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By L. B. Pankratz

Enthalpies above 298° K were determined for AgCl to 1,400° K and for AgBr to 1,200° K by copper-block calorimetry. Before melting, both compounds showed an anomalous increase in enthalpy, an effect associated with lattice defect formation. Melting points and heats of fusion were determined to be AgCl, 730° K and 2,945 cal/mole; AgBr, 700° K and 2,030 cal/mole. The heat capacity of both melted substances decreased with increasing temperature over the entire liquid ranges investigated. Enthalpies above 298° K were tabulated at even temperatures along with derived entropy increments and heat capacity values. The results were combined with the known heats of formation and entropies at 29.8.15° K to obtain values of the heats and free energies of formation over the range 298.15° to 1,400° K for AgC1 and 298.15° to 1,200° K for AgBr.

Jan 1, 1970

By W. R. McDonald

The Bureau of Mines, U.S. Department of the Interior, conducted small-scale field tests on acidic copper tailings as part of its effort to develop, improve, and demonstrate technology for stabilizing mining and mineral-processing wastes. Two successful demonstration revegetation plots were established on an abandoned copper-tailings pond located on public land adjacent to Holden Village, Wash. The tailings were neutralized with treatments of either dolomitic lime or limerock and fertilized with processed sewage sludge and/or commercial fertilizer. Excellent plant growths covering 70 and 24 percent of the surface were achieved on 1/8-and 1-1/2-acre test plots planted in 1973 and 1974, respectively. Regar brame, Tegmar intermediate wheatgrass, and tall wheatgrass provided the best plant growth and surface coverage. The target pH of tailings neutralization was 6.8; however, good plant growth occurred in areas where the soil pH ranged from 2.9 to 5.8.

Jan 1, 1978

By J. P. Hansen

Wustite beds were reduced with carbon monoxide and mixtures of hydrogen and nitrogen in the temperature range 900° to 1,300° C to determine the effect of temperature, gas flow, and surface area on the rate of reduction to iron. The composition of the gas stream as it passed through the wustite bed was continuously measured with infrared absorption cells and heated-wire methods. The change in composition was used to calculate the reaction rates. Arrhenius plots of the data give heats of activation of 34 kcal for particles using CO, 27 kcal for particles using H2, 24 kcal for pellets using C8, and 6 kcal for pellets using H2. The velocity of reduction is dependent on the area of reacting interface and the driving potential of the gas (reducing gas concentration minus equilibrium concentration) as well as the exponential temperature effect. The reaction rate was independent of the gas velocity over the range of conditions studied.

Jan 1, 1965

In this U.S. Bureau of Mines report, proposed narrow-vein and longwall mining concepts using drill-split technology (described in part 1 of this series) and in situ liner concepts (described in part 2 of the series) are combined and applied conceptually to environmental problems. Proposed applications deal with (1) acid mine drainage (AMD), (2) solid waste disposal, (3) site remediation, and (4) pollution prevention through innovative industrial design. For control of AMD from abandoned hillside mine workings, it is proposed that source veins be re-mined, processed for residual values, then backfilled using an impermeable compound backfill mix. For solid waste disposal, "vertical landfills" are proposed, consisting of trash-backfilled underground rock quarries. Vertical landfill activities take place in in situ lined containments that geohydrologically isolate the mining-backfilling activities. Site remediation through the creation of in situ underliners, for the capture of toxic leachates, and pollution prevention through the underground storage of toxic, flammable, and explosive materials in in situ containments, are proposed.

Jan 1, 1995

By J. W. Town

Studies were made by the Bureau of Mines to determine the influence of textural features on the beneficiation of phosphate minerals (pellets) from selected bed and composite samples representing different rock types of the Western Phosphoria Formation. The particle size of the samples was reduced by attrition grinding to minus 20-, 28-, or 48-mesh depending on ore grade and gangue matrix. Sizing of the ground material showed that the phosphate pellets would concentrate in the plus 200-, 270-, or 325-mesh size fractions sufficiently so that the phosphate content was above the 31.5 :cent P2O5 required for acidulation. The phosphate content of essentially pure phosphate pellets was shown to range from 33 to 39 percent P2O5. Microscopic identification of the particles in each size fraction showed that the phosphate was either in the pellet form and readily liberated or so intimately associated with the gangue matrix that size reduction necessary Co obtain liberation was impractical.

Jan 1, 1967

By D. E. Shanks

As part of its effort to produce cell-grade alumina from clay, the Bureau of Mines investigated the hydrogen chloride gas-sparging crystallization of aluminum chloride hexahydrate (ACH) from aluminum chloride liquor, to provide information for optimizing the crystallization operation. Four parameters important in controlling the crystallization of the aluminum chloride hexahydrate and the concentration of impurities, particularly phosphorus and magnesium, in ACH crystals are (1) aluminum chloride concentration in the feed solution to crystallization, (2) hydrogen chloride gas flow rate, (3) temperature, and (4) concentration of phosphorus and magnesium also in the feed solution. Parameters 1, 2, and 3 affect crystal formation. The combined effects are very important because the phosphorus and magnesium concentrate in the crystals during the early stages of crystal growth. Aluminum chloride hexahydrate of cell-grade purity was crystallized from saturated aluminum chloride solutions containing less than 0.003 wt-pct P205 and 0.010 wt-pct MgO. Crystallization temperatures less than 600 C decreased crystal purity.

Jan 1, 1981

By J. A. Eisele, D. J. Bauer, D. E. Shanks

As part of its effort to produce cell - grade alumina from clay , the Bureau of Mines investigated the hydrogen chloride gas - sparging crystallization of aluminum chloride hexahydrate ( ACH ) from aluminum chloride liquor , to provide information for optimizing the crystallization operation . Four parameters important in controlling the crystallization of the aluminum chloride hexahydrate and the concentration of impurities , particularly phosphorus and magnesium , in ACH crystals are ( 1 ) aluminum chloride concentration in the feed solution to crystallization , ( 2 ) hydrogen chloride gas flow rate , ( 3 ) temperature , and ( 4 ) concentration of phosphorus and magnesium also in the feed solution . Parameters 1 , 2 , and 3 affect crystal formation . The combined effects are very important because the phosphorus and magnesium concentrate in the crystals during the early stages of crystal growth . Aluminum chloride hexahydrate of cell -grade purity was crystallized from saturated aluminum chloride solutions containing less than 0.003 wt - pct P205 and 0.010 wt - pct Mg0 . Crystallization temperatures less than 60° C decreased crystal purity .

Jan 1, 1965

By Danny A. Riley, James R. Sanger, Hani S. Matloub, Michael Agresti, David Rowe, Lin-Ling Zhang, Yuhui Yan, Paula Galaviz, Judith Marchant-Hanson, Ji-Geng Yan

Until now there has been controversy about which tests should be performed to diagnose early Hand-Arm Vibration Syndrome (HAVS). Initial screening questions, especially about tingling and numbness, routinely given to patients prior to examinations proved to be a very important tool in the diagnostic process1, 4. However, standardized tests that are simple, quick, valid and reliable are needed to support a diagnosis of HAVS. Purpose: To find the most valid and reliable tests to diagnose HAVS. Material and Methods Five major tests were performed on Group I and Group II. Group I: Control group of 12 volunteers including students, nurses, secretaries and physicians with no history of using vibrating tools (age 20 to 50y, mean age 38.5y; 5male, 5 female.) Group II: 12 workers (age 17 to 65y, mean age 39y; 9 male, 3 female) were sent by a local trade union with a history of using vibrating power tools on their jobs for varying amounts of time (mean 12.2y, from 0.5 to 35y.) Pre-enrollment survey showed that each had more than 4 complaints commonly associated with use of vibrating tools (including numbness, tingling, weakness, pain, finger color or nail changes, temperature change, and difficulty moving.) 1. Sensory nerve conductive tests: Amplitude and nerve conductive velocity (NCV) were evaluated. 2. Cold Stress-Temperature recovery time tests were done on the index finger of the dominant hand following these steps: Confirm water bath is within 4-5º C. Place the finger temperature probe on pad of the index finger of the dominant hand. Record temperature every 15 seconds. Place subject’s hand in the cold- water bath for exactly five minutes. Record temperature every 15 seconds for ten minutes. 3. Blood test: Venous blood was taken by a 21-gauge needle with the yellow collection tube adapter. S-ICAM, Sera Thrombomodulin, Norepinephrine levels were evaluated by Henderson Research Centre, Canada. 4. Finger Sensory Evaluation: Semmes-Weinstein monofilament test and 2-point discrimination tests were performed on bilateral fingers. 5. Digital blood pressure test: blood pressure was measured in bilateral index fingers. Results 1. Median nerve sensory conductive amplitude from palm to wrist : GI: mean 96 ± 31µm; GII: mean 43± 30µm; for dominant hands. GI vs GII: P<0.001

Jan 6, 2006

By William T. Reid

Low-temperature carbonization of coal in Japan served as an important source of liquid fuels during the war. Six plants operating in Japan Proper produced 203,069 KL (53.7 million gallons) of liquid fuel from 1940 until the end of the war in August 1945, while four additional plants in Karafuto and Korea produced 211,943 KL (56.0 million gallons) for a total of 415,012 KL (109.7 million gallons) of liquid products. Semicoke produced in these plants was used for domestic fuel, for gasi- fication in portable gas producers on automotive vehicles, and to replace imported low-volatile bituminous coal in the manufacture of metallurgical coke. Since 1936 one plant had produced more than 300,000 metric tons of semicoke for blending with bituminous coal to form coke, while the total production of semicoke since the beginning of the industry in 1923 is approxi- mately 2,000,000 metric tons. Despite an apparent annual carbonizing capacity of about 2,000,000 metric tons of coal for the entire country, the maximum amount of scmicoke produced during the peak year, 1943, was 468,446 metric tons. The equipment used is primarily of Gorman design. Just before the end of the war, 6 plants using 20 Lurgi carbonizers were operating with a total rated capacity of more than 1,500,000 metric tons of coal per year, while 2 Koppors units had a combined annual rated capacity of 400,000 metric tons of coal. One plant using the Japanese-designed Mimura system was in service but with so much mechanical trouble that its output was small, while in another plant 4 Wanisht carbonizers of Japanese design but based on an early German development were running satisfactorily, and carbonizing about 100,000 metric tons of coal per year. A single installation of 15 American-designed Knowles ovens was operating near Tokyo but was carbonizing pitch for electrode carbon. ..! No true low-temperature process used in Japan could carbonize strongly. caking coals satisfactorily. The Mimura process designed for this purpose was unsuccessful, as was the Shimomura process before it, while the Lurgi, Koppers, and Wanishi systems operated only with noncaking or very weakly caking coals. The Knowles ovens, really a medium-temperature process, could carbonize-caking coal without difficulty...

Feb 1, 1948

By E. A. Mihok

A pilot plant for treating mine drainage by neutralization with limestone was designed, fabricated, and operated by the Bureau of Mines. The process consists of (1) producing a very fine (minus 400-mesh) limestone slurry, (2) mixing the slurry with the mine water, (3) aerating the resulting mixture to remove carbon dioxide and precipitate iron, and (4) separating the solids from the liquid by sedimentation. A mine discharge of pH 2.8, containing 1,700 ppm total acidity, 36 ppm ferrous iron, and 360 ppm total iron, was treated at rates from 300 to 400 gpm. The treated water ultimately reached a pH of 7.4 and contained no detectable iron. The resulting sludge compacted to approximately one-third the volume of sludge from mine water neutralized with lime. The advantages of the limestone process, compared with the conventional lime process are as follows: Widespread distribution and lower cost of run-of-mine, indigenous limestone; simplicity of plant design; reduced hazards and plant operating and maintenance costs accruing from the use of a less reactive chemical agent; higher solids concentration of the precipitated sludge; and no deleterious effect caused by accidental overtreatment. While total process costs could not be determined, it is conservatively estimated that the cost of treating mine water by the limestone process is one-third to one-half the cost of the lime process, depending on the characteristics of the water to be treated and the availability and quality of limestone used.

Jan 1, 1968

By D. Harrington

Every few weeks United States newspapers of 25 or 30 years age ran scare-heads telling of some mine disaster, which was a first-page attraction for a day or two and then was forgotton until another disaster occurred a few weeks later. Interspersed with these disasters were the so-called sniping mine accidents, causing the death of one or two mine workers. The summation of all types of mine fatalities usually exceeded 3,000 a year. In the period 1906-10, inclusive, there wore 84 major explosion disasters (or about 17 per year) in united States coal mines; the fatalities resulting from those disasters numbered 2,388 for the 5-year period. These frightful catastrophies helped to cause the total number of fatalities in our coal mines for the 5 years (including the fatalities from major explosions) to reach the enormous total of 13,288, an average of 2,658 per year. In addition, some hundreds of other typos of mining accidents swelled the annual fatality list to upwards of 3,000. This admittedly deplorable condition created so much Nation-wide comment that Congress was impressed with the necessity of having something done by the Federal Government with a view to trying to halt at least sonic of the excessive loss of life in our mines; in consequence, the Bureau of Mines was created and began to function in July 1910.

Jan 1, 1935

By A. Tewarson

Combustibility data are presented for 14 samples representing commonly used mine materials (treated and untreated wood, conveyor belt and brattice cloth). The combustibility data were obtained in the Factory Mutual Small-Scale Combustibility Apparatus (sample area -0.008 m ). The hazards associated with the mine materials were evaluated in terms of: 1) ignition/ surface flame spread using an ignition parameter (IP). A reasonable correlation was found between IP values and U.S. Bureau of Mines ratings for conveyor belts and brattice cloth and large-scale fire test data for treated and untreated timber sets; 2) generation of combustible vapors, using a vapor generation parameter (VP); 3) heat release using a heat generation parameter (HP). A reasonable correlation was found between HP values and the large-scale fire test data for treated and untreated timber sets; 4) generation of "smoke," toxic and corrosive products using a chemical compound generation parameter (CP); and 5) light obscuration by "smoke" using the light obscuration parameter (LP). All the wood treatments, except Fireguard, were found to be effective in reducing the fire hazard. The effectiveness of the treatment appears to be due to enhancement of carbon formation in the solid phase and enhancement of water formation in the vapor phase. Concepts are presented for establishing 1) the relationship between various parameters (IP, VP, HP, CP, and LP) and basic properties of materials, and 2) the usefulness of the parameters as criteria for the combustibility and fire hazard evaluations of the mine materials.

Jan 1, 1982

By Roy F. Abernethy

This publication by the Federal Bureau of Mines contains the free-swelling indexes for 2,812 samples of coal received from January 26, 1948, to July 15, 1957, and the Hardgrove grindability indexes for 2,339 samples of coal received from June 23, 1947, to July 15, 1957. These data consist of the origin of the sample, bed name, and analysis. Summaries show the high, low, and average values for each bed. The free-swelling index is a relative measure of the caking properties of a coal when burned on a grate, and the Hardgrove grindability index is used to estimate the relative ease of grinding coals. Development and standardization of these test procedures were at a much later date than those for the more familiar tests, such as proximate and ultimate analyses and calorific value determinations. The newer tests are valuable in supplying supplemental information, particularly for assisting in evaluating coals used in certain types of combustion processes.4/ Data from such tests are important to designers of burning equipment, operating engineers, and purchasing agents. Data from these newer tests are scarce and scattered through a number of publications. Special projects were started to determine the free-swelling and grindability indexes, in addition to the regular analyses on the tipple samples collected by Bureau engineers. Since the start of these special projects, all the coal fields of commercial importance have been adequately covered in the sampling program.

Jan 1, 1961

By K. C. Dean

During the course of the investigation of manganese mineral occurrences in the western United States, the Bureau of Mines collected several lots of ore&apos; from properties in the vicinity of Winkelman, Ariz. As none of the ores would be marketable directly, an investigation was made to determine their amenability to concentration by ore dressing. The Geronimo group of claims is in Pinal County, 8 miles west of Winkelman, Ariz. The manganese oxides occur as cementing material in ore zones of conglomerate. Representative samples of a 2-ton lot of ore cut from outcrops of two lenticular deposits were laboratory-tested. Two 1-ton samples from the Benningfield property were similar in physical characteristics but differed in grade. This claim is 11-1/2 miles south of Winkelman and about 1 mile west of the San Pedro River on the south side of Putman, Wash. The manganese minerals occurred as nodules and lenses, replacing limestone, in a capping over a dark, igneous dike. The North Star group consists of five claims on the west side of the San Pedro River 14 miles south of Winkelman. The ore consists of a low-grade, manganese oxide-calcite occurrence interspersed with stringers of higher-grade material and is present as filling in a fissure zone in porphyry. Two samples were obtained by the examining engineer; one sample represented run-of-mine material, the other represented ore from the vein that could be hand-sorted or selectively mined.

Jan 1, 1952

By A. J. Barry

An apparatus and procedure have been developed for testing the anchorage effectiveness of slotted-type bolts. The apparatus consists of: (1) A hydrualic Jack assembly for loading the bolt and (2) a device (extensometer or cathetometer) for measuring displacement of the bolt as it is loaded. This apparatus and procedure permit measurment of anchor slip for loads up to the yield load of the bolt. Two representative makes of slotted-type bolts (a total of 94 bolts) were tested in typical sandstone and shale mine roof. Analysis of the test results showed that (1) anchorage capacities up to the yield load of the bolts can be developed in either rock type; (2) the shape of the slotted end of the bolt affects the ease with which the bolt can be driven; (3) all bolts for which the driving distance was more than 1.25 inches produced satisfactory anchorage in both rock types (thus, driving distance can be used as a criterion for satisfactory anchorage); (4) for the group of bolts that was satisfactorily anchored the anchor slip was unaffected by the type of bolt but was considerably larger in shale than in sandstone; and (5) the bolt expansion, that is, the amount the wedge expands the prongs in excess of the diameter of the hole, can also be employed as a criterion for satisfactory anchorage. Although the bolt-expansion and driving-distance results do not differ appreciably, the latter is recommended because it is easier to determine.

Jan 1, 1954

By Robert A. Jankowski

"Following passage of the Coal Mine Health and Safety Act of 1969 (Public Law 911173), the Bureau of Mines initiated a research program aimed at controlling respirable dust exposures of coal mine workers. Respirable dust is the dust that gets into, and interacts with, the lungs of those who inhale it. It has long been recognized as a severe health hazard to mine workers. This program has been implemented by a team effort consisting of the Bureau's in-house capabilities, the Generic Center for Respirable Dust, and contractors, as necessary. Over the years, Bureau research has addressed principally three areas:o Compliance with the Federal 2.0 mg/m3 dust standard (1970-76).o Dust control for longwall mining (1976-1983).o More stringent respirable dust standards due to quartz dust (1983-1987).In addition, fundamental studies have been conducted by the Generic Center for Respirable Dust, with emphasis on penetration of dust into the lung. Accomplishments have been significant, but problems remain, as noted later.The Coal Mine Health and Safety Act of 1969, established a 2.0 mg/m3 dust standard for all coal mining operations, underground as well as surface. At the time of enactment of this legislation, the industry was averaging approximately 4.0 mg/m3. The Bureau of Mines respirable dust research program played a significant role in identifying and developing effective technology to allow better compliance with this new standard, thanks to industry implementation and Federal enforcement."

Nov 1, 1988

By Richard A. Thomas, Charles D. Litton, Kenneth E. Mura, Harry C. Verakis

Experiments were undertaken to evaluate the flammability of typical noise abatement materials used to line the cab interior of mobile mining equipment. The experiments were conducted using three different experimental configurations: 1. A ventilated tunnel test. 2. A full-size cab test where the interior surfaces were lined with the sample material and then ignited near the floor using a methane-air burner. 3. Standard ASTM E-162 tests using a radiant panel test apparatus. This paper describes the tests and presents the results obtained for 15 to 20 different materials of various chemical compositions and thickness. With one exception, materials that did not exhibit flame spread in the tunnel test also performed well in the full-scale cab test. All materials that had passed only a small-scale flammability test, such as SAE J369, failed dramatically in all three of the above test configurations. With one exception, all materials that performed well in the full-scale cab test had flame spread indices < 25, based upon the ASTM E-162 results. The lone exception had an ASTM E-162 flame spread index of 68. With regard to samples that failed the full-scale cab test, the carbon monoxide levels within the cab reached lethal concentrations in the range of 1.8% to 3.8% within 2 minutes from ignition of the sample—dramatically illustrating the severe fire environment that can result within the cab space.

By Potts J. D.

Installation of a horizontal air-blocking shelf around the inside perimeter of the surface mining drill deck shroud is proposed to improve dust capture. Without the use of this shelf, a strong Coand? effect airflow pattern results in dust leakage to the environment, especially at the shroud-to-ground interface. Bailing air exits the drill hole and travels along the drill steel to the underside of the table, where it fans out across the bottom of the drill table and continues down the sides of the shroud. This dust-laden bailing air then strikes the ground and fans out under gaps between the shroud and the ground. The proposed shelf prevents dust-laden air from striking the ground by redirecting it toward the center of the enclosure, where it can be captured. Laboratory tests demonstrated that the shelf reduced dust levels outside of the shroud by 81% under operating conditions consisting of a 1.9:1 collector-to-bailing-airflow ratio and a 51-mm (2-in.) gap between the shroud and ground. The shelf was 152-mm (6-in.) wide and was located at a height equal to 2/3 the distance measured from the bottom of the shroud to the bottom of the drill table. The air-blocking shelf was also capable of overcoming the adverse impact of vertical leakage along the shroud seams as long as this leakage was confined to an area below the horizontal plane defined by the shelf location.

Jan 1, 2008

In 2005, a total of 2,063 coal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Coal mines comprised 14.1% of all mining operations. ? Bituminous mines comprised 92.6% (n=1,911) and anthracite mines 7.4% (n=152) of coal mining operations. ? Approximately 70% of all coal mines were located in three states: Kentucky (28.0%), West Virginia (21.8%), and Pennsylvania (20.6%).

Jan 1, 2008

By V. H. Gottschalk

Among the procedures developed by the Germans for providing the tonnage of iron powder needed to make rotating bands for artillery shells is the use of a ceramic tunnel kiln, not only for finishing the reduction of centrifugal powders but also for making so-called "brickyard sponge iron," which, after crushing and grinding, seems to yield a product suitable for powder-metallur- gical purposes. The final report issued jointly by the German Powder-Metallurgical Society (DPG) and the Chemical-Metallurgical Branch of the Research Depart- ment of the Metallgesellschaft, Inc. (ZFC of MG) gives the available details of this procedure, which may be regarded as a further development of the process in commercial use since 1911 at a ceramic plant in Hoeganaes, Sweden. The Bureau of Mines' wartime development of the Hoeganaes process also cul- minated in the adaptation of ceramic tunnel kilns for carrying out the solid- carbon reduction of iron ores, and comparison with the German technique should further advance the art. This information circular is issued as a supplement to Bureau of Mines reports of investigations Nos. 3819,2 3822, 3841,2 and 4271, on brick- yard sponge iron and is based on four German reports entitled "Making Iron. Powder in the Tunnel Kiln," translated from FIAT microfilm reel H-46, frames 9190-9209, 9280-9299, 9339-9357, and 9377-9384 (PB L 70042), which represent the four original research reports, Nos. 2005, 2008, 2010, and 2012, respec- tively, of the Metallgesellschaft, Inc.

Aug 1, 1948