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By Daniel L. Ng

This Bureau of Mines report describes the results of scanning electron microscopic (SEM) studies of the combustion residues of carbonaceous dust particles resulting from explosions and thermal ignitions in laboratory and full-scale mine tests. The dusts studied varied widely in rank and volatility: Pittsburgh seam bituminous coal (35% volatility), Pocahontas seam bituminous coal (16% volatility), anthracite (7% volatility), graphite, and diamond. The most systematic explosion studies were performed in an 8-L chamber with narrow size distributions of Pittsburgh coal dust with surface mean diameters of 2, 22, and 84 pm. Experiments were conducted mainly in air, with some data obtained in 50% 02. Observations of the bituminous coal explosion residues showed particles with rounded edges, particles with blowholes, and some cenospheres. The lower volatility dust residues showed fewer changes from the original, unburned dust. In addition to the experimental studies, results of SEM observations of residues from a mine explosion disaster are reported. Comparison of such residues with those from the laboratory and experimental mine explosions can help investigators determine the extent of dust participation in the disaster and in identifying the possible ignition sources.

Jan 1, 1983

By James Westfield

Bureau of Mines activities for safety and health in the mineral industries were reorganized during the fiscal year to provide direct supervision by the Assistant Director -Health and Safety. On December 19, 1954, the field offices conducting these activities were designated as district health and safety offices reporting to the Assistant Director. The functions of determining the causes of accidents and injuries in the mineral industries and recommending measures to eliminate them were continued, with satisfactory results in improved safety records. The inspection of coal mines and enforcement of the Federal Coal Mine Safety Act of 1952 were conducted as directed by the Congress, and safety conditions in the mines were notably improved. One coal-mine explosion classed as a major disaster occurred during the year. The causes of that explosion and means for preventing a recurrence were still under investigation because of the extreme difficulty in recovering several portions of the mine. Basic research on the nature of certain hazards and ways of eliminating them is continued. Training of individual workmen and supervisors in this knowledge is a major part of the work.

Jan 1, 1956

By C. Hellar

A new dual-boom remotely controlled roof bolter was designed, fabricated, and then tested in an underground coal mine. Remote-control functions allowed complete bolting cycles to be performed on two booms with both operators located within protective cabs. Capabilities included 3-to 6-foot-long bolts in 5-to 8-foot seams, limited to bolts 20 inches shorter than seam height. Machine was in compliance with all regulations including dust collection, machine lighting, and permissibility.

Jan 1, 1979

By M. A. Trevits, J. E. Urosek, A. C. Smith, M. P. Valoski

Unlike other types of mining accidents, where an incident generally involves only a few workers, the danger of a mine fire extends to every person working in the underground environment. Mine fires can trap or kill those working underground by blocking avenues of escape and rapidly creating heat, asphyxiating gases and toxic fire products that can quickly spread throughout the mine. The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), is conducting research to test, evaluate and improve or modify coal mine fire-fighting strategies and methodologies through large-scale tests. Because wood is the second most abundant fuel available during a coal mine fire, it was decided that a series of large-scale wood crib fire tests was needed to measure the products of combustion and to observe the capability of commonly available direct application fire suppression equipment, namely, fire extinguishers, water and gas-enhanced foam. This paper discusses the wood crib fire tests, provides insight into the products of combustion and describes observations made during the application of the fire suppression agents.1

This publication is the fourth in a series of miners? circulars covering various phases of accident prevention in bituminous-coal mines; these circulars constitute a text hook for courses of instruction on accident prevention in bituminous-coal minim. To these may be added material of particular interest in the field where the course is presented. Other circulars in the series are: Accident Statistics as an Aid to Prevention of Accidents in Bituminous-Coal Mines (Miners? Circular 47). Accidents from Falls of Roof and Coal in Bituminous-Coal Mines (Miners' Circular 48). Accidents from Hoisting and Haulage in Bituminous-Coal Mines (Miners' Circular 49).

Jan 1, 1946

By L. M. Irwin

This Bureau of Mines investigation relates the physical properties of copper reverberatory furnace slags to changes in composition, The smelting of upper Michigan copper ore presents some problems that probably differ from those of other copper smelting areas. The study of these problems has, however, provided important data regarding slags in general and therefore will be of value to other operations as well. Conclusions reached from this study were: (1) Slag fluidity and refractive indices varied directly with the iron content and inversely with silica, lime, and alumina, and (2) there was no apparent correlation between slag fluidity and its copper content.

Jan 1, 1962

By S. L. Gerhard

In the United States the performance characteristics of permissible explosives are controlled by routine tests, which include firing the explosive into a gallery filled with a methane-air mixture. These tests are made by the staff-of the Explosives Division of the Bureau of Mines and are similar, in general, to those employed in other countries. This control has helped to reduce the frequency of accidents involving the ignition of firedamp by explosives but has not clarified the basic causes of the ignition. To advance this control and to minimize potential hazards further, this fundamental knowledge is needed. Some of the results of recent research on the causes of the ignition are described herein. NATURE OF THE PROBLEM When an explosive ignites firedamp in the gallery tests, the source of the ignition must be one or more of the emissions from the steel borehole. It has been accepted generally that these emissions are (1) particles, (2) the shock wave, and (3) hot gases and flames. Photographs show that the shock wave emerges from the borehole first, followed closely by hot gases. At first the velocities of these are high and approximately equal, but the velocity of the gases decreases more rapidly than that of the shock wave, and by the time the reactions causing the flame are complete the shock wave travels in an otherwise undisturbed medium. The particles are originally enveloped in the hot gases but some soon begin to break through and eventually out-distance the shock wave. The approximate geometry of these emissions about 1 millisecond after the shot is fired is illustrated in figure

Jan 1, 1939

By S. L. Gerhard

In the United States the performance characteristics of permissible explosives are controlled by routine tests, which include firing the explosive into a gallery filled with a methane-air mixture. These tests are made by the staff of the Explosives Division of the Bureau of Mines and, are similar, in general, to those employed in other countries. This control has helped to reduce the frequency of accidents involving the ignition of firedamp by explosives but has not clarified the basic causes, of the ignition. To advance this control and to minimize potential hazards further, this fundamental knowledge is needed. Some of the results of recent research on the causes of the ignition are described herein. NATURE OF THE PROBLEM When an explosive ignites firedamp in the gallery tests, the source of the ignition must be one or more of the emissions from the steel borehole. It has been accepted generally that these emissions are (1) particles, (2) the shock wave, and (3) hot gases and flames. Photographs show that the shock wave emerges from the borehole first, followed closely by hot gases. At first the velocities of these are high and approximately equal, but the velocity of the gases decreases more' rapidly than that of the shock wave, and by the time the reactions causing the flame are complete the shock wave travels in an otherwise undisturbed medium. The particles are originally enveloped in the hot gases but some soon begin to break through and eventually out-distance the shock wave. The approximate geometry of these emissions about I millisecond after the shpt is fired is illustrated in figure

Jan 1, 1939

By E. Morrice, R. D. Smith

Thermal expansion and electrical resistance measurements were made on cerium metal from 4° to 300° K. The apparatus developed , including a specimen holder and a cryostat system , are described along with the experimental techniques used in obtaining the measurements . The total linear thermal expansion Data at of 99.83 weight - percent cerium metal between 4 ° K and room temperature was 4.24 percent . The resistivity at 4° K was 7.0 x 10-6 ohm- centimeter . 4° K indicate a fundamental relationship between residual resistivity and purity of cerium metal . The effects of annealing and repeated thermal cycling on resistivity were determined .

Jan 1, 1964

By Raymond B. Ladoo

Cne of t·: . .:: i::,portt recent developrr.ents in the feldspar industcy l:.a.s beer. tl:.e r,:ipid. rise of Ne·N H.v-:psr.ire as a. feldspar producing State. Tl:.e unusual size and purity of t: e deposit now 'being worked ne3.r Keene, and tr.a i.nproved metl:.ods ot:' rr.ining srd ir,illing used l:.ave been responsible foe tt.is situation. ti'eldsp'.:l. w'ls occ':tsiona.lly produced sorr.e ye1rs ago in srr.a.ll (tuantities in New Hrunpshi :e, but t::.e State had not been considered a producer of" feldspar ui til lS3l. In the s::ring of tr .. at yea!', t:.e '[eane iic Products co. of Keene, N.H., beg3Il in a srr.9.ll way tl:e production of feldspar fro:n t1eir property in Gilsum, H.H., whicr. l-.a.d long been opera.tei a.s a :tl.ca mine. The purity of the feldspar at enoe '\ttracted f''.lvorai)le attention. and tt.e production of crude ore rapidly in­ cre'.\sed. Early in 1922, a new company, t'he Golding-Keene Co,

Sep 1, 1922

By John J. S. Sebastian

A laboratory-scale investigation was made of the basic problems involved in developing a ceramic heat exchanger to operate at high temperatures for using nuclear heat from gas-cooled process-heat reactors. Technical data were obtained on transferring heat by forced-convection from helium to air in a single-tube vitreous-alumina heat exchanger. Coolant air was passed through the annulus parallel with, and either concurrently or counter to, the flow of helium inside the tube. The data obtained pertain to removing heat from the helium. Average inside film coefficients were determined at mean surface temperatures of 200° to 1,570° F., inlet-gas temperatures of 1,450° to 2,665° F., and Reynolds numbers up to 560. The gas-to-surface temperature ratios were varied from 1.05 to 7.6. The tabulated results are shown in the appendix at the end of this report. The film coefficients of heat transfer were correlated by taking into account the physical properties of the helium at the average fluid temperature. With experimental conditions pointing to a laminar flow, the Nusselt number was found to decrease as the ratio of gas-to-wall temperature was increased to a value of 3. However, within the range tested, gas-to-wall temperature ratios above 3 did not affect the Nusselt number, regardless of the value of the Graetz number. Thus, beyond this point any increase in this ratio ceased to influence the heat-transfer relationship.

Jan 1, 1962

By J. H. Daniel

This report, summarizing the results of two studies sponsored by the Bureau of Mines, presents information on the types of mobile machines used in surface coal mines in the United States, and the amount of noise to which miners are exposed. Data consist of a calculated value of the probability of noise overexposure caused by specific equipment. These data are extrapolated to estimate the number of overexposed operators. Bulldozers were identified as the major contributors to noise overexposure, and the report presents results of a Bureau-funded program on the feasibility of providing retrofit noise control on bulldozers.

Jan 1, 1980

By Walter L. Fisher

The public interest in the Alaskan situation is such that, with the consent of the President, I have concluded, at the request of the American Mining Congress, to make at this time a candid, if somewhat informal, expression of the views I have formed as Secretary of the Interior, under whose official supervision much of the administration of the Territory is now placed. Pressure of other matters imperatively requiring attention has prevented their presentation in as precise and comprehensive a form as I had hoped. The absence of the President from Washington has also prevented the submission to him of what I have prepared. I wish to say, however, that no one is more earnest than he in the desire to see a policy of prompt and wise development inaugurated in Alaska, and that the general policy contained in this address has been discussed with him, meets his approval, and will have his support. I have recently returned from an altogether too brief but nevertheless a most interesting and profitable visit to those portions of Alaska that are more immediately involved in the questions now under public consideration. Favored by extraordinary weather and the cooperation of steamship and railroad lines and the assistance of all of the governmental agencies, including the Revenue-Cutter Service, I visited every port in Alaska that seems likely in the near future to become an important entrance to the country. I examined all of the harbor and town sites which for this purpose have attracted any considerable public attention. I traversed the entire length of each of the three railroads that have been constructed in the Terri.tory and made a short trip from White Horse down the upper Yukon. Both before and during the journey I examined a mass of books, records,' and papers relating to the country and its resources. I had conferences with official committees representing the principal communities I visited and with numerous individuals, residents both of the coast and of the interi.or, and conferred with engineers, miners, prospectors, railroad officials, business and professional men.

Jan 1, 1911

By W. L. Barry

A review of the practices of analyzing for precious metals at the Reno Research Center, U.S. Bureau of mines, is presented. A general description of fire assaying, the physical layout of a fire assay laboratory, and the use of fire assaying in combination with atomic absorption, induction coupled plasma, and emission spectroscopy is reviewed. The combination of techniques significantly decreases the detection limits for precious metal analyses and simplifies the analysis of the platinum-group metals. Methods of protecting personnel from ingestion of lead are also discussed.

Jan 1, 1982

By EDGAR K. SOPER, Clarence A. Wright, DOUGLAS C. LIVINGSTON, Thomas Varley

In 1917 the Federal Bureau of Mines and the University of Idaho arranged to cooperate in an investigation looking to the improvement of mining and milling methods in the mining districts of the State of Idaho, with an especial view to the wider development of the minerul deposits and greater efficiency in the treatment of the lowgrade ores of the State. This work has been made possible lnrgely through the generosity and active assistance of the mine operators, especially certain companies in the Coeur d'Alene region. As the first step in the work under the cooperative agreement it wa.s decided to gather all data possible on the various mining districts throughout the State, both active and abandoned, in order to ascertain their potential possibilities, especial attention being paid to methods of metallurgical treatment and to the solution of the many metallurgical problems in order to effect a greater commercinl saving. With this plan in view, field work was begun in the latter part of May, 1917, and was continued during the summer. E. K. Soper, formerly professor of mining, University of Idaho, and now dean of the mining department of Oregon Agricultural • College, Corvallis, Oreg., visited the mining districts in central and southwestern Idaho and also some of those in the northern part of the St.ate. D. C. Livingston, professor of geology at the University of Idaho, Moscow, Idaho, also visited some of the mining districts in central Idaho during the summer; in addition, much valuable information he had gathered on former trips to many other districts is included in this report. Credit is also due Mr. Livingston for the maps covering the State, as well as the bibliography nt the end of each chapter. Thomas Varley, superintendent of the Seattle mining experiment station of the Bureau of Mines, spent a short time in the field, principally in the mining districts in central and . northern Idaho, and made a brief visit to the southwestern districts with Mr Soper. The field work of Mr. C. A. Wright, metallurgical engineer of the Bureau of Mines, in direct charge of the cooperative work, was chiefly in the Coeur d'Alene region. Mr. Wright visited nearly all of the mining districts in the region and devoted most of his time to studying the milling methods. The results of the investigation are set 1iorth in this bulletin. The bulletin aims to give the l9Calities of the various mining districts, and the nature of the present operations and those that have been carried on in the past. The geology is discussed only in a general way, the descriptions being intended more especially to bring out the types of ore deposits and the character of the ores, a knowledge of which is essential in determining the proper treatment of the ores. The writers do not wish to imply that all districts mentioned in this bulletin were visited during the summer of 1917, for a great deal of the material has been gathered from other reports, especially from publications of the United States Geological Survey. However, it is hoped that this report will be of help to those who are interested in mining in the State of Idaho. The plan is to continue the field work and subsequently publish the results of the investigations in much more detail, with greater emphasis given the metallurgical treatment of the ores and the problems involved.

Jan 1, 1919

By J. B. Stott

The performance of an adiabatic calorimeter for measuring heats of oxidation of coal is assessed and suggestions made for its improvement and calibration. The use of magnetic analysers for measuring small oxygen deficiencies in air is described and three different methods of measuring the output for such a meter are characterised. The occurrence of spontaneous heating in an 800 tonne heap of Wyoming coal is briefly described. The major part of the report deals with the oxidation of Pittsburgh seam and Wyoming subbituminous coal and describes an experiment in which 1 tonne of Wyoming coal is stored in a 5 metre long insulated container whilst air was passed through. Temperature rises, rates of oxygen absorption and gas compositions of the air stream were measured. The report relates the results of these-experiments to a theory of spontaneous heating developed by Stott and Quan which stresses the importance of the moisture content of the coal and the relationship between the heat necessary to evaporate this water to the heat available from coal oxidation. The work was carried out over a five month period and the emphasis is on demonstrating the effects of moisture transfer and confirming the theory of Stott and Quan.

Jan 1, 1980

By John A. Johnson

"INTRODUCTION The use of wet drilling with adequate ventilation has largely controlled production of dust in drilling rock; however, in some operations, such as shaft sinking and modern tunnel driving, when each of a number of drills is operating in a small cross-sectional area, it is at times difficult to ventilate well enough to keep the dust concentration within desired limits.Some chemical compounds, known as wetting agents, when added to water in small quantities reduce the interfacial tension and make it possible for the solution to wet dust particles more effectively than water alone.This report presents results of tests on the effectiveness of two wetting solutions in reducing the amount of dust produced by wet drilling in basalt.ACKNOWLEDGMENTSThe tests were conducted at the Bureau's Mount Weather Testing Adit, Mount Weathe, Va. The author acknowledges the assistance and cooperation of Wing G. Agnew, superintendent; Marvin M. Reveille, mining-ngineering aide; and the rest of the crew at Mount Weather in conducting the tests. C. W. Owings, mining engineer, Safety Division, assisted in conducting some of the first tests and gave valuable advice and guidance throughout the work and in preparing this report."

Jan 1, 1943

By David Schlain

The Bureau of Mines investigated methods for electrodepositing platinum-group metals from molten cyanide baths. The preparation of thick, protective coatings on molybdenum, Inconel, graphite, stainless steel, copper, and other structural metals were studied, as well as the electroforming of platinum and iridium crucibles. Iridium, rhodium, and ruthenium can be electrodeposited under an inert atmosphere, while platinum and palladium require the presence of air. Electrolytes may be prepared by direct-current electrolysis in NaCN or mixtures of NaCN and KCN using anodes of the particular platinum-group metal. When the concentration of metal increases to about 0.3 or 0.4 percent, the deposits become bright, adherent, and coherent. Current densities may be 10 to 25 ma/cm2, and plating rates are often 0.5 mil/hr. Platinum and palladium baths deteriorate because of the oxidation of cyanide to cyanate and carbonate, and the precipitation of metal. Changes in the platinum cyanide bath are relatively slow. The protection against oxidation afforded by the platinum-group metal coatings is evaluated by testing encapsulated specimens in a thermogravimetric balance. Surface pretreatment and the use of undercoats are discussed.

Jan 1, 1977

By Ned Baker

Details are given of a fuel-induction system for a hydrogen, fueled engine. The induction system was designed to preclude backfire otherwise common in hydrogen fueled engines. System features and test data are presented and discussed in the context of the requirements peculiar to use in an underground mine environment. The fuel induction-system when tested in conjunction with a modified Caterpillar 3304 engine provided backfire free engine operation and satisfactory engine performance.

Jan 1, 1982

By B. J. Barfield

Standard erosion plots (4.6 m by 22.1 m on 9 percent slope) were constructed on the Alston Surface Mine of Peabody Coal Company in Western Kentucky to evaluate the effects of placement technique and density on the erodibility and eroded size distribution from mine spoil and reconstructed topsoil. PLots were constructed with a dozer and scraper pan from shale spoil material, topsoil (A horizon) and subsoil (B and C horizon mixture) using soils stockpiled at the Alston Surface Mine. Plots were evaluated under fallow conditions with a tilled plot surface and two compacted conditions. One compacted condition was generated by tracking the surface with a dozer and rolling with a loaded scraper pan. The second was generated by rolling the surface with a solid wheel compactor. Rainfall was supplied with the Kentucky Rainfall Simulator at a rate of 63.5 mm h-l with the plots in three different soil moisture conditions; dry, field capacity, and very wet. Runoff was evaluated for flow rates, sediment concentrations, and aggregate and primary particle size distributions. Sediment yields and the Universal Soil Loss Equation E130 indexes were calculated from the data for each plot. The erodibility was calculated from the tilled plot data using a weighted soil loss and E130 value from the dry, field capacity and wet runs, and a cover management factor calculated for every other condition. For the topsoil and subsoil plots, sediment yield was greatest for the dozer scraper pan plots and lowest for the tilled plots. For the shale plots, erosion rates from the wheeled compacter plots were the highest and tilled plots the lowest. Average erodibilities were 0.14, 0.38, and 0.41 tons ac h ft-1 tonf-1 in-1 hundred ac-1 for the shale, subsoil, and top-soil plots. Cover management factors for each plot were 1.29, 1.42, and 1.17 for shale, topsoil and subsoil plots compacted with the solid wheeled compacter and 1.29, 3.79, and 2.51 for shale, subsoil, and topsoil plots compacted with the dozer scraper pan conbination. The accuracy of the Wischmeier erodibility nomograph was evaluated on the data collected. Erodibilities were accurately predicted for the topsoil plot and poorly predicted for the sub-soil plot. The accuracy of the CREAMS procedures for predicting the composition (size distribution) of eroded particles was also evaluated. The composition was well predicted for the topsoil plots, moderately well predicted for the shale plots and poorly predicted for the subsoil plots.

Jan 1, 1983