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By S. H. Lorain

This paper is one of a series on mining methods and costs being published by the U. S. Bureau of Mines. The operations of the Quartz Hill Mining Co., near Dewey, Mont., afford an interesting example of the cost of mining small bodies of direct shipping ore; they also illustrate the effect of the unavoidable periods of unusually high exploration and development costs in this type of mining upon the cost per ton of producing ore. The importance of skilled geological guidance and the necessity of avoiding unnecessary overhead and capital expense at small mines are shown. Operating conditions at Quartz Hill are typical of those in many other mining districts of southwestern Montana. It is believed that the costs presented here may be of value in the preliminary estimation of costs to be expected by conservative operators under similar conditions elsewhere. The information contained in this paper was obtained during a visit to the Quartz Hill mine in August 1936.

Jan 1, 1937

This Bureau of Mines publication describes the plan used to instrument two longwall gateroads at the Powhatan No. 4 Mine of the Quarto Mining Co. Vibrating wire stressmeters, flat jack U-cells, multipoint extensometer stations, and convergence stations were installed in or on the coal pillars, roof bolts, and roof strata of the gateroad entries. The instruments measure pillar stresses, bolt loadings, and strata movements as the gateroad entries are developed and the longwall panel(s) is mined. The report details only the instrumentation plan of the longwall gateroads and not the evaluation of any subsequent data. This is because a complete analy-sis of the data cannot be made until extraction of the longwall panel(s) is complete.

Jan 1, 1982

By Douglas A. Crum

The Taylor's friction circle method for slope stability analysis can be extended to incorporate multiple circles defining the slip surface in a failure mechanism so that it is a workable method for bearing capacity calculations of foundations and rotational failures of retaining walls and similar structures. The U.S. Bureau of Mines has further extended the multiple-circle method to include friction in the material strength and to utilize computational schemes such that this method can be programmed with optimization capabilities rather than being used as a graphical or semigraphical method. Some examples are given that demonstrate ultimate bearing capacity calculations of embedded foundations with eccentric loads and nearby slopes.

Jan 1, 2010

Prevention of coal-mine explosions depends largely upon thorough knowledge of the causes that initiate explosions. A review of coal-mine explosions in one geographical area when supplemented by nationwide data of similar nature, should serve as a guide for the adoption of measures for explosion prevention. Explosions in bituminous-coal mines of the United States during the 10 years ended December 31, 1932, ranked third in the causes of fatal accidents and constituted 16.1 percent of all fatal accidents in bituminous mines. Kentucky now ranks fourth in coal output in the coal-producing States of this country; a study of the coal-mine explosions in this state will be of definite interest locally among coal-mining people, as well as to those in the coal-mining industry who are concerned in preventing coal-mine explosions. This circular reviews gas and dust explosions in Kentucky coal mines to show their hazards, to point out the influence of certain factors in causing explosions, and to indicate the effectiveness of preventive measures.

Jan 1, 1934

By J. E. Matta

The methane gas emitted from coal samples collected from the conveyor belts dumping into silos was measured by the Bureau of Mines. Approximately 50 pct of the total gas desorbed into a sealed can within 1 week was released during the first 24 hours. No simple correlation between the gassiness of the coal stored and the methane concentration in the silo open space above the coal was found. This was probably because the gassier coals were stored in open-top Silos, which were better ventilated. Although the methane concentration in the open space above the coal pile was less than 1 pct for all 34 silos investigated, a methane measurement in the coal pile showed that high methane concentrations can exist. The methane released in the pile appears to accumulate and not liberate freely into the open space above the coal pile. Probably this gas is released during reclaiming operations, but further research is required to substantiate this claim.

Jan 1, 1978

By Donald P. Blasko

The Bureau of Mines investigated two areas of oil and gas seeps in the north-central Gulf of Alaska--Katalla River to Bering River and Cape Yakataga to Yakutat Bay to determine (1) whether previously reported seeps are still active, (2) the characteristics of the seeping hydrocarbons, and (3) the amount of bitumen contained in the drainage leaving the seeps and entering the Gulf of Alaska. Thirteen separate oil seeps, six bitumen deposits, and eight gas seeps were located, sampled, and analyzed. The oils ranged from 35.2° to 14.1° API gravity and had sulfur contents from 0.53 to 1.31 wt-pct. Bitumen samples had API gravities from 2.4° to 14.6° and sulfur contents from 0.28 to 0.88 wt-pct. Gas samples had specific gravities ranging from 0.577 to 0.883 and caloric values from 724 to 1,427 Btu/cu ft. A total of 63 water samples obtained from seep locations and seep drainages were analyzed by atomic absorption spectrophotometry for ionic content and by solvent extraction for hydrocarbon content. Although some of the water at the oil seeps had a bitumen content as high as 246,000 mg/1, the amount of hydrocarbons actually reaching the Gulf of Alaska averaged <0.2 mg/1.

Jan 1, 1976

By Isaac A. Zlochower, Michael J. Sapko, Ronald S. Conti

The Bureau of Mines has developed a system using a high-speed electropneumatic mechanism for the rapid (grab) sampling of dusts and gases during an explosion. The sampling system consists of an aluminum housing that incorporates two 30-cm3 preevacuated glass vials with rubber septums. Upon actuation, the sampling probe needle is driven through the septum with a pressurized air pulse, filling the tube with gas and dust from the mine explosion. After a predetermined time, the sampling probe needle is retracted by a second high-pressure air pulse to its normal (quiescent) state, allowing the sampling tube to reseal. The onset and the duration of sampling are independently variable and controlled by a time-delay relay package. This technique enables the monitoring of pyrolysis-charring in coal particles and the generation and combustion of the pyrolysis vapors in both large- and small- scale explosions. The following results were obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Laboratory: (1) Gas sampling of the leading edge of the flame front shows the large concentration changes, characteristic of the flame front; (2) gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen; and (3) the particles collected in the flame zone show signs of extensive pyrolysis and charring.

Jan 1, 1988

By Carlton E. Brown

Broom and Yant6/ recently described a. microprojection method for determining the particle-size distribution and number concentration of samples of dust collected from the air by such samplers as the Owens jet dust counter) and the thermal precipitator8/ . This method was developed to obviate or reduce the eyestrain consequent to the regular filar-micrometer method9/ and to save time and work. The article stated that work was in progress on a micrcprojection method for counting impinger dust samples; this article describes the method developed. ACKNOWLEDGMENTS The assistance of the personnel of the ventilation Department of the Anaconda Copper Miring Co., Butte, Mont., in developing this method and particularly in suggesting a suitable material to use for the microprojector screen is sincerely appreciated. Much of the work was done in the laboratory of the Anaconda Copper Mining Co. on samples collected in Butte mines during a cooperative study with this Bureau.

Jan 1, 1938

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 can and ore rate mines in various foreign countries. This interpretation of the mining laws of the Irish Free State has been prepared from the best available material in Washington and is released subject to amplification and correction, if necessary, by American foreign-service officials. INTRODUCTION This paper is based upon the mines and minerals act, 1931, enacted by the Legislature (Oireachtas) of the Irish Free State (Saorstát Eireann), December 22, 1931, the lull title of which is "An act to establish a board to perform functions in relation to mines and minerals, to authorize the making of lenses of mines and minerals belonging to or vested in Saorstát Eireann, to name provider for facilitating the working of other mines and minerals and, for imposing restrictions on the working of minerals required for the support of buildings and works, to amend the law with respect to mines, and for other purposes incidental to the matters aforesaid.&apos;

Jan 1, 1933

By D. A. Hill

This volume contains a summary of the results of past analyses on U.S. Bureau of Mines Contract No. H0122061 which are relevant to electromagnetic location in mine rescue situations. The analytical results indicated that detection of a trapped miner equipped with a special transmitter is feasible in most situations. Location of the miner by surface measurements is also generally feasible within certain errors. The feasibility of miner detection and the accuracy of miner location have been examined theoretically for a wide variety of situations. Agreement with experimental results is generally good in cases where measurements are available.

By M. O. Serbousek

The load-transfer mechanics of fully grouted roof bolts in coal mines have been investigated in laboratory and analytical studies. The purpose of this Bureau of Mines research is to increase understanding and better interpret data from routine field pull tests and to develop a numerical model of a grouted bolt that can be used in a global computer model of a mine roof. Analytical studies using closed-form solutions and finite-element techniques were compared to experimental results. Laboratory work includes variation of bolt length, hole diameter, and grouL type. Pull tests were pel&apos;fol·med on 4-, 2-, and I-ft bolts in holes of 1-and I-3IB-in diameters. Both polyester resin and inorganic grouts were used as the anchorage medium. Strain gauges were installed on the bolts at several locations to observe the rate of load transfer from the bolt through the grout to the rock mass when a force was applied at the bolt end using standard jack pull testing procedures and equipment. The average anchorage length of 4-and 2-ft bolts was 22 in. Grout type and hole size variations did not produce a significant effect on the rate of load transfer from the bolt to the rock.

Jan 1, 1987

By John K. Alley

Fibrous silicon carbide was produced by thermal decomposition of certain silicates contained in graphite crucibles. Induction heating was used to produce the necessary temperature and thermal gradients. Both green and white fibers were mainly the beta modification even though each color grew within a different temperature zone. Alpha silicon carbide, present in insufficient amounts for X-ray detection, was identified by electron diffraction. The white fibers formed in a zone between 1,365° and 1,634° C (±50° C). The green fibers (less contaminated) formed in a much more narrow zone between 1,650° and 1,672° C (±50° C). The average lengths and widths of microscopic fibers grown by this method were 1.5 mm/0.002 mm (white) and 1.2 mm/0.0035 mm (green); however, same fibers observed by electron microscope had cross-sectional measurements of 150 to 300 A. Both differential thermal analysis and thermogravimetric analysis showed that silicon carbide fibers oxidized in air at temperatures above 500° C. Fibrous silicon carbide was indexed as a cubic cell with the dimensions a = 4.358 A. The density calculated from X-ray data was 3.217 g/cm3.

Jan 1, 1963

By H. G. Iverson

As a part of the program of investigation of domestic sources of manganese ore, mining engineers of the Bureau of Mines examined and sampled three properties in the vicinity of Winnemucca, Nev. As the ores were too low grade for direct production of ferromanganese, they were tested for their amenability to concentration by ore-dressing methods. Two samples of ore were procured by examining engineers of the Bureau of Mines from several outcrops in the Pollard Canyon area, Pershing County, about 30 miles southeast of Winnemucca. The manganese occurs in relatively small lenticular bodies as secondary replacement deposits in chert and quartzite. The first sample represented average run -of -mine ore as exposed in the Pollard Canyon deposits. Sample 2 was composed of hand-sorted, high-grade ore.

Jan 1, 1954

By William C. Cooley

This volume contains copies of the 5 x 8 in. accession card file for all items collected which were judged to be relevant to underground hydraulic coal mining. In many cases, abstracts are included. Abstracts were taken from the source, from other reviews, or from the preliminary screening of Russian documents performed by Dr. A. L. Brichant. No attempt was made to write abstracts for every accession item.

Jan 1, 1975

By Robert C. Johnson

Single crystal whiskers of ZrO2 and TiO2 were grown by solution and crystallization of these oxides in molten baths. Mixtures of Na2B407 and LiC1 were the most suitable growth media for zirconia. Sodium borate alone and Na2CO3 plus SiO2 were best suited for titania. The solubilities of zirconia and titania in molten sodium borate were determined, Whether zirconia whiskers were dendritic or nondendritic depended on the temperature used. The best single crystal whiskers were grown below 1,100° C. Titania whiskers always grew as single crystals. The tensile strengths of zirconia and titania whiskers were about 15,000 psi and 50,000 psi, respectively. Modulus of rupture was about 49,000 psi for zirconia whiskers and 75,000 psi for titania whiskers. Chemical analyses showed the zirconia and titania whiskers to be pure. The zirconia and titania whiskers were shown by X-ray analysis to be, respectively, baddeleyite and rutile.

Jan 1, 1965

By J. H. Maysilles

The Bureau of Mines is conducting research on various technologies to recover alumina from domestic resources for feedstock to existing aluminum smelting capacity as a means to reduce dependence on imported bauxite, which represents 93 pct of U.S. aluminum requirements. One of the more promising technologies being investigated is the hydrochloric acid leaching of kaolinitic clay. In the hydrochloric acid leaching technology, alumina is recovered from iron-free aluminum chloride leach liquor and separated from impurity elements by sparging the liquor with HC1 gas to crystallize aluminum chloride hexahydrate (ACH). A large-scale crystallizer with a 336-gallon usable volume was constructed and operated to obtain engineering and design data for potential scale up and to demonstrate the ability of the technology to produce specification grade alumina. Test campaigns involving about 1,400 hours of operation were completed. ACH meeting all chemical purity requirements could not be produced by a single crystallization, but was produced by recrystallizing the product from the calcined kaolin clay leach liquor. Product crystals with a size distribution of more than 80 pct plus 100 mesh and 65 pct plus 65 mesh were made at a rate of 10 pounds of ACH/(hr)(ft3). The zirconium tube heat exchanger used to maintain constant process temperature operated with an over-all heat transfer coefficient of 420 to 500 BTU/(hr)(ft2)(°F).

Jan 1, 1981

By Patricia R. Devine

This report expands an earlier study by Jack Faucett Associates (OFR #40-88) of the same title. Both reports are based upon an interindustry analysis from 1963 through 1982, during which time U.S. metals consumption and production did not keep pace with economic growth. The report discusses three sources of change: technological change, economic growth, and composition of final demand, as well as the relative importance of the individual components of final demand for metals. The results show investment and personal consumption to be the most metal-intensive components of final demand, and technological change to be the major cause of decline in consumption growth during the study period. Technology change is defined as alterations in production processes resulting in more or less consumption of metal per unit of output, often because of material substitutions and design changes. A trade analysis shows the significance of import growth, particularly indirect imports (metal contained in imported goods) as a factor contributing to the reduced growth rate of domestic metal production. The effect of import growth is partially offset by indirect export growth, suggesting that continued increase of all U.S. exports can have a strong effect in reducing the negative trade balance in metals.

Jan 1, 1988

By Jim F. Lemons

The Bureau of Mines Minerals Availability System collected and analyzed data for 34 nonlaterite and 9 nickeliferous laterite domestic chromite deposits in order to assess their viability as sources of chromium under present technologic and economic conditions. These 43 deposits, none currently in production, contain approximately 6.3 and 22.3 million metric tons of Cr203 at the demonstrated and identified resource levels, respectively. Approximately 4.6 and 15.6 million metric tons of Cr203 are recoverable at the demonstrated and identified levels, respectively, for the 34 nonlaterite deposits. None of these resources are economically recoverable at January 1981 market prices. Production of metallurgical-grade chromite (market price $128 to $144) would require a minimum chromite market price of $237 per metric ton. Chemical-grade chromite production (market price $74 to $85) would require a chromite market price in excess of $188 per metric ton. From the 34 nonlaterite deposits, roughly 5.4 and 17.6 million metric tons of ferrochrome could be produced at the demonstrated and identified resource levels, respectively; however, a minimum market price of $770 per metric ton of ferrochrome would be required to stimulate production. The nine nickeliferous laterite deposits were not evaluated through production stages because of uncertainties in process technology and cost.

Jan 1, 1982

By P. E. King

The U.S. Bureau of Mines is conducting an ongoing research project to better understand the phenomena involved within electric arcs utilized in electric furnace steelmaking. With a better understanding of the physical and electrical characteristics involved, dynamic or predictive control of electric arc furnaces may be possible. A mathematical model is presented, but not solved, and the system of coupled equations is analyzed. Characteristic parameters are used to determine relative importance. In this manner, significant quantities are dermed. The parameters found to contribute little to the system of equations of motion are ignored. A resultant simplified system is identified, and directions for further study are indicated toward control of electric arc furnaces.

Jan 1, 1990

By W. T. Benson

In May l942, the Bureau of Mines started exploring for manganese on the Black Poch manganese property, Esmeralda County, Nev., to determine possible reserves of manganese in the deposits. The work was done by the Bureau in cooperation with the Federal Geological Survey and comprised a study of the geology, mapping the area, and exploring by trenching, test pitting, and sampling. All ore bodies were examined and sampled, and the three most important areas were explored by trenching and test pitting. This report notes the location, ownership, and history of the deposits; explains the physical features of the district; mentions briefly mine workings and metallurgy; and describes the geology and ore bodies. The Bureau erected a temporary camp, repaired 5 miles of temporary road, constructed 1,000 feet of new road, dug 3,173 foot of trenches with a vertical crone section of 4 x 10 feet and 91 test pits with a cross section 3 x 6 feet, averaging about 6 feet deep, and cut 134 samples.

Jan 1, 1950