenburg County, Virginia, is in the southeastern part of the State, bordering on North Carolina,U. S. Highways 1, 15, and 58 traverse the County, and State and County roads provide ready access to most parts of the area.In 1942, Joseph and Richard Hamme discovered tungsten-bearing quartz veins in Vance County, Forth Carolina, and started mining and milling the ore. The first concentrates were shipped in July 1943. In August 1943, the Hamme holdings were acquired by Haile Mines, Inc., who continued the mining operations.The Bureau of Mines began exploratory work in North Carolina in June 1943. Reconnaissance work showed that the mineralized belt extends north-ward into Virginia. The Kimball tract, which joins the Taylor property on the north, was explored in 1943 by trenching and drilling by the R. G. Lassiter interests of Raleigh, Y. C., with disappointing results.The topography of the district is mature and characterized by wide, shallow valleys and low, rounded ridges. The main ridges trend northeast. Most of the area ranges from 300 feet to 400 feet above sea level.The relief apparently is controlled by resistant quartz lenses and the associated hard, silicified zones. The enclosing schists and granites are usually deeply weathered. Consequently, most of the quartz veins are found on the ridges."

Apr 1, 1946

By J. G. Stuart, A. W. Cipkins, R. H. Thompson

Preliminary safe distances for blasting wiring from typical electromagnetic sources are presented. The distances are for underground coal mines and electromagnetic sources in the frequency range below 10 MHz. The distances are based on measurements performed at 3 locations in each of 3 coal mines. The measurement apparatus, measurement procedure, measurement results and the rationale used in the calculation of the safe distances are all described. The safe distances presented are dependent on the measurement results and their interpretation. More measurements are clearly necessary to establish the validity of the suggested distances.

Jan 1, 1985

By Edward F. Courtney

Loss of life, loss of sight, crippling injuries, and property damage nearly always result from accidents involving explosives. The severity of such accidents has prompted lawmaking bodies to pass laws concerning the transportation, handling, and use of explosives; manufacturers of explosives publish manuals &apos;describing explosives and practical methods of handling then; and mining companies and others who use large quantities of explosives publish rules based on actual experience for the guidance of their employees. Careless storage of explosives by thoughtless or incompetent persons, particularly if they are left where children or saboteurs have access &apos;to them, has led to many serious accidents. Many contractors and mining operators who use explosives are extremely careless about storing them. It is the purpose of this paper to discuss the explosive-handling practices of a large western mining company, which are considered better than most.

Jan 1, 1946

By James S. Browning

The Bureau of Mines conducted laboratory batch and pilot plant flotation tests to determine the technical feasibility of recovering commercial-grade mica from a California micaceous schist. Best results in the laboratory batch tests were obtained using sodium carbonate and sodium silicate for pH control and quartz depression, and a combination of fatty acid and cationic reagents as the mica collector. In continuous pilot plant flotation tests, an alkaline fatty acid-cationic method recovered about 70 percent of the mica in a concentrate analyzing 95.6 percent mica.

Jan 1, 1965

By J. L. Konchesky

The Bureau of Mines investigated the main reactions of coal gasification by steam. Coal (minus 70 mesh)-water slurry was fed into a laboratory-scale tube-coil gasifier to show the effects of residence time (0.6 to 1.1 sec), steam-coal ratio (2 to 11 lb/lb), and temperature (1,600° to 1,900° F), at about 1-1/2 atm. Devolatilization was very rapid: about 70 pet of the coal&apos;s volatile matter evolved within 0.6 sec at about 1,600° F; temperature increase released more volatile matter until about 95 pct was driven off at 1,900° F. Devolatilization was not increased by raising steam concentrations and was only slightly increased by extending residence time. Below 1,600° F, there was no evidence of the steam-carbon reaction, but at 1,900° F more than 80 pct of the coal&apos;s fixed carbon was converted to gas; the conversion was increased Significantly by increased residence time and steam concentration. The water-gas shift reaction occurred simultaneously with devolatilization, and the steam-carbon reaction, approaching equilibrium with increased residence time and temperature and decreased steam concentration.

Jan 1, 1969

By W. T. Abel

Laboratory tests were conducted with a closed, recycling system to evaluate the effectiveness of solid-in-gas suspensions as heat transport mediums. Micronized graphite in helium or nitrogen was circulated by a centrifugal compressor to determine the feasibility of the method and heat transfer capabilities of the mediums. Suspensions were circulated without plugging or eroding the compressor or piping. At low flowrates and light (0.1 to 0.2 volume-percent) graphite loadings, slightly less power was required to transport a given amount of heat with suspensions than with helium alone. Graphite deposition on the heat exchange surfaces of the cooler decreased the heat transfer effectiveness at higher solids concentration. Efforts to eliminate deposition are described.

Jan 1, 1963

By E. Morrice

High-purity neodymium, praseodymium, and didymium (a cerium-free mixture of light rare-earth elements) were prepared by electrolysis of the oxides in a medium consisting of the respective rare-earth fluorides and lithium fluoride. The metals were electrodeposited in the liquid state and collected as nodules on a skull of frozen electrolyte. Cells were operated from 1,000° to 1,100° C. The requisite temperature was maintained by passing alternating and direct currents through the bath. Graphite was used for the anodes and tungsten for the cathode. The metal products contained <0.02 percent each carbon and oxygen and <0.025 percent tungsten as major impurities. Analysis of typical didymium metal nodules showed an approximately twofold enrichment in neodymium and praseodymium over their respective concentrations in the cell feed. The lanthanum content of the metal was about one-half its content in the oxide.

Jan 1, 1967

By R. S. Dean

The principle of explosive crushing depends upon the fact that an expandable substance contained within the pores of a solid body will disrupt such a body upon expansion. Such expansion may be obtained by the detonation of an explosive or by the sudden release of pressure of a superheated liquid. That this principle of disruption may be applied to minerals rests on the fact that cracks, cleavage planes, and pores exist in all minerals to an extent hardly conceived possible heretofore. Crushing by this method takes advantage of forces applied from within the mineral rather than from forces applied from without. The application of a force from within would appear to be more effective.

Jan 1, 1932

By David C. Byrne

PURPOSE: Evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. RESEARCH SUMMARY: The results of previous NIOSH research show that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and gender. Using hearing thresholds at 4,000 Hz as an indicator, coal miners experience hearing loss 2.5 to 3 times greater than would be expected for persons not exposed to occupational noise. At age 50, 90% of coal miners and 49% of metal/nonmetal miners were found to have a hearing impairment. In comparison, only 9% of a nonoccupationally exposed control group had a hearing impairment at age 50. There are numerous barriers to the prevention of hearing loss among miners. In an effort to overcome some of these obstacles, this work was initiated to evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. Experiments will involve analysis of this new technology under both laboratory and field conditions. Laboratory components will consist of controlled studies using an anthropometrically correct test fixture as well as human subjects to evaluate the adequacy/effectiveness of various hearing protective devices. Electroacoustical performance testing of new noise monitors will also be conducted in a laboratory setting. Subsequent field studies will determine the actual usefulness and practicality of the personal protective/monitoring equipment as used in different mining situations. It is anticipated that increased on-the-spot awareness of hazardous noise levels and the availability of better-suited hearing protectors will provide a degree of protection beyond what is currently attained in different mining environments. Therefore, the intent of this project is to identify and adapt new acoustical technologies and products that have a direct application to individual mine workers. With increased knowledge of these technological advances, a greater demand for similar devices will likely occur, which, in turn, will lead to a better understanding and awareness of hearing loss prevention methods throughout the mining community. The ultimate goal is for widespread integration of useful hearing loss prevention products and devices into the daily routines of miners

Jan 2, 2000

By D. R. Brooks

The Bureau of Mines has tested a dewatering technique for phosphatic clay waste. The technique utilizes a flocculant, polyethylene oxide (PEO), that forms strong, stable flocs that can be dewatered on a static screen followed by further dewatering on a rotary screen or trommel. In field tests conducted in central Florida, clay wastes containing approximately 4 pct solids have been consolidated to greater than 20 pct solids. The rate at which PEO-treated material continues to dewater in a mine cut also was monitored. Preliminary results indicate that PEO-treated material will dewater to 30 pct solids in 80 days. Pretreatment of phosphatic clay waste with lime lowers the PEO dosage required for dewatering.

Jan 1, 1986

By Thomas E. Marshall, Patrick A. Kinek, Gerald L. Finfinger

The purpose of this investigation was to evaluate the integrity of the existing shutoff valves and actuators used under high-temperature conditions in the Bureau of Mines&apos; horizontal borehole methane drainage pipe- line system and to determine the potential for improvement in the system. In the field tests, both fire-safe ball valves and standard brass ball valves were initially subjected to a 30-min pan fire without thermal protection. Neither valve could maintain line pressure beyond 11 min in a fire that reached temperatures between 500° and 700° C. Based on the test results, it was concluded that the brass ball valve used in the Bureau&apos;s methane drainage pipeline system can be retrofitted with an inexpensive "fire bag" to substantially increase its integrity under mine fire conditions.

Jan 1, 1986

By J. M. Singer

The objective of this investigation was to determine minimum air velocities and entrainment rates for coal and rock dust dispersion in wind tunnel experiments under conditions that simulate dispersion from surfaces in coal mines where airflows are induced by weak gas explosions. Dust deposits were bed-or ridge-shaped; particle sizes were 6 to 80 microns (cohesive deposits) or 100 to 150 microns (free-flowing deposits); and wind tunnels were 7.62 cm wide by 5.08 cm high by 300 cm long, and 2.4 m wide by 1.5 m high by 215 m long. The investigation showed that minimum air velocities (directed at mid-height) of separate, layered, or mixed piles of coal dust and rock dust were within the range 5 to 30 m/sec, independent of size of wind tunnel. This finding considerably facilitates scaling of data to mine-size passageways. Free-flowing deposits dispersed relatively slowly by single-particle detachment; cohesive dusts dispersed faster by the breaking and lifting of large clumps along weak failure flames; particle dispersion occurred in flight. Layered or mixed deposits of coal and rock dust did not disperse selectively. Semiempirical expressions were derived relating minimum air velocities and dispersion rates to dust-pile geometry, cohesion, porosity, and bulk density.

Jan 1, 1972

By Spencer P. Howell, Munroem Charles E.

"Introduction;As in the case of TNT previously presented*, this report presents the results of an investigation to discover the safest and best way of utilizing picric acid for industrial blasting purposes. It describes the physical and chemical properties of this explosive, gives precautions to be observed in handling, packing, preparation of cartridges, and holes, presents the results of field tests in blasting stumps and bowlders, and compares the results with those obtained from dynamite.The investigations reported herein were undertaken and this paper has been prepared, solely to aid in the salvage of the surplus picric acid accumulated for war uses and released by the declaration of the armistice. No funds were available nor have any been appropriated with which to defray the expense of converting this picric acid into any other form or to prepare any explosive mixture from it. The sole problem was to find appropriate uses for this military picric acid in existing needs and to show that it can be efficiently used in carrying out essential civil projects.It is not intended by this publication to promote the use of picric acid as an industrial explosive further than is necessary for the proper utilization of this surplus. On the contrary, the authors believe that picric acid by itself is unlikely to come into general use as an industrial explosive, chiefly because of its cost but also as shown by the clouds of smoke it emits on explosion and the nature of the reactions it undergoes because we do not obtain from it its highest efficiency. As demonstrated in its previous use in Joveite, better results and higher efficiencies may be obtained by mixing picric acid in proper proportions with sodium nitrate or ammonium nitrate, to more completely oxidize the picric acid, and another nitrosubstitution compound, such as nitronaphthalenes, with which do desensitize and waterproof the composition formed. By such admixture not only may the energy resident in the picric acid, be more fully utilized but the cost of the resulting blasting explosive should be much less than that of picric acid."

Apr 1, 1921

By M. R. Peterson

The U.S. Bureau of Mines investigated column flotation for recovery of a high-grade fluorite (CaF2) concentrate and byproduct concentrates from the Fish Creek fluorite deposit in Eureka County, NY. The recovery scheme consisted of (1) grinding the ore to minus 48 mesh, (2) fluorite rougher and cleaner flotation, (3) desliming the rougher fluorite flotation tailings at 20 Jjm, (4) mica flotation, and (5) silicate rougher flotation. Acid-grade fluorspar, mica, free silica (Si02) sand, and low-grade beryl (Be3Al2S~018) concentrate were produced in a 100 lb/h continuous column flotation unit (CCFU). The highest results achieved were %.6-pct CaF2 recovery in a fIrst cleaner concentrate containing 99.7 pct CaF2. Beryl recovery was as high as 92 pct at a grade of 5.3 pct BeO. The silica sand, which assayed 98 pct Si02, was recovered as the rougher beryl flotation tailings. Collector reagent consumption was reduced 45 pct for fluorite and 58 pet for silicate flotation in comparison with bench-scale conventional flotation. All products were signillcantly improved in both grade and recovery over conventional flotation results, and the recovery scheme was simplifIed by removal of several stages of flotation in the fluorite and silicate flotation steps.

Jan 1, 1990

By B. H. Eccleston

Experimental data were obtained from two medium-duty diesel engines derated to qualify for use in underground mines. Gaseous and particulate emissions from these engines were measured and results provide information on the effect of exhaust treatment devices on the emissions. The devices in the study were a catalyst, a particulate trap, and an exhaust gas cooler of the water scrubber type. Emission levels of carbon monoxide and hydrocarbons were observed to be very low in comparison with emission levels of comparable engines in full-rated operation. Oxides of nitrogen and benzo(a)pyrene content of the exhaust also were found to be somewhat low in comparison with previous findings. For particulate reduction, the combination of a particulate trap and a scrubber was observed to be the most effective combination tried; in some cases, over 60 pct particulate reduction was effected by the trap-scrubber combination.

Jan 1, 1981