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By M. Kanda, W. D. Bensema, J. W. Adams

Two different techniques were used to make measurements of the absolute value of electromagnetic noise in and above an operating coal mine, McElroy Mine, located near Moundsville, Nest Virginia. The electromagnetic environment created by 300 volt dc and 480 volt ac machinery was measured. In one technique noise was measured over the entire electromagnetic spectrum of interest for brief time periods. The noise was recorded using broadband analog magnetic tape. The noise data was later transformed to give spectral plots. In the other technique, noise amplitudes were recorded at several discrete frequencies for a sufficient length of time to provide amplitude probability distributions. The specific, measured results are given in a number of spectral plots and amplitude probability distribution plots.

Jan 6, 1974

By G. M. Potter

During investigation of the occurrence of manganese deposits in the western United States, the Bureau of Mines collected 2-ton samples of 4 ores from 3 properties in northeastern Nevada. Laboratory tests were made to determine the amenability of these ores to ore-dressing methods of concentration. The Caviglia-Vietti property is situated 11 miles southeast of Ely, White Pine County, Nev. The ore deposits are lenticular veins and irregular masses found in limestone fracture zones and along the contact of limestone and underlying shale. Two samples, of the ore were tested: Lot A, from the Vietti shaft, and lot B, from the. Caviglia shaft.

Jan 1, 1954

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

Reduce well construction and operation costs associated with in situ leach mining while increasing mineral recovery. Approach To accommodate the size of centrifugal pumps presently in use, in situ leaching production wells are typically drilled to 6 inches in diameter, while monitor wells are drilled to measure 4 inches in diameter. However, in order to reduce the cost of drilling these larger diameter wells and to increase recovery, the Bureau has developed jet pumps which have smaller diameters than centrifugal pumps of the same capacity. This allows both production and monitor wells to be drilled smaller. Bureau estimates indicate that the cost of drilling a 3-inch-diameter production well at in situ leaching operations would be about 35 percent less than the cost of a 6-inch well. Similarly, the cost of drilling a 2-inch-diameter monitor well would be about 26 percent less than the cost of a 4-inch well. Such significant savings in the cost of drilling these wells would effect a substantial reduction in total capital cost. Use of the new jet pumps can also increase the percentage of recovery because less costly wells allow closer well spacings, improving the distribution of the leach solution. How the System Works After the borehole is cased, the new small-diameter jet pump, along with piping and accessories, is installed and connected to a centrifugal pumping unit on the surface. High-pressure water from the surface pump is forced through a nozzle into the venturi of the jet type pump injector. This jet action lifts the leach and mineral-bearing solution to the surface.

Jan 1, 1984

By James W. Myers

The Bureau of Mines studied factors affecting ignition of coal mine refuse and on methods for control of burning. Laboratory experiments showed that air permeates more readily through segregated than through nonsegregated refuse and that air permeability is greater through coarse than through fine particle refuse. Minus 3-1/4-inch refuse ignites spontaneously more readily than minus 1/4-inch refuse. The burning of a 1,000-pound conical coal pile was con-trolled by capping with an 18-inch-thick layer of minus 1/4-inch refuse containing 37 percent combustible. In field trials, the burning of refuse at operating mines was controlled by capping with a layer of fine refuse. Water, applied as a spray or by injection, quenched surface flames and cooled the burning waste. Inspection of refuse piles at operating mines showed that the spontaneous ignition tendency is affected by the exposed surface relative to the total volume and the segregation of particles during dumping.

Jan 1, 1966

By Richard A. Dick

Eight blasts were fired in a 2-1/2-ft bench in the Stewartville member of the Galena Limestone formation in an aggregate quarry near Stewartville, Minn. The shots were dimensionally proportional to production-size bench blasts and were about 5 to 10 percent of full scale. The effects of site, timing of initiation, and burden-to-spacing ratio were studied in a 2 x 2 x 2 factorial experiment, using three boreholes, caw;, containing a 1/2-in charge diameter of high-density ammonia dynamite, in each blast. Detonation velocity measurements indicated that the dynamite detonated satisfactorily in the 1/2-in charge diameter. The effects of the three experimental variables were analyzed by weight for the percentage of oversized material produced and for size distributions determined by screening the entire muckpiles. The bench faces were painted before each shot in an effort to determine the origin of the oversized material. The square pattern (burden and spacing = 15 in) produced finer overall fragmentation and less oversized material than the rectangular pattern (burden = 15 in; spacing = 22-1/2 in). Sites 1 and 2 were about ft apart. Although site 2 produced slightly better overall fragmentation than site 1, the amounts of oversized material produced showed no significant difference. The timing of initiation (instantaneous or delayed) did not significantly influence the overall fragmentation or the amount of oversized material produced.

Jan 1, 1973

By Seth T. Reese

THE INJURY DATA and experience at coal mines in the United States for 1951 are presented in this bulletin under the following general heads: (A) General injury experience: Tables 1 to 18: Contain current data on number of fatalities and nonfatal injuries, frequency and severity rates, average severity, major and detailed injury agencies, and distribution of injuries by part of body and days of disability. (B) Selected injury data: Tables 19 to 43: Contain current data on various selected factors of operating and physical conditions that contributed to the occurrence of injuries at bituminous-coal, lignite, and anthracite mines. These factors include extent of hand and machine loading, size of mine by employment and production groups, thickness of bed or vein, duration and number of work shifts, rating of mine as gassy or nongassy, types of cap lamps, explosives, and combination of factors that influence mine safety. (C) Injury experience by States: Tables 44 to 50: Contain current data on number of fatalities and nonfatal injuries, frequency and severity rates, average severity, major causes and principal agencies, injury records of all coal-producing States, and the relative standing by States according to injury-frequency rates. (D) Major disasters: Table 51: Lists the coal-mine disasters that occurred during 1951, giving location, source, and cause. A major disaster in coal mining is defined as a single accident in which or as a result of which five or more men lost their lives. (E) Historical coal-mine injury experience: Tables 52 to 86: Contain data on injuries, injury-frequency rates, employment, and production at bituminous-coal, lignite, and anthracite mines from the earliest records through 1951.

Jan 1, 1955

By T. E. Bernard

The CO2-absorbent canisters used in four approved rescue breathing apparatus were investigated. A breathing machine was used to simulate human expiration with gas flow rates of 26, 37, and 48 1/min of 3.5% CO2 in air. The exit gas CO2 concentration, the pressure drop across the canister, and the exit-gas temperature were monitored. The absorbent capacities of the packed-bed canister designs were found to be dependent on flow rate within the range studied, while the capacities of the other designs were less affected. The radial canister had the least resistance to breathing while the complex bed design proved to be the most effective in utilization of the chemical. The overall results indicated that LiOH (lithium hydroxide) has the highest capacity for CO2 absorption among the absorbents tested. It can be used in a simple packed-bed design while maintaining acceptable levels of resistance and exit-gas temperature. Examination of oxygen supply with respect to CO2-absorption capacity suggested that it is desirable to closely match CO2-absorption capacity with the avail-able O2 supply to minimize the size and weight of rescue breathing apparatus.

Jan 1, 1979

By W. W. Odell

Engineers interested in the manufactured-gas industry have witnessed p pronounced improvements in gas-generating equipment and marked changes in operating procedure during the past decade. In spite of these changes, however, the trend of development in the near future seems to be doubtful. Uncertainty exists mainly because no one can yet accurately calculate the number of years which will elapse before petroleum products become too expensive for, general use in making gas. Research in this field has been active, and the ultimate results are awaited with interest. Some engineers predict that in the future coking coal will be carbonized on such a large scale that coal gas will be used (straight or modified) for city distribution; others maintain that gas oil will be used in large quantities in the production of base gas; they believe that it will be economical to use oil even at appreciably higher prices. The question involves, among other; factors, consideration of initial and relative costs of equipment, flexibility of operation, salability of coke, cost of distributing different gases, and the relative value of by-products, It is common belief that for many years large quantities of oil will be used in gas-making, particularly in the generation of peak gas or that water gas will be used for the synthetic production of hydrocarbons to enrich additional water gas. In this paper interest centers in a discussion of the practicability of employing synthetic processes in view of reported investigations of the chemistry of the synthetic reactions. For many years it has been known that the chief components of water gas would react chemically under proper conditions to form methane. As long ago as 1903 a patent3 was issued in this country for a gas-making process which included the synthetic production of methane. More recently the studies of numerous investigators here and abroad have shown that besides methane it is possible to produce other paraffins, olefins, and additional, materials adaptable for enriching water gas or for other uses. The question arises: In what manner, if at all, can such processes be incorporated, as a part of the gas-making scheme in a city-gas plant?

Jan 1, 1928

By Paul M. Tyler

In 1939, American industry got, off to a poor start, slowed down further during the first quarter, quickened after May, speeded up still more when war broke out again in Europe, and ended the year at a pace close to an all-time record. The average index of general business activity for the entire year (105) was well ahead of that for 1938 (86), failed to equal that of 1937 (110), and fell behind the average for 1929 (119) by a wide margin. (Federal Reserve Bank yearly indexes in parentheses).

Jan 1, 1940

By T. E. Hill

The Bureau of Mines investigated the possibility of physically separating Missouri and Minnesota granites into commercially usable fractions of feldspar, quartz, and mica by mineral dressing techniques. The probability of r covering a feldspar fraction from raw granite suitable for commercial uses was developed through correlation of the iron oxide content by extensive petrographic studies. This probability evaluation also included Wisconsin granites and a high-feldspar iron ore concentration tailing from Missouri. Laboratory recoveries of feldspar and quartz were on the order of 80 percent. Mineral content of each fraction was generally over 95 percent, indicating excellent response to separatory techniques, Acid leaching of feldspar and quartz concentrates to remove iron oxide improved the grades chemically; however, occluded iron oxide particles in the leached products prevented attaining top grades of feldspar. Mica was removed as scrap grade at low recoveries. Each concentrate conformed to some category of commercial feldspar, quartz, or mica.

Jan 1, 1969

By Gene Asai

The Bureau of Mines investigated the caustic extraction of alumina and soda from retorted dawsonite-bearing oil shale, as part of a program to devise technology for treating alternative domestic sources of alumina for the production of aluminum metal. Colorado oil shale yielding 13 pct oil (35 gal/ton) and containing 12 wt-pct dawsonite (representing about 4 pct extractable alumina) was retorted to obtain oil-free (spent) shale Spent shale was leached with dilute NaOH to determine the effect of particle size, retorting temperature, leaching variables, and storage conditions on extraction of alumina and soda and dissolution of impurities. Maximum alumina and soda extractions were obtained by promptly leaching minus 28-mesh spent shale, obtained by retorting raw shale at about 5000 C, with 0.5N NaOH. Under these conditions, dissolution of impurities such as Ca, Fe, Ti, and P was low. Leaching tests were made on spent shale stored for periods of up to 30 days at 0° to 42° C and at 0 to 100 pct relative humidity (RH). These tests indicated that significant reductions in alumina extraction would occur if spent shale were stored in ambient Colorado air under naturally fluctuating temperature and humidity.

Jan 1, 1983

By Andrew Allan

During recent years underground production for the Pennsylvania anthracite region has reached the lowest output per man per day figure of the last decade and a half. This fact, combined with increased unit costs for labor and material, has forced the market price of anthracite ever higher. Over the years the mines have become deeper, and haulage distances have increased, thus adding to the mining costs. The industry now recognizes the need for new mining techniques to offset increasing costs. The Federal Bureau of Mines, through its Anthracite Research Laboratory, is engaged in a program of underground-mining research in cooperation with anthracite-producing companies to aid in reestablishing the economy of the region by introducing methods and/ or machines that will reduce underground-mining costs and, at the same time, enhance the safety of the workmen.

Jan 1, 1953

By L. B. Pankratz

Thermodynamic data on carbides, nitrides, and other selected substances were reviewed, evaluated, and compiled at the U.S. Bureau of Mines Albany Research Center. Values for Cp°, S°, H° - H°298, -(G° - H298)/T, ?Hf, ?Gf, and log Kf are given in tabular form. Cp°, H° - H°248, ?Hf°, and ?Gf° are also expressed algebraically.

Jan 1, 1994

By Travis Q. Lyday

Australia was one of the world's principal producers of minerals and metals, and its minerals industry was a leading catalyst in promoting growth of the country. Australia was the world's largest producer of alumina, bauxite, diamond, ilmenite, monazite, opal, rutile, sapphire, and zircon. It was the premier exporter of alumina, coal, ilmenite, refined lead, monazite, rutile, and zircon, and was the second leading exporter of iron ore, after Brazil. Ranking behind China, the United States, the U.S.S.R., the German Democratic Republic, Poland, and the Federal Re-public of Germany, Australia was the seventh largest producer of coal (all grades) in the world. Australia was the fourth largest gold producer in 1988, after the Republic of South Africa, the Soviet Union, and the United States. It was the second largest producer of zinc, the third largest producer of nickel, the fourth largest producer of uranium, and the seventh largest producer of copper. 2 The country's mineral wealth was so extraordinary that it was virtually self-sufficient in most mineral commodities. Endowed with abundant resources of coal, natural gas, liquefied petroleum gas, and uranium, Australia was one of the few market economy countries that was a net exporter of mineral fuels. About 90% of Australia's consumption of crude oil was supplied by domestic production; this was expected to decline significantly about 1990, unless significant new oilfields were discovered.

Jan 1, 1990

By W. A. Calhoun

A method for treating high-iron Arkansas bauxites for recovering both abrasive and metal-grade bauxite has been developed by the Bureau of Mines. Present practice usually produces a reject containing appreciable quantities of metal-grade bauxite; however, the processing renders the alumina in the reject unsuitable for the Bayer extraction treatment. Thus the Arkansas abrasive bauxite industry has, in the past, produced little or no metal-grade bauxite. The present investigation was made to determine the possibilities of batter utilization of those particular bauxites through recovery of the wasted metal-grade portion. The large expansion of aluminum-production facilities planned for 1951-53 makes recovery of metal-grade bauxite from presently treated abrasive and marginal abrasive ores en especially timely objective and a welcome addition to our aluminum potential. The quality of the Arkansas bauxites and the inherently associated titania content have made this material particularly attractive to the abrasives industry. however, the gradual depletion of natural abrasive-grade bauxite reserves in this area, the comparative scarcity of high-grade ore, and the difficulty of maintaining adequate reserves have necessitated blending different grades of bauxite calculated to meet specifications. Production of abrasive-grade bauxite from tile, high-iron reserves 13 becoming, increasingly necessary. In one commercial operation, producing abrasive-grade from ores averaging slightly less than 10 percent Fe2O3, approximately 2.7 tons of ore are required to produce 1 ton of abrasive-grade bauxite. The reserves of ore of this grade, however, have been considered inadequate for a long-range production, and ultimately ores averaging 12 to 15 percent Fe2O3 will have to be treated to moot the continued demands of the abrasive industry.

Jan 1, 1952

By S. M. Shelton, R. B. Fisher, M. M. Fine

"INTRODUCTION The Batesville manganese district lies in the southern part of the Ozark region, mostly in Independence County but partly in Sharp, Izard, and Stone Counties of north central Arkansas.Oxides, carbonates, and silicates of manganese are found in the district. 4/ Carbonate ores have been mined from time to time, but the reserves of potentially commercial ore are chiefly black manganese oxide minerals.The district has produced manganese ore for many years. lip to and including 1933, 160,804 long tons of ferruginous manganese ore (10 to 35 percent manganese) and 140,277 long tons of metallurgical ore (35 percent or more manganese) were shipped;./ most of it was wad orThe term ""wad ore,"" used locally to designate the soft, clayey de¬posits of oxide ore, is a partial misnomer. The ores contain a soft, low-specific-gravity mineral of indefinite composition, which can be designated as wad, but coarse and fine particles of psilomelane and hausmannite, with a smaller proportion of braunite, pyrolusite, and indefinite manganese silicates, are also present. Large and small lumps of high-grade, hard manganese oxide minerals are found, frequently embedded in a soft, black matrix of fine particles of manganese oxides mixed with gangue."

Jul 1, 1942

By A. J. Barry

This report presents observations made by Bureau engineers regarding hydraulic-powered roof supports that are currently being used or have been used on nearly all operating longwalls in the United States, A comparative summary of specifications for various types of powered supports with a brief description of the mine conditions has been compiled to enable mining engineers and mine operators to readily evaluate the differences in design data. Some of the support data furnished in the field may vary from those listed in manufacturers' brochures because of the trend to customize various support components to meet specific mine conditions. A method of estimating support requirements for different assumed operating conditions is presented. Similar computations for specific mine conditions may be used to make preliminary estimates of support requirements.

Jan 1, 1969

By P. S. Haury

"INTRODUCTION Preliminary examinations of the Mohawk zinc prospect were made by John 14. Price and the author in July, August, and September 1943. Considerable quantities of oxidized lead and zinc minerals were found in old shallow work¬ings along two faults - one an over thrust fault with Paleozoic limestone in the hanging wall overlying Cretaceous shale and arkose in the footwall of the fault, and the other a bedding fault in the Paleozoic limestone.The chances appeared good for finding important lead-zinc sulfide ore bodies at 200 to 300 feet beneath the surface, so exploration in three steps by the Bureau was recommended:Surveying, mapping, and character sampling of the outcrops with topographic and geologic mapping of the immediately surrounding area.Preliminary drilling of four test holes, aggregating about 1,500 feet, to locate the top of a possible sulfide ore zone and determine the thickness and intensity of the sulfide mineralization.Contingent upon favorable results of the second step, diamond drilling of about 6,300 feet of additional hole to explore the sulfide ore bodies.The outcrops were surveyed and sampled, a topographic map was made of the area, and the geology was mapped. A project was set up for preliminary drilling of step 2 in the fiscal year 1944-45. An access road to the drill sites was built in April 1945. Diamond drilling was started on April 28 and completed on September 25, 1945, under the supervision or the Bureau of Mines. The exploratory work is covered in this report."

Oct 1, 1946

By A. C. Johnson

The T. L. shaft of the Eureka Corp., Ltd., near Adams Hill, Eureka, Nev., was sunk in 1954 and 1955 to permit exploration and development of the lead-zinc-silver ore that had been indicated by drilling. This paper describes the sinking of the 4-compartment, vertical shaft to a depth of 1,127 feet and includes pertinent details of equipment, methods, and costs. A shaft crew of 10 men, supplemented by 13 hoistmen, topmen, carpenter, and shop crewmen, sank and timbered the 1,127 feet of shaft in 630 workdays. Total labor per foot of shaft was 107.95 man-hours. Supplies per foot of shaft included 20 pounds of explosives, 1.61 pounds of drill steel, and 200 board-feet of timber. Power consumption, including that required for pumping, averaged 3,726 kw.-hr. per foot.

Jan 1, 1958