Search Documents

By T. A. Klinefelter

"INTRODUCTION During the development work on sponge iron by the Bureau of lines it was desired to produce a product of maximum density for the furnace. One means of doing this would be to make a plastic mixture of the ground ore and extrude as pellets or large slugs or brick shapes.If a pelletizing Process is employed, the pellets must be strong enough to resist breaking when rolled and tumbled in going through the rotary kiln. If a brick-making process is employed, the brick must be strong enough to withstand handling and considerable pressure when stacked in the kilns.The study had two objectives: first, to find a binder of sufficient strength throughout the early stages of curing and heat treating and, second, to determine the degree of curing and heat treatment necessary to prevent disintegration under normal working conditions.Although the investigation had as its primary objective the processing of sponge iron, the data should interest other industries in which non plastic or poor-bonding slimes are a problem."

Jan 1, 1946

By L. J. Kane

Chemical processes using coal often require economical removal of dust from high-temperature gases. Laboratory-scale investigations by the Federal Bureau of Mines have shown that an aluminum silicate fiber is suitable for filtering dust from gases at 1,800° F. The effects of the bulk density of the filter, rate of gas-flow, concentration of dust in the filter, fiber diameter, depth of filter, and concentration of dust in the feed gas on removal efficiency, pressure drop, and capacity of the filter to hold dust were studied. The laboratory filters were difficult to construct because the fibers were longer than the tube diameter. This caused irregular distribution of fiber that permitted dust-laden gases to leak through channels developed in the filter. Leaks also formed between the filter and the tube wall, but this was minimized by improved filter design. However, edge leaks and leaks through channels in the filter probably would be insignificant in properly constructed filters of industrial size. As the concentration of dust in the filter increased, the efficiency of the low-density filters decreased, contrary to expectations, probably because a higher percentage of the dust passed through channels that developed in the filter. The efficiency of high-density filters, however, increased with the concentration of dust in the filter. Results indicate that loosely packed filters would have a longer life than tightly packed filters at the expense of efficiency. As regeneration or replacement of stationary filters is difficult and expensive, loose filters would be best for filtering gases containing much dust. Gases containing little dust may be cleaned with tightly packed filters to obtain higher efficiency. For either type of filter, precleaning with cyclone separators or other means is advisable.

Jan 1, 1960

By J. M. Riley

A fluorometric method using morin in an alkaline-buffered chelating solution has been developed by the Bureau of Mines for determining beryllium in ores and mill products. Apparatus for measuring fluorescence intensities of the beryllium-morin reaction is described. Preparation of the sample for analysis consists essentially of digestion with sulfuric, nitric, and hydrofluoric acids, fusion of the residue with sodium carbonate and sodium borate, Solution of the melt with sulfuric acid, and proper dilution. Chemical separation of other ions is usually unnecessary. The method rave reliable beryllium determinations on samples in the 0.01- to 0.37-percent BeO range. The method is particularly applicable to low-grade beryllium ores; however, semiquantitative beryllium determinations have been made on beryl containing 12.0 percent BeO.

Jan 1, 1956

By R. W. Nash

This report describes the design and operation of a digital instrumentation package for the Bureau of Mines improved torsion pendulum, a scientific instrument that measures the vibration damping of metallic materials. The new design eliminates manual analog-to-digital conversion, reduces the data acquisition time, and increases the precision of the measurements. The digital output can be coupled directly to a micro-processor or computer to produce the final data in real time.

Jan 1, 1983

By C. Stephan, E. Weiss, J. Trackemas, M. Sapko

The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory (PRL), in collaboration with the Mine Safety and Health Administration (MSHA), the mining industry, and seal manufacturers recently conducted a series of full-scale experiments within the underground experimental mine at PRL’s Lake Lynn Laboratory. The purpose of the experiments was toe valuate the explosion-resistant characteristics of several new seal designs for rapid deployment during mine emergencies. These seals can be deployed in 6 to 10 hr and are capable of with standing explosion overpressures in excess of 140 kPa (20 psi). These novel seal designs use available mine materials, do not require conventional rib hitching, and, most importantly, can substantially reduce exposure time for coal miners during sealing and mine recovery operations.

By J. E. Matta

The Bureau of Mines has developed a tracer gas method for measuring leak-age through permanent mine stoppings. In this method, a temporary brattice is erected in the same entry as the leaking permanent stopping. Leakage was evaluated from concentration measurements of a tracer gas introduced into the space between the stopping and brattice. Stopping leakages ranging from 15 cfm to 265 cfm were simulated in an underground coal mine. Leakage values determined by the new method were within 10 pct of the known values.

Jan 1, 1978

By D. Harrington

The occurrence of dusts in underground workings creates many difficult and, in some instances, contradictory and conflicting problems for workers, operators, and all others interested in health and safety in mining and tunneling. Moreover, there are many misconceptions both as to the actual effect of most dusts which may be encountered in underground work and as to remedial or alleviating measures. Although the harmfulness of mine dusts to health of miners has been mentioned by man; writers in ancient times, much of our really authentic knowledge of the effect of underground dusts upon health or safety in both coal and metal mines has been pained during the past 30 or 35 years. There has been, however, a considerable amount of generalizing from some local condition or occurrence or theory rather than arriving at conclusions after extended studies and observations made not only in mines and tunnels but also in town, camps, and plants, and comprising date on as many different mining and tunneling localities, conditions, etc., as could be secured with reasonable expenditure of time or money. This paper dives sortie observations based on the writer's 30 odd years of experience in and around both coal and metal mines, including approximately 20 years? close study of dust disease with detailed surveys and reports on dust occurrence and effects in considerably more than 100 mines in probably 20 States of the Union. The observatio are those of an engineer and in many respects conflict the with "going" ideas of doctors, pathologists, and others who have written on dust disease. Were the word dust is used in this p: per in connection with respiratory disease, it refers to solid particles which float or can float in the air breathed by workers. Although these particles are usually dry, they may be wet; in general, their dimensions are so small as to be invisible to the nailed eye. Dusts in coal mines which may be involved in the initiation or extension of explosions, are generally thought to be those which are smaller than 20-mesh in size but chiefly finer than 20-mesh; coal-mine dusts which are harmful to health of workers have essentially the same general physical characteristics as other dusts, but usually consist of smaller particles.

Jan 1, 1936

By Walter J. Frank

Thls report summarizes work done under Bureau of Mines contract H0357100, "Development of a Crimp Connector for Trailing Cable Splices." The purpose of this effort was to establish optimum connector design conditions to meet flex cycle, pullout and electrical resistance criteria on phase power conductors. Field testing of "optimum design" connectors is briefly discussed. One of the primary objectives of contract H0357100 was to enable one to design better performing phase conductor connectors. Illustrating the practical significance of this 1s a discussion on the development of a new splice kit for trailing cables. The connectors in this kit were designed in accordance with the design methods described in the contract final report. Kit components, test data, and a connector installation tool are also discussed. The successful effort on the phase connector has resulted in contract H0377042, entitled "Design and Testing of Joining Sleeves for Trailing Cable Ground and Pilot Wires." The purpose of this contract (currently in effect) is to improve ground-conductor and pilot-wire performance. Significant findings to date are discussed.

Jan 1, 1979

By Thaddeus B. Evans

This information circular is one of a series describing mining methods and costs, being published by the Bureau of Mines. The Sunbright mine of the Foote Mineral Co. at Sunbright, Va., is the southernmost underground limestone mine in the State. It is a comparatively recent operation, and a description of its rapid development to production stage may have particular interest for the limestone-mining industry. ACKNOWLEDGMENTS Acknowledgment is made to the executives of the Foote Mineral Company including F. B. Shay, vice president in charge of production, W. B. Towner, general production manager; and to the members of the company staff at Sunbright for their assistance in preparing this paper.

Jan 1, 1957

By Robert R. Stein, Roy C. Bartholomae, William W. Aljoe

This Bureau of Mines report describes in detail the design and operation of a test apparatus for measuring the sound power levels of drills used by the mining industry. The two major components of the test apparatus are a computer-controlled automated drill test fixture (ADTF) and a large (45,000-ft3) reverberation chamber that houses the ADTF. Design specifications and performance capabilities of the ADTF and the reverberation room are given. Initial test results for three types of drills--a pneumatic percussion drill, a hydraulic percussion drill, and a pneumatic rotary drill--are given to illustrate the types of experiments that can be conducted with the test appartus.

By Michael D. Fenton

Bauxite resources were primarily in Africa, Asia, Oceania, and South America. Only five countries combined, Australia, Brazil, Guinea, India, and Jamaica, contained most of the total world reserves available for extraction under current economic conditions and accounted for nearly 80 % of world production of bauxite. World bauxite and alumina production declined and prices for smelter-grade alumina remained below the $200/mt level during 1993 because of growing aluminum inventories on international markets and declining worldwide demand. The United States imported bauxite primarily from Australia, Brazil, Guinea, and Jamaica. U.S. alumina plant capacity remained essentially unchanged throughout 1993, but apparent capacity utilization decreased by the close of 1993. Chromium Most of the world's known resources and reserves of chromite are located in India, Kazakhstan, South Africa, and Zimbabwe. India, Kazakhstan, and South Africa accounted for 73 % of world production of chromite. The two largest producers of chromite, Kazakhstan and South Africa, were in the process of major economic and political change during 1993. South Africa's production and exports of chromite continued to fall during 1993, because of weak international demand and a flood of cheap metal from the former U.S.S.R. and China into world markets. Despite a significant increase in production, South Africa's ferrochrome producers continued to operate below capacity in 1993. Prior o the dissolution of the U.S.S.R., Kazakhstan was a major internal supplier of chromite ore to the U.S.S.R. consumer, but subsequent decline in demand led to a downward trend of chromite production in Kazakhstan and increasing exports to Europe during 1992 and 1993. The United States consumed, about 10% of world chromite ore production in various forms of imported materials. The United States imported nearly one-half of its required chromium contained in chromite ore and chromium ferroalloys and metal from South Africa; the remainder was from the minor producers Turkey, Yugoslavia, Zimbabwe, and others.

Jan 1, 1995

By Will H. Coghill

Recent work on beneficiation of the .Alabama red iron ores and ferruginous sandstones has brought out interesting new facts on particle-size reduction that axe a valuable supplement to what is already known.4/ The work was done by the Southern Experiment Station of the Bureau of Mines in cooperation with-the University of Alabama, University, Ala., on two samples from the Birmingham district. One was an oolitic red iron ore containing about 35 percent iron; the other was a ferruginous sandstone containing about 25 percent iron, particularly attractive because of its low phosphorus content. In both samples rounded quartz (sand) grains were embedded in an oolitic, "onion skin" matrix of hematite. The hematite carries varying amounts of clay, which limits the grade of concentrate that can be made. The clayey hematite is soft, so that the rock crumbles readily under pressure. The sand grains shell out like corn,, and without much exaggeration the mill used for differential grinding might be called a "sheller,"

Jan 1, 1940

By R. D. Saltsman

Under contract with the Federal Bureau of Mines, Bituminous Coal Research, Inc., performed a statistical study to find less expensive and time-consuming methods of monitoring the noncombustible content of coal mine dust. Calculations based on thermodynamic considerations verified the reasonableness of Federal rock-dusting requirements. The results of extensive sampling in southwestern Pennsylvania mines indicated that, at the 95-percent confidence level, the present system of sampling at 200-foot intervals may be replaced by sampling at 500-foot intervals, and that a 1-inch scoop floor sampler may replace the standard 6-inch scoop for floor sampling. Further field testing is recommended.

Jan 1, 1975

By Willis Beckering

The Bureau of Mines designed a cell having four variable compartments in series to facilitate analysis of multicomponent mixtures. Use of the cell considerably decreases the time required for differential absorption analyses. A solution of a major component is placed in each compartment, and the light absorbed by each of these components is varied by increasing or decreasing the path length of the appropriate cell. Simple calculations then establish the amount of the component present. In analyzing unknown mixtures, compensation is made for compounds known to be present, and the differential spectrum representing components not accounted for is recorded and analyzed.

Jan 1, 1966

By W. H. Herschel, E. W. Dean

"IntroductoryThe common practice of the petroleum industry is to measure viscosity by the use of instruments of the efflux or capillary tube type. The Saybolt universal viscosimeter has been tentatively adopted as a standard by the American Society for Testing Materials and is used extensively in the United States.Several instruments of foreign origin are also more or less familiar, such as the Redwood, the Engier, and the Baroey.Effina-type viscosimeters are well adapted to the ordinary needs of petroleum testing laberatories as they are simple and rugged in construction and away to manipulate, even in the hands of operators lacking scientific training. They have, however, certain limitations and for certain spacial types of work there are notable advantages incident to the use of the so-called torsion types of type of viacosimeter. The most satisfactory type of torsion viscosimeter now available in the market some to be that of MacMchael, which has been discussed in detail in a recent paper (Herschel, W. H., The MacMichael Torsional Viscosimeter. Jour. of Int. and Eng. Chem., vol. 12, 1920, pp. 282-286). The present paper indicates conditions under which this viscosimeter may be used to advantage in the petroleum laboratory, and outlines simple methods of operation and calibration."

Jan 1, 1921

By J. B. Littlefield

The Greenburg-Smith impinger was developed at the Bureau of Mines in cooperation with the United States Public Health Service in 1922 in the course of an investigation of dust-sampling instruments available at that time. Although it is not used extensively outside of the United States, it is now soused in this country to collect samples for the determination of any dustiness, and most of the information correlating degree of dustiness with physiological effect has been obtained by the impinger method. The chief disadvantages in the use of the regular impinger, especially in mines and other places accessible with difficulty, are its bulk weight, and power requirements. It requires a source either of electricity or of compressed air, which necessitates connections and extension of existing supply lines to each sampling point; the only alternative is the use of a relatively large pump hand-operated with considerable effort.

Jan 1, 1937

By R. H. King

A very simple cold-bend test was devised and tested for evaluating thermoplastic jackets used on mine-power-feeder cables. A test sample is bent into a semi-circle whose radius is equal to the minimum bend radius recommended by IPCEA and then cooled to the, desired test temperature (-35°C). While at temperature, the sample is straightened by pulling the cable ends with a winch arrangement. The results show that of the jackets tested, those which cannot withstand the test literally burst when the sample is straightened.

Jan 1, 1978

By Robert M. Becker

A thick-wall cylinder solution applicable to the evaluation of anisotropic elastic parameters is derived for the interpretation of stress relief data. For a restricted class of problems, a special relationship among certain orthotropic moduli yields stress distributions for the plane orthotropic problem that are identical to the corresponding isotropic case. A ring or hollow cylinder with these specialized anisotropic properties subjected to uniform radial loads is one of the problems in this class. Consequently, known stress solutions are used to develop the strains and displacements for a specialized orthotropic thick-wall cylinder under uniform pressures. The results are consistent with anisotropic equations used in the evaluation of in situ rock stresses.

Jan 1, 1968

By Edward D. Thimons

The Bureau of Mines conducted in-mine tests to determine correction factors applicable to low-velocity airflows (below 150 fpm) measured by the smoke cloud, vane anemometer, and oil of wintergreen tracer gas techniques 0 The average correction factors found for these methods of measurement were lower than those reported in the literature for use with higher velocity measurements. All tests measured airflows with controlled average velocities ranging from 50 to 100 fpm. Correction factors averaged about 0.75 for readings taken by the centerline smoke cloud method, remotely controlled and stickheld center" line anemometer, and split traverse stick-held anemometer. For hand-held centerline anemometer and oil of wintergreen tracer gas readings, correction factors averaged about 0.67. Since special anemometers are needed to measure airflows in this low-velocity range, and since proper calibration of these anemometers is difficult and expensive, the use of anemometers for low-velocity measurement is imprac-tical. On the other hand, smoke and oil of wintergreen give results as con-sistent as those obtained with specially calibrated, low-velocity anemometers. Furthermore, they are easy to use and inexpensive.

Jan 1, 1979

By James J. Olson

The Bureau of Mines recorded both particle accelerations and velocities from one-stick and production blasts at Eagle-Picher Industries' Shullsburg mine, Shullsburg, Wis., to test the effectiveness of square root scaling in grouping underground blast vibrations and to determine the effects of rock type and mine geometry on blast vibrations. Although the charge weights of subsequent delay periods sometimes exceeded the charge weight of the zero-delay period, both acceleration and velocity records showed that the zero-delay portion of the Shullsburg production blasts produced the highest vibration amplitudes. Because of the restricted range of charge weights in the Shullsburg experiments, no statistical determination of an appropriate scaling factor could be made. However, the square root scaled peak particle velocity data from the Shullsburg production blasts grouped well within the approximate band-width of vibration data obtained by the Bureau from quarry blasts in many different rock types. This indicates that scaling by some factor, perhaps the square root or cube root of the charge weight, may be an effective way to group and study vibration data from underground blasts. Further research is needed to determine which scaling factor is best for underground blasting.

Jan 1, 1970