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By E. D. Gardner

About five minutes after 3 o'clock on Thanksgiving morning, November 24, 1927, smoke was discovered coming up No. 2 shaft of the Magma Copper Co.'s mine at Superior, Pinal County, Arizona. Of the 49 men in the mine at the time, 42 were able to make their way to the outside unassisted, but 7 perished. Six bodies were recovered, and the seventh, that of an Apache Indian cage-tender at No. 2 shaft, is thought to be in the caved section between the 1,600 and 2,250 foot levels A second and independent fire broke, out in No. 1 shift about 2 a.m., November 27, burning .out the shaft timbers from the surface to the 200-foot level and destroying the surface fan and structures. About 20 men were underground fighting the fire in No. 2 shaft, but all were safely withdrawn, aril the fire in No. 1 haft was quickly controlled.

Jan 1, 1928

By K. D. Luxbacher

Understanding methane emissions in underground coal mines is critical for a safe and productive mine. In addition to reasonable estimation of initial coalbed reservoir parameters, it is also crucial that changes in effective stress due to mining and pore pressure reduction are taken into account due to their effects on porosity and permeability. Primary parameters for estimation of emissions or modeling of the mining environment for this purpose are porosity and permeability which can change dramatically as a result of stress redistribution associated with mining and gas desorption from a large coal volume. These parameters affect the emission rates and ventilation requirements, as well as water inflow into the working environment. Stopping leakage, on the other hand, is a secondary stress dependent factor in estimation of emissions, as convergence of the roof and floor strata, compromising the integrity of the stopping, may result in leakage, making prediction of ventilation requirements difficult. This paper aims to examine the effects of porosity and permeability changes of the coal seam on methane emissions in an underground continuous miner section. The models were developed and executed in a dynamic fashion to simulate an advancing section. Through this process, the changes of effective stress in coal, particularly their change paths, on porosity and permeability were incorporated into the models and methane emissions, concentrations, air requirements, water inflow and possible leakage from the stoppings were investigated using a conventional coalbed methane reservoir model.

Jan 1, 2009

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

MINE VENTLATION NETWORK ANALYSIS

Jan 1, 1977

By F. R. Cattoir, D. H. Baker

Fused - salt electrorefining has been successfully applied to the purification of vanadium metal . The electrolyte used in this refining technique was sodium chloride to which had been added 3 to 6 percent vanadium as vanadium dichloride . The average deposition current efficiency was 91 percent . Oxygen and nitrogen , the impurities in commercially produced vanadium metal , were reduced by two - thirds of the amount contained in the feed material . Hardness of the vanadium- metal product was reduced from an initial 97 Rockwell B ( RB ) to a minimum of 35 Rg . The reduction of these impurities markedly improved the plasticity of the final product obtained by melting the crystalline cell metal into small ingots . These ingots could be given a 99 - percent cold reduction by rolling before edge cracking appeared . Growing interest in high - purity vanadium and the industrial need for purer metals and improved alloys for use under high temperatures and high speeds have demanded the elimination and/or control of impurities . Accordingly, research to eliminate or control the undesirable impurities has been expanded .

Jul 1, 1960

By A. N. Styler

As part of its water-jet assisted rock cutting research, the Bureau of Mines has initiated a study into the mechanism of rock fragmentation by water-jet-assisted mechanical tools. The objective of this research is to increase coal extraction efficiency by seeking an improved understanding of the synergistic relationship between mechanical cutters and water jets, enabling the design of more effective cutterheads. Rock chips collected during laboratory traverse speed jet-assisted cutting tests were analyzed with respect to the size distribution of the chips and the forces measured during cutting. As the water-jet pressure was increased, the size distribution of the product became coarser with V-face type cutting tools producing less fine material than conical cutting tools. Fracture mechanics theory accounted for less than 10 pet of the energy consumed during fragmentation of the rock. The energy consumed by processes other than rock breakage decreased with the use of water jets and increasing advance rate.

Jan 1, 1987

By L. C. IlsLey

Cooperation between the United States Bureau of Mines and the Safety in Mines Research Board of Great Britain, continuous since 1924, has made possible this and other papers on safety subjects. Grateful acknowledgment is made to representatives of the Safety in Mines Research Board of the Mines Department for their assistance in arranging visits to several mine safety stations, and to F. R. Wynne, Deputy Chief Inspector of Mines, Great Britain, for arranging visits to mines in Great Britain, Belgium, Germany, and France. During the summer of 1927 the writer had the privilege of visiting the mine safety testing stations in Great Britain, Belgium, Germany, and France, in the order named. All of these countries have large coal mines, many of which are rated as gassy. Therefore, when installation of electrical equipment is contemplated, each of these countries is confronted with the same safety problem as is the United States - the development of electrical equipment that will not ignite gassy mine atmospheres which might, through neglect or accident surround the equipment. The means used by these countries in safeguarding gassy mines should therefore be of general interest to safety engineers of American coal mines, and it is proposed to give a brief survey for each of the four countries mentioned. This paper presents the second of these surveys, which covers conditions in Belgium.

Jan 1, 1929

By William G. Gruzenaky

The separation of yttrium and the individual rare-earth elements (lanthanons) from mixtures in which they occur has been a difficult problem through-out the years. Because of the increased interest in the various uses of these metals, the economy of their production may become of great importance. Studies relative to this problem, undertaken at the Federal Bureau of Mines Albany Metallurgy Research Center, resulted in the development of a solvent extraction method by which yttrium can be separated from the rare-earth metals. A separation factor of 10.93 was obtained between yttrium and cerium from a single-stage extraction, and a factor of 1.78 was obtained between yttrium and erbium from a multistage system. The valuable metals were extracted from euxenite by caustic soda fusion or by chlorination, and several separation methods were investigated. Partial separation of the yttrium and rare-earth element fraction was made by chemical methods and by solvent extraction. Thermal decomposition of aqueous rare-earth nitrates or selective ignition of yttrium and rare-earth oxalates yielded a fraction enriched in cerium. A fraction enriched in the light rare-earth elements resulted from a double sulfate precipitation, whereas a potassium ferrocyanide pr cipitation yielded a fraction enriched in yttrium. Precipitation with dimethyl phosphate yielded a fraction enriched in yttrium and heavy rare-earth elements. Enriched fractions were obtained with several solvent extraction systems. A system consisting of rare-earth nitrates, nitric acid, and tri-n-butylamine-3 methyl-2-butanone favored the separation of yttrium from the heavy as well as from the light rare-earth elements.

Jan 1, 1961

By A. Visnapuu

The Bureau of Mines investigated carbonyl processing techniques for the recovery of the critical metals Ni, Co, Mn, and Cr from domestic primary and secondary sources. In most cases, the source materials require reductive precarbonylation treatment to metallize the contained Fe, Ni, and Co compounds to render them reactive with CO. The critical metals were recovered either by direct conversion to the respective carbonyls or as upgraded products by carbonyl removal of an undesirable metal. Best metal-to-metal carbonyl conversion was under CO pressure, from 80 atm upward, and at 1400 C. Carbonylation was accelerated by the addition of HzS in small quantities. CO pressure, temperature, promoter and pretreatment trends, and other factors enhancing metal carbonyl formation are presented.

Jan 1, 1987

By Pablo Velasco

The Ecuadorean mineral sector and overall economy have retained their traditional dependence upon the production and export of hydrocarbon products. Exports of crude oil and its products accounted for 62% of the country's export earnings in 1985. Ecuador's major mineral commodities produced and exported were cement, gold, limestone, liquefied natural gas, liquefied petroleum gas, natural gas, natural gasoline, crude petroleum and condensate, raw steel, semimanufactured steel products, and sulfur.

Jan 1, 1987

By H. S. Caldwell

This report describes work by the Bureau of Mines on the vacuum distilla¬tion of some of the more volatile metals such as cadmium, zinc, and magnesium from lead and tin. Evacuation within a distillation apparatus allows rapid diffusion of vapor away from the evaporation surface and prevents reaction of the vapor with residual gases. A reduction of pressure to several tenths of a millimeter makes possible practicable distillation rates, at temperatures for which the partial pressure of the metal vapor exceeds 10-3 atmosphere. The rate and selectivity of distillation depend primarily on the volatility and molal ratios of the alloy metals, and their chemical activity to each other. For very rapid evaporation or low concentration of the more volatile constituent, the rate is determined by the rate of diffusion of the evaporating metal, to the surface of the melt. Cadmium, zinc, magnesium, and tellurium were found to volatilize readily from both lead and tin. Tellurium appears to volatilize as an intermetallic compound rather than the pure metal. Antimony could not be removed from lead at 1,000° C.; the condensate was nearly all lead. Antimony, bismuth, and lead were removed from tin.

Jan 1, 1960

By Martin H. Stanczyk

Ultrafine grinding of the industrial minerals mica, pyrophyllite, talc, marble, barite, and fluorite was accomplished using the Bureau-developed and patented attrition-grinding process. The materials, representing minerals of diverse physical characteristics, were batch ground in a 10-inch-diameter machine using statistically designed experimental test programs. The tests were made to determine large effects of variables such as feed pulp density, grinding medium size, and quantity of the electrical energy consumed during grinding on product particle size and bulk density. In designing the test programs, it was assumed that there was no interaction between the variables. Relatively coarse commercial flotation concentrates of mica, barite, and fluorspar and mine-run products of pyrophyllite, talc, and marble were readily ground into subsieve size ranges. Considering the great amount of particle size reduction obtained, the electrical energy requirements for grinding were very low. In general, the test results indicated that the best conditions for particle size reduction were approached when grinding with the coarser fraction of sand grinding media, the higher-sand-to-mineral weight ratio, and the higher feed pulp density.

Jan 1, 1972

This chapter summarizes data on crude mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are tables that show the principal mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume n of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output!' It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the production of auxiliary processing at or near the mines.

Jan 1, 1979

By Ronald S. Conti

Fire is a major concern for those who work in underground mines. A mine fire can occur at anytime and often results in a partial or total evacuation of mine personnel and could result in the loss of lives. Therefore, having a workforce that is well trained to prevent, detect, and fight a fire is important. This paper focuses on responders’ preparedness for fire. Responders in this context are considered the entire workforce and are categorized as first, second, and sustained responders and evacuating miners. Quality training enhances ones awareness of mine fire hazards and promotes self-confidence in combating fires and responding to emergencies. Early warning systems and other escapeway aids such as a through-the-earth signaling and communication system, lasers and strobe lights are also addressed. The technological advancements that have been made can improve the state-of-preparedness for responders to underground emergencies and increase the chances of survival for escaping personnel.

By Thomas P. Mucho, Dennis Dolinar, Christopher Mark

During the 1990s, the former U.S. Bureau of Mines conducted a number of field studies in which the performance of different types of roof bolts were evaluated in different geologic environments. The studies used a standard suite of measurements, including multipoint extensometers, strain-gauged roof bolts, and roof bolt load cells. The sites were chosen to investigate the effect of a variety of parameters, including installed tension, bolt capacity, grout annulus, and horizontal stress orientation. Although not fully successful, the measurements provided valuable insights into each of these issues. They also showed that instrumentation and monitoring have important advantages over observational methods for comparing the performance of different roof bolting systems.

Jan 10, 2000

By Oleg Terichow

The Bureau of Mines studied the penetration of a slender cylindrical tube into a sand bed, simulating seafloor material under the application of a static load. The factorial experimental design was based on three factors: tube diameter, geometry of penetrating bit, and seawater saturation of sand, all of which were found to be significant in influencing the depth of penetration. The geometry of the penetrating bit, or shoe, is of major significance in the mechanics of penetration and should be considered the most important factor for additional study. Linear regression analyses of the load-penetration data show that the relationship is linear.

Jan 1, 1970

By R. P. Vinson, Abdurrahman Cetinbas, Joseph Cervik, M. G. Zabetakis

The periphery of longwall panels in the Pocahontas No. 3 coalbed is characterized by a zone of reduced permeability that inhibits the natural drainage of methane. A residual gas pressure of 105 psig was measured after 1 year in an isolated block of coal measuring 340 by 1,100 feet. The buildup of gas pressure within such large blocks causes methane problems during plowing operations. However, natural drainage holes drilled during development have been found to reduce the gas content of the coal in this coalbed by over 90 percent. The effect of water infusion on dust during plowing operations was investigated using existing methane drainage holes. These holes were cleaned of debris and a pipe was grouted into the hole for water infusion of the panel. Both total and respirable dust levels were reduced by 40 to 79 percent. Water infusion of the panel proved more effective than did the use of a plow-mounted spray sys tem.

Jan 1, 1974

By G. M. Molinda, J. P. Ulery

Since 1970, abnormally high methane emissions have been observed in eastern sections of the Federal No. 2 Mine operating in the Pittsburgh Coalbed in northern West Virginia. The nature and volume of these emissions indicate a source other than the coalbed. An investigation was undertaken to delineate probable methane sources. Gas well information and stratigraphic correlation of corehole data indicates that a sandstone directly above the main coalbed is an additional source of methane emissions. The sandstone body appears to be an ancient stream channel, infilled with fine-grained sand and organic matter. Coalification of the organic matter produced methane as a byproduct. Additional methane presumably migrated into the sandstone unit from the subjacent coalbeds. The methane became trapped in the porous clasticunit by the surrounding impermeable strata. Mine development near this unit creates a significant pressure gradient, triggering abnormal methane emissions into the mine along naturally occurring fractures. Pre-development methane drainage of the sandstone could be accomplished by completing vertical boreholes along its trend.

Jan 1, 1984

By C. M. K. Boldt

This U.S. Bureau of Mines report presents a study of three typical tailings samples as potential cemented backfill in underground mines. The testing series was unique in that the pulp densities of the samples were all above 75 pct solids. Test results included dry density; slump; percent settling after 28 days of curing; tensile strength after 28, 120, and 180 days of curing; and unconfined compressive strengths after 7, 28, 120, and 180 days of curing. The physical properties of the various test mixtures were further analyzed using linear and nonlinear statistical methods to produce correlations and mathematical equations. Physical properties were used to determine the influence of mix additives and as input for numerical modeling studies of backfill. The mathematical relations were used as a predictive tool in determining the suitability of various materials as backfill.

Jan 1, 1989

By J. J. Henn

A process is evaluated for recovering metallurgical-grade manganese are from the low-grade manganiferous iron ores of the Cuyuna Range, Minnesota. The process, developed by the Bureau of Mines, employs high-temperature sulfatization of the are to form manganese sulfate and reduction of the are to convert the iron to a magnetic oxide. The roasted ore is water-leached to dissolve the manganese sulfate, which is then separated from the leach residue, is crystallized, and is calcined to produce the manganese product. Iron is recovered from the leach residue by magnetic separation, and is pelletized and calcined to produce byproduct iron ore pellets. The fixed capital cost for a plant yielding a product containing 100 tons of manganese per day is $19.6 million on a mid-1970 basis when the raw are contains 4.84 percent manganese. The estimated operating cost of the plant is $211 per ton of contained manganese. Graphs are included to show the effects of ore cost and varying manganese content of the raw ore on the estimated operating cost.

Jan 1, 1972

By Scott A. Stebbins

During 1981, the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral resource survey of the 6,400 acre (15,800 ha) Lincoln Creek RARE II area (No. 5983) in the Toiyabe National Forest (fig. 1). Samples of outcrops and stream channels contained no significant amounts of economic minerals. A radioactive deposit in a pegmatite dike occurs 1.25 mi (2.02 kin) southeast of the study area, hut similiar deposits have not been discovered within the area boundary. No coal or deposits were found.

Jan 1, 1982