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By V. L. Elliott, C. L. Meyette

The conditioning of semifinished steel products such as billets, blooms, and slabs to remove surface defects before further processing to finished products is a necessary accompaniment to steel mill rolling operations. A knowledge of the kinds of defects which occur and of the conditions in melting, teeming, and rolling that may lead to their occurrence is favorable to the production of quality products. Surface defects may be classed as either of mechanical origin such as those that occur in the heating and rolling operations and include breaks, tears, guide marks, mechanical laps and the like, or they may have been in the ingot before heating and rolling. Examples of the latter are ingot cracks, blow-holes, scabs, and inclusions which lead to the numerous known types of seams and surface flaws. Most of the common types of surface defects and methods for their identification by visual examination or by the aid of macro-etch tests are well known. The conditions which caused their formation are also appreciably understood and this knowledge has been instrumental in the establishment of methods for metallurgical control. There are, however, defects of doubtful origin. In any endeavor to trace the causes for their occurrence, the question of first concern is: I. Whether they were formed in the rolling procedure. 2. Whether they existed in the ingot prior to rolling. In the case of semifinished products which are rerolled to finished products there is also the question of whether they were formed in the primary or in the secondary rolling. In metallurgical laboratories where numerous or routine examinations of the quality of rolled products are made over the course of time, there will doubtless be many puzzling cases of defect origin. Microscopic examination of the defects may, however, reveal a characterizing condition that can be used to classify them broadly with respect to their origin. Such a condition has been observed and, after detailed investigation, is described here with the thought that it may offer a usable and relatively simple solution to a bothersome problem. Basis For Classifying In this discussion the term "mechanical type defects" will be used to designate those that have occurred as a result of the rolling operations such as in rolling from the ingot to billets, blooms, or slabs or in rerolling to finished products. The term "steel type defects" will be used to designate those that were present in the ingot prior to primary rolling or that were in the semifinished product prior to secondary rolling to finished product. The basis for distinguishing between the two types of defects lies in the relative degree of subscale formation surrounding them. Subscale is defined1 as a zone of

Jan 1, 1949

By R. Grierson, L. J. Bonis

The high-temperature Strength oF TD nickel has been observed to be dependent upon the previons thermal and mechanical history of the material. Variations in both the level and the anisotropy of strength have been observed. 01 this paper- these variations are correlated with the storing of annealing resistant elastic strain energy in the matrix of the TD nickel. An x-vay line -broadening tecknique is used to measure the maLrTis elastie strain. THE inclusion of a finely dispersed second phase into a ductile matrix has long been recognized as an extremely effective method of strengthening the matrix both at high and at low homologous temperatures. It has been found, however, that the factors which determine the high-temperature strength are not the same as those which are important at low temperatures. Below 0.5 Tm the size and distribution of the second phase particles are of prime importance in determining the strength,')' while above this temperature the strength is mainly dependent upon the previous thermal and mechanical history of the alloy,3-7 This paper is primarily concerned with explaining the response of the high-temperature mechanical strength of one of these alloys (DuPont's TD nickel) to various thermo-mechanical treatments. It will be shown that this response is not associated with the occurrence of any form of dislocation substructure within the matrix of the alloy. It has been found, however, that a correlation does exist between the elastic strain level in the matrix and the previous thermomechanical history of the alloy and that the observed changes in elastic strain level parallel the measured changes in high-temperature strength. It therefore must be concluded that variations in high-temperature strength are a direct result of the variations in elastic strain level. MATERIAL TD nickel contains approximately 2 vol pct of Tho2 in an unalloyed nickel matrix. It is formed, as a powder, by a chemical technique and this powder is compacted to form ingots which are then extruded to give 21/2-in.-diam rod. Rod of smaller diameter is prepared from the as-extruded rod by swaging. In the studies reported in this paper, 1/2-in.-diam rod was used. This rod received an anneal of 1 hr at 1100°C prior to being used in any of these studies. EXPERIMENTAL TECHNIQUES Two methods were used to examine the structure of the nickel matrix of the TD nickel. These were: 1) transmission electron microscopy; 2) the analysis of the position and profile of X-ray diffraction lines obtained using the nickel matrix as the diffracting media. To prepare thin foils for electron-microscopical examination, slices of TD nickel approximately 0.050 in. thick were cut from the as-received 1/2-in.-diam rod. These were then chemically polished down to 0.045 in., rolled to 0.009 in., given a predetermined heat treatment, and thinned, using a modified Bollman technique, to provide the foils for observation. All observations were carried out at 100 kv, using a Hitachi HU-11 electron microscope. Specimens of the undeformed rod were prepared by grinding down the 0.050-in.-thick slices to approximately 0.015 in. and then thinning chemically and electrolytically to give the thin foils. The X-ray specimens were prepared by rolling 0.375-in.-thick rectangular blocks down to 0.075 in. The surfaces of the rolled material were ground flat, chemically polished to remove the layer disturbed by the grinding, and given a predetermined anneal in an inert atmosphere. They were then ground lightly to check their flatness and given a final chemical polish prior to being examined. The X-ray diffraction line profiles were measured using an automated Picker biplane diffractometer. A special specimen holder was built to allow a more accurate and reproducible positioning of the specimen. The line profiles were determined by carrying out intensity measurements at intervals of either 1/30 deg or 1/60 deg over a range of 3 deg on either side of the nickel peaks of interest. A piece of pure nickel which had been recrystallized to give a large grain size was used as a standard to give the X-ray line profile generated by a strain-free matrix. The analysis of the X-ray diffraction line profiles is a modification of that due initially to Warren and Aver-bach8and has been described elsewhere.3 This analysis gives a measurement of two parameters associated with the structure of the nickel matrix. These parameters are: 1) the size of the coherently diffracting domains within the nickel matrix; 2) the magnitude of the elastic strains in these domains. Both of these parameters are first determined in terms of a Fourier series. These series are obtained from other Fourier series which describe the measured profile of the X-ray diffraction lines. Thus, for both the coherently diffracting domain size and the elastic strain level, it is possible to plot Ft (the Fourier coefficient) against t (the term in the Fourier series), where t can be expressed in terms of a distance L and the Fourier coefficient Ft(S) (associated with elastic strain level) can be expressed in terms of the root mean square strain (e2)1/2. Thus a plot of (F 2)1/2 vs L can be obtained. Plots of this type are shown graphically in Figs. 6 and 8. Interpretation

Jan 1, 1968

By A. L. Holley

The first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plunlbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth's surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, onehalf of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1879

By Michel Dupuy, Daniel Calais

The study of self-diffusion of plutonium in E phase has been carried out by the welded couples method. The tracer used was puZ4O which is detected by its X-ray emission (conversion lines of uranium which are computed between 13 and 21 kev). Intensities were measured with a scintillation counter. Each layer was removed in a direction parallel to the original interface with a grinding machine and a thickness measured with a pneumatic comparator. The concentration-penetration curves obtained were corrected for the effect of heating time from room temperature to annealing temperature and for the expansion due to phase transformations of plutonium. They were analyzed by the generalized Gruzin method. Self-diffusion of plutonium in E Phase is very fast cm per sec between 500" and 620°C) and the diffusion zones are 2 to 3 mm wide for annealing times ranging from 30 min up to 10 hr. The Arrhenius law gives the temperature dependence in the form: From the point of view of self-dqfusion, PUE phase falls into the anomalous bcc metals category (Tip , Hfp, Zrp, Uy) with a low-frequency factor and an activation energy lower than those provided by standard correlations. No theory proposed hitherto to explain these anomalies (influence of dislocations, of extrinsic vacancies bonded to inlpurities, of bi-vacancies) can clearly explain the self-diffusion coeffzcients of plutonium. DIFFUSION in bcc metals is a present-day problem. A recent symposium (Gatlinburg, 1964), followed by a book,' has been devoted to it. A great many experiments seem to show that diffusion in certain bcc metals obeys unexpected laws. The activation energies measured are sometimes strangely low (B hafnium, y uranium). For certain metals (0 zirconium, p titanium) the curves of log D (D = diffusion coefficient) as a function of 1/T (T = absolute temperature) are not linear. The frequency factors Do, which are of the order of 1 sq cm sec-' in fcc metals, vary from 1 to 10~6 sq cm sec-'. Various theories have been put forward to explain these anomalies; none is yet satisfactory. We wished to introduce a new experimental result by studying the self-diffusion in c plutonium. This allotropic phase, stable from 475°C up to the melting point (640°C), is in fact bcc. Unfortunately, nothing is known of the characteristics of the point defects in this phase, which limits the scope of the hypothesis which can be made about the mechanism(s) of self-diffusion in plutonium. 1) EXPERIMENTAL METHODS 1) Principle. We used the welded couple method. The two pellets of the couple initially have different 240 isotope contents (X emitter). After diffusion, the concentration/penetration curves are drawn up by the generalized Gruzin method. 2) Gamma Spectrography. The metal used in our study is plutonium, either low in puZ4O (isotopic content 1 pct) or high in puZ4O (8 pct). The latter also contains plutonium 241 (-1 pct) and 300 ppm of ameri-cium produced by the reaction Pu2U-AmM1 + 8-. The emission spectra of these two plutoniums placed in leak-tight vinyl bags have been studied by y spectrograph~. The detector is a thin crystal of thallium-doped sodium iodide. The activity of the plutonium rich in 240 is about twice that of the plutonium low in 240 in the energy band of 17 kev (L conversion lines of uranium); this band was used in these measurements. 3) Preparation and Examination of the Diffusion Couples. Diffusion couples were made from plutonium with a high and low PU"' content. Pellets (6 6 mm. thickness 3 mm) mounted on a polishing disc with ground parallel faces were polished mechanically on both sides. In this way, pellets with two parallel faces were easily obtained. The polished pellets were joined by a 6 phase anneal (420°C, 1 hr) in a small screw press (pressure of 20 kg per sq mm cold); a centering ring enabled the two pellets to be pressed coaxially. The couples then were subjected to the diffusion treatment by annealing in the E phase in sealed silica ampules in argon at atmospheric pressure. The annealing temperatures and times are given in Table I. The couples were encased in a mild steel ring, the joint interface being thus parallel to the ground face of the ring. The diffusion couple/ring assembly underwent successive abrasions by means of a magnetic plate grinder. The thickness of the abraded layer was measured with a Solex pneumatic comparator when it was less than 0.1 mm (accuracy 0.2 p) or with a mechanical micrometer (accuracy 3 p) for passes of the order of 0.2 mm. All these operations were done in glove boxes, as plutonium is particularly toxic. After each abrasion we determined the emission spectrum of the ground face. The emissive surface is defined by means of a diaphragm 3 mm in diam. We noted more particularly the X activity in the 17-kev

Jan 1, 1969

By Raymond Mancha

When calculating the pressure-volume characteristics of projected mine-ventilating circuits by orthodox methods, certain basic assumptions are required in order to employ the various available empirical data. It is assumed, for example, that the mine air is an incompressible fluid subjected to isothermal flow, an assumption sufficiently accurate for practical purposes since pressure and temperature differentials are small throughout the average circuit. A more erroneous assumption, however, is that all air is accounted for as it travels throughout the mine. No attempt is usually made to evaluate stopping leakage as it occurs; instead, the air volume required at the last crosscuts is assumed to enter the mine, travel the various intake air courses intact, sweep the workings and travel out by the return air courses to the point or points of exit from the mine. Actually, there is a leakage of air from intake to return at every stopping, the quantity of this leakage depending upon the tightness of the stopping and the pressure difference across the stopping. Unfortunately, a lack of empirical data and knowledge of the condition of individual stoppings makes an exact analysis of underground stopping leakage impossible. Generally, leakage is most severe through the old stoppings outbye the circuit. These are also subjected to higher pressure differences than the newer inbye stoppings. Therefore the circuit air volume diminishes at a decreasing rate progressing from outbye to inbye the circuit. Consider a simple mine circuit consisting of one intake and one return air course, each of equal and uniform section area and interconnected at regular intervals with crosscuts equipped with stoppings. At any point X inbye the circuit the air volume q on the intake air course equals that on the return air course and decreases with diminishing rate from outbye to inbye the circuit between the limits of Q1 completely outbye and Q completely inbye. Such a volume change is represented by curve a, Fig. I, which is computed with the aid of the equation q = Q1- (Q1- Q)(X + L)N. This equation results from the general algebraic equation of form q = k, — kXN after solving for kl and k with the knowledge that completely outbye X = o and q = QL, also completely inbye X = L and q = Q. Curves a, b and c, Fig. I, show values of q as ordinates versus values of X as abscissas, for values of N equal to 0.50, 1.00 and 2.00, respectively. Distribution of underground stopping 1eakage directly affects the air-volume distribution along the circuit, which in turn determines the circuit pressure gradient. To deliver any required air volume inbye a circuit or portion thereof requires a higher circuit-pressure differential if stoppings leak than is necessary with tight stoppings. Every mining engineer engaged in the analysis of projected mine-ventilation circuits is therefore confronted with the problem of making proper allowance for the effects of leaking stoppings. The purpose of this paper is to present evidence in support of the author's suggestion that circuit pressure increase (per cent)

Jan 1, 1942

By Raymond Mancha

When calculating the pressure-volume characteristics of projected mine-ventilating circuits by orthodox methods, certain basic assumptions are required in order to employ the various available empirical data. It is assumed, for example, that the mine air is an incompressible fluid subjected to isothermal flow, an assumption sufficiently accurate for practical purposes since pressure and temperature differentials are small throughout the average circuit. A more erroneous assumption, however, is that all air is accounted for as it travels throughout the mine. No attempt is usually made to evaluate stopping leakage as it occurs; instead, the air volume required at the last crosscuts is assumed to enter the mine, travel the various intake air courses intact, sweep the workings and travel out by the return air courses to the point or points of exit from the mine. Actually, there is a leakage of air from intake to return at every stopping, the quantity of this leakage depending upon the tightness of the stopping and the pressure difference across the stopping. Unfortunately, a lack of empirical data and knowledge of the condition of individual stoppings makes an exact analysis of underground stopping leakage impossible. Generally, leakage is most severe through the old stoppings outbye the circuit. These are also subjected to higher pressure differences than the newer inbye stoppings. Therefore the circuit air volume diminishes at a decreasing rate progressing from outbye to inbye the circuit. Consider a simple mine circuit consisting of one intake and one return air course, each of equal and uniform section area and interconnected at regular intervals with crosscuts equipped with stoppings. At any point X inbye the circuit the air volume q on the intake air course equals that on the return air course and decreases with diminishing rate from outbye to inbye the circuit between the limits of Q1 completely outbye and Q completely inbye. Such a volume change is represented by curve a, Fig. I, which is computed with the aid of the equation q = Q1- (Q1- Q)(X + L)N. This equation results from the general algebraic equation of form q = k, — kXN after solving for kl and k with the knowledge that completely outbye X = o and q = QL, also completely inbye X = L and q = Q. Curves a, b and c, Fig. I, show values of q as ordinates versus values of X as abscissas, for values of N equal to 0.50, 1.00 and 2.00, respectively. Distribution of underground stopping 1eakage directly affects the air-volume distribution along the circuit, which in turn determines the circuit pressure gradient. To deliver any required air volume inbye a circuit or portion thereof requires a higher circuit-pressure differential if stoppings leak than is necessary with tight stoppings. Every mining engineer engaged in the analysis of projected mine-ventilation circuits is therefore confronted with the problem of making proper allowance for the effects of leaking stoppings. The purpose of this paper is to present evidence in support of the author's suggestion that circuit pressure increase (per cent)

Jan 1, 1942

By H. I. Aaronson

ONLY limited studies have been made of pro-eutectoid a morphology in hypoeutectoid Ti-Cr alloys during previous investigations, 1-3 The nature of the eutectoid reaction, ß?a + TiCr2, has been considered in somewhat more detail.1,2,4,4 Inasmuch as the proeutectoid ferrite reaction in plain carbon steels has recently been extensively investigated in this laboratory, advantage has been taken of the opportunity to compare the morphologies developed in two rather different eutectoid systems in order to permit a preliminary estimate to be made of the degree of generality which may be ascribed to the various results obtained. Experimental Procedure The chemical analyses of the alloys used are given in Table I. The 7.22 pct Cr alloy was prepared by the Battelle Memorial Institute from iodide titanium and high purity chromium. The initial ingot was made by arc melting a master alloy and iodide titanium. The resultant ingot was twice remelted. by the consumable electrode technique. Upset forging at 950°C reduced the final ingot to 3/4 in. sq bars. The 10.94 pct Cr alloy was prepared by the Titanium Metals Corp. of America from sponge titanium and chromium of ordinary purity. This alloy was melted twice by the consumable electrode technique, forged at 1200° to a 3/4 in. sq bar, and rolled at 815°C to a 1/2 in. round. Specimens 1/4 in. x 1/4 in. x 1/16 in. were cut from the 7.22 pct Cr alloy; halves of disks 1/2 in. in dlam and 1/16 in. thick served as specimens of the 10.94 pct Cr alloy. These specimens were individually encapsulated in Vycor, Each capsule was evacuated three times to a pressure of 2 to 6 x lo-' mm Hg and flushed twice with a reduced pressure of argon prior to sealing. The inclusion of two small packets of zirconium chips permitted the capsules to be outgassed and internally gettered, without heating the specimen, prior to heat treatment. The specimens were solution annealed for 40 min at 1000°C, isothermally reacted in deoxidized lead pots, and quenched in iced water. Most of the isothermal reaction treatments were carried out at 25" intervals between 725° and 550°C on specimens of the 7.22 pct Cr alloy and at 650°C on specimens of the 10.94 pct Cr alloy. Results and Discussion Morphologies of Proeutectoid a*—Kinetics of the ß?a Reaction: Fig. 1 shows the TTT-curves for the beginning of the proeutectoid a and the eutectoid reactions in the temperature range investigated in the 7.22 pct Cr alloy. The M, temperature in this alloy is below 0°C. The curve for the beginning of the proeutectoid a reaction is in good agreement with that of Frost, Parris, Hirsch, Doig, and Schwartz' for a 7.54 pct Cr alloy, appears at considerably earlier reaction times than the corresponding curve presented by Rostoker4 for a 7 pct Cr alloy, and lies athwart the curve of Spachner and co-workers11 for an 8 pct Cr alloy. Differences in criteria for the beginning of the a reaction and the relatively high rate of this reaction at lower temperatures presumably account for some of these divergences and may also explain, in part, the apparent failure of an iodide-base 7.22 pct Cr alloy to react more slowly than sponge-base 7 to 8 pct Cr alloys. Grain Boundary Allotriomorphs: Crystals of this morphology nucleate at and grow preferentially and more or less smoothly along the matrix grain boundaries.5-7 Allotriomorphs are the first morphology to precipitate at most grain boundaries at reaction temperatures from 725°C, the highest temperature studied, at least through 575°C. Fig. 2 Shows typical allotriomorphs, formed during an early stage of transformation at 725°C. Grain boundary allotriomorphs are not the predc=iaant morphology at late reaction times at any temperature studied. However; from 725" through

Jan 1, 1958

By P. C. Kelly

The processes involved in turning a set of seismograph records into a geological structure map may be divided into three classes; (1) picking reflections on the records, to be used for the computations; (2) determining the basis on which the computations should be made in order to arrive at correct results; (3) making the necessary computations and plotting sections and maps. The first is usually done by the crew chief, or at least checked by him. The computing system usually originates in the head office, occasional consultations with the party chief providing modifications as necessary to meet special conditions. The computations and plotting are done by the party computer, with possibly one or two assistants if the calculations require much time. Picking the Rejleclions Marking of the reflections on the records is perhaps the most important step and the one most likely to determine the reliability of the final results. Making the "picks" is important because most of the problems that come up in practical work are connected with the problem of what can be done with poor records. The lack of any definite criteria by which to judge what are good and usable reflections is at the bottom of the difficulty. Give the same set of records to several people to mark and they will probably come out with a variation in the number of reflections per record that are deemed usable. With good records the correct picks are obvious to all, but with poor records experience seems to be the only reliable guide as to what picks are reliable and what are merely born of imagination and desperation. Experience in marking records and seeing how the structures eventually check out is more important than training in physics or geology. Different types of equipment and shooting methods may produce records quite different in appearance, from the same territory, and the computer can do his best work with records of a type on which he has had considerable experience, and has learned the limitations and shortcomings as well as the virtues of the data with which he is working. Reflections may be picked for dips only, in which case the particular reflection picked is not recognizable with certainty on records from any other spread. For the purpose of computing dips it is necessary that the reflection be marked on a11 or nearly all of the strings of the records, as

Jan 1, 1940

By P. C. Kelly

The processes involved in turning a set of seismograph records into a geological structure map may be divided into three classes; (1) picking reflections on the records, to be used for the computations; (2) determining the basis on which the computations should be made in order to arrive at correct results; (3) making the necessary computations and plotting sections and maps. The first is usually done by the crew chief, or at least checked by him. The computing system usually originates in the head office, occasional consultations with the party chief providing modifications as necessary to meet special conditions. The computations and plotting are done by the party computer, with possibly one or two assistants if the calculations require much time. Picking the Rejleclions Marking of the reflections on the records is perhaps the most important step and the one most likely to determine the reliability of the final results. Making the "picks" is important because most of the problems that come up in practical work are connected with the problem of what can be done with poor records. The lack of any definite criteria by which to judge what are good and usable reflections is at the bottom of the difficulty. Give the same set of records to several people to mark and they will probably come out with a variation in the number of reflections per record that are deemed usable. With good records the correct picks are obvious to all, but with poor records experience seems to be the only reliable guide as to what picks are reliable and what are merely born of imagination and desperation. Experience in marking records and seeing how the structures eventually check out is more important than training in physics or geology. Different types of equipment and shooting methods may produce records quite different in appearance, from the same territory, and the computer can do his best work with records of a type on which he has had considerable experience, and has learned the limitations and shortcomings as well as the virtues of the data with which he is working. Reflections may be picked for dips only, in which case the particular reflection picked is not recognizable with certainty on records from any other spread. For the purpose of computing dips it is necessary that the reflection be marked on a11 or nearly all of the strings of the records, as

Jan 1, 1940

By Martin Mayers

FIVE-SIXTHS of all the coal that is mined in the United States is burned, without previous treatment other than screening, for the produc-tion of heat and power, so that its value is fixed by its suitability for this purpose. Nevertheless, the characteristics of individual coals that determine their fitness for use in particular pieces of combustion equip-ment are not yet well known. This condition is due not only to the small extent of our knowledge concerning coal itself, but also to our compara-tive ignorance of the nature of the combustion process. The following paper is an analysis of the combustion process as it occurs in industrial furnaces, based largely on the results of laboratory research on combus-tion rates. From this analysis it is possible to determine the characteris-tics of the fuel that limit the capacity of a given piece of combustion equipment. Limitations imposed by other factors than the attainable speed of combustion will not be considered, since they are subject to a different type of analysis involving the balancing of maintenance costs against fixed charges. In order to observe the relations among the various factors that affect the speed of combustion, representative particles of fuel will be followed through two types of furnaces. A pulverized-coal furnace will be con-sidered first, because the independence of the individual particles facili-tates the analysis of the effect of furnace conditions. The second example will be a grate-fired furnace in which ignition of the fuel takes place on the underfeed principle. This includes both underfeed and chain grate stokers,(8)? but does not include hand-fired furnaces and some overfeed stokers. The furnace will be considered to be large enough, the tempera-ture high enough, and enough air provided, to burn the fuel completely, without, for the moment, specifying these quantities more completely.

Jan 1, 1934

By B. C. Allen

Grain boundary grooving has been studied in chromium, molybdenum, and tungsten under a variety of conditions using high vacuum techniques and tantalum -gettered argon. The average surface free energy of solid chromium, and the chromium-liquid silver interface free energy were respectively found to be 2200 ± 250 and 500 i 130 ergs per sq cm from groove formation kinetics and estimates of pertinent volume difffusion coefficients. The results for chromium were unffected by variations in interstitial content ranging from 0.003 to 0.09 pct C, or 0.003 to 0.03 pct O. Surface diffusion is the primary mechanism of groove formation in chromium under 1 atm argon at 1200" to 140O°C, and is essentially unaffected by 0.003 to 0.09 pct C, 0.003 to 0.03 pct O , metastable nitrogen contents up to -0.01 pct, and up to 2 torr Ag vapor. At higher temperatures, the major mechanism is volume diffusion in argon or evaporation-condensation in stutic vacuum. Surface diffusion occurs in molybdenum at 0.5 to 0.96 and in tungsten at 0.5 to 0.9 of the absolute melting tempera -ture by a single mechanism, possibly by the migration of single adatoms or vacancies. Results were slightly affected by up to 23 tory Sn vapor, and in molybdenum were essentially unaffected by 0.5 Ti or carbon in the range 0.002 to 0.02 pct. Volume difffusion through the liquid is the mechanism of groove formation in chromium-liquid silver at 1200" to 1400°C and in molybdenum-, Mo-0.5Ti-, and tungsten-liquid tin at 1200" to 2000°C. The solid-liquid interface free energies involved were estimated from grooving kanetics. WHEN a grain boundary intersects a solid surface, a groove tends to form along the line of intersection at temperatures above about half the absolute melting point (0.5 TM). The groove progressively grows by preferential atomic migration either by diffusion or evaporation. Establishment of a groove angle occurs in accordance with the grain boundary and surface free energies involved. The motivation for groove formation is a reduction in the total surface free energy of the system. This study is a continuation of previous work on thermal grooving of chromium, molybdenum, and tungsten.&apos; The temperature ranges were extended, and the effect of metallic and interstitial impurities was evaluated. The results were such that certain interface free energies and surface self-diffusion coefficients were deduced from the grooving kinetics. EXPERIMENTAL WORK Materials and Preparation. As indicated in Table I, the 0.05-0.08-cm-thick chromium, molybdenum, and tungsten sheet used was nominally 99.99 pct after recrystallization. Two lots of molybdenum with about the same analysis, Mo-0.5Ti,* and tungsten were ob- *Alloy compsitions are expressed in weight percent . tained commercially. Extruded chromium rod,&apos; prepared from iodide process crystals, was warm rolled to sheet at 700°C. Sheet of three Cr-0 impurity alloys containing up to 0.03 pct 0 was prepared by warm rolling arc melted, extruded, and swaged rod. Two Cr-C impurity alloys containing up to 0.09 pct C were made by equilibrating unalloyed chromium with a known amount of CH4 for 24 hr at 1150°C in previously evacuated quartz capsules. Chromium containing nominally 0.015 and 0.06 pct N was similarly prepared by equilibration with NH3. The sheet was recrystallized to give a stable grain size about equal to the sheet thickness. Molybdenum and Mo-O.5Ti were recrystallized in a tantalum resistance furnace 1 hr at 1 x lo-5 torr at 2300" and 220O°C, respectively. Tungsten was similarly annealed for 1 hr at 2500°C. Chromium and its impurity alloys were outgassed at 1100°C and recrystallized 1 hr at 1700°C under 1 atm Ar. Except for nitrogen, the impurity content stayed roughly constant. Nitrogen in both alloys was reduced to <0.001 pct. In fact, over 80 pct of the added nitrogen was lost after outgassing at llOO°C and annealing sheet 1 hr at 1300°C in argon in the presence of tantalum. Such a rapid loss can be rationalized since -2 torr N are required for equilibrium with 0.04 pct N in solution,3 while the equilibrium pressure is ~10-5 torr over tantalum at 1300°C.4 The recrystallized sheet was cut into small coupons which were metallographically ground and polished on one side with a minimum of grain boundary relief. The surface roughness was on the order of 0.01 µ. The tin and silver used were nominally 99.999 spec-trographically pure. After being outgassed at 1100°C and equilibrated in a molybdenum crucible for 0.5 hr at 1800°C in argon, the tin contained 3 ppm 0, <0.3 ppm N, and 0.1 ppm H. Following outgassing at 900°C and equilibration in a chromium crucible 1 hr at 1400°C in argon, the gas content of the silver was 1 ppm O, <0.5 ppm N, and 0.3 ppm H. Grooving Under Argon or Vacuum. All specimens were placed in unsealed containers made from rod or sheet of the same alloy, thereby enabling the polished surface to achieve gas-solid equilibrium. The annealing fixtures are shown in Fig. 1. The specimen was placed in a resistance furnace with a tantalum or Ta-10W heating element plus tantalum fixtures or radiation shields. Chromium was outgassed at 1100°C, and molybdenum and tungsten were outgassed at 1900°C to 1 x l0-5 torr or at the grooving temperature, whichever was lower. In vacuum anneals, the specimen was then heated directly to the intended grooving temperature. In argon anneals, 99.996 Ar was admitted

Jan 1, 1970

By L. G. Huntley

A description f the geology and conditions affecting the occurrence and mining of oil; also the prospects of obtaining oil in different parts of the country. THE Colombian highlands consist of three parallel mountain ranges (Fig. 1) called respectively the eastern, central, and western cordillera of the Andes. A segment of the range that forms the backbone of the Isthmus of Panama also extends into Colombia, along the Pacific coast, as far southward as the mouth of the San Juan River. These four mountain ranges furnish the key to the varying climatic conditions and vegetation of the country. The river valleys are hot and covered with dense tropical growth. This is also generally true of the coastal plain, although in the northern portion there are some fairly open stretches where cattle are raised and even small districts where semi-arid conditions prevail. The population of this heavily wooded wet lowland depends almost entirely on river transportation for all intercourse. The elevated mountainous plateaus of the three ranges are more open and more generally cultivated; all traffic is by means of horses, mules, and the burro. The canoe and river-steamer transportation systems of the valleys are connected with the highland system of trails and roads by short cross trails and the few short railroads of the country. As these cross trails must pass through the intermediate foot-hill region, where the heavy rainfall reaches its maximum, they are exceedingly bad and the life of pack animals is short. The oil development of the Magdalena River valley is in this intermediate region, between the river and the sierras, north of Bogotá.

Jan 9, 1922

By A. H. Larson, R. J. McClincy

Laboratory-scale decopperizing experiments with multiple sulfur addifions were conducted at 330°C on ternary Pb-Cu alloys containing, as the third elenlent, Sn, Ag, As, Sb, Bi, Zn, and Au, common impurities in lead blast-furnace bullion. For silver and tin, an increased rate and extent of &apos;cofifier removal was obsert3ed. The elements As, Sb, Zn, Au, and Bi had no effect or less effect as compared to sulfur additions with no i)npurily additions. THE production of primary lead in the blast furnace yields an impure lead frequently containing such impurities as copper. antimony. arsenic. tin, gold, silver iron, oxygen. and sulfur. By cooling this lead to a temperature near its melting point. most of the iron, sulfur, and oxygen and part of the other impurities are removed in the form of a dross. With incipient solidification of the lead, the copper concentration wil have been reduced to 0.02 to 0.05 pct. depending upon the concentration of the other impurities. according to Davey.&apos; Since copper interferes with the treatment of silver after the desilverizing process, it is desirable to decrease the copper content of the lead still fur-ther before the lead is desilvered. The decopperizing of the lead is accomplished by stirring a small quantity. approximately 0.1 pct. of elemental sulfur into the lead at a temperature near its melting point, 330" to 360°C. The copper is removed as a copper sulfide which constitutes a small fraction of a voluminous dross consisting mostly of lead sulfide and entrained metallic lead. The residual copper concentration following the decopperizing operation is frequently as low as 0.001 to 0.005 pct. Thi fact has aroused considerable interest because the equilibrium copper concentration of lead in contact with solid PbS and solid Cu2S is at least an order of magnitude greater, 0.05 pct Cu at 330C. 1, 2 Most investigators have suggested that various impurities in the lead bullion are responsible for the very low copper concentrations frequently encountered in practice. There is little agreement, however? as to which of the impurities are helpful and which are not.3"11 Also. few investigators have sought to explain the mechanisms responsible for the removal of copper to very low concentrations. Willis and Blanks9 have proposed that a nonstoichiometric copper-deficient cuprous sulfide forms in place of the supposed Cu2S. Being copper-deficient, this sulfide phase would possess a low copper activity, and the diffusion of copper dissolved in the liquid lead into this phase would be greatly facilitated. Pin and wagner2 have investigated the removal of copper from liquid lead by studying the effect of impurity-doped lead sulfide on the decopperizing of pure Pb-Cu alloys. Samples of the doped PbS were held in contact with copper-saturated lead for 1 week at 33&apos;7°C. They reported a beneficial effect on decopperizing with bismuth and antimony and no effect with tin or silver. which is directly opposite to the results observed in practice and those reported by Davey 3 and this studv. The purpose of this paper is to describe the effects of certain additive elements on the extent to which copper can be removed fro111 liquid lead by successive additions of sulfur. The impurity elements were added individually to prepared Pb-Cu alloys. The resulting ternary alloys as well as a binary Pb-Cu alloy were then decopperized with repeated additions of sulfur. EXPERIMENTAL Materials. Granulated test lead with a purity of 99.999 pct and the additive elements Cu. Ag. Sb. Bi. Zn. Sn. and Au with purities of 99.99 pct were American Smelting and Refining Co. research-grade materials. The major impurities in the lead were 1 ppm each of iron and copper. all others being less than 1 ppm. The arsenic used was a technical-grade arsenic of 98+ pct purity. Reagent-grade flowers of sulfur were melted under argon to provide small pieces free of fines. Apparatus. The decopperizing experiments were carried out in a 25-mm-OD by 375-mm-long Pyrex tube sealed at one end. The tube was mounted vertically in a resistance-heated. hinge-type tube furnace controlled to within ±lcC. Temperature measurement was accomplished by means of a standardized chromel-alumel thermocouple sealed into the base of a silica. paddle-type stirring rod. All decopperizing experiments were carried out under an argon atmosphere. Procedure. A Pb-Cu starting alloy containing 0.05 pet Cu was prepared under carbon and poured into cold tap water to produce shot. The ternary alloys were prepared by melting together 100 g of the starting alloy and a sufficient amount of the impurity element to yield the desired concentration. The resulting alloy was then homogenized in a Pyrex tube at 450C with continuous stirring. The furnace temperature was then lowered to the operating temperature of 330°C. When thermal equilibrium had been obtained at the operating temperature, individual additions of 0.2 pct (0.2 g) of solid sulfur were added to the melt and stirred in. Stirring was continued for a period of 3 min. discontinued for 5 min. and resumed for the remaining 2 min of a 10-min cycle. This cycle was repeated for as many sulfur additions as desired. When the decopperizing experiment had been completed the lead bullion was quenched and samples of the bullion and dross phases were taken for analysis. Results. The results obtained in the decopperizing

Jan 1, 1970

By George S. Rice

MANY studies on ground movement and subsidence have been carried on by members of the Institute during the past year, but only a few papers have reached maturity. Two of the mining schools of this country have continued their interest in ground movement research. At Columbia University School of Mines, Philip Bucky has continued his investigations, employing photoelastic methods and the use of his centrifugal apparatus for testing what he termed "the strength and behavior of mining structures." Helmut Landsberg, of The Pennsylvania State College, has developed a convergence recorder similar in principle to that used by the

Jan 1, 1936

By L. Moyd, P. Moyd

The first commercially available portable gamma ray-neutron beryllium detector, the Rerylometer, was developed by the same group that developed the first practical portable scintillation counter, the Scintillo-meter. This group includes Professor George Brownell, of the Geology Department of the University of Manitoba in winnipeg, and his associates, K. I. Roulston, R. w. Pringle, and R. L. Funt, of the Physics and Engineering Departments of the University of Manitoba. A prototype model was tested in the field by Dr. Brownell during the summer of 1958. Commercial production was undertaken shortly thereafter by Nuclear Enterprises Ltd., of Winnipeg, and a license for manufacture and distribution in the U.S. was granted to Isotopes Specialties Co., of Burbank, California, a division of Nuclear Corporation of America. Early in 1959, we were retained by the &apos;Mining Division of Minerva Oil Co. to Legin a search throughout North America for minable deposits of beryllium, and to train members of their permanent staff to continue the program. The project included literature sur-veys, interviews with members of various federal, state, and provincial agencies, scanning of our own collection of suites of specimens from various mineral occurrences, and the examination of deposits in the field. The value of a beryllium detector to this program was obvious and arrangements were made to procure one as soon as possible, which resulted in our obtaining and using the first instrument that was produced commercially in the U. S. In addition to the commercially available Berylometer, Mr. William Vaughan and his associates, of the U. S. Geological Survey Geophysics Division, in Denver, have developed and tested several experimental instruments based on the same principles. DETECTOR Principles The detection of beryllium is based on the fact that "hard" gamma rays (1.6 MEV and geater), such as those produced by Antimony convert ordinary beryllium (Be9) to Be8 , with the release of a neutron. The neutrons are counted by a scintillator designed to favor neutron responses while suppressing those of gamma rays. &apos;The instrument is completely selective for beryllium. No other element can interfere. Instrunlentation The Rerylometer itself, which is cylindrical, is about 8 inches in diameter, 13 inches high, and weighs about 11 pounds. (Figs. 1, 2). The principal components include: 1. A disc of wax to moderate (or "thermalize") neutrons. 2. A boron-enriched polyester-zinc-sulphide fluorescent screen. This material produces strong flashes when struck by thermalized neutrons but only weak flashes from gamma rays. 3. A photomultiplier tube. 4. An electronic circuit, complete with one srnall 71/2-volt dry battery. The photomultiplier tube and electronic circuit convert neutron flashes to electrical impulses, but gamma ray effects are almost

Jan 1, 1961

By R. D. MacDonald, John Dasher, A. M. Gaudin

ION exchange is a widely used unit operation in water treatment and elsewhere in chemical industries. It has occasionally been used in hydro-metallurgy for treating plating, pickling, and rayon wastes Concerning ion exchange in extractive hydrometallurgy—for treating ore leach solutions— the literature prior to the Geneva Conference has given only hints."-" Yet most of the ore leach plants now being built or completed in the last three years use ion exchange for this purpose. Most of these plants are used for extracting uranium. The overall process for leaching low grade uranium ores and the history of its development have been given in the authors&apos; previous papers.&apos;,&apos; The object of this paper is to discuss certain engineering aspects of the new application of ion exchange to recover dissolved values from ore leach solutions. Necessarily the illustrations will be taken from the first application—to uranium metallurgy. Although ion exchange processes have been devised in which separation of spent residue from pregnant liquor is not required, as in the RIP process,"-&apos;I only ion exchange operation, in which the resin is contacted with a clear solution, will be discussed in this paper. Uranium exists in acid leach liquors mainly as the cation UO," and can be adsorbed completely by cation exchange resins, but the adsorption is not selective as other cations such as Fe++, Fe+++, Al+++, Mg++, Mn", and Ca++ are also adsorbed. Uranium, however, forms complex anions with sulfate, phosphate," Carbonate"~"~ and even with chloride if the solution is strong enough.15 These anions can be adsorbed by anion exchange resins. The strong base anion exchangers have a very strong preference for these complexes and hence this adsorption is very selective. In this paper, the examples concern acid sulfate leach liquors from which uranium is adsorbed as UO,(SO,),-% and UO,(SO,),". Materials and Equipment Ion Exchange Material—Ion exchange materials include natural and synthetic; organic and inorganic; cationic and anionic; and weak, intermediate, and strong varieties. They consist of fragments or beads normally in the size range —16 to $50 mesh. The newer varieties have been developed to have greater stability, chemical strength, and/or capacity than earlier varieties. The resin used for uranium recovery is a strong base anion exchanger.* To make * Such as Rohm and Haas Amberlite IRA-400 series, British Permutit DeAcidite FF. Permutit lonac SE. and Dow Nalcite SAR. this resin, styrene plus a few percent divinyl benzene are polymerized into long chains with occasional cross links. This resin in bead form is then reacted to introduce quaternary amine groups onto most of the aromatic rings.&apos; These resins are water-avid gels of specific gravity of about 1.1, which shrink and swell by osmosis when the ionic content of the surrounding solution is changed. The beads which are shown in Fig. 1 can be broken like an onion by rapidly replacing 15 pct H,SO, with water. This organic gel can also be broken by mechanical handling as by a centrifugal pump. Otherwise it is remarkably stable. It is unharmed by fairly strong acid or alkali, oxidizing or reducing agents, and heat up to 70°C. The strong base resin when completely in the chloride form (with a chloride anion on each quaternary amine group) holds over 107 g of C1- per dry kg. As all these chloride ions can be displaced by other anions, the resin has an exchange capacity of over 3 g equivalents per dry kg. However, the resin is sold and used by moist volume. The moist resin contains about 50 pct water, weighs about 43 lb per cu ft, has 40 pct voids, and an exchange capacity of over 1 g equivalent per liter of bed volume. Ion Exchange Equipment—Ion exchange equipment used for recovery of uranium from leach solutions is substantially identical to that developed for water treatment and other applications.&apos;" The resin beds are held in closed tanks or columns which, in the uranium plants, have been standardized at 7 ft diam and 12 ft high. The resin bed

Jan 1, 1958

By A. B. Kinzel, Walter Crafts

A PRevioUs study1 of the relations of impact strength to inclusions showed that the dynamic strength of steel is lowered by the presence of visible counted inclusions, but that other factors comprised in the term "body" have a marked influence. The previous work was carried out on selected steels from a single source, so that the body factor was purposely minimized, but even under these conditions it was found that inclusion counting or the use of the commercial inclusion rating is not satisfactory. The tensile-impact test, however, was indicated as a satisfactory measure of dynamic strength. It was further suggested that the tensile-impact test should be so standardized as to be suitable for use in specifications, and that the hardness factor should be worked out over a sufficient range to admit ready commercial use of the tensile-impact test. In accordance with these suggestions, and in view of the fact that the steels reported in the previous paper were selected and treated so as to have a minimum variation in body, hardness and structure, further work has been performed on a variety of steels which are not limited by these conditions. The word "body" is used here for want of a better term. It is simply a convenient expression which comprises the effect, of the various unknown factors that modify the dynamic strength of the steel. Thus at our present state of knowledge, the writers have chosen to consider hardness, structure and counted inclusion content as factors not comprised in the term "body," and such factors as raw materials, process of melting, fabricating, etc., as comprised in the term "body." Numerous grades of steels made in several ways have been taken from different sources and have been heat-treated to varying hardness by normalizing and by quenching and drawing. The results, therefore, may be considered to be generally applicable to current engineering steels. A certain limitation with respect to the hardness at which steel should be tested still seems necessary. The upper limit of this hardness range has

Jan 1, 1931

By L. E. Young

IT has been said the British Empire was built on British Coal. In all the postwar planning for Great Britain the necessity for producing cheap coal and the prosperity of the coal industry are given first consideration. On Jan. 23, 1945, there was released in London a "Report to the Colliery Owners" which had been awaited with great interest. This was entitled "A Plan for Coal" and was the recommendation of Robert Foot, chairman of The Mining Association (Colliery Owners), prepared at their request. Presentation of the "Plan" at this time is particularly significant as it is an answer to the demand for nationalization of the coal industry by the Labour Party and at the same time is a carefully considered program for postwar reconstruction, prosperity, and stability. In the words of Mr. Foot, If the coal industry for the first ten years after this war is to find itself in a situation similar to the one it occupied for the ten years following the last war, with its record of disputes, strikes, stoppages, short-time working, unemployment, and, with it all, a completely insufficient margin of profit, and all the insecurity and instability in our basic industry that was brought with them, it is goodbye to any real prospect of full employment, social security, and high standard of living. To present an elaborate review of the conditions which have brought to a crisis the unfortunate situation in the British coal industry is here unnecessary, but certain of the salient points

Jan 1, 1945

By Clark L. Corey, Bogdan Lisowsky

Electrical resistivity, X-ray line positions, degree of order, and microstructures have been investigated for Ni-A1 alloys near the Ni3Al composition. The results indicate that Ni3Al undergoes disordering between 1250oC and the mp; also supersaturated y, produced in y + y&apos; alloys by gas quenching, is extensively ordered prior to y&apos; (Ni3Al) phase separation. The latter reaction, if not both, must follow the cooperative phenomena model. Shifts in line position as a function of quench-indulced super satulration are shown. Lattice pavarneters of equilibriunz and nonequilibrium phases are given. THE objective of this investigation was to determine the mechanism and kinetics of the reactions which occur in Ni3A1 and hypostoichiometric Ni3A1 alloys. The results are of particular significance relative to pre-precipitation phenomena. Early work on Ni-A1 binary compositions near the Ni3A1 composition (13.6 wt pct Al) has been adequately reviewed by Hanssen,1 whose phase diagram is presented in Fig. 1. williams2 verified the suggestion made by Taylor and Floyd3 and others4 that y&apos;, Ni3A1, may precipitate coherently on (100) planes of the y phase (see Fig. 1 for phase nomenclature); he further suggested a two-step precipitation mechanism consisting initially of probably short-range ordering followed by actual precipitation of y&apos;. The precipitation stage in low-aluminum hypo-eutectic compositions has been studied by a number of investigators;*"7 short-range order or "zone" formation have been suggested as explanations for various diffuse X-ray scattering effects. The ordering reaction in Ni3A1 alloys is characterized by a) a very rapid rate of ordering in nonstoi-chiometric compositions, b) absence of a disordered phase region for the stoichiometric compound, y&apos;, or Ni3A1, c) precipitation phenomena as a dominant aspect in hypoeutectic alloys, and d) an increase in elec-trical resistivity on ordering.&apos; The latter two factors were found by Newkirk to characterize ordering in Co-Pt, for which an extensive and detailed analysis was made.&apos; An electrical-resistivity increase on ordering has also been reported for cuAu3.10 PROCEDURE Ni-A1 alloys in the form of 1300-g chill-cast ingots were prepared by vacuum melting electrolytic nickel and high-purity (99.99 pct) aluminum. Very small heats prepared from high-purity carbonyl nickel, supplied through the courtesy of Dr. Goff of the Naval Research Laboratory, were used for comparison with the larger ingots and no differences were noted. The cast material was homogenized in purified argon for a minimum of 72 hr at 1200°C and water-quenched from 1350°C. Compositions studied are given in Table I. The 10 pct A1 alloy was both hot- and cold-rolled. X-ray superlattice line intensities and peak positions were obtained from -270 mesh filings, using CuK, radiation with a LiF crystal monochromat adjusted to receive both 01 and a2. One-degree slits and a 1/8 deg per min scan rate were used to record line traces. A standard tungsten powder, obtained through the courtesy of G.E. Research Laboratory, was used to calibrate line positions.

Jan 1, 1968

By JOSEPH MACDONALD

STRIPPED of its romantic possibilities, mining is a commercial business, carried on for the profit there is in it, and the business of the manager, in its ultimate analysis, is to make the profit as large as possible. The general manager of a mining company should keep himself personally familiar with all the details of its operations. If be fails to do so, chaos results, labor becomes inefficient, costs go up, and profits go down. Nowhere is this emphasized more than in Mexico. If the mining operations are extensive and complex, involving, besides the work of mining the ore, its transportation and treatment by various milling operations, and the marketing of the products, the business, to be carried on properly, must be divided into a number of main departments, which are subdivided into minor departments. Each main department should be under the immediate charge of a superintendent, or a foreman, and each minor department under a shift-boss. Organized in this way, and with all the principal centers of activity connected by telephone, the manager can keep in touch at all times with the details of every branch of the business, and be in a position to perform effectively the full duty of manager. The ?total cost of mining operations may be broadly divided under the heads of Labor, Supplies, and Marketing. Of these, it will be found, on averaging a number of cases, that the cost of labor will be about two-thirds of the total cost. The importance, therefore, of an efficient labor-department will be apparent. This department must be sub-divided and organized differently, according to the peculiar conditions at each mine, and no one system, however well suited for one particu-

Jan 1, 1909