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By J. D. Dixon

The Bureau of Mines has developed structural design data for unreinforced concrete tunnel linings in the form of stress and deflection coefficients from which bending, axial, shear, and boundary stresses, moments, thrusts, and shear forces, and structural deflections can be determined at any point on the lining. Results were obtained by structural analyses of nine concrete-lined tunnel configurations subjected to 22 biaxial load conditions. The tunnel configurations include three basic shapes, circular, rectangular, and horse-shoe, with dimensions based on designs evolved by the mining industry. These analyses were made by the direct stiffness matrix method, a computer-oriented procedure. Numerical results agree closely with those obtained experimentally.

Jan 1, 1969

By Mark I. Copeland

The Bureau of Mines discovered that silicon and nickel additions can prevent the formation of copper alloys of Sn, Sb, and As on the surface of steel during reheating to hot-working temperatures. When molten, these copper alloys cause surface hot shortness during hot working. Wrought steels were reheated isothermally and by simulated industrial practice; the resulting surfaces were metallographically evaluated. The steels contained, In weight-percent, 0.20 C, 0.45 Mn, and up to 1.00 Si, 1.00 Cu, and 0.15 Ni, and up to 0.30 Sn, Sb, or As. The larger the Cu, Sn, Sb and As content of the steels, the greater the amount of silicon necessary to prevent copper alloy formation. A content of 0.10 Ni considerably decreased the amount of silicon necessary for copper steels containing tin and antimony, but not for those containing arsenic. Theories for the beneficial effect of silicon and nickel additions are presented.

Jan 1, 1975

By W. E. Miller, John Campbell, W. P. Yant, G. W. Jones

"Because of its interest in accident prevention, the U.S. Bureau of Mines cooperates with city officials and utilities in investigating the causes of explosions in sewers, manholes, and other underground openings and in developing means for preventing such explosions. For several years this Bureau has been cooperating with the Edison Electric Illuminating Co. of Boston and the Boston Consolidated Gas Co. in detecting and eliminating combustibles and physiologically harmful gases in manholes in the city of Boston and adjacent territory.These Bureau of Mines investigations° have shown that combustible gases from the usual sources — leakage from gas—distributing systems and from underground tanks and gasoline wastes — can be located and the dangerous conditions remedied by a well—planned, adequately supervised, systematic, and continuous manhole survey. However, other types of gas, which are termed here ""soil"" gases, also occur in manholes and are more difficult to eliminate because they have no fixed origin and because seasonal and barometric changes affect their production and passage into the manhole space. These gases appear to be produced by bacterial and fermentation or through reactions of entrapped air in the soil. Soil usually abnormally high in carbon dioxide and low in oxygen, and contain varying amounts of methane. They are especially clangorous to men entering manholes because they lack sufficient oxygen to support life. Owing to the difficulty of constructing gastight manholes the most feasible method for eliminating soil gases from manholes is by ventilation. Consequently the Bureau of Mines initiate 4 study of natural ventilation methods for the removal of these gases from manholes and also for taking care of unforeseen accumulations of combustible gases and vapors.The following factors were considered by the Bureau to be important to the natural ventilation of manholes: (1) Relation of area of ventilation opening* to the capacity of the manholes, (2) size and shape of the manhole, (3) design of the ventilation opening (4) and velocity, and (5) weather conditions."

Jun 1, 1936

By Powell. Alfred R.

"An investigation has been made of the applicability to a variety of coals, other than those from Illinois, of the Powell and Parr method of analysis for the forms of sulphur in coal.A complete study was made of the sulphur in the following coals:- Upper Freeport, Pa.; Pittsburgh seam, Pa.; Pocahontas No. 3, W, Va..; Letcher Co., Ky.; Morgan Co., Tenn.; and Cherokee Co., Kan.The method of analysis gave excellent results when applied to these coals. In the determination of pyrite, the iron-sulphur ratio checked in every case with the theoretical. After the extraction of the pyrite and sulphates, the remaining sulphur was proved to be organic in nature.This work indicated that sulphur exists in coal in three typical forms: - pyrite or marcasite, sulphates, and organic sulphur. A study of the changes which these forms undergo during coking has been made on a variety of coals, and the following five classes of reactions established.First. Complete decomposition of the pyrite and marcasite to ferrous sulphide, pyrrhotite, and hydrogen sulphide. This reaction begins at 300°C., is complete at 600 °C., and generally reaches its maximum between 400 and 500°C."

Mar 1, 1920

By C. Melvin Lepper

To provide the U.S. mining and energy industries with information in the selection of seismic detectors for high-resolution applications, the Bureau of Mines evaluated 35 velocity detectors (geophones) and 9 accelerometers. It was found that velocity detectors with natural frequencies from 10 to 100 Hz were effective for seismic studies in the 5-to 600-Hz spectrum and that accelerometers were most effective in the 100-to 1,000-Hz range. Although the accelerometers described in this report performed about equally with the better velocity detectors tested, the accelerometers showed higher output voltage levels at higher frequencies, which is an advantage. It is important that a seismic detector and its intended purpose be matched properly to achieve the intended results in high-resolution applications. There are many factors that could affect proper matching, thus careful selection of the best detector for a particular application must be exercised.

Jan 1, 1981

By N. A. C. Smith

During the past, six, years, the Bureau of Mines has made and. published several hundred analyses of typical crude oils and 'has developed a system of interpreting the analyses and of classifying crudes. This system is presented here with. It is apparently equate for classifying crude oils into four main groups and has also been found very convenient in studying the geological relationships between crude oils, and the probable refinery yields of valuable products from them. Crude petroleum is morn to be a very complex substance. An analytical statement of its properties must, therefore, consist of two distinct parts, - first, the report of the results of the determinations made by the analyst in the laboratory, - second, the proper arrangement, classification and interpretation of these results so that the analysis, as a mole, will indicate the meaning- and the relative- importance of the essential characteristics of the oil.

Jan 1, 1927

By R. E. Brown

The objective of this Bureau of Mines study was a laboratory-scale evaluation of the sodium sulfate refining process for removing copper from molten ferrous scrap. Maximum copper removal is achieved in carbon-saturated melts at 1,300° C. Low carbon concentrations and higher temperatures result in a less efficient copper removal and an increased sulfur concentration in the iron. Sodium sulfate refining significantly lowers the concentration of aluminum, manganese, and silicon; however, the copper removal efficiency is adversely affected by the presence of manganese and silicon. Compared with other reagents tested, sodium sulfide-forming slags were found to be the most suitable for both copper removal and sulfur control. The sulfur content of the refined iron was higher in tests conducted in acid-type refractory crucibles. Earlier studies showed that tin, a significant metallurgical impurity, is not removed by the sulfate process. During the present investigation, results showed that chlorination, using organic solid sources of chlorine, reduced the tin concentration to acceptable levels in molten iron.

Jan 1, 1975

By Charles E. Munroe

"It has been recently learned that certain foreign manufacturers are offering far importation into this country detonators at greatly reduced prices, some of these detonators being of such low grade (No.4), that their use would greatly increase the dangers in blasting.Detonators and electric detonators are used in initiating the explosion of the various high explosives that are now so extensively employed in a great variety of mining operations. Originally a large number of different grades (or ""strengths"") of detonators and electric detonators were marketed, the grade number indicating the weight of the charge of fulminating material contained in the copper case of the detonator. As late as 1914, a report of the Bureau of Mines (Bulletin 80, A primer an explosives for metal miners) shows that grades Nos. 3, 4, 5, 6, 7, and 8, containing from 0.54 to 2.00 grams each, were being offered for use. However, the writer bad observed as early as 1896, when the more insensitive types of explosives like nitro-substitution explosives began to be introduced for use in mining and other blasting operations, that use of a high-grade detonator was essential to insure certainty of discharge."

Mar 1, 1921

By David R. Hanson

Experimental work performed by the Bureau of Mines in a laboratory environment has shown that the formation of failure zones within certain rock types is accompanied by the emission of significant amounts of radiofrequency (RF) electromagnetic (EM) energy. This radiation was detected using nonresonant, "electrically short," broad-band antennas. Rock types for which emission was observed include granite, quartzite, and taconite; sandstone and marble did not emit measurable radiation. Amplitude spectra of the radiation showed the energy to be concentrated between 10 and 40 kilohertz. These data indicate that emission is directional, but this has not yet been proven. In addition, amplitude of RF emission increases with increasing crack size. Since emission was observed only for brittle quartz-bearing rocks, it appears the formation of piezoelectric fields is a necessary condition for RF radiation. Plausible mechanisms for emission include rapid decay of piezoelectric fields accompanying the sudden stress release at failure and/or the acceleration of an "exoelectron plasma" through the intense local piezoelectric fields. Since emission appears to increase with the scale of failure, and since antennas do not need to be coupled directly to rock surfaces as with conventional geophones, the possibility of developing a portable system to monitor seismically active areas exists.

Jan 1, 1981

By Robert B. Schluter

The Bureau of Mines investigated separating copper-nickel mattes to recover a copper-rich fraction suitable for processing by conventional copper metallurgical processes and a nickel-rich fraction suitable for processing in a hydrometallurgical nickel circuit. Distribution of cobalt and precious metals between the copper and nickel fractions was also determined. A matte containing a nominal 65 pct Cu, 9 pct Ni, 4 pct Fe, and 20 pct S was separated into a copper fraction that comprised 80 pct of the matte weight and contained 70 pct Cu and <1.5 pct Ni, plus a nickel fraction that contained 40 pct Ni and 30 pct Cu. Recoveries of copper and nickel into their respective fractions were 90 pct and 87 pct. These results were obtained in a laboratory flotation cell at a matte grind of 90 pct minus 500 mesh and a pH of 12.4, using 1.7 pounds DPG (diphenylguanidine) per ton of matte as collector and frother. Magnetic separation was used to remove metallic iron-nickel alloy from the copper fractions. Distribution of cobalt was about 70 pct to the nickel fraction and 30 pct to the copper fraction. Silver reported predominately to the copper fraction, while Au, Pt, and Pd were essentially entirely recovered in the nickel fraction.

Jan 1, 1982

By T. M. Garland

A nomographical approach is proposed as a fast, easy-to-use, and reason- ably accurate method for estimating expected discounted cash flow (DCF) rate of return and payout time for onshore development drilling and oil production. All costs pertaining to drilling, completing, and equipping development wells, annual expenses of operation, maintenance, and taxes incurred in producing properties, and crude oil prices were considered in developing the nomographs. This report briefly outlines the origin, derivation, and use of the nomographs.

Jan 1, 1973

By Manuel Gomez

Areal distributions for ash, total sulfur, and sulfur forms were developed for the top 12 inches, the middle section, the bottom 8 inches, and the total seam of Pittsburgh coal in southwestern Pennsylvania. The sulfur and ash exhibit an apparent high local variability. As a general rule, both the sulfur and ash show high concentrations in the top 12 inches and in the bottom 8 inches of the seam relative to the concentrations observed in the middle section of the seam. The high-low sulfur and ash concentrations in the top 12 inches of the seam are not coincident with the high-low sulfur and ash concentrations in either the middle section or the bottom 8 inches of the seam. With respect to sulfur and ash, it is suggested that the top and bottom sections of the Pittsburgh coal may reflect both a syngenetic and epigenetic origin. Present data support the belief that paleotopography controlled Pittsburgh seam deposition. Evidence is presented to show that channels were cut at various times into the semilithified sediments that buried the Pittsburgh seam. In this channeling process, portions of the Pittsburgh coal may have been eroded away. Following channel development, the lower part of the Pittsburgh sandstone filled the complex system of braided channels to produce the "want areas" encountered in present mining operations. In localized areas of the Pittsburgh seam, impingement of Pittsburgh sandstone may be responsible for the lateral displacement of the coal. Information of this type becomes important in the assessment of exploration data, in the development of a quality control system for mine output, and in mine life planning.

Jan 1, 1974

By William A. Vogely

STRIKES in the steel and copper industries adversely affected production in the minerals industry in 1959. Because of an excellent first half of the year and rapid recovery of production after the steel settlement, most statistical indicators were higher than the recession-recovery year 1958. Domestic production of metals declined by 9 percent, but nonmetals (except fuels) increased by 8 percent. Ferrous-metal mine production was down 8 percent, and base-metal mine production was off 11 percent. Employment was high during the first half of the year, but averaged lower than in 1958. Stocks continued to decline as a whole, but crude metal ore stocks actually increased. The indexes of stocks at yearend were still high as compared with 1955. Prices were firm throughout the year. A new index of average unit mine value is presented for the first time in this review; it showed a very slight decline in average mine realization for 1959. The percentage share of supply from imports increased in some commodities, due in large part to the shutdown of domestic iron, steel, and copper industries.

Jan 1, 1960

By S. R. Wilson

[The Anniversary-Bucky pegmatite is one of the largest, dikes in the Quartz Creek district, 21 miles east of Gunnison, Colo. The major dike consists of quartz-albite pear pagmatite and graphic granite with many quartz masses as individual cores occurring within the dike. A mining operation on one of the largest core areas has exposed several mineralogic cones directly associate with the core. These zones, including the large- units of the dike, are quartz pegmatitc, quartz-perthite pegmatite, perthite pegmatite, muscovite-feldspar -quartz pegmatite, quartz-albite pegmatite, and perthite-quartz (graphic granite) pegmatite. Muscovite and beryl are found in the muscovite-feldspar-quartz zone and are the only two products that have been marketed. Other potential products are perthite, graphic granite, and possibly small quantities of columbite-tantalite, monazite, and related radioactive minerals. The Bureau of Mines drilled two diamond-drill holes during April 1950 to investigate the largest and cost promising core area. This, report describes the results of this drilling.]

Jan 1, 1953

By Steven J. Page

The increasing concern for dust control in metal and nonmetal mining prompted the Bureau of Mines to investigate the dust suppression technique of applying foam to face drilling and crushing operations in a gypsum mine. Previous attempts to achieve effective dust control on face drills using other techniques, such as dry collection and boom-mounted external water sprays, have not been successful. The largest problem encountered when using these techniques has been the lack of sustained effective dust capture at the face. Results for two faces studied show that injection of the foam through the drill steel provided an average dust reduction of 95 pct. However, the use of foam on the crusher provided no dust reduction at the operator&apos;s position (because of good local ventilation) and a 27-pct average dust reduction for two feeders at a location midway between the operator&apos;s position and the crusher. The conclusions obtained from this study are that (1) foam can be an extremely effective dust control technique when used on localized dust sources such as dust generated within a blasthole during drilling, and (2) foam is only marginally effective as a dust control technique when used on nonlocalized dust sources such as dust generated during the feeder-and-crusher operation.

Jan 1, 1981

By Maria I. De Rosa

This report analyzes mine fires for all U.S. underground and surface metal/nonmetal mining categories during 1990–2001 by state and six successive 2-year time periods. Injury risk rates are derived, and ignition source, methods of detection and suppression, and other variables are examined. Fires involving contractors are also included in the analysis. The data were derived from Mine Safety and Health Administration (MSHA)mine fire accident publications and verbal communications with mine personnel. The analysis will provide the National Institute for Occupational Safety and Health, MSHA, and the mining industry with a better understanding of the causes and hazards associated with mine fires and an increased awareness aimed at preventing and reducing fire hazards. It will also form a basis for future fire research programs.

Jan 11, 2004

By R. E. Perry

In connection with a program of coal research at the Southern Experiment Station the Bureau of Mines, in cooperation with the University of Alabama and the various coal operators, conducts washability studies of coal from beds in Alabama and other Southern States in which commercially important deposits occur. One of the main objectives of a washability study is to obtain technically and commercially important data necessary for determining the best methods for preparing and utilizing the Nation&apos;s limited reserves of coking coal. Such information is important to conservation because it facilitates selection of preparation methods that will provide maximum yields of coal with low ash and sulfur contents.

Jan 1, 1958

By Kenneth C. Stewart

Eight brands (three samples of each kind) of commercially available audio-dosimeters were performance-tested. Each unit was placed in an anechoic chamber and subjected to various acoustic signals to measure its A-weighting response and overall integration accuracy. All units met the A-weighting tolerance for type II sould level meters, and six brands were within the Bureau I s overall accuracy requirements of ±2 dbA referred to input.

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 Michael S. Wieland

Recognizing the dynamic nature and possible range of toxic concentrations in the impending fume cloud prior to undertaking explosive blasting can reduce potential hazards and mitigate related incidents. The scaled cloud model was formulated to predict the relevant (major) toxic components in fume clouds released by nonideal mining explosives used for surface blasting. Natural turbulence unceasingly disperses the toxic molecules, widening (inflating) the fume cloud while diluting the concentrations, ultimately rendering nonhazardous conditions. The threshold cloud size depends upon the type and quantity of total explosives used and the cloud&apos;s thermodynamic condition. Though the scaled theory works for fume clouds with irregular (odd) shape, an equivalent upright cylindrical form is useful for rendering simple riskhazard scenarios. The cylinder&apos;s projection downward on the underlying terrain yields a circular &apos;shadow&apos; marking the region threatened, thereby permitting a rough estimation of the potential hazards, were the cloud to settle down there. Wind causes the cloud to drift while it expands, so the shadow travels while it grows, until the risk hazard process is truncated at the nonhazardous threshold. The overall relative fume toxicity (RFT) is taken from the traditional Russian RFT rule, which utilizes only the two fume components that tend to dominate the resultant toxicity: carbon monoxide (CO) and total nitrogen oxides (NOx). Tabulated constants that characterize the fume spectrum in the cloud model were resolved for ammonium nitrate (94%) with fuel oil (6%), ANFO-94/6, using a refined thermodynamic work-principle. Comparable results were found with the reduction factor technique, when test results from the underground fume chamber were readjusted to reflect nominal field shooting conditions.