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By D. W. Gillmore, C. C. Wright

DEWATERING is a major problem in the preparation and utilization of fine-sized coals now being recovered in increasing amounts from colliery effluents, refuse banks, and silt ponds. Of the various methods which have, been proposed for dewatering fine coal, gravity drainage is probably the oldest and most widely used, and yet little information on this subject has been published. Consequently a laboratory investigation of gravity drainage phenomena was undertaken not only to provide basic data for predicting the drainage behavior of fine coals in cars, bunkers, basins, and silos, but also to obtain some understanding of the moisture retention properties of fine coal. Because of practical interest in the problem, a reproducible laboratory technique, which simulated plant conditions as closely as possible, was developed for the evaluation of drainage variables. The ap- paratus selected consisted of vertically-mounted lucite columns, nominally 4 to 8 ft in length and 2, 3 or 6 in. in diam; the bottom of the column was provided with a rubber stopper through which was inserted a -in. diam drainage tube; a wad of glass wool was placed on the upper part of this outlet tube to retain the coal and a plug was temporarily located at the lower end to prevent drainage during charging of the column, see Fig. 1. The most satisfactory testing procedure is as follows: 1—The fine coal, which has been thoroughly

Jan 1, 1953

By AIME AIME

TRAINED as a mining engineer and with no little experience in the field of mining, his interests and activities later transferred to the alloying, fabrication, and physical metallurgy of nonferrous metals, principally silver, Robert H. Leach represents in his professional life both of the major phases of the fraternity of mining and metallurgical engineers. In his personal characteristics, his wide circle of true friendships, his kindly, sympathetic interest in the problems of his fellow engineers, be they the junior men of the mineral industries or the mature and experienced men, he typifies the characteristics and attitude so desirable in the professional man.

Jan 1, 1939

By J. T. Burwell

The crystal orientation in silicon iron that has been given a particular treatment described by Goss,l has been studied by Goss, by Bozorth2 and by Sixtus,3 but their results do not agree and are almost entirely qualitative. The following pages give a description of the orientation of the crystals in the material as determined by means of X-rays and expressed graphically in a pole figure. The treatment consists of hot-rolling the material into strip and then giving it two cycles of cold reduction followed by recrystallization. This produces remarkably good properties in the rolling direction, the product having a maximum permeability in this direction of more than 25,000 and a permeability at 16,000 Gauss of more than 2200. It is now generally agreed that Goss's original conclusion1 that the crystals in the final product are randomly oriented was incorrect, since Bozorth2 and Sixtus,3 using different methods, have shown that there is a decided preference in orientation. Those writers, however, expressed their results only in terms of one or more ideal orientations with deviations therefrom. X-ray Data A strip of the material containing 3.1 per cent Si, prepared by Goss,† 1.2 by 0.0125 in., was etched rapidly in warm dilute hydrochloric acid until it was 0.005 in. thick, in order to eliminate the effect of the two surface layers. The specimen was then mounted in an integrating camera similar to one described in the literature.4 The purpose of this camera is to translate the specimen during exposure, so that a statistically large number of grains contribute to the pattern photographed. The camera also allows the plane of the specimen to make various angles with the X-ray beam. An area 5 by 1.2 in. was scanned by a beam of unfiltered radiation from a molybdenum target tube operating at 37 kv., and the measurements were made principally on the peak of the white radiation. X-ray photographs were taken at intervals of 15" in a plane

Jan 1, 1940

By W. E. Keck, Paul Jasberg

The flotative properties of the principal minerals in Michigan's potential iron ores have been investigated to develop methods of bene-ficiation for the ores. One of these minerals, magnetite, is of considerable importance as a source of iron. Study of its flotation was similar to that of hematite1, another iron mineral in these potential ores. The present research consisted essentially of: (1) a survey of the literature on magnetite flotation, (2) the preparation of pure magnetite, (3) the development of laboratory procedure and (4) flotation experimentation. Literature on Magnetite Flotation.—For the purpose of this discussion, the results of previous work on the flotation of magnetite can be summarized as follows. The mineral has been floated with pine oil2, and it has also been separated from synthetic mixtures with silicates by the use of the same reagent2. Magnetite and apatite in iron-ore slimes have been separated by flotation of apatite with sodium palmitate3. These data were utilized in the present investigation. Preparation of Magnetite.—The pure mineral was prepared from the magnetic-separator concentrate of an iron ore (obtained from the Wither-bee Sherman Corporation, Port Henry, N. Y.). This concentrate was slowly comminuted with laboratory rolls and pulverizer to pass 65-mesh and was then tabled several times. Tabling yielded a relatively coarse magnetite concentrate, tailing and slimes. The two latter materials were rejected insofar as the present work is concerned, and treatment of the magnetite (table concentrate) was continued by separating it into — 65 + 200 and — 200-mesh sizes. Separation of the sizes was made by first dry screening and then wet screening. The —200-mesh material was rejected to eliminate possible introduction of error into flotation

Jan 1, 1939

By R. E. Head

Under existing economic conditions, the treatment of gold ores occupies an outstanding position in metallurgical activity. The increased price of gold has automatically brought about a reclassification of old dumps and low-grade orebodies, and many that formerly were considered valueless are now being vigorously investigated and worked. This situation has developed problems that have taxed the ingenuity and ability of metallurgists to the utmost. Some gold ores give a high extraction of gold by standardized methods of treatment; other ores of apparently similar character yield but a relatively small percentage of their gold when treated by the same processes. Surface Contamination The experience gained by microscopic study of numerous gold ores and tailings has shown that there are pronounced differences in the physical characteristics of the minerals composing them, more especially of the gold. Repeated studies of tailings from flotation and cyanidation of gold ores has established the fact that surface contaminations on gold particles are often directly responsible for high gold losses; comparison of gold particles isolated from flotation concentrates and the resulting tailings have showed that the clean gold has been recovered and the tarnished or contaminated gold invariably lost in the tailing. Obviously, it is not possible to make such a comparison of gold ores treated by cyanidation, as the clean gold has been taken into solution; but when the gold found in cyanide tailing has a tarnished or coated surface, one may infer, with a reasonable degree of certainty, that the clean gold has been extracted. This premise is supported by experimental evidence obtained by isolating particles of tarnished gold and exposing them to cyanide solution in small parting cups. In one such experiment, tarnished gold particles picked from a cyanide tailing showed but slight evidence 01 dissolving at the end of 27 days. In this test, a cyanide solution of 1.6 11). per ton was used and the leach solution was decanted arid renewed every

Jan 1, 1939

By Fred D. DeVaney and

The coercimeter, as its name implies, is an instrument for measuring the coercive forcet of magnetic substances. It was developed by Davis and Hartenheim in the Special Studies Section, Metallurgical Division. A detailed description of this apparatus may be found elsewhere.2 The coercive force determinations of magnetic materials are interesting because of the relationship established by Gottschalk,4 who showed a linear relationship between the magnetization coercive force and the specific surface of comminuted particles. The value of this relationship in determining grinding efficiency has been shown by Dean.3 The determination of the surface contained in the subsieve sizes has always been a difficult problem for investigators. They made approximate measurements of the surface of coarse materials by sizing on screens, but for the determination of the surface of the sub-sieve sizes it was necessary to make detailed grain counts or elutriation tests, or to study dissolution rates. The technical literature contains many references to other methods for determining these surfaces, either by some special apparatus or by mathematical calculations based on distribution lines. Many of the methods are long and tedious, and the results of some, at least, are questionable. he turbidimeter gives quick results on ground cement. By using magnetite as the material to be ground, a simple determination of its coercive force by the coercimeter, requiring 10 minutes or less, can be transposed directly and accurately into units of relative surface. This subject has been pursued further by the U. S. Bureau of Mines in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Mo., and the following is a description of the results.

Jan 1, 1939

By James Douglas

The development of the copper-resources of this country has kept close pace with the unfolding of its geographical area to commerce. In colonial days, when our English ancestors occupied only the Atlantic seaboard, insignificant quantities of copper were mined in Connecticut, New Jersey, and Pennsylvania, and the ore was shipped for treatment to England. The first steam pumping-equipment

Jan 1, 1891

By V. R. Garfias

INTRODUCTION FOR a number of years the senior author has been interested in the various geologic and engineering problems involved in the development of the petroliferous districts of northeastern Mexico, having in a previous paper 1 endeavored to present a summarized statement of the information relating to the geology and soil resources of this region. Of the many interesting geologic phenomena, perhaps those which have been the object of more speculation relate to the igneous intrusions which, in places, have a controlling influence on the accumulation of oil in commercial quantities, a relationship which has been tentatively explained by various observers with as many interestingly different views. The authors of the present paper aim to record, in the course of a general discussion of the various viewpoints, some additional data, and present further tentative conclusions with a view to rounding out an up-to-date summary of the subject. The greater part of the area in question lies in the State of Vera Cruz, only a northwest fraction being in the State of San Luis Potosi. Vera Cruz is bounded on the north by the State of Tamaulipas, the northernmost of the Mexican States along the Gulf. The topography of the States of Tamaulipas and Vera Cruz and of Texas and Louisiana to the north, is controlled by the Gulf coastal plain which in northern Vera Cruz has an average width of about 60 miles, the transitional topography between that of the rugged flanks of the Sierra and the lowlands of the coast being made up of a series of terraces and irregular hills and valleys.

Jan 8, 1917

By William Glenn

In their account of chromium, Roscoe and Schorlemmer (Treatise on Chemistry, London, 1879) state that "In 1762 Lehmann, in a letter to Buffon, de nova minerœ plumbi specie crystalline rubra, described a new mineral from Siberia, now termed crocoisite." In 1786 Lehmann analyzed it (Nicholson's Jour., Dee., 1798) and found that it contained chiefly lead, and that the " mineralizers " were arsenic and sulphur. It was next examined in 1189 by Macquart and Vauquelin, who stated that it contained an intimate mixture of iron, alumina, and lead peroxide. The account of their work was published over the name of Macquart. Vauquelin (Louis-Nicolas) was a Norman peasant, who had studied in the village school, and at the age of fourteen was a laboratory-boy in a pharmacy at Rouen. Later, he found his way to Paris, and in 1789 was assistant to Fourcroy, a pharmacist and a teacher of note. It was here that he met Macquart, with whom he did the work on Siberian red lead, and at this time his friend Cheradame taught him his Latin.

Jan 1, 1896

By Fred D. DeVaney and

The coercimeter, as its name implies, is an instrument for measuring the coercive forcet of magnetic substances. It was developed by Davis and Hartenheim in the Special Studies Section, Metallurgical Division. A detailed description of this apparatus may be found elsewhere.2 The coercive force determinations of magnetic materials are interesting because of the relationship established by Gottschalk,4 who showed a linear relationship between the magnetization coercive force and the specific surface of comminuted particles. The value of this relationship in determining grinding efficiency has been shown by Dean.3 The determination of the surface contained in the subsieve sizes has always been a difficult problem for investigators. They made approximate measurements of the surface of coarse materials by sizing on screens, but for the determination of the surface of the sub-sieve sizes it was necessary to make detailed grain counts or elutriation tests, or to study dissolution rates. The technical literature contains many references to other methods for determining these surfaces, either by some special apparatus or by mathematical calculations based on distribution lines. Many of the methods are long and tedious, and the results of some, at least, are questionable. he turbidimeter gives quick results on ground cement. By using magnetite as the material to be ground, a simple determination of its coercive force by the coercimeter, requiring 10 minutes or less, can be transposed directly and accurately into units of relative surface. This subject has been pursued further by the U. S. Bureau of Mines in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Mo., and the following is a description of the results.

Jan 1, 1939

By J. T. Burwell

The crystal orientation in silicon iron that has been given a particular treatment described by Goss,l has been studied by Goss, by Bozorth2 and by Sixtus,3 but their results do not agree and are almost entirely qualitative. The following pages give a description of the orientation of the crystals in the material as determined by means of X-rays and expressed graphically in a pole figure. The treatment consists of hot-rolling the material into strip and then giving it two cycles of cold reduction followed by recrystallization. This produces remarkably good properties in the rolling direction, the product having a maximum permeability in this direction of more than 25,000 and a permeability at 16,000 Gauss of more than 2200. It is now generally agreed that Goss's original conclusion1 that the crystals in the final product are randomly oriented was incorrect, since Bozorth2 and Sixtus,3 using different methods, have shown that there is a decided preference in orientation. Those writers, however, expressed their results only in terms of one or more ideal orientations with deviations therefrom. X-ray Data A strip of the material containing 3.1 per cent Si, prepared by Goss,† 1.2 by 0.0125 in., was etched rapidly in warm dilute hydrochloric acid until it was 0.005 in. thick, in order to eliminate the effect of the two surface layers. The specimen was then mounted in an integrating camera similar to one described in the literature.4 The purpose of this camera is to translate the specimen during exposure, so that a statistically large number of grains contribute to the pattern photographed. The camera also allows the plane of the specimen to make various angles with the X-ray beam. An area 5 by 1.2 in. was scanned by a beam of unfiltered radiation from a molybdenum target tube operating at 37 kv., and the measurements were made principally on the peak of the white radiation. X-ray photographs were taken at intervals of 15" in a plane

Jan 1, 1940

By Raymond C. Johnson

GASIFICATION is important to the anthracite industry, as it is to the entire solid-fuel industry and to the nation. However, to the anthracite industry it may have particular significance in that it would increase the market value of many millions of tons of a by-product fuel, which the industry now has in storage and is currently producing, in addition to increasing the potential market for all its products. The by-product fuel is of usable quality but the ash content is higher than it can be in other products and therefore it must be converted or used at the point of production. Gasification is one method by which the product may be given increased value. The inherent characteristics of anthracite make it well suited for producing a fuel or synthesis gas. It is the most concentrated form of natural commercial carbon, noncaking and noncoking; it does not produce smoke, tar, or soot and has a low sulphur content; and the volatile matter, which ranges between 2 and 8 pct, is 80 to 85 pct hydrogen with small amounts of methane, carbon dioxide, carbon monoxide, and nitrogen. The ash fuses at high temperatures, which allows it to be burned at high rates without slagging. However, with the addition of small amounts of dolomite, the ash will form a slag, or glass, which is very fluid. Anthracite has long been used in the manufacture of city gas and it is extensively used in various parts of the country to make water gas to be converted to hydrogen. Buckwheat and rice anthracite are used in Galusha producers to make producer gas. Excellent synthesis gas has been made in a Galusha producer with rice and barley anthracite with oxygen in tests at the Consolidated Mining and Smelting Co., Trail, British Columbia. In these tests, anthracite was shown to have advantages over competitive fuels, in that the gas had a higher hydrogen content and could be cleaned with less difficulty. The anthracite seams are steeply pitching and in mining the parting strata and some of the roof and bottom materials are taken with the coal. In preparation, these materials are separated by gravity from the commercial product and stored in refuse banks. This refuse contains a mixture of rock, slate, or shale, and high-ash anthracite with bone coal, which is low-ash coal that is interspersed with thin bands of shale. The bone coal contains between 25 and 50 pct ash with an average ash content of approximately 30 pct, with a

Jan 1, 1953

By J. F. Emig

The Burns Harbor Plant was designed to produce and process large ingots into plate, hot rolled sheet, cold rolled sheet and tin plate. Rimmed ingots, in particular, are poured 96" to 106" high and weigh up to 85,000 lbs. During the latter part of 1970, a quality problem was encountered involving white line "sliver" defects on the surface of cold rolled, low carbon, rimmed steel sheet. Sheets containing these defects are not desirable for exposed automotive items because of the possibility of opening during forming or becoming more apparent after forming. Metallographic work located and identified two basic types of inclusions within the white line defects: (1) complex oxides consisting largely of iron and manganese oxides and (2) scale-type iron oxide. The presence of these oxides strongly suggested that the-white line defects were resulting from an unsound, unclean rim zone.

Jan 1, 1972

By W. E. Keck, Paul Jasberg

The flotative properties of the principal minerals in Michigan's potential iron ores have been investigated to develop methods of bene-ficiation for the ores. One of these minerals, magnetite, is of considerable importance as a source of iron. Study of its flotation was similar to that of hematite1, another iron mineral in these potential ores. The present research consisted essentially of: (1) a survey of the literature on magnetite flotation, (2) the preparation of pure magnetite, (3) the development of laboratory procedure and (4) flotation experimentation. Literature on Magnetite Flotation.—For the purpose of this discussion, the results of previous work on the flotation of magnetite can be summarized as follows. The mineral has been floated with pine oil2, and it has also been separated from synthetic mixtures with silicates by the use of the same reagent2. Magnetite and apatite in iron-ore slimes have been separated by flotation of apatite with sodium palmitate3. These data were utilized in the present investigation. Preparation of Magnetite.—The pure mineral was prepared from the magnetic-separator concentrate of an iron ore (obtained from the Wither-bee Sherman Corporation, Port Henry, N. Y.). This concentrate was slowly comminuted with laboratory rolls and pulverizer to pass 65-mesh and was then tabled several times. Tabling yielded a relatively coarse magnetite concentrate, tailing and slimes. The two latter materials were rejected insofar as the present work is concerned, and treatment of the magnetite (table concentrate) was continued by separating it into — 65 + 200 and — 200-mesh sizes. Separation of the sizes was made by first dry screening and then wet screening. The —200-mesh material was rejected to eliminate possible introduction of error into flotation

Jan 1, 1939

Jan 1, 1904

By C. M. Brown

Selection criteria for the instrumentation employed in semi-autogenous grinding circuits are reviewed. Instruments in use for grinding mill and related process equipment start- up, shutdown, protection, monitoring, control, and performance reporting functions are discussed with examples given of current industry practice. The quantity and type of instrumentation used vary from operation to operation, but today many semi- autogenous circuits are highly instrumentated, and employ automatic process control for both circuit stabilization and optimization of economic performance. Examples of analog and digital based control systems exist, and are described.

Jan 1, 1982

By F. V. Lenel, G. S. Ansell, E. C. Nelson

IRMANN'S' discovery that extrusions of fine alumi-num-flake powders possess remarkable high-temperature strengths has led to the production of a new class of engineering materials whose properties are derived from a fine dispersion of oxide particles in a metallic matrix. A fundamental study of such materials and elucidation of the mechanism whereby the oxide parti-

Jan 1, 1958

By A. C. Fieldner

THE older coal chemist had a much simpler conception of coal than we have today. To him coal was a mineral composed essentially of carbon, hydrogen, oxygen, nitrogen, sulfur, ash, and water, in various proportions. His studies on the constitution of coal were directed along the conventional lines of proximate and ultimate chemical analyses and making deductions from these data without any real appreciation of the fact that coal is a conglomerate of various chemical compounds, including many of the most complex structures known to organic chemistry. The view of the modern coal chemist is well expressed by Franz Fischer, I who says that while proximate and ultimate analyses are important both from the scientific and technical point of view, they tell the chemist no more concerning the number and kinds of chemical compounds that constitute coal than the reader would learn of the contents of a book if told that the printed contents consisted of 15 per cent. of the letter "e," 5 per cent. of the letter "n," 1 per cent. of the letter "g," 4 per cent. of the letter "b," etc. As the reader must have the grouping of letters into words and words into sentences, so the chemist must have the grouping of atoms into molecules and the proportion of each molecular compound in the coal aggregate before he acquires an adequate knowledge of the constitution of coal. Modern investigators2 are laying the foundation of a new chemistry of coal based on the biochemistry of plants and the chemical changes involved in processes of fermentation and decay. As

Jan 5, 1925

By Leonard Greenburg, William B. Harris, Gustäv Werner

HAULAGE in tunneling operations generally has been done with electric locomotives. As a rule, on short hauls the source of electricity is a storage battery mounted on the locomotive, which, of course, must be removed and recharged periodically. Where the distance from the recharging point to the tunnel face is very long, and where loads are heavy, trolley-driven locomotives are used. Diesel engines have been used in mining and tunneling operations in Europe for a number of years. The recent reports of studies in Belgium1 and by the Bureau of Mines in this country2-4 have indicated the potentialities of this form of power for haulage, mucking, bulldozing and many other underground operations. The hazards attending the use of Diesel engines in more or less closed spaces have long been known. The exhaust constituents that may create a harmful or objectionable environment are carbon monoxide, oxides of nitrogen and sulphur, carbon dioxide, aldehydes and smoke. Lack of precise information regarding the concentration of these gases and the ventilation requirements to reduce them to safe levels has to some extent suppressed their general acceptance in tunneling and mining work. Not until the work of the Bureau of Mines referred to above, and certain experience gained in the construction of the Delaware Aqueduct,‡ has there been available the requisite information regarding the conditions under which their use may be permitted. This paper concerns itself with the successful operation of Diesel engines underground in the construction of certain parts of the Delaware Aqueduct, and describes the conditions under which Diesel engines have been found to operate with a minimum production of noxious gases. The test data reported were obtained during the operation of Diesel engines over a period of two years.* STUDIES BY THE NEW YORK STATE DEPARTMENT OF LABOR Exhaustive tests were made by the Division of Industrial Hygiene, of the composition of the exhaust gases given off by a Diesel engine mounted on. a test block. These tests showed that certain quantities of the gases are discharged from the exhaust. On the basis of these figures, preliminary requirements of design and control

Jan 1, 1942

The American mining industry is vigorous today because it is young. At a time when the ore deposits of central Europe, for example, were being exploited actively, those of the United States were lying practically untouched. The founding fathers of our republic were not interested in mineral wealth because they were ignorant in such matters; their preoccupations were with defence against the Indians, the clearing of the forest, and the starting of agriculture in their new domains. They had no idea of establishing a mining industry. The Indians whom the American colonists dispossessed had no mines; they used only the metal that was to be found lying on the surface of the ground. Their arrows and spears were tipped with flint, which likewise called for little digging, if any. The native copper that glacial action had torn from the lodes of the Lake Superior region and had carried into the valleys of the Ohio and Mississippi was employed in the making of earrings, bracelets, knives, and scrapers. The same useful metal was found in many other places, in Virginia and Carolina, in Vermont and New Jersey, for example, but the Indians did not know how to melt it, much less how to smelt the ore, therefore they shaped it into tools and implements by hammering. Fortunately for them the hammering of the metal caused it to harden and therefore to become serviceable for implemental use. It is doubtful if they obtained the copper by actual mining, that is, by digging or excavating; it is true we find traces of such operations in the Keweenaw .peninsula of Michigan, but we have no

Jan 1, 1932