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By Graham Bright

Before the arrival of central-station power, all coal and metal mines generated their own power and, in many cases, these isolated power plants gave a fair continuity of service. In coal mines that produce considerable gas, it is essential that power be available at all times for operating the ventilating fan and the hoist, if the mine is of the shaft type. In the case of an isolated power plant, if trouble should develop with the fan the men can be hoisted quickly when the mine is of the shaft type. On the other hand, if trouble develops with the hoist, the fan can be kept in operation, and there will be no necessity of haste in getting the men from the mine. Now that central-station power is being used so extensively for mine service, the continuity of service with gaseous mines is very important. : Inherently, the central station is much more reliable than any isolated plant, but trouble may occur on the transmission lines which may prevent the transmission of power for a considerable time. : Some mines have kept their steam equipment intact and ready for operation in case the purchased power should fail. This is expensive procedure, for the boiler plant must be fired at all times so that the emergency power will be quickly available. In a number of instances, gasoline-engine driven generators have been installed to furnish emergency power for the service hoist. As most service hoists are of the alternating-current type, the generator of the gasoline-engine driven set is usually of the a.c. type and is arranged to drive the service hoist motor at full speed, or an extra motor that can be thrown into gear on either the main or service hoist and the hoist operated at a greatly reduced speed. This arrangement is used because it is difficult and expensive to obtain and install large gasoline-engine driven units. The author has recently developed a plan by which the main hoist and the fan can both be operated at reduced speeds, in case of loss of power from a central-station power system. In this plan a gasoline-engine

Jan 1, 1923

By Graham Bright

Before the arrival of central-station power, all coal and metal mines generated their own power and, in many cases, these isolated power plants gave a fair continuity of service. In coal mines that produce considerable gas, it is essential that power be available at all times for operating the ventilating fan and the hoist, if the mine is of the shaft type. In the case of an isolated power plant, if trouble should develop with the fan the men can be hoisted quickly when the mine is of the shaft type. On the other hand, if trouble develops with the hoist, the fan can be kept in operation, and there will be no necessity of haste in getting the men from the mine. Now that central-station power is being used so extensively for mine service, the continuity of service with gaseous mines is very important. : Inherently, the central station is much more reliable than any isolated plant, but trouble may occur on the transmission lines which may prevent the transmission of power for a considerable time. : Some mines have kept their steam equipment intact and ready for operation in case the purchased power should fail. This is expensive procedure, for the boiler plant must be fired at all times so that the emergency power will be quickly available. In a number of instances, gasoline-engine driven generators have been installed to furnish emergency power for the service hoist. As most service hoists are of the alternating-current type, the generator of the gasoline-engine driven set is usually of the a.c. type and is arranged to drive the service hoist motor at full speed, or an extra motor that can be thrown into gear on either the main or service hoist and the hoist operated at a greatly reduced speed. This arrangement is used because it is difficult and expensive to obtain and install large gasoline-engine driven units. The author has recently developed a plan by which the main hoist and the fan can both be operated at reduced speeds, in case of loss of power from a central-station power system. In this plan a gasoline-engine

Jan 1, 1923

By L. S. Darken

THE manufacture and treatment of metals comprises operations whose effectiveness depends in large measure upon diffusion phenomena. The significance of such phenomena has, for a few simple cases, long been understood, but in more complex cases it has not been adequately recognized. This paper presents a mathematical analysis of some of the cases in which diffusion leads to the formation of a new phase within the metal, and this analysis provides a basis for interpreting quantitatively many apparently diverse experimental observations recorded in the literature, some of which are outlined in the following pages. OBSERVATIONS RECORDED IN LITERATURE An outstanding instance is the general type of phenomenon in which diffusion of an element into an alloy is followed by a phase change, which most frequently is a reaction (precipitation) of the diffusing element with one or more components of the alloy to form a compound. Thus in certain alloys heated in contact with oxygen not only the usual oxide scale appears but, in addition, beneath the surface, a well-defined zone in which free oxide particles are dispersed with notable uniformity. This zone, commonly referred to as the subscale or zone of internal oxidation, is remarkable in that the visible boundary between it and the unaltered metal is usually sharp. Such a subscale, which appears to have been recognized first in oxidized copper alloys, has been described and studied by C. S. Smith,1 by Rhines,2 and by Rhines, Johnson and Anderson;3 but it appears also in other alloys when they are exposed to conditions that bring about the precipitation of some compound, not necessarily an oxide. Another clear case of this same kind is the diffusion of carbon into a steel containing an element such as molybdenum, chromium, vanadium or tungsten, whose carbide is less soluble in iron than iron carbide, the result being that some part of that element is precipitated as a dispersed carbide. A similar phenomenon may occur on the welding of two alloys each of which contains one of a pair of elements that react to form a compound or a new phase of any sort. But in addition to the precipitation of a compound formed from the diffusing element, other effects may result merely from the presence of the diffusing element. For instance, if homogeneous austenite, nearly saturated with respect to carbon, is heated in contact with silicon in the absence of oxygen, one would expect to find, behind the several iron-silicon phases analogous to a scale, a zone of austenite containing dispersed carbide, because of the fact that silicon decreases the solubility of carbon in iron. As still another example, oxidation of an alloy may result in diffusion toward the surface of one or more of the constituents; for instance, during oxidation of a steel containing an element such as copper, which is less prone to oxidation than iron, there is a notable enrichment of copper just beneath the scale-metal interface. As an example of a yet more

Jan 1, 1942

By Castle. J. E., J. L. Gillson

In this chapter there is a wide difference in the meaning of some words used for rock and mineral names as defined by scientists and tabulated in the "Glossary of Geology and Related Sciences," published in 1957 by the American Geological Institute, and the meaning as used by the commercial producers of feldspar. It is necessary, therefore, to define these terms giving both the "scientific" and the "practical" definitions. There is no ambiguity about the name feldspar itself. This is a general term for a group of related minerals which are silicates of aluminum, combined with sodium, potassium and calcium. The feldspars are the most abundant minerals of the igneous rocks, and since these rocks make up the largest proportion of the earth's crust by volume (although not of the actual surface area of the continental land masses) the feldspars are the most abundant minerals of all. The igneous rocks themselves are classified on the basis of the variety of the feldspar present. The potash feldspars, which are called orthoclase and microcline, are the dominant minerals of the granites and syenites, and of their fine grained equivalents, the rhyolites and trachites. The plagioclase feldspars form an isomorphic series, of which the sodic endmember is called albite, and the lime endmember, anorthite. The members near the sodic end, albite, oligoclase and andesine are the characteristic feldspars of the granodiorites and diorites, and of their fine grained equivalents, the dacites, and andesites. These feldspars-orthoclase, microcline, albite oligoclase and andesine-are the feldspars used commercially. Labradorite, a member of the plagioclase group, in which the lime exceeds the soda in the chemical composition, is the common feldspar of the gabbros, anorthosites, norites, basalts and other so-called "basic" rocks. Although some attempts have been made to use labradorite as a commercial feldspar, none is now used except as an ornamental stone. The mineral anorthite is very rare. Since the feldspar in most of the common igneous rocks is relatively fine grained, and mixed intimately with other minerals, from which it can be separated cleanly only with difficulty, most masses of the common rocks cannot be used as sources for the feldspar contained in them. It is only the rarer types of rocks in which the feldspar is very coarse-grained, or ones containing very little of the iron-bearing minerals which are objectionable impurities in commercial feldspar, that are quarried to yield an acceptable product. The most widespread type of such a rock from which commercial feldspar can be produced, is that called "pegmatite." These rocks are dikes and bodies of irregular shape and of a size measured in feet or yards in most cases, rather than in miles. They are more commonly associated with granites, rather than with other coarse-grained igneous rocks. Many of them contain crystals of various minerals, including the feldspars, that are much larger than are found in the host rock, the granite, and in many there are large masses of feldspar that are sufficiently free from iron-bearing silicates so that products acceptable to the ceramic industry can be produced, in some cases simply by hand sorting. Most of this feldspar in pegmatites, however, does contain intergrown quartz up to 25 pct. Pegmatites are so important, not only as commercial sources of feldspar, but also of other minerals which are produced com-

Jan 1, 1960

By Gerald Sherman

MINE fires are always dangerous and are frequently accompanied by loss of life during the period of confusion which is apt to follow their discovery. In metal mines, fires may result from the accidental ignition of some combustible material, or they may be of spontaneous origin resulting from the rapid decomposition of sulphide. They occur frequently enough to demonstrate the need of some special equipment and a general plan for controlling them, in addition to measures for their prevention. Nearly all the large copper mines have had fires, and the methods of fighting them have been well described in recent papers, notably-by C. L. Berrien,1 R.. E. Tally,2 and others in discussion. The Copper Queen mine has many shafts, which are connected by underground workings. The deeper parts are ventilated by fans, but in the shallower portions natural ventilation through numerous connecting raises or shafts is sufficient. There have been several fires in the past few years, of which all are extinguished but one, and that is under control. These notes cover particularly the preparations that are being made-to check a new fire, partially or temporarily, and to facilitate the escape of workmen in the interval before a definite plan of fighting it can be established. A fire may occur in a shaft or station, or in some working father away. In case of fire in an upcast shaft, the gas would escape to the surface and the immediate result would probably not be dangerous to workmen, as they could escape by other shafts. In a downcast shaft, however, the gas would be distributed very rapidly throughout a large portion of the mine, and men might easily be trapped and asphyxiated. A fire in mine workings, drift, raise, or stope, would be dangerous in a degree, but the draft there is likely to be less strong than in a shaft and probably a smaller area would be invaded by the fire gases.

Jan 1, 1918

By Gray L. L., Max Littlefield, Godbold A. C.

The West Edmond pool of Central Oklahoma, a limestone reservoir, has an area in excess of 29,000 acres and as of Sept. 15, 1946, had produced 53 million barrels of oil from 731 wells at an average depth of 6900 ft. Water has encroached into the reservoir along the west side of the pool and although the area of water invasion is large the net volume of water influx is small, because encroachment has been primarily into a fracture system. The most significant part of this study concerns the character of the Hunton reservoir. Geological study of cores of the producing section was made to supplement core-analysis data. It was determined that approximately 90 pct of the pore volume was contained in intergranular or sand-like porosity and 10 pct in fractures (intermediate porosity). The porous limestone is divided into blocks by the fractures, although in the strongly dolomitic parts of the producing section, fractures are less well developed. The low-permeability intergranular porosity, largely subsidiary to the high-permeability fractures, will produce oil into the fractures by evolution of solution gas. The fractures in effect serve as drainage channels for production of oil from the inter-granular porosity. Because of such a large difference in permeabilities of the two com-ponents, a high degree of by-passing will occur, and, accordingly, the economics involved in undertaking full-scale high pressure gas injection operations have been seriously questioned. Introduction The West Edmond Hunton pool, which covers portions of Canadian, Logan, Oklahoma, and Kingfisher Counties in Central Oklahoma, is the largest reservoir producing oil from a limestone in the state. The total area of the pool comprises about 29,240 acres and development is considered to be essentially complete. In all, 731 producing wells have been completed in the Hunton reservoir at an average depth of approximately 6900 ft, and have yielded a cumulative oil production in excess of 53 million barrels as of Sept. 15, 1946. In addition to wells completed in the Hunton limestone, 21 wells have been completed in the Bartlesville sand at a depth of approximately 6500 ft, which have produced a total of 730,000 bbl of oil. One small producer has been completed in the Cleveland sand at a depth of 5700 ft. However, a study of only the Hunton limestone reservoir will be presented in this paper. The most significant phase of this study concerns the special type of geological core examination that was made in an effort to ascertain the type and degree of porosity in the rock in accordance with lithologic types. Results of this geological study showed the west Edmond pool to be of such a complex nature as to appreciably affect the behavior normally associated with homogeneous reservoirs. Recognition of this condition in the

Jan 1, 1948

By Max Littlefield, Godbold A. C., Gray L. L.

The West Edmond pool of Central Oklahoma, a limestone reservoir, has an area in excess of 29,000 acres and as of Sept. 15, 1946, had produced 53 million barrels of oil from 731 wells at an average depth of 6900 ft. Water has encroached into the reservoir along the west side of the pool and although the area of water invasion is large the net volume of water influx is small, because encroachment has been primarily into a fracture system. The most significant part of this study concerns the character of the Hunton reservoir. Geological study of cores of the producing section was made to supplement core-analysis data. It was determined that approximately 90 pct of the pore volume was contained in intergranular or sand-like porosity and 10 pct in fractures (intermediate porosity). The porous limestone is divided into blocks by the fractures, although in the strongly dolomitic parts of the producing section, fractures are less well developed. The low-permeability intergranular porosity, largely subsidiary to the high-permeability fractures, will produce oil into the fractures by evolution of solution gas. The fractures in effect serve as drainage channels for production of oil from the inter-granular porosity. Because of such a large difference in permeabilities of the two com-ponents, a high degree of by-passing will occur, and, accordingly, the economics involved in undertaking full-scale high pressure gas injection operations have been seriously questioned. Introduction The West Edmond Hunton pool, which covers portions of Canadian, Logan, Oklahoma, and Kingfisher Counties in Central Oklahoma, is the largest reservoir producing oil from a limestone in the state. The total area of the pool comprises about 29,240 acres and development is considered to be essentially complete. In all, 731 producing wells have been completed in the Hunton reservoir at an average depth of approximately 6900 ft, and have yielded a cumulative oil production in excess of 53 million barrels as of Sept. 15, 1946. In addition to wells completed in the Hunton limestone, 21 wells have been completed in the Bartlesville sand at a depth of approximately 6500 ft, which have produced a total of 730,000 bbl of oil. One small producer has been completed in the Cleveland sand at a depth of 5700 ft. However, a study of only the Hunton limestone reservoir will be presented in this paper. The most significant phase of this study concerns the special type of geological core examination that was made in an effort to ascertain the type and degree of porosity in the rock in accordance with lithologic types. Results of this geological study showed the west Edmond pool to be of such a complex nature as to appreciably affect the behavior normally associated with homogeneous reservoirs. Recognition of this condition in the

Jan 1, 1948

By R. W. Raymond

That the death of Martin Coryell, which occurred at Lambertville, New Jersey, on Monday morning, November 29th, touched the sympathies of a wide circle of professional associates and personal friends, was amply testified by the gathering at the funeral services on Friday. Like his distinguished friend and neighbor, the late Ashbel Welch, Mr. Coryell was one of those pioneers in American engineering to whom we owe the great railway and canal systems which lie at the base of our national prosperity, and who have consequently enjoyed the respect and esteem of their successors of the present generation. Martin Coryell was born July 20th, 1815, at New ope, Rucks County, Pa., and was educated principally in the schools of his native town arid of Lambertville, New Jersey, to which place he returned for permanent residence fifty years later. With the exception of a brief period in youth, during which, to restore his failing health, he learned and practiced for a few months the carpenter's trade, and another brief period, later in life, when he read law for a time in the office of B. H. Brewster, of Philadelphia, afterwards Attorney-General of the United States, Mr. Coryell may be said to have spent his life as an active civil and mining engineer. Even these two episodes can scarcely be said to have been deviations from that profession, since they served to give him more thorough preparation for constructive and administrative work. The Delaware Division Canal, the Raritan Canal, and the Brunswick Canal, are among those upon which Mr. Coryell was employed. For the Raritan Canal Company, under the superintendence of Ashbel Welch, he located the greater part of the Belvidere Railroad (now the Belvidere division of the Pennsylvania Railroad), and directed its construction from Trenton to Lambertville. He was also active as a mining engineer, being one of the early pioneers of mining in the Lake Superior copper region, and had much to do with the development of the Hazleton coalfield and the railroad which has since expanded into the Lehigh Valley system. In 1862, he removed to Wilkes-Barre, where, in 1864, he became manager of the Warrior Run Mining Company. One of the editors

Jan 1, 1887

By D. A. Kraai, S. Floreen

The effect of 1 to 50 ppm S on the ductility of nickel at 800° to 1400°F was studied. Results at each temperature showed a decrease in the reduction of area from approximately 95 to 5 pet over the sulfur range studied. Ductility varied with grain size, but only to a minor extent relative to the sulfiw effect. The effects of sulfur were completely offset by the addition of small amounts of magnesium. The results indicate that the "hot-short" loss in ductility is not an inherent property of nickel. Some possible mechanisms which cause the loss in ductility are described. MANY metals or alloys that normally possess high ductility exhibit a ductility loss at intermediate temperatures. This loss in ductility is often called "hot-shortness". Numerous examples of this phenomenon have been reported in the literature. Much of this work has been reviewed by McLean1 and by Rhines and Wray.2 To date there is no fully satisfactory explanation of the cause of this intermediate-temperature hot-shortness. It is generally recognized that impurities, and particularly impurities that form low-melting phases, can cause embrittlement. Examples of hot-shortness have been reported, however, where there were no obvious impurities present which would lower the ductility. Thus there has been some basis for believing that hot-shortness is an inherent property, and that even the purest metal would display a hot-short loss in ductility. This latter hypothesis was recently put forward by Rhines and wray2 based on studies of nickel and nickel alloys. In the discussion of this paper, however, Guard noted that high-purity nickel showed no hot-shortness.3 Thus there is reason to doubt whether pure nickel, or by inference any other pure metal, will inherently exhibit hot-shortness. The present work was initiated to determine the extent to which hot ductility was sensitive to very small amounts of an impurity element. If it could be demonstrated that hot-shortness could be induced by only minor amounts of an impurity, then it might be argued that hot-shortness in general is an impurity effect, and not a fundamental property of pure metals. The particular impurity studied was sulfur in nickel. The deleterious effects of sulfur are well- known. It is also well-known, and will be shown below, that additions of magnesium will render sulfur innocuous. When no such refining agents are added, however, the Ni-S system is a very useful one for studying the influence of small amounts of impurities. EXPERIMENTAL PROCEDURE Two heats containing -24 ppm S were vacuum-melted and small amounts of magnesium were then added under an argon atmosphere. These alloys were used to show the effectiveness of the normal magnesium treatment in overcoming the influence of sulfur. A second series of alloys with a sulfur range of 1 to 50 ppm was then prepared by vacuum melting nickel in alumina crucibles. No elements, such as magnesium, which tend to combine with sulfur were added. The higher sulfur contents were attained by adding nickel sulfide. Lower sulfur contents were prepared using a method in which the melt was oxidized under vacuum to produce the reaction S + 2O = SO2 These heats were subsequently deoxidized with carbon. Ten- to twenty-pound ingots were cast of all of the alloys studied. The compositions are given in Table I. The ingots were forged and hot-rolled to 3/4-in. bar. They were then annealed at either 2000" or 1600°F to produce different grain sizes. One-quarter-in.-diam tensile specimens were machined from the bars. These were tested at 800°, 1000o, 1200°, and 1400°F. The specimens were held at temperature approximately 45 min before testing. The strain rates were 0.005 min-1 to yielding, and 0.05 min-' after yielding. No extensometers or gage marks were placed on the specimens because the higher sulfur heats tended to fracture at the knife-edge indentations or gage marks. The properties measured were ultimate tensile strength and reduction of area. The analytical technique for determining sulfur at low levels was that developed by Burke and Davis.4 They reported a standard deviation of 1 ppm at an average sulfur level of 4 ppm in NBS standards. A standard deviation of 3 ppm is probably more realistic for the alloys used in this investigation considering the possibility of some segregation in the ingots. RESULTS A summary of the tensile results is given in Table I. As shown in the table, both heats to which

Jan 1, 1964

By Wayne E. Tuomi

The mining industry is faced with a pressing problem; that is, to develop more efficient methods of extraction, handling and upgrading-techniques that will do the job faster and better than ever before. New techniques require new machines, or applications of new and improved materials that can be used to modify and improve existing machine and equipment designs. The traditional approach has been to increase productivity by increasing equipment size. Prognostication indicates that the trend toward larger equipment sizes and capacities will continue as one answer to the challenge imposed by future increases in mineral demands. But what is the limit on the continued growth of equipment size? Until about 1930, there was a very definite limit-a limit imposed by the strength of the steels and the power plants then available. The equipment engineer had come to an impasse: even though it was easily possible, for instance, to triple the size of a bucket, it had become impractical to correspondingly enlarge the boom, the counterweight, and the power plant.

Jan 3, 1967

By M. C. Fuerstenau, D. W. Fuerstenau

Studies of the collection of alkali and ammonium halides utilizing vacuum flotation techniques and contact angle measurements show that ionic size controls the flotation of techniquesthese halides with amine salts measurementsas collector. Contact angles of air bubbles on sylvite in saturated brines were withaminemeasured salts asascollector.a function of such variables as collector addition, length of collector chain, and pH of the brine. No contact occurs between halite and an air bubble in brines containing dodecylammonium acetate as collector. LONG-CHAINED aliphatic amine salts have been used for the separation of sylvite (KCl) from halite (NaCl) by flotation.1,2 It is puzzling how these two minerals, which are so similar chemically and crystallographically, can be separated by this method. Gaudin" has postulated that the difference in floatability of halite and sylvite with salts of primary amines depends on ionic size: In the case of amine flotation, the cation would attach itself to the chloride. I have a speculation there, which I cannot prove, that the ammonium group, that is the —NH3 group in the amine, floats potassium chloride because the dimensions of this grour, as it has been measured in other compounds is almost identically the dimensions of the potassium ion, quite different from the sodium ion, and so it fits where potassium had been, in place of it and not attached to it. Apparently, because an aminium ion (RNH3+) is much larger than a sodium ion, it cannot fit into the lattice of halite. Taggart also has speculated that ionic size may control the floatability of sylvite.4 The object of this experimental investigation has been to test this hypothesis and to study what controls the adsorption of cationic collectors at the surface of sylvite. Since collection is to be approached from the viewpoint of ionic size, the ionic radii that are of interest in this work are presented in Table I. The values of the ionic radii of the ions listed in Table I, except NH4+, are those given by Pauling." Several different values for the radius of the ammonium ion have been given, but that of Goldschmidt6 seems to be preferred. The radius of the charged head of a dodecylammonium ion is assumed to be the same as that for the ammonium ion. Little experimental work has been reported in the technical literature concerning the separation of sylvite from halite by flotation. Guyer and Perren studied the separation by flotation of 50 pct binary mixtures of NaCl, KC1, NH,Cl, NaNO3, KNO3, K2SO4, and Na,SO, using either oleic acid or a sodium sul-fonate as collector.' It is possible to measure floatability under actual flotation conditions where all three phases, air- water-mineral, are present by vacuum flotation tests and contact angle measurements.9 Both of these techniques were used in the experimental approach in this paper. Experimental Method and Materials The vacuum flotation tests were run with glass-stoppered pyrex graduated cylinders. Twenty-five ml graduates were used to test the floatability of all salts studied except rubidium and cesium salts. For each test distilled water containing the desired collector concentration was saturated with the salt to be floated. Sufficient salt (—48 mesh) was added to leave about 2 ml of solids in the bottom of the graduate. After the graduate had been agitated several minutes to saturate the solution with air, a vacuum was applied. If the salt were floatable in the collector solution, the gas bubbles attached themselves to the particles, and the particles floated to the surface. In determining the floatability of the expensive Rb and Cs halides, the experiments were run in 10 ml graduates with about 11/2 ml of collector solution initially. Contact angles were measured in the usual manner except that the solutions had to be previously saturated with the mineral to avoid dissolution of the crystal. Solutions for studying contact angles were made by adding the desired amount of collector to a saturated brine, giving the collector concentration in molarity. The mixture was agitated until dissolution of the collector was complete, with the exception of those concentrations greater than about millimolar. At these high concentrations complete dissolution of the collector was impossible. The face of the mineral to be tested was a freshly cleaved crystal of halite or sylvite. The mineral was placed in the brine and conditioned with collector for at least 15 min, which was found to be long enough to obtain a maximum value for the contact angle. The temperature remained constant during each experiment. The experiments were run at 24°C ±2°C. For contact angle measurements, a crystal of halite from Carlsbad, N. M., was used. Several samples of sylvite were used in this work: a crystal of sylvite from Stassfurt, Germany; a crystal from Carlsbad, N. M.; and a crystal of chemically pure potassium chloride. Saturated brines were made from reagent grade chemicals and distilled water.

Jan 1, 1957

By T. S. Lundy, R. E. Pawel

Effects of short-circuiting paths on observed diffusion behavior in real crystalline systems are considered. It is concluded that experimentally measured diffusion coefficients may vary widely from values associated with true lattice diffusion to those appropriate for short-circuiting paths alone depending upon the conditions of the experiment and the sensitivity and completeness of the data. IN 1961 Harrison1 classified experimentally observed diffusion behavior in systems involving both lattice and dislocation-enhanced atomic transport into three categories. His types A and C were limiting cases where the measured diffusion coefficients using the usual serial sectioning techniques were representative of lattice diffusion (with only slight effects of dislocations) and dislocation-network diffusion (with only slight effects from lattice diffusion), respectively. In both cases A and C for a sectioning experiment in which the diffusion couple has the semi-infinite geometry and unidirectional diffusion takes place from a plane source located at the origin of the coordinate system, he pointed out that Gaussian penetration behavior should be observed. For case A the lattice coefficient should be slightly enhanced by dislocation contributions, and the model of Hart2 can be used to predict the amount of this enhancement. For case C the observed coefficient should be that for the dislocation network and have little or nothing to do with lattice diffusion. Hart's model in its general form is still applicable, but the apparent diffusion coefficient for this case is virtually independent of dislocation density. Harrison's case B is that for which non-negligible contributions exist for transport by both mechanisms and "the concentration distribution does not approximate to any simple form." With the possible exception of very low temperatures where diffusion distances approach atomic dimensions, any real diffusion specimen will in general show non-Gaussian behavior provided the data are complete enough to uncover it. Thus, a "complete" set of data for any real system cannot be expected to be totally amenable to treatment by a simple mathematical model which does not take into account the relative distribution of transport by the various modes or submodes. For a particular sensitivity of specimen analysis and at a given temperature of annealing if the concentration profile could be observed as a function of time, "the behavior will initially be type C, and will develop into type B. and ultimately type A".1 Thus, it appears that the type of diffusion behavior which is experimentally observed in a given system depends very much upon the particular experimental conditions and the particular tools available to obtain the data. Interpreted in this fashion, Harrison's classification refers not to the diffusion behavior as a whole but to the relative sensitivity of the method of examination and completeness of the data. In the present paper we will: 1) assume that the measured penetration behavior follows the same general classification as that proposed by Harrison; 2) give, for diffusion in tungsten, examples of the range of diffusion coefficients that it is possible to obtain in a single experiment; and 3) speculate that some arguments which consider the possibility of short-circuiting effects being responsible for "anomalous" diffusion in several bcc metals may have been discarded prematurely.3 Both monocrystalline and polycrystalline tungsten were used in this work. The former was obtained as triple-pass, electron-beam zone-refined 6.0-mm-diam rod from Materials Research Corp.. Orange-burg. N.Y. The latter was swaged, high-purity bar stock which was annealed for 2 hr at 2200°C and 10-9 torr to yield an average grain diameter of about 25 /i. The tracer Nb95 was received in oxalate solution from the Isotopes Division, Oak Ridge National Laboratory. Experimental procedures of specimen preparation, isothermal diffusion annealing, serial sectioning by anodizing-and-stripping, and y counting of the individual sections to determine the tracer penetration profile after a given diffusion anneal have been described elsewhere.4 However, it should be noted that the anodizing-stripping sectioning technique has the particular advantage for this research of permitting sectioning to be accomplished over a wide range of

Jan 1, 1970

By Roscoe C. Clark

In a previous technical note' by Walter Rose, evidence is offered in support of the contention that "the possibility of describing oil recovery features in terms of capillary pressure phenomena has not been established entirely." It is not the purpose of this note to present further discussion of this possibility but rather to point out that the argument presented there does not appear to be generally valid. In the cited note' reference is made to the experiments of Welge2 wherein it was shown that when water was displaced by oil from a core the pressure in the water phase was less than in the oil phase but that when this oil was then produced by water drive the pressure in the water phase was greater than in the oil phase. Rose has concluded from these observations that conditions of static equilibrium did not obtain since the fluid saturations were such that phase discontinuities seemed unlikely. The argument from which this conclusion was drawn is based on the contention that "the pressure is always greatest in the non-wetting phase at each static interstitial interface of contact with the wetting phase." This premise appears to have been reached from a consideration of capillary phenomena in cylindrical tubes, although it may a1so hold for other types of pore geometry, hut as will be shown below it does not hold for all pore shapes and hence is not generally applicable. Since the pore structure of porous media such as reservoir rocks i- in general so complex as to defy exact description. it is undoubtedly of great value to establish a model in terms of pore shapes of known geometry, provided of course that the limitations of the model are recognized. That the limitations of the capillary. or cylindrical, tube model have not always been fully recognized will be evident from the following discussion of a pore of different shape hut one which may a. logically he considered a.; the capillary tube. The pore space to be considered is that shown in Fig. 1, which may be thought of as the "hole in a doughnut."* Consider the interface, A-B-A', between two immiscible fluids, P, and P2, which interface meets the solid alone a line, A-C.A'-C'. The interface A-B-A' is the surface of a spherical segmen† while the line of mutual contact be-

Jan 1, 1950

By George Rice

THE subject of violent bumps in coal mines has been again brought to attention by a recent succession of such occurrences in the coal mines of the Cumberland field of eastern Kentucky and southern Virginia, which have caused fatalities and injuries to underground employees, a report on which is being issued by the United States Bureau of Mines1. The A.I.M.E. has had two valuable papers on bumps in the No. 2 Mine, Springhill, Nova Scotia, each followed by general discussion on bumps and their causes2. This paper gives a brief review of suggested causes and remedial measures given in English, Canadian and United States reports on bumps in coal mines, and then presents suggestions arising from the writer's recent investigation of the bumps in the Cumberland mines, made at the request of the mine operators, to determine the causes and remedies. These bumps, which occur under the simplest natural conditions, provide better opportunity for analysis of causes and effects than afforded under more complex conditions. The simple conditions in this field consist of relatively thin and level coal beds and uniform roof strata free' from folding and faulting.

Jan 1, 1935

US 4,135,913-Extraction of nickel values from iron-containing nickel sulfide ore, particularly pentlandite or nickeliferous pyrrhotite A mixture of raw ore, roasted ore, or iron powder, and coal as a reductant is heated to a temperature of 800- 1000° C in a nonoxidizing atmosphere to convert the bulk of the iron content to metallic iron while diffusing into the iron the bulk of the nickel, the mixture cooled, and the cool material separated into a magnetic fraction containing most of the nickel and a non-magnetic gangue fraction A Illis arid L S Renzoni, assigned to International Nickel Co, Inc Jan 23, 1979 7 pp (75-21) Filed 10-10-75 (621,343) Priority Canada, 10-27-72 (155,032) Same Canadian 981,910, dated Jan 20, 1976 Same British 1,389,145, dated Apr 3, 1975 US 4,135,917-In the recovery of gallium from a solution obtained by the digestion of bauxite or nepheline in an alkali solution for the production of alumina, the digestion solution is neutralized, the neutralized solution evaporated to an op¬timum caustic alkali concentration and adjusted to a ratio of alkali metal oxide to alumina of above 2, the corrected solu¬tion contacted with a gallium-aluminum alloy, arid high-purity gallium recovered from the solution by electrolysis or cemen¬tation K A Badaliants, et al Jan 23, 1979 6 pp (75-109) Filed 12-19-77 (862,201) Priority USSR, 12-22-76 (2,428,¬006) US 4,135,918-Extraction of copper from copper sulfide ore containing also one or more of the metals iron, nickel, arid cobalt Ore is roasted at a temperature of 750-800° C to expel sulfur, the sulfur-free calcine slurried in water containing a sufficient amount of sulfuric acid to supplement any sulfuric acid formed in situ, the slurry heated at 150-165° C in the presence of a reducing gas to form soluble sulfates of metals other than copper while reducing copper to elemental form, arid the slurry filtered to recover copper solids Any precious metals present in the ore will report with the copper solids V A Ettel, A P Devuyst, R Sridhar, arid C. E O'Neill, as¬signed to International Nickel Co, Inc Jan 23, 1979 5 pp (75-117) Filed 3-2-78 (882,610) Priority Canada, 5-13-77 (278,360)

Jan 1, 1980

By R. J. Linney

Reserve Mining Co. produces 5 million tons of iron ore pellets per year. The finished product runs about 65.50 pct Fe, with 7.75 to 8.00 pct SiO2. Less than 12 pct arrives at the blast furnaces smaller than % in. This plant was originally designed to produce 3.75 tons annually—not 5 million. To handle the increased tonnage a fifth fine crushing line was added, and some very minor changes were made. When production can be stepped up 33 1/3 pct without extensive additions or changes—within the short period of a year—basic engineering has been sound. Operators of the plant consider it the best design job they have seen or heard of, and competent authorities have said that start-up was quicker and easier than for any previous large-scale minerals beneficiation plant. One big advantage is the elbow room allowed. Generally speaking, there is an eternal conflict between operator and designer over space. The designer has his costs per cubic foot, and he is keenly aware that if he permits the number of cubic feet to rise unnecessarily, total costs will be too high. But this was a new operation, and on a large scale. There were no proven standards to go by. Realizing this, Reserve's engineers provided ample and efficient access to machinery, allowing extra space for unanticipated situations. In three years of production this planning has paid off handsomely. Gravity Flow Saves Time and Money: This plant is on a rocky hillside, the car dumper about 270 ft above Lake Superior. In locating buildings and placing machinery the designers mad= good use of gravity flow, at considerable financial savings. In the concentrator building from rod mills to filters, gravity carries the material between all stages of the operation except one—the closed circuit pumping of concentrate between cone classifiers and ball mills. Since no machine is located directly above any other, an observer can stand on the truck ramp adjacent to the offices and laboratory and see practically every phase of activity in the huge building. The first mill section started in August 1955. After a day's run several modifications were made on auxiliary chutes and launders where spillage had occurred. This procedure was followed for the first

Jan 1, 1960

By Fred Bond

WHEN some materials are ground dry in a ball mill, a stage of comminution is reached at which the finely divided particles begin to adhere to the balls and to the mill lining. As grinding progresses, a coating accumulates upon the grinding media, which tends to cushion the impacts and thus retard reduction of the material, and finally becomes so thick that all grinding ceases. At this stage, the characteristic noise produced by the grinding media dur-ing normal mill operation changes to a dull, muffled sound. In most instances, the formation of the coating marks the practical limit of size reduction. Industrial requirements for fine grinding frequently meet with this obstacle, and the tendency in many com-mercial operations to grind materials to a higher degree of fineness than formerly makes the solution of this problem an im-portant one. The phenomenon is of far greater importance, therefore, than the limited amount of research and technical discussion devoted to it implies. In order to learn more about the coating of different materials when ground dry to a high degree of fineness, certain labora-tory tests were made from which it was found that different materials form coat-ings at widely different size distributions. It is probable that most materials will coat if they are ground fine enough; the exceptions have inherent lubricating qual-ities, like coal and graphite.

Jan 1, 1940

By Harold R. Bradford

EXPANSION initiated during and after the war has placed industrial plants in new areas and increased reduction and manufacturing facilities in communities already established. With added expansion interest has grown in possible area contamination from waste products. Evolved flue waste contains many chemical contaminants that may or may not cause concern; however, atmospheric pollution has always been a problem to industrial communities. For some time effects attributed to small quantities of compounds of fluorine in various waste gases have been studied by industrial, medical, agricultural, and associated interests.1'2 Aside from an article by Churchill, Rowley, and Martin in 1948," little has been published on the subject of fluorine in coal except by foreign investigators. The first indication of fluorine compounds in coal was noted in England in 1934 by R. Lessing,4,5 who found that the presence of fluorine in Midland and West County coals was definitely established by etching of glass and by severe corrosion of porcelain fillings in a gas works scrubber. Etching of glass in a direct contact annealing kiln initiated research, and in 1944 four papers were published by H. E. Crossley,6-9 giving results of investigations of fluorine in coal of England by the Fuel Research Board, Department of Scientific and Industrial Research. These investigations studied methods of determining fluorine, the quantities present in various coal deposits, the geographical distribution of fluorine in British coals, occurrence of fluorine in minerals associated with coal, amounts of fluorine compared to other constituents of coal, the nature of fluorine compounds, and industrial significance of fluorine in coal. It was shown that British coals contain from 5 to 200 ppm of fluorine, which is probably present as fluorapatite [Ca10F2(PO4)6], often written as [3Ca3P2O8.CaF2]. The fluorapatite is intimately associated with shale in some coals and can often be separated from these coals along with the shales. H. E. Crossley8 also reported no correlation between the amounts of chlorine, sulfur, or ash and the amount of fluorine in different coals. He found, however, a relationship between the content of fluorine and phosporus in many British coals. Thus it should be possible to anticipate likely fluorine-rich coals from existing data giving phosphorus content. Behavior of the fluorine compounds of coal was compared with that of 12 fluoride-phosphate minerals in sink-float separations and solvent ex-

Jan 1, 1958

By H. H. Uhlig

A study of passivity in chromium-iron alloys holds considerable interest, both because of the present-clay practical importance of the stainless steels, and because of the scientific importance attached to the mechanism of their corrosion resistance. Upon the discovery of the passive chromium-iron alloys in 1912, it seemed logical to attribute the observed phenomenal corrosion resistance to a thin, continuous, protective reaction product on the surface. The product was thought to be Cr2O3 or a similar oxide containing both chromium and iron. This mechanism seemed likely in view of Michael Faraday's conjecture that passive iron is not reactive in concentrated nitric acid because of an oxide on the metal surf ace. Since 1912, data have accumulated that permit a further exploration into the nature of passivity and provide a new approach to the problem. A summary of the facts lends considerable weight to a mechanism based not on physical protection of an oxide or similar compound, although such compounds may be present on the surface, but to a change in tendency of surface metal atoms to react chemically. This change in reaction tendency is ascribed to chemisorbed films that effectively satisfy residual valence forces of the metal surface, but do not appreciably disturb the positions of metal atoms in the lattice. In other words, formation of a new lattice such as that of an oxide is not a necessary condition for this type of passivity. The decreased reaction tendency of the metal by reason of chemisorbed films can thereby account for low reaction rates of the stainless steels in many media, as well as a noble galvanic potential as is observed. Substances capable of adsorbing on the stainless steels, and hence accompanying the property of passivity, are typically oxygen, nitrites or chromates, but are not in any sense limited to these. Other elements and compounds can also chemisorb, and therefore may also play a major part in the mechanism of passivity in specific media. The mechanism of passivity based on chemisorption or activated adsorption begins with the interpretation Langmuir proposed for his experiments concerning adsorbed oxygen on tungsten.' He found that adsorbed oxygen was tightly bound, remaining on the tungsten surface above temperatures at which WO3 rapidly volatilizes. The oxygen in such a state did not readily react with hydrogen even at

Jan 1, 1949

By Stephen H. Stow

A relationship exists between the color and the chemical composition of the pebbles from the Bone Valley Phosphate Formation. Darker-colored pebbles are relatively high in iron oxide and relatively low in calcium phosphate when compared to lighter-colored samples; the brown color of the phosphate pebbles can be correlated with their iron content and the black and gray colors with their organic carbon content.1,3 It was anticipated that the darkness of a phosphate sample might be quantitatively measured by a simple reflectivity test and that the amount of reflected light could be correlated with the chemical composition of the rock, especially with the elements which cause the color and darkness of the Florida phosphates. Twenty-one samples of production grade phosphate rock from Hillsboro County, Fla., were studied. All samples were ground to -200 mesh for reflectivity tests and analyses. All analyses are accurate to well within ±2% of the reported value, except for aluminum and organic carbon, which are accurate to only ±15% of the reported amount. Reflectivity measurements were taken with a model 610 Photovoltmeter for tri-stimulus amber, blue and green, and white lights. Experimental procedures and data are available upon request. Results Table 1 contains linear correlation coefficients (LCC) for the element-reflectance relationships for the samples. The top portion of the table refers to the LCC between the percent of light reflected off the samples and the percent of a given element (or its oxide) as analyzed. In the lower portion of the table the LCC refers to the relationship between the same reflectance data and the chemical analyses which have been corrected on the basis of 0% acid insoluble material (chiefly quartz) in the phosphate rock. Each LCC presented in Table I is computed for the 14 coarser samples exclusive of the seven concentrates since the concentrate samples appear to have anomalous reflectivities upon comparison with the coarser grades. Only the most significant LCC for each element is presented in graphical form. Discussion of Data Iron: [Fig. 1] is a graph of the relationship between iron and reflectivity (LCC = - 0.98). A good correlation with Fe2O3, is expected due to the relationship between the tan (or brown) color and the abundance of iron oxide, the principal mode of occurrence of iron in Florida phosphates.8 Note the location of the seven triangles which repre-

Jan 1, 1972