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By Ralph L. Windrow

This paper is one of a series being prepared for and published by the United States Bureau of Mines describing methods and costs of mining and preparing sand and gravel for market at various plants throughout the United States. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. The Clowdy plant, with which this paper deals, is located 7 miles west of Dallas, Tex., and has a rail connection with the Texas and Pacific Railway. In addition to the rail outlet there is a paved road over which materials produced at this plant can be moved into Dallas by truck.

Jan 1, 1932

By G. Dale Cor, Will H. Coghill, M. F. Williams, I. L. Feld

"INTRODUCTION During the past several years the Southern Experiment Station of the Bureau of Mines, with the cooperation of the University of Alabama, has given attention to hydraulic classification. One of the things this work has revealed is a variability not generally recognized in the conditions of teeter at different depths. This report depicts the passage of material through a teeter column and its emergence as a classified product.The work was made possible through the development of a classifier for several hundred pounds per hour permitting a small quantity of coarse spigot material to be discharged without the usual interruptions caused by stop-pages. Previous designs of small classifiers have been unsatisfactory because the,orifice used to control the quantity of spigot product as subjectto stoppages, particularly when attempting to discharge a small quantity of although the classifier used in this work has been described in detail in a previous publication 6/ its principal features will be discussed briefly herein. The main subject matter of the paper is based upon the three figures that illustrate in panorama the conditions that exist in a classifier during the continuous classification of bituminous coal, anthracite coal, and an iron ore trailing."

Jan 1, 1946

By Katherine Harding

This Bureau of Mines publication describes a practical approach to sampling that does not require elaborate statistical techniques. Simple steps are given for finding a cutoff point in the response from a repetitive survey. This procedure can be used to estimate the aggregate value of the characteristic being measured without waiting for a complete count from the survey. This is a useful technique when the reference periods are repeated at frequent intervals, such as monthly and quarterly, and when the statistical collecting agency is engaged in publishing timely data which must be accurate economic indicators.

Jan 1, 1971

By H. Tomlinson

The development of the Sevier Valley Coal Co.'s mine marks the opening of the Salina Canon coal district in Utah. The mine is favorably located with respect, to the existing markets of the West, and if the present estimates of the amount of workable coal in it are accurate it has many Important advantages in favor of its development. This mine is situated 18 miles east of the town of Salina, Sevier County, Utah, which at present is the nearest shipping point oh the Marysvale branch of the Denver & Rio Grande Western Railroad, and is about 152 miles south of Salt Lake City, which is the distributing center for much of the coal from the Carbon - Emery coal field and is the place from which nearly all Utah coal shipped to San Francisco and points on the northern Pacific coast has a common haul.

Jan 1, 1930

By John Gross

The modern practice of grinding ores so that often 80 per cent or more of the product is finer than 200 mesh makes it desirable to supplement sieve sizing so as to extend considerably the range of sizing. Moreover, the fact that the material finer than sieve size represents the major part of the work done in grinding emphasizes thick need in can investigation of crushing efficiency. A method based on the settling rate of particles in grater appeared to be most practical for sizing; finely ground ores. There are two possible methods of utilizing this principle: one based on free settling or sedimentation; and the other on separation by means of a rising; current of water, or elutriation. In sedimentation, mechanical entanglement causes material at the start to settle in a mass, and this persists throughout. As this feature is largely eliminated by elutriation, which permits a comparatively clean separation of the various sizes, the elutriation method was adopted.

Jan 1, 1929

By R. W. Stahl

"This study by the Federal Bureau of Mines was confined to pillaring with continuous mining machines and to mines where total extraction is practiced. Many different conditions and practices in as many coalbeds as possible in Pennsylvania were observed.Pillar extraction or pillaring can be the most productive part of coal mining if done properly; but it also can be the most dangerous if done improperly.Because of the need for more careful planning before and caution during pillaring, many mining companies resort to the undesirable practice of stumping or hogging of pillars with subsequent unnecessary waste of valuable natural resources. Pillaring can be done at reasonable cost and safely, as proven at many mines where complete extraction is practiced and enviable cost and accident records are maintained.Although continuous mining machines are bulky and sometimes difficult to maneuver, they have been used with great success in pillaring. Occasionally, however, a machine is caught, or men are injured by a fall during pillar recovery. This Bureau survey was conducted to ascertain how safe and successful pillaring (especially the removal of final stumps in lifts or the final stump of a pillar), is accomplished in some mines, while others have considerable difficulty under similar conditions.The Bureau hopes the information to be presented in this publication will prove beneficial to those who wish to recover more pillar coal and to improve their accident record during such procedures."

Dec 1, 1959

By Howard F. Puariea

This paper is one of a series describing methods and costs of recovering sand and gravel from alluvial deposits in the United States and deals directly with the methods employed by the Portland Gravel Co. in operating a clamshell dredge on the Willamette River near Portland, Oreg., and a pump dredge on the Columbia River near Vancouver, Wash. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local expenditures only and not total production costs. It is recognized that publication of total costs may in some instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1932

By L. H. Lange, F. F. Hintze

"Mineralogical Composition of Cyanite RockIn the group of minerals used in making this study, the cyanite is associated with quartz, mica, and feldspar in the schist. The amount of quartz is variable, but it is always an abundant mineral. Both large and small crystals of quartz occur in irregular masses, rarely ever showing crystal outline. Mica is of the clear and dark varieties the larger crystals being dark as a rule, and the finer crystals of light color, The present mineralogical composition of the mica is rather variable as most of the original biotite and muscovite have suffered alteration, and much secondary mica is present as a result of alteration of the original mica and other minerals present, especially the larger cyanite crystals. A large part of the mica now found in the ore is chlorite, with varying amounts of Jefferisite and others, especially sericite. These are in the form of aggregates, or felt-like intergrowths filling the spaces between the quartz, cyanile, and feldspar.The feldspar is plagioclase probably mostly albite. It is white, possesses good cleavage, and is one of the hard brittle minerals of the rock. It alters to kaolin, and sericite, and more or less of these alteration minerals are present within the feldspar crystals but not separated from them.The cyanite is of two varieties, distinguished by their colors as blue and white cyanite. The blue color varies in intensity, being a pronounced blue in some crystals and paler in shade in others. Some crystals have been seen which possess the blue color in one-half of their mass and are pure white or clear in the other half. The purity of the cyanite is probably not affected by the color, but it is difficult to detect the white cyanite in the ore by macroscopic examination, so that great care has to be exercised in the selection of the ore in the field."

Apr 1, 1931

By F. F. Hintze

In the group of minerals used in making this study, the cyanite is associated with quartz, mica, and feldspar in the schist. The amount of quartz is variable, but it is always an abundant mineral. Both large and small crystals of quartz occur in irregular masses, rarely ever showing crystal outline. Mica Is of the clear and dark varieties, the larger crystals being dark as a rule, and the finer crystals of light color. The present mineralogical composition of the mina is rather variable, as most of the original biotite and muscovite have suffered alteration, and much secondary mica is present as a result of alteration of the original mica and other minerals present, especially the larger cyanite crystals. A large part of the mica now found in the ore is chlorite, with varying amounts of Jefferisite and others, especially sericite. These are in the form of aggregates, or felt-like intergrowths filling the spaces between the quartz, cyanite, and feldspar. The feldspar is plagioclase probably mostly albite. It is white, possesses good cleavage, and is one of the hard brittle minerals of the rock. It alters to kaolin, and sericite, and more or less of these alteration minerals are present within the feldspar crystals but not separated from them. The cyanite is of two varieties, distinguished by their colors as blue and white cyanite. The blue color varies in intensity, being a pronounced blue in some crystals and paler in shade in others. Some crystals have been seen which posses the blue color in one-half of their mass and are pure white or clear in the other half. The purity of the cyanite is probably not affected by the color, but it is difficult to detect the white cyanite in the ore by macroscopic examination, so that great care has to be exercised in the selection of the ore in the field. Of the above minerals, cyanite is the heaviest, having a specific gravity of 3.6; none of the others approach it in specific gravity. The usual as opiates of cyanite in the mica schists are garnet, magnetite, and tourmaline, but these have not been noted in the group of minerals treated, and their absence is a point of great value in favor of this ore, as they possess high specific gravities and interfere in separation processes, and if not separated they are detrimental because of their easily fusible character. Small amounts of apatite and titanite have been noted, but not enough to cause trouble.

Jan 1, 1931

By Lowell B. Moon

Regardless of how a mineral deposit in first discovered or by whom, any mining enterprise based upon it must pass through a preliminary stage of exploration. The common understanding of ?exploration? among mining engineers is well-expressed by Jackson and Knaebel:3/ Exploration work ranges from that performed by the individual prospector employing only the simplest tool, and equipment to elaborate campaigns involving the expenditure of largo stuns of money end the use of churn- car diamond-drilling equipment, large test-pitting crews, or sometimes a regular mining organization. In any event, the object is to determine as accurately as possible, with the funds available, the size, shape, and other characteristics of the ore bodies and their average value or grade.

Jan 1, 1945

By J. N. Geyer

In coal mining it is essential to maintain the roof over working places and roadways in the safest condition possible. To this end every effort should be made to win the coal with the least injury to the immediate roof strata, as broken strata certainly present a greater hazard than a sound roof. The chief causes of injury to the roof in mining are inherent in the method of development and recovery and the blasting practices followed. The first, which may produce severe stresses in the roof, weakening it over comparatively large areas has been discussed in previous papers3 and will not be treated here. The second cause is local in effect, but with the same general method of blasting being employed throughout a mine having uniform roof conditions, similar effects on the roof may be expected. In the Bureau's investigation of accidents caused by falls of roof and coal it has been necessary to make a careful study of blasting practices and their effect on the immediate roof. The purpose of this paper is to show the effect of the observed methods of blasting on different types of roof and to point out methods that have been proved to be least harmful to the roof strata. The data used in preparing this paper have been compiled from reports made by Bureau engineers engaged in the study of falls of roof and coal, and embrace mines opened in the Pittsburgh coal in Ohio and Pennsylvania and the Pittsburgh and Sewickley coals in West Virginia.

Jan 1, 1933

By Walter T. Ackley

[The geophone has occupied a prominent position as a mine signalling device since its first introduction. The Bureau has carried out tests at different times with a view to improving the early geophones. The following paper describes briefly the adaption of the vacuum-tube audio frequency Amplifier to a new form of geophone. It is not intended to convey the idea that the results described are sufficient to warrant the drawing of definite conclusions as to the practicability of the electrical geophone, but the data and tests liven herein are made public because of their possible use to the industry and as a result of inquiries received as to the feasibility of such adaptions and modifications of the early geophones. Because of the limited time available to the authors, only one geophone with its auxiliary amplifier was constructed. As is well known, two geophones are necessary in order to determine the direction of a sound. Although the principles upon which the electrical geophone operates appear to be fundamentally correct, it is not possible to state whether two such devices 'rill function as efficiently, (as regards determining direction of sound) as the present geophone. In order to operate efficiently as a direction finder, the amplifiers of the electrical geophone must each amplify with exactly the same degree of magnitude. By proper design and adjustment this can probably be accomplished without greatly complicating the design. inasmuch as audio frequency amplification is used, no tuning; is necessary as is the case with tuned radio-frequency circuits. The same filament and plate batteries can be used to operate the amplifiers and by the use of dry cell tubes, requiring shall filament and plate currents, it if believed that a compact, portable and practical instrument can be evolved. Further investigations of the electrical geophone should be conducted to determine the points outlined in this preliminary report.]

Jan 1, 1924

By EINAR M. ARENTZEN

This information circular. deais primarily with an engineering descrip- tion of a type of longwall cutting and loading machine developed by Eick- hoff Maschinenfabrik, Bochum, Germany..: This machine is supposed to have been developed and tested during the latter part of 1941 and early 1942. The only source of information is con- tained in certain literature and engineering data, with drawings which were acquired by the Allied Military Authorities when Germany was occupied; and the information will have to be limited because the writer has not seen the machine in the factory or in operation. However, the information may be of interest to the coal-mining industry in this country, and for this reason our Government has decided to publish the data procured so far. The Eickhoff cutting and loading machine is particularly suitable for the longwall mining system. It can only be used under that type of mining system and is not suitable for the more common type known in this country as room-and-pillar work. The material for the description of the machine and its operation was compiled and translated from German drawings and operating instructions. These detailed drawings and instructions are on file with the Bureau of Mines and are available for inspection by any responsible person interested in the details of the construction of the machine.

Dec 1, 1946

By William J. Campbell

The purpose of this investigation by the Federal Bureau of Mines was to design and construct a fluorescent X-ray spectrograph for dynamic rate studies of selective oxidation in molten metals and to establish basic principles for interpretation of data obtained by this method. An X-ray spectrograph was constructed in which the sample holder is a resistance wound furnace; it was operated up to 800° C. in oxidizing atmospheres. No difficulties were experienced with the cooling or heating systems nor with the protective layer of mica around the X-ray tube window, even though the oxidizing surface of the metal is only 0.5 inch from the X-ray tube window, Means are provided for heating under controlled atmospheres for selected time? temperature cycles.

Jan 1, 1961

By W. Dan Walker

In an effort to keep mine hoist accidents to a minimum and to impart to managers and workers the essential elements that enter into safe installation and maintenance of hoisting equipment, the Bureau of Mines presents this Information Circular as a guide. Hoisting of men and materials is an essential operation in many mines and has become so commonplace that some persons are likely to ignore day-to-day inspections or become lax in the operating phases. With proper maintenance and operation, hoists can be exceptionally safe. However, lack of strict attention can invite tragedy or costly shutdowns.

Jan 1, 1961

By J. W. Horne

The United States Bureau of Mines in cooperation with the State of Colorado at the University of Colorado has conducted experiments to determine the amount and composition of the noncondensable cases evolved when crude shale oil is distilled under pressure. Hydrogen sulphide is one of the components found in the complex mixture of uses produced by the distillation of shale oil under pressure. This paper deals with the apparatus and method used in determining the amount of hydrogen sulphide evolved in the laboratory experimental cracking stills.

Jan 1, 1931

Heavy liquids have come into use in ore-dressing investigations, as they make possible the separation of an ore into its specific-gravity components. A paper containing a general dissertation on heavy liquids has been written by John D. Sullivan,4 and the practical application of heavy liquids is explained by Box and Crabtree5. Some heavy liquids become discolored after continued use, and the lack of transparency impairs their value. Since they are fairly expensive, reclaiming is desirable. This paper briefly discusses the preparation and care of some of the more common heavy liquids.

Jan 1, 1928

By A. R. Elliott

"In addition to the usual interpretation that is placed on the words ""thief"" and ""thieves"", the petroleum industry also uses these words when referring to an instrument that is used for taking samples of oil from a tank or reservoir. It is an abbreviation of the term ""thief-tube"". It is desirable in sampling volumes of oil in tanks or reservoirs to obtain samples at different intervals below the surface of the fluid, because of the variation in the character of the oil at different depths. It is for this purpose that the ""thief"" is used.The subject of oil thieves is probably as old as the oil industry itself. Opinions as to which is the most practical instrument for thieving oil in tanks, to obtain a true average sample, differ wherever oil is produced and is analyzed. Every district, and even many of the companies within the district, will have different appliances for ""grabbing"" oil samples. It is interesting to note in passing that though the thief has an apparently insignificant part in the handling of oil, yet the results depending on it are of paramount importance practically every branch of the transportation, refining, and marketing of petroleum. Determinations, particularly dependent on a representative sample, are made by the centrifuge, laboratory distillation tests, and the hydrometer.The purpose of this article is to discuss conditions found in the California fields. Only a general description of types of thieves and the methods of using them will be given. However, it is believed sufficient data are given to enable the reader to form his own opinion as to which of the devices is most practicable under the prevailing conditions. Thieves of all types have their good points, speaking broadly, and it is possible to get good results with any of them, provided they are operated according to instructions and with due care. In work of this kind the advantages or disadvantages reside in the person operating the instrument rather than in the instrument used."

Apr 1, 1920

By Edward D. Thimons

The Bureau of Mines conducted a state-of-the-art study of techniques currently employed to close large openings in underground mines. A large opening was considered to be any opening over 10 feet high and having a cross section of at least 200 square feet. Five salt mines and one limestone mine were visited to observe various methods of sealing large openings. Because of the variations in conditions from mine to mine, no definite conclusions could be drawn as to which is the best method. In mines where waste material is available, stoppings built by piling waste material are efficient and economical. Where waste material is not available properly constructed brattice cloth stoppings are superior to those built from wood, concrete block, or urethane foams.

Jan 1, 1975

By E. J. Gleim

Contact with trolley wire in the mines of the United States has taken a considerable toll of life throughout the years that trolley locomotives have been employed as a means of' transportation. A study3/ of the records over a 15-year period for one State alone showed that, of 98 fatalities resulting from contacts with electrical circuits and equipment, 75 were caused by direct or indirect contact with unguarded trolley wire in coal mines. The law relating to guarding trolley wires in the mines of this particular State, as amended in 1935, reads in part as follows: "All trolley wires carrying 220 volts or more, and less than six feet six inches above top of rail, must be guarded at all points under which men and animals are required to pass***,'" The natural conclusion to be drawn from such records is that lack' of guards or shields must be held responsible for these fatalities. As a preventive measure, it has been advocated that every foot of trolley wire in mines should be guarded. Although some such drastic steps may appear to be amply justified, closer examination of the records nor this and other coal-mining States shows that absence of guards is not entirely responsible; but rather that other factors, such as carelessness and neglect it the observance of certain well-established simple rules concerning installation and location of trolley wires, also are responsible. In other words, if trolley wire is installed carelessly and its maintenance is neglected, it should not be expected that the mere installation of guards will overcome such carelessness and neglect. This publication discusses Various types of guards that have been used in Coal and metal mines of this country, together with related steps bearing upon the problem of 'preventing shock and fatalities from contacts with trolley wire. The material herein contained is taken largely from Information Circular 6577,4/ now out of print, and has been revised to include some types of guards that have been used in metal mines, together with a discussion of guard materials not covered in that publication.

Jan 1, 1945