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By C. R. Nisewanger, F. W. Brown

"The velocity of detonation of an explosive is one of its most important properties, because its performance depends markedly on the rate at which it releases its energy. Fortunately, the velocity of detonation is one of the few properties of an explosive that can be measured precisely. However, the velocity of detonation of an explosive may depend on several factors other than its chemical composition, such as density, physical state, degree of confinement, nature of confinement, and magnitude of initiating impulse. Presumably for an explosive of fixed chemical and physical properties there are certain limiting conditions of confinement and initiation under which the explosive will detonate at a maximum constant and uniform velocity. This velocity is its ""ideal"" velocity of detonation. It is obvious, however, that in order to evaluate performance properties of an explosive in all of its applications it may be necessary to measure its velocity of detonation under a number of conditions in which the velocity of detonation is far from the maximum ""ideal"" velocity.. Under certain-conditions the velocity of detonation may even,be,different at different points in the explosive.It is .relatively simple to determine the velocity of detonation of an explosive under a. standard set of conditions if one is free to use large quantities of the explosive and to form it into a convenient shape. Under these circumstances; one can use a thin column of explosive a meter or more in length. The time required for an explosion to travel the length of the column will not be less,of the order a few ten-thousandths of a second and can be readily and accurately measured .by means of the standard spark chronograph or by photographing the explosion with a rotating-drum camera. However in many applications the explosive charge may be of relatively small dimensions arid may not be in a form convenient for making velocity measurements and often may be enclosed in a case or other confining medium. It may be necessary to determine the velocity of detonation over distances of the order of a few centimeters, in which case the time intervals to be measured will be extremely small. For example, the time required for an explosion to traverse 1 centimeter of tetryl is of the order of 1.5 microseconds.Since no satisfactory method of determining time intervals of the order of magnitude of a few microseconds within an explosive charge was available,, at least not for all conditions that might be encountered in practice, it was necessary to develop a special electronic chronoscope which is capable of measuring time intervals as small as a microsecond with a fair degree of accuracy. This report describes the chronoscope and its application to measurements of velocities of detonation in explosives."

Mar 1, 1946

By James C. Cawley

The Bureau of Mines conducted an investigation to statistically determine the mean current or voltage for resistive, inductive, and capaci-tive circuits that would cause spark ignitions in 8.3% methane-air, 5.3% propane-air, and 7.8% ethylene-air mixtures. Each mean ignition current or voltage was determined on the basis of 100 trials. Each trial consisted of 400 revolutions, 200 in each polarity, at 80 rpm of the standard breakf1ash apparatus. In general, spark ignition curves published in UL 913 for resistive and inductive circuits represent approximately the mean current values determined in this study, while published capacitive circuit values in methane are considerably less than the mean voltage values from this study, especially for a capacitance of less than 100 ~F. For resistive and inductive circuits, spark ignitions were obtained at currents con-siderably below those in the published curves, but this study was not optimized to find minimum ignition values. This report defines "safety factor" as applied to intrinsic safety testing as the energy ratio of the mean values of ignition current or voltage for two test gases. The safety factors presented in this report are not constant with voltage or current and, therefore, are not recommended for use.

Jan 1, 1986

By G. B. Shea

In 192b, there wore 47 fatal accidents in the California petroleum industry, 14.6 per cent more than occurred in 1927 when 41 men lost their lives in the drilling, producing, manufacturing, and marketing divisions of the industry. This increase in the number of fatal accidents for 1928 has caused the first upward trend in the fatality curve of the California petroleum industry since 1923. In no other year during the 6-year period have the fatalities in any one year been greater than those for the preceding year. This fact should be given serious consideration and study by the petroleum industry, and an endeavor should be made to cause the number of fatalities again to decrease and conform to the previous gradual declining trend of the fatality curve. The following chart shows the trend of fatal accidents during the past six years:

Jan 1, 1929

By Earl L. Hastings

Although the principal market for diatomite in the United States is in the East,4 production of the material is presently restricted to the West, because the deposits are larger, mining costs are cheaper, and the quality of product is better than that obtained from other domestic deposits. However, Tallahatta diatomite, occurring in Choctaw and Clarke Counties, Ala., has a freight rate advantage, which should encourage competition for those market that are now being supplied with the purer diatomites from the western deposits. For this reason, diatomite occurrences in the Tallahatta formation were examined by the Bureau of Mines and physical properties of samples from the deposit were determined to obtain additional data for use by any potential producer who wished to evaluate the material for its commercial possibilities. In 1894 K. M. Cunningham5 found that the buhrstone formation (now known as the Tallahatta formation) contained "siliceous shells of marine diatoms, radiolaria and foraminifera, thus being rather of the nature of tripoli or diatomaceous earth than of a true clay." Cooke6 and Semmes7 also reported the Tallahatta formation to be composed principally of diatomaceous earth with accompanying beds of sand, clay, and sandstone.

Jan 1, 1963

By J. R. Thoenen

The objective of this circular is threefold: First, to describe briefly the various modes of occurrence of sand and gravel. Second, to emphasize the need for adequate prospect¬ ing and exploration prior to the expenditure of funds for development and plant construction. Third, to describe various methods of prospecting and exploration and their application to the several modes of occurrence of sand and gravel. Sand and gravel may be found in nearly every county or township in the United States. Commercial deposits, however, are by no means so widespread. The introduction of concrete and the consequent impetus given to consumption of gravel and sand aggregates has seriously depleted deposits in some congested areas. Increasing re¬ strictions in the specification requirements for marketing sands and gravels have further narrowed the economic areas. On the other hand, the combination of increasing transportation costs and decreasing selling prices has forced the decentralization of gravel production. As a result smaller, intermittently operated, and widely scattered portable or semiportable unit plants have been encroaching on the territory formerly supplied from centrally located pits with large tr.atment plants. Generally speaking, the small portable plant can not produce any great variety of ma¬ terials to as exacting specifications nor as economically as the large permanent plant.

Dec 1, 1932

By Paul E. Bennett, James S. Browning, Thomas L. McVay

Continuous 1.0- to 1.5 - ton - per - hour pilot plant flotation tests were made to determine the technical and economic feasibility of recovering beryl from flotation tailing being produced at the spodumene concentrator of the Foote Mineral Company , Kings Mountain , N.C. Best results were obtained when using an acid circuit and amine - type cationic reagents to float a bulk beryl - feldspar concentrate and then selectively floating the beryl away from the feldspar , using a petroleum sulfonate collector . About 77 percent of the beryllium in the pilot plant feed was recovered in a concentrate containing 6.42 percent BeO . The capital cost of an integrated flotation plant capable of treating 500 dry tons of spodumene mill tailing per day for recovery of beryl and feldspar is estimated at $ 210,000 . Indicated direct operating costs for the plant were $ 1.52 per ton of dry spodumene flotation tailing treated . This approximated the value of beryl recovered , but potential profits of about the same magnitude lie in concurrent recovery of marketable spodumene and feldspar byproducts .

Jan 1, 1964

By Charles L. Kimbell

In overview, 1988 appeared to be the best year for the world's mineral industry since 1980, although the all-important petroleum component suffered severely from low prices. With this notable exception, the traditional statistical measures of mineral industry performance, namely production, trade, and consumption, reflected growth in most elements of the world mineral industry from crude material extraction through the gamut of downstream processing. Moreover, the growth was reasonably well distributed geographically, with many countries sharing in the substantial upturn in activity. World crude mineral output value was estimated at over $1,272 billion in current dollars ($1,090 billion in constant 1983 dollars). The value added by the processing component of the mineral industry raised the total value of the industry's output to an estimated $3,057 billion in current dollars ($2,620 billion in constant 1983 dollars). Less easily assessed was the value of mineral commodities moving in 1988's international world trade, particularly because of the declines in world crude oil and refinery product prices. It remained to be seen if increased volume and value in nonfuel mineral and coal exports, coupled with an increase in the volume of oil exports, would be adequate to offset the drop in oil prices. Whether or not the value of world mineral commodity trade topped the 1987 level of over $498 billion, an increase in the volume of mineral commodity trade was almost assured. Similarly, although comprehensive statistics were not avail-able on consumption of all mineral commodities in all countries, available data on selected major commodities in selected major countries suggested that not only had output of most mineral commodities advanced, but so too had consumption levels for most commodities.

Jan 1, 1990

By S. P. Kinney

Economy in blast-furnace practice depends largely upon efficient gas-solid contact in the shaft of the furnace. If efficient work is not done in the shaft the hearth and bosh will not function properly. A condition may be readily imagined where the particles of ore in the shaft are so large that the time entailed in the descent of these materials into the bosh is not sufficient to permit proper reduction and preparation prior to the time the ore enters the bosh of the furnace. Another condition may be pictured where the density of the stock column and the flow of stock is such that the ore will take one course and the gas another. Both of these examples will result in insufficient contact between the gas and the ore. Unreduced ore will reach the hearth, and gas which has not been efficiently oxidized will reach the stock line. The result is the use of an excess of carbon in the smelting process. An example of the result of inefficient gas-solid contact in the shaft of a blast furnace is shown by the curves in Figure 1.

Jan 1, 1930

By Jr. Kauffman

The data contained in this report were obtained incidental to the Bureau of Mine's investigation of the lime-soda sinter process as applied to the recovery of alumina from siliceous bauxite, kaolin, and other high aluminous materials. The Bureau of Mines was charged by Congress to investigate processes for the production of aluminum from domestic low-grade ores. The Eastern Experiment Station at College Park, Md., conducted laboratory and pilot-plant investigations of the recover-y of alumina by the lime-soda sinter process. Reports by the College Park staff covering the recovery of alumina from these sources have been published. The lime-soda sinter process involves the sintering of the finely ground siliceous bauxite or clay with limestone and soda ash in a rotary kiln. During the sintering the alumina supposedly reacts with the soda ash to form soluble sodium aluminate and the silica combines with the lime to form the insoluble orthosilicate. In the early stages of the investigation it was considered desirable to know the temperatures at which the phase changes occurred during the sintering operation. The total time involved in the passage of any given portion of the charge through the kiln was 28 minutes. The exposure time of the charge to temperatures above 600° C. (decomposition temperature of kaolinite) was, roughly, half the total. The exposure to the full temperature of the kiln, 1,100° C was only 3 minutes. (Subsequently, the maximum kiln temperature and retention time were increased.)

Jan 1, 1949

Develop personal computer (PC) based software for analyzing and/or filtering time- and frequency-domain attributes of seismic and electromagnetic signals from geophysical surveys for the enhanced interpretation of rock masses and subsurface geologic structure. The Problem Both mining and petroleum geophysicists utilize seismic signals to characterize rock masses for delineating subsurface stratigraphy and structural conditions. However, a vast amount of information available in seismic project evaluation data often is unavailable for interpretation unless these data are enhanced. New processing technology increases the quality of these signals for analysis and interpretation. Comprehensive signal processing software is mostly written for petroleum exploration companies. Commercially available signal processing programs are often limited to a single application or are restricted for use with specific hardware, e.g., a digital oscilloscope or a mainframe computer. The programs may use computer codes that are proprietary, restrict user modification to expand capabilities, or may be hard to interface. They may have insufficient documentation for easy use and be support dependent.

Jan 1, 1990

By Raymond B. Ladoo

"The talc and soapstone deposits of Vermont have been worked more or less continuously for nearly 100 years, but all of the early efforts seem to have been directed toward the production of slabs for foot warmer, and other similar uses. Altho soapstone of good quality occurs at several places, much of the material first utilized was really talc and was not massive enough to be cut successfully. The grinding of talc in Vermont seems to have commenced in about 1902 and has shown continuous growth since that time. Statistics compiled by the Geological Survey in Mineral Resources of the ,United States show that the production of talc in Vermont has increased, from 8,978 short tons valued at $65,525 in 1905 to 93,960 short tons valued at $625,150 in 1917. Until 1917, New York was the leading producer in both tonnage and value with Vermont second, but in 1917, Vermont took the lead in tonnage produced, although not in value, with a production of over 47% of the total tonnage produced in the United States and over 35% of the world's pro-duction. This increase in production will probably be continued, though possibly at decreased rate, for the reserves of talc In Vermont are large.Active talc mines and mills in Vermont are found in four districts: Chester, Windsor County; Rochester, Windsor County; Waterbury, Washington County; and Johnson, Lamoille County, These mines and mills are distributed as shown in the following table:While there are a great many other known deposits of talc and soapstone in Vermont, some of which have been worked, those listed above are the only ones which have survived and are producing on a commercial basis. The closing down of many mines and quarries, for example, those at Perkinsville, Stockbridge, Reading, Cavendish, and Athens, has been attributed to several causes. Of these causes the most important seem to be exhaustion of the deposit, poor grade, long haul to the railroad, poor management due to lack of knowledge of mining methods and failure to consider talc mining strictly as a business proposition. The companies which are now operating with greatest apparent success are those which have realized the present and future possibilities of their industry, and have invested sufficient capital in both equipment and personnel to establish their companies on a firm business basis."

Sep 1, 1919

By H. F. Yancey

Traditionally the Pacific Northwest has relied on hydroelectric power, which has been both abundant and cheap. However, comparatively few hydroelectric sites capable of providing low-cost power remain, therefore the need for supplemental thermal generation, perhaps within the next decade, is generally recognized. Based on the present cost and availability of competing fuels, coal seems to be the logical choice for projected thermal power plants. Power companies and public utilities have become interested in establishing reserves of coal for future use. One deposit explored in 1958-59 lies in southern Thurston and northern Lewis Counties, Wash., near Centralia. Drilling, totaling 22,700 feet, proved the existence of 70 million tons of strippable coal--an ample reserve for the projected power plant. The coal, like most others and particularly those of Washington and Oregon, when mined in full seam section by mechanical methods, would require cleaning to make it suitable for use. The amount and nature of the impurities in this coal dictated a thorough investigation of its cleaning characteristics to establish economic factors and to insure proper preparation-plant design. Therefore, arrangements were made through a cooperative agreement to conduct such work at the Seattle Coal Research Laboratory of the Bureau of Mines. This report describes that investigation. The results are of interest primarily in connection with the utilization of this particular deposit, but some of the information developed is applicable to other deposits of low-rank coals in the West, because the impurities in these coals differ greatly in behavior from those generally associated with the higher rank coals of the Appalachian field.

Jan 1, 1961

During 1990-1999, a total of 458 fires occurred in all coal mining categories; 157 of those fires caused 164 injuries and 2 fatalities. The greatest number of fues and fire injuries occurred at surface mines, whch also had the highest risk rate values. A total of 66 fuefighting interventions were required. Of these, there were 25 mine rescue team interventions in underground mines, including 5 mobile equipment firefighting interventions, and 41 fire brigade and fire department interventions at all surface operations, including 19 mobile equipment interventions. In all, 50 fires destroyed or heavily damaged equipment (including 16 pieces of mobile equipment) because of failure of other firefighting methods, late fire detection, undetected fires, or fire size. A total of 1 14 fires were detected late by smoke, and 42 fires were not detected.

By T. E. Gray

This report describes preparation characteristics of the significant coalbeds in Marion County, W. Va., as determined by the Bureau of Mines. It is one in a series telling what coals are suitable for producing metallurgical coke, either as mined or after beneficiation. Over 9.4 million tons of coal was produced in Marion County, W. Va., in 1958, of which almost 6 million tons was cleaned mechanically in nine cleaning plants. All of the coal mechanically cleaned came from the Pittsburgh bed. The Bureau of Mines estimated that 1,578 million tons of recoverable coal remained in the county in beds 28 inches or more thick as of January 1, 1955.

Jan 1, 1960

By David N. Montgomery

The characteristics of a closed cavity acoustic coupler were measured. Various configurations were investigated to determine their feasibility for use in a portable audio dosimeter calibrator.

Jan 1, 1976

By C. E. Wyndham

The occurrences of manganese In Alabama were reported to be widely scattered over the northeastern section of the State, and these were examined before a development project was started.2/ The most promising and available showings were chosen for further investigation, which include 1 deposit in Goshen Valley, 6 in the Rock Run area, and 2 in the northern section of Calhoun County. The work was performed by the Bureau of Mines from July 29, 1949, to February 17, 1950. The work consisted of power auger drilling 69 holes 3-1/2 inches in diameter and totaling 2,548.4 linear feet. The accuracy of samples from auger drill holes in this type of deposit was determined by sinking two shafts a total depth of 68.17 feet, from which channel samples were cut. Sixteen rotary core holes totaling 1,048.7 linear feet were drilled with a 3-inch, double-tube core barrel. Twenty-two diamond core holes were drilled with a 2-1/8-inch, double-tube core barrel and NX diamond bit. In addition to the above drilling 220.8 cubic yards of soil and rock was excavated by hand from 403.9 linear feet of trenches and 69.7 feet of test pita. A total of 206 samples were taken and analyzed for manganese, iron, cobalt, nickel, and insoluble.

Jan 1, 1953

By Oliver Bowles

"The town of Monson in Piscutaquis County, Maine is the, center of an important site industry. Monson slate has a nation-wide reputation, particularly for electrical switch boards, and the deposits have been worked for the manufacture of such products for many years. Open-pit quarrying is the method most commonly employed in obtaining slate. Underground methods have been used in the Peaon Bottom district near Delta, Pennsylvania, but the quarries that were thus operated are now abandoned. Underground methods have been used more extensively in foreign countries, the most famous example being the slate mines at Angers in France, where an over-head stoping method has been employed successfully for many it is only under special conditions that underground methods can be successfully used. If the deposit is wide and relatively thin, or if the material is too unsound to constitute a safe roof, open-pit methods must be used, for slate is too low-priced a commodity to justify the heavy expense of any timbering methods. It is only where the deposit is relatively narrow, of great depth, and sufficiently sound to afford a strong roof that ordinary mining may be employed.The best slate beds in two of the three quarries operated at Monson are no worked by underground methods. The chief bed worked by the Portland Monson Slate Co. is 10 feet thick, stands vertical and strikes N. 63º F. The slaty cleavage is vertical and crosses the strike of the beds at an angle of 5 to 10°. The grain or second direction of splitting is vertical and perpendicular to the cleavage. In addition to the 10-foot bed, to 2-foot beds and one 5-foot bed are available but are not now utilized. In the Monson Maine Slate Co. quarry (the old Pond quarry),a greater number of beds available, but at present quarrying is confined to a single bed about 9 feet thick which dips 30º S.E. and strikes N. 47ºF. The slaty cleavage is vertical and strides N. 45º F., while the grain strikes N. 45-50º W. and is also vertical."

Nov 1, 1920

By R. L. Brown

This report, the seventeenth in an annual series, summarizes Bureau of Mines research and technologic work on coal and related investigations for July 1, 1951, to July 1, 1952. It 1s based largely on publications issued during the fiscal year, although 10 some instances data are presented that have not been published previously. Footnote references are given to the publications so that further details on the work may be obtained. Bureau of Mines research on the mining, preparation, and utilization of coal is directed toward developing and encouraging safer and more efficient mining practices and preparing and utilizing coals to the best advantage.

Jan 1, 1953

By Arnold B. Hubbard

A thermal decomposition study of the kerogen in three Colorado oil shales was made at different temperatures by heating the shales in the absence of oxygen at atmospheric pressure and measuring the decomposition products (gas, oil, and bitumen) formed. From these data the specific reaction rates, "k", for the thermal decomposition of kerogen were determined for each temperature studied, making it possible to calculate the time required to accomplish a given amount of decomposition within the temperature range. The influence of temperature on reaction rates was presented by plotting the data according to the Arrhenius equation, thus providing a means of estimating the values of "k" for any temperature within the range of this study. It was found that the specific reaction rates for the thermal decomposition of the kerogen in the three sampler were comparatively equal at corresponding temperatures.

Jan 1, 1950

By G. H. Keith

The Bureau of Mines determined the mechanism(s) involved in observed anomalous changes in mechanical properties of vanadium-base alloys. Tensile properties of electrorefined and commercial-purity vanadium-base alloys containing up to 5 atomic percent molybdenum or titanium were measured between 77° and 673° K. Snoek oxygen and nitrogen peak heights were measured to determine the changes in dissolved interstitial content caused by increasing quantities of solute. In addition, changes in lattice parameter were followed wit: precision X-ray techniques. Softening, observed in alloys containing titanium, is explained by the formation of a second-phase titanium compound with oxygen or nitrogen. However, because of partitioning of titanium between compound formation and solid solution formation, about five times the stoichiometric amount was required for complete reaction. Addition of 1 percent titanium drastically lowered the strengthening due to strain aging, at 673° K, and 2 percent titanium essentially eliminated it. All alloys were ductile at 77° K. Variations in the tensile properties of the molybdenum-containing alloys are explained by variations in the amounts of interstitial impurities present. The molybdenum did not react with these impurities and had no effect on strengthening due to strain aging. Commercial-purity vanadium alloys containing more than 2 percent molybdenum were brittle at 77° K.

Jan 1, 1969