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By Charles Anema

The Mancarried and Helicopter Receivers were developed under the contract I for trapped miner location. This program was a five phase program with 15 mancarried and 5 helicopter production receivers delivered under Phase IV and equipment documentation required under Phase V.

Jan 11, 1976

By d&apos, Kathleen J. Amico

THIS SUMMARY appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operatons at or near mines.

Jan 1, 1963

By J. Grumer

Nine dust and gaseous inhibitors of propagating coal dust-air flames (lean, stoichiometric, and rich) were evaluated in a newly developed 15-cm-id, 3.6-meter-long instrumented flame duct, under conditions such that wall quenching was virtually absent and the dust concentration was temporally and spacially uniform to within about t5 percent. Listed roughly in order of increasing efficiency, the inhibitors evaluated were rock dust (calcium carbonate), powdered oyster shells (calcium carbonate), Halon 1301 (trifluorobromomethane), Halon 1211 (difluorochlorobromomethane), sodium chloride, Super-K (potassium chloride), regular-grade fire extinguishant powder (sodium bicarbonate), Purple-K (potassium bicarbonate), and Monnex (potassium bicarbonate combined with urea). Experiments were extended to clouds containing 1 and 2 volume-percent of methane. The inhibition of lean, stoichiometric, and rich methane-air flames without coal dust was also examined in a few instances; results agreed with those obtained for coal dust-air flames.

Jan 1, 1971

By F. N. Kissell, R. J. Bielicki

The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. Air samples were collected in glass syringes and analyzed by electron-capture gas chromatography. In these studies, the lower limit of detection was about 1 part per billion by volume (ppb) of SF6 per part of air. Experiments conducted in a Pennsylvania limestone mine showed this technique useful in evaluating the effectiveness of auxiliary fans, measuring low flow velocities, probing the air circulating near a working face region where ventilation appeared to be poor, and estimating volumetric flow rates in airways of large cross-sectional area and having low flow velocities. This technique was also used in a western vein-type metal mine to measure the amount of return air being recirculated into the intake air due to leakage through old stoped areas.

Jan 1, 1974

By Oliver C. Ralston, Foster Fraas

"INTRODUCTION The predominant characteristic of powdered mica is the thin -plate shape of the particulars, and the thinner the plates, the more enhanced is this characteristic. Consequently, it is frequently desirable to grade mica according to the thickness of the plates. Concerning the various possible methods for grading mica, very little has been published. There is also no information on the relative quantities of mica per given range of plate thickness. This paper presents a graphical method that shows how these quantities are distributed and how the different methods of grading compare.CUMULATIVE BULK DENSITYBulk density, which is an indirect measure of the plate thickness, was determined in a small cylindrical cup of 3.37 cubic centimeters volume. The mica was placed in the cup under a standard procedure. The densities thus measured checked these determined in a 273 cubic centi¬meter cup with less than a 2 percent error.In calculating cumulative densities it is important to know how they are averaged. In any grading operation the bulk density of a series of fractions is determined. Starting with the lowest density fraction, the cumulative percent under-density can be calculated through the various fractions. It is possible that quantity may be measured by volume or weight and that the averaging may be done by a number of methods. However, experimentally it has been shown that the quantity must be by volume and that the averaging must be arithmetic. This is illustrated in table 1, in which the calculated and actual bulk densities are listed."

Sep 1, 1942

By W. A. Cole

The sulfur shortage that existed during the Korean conflict stimulated interest in coal measures as possible sources of sulfur. One of the areas brought to the attention of the Bureau of Mines was in Marion County, Iowa, where comparatively high-sulfur coals and other marcasite-bearing strata were known to occur. A Bureau of Mines engineer inspected the marcasite occurrence on December 4, 1954; this prompted further work on the Iowa coals and associated formations as a source of iron sulfides. An investigation of the Iowa high-sulfur coals was undertaken including core drilling, field reconnaissance, and compilation of data pertinent to consideration of the following: 1. Upgrading Iowa coal by mechanical cleaning and the feasibility of recovering sulfur from coal brasses. 2. Possibility of processing the high-sulfur coals by adaptation of methods employed in processing industrial gases to produce sulfur and sulfur products. 3. Possibility of finding concentrations of iron sulfides in associated rock formations in sufficient quantity for economical recovery.

Jan 1, 1957

By R. C. Buehl

[Improvements in refractories for high-temperature service have made possible the use of higher temperature in many processes. Consequently, it sometimes is desirable to use gases heated above 1,600° F., and for moderate rates of gas flow, there gases can be heaters best with pebble heaters. Pebble heaters of the stationary-bed type in which the chanber was lined with mullite brick and pebbles of pure alumina served as the heat-exchange medium have been used recently to heat the air blown into an experimental blast furnace4/ These pebble heaters worked well and made it possible to use air temperature up to 2,500° F. at the tuyere of the furnace. Since little has been published on this type of gas heater, a review of the construction on employed and operating data should assist in selecting applications and designing units.]

Jan 1, 1953

By V. R. Spironello

Operating variables affecting the efficiency of the basic oxygen furnace (BOF) and the level of contaminating elements in the steel product were investigated by the Bureau of Mines. Steel was made in a 400-lb-capacity BOF designed to rotate on its vertical axis to increase the area of hot metal surface subject to oxygen attack. Hot metal for the BOF was made by melting pig iron and scrap in an 18-inch (ID) cupola. The variables were BOF speed of rotation, rate of oxygen flow, number of jets and angle at which they were machined into the oxygen-lance tip, temperature of hot metal, reactivity of lime, and temperature of scrap for the BOF charge. Experiments were arranged according to a two-level fractional-factorial design. The effects of the seven variables were evaluated for 13 responses. The greatest ingot yield occurred while using the larger angle lance tip and jets. The most carbon burned per unit volume of oxygen resulted from rotating the BOF and using the smaller angle lance tip. The largest sulfur transfer to the slag occurred at the higher hot metal temperature levels and higher rate of oxygen flow.

Jan 1, 1970

By Douglas C. Peters, Valois R. Shea-Albin, Dennis R. Dolinar

An accurate assessment of the vertical stress on a coal seam at depth is important for mine design. Vertical stress calculation techniques presently available either are not sufficiently accurate or cannot handle complex surface topography. Therefore, the U.S. Bureau of Mines developed a computerized method to calculate vertical stress exerted on surfaces at depth that includes the effect of topography. Two input data sets are required: a digital elevation model containing topographic elevations and a coal seam file defining coal seam elevations at depth. Boussinesq's equation then quantifies the vertical stress resulting from topography. The computerized method was tested on a coal seam overlain by a complex topography where a vertical stress map encompassing several square miles was produced. Results show that depth mitigates the affects of surface topography, while the coal seam topography has a direct effect on the vertical stress. In comparison to the computerized method, the direct stress method overestimates stress under hills and underestimates stress under valleys. The largest difference between the two methods occurs under the steepest topographic relief. A limitation of the computerized method is that stresses cannot be accurately determined near an outcrop.

Jan 1, 1992

By E. J. Kloos

Two self-contained breathing apparatus of the closed-circuit compressed-oxygen type were evaluated for performance at 32° to -25° F. Low-temperature effects of oxygen and carbon dioxide concentration, visual properties of the facepiece, and mechanical operation of the apparatus were studied. Although operation varied with the wearer, his breathing rate, the apparatus precooling time, and the temperature, results suggest that general use of currently approved compressed-oxygen closed-circuit breathing apparatus be limited to temperatures above 32° F.

Jan 1, 1968

By T. T. Campbell

Research conducted by the Bureau of Mines demonstrated the feasibility of preparing columbium and tantalum metals by the application of Kroll-process techniques. Yields in excess of 95 percent were obtained in a modified Kroll-process reduction apparatus constructed from nickel and Inconel.4 Operating conditions during reduction and distillation were determined. Optimum temperatures during sodium reductions ranged from 650° to 750° C and for magnesium from 700° to 800° C with retort pressures ranging from 3 to 7 psig. Undesirable vapor phase reactions occurred when temperatures exceeded 750° C during sodium reductions or 850° C with magnesium. Vacuum distillation at 850° C effectively removed volatile salts and excess reductant from the reduced metals. Calculations based on the results obtained in small scale tests indicate that reaction rates of up to 34 lb/hr could be obtained during columbium reductions and up to 60 lb/hr during tantalum reductions in production scale reac¬tors. The small, laboratory-scale techniques used in this study could be adapted to commercial practice. The reduced powder or sponge metals can be consolidated by conventional arc-melting techniques, and the arc-melted metals can be fabricated into ductile sheet at room temperature. Analyses of arc-melted buttons prepared from Kroll-process tantalum or columbium showed that tantalum of greater than 99.8-percent purity was obtained and that columbium purity exceeded 99.7 percent. A significant purification of the reduced metals occurred when they were consolidated by electron-beam melting, and the purity and ductility of electron-beam-melted Kroll-process tantalum and columbium compared favorably with the commercial metals. After electron-beam melting, the purity of the tantalum exceeded 99.95 percent, and columbium purity was approximately 99.9 percent.

Jan 1, 1962

By J. C. Franklin

An experiment was conducted by the U.S. Bureau of Mines and the Canada Centre for Mineral and Energy Technology (CANMET) to measure the emanation rate of radon from cemented unclassified mill tailings in two dewatered stopes of a uranium mine at Elliot Lake, Ontario, Canada. The radon was monitored upstream and downstream and in both stopes to determine the concentration in the stopes and the amount exhausted from both stopes. The emanation rate was determined to be 0.55 pCi/cm2 sec-1 from the mill tailings, which is approximately 1,000 times higher than the average flux in the mine before backfilling.

Jan 1, 1982

By R. L. Grayson, S. S. Peng

"Research has been conducted during the past year on a study to correlate respirable coal mine dust characteristics with worker positions and coal seams. The first characteristic of respirable coal mine dust which has been addressed in the correlation study is respirable dust mass concentration. In fulfillment of this objective, two mines operating in different coal seams have been selected for respirable dust mass sampling on both longwall panels and continuous mining sections. At present, sampling has been completed on the longwall panel operating in the first mine, and one half of the planned sampling has been accomplished on the continuous mining section.The first mine sampled is operating in the Pittsburgh coal seam. The average mining height is approximately 78"" with an average of 8"" of bottom shale being mined. The mine is primarily a longwall mine, and continuous mining machines are used to support the longwall.Figure 1 shows the layout of the longwall panel which was sampled. Intake air is coursed via the track heading up to the headgate area. The air splits at the headgate. Approximately 20,000-30,000 cubic feet of air per minute (CFM) is used to ventilate the longwall face and about 5,000-10,000 CFM is routed down the belt entry. Substantial leakage across the gob was noted during the sampling period. An average of 1800 CFM per 100 feet of face leaked through the shields into the gob from #1 shield to #112 shield. A substantial amount of leakage also occurred between the #1 shield and the solid rib of the headgate development panel. The path of the air used to ventilate the panel is shown with arrows in Figure 1. Direction of air flow was opposite to the coal moving direction on the armored face conveyor.A double-drum ranging shearer is used on the face to cut a 30-inch web of coal. Normal practice is to cut from the tailgate to headgate with the leading drum raised and the tail drum lowered for cutting bottom. After reaching the headgate, the shearer is reversed and both drums are lowered for a clean-up pass. The last 40 feet of face on the tailgate is cut on the clean-up pass.The shearer is equipped with 2 banks of 4 water sprays each and 2 large sprays on the headgate end and 1 bank of 4 sprays on the tailgate end. Additionally, sprays are located above bits on the cutting drums. Actual cutting speed was approximately 14-18 feet per minute, depending on conditions.The cross sectional area for air flow on the face was approximately 60 square feet before a pass was mined and 80 square feet after a pass was mined but before the shields were advanced. The cross sectional area at the shearer was about 35 square feet.The condition of both the tailgate and headgate of the panel was good with no signs of significant roof problems. The roof conditions along the face during the sampling period were variable. At times, as much as 3 feet of drawslate fell from the roof for a span of as much as 40 shields. Generally, however, relatively local areas of falling roof were encoun-tered, usually limited to a 10-20 shield span when appearing.Ten days were spent gathering respirable dust samples on the longwall panel. Mine Safety Appliance (MSA) sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters, and constant-flow DuPont pumps were used to obtain thesamples. The pumps were calibrated at a 2 liters-per-minute flow rate. The 10-mm cyclone was selected for classifying total dust into the desired respirable fraction in order to obtain ""legally defined"" respirable dust samples for detailed physical characterization."

Jan 1, 1988

By J. O. Jones

[Willis Mountain in southeastern Buckingham County is one of several kyanite deposits its central Virginia. It is composed principally of kyanite resulting from metamorphism of siliceous sedimentary beds rich in alumina. The mountain, which trends north-south, is 2 miles long and is topped by a narrow ridge with sleep rugged sides rising to an altitude of 1,160 feet and projecting 500 fast shove the surrounding countryside. Bureau Mines engineers examiner Willis Mountain early in 1949, when bonded concentrations of coarsely crystalline kyanite were observed in the kyanite-quartzite on the northern end of the mountain and in loose boulders on the eastern slope. Commencing in late July 1949, the investigations continued on the Long Mountain segment for 11 months, ended in June 1950. A total of 600 samples from 32 diamond-drill holes, aggregating 3,876 feet of drilling, and from 255 feet of sampling in 3 trenches was assayed for kyanite and ferric oxide.]

Jan 1, 1954

By R. Ward Stahl

Fire has been one of man's most useful tools through the ages and certainly is a "must" for industrial progress but when uncontrolled is one of the most destructive agencies. This fact is even more important in a coal mine, where many persons and much expensive equipment are confined in a relatively small area. Means of escape from a burning area, as well as from the products of combustion, are often limited; and in many instances the entire surroundings are combustible. Numerous mine fires, which resulted in a high death toll and great financial loss through the years, have caused mine owners to search for the best fire-fighting equipment; much of this has been installed, the quantity depending largely upon the experience of the individual companies or neighboring mines in certain coalfields. A mine owner or operator has meager published information on the actual fire protection afforded and systems of fire-fighting inaugurated in the coalfields, by which he could compare his efforts and get some idea of the adequacy of his own protection. To further general knowledge of the subject, it was decided to survey a representative number of mines in the field and show what has been accomplished. Representative mines were selected in various coal beds; some had similar tonnage, so comparison could be made if desired.

Jan 1, 1957

By Peter F. Steidl

As part of the Bureau of Mines methane control program, the Upper Free- port coalbed was studied in Fayette County, Pa., where this coalbed lies about 650 feet below the Pittsburgh coalbed and contains the largest remaining reserves of any coalbed in the county. Coal and overburden isopachs, structure and joint pattern maps, and a fence diagram were prepared using data from gas and oil exploration logs and coal outcrops. These maps will aid in determining the need and/or feasibility of degasifying the Upper Freeport coalbed in the study area. Much of the coalbed in this area is under 600 to 1,400 feet of overburden. By correlation with data from the Pittsburgh coalbed, the gas content at depths of this order is estimated to be between 140 to 300 cf/ton of coal, for a total of 190 to 400 billion cubic feet of methane in this coalbed in Fayette County.

Jan 1, 1977

By D. J. Parker, D. Harrington, L. H. Harrison

The necessity for protection against the hazards of lightning manifests itself from time to time in the mining industry by reason of loss of life, damage to electrical equipment, fires in surface structures at mines, and accidents in the handling and use of explosives. This paper is intended to assemble, correlate, and present some of the salient. points embodied in the available literature on the subject and at the same time give some factual data concerning instances of such loss of, life and damage to property, with special application to the mining industry The annual loss of life and destruction of property by lightning is considerable; the former may be prevented to a limited extent, though use of common sense as to exposure is required and not always followed; the latter can be prevented to a considerable degree. The manufacturers of electrical equipment,, through improved types of lightning arresters,, have done much toward the protection of electrical equipment, with consequent safeguarding of life and of property. Education based on unfortunate experiences has gone far to discourage the handling of explosives and blasting accessories during thunder storms, especially in open pits and quarries, and to a much smaller extent in underground workings. The lowly lightning rod plays an important role in the protection of certain types of buildings (especially isolated buildings), stacks, monuments, and other structures. LIGHTNING PHENOMENA In 1751, Franklin proved that lightning was simply a visible display of electricity - an extended spark; and until a generation ago little had been added to his exposition, to define the various phases of the phenomenon. Matters pertaining to lightning are discussed in the following references:

By Maurice Deul, Herbert H. Fields, John H. Perry

The Bureau of Mines has been promoting health and safety in mining since its establishment in 1910. One area of research covers methane control in coalbeds; this report describes a multipurpose borehole used for both degasification and the production of commercial-quality gas. The multipurpose borehole was drilled into a barrier pillar, and seven horizontal degasification holes and one pressure point hole were drilled radially out from its perimeter. On January 28, 1974, after 505 days of degasification, a compressor was installed to the exhaust stack of the multipurpose borehole (2), and pipeline--quality gas was introduced into a commercial pipeline. As of February 4, 1975, over 171 million cubic feet of gas had been purchased by the gas company. The in situ pressure at a depth of 200 feet into the coalbed and the average gas flow and water flow from the degasification holes as they were completed and closed off were 203 psig, 1,200,000 cfd, and 6.8 gpm, respectively. Twenty-four hours after the seven holes were connected through individual pipes to the atmosphere, the total gas and water flows and the in situ pressure dropped, respectively, to 971,000 cfd, 1.3 gpm, and 18 psig. Five hundred days later, the corresponding values were 620,000 cfd, 0.15 gpm, and 10.5 psig. Daily flows have been as high as 800,000 cfd, and as low as 360,000 cfd, during the last 500 days. On February 4, 1975, after 882 days of degasification, 576 million cubic feet of gas had been removed from the Pittsburgh coalbed; apparently a much larger area of virgin coal is being degasified than is defined by the holes. This study indicates that horizontal boreholes drilled into a coalbed from the bottom of any shaft will effectively remove gas from the Pittsburgh coalbed.

Jan 1, 1975

By Nicholas P. Kripakov

The U.S. Bureau of Mines examined the applicability of existing material models to solve practical geotechnical mining-related problems by solving a yielding pillar stability problem considering confining effects on strength. Numerical difficulties normally encountered with modeling strain softening behavior were eased with a simplified computational procedure using a quasi-elastic approach to account for residual strength after initial failure. Although in agreement with a confined-core pillar design method using actual mine conditions that include mine layout geometry, overburden geology, and rock properties of the deposit and surrounding structure, the results cannot be verified because measured field data are not available at this writing.

Jan 1, 1981

By Rose L. Ballard

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are the tables that show the principal nonfuel 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 II 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 output from auxiliary processing at or near the mines.

Jan 1, 1985