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By A. H. Lindley, R. Shorr, Frazier M. Stewart, F. Crerie

The mineral industry, so important to industrial development, faces a major challenge in creating the most effective financial structure to provide funds essential for seeking, evaluating, developing, and extracting minerals. The acquisition of funds for mineral development and plant erection do not differ greatly from fund-raising in nonmineral ventures because risks are essentially comparable. High-risk exploration funds, however, are more difficult for the mineral industry to acquire. With the world's ever-increasing appetite for minerals, the internally generated cash of major oil and mining companies cannot be expected solely to maintain the world's mineral supply. The augmented costs, risks, and difficulties of exploration have been shared increasingly by the smaller independent operator and by private and public participation drilling programs within the petroleum industry over the past 30 years. Only recently has the mining industry awakened to the need for utilizing exploration and development funds derived from sources other than established mining and banking circles. Almost from its inception, the oil industry was forced to drill deep holes through overburden without the aid of a mineral "outcropping" which required geological, and in subsequent years, geophysical interpretation. The poorly financed, nontechnical prospector, who depended on a mineral outcrop, was not to play an important role in oil exploration as he did in mining. Because of the high cost of drilling and the demands for technical judgment to locate an exploration drill hole, corporate and sophisticated private funds generally financed oil discoveries. When external funds were subsequently required, these financially sophisticated explorers would turn to the banking community from which came numerous ingenious innovations, taking cognizance of existing tax laws. Like the oil explorer, the miner is now faced with probing below the surface, relying solely on regional geology and geophysical anomalies. The day is gone, for practical purposes, when the prospector discovers a deposit from a mineral outcrop. There is little doubt that the mining industry will now follow the course taken by the petroleum industry in acquiring external funds if it is to meet the future raw material requirements of the world. The oil industry has been able to attract bank funds more readily than the mining industry after a mineral discovery has been made because: (1) with few exceptions, an oil discovery can be placed into commercial production and will generate cash at much less expense and time than a mine; and (2) generally, costs of oil production, the value

Jan 1, 1976

By B. W. Prof. Frazier

(Read at the Wilkes-Barre Meeting, May, 1877.) THIS interesting application of the laws of thermodynamics to metallurgical practice has not been discussed by any writer, within my reading, except the late Prof. Gallon of Paris. In his Cours de Machines,* Prof. Callon has given a short but lucid discussion of this subject in the admirably clear style for which he was remarkable. Although the interest attached to the subject is rather theoretical than practical, I have thought that an attempt to explain the mechanical action exerted in the hot-blast oven might not be entirely devoid of utility, especially in the suggestions which it involves. The statement, that the mechanical work performed in heating the blast is, when high temperatures are produced, considerably greater than the work performed by the blowing-engine, may seem incredible to many who are practically acquainted with the subject, appearing, as it does, to conflict with the results of their experience. It is, nevertheless, literally true, and I shall attempt in this paper to prove it, and to explain why it has not rendered itself palpably manifest in practice. Before proceeding to the mathematical demonstration, it will be well to recall to mind the definitions of some terms employed by writers in mechanics and thermodynamics. The actual energy of a moving body, as defined by Rankine, is the work which it is capable of performing against a retarding resistance before being brought to rest, and is equal to the energy which must be exerted on the body to bring it from a state of rest to its actual velocity. The value of that quantity is the product of the weight of the body into the height from which it must fall to acquire its actual velocity. * Vol. I, chap. x, [§ ] 4, p. 312.

Jan 1, 1878

By Oswald J. Heinrich

The responsibility resting upon the owners and managers of mines where fire-damp is generated, renders it a matter of imperative duty that a frill and correct statement of any explosion that occurs should be given to the public. But such a statement must be based on the testimony of impartial eye-witnesses or trained experts. Then a sad experience may result in the adoption of effective preventive measures. In the absence of any official and professional body of mining experts in the State of Virginia, the writer desires to submit to his professional brethren of the American Institute of Mining Engineers an account of an explosion which recently took place in a colliery under his management, and earnestly desires a thorough and impartial discussion on the Fats submitted. Description and Plan of the Mine.—The "Grove" shaft is situated at the nearest point 825 feet from the last old workings upon the Midlothian property, south of the old Pump shaft works. (See Plate 111.) The shaft was sunk by the former company, some thirty years ago, to the depth of 622 feet. An incline over 230 feet long, starting in a northwest direction at a depth of 105 feet above the shaft bottom, had been driven to explore the coal on the dip. A return of very small dimensions had been driven round the shaft on the south side, entering the upcast chamber. With the information obtained from the former company that a seam of coal about four feet thick, at a depth of 490 feet, had been found, and with the information obtained by the present proprietor, R. T. Burrows, of Albion, N. Y., by means of two boreholes on the dip west of the old shaft, in both of which workable seams of coal at various depths had been ascertained, the clearing out and thorough retimbering of this shaft were commenced in March, 1873. Borehole No. 1, at a depth of 4773 feet from surface, revealed a seam of coal. This borehole was afterwards carried to a depth of 1140 feet to the granite, without finding any other seam of coal. Borehole No. 3, at a depth of 608 feet, revealed the first coal-seam, 14 1/2 feet thick; at 633 feet, the second, 12 feet thick; at 662 feet the third, 1 foot thick, and at 692 feet the fourth, 43 to 5 feet thick. The borehole was stopped at a depth of 715 1/2 feet.

By Edwin M. Chance

During the past 10 years, the safe and efficient lighting of the coal mines of this country has received an ever-increasing amount of attention. Several States have passed laws attempting to regulate the type of lamp to be used and the nature of the fuel to be burned, and the mining departments of coal-mining States have generally shown a keen and intelligent interest in this subject. The passage of the recent Employers' Liability Act in Pennsylvania has made it necessary for many coal-mining companies to take out liability insurance, and the companies underwriting such insurance have made it desirable for the insured to permit the use of none but illuminants of established worth. While these conditions have not obtained for a sufficient length of time to permit the statement that the illumination of coal mines by portable lamps has been standardized, still, considerable progress has been made and the direction of future practice in this branch of coal-mining technology is very evident. Under these conditions it seemed that a review of the methods now used in coalmine illumination, together with a brief consideration of the principles underlying these methods, might be of some interest. Miners' lamps may be divided into three classes: The open light, the electric cap lamp, and the flame safety lamp. It will be desirable to consider each of these classes separately, as each has properties peculiar to itself and one class is hardly comparable with another. In this country, without question, the open light is the most generally used of all miners' lamps. This fact is explained by the relative freedom of a large proportion of our mines from gaseous conditions, and by the admirable systems of ventilation installed in those that show a tendency toward such conditions. In the metal mines, the miner's candle has had and still has considerable vogue. Because of the small amount of ventilation usually supplied in metal mines, the freedom of the candle from any tendency to produce noxious gases or offensive odors, and the small amount of air it consumes, are valuable assets, while, because of the light color of the rocks in which workings are driven, the meager light is not a serious handicap.

Jan 1, 1918

By G. A. Vissac

In the presentation which follows, wash-ability curves, such as are commonly used in making studies preliminary to the cleaning of any coal or to the concentration of any mineral, have been reduced in each instance to a single straight line; thus all the most important characteristics of the coal or mineral are represented in a form more advantageous than that in which such data usually are shown. To obtain consistent results, float-and-sink data must be based on a single definite narrow size range, which may be designated "a coal unit." It will be shown that such units, each embodying a different size range, can be grouped to form what may be termed "a composite coal." A three-dimensional presentation will emerge, which will closely identify the coal, illustrate its characteristics in a new manner and explain many obscure facts. Float-and-sink Tests For the preliminary study of any cleaning or concentration problem, or in the control of any operation, float-and-sink tests must be made. The results of these tests are grouped in tabular form and then illustrated in various systems of curves; but if such a graphic representation is to have the utmost practical value, it must offer at least the following advantages: (I) It must be easier to read than the tabular results, and (2) it must be easy to plot, check and interpolate. The first requirement will be attained by reducing the number of curves to a minimum, and the second by some system of representation that will use only straight lines. Of the many washing curves now in use, only the "recovery curve," often known as the "composite curve"—a somewhat misleading term—will be considered; Any point on the recovery curve will show what percentage of weight of clean coal can be recovered when the mineral is washed at a certain specific gravity. As an example, the tests listed below Fig. I are illustrated in the drawing by a curve obtained by plotting (I) as abscissas the ash content of the coal recovered and (2) as ordinates the corresponding percentage of refuse discarded; but, in general practice, instead of writing down that weight, it is customary to set down its complement, which is the corresponding weight of coal recovered. From this curve can be deduced the information necessary for the solution of most practical problems. New Form of Graphic Presentation The resemblance of the recovery curve ill Fig. 1, or, for that matter, the recovery curve obtained in common practice! to a Power curve is apparent. The general equation of such a curve is Y = axn, where n is negative. Taking logarithms: log y = a + n log x. Using a logarithmic scale, the equation of the recovery curve will be Y = A + bX. On this logarithmic basis! the recovery graph will be a straight line, using the same variables as in Fig. I; namely, the ash con-

Jan 1, 1942

By E. Teghtsoonian, K. G. Davis

THE preparation of cobalt crystals offers problems: on cooling through 400°C a phase transformation takes place whereby the structure changes from face-centered cubic to the low temperature close-packed hexagonal form. There are a few references in the literature which describe the preparation of cobalt crystals for magnetic work1,&apos; where melt-solidification methods were used. Reasons will be given why such methods were found unsuitable for our purposes. The following techniques were tried: 1) Solid state methods. Any mechanical shaping of tensile specimens would lead to uncertainty with regard to residual strains. With this in mind, following Kaa, strain-anneal and grain growth techniques were extensively investigated. In no Case were useful single crystals obtained. The transformation boundaries, which are crystallographically similar to twin boundaries, are probably extremely stable and inhibit the grain growth. 2) Growth from the melt. Normal melt-solidification methods were tried, using recrystallised alumina crucibles, and also a osoft moldo technique in which cobalt rod was packed in alumina powder. Trouble was encountered with gas evolution on solidification of the melt, giving porosity. Some adhesion of cobalt to the alumina also took place. Only a small proportion of the runs gave single crystals. 3) Zone-refining. Much the best results have been obtained using an electron-beam floating zone refiner. The refiner, based on a design by Calverly et Al .5 had a single-turn tungsten filament. It was operated at 600 v with an emission current around 45 ma. Commercial cobalt rod 1/8 in. in diam was given one pass at a rate of zone travel normally 25 cm per hr, under a vacuum approximately 10-5mm of Hg. Over 50 pct of the runs gave long sections of single crystal. Crystals up to 2o Cm long with good uniformity of cross section and straightness have been grown in this way. Increase in the length of the molten zone resulted in higher single-crystal yields, but control of zone stability was reduced. Sub-boundaries in the zoned crystals were few, and Laue X-ray spots were sharp. The success of the method is believed to lie in two factors, namely i) the absence of crucible restraints during the transformation, and ii) extreme axiality of heat flow during cooling. The axes of the zoned crystals were clustered around the [ 1010] pole, the pole of the basal plane being at least 60 deg from the specimen axis. Crystals grown at lower rates of zone travel showed the same orientation range, Fig. 1. This orientation is similar to that for other hexagonal metals grown from the melt, which is a little surprising when the mode of formation of the hexagonal phase is considered. The preferred orientation is probably caused by anisotropy of heat conduction, i.e., that crystal which can most effectively conduct heat away from the transformation interface will be favored. Fig. 2 shows the area on a standard cubic stereo-gram in which there are no poles more than 60 deg from one of the four < 111> directions. This area

Jan 1, 1962

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&apos;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.&apos; 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 George A. Koenig

This new departure in assaying is the outcome of a long-felt desire to shorten the time required in muffle-assaying, as well as to do both crucible- and scarifi cation-work in one furnace. The first object in view was the gold-assay, which must always be a combination of the crucible- and muffle-work. The large lead buttons consume much time in their reduction by scorifying and cupelling. The Hoskins gasoline furnaces have been a great convenience, for years past, in that class of practice, where only one assay was required at a time. But even with them I found myself hampered, since the crucible-furnace only takes one crucible at a time, and my practice implies always duplicate assays. Another difficulty was to get the muffle up to the necessary heat and to maintain it at that heat. Whecever I had pumped myself into perspiration and out of breath, the question presented itself, " Is the muffle necessary to do this work properly ?" Hartmann and Plattner and all their blow-piping disciples have shown that very good results are obtainable by playing a direct flame upon the work-lead. Could this be done on the regular muffle-assay scale ? I placed a cupel upon a fire-brick, surrounded it with charcoal, and then played upon it with a Bunsen gas blow-pipe. The result was encouraging. With some care a 2.75-inch scorifier charged with 0.1 A. T. of a 100-ounce ore could be melted down and scorified without any apparent loss. I thought then of constructing a furnace with four blow-pipes in a row; but the combination of gas and charcoal seemed unpractical. Instead, I placed an F crucible, bottom up, in a Hoskins crucible-furnace. Upon this support I placed a charged scorifier. The rapidity with which a very refractory charge melted and scorified was simply amazing to me. Then a cupel was put in the place of the scorifier, the lid was moved sideways, and a blow-pipe was

Jan 1, 1899

By A. Lee Barrett

Mine power systems are quite different in many respects from those usually found in industrial plants. Wide areas are served, usually by a circuit which is connected continuously throughout the mine. In some mines one circuit may run for several miles. There are usually a small number of branch circuits involved considering the areas covered. In all mines circuits are sectional-ized at approximately 2500 ft by means of switches. All, or at least most branch .circuits, are sectionalized by manual switches. In some mines automatic sectionalizing gear is used to give automatic overload protection at various strategic points in the system. However at the present time this practice is by no means general. Circuit hazards in mine electric systems are much greater than those encountered in industrial installation. Falls of roof or coal form a prominent hazard which may break the wire and may cause ground faults or partial ground faults. Ordinarily electric cables in mines cannot be insulated, therefore a fall can easily cause a short circuit. The humidity in most mines is greater than 95 pct and at many points the floor is wet and water may be dripping from the roof over insulators, increasing the difficulties at that point. All electrical circuits must be contained in the mine entries and space must also be provided for moving equipment and men. Consequently, because of the proximity of the power circuit to the locomotives and other moving equipment a considerable hazard is introduced. Mine haulage track is not always good so that wrecks are not unusual. A wreck frequently does considerable damage to the power circuit. A ground fault frequently results in heavy arcing which may be sustained. If the damage to the circuit is mechanical it may mean that a trip of coal has wrecked and a great deal of coal dust could be thrown into the air as a result of the wreck. The arc resulting from the ground fault could ignite the coal dust and a mine explosion would result. A continued ground fault, even if high in resistance, also may ignite the coal which may be on the bottom of the entry and a mine fire may result. The fire hazard is one of the most serious hazards in any coal mine. Since the mine circuit is completely interconnected, any power interruption resulting. from a fault seriously affects the whole operation. Unless the mine is completely sectionalized the whole mine will be shut down until the fault is located and the proper switches are opened to isolate the fault; even then large areas may still be without power if they are supplied by a single power circuit which may be opened in isolating the fault. Further, mine power is usually supplied from a relatively small number of substations and the fault may be on a stub feed circuit, in which case power cannot be restored until the fault has been cleared. Practice varies widely with respect to placement of substations. Usually they will be spaced from I to 2 miles in 500V opera-tions, and at I mile intervals or less, in 250V operation. Actual mining operations govern substation placements and no general rules can be followed.

Jan 1, 1949

By Donald W. Scott

Generally speaking, there is nothing very difficult about taking good microgrztphs of photogenic thin sections or grains with a petrographic microscope-camera setup. However, sometimes it is desired to show some detail that cannot be illustrated satisfactorily by the usual micrographs taken with parallel polarized light, with crossed nicols, or even with two micrographs. A simple procedure giving good results has been used at Battelle Memorial Institute for subjects falling into this classification, and it is believed to be of interest, especially to research people who must sell a point to executives through the medium of well-illustrated reports. The following problem illustrates a typical application: It is desired to photograph a thin section of an iron ore to illustrate the character and association of the iron oxides and the individual quartz crystals. A magnification of 75 dia. is acceptable. A micrograph of the field in question (Fig. Ia) was taken with parallel polarized light. Due precaution was taken to provide critical illumination, correct exposure, a sharp focus, a good darkroom technique, and other essential conditions. It illustrates correctly the iron oxides, but it fails to show the individual quartz crystals. A micrograph of the identical field (Fig. Ib) was taken under the same precise conditions, but with crossed nicols. It gives a better idea of the character of the individual quartz crystals but is likely to be misinterpreted unless accompanied by a lengthy descriptive note. This micrograph suggests that the centrally located, large black area is composed entirely of iron oxides. That this&apos; is an incorrect interpretation is evident by reexamining the micrograph of Fig. Ia. The correct interpretation is that the dark area contains quartz crystals oriented with their optical directions parallel to, or nearly parallel to, the vibration directions of the polarizer and analyzer of the microscope. Thus, the executive, or anyone who had not done the work personally, would get no more than a fair interpretation, even if two micrographs were included; and in the interests of both brevity and clarity, one micrograph usually is more desirable. Exactly how many quartz crystals occur in this region cannot be told from the two micrographs, and a printing of the two negatives in register would likewise not show the detail desired. Thus, it is evident that some subjects cannot be satisfactorily illustrated by the usual procedures. In photographing Fig. Ic the light was subdued and, during the entire exposure of 75 sec., the analyzer nicol was rotated uniformly in its mounting from a crossed position to 45° uncrossed position to introduce the desired amount of contrast in the various individual quartz crystals. The true reproduction of the character and association of the iron oxides, and the additional structure and detail in the quartz areas, is apparent. It might be

Jan 1, 1949

By William C. Marshall, Frank G. Norris

The term "total operation" is meant to include problems that cannot be answered from the standpoint of either the blast furnace or the open hearth separately but must be studied by considering the interrelations of these two processes. There are other ways of expressing this idea, such as reference to the blast furnace and the open hearth as an integrated process or by emphasizing the interrelation and interaction of the two processes. Much progress has been made in metallurgy and other fields by breaking complicated processes and reactions into simpler parts and studying each of these intensively. This intensive study frequently is done under the controlled conditions of the laboratory experiment. The entire process is understood better by this specialized study of each of its parts. This procedure is so satisfactory that an understanding of unit operations is a fundamental requirement of chemical engineering. Much discussion of the open-hearth process is in terms of one heat or one furnace. By this is meant that the conclusions apply to one furnace, wherever it may be. Furnaces seldom occur singly; they are located in groups and these groups are located in steel plants having characteristic blast-furnace equipment. Problems that are affected by the number of furnaces operating, by the number of blast furnaces in the plant and by the fact that the open- hearth shop is dependent on the bla furnace capacity rather than on its o needs for the amount of iron available among those which, in contrast to "u operations," we have chosen to call "to operations." Many of these problems, such as cha ing delays and the general mechani problem of material handling, are familiar that merely to define " total op ations" brings them to mind. These pr lems are of such importance that alrea they have received careful thought 2 study and probably will merit furt study. As will be shown later, these mechan problems are so intimately related metallurgical problems of total operati that the effect of certain changes cannot ascribed with certainty to either a mech ical or a metallurgical cause entirely. Although the problems coming under general term of "railroading" are inclu in the problems of total operations, &apos; others are selected for the discussion of paper, One of these is strictly a problem composition; the other is strictly a prob of tonnage production. The problem of phosphorus is pres whenever basic open-hearth slag is used the blast-furnace burden. This practice not secured universal acceptance chi because of difference in preference for h manganese or low-manganese pig iron hjgh-manganese (2.00 per cent) iron is to made, open-hearth slag as a source manganese is usually cheaper than m

Jan 1, 1943

By Fred Bond

THERE is acute need for a method that will measure the size distribution of finely di-vided materials, particularly when the par-ticle sizes are smaller than the openings of the finest screen cloth regularly available for testing. Several methods and types of apparatus are in common use, but none are entirely satisfactory for all purposes. The commonest methods are microscopic grain counts, elutriation by liquids or air, and sedimentation. Valuable results have been secured by air elutriating devices, typified by the Haultain Infra-Sizer and the Pearson Air Analyzer. These are especially useful in obtaining sized fractions that can be examined and analyzed separately. They are particularly advantageous because the sizes of the sam-ples produced are adequate for a consider-able amount of subsequent manipulation and testing. The sedimentation methods, such as the Wagner and Klein turbidimeters, and the sedimentation balance, do not deliver sized fractions, but they do provide a means for reasonably rapid comparative determina-tions of fineness and surface area, which are important in many industries. The sedimentation balance consists essen-tially of a balance pan suspended in a liquid that contains falling particles. These are weighed as they settle onto the pan, and the time rate of settling is determined. The size distribution is computed from the set-tling rate. The balance appears to be in-herently more accurate than any of the other methods, and it has served a useful purpose in the study of numerous problems, but there have been limitations which have re-stricted its scope of application. Because of the essential simplicity of the method, it was felt that intensive investiga-tion might lead to modifications that would make it a valuable tool for the operators in industries that require precise information regarding the results secured from grinding equipment. A large number of size-distribu-tion determinations below 200 mesh were required in connection with a particular research problem in fine grinding. The sedimentation balance was used, in this investigation, and a technique was gradually developed that ultimately gave good results. A serious difficulty appeared, early in the work. It was discovered that less material always settled on the sedimentation pan and more on the bottom of the containing jar than could he accounted for by calculation, and also that the material that settled to the bottom of the jar outside the edges of the pan was considerably finer than that on the pan. This segregation was so great that the dis-tribution obtained for the finer sizes was obviously very much in error; material ground to about the degree of comminution of cement might have only 60 per cent of the calculated weight actually settling on the pan, and the error increased with the fine-

Jan 1, 1939

Discussion of the paper of W. R. Shimer and F. O. Kichline, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 81, September, 1913, pp. 2361 to 2377. ALLERTON S. CUSHMAN,* Washington, D. C.:-I have been much interested in Mr. Shimer&apos;s valuable contribution. The apparent fact that the oxides of certain metals which are not reduced by hydrogen per se, are reducible when the oxides are dissolved in iron in small quantity, is brought out for the first time, and is worthy of the careful attention of investigators. The Ledebur method has been subjected to considerable criticism, owing to the alleged fact that it did not measure the oxygen combined with impurities. Personally I have found the method extremely helpful in spite of the minute quantities of oxygen with which it deals. Mr. Shinier points out that the highest oxygen he obtained by over-blowing was 0.074 per cent., while the minimum quantity in a properly finished steel was in the neighborhood of 0.02 per cent. The Ledebur method is used as a constant check on the quality of heats made in practice under my direction. In dealing with a very pure commercial iron, we should expect to find and would find difficulty in galvanizing sheets made from a heat running 0.07 per cent. oxygen. In fact, we do not like to have the oxygen rise above 0.03 per cent. I am inclined to agree with the author that excessive oxygen leaves a bath of metal in a very short time, but nevertheless I believe it takes only a very little combined oxygen to begin to make its presence felt in the pickling and galvanizing department, when sheet metal is the product manufactured. As Mr. Shimer points out, the higher the carbon, the lower the oxygen danger, and it is partly for this reason that the manufacture of carbon-free metal in the open-hearth furnace has to be so very carefully watched and controlled from the furnace through to the finished product. It is quite possible that, there is a critical temperature of dissociation between iron and oxygen, although the critical points may vary in baths of different carbon content. Unfortunately, the accurate determination of the temperature of a molten bath at the time of pouring or teeming is a very difficult matter. For a long time I have been wishing that there were some reliable data which would indicate the effect of the tem-

Jan 12, 1913

By R. P. McLaughlin

Discussion of the paper of R. P. McLaughlin, presented at the San Francisco meeting, September, 1915, and printed in Bulletin &apos;No. 108, December, 1915, pp. 2313 to 2319. M. E. LOMBARDI, Berkeley, Cal.-Mr. Bell, I would ask you to state before the meeting what you said to me the other day, about the final recovery of oil from oil sands that have become inundated with water. A. F. L. BELL, San. Francisco, Cal: In stating my opinion, I give it with certain qualifications. In the Kern field, and possibly in some others, I think we will eventually get all the oil out, whether the water comes in or not, since it is peculiarly constructed, being in the form of a partial dome. In 1909, while I was field manager of the Associated Oil Co., I installed some large air compressors to handle the water. At that time the oil had migrated to the higher and more shallow portions of the field, because the water had inundated the deeper sections. The result was that the shallow districts within the center of the dome were in many, cases producing as much or more oil per well than the deeper wells. And in the inundated sections the water had slowly spread over large areas, so that nothing but water was pumped from them. Under these conditions, we decided to pump the wet. well with air, and installed four 2,000-cu. ft. compressors. The air was compressed and forced into the wet wells at, about 250 lb. pressure. Shortly the inundated district that had produced almost all water and only about 150 bbl. of oil a day increased its production to over 2,000 bbl. of oil per day. It was not-long before, we noticed that the production of the shallow territory was falling off to such an extent that in many cases the wells were abandoned; at the same time the area of the water-inundated district was greatly reduced, showing that when the water pressure was reduced the oil migrated back to the lower depth. The wells which at first had had the air jets put into them finally produced so much oil that we had to take the &apos;air jets out and return to the use of the beam pump, because it is not commercially feasible to pump, an oil of 14° gravity with air. To handle such oil profitably by air, it must carry with it 50 to 90 per cent. of water. The results have led me to believe that oil monoclines, where there is a gradual rise to a certain point, or in plunging anticlines, even though water gets into oil sands, eventually we get the larger percentage of the oil. However, the man with a small acreage in the deeper sections may find some morning that his oil has gone, another man in some higher portion of the district having gotten it.

Jan 12, 1915

By David Turnbull

In most reactions involving solids the transformation kinetics may be represented by the combination of two processes —those of nucleation and of growth. For example, Mehl and his coiq-orker in their studies on the transformation of austenite to pearlite in steels have been able to describe the kinetics in terms of the rates of nucleation and of growth. By micrographic examination of their specimens they determined the nucleation rate (rate of appearance of pearlite colonies) as a function of time, of percent transformation, and of temperature. They observed that after an incubation period in which no nuclei are observed, the number of nuclei appearing per unit time per unit of untransformed grain boundary area, increases at an increasng rate with time. When recrystallization rates have been interpreted in terms of rates of nucleation and growth and the rate of nucleation determined, an incubation period followed by an increasing rate of nucleation has also been reported. Among the studies in which this phenomenon has been observed are those of Kornfeld and coworkers3 on cold-drawn aluminum wire, of Anderson and Mehl4 n the recrystallization of aluminum sheet, and of Stanlcy and Meh15 on the recrystallization of silicon ferrite sheet. The existence of an incubation period during which no nuclei are observed does not appear to have been reconciled with the generally accepted Volmer-Becker theory of nucleation in condensed systems. This theory ostensibly requires the rate of appearance of nuclei to be independent of time. Volmer-Becker Theory In order to form a stable nuclcus of a new phase B in a mother phase A, the molecules or atoms of the mother phase must surmount a free energy barrier whose height is determined by the volume free energy change accompanying the transformation and the energy of the surface separating the two phases. The free energy difference between nuclei of various sizes and the molecules or atoms of the mother phase is plotted schematically in Fig I as a function of the radius of the nucleus r. This free energy difference is plotted for two values of the change of free energy per atom, (Jb — ja) accompanying the transformation when the volumes of the two phases are infinite. One of these values of (Jb—Ja) corresponds to a temperature above the temperature To at which the phascs A and B are in equilibrium, and the other to a temperature below To. In order for a nucleus of phase B to be stable at a temperature T² < TO, its radius must be equal to or greater than the critical value r* for which the free energy of formatioil of the nucleus is a maximum, the of phase B having radii equal to or less than r* will be called embryos hfehl and Jetter," in discussing the kinetics of nucleation in solid systems, suppose that embryos of critical size are formed

Jan 1, 1949

By A. Cochardt, D. H. Feisel

HE success of the sintered aluminum powder material (SAP)&apos; in raising the maximum useful temperature of aluminum alloys has stimulated effort in investigating similar systems in which the metallic matrixes have higher melting points. Examples of such systems which have been studied are nickel-alumina,2, 3copper-silica,4 copper-alumina,4 titanium-cerium oxide,5 and 80/20 nickel-chromium,8 cobalt,= and molybdenum7 matrixes with various hardeners. Conventional precipitation-hardened high-temperature alloys are often thermally unstable in service. The original fine particles that are responsible for good strength properties grow in size at elevated operating temperatures, a process termed "over-aging." This growth of precipitated particles causes a gradual loss in strength properties. A previous paperb describes the factors that govern the process of overaging, and estimates the time required for overaging of a nickel-alloy matrix dispersion-hardened by various precipitates such as are found in current high-temperature alloys, and by alumina. These calculations indicate that nickel-base alloys hardened with Ni3Al, Tic, or TiN are quite unstable at 1340" F (727°F). Such alloys should overage within a few hours at that temperature. A nickel-base alloy hardened with alumina, on the other hand, should behave differently. It should not overage appreciably within a thousand years. It was further shown8 that the thermal stability of the oxide-hardened alloy is mainly due to the low solubility of oxygen in equilibrium with alumina in the nickel-base matrix. Since the oxygen solubility is small, little oxygen can diffuse, and structural changes require very long times. This paper illustrates the effects of time and temperature on the structural stability of nickel alloy matrixes hardened by dispersions of Ni3A1, Ni3Ti, Tic, and alumina, and of nickel-chromium matrixes hardened by alumina. Hardness measurements and metallography have been used as a measure of structural stability. EXPERIMENTAL PROCEDURE Using the best information from published phase diagrams,&apos;-l4 compositions of the Ni-Al, Ni-Ti, and Ni-Ti-C alloys were determined so as to have 5 vol pct of precipitate at 1350° F(732°C), the temperature selected to illustrate the effect of time on structural stability. Table I lists the chemical compositions of these alloys. Standard laboratory melting and alloying techniques were used in preparing ingots of the F-Series of alloys. The cast ingots, 1 3/4 in. in diam, were forged to 3/8-in. diam rods.

Jan 1, 1960

By John T. Popp, Jodi A. Rulli, Anthony T. Iannacchione

Anomalous geological features in the coal and surrounding strata of a mine in northern West Virginia have fractured and deformed an inherently weak roof rock prior to mining. Horizontal stresses, as much as six times greater than overburden related horizontal stresses, have induced cutter roof failure. This failure was distinguishable from rock deformation associated with geological anomalies because it was induced by mining. The characterization of these features has allowed for the prediction of zones of unstable roof rock and the determination of failure trends on gateroad stability. Geological anomalies included clastic dikes and a narrow zone of sandstone roof. Clastic dikes, representing intrusions of shale and claystone, were invariably accompanied by local roof rock instability, and often formed the boundaries of roof falls. Shale was the dominant roof lithology except where a small sandstone occurred in the northwest portion of the longwall mining area. The sandstone occurs in two phases: a sandstone-filled channel, 5-m- thick and 60-m-wide, which eroded and replaced the shale roof and the upper part of the coalbed; and a sheet sandstone unit which was crossbedded to interbedded with the underlying shale. Horizontal stresses are naturally relieved through the initiation of cutter roof failure. This failure may extend from a few meters to several tens of meters horizontally, and from a few centimeters to several meters vertically. Orientations of entries and crosscuts has a greater influence on the direction and total length of cutter roof failure at the rib-roof intersection than does the principal directions of the in situ horizontal stresses. Seventy-four percent of the cutter roof failures occurred along the rib-roof intersection. Orientations of cutter roof failure away from the rib- roof intersection were clustered in the north-south direction and may have been influenced by the horizontal stress field.

Jan 1, 1984

By S. F. Radtke, J. A. Snyder, R. M. Scriver

An automatic, continuous casting arc furnace employing a nonconsum-able electrode and a direct current arc has been constructed and operated successfully for titanium. A comparison of the properties of arc and induction-melted titanium indicates that where high ductility, formability, and toughness are required, arc-melted metal is preferable. BECAUSE of the reactivity of titanium metal with all known refractories and the common atmospheric gases, melting of the metal presents numerous problems. It is necessary to provide an inert atmosphere in the furnace as well as a crucible material that will not react with the molten metal, if a ductile ingot is to be produced. Two special furnaces have been developed that meet the requirements and one, the induction heated graphite furnace, has been described in some detail.&apos; Little information is available for sizable units wherein power is applied to the melt through an arc, and the dearth of technical information on such a furnace prompted this report. It has been demonstrated clearly that arc melting produces titanium metal with superior toughness, ductility, and formability. To produce titanium ingots with these properties, an automatic, continuous casting arc furnace has been developed and is described herein. The history of arc melting may be traced to 1800, when Sir Humphrey Davy2 first experimented with Volta&apos;s electric battery and found that light could be produced and an arc formed between two carbon points attached to the cell. The discovery of the arc was followed by the design and construction of an arc furnace by Napier," in 1845, for the reduction of metal oxides. In 1853, Pichou&apos; described a similar furnace, although it was not until the discovery of the dynamo in 1867 that the arc furnace could achieve commercial significance. In 1878, Siemens- esigned the first arc furnace intended for the melting of metals and by 1882 had melted steel and platinum successfully. . This was followed by Moissan&apos;s" classical work with the arc furnace in 1892. W. von Bolton,&apos; in 1905, found that the arc furnace was suited admirably for melting refractory metals. In his work with tantalum, no suitable refractories for retaining the molten metal were found to exist. Together with Otto Simpson, he developed an arc furnace with a water-cooled copper crucible in which tantalum could be melted without contamination. This technique proved eminently successful. In his paper on the preparation of ductile titanium, Krolle first described an application of the von Bolton furnace to the melting of this metal. The

Jan 1, 1952

By Walter O. Snelling

In the course of some experiments more than five years ago, made for a totally different purpose than the investigation of the oil used, I placed a small quantity of a transparent yellow lubricating oil in a bomb-like vessel and heated it to a relatively high temperature. At the end of the experiment I removed the oil from the vessel and was amazed to find that instead of bearing any resemblance to the oil which I had put in, it now had the appearance of ordinary crude oil. The green color by reflected light and the rich red-brown by transmitted light were so unmistakable as to at once lead to further investigation. I subjected the material to fractional distillation, and the surprise which I experienced at the appearance of the oil, changed to amazement when I found that it yielded, on distillation, 15 per cent. of gasoline and 30 per cent. of burning oil, and that its constitution resembled crude oil quite as much as did its appearance. Furthermore, the gasoline and kerosene distillates which it yielded were of a clear water-white color, entirely without treatment with acid or alkali, and were entirely free from the odor familiar in "cracked" petroleum distillates. The result of this experiment was quite too remarkable to be credited without further confirmation, and I at once filled the vessel with some of the same oil that I had used before, and again heated to about the same temperature that I had previously used, and for the same period of time. Upon opening the vessel and removing the contents I found, not the material resembling crude oil that I had obtained before, but apparently only the same oil that I had put in, somewhat darkened in color, but nevertheless far different in appearance from the material obtained in the previous experiment. Evidently some condition existed in the first experiment that had not existed in the second test, and here began a series of tests in which I sought by the change of one variable after another to arrive at the identical conditions which must have existed in the first experiment. Only the fact that the bottle of heavy oil used in the first test was still in its place,

Jan 1, 1915

By Benjamin Talbot

The problem of segregation and cavities in steel ingots is a subject which has given and is still giving metallurgists, engineers, and operators matter for serious consideration. This question has come more into prominence lately in the United States, due largely to the desire of railroad engineers to secure a better rail than they have obtained ill the past, as the service they demand is increasing in severity; and no doubt manufacturers will be able to meet what is required of them. The rails here are as good as those made in other countries, but the conditions of service and the extremes of climate are more Revere and consequently more breakages occur. Various reasons have been advanced to explain why rails may not be as good in quality to-day as in the past. Some engineers consider that modern methods of manufacturing, designed chiefly to obtain large output, tend to reduce the standard of excellence of more deliberate methods. Others think that 4-ton ingots are worse than those of 2 tons. Again, it is stated that the 100-ton heat in one ladle is too large, and is a step in the wrong direction in casting. My experience upon the question of the size of the ingot is that in rolling rails of from 85-to 100-lb. sections, the range of ingot is only practically such that the difference in the size does not help in the question of segregation, cavities, or blow-holes. I call attention to two ingots from work done at Pencoyd, Pa., 16 years ago. These ingots were bottom-poured, cast at the same time from the same center-runner, the one being 20 by 24 in. and the other 13 by 16 in. in size. The steel was acid open-hearth, and contained C, 0.43; P, 0.062; S, 0.069 per cent. At the same place in each ingot where seg-

Jan 1, 1914