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HAVING previously described the metals to you, before I proceed any farther I do not wish to fail to tell you, as I promised to do in the first chapter on metals, what I have learned through experience concerning the semiminerals, although this may seem to you outside our proposed subject. Since these are not produced by Nature as all rock or all metal they are called semiminerals by speculative physicians. Many kinds of these are found; those that resemble rocks are earthy, very difficult to liquefy, and much more adapted for adorning paintings than for anything else. Those that liquefy with fire, like sulphur, antimony, marcasite, [22] calamine, zaffre, manganese, and others, resemble the metals almost like brothers. Some others are more watery so that they dissolve in water, although they are fairly dense, and are obtained and reduced to their, perfection by means of water. These are the salts, vitriol, rock alum, and saltpeter. To these, as a watery thing, belongs also quicksilver, as it is commonly called because of its motion. Although it appears. not only liquid, but very liquid, this is not at all similar in its effects to any of the above. Indeed, it retains its same being until its very form is consumed. Since the reasons for its effects are almost impossible to investigate, I do not intend to speak of them here or to enter now this maze of speculation, because I wish to make definitely clear to you what this quicksilver really is. Therefore, leaving aside opinions and disputes, I shall take only those of the said semiminerals that I know are useful. First we shall see the method by which the semiminerals can be found and then how they are to be extracted from their matrices. These, perhaps, have no less need of effort and industry than the metals since they are substances completely hidden in the rocks or in the earth. For this reason some of these that are sought are made use of by means of fusion after they have been mined from their mother mountains, and some others need to be disposed by a certain maturative corruption, now with moisture and coldness, now with dryness and heat, as with waters, rains, frosts, or long baking in the sun, with fire, or even with a strong reheating within themselves. Most of them can finally be brought to the desired end by means of solution with water and fire.

Jan 1, 1942

By R. K. McGeary, B. Lustman

Orientation relationships and rates of annealing of 97 pct cold rolled zirconium have been studied by X-ray techniques, metallography, and by hardness measurements. The process of annealing occurring by the formation of domains, and their subsequent growth without recrystallization, is demonstrated. NUMEROUS investigators1-' have revealed sub-grain formation after annealing cold worked metal single crystals and have generally described the results in terms of a dislocation mechanism of polygonization.5,6 in heavily cold rolled polycrystal-line aluminum the first stages of heating cause an apparently spontaneous subdivision of regions of the deformed matrix into a great number of slightly disoriented domains followed or accompanied by rapid growth of certain domains to form a recrystallization texture.7,8 In the present investigation the isothermal rate of annealing of cold worked polycrystalline zirconium has been studied by X-ray techniques, metallography, and by hardness measurement. It will be shown that, rather than by the usual nucleation and growth mechanism,"12 the process of annealing can best be explained by the formation of domains early in the annealing treatment and the subsequent growth of these domains without recrystallization. Experimental Procedure All the experimental work was performed on an arc-melted ingot of high purity zirconium crystal bar made by Westinghouse in a production scale deBoer unit. The weight percentage of impurities in the zirconium were as follows: C, 0.04; Fe, 0.05; Hf, 0.014; W, 0.01; Ti, Ni, and Al, 0.003; Si and N, 0.002; Cr and Cu, 0.001. Metallographically the zirconium showed only a single phase. The 4 in. diarn ingot was forged at 760°C to a 1 1/2x3 in. plate and was then rolled at 760°C to 0.150 in. thickness and annealed at this temperature for 20 min to produce an equiaxed grain structure of about 0.1 mm average grain diameter. The hot rolled plate was roller-leveled, surface ground to 0.135 in., cold rolled 83 pct reduction in thickness on a two-high mill, and then to a total reduction of 97 pct on a Sendzimir mill. The 0.004 in. strip material so produced received no subsequent mechanical treatment. Specimens % in. square were sheared from the rolled strip and isothermally annealed at 104 mm Hg in an all glass vacuum system equipped with a Vycor furnace tube. The temperature data presented are the average temperatures during the runs and did not vary more than about k3"C. X-ray Diffraction Methods: When zirconium is drastically cold rolled, a high degree of preferred orientation results in which prism poles, {1010}, are perpendicular to the rolling direction. After fully annealing this material an entirely new texture develops which corresponds to a 20" or 40" rotation of the deformation texture about hexagonal axes of

Jan 1, 1954

In the death of Major A. B. desaulles at South Bethlehem, Pa., on Dec. 24, 1917, the Institute lost a valued and esteemed member, one of the last few of those who, in May, 1871, at Wilkes-Barre, attended the first meeting of the Institute, in response to a call that had been issued by R. P. Rothwell, Eckley B. Coxe, and Martin Coryell. Major desaulles was born Jan. 8, 1840, at New Orleans, and was the son of Louis and Armidc Longer desaulles, each of French descent. As a boy he was privately tutored in the South, and then schooled in New England to enter the Rensselaer Polytechnic Institute, where he was graduated with honors in the class of '59. Following his graduation he studied in France and Germany for two years, returning to New Orleans in 1861 to enter the Confederate Army, in which he served with distinction as an engineer throughout the Civil War, rising to the rank of Major and the command of his Corps. After the close of the war he pursued his studies abroad for another year, returning to New York in April, 1866, when he became engineer for the New York & Schuylkill Coal Company, and remained at its plant near Wilkes-Barre until October, 1871, when it was sold to the Philadelphia & Reading Coal and Iron Company. He then returned to New York where for several years he was engaged in the practice of his profession. In 1869, he married Catharine M. Heckscher, daughter of Charles Heckscher of New York City. Mrs. desaulles survives him. In 1876, Major desaulles became superintendent of the Dunbar Furnace Company in Fayette County, Pa., with which company he remained until 1883. As a feature of the Pittsburgh meeting in May, 1879, Major and Mrs. desaulles entertained the members of the Institute at dinner at Dunbar on the occasion of the Institute's visit to Dun-bar furnace. In 1883, he took up the formation of the Oliphant Furnace Company in that county, of which he became and remained the head for five years. He was then called to the superintendency of the New Jersey Zinc Company at South Bethlehem, Pa., in which position he remained until his retirement,from active service in 1911, maintaining, however, hi.; keen interest in the metallurgy and smelting of zinc, in collaboration with his son Charles, a member of the Institute and a Director of the American Smelting and Refining Company. From 1888, until his death, he resided in South Bethlehem, a prominent and highly respected citizen of that progressive and stirring community. Major desaulles was a member of the Protestant Espicopal Church, and at the time of his death was a vestryman of the Church of the Nativity at South Bethlehem. He was president of the Men's Club of the Church of the Nativity. His kindly nature led him to take an active interest in the promotion of healthful sports among young men. He was ever active in all things pertaining to the general welfare and uplift of his fellowmen. In his death the profession has lost a distinguished engineer and mctallurgist and our country a patriotic able citi-zen and man of affairs—one greatly beloved by those whom he honored with his friendship, and respected and looked up to by all who were privileged to know him.

Jan 1, 1920

By C. P. Sandberg

INTRODUCTION. NOTWITHSTANDING the growing importance of this subject, no work specially devoted to it has hitherto been published. Having had to inspect during the last twenty years nearly a million tons of iron and steel rails for various countries, I have obtained experience of what rail manufacturers can practically execute, as well as of what railway engineers practically require. Bearing these two points in mind, I have from time to time published observations with a view to unite both interests, -that of the producer and that of the consumer,-and to reduce the specifications and the forms of sections to standards, or types, in order to facilitate the execution of the works and to improve the construction of permanent way. The Swedish government railways, as well as private companies owning railways in Sweden, Norway, and Denmark, have during the time above mentioned consulted with me and intrusted to me their rail inspection. I therefore owe to these countries much of the opportunity which I have enjoyed of gaining experience and position. Next to Sweden, America is the country which has most liberally favored me with its confidence in placing these matters in my hands. Through circumstances not under my control there has been little exportation to, and less work done by Europe for, America during the last six years ; but the recent revival of the rail trade has been the more gratifying to me, seeing that almost all the importers of American rails are still specifying for the Sandberg rail sections and inspection. It is therefore with .feelings of gratitude that I now beg to lay before the American Institute of Mining Engineers, and I hope, through that body, before the American railway world, the results of some experience which I have gained in the execution of work for their country, and which therefore belongs rightfully to

Jan 1, 1881

By David L. Holt, Walter A. Backofen, Anwar-ul Karirn

ANNEALING the binary alloy, Mg-0.5 wt pct Zr in a hydrogen atmosphere results in extensive precipitation of zirconium hydride. The morphology of these precipitates has already been investigated.lm3 Squires, Weiner, and phillips4 found, following creep testing of the hydrided alloy at 450" and 500°C, that hydride denuded zones formed along grain boundaries that were aligned approximately normal to the tensile axis. Zone formation was attributed to diffusional creep by magnesium transport down the prevailing stress gradients.4'5 Recently, electron microprobe analysis by Karim, Holt, and Backofen6 showed the zones indeed to be zirconium-free and furthermore it was shown that in compression, zones formed along boundaries approximately parallel to the stress axis. Thus it was confirmed that the zones are formed by diffusional creep. Typical zone-formation is shown in Fig. 1. Karim, Holt, and Backofen also measured the con- tribution to the total strain, from diffusional flow, slip creep, and grain boundary shear: results showed that diffusional strain tends to saturate with increasing imposed strain, while grain boundary shear eventually becomes the dominant deformation mode. It was suggested in explanation that the precipitate-denuded zones are soft and easily sheared, such deformation contributing to the grain boundary shear measurement. A point to be emphasized is that the Mg-0.5 Zr alloy was not superplastic for the index of strain rate sensitivity of flow stress, m = a log log 6 was only 0.25. It was recognized that diffusional creep in a poly crystalline aggregate must be accompanied by boundary shearing.' The suggestion was that the non Newtonian-viscous character of diffusional creep in the Mg-0.5 wt pct Zr alloy is due to resistance to sliding of boundaries lying approximately parallel to the tensile axis.= The work described in the present note should be seen against the above background for it represents initial efforts to observe in a similar way diffusional creep in a superplastic alloy. Previous work with the ternary-alloy Mg-6 Zn-0.5 Zr, pellet extruded, showed it to be superplastic however it does not contain resolvable precipitates to act as internal markers for diffusional creep. Also the fine grain size of the alloy (0.5 p) made conventional metallography rather difficult. Solubility relationships in the Mg-Zn-Zr system are not well known, however making reasonable guesses about the probable phase diagram of the ternary, Mg-Zn-Zr, various heat treatments were attempted to produce hydride precipitation. Finally a 16-hr anneal at 495' in hydrogen was found to pro-

Jan 1, 1970

By G. F. Loughlin

Nearly 55 years have elapsed since the U. S. Geological Survey was organized. During this period the mineral industries have grown from infancy or early childhood to well developed maturity, and some mining industries appear to be declining. Decline in mining is even more conspicuous in certain districts, or even states, than in any mining industry as a whole, and discoveries or developments of important new districts have been very few in recent years. Our reserves of most metals and nonmetals are adequate for many years of normal production, subject to changes in rate of exploitation that may be caused by foreign competition and by changes in technology and market conditions; but the declining production of many districts and the scarcity of important new discoveries to compensate for them is cause for some apprehension. It is likely that future production will depend to a considerable extent on deep exploration and on the thorough examination of places in and adjoining existing districts where significant outcrops are lacking and only apparently insignificant geologic features offer encouraging clues—more so than on the discovery of entirely new districts. Even the possible discovery of new districts, which have escaped the intensive search by the nontechnical prospector, must be dependent on geologic information. There is therefore no need for argument as to the value of geology to the mining industry; and the need of continuing to advance the science. The U. S. Geological Survey's past contributions to mining geology, as expressed in its official reports and other publications, are recognized by Ransome in his historical review of mining geology in the Lindgren volume.' These contributions have helped to form the basis of modern mining geology, which has grown rapidly in the last 25 years. This growth has witnessed the organization and maintenance of geologic staffs by mining companies in several districts, and their detailed work, together with the fact that nearly all of the larger mining districts have

Jan 1, 1935

By Ellis Clark

THE greater portion of the brown ore in the vicinity of Easton, along the north slope of the Lehigh Mountain or Durham range of hills, is obtained from mines instead of from open cuts or quarries, as is the case in the ore-beds in the western part of Northampton County, in Lehigh County, and in Berks County. The reasons for this method of procedure are various, and the principal causes of the shaft and regular mine system of working being adopted instead of the open air cuts, are : First, the large amount of stripping that would be necessary, as the richer and more valuable portions of the ore do not appear to be found as near the surface as those in other portions of the Kittatinny valley; second, the occurrence of the ore in regular beds, interstratified with the clay, and, to a less extent, in pockets or erratic deposits, as is the case in the mines of Lehigh County; and third, on account of many of the mines being situated at the immediate base of the Lehigh Mountain, where the surface water would be in such large quantities as to be with difficulty handled, and where the subsequent caving in of the sides of the open cut would be almost certain to expose the gneiss rock, which is water-bearing, the large quantities of water coming from which would probably drown out the ore-bed. Shafts, and a regular system of gangways and mining are therefore required by the configuration of the surface, the depth of the deposits and their geological structure. The ordinary size of the shafts is about four feet square, but where an extensive plant of pumping machinery is required the size may be increased to eight feet by six, with two compartments for the hoisting and pump-shaft respectively. A man-way, consisting of ladders with rests at intervals of twenty or thirty feet, is comprised in the pump-shaft, the wire rope being used for purposes of ascent and descent only in exceptional cases, on account of accidents which

Jan 1, 1879

By R. L. Rickett, W. C. Leslie

The influence of deoxidation practice, prior thermal history, and aging time and temperature on the strain-aging behavior of low-carbon open-hearth steels was investigated. The criterion of aging employed was the increase in yield strength in the tensile test, after straining and aging. Composition, prior heat treatment, and aging conditions were all found to be important in governing the strain-aging characteristics of these steels. THAT deoxidation changes the strain-aging propensities of low-carbon steels has been known for a long time, but there has been little agreement, and even contradiction, between results obtained by different investigators and between results obtained in the laboratory and in the mill. This investigation was begun in the hope that some of the uncertainties connected with the strain aging of commercial steels could be eliminated. In considering this problem, it was necessary to define strain aging and to examine the methods used to measure this property. Strain aging can be defined as the changes in properties of a metal or alloy with time, after cold working. The rate at which these changes occur increases as the temperature is raised above atmospheric. The requisite plastic strain is the principal distinction between strain aging and quench aging, the latter being due to precipitation from supersaturated solid solution. Strain aging is also characterized by rapid attainment of maximum hardness at high aging temperatures and lack of softening (overaging) at low aging temperatures. Several possible criteria of strain aging have been listed by Sachsl and by Davenport and Bain.' Because changes in mechanical properties are the most easily measured and the most commonly used, consideration of methods to be used in this investigation was confined to three tests: tensile, notch-impact, and hardness. Hardness tests are the most economical and easiest to perform, but produce only one measure of strain aging. Also, as pointed out by Felmly, Hartbower, and Pellini,³ hardness changes due to aging are not pronounced for steels containing more than 0.15 pct C. Notch-impact tests require careful preparation of large numbers of specimens. Above and below the transition temperature the test lacks sensitivity; furthermore, it is extremely difficult to impart a uniform strain to the specimens, followed quickly by aging and final testing; machining must generally take place after straining. For these reasons, the tensile test was selected for use. Although this test requires a considerable expenditure of time, labor, and money in preparation of the specimens and performance of the test, more information can be gained than from any other single mechanical test, information which includes upper and lower yield points, yield-point elongation, tensile strength, strain-hardening exponent, reduction of area, and elongation. Low and Gensamer' and Schwartzbart and Low5 lso used the tensile test, taking the increase in flow stress after straining in tension and aging as a measure of strain aging. In our work, as in theirs, each specimen was strained an arbitrary amount, sufficient to pass through the

Jan 1, 1954

James Douglas will long be remembered as a distinguished mining engineer and metallurgist, as a scientist with broad vision, as an executive whose understanding of practical problems coupled with his knowledge of men and affairs enabled him to weld together great mining interests and to their service build railroads and bring power. More, he will be recalled as a philosopher and a writer of charm, a historian of no mean order, and one whose catholic tastes and enthusiasms led him into the fields of education, medicine and theology. His aim was to possess that which he considered made life worth while—friends and effectiveness in whatever task he undertook. In this aim he was successful to a degree exceeded by few, as thousands of his friends and associates could and can testify. Dr. Douglas was born on November 4,1837, at Quebec, Canada. His father, James Douglas, Sr., was a prominent physician and the leading surgeon of Canada. He also established the first retreat for the insane in the Dominion, the Quebec Lunatic Asylum, to which he devoted his services for years; The son followed in the footsteps of his father and studied medicine, not only in Canada but also in Scotland and in Germany. He entered the University of Edinburgh in 1855 but after two years at that institution returned to Canada and was graduated from Queens university at Kingston, Ontario, .with the degree of Bachelor of Arts. Later he went to Lava1 University, Quebec, and subsequently became professor of chemistry at Morrin College, Quebec. After he was graduated—at the time he considered his formal education completed—he traveled with his father in Europe and in the Orient; visiting Egypt, being especially interested in that country, several times. They gathered together an important archaeological collection which later was donated by them to the Metropolitan Museum of Art in the city of New York. James Douglas was also greatly interested in photography, a hobby in which he made use of his chemical knowledge. The writer can remember distinctly the descriptions he gave more than forty years ago in Arizona of the difficulties he encountered with the old wet photographic plates, especially while traveling in Egypt, when he prepared and used his own chemicals. In his humorous manner he told how he once discovered, in the nick of time, the nurse preparing to give the baby in the party a rub-down, using for that purpose the white, limpid

Jan 1, 1934

By Claude H. P. Lupis, John F. Elliott

The classic Siez~erts' technique has been employed to determine the solubility of oxygen in liquid pure silver and the effect on the oxygen solubility of solute metal additions to liquid silver. The results indicate that oxygen deviates slightly from Sieverts' law in pure silver as = 3.9. Gold, platinum, md palladium decrease the solubility of oxygen in silver. First-order free energy, enthalpy, md entropy interaction coefficients are determined from the data. An important aspect in the establishment of the formalisms to be applied to represent the thermody-namic behavior of components of solutions is the accuracy of the experimentally determined thermody-namic properties. Wagner developed the first-order free energy interaction coefficient.' Recent papers2'3 extend the treatment formally to other thermodynamic properties and define the second- and higher-order interaction coefficients. A current communication4 considers in some depth the requirements and limitations imposed because of experimental error on the use of several formalisms now under active consideration in the field. This communication reports the results of an experimental study of the behavior of oxygen in liquid silver alloys that was carried out concurrently with the development of Refs. 2 and 3 with the hope of providing sufficiently precise information so that enthalpy and entropy interaction coefficients could be determined. THE EXPERIMENTS The Sieverts technique was employed using an improved design of the reaction bulb over that developed originally by Humbert5 and subsequently improved by pehlke6 and Weinstein.7 The Vycor reaction bulb as shown in Fig. 1 was air-cooled and contained a port for the thermocouple angling off to one side and a vertical port for connections to the gas supply and

Jan 1, 1969

By C. P. Sandberg

Notwithstanding the growing importance of this subject, no work specially devoted to it has hitherto been published. Having had to inspect during the last twenty years nearly a million tons of iron and steel rails for various countries, I have obtained experience of what rail manufacturers can practically execute, as well as of what railway engineers practically require. Bearing these two points in mind, I have from time to time published observations with a view to unite both interests,—that of the producer and that of the consumer,—and to reduce the specifications and the forms of sections to standards, or types, in order to facilitate the execution of the works and to improve the construction of permanent way. The Swedish government railways, as well as private companies owning railways in Sweden, Norway, and Denmark,.have during the time above mentioned consulted with me and intrusted to me their rail inspection. I therefore owe to these countries much of the opportunity which I have enjoyed of gaining experience and position. Next to Sweden, America is the country which has most liberally favored me with its confidence in placing these matters in my hands. Through circumstances not under my control there has been little exportation to, and less work done by Europe for, America during the last six years; but the recent revival of the rail trade has been the more gratifying to mo, seeing that almost all the importers of American rails are still specifying for the Sandberg rail sections and inspection. It is therefore with feelings of gratitude that I now beg to lay before the American Institute of Mining Engineers, and I hope, through that body, before the American railway world, the results of some experience which I have gained in the execution of work for their country, and which therefore belongs rightfully to

Jan 1, 1881

Jan 1, 1968

By Geo. H. Eldridge

This sketch of the Florence oil-field, presented to the Institute by permission of the Director of the U. S. Geological Survey, is accompanied with a map, Fig. 1, the topography of which has been taken from a field-manuscript of the Survey. The scale of the map and

Jan 1, 1892

By Harry L. Washburn, Robert L. Llewellyn, W. J. Halvorsen

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment. JUSTIFICATION FOR COAL PREPARATION During the past decade, major changes have occurred affecting the market, profit, and long-range planning of the coal industry. Mining companies have become "partners" with consumers at many new and some old mines, both for steam and metallurgical coals. Coal properties have become "assigned" tonnages at mutually agreed upon conditions and prices. Lower unit-train tariffs have been instrumental in helping coal markets to compete against oil and nuclear energy. Coal prices for power plants are still on a Btu (British thermal unit)

Jan 1, 1981

By R. T. Pepper

DURING an investigation into the effect of heat-treatment on the creep properties of the magnesium alloy ZW1, (1 pct Zn, 0.6 pct Zr), the previously published methods of final polishing were found to be unsatisfactory. A new diamond-polishing technique has been developed to facilitate the study of fine precipitates in this and other magnesium alloys, and is described in this note. The sectioning and coarse grinding techniques are those of Fox and Hall,' and Hess and Cieorge.' Pre- liminary mechanical polishing is done with 6-µ, and 1-µ( grades of diamond compound on 'Microcloth' using a lubricant of 'Hyprez' oil. When the conventional technique is used with a 1/4- µ diamond wheel for the final polishing of magnesium alloys, scratching is likely to result from the abrasive action of the 'Microcloth' nap on the soft metal surface. This problem has been overcome by the use of a cream on the wheel in order to separate the specimen surface from the polishing cloth. To prepare this cream, a solution of 6-ml tri-ethanolamine in 75-ml water is stirred into 12.5 g stearic acid at a constant temperature of 80° to 90°C. The cream is allowed to cool, and is then 'whipped' to a smooth consistency with 100-ml 'Hyprez' oil. Before polishing, the diamond loaded 'Microcloth' is moistened with a few drops of 'Hyprez' oil, then a small amount of cream is worked into the nap. For the best results a wheel speed of 500 rpm should be used for polishing, and the specimen should be held by hand with a light pressure while being rotated in the opposite direction to the wheel. After polishing it is necessary to swab the specimen thoroughly in methylated spirits to remove residual cream and oil from the surface in order to avoid uneven etching and drying stains. Fig. 1 shows the surface finish obtained on a specimen by polishing on a 1/4- ° diamond wheel using the cream, and Figs. 2 and 3 the precipitate observed in ZW1 after polishing, and etching for two seconds in nitric acid 15 pct in ethylene glycol. This new diamond-polishing technique has made a valuable contribution to the programme of metal-lographic research on ZW1 and has become a routine laboratory practice for other low alloy content magnesium alloys.

Jan 1, 1961

By Harry L. Washburn, Robert L. Llewellyn, W. J. Halvorsen

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment. JUSTIFICATION FOR COAL PREPARATION During the past decade, major changes have occurred affecting the market, profit, and long-range planning of the coal industry. Mining companies have become "partners" with consumers at many new and some old mines, both for steam and metallurgical coals. Coal properties have become "assigned" tonnages at mutually agreed upon conditions and prices. Lower unit-train tariffs have been instrumental in helping coal markets to compete against oil and nuclear energy. Coal prices for power plants are still on a Btu (British thermal unit)

Jan 1, 1981

By M. R. Geer, H. F. Yancey

Although the use of dense suspensions for coal cleaning was pioneered in the United States with the Chance sand flotation process, and during the past year a pilot plant using a magnetite suspension has started operation in this country, the more recent developments in this field of coal cleaning have occurred principally in the Netherlands. During the thirties the Dutch developed the Barvoys process, in which a medium of barite and clay is employed, the Tromp process, which utilizes a magnetite suspension, and the Loess process, in which is used the air-borne earth or soil known as loess.1-3 All these processes are finding increasing use in European coal-cleaning practice. Now a fourth process, the cyclone cleaner, is under development by the Netherlands State Mines. A cyclone thickener for reclaiming and thickening the dense suspension is a novel feature of the Loess process. Through accident, the discovery was made that the cyclone could be utilized as a cleaning device for fine coal. When the cyclone thickener at the Maurits mine plugged, the overflow was found filled with clean coal free of refuse, and from this observation developed the concept of the cyclone as a coal cleaner. In June 1945 the cyclone cleaner was observed by one of the authors,' and in September 1945 it was described by Dries-sen6 in a paper presented in London before the Institute of Fuel. As the cyclone seemed to offer unusual promise as a means of extending heavy-medium cleaning to the finer sizes of coal that cannot readily be treated in existing heavy-medium processes, the Bureau of Mines, following Driessen's, presentation, launched an investigation of the cyclone as a coal cleaner. Added impetus was given to this study by the present increased interest in heavy-medium cleaning in this country. Object and Scope of Investigation Driessen's report, although comprehensive in many respects, did not include a detailed description of the cyclone cleaner, and contained almost no information on the influence of the various operating variables of the cyclone. It was necessary, therefore, to investigate the influence of the cyclone adjustments on its performance before studying the application of the cyclone to various coal-washing problems. The present report is confined entirely to these preliminary tests, designed to demonstrate the operating characteristics of the cyclone. The investigation has been in progress

Jan 1, 1949

By Edward S. Cook

For several years past, dating particularly from the days of serious "ore-dirt" complications at the Warwick furnace, I have been desirous of providing some safe, quick and easy method of relieving the tuyeres of slag, when the cinder- and iron-notches are chilled through loss of heat in the clucible or when, from dropping or jumping of stock, the molten slag is forcibly driven into the bellyand leg-pipes. Various methods were proposed, but objections of one kind or another always presented themselves, and the subject was postponed to a more convenient season. In the summer of 1887, while running on anthracite alone, 1 found the various expedients in use to be so utterly valueless, that the importance of a practicable tuyere slagging-valve impressed me more forcibly than ever. The holes left in the cast-iron jacket at one side of the bottom of the water-blocks were found to be of no value whatever. The swinging or hinged cap on the elbow of the belly-pipe, while convenient to permit the removal of lag after the belly-pipe was partially or wholly filled, could not be adapted to discharge the slag before solidifying, except at great risk to the men and loss of time just when the constant running of the engine and the keeping of blast on the furnace was of the utmost importance. By removing keys from the caps and holding them in place with props, the slag could be discharged through the tuyeres and belly-pipes, with the engine running, by knocking the props away at a given signal. This method is extremely hazardous to life and limb, and I have always hesitated to make use of it. When the furnace is in such condition as to require the adoption of some method of the kind, the stoppage of the engine, cooling the blast and the contents of the crucible, always aggravates the trouble. When the caps are blown open and the slag is discharged by removal of the props, it is necessary to stop the engine to replace them. An hour or more will elapse before this can be done, as the slag must be partly removed before the tuyeres can be approached by ordinary mortals, and the caps handled and fastened in place again. Any movement of the stock is liable to burn the workman, as he stands, securing the cap in front or at one side of the open belly-pipe.

Jan 1, 1889

By W. L. Freyberger, R. B. Booth

Froth flotation is a chemically induced method for beneficiating or up- grading an ore, which utilizes a layer or column of froth as a separating medium to segregate and remove the valuable minerals from the worthless gangue components of a finely ground ore suspended in water. The object of this chapter is to discuss the theoretical aspects of froth formation, the various frothing agents employed in flotation, and the effect of chemical structure on froth formation, and to correlate these factors with flotation technology. The flotation method of separation is conducted in three main steps: 1) selective chemical modification of the surface of specific mineral particles to effect floatability or nonfloatability; 2) contact between air bubbles and mineral particles, the selective adherence of floatable minerals to these bubbles, and the rejection of nonfloatable minerals; and 3) separation of the floatable minerals from the nonfloatable minerals. As indicated above, these three operations are achieved by the use of chemicals. Frothers play their most important role in the second and third steps by influencing particle- bubble contact and by affecting the degree of separation obtained in the froth column. Frothers, as defined by flotation operators, are compounds that are used specifically for the purpose of creating a froth in a flotation separation. How- ever, some collectors produce froths that are adequate for some flotation operations. Although this chapter is chiefly concerned with the specific frothers used in flotation, some discussion of frothing collectors is included. Otherwise, collectors (or promoters) and modifiersare not discussed at length; for information on these types of flotation chemicals, the reader is referred to other sections of this book or to other sources.l HISTORICAL DEVELOPMENT OF FROTHING AGENTS Historically, there are two distinct phases in the development of frothing agents and other flotation chemicals: 1) 1860 to 1920-oil flotation, and 1921 to date-chemical flotati0n.2~3 Early in the first period, large quantities of fatty and oily materials, up to 10 to 20% of the weight of the ore, were used as a means of separating the sulfide and oxide components from the gangue minerals in ore pulps. Later, various gases replaced these large quantities of oil as a buoyant and separating medium, decreasing oil requirements to less than 1% of the weight of the ore. With this reduction in oil

Jan 1, 1962

By Ellis Clark

The greater portion of the brown ore in the vicinity of Easton, along the north slope of the Lehigh Mountain or Durham range of hills, is obtained from mines instead of from open cuts or quarries, as is the case in the ore-beds in the western part of Northampton County, in Lehigh County, and in Berks County. The reasons for this method of procedure are various, and the principal causes of the shaft and regular mine system of working being adopted instead of the open air cuts, are: First, the large amount of stripping that would be necessary, as the richer and more valuable portions of the ore do not appear to be found as near the surface as those in other portions of the Kittatinny valley; second, the occurrence of the ore in regular beds, interstratified with the clay, and, to a less extent, in pockets or erratic deposits, as is the case in the mines of Lehigh County; and third, on account of many of the mines being situated at the immediate base of the Lehigh Mountain, where the surface water would be in such large quantities as to be with difficulty handled, and where the subsequent caving in of the sides of the open cut would be almost certain to expose the gneiss rock, which is water-bearing, the large quantities of water coming from which would probably drown out the ore-bed. Shafts, and a regular system of gangways and mining are therefore required by the configuration of the surface, the depth of the deposits and their geological structure. The ordinary size of the shafts is about four feet square, but where an extensive plant of pumping machinery is required the size may be increased to eight feet by six, with two compartments for the hoisting and pump-shaft respectively. A man-way, consisting of ladders with rests at intervals of twenty or thirty feet, is comprised in the pump-shaft, the wire rope being used for purposes of ascent and descent only in exceptional cases, on account of accidents which

Jan 1, 1879