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By Richard L. Fischer

Constant-volume charges of precipitated PETN (pentaeythrite tetranitrate) at three specific gravities (0.50, 1.00, and 1.50) were used in laboratory tests to examine the effects of changes in explosive properties on free-surface displacement pulses and on crater dimensions. The tests were performed in large blocks of cement-mortar. The values for the detonation velocity, detonation pressure, specific energy, energy density, and energy release rate were calculated from the explosive loading density. Calculated explosive properties were correlated with free-surface displacement pulse measurements, strain energy, and measured crater dimensions. Increases in explosive properties resulted in increased free-surface displacement pulse parameters and crater dimensions. The loading density, detonation velocity, energy density, detonation pressure, and energy release rate were found to be best indicators of explosive performance. Simple acoustic relationships involving impedance ratios were examined and could not be used to predict peak displacement amplitude or strain energy. Data are presented in the customary English units as well as the International System of Units (SI).

Jan 1, 1970

The principal activities of the Bureau of Mines Explosives Research Center from July 1, 1963 to June 30, 1964 are described briefly in part 1. Part 2 gives short abstracts of publications that appeared during fiscal year 1964; in general; the research reported in these publications antedates the report period. Part 3 describes a short-term investigation into safety problems associated with shipping of molten sulfur; this investigation is not at present destined for publication elsewhere.

Jan 1, 1965

By Perry N. Halstead

This report describes two goniometers that, by simple manipulation, can be used to ascertain the attitude of a joint, vein, or fracture plane observed on the planar projection of a borehole photograph taken with an NX borehole camera of the type developed by the U.S. Army Corps of Engineers. One goniometer was designed to interpret photographs taken in vertical drill holes and the other for photographs taken in inclined drill holes. In practice, several measurements are made on each photograph with the goniometer. These data are then substituted into mathematical equations, which are derived in this report and the attitudes of fracture planes are determined.

Jan 1, 1968

By John M. Devine

The severe corrosion of equipment that is caused by the presence of hydrogen sulphide in oil and gas has been described in detail by several authors. Such corrosion, termed "low-temperature hydrogen sulphide corrosion", presents a somewhat different problem from the "high-temperature hydrogen sulphide corrosion" that is encountered in refinery operation and which has been described by various-investigators of refinery corrosion.

Jan 1, 1932

By Lloyd A. Morley

The primary goal of this research report is to discuss safety considerations involved in the use of lead-acid batteries for traction purposes in underground coal mines. In order to arrive at the objective, the topic of battery safety has been divided into two specific areas. The first deals with the fact that batteries emit hydrogen gas during and after the charge cycle. Hydrogen gas can be the source of dangerous explosions or mine fires. The second major topic deals with the electrical nature of the battery and battery-charging systems, which also provides a source of mine fires as well as electrocution hazards. In addition to the discussion on battery safety, a literature review has been undertaken to acquaint the reader with some basic concepts inherent to the battery usage process. The result of this research is a set of design specifications and procedural recommendations directed at improving the safety factors inherent in any underground battery usage scheme.

Jan 1, 1977

By John R. Bartels

In laboratory testing, the Bureau of Mines established criteria by which common resin-grouted roof bolting systems can be evaluated and compared. Ultimate strength and stiffness were determined for nonten-sioned full-column, point-anchor, tensioned full-column, and debondable resin-grouted bolts, and for variations on full-column boltsn Bolt per-formances were compared using the performance of the 3/4-in full-column resin-grouted bolt as the standard. New and innovative systems can also be qualitatively compared against this standard. Since the medium into which a resin-grouted bolt is installed is one of the most important parameters affecting bolt performance, various host mediums were used in the testing: sandstone, concrete, simulated coal, simulated shale, and plaster. Bolt performances expected in other mediums can be inferred from the response patterns obtained in these mediums. Results indicate several functional differences among bolt types. Where resistance to shear is important, point-anchor bolts may outperform nontensioned full-column bolts at a lower cost. In medium-to soft-strength rock, tensioned full-column bolts perform best. Also, varying the resin-steel ratio seems to have little effect on the properties of a full-column bolt, when proper resin mixing is ensured.

Jan 1, 1985

By Floyd R. Anderson

Noise control of existing pneumatic drills is difficult and runs into cost, performance and weight penalties. A need exists for a start-from-scratch approach for quiet pneumatic rock drills. The designs based on Leavell Principles which has been successfully used in demonstrating a quiet and vibration free paving breaker, is the concept chosen here. This report shows the feasibility of a quiet stoper for drilling roof bolt holes in coal mines. The work is directly applicable to pneumatic percussive rock drills. The report shows an oscillator based on patented Leavell concepts which results in a vibration free tool and noiseless exhaust. Dynamics of the oscilator is analyzed. Independant rotation of drill rod is provided by an air motor (screw expander) and flushing of cuttings is accomplished by an air ejector in a compact lower housing. The feasibility of no exhaust noise, low drill machine noise, and vibration free casing is discussed.

Jan 1, 1977

By Nicholas Kyriazi

A joint effort by the U.S. Bureau of Mines and the U.S. Mine Safety and Health Administration (MSHA) was undertaken to determine how well self-contained self-rescuers (SCSR's), deployed in accordance with Federal regulations (30 CFR 75.1714), survived the underground environment with regard to both impact damage and aging. This report presents findings regarding laboratory-tested SCSR's from 1982 through 1990. The SCSR's were tested on human subjects and on a breathing and metabolic simulator (BMS). These results indicate that most of the apparatus, if they pass their inspection criteria, perform as expected except for units with manufacturing defects or design deficiencies. However, when the apparatus are carried in and out of the mine daily and stored at the working section, they may suffer abuse. Physical signs of abuse, unless extremely obvious, are frequently not detected by the miners or mine operators. This poses a potential danger to a user in an emergency. Recommendations include improved training in inspection procedures.

Jan 1, 2010

By N. L. Kozlinsky, B. W. Gandrud

"The Marvel mines 1 and 3 of the Roden Coal Co. are located in the Cahaba field in Bibb County, Ala., nearly southwest from Birmingham, an airline distance of roughly 30 miles. The coal of the Clark seam at this point has some coking properties, but at present it is sold exclusively as a domestic and steaming coal.This paper, which is the second of a series on the washability of Alabama coals, like its predecessor dealing with the Mary Lee seam,5 contains screen-sizing and float-and-sink tests of a representative sample of the raw slack, and slotted-screen tests showing the proportions of flaky particles in certain selected sizes; inasmuch as this coal is not used for coke manufacture, no crushing tests have been made. These data have been obtained in connection with an exhaustive study of coal preparation in Alabama, now being conducted by the United States Bureau of Mines and the University of Alabama with the cooperation of the different coal operators. As the work progresses, other papers will follow containing further data on Alabama coals and giving results obtained in preparing these coals by various methods.The only published investigative work on the Clark seam is that of Forbes,6 who gives a number of sections of this seam in Marvel No. 3 mine with proximate and ultimate analyses of face samples taken in the mine and also some analyses of delivered coal.The available information on this coal indicated that the preparation problem was one of ash reduction. In order to substantiate this information a complete analysis of the 3/4 by 3/16 inch size, and sulphur determinations and ash-fusibility tests of the float-and-sink fractions have been made; these results are given in Tables 1 and 2. As these results also indicate that the preparation problem is one of ash reduction, the tests and discussion have been devoted to that subject."

Jun 1, 1930

By Arno C. Fieldner

The objectives of the coal-research activities of the Bureau of Mines are very well expressed in the organic act of Congress establishing the Bureau. It reads as follows: That it shall be the province and duty of the Bureau of Mines, subject to the approval of the Secretary of the Interior, to conduct inquiries and scientific and technologic investigations concerning mining, and the preparation, treatment and utilization of mineral substances with a view to improving health conditions, and increasing safety, efficiency, economic development, and conserving resources, through the prevention of waste in the mining, quarrying, metallurgical and other mineral industries; to investigate explosives and peat; and on behalf of the Government to investigate the mineral fuels and unfinished mineral products belonging to, or for the use of, the United States, with a view to their more efficient mining, preparation, treatment, and use; and to disseminate information concerning these subjects in such a manner as will best carry out the purposes of this act.

Jan 1, 1946

By J. R. Ruark

Because of the importance of oil-shale reserves the Bureau or Mines resumed research investigations in this field beginning in 1944. The Bureau early decided to build a Large-scale demonstration plant to accomplish the dual purpose of obtaining design data and to produce crude shale oil for refining studies. Two 40-ton-Capacity batch N-T-U (Nevada-Texas-Utah) retorts were completed for this purpose in 1947. After a preliminary operation, the plant was used to investigate process variables of air rate, recycle gas rate, and shale particle size and crude. Correlations obtained from these variables are presented in this report. Researchers concluded that recycle gas was not necessary for efficient operation of the process. Short comings of the batch method of processing the oil shale are pointed out in the report. Several periods of prolonged production operations were carried out. During these periods, the retorts were operated to produce as much crude oil per day as possible. The lifetime operation of the N-T-U retorts was divides into three periods, namely, preliminary operation, process variable study, and production operation. During the preliminary operation, 187 runs were made with a total of 7,596 tons of raw shale used to produce 3,688 barrels of crude shale oil. During the process variable study, 179 runs were made with a consumption of 7,494 tons of raw shale and a production of 4,218 barrels of crude shale oil. The production operation consisted of 554 runs in which 22,457 tons of raw shale was used to produce 12,359 barrels of crude shale ail. The overall total for the lifetime operation of the retorts consisted of 920 runs with a total consumption of 37,547 tons of raw shale and a production if 20,265 barrels of crude shale oil.

Jan 1, 1956

By W. T. Benson

The nickel-bearing laterite deposits in the Pine Flat and Diamond Flat areas, Del Norte County, Calif., were investigated by the Bureau of Mines to determine the extent and nickel content of the two deposits and the amenability of the ores to metallurgical treatment. The work was based on drill-hole sampling and metallurgical tests in which attrition scrubbing and sizing, reduction roasting, and magnetic separation were used. Results of the sampling indicated that the deposits are comparatively small and are marginal or submarginal in grade. Metallurgical tests showed that no separation of cobalt from nickel and iron was made by sizing; however, a large portion of the chromium was separated. Reduction roasting and magnetic separation did result in upgrading the iron, nickel, and cobalt, and the simultaneous rejection of chromium.

Jan 1, 1963

By J. B. Gayle

The merits of the various methods for dry-quenching coke have been the subject of numerous publications and almost equally numerous controversies for the past 40 years.5/ Most investigators have concluded that dry quenching is advantageous. Some have based their arguments on the improved physical properties of the resultant cokes. Others have claimed little or no improvement and have based their arguments on the economies acquired from the recovery and utilization of sensible heat. The extent to which the method of quenching influences the properties of the resultant cokes is of importance in connection with the operation of both commercial and experimental ovens. On the other hand, the recovery and utilization of sensible heat are economic problems related solely to commercial oven operation and- depend on the method of dry quenching used and the demand for a low intensity energy source. The scope of the present Bureau of Mines investigation has been limited to a comparative study of the properties of wet- and dry-quenched cokes produced from six coals and blends carbonized at flue temperatures of 2, 000° and 2,400° F. in the Tuscaloosa oven.

Jan 1, 1959

By S. M. Runke

An ever-increasing demand for beryllium and beryllium alloys has directed attention to the milling of low-grade domestic deposits as a possible means of supplying part of the Nation's ore requirements. The United States generally produces less than 10 percent of its annual supply. For example, new supply in 1953 was estimated at about 9,250 tons, of which the United States imported 8,500 tons. Domestic production was only 750 tons.2/ Since record high prices for beryl in 1952 and 1953 did not greatly increase domestic product ion, the United States must develop mechanical beneficiation processes to use low-grade deposits and reduce dependence on foreign sources

Jan 1, 1954

By Ira L. Wright

This paper describing the milling practice of the Black Hawk Consolidated Mines Co., is one of a series being prepared by the United States Bureau of Mines. ACKNOWLEDGMENTS Part of the information contained in this paper was furnished by I. H. Stanley, mill superintendent, Black Hawk Consolidated Mines Co., Hanover, M. M., and a part by the South-western Engineering Corporation, Los Angeles, Calif. The assistance of T. G. Chapman in arranging the paper for publication is also acknowledged.

Jan 1, 1930

By John Ward Smith

The potential economic value of oil shale depends on the products from thermal degradation of the rock, because no other practical method for producing valuable material from oil shale has been found. Detailed study of thermal degradation behavior can aid in characterizing oil shales and their deposits and in evaluating oil-shale processing methods, Numerous publications describe various pyrolysis properties of oil shales (see surveys 3, 9, 11 and articles 1, 2, 4-8, 10, 12),4 but they do not describe a generally applicable analytical procedure for detailed evaluation of thermal degradation products. The analytical method presented here for such evaluations is designed to provide for: 1. Control of retorting conditions--temperature, heating, rate, reaction atmosphere--plus some control over retort pressure and carrier-gas flow, 2. Precise direct gravimetric measurement of the thermal degradation products--oil, water, gas, and spent charge (residue after thermal treatment of the charge). 3. Samples of all products. 4. Determination of the identities and amounts of gaseous compounds produced. 5. Elemental analysis and gross heating value of all products. 6. Determination of the distribution in the retorting products of the elements present in the original samples.

Jan 1, 1962

By Don Steffa

Drift mining, according to California mining terminology - and it is distinctly a California development - is the blocking out and extraction (breasting) of the auriferous gravels of an ancient buried stream either through tunnels, inclines, or shafts; it is one of the minor divisions of the larger classification known as placer mining. The contribution of each of these divisions and of lode mining to the gross production of gold in California totals as follows:3 [ ] The total amount of gold recovered from the placers of California from 1848, when Marshall discovered the precious metal in the mill race at Coloma, to 1928, was $1,226,515,404. The same period saw a total gold production from all operations of $1,823,562,360.

Jan 1, 1932

By J. F. Barkley

"The fly-ash problem of the smoke-abatement engineer - who now might well be titled, ""Smoke and Fly-Ash Abatement Engineer"" - starts with the necessity for him to know what fly ash really is, what plants really create it, and how much is being created. Fly ash in this connection may be defined as all solid particles emitted to the atmosphere as a result of the combustion of fuel.COMPOSITION OF FLY ASHMuch can be learned about fly ash by studying samples with a strong magnifying glass or, preferably, a high-power microscope. As an example, figure 1 is a photomicrograph of an underfeed-stoker fly ash weighing 23.7 pounds per cubic foot, which passed a baffle-type cinder catcher and was caught by a Cottrell precipitator. Figure 2 shows a similar fly ash made at a higher stoker rating and weighing 36.2 pounds per cubic foot. The lighter ash contains more light, unconsolidated ash than the heavier. In both instances some of the ash has been fused to a glass, as is indicated by the spherical particles resembling marbles; however, the heavier dust contains more and larger spheres. With the faster burning and higher air pressures occurring at the higher burning rates, more of the larger fused spheres reached the precipitator.Such studies of fly ash frequently make possible correct determination of its source. For example, the Supreme Court Building, one of the finest of the Federal buildings in Washington, was having considerable difficulty with fly ash from some outside plant. It was thought to come from a nearby apartment house. A fly-ash trap was installed there, and care was taken in the operation of their underfeed stokers. The fly-ash nuisance continued. Microscopic examination of the fly ash found about the building compared with samples taken from the stack of the apartment house showed to the surprise of the accusing building superintendent that the present source was elsewhere. By the same means, the source was found to be a plant about ore-half mile away."

Sep 1, 1939

By R. D. Leitch

Spontaneous firing of coal during storage end even during shipment has long been a serious problem, especially in some regions and with some coals, and methods for preventing such firing have been investigated at intervals for more than 70 years. Spontaneous or other firing of coal waste, either outside or inside mines, has also been a problem probably for as long as mining has been practiced extensively. Much trouble has been caused by such fires, and much money has been spent in attempts to extinguish them. It is known generally that surface waste banks in bituminous-coal fields are very likely to take fire sooner or later, but it is not known so generally that anthracite refuse-bark fires also are common and that at least some of them are more serious in their effect and results than being regarded merely as a nuisance. There surface refuse fires probably would have attracted much more than local attention long ago had it not been that they usually cause no more serious trouble than air pollution. A few supposedly effective methods of preventing or extinguishing spontaneous fires have been reported rather recently. Unless one or more of these prove to be widely applicable, methods of solving these problems are no more certain today than they have been for many years.

Jan 1, 1940

By P. A. Bloom

Bureau of Mines research was conducted to develop effective separation methods that might be used in exploiting substantial tonnages of complex barite-fluorspar ores in Arizona. The exploitable reserves now may be increased as recent batch and continuous flotation tests demonstrated that a complex barite?-fluorspar ore from the Red Chief deposit, Yuma County, Ariz., could be selectively treated to concurrently produce (1) fluorspar and (2) a barite byproduct of marketable grade. The sample contained 24.8 percent CaF2 and 24.3 percent BaS04. Processing comprised production of a fluorspar product containing 97 percent CaF2 with an 82 percent recovery, using a sodium fluoride-lignin sulfonate-fatty acid reagent combination. Concurrent retreatment of the fluorspar tailing, using sodium cetyl sulfate as a collector, yielded a barite product of 94 percent BaS04 grade with a 71-percent recovery. The products met specifications for acid-grade fluorspar and drilling mud-type barite.

Jan 1, 1963