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By Margaret V. Doyle, R. W. Powers

INTERNAL friction measurements, carried out as functions of temperature, have been used extensively to obtain data on the mobility of interstitial impurities in the Group V metals, vanadium, colum-bium, and tantalum. For a given frequency of vibration, the internal friction peaks at a temperature which depends principally on the particular metal and interstitial impurity. Relaxation times and corresponding activation energies are determined from a knowledge of such peak temperatures for various vibration frequencies. These experimentally determined relaxation times are related to the average jump frequencies of the interstitial impurity atoms using the model of Snoek1 and can be related to macroscopic diffusion coefficients as shown by Polder.2 In these Group V elements, the impurity whose diffusion rate has been the hardest to pin down by the internal friction technique has been carbon. The experimental difficulties associated with carbon in these metals were not evident in the earliest investigation carried out by Ke on tantalum.3 The carbon peak was thought to occur near 140°C at 1 cps on the basis of the enhancement of the height of this peak measured on specimens which had been coated with colloidal carbon and heated in vacuo at 1200°C. Presumably on the basis of similar evidence, Wert identified a peak also near 140°C at 1 cps in columbium with the diffusion of carbon in that element." Later, the difficulties of admitting carbon into these metals without simultaneously introducing oxygen were pointed out by Ang and Wert- nd by Marx, Baker, and Sivertsen.6 The latter suggested that the peaks attributed to carbon in tantalum and columbium might arise from the presence of traces of oxygen, adventitiously absorbed during the carburization. Such suspicion was confirmed, at least in tantalum, when it was found possible to prepare C-Ta specimens without contamination by oxygen. Specimens sci prepared, aitnough high in carbon content, gave no evidence of a damping peak near 140°C.7 Recently, the authors were able to Show that carbon diffuses in tantalum at a rate only slightly slower than that for nitrogen.8 At 1 cps, the carbon peak lies at 34g °C, only a few degrees above the nitrogen peak at 341 °C. However, the two could be distinguished by a different stability with respect to aging at 400 °C and by a different dependence of peak height on solute concentration. On the basis of this experience with tantalum, it appeared worthwhile to search also for a carbon peak in columbium in the vicinity of the nitrogen peak." In this report, the location of the carbon peak in columbium is made known and its position relative to the nitrogen peak is compared with the authors' previous findings in tantalum. In addition, a second source of internal friction seen only in specimens of very high purity is discussed. Columbium was obtained from the Fansteel Metallurgical Corp. as either 30 or 40 mil diam stock. The manufacturer gives the following analysis as typical of this material: 99.4 pct minimum Cb, 0.10 pct maximum C, 0.5 pct Ta, 0.04 pct Ti, 0.02 pct maximum Si, and 0.01 pct maximum Fe. Wires 13 in. long were degassed near 2200°C for 4 to 16 hr in an ultimate vacuum better than 2.10" mm Hg in an apparatus described previously.8 This treatment reduced the oxygen and nitrogen damping peaks observed in the as-received material to less than 0.0001 in Q-1 above background. The latter value varied somewhat from specimen to specimen in the range 0.0004 to 0.0008, depending chiefly on the wire diameter and the frequency of vibration. The high temperature evacuation left the specimen in a rather soft condition, the Vhn being reduced to 40 from a value near 121 in the as-received conGi~iur~. The gram size was about the diameter of the specimen. After outgassing, specimens were loaded with carbon by absorption of such hydracarbons as methane or ethylene. Carbon was also added to a few speclrnens by heating them at

Jan 1, 1958

By J. Washburn, R. Drouard, E. R. Parker

Temperature dependence of the rate of recovery in zinc single crystals after a simple shear deformation at low temperature was investigated. Some tentative suggestions regarding the annealed and strain-hardened states of a crystal are discussed. RECOVERY may be defined as the gradual return of the mechanical and physical properties of strain-hardened metal to those characteristic of the annealed material; an increase in temperature increases the rate of recovery. The annealing process in strain-hardened polycrystalline metals is complicated by the inhomogeneity of strain which always exists in aggregates. Polygonization in bent regions of the crystals and growth of new almost strain-free grains starting at points of severe local distortion1-:' make it almost impossible to isolate and study the recovery process. Homogeneously strained single crystals, however, do not polygonize or re-crystallize and hence they can be used advantageously to study recovery. In such crystals strain hardening is completely removed by recovery alone. Since recovery is a process whereby certain lattice disturbances introduced by plastic flow are gradually reduced, a knowledge of the rate and temperature dependence of this process for various conditions of prestrain might be helpful in formulating a model of the strain-hardened state. For simplicity it seemed desirable to limit the type of prestrain to the simplest obtainable, i.e., simple shear strain. In the experiments to be described, recovery was studied by observing changes in the stress-strain curve of prestrained zinc single crystals held for various times at temperatures above that employed for straining. Single crystals were grown from the melt by a modified Bridgeman technique from Horse Head Special zinc 99.99 pct pure, and from spectrographically pure zinc 99.999 pct pure. They were grown as 1 in. diameter spheres and acid-machined' to the final specimen contour. The test section was a cylinder about 1/8 in. high and 3/4 in. in diameter. The conical sections adjacent to the test section were cemented into the grips so the load could be transmitted to the crystal as uniformly as possible. The specimens were oriented so that in testing the maximum shear stress was applied along one of the slip directions, [2110], in the (0001) plane. Details of the production and testing of such specimens have been presented.' Each test was carried out according to the following schedule: 1—The crystal was strained at — 50°C until it reached a maximum shear stress, ,,,. The strain rate was approximately 5 pct per min in all cases. 2—After straining, the crystal was unloaded before the temperature was changed. Unloading required about 3 min. 3—The temperature of the specimen was then increased from — 50°C to the temperature, T, of recovery. This change in temperature was completed in a time of less than 2 min. The specimen remained at temperature, T, for a time, t, which differed for the various specimens. 4—Thereafter the temperature was again reduced to — 50 °C in approximately 3 min. 5—While at —50°C, the stress-strain curve after recovery was obtained. 6—The specimen was then unloaded and annealed for 1 hr at 375 °C in a helium atmosphere to bring about complete recovery. Cooling to room temperature after anneal required 90 min. 7—The same crystal could be re-used for another test because the plastic properties after annealing closely duplicated those of the original crystal. The specimen was immersed during the test in a bath of methyl alcohol which, through a system of tubes, could be pumped through either of two heat exchangers to regulate the temperature; this was accomplished by circulating the liquid through coils immersed in a bath of acetone and dry ice for cooling or in a bath of warm water for heating. Test temperatures were thus maintained constant within ±1°C. The — 50°C temperature was low enough so that no measurable recovery occurred during unloading and reloading. The stress-strain curve continued after recovery along a path below, but approximately parallel to, the path of a curve obtained in an uninterrupted test. Fig. 1 shows some of the results from a specimen of 99.999 pct Zn. The amount of downward displacement of the curve due to recovery was a

Jan 1, 1954

By J. Chipman, M. N. Dastur

The importance of dissolved oxygen as a principal reagent in the refining of liquid steel and the necessity for its removal in the finishing of many grades have stimulated numerous studies of its chemical behavior in the steel bath. From the thermodynaniic viewpoint the essential data are those which determine the free energy of oxygen in solution as a function of temperature and composition of the molten metal. A number of experimental studies have been reported in recent years from which the free energy of oxygen in iron-oxygen melts can be obtained with a fair degree of accuracy for temperatures not too far from the melting point. Certain discrepancies remain, however, which imply considerable uncertainty at higher temperatures; also several sources of error were recognized in the earlier studies. It has been the object of the experimental work reported in this paper to reexamine these sources of uncertainty and to redetermine the equilibrium condition in the reaction of hydrogen with oxygen dissolved in liquid iron. The reaction and its equilibrium constant are: H2 (g) + Q = H2O (g); K1 _ PH2O / [1] Ph2 X % O Here the underlined symbol Q designates oxygen dissolved in liquid iron. The activity of this dissolved oxygen is known to be directly proportional to its concentrationl,2 and is taken as equal to its weight percent. The closely related reaction of dissolved oxygen with carbon monoxide has also been investigated:3,4,5 co (g) +O = CO?(g); K _ Pco2___ [2] K2= pco X % O [2] The two reactions are related through the wat,er-gas equilibriuni: H2 (g) + CO2 (g) = CO (g) + H2O (g); K2 = PCO X PH2O [3] PH2 X PCO2 and with the aid of the accurately known equilibrium constant of this reaction, it has been shown5 that the experimental data on reactions [1] and 121 are in fairly good, though not exact, agreement. Experimental Method Great care was taken to avoid the principal sources of error of previous studies, namely, gaseous thermal diffusion and temperature measurement. The apparatus was designed to provide controlled preheating of the inlet gases and to permit the addition of an inert gas (argon) in controlled amounts, two measures found to be essential for elimination of thermal diffusion. A known mixture of water vapor and hydrogen was obtained by saturating purified hydrogen with water vapor at controlled temperature. This mixture, with the addition of purified argon, was passed over the surface of a small melt (approximately 70 g) of electrolytic iron in a closed induction furnace. After sufficient time at constant temperature for attainment of equilibrium the melt was cooled and analyzed for oxygen. GAS SYSTEM A schematic diagram of the apparatus is shown in Fig 1. Commercial hydrogen is led through the safety trap T and the flowmeter F. The catalytic chamber C, held at 450°C, was used to convert any oxygen into water-vapor. A by-pass B with stopcocks was provided so that the hydrogen could be introduced directly from the tank to the furnace when desired. From the catalytic chamber the gas passed through a water bath W, kept at the desired temperature by an auxiliary heating unit, so that the gas was burdened with approximately the proper amount of water vapor before it was introdvced into the saturator S. All connections beyond the catalytic chamber were of all-glass construction. Those connections beyond the water bath were heated to above 80°C to prevent the condensation of water vapor. After the saturator, purified argon was led into the steam-hydrogen line at J, and finally the ternary mixture was introduced into the furnace. THE SATURATOR The saturator unit comprised three glass chambers, as shown in Fig 1, the first two chambers packed with glass beads and partially filed with water and the third empty. Each tower had a glass tube with a stopper attached for the purpose of adjusting the amount of water in it. The unit was immersed in a large oil bath, which was automatically controlled with the help of a thermostat relay to constant temperature, ± 0.05ºC, using thermometers which had been calibrated against a standard platinum resistance thermometer. The performance of the saturator over the range of experimental conditions was checked by weighing the water absorbed from a measured volume of hydrogen; the observed ratio was always within 0.5 pct of theoretical.

Jan 1, 1950

By WILLIAM J. LINNEY

MAGNETITE ore from Lyon Mountain, so- called "Low Phos Chateaugay," has long been known to the iron and steel industry for its almost complete absence of impurities. These magnetites occur along the northern foothills of the Adirondacks in several parallel and folded stringers which are continuous for several miles, striking generally northeast-southwest and dipping usually over 45° to the northwest, or roughly toward the St. Lawrence River. Ore of minable thickness is found in shoots of various sizes as to length and breadth, but of undetermined and possible great depth.

Jan 1, 1943

Prof. Henry M Howe, New York: It is extremely probable that this efflorescence of silica is due to the liquation either of silicon or of a silicide, and the subsequent oxidation of the silicon to silica. As Mr. Fackenthal says, it is very hard to see why silicon should liquate from an iron containing so little silicon, and it seems more probable that some silicide of some volatile element has liquated, and has dissociated on reaching the air, and that the volatile element has volatilized, leaving the silicon to oxidize to silica. The volatile elements present which might thus liquate in combination with the silicon are sulphur, zinc, and lead. It is hard to see why sulphide of silicon should have liquated from an iron containing so little of either sulphur or silicon. At first, one naturally thinks that either the zinc or the lead present in this furnace might have liquated as silicide. It is true that they are both volatile at the temperature within the furnace, but then the vapor-tension* of each of them within

Jan 1, 1901

By B. T. Brady

Rock mechanics, like all engineering disciplines, must have a theoretical foundation. The subject of this chapter is the formulation of analytical methods that may aid in the rational design and determination of the stability of engineering structures in competent brittle rock materials. By an engineering structure in rock, we mean any (1) excavated sub- surface opening, (2) open surface structure, or (3) system of openings in rock that is virtually self-supporting-that is, not requiring artificial systems to carry structural stresses.

Jan 1, 1970

By P. Shahinian, R. L. Stegman, M. R. Achter

Creep strength has been determined as a function of oxygen pressure for nickel at 510" and 600°C. Creep-rupture life drops from its highest value at the ultimate vacuum of 10-7 torr to a high pressure plateau of nearly constant life which, at 600°C, commences at torr. This behavior is described in terms of a model that relates surface gas adsorption and the generation of fresh crack surfaces. In a calculation based a this model the predicted pressure beyond which the creep strength should not decrease further has been found to agree well with the observed value. The introduction of oxygen during creep in vacuum was found to cause a prompt rise of the creep rate. The magnitude of the environmental effect was much less than generally observed in fatigue and this is attributed to the diffarent crack morphologies in creep and fatigue. GASEOUS environments are known to affect creep resistance adversely1-5 but the effects have received less attention than the much larger ones in fatigue. At low temperatures it has been shown for nickel that the creep rates are faster and the rupture lives are shorter in air than in vacuum and that these environmental effects can be correlated with faster crack growth rates in the reactive environment.' In support of a mechanism of gas adsorption at the crack tip to explain the above effects, a calculation based on kinetic gas theory showed that surface coverage by gas was not as rapid as the exposure of fresh metal at the crack tip in the ultimate vacuum but was in air.7 In fatigue a number of investigations have demonstrated that the reduction of life with gas pressure usually follows a step curve with most of the reduction occurring in a transition range at intermediate pressures and little or no change at high and low pressure.8 There have been no studies, however, in which creep strength has been determined as a function of reactive gas pressure to see whether similar effects would be found. This investigation was undertaken to study the kinetics of the environmental effect in the creep of nickel. EXPERIMENTAL PROCEDURES The environmental creep apparatus was constructed to minimize many of the experimental conditions which can cause scatter in data. Dead weight loading is employed and weights are contained within the environmental chamber to eliminate bellows and the necessity for compensation for gas pressure changes. Elongation over the specimen gage length is recorded from a Riehle Model DV Controlled Environment Extensometer which provides readout to 2.5 x 10- in. Temperature is monitored and controlled from a thermocouple at- tached to the specimen gage length to +0.5oC or better. The freon trapped oil diffusion pump vacuum system included an auxiliary liquid nitrogen trap and, with a wide range variable conductance leak valve, pressures from the ultimate vacuum of 10"7 to l03 torr of any desired gas are obtainable. Pressure is measured by means of a hot filament ionization gage below 10"3 torr and a NRC Model 530 Alphatron Vacuum Gauge above 10-3 torr. The oxygen, which was leaked into the environmental chamber, was an Aviator's Grade of 99.5 pct purity with a dew point of -80°F. Analysis of the nominal 99.8 pct Ni showed the following percentages of major impurities: 0.02 C, 4.01 Mn, 0.005 Si, 0.01 Cu, 0.02 Fe, and 0.034 Mg. Cylindrical specimens were machined with a 0.180

Jan 1, 1970

By O. Hoover, M. Herman, V. V. Damiano

The Jetter and borie' teclznique of determining textures using a spherical specimen has been applied to tlze study of compression-rolled beryllium sheet. Snzall spheres the order of 1 mm in diam cut from the beryllium sheet were autotnatically rotated about tz41o axes using the G.E. single-crystal goniometer. Quantitative pole figures were obtained without tke need to apply absorption corrections. Compression-rolled beryllium exhibited peak intensities ,for (0002) planes of positions tilted 10 deg to the rolling plane and a near random distribution of (1010) planes about the nornal to the rolling plane. TECHNIQUES for determining textures of rolled sheet material are amply described in the literature. The techniques are found to be variations of two basic methods. One due to Decker, Asp, and arker, referred to as the transmission method, utilizes a thin-sheet specimen in which the X-ray beam enters the specimen from one side and the intensity of the beam which emerges from the opposite side is measured. The second method due to chulz,3 referred to as the reflection method, utilizes a thick specimen and the intensity of the beam emerging from the same side is measured. The two rotations of the specimen in the beam are designated a and 8. In order to completely determine the texture of sheet material, it is generally necessary to use a combination of the two methods. The calculations involved in correcting the raw X-ray data for absorption effects and the combining of the data obtained by the two methods are very laborious and time consuming. To avoid the intensity corrections which arise as a result of the changing diffraction volume and path length within the sample other methods have been proposed. The Norton method utilizes a cylindrically shaped specimen cut from the sheet material. Since the rods have rotational symmetry, the absorption correction is constant for rotations about the sheet texture. Jetter and Borie' employed a spherical specimen to analyze the fiber texture of extruded aluminum rods. The spheres were rotated rapidly about the fiber axis to include a large number of grains in the X-ray beam and changes in intensity with respect to tilts of the fiber axis were measured. The absorption correction was constant for all angles and was neglected. The Jetter and Borie' technique finds excellent ap- plication to very fine-grained low-absorbing metals in which the entire sphere volume can contribute to the diffraction volume. In the case of low-absorbing metals, however, serious limitations on specimen thickness occur as demonstrated by Braggs due to de-focussing effects. Peak shifts may occur which negate the assumption that integrated intensities are proportional to peak intensities. These limitations in sphere size to the order of 0.5 to 1 mm for beryllium require that the grain size be sufficiently small to include a large enough statistical sample. The present paper describes the application of spherical specimens less than 1 mm in diam to the quantitative determination of pole figures for compression-rolled beryllium sheet having a grain size the order of 10 p. EXPERIMENTAL 1) Specimen Preparation. Two techniques for spark-machining beryllium spheres were tried. One involved the use of a hollow cylinder as a cutting tool. The tool was fed into the rotating cylindrical specimen as shown in Fig. l(a). The hollow cylinder was carefully aligned such that the axis of the cylinder and the axis of the specimen lay in the same plane and were 90 deg to each other. As the hollow cylinder was fed into the rotating cylindrical specimen, a spherical shape was formed as shown in Fig. 1. Alignment was very critical. Slight misalignment resulted in the formation of a barrel-shaped specimen instead of a sphere. A second technique involved the use of a cutting wheel shaped as shown in Fig. 2 with a groove of the desired radius. A section of the sheet specimen was first turned into a cylinder on the left part of the cutting wheel. It was then shifted to the right and a spherical specimen was turned as shown in Fig. 2. The axis of the cylinder lay in the plane of the sheet. Flats corresponding to the rolling plane of the sheet were used to grip the specimen during the machining operation and these served to identify the rolling plane of the sphere. 2) Rotation of Spec=. The spherical specimen is shown mounted on the G.E. single-crystal goniometer in Fig. 3. The knob A of the goniometer shown in Fig. 3 rotates the specimen about the pedestal axis. These angles have been designated as @ angles. The knob B rotates the specimen about an axis perpendicular to the pedestal axis. These angles have been designated as p angles. A device was made to automatically drive the single-crystal goniometer by means of two flexible shafts connected to the A and B knobs as shown in Fig. 3. The motor system was designed to rotate the knob A, thus rotating the specimen through angles of $I while the B knob remained stationary. After one complete

Jan 1, 1967

By Nelson Severinghaus

Following the end of hostilities of World War 11, a resurgence of industrial and home building has given impetus to the use of many products of the stone industry. Shortage and high prices of some building materials such as lumber have aided wider acceptance of materials such as concrete products which have been relatively plentiful and which have not risen so rapidly in price. Ingredients for many of these substituting materials come from the stone industries, often from by-products of stone operations. Most of the tonnage of the stone industry in the State of Georgia comes from granite and marble. There are extensive dimension stone operations in granite in the Elberton and in the Lithonia areas. Building and monumental marble from the Tate area has been used throughout the country. Cutting operations in both types of stone have their by-products in faulty blocks and in spalls. In the State there are three large crushed-stone plants utilizing granite, One near Camak, One near Lithonia and one at Stockbridge. All have had excess fines Or in in the past but this excess is largely disappearing with development of new uses. At times this "waste" has amounted to as much as 20 pct of the stone quarried. Handling Of this large tonnage from point of screening out to storage piles presented a costly problem and large areas were taken up by the piles. Crushed 'tone is generally sold with a a narrow margin Of price over cost, so any elimination of disposal cost or increase of income by marketing of by-products is highly desirable. By-products of Granite Dimension Stone It sometimes becomes difficult to differentiate between main product and byproduct. In the cutting of granite dimension stone in the Lithonia district of Georgia, a considerable quantity of remnants of Uneven shape and size is produced. The larger of these pieces have long found use as building rubble, particularly for retaining walls and building foundations (Fig I), They are broken down to one man size by plug drilling and wedging and by hammer. In recent times, demand for this former by-product has grown so that quarries have been opened for the production of rubble as a main product. Local masons have attained skill in using these irregular shapes to form economical and attractive walls. Areas such as Elberton, Georgia, which do not have a large building market nearby, tend to accumulate piles of large pieces of reject stone. When a road job or other local construction offers a quantity market for crushed stone, a portable crusher works this material down to crushed aggregate. Spalls and finer chips from granite stone-cutting operations have generally found their way into crushers and thence to the many uses for crushed aggregate. One company near Lithonia started marketing the smaller by-product crushed sizes for chicken grit about ten years ago. This use has grown to nation-wide distribution and the tonnage is now so great that they have opened a large quarry with

Jan 1, 1948

By Nelson Severinghaus

Following the end of hostilities of World War 11, a resurgence of industrial and home building has given impetus to the use of many products of the stone industry. Shortage and high prices of some building materials such as lumber have aided wider acceptance of materials such as concrete products which have been relatively plentiful and which have not risen so rapidly in price. Ingredients for many of these substituting materials come from the stone industries, often from by-products of stone operations. Most of the tonnage of the stone industry in the State of Georgia comes from granite and marble. There are extensive dimension stone operations in granite in the Elberton and in the Lithonia areas. Building and monumental marble from the Tate area has been used throughout the country. Cutting operations in both types of stone have their by-products in faulty blocks and in spalls. In the State there are three large crushed-stone plants utilizing granite, One near Camak, One near Lithonia and one at Stockbridge. All have had excess fines Or in in the past but this excess is largely disappearing with development of new uses. At times this "waste" has amounted to as much as 20 pct of the stone quarried. Handling Of this large tonnage from point of screening out to storage piles presented a costly problem and large areas were taken up by the piles. Crushed 'tone is generally sold with a a narrow margin Of price over cost, so any elimination of disposal cost or increase of income by marketing of by-products is highly desirable. By-products of Granite Dimension Stone It sometimes becomes difficult to differentiate between main product and byproduct. In the cutting of granite dimension stone in the Lithonia district of Georgia, a considerable quantity of remnants of Uneven shape and size is produced. The larger of these pieces have long found use as building rubble, particularly for retaining walls and building foundations (Fig I), They are broken down to one man size by plug drilling and wedging and by hammer. In recent times, demand for this former by-product has grown so that quarries have been opened for the production of rubble as a main product. Local masons have attained skill in using these irregular shapes to form economical and attractive walls. Areas such as Elberton, Georgia, which do not have a large building market nearby, tend to accumulate piles of large pieces of reject stone. When a road job or other local construction offers a quantity market for crushed stone, a portable crusher works this material down to crushed aggregate. Spalls and finer chips from granite stone-cutting operations have generally found their way into crushers and thence to the many uses for crushed aggregate. One company near Lithonia started marketing the smaller by-product crushed sizes for chicken grit about ten years ago. This use has grown to nation-wide distribution and the tonnage is now so great that they have opened a large quarry with

Jan 1, 1948

By G. A. Vissac, R. G. Minet, N. E. Sylvander

R. G. Minet—The authors' description of the remarkable progress made in the last few years in applying the fluidized solids technique to the problem of lignite drying and carbonization clearly demonstrates that engineering techniques available today may make many processes practical and profitable which a few years ago were considered otherwise. As pointed out in the article, the future of the carbonization step hinges on the value and utilization of low temperature tar. On paper, at any rate, this tar looks like a valuable raw material for the chemical industry to use. Some 50 to 60 pct may be converted to pitch for electrodes, roofing, road tars, and other valuable products; the 25 to 30 pct tar acids could conceivably form a basis for a new low cost resin or plastic of the phenolformalde-hyde type. Yet these materials are so new and dissimilar from available sources that much work must be undertaken by the chemical industry before they will be accepted. Now that the work of Dr. Perry and his colleagues has made a large supply of low temperature tar a real possibility, I would expect the chemical industry to accelerate its work in this field. On the basis of certain data available in the literature it appears possible to produce a more aromatic tar, although in smaller yield, by operating at temperatures in the range of 1300" to 1500°F. Operating a fluidized bed process for lignite at these conditions should be technically possible, at least, and could produce a tar having more familiar characteristics. I wonder if Dr. Parry would care to comment on such a possibility. Incidentally, in our own work on carbonizing coking coals in fluidized beds, using Ohio, Pennsylvania, and West Virginia high volatile bituminous coals, we have obtained yields which agree with the correlation given for tar yields vs moisture and ash-free volatile Btu. Our data are slightly under the line, but certainly in the range of the correlation. We have also obtained evidence in support of the authors' statement as to the effect of air on the process. In our pilot plant all the heat required for carbonizing is released by internal combustion of char in the fluidized bed in normal operation. We are also equipped to obtain all carbonization heat by external electric heaters on the shell of the carbonizer while introducing only an inert gas to the process. We note no difference in tar yield or characteristics between the two operations. In the case of the gas, however, it appears that some hydrogen is consumed by the air combustion. We would be interested in hearing in a little more detail about the hot dust and char handling problems at Sandow. Have the authors found char subject to spontaneous combustion? Have they ever tried a coking coal in their pilot plant? V. F. Parry (author's reply)—Production of a more aromatic tar by operation of the carbonizer at 1300" to 1500°F does not appear to be economical. 1) The capacity of a reactor operating at 1500°F would be 30 to 50 pct less than the capacity at 932 °F and the cost of processing would increase materially. 2) The cracking of tar vapors in a reactor requires appreciable time to complete the reactions and it is doubtful that considering the very short time of residence of tar vapors within the reactor (4 to 10 sec after evolution) the basic character of the tar would be changed significantly. This is indicated from the data reported in Table XIV. 3) General studies have shown that it is advisable to operate at the minimum temperature to produce the maximum tar and minimum gas. 4) Operating problems and the maintenance of vessels and reactors, and the hazards of handling hot char, increase with the temperature of carbonization. It is technically possible to operate at temperatures as high as 1500°F, but in my opinion it is not economical or desirable. We believe that the primary tar must be won in the simplest way and then processed alone to change its character for production of desired products. It is interesting to have confirmation of our observations on the reaction of air with the products of carbonization. The major reaction is with the char, fol-

Jan 1, 1957

By Bryan J. Travis, Thomas L. Cook

INTRODUCTION Our growing concern for adequate and secure sources of energy and minerals has stimulated vigorous exploration for new sources, research toward a better understanding of geological processes, and development of new extraction technologies. The need for control, or at least prediction, of subsurface fluid flow is important for many of these technologies for example: primary, secondary and tertiary recovery of oil; ground water and waste management; in-situ fossil energy extraction (oil shale, coal, tar sands); and solution mining of uranium, copper and other minerals. These technologies, especially the last two, are characterized by highly complex systems. A partial list of the physical processes occurring would include flow in porous/fractured media, multi-phase and multi-component flow with heat transport, chemically active fluids and soils, tracers, diffusion and dispersion, fracturing and dissolution. A great deal of understanding of how these processes behave and interact can be obtained from models. MODELS Theoretical models are valuable because they: 1) provide a frame of reference for interpreting results of laboratory and field experiments; 2) once validated by experiments, allow a variety of geometries, injection/production strategies, etc., to be examined (at relatively low cost) for efficiency and stability; 3) can provide guidance to the design of experiments and field operations. Most models are based on the fundamental principles of mass, momentum and energy balance. But from this starting point, many paths can be taken. For example, there is the theory of Payatakes (1973) which concentrates on the microscale dynamics. In this approach, the rock or soil matrix is represented by a complex of characteristic channels (such as periodically constricted smooth tubes). Detail of flow within the characteristic channel is calculated very accurately. A difficulty with this model is that description of a representative channel can require several parameters which may not be easily measured. Also, it is not clear how the channels can be combined practically to model a large scale flow. Another type of model is the "global" one described by Bear (1972). Here, the continuum equations for conservation of mass, momentum and energy are averaged over a distribution of pore channels, resulting in a set of conservation equations in which the small scale structure of the medium is replaced by quantities such as porosity, permeability, dispersion coefficients and tortuosity. This approach allows computation of large scale flows. However, additional constitutive equations are needed which relate averaged quantities such as permeability to observables such as local saturation, particle size distributions, and others. An important difference between models is the way they handle the momentum equation. Payatakes' model solves the full equation. In others, it is replaced by a simpler relation such as Darcy's law (valid for slow flow rates) or by Forchheimer's equation which extends Darcy's law to higher flow rates. These simple relations can nevertheless match a great deal of experimental data (Dullien 1975). The permeability term which appears in Darcy's law and in Forchheimer's expression has been related to other quantities such as porosity and particle surface area. The Kozeny-Carmen equation is a well-known example, valid for some ranges of porosity and particle sizes and for some materials. Several other semi-theoretical, semi-empirical formulations have been devised, none of which are entirely satisfactory. One goal of researchers has been the ability to predict permeability of a porous material from basic measurable quantities such as grain size distributions without recourse to adjustable parameters. This effort has proceeded from consideration of distributions of idealized, non-intersecting channels, to intersecting channels, to consideration of both distributed pore radii and pore neck radii. This last approach has been used successfully to predict permeabilities (ranging over several orders of magnitude) in sandstones (Dullien 1975). Additionally, studies on explicit networks of channels (e.g., Fatt 1956) and percolation theory (e.g., Larson et. al. 1981) have been used to examine interconnectivity effects in porous media with the hope of eventually being able to predict permeability accurately. To be of more than theoretical interest, a model must be compared s controlled laboratory conditions where boundary and initial conditions and relevant material properties can be accurately determined. Also, extraneous forces can be eliminated so that the interactions between processes of interest can be clearly seen and flow models can be vigorously tested. In contrast to the well-defined environment and

Jan 1, 1982

By A. R. Powell

Four, general methods have been used in the study of the decomposition of coal. The first has been directed toward the processes of coal formation, the second has been by means of microscopic studies, the third from the data of destructive distillation, and the fourth has made use of various solvents. Applying these methods to the sulfur of coal, it has been found that the organic sulfur of plant and animal life enters into the formation of coal and remains in organic combination in the final product. The inorganic sulfur is almost entirely combined as iron pyrites and marcasite. The infiltration of hydrogen-sulfide waters is doubtless a large factor in these combinations. Sulfates are found in very small quantities except where free oxygen has entered the coal strata. The mechanical mixing of detritus with the early coal material is another source of sulfur. In this case the sulfur is distributed in microscopic particles throughout the mass. In destructive distillation, a part off the sulfur comes off as hydrogen sulfide and various thiophen compounds, but this furnishes little information as to the nature of the sulfur compounds in the coal itself. The use of solvents has given valuable data concerning the sulfur compounds in coal. Fremy1 and later E. Guignet2 noted the action of alkaline solutions on coal after treatment with nitric acid and Anderson and Roberts3 showed' the presence of large quantities of organic' sulfur in the extract so obtained. In a study of the phenol extract of coal, Parr and Hadley4 found organic sulfur in the soluble organic material. These investigations proved the presence of organic sulfur in coal in addition to the inorganic forms, such as iron pyrites and sulfates. T. M. Drown5

Jan 9, 1919

By Lane D. Schultz, John D. McLennan, Jean-Claude Roegiers

During construction of the intake tunnels for a nuclear power facility in Ohio, evidence of a potential geological discontinuity was discovered. Assuming that the discontinuity might still prevail underneath the site, it was decided to measure the stress profile across the discontinuity. This information would be used to assess future stability on the basis of predicted shear stresses acting along the fracture. Seven intervals were hydraulically fractured to determine the magnitude and orientation of the stress tensor, in order to infer the shear stresses acting along the discontinuity. The formation consists of tightly interbedded shales. This, in combination with the shallow depths, would be expected to lead to horizontal hydraulic fractures -- a situation which generally provides limited information. Careful testing procedures, and meticulous interpretation, allowed the determination of the horizontal stress components as well as the vertical component, via the initiation and/or propagation of multiple fractures. The measured stresses fall within the range of stress magnitudes and orientation determined in other areas of the northeastern and north-central United States and in southern parts of Canada. In addition, a small stress gradient anomaly was recorded at depth. On a different scale, the measured stress regime is also evaluated in light of the regional geological setting.

Jan 1, 1982

By Richard Schellinger, Ronald H. Carlson, Robert D. Norris

INTRODUCTION A very important key to the success of an in-situ leach venture is proper choice of well field chemistry, in which type and concentration of oxidant plays a significant role. For proper design of well field and plant, an engineer must be able to estimate uranium production levels and their change with time. The rate controlling step in the uranium leach process is generally acknowledged to be the oxidation step (Goddard and Brosnahan, 1980; McKnight and Anthony, 1979; Mays, 1979). Uranium head grade is very dependent upon concentration of oxidant injected into the ore zone. If oxidant levels are too low, uranium production requirements will not be met; if levels ate too high, excess oxidant will be wasted in side reactions with gangue material and leach economics will suffer. To date, no reliable laboratory technique exists for generating data easily translatable to field conditions. Empirical correlations based upon lengthy field testing have been the major tools avail- able to the design engineer to date. During the past five years, FMC has developed lab- oratory techniques for studying uranium leach chemistry under conditions simulating as closely as possible the field situation. Both agitated batch and consolidated core leach procedures have been developed. Results of FMC agitated batch studies are described in detail in a companion paper (Carlson, et. al., 1980). This paper will focus on the technique developed for leaching consolidated undisturbed core under simulated down-hole conditions. Through use of a follow-up computer model (Winkley, 1980), generated data can be translated to expected field response, thus providing the design engineer with valuable information in a relatively short period of time. CHEMISTRY In addition to uranium (+4), other oxidant-consuming species present in uranium ore are iron sulfides and carbonaceous material. Iron sulfides are usually present in concentrations far exceeding those of the other two materials and, therefore, represent the major oxidant-consuming species present in uranium sandstone ore. Previous studies (Carlson, et. al., 1980) have shown that iron sulfides exist in both Texas and Wyoming ores as a mixture of pyrite and marcasite (FeSz); furthermore, uranium mineralization (existing as uraninite) was shown to exist as a fine granular material coating or imbedded in iron sulfide crystals and sand grains (i.e. quartz and feldspars). The leach chemistry of a uranium ore body can be described by the following equations using hydrogen peroxide (Hz021 as oxidant:

Jan 1, 1980

By Walter Miller

With returning prosperous conditions in all industries, oil-refinery engineering has found opportunity for the more extensive application of improvements developed during the several years of depression. The year has brought out little of an entirely new nature, but much in wider application of previous worth-while developments. The greatest volume of work done has been in modernizing the distillation and cracking units of existing refineries, particularly by substitution of combination skimming and cracking units for older equipment, and the installation of cracking plants in smaller refineries where formerly only skimming was practiced. A number of entirely new refineries were installed during the year, two of the most important being the 20,000-bbl. refinery by the Atlantic Refining Co., at Atreco, Tex., and a 12,000-bbl. plant by the Wilshire Oil Co., at Norwalk, Calif., these two embodying some of the latest developments in cracking and treating. Total refining capacity for the United States is now reported as being something over 4,000,000 bbl. per day, but a movement is on foot looking to a complete revision of these figures, as experience has indicated not only some overstatement of capacity of equipment but that considerable equipment is included which because of obsolescence and location will probably never be run again. The 3,000,000-bbl. figure which the industry reached during the year's high consuming period required the operation of probably 95 per cent of the country's efficiently usable capacity. Cracking and Polymerization There were no new outstanding developments in the cracking field, progress being made largely in the further refinement of known principles. Improvements in furnace design and operation have been largely in permitting closer control of the heating curve through the cracking-tube system, assisting in more uniform yield and in the lessening of coke deposition, and permitting longer trouble-free operating time as well as reduction in furnace-maintenance cost. Actual operating polymerization capacity has been increased little during the year, but a number of projects have been started, some nearing completion, the production from which will be available during 1937.

Jan 1, 1937

By Merlyn B. Buhle

FOR the past 20 years electrical earth resistivity exploration has been used in Illinois in many phases of study undertaken by the State Geological Survey, chiefly in locating and outlining deposits of water-bearing sand and gravel from which to obtain ground water for municipal and industrial supplies. At least 43 municipalities in the state derive their total water supply from deposits of sand and gravel discovered by resistivity methods. These deposits occur in both Quaternary and preglacial valleys and within much of the glacial drift which covers .a large portion of the state

Jan 4, 1953

By A. B. Kinzel

IT has often been stated that the steel industry did no research or development work in the decades preceding 1920. If restricted to organized research on the quality and field of application of structural and engineering steels, this statement may be true. But the industry did conduct a vast amount of process research during this period, although some of the projects were not carried out as separate organized research programs. Securing a low cost of tonnage production was the sole problem receiving serious attention from the industry prior to 1920, and today this is still the major problem. Those in the industry deserve much commendation for the important increase in production capacity per dollar invested and for the markedly lowered cost of production. In recent years, a distinct change may be noted in the attitude of the steel industry toward research involving its product. With the advent of high-speed machinery both in the manufacturing and transportation industries, steel as a quality engineering material has come to the fore. In the past, high-quality carbon steels and alloy steels have been introduced over a period of years, largely at the insistence of the consumer and partly prompted by research carried out by those interested in the use of the alloys. The commercial introduction of these materials made slow progress.

Jan 1, 1935

By A. R. Ledoux

I WAS wondering whether we were going to adhere to our text. It seems to me that we are having a very remarkable meeting of mining engineers this year, because no matter what the texts may be that are assigned to us, we get back toward something higher; we turn to the consideration of questions of ethics, and of applied Christianity. Yesterday we listened to the most eloquent and remarkable address by Mr. Rickard in memory of Dr. Raymond, and it was told us that he was to speak about Raymond's achievements as an engineer. He did say considerable on that subject, but he was himself carried away with the spirit of the man and moved us all by his portrayal of Dr. Raymond's continued and fruitful labors for the betterment of mankind-that is to say his religion. Our President asked me if I would say something this afternoon and I find in the bulletin that the text of the discourses which we are to have here this afternoon is "International Cooperation in Mining in North America." But again I find that the eloquent speaker who has just preceded me has dwelt largely on ethical and spiritual cooperation rather than upon cooperation in mining. That is, cooperation as men, rather .than solely as engineers. The imaginary line dividing Canada from the United States, unmarked by fort or military post, was mentioned by a previous speaker. There are going to be in the future, I am sure, fewer entanglements of the barbed wire of tariff discrimination along our border-to that end let us cooperate. But there has always been a reciprocity in men. A Canadian conceived and created our great transcontinental line, the Great Northern Railway; an American made the Canadian Pacific what it is. In mining and metallurgy, American engineers, backed by American capital, have built up great Canadian industries while Canadian experts have developed some of the resources on this side of the line. They have done much more than develop our resources: some of them have been our leaders in sympathy for labor. It is therefore not a question of creating a spirit of cooperation, but of giving it freer scope and a fuller realization of fraternity-or, to use the .word now more common and of deeper significance-brotherhood.

Jan 4, 1919

By F. D. Rosi, C. A. Dube, B. H. Alexander

WHEN a deformed polpcrystalline metal is heated to a sufficiently high temperature, a recrystallized structure develops which consists of small, essentially stress-free grains. This transformation is referred to as primary recrystallization. Under certain conditions, on prolonged annealing of the specimens, a type of grain coarsening occurs in which a small number of grains commence to grow at various points by devouring the neighboring finegrained primary structure, which, in itself, exhibits a marked stability toward normal grain growth. This grain coarsening process has been referred to by Burgers' as "secondary recrystallization" or "exaggerated grain growth." Although much work has been done on recrystallization and growth processes, present knowledge of the factors which determine the occurrence and growth of secondary grains is inadequate for the advancement of a theory which accounts for the observed characteristics of this recrystallization phenomenon. In this respect, it would be important to make measurements of the velocity of growth of these large secondary grains. The early work of Feitnecht2 on aluminum showed that the size of secondary grains increased with temperature and time, suggesting that such measurements would be possible. More recently, Burgers1 found that the growth velocity of these grains in aluminum was constant over a large time interval, as is generally found for the growth velocity of primary grains in a uniformly deformed test piece.3-5 It is reasonable to expect that the determination of the activation energy of the secondary growth process might lead to a better understanding of the underlying atomic mechanism. This investigation, therefore, is one of a series primarily designed to measure the growth velocity of secondary grains at various temperatures for silver, copper, and aluminum. It is hoped that these studies along with those of orientation relationships, will establish a sound basis for theorizing as to the origin and nature of the secondary transformation. Experimental Procedure The metal used in the present investigation was high-purity silver (999.9 fine), which was supplied in the form of cold-rolled plates 0.250 in. thick. These plates were annealed at 500°C for 1 hr and then straight-rolled to a thickness of 0.04 in. in three reductions of approximately 45 pct, followed in each case by an anneal at 450°C for 1/2 hr. The 0.04 in. sheets were given a final reduction of approximately 50 pct, which resulted in a thickness of 0.02 in., thereby insuring two-dimensional crystal growth. Individual specimens of this material about 1x3 cm were used for all heat treatments, unless otherwise noted. The annealing was carried out under an atmosphere of argon in an Inconel tube furnace whose temperature was controlled to within -+2°C. Metallographic examination of the secondary transformation was accomplished by mechanically polishing the specimens on one side to approximately one half their thickness through 2/0 metallographic emery paper, and then electrolytically polishing in a solution of potassium ferrocyanide and sodium cyanide. With a current density of approximately 20 amp per sq dm, the time required to obtain a satisfactory surface varied from 3 to 5 min. Standard potassium bichromate was used to etch the electrolytically polished surfaces. A heavy etch with this solution produced a sharp contrast between the secondary grains and the fine-grained primary structure, darkening the latter while leaving the large secondary grains bright. All area measurements of the secondary crystals were made with a planimeter on enlarged tracings of the grains.

Jan 1, 1953