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By Edward J. Chuhta, Joseph E. Chilton, Robert J. Timko

in underground mines to measure worker exposure to various gases such as methane, carbon monoxide, and nitrogen dioxide (NO2). Even in relatively small concentrations, NO2 can produce harmful side effects in underground workers. Mines using equipment powered by diesel engines, carrying out explosive blasting operations, and performing extensive arc welding and/or cutting work will have measurable quantities of NO2 released by these processes. Workers in these areas often use gas monitors to warn of excessive gas concentrations and to help them determine when to increase ventilation air that will dilute these gases, thus minimizing exposures to this gas. Portable gas monitors, used to measure NO2 levels, must be calibrated before each use. Calibration is typically performed using a small portable pressurized cylinder containing a certified gas mixture. The certified NO2 standard mixture, usually 10 ppm NO2 concentration, is diluted with either air or nitrogen gas. To determine the stability of commercially available portable gas standards, two different cylinders containing NO2 in nominal 10-ppm concentrations were examined. One cylinder was diluted in air, the other, in nitrogen. Baseline NO2 mixtures were generated using a standard liquid NO2 permeation tube operated at a constant temperature. Final dilutions of the test gas mixtures were made with air or with nitrogen using a mass flow-controlled gas dilution system. This study showed that, when a permeation-type NO2 generator is used, the electrochemical sensors in portable NO2 monitors provide identical results for gas mixtures whether they are diluted with air or with nitrogen. Two different gas monitors, one with a two-electrode sensor and one with a three-electrode sensor, were used to measure gas concentrations in the two commercially available cylinders. One month after the cylinders were delivered, the NO2-in-nitrogen cylinder, stated to contain 10 ppm NO2, measured 8.13 ppm. The NO2-in-air cylinder, also stated to hold 10 ppm NO2, measured 6.88 ppm. Therefore, before using NO2 gas cylinders to calibrate monitors, it is recommended that their concentrations be verified either by manufacturer recertification or by comparing the stated cylinder gas concentrations to a laboratory-based permeation tube-generated standard.

Dec 1, 2005

By Allen D. Look

Uninterrupted shaft operations are an important economic factor in mine operation, and good shaft support is an important aid in preventing accidents and interruptions. More permanent supports can cut the hazards, costs, and delay incident to replacement of conventional timbers, especially where subject to decay. Installation of prestressed, precast concrete shaft supports in 100 feet of shaft at the Banner mine, Lordsburg, N. Mex., nave a satisfactory permanent installation in a section of shaft that had given trouble with conventional timbering. Use of rock bolts supporting gunited wire netting around the rock walls of the shaft prevented sloughing. No attempt was made in this paper to arrive at comparative costs of installation of various types of support. However, it was indicated that use of a lighter weight aggregate would be desirable in further use if prestressed precast members as placed in the Banner mine.

Jan 1, 1957

By Frank L. Hess

In 1876 cassiterite was identified in the placer gold from the northern Black Hills, and such a mixture could have come only from Nigger Hill or one of the streams draining the hill, because in no other hart of the northern hills have cassiterite anti gold been found together. Nigger Hill is in western Lawrence County, South Dakota, and on it is the little camp of Tinton. The Wyoming line runs along the west side of the hill and crosses the ridge which is the hill's continuation about miles north-northwest of Tinton.

Jan 1, 1938

By Charles T. Chislaghi

An economical, remotely operated (automated), temporary roof support (ATRS) has been developed by the Bureau of Mines for use on a single, fixed-head roof-bolting machine (squirmer) that operates in low coal seams (less than 42 in thick). The ATRS eliminates the need for squirmer operators and helpers to go under unsupported roof to set or remove temporary support prior to or during the roof-bolting cycle--a task that annually accounts for approximately 20 pct of all roof fall fatalities. The ATRS can be adapted to any squirmer used in the U.S. low coal fields. A prototype ATRS was field-tested at Imperial Colliery Co.?s Mine No. 20 in Eskdale, W. Va. The Mine No. 20 amended roof- control plan, which requires the use of the Bureau?s ATRS as temporary support during face bolting, has been approved by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor.

Jan 1, 1982

By John Nagy

Limited experiments in the laboratory with specimens of mine rock from a Virginia bituminous coal mine indicate that natural gas-air mixtures can be ignited by sparks generated by rubbing friction of sandstone against sand-stone, shale against sandstone, sandstone against (roof-bolt) steel, and shale against steel. Such sparks, generated during a roof fall, may have initiated a recent gas explosion in this Virginia mine, although this cannot be stated with certainty. No ignitions of gas were produced by sparks or heat generated by impact friction between mine rocks or steel, during tension breaks of roof bolts, or by pull tests of roof bolts through their washers and roof plate. However, this negative result of limited experiments does not preclude the possibility of gas being ignited by these conditions.

Jan 1, 1960

In 2006, a total of 741 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 These mines (e.g., potash, gypsum, salt) comprised 5.0% of all operations. ? Mines producing common clay comprised 25.2% (n=187) of all nonmetal mining operations. ? Nonmetal mining operations were located in all states and territories except Alaska, Delaware, Hawaii, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands.

Jan 1, 2008

By H. O. McDonald

Solutions containing Cr6+ and sulfuric acid are used in a number of surface-finishing operations. Substantial quantities of chromium and copper are lost and pollution problems are created when the spent solutions are discarded. To minimize the undesirable environmental effects while improving secondary resource recovery technology, the Bureau of Mines is conducting research to detoxify and recover metals from these solutions. Spent etchants are treated to remove copper and reduce Cr6+ to Cr 3+ in an electrolytic cell. The anodes and cathodes are granulated coke. The spent solution is continuously pumped through the electrodes. Hexavalent chromium is reduced to trivalent chromium, and copper is recovered at the cathode. Reoxidation of Cr3+ at the anode was not observed. The removal and recovery of copper reduction of Cr6+ lessen chemical demand and increase efficiency in waste in treatment operations associated with the use of these solutions.

Jan 1, 1980

By Michael Horn

This report presents a structural analysis of the economies of Spokane County, Washington and 21 surrounding counties. An economic trading region made up of 22 eastern Washington, northern Idaho, and western Montana counties, with Spokane, Washington as the central place, was defined for this study. The Micro IMPLAN modeling system with the 1990 county database was used to create an Input/Output based model of the regional economy. The leading industries, with respect to employee compensation, employment, value of exports, and total industry output are shown for each county and the region. The value of total industry output from natural resource based industries is also shown (or each county and the region. The total industry output from the Spokane Economic Trade Area (S ETA) region is valued at $22.3 billion. The SETA region provides $7.1 billion in employee compensation to a work force of 374,000. Spokane County, Washington accounts for about 50 percent of the regional total output, employee compensation, and employment. Both Spokane County and the region as a whole produce about 80 percent of total industry output for final demand with the remaining 20 percent going to intermediate inputs for further production. About $7.4 billion of the $22.3 billion SETA output is exported from the region. Spokane County exports about $4.7 billion, or 41 percent of the $11.5 billion Spokane County output. Exports account for more than 50 percent of the total output in 12 of the 22 counties within the region. Based on the output of the top 25 industries in each county and the SETA region about 9 percent of the industry output from Spokane County and 18 percent of the regional industry output come from natural resource based industries. For counties other than Spokane County, total industry' output from natural resource based industries represents from 12 percent to 81 percent of county output from the top 25 industries. Natural resource industries account for more than 50 percent of total county output in 8 counties within the region

Jan 1, 1994

By P. C. Good

This Bureau of Mines report describes the preparation of phosphoric acid directly from phosphate ore, without prior beneficiation, in a small-scale, continuous process research unit, as part of an effort to improve minerals and metals recovery from domestic resources while minimizing environmental effects. Three phosphate-matrix samples, ranging in grade from 18.2 pct P20S5to 11.9 pct P205, were dry-fed at a rate of 1.82 kg/hr (4 lb/hr) to a continuous-circuit, 12-liter, single-tank digester to yield phosphoric acid and byproduct gypsum filter cake. Comparison with earlier data shows that a significantly improved filtration rate was attained in a single-tank reactor compared with that attained in a five-tank reactor train processing the same ore. Iron and aluminum impurities in the product phosphoric acid averaged about 60 pct higher than amounts reported in commercially prepared, concentrate-derived acid. All gypsum filter cakes prepared had a firm, sandy texture, rendering them physically suitable for stacking or landfill use. Introduction of dry attritioning and air classification approximately doubled the attainable filtration rate when the dry-beneficiated product was digested. In air classification, there was a 12-to 14-pct P205 loss. Depending on the technique used and the matrix grade, overall P205 recovery ranged from about 72 to 89 pct.

Jan 1, 1979

By E. C. Hoeman, W. C. Stoecker, R. C. Redfield

"INTRODUCTION Industrial sands, characterized by specific physical and chemical proportion, are,essential new materials for the manufacture of glass, sodium siliante and other products. Sands of suitable characteristics are used extensively for molds and cores in the casting of metals as a granular medium in municipal water filters, as abrasives, as traction sand to prevent the slipping of driving wheels of self-propelled vehicles on trucks and in various ceramic and other structural forms. In addition to the use of common silicon sands in concrete, cement, and mortar, special sands find use in sand-lime brick oxychloride cement, and flooring, for coating prepared roofing, and for placing ware in saggers although sand for sandpaper has been mostly displaced by other harder mineral or synthetic grains, other abrasive uses are numerous and include sandblasting stone sawing, glass burnishing and finishing."

Oct 1, 1945

By L. B. Pankratz

Heat contents, measured above 298.15° K, and derived entropy increments are presented in tabular and equation form for the two crystalline forms of zinc sulfide (sphalerite and wurtzite) and for four solid solutions of iron and zinc sulfides having the compositions Zno.,,6Fe0.302S, Zno.750Fe0.250S, Zno.650Fe0.3505, and Zno.498Feo.502S.

Jan 1, 1965

By Leslie H. Sharp, Martin J. Gavin

Those of the oil-shale operators in this country who are sincerely attempting to make a real industry out of oil-shale developments, are anxious to obtain fundamental data on the retorting of oil-shale; particularly as regards the effect of certain variable factors in the process of retorting on the quantity and quality of products yielded from oil shales when they are subjected to destructive distillation. From careful examination of a con siderable number of suggested processes for treating oil shales and the con flicting ideas on which they are designed, it seems probable that accurate information of a fundamental nature is highly essential to the successful establishment of an oil-shale industry in this country. . Accordingly, the United States Bureau of Mines, in cooperation with the State of Colorado, is undertaking to furnish some definite and impartial information of this type through investigations now under way at the University of Colorado, Boulder, Colo. A retort for the distillation of oil from oil shale has been designed and installed, together with the necessary auxiliary equipment for controlling and determining variable factors of distillation, and for recovering and de termining the quantity and quality of the products yielded from the shales. The retort is of such a nature that conditions of retorting can be accurately . and completely controlled, and varied at will. It is not designed as a com mercial retort, but only for research purposes. A testing laboratory with equipment necessary for the examination of the shales, physically and chemic ally, and the products yielded by them, has also been fitted up . The material used in the investigations is oil shale obtained from the DeBeque, Colorado, shale field. It yields on distillation in the Bureau of Mines testing apparatus, about 42 gallons of oil to the ton, and is there fore a fairly representative sample of the shales that probably will be first worked in Colorado. The shale used will be as uniform as possible in character and oil yield and will all be obtained from the same seam at the same point, in order to avoid the introduction of unnecessary variable factors in the tests and to render results strictly comparable •

Jul 1, 1920

By E. P. Youngman

This paper is one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the mining laws of British Honduras has been prepared from the best available information in Washington and is released subject to amplification or correction, if necessary, by United States foreign-service officers. INTRODUCTION The mining law governing all mineral substances other than oil is ordinance No. 7 of 1927 (Minerals Ordinance, 1927), passed by the Legislative Council on March 25, 1927. The accompanying regulations, No. 3 of 1932 (General Minerals Regulations, 1932), made under the authority of section 66 of the minerals ordinance, were made by the Governor in Council on December 23, 1931.

Jan 1, 1934

By Christopher Van Dyke, Edward L. Petsonk, Knox Van Dyke, Vincent Castranova, Ji-Hee Kang, William Pailes

"INTRODUCTIONPlatelet-activating factor (P AF) has been shown to mediate a broad range of biologic activities (1). Chemical analysis has shown that PAF is a glycerophospholipid with a choline polar head group, an ester-linked acyl chain at the second carbon of the glycerol backbone, and an ether linkage at the first carbon. The alkyl group attached to the first carbon can exist in a variety of chain lengths, with the C16 and C18 forms predominant in humans. The structure of P AF has been identified as 1-0-alkyl-2-acetyl-sn-glycerol-3-phosphorylcholine (2,3).PAF can be released from a variety of cell types, such as basophils, neutrophils, and alveolar macrophages ( 4-6). Stimuli for the release of P AF include calcium ionophore, phorbol esters, chemotactic agents, and zymosan. In addition, endotoxin has been shown to be a potent stimulant of P AF release from alveolar macrophages (7).P AF has been shown to have a number of pulmonary effects. It has been associated with asthma since it can cause contraction of pulmonary tissue (8) and leukotriene secretion from leukocytes (9) and induce airway constriction when inhaled by humans (10). In addition, PAF is a potent chemoattractant and can cause migration ofneutrophils into the airspaces of the lungs (11,12). Endotoxin is a lipopolysaccharide-protein complex derived from the cell walls of gram-negative bacteria. I.PS is the lipopolysaccharide portion of endotoxin. LPS contains four covalently joined subunits: lipid A, 3-deoxyoctonate, a core polysaccharide moiety, and an 0-specific antigenic polysaccharide side chain. Rough LPS contains no 0-antigen side chain. The liP.id A portion of LPS has been associated with most of the biolQgic effects of endotoxin (13). This lipid A subunit consists of a D-glucosamine disaccharide backbone substituted with four fatty acid side chains. Endotoxin is found in a wide variety of occupational settings associated with organic dusts derived from plants or animals, such as cotton, cereal grains, silage, rice, and poultry (14-18). In addition, airborne endotoxin has been found in sewage treatment plants, composting plants, offices with contaminated humidifiers, and showers or saunas (19-22)."

Jan 1, 1990

By Guy B. Taylor, Horace C. Porter, E. C. White

When the Federal investigation of coal - dust explosions in mines was begun in 1908 , following a series of mine explosion disasters in 1907 , mining men generally questioned whether coal dust in air is explosive unless " gas " or methane is present , though perhaps in small amounts not detectable by a safety lamp . The experimental tests beginning in 1909 at the Pittsburgh testing gallery, and after 1911 , at the Experimental mine , demonstrated to the mining public the explosibility of coal dust in itself . There followed much controversy , both among practical mining men and scientists , as to whether the coal-dust particles uni te directly with the oxygen of the air, or whether gas is instantaneously distilled from the dust prior to explosive combustion , the gas enveloping each particle and propagating the flame from one to another . In considering methods of preventing explosions , this question made no difference for practical purposes , but it did have bearing in determining the relative inflammability of dusts of different coals . This led to the experiments by Guy B. Taylor and Horace C. Porter , on the momentary heating of the inflammable coal dusts , reported in this paper . Meanwhile , experiments on the inflammability of coal dust conducted in the Experimental mine , under my direction , and in the laboratory by J. C. W. Frazer and later by J. K. Clement and J. N. Lawrence , showed that different kinds of coal dust differ markedly in inflammability , thus confirming experiments made by Messrs . Taffanel and Durr at the Lievin Testing Station , France , and by various investigators in Great Britain . Both the French and British investigators concluded that their experiments demonstrated the distillation of volatile matter preceding inflammation .

Jan 1, 1922

By Ernest W. Loya

The Bureau of Mines has developed a computer program for calculating the composition of gravimetric primary standard gas mixtures. The Fortran IV program applies corrections due to buoyancy variations of the cylinder and inaccuracies of the balance weights. The program also determines the statistical error due to the sensitivity and precision of the balance and applies the analytical error of the weighed gases.

Jan 1, 1985

By Welton J. Wenger

Apparatus for the analytical distillation of crude oils under an artificial pressure of 760 mm. of mercury has been designed and constructed. This apparatus enables laboratories at high altitudes to make Bureau of Mines routine analyses of crude oils with results similar to those obtained by laboratories at sea level. This is especially important for laboratories in the Rocky Mountain region, where barometric pressures of approximately 600 mm of mercury are encountered. During the past 30 years, the ?Bureau of Mines has made several thousand analyses of crude oils from various parts of the United States and from foreign countries. The first part (stage 1) of the distillation for the analysis is made at atmospheric pressure, and as most petroleum laboratories are near sea level, comparable results are obtained ordinarily. However, the increased use of the method by .laboratories at high altitudes has caused difficulty, as the analyses cannot be accurately compared with analyses from laboratories at sea level. For instance, laboratories at 7,200 feet generally report 2 to' 4 percent (based upon the crude oil) more gasoline than sea level laboratories. The use of the pressurized apparatus developed by the writers makes it possible for these high-altitude laboratories to duplicate analyses made at sea level.

Jan 1, 1949

By Richard A. Dick

Underground blasting in permanently frozen gravel was studied in a 7-by 12-ft drift by running a nonreplicated 2 X 2 X 2 factorial experiment on the effects of type of cut, delay, and explosive on the fragmentation subsystem. Comparisons were made between a V-cut round and a burn-cut round, millisecond delays and half-second delays, and 40 percent special gelatin and 60 percent high-density ammonia dynamite. The number of large blocks in the muck pile) loading time, shuttle car operating time lost because of cleanup needs, length of advance per round, and length of muck pile were recorded and statistically analyzed. None of the blast parameters had a significant effect on the length of advance or length of muck pile, although the half-second delays tended to give a shorter muck pile than millisecond delays. The burn cut required less secondary breakage, less loading and cleanup time, and gave better overall fragmentation than the V-cut. The ammonia dynamite shots required less secondary breakage and less loading time than those using special gelatin. The half-second delays gave better overall fragmentation and required less cleanup time, but the millisecond delays gave a better loading rate. None of the differences between delays and explosives were notably significant.

Jan 1, 1970

By J. L. Eakin

A method was developed by the Bureau of Mines in the laboratory and in the field to relieve capillary waterblocks in gas wells. Impaired gas permeability was improved by this inexpensive chemical treatment which lowers the surface tension of the water held in the capillaries of the formation. Effectiveness of the alcohol-surfactant treatment was tested with a variety of chemicals and with sandstone cores cut from rocks having relatively low permeability. Field tests on 20 gas-producing and storage wells demonstrated the effectiveness and limitations of the method. The productive capacity of some wells was doubled by the treatment. The final test was evaluated by the neutron logging technique for measuring changes in apparent liquid saturation. Maximum apparent liquid saturation was reduced by 52 percent; gas production rate increased from 2.3 to 3.5 MMcfd (million cubic feet per day).

Jan 1, 1965

By S. H. Katz

In the Bureau of Mines investigations of respiratory apparatus, a laboratory study of dust respirators has been conducted, and the results will be published in detail as a technical paper. Many industrial dust respirators, and many fabrics and filtering materials were tested. The principal results of these tests, and the conclusions drawn from them, are presented below. Reference to the patent literature discloses numerous types of dust respirators, mostly based on the filter principle. The present study included only representative filter-type respirators, purchased on the market.

Jan 1, 1926