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Crosson and Peters treat the errors that result in miner location due to errors in the overburden earth model used for computing location. A parallel effort by J. Powell of PMSRC is discussed here, where the location method used is that of the Westinghouse location program - "Miner". This location program was tested by Powell by using arrival times generated from the overburden earth model of Table l* rounded to the nearest millisecond. Location computations were then made using 3 geophones at a time. The average location is tabulated for all geophone triplets except when 3 geophones are in line. Geophone arrays were as shown in Tables 2 and 3. The manner in which the test was done is illustrated in Figure 1. I. SUMMARY OF RESULTS The arrival time differences, based on the Table 1 earth model, together with geophone locations based on the array geometries of Tables 2 and 3, were entered into the computer, together with a stated depth of 700 feet and an estimated overburden seismic velocity of 10,000 feet per second. These parameter values were processed by the location program - "Miner". Figure 2 illustrates the interpretation of the plots and data. The tabular data and plots of Table 4 and Figures 3, 4, and 5 illustrate the location error results obtained. These plots indicate that for sources within the array, the errors are considerably less than the measured errors obtained during field tests of the present location system. The possible reasons for this discrepancy are noted in Part Eight (Earth Models).

Jan 1, 1974

By Ronald D. Hill, Elmore C. Grim

The removal of overburden often exposes pyritic materials (iron disulfide). As shown in equations 1 and 2, the oxidation of this material results in the production of ferrous iron and sulfuric acid. The reaction then proceeds to form ferric hydroxide and more acid, as shown in equations 2 and 4. [ ] Consequently a low pH water is produced (pH 2-4.5). At these pH levels, the heavy metals such as iron, manganese, copper, and zinc are more soluble and enter into the solution to further pollute the water. Water of this type supports only limited water flora, such as acid-tolerant molds and algae; it will not support fish life, destroys and corrodes metal piers, culverts, barges, etc., increases the cost of water treatment for power plants and municipal water supplies, and leaves the water unacceptable for recreational uses. The amount, and rate of acid formation, and the quality of water discharged are a function of the amount and type of pyrite in the overburden and coal, time of exposure, characteristics of the overburden, and amount of available water(l). Crystalline forms of pyritic material are less subject to weathering and oxidation than amorphic forms. Since oxidation by oxygen is the primary reaction during early acid formation, the less time pyritic material is exposed to air, the less acid is formed. Thus, a positive preventative method is to cover pyritic materials as soon as possible with earth, which serves as an oxygen barrier. In terms of mining, this step is accomplished by current reclamation techniques and small open pits.

Jan 1, 1974

By John H. Soulé

"INTRODUCTION The Peerless mine was examined by W. R. Storms, an engineer of the Bureau of Mines, on June 2, 1944, in conjunction with a mineral survey of the adjoining For Bayard Military Reservation. Storms again studied the mine on January 13; 15 and 16, 1945, to determine the possibilities of finding new ore reserves to replace these depleted by mining. A project to explore the Peer-less vein at depths below and to the south of the principal mine workings was proposed. Special attention was given to the possibility of exploring favorable beds in the Magdalena and Lake Valley limestones at points near the Peerless fault.The proposed project was approve and exploratory work started on January 2, 1946, and was completed on June 5, 1946. The mine was not in operation during the project, and all equipment had been removed."

Apr 1, 1947

By Steven J. Page

Accurate measurement of workplace respirable dust concentration is an essential step in eliminating lung disease in any occupational setting. In the United States (U.S.) coal mining industry, this measurement process has relied upon a personal sampler that includes a 10 mm Dorr-Oliver (DO) nylon cyclone operated at a flow rate of 2.0 L min-1 to collect a respirable dust sample. Dust concentrations measured with this sampler are multiplied by 1.38, which was empirically derived, to convert them to measurements approximating the United Kingdom British Medical Research Council (BMRC) definition of respirable dust upon which the health effects of coal mine dust are based. The International Organization for Standardization (ISO) subsequently refined the respirable dust definition and the U.S. National Institute for Occupational Safety and Health (NIOSH) 1995 Criteria for a Recommended Standard presented a conversion multiplier of 0.857 to apply to the 2.0 L min-' DO (in addition to thel.38 multiplier) to obtain equivalent ISO concentrations, as approximated by the 1.7 L min-1 DO. However, the conversion multiplier 0.857 was derived indirectly from a limited size distribution data set rather than a direct comparison of the DO samplers. The present analysis focuses on providing a more accurate conversion multiplier derived from direct comparisons of the 2.0 L min-1 (with 1.38 BMRC equivalency multiplier) and 1.7 L min-1 DO cyclones. A weighted linear regression analysis of this database suggests that a more accurate estimate of the conversion multiplier is 0.815.

Jan 1, 2009

By Willard L. Hunter

The separation of tantalum and columbium by solvent extraction was under-taken as part of the Bureau of Mines research program to improve methods for extracting, separating, and reducing these elements to metal. The diethyl ketone aqueous HCl-HF system was one of several systems studied to determine the effect of metal and acid concentrations in aqueous solutions upon the transfer of tantalum and columbium into selected ketones. The tantalum-columbium oxide mixture used in this investigation was obtained by chemical extraction from Geomines slag. The investigation showed that tantalum 99.4 percent pure and columbium 97.2 percent pure can be produced by the selective transfer of tantalum into diethyl ketone from a solution of 2-N HF and 1-N HC1. The relatively low acid concentration necessary for tantalum transfer and the excellent selectivity of the system recommend its use for the separation of tantalum and columbium.

Jan 1, 1961

By M. M. Jones

A procedure for the spectrophotometric determination of uranium has been developed in support of minerals research being conducted by the Bureau of Mines. Uranium is separated from the sample by tributylphosphate extraction from acid solution containing added aluminum nitrate and (ethylene dinitrilo)-tetraacetic acid solutions. The colored uranium-dibenzoy1methane complex is developed in the organic phase by adding an ethanol solution of dibenzoylmethane buffered with triethanolamine. Absorbance is measured at 410 nanometers, and the response is linear up to at least 100 micrograms U30S in the aqueous aliquot taken for analysis. Aliquots containing as little as 8 micrograms U30S may be analyzed with relative errors no greater than ±5 percent. For aliquots containing at least 35 micrograms U308, relative standard deviation at the 95-percent confidence level is about ±2.2 percent. Appropriate procedures are given for analyzing a wide variety of samples.

Jan 1, 1980

By E. R. Cole

A lead smelting process that appears to present minimal pollution problems has been developed at the Bureau of Mines, Rolla Metallurgy Research Center. Ten and 100 g samples of PbS mill concentrates were vaporized at 1,000° to 1,100° C in a furnace with an inert gas atmosphere during a 2-hour period. The PbS vapor was transported by the inert carrier gas to the reduction zone of the furnace where it was reduced at the same temperature with excess hydrogen to metallic lead. Lead of 99.9 pct purity was produced. The H2S formed can be decomposed into elemental sulfur and water vapor by a modified Claus process. Approximately 90 pet of the Cu and 70 pct of the Ag and Zn remain in the residue and are potentially recoverable. More than 98 pct of the lead in the concentrates was extracted.

Jan 1, 1974

By S. A. Matthes

This Bureau of Mines report describes a system for the dissolution of metal and mineral samples using a microwave heat source. Samples and an acid mixture are placed in sealed polycarbonate vessels. The vessel contents are heated using microwaves, digested for 2 min, and quickly cooled. After the solution is brought to a final volume, the vessel contents are heated an additional 2 min in the microwave oven. Using this method, a slag, a feldspar, and a Ni-Cu alloy were dissolved and analyzed by atomic absorption spectroscopy. Values obtained for Na, K, Cu, Ni, Si, Mg, Mn, Ca, Al, and Fe agreed with certified values and had an average relative standard deviation of 1 pct. This system results in a significant savings in time and expense over traditional methods of sample dissolution, and is ideal for preparing solutions for analysis by atomic absorption, plasma optical emission, or X-ray spectroscopy.

Jan 1, 1983

By John D. Sullivan, Edward P. Barrett

The experimental work on the utilization of tin-plate scrap at the North- west experiment station of the U. S. Pireau of Mines in cooperation with College of Mines, University of Washington, necessitated the selection of a simple method for the determination of tin in the iron produced. Some of the standard methods for the determination of tin which were tried are given below: 1. Dissolving in acids and precipitating the tin as sulphide, igniting and weighing as Sn02. 2. Dissolving in aciis, reducing with nickel, cooling in an atmosphere of carbon dioxide, end titrating with standari iodine solution. 3. Dissolving in acids, precipitating the tin as sulphide, dissolving this sulphide in H3 and H2S04, heating until fumes of 503 are evolved, reducing with nickel or sheet lead, cooling in an atmosphere of carbon dioxide, ani titrating with a standard iodine solution.

Mar 1, 1923

By J. Ankrum, T. Xia1, D. Wilder, K. Spratt

The human lumbar spine is inherently an unstable structure and requires sophisticated neuromuscular control to maintain its stability and for performing physical tasks. As a consequence, it is important to understand the potential health effects on human operators of mechanical stimuli such as shock and vibration.1 Impact applied to a vehicle operator combines the risk of sudden, unexpected load with the mechanical stress of the seated posture.2 Because many work environments contain the potential for multiple, unexpected impacts, it is important to understand how the trunk muscles respond to complex conditions. We believe the results have implications for isolation design and standards development. Methods Muscle activity was recorded during simple and complex impacts, applied randomly and without warning, while subjects sat on an air-suspension truck seat located on a man-rated 6-DOF motion platform (Rexroth-Hydraudyne). Simple (single) impacts consisted of 100 ms quarter-sine jolts in the side-to-side (L and R) and vertical upward (V) directions with peak amplitude at 0.4 g. Complex impacts consisted of combinations of two simple (single) impacts in sequence (LV, RV, VL, VR), separated by 100 ms. Twelve right-handed males (23.7 ± 7.8 years old) were tested without a blindfold under 2 posture conditions (supported while leaning back and unsupported, sitting upright) and 2 seat suspension conditions (present or absent). Each type of impact was repeated three times under each posture and suspension condition, resulting in 84 impacts in total. Surface EMG signals from the left and right erector spinae (ES), rectus abdominis (AR), external obliques (EO) and internal obliques (IO) were recorded and transformed to 25ms RMS values. The response time, defined as the time the muscle activity exceeded the mean + 2 STD of the pre-impact resting period, peak response amplitude, and time were then derived. A mixed-model repeated measures analysis of variance was used to evaluate statistical significance, where type I error rate was set at .05. Results One question we asked of these data was whether there were differences in responses related to simple single strike impacts (L, R, or V) and complex, double-strike impacts (LV, RV, VL, VR). There are 21 possible combinations of comparisons of simple and complex impacts to each other. The differences found are listed in Table 1.

Jan 6, 2006

By A. W. Fahrenwald

"Cooperation was arranged between the mine operators, the Michigan College of Mines and Technology, and the Bureau of Mines for a study of present milling practice in the copper district of Michigan. Work was actively commenced in January, 1928.In Michigan copper occurs almost wholly as native copper. An insignificant amount of copper sulphide is present. The native copper occurs in two general classes of formations--namely, amygdalaid and conglomerate.In respect to ore dressing, the outstanding peculiarities of the two types of copper are: (1) In the amygdaloid, the relative coarseness of the metallic copper, which is almost completely liberated at approximately 48-mesh comminution; (2) the sprangly and flakey physical character of much of the liberated copper after crushing; (3) in the conglomerate, the extremely fine dissemination of the metallic copper, which is not completely liberated by crushing to -200 mesh.Because the study to date has been confined almost wholly to amygdaloid ores, the conglomerate class is not considered herein. The conglomerate ore is being efficiently treated, and the loss of copper is small.The amygdaloid ore contains a silicious gangue of which 80 per cent has a specific gravity of less than 2.84, 92 per cent of less than 2.94, and 98 per cent of less than 3.17. Epidote of 3.25 specific gravity is noticeably present, and accumulates on the table concentrators, from which it is hard to make clean con¬centrate and middling recovery.The general nature of the amygdaloid ores varies a little from mine to mine, but the general characteristics are the same, as is shown later by flotation tests."

Jun 1, 1928

By E. K. Kleespies

The Bureau of Mines determined the kinetics of the reaction of titanium-iron alloys with titanium trichloride dissolved in sodium chloride to provide a basis for understanding the reactions occurring in metallurgical processes involving reduction of the metal halides or alloy refining in fused salts. The rate of the heterogeneous reaction was determined between titanium-iron alloys and titanium trichloride to elucidate the effects of alloy composition on the rate. Measurements were made in an inert atmosphere with a high-temperature thermobalance using high-purity reactants. The rates of the reactions were about 1 x 10-5 g Ti/cm2-sec, and the reaction was phase-boundary controlled. Titanium alloys of the body-centered cubic beta structure reacted faster than those with the hexagonal close-packed alpha structure. The inter-metallic compound, TiFe, reacted very slowly, whereas TiFe2 was inert. Alloys containing above 89 atomic percent iron gained weight by reacting with titanium species in the salt solution and depositing titanium in the alloy. The effect of TiCl3 concentration on the reaction rate was determined from 2 to 12 weight-percent TiC13 and at various alloy compositions. At high iron contents, above 50 atomic percent, the TiC13 concentration effect was small. At lower iron contents, the TiC13 concentration effect was greater for beta-crystalline alloys than for alpha-crystalline alloys. The temperature dependence of the reaction between titanium alloy containing 8.7 atomic percent iron and titanium trichloride was measured over the temperature range 1,062° to 1,220° K, and the energy of activation was 7.7 kilocalories for the reaction.

Jan 1, 1967

By E. J. Gleim

"Information gathered during recent months by field men of the U. S. Bureau of Mines shows that in one State alone there have been 71 fatalities from electrical causes during the last 51/2 years, of which 55 were from contact with mine trolley wires operated at 250 volts or less, direct current. The 1928 law relating to the guarding of trolley wires in the-mines of this particular State reads: ""All trolley wires carrying a voltage of class 2 must be properly shielded except where the same are at least 61/2 feet above top of rail."" Class 2 voltage is defined as being ""between 300 volts and 600 volts direct current, or 240 volts and 480 volts alternating current."" From this it may be inferred that no guards are required, for 250-volt trolley wires, and the natural conclusion to be drawn is that the lack of guards or shields must be held responsible for these fatalities. To prevent fatalities from this source, it has been advocated that every foot of trolley wire in mines should be guarded. While some such drastic step may appear to be amply justified, a closer examination of the records shows that lack of guards is not entirely responsible but rather that carelessness and neglect in the observance of certain well-established simple rules concerning installation and location of trolley wires must also bear a share in the responsibility. In -other words, if trolley wire is installed carelessly and its maintenance neglected, failure may be expected of any guards that have been put up.There are a-number of factors affecting safety as related to trolley wires in mines, among which the following may be enumerated.1. Installation relative to track and passageways.2. Guarding.3. Maintenance.4. Discipline.Acknowledgment is made to D. Harrington and K. L. Marshall of the safety division of the bureau for assistance given in securing data on cost of installing guards for trolley wires.The statement that fatalities should not be charged in every case to lack of guards is supported by the following example: A man operating a locomotive was electrocuted when the trolley wheel jumped the 250-volt trolley wire and allowed it to sag against his shoulder. He was sitting in the regular place provided in the locomotive, but the wire was 11 inches inside of the rail and only 39 inches above it where the wire touched him, or 11 inches from the roof at a distance of 12 feet from the nearest hanger. The accident occurred between two hangers 44 feet apart, and the trolley wire was inside the rail over the entire distance, being 2 inches inside at one hanger and 10 inches inside at the other hanger. A bolt in the roof indicated that there had been a hanger at one time between the two on the 44-foot span.This example is a violation of good practice in the installation and maintenance of trolley wire. In the first place the wire should have been outside instead of inside the rail. In the second place there should have been at least one intermediate hanger so that the span would not be so great and the sag would be reduced. Furthermore, it is possible that the wire was not taut enough even when the intermediate hanger was in place.To provide a degree of safety for men in the mines certain coal-mining States, recognizing the need, have enacted laws to regulate the installation of trolley wires. These limit the distance that the wire must be kept outside and above the rail. Thus, the 1927 mining laws of Ohio specify that:"

Apr 1, 1932

By Hal H. Engel

This publication was written in response to numerous requests for information about the Federal Bureau of Mines' "Demonstrated Lecture on Flame Propagation and Permissible and Explosion-Proof Electrical Equipment." The requests came principally from: (1) Persons wanting to know more about the demonstration before requesting it for groups they represented; (2) persons wishing advance information to help publicize a meeting where the demonstration was to be given; and (3) members of audiences desiring something to help them remember the salient points, facts, and figures presented during the lecture and demonstration. The purpose of the demonstration that accompanies the lecture is to show: (1) Variations in flame speed and pressure at various percentages of flammable gas within the flammable range; (2) effect of flame speed on the "pressure piling" within the area confining the mixture; and (3) the application of flame speed and pressure piling to the combustion of surrounding gas and to the design and maintenance of electrical equipment used in hazardous locations.

Jan 1, 1960

By R. B. Prater

Research by the Bureau of Mines includes efforts to devise means for maximum recovery of critical and strategic metals from primary and secondary domestic resources. As part of that effort, the Bureau developed a hydrometallurgical process to recover Co, Ni, and Cu from Missouri lead-smelter matte. The process includes leaching with H2S04 plus Mn02 as an oxidizing agent, liquor purification, selective precipitation of CuS, (Co,Ni)S, and MnC03, and crystallization of Na2S04&apos; This report is concerned primarily with liquor purification, in which As and Fe are removed from the leach liquor by pH adjustment and filtration. Two variations of the purification step are described. One variation provides liquor containing <1 mg/L As and Fe but requires two solid-liquid separations, The other is achieved with only one solid-liquid separation but leads to a lower degree of purification.

Jan 1, 1987

By Wilbur I. Duvall

This report presents experimental data on the propagation of explosion- generated strain pulses in rock. Tests were performed in 5 different rock types, employing 10 different types of explosives. Charge sizes ranged from 0.5 to 50 pounds, and travel distances ranged from 2.5 to 70 feet. Analysis of the data shows that the experimental peak strain data satisfy an exponential decay propagation law of the form: ?R/W1/3 = Ke ?aR/W1/3. For a particular rock, parameter K is a linear function of the calculated detonation pressure or the calculated energy density of the explosive. For a particular explosive, K is a linear function of the elastic parameter of the rock, p2, a result, which is at variance with elastic theory. The absorption constant, a, is independent of type of explosive but dependent upon rock type. However, no definite relation between a and the physical properties of the rock could be established.

Jan 1, 1959

Occupational illnesses are more difficult to identify than on-the-job injuries. Many illnesses related to occupational exposures may not be diagnosed until years after exposure; by that time, exposed workers may have changed jobs or left the workforce. Other approaches to identifying occupationally related illness are analysis of death certificate data (see chapter 2) and medical examination studies of workers known to have high exposures to hazardous agents. Figures 5-1, 5-3, 5-4, 5-6, 5-8, and 5-10 show, for each commodity, the percent of illness conditions reported to MSHA by nature of condition. Heart attacks that occurred on the job are reported without regard to work-relatedness. Figures 5-2, 5-5, 5-7, 5-9, and 5-11 show rates by year during 1986-1995 for selected conditions. Since there are many limitations on the accuracy of illness reporting, the frequencies and rates shown here should not be considered directly comparable across commodities. Figure 5-12 shows estimates for hearing loss by age among coal miners compared to a nonoccupationally noise-exposed population. These data come from a study by Franks [1996] of a group of audiograms obtained on coal miners by a commercial company. Using the NIOSH definition of hearing impairment, i.e., an average hearing threshold level for both ears that exceeds 25 dB at frequencies of 1,000, 2,000, 3,000 and 4,000 Hz, the figure shows that by age 30, more than 10% of miners suffer hearing impairment; by age 50, 90% of miners have hearing impairment. In contrast, only 10% of the nonoccupationally noise-exposed population suffer hearing impairment at age 51, and 50% of the nonoccupationally exposed population have hearing impairment at age 69. Figure 5-13 shows a similar analysis of commercial audiograms on male metal/nonmetal miners [Franks 1997]. At age 20, approximately 2% have hearing impairment using the NIOSH definition of hearing impairment described above. This increases to 7% at age 30, 25% at age 40, and 49% at age 50. In contrast, only 9% of the nonoccupationally noise-exposed comparison population have hearing impairment at age 50. Franks&apos; analysis showed a different pattern for female metal/nonmetal miners; they developed hearing loss at the same rate as would be expected for a non-noise-exposed female population.

Jan 5, 2000

By R. A. Friedel

Data on compositions of natural substances are important in the study of possible interrelationships. The similarity of the low molecular weight alkane isomers from crude oil and Fischer-Tropsch catalytic synthesis product has been reported (8).3 A similar composition for the alkane isomers from high-temperature coal carbonization has been found. The composition of the C4 to C 7 alkane isomers from these three sources can be calculated quantitatively with the equations previously developed to calculate alkane isomers in Fischer-Tropsch product. An KM sting reversal of the concentrations of the monomethyl isomers from C6(2 Me > 3 Me) to C7 (3 Me > 2 Me) occurs in all three products; fragmentary comparisons at higher carbon numbers indicate some dissimilarities. Naphthene isomers in the C6 to C7 range for crude oil and high-temperature coal carbonization also have similar compositions. Aliphatic hydrocarbons from low-temperature coal carbonization processes are considerably different, consisting mainly of normal alkanes.

Jan 1, 1968

By M. J. Ferrante

Low-temperature heat capacities and high-temperature enthalpies were determined calorimetrically for Na2Cr04, A reversible transition was found at 700° K with an isothermal heat of transition of 2,263 cal/mole. High-temperature X-ray diffraction analysis showed that the transition was a crystal change from the low-temperature orthorhombic form to the high-temperature hexagonal form. At 795° K the hexagonal form had the parameters a, = 5.691 and co = 7.478 A. Powder diffraction data for the high-temperature form are given and possible structures discussed. The melting point was determined to be 1,065° K with a heat of fusion of 5,810 cal/mole. Enthalpy and entropy increments from this investigation were combined with other data from the literature to calculate enthalpies of formation, free energies of formation, and equilibrium constants of formation from 298° to 1,400° K. Equations that represent enthalpies above 298° K are given.

Jan 1, 1972

By M. J. Ferrante

High-temperature enthalpy and X-ray powder diffraction studies were con-ducted on aluminum sulfide (Al2S3) as part of the Bureau of Mines effort to provide new data for the advancement of mineral technology consistent with environmental preservation and energy conservation. Relative enthalpies were measured with a copper-block calorimeter from 298.15 to 879 K. Tabulated values are listed for heat capacity, entropy, Gibbs energy functions, and relative enthalpies between 298.15 and 900 K. Enthalpies were also given in the form of an equation and combined with published data to calculate standard enthalpies of formation and Gibbs energies of formation for reactions of crystalline aluminum with crystalline, liquid, and gaseous diatomic sulfur. The hexagonal, rhombohedral, and cubic phases of Al2S3 were identified by X-ray powder diffraction studies, and the indexed powder diffraction patterns of these phases are given. The hexagonal phase was stable to about 852 K and was partially converted to the rhombohedral form at 879 K.

Jan 1, 1981