Search Documents

Although early Spanish settlers used coal several centuries ago, significant commercial coal mining in New Mexico began in 1861, when the U.S. Army opened a mine to supply Fort Craig. Since then, coal from the state has been used to fuel railroads, lead and copper smelters, and other local industry. In recent years, lower-cost strip mining methods and an increased demand for coal by electric utilities in the Southwest have caused an increase in New Mexico coal production. The coal-bearing regions of New Mexico underlie about 25,000 square miles or20.6 percent of the total area of the state. However, the majority of coal-bearing regions lie under Indian lands that are regulated by the Office of Surface Mining (see Navajo and Hopi data on pages 72-75). Today, most of the coal produced in New Mexico comes from the San Juan Basin in the northwest part of the state and the Raton Area in the north central part. New Mexico's reserves are estimated to be 4.6 billion tons, about one percent of the national reserve. New Mexico's permanent regulatory program was conditionally approved December 3 1, 1980. Its Abandoned Mine Lands Program was approved July 17,198 1.

Jan 1, 1992

By A. C. Richardson, G. D. Coe, B. M. Bird

"The Hull mine of the De'Bardeleben Coal Corporation is located in the Warrior field, in Walker County, Ala., about 25 miles northwest of Birmingham. The Mary Lee bed at this point is coking coal and has been used in the manufacture of by-product coke, but at present it is sold exclusively as a domestic and locomotive fuel.The data in this paper, which is the third in a series on the washability of Alabama coals,5 have been obtained in connection with an exhaustive study of coal preparation in Alabama now being conducted by the U. S. Bureau of Mines and the University of Alabama with the cooperation of the different coal operators. The paper contains screen-sizing and float-and.-sink tests of a representative sample of run-of-mine coal, and flakiness tests and crushing tests of certain sizes.In addition, complete analyses of the ¾-inch to 3/16-inch size, raw coal, together with ash fusibility tests of the float-and-sink fractions have been made; those results are given in Tables 1 and 2. Since they indicate that the pr ration problem, like that at Lewisburg, Ala., is one of ash reduction, the further tests and the discussion have been restricted to that subject."

Apr 1, 1931

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 L. H. Adami

Heats of formation were obtained for four anhydrous crystalline sodium borates by hydrochloric acid solution calorimetry. The heats of formation at 298.15° K from the elements are NAB02, -233.2 ±0.6 kcal/mole; Na2B07, -786.4 ±1.0 kcal/mole; NaB305, -549.9 ±0.8 kcal/mole; and Na2B6013, -1,412.5 ±2.0 kcal/mole, The heats of formation from the constituent oxides are NaB02, -31.5 ±0.8 kcal/mole; Na2B407, -78.8 ±1.3 kcal/mole; NaB305, -44.1 ±0.8 kcal/mole; and Na2B8013, -96.7 ±1.5 kcal/mole.

Jan 1, 1968

By Walter L. Finlay

The Bureau of Mines has developed prototype instruments promising to improve the ability to warn of imminent roof falls. An unusually good opportunity to test these comparatively under natural caving conditions was afforded by the forecasted caving in August 1977 of a mined-out region of the White Pine Mine. The latter's rock strata closely resemble those in many coal mines. The anticipated cave was of the competent-roof/weak-pillar type. It occurred as, and when, predicted. Automated convergence and bed separation gages agreed well with the standard manual convergence gage measurements. A micro seismic gage was found to be insensitive to the fall and may require different test conditions for effectiveness. A roof resistivity unit was tested under a separate Bureau of Mines contract. (No. H02720J7). An unplanned addition showed interesting potential.

Jan 1, 1978

By L. A. Haas

A kinetic study of the carbon deposition reaction was undertaken by the Bureau of Mines as part of a broad investigation of metallurgical reactions in the iron ore blast furnace. The disproportionation of carbon monoxide on iron pellets was investigated at carbon monoxide pressures between 0.5 and 2 atmospheres (absolute) and temperatures from 400° to 1,075° C. Gas flow in the range from 0.25 to 0.85 standard liter per minute was found to have little effect on the reaction velocity. The addition of nitrogen and helium to caron monoxide exerted only a dilution effect on the rate of carbon deposition. However, an addition of 1 percent hydrogen increased the rate about 100 times. Small amounts of carbon dioxide in the inlet gas exerted little effect on the rate of carbon deposition. The maximum rate for carbon deposition in the first 2 hours occurred at 550° C. The apparent molar activation energies at various stages of the reaction were found to vary from 13 kcal initially to 36 kcal during the latter stages of the reaction. The reaction rate behavior was tentatively explained by an adsorption step followed by the diffusion of iron through a shell of inactive iron carbide.

Jan 1, 1968

By N. S. Dalal, Xianglin Shi

"The mechanism of vanadium(V) V ) toxicity is still not fully understood in spite of extensive current effort (1-3). The presence of a vanadium(V) V ) -dependent NAD ( P )H oxidase in cell membranes suggests that at least one of the pathways involves oxidation of NAD(P)H (1-3). Considerable effort has therefore been devoted to finding the mechanism of NAD ( P ) H-oxidation by va¬nadium( V ) (1-19). Recently Liochev and Fridovich (4, 16) provided a critical review of vanadium( V) -stimulated NAD (P )H oxidation by plasma membranes. They out¬lined a mechanism in which vanadium(V) V )-stimulated oxidation of NAD ( P )H by biomembranes involves an O2 - initiated free radical chain reaction (4 ). While the above may be the major pathway for the vanadium-me¬diated NAD (P )H oxidation in membrane-related sys¬tems, some recent results suggest that in the presence of NADPH the flavoenzyme glutathione reductase can function as a vanadium(V) V ) reductase (18). Because of the significance of this result in relationship to the mech¬anism of vanadium( V) metabolism and the novelty of the metal-reductase behavior of a flavoenzyme, we have car¬ried out additional studies on one-electron reduction of vanadium( V) by two other, related flavoenzymes: lipoyl dehydrogenase and ferredoxin-NADPH oxidoreductase. These two enzymes were selected because they are known to catalyze a one-electron reduction of Cr ( VI ) (19-21 ), which is isoelectronic with vanadium( V ).The present study also reports on the generation of hydroxyl ( • OH) radicals in the vanadium( V) -flavoen-zyme redox system without exogenous H2O2. The • OH study was undertaken because • OH radicals are known to be generated in reactions of vanadium( IV) with H2O2 (17,18,22-27). For example, Piette and co-workers (17, 22) have studied effects of vanadium(IV) IV ) on lipid per-oxidation and NADPH oxidation and suggested that va-nadium( IV) -induced • OH radical formation may play an important role in vanadium( V) toxicity. Carmichael (25, 26) investigated the reaction between a RNA /VO 2' complex and H2O2 with a view to probe the possible re-lationship between vanadium( IV) -mediated • OH radical generation and DNA damage. He has suggested that in this reaction the • OH radical adds to the C (5) carbon of uracil, causing nucleotide damage, similar to what occurs in the nucleotide /Fe2+ / H2O2 reaction (28) and in y-irradiated aqueous solutions of nucleic acids (29 ). To our knowledge, however, there is as yet no report on ·OH radical generation in any reaction involving the reduction of vanadium ( V) by a well-characterized enzyme, without exogenous H20 2 • The present study provides evidence that ·OH radicals can form in a flavoenzyme-mediated reduction of vanadium( V) to vanadium( IV) and that this process involves also the reduction of molecular oxygen ( 0 2 ) to H20 2 • The H20 2 thus generated reacts with vanadium( IV) to produce ·OH radical, in analogy with the Fenton reaction ( Fe2 + + H20 2 - Fe3 + + OH- + ·OH)."

Mar 1, 1992

By L. A. Haas

In this Bureau of Mines investigation, conditions were determined to form an iron sulfide adherent coating with a metallic golden luster on steel upon anaerobic heat treatment with sulfur. The sulfide formation rate was determined in the temperature range of 105° to 500° C with reaction times up to 68 hours. The optimum temperature and time to form an adhering decorative coating on mild steel was in the range of 105° C for about 70 hours to 285° C for 1 hour. The golden coating consisted of an inner layer of pyrrhotite and an outer layer of pyrite. At temperatures higher than about 300° C, the outer layer thickness decreased owing to the decomposition of pyrite to pyrrhotite.. Small quantities (<0.5 wt-pct) of petroleum oil accelerated the sulfide growth rate. The sulfide coating decreased the corrosion rate of steel in a neutral aqueous medium by a factor of two. The dissolution of pyrite in water was dependent on particle size and surface area with the flat pyrite coatings exhibiting the lowest dissolution rate.

Jan 1, 1974

To improve a miner&apos;s chance of survival during an emergency by providing immediately avail-able breathable air and protection from toxic gases until a longer-duration breathing apparatus, stored nearby, can be reached. Approach: A belt-carried apparatus which can provide a closed-circuit atmosphere for ten minutes breathing has been developed under a Bureau of Mines contract. How It Works: Water vapor and carbon dioxide in the user&apos;s exhaled breath are removed, and oxygen is supplied, by chemical reactions. When the user exhales into the mouthpiece, water vapor in his breath reacts with potassium superoxide (KO2) stored In the canister to produce oxygen. The other product of this reaction (KOH) reacts with carbon dioxide and removes it from the air. The oxygen-enriched air then flows from the canister into two breathing bags. When user inhales through the mouth, that air is drawn out of the bags, makes a second pass through the chemical-containing canister, and flows into the mouthpiece tube. A nose clip is worn to seal off the nasal passages.

Jan 1, 1975

By W. R. Reed, J. A. Organiscak

Surface mining operations use large off-road haul trucks extensively to move material at mining properties. Past research, using the United States Environmental Protection Agency’s (EPA) emissions factors for unpaved haul roads, has shown that haul trucks generate the majority of dust emissions from surface mining sites, accounting for approximately 78%-97% of total dust emissions. Observations of dust emissions from haul trucks show that if the dust emissions are uncontrolled, they can be a safety hazard by impairing the operator’s visibility. This increases the probability for haul truck accidents (See photos above). However, the greatest long-term health hazard of dust generated from hauling operations is due to inhalation of the respirable dust [median diameter <4 micrometers (µm)] and tho­racic dust, which is equivalent to the EPA’s definition of PM10 [particulate matter with a median diameter <10 µm]. Exposure to respirable dust has long been considered a health hazard at surface mining operations, especially if silica dust is present. There are two legislative acts that regulate the air quality for mining operations: the Federal Coal Mine Health and Safety Act of 1969 and the Clean Air Act of 1970. The Federal Coal Mine Health and Safety Act of 1969 established the limits for dust in the work place for health and safety pur­poses. The Clean Air Act of 1970 regulates air emissions from facilities from an envi­ronmental perspective.

The Bureau of Mines conducted large-scale laboratory copper ore leaching tests to enable improving copper recovery from large dump-leaching operations. This was done by comparing leaching progress when copper was recovered from recycled leach liquor either by cementation or by solvent extraction. Copper was leached from 7-ton ore samples at room temperature using pH 2 ferric sulfate solutions. With are samples containing 11 percent minus 0.5-inch fines, no marked advantage in using either of the copper recovery methods was evident after 416 days of leaching. With ore containing 32 percent minus 0.5-inch fines, solvent extraction of copper was advantageous in that 60 percent of the copper was extracted after 568 days, whereas only 48 percent of the copper was extracted when cementation was used. Less acid was consumed during leaching when solvent extraction, rather than cementation, was used for copper recovery. Iron, contributed by cementation with scrap iron, plugged the ore bed containing 32 percent fines.

Jan 1, 1981

By W. F. Marshall

The Bureau of Mines conducted a series of experiments to determine the influence of exhaust rebreathing on emissions from various gasoline and diesel engines. Tests were conducted that simulated operation of engines in nonventilated spaces as well as in spaces with partially restricted ventilation. Results of these tests showed that exhaust rebreathing can have a marked effect on exhaust emissions and thus on the composition of the air in the working space. For the case of restricted ventilation, unacceptably high (greater than 50 ppm) levels of CO in the air of the working space resulted from exhaust rebreathing rates as low as 8 pct exhaust in the engine&apos;s intake. Operation in a nonventilated space resulted in highly critical CO levels (fatal in a few minutes) at times corresponding to 1 to 3 pounds of fuel consumed per 1,000 cu ft of space. Tests involving spaces of various sizes showed that volume of the air space [per se] is not important--the primary variable is fuel consumed per unit volume of air space.

Jan 1, 1973

By Susanne Hering, Brent Kirby, Charles D. Litton, Tracy Allen, Kirk R. Smith, Rufus Edwards

In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 µm) and fine (mass median diameter, 0.27-0.42 µm) size distributions (average r2 = 0.997 ± 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries.

By James H. Aase

Shales from 10 locations in Michigan were sampled, tested, and evaluated to determine their suitability as raw materials for producing lightweight aggregate by rotary-kiln methods. Sampling procedures and the geology of the shale units tested are discussed. Preliminary testing in a muffle furnace preceded extensive testing in a l6-inch by 14-foot rotary-kiln. Rotary-kiln products from these shales ranged in weight from 35.5 to 61.2 pounds per cubic foot (pcf). Concrete test specimens made pith selected aggregates were evaluated to determine the qualities of the concrete. Compressive strengths of the concrete ranged from 2,830 to 4,240 psi after 28 days of curing. Unit weight of the concrete ranged from 94.8 to 101.5 pcf. Lightweight aggregate suitable for use in structural concrete meeting ASTM standards was produced by the rotary-kiln method using shale samples from two locations.

Jan 1, 1967

As longwall shields are lowered in preparation for advance, dust from the canopy falls directly into the air stream with the potential of becoming entrained. Historical dust sampling data from the early 1980s shows that shield advance contributed an average of 12 percent to the airborne respirable dust levels found on longwalls in the United States. Data from the 1990s indicates that shield dust liberation had increased to an average of 23 percent. Increased longwall production levels over this time resulted in the need to move a larger number of shields during each shift, while an increase in air velocities on the face was also occurring. These factors combine to suggest that greater quantities of shield dust are being entrained into the face air. A series of controlled laboratory tests were conducted in a test stand simulating shield dust entrainment to evaluate changes in airborne respirable dust levels at different air velocities. Significant differences in respirable dust entrainment were observed. The test facility, test methodology, and dust sampling results will be reviewed and discussed

By J. C. Duchon

The U.S. Bureau of Mines is conducting human factors research for the purpose of reducing accidents and improving the person-machine interface found in surface and underground mining operations. Miners are exposed to a variety of environmental stressors, e.g., extreme heat, noise, vibration, and adverse illumination, throughout the workday. Exposure to these environmental stressors has been noted in the literature to affect performance on vigilance tasks. Since impaired performance at vigilance tasks can lead to industrial accidents, further investigation of the effects of environmental stressors on human performance is warranted. A brief description of the environmental conditions present in the mining workplace is followed by a review of experiments dealing with the effects of environmental stressors on vigilance task performance. The applicability of past research to actual mining operations is considered.

Jan 1, 1989

By C. P. Bowie

The Bureau of Mines has been conducting investigations with the view of determining the types of containers best adapted to the stor- age of oil. These investigations have shown that tanks composed wholly of steel give the best results. Where larger containers than it is feasible to build with steel are desired, concrete-lined reservoirs can be recommended for some grades of oil. Practically all such containers in use at present have wooden roofs and this type of construction is here described, although it is the belief of the writer that concrete roofs would be far more satisfactory in every way, and that the difference in cost between a concrete and a wooden roof would, as a rule, in a few years' time, be offset by a saving of oil and in cost of repairs and renewals.

Jan 1, 1918

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. C. Franklin

A data-acquisition system was designed by the Bureau of Mines to monitor five detectors with radon continuously flowing through each. These detectors could be monitored up to 12 times an hour, but were only monitored according to a preset time, thus allowing radon to be monitored continuously in a uranium mine. The counter can be set to monitor each detector for any period of time up to 16.5 minutes. This allows very low concentrations to be monitored longer to reduce statistical error. There would be no upper limit in radon concentration that could be monitored, but there would be a lower limit of 50 picocuries per liter (pCi/l). Each detector was cylibrated in the laboratory by the Lucas flask method. Multiple samples were taken at two different concentrations, and the correction factor for each detector was determined by a least squares fit of the data. To verify the calibrations, a series of measurements at several concentrations were made against a constant source. Our agreement at low radon concentrations (300 pCi/i) with the two-filter method as within 3 percent; thus, the total error would be this difference plus the two-filter error. At high concentrations the coefficient of variation ranged between 2.1 and 9.8 percent for the five different detector units.

Jan 1, 1976

The current procedure for measuring the concentration of respirable coal mine dust is as follows. Each filter is preweighed by the filter manufacturer to ±0.1 mg. Following sampling with the Coal Mine Dust Personal Sample Unit (CPSU) at 2.0 L/min, the filter with coal mine dust is sent to MSHA for weighing. The current MSHA procedure for weighing respirable dust samples uses a Mettler Model AE163 analytical balance in conjunction with an automatic weighing system with a precision of ±0.02 mg [Tomb 19901. Each balance is calibrated twice per day. Quality control for the automatic weighing system includes the systematic weighing of one in eight filters on a second Mettler AE163 balance. Tolerance is set at ±0.1 mg between the two weighings of the same sample. Weights are truncated at the 0.1 mg level (e.g., 3.457 mg is truncated to 3.4 mg) [Bowman et al. 19851. The difference of the two truncated weights is then recorded as the weight of coal dust deposited. The respirable concentration (mg/m3) is computed by multiplying by a correction equal to 1.38 and dividing by the volume of air sampled (2.0 L/min x sampling time [min]).

Jan 1, 1997