Search Documents

By Roy Greenfield

Estimates are given for the distance from a seismometer at which a miner can probably be detected. The procedure in making these estimates was to first establish the natural noise levels at the output of a surface seismometer for the 25 to 100 Hz frequency passband. The noise levels give the range of values which may be expected in areas with no man-made noise. For each noise level, we give the detection threshold which, when exceeded, indicates that a signal has been received. Based on the signals recorded by Westinghouse, curves are given which show the peak signal amplitude as a function of source- to-receiver distance (slant range). Curves are given for the Westinghouse seismic thumper, a 50-pound timber, and a sledge. For a given type of source, the receive signal strength depends more strongly on slant range than on any other factor. However, there is approximately a five-to-one scatter in the amplitudes. Thus, further study of factors affecting the signal amplitude might allow better estimates to be made for any particular geological setting. Combining the signal amplitude with the detection thresholds for the different noise conditions gives the distances at which a miner should be detected. These are given in Table l* below. [ ] The text also gives the increase in detection ranges which should occur if steps are taken to increase S/N by 10 dB. We feel that 10 dB is a conservative estimate of the improvement possible. During an actual rescue operation, the seismic crew and system should be capable of making on-site estimates of their detection capability, based on measurements of the site noise, and upon the best available estimates of the

Jan 1, 1974

By W. C. Hudson

"The Miami-West Palm Beach belt of silica sand, which may be suitable for the manufacture of high-grade glass, extends 65 miles northward from the neighborhood of Miami to the vicinity of West Palm Beach, The sand presumably originated in the host rocks constituting the oceanward slope of the Appalachian Mountains and the Piedmont Plateau of Georgia and the Carolinas. The sand now lies in a long, narrow, and probably thin belt that forms a dune-capped terrace marking a previous stage of submergence. The highest dune crests appear to be no more than 30 feet above sea level, and the water table is about 10 or 15 feet below the general level of the terrace.The width of the belt in several places is known to be more than a mile, and the thickness of the clean glass sand sampled ranged from 4 to more than 7 feet. Visual inspection and the meager data indicate the existence of bodies of glass sand large enough to supply foreseeable markets.Analyses of three samples indicate that beneficiation would make the sand suitable for the better grades of ordinary and flint glass.The prospective grade and quantity of sand, an available market in Florida for glassware, and the expectation of postwar expansion of the new industry of glass producing justify more detailed exploratory work and beneficiation testing.U. S. Route No. 1, Old Dixie Highway, the Seaboard Railway, and the Florida East Coast Railway, all substantially parallel and usually within a width of a mile or two, run along parts of the belt or between it and the coast. In addition to many streets and unpaved roads, a paved road crosses the belt at right angles about every 5 miles. Numerous towns are situated within or near the belt. Any area selected for a mining, processing, and manufacturing plant would be near a railroad, a highway, and water and also accessible to public utilities.The subtropical climate, famous for its pleasantly warm winters, would preclude seasonal interruption of plant operations."

Apr 1, 1946

By Frank J. Wiebelt

The Mohawk lead-zinc mining in San Bernardino County, Calif., was examined by D. W. Butnor, an engineer or the Bureau of Mines, at the request of Dunton, Ray, and Greenwood, leaseholders. Current operations were on a marginal economic basis, and government aid was sought in an endeavor to outline ore reserves so that production might be maintained.

Jan 1, 1949

By A. B. Hooker

A list of permissible mine equipment, tested and approved by the Bureau r. Mines previous to January l, i-)4, , was published in Bureau c Moines In ornation Circular 7207.3/ The l ,.t c -. that dote was complete as to equipmentthen available and in current Information Circular 7210,?+/ published as a supplement thereto, listed equipment approved during; the calendar 1942. Information Circular72x'3,_/ published as a second supplement thereto, ! listed equipment approved during the calendar year 1943. The present listis. Another supplement covering approvals issued during the calendar year 1c)44. The items are numbered crud to indicate the consecutive order in which each typo of machine or device was approved _.c?. in its particular classification. Thus Information Circular 7207 gave 1,t drills and drilling much fines on the Bureau'sactive.. d active list Ih: additional anal approval: were given in 1942 the three issued in 19 and one issued :n 1944- bring the total to `3. Item 111, under. Loading Machines and conveying appeared in lnformation Circular 7207. It is repeated ',tore to _how that on j,,l was granted Curia 1the optional of this loader when modified .'or 2 0. alt ciruits .]

Jan 1, 1945

By S. P. Kinney

[The blast-furnace operator is often confronted with the problem of determining the size of the materials which are used in the furnace burden. The statement is heard that the coke is larger or smaller or that certain ore is finer than that previously used. A screen analysis of the materials used gives a measure of the different sizes of materials in an aggregate. When one is fine and the other is coarse, the difference is obvious; but when the materials are of similar sire, it is more difficult to estimate the degree of finances or coarseness. In considering raw materials it would be desirable to be able to judge the size of the radio ideal materials entering the furnace and the burden as a whole, by one representative value, such as the average size of particle. Previous work by Perrott and Kinney3 developed a method for measuring the average size of particle in a mass of finely ground materials, and an attempt will be made to apply this method to the materials included in the blast-furnace charge and to the entire burden.]

Jan 1, 1930

By S. D. Maksimovic

The use of vertical surface degasification boreholes with bleeder systems and the use of a timbered bleeder system to degasify gob areas were studied by the Bureau of Mines. This report describes three gob degasification studies conducted in the Pittsburgh coalbed. One study was conducted to determine the number of panels degasified with one large borehole. The study showed that the borehole provided degasification for three panels. Another study was conducted during the retreat of a 35-acre panel with a single-entry and a two-entry bleeder system and a large surface borehole. A major portion of methane emitted from the panel was carried away by the bore-hole, leaving the bleeder entries relatively free of methane. The last study was made to determine the effectiveness of a timbered bleeder system. The bleeder entries successfully degasified the gob area when enough entries were available and adequate pressure was available to force the air through roof falls.

Jan 1, 1980

By Knox Van Dyke, Vincent Castranova, Lixin Wu, Mark J. Reasor, James M. Antonini

"One of the proposed mechanisms involved in the pathogenesis of silicosis is that inhaled silica dust activates a ""respiratory burst"" in pulmonary phagocytes, such as macrophages and neutrophils. This increase in oxidative metabolism results in enhanced generation of reactive oxygen species which if produced in excess, would overwhelm natural defense mechanisms and cause damage to the lung parenchyma. This damage would then result in scarring, fibrosis, and decreased gas exchange.Weiss and LoBuglio' have listed several oxygen species produced by phagocytes which may be involved in cellular injury. These oxidants include superoxide anion, hydrogen, peroxide, hydroxyl radical, and hypochlorous acid. Superoxide anion (0;) is generated from molecular oxygen by the plasma membrane bound enzyme NADPH oxidase according to the following reaction:Once generated, superoxide anion can form hydrogen peroxide:In the presence of myeloperoxidase and halide, hydrogen peroxide can form hypochlorous acid:Superoxide and hydrogen peroxide can also form highly reactive hydroxyl radicals. Hydroxyl radicals can be generated slowly by the Haber-Weiss reaction:In addition. hydroxyl radical production can be catalyzed via the Fenton reaction:Hydroxyl radicals can also be generated from the reaction of superoxide and hypochlorous acid as follows:Recent investigations suggest that, in addition to the reactive oxygen species discussed above, nitric oxide may be a potential mediator of silica-induced toxicity.2-4 Nitric oxide (NO') can be generated by the cytosolic enzyme nitric oxide synthase according to the following reaction:NO synthase exists in two forms. i.e.. a constitutive. Ca2+-calmodulin-dependent form and an inducible. Ca2+-calmodulin-independent form. In pulmonary phagocytes. the activity of the constitutive form of NO synthase is low. However. NO synthase can be induced in macrophages and neutrophils by a variety of stimulants such as lipopolysaccharide. interferon y. chemotactic peptide, platelet activating factor, or leukotriene B4.3.5Once generated. nitric oxide can combine with superoxide anion to form peroxynitrite as follows:Peroxynitrite is a potent oxidizing agent. In addition, peroxynitrite can form peroxynitrous acid. which in turn can produce hydroxyl radical and nitrogen dioxide (all of which exhibit strong oxidizing potential) by the following reactions:Oxygen metabolites have been shown to cause lung damage in vivo.6 Such damage includes edema. leakiness of the alveolar endothelial/epithelial barriers, and airway constriction.7 Superoxide and hydrogen peroxide have been associated with membrane damage and cell lysis.8 These oxidants have also been associated with alteration of cytoskeletal structures at cell-cell junctions and elevation of transepithelial conductance in cultured monolayers.9 Macrophages or neutrophils can be stimulated by bacteria or phorbol myristate acetate to produce sufficient oxidant levels to lyse lymphoma cells.10 This cell killing is inhibited by catalase but is unaffected by superoxide dismutase. hydroxyl radical scavengers. or azide. i.e., an inhibitor of peroxidase. This implicates hydrogen peroxide as the active oxidant. Similarly. Weiss et al.11 have reported that hydrogen peroxide is critical in the death of cultured endothelial cells due to neutrophil activation. In addition. hydroxyl radicals generated by monocytes have been associated with cell injury.12 Lastly. peroxynitrite has been shown to oxidize sulfhydryl groups and to inactivate proteinase inhibitor making the lung more susceptible to damage caused by phagocytotic enzymes.' Therefore. a strong case can be made that activated pulmonary macrophages and neutrophils are capable of causing oxidant injury. This chapter presents in vitro and in vivo data indicating that silica is associated with the production of reactive oxygen species from these pulmonary phagocytes."

Jan 1, 1998

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

1, Introduction This report is submitted in fulfillment of the requirements of USBM Contract No. J0255017, "Development of Emergency Escape Systems Guidelines for Underground Metal and Nonmetal Mines" Under this contract the history of past mine fires was studied. Representative metal and nonmetal mines were surveyed and escapeways, refuge chambers, life support, and emergency hoist requirements were studied to determine the problems in complying with the proposed regulatory standards and their enforcement by MESA Mine Inspectors. In addition, a computer program was written to evaluate mine evacuation performance. The completed program is included in the appendix. 1. 1 Historical Review of Metal and Nonmetal Mine Fires Early records of mine fires are poorly documented because there was no statutory provision for reporting fires to the Bureau of Mines. The survey of representative mines during the course of this contract indicated that many small fires still go unreported even though they are now required to report all fires A recent report survey approximately 80 disasters in metal and nonmetal mines, (6 ) Table I is a summary of some of these fires. Historically most metal and nonmetal mine fires have been caused by electrical problems. Spontaneous combustion and the use of welding equipment are the other major causes of mine fires(14) Although not documented, many mine personnel agree that 30 percent to 40 percent of underground metal and nonmetal mine fires have their origin from cigarettes and other smoking related materials. The number of fires related to spontaneous combustion is decreasing and equipment fires are on the increase. The reduction of spontaneous combustion fires can be attributed to the use of sandfill in more mines and the increase in equipment fires to the increased use of LHD equipment.

Jan 1, 1976

By T. M. Nasiatka

This report sterns from a study undertaken by the Federal Bureau of Mines to determine the possibility of reducing filter-cake moisture by applying radiant heat. Suitable laboratory equipment was set up to study the effect of heat, heating time, proximity of the heater to the filter cake, cake thickness, and other variables related to the final filter-cake moisture. A minus-48-mesh coal slurry and application of heat for 60 seconds resulted in filter-cake moistures 5.6 to 13.2 percentage points lower than could be accomplished by filtration alone at 24 inches of Hg for 1-1/4-and 1 1/2-inch cake thickness, respectively. The moisture reduction can be attributed to the combined effect of lower fluid viscosity and evaporation.

Jan 1, 1959

By A. L. Engel

This report is a compilation of preliminary and, in some cases, more extensive concentration experiments by the Federal Bureau of Mines on low-and medium-grade fluorspar ores from three localities in Nevada and one in California. The work was done on samples obtained from Shoshone mine, Nye County, Valery mine, Pershing County, and the Broken Hills mine, Mineral County, all in Nevada, and Dirty Weather mine, Inyo County, Calif. These investigations were made to aid in the development of domestic fluorspar resources, in line with the Bureau's long-established program of conservation of mineral resources. The treatment methods employed in the experimental work described included simulated or "heavy-liquid" gravity concentration of coarse minerals and comparatively fine-grained minerals, and flotation concentration of finely-ground minerals. These methods were attempted in order to beneficiate the ores and produce concentrates which could be marketed readily, with as high a recovery rate as possible, while using simple treatment methods suitable for small-scale operation.

Jan 1, 1961

By James L. Konchesky

Crushed coal, consisting of a wide range of sizes, was effectively blended by recycling it through a bin equipped with a particle distributor. Vertical blending was accomplished by simply recycling the coal; it was not significantly influenced by the horizontal blending that was achieved by the distributor. The method was effective, even though the coal was wet and possessed poor flowing characteristics. Recirculation appears capable of providing uniform blends of solids that can be more efficiently processed. Recirculation also appears useful, preceding packaging operations, to insure for blending of solids into specification products. Continuous measurement of the bulk density of the coal by a gamma ray meter proved to be an effective monitor of vertical blending effectiveness.

Jan 1, 1972

By R. F. Stewart

A sedimentation method involving the use of the Palo-Travis apparatus was found satisfactory for rapid determination of the size distribution of coal particles ranging from 10 microns in diameter to those passing an 840-micron opening (20-mesh sieve), The method is most useful for comparing the size distributions of samples of pulverized coal where the actual size of the particles is not required and is applicable to sieve and subsieve sizes of a wide variety of coals and chars that can be wetted and are heavier than water. An analysis, including all calculations, can be completed in 1/2 to 10 hours, depending on the time required for the finely divided coal to settle. A typical analysis requires about an hour, making this a rapid, precise method for routine size-distribution analysis of powdered coals. When used with coal particles smaller than 400 microns, the method is precise within 15 microns for wide variations in test conditions and within 5 microns for identical test conditions. The precision decreases as particle size increases, becoming unsatisfactory for particles larger than 400 microns (40-mesh). For precision within 15 microns, the samples must be equal in weight. Greater precision is obtained with 4-gram samples, but samples as small as l gram may be used.

Jan 1, 1961

By John R. Shattuck

As a part of the general chromite investigation in California designed to aid In the production of chromite during the recent war emergency, the Bureau of Mines explored the Coggins property in Siskiyou County, Work by the Bureau in cooperation with the Federal Geological Survey began in October 1942 and was concluded in March 1943. This report presents a brief history of the mine, outlines the physical features of the district, describes the deposits) and explains the work completed by the Bureau of Mines, Table 1 shows the analysis of diamond drill-hole samples. The logs of drill holes are in the appendix.

Jan 1, 1949

By John A. Davis, John Gross

Six tests were made by the Alaska Station of the Bureau of Mines on a sample of black sand delivered to the station by Messrs. James, Eagan & Griffen from Fairbanks Creek, Fairbanks mining district, Territory of Alaska, to devise a method of recovering the gold content. More than 90 per cent of this black sand consisted of magnetite and garnet which can be separated magnetically. The Station has no equipment for magnetic separation other than an electromagnet similar to the one used by Day and Richards, (Day, D.T., and Richards, R.H., Investigations of Black Sands from Placer Mines, U. S. Geol. Survey, Bull. 285, 1906, pp. 150-163), which can only be used satisfactorily on small samples. To treat the entire lot of black sand with this machine would have been impracticable. Therefore only a small part of the sand was so treated, the rest being divided into five lots in order to obtain comparative results from other methods of treatment.

Aug 1, 1920

By M. I. Copeland

The investigation of the zirconium-gadolinium equilibrium diagram was part of a program to investigate rare:earth alloys for use as nuclear reactor control materials. Investigation of the zirconium-gadolinium equilibrium diagram revealed a eutectic system with limited terminal solubilities and one peritectoid reaction. The eutectic composition occurs at about 82 percent gadolinium, and the eutectic isotherm, which occurs at 1,220 ±5° C., extends from about 12 to 99+ percent gadolinium. A peritectoid isotherm occurs at 890 ±5° C. and extends from about 2 to 99+ percent gadolinium. The solubility of gadolinium in beta zirconium decreases from about 12 percent at 1,220 ±5° C. to about 2 percent at 890 ±5° C. The solubility of gadolinium in alpha zirconium decreases from approximately 5 percent at 890 ±5° C. to between 2 and 3 percent at 600° C. Vary little solubility of zirconium in gadolinium was indicated. An allotropic transformation of gadolinium was observed at 1,260 ±5° C. A change of the gadolinium transformation temperature on alloying with zirconium was not observed.

Jan 1, 1961

By Clarence O. Babcock

Model pillars of limestone, marble, sandstone, and granite having length to diameter ratios of 3:1, 2:1, 1:1, and 0.5:1 were broken in axial compression to determine whether lateral end constraint affected the breaking strength. Steel rings bonded to the ends of the model pillars with epoxy provided, during the loading cycle, a lateral end constraint of about 17 to 30 percent of the average axial stress. The effect of this constraint was to increase the breaking strength of the rock as compared to cylindrical pillars without constraint. The percentage increase in breaking strength varied with rock type and increased as the length to diameter ratio decreased. The maximum increase in breaking strength was 35 percent for marble pillars having a length to diameter ratio of 0.5:1. A theory was developed which relates the expected constraint to the physical properties of the ring and rock.

Jan 1, 1968

By Deborah A. Spotts

Researchers at the Bureau of Mines have developed a technique for re- generating chromic acid-sulfuric acid etching solutions used in metal surface treatment operations. The technique utilizes a diaphragm cell equipped with a cation-selective membrane to oxidize cr3+ to cr6+ at the anode and to remove copper, the major metallic contaminant, at the cathode. Normally, spent etchant is discarded after approximately 3 days of use. Using the electrolytic cell, the etchant can be used for a year without replacement, From data obtained from industrial-scale cells, the installation of a regeneration cell with a 1,000-gal catholyte- holding tank has been estimated to save at least $240 per day, The payback period for the investment is estimated to be about 10 mo or less. Because the magnitude of these cost savings will vary at different locations, several graphs are presented to aid in calculating payback for a specific site. Using these graphs and the capital costs presented in this study, the payback period can be determined for installing a regeneration cell with a 500- or a 1,000-gal catholyte-holding tank in an existing surface treatment plant.

Jan 1, 1983

By A. S. Prokopovitsh

A spectrophotometric method for the determination of small amounts of copper in tungsten metal powder using the principle of solvent extraction has been developed by the Federal Bureau of Mines. The metallic sample is dissolved in hydrogen peroxide, tartaric acid added, the pH adjusted, and the excess peroxide destroyed by boiling. Copper is reduced to the cuprous state, and the reagent neocuproine (2,9-dimethy1-1,10-phenanthroline) is added to form a colored complex with the copper. This colored complex is then extracted into chloroform and the absorbance of the separated chloroform layer measured on a spectrophotometer. Copper contents as low as 1 p.p.m. (parts per million) can be determined. The method is limited to finely divided tungsten powder. The interest of the Bureau of Mines in developing more sensitive methods for the determination of trace impurities in high-purity tungsten prompted an investigation of the possibility of using solvent extraction-colorimetric methods. The organic reagents now commercially available make possible many extremely sensitive colorimetric methods for the determination of metallic ions. Extraction of the colored complex into a small volume of organic phase can be used to further increase sensitivity (4) .4/ This general approach has the added advantage that no special equipment beyond that normally found in an analytical laboratory is required.

Jan 1, 1961

By L. E. Geyer, W. W. Adams, M. G. Parry

"More than 73 million pounds of rock dust were used by the bituminous-coal-mining companies in the United States during 1930 to present or limit loss of life and destruction of property from explosions of gas and coal dust in underground mining operations, according to statistics compiled by the United States Bureau of Mines from reports furnished by mine operators. The mines using rock dust produced 65. 691, 753 tons of coal during the year, more than 30 percent of the total production of bituminous coal from underground mines in the United States that year. Although only 382 out of a total of 5,629 active underground bituminous mines applied rock dust to underground working as a precaution against explosions, they were chiefly the larger producing mines, employing 25.4 percent of all of the underground bitumious mine workers in the United States and accounting for 27.4 percent of the total number of man-hours worked underground at bituminous mines.a summary of the reports for the 382 mines using rock dust showed a total production of 96,691,755 tons of bituminous coal, 89,503 men employed underground, and 129,718,965 man-hours worked by the underground employees. (See tables 1 and 2.) These mines averaged 8.76 pounds of rock dust per ton of coal shown by reports from 385 mines using rock dust in 1932 (See table 3.)"

Nov 1, 1935

By Philip C. Good

The Bureau of Mines investigated the feasibility of utilizing low-grade phosphatic shale as a feed for phosphoric acid production. Present practice in the phosphate mining operations of southeastern Idaho is to remove and either stockpile or waste low-grade phosphatic shales as the high-grade phosphate beds are selectively mined. Acid digestion studies were performed on uncalcined shale and on shale calcined to remove free carbon to determine phosphoric acid quality, yield, and amenability to filtration. The untreated shale, containing 21.4 pct P205, was digested with sulfuric acid in a single-tank reactor to yield phosporic acid and gypsum residue. Although 96 pct P205 recovery was attained in digesting uncalcined shale, only the calcined product gave satisfactory filtration rates. Calcined shale yielded phosphoric acid recovery of about 93 pct of the contained P205. It was higher in impurities than commercially prepared acid derived from high-grade western phosphate rock. An acid filtration rate of 745 lb P205/ft2/day was attained. This value is lower than the rate of 900 lb P205/ft that is generally considered to be acceptable in industrial production of phosphoric acid from high-grade phosphate rock.

Jan 1, 1981