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By A. C. Fieldner

The Bureau of Mines has recently conducted a study of results obtained in analyzing similar samples of coal and coke by 25 laboratories throughout then country, in comparison with results obtained in the Bureau's coal laboratory at Pittsburgh. The purpose of this work was primarily to obtain a comparison of the methods of coal analysis used by the laboratories of the American Gas Association. Therefore, four standard samples of coal end one of coke ware prepared in the Bureau of Mines coal laboratory at Pittsburgh, and portions sent to each laboratory. At the same time, a like number of standard samples were submitted to 12 commercial laboratories rot affiliated with the Association, for the purpose of comparing their analyses with the results is obtained by the U. S. Bureau of Mines and the American Gas Association. Tire comparison is based on the average of 24 analyses by the Bureau of Mines on each kind of coal, and the accompanying curves show the deviation from this average analysis, together with deviations from the check limits of the American Society for Testing Materials.

Jan 1, 1923

By Gregory J. Chekan

As part of the initial investigation and validation of a new boundary-element formulation for stress modeling in coal mines, the underground stresses and displacements at two multiple-seam coal mines with unique stress problems were modeled and predicted. The new program, LAMODEL, calculates stresses and displacements at the seam level and at requested locations in the overburden or at the surface. Both linear elastic and nonlinear seam materials can be used, and surface effects, multiple seams, and multiple mining steps can be simulated. In order to most efficiently use LAMODEL for accurate stress prediction, the program is first calibrated to the site-specific geomechanics based on previously observed stress conditions at the mine. For this calibration process, a previously mined area is "stress mapped" by quantifying the observed pillar and strata behavior using a numerical rating system. Then, the site-specific mechanical properties in the model are adjusted to provide the best correlation between the predicted stresses and the observed underground stress rating. Once calibrated, the model is then used to predict future stress problems ahead of mining. At the two case study mines, the calibrated models showed good correlation with the observed stresses and also accurately predicted upcoming high stress areas for preventive action by the mines.

Jan 5, 1999

By L. W. Higley

Procedures were developed for reclaiming high-temperature alloy scrap in the form of standard cobalt-base alloy. A cobalt-base, multicomponent, high- temperature alloy, such as S-816, can be successfully melted from scrap, and its specified chemical composition can be retained. Induction furnace melting in a controlled atmosphere was used to obtain ingots that were subsequently fabricated by impact forging to provide specimens for heat treatment and testing. Of the numerous metal elements in S-816 alloy, only small quantities of molybdenum were lost in the melting operation as finally developed. Test results indicated that the scrap material, after melting, forging, and heat treatment, was equivalent in room-temperature tensile strength, in high-temperature creep and stress-rupture properties, and in chemical composition to commercially produced S-816 alloy made from virgin material.

Jan 1, 1963

By A. J. Farstad, R. F. Kehrman

Characteristics of metal/non metal mines were evaluated to determine the suitability of applying the U.S. Bureau of Mines electromagnetic location system to the problem of locating trapped driers in metal/non metal mines. Statistical distributions of mine depths and overburden conductivities show that the existing USBM EM system is inadequate for most metal/non metal mines. Alternate approaches to trapped miner location in deep mines were identified and subsequent field tests were conducted at six (6) mines to evaluate their feasibility. The approach considered to be the most promising is one which utilizes the existing manpack transmitting system, modified slightly for a dual frequency output, in conjunction with a sophisticated signal processing receiver on the surface. The main advantage of staying with a "through the earth" approach is that the underground equipment can be kept simple, easily maintained, light- weight and inexpensive.

Jan 1, 1979

By J. R. Wait, D. A. Hill

A survey of the literature on ELF and VLF atmospheric noise has been made. Most measurements have concentrated on the vertical electric field and the horizontal magnetic field rather than the vertical magnetic field which is of interest in transmission between horizontal loops. The limited vertical magnetic field data indicates that the vertical component is generally 10 to 20 dB below the horizontal component. Three laterally inhomogeneous earth models have been analyzed for conversion of horizontal to vertical magnetic field. The rough surface model examines surface effects, the inhomogeneous thin sheet model treats volume effects, and the buried cylinder model treats localized man-made effects. All three models predict the possibility of significant conversion from horizontal to vertical magnetic field. A thin sheet model has also been used to examine transmission from a buried magnetic dipole source. It is found that the pre- dicted fields more nearly model the measured data than does the homogeneous half-space model.

By R. C. Ellman

Significant effects of in-the-mill drying on the pulverization of lignite have been demonstrated in an experimental impact-type pulverizer by tests in which the primary variable was temperature of the sweeping gas. Reduced power requirements and increased product fineness were observed as the extent of drying was increased. Pulverization with in-the-mill drying was studied in comparative tests made on lignites from five mine sources. All of the lignites responded in a similar manner; however, differences in the pulverizing characteristics of the individual lignites were significant. For one lignite, the electrical input to the pulverizer driving motor with minimum sweeping-gas temperature was 33.9 kw.-hr. per ton, decreasing to 14.0 kw.-hr. per ton with a sweeping-gas temperature of 658° F.; for another lignite, at comparable operating conditions, the electrical input decreased from 59.1 to 19.0 kw.-hr. per ton. In the first case, the product fineness increased with increasing temperature of sweeping gas from 65.2 to 79.2 percent through a 200-mesh sieve, and in the second case, from b2.7 to 86.9 percent through a 200-mesh sieve.

Jan 1, 1962

By Joseph A. Sutton

The prospect of utilizing bacteria in mining and metallurgical processes introduces a new and challenging area of investigation. Elements of bacteriology and metallurgy are discussed in connection with possible areas where biological science might be applied in extractive metallurgy. Bacteria may prove important in the selective separation of metals from ores and metallurgical solutions, the production of sulfur from gypsum or pyrites, and the production of sulfuric acid from elemental sulfur. A series of reports concerning the experimental applications of bacteria on minerals and metallic ores will follow this paper. For several years the Bureau of Mines has been investigating the action of bacteria in the oxidation of sulfide minerals and their potential uses in metallurgical processes. Primary attention has been given to the possible utilization of certain strains of autotrophic bacteria that live in industrial leaching solutions or fractures of mineral outcrops. The purpose of this paper is to acquaint the mining and metallurgical engineer with micro-organisms and some of their possible applications in the field of extractive metallurgy.

Jan 1, 1961

By R. S. Olsen

The Bureau of Mines is engaged in a continuing research effort toward the recovery of alumina from kaolinitic clay and other nonbauxitic domestic minerals. Hydrochloric acid extraction of calcined clay is among the acid processes under consideration. Although aluminum is easily leached from calcined clay, the presence of fines and slimes in the leached residue has hindered the application of this and other acid leaching processes. A clay feed preparation method was therefore developed that eliminated the slimy nature and the separation problems normally associated with leached clay residues. The preparation process consists of crushing the raw clay to minus 20 mesh, dampening the crushed clay with a fine water mist while tumbling on a rotating disk, and calcining the misted clay at 750° C. The misting process increases residue settling rates threefold to 9 cm/min (18 ft/hr) and filtration rates by two orders of magnitude. Leaching-kinetics were determined for misted clay feeds in a batch, stirred-tank reactor. Rapid leaching occurred during the first 85 to 90 pct of the extraction. The linear relationship of extraction to time during this initial phase corresponded to a zero order reaction with a rate constant of around 10 pct/min.

Jan 1, 1981

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

MINE VENTILATION NETWORK ANALYSIS

Jan 1, 1977

By Howard C. Turnage, Dana T. Updyke, Wayne C. Muhler

The objective of this project was to develop technical data and evaluate performance and utility of leaky feeder communications systems currently used in North American underground mines. The desired information was obtained principally through on-site surveys. Altogether, six of the seven mining companies known to be using leaky feeder communications were visited. This report covers the findings of these surveys. In addition, the report provides a brief background summary of mine communications, a technical discussion of leaky feeder systems, and conclusions and recommendations based on the results of the survey.

Jan 6, 1980

Develop a method to evaluate the effectiveness of coal scam fire surface seals so that potential problems may be corrected at an early stage, before the integrity of the surface seal is lost. Background Surface seals are the primary coal seam fire abatement method being used in the western United States. Surface seals smother a fire by denying it oxygen. The seal is usually constructed by placing a mantle of soil, four to ton feet thick, over a coal scam fire area to exclude air from the fire. The soil is compacted to increase effectiveness, and a soil cement may be used to augment the soil. In some cases, burning coal may be excavated and separately smothered or otherwise extinguished in another area; in other cases, a trench maybe excavated and backfilled with incombustible material to isolate a fire. More often, a surface seal is simply applied over and around the entire known burning area. In the 1950's, the Bureau of Mines administered a large program to treat numerous coal seam Fires across the western United States. Methods used in this program were described in Bureau of Mines Information Circular (IC) 7932, dated 1959. More recently however, various coal seam fires have been treated with surface seals under the direction of state Abandoned Mine Land Reclamation authorities. It has frequently taken years to evaluate the effectiveness of surface seals. By the time problems become evident, it has often been too late to take corrective action within the scope of the original abatement project. For this reason, the Bureau of Mines developed a means for tracking temperature trends at coal seam fire projects to obtain a better and earlier handle on the effectiveness of surface seals.

Jan 1, 1991

By J. W. Faul

[The Bureau of Mines initiated an extensive research on coal-mine ventilation factors in 1922, large- scale tests being conducted in its experimental nine near Bruceton, Pa., over a period of two years. A comprehensive report an this work is in course of preparation, but in order to place the practical results before the mining fraternity immediately and in condenses form, the more important features will be presented in a number of short papers. The present report is the first of a series dealing with the resistance of coal-mine entries to the flow of air and considers only entries in which there are no obstructions other than the natural roughness of the ribs, roof, and floor.]

Jan 1, 1924

The object of this program was to design and build a self-contained system for remote monitoring of the atmosphere in mines. The system developed uses the mine pager phone line as the primary communication channel and also has the capability of using 208 Hz in the ELF band for wireless transmission through the earth. The depth for through-the-earth trans- mission is expected to be about 80 to 90 meters in high conductivity soil and is limited by the noise level in the ELF band-pass filters. The underground components of the TEM System are energized by mine power through a battery charger - storage battery power supply. In the event of mine power failure the battery capacity is more than sufficient for one week's operation with interrogations every four hours.

By J. P. Barkley

"The accompanying tabulation gives the results of a series of operating tests on two types of small stokers. One was an inclined, natural-draft, moving-grate, overfeed ""hand-stoker"" fired and manipulated by hand; the other was. a horizontal, forced-draft, stationary-grate, underfeed, mechanical unit-stoker operated by an electric motor. These were installed as shown by the accompanying sketches (figs. 1 and 2) under horizontal return tubular boilers of a nominal rating of 150 bl.h.p. each.The steam load carried by these boilers was a rather typical heating load. It was fairly constant and of about 30 bl.h.p. throughout the summer months, with small variation between day and night. During the winter months the daily variations were dependent upon the outside temperature. The boilers were banked a considerable part of the night.As noted in the table, two kinds of coal were used. The size of one kind was run-of-mine and the other 11/4 inch nut and clack. These coals from two different mines of the New River district both caked considerably during burning, the nut and slack more than the other. Analyses of the coal were as follows:"

Jun 1, 1929

By Wilbur I. Duvall

The borehole deformation gage and overcoring techniques developed by the Bureau of Mines form one of the primary methods of determining in situ rock stress. This report describes a least squares method of calculating the average rock stress components in the horizontal plane from more than three diametral deformation measurements in a vertical borehole. This least squares analysis provides a means of determining the multiple correlation coefficient, the variance, and the scatter for a set of deformation measurements. From this information, confidence limits can be calculated for the secondary horizontal principal stresses and their directions. The material presented in this report can be used as a guide to the development of least squares solutions for stress measurement techniques other than the borehole deformation method. Since the statistical information that results from the least squares method is extremely useful in the interpretation of results, it is recommended that a least squares analysis be used on stress measurement data whenever possible.

Jan 1, 1979

By Van H. Manning

"Under the organic act establishing it, the Bureau of Mines is authorized to conduct investigations designed to improve health and safety conditions in the mineral industry and to promote efficient development and utilization of our mineral resources. The field of the Bureau's activity, therefore, begins with the commercial development of mineral deposits and ends with the production and utilization of the final marketable product.In order to serve more efficiently the various sections of the country, the Bureau has established, in addition to its main offices at Washington, D. C., eleven field experiment stations, three field offices and several mine rescue cars and mina rescue stations. These field branches are so distributed as to cover most of the mining districts of this country, including Alaska. The field service in general deals with specific experimental problems, cooperative work with non-governmental institutions, and mina rescue work, while the Washington office is the administrative head and is responsible for the distribution of general information, the chiefs of the technical and administrative divisions of the Bureau being stationed there.The Bureau is prohibited by law from doing work exclusively for the benefit of any private company or individual. Generally speaking, the Bureau does no assaying, ore testing, or similar service work for the benefit of private companies or individuals. In response to requests for work of this sort a list of assay and ore testing laboratories is supplied. In referring inquiries to com-mercial laboratories or consulting engineers, care is taken to mention several names so as to avoid designating any one establishment or engineer."

Apr 1, 1920

By Parviz F. Rad

The Bureau of Mines conducted groove cutting experiments in marble, lime-stone, granite, and quartzite with a 7-inch disk cutter under a normal thrust of 7,000 lb. The values of muck weight per unit length, specific energy, cutting coefficient, and groove depth for each of these rocks were determined for groove spacings ranging from 0.1 to 4 inches, and from these results the values of optimum and critical spacing were computed" The results indicate that compressive strength may be used to predict some of the cutting characteristics of the independent grooves. Considering all the cutting characteristics, particularly those for the interacting grooves, Shore hardness, coefficient of rock strength, and torsional velocity correlate with cutting characteristics better than do other physical properties. Some of the field applications of the principles established in this report are identified.

Jan 1, 1974

By F. W. Cox

Exhaust emissions were measured from 25 aircraft turbine engines using Jet A fuel. Analytical apparatus, procedures, and results are described. Carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide, and aldehydes were measured at engine operating modes representing power levels used in airline operation. Carbon monoxide, hydrocarbon, and aldehyde emissions were highest at idle and lowest at takeoff; oxides of nitrogen were lowest at idle and highest at takeoff. Of the total oxides of nitrogen emitted, nitrogen dioxide constituted from 10 to 100 pct, depending on the exhaust gas temperature. Engines retrofitted with smoke-reducing burner cans produced less carbon monoxide, hydrocarbon, and aldehyde emissions, and slightly more oxides of nitrogen then engines with standard burner cans.

Jan 1, 1972

By C. E. Wethered

This paper describing the mining methods employed by the Federal Mining and Smelting Co., operating the Morning mine at Mullan, Idaho, is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The daily tonnage produced at the Morning mine, including that mined by leasers, is 1,100 tons. Mine run of ore will average 9.1 per cent lead, 5.8 per cent zinc, and 4.4 ounces silver per ton. A stull set and fill method of mining is employed.

Jan 1, 1930

By Charles B. Kenahan

Application of ultrasonics in the electrolytic deposition of metallic manganese and manganese dioxide from sulfate electrolytes had several effects. Ultrasonics produced finer-grained deposits of electrolytic manganese at all current densities than obtained in normal cell operation, but at high current densities it resulted in less adherent deposits. Ultrasonic radiation did not affect cell voltage or cathode current efficiency. In the electrodeposition of manganese dioxide at 70° C., ultrasonic-; increased the current efficiency and decreased the cell voltage at a current density of 9 amperes per square foot, but it had little effect at current densities above this. The decrease in cell voltage was caused by the depolarizing action of ultrasonics at both anode and cathode. Ultrasonic radiation produced a smooth, glossy, adherent, and pit-free deposit at all current densities and at each temperature. Radiation had no effect on current efficiency or cell voltage at 90° C. Ultrasonics was more effective than conventional agitation in producing all of these effects.

Jan 1, 1962