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By G. R. Hopkins

[Apparent progress in fuel economy at petroleum refineries, as measured by the average amount of .seat units required to refine a barrel of crude oil, received a set-back in 1935, when the average rose to 562,00 B. t. u., compared with 562,000 B.t.u. in 1937 (see fig. l). The primary factor in the rise in average heat requirement's per barrel of crude oil refined in 1938 wan the decline in total runs to Invariably the average requirement increases when crude ins to stills decline, and vice versa. In other words, annual gains in fuel efficiency at refineries arc masked by the degree to which the capacity is utilized. Additional crude runs give lower average e heat requirements in two ways - first, because they are mane with the c expenditure of comparatively small amounts of auxiliary heat, and, second, because the additional runs generally represent simple topping operations. In 1938 crude runs, to stills declined 1.6 percent (from 1,183,440,000 barrels in 1937 to 1,165,015,000 barrels in 1938), but the total heat consumption declined only 0.4 percent, or from 663,866 billion B. t. u. in 1777 to 660, 56 billion in 1938 .]

Jan 1, 1939

By James R. McVey

Tests during pillar robbing, longwall operations, and other mining activities indicate that roof-floor convergence rates can be used as an indicator of imminent roof failure. A large number of electrical-mechanical devices have been built to measure convergence as well as convergence rates, but most obstruct mine traffic and are costly and time consuming to install. The Bureau of Mines has designed and is evaluating three types of small ultrasonic units to make these measurements. The new instruments provide nonobstructing measurements up to 35 ft away. The ultrasonic transducers can be attached to a roof bolt, placed in an unsupported area (by means of a toss basket), or handheld. Total distance to the target and rate of closure are displayed digitally to 0.001 ft and 0.01 ft/min, respectively.

Jan 1, 1984

By T. M. Barczak

Many of the support concepts currently used in the United States originated in South Africa. These products include the Hercules Crib1, Propsetter, MX Prop, Rocprop, and Spider Prop. Another recent development has been the introduction of hydraulic prestressing units, such as the Jackpot system, to various U.S. standing support systems. Several other prop-type supports with similarities to systems used in South Africa are in use in U.S. coal mines. Some exciting new developments that improve the installation and yield performance of props are also underway. In addition to prop-type supports, crib-type supports and single-unit systems such as the Can support are also frequently utilized in longwall tailgates in the U.S. The goal in U.S. support development is to enhance roof support capability while alleviating material handling barriers to reduce injuries associated with support handling and installation. Support products are generally full-scale tested at the National Institute for Occupational Safety and Health (NIOSH) in the unique Mine Roof Simulator load frame. The performance testing protocol is designed to simulate the full range of load conditions that occur in underground mining to identify the performance deficiencies and limitations of the support products. Once the products complete the performance evaluation, they are implemented into the NIOSH Support Technology Optimization Program (STOP). STOP is a window’s based software program that was developed by NIOSH for facilitating the design of standing roof support systems. STOP has become an industry standard to compare the performance capabilities and facilitate the application of these support products into various mining conditions. The purpose of this paper is to provide an overview of the support design and application philosophy in the United States.

By Albert F. Baker

Techniques were developed and circuitry was assembled for measuring the total and volume resistances to the flow of electric current through solid specimens of anthracite. The two-, three-, and four-terminal test methods demonstrated the extreme sensitivity of resistivity to differences in anthracite characteristics and showed response to changes resulting from variations in structure, temperature, and moisture content.

Jan 1, 1966

By Peter D. Lohn

The Bureau of Mines conducted both laboratory and field investigations to study the effectiveness of medium-pressure (up to 30,000 psi) water jets in controlling the generation of airborne respirable dust during the hydraulic fragmentation of coal. Laboratory studies were conducted at the Farmington High Energy Test Site of the Twin Cities Mining Research Center, and field studies were carried out at the Humphrey No. 7 mine, Mount Morris, Pa., in the Pittsburgh coalbed. The water jets were produced by commercially available triplex pumps. The dust samples were collected by midget impinger samplers, and analyzed by electronic and optical counting techniques. Respirable dust concentration for a full-scale production model was projected at below 2 mg/m3, the maximum exposure allowed by the Federal Coal Mine Health and Safety Act of 1969.

Jan 1, 1975

By C. Ortuglio

The Bureau of Mines developed equations to determine the relationship of yields and products obtained from BM-AGA carbonization in 13-and l8-inch-diameter retorts. The developed equations indicate that results of carbonization in l8-inch-diameter retorts can be predicted from results obtained with l3-inch-diameter retorts.

Jan 1, 1966

By K. E. Tame

The Bureau of Mines is studying possible modifications in conventional uranium ore-processing steps to confine and permit controlled disposal of radioactive wastes. Surveys of Ra226 contamination of liquid wastes from uranium mills indicated that the Vanadium Corporation of America plant at Durango, Colo., had one of the more urgent problems. A possible procedure for minimizing the waste disposal problem was to reuse the waste solution in the mill--in effect, erasing the need for disposal of liquid waste. In examining this possibility, interlocked bench-scale leaching and solvent extraction tests simulating the Durango flowsheet were made. The simulated reuse of barren raffinate for leaching and washing was carried through three separate campaigns of 9, 12, and 35 cycles each.

Jan 1, 1961

By Michael R. Kennedy

This report describes the demonstration of longwall mining in a seam dipping 27 to 34'. Equipment was selected on the basis of capability, compatibility, and co t. Snowmass, Bureau of Mines, consultants and manufacturers were involved in the selection process. The equipment arrived in early 1981, prior to completion of development for the first panel; therefore, the equipment was operated on the surface for training. The surface training paid off with a fast, efficient installation and start-up of the face. The longwall equipment operated very well on the steep pitch with an average equipment downtime of 21.9[9]. Coal handling outby the face was a problem which caused an additional downtime of 19.5%. Development for the panels proved to be the major problem in the economics of longwall mining on a steeply dipping seam. During the first 9 months of operation the longwall averaged 71.9 TPMS and development averaged 0.6 TPMS for an overall average of 14.1 TPMS. Had mining continued, timing of development would have been another major problem. Monitoring of subsidence, pillar stability and shield loading was done in connection with mining, but little useful information was gained from the monitoring.

Jan 1, 1987

By W. H. Young

The thickness of the coal seam is one of the more important items influencing the productivity and general overall efficiency of operation 1 of a coal mine. The average thickness of coal seams mined in the United States decreased 2 inches between 1950 and 1955 to an average of 62 inches, which also is 3 inches less than the 65 inches in 1945. The decrease in thickness is due partly to the increased production from strip mines with thinner seams and partly to the increased percentage of total production at underground mines in certain States having thinner seams. The thickness of seams at auger mines was measured for the first time in 1955 and was 53 inches. Though bituminous coal and lignite is mined today from seams of exceedingly variable thickness -less than 2 feet to ore than 50 feet -a large majority of the production, 65 percent in 1955, came from seams 3 to 6 feet thick. This is not surprising since the coal seam of moderate thickness presents the least mining difficulties.

Jan 1, 1957

By Victor Kalcevic

A gas-flow retort for thermal processing of oil shale to recover shale oil was developed by the Bureau of Mines at its Oil-Shale Demonstration Plant, Rifle, Colo., from 1948 to 1952. The retort is a crossflow gas-to-broken-solids heat exchanger. The heating medium is the gas produced in the shale retorting process. The gas is heated in specially designed stoves outside the retort and recycled to the retort. Oil shale from the Mahogany ledge section of the Green River formation in northwestern Colorado was the material processed. Indicated maximum oil recoveries for 20-to 25-gallon-per-ton shale in a l2-inch-thick shale bed and a 20-inch bed are 96 and 91 weight-percent of Fischer assay, respectively. Heat requirements for maximum recovery are 600 to 750 B.t.u. per pound of shale. Properties of the recovered shale oil are affected slightly by shale-bed thickness and extent of retorting. Oil recovery from oil shales assaying over 30 gallons per ton is lower than that from leaner shales.

Jan 1, 1959

By S. P. Holt

The Rush & Brown mine has been one of the most consistent small producers of copper ore in the history of Alaskan mining. Approximately 50,000 tons of ore have been shipped to smelters from the property. Production has been made from two distinct and separate ore bodies of dissimilar types. The Shear Vein deposit has been mined to a depth of 500 feet below the surface without a reduction in the size of the ore shoot or the grade of ore. The Magnetite ore body has been partly mined to a depth of 200 feet below the surface. Because of the favorable production record of the Rush & Brown mine, the present need for copper and the fact that the owners were attempting to place the mine in production, it was deemed advisable to investigate this property under the Strategic Minerals Act of 1939 as a possible source of copper.

Jan 1, 1948

By Eric R. Bauer

The magnitude and rate of advance of an inmine coal squeeze was deter-mined by measuring roof-to-floor convergence on a regular basis. A dial-gage tube extensometer was used to collect data. Using these measurements) Bureau of Mines employees drew contour maps and graphs to show the direction and rate of squeezing. Information on the rate of squeeze advance was used to determine whether steps should be taken to prevent roof and/or floor movement from closing an entire section of the mine and if alteration of mining plans was necessary to prevent further squeeze development. Data analysis revealed that the squeeze was decelerating; thus there was no need to strengthen support in the areas of the mine that were studied. Mining plans were altered, however, as a result of the findings of this investigation.

Jan 1, 1981

By G. R. Hopkins

A recently completed survey , made by the Bureau of Mines to determine the trend of fuel consumption at refineries in the United States , showed the following outstanding points : A decrease in the use of oil for fuel in 1927 of over 5,000,000 barrels as compared with 1926 ; a decrease in the use of coal of over : 1,000,000 short tons ; small increases in the use of both natural gas and refinery gas ; an increase in the use of petroleum coke . The decrease in fuel - oil consumption was approximately 2,000,000 barrels each in the Atlantic Coast , Texas , and Louisiana- Arkansas districts , with an increase of 1,000,000 barrels in the Indiana - Illinois district , or a net decrease of 5,000,000 barrels . The decrease in fuel- oil consumption by refineries in the Texas and Louisiana- Arkansas areas was offset largely by increased consumption of natural gas and refinery gas , whereas the increased consumption in the Indiana- Illinois region was more than offset by the decrease in coal consumption . The use of coal for fuel declined from 6,052,000 short tons in 1926 to 5,031,000 short tons in 1927. Practically all of this decrease was recorded in the Appalachian and Indiana- Illinois districts , which at the same time showed the largest percentage increase in the use of oil for fuel . It is probable , therefore , that although coal prices also fell off , a considerable quantity of oil replaced coal in this area in 1927. In addition , the group of refineries , which are by location more or less definitely committed to the use of coal for fuel , undoubtedly succeeded in saving a material amount of coal through the use of more efficient fueling methods . A total of 130,815,000,000 cubic feet of natural gas was consumed for fuel at refineries in 1927. This represents an increase of 8 per cent over the 1926 total . Nearly all of this increase resulted from the opening of a line from the Monroe field to Baton Rouge , La . Had this line not been opened , there would have been a decrease in the use of natural gas , as a number of districts , particularly the Rocky Mountain , reported decreases in its use . The use of refinery or still gases for fuel did not change materially during 1927 , there being a total of 52,807,000,000 cubic feet burned as compared with 52,077,000,000 cubic feet in 1926. Refinery gases are largely a product of cracking and , it was probably more than a coincidence that a few districts in which cracking slowed down in 1927 also reported less refinery gas used as fuel .

Jun 1, 1924

By F. W. Brown, F. C. Gibson

"INTRODUCTION There is urgent need for a satisfactory permissible multiple-shot blasting unit capable of firing 10 detonators in series and safe for use in underground mining where a. gas-ignition hazard may exist.. As there is at present no entirely satisfactory permissible unit of either the battery or generator type, tile described capacitor-battery type has been developed. Consideration of the Bureau of Nines approval schedule pertaining to the generator and magne to-type units and of the electrical characteristics of the unit described in this report indicate that this unit should meet Bureau of Mines permissible requirements.This report gives a detailed description of the design and operation and results of tests to determine safety of operation in gassy atmospheres.DESIGN AND OPERATION OF UNITOperation of the vibrator-type multiple-shot blasting unit is based upon utilization of the discharge energy from a capacitor charged to a given. voltage and having capacitance adequate to store enough energy to initiate 10 detonators in series. The primary source of energy is a 4-volt cap lamp battery such as is carried for illumination on the person of underground workers in nearly all mines. As this battery is already available and is recharged daily it is considered to be a reliable and convenient source of energy for a blasting unit. Figure 1 is a schematic diagram of the circuit for an improved unit, and figures 2 and 3 are views of the experimental unit. The battery potential is applied through a radio-type synchronous vibrator (8) to an 8-volt center-tapped primary of a small transformer (9) having a high-voltage center-tapped secondary. The vibrator introduces an alternating low-voltage potential into the primary and mechanically produces full-wave, rectified, pulsating, direct current from the secondary. A buffing condenser (11) across the secondary gives the proper wave form for long vibrator life: a resistor (12) its in series with this condenser across the total secondary to protect the transformer in case of• failure .of this capacitor. A voltage divider (10) with an adjustable slider permits accurate adjustment of the potential applied to the high-capacity firing condenser (5)."

Oct 1, 1947

By Robert W. Smith

In a certain application2/ it was necessary to compute the beta function B(p, q) for a certain set of values p and q. Since t he set of p and q values was much mo re finely spaced than those in any published tables, the authors decided to make their results available in this report. In connection with this application the functionB(p, q) was needed at various points in the p, q plane at intervals of 0.05, 0.05<p = q< 10.00. Fletcher, Miller, and Rosenhead2/ state that the only tables available in the desired range are those of Rearson.4/ However, the interval used by Pearson was not small enough for the present application. For this reason it was decided to calculate B(p, q) for p = q =0.05 (0.05) 10. 00.2/ This table is published because of the fundamental importance in mathematical analysis of the complete beta function.

Jan 1, 1953

By Levent Ozdemir

The results of a laboratory research program aimed at the development of a water jet assisted drag bit cutting system for coal mine applications are presented. Two types of drag bits, a conical and a plow bit, were tested in a hard sandstone rock with jet pressures of up to 20,000 psi. Jet locations investigated were in-front and behind the bit. For each jet mounting location, three jet impingement distances with respect to bit tip were tested. The closest jet impingement location to bit tip was found most effective, providing the greatest force reductions on the bit. Overall, significant bit force reductions up to 50 percent were obtained with jet assist. Also observed was a drastic reduction in airborne dust when jets were employed.

Jan 1, 1986

By A. Wahab Khair, N. P. Reddy

"Abstract. This paper attempts to characterize coal breakage due to the action of a continuous miner. Coal blocks with an approximate dimension of 45.7 cm x 38.1 cm x 15.2 cm (18 in. x 15 in. x 6 in.) were first subjected to confining pressures equivalent to in-situ conditions. Then the blocks were cut along the face/butt cleat direction by the cutting head of a specially designed unique automated rotary coal cutting simulator (ARCCS), simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-sit and operating parameters a number of other para¬meters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment, the coal fragments were collected in bags using a vacuum cleaner. These fragments were then sieved for size distribution analysis.INTRODUCTIONThe Federal Coal Mine Health and Safety Act of 1969 was enacted to emphasize to coal operators that the airborne respirable dust should not exceed 2 mg/m3, thus reducing the incidence of coal workers pneumoconiosis.Dust control techniques such as conventional water sprays and dust collectors are only partially effective and require additional equipment expenditures. A more authentic approach would be to reduce respirable dust at the source the continuous mining machine cutting head, where the fragmentation process occurs. Improving the fragmentation process by characterizing the coal breakage will not only reduce respirable dust at the face, but it will also decrease the amount of respirable dust that is liberated during the secondary handling.Fragmentation of coal can be expressed as a function of three major groups of parameters; namely, 1) coal properties, 2) in-situ conditions and 3) operating parameters. This paper deals with the characterization of coal breakage along both face/butt cleat direction as a function of machine operating parameters such as rate of advance, angle of attack, bit configuration, bit lacing (spacing and pattern) and bit speed at various equivalent in-situ pressures."

Mar 1, 1989

By James C. Cawley

A summary is presented of existing leaky feeder communications systems currently in operation in North America. Background information pertaining to previous use of leaky feeder technology is discussed along with the survey methodology. A review of some pertinent facts concerning propagation in tunnels and specific reference to mine tunnel propagation is presented. A summary of the characteristics of each mine visited is presented in tabular form, and methods of procurement and maintenance are discussed. The role of user training in efficient system use is presented. Seven sites representing eight mines are included in the survey. Economic and technical topics are considered.

By H. W. Davis, W. W. Adams, O. E. Kiessling

"Current economic problems frequently have focused attention upon the lack of adequate quantitative information indicating the relationship between human effort and output in various branches of the mineral industry. With the exception of complete records covering coal mining, only scattered information on the units of human energy required to produce a unit of raw material is available for most of the important industrial minerals. Fortunately a virtually complete statistical record is available covering this phase of the iron-ore mining industry.For many years iron-ore mining companies, whose interest in safety work is well-known, have reported annual data on employment to be used in the compilation of accident statistics. These data on hours of labor and other detailed employment information have been correlated with the statistics on production also reported annually by producers. The outstanding trends shown by this composite record for the 10-year period 1923-32 are included in the following discussion, supplemented by a summary table that presents the principal statistical background of the study. 5The substantial reduction in the number of men needed to produce the annual iron-ore requirements of the United States, as shown strikingly in the graphs, illustrates that in iron-ore production improvements in technology have been consistently winning a battle over the difficulties of nature. In 1923, for example, 41,294 men working 107,551,244 hours were required to produce 69,351,442 gross tons of merchantable ore, equivalent to an average output of 0.645 ton per man-hour. In 1929, however, only 30,763 men working 77,111,686 hours 'zero required to produce 73,027,720 tons of merchantable ore, equivalent to an average output of 0.947 ton per man-hour. Thus, from 1923 to 1929 the average number of men working decreased 25.5 percent and the total man-hours worked 28.3 percent, while the average output per man-hour increased 46.8 percent and total merchantable ore production 5.3 percent."

Feb 1, 1935

By Dean C. Holt

This work was done to appraise the potential of titanium minerals in known titanium- bearing placer deposits and potential titanium- bearing placer areas in western Montana . Reconnaissance studies were made of more than 225 stream areas . Churn drilling and other placer exploration techniques were used in sampling eight deposits . The sampling results indicate that areas containing more than 10 pounds of ilmenite and other titanium- bearing black - sand minerals per cubic yard occur in the Bitterroot , Upper Clark Fork , and Jefferson River drainages . The chief source for the constituents of the black sands appears to be the Idaho batholith , and the highest black - sand concentrations are generally found near the source . Sample testing methods include gravity and magnetic separation and visual microscopic as well as chemical and radiometric analyses on deposits sampled in detail .

Jan 1, 1964