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By Earl R. Maize

This is the first of a series of reports dealing with development of a method of strengthening bituminous-coal-mine roof. Later reports will describe the progress made with injecting high cohesive and adhesive bonding agents into bedding planes and mine tests of roof strata strengthened by the bonds formed. The concept of strengthening roof strata in coal mines by inserting steel rods in the form of bolts has been widely accepted by the coal industry. The benefits of increased production and safety derived from this type of roof support has more than justified the increased cost of roof bolting. However, not all coal-mine roof structure is amenable to this type of support, and failures occur owing to the heterogeneity and variable character of mine-roof strata.3/

Jan 1, 1957

By H. Tomlinson

The development of the Sevier Valley Coal Co.'s mine marks the opening of the Salina Canon coal district in Utah. The mine is favorably located with respect, to the existing markets of the West, and if the present estimates of the amount of workable coal in it are accurate it has many Important advantages in favor of its development. This mine is situated 18 miles east of the town of Salina, Sevier County, Utah, which at present is the nearest shipping point oh the Marysvale branch of the Denver & Rio Grande Western Railroad, and is about 152 miles south of Salt Lake City, which is the distributing center for much of the coal from the Carbon - Emery coal field and is the place from which nearly all Utah coal shipped to San Francisco and points on the northern Pacific coast has a common haul.

Jan 1, 1930

By John R. Shattuck

Preliminary examination of the McCormick chromite property was made by the Federal Geological Survey and the Bureau of Mines during the spring and summer of 1943. In October 1943 an exploratory project was undertaken by the Bureau in cooperation with the Survey and was completed in February 1944.The urgent need during the war for high-grade lump chromite such as produced at the McCormick mine, was one of the pertinent reasons for the project. The McCormick mine is situated about 12 miles southwest of the town of Sonora, in the foothill belt of the Sierra Nevada Mountains, Tuolumne County, Calif. The chromite occurs as irregularly shaped lenses in masses of dunite contained in a steeply dipping, sheared, serpentinized zone of peridotite, near a contact with granodiorite.

Jan 1, 1949

By J. A. Lamonica

The Bureau of Mines studied two types of approved coal mine dust personal samplers to determine the effect of decreasing the amplitude of airflow velocity fluctuations on cyclone performance. Results indicate that more dust is collected when pulsation free flow is used. Velocity fluctuations were reduced by means of a pulsation damper; damper efficiency of about 85 percent was needed to reduce the fluctuations to an acceptable level. The data were obtained employing both pulsating and non-pulsating flow. A comparison was made of (1) the masses of respirable coal dust as determined by weighing and of (2) the particle size distributions as determined by an electronic counter. An empirical relationship is given between the ratio of masses collected using pulsating and nonpulsating flow (M') and the ratio of the maximum air velocity to the minimum air velocity (V') as measured in the cyclone entrance channel.

Jan 1, 1972

By Sidney Katell

Several systems have been proposed for the production of synthetic crude oil from oil shale. An economic analysis of one proposed system is presented in this paper. An oil shale complex to produce 100,000 barrels per calendar day of semirefined crude oil will require a capital investment of $426,216,400. This investment includes mining, retorting, intermediate pipelining, and partial refining. A selling price of $3.74 per barrel of product will be necessary to maintain a discounted cash-flow rate of 12 percent.

Jan 1, 1971

By Thomas M. Barczak

he stiffness characteristics of longwall shields were investigated in this Bureau of Mines study. Since longwall strata activity is characterized by roof-to-floor and face-to-waste displacements, a model with two degrees of freedom was used to describe the load-displacement relationship of the shield structure. The model considers the support as an elastic body and relates horizontal and vertical resultant forces acting on the support to associated displacements as a function of the stiffness of the support structure. Stiffness coefficients under full canopy and base contact configurations were determined by controlled displacement loading of longwall shields in the Bureau's Mine Roof Simulator (MRS). Three two-legged longwall shields of different manufacture were investigated. The stiffness characteristics of these shields were evaluated relative to two parameters, namely, shield height and setting pressure. The test results indicate a reduction in shield stiffness for increasing height. Setting pressure was found to have less of an effect on shield stiffness, producing only a slight increase in stiffness as setting pressure increased. Similar trends were observed for all three shields, indicating a similarity in stiffness characteristics for shields of the same basic configuration.

Jan 1, 1988

By N. F. LeJeune

For a number of years the Bureau of mines has conducted semi-annual surveys to determine the changes in the characteristics of the motor gasoline being sold in the United States. The Bureau of Mines surveys, from April, 1917, to January, 1943, indicated a progressive decrease in the end point range. The survey for July, 1923 showed an interruption in this progressive decrease. This interruption, as shown in Table 1, in the line marked "Difference," was apparently a definite one, for the data obtained in the surveys of July, 19233, January, 19244, and the present one, apparently substantiate it. The figures in Table 1 were obtained by averaging the end points of the least volatile and most volatile samples of gasoline. For example, of 850 samples analyzed in 1919, the 10 per cent (85 samples) having the highest end points and the 10 per cent having the lowest end points were grouped, and the end points of each group averaged. These averages are represented in the table as the "Maximum 10 per cent" and the ?Maximum 10 per cent," respectively. The same scheme was used on the succeeding surveys.

Jan 1, 1924

By John P. Harmon

A group of organic chemicals, known as wetting agents, has been developed, primarily for use in the textile industry. These chemicals have the property of reducing the surface tension of water when mixed with it in very dilute solutions. The advantage of lowered surface tension is recognized in dust-control work, and several wetting agents, have been tried by dust-control engineers with varying degrees of success. It is well-known that certain solids, coal for instance, are extremely hard to wet with plain water because of the high surface tension of water and the water-repellent action of coal. If the surface tension of the water is reduced, it can be demonstrated that the coal can be wetted easily. This is accomplished practical and at law cost by dissolving a very small percentage of wetting agent in the water that is to be used for wetting purposes. (Care should be exercised in using a wetting agent to be sure that it will not interfere with a subsequent process.) For some time, the comparative efficiency of various wetting agents has been the subject of considerable work by dust-control men at coal mines, as well as by members of the Bureau of Mines 3/, 4/, 5/, 6/. In this connection, a number of samples of air-borne dust have been collected in the mines. With the exception of dust-control measures conditions of dust generation and dissemination were maintained as, nearly uniform as possible. Samples were collected when water alone was sprayed on the cutter bar of a mining machine; various wetting agents were then successively added to the water and more samples of air-borne dust were-collected.

Jan 1, 1946

By Thomas M. Barczak

This report describes a study that examined load transfer mechanics in longwall shield supports as part of the Bureau of Mines research program to optimize support design and utilization. The objectives of this study were to determine the contribution of the leg cylinders and the caving shield-lemniscate assembly towards full shield vertical and hor-izontal load resistance capability and to determine how the interaction of these members affect overall shield response. Load-displacement characteristics of the leg cylinders and the caving shield-lemniscate assembly, independent of the full shield, were evaluated from controlled displacement tests in the Bureau's mine roof simulator and responses were compared with full shield responses to identify load transfer mechanics. It is concluded from this research that the participation of the caving shield-lemniscate assembly significantly affects the response of the shield support. It is likely that the caving shield-lemniscate assembly is not participating fully in current shield designs because of translational freedom in the numerous pin joints. It is also concluded that the shield will respond differently to different boundary condi-tions resulting from interaction with the strata. This report describes load transfer mechanics of shield supports and the implication of these research findings on shield design and utilization.

Jan 1, 1988

By Robert M. Becker

A multistage probability model for assessing the reliability of mineral samples following any number of stages of sample reduction is presented. Sample reduction is the process of alternately crushing or grinding and sampling mineral particles prior to assaying. The final multistage model developed accurately describes the ideal sample reduction practice. This model is based on previously developed and experimentally tested models for a single stage of sampling. The problem is approached through the probability distributions for the various stages of sampling. The probability distribution, moments, and moment relationships for a single stage of sampling are first reviewed, and the useful concept of unit moments is defined. In presenting the models for two stages of sampling, emphasis is placed on the physical description of the sample reduction process which leads quite naturally to its mathematical representation. In this representation, crushing or particle-size reduction between the stages of sampling is viewed as a random process with respect to the number and proportion of particles of the various kinds produced. The physical and mathematical description is extended to more than two stages of sample reduction, and the first three moments for any number of stages are developed. In common sample reduction practice the effects of a finite population (finite amount of material) at each stage of sampling appear to be important in describing the variance contribution of each stage. This is also true for the third moment about the mean. An example is cited in which the skewness increases by more than an order of magnitude when several stages of sampling are considered. This is largely due to the dependence of the multistage third moment about the mean on the variance. In general the model and results should be useful in helping to understand, control, and reduce the random errors that arise in the sample reduction process.

Jan 1, 1968

By Sumner M. Anderson

ATHOUGH scattered signs of increased activity in the mining industry accompanied an incipient improvement in the overall economic situation during the latter months of 1963, production levels for the year as a whole responded to the general 1962-63 business recession with a 4.2 percent decline. The petroleum industry, active since 1907, did not become a dynamic force in the economy until exploration and drilling contracts were concluded with private companies in 1958 and 1959; on November 15, 1963, having virtually achieved self-sufficiency in petroleum in the preceding year, those contracts were unilaterally annulled. In the field of metallics, the only approach to internal sufficiency-aside from the iron and steel industry that has depended heavily on the importing of basic raw materials-has been in mining, smelting, and refining lead and zinc although iron ore, silver, beryllium, tantalite, and tungsten have been mine production items of economic significance. Reserves of lead, zinc, silver, bismuth, vanadium, and low-grade and metallurgically difficult iron ore-as well as those of beryllium, tantalite, and tungsten which are produced primarily for export-appear to be fairly abundant. The exploration of deposits of copper, cobalt, tin, lithium, gold, manganese and uranium has been undertaken on a relatively small scale, and little precise information is available on the extent of reserves. Argentina is dependent on foreign sources for part of its required iron and steel and, except for lead and zinc, most of its nonferrous metals. Nonmetallies and solid fuels present an exceptionally varied array of production items among which cement had the second largest 1963 output in South America. Borates, bentonite, common clay, diatomite, fluorite, granite, lime, limestone, obsidian, onyx, rhodochrosite, salt, and spodumene ordinarily are produced for export either exclusively or in excess of domestic consumption requirements. Barite, cement, chalk, gypsum, marble, and mica are both exported and imported. Argentina depends entirely or partly on imports for coal and coke, certain special types of clay, mineral abrasives, graphite, magnesite, mineral fertilizers, sulfur, talc, and minerals for construction, the last group being chiefly attributable to convenience of river transport from Uruguay.

Jan 1, 1964

Part Two of this report is based upon six working memoranda prepared during the first half of 1972 at an early stage in our work for the Bureau of Mines. This work presents preliminary performance estimates of baseband voice and narrowband through-the-earth electromagnetic communications systems of principal interest to the Bureau for operational/ emergency mine communications applications. The calculations were prepared to obtain early indications of the feasibility and governing parameters of such communications systems. They are based on limited, but pertinent, coal mine electromagnetic noise data acquired to-date by Bureau of Mines contractors; on theoretical signal-attenuation characteristics for two transmitter antenna types of present interest to the Bureau and on semi-empirical models which describe the intelligibility of voice communications as a function of the frequency variations of the signal-to-noise ratio across the voiceband. This work examines the cases of baseband voice and narrowband communications for uplink and downlink transmissions, for frequencies up to 3kHz. Downlink transmissions are via a horizontal wire antenna, and uplink transmissions via a vertical-axis loop antenna, for typical mine depths of 300, 600, and 1000 feet. Representative coal-mine overburden conductivities of 10-2 mhos/meter (moderate and common) and 10-1 mhos/ meter (high) were used; the former figure for both voice and narrowband calculations and the latter for narrowband calculations only. Examples of high, moderate, and low, surface and subsurface, harmonic and broadband-impulsive noise conditions were taken from NBS and Westinghouse (WGL) mine noise data, together with examples of high- and low-levels of ELF atmospheric noise taken from M.I.T. Lincoln Laboratory data. The effects of simple voice spectrum shaping techniques on the intelligibility of through-the-earth voice communications are examined, and indexes of intelligibility more broadly based than signal-to-noise ratio are discussed. Finally, a means of overcoming the affects of 60 Hz noise and its harmonics which are the largest contributors to typical audio frequency in-mine noise, is suggested. These feasibility calculations are not intended to serve as definitive and complete treatments, but as a starting point: to establish first-order estimates of the magnitude and variability of transmitter power requirements under different noise, overburden conductivity, and mine depth conditions; to identify relationships, conditions, or frequencies that are likely to limit or enhance system performance; to reveal items requiring further investigation and data still required; and to suggest practical methods for optimizing system performance. These objectives were met by the calculations. Simple experiments to support these calculations can and should be carried out; together with more detailed investigations of specific modulation, coding, noise-suppression, voice-compression and signal-conditioning techniques, aimed at producing through-the-earth operational/emergency mine-communication systems that are not only effective, but practical and economically sound.

Jan 1, 1974

By P. G. Clites

This study was undertaken to determine the effect of consumable-electrode vacuum arc melting on the properties of copper and to determine the applicability of the process to the production of cast shapes of copper. Ingots and castings were produced from electrolytic tough pitch copper (ASTM designation ETP), from electrolytic cathode copper (ASTM designation CATH), and from oxygen-free copper (ASTM designation OF). The products of this study were evaluated to determine the effect of the melting process on the removal of impurities from the copper and on the physical properties of the copper. The results indicate that consumable-electrode arc melting can be satisfactorily applied to the melting and casting of copper. Ingots prepared directly from electrolytic cathode copper contained slightly higher levels of impurities than are found in commercial oxygen-free copper, Excellent results were obtained with centrifugal castings of unalloyed copper, and reasonably successful static castings can be produced if proper mold and gating systems are employed.

Jan 1, 1963

By Joan C. Biordi

[Composition profiles for atomic, radical, and stable species, as well as temperature and area expansion ratio profiles, have been determined for a nearly stoichiometric CH4-02-Ar flame and one to which 0.3 percent CF5Br inhibitor had been added. Net reaction rate profiles were calculated for all the observed species. For the normal flame, these and the mole fraction profiles gave rate coefficient information about the elementary reactions in the methane flame, for example, CH. + 0 4- H2CO 0 H, k4 = 1.05 X 1014CM3 mole-1sec-1 for 1,550§T 0,725' K; CO + OH 4 C02 + H, k6= 4.7 X 1011 for 1,350{T X1,750° K. Comparison between the inhibited and normal flame showed that A] and [CH3] were significantly reduced at the lower temperatures in the inhibited flame even though in the hot gas region the [E] [OH!, and [0] were essentially the same in both flames. The CF3Br disappears very early in the flame, relative to the fuel, and the reaction primarily responsible for its disappearance is H v CF3Br 4 HBr + CF3, where k7 is found to be 2.2 X 1014 exp(-9460/RT) for 700-1,550° K. Reaction of the inhibitor with methyl radicals provides for the relatively small amounts of CH3Br observed, but CH3 + Br2 - CHs Br + Br must also occur. The HBr formed reacts rapidly with H atoms to form H2 and Br, but the reaction is soon "balanced" in the flame as may be demonstrated by calculation of the equilibrium constant at various temperatures. The fluoro-carbon fragment produced in reaction (7) also reacts rapidly, in part with methyl radicals to give the observed elimination product CH2CF2 Later in the flame, above -1,400' K, F2CO is formed from the reaction CH2CF2 + 0 P F2CO + CH2 and k., -1.5 X 1013 at 1,600° K. The rather slow decay of carbonyl fluoride is attributed to reaction with H atoms according to the sequence F2CO I H - HF + FCO and FCO + H HF + CO.]

Jan 1, 1975

By D. H. Baker

These investigations were conducted to determine the feasibility of molten salt electrorefining of zirconium scrap, offgrade sponge, and alloys under contract number AT(11-1)-475 between the Atomic Energy Commission and the Federal Bureau of Mines. Offgrade zirconium sponge having a Brinell hardness of 169 can be refined by this technique to produce metal having, consistently, a Brinell hardness of less than 90. Also, zirconium alloy scrap, approximating zircaloy-2 in composition, can be refined to recover zirconium metal with a Brinell hardness of less than 100 that is essentially free of the major alloying elements. Analysis showed that the quantities of these elements were decreased as follows: iron from 0.27 to 0.002, tin from 1.36 to 0.001, nickel from 0.02 to 0.001, and chromium from 0.12 to 0.002 percent.

Jan 1, 1961

By Clyde M. Pearce

The Lake Superior iron-mining district includes parts of the States of Michigan, Minnesota, and Wisconsin. The laws of each State provide for an industrial commission and for inspection of mines. The following extract from the General Orders on Mines, effective October 25, 1937, issued by the Industrial Commission of Wisconsin, is the only reference to the use of safety catches on mine cages or skips found in the laws and regulations in the Lake Superior iron-mining district: Order 316 - Cages for Hoisting Men. (c) Sides, Gates, and Safety Catches. ***Every cage shall be provided with safety catches of sufficient strength to hold the cage with its maximum load at any point in the event the hoisting cable should break. (d) Testing Safety Catches. The safety catches of cages and skips used to hoist men shall be kept well oiled and in good working order. They shall be tested at least once each month by tying up the cage or skip with hemp rope, lowering a few feet of hoisting cable on top of cage, then cutting the hemp rope, provided that any other system of testing, which is equally effective, may be used.

Jan 1, 1945

By William O. Vanderburg

This paper describing the practice at the Wolf Pongee concentrator at Federland, Colo., is one of a series on similar subjects being published by the United States Bureau of Mines. The author acknowledges the assistance of Loach, manager of the Wolf Tongue Mining Co., and of W. G. Roseborough, superintendent of the golf Tongue mill, in the preparation of this paper.

Jan 1, 1933

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

8. Field Demonstration of the Remote Mine Sealing System in a Coal Mine 8. 1 Selection of Field Test Site Eastern Associated Coal Corporation (EACC) offered its Federal No. 1 coal mine in Grant Town, West Virginia as the site for field testing of the remote sealing system. The choice of Federal No. 1 mine was particularly appropriate as the first attempt at fire control by remote sealing was done in this mine in 1963. EACC provided the men and equipment required for much of the initial preparation. Considerable assistance, advice, and background on coal mining technology was given by Mr. William Laird, Vice President for Research and Development, EACC, and by Mr. Lawrence Jackson, Resident Engineer at the Federal No. 1 mine. District 3 USBM office, the West Virginia Bureau of Mines, the Technical Support Group of the USBM, and Local 4047 of the United Mine Workers of America also cooperated. 8.2 Preparation of Field Test Site 8.2. 1 Underground Site Preparation The underground site chosen for the field testing was in a non-working portion of the mine within a few hundred feet of the main haulage road, as shown in Figure 80. Known as "Seven Switch, " this area was a 20 minute walk or 5 minute "jeep" trip from the man-trip shaft. Ten years having passed since this area was actively worked, considerable effort was required for gob clearing, roof bolting, rock dusting, and rejuvenating the track from the haulage road to the test area. Three primary borehole locations were chosen for the test program. Borehole No. 1 was in a straight passageway

Jan 1, 1973

By B. S. Covino

The Bureau of Mines has conducted a laboratory and field corrosion test¬ing program to determine materials of construction for the leaching and gas-sparging crystallization environments of the clay-HC1 process in order to more fully utilize the alumina from domestically available kaolinitic clays. Laboratory tests were used to determine the corrosion rates of 22 metals and alloys by weight-loss measurements in these two environments of the process. The results of this laboratory study were used both to suggest metals and alloys for field testing and to determine the effect of the individual solution components on the corrosion behavior of the metals and alloys. Results from the field tests were used to recommend Ta, Ta-2.5W, and Ta-10W for con¬struction of the agitators for the leaching process. The metals and alloys recommended for construction of the gas-sparging crystallizer heat exchangers were Ta, Ta-2.5W, Ta-10W, Nb, Nb-1Zr, Nb-3Zr, Nb-28Ta-10W-1Zr, Nb-10Hf-1Ti, and Zr for the first stage and Ta, Ta-2.5W, Ta-10W, Nb-28Ta-10W-1Zr, Nb, Nb-10Hf-1Ti, and Zr for the second stage.

Jan 1, 1981

By Richard Havens

Samples of low-grade oxide manganese ores were procured from two southern Utah properties by examining engineers of the Bureau of Mines during an investigation of manganese mineral deposits of continental United States. A 2-ton lot of ore was obtained from the Blackbird group of mining claims in Paiute County, 11 miles southeast of Marysvale, Utah. The deposit was described as an intrusive sheet or sill of altered brecciated rhyolite cemented together by manganese oxide minerals. A 2-ton sample from the Black John property, situated 32 miles northeast of Kanab, Kane County, Utah, was taken from open cuts on the vein. The blanket-type vein deposit consisted of nodules and streaks of manganese imbedded in compact gray clay.

Jan 1, 1949