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By Griffith. F. E., Glei

"INTRODUCTION For many years protective grounding of electrical equipment has been advocated as a means of safeguarding equipment against damage and of minimizing shock hazards to persons. Several codes are in effect covering in considerable detail the items to be observed in obtaining effective grounding in and about industrial plants. Although the coal-mining industry does not have a comprehensive code of its own covering the grounding of electrical installations, a number of States and individual coal-mining companies have issued codes, standards, or rules that include certain requirements with reference to grounding. As early as 1916, 4/ and again more recently, 5/ the Bureau of Mines recommended grounding, particularly as a means of preventing shock to men working on or around electrical equipment.It is common knowledge among electrical engineers of public utility and mining companies that connecting a wire from the frame of a machine to a rod or pipe driven into the earth does not necessarily assure desired protection of surface equipment. In fact, it has often been found necessary to use several interconnected rods and to treat the surrounding earth with salt or other chemicals before the connection to earth would have sufficiently low resistance to give satisfactory results. Even these expedients have not produced the desired results in some localities. It has also been found that ground connections initially having a low resistance may attain high resistance during some seasons of the year. In spite of such difficulties with surface equipment, it has sometimes been assumed that a mining machine resting on the floor in a coal mine is grounded by virtue of its contact with that floor. It has also been assumed by persons endeavoring to comply with grounding requirements that a peg or rod driven into the mine floor would provide a sufficiently low-resistance contact with the earth to be satisfactory as an electrode for connecting the grounding wire from frames of equipment. That both assumptions may be wholly untrustworthy has been proved by the authors in actual tests with underground machinery."

Dec 1, 1943

By W. M. Myers

"The continued expansion of modern industry broadens the markets for minerals and their product. With these increasing demands new uses are being found for minerals that heretofore were considered as possessing no commercial possibilities. This tendency is reflected in the nonmetallic field in a constantly increasing demand for minerals formerly considered to be of scientific interest only, Furthermore, nonmetallic minerals of established commercial importance are used in new ways in various products, and this tends to expand the markets for these minerals. Some recent outstanding developments in applications of minerals are given in the following pages.The Andalusite GroupAmong the minerals that until recently were considered of scientific interest only, may be listed those of the andalusite group. This group is composed of the three minerals, andalusite, cyanite (or kyunite), and sillmanite, which are all forms of the compound Al2SiO5 (A1203, S1O2), and are therefore identical in chemical composition, but differ in physical properties,"

Mar 1, 1924

By John Ward Smith, Neil B. Young

Shale specific - gravity to oil - yield relationships were developed for black shales of the New Albany Formation of Kentucky from data collected on core samples representing the complete section of the formation in three counties . Linear equations for estimating oil yield from measured specific gravity and for estimating specific gravity from measured oil yield were shown to be applicable within small error limits to all the sites tested . Variation in pyrite content is the largest source of error .

Jan 1, 1964

By James H. Russell

The Bureau of Mines used a statistical approach to evaluate the effects of temperature, current density, and composition of the electrolyte on the purity of boron prepared by electrolysis of a fused mixture of boric oxide in potassium fluoborate. The quadratic equation which best fits the data was calculated for a temperature of 650° to 850° C, a cathode current density of 40 to 1,150 amp/ft2,and a boric oxide content of 0.3 to 7.1 molal. The best products, better than 95 percent boron, were obtained when the current density was less than 2 amp/ft2 and the boric oxide content was less than 2 molal.

Jan 1, 1967

By M. J. Beus

Researchers at the U.S. Bureau of Mines have developed personal-computer-based data acquisition, instrumentation, and mine visualization and modeling techniques to evaluate a mine accessway in a deep hard-rock mine in northern Idaho. These techniques were applied to a mine shaft in a large silver mine that has been in operation for many years. A very deep, rectangular, timber-supported shaft extending to depths exceeding 2.3 km (7,500 ft) had been deforming continuously as a result of nearby mining, resulting in operational problems. Preliminary visual observations and rock and support monitoring confirmed that severe diagonal distortion was occurring. Extensive field measurements and data analysis confirmed initial observations, provided insights into the cause of deformation, and defined a general approach to structural modeling. Computer analysis of the problem was initiated by developing a three-dimensional model of the terrain. This represented a volume of rock approximately 80 km3 (40 x 1010 ft3) and an area on the surface surrounding the mine 9 km2 (3 square miles). Based on this model, a three-dimensional, finite- element analysis was conducted to establish boundary conditions for sequentially more detailed two- and three-dimensional submodels of the shaft area. Results from the computer study are being used to develop new approaches to mine design and to provide design guidelines for deep mine accessways subject to severe rock-mass loading conditions.

Jan 1, 2010

By W. Miola, R. V. Ramaoi

"The MSHA prescribed method for the determination of quartz in airborne respirable-dust samples from underground coal mines is the P-7 method, a combination of /ow-temperature, radio-frequency ashing (LTA) and infra7 red analysis (IR). There is no prescribed procedure for quartz analysis in bulk samples of coal and host rock. Dispersive infrared (IR), Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) methods are most commonly used for the analysis of quartz in powders. Several aspects of the experimental procedures, such as the preparation of the analysis sample from bulk samples, ashing techniques, scanning procedures, peak measurement location, calibration techniques, sample amounts, size consist and data interpretation, affect the results from each of the methods differently. Significant differences in analytical results obtained from X-ray diffraction (XRD) and infrared spectroscopy (IR) on the same samples are reported. All studies point to the need for reliable quartz analysis methods.In a recent research program, a procedure for preparing bulk-coal and host-rock samples for quantitative quartz analysis was developed. Further, the results from X-ray diffractometry and infrared spectroscopy for quartz content on identical samples were compared. Calibrations with pure and mixed standards were used to assess the influence of particle-size distribution, matrix and calibration on the analytical results. In this paper, several issues concerning the measurement of quartz in the samples of coal, host-rock and airborne respirable dust from mines are outlined and quantified. IntroductionThe literature on coal-mine airborne-dust control has identified a need for a better understanding of the sources, mechanisms and amounts of quartz in mine airborne respirable dust (Althouse, 1984; Jankowski, Nesbit and Kissel, 1985; Ramani 1988; Qin, 1988; Bhaskar and Xu, 1990; Bhaskar and Li, 1992; Ramani, Qin and Miola, 1991 ). To understand the quartz content in the source materials, bulk samples of coal and host rock must be analyzed. Establishing an analysis procedure for determining the quartz content in bulk-coal and host-rock samples is necessary for identifying the sources of quartz in mines; for establishing the relationships between the quartz contained in the source and in the airborne dust; and for controlling the content of quartz in the mined product and in the airborne respirable dust."

Dec 1, 1996

By W. M. McKewan

This U.S. Bureau of Mines report discusses wire ropes used for hoisting in U.S. mines. The in-formation presented was extracted from a large body of data compiled by the U.S. Mine Safety and Health Administration (MSHA) using a data base management system (DMS). Further, these extracted data were then manipulated to provide tables of data that show the types and amount of wire rope used for hoisting. This report describes the different types of wire ropes and how a DMS can be used to manipulate MSHA's wire rope inventory data. The data indicate that more 1-1/4-in-diam ropes, 6x27 construction ropes, and right lang lay ropes are used in U.S. mines than ropes of any other diameter, construction, or lay type.

Jan 1, 1991

By John B. Gayle

The coking time has considerable influence on the throughput of a coke oven, and for this reason a large number of papers dealing with the relationship between coking time and the different operating variables have been published. Although all factors known to influence the coking time have been studied, agreement has not been reached on several questions.2/3 Therefore, it appears worthwhile to evaluate any data that become available during investigations of the carbonizing properties of various coals and coal blends. Because it is expected that reports covering several different phases of this problem will be forthcoming as additional data-become available, the following study of the relationship between coking time and bulk density represents a report of progress on the overall investigation of factors influencing the coking time in slot-type ovens. The practice of including coarse coal in the blend going to the ovens to obtain increased bulk densities is well known. Similar increases have been realized by adding small quantities of oil to the coal mix. Although it would appear that such procedures provide inexpensive methods for increasing the capacity of existing coke-oven installations, Ramsburg and McGurl4/ point out that this increase is possible only if the additional coal can be carbonized in the same coking time as regularly employed without using abnormally high flue temperatures. This statement is in substantial-agreement with the position of Auvil and others5/ and implies that any change in bulk density may be accompanied by a corresponding change in coking time. On the other hand, a recent review of proposed methods for calculating the time required for carbonization6/ includes a number of equations that completely ignore the effects of variations in bulk density.

Jan 1, 1954

By C. M. McCulloch

A series of geological surveys were completed in six coal mines in connection with a Bureau of Mines research program on methane control. The aim of these surveys was twofold: First, to study the overall geology of the coalbed, and second to use the resulting data to evaluate the influence of the geological characteristics of the coalbed on safe and efficient coal extraction. This report explains the advantages of geologic maps and fence diagrams in coal mining, and how the knowledge gained from such geologic investigations of mines can help control many underground problems.

Jan 1, 1975

By J. S. Webb

This is one of a series of papers dealing with mining methods, practice, and costs be¬ing published by the United States Bureau of Mires. In this paper a description of the mining practice in vogue at the Braden unit of the Kennecott Copper Corporation is undertaken. PRODUCTION At present (1931) the entire production of ore is being obtained from the Teniente mine. The miring method in use is an adaptation of block undercutting which has been a development of the stoping and pillar caving experience obtained at this property. Improvements in mining practice are constantly being made.

Jan 1, 1932

By d&apos, Kathleen J. Amico

THIS SUMMARY appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U .S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed ?mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operations at or near mines.

Jan 1, 1965

By W. G. Sandell, G. M. Potter

"As a part of the wartime activities of the Bureau of Mines, metallurgical services were extended to other Government agencies engaged in purchasing and stock-piling some of the more critical and strategic materirals. At the request of George A. Easley, representative of the MetalsReserve Company, beneficiation studies were made on a sample of complex tin-tungsten ore from the Urania mine in Bolivia, South America.The low-grade Urania ore (1.9 percent Sn and 1.55 percent W03) contained a very complex of cassiterite and scheelite with iron sulfidesand quartz. The problem involved in concentrating this ore was the removal of sulfides and silica by stage flotation and gravity concentration for the production of a marketable tin-tungsten concentrate. The sulfides and primary quartzite were readily rejected, but the secondary quartz was intimately associated with cassiterite, and ultimate recovery depended on treatment of minus 560-mesh (theoretical) sizes.The ore was amenable to concentration by ore dressing. Seventy percent of the tin and 83 percent of the tungsten were recovered in a product that assayed approximately 20 percent Sn and 20 percent W03 and that met grade ""F"" specifications of the Metals Reserve Company for mixed tin-tungston concentrates."

Feb 1, 1948

By S. P. Kinney

The Department of the Interior has recently investigated the atmospheric conditions in tunnels of the Union Pacific Railroad in Utah and Wyoming , by observations made from the cabs of freight locomotives . This work was conducted by the Bureau of Mines at the request of , and in cooperation with , the Union Pacific Railroad Co .. and was brought about by several accidents to members of engine crews while passing through tunnels , from pollution of the tunnel air by exhaust gases from freight locomotives . The object was to determine the cause of gassing accidents , by examining into composition of the air in locomotive cabs while passing through railroad turmels ; to learn the effect of these conditions on the engine crew; and to provide a means of protection for the men so exposed . Gas samples and temperature readings taken in the cabs of locomotives were used in studying the atmospheric conditions to which the locomotive crews were exposed . The symptoms and the physiologica effects produced in men exposed to the atmospheres encountered were studied . The pulse rates and body temperatures were taken , and the determinations of the carbon monoxide content of the blood were made . Various methods for the prevention of gassing and for the protection of men therefrom were considered and tested , among which were the use of mechanical devices for deflecting the smoke away from the engine cab, and the use of various types of gas masks and breathing apparatus . While this investigation is a part of the safety work of the Bureau of Mines in connection with hazards from atmospheres containing carbon monoxide ( CO ) , the results are of particular value to railroads operating steam locomotives through tunnels , and are also valuable to other industries where atmospheres having poisonous gases or of a high temperature and humidity may be present . The results may be summarized as follows :

Jun 1, 1923

By Harry K. James

Experimental studies of the physical and explosion characteristics of pure hydrazine nitrate and multicomponent systems containing hydrazine nitrate, supplemented with an extensive Literature survey, are presented. Such proper- ties as melting point, heat of fusion, density, viscosity, surface tension, thermal stability, decomposition process, detonation velocity, impact sensitivity, and TNT equivalence are included.

Jan 1, 1970

By Paul W. McGann

THE MINERAL INDUSTRIES had a near-record year in 1950, as rising industrial activity in general, greatly accentuated by the outbreak of hostilities in Korea in midyear, called forth increasing supplies of mineral fuels and raw materials. The aggregate value of mineral production was second only to that in 1948, and the aggregate physical volume was exceeded only in 1948 and 1947. Lower coal production accounted for the failure to surpass these earlier years. Growth of production was fairly constant throughout the year, especially for crude petroleum; its physical output for the year as a whole exceeded that of 1949 by 7 percent. According to Federal Reserve Board indexes, other relative gains were 16 percent for coal, 9 percent for fuels in general, and 17 percent for metals. The increase for mining in general was of the order of 10 percent. This was not quite as large as the general increase in industrial production but clearly reflected the total-industrial trend (see fig. 1).

Jan 1, 1953

By Thomas Varley

"During the past few years, since flotation has become the paramount treatment method for most all kinds of ores, the Bureau has gathered the data on consumption of reagents used in the flotation treatment. The first report was issued in 1916. A brief review of such reports shows the progress made in the art of flotation, and each year brings forth development of new reagents or combinations of reagents that seem sure to survive, but research and progress spell their defeat, if not by entire elimination, at least subjects them to considerable modification. Fortunately, close cooperation between the Bureau and the operators has been the means of an exchange of ideas in research work, and the development, in plant practice, of such research work on a commercial basis, is one of the outstanding features in milling today.In past years flotation has been referred to generally as ""oil flotation""— today it might be more properly called ""chemical flotatioin"" Minerals can be floated today without oil. Chemicals alone will do the work, showing how little was truly known about the process heretofore. The term ""regents as used herein, includes both chemicals and oils. The total pounds of oils and reagents consumed during the year was greater than shown in the 1925 report. The 1926 total was 201,711,795 pounds as compared with 81,688,967 pounds for 1925. The equivalent in pounds of reagent use& per ton of ore for 1926 was 3.933 as compared with 1.7972 for 1925. This increase is due largely to the amount of lime which is added in the alkaline circuits particularly in the mills treating coppers ores, which accounts for the larger tonnages."

Jan 1, 1928

By Nicholas Kyriazi

The Bureau of Mines subjected three commercial compressed-oxygen self-contained self-rescuers to a series of laboratory treatments designed to simulate various environmental conditions in underground coal mines. The environmental treatments consisted of extremes of temperature and of shock and vibration. The tests were designed to predict the ability of the self-rescuers to withstand those environmental stresses without causing a decrease in wearer protection. A critical concern was internal damage to an apparatus that would cause it to malfunction or seriously degrade its performance without any obvious external signs. The Bureau has previously tested chemical oxygen self-contained self-rescuers in a similar research program. Although the three compressed-oxygen units are not as sturdy as the chemical oxygen self-rescuers tested previously, they performed reliably after treatments on treadmill tests with human subjects and on machine tests using a breathing and metabolic simulator. Serious damage was caused by both the heat treat-ment of 71° C (venting of the 02 bottle in most cases), and in the shock treatment (breaking open of the case and dislodging of the components). When physical damage is obvious, a complete refurbishing of the damaged self-rescuer is recommended.

Jan 1, 1983

By N. L. Wimmler

"INRODUCTIONSedimentary deposits of titaniferrous magnetite occur at various localities in the eastern foothills of the Teton Ranse in Deer Lodge County, Mont. The Choteau deposit was examined by a Bureau of Mines engineer in August 1942. An exploration project was recommended.Core drilling exploration was begun in June 1945; it was concluded in August 1945, Seventy-six holes were drilled. This report presents the data obtained by the Bureau of Mines exploration.ACKNOWLEDGMENTIn its program of exploration of mineral, deposits, the Bureau of Mines has as its primary objective, the more effective utilization of our mineral resources to the end that they make the greatest possible contri¬bution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, Chief, conducts preliminary examination, performs the actual exploratory work, and prepares the final, report. The. Metallurgical Branch, R. G. Knickerbocker, Chief, analyzes samples and performs beneficiation tests. Both of these branches are under the supervision of Dr. R. S. Dean, Assistant-Director. The field work was supervised by Earshel W. Newman, engineer in charge of the Helena Field Office. D. B. Hoiekvam was the project engineer; he provided most of the data used in the preparation of this report."

Dec 1, 1946

By Joseph J. Wallace, Lloyd Williams, D. A. Reynolds, James J. Dowd, R. F. Abemethy

"SUMMARY AND CONCLUSIONS1. The investigation shows that the most important beds in Allegany County, from the standpoint of known recoverable reserves are: Lower Bakerstown, Upper Freeport, Upper Bakerstown, Upper Kittraing - less important beds are: Sewickley, Waynesburg, Pittsburgh, and Barton. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 tons per acre-foot of coal in place, are estimated to be 556 million short tons, as of January 1, 1951. Of this total, 304 million short tons is in beds 23 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to permit making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total eat ted reserves.3. Recoverable reserves of coal have been estimated in beds 28 inches and more thick. This thickness is about the minimum now being mined by hand-loading onto conveyors in the Appalachian region. The weighted average recovery for all beds in Allegany County, as determined by this investigation, is 49.8 percent. This percentage is based on the total thickness of coal (less partings 3/8 inch or more thick) in the bed rather than on the thickness of the coal mined. Based on the weighted average percent recovery for all beds in Allegany County, the recoverable reserves are estimated to be 152 million short tons as of January 1, 1951.4. The Allegany County coals are low-volatile bituminous in rank.5. The Allegany County coals are strongly coking."

May 1, 1953

By R. Hogg

"The problems of sampling particulate materials, and of characterizing the distributions of particle size and composition are reviewed. Requirements for sampling from comminution systems are discussed and a simple formula is presented for estimating the minimum sample size needed. The limitations and errors associated with the techniques available for particle size analysis are evaluated and guidelines are suggested for the selection of appropriate methods. The use of microscopic and macroscopic approaches to the characterization of particle composition are discussed.INTRODUCTIONComminution is a process of particle size reduction in which the goal is to produce a material with a specified particle size distribution from a coarser feed. In mineral processing applications, the product size distribution is often qf secondary importance to the extent to which individual mineral grams can be liberated from one another. However, due to poor understanding of the nature of the liberation process and the lack of reliable procedures for characterizing it, the actual specification is normally in terms of particle size.Particle size distribution can be regarded as the fundamental characteristic of a particulate system. The distributions of particle shape and composition among the various particle sizes present are often sufficient to define the bulk properties and behavior of the system. Description of the distributions of size; shape and composition of the different phases which may exist within individual particles is necessary to complete the picture and is especially important for predicting liberation etc., in comminution processes. It is quite obvious that · the complete characterization of real particulate systems is a formidable, if not .impossible task. Practical characterization procedures should involve ·evaluation of those characteristics which are deemed to be important and which can be measured. In comminution systems, this should ideally include the particle size distribution, the size-by-size distributions of particle composition, and as much information as can be acquired on the internal composition and structure of individual particles. In most cases, of course, we fall far short of even this rather limited goal."

Jan 1, 1988