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By J. R. Thoenen

During the year 1927 the Bureau of Mines, at the request of a number of quarry operators, undertook to make a study of quarry operating costs in order to determine average costs for certain operating conditions and to suggest a model cost accounting system for quarry operations. A detailed questionnaire was prepared and mailed by the bureau to all quarries on its records as employing ten or more men in 1926.

Jan 1, 1929

Provide a method for obtaining in situ measurements of coal cutting forces which are needed for mining machine design. Approach A portable in-seam testing device is carried to the face of an underground coal mine heading to measure the cut-ting force encountered by a continuous miner pick directly at its maximum depth of cut. How It Works The tester frame is attached directly to the coal surface with four one inch diameter threaded studs resin-bolted into 1-1/4 inch diameter holes which are drilled 30 inches deep. Spherical nuts and washers compensate for misalignment between the bolts bearing plate, and traverse beams. Spacers can be placed over the studs to assure that the traverse beams remain in the same plane. Cutting forces are applied by a hydraulic cylinder that moves the pick of the tester through a twin-chain arrangement which gives a 20-inch cutting stroke with

Jan 1, 1982

By W. Beckering

IN CHARACTERIZING tars obtained by the low-temperature carbonization or North Dakota lignite, infrared spectra have been an invaluable aid in both qualitative and quantitative examination. Quite early it became evident in the tar-research program of the Bureau of Mines, U.S. Department of the Interior, that the small number of published spectra available for hydroxy aromatics would be inadequate for comparative purposes when dealing with the wide range of compounds present in coal tar; therefore, compiling a catalog of spectra was initiated as a continuing part of the tar program. As these spectra should be valuable to other investigators in this and related fields, they are being presented in this report. This group or spectra (figs. 1-98) represent 97 compounds, largely phenolic materials. The major problem of this project has been the availability of materials for examination. Samples have been obtained from commercial and private laboratories or synthesized at the Bureau of Mines Lignite Experiment Station, Grand Forks, N. Dak.

Jan 1, 1959

By Charles S. Allbright

To develop a method for predicting the stability of a fuel during long-term storage from rapid aging tests at 200° F, the Bureau of Mines determined the stabilities of three gasoline base stocks and an alkylate blending stock in both sealed storage and aerated storage at 110° F for periods extending to 32 weeks. Stabilities of samples containing gasoline-additive compounds were compared by aging, using two methods--rapid aging in a bomb at 200° F for intervals up to 16 hours and storage at 110° F. The additives used were an uninhibited tetraethyllead motor mix, N,N'-di-sec-buty1-p-phenylenediamine and 2,6-di-tert-butyl-4-methylpheno1. Results were related by graphs that enable predictions of gum and sediment formation during storage from data obtained in bomb tests. A premium-gasoline base stock and the alkylate proved to be stable, but the two regular-grade gasoline base stocks were found to be unstable. Addition of the diamine antioxidant improved the stability of both of the regular gasoline base stocks, while the phenol antioxidant improved only one of them. The presence of the tetraethyllead decreased the storage stability of all four fuels, both with respect to formation of gum and precipitation of inorganic sediment. The rapid test at 200° F appears to offer promise as a basis for a method of predicting gasoline stability in long-term 110° F storage.

Jan 1, 1968

By E. E. Remmenga

Often a collection of analytical data, which should reasonably be expected to follow the normal distribution, contains too many extreme values, which the experimenter is inclined to eliminate according to some arbitrary procedure. The stepwise computer procedure described for this purpose is similar to many other truncation procedures; however, because truncation of a basically normal distribution causes a downward bias in the estimated variance, this procedure provides a graphical method to compensate for the bias.

Jan 1, 1971

By Edmund S. Leaver

This information circular is written is response to the marry requests for information on the recovery, or reason for poor recovery, of fine gold by the amalgamation process. Checking Gold Content Experience has shown that in many cases error has been made because the true told content of a particular sample or deposit was not known. Fire assays of representative samples give accurate results and should be considered final in determining the gold content.

Jan 1, 1928

By Oliver Bowles

"The manufacture of asbestos paper began commercially about 40 years age but its principal development has taken place during the past twenty-five years. The asbestos used by the ancients, termed amiantus by Pliny was used for winding sheets, tablecloths and other fabrics. It was probably chrysotile fiber and was a woven and not a felted product, and there¬fore is not to be confused with asbestos paper. There are, however, some early references to paper manufacture that are of interest. Pontoppidian, Bishop of Bergen, in his Natural History of Norway, published in 1750, refers to paper made from asbestos found in the parish of Waldens. He states that this paper did not burn when thrown in the fire, but the writing on it totally disappeared. This indicates that the primary ob¬ject was to obtain an indestructible writing paper. About 100 years later, further efforts were made with the same object in view. In 1853, a patent was issued for a process of making paper from a mixture of asbestos and alum. Many experiments were made to manufacture suitable asbestos printing paper. Some such papers contained only about one-third asbestos, the remainder being of combustible material. Such papers would burn, but would leave a white residue which retained its shape and preserved the written characters. On account of the difficulty of obtaining a smooth and even surface, and the tendency for the material to absorb ink like blotting paper, asbestos paper is not well adapted for writing or printing purposes. Other early uses of asbestos paper were for ornamental wall-paper and carpet linings. None of the uses mentioned above have developed to anything of importance in a practical way, but the manufacture of asbestos paper has become a very important industry, and it has found extensive uses in ways that were never dreamed of by the early investigators.It is recorded that the first sheet of asbestos paper made in America was manufactured in 1876 by John Roberts & Son Company, in a mill near Waltham, Mass. The material first used was a long-fibered amphibole asbestos from Italy. About three years later, Canadian fiber was introduced and proved to be very satisfactory. The shorter grades of fiber which would otherwise be wasted were used for the manufacture of paper and board. For several years, the product of this mill was sold through Rice Kendall of Boston, Mass. From 1881 to 1900, the H. W. Johns Company, of New York, took the entire product which was 30C to 700 tons per year. The latter company built their own asbestos paper mill at Brooklyn in 1900. Keasbey & Mattison Company, of Ambler, Pennsylvania, began to manufacture in 1897. Other early manufacturers were: the Asbestos Paper Company, at Baldwinsville, Mass„ and Mr. B. S. Binney, at Shirley, Mass. The number of manufacturers gradually increased until at present asbestos paper is manufactured by the following ten companies:"

Nov 1, 1919

By Maria I. De Rosa, Charles D. Litton

The U.S. Bureau of Mines conducted experiments for predicting materials' ease of combustion (smoldering onset, smoldering, flaming, and decomposition rates) by means of submicrometer smoke particle characteristics for the development of a simple test method. The experiments were carried out in an approximately 20-L furnace, with a 10-L/min airflow through the furnace for a 14-min duration, at set furnace temperatures of 150°, 250°, and 1,000°C. The variables studied as a function of time were the onset time of smoke particles, time and duration of maximum smoke particle generation, average concentration of smoke particles, and particles' average diameter, mass weight loss, and furnace temperatures. Results show that the onset time of smoke particles is predictive of materials' ease of smoldering, and the time of maximum smoke particle generation and its duration, coupled with mass weight loss, are predictive of materials' ease of smoldering and flaming (depending on the experimental temperatures), and decomposition rates.

Jan 1, 1992

By McHenry Mosier

Although local conditions at each mining property affect the percentage of increase in drilling speed for a given reduction in gage of bit, the results of drilling tests conducted at the Mount Weather testing adit show such a large advantage in favor of the smaller gages that they should be indicative of the possibilities at most mines. GENERAL DISCUSSION Although it is common knowledge among miners that drilling speed ill- creases with reduction in gage of bit, the large amount o this increase is not so universally realized, A recent Bureau of Mines4/ survey of drilling practices in 28 metal mines showed that the maximum gage of starters is 3 inches and that at 50 percent of the mines starters are 2-1/4 inches or larger, Because this size appears too large for conditions at most' mines where abrasion is moderate and where powder distribution permits, the use of smaller bits presents a favorable opportunity for reducing drilling costs.

Jan 1, 1939

By McHenry Mosier

Although local conditions at each mining property affect the percentage of increase in drilling speed for a given reduction in gage of bit, the results of drilling tests conducted at the Mount Weather testing adit show such a large advantage in favor of the smaller gages that they should be indicative of the possibilities at most mines. GENERAL DISCUSSION Although it is common knowledge among miners that drilling speed increases with reduction in gage of bit, the large amount o this increase is not so universally realized, A recent Bureau of Mines4/ survey of drilling practices in 28 metal mines showed that the maximum gage of starters is 3 inches and that at 50 percent of the mines starters are 2-1/4 inches or larger, Because this size appears too large for conditions at most mines where abrasion is moderate and where powder distribution permits, the use of smaller bits presents a favorable opportunity for reducing drilling costs.

Jan 1, 1939

By Charles L. Kimbell

For a study such as this, which summarizes and amalgamates much information collected, compiled, and utilized by the numerous U.S. Bureau of Mines country specialists and branch chiefs for inclusion in their country and regional reports that comprise the five other volumes of the international studies of the Minerals Yearbook, it is clearly impossible to cite all sources of information used in its presentation, but some recognition seems due. Generally speaking, this study and its related detailed studies on countries and areas would be much more difficult, if not impossible, without the efforts of the personnel of our counterpart agencies throughout the world. Information they collect, compile, and then publish, either in their own volumes or those of central statistical agencies in their countries, are the foundations on which this work rests. Thus, we must begin by expressing our appreciation to the multitude of persons employed by these agencies for their contributions.

Jan 1, 1993

By Edward L. McHugh, Charles Sabine, Jami Dwyer, David G. Long

Slope failure accidents were responsible for about 12% of U.S. surface mine fatalities between 1995 and 2003. Small surface movements on a mine highwall may be precursors of failure that, if detected, could provide sufficient warning to enable workers and machinery to be withdrawn to safety. Radar interferometry offers the necessary precision to detect these movements. Radar has some advantages over other methods in its ability to cover large surface areas for true two-dimensional monitoring day and night under almost any weather condition. Radar’s active transmit/receive mode of operation provides for more direct sampling than do passive optical methods that depend on solar illumination. Improvements in microprocessor speeds and capacities have led to the development of a number of small, portable, ground-based systems; such systems are now being deployed at several locations around the world. As part of an ongoing study of monitoring technologies, researchers from the National Institute for Occupational Safety and Health and Brigham Young University, Provo, UT, cooperated to assess the feasibility of using interferometric radar to monitor mine slope stability. Field tests of a device incorporating prototype equipment were successful in that small, centimeter-scale displacements on rock slopes were detected.

Jan 4, 2006

By Roy H. Grau, John C. LaScola

This Bureau of Mines report contains a tabulation of methane emissions during 1980 for all coal mines located in the United States with emissions greater than 0.1 MMcfd. Listed for each mine are methane emission quantity, location, and coalbed. The report also compares records of 1975 and 1980 and describes relationships between emissions in 1980 and the Bureau's coalbed gas content data on 11 mines.

Jan 1, 1984

A general analytical solution of the effect of an inclined contact separating two media of differing electrical properties on a normally incident plane electromagnetic field has been given (Geyer, 1972). These solutions for the electromagnetic response at any observation point P(r, [u]) are given in the form of inverse Lebedev-Kontorovich transforms. Two modes of excitation are considered: (1) case where current density flows across strike of the contact separating the media of differing electrical properties (only Er , E [u] , and Hx differ from zero) and (2) case where current density flows along-strike (only Hr , H [u] , and Ex differ from zero). The electromagnetic fields in the frequency range of interest and for the rock conductivities under consideration are quasi-static in nature so that to a first-order approximation the horizontal magnetic field at the surface of the earth is constant and continuous across the discrete discontinuity in resistivity for case (1) above, and so that the tangential derivative of the horizontal electric field at the surface of the earth is constant and continuous across the discrete discontinuity for case (2) above. Of course, it is well known that where large horizontal gradients in conductivity exist, there also exists large anomalous components of the vertical magnetic field (Weaver, 1963). The recognition of such anomalous components and their magnitudes due to the presence of lateral resistivity changes in the overburden becomes very important in any wavetilt type measurement which may be used to locate a miner. When the lateral change in resistivity becomes quite large, the integral solutions (expressed as Lebedev-Kontorovich transforms) simplify considerably and allow ready numerical evaluation. Examples of the amplitude and phase responses of the radial electric, horizontal electric, and vertical magnetic field in the vicinity of the contrast in resistivity are shown in Figures 2, 3, and 4. Of particular significance is the fact that the anomalous vertical magnetic field is three orders of magnitude larger near the contact than far from the contact. This fact implies that where large resistivity contrasts do occur in the rocks overlying mine workings, that significant errors may be present in wavetilt measurements as used above for location criteria! Another observation insofar as the anomalous vertical magnetic field is concerned is the linear variation of phase as one proceeds away from strike in induction number (increased distance or frequency). For a pulse-excited communications system this phenomena would have a bearing on where the zero crossings would occur (i.e., 'pulse breadth') in the transient coupling between any given source-receiver configuration and at any given receiver site.

Jan 1, 1973

By Charles L. Kimbell

Updated information on market economy country petroleum industry capital and exploration expenditures by geographic area (table 14) was not available in time for inclusion here, thus this information remains the same as was presented in the previous edition of this chapter. The salient statistics on U.S. foreign investment in mineral industry activities (table 15) as reported by the U.S. Department of Commerce has been revised to show the latest information for the years 1986-90.

Jan 1, 1993

By Richard F. Link, George W. Gladfelter, George S. Koch

Contour maps, useful in mineral industries, for example, in analysis of trends in mineralization, may be constructed through statistical methods of regression analysis programed for an electronic computer, For many applica­tions, the resulting maps are more useful and objective than conventional contour maps that are necessarily subjective because they are drawn by hand methods. In principle, an equation is found that fits a quadratic surface to observed elevations of points referred to a datum plane, The quadratic sur­face, represented by a contour map may take the form of a ridge, valley, dome, or basin, Once an equation has been derived, its coefficients may be used to construct a contour map--showing lines of equal value that are derived from the original observed data points by the averaging process of fitting the quadratic surface. Methods employed are illustrated by an example analysis, based on data from a large vein of the Fresnillo mine, Zacatecas, Mexico. Computer programs to implement the methods are described in an appendix,

Jan 1, 1964

Develop design and support guidelines for coal mine entry intersections based upon results of integrated field and numerical modeling analyses of structural parameters for improving ground stability. Background Underground coal mines contain a large number of entry intersections. Dome-shaped zones over the intersections are unstable and are often associated with roof falls. These roof falls may occur during mine development, trapping equipment and endangering miners. These high-risk areas of the mine account for 10 pct of the total number of ground-failure-caused fatalities. The falls, ranging from heights of 1 to 20 ft, cause high dilution and slow the advance rates. Stability at intersections is influenced by four structurally interrelated parameters: in situ stress, geological discontinuities and physical properties, intersection geometry, and roof span. Because of the complex interaction of these parameters, the actual mechanism of roof failure may vary considerably, depending upon the roof lithology, rock strength, and stress conditions.

Jan 1, 1990

By Wilbur I. Duvall

The Bureau of Mines presents a theoretical solution for the stresses and displacements in an infinite elastic plate containing a circular hole whose boundary is subjected to applied shear loads over four separated arcs. The results for the applied shear loads can be superimposed on the results for applied radial loads, given in a previous publication, to obtain a complete two-dimensional approximation of the stresses and displacements induced in the rock by tunnel boring machines anchored in a circular tunnel by means of four props. Analysis of the various solutions shows that the tangential tensile stresses induced on the boundary of the circular tunnel by applied radial loads can be minimized in the roof and floor of the tunnel by the application of appropriate shear loads to each of the four props. Thus when planning tunnel boring operations, consideration should be given to the in situ stress field in the rock and the induced stresses in the rock resulting from the applied radial and shear loads produced by the props of the boring machine.

Jan 1, 1968

Occupational illnesses are more difficult to identify than on-the-job injuries. Many illnesses related to occupational exposures may not be diagnosed until years after exposure; by that time, exposed workers may have changed jobs or left the workforce. Other approaches to identifying occupationally related illness are analysis of death certificate data (see chapter 2) and medical examination studies of workers known to have high exposures to hazardous agents. Figures 5-1, 5-3, 5-4, 5-6, 5-8, and 5-10 show, for each commodity, the percent of illness conditions reported to MSHA by nature of condition. Heart attacks that occurred on the job are reported without regard to work-relatedness. Figures 5-2, 5-5, 5-7, 5-9, and 5-11 show rates by year during 1986-1995 for selected conditions. Since there are many limitations on the accuracy of illness reporting, the frequencies and rates shown here should not be considered directly comparable across commodities. Figure 5-12 shows estimates for hearing loss by age among coal miners compared to a nonoccupationally noise-exposed population. These data come from a study by Franks [1996] of a group of audiograms obtained on coal miners by a commercial company. Using the NIOSH definition of hearing impairment, i.e., an average hearing threshold level for both ears that exceeds 25 dB at frequencies of 1,000, 2,000, 3,000 and 4,000 Hz, the figure shows that by age 30, more than 10% of miners suffer hearing impairment; by age 50, 90% of miners have hearing impairment. In contrast, only 10% of the nonoccupationally noise-exposed population suffer hearing impairment at age 51, and 50% of the nonoccupationally exposed population have hearing impairment at age 69. Figure 5-13 shows a similar analysis of commercial audiograms on male metal/nonmetal miners [Franks 1997]. At age 20, approximately 2% have hearing impairment using the NIOSH definition of hearing impairment described above. This increases to 7% at age 30, 25% at age 40, and 49% at age 50. In contrast, only 9% of the nonoccupationally noise-exposed comparison population have hearing impairment at age 50. Franks' analysis showed a different pattern for female metal/nonmetal miners; they developed hearing loss at the same rate as would be expected for a non-noise-exposed female population.

Jan 5, 2000

Crosson and Peters treat the errors that result in miner location due to errors in the overburden earth model used for computing location. A parallel effort by J. Powell of PMSRC is discussed here, where the location method used is that of the Westinghouse location program - "Miner". This location program was tested by Powell by using arrival times generated from the overburden earth model of Table l* rounded to the nearest millisecond. Location computations were then made using 3 geophones at a time. The average location is tabulated for all geophone triplets except when 3 geophones are in line. Geophone arrays were as shown in Tables 2 and 3. The manner in which the test was done is illustrated in Figure 1. I. SUMMARY OF RESULTS The arrival time differences, based on the Table 1 earth model, together with geophone locations based on the array geometries of Tables 2 and 3, were entered into the computer, together with a stated depth of 700 feet and an estimated overburden seismic velocity of 10,000 feet per second. These parameter values were processed by the location program - "Miner". Figure 2 illustrates the interpretation of the plots and data. The tabular data and plots of Table 4 and Figures 3, 4, and 5 illustrate the location error results obtained. These plots indicate that for sources within the array, the errors are considerably less than the measured errors obtained during field tests of the present location system. The possible reasons for this discrepancy are noted in Part Eight (Earth Models).

Jan 1, 1974