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By M. M. Mebta, G. W. Dean, W. H. Somerton

With the advent of underground heating operations, interest has developed in the alteration of rock properties by high-temperature treatment. In the present work a number of sandstones were heated to temperatures in the range of 400°C to 800°C under both atmospheric and simulated reservoir pressures. Pertneabilities increased by at least 50 per cent and sonic velocities and breaking strerlgths decreased by an equivalent amount. Differential thermal expansion and other reactions of constituent min-era1 grains are the causes of these alterations. INTRODUCTION In the underground combustion of petroleum reservoirs, temperatures of the order of 600C are reported to have been reached in the combustion zone.' At this temperature rocks are subject to extensive thermal alteration. Temperatures of this magnitude and higher may also occur in subsurface formations when subjected to bottom-hole heating, thermal drilling operations, and underground nuclear explosions. Temperatures of this magnitude might also be generated by conventional rock drilling methods at points of bit-tooth contact. In earlier work, the permanent deformation of rocks resulting from heating was reported. Major structural damage of rocks occurs due to differential thermal expansion of mineral constituents. A number of mineral alterations including crystal inversions, loss of water of crystallization and dissociation, may also contribute to changes in physical structure and properties of rock. In the present work, samples of three typical sandstones were heated to several temperatures up to a maximum of 800C and then allowed to cool to room temperature. Heating was done under both atmospheric pressure and simulated reservoir pressure conditions. Physical properties of the samples were measured before and after heating and comparisons made. Measured properties included permeability, sonic velocity, breaking strength and fracture index. Changes in physical properties were compared to changes in mineralogical characteristics as determined by thin-section. X-ray diffraction and chemical tests. EQUIPMENT AND PROCEDURE Two outcrop sandstones (Bandera and Berea) and one sub-surface sandstone (St. Peter) were selected for the tests. These samples have a wide ranee in composition and physical properties as shown in Table 1. The first series of tests was made on 2-in. diameter by 5-in. long test specimens. Test specimens used in all later work were 3/4-in. diameter by 1 1/8-in. long, this being the specimen size required for heating at simulated reservoir pressures. After careful washing, the cores were oven dried at 100 ± 5C for a minimum of 24 hours before the tests were run. Test specimens were heated in an electric furnace at a constant rate of temperature increase of 3C per minute. When maximum temperature of the run was reached, the sample was allowed to soak for one hour. The furnace was then cooled to room temperature at the same rate of 3C per minute. The entire heating operation was designed for reproducibility without subjecting the test specimens to excessive thermal shock. For samples heated under simulated reservoir pressures, a pressure cell designed by Dean was used (Fig. 1).3 The core sample was inserted into a thin-walled (0.006 to 0.01-in.) copper cup which was then mounted in a high-pressure cell. Provisions were made for the application of internal pore pressure as well as confining pressure. Tests showed that the thin-walled copper cup closed tightly around the core and satisfactorily transmitted confining pressure to the core. The core was heated by placing the entire cell into the electric furnace. The heating program was the same as that used in the atmospheric pressure runs: tempera-ture rise of 3C per minute to maximum temperature of the test, soaking at maximum temperature for one hour, and cooling at a rate of approximately 3C per minute. The cell was designed to withstand 5,000 psi at 1,000C. However, since it was considered likely that repeated heating and cooling would in time weaken the steel, 2,000 psi at 850C was set as a working limit. In the present series of tests, the pore pressure was held constant at 750 psi and the confining pressure at 1.500 psi. The pressure source was a high-pressure nitrogen tank. The two pressures were controlled manually but are accurate well within ± 50 psi.

Jan 1, 1966

By J. A. Roberson, Robert A. Rapp

From the observation of platinum wire marker movement in the oxidation of columbium at high lemperatures and low oxygen pressures, predonzinant cation diffusion in CbO, has been demonstrated. The Cu,0 molecule was used as an oxidizing species to study the nature of the porous scale and the location of the reduction site in the oxidation of colum-bium. The Cb205 scale contains microporosity and forms by alternate ionic diffusional growth and fracture. The oxidation of columbium at high temperatures and very low po, results in a relatively compact and protective Cb205 layer. THE observation of marker movements during oxidation is one means for the identification of the mobile ionic species in an oxide lattice. Previous marker experiments in the oxidation of columbium have all resulted in the markers being found on the outside surface of the Cbz05 scale. The Cr203 powder markers of Klopp et a1.,' the gold film marker of Kofstad and ~jijllesdal,' and the platinum wire marker of Cathcart et a1 .3 were found at the oxide/gas interface for oxidation temperatures ranging from 450" to 120O0C. However, in all experiments relatively high oxygen pressures were used. As discussed by Mrowec, even the interpretation of marker experiments in simple scales containing only one compound is not without ambiguities. In brief, it can be said that a marker may be found almost anywhere in the scale layer if the metal oxidizes by cation diffusion through the scale; the position of the marker depends upon morphological happenings in the scale. When considering marker movement in a polyphase scale one must proceed with extreme caution. For example, in the past (and present) work markers have never been found at the columbium-scale interface, and one might infer that the oxygen ion is mobile in CbO and CbO,. However, only trace quantities of CbO and CbOz have been present on any of the specimens, so no firm statement is justified on this basis. Despite previous experimental work, considerable doubt still exists concerning the role of the oxides CbO and CbOz in the oxidation of columbium. The identification of the mobile ionic species in CbO and CbOz from the observation of platinum wire markers was one goal of the present investigation . The linear kinetics of columbium oxidation at high temperatures (T - 1000°C) suggests that the Cbz05 scales which form on columbium are porous. From mercury absorption measurements on a Cbz05 scale formed at 500"C, Aylmore et al.' reported a minimum volume fraction of connected voids equal to 0.15. While these scales often appear to be quite porous when viewed in metallographic cross section, they are so brittle that metallographic preparation is likely to exaggerate any porosity originally present. In this investigation, porosity developed during the oxidation of pure columbium and present at the high temperature was detected by oxidizing specimens in sealed evacuated capsules containing large compacts of mixed copper and CuzO powders. wooda has demonstrated that the CuzO, or (CuzO),, molecule is volatile and that oxygen is transferred by the CuzO molecule from a Cu/CuzO mixture to materials having a greater affinity for oxygen. For each molecule of CuzO that is reduced at a sink for oxygen, two atoms of copper are deposited. Quantitatively, essentially all of the oxidation carried out by a Cu-Cu20 compact results from a displacement reaction involving the CuzO molecule. When a metal which oxidizes to form a porous scale is exposed to the CuzO vapor, the CUZO molecules are reduced in the pores leaving a deposit of metallic copper to mark the site of the reduction. This technique has the rather unique advantage that any copper-coated pores found in the scale are unambiguously related to the reduction site in the growth of the scale under consideration. Pores or cracks which form in a msition*- external to the reduction site or which occur as a result of cooling or handling of the specimen will not exhibit the copper deposit. EXPERIMENTAL PROCEDURE Marker experiments were made on columbium metal, and on pellets of CbO which had been pressed and sintered. Platinum wire markers (0.001 and

Jan 1, 1968

By A. G. Guy

Thermodynamic activity rather than chemical composition is basic to the analysis of diffusion. This is the essential conclusion reached by Darken1-3 and by Birchenall and Mehl.4 If so, it is reasonable to expect that diffusion calculations should be carried out using activities. This paper will illustrate a method of employing activities in analyzing interstitial diffusion. For interstitial diffusion (of carbon in iron and probably generally) the diffusion of the solvent atoms, volume changes, and other such complexities not explicitly provided for in the usual diffusion equations cause a negligible error of the order of 1 pct. Therefore it is relatively easy to test the validity of an analysis based on activities in the instance of interstitial diffusion. The mathematical treatment of the more complex substitutional diffusion could be simplified once the adequacy of the activity method had been established for substitutional diffusion. Thus the present work has the purpose not only of providing a superior analysis of interstitial diffusion but also of indicating a possible approach to the more important question of an adequate treatment of substitutional diffusion. Development of the Diffusion Equation Although activities are convenient quantities to determine experimentally, they are derived from the more fundamental fugacities.9 Possible confusion in using activities can be avoided by basing equations involving their use on the relationship, dP = -D1d/ax dt [I] where, dP = the number of grams of solute crossing one cm2 in the time dt sec. D, = the diffusion constant for use with fugacities; it is assumed to be constant at a given temperature, and has units of secs. f = the fugacity of the solute in the solid solution; the units are those of pressure, dynes per cm2. x = the distance in cm. Eq 1 can be considered to be the basic form of the first Fick Law for one-dimensional diffusion. In order to convert Eq 1 into an equation involving activities, a choice of a standard or reference fugacity, f°, must be made: then. a = f [2] where a is the activity corresponding to the fugacity f. However, the value of a is also determined by the relation, a = a\c [3] where a is the activity coefficient and c is the concentration. For a given value of a (such as a = 1) it is evident that the units used for expressing concentration will affect the numerical value of a corresponding to a given amount of carbon dissolved in y-iron. Since weight per cent concentration is so widely used, this unit will be adopted as the standard in this paper. When the value off given by Eq 2 is substituted in Eq 1, the first Fick Law becomes, dP= -D,f°dl [4] Since D,f° is constant (at a given temperature), the second form of Fick's Law can be obtained in the usual manner, -dt D'f° dx [5] where c' is the concentration in g per cm3. In terms of weight per cent concentration, c, Eq 5 becomes, dc _ 100 d2a Tt = T /f w [6] where p is the density of the solid solution and will be assumed to be constant. In order to simplify Eq6, it is necessary to consider the standard state, f°. Standard states are chosen for convenience. There appears to be one especially convenient choice for the analysis of interstitial diffusion. If the activity coefficient, a, is set equal to unity at infinite dilution of the solute, 100 then — 100D1fl° is approximately equal P to the usual diffusion constant in dilute solutions. This is true since the activity, a, in Eq 6 can be replaced by the concentration, c, with little error in an infinitely dilute solution.* Here f1° is the standard fugacity necessary to achieve this standard state. It is proposed that a diffusion constant Da' be defined, Da1=100/pD1f1° [7] where A is the metal whose diffusion is * The second derivative of a is equal to the second derivative of c in dilute solution only if -da/dr- is. zero. Although theory does not require this condition, in the systems C in Fe, and Zn in Cu, dc is in fact found to be essentially zero.

Jan 1, 1950

By G. W. P. Rengstorff, H. B. Goodwin

A method is described for purifying iron in batches of 150 Ib or more. Oxygen, carbon, nitrogen, and sulphur are removed from flakes of electrolytic iron by treatment in wet and then dry hydrogen. A special consumable-electrode arc furnace is used to remove hydrogen and to melt the flakes into ingots. A LTHOUGH iron and steel have been made and used for hundreds of years, there are still wide gaps in the knowledge of these metals. One reason for this is that the true properties of the base metal, iron, are not well known, simply because really pure iron has never been readily available for research purposes. Commercial iron, and even the "pure" irons which are readily available, are really complex alloys of iron with oxygen, nitrogen, hydrogen, carbon, sulphur, silicon, and other elements. With such materials, it has not been possible to prepare steels and other iron-base alloys in which all elements are present in exactly controlled amounts. It is an almost impossible task to determine the separate effects of each element or the intereffects of several elements unless alloys can be prepared containing only the desired elements. The ability to make controlled alloys of low impurity content is of far more than academic interest. It will assist in the study of such practical problems as the brittle failure of ship hulls or high pressure gas pipelines, determination of the factors which affect the deep-drawing properties of steels, the improvement of magnetic and electrical properties, the phenomenon of aging, and many others. In 1949, the American Iron and Steel Institute asked Battelle Memorial Institute to prepare high purity iron on a larger scale than had been attempted up to that time. The work was directed toward the preparation of iron as low as possible in carbon, oxygen, nitrogen, hydrogen, and sulphur because these are the contaminating elements of major interest in many research investigations on iron-base alloys. The initial goal was to prepare iron with not more than a few thousandths of one percent of each of these impurities. The purpose was to set up a "bank" of high purity iron on which researchers could draw when a supply was needed and which could be replenished from time to time as the stock became depleted. Of several possible purification methods, heating in hydrogen was selected as the most promising for the removal of both carbon and oxygen from solid iron. Metallic impurities are not removed by hydrogen. Electrolytic iron was chosen as a starting material because it is the most readily available form of iron low in metallic impurities. Decarburization and desulphurization were obtained by annealing in wet hydrogen at relatively low temperatures. The optimum temperature, as found by previous investigators,' is about 1400°F. This treatment also removes nitrogen. Deoxidation is favored by dry hydrogen and higher temperature. There is evidence from previous work that an anneal at 2200°F in dry hydrogen will deoxidize the iron, reduce the nitrogen content, and reduce the sulphur content. These facts suggested the use of a two-stage process: treatment in wet hydrogen followed by treatment in dry hydrogen. To carry out the purification process in a reasonable time, it was necessary that the iron be in thin pieces. Flakes of electrolytic iron were used. Because most research requires that the iron be in massive form, it was nccessary to melt the purified iron to consolidate it into large pieces. For this work, it was decided to prepare ingots weighing at least 15 lb by using a cold hearth arc-melting process in which the iron was melted in an inert atmosphere of argon or helium. This method of melting was selected because the water-cooled copper crucible is not wet by the iron and does not contaminate it as a refractory crucible would. Because the crucible is also the ingot mold, contamination from mold materials was also eliminated. Contamination from electrodes was avoided by making them from purified electrolytic iron. The melting procedure finally developed was an adaptation of the Kellogg electric ingot process.' Two batches of purified iron weighing about 100 Ib each in ingot form were prepared with analyses as shown in Table I. The remainder of this paper describes the procedures in more detail. In general, the process con-

Jan 1, 1956

By M. F. Burr, F. V. Lenel, G. S. Ansell

The mechanism of materials transport was studied in a model experiment in which a silver sphere was sintered to a silver plate under an applied external stress near 800° C. For this purpose the rate of growth of the neck between the sphere and the plate which is proportional to the strain rate of the creep process involved in a neck growth was determined by measuring the change in electrical resistance of the away. This rate of neck growth will depend upon the magnitude of the applied external stress. By measuring the rate just before and just after a change in the external load and therefore the applied stress, the relationship between strain rate and stress can be derived. For material transport by slip in a pure metal it is expected that the strain rate should be proportional to the 4.5th power of the stress, while for transport by diffusional flow the strain rate should be proportional to the first power of the stress. It was found that for stresses above 5 X 10' dynes per sq cm (70 psi) the exponent in the stvain rate-stress relationship was near 4.5 while for a stress of 0.7 x 108 dynes per sq cm (10 psi) an exponent of 1.8 was determined indicating that under the conditions of the experiment the transport mechanism for creep in silver shifts from diffusional flow to slip in the region of 0.7 x 106 dynes per sq cm (10 psi). The importance of these findings for an understanding of the mechanism of material transport in conventional sintering (without an external load) is pointed out. In a paper by Early et al.,' the mechanism of material transport during sintering was treated as a creep process. It was pointed out that two possible types of creep processes could operate during sintering. In one of these material transport takes place by vacancy diffusion due to a gradient in chemical potential. The vacancy sinks in this diffusion process may be either grain boundaries, as in Herring-Nabarro microcreep, or regions beneath a surface of small radius of curvature. The diffusive transport may be by volume, grain boundary, or surface diffusion. In the other mechanism, creep takes place by slip, i.e., dislocation motion with its rate generally controlled by dislocation climb. One method of distinguishing between these two modes of materials transport is to investigate the creep rate, i.e., the rate of material transport as a function of stress. For material transport by vacancy diffusion, the creep rate is proportional to the stress.' For creep by slip, controlled by dislocation climb, the creep rate is proportional to a power of the stress. For pure metals this power is 4.5;374 for dispersion-strengthened material a fourth power relationship can be derived.5 This difference in the stress dependence of the strain rate is illustrated schematically in Fig. 1, in which the logarithm of strain rate is plotted vs the logarithm of the stress for material transport in a pure metal by vacancy flux and by dislocation climb. The stress range in which the two types of material transport overlap would be expected to be relatively small. In the experiments described by Early and coworkers compacts pressed from spherical copper powder were sintered isothermally under an applied axial external load in a dilatometer. During sintering the magnitude of the applied external load was changed and the rate of axial shrinkage of the compact before and after the load change determined. In order to find the stress dependence of the strain rate the magnitude of the stress acting on the neck area between the spherical particles before and after the load change had to be calculated. This stress is the resultant of the stresses due both to the externally applied load and to surface tension. The stress due to surface tension is a function of the geometry of the powder compacts. It can be determined, at least for simple geometrical arrays,'76 but it is difficult to obtain exact values of the stresses for actual powder compacts when only average values of particle diameters and of neck diameters between particles are available. The calculation of stress and the strain rate-stress relationship is therefore only very approximate.

Jan 1, 1968

By H. C. H. Darley

The influence of particle size and concentration on the development of chip hold-down pressure (CHDP) was studied in an apparatus designed to measure the change of filtration rate during the first second of the filtration process. CHDP is controlled by the "bridging" particles (i.e., particles in the 50 to 0.2 micron range), whereas filter loss is controlled by the colloid fraction. The results indicated that a fast drilling fluid with a low filter loss could be obtained if the concentration of bridging solids and the viscosity were kept very low. A novel group of drilling fluids, which we have named colloid emulsions, was developed to meet the above requirements. These colloid emulsions are made by dispersing art oleophilic colloid in oil and emulsifying about 5 per cent of this dispersion in water or a dense brine. Good results have been obtained in field trials with emulsions which use asphalt as the oleophilic colloid. INTRODUCTION In recent years it has been found that fast rates of penetration can be maintained in hard formations by using "clear" water as a drilling fluid. In some cases, however, water cannot be used because the very high down-hole filter loss creates various difficulties in drilling, in logging, or in producing the well. It then becomes necessary to "mud up", which results in a decrease in drilling rate. The reason that mud decreases drilling rates is a complex subject which has been well covered by such authors as Garnier and van Lingen, Cunningham and Eenink,' and van Lingen.3 One of the principal factors involved is the tendency of the drilling fluid to develop a filter cake on the bottom of the hole. The pressure differential which develops across this filter cake opposes the action of the bit in dislodging chips from the rock. This pressure differential is referred to by Garnier and van Lingen' as the chip hold-down pressure, which is denoted by the initials CHDP in this paper. The work described in this paper was undertaken to develop a drilling fluid which would minimize CHDP but which would still have a low filter loss—in other words, a fluid which would deposit a filter cake on the sides but would lay little or no filter cake on the bottom of the hole. EVALUATION OF CHDP EXPERIMENTAL Conditions governing the growth of filter cake on the sides of the hole are obviously different from those on the bottom of the hole. On the sides of the hole, cake will form continuously but at a decreasing rate, until eventually the rate of growth will equal the rate of cake erosion by the mud stream.' On the bottom of the hole, each time a bit tooth dislodges a chip the cake is removed, a fresh rock surface is exposed, and the filtration process must start over again. Thus the CHDP is determined by the amount of cake which can form in the interval between successive tooth strikes at a particular spot, normally a fraction of a second. Our first step therefore was to study filtration rates over the first second or so of the filtration process. These tests were conducted in the simple type of dynamic filter cell shown in Figs. 1 and 2. In this cell the mud was filtered through a train of rock cores while rotating blades kept the mud flowing over the surface of the core. The procedure was to evacuate the cores to 0.05 mm of mercury, saturate with brine, and assemble in the holder under brine. The permeability of the core train was then determined. A plastic seal was placed on the face of the core train, and a rip cord was attached from the seal to one of the blades. At the start of the test, 500 psi was applied to the mud, and the meniscus in the capillary measuring tube was adjusted to zero. When the blades were started, t,he seal was ripped from the face of the core, and filtration began. The filtration rate was at first measured by photographing the advance of the meniscus in the capillary tube. Using

Jan 1, 1966

By R. R. Vandervoort, W. L. Barmore

Tensile creep experiments were conducted on high-purity, poly cvystalline rhenium from 1500" to 2300°C at stresses from 1500 to I0,OOO psi in a vacuum of 10-a torr. The apparent activation energy for creep was 60 kcal per mole, and the steady-state creep rate varied directly with stress to the 3.4 power. Dislocation substructure that developed during creep was studied by transmission electron microscopy. Possible rate-controlling deformation mechanisms are discussed. The creep behavior of most metals at elevated temperature can be represented by the following equation:&apos;&apos;&apos; t = Cf(s)(^)(s/E)nD [1] where i = steady-state creep rate, C = constant, f(s) = a function involving microstructure, s = applied stress, E = the average elastic modulus at test temperature, n = constant, D = diffusion coefficient According to this well-established relationship, metals with higher elastic moduli and lower diffusion coefficients should have greater creep resistance at the same stress and temperature and equivalent mi-crostructures. While no diffusion data are available, the diffusivity of rhenium should be less than that for most other refractory metals because of its high melting point and hcp crystal structure. The Sherby-Simnad relation for calculating atomic mobility in metallic systems3 predicts that the diffusion coefficient for rhenium is less than that experimentally determined for tungsten4 in the temperature region 1500. to 2200°C. At these temperatures the elastic modulus for tungsten5 is only slightly larger than the extrapolated modulus for rhenium.6 Thus, rhenium is a good possibility for a a high-temperature structural material, but few data on the creep of rhenium have been reported. This investigation was undertaken to study the high-tempera-ture deformation behavior of rhenium in detail. EXPERIMENTAL TECHNIQUES The material used in this study was consolidated from high-purity powder. After cold pressing the powder to a plate a in. thick, the billet was sintered in hydrogen at 2250°C for 24 hr. The plate was reduced to 0.100 in. by cold cross rolling with intermediate anneals at 1650°C for 20 min between passes. The plate was further reduced to 0.060 in. by unidirectional cold rolling with similar heat treatments between passes, and then finally stress-relieved in hydrogen at 1650°C for 30 min. Specimens tested at 1900°C and below were pretest-annealed at 1900°C for 2 50 hr. Specimens tested above 1900°C were pretest-annealed at 2400°C for 5 hr. The impurity content in the "as-received" plate was quite low, table I. Essentially no change in impurity levels was detected in specimens after creep testing. All creep tests and annealing treatments were conducted in a vacuum of 10-8 torr in a test furnace heated by a tungsten mesh element. The load was applied to the specimens through a bellows, and stresses were maintained to ±1 pct of the selected value by periodic corrections for changes in specimen cross-sectional area during creep and for changes in the bellows spring force due to load column extension. One-inch-diameter tungsten force rods were used in the hot zone of the furnace. Deformation at temperature was measured by optically tracking gage marks on the specimen. Temperature was measured by a calibrated optical pyrometer and was determined to ±5"C. Grain sizes were determined by the linear intercept method and specimens were examined in the "as-polished" condition, using polarized light. Specimens annealed at 1900°C had a grain size of 52 ± 5µ , and those annealed at 2400°C had a grain size of 148 * 11 µ. Pieces were cut from the gage section of creep-tested specimens and planed to a thickness of about 0.010 in. by spark discharge machining. Thin foils for viewing by transmission electron microscopy were obtained by electropolishing in a solution of 6:3:1 ethyl alcohol, perchloric acid, and butoxy ethanol, respectively, using the window technique. Bath temperature was —4OoC, and the cell potential was 35 v. The foils were examined in Siemens Elmiskop I, operating at 100 kv. RESULTS AND DISCUSSION In order to analyze the results from creep experiments, Eq. [I] is rewritten in the following form: <=Kf(s)ne-/RT [2] where K = constant, ?// = apparent activation energy for creep,

Jan 1, 1970

By H. R. Gardner

The heat treatmmt of plutonium was studied using the Jominy end-quenching technique commonly used for determining the hardenability of steel. Plutonium specimens were end-guenched from temperatures in each of the ß, y, d, d&apos;) and E phases. One series of specimens with a low-iron content, 165 pprn Fe, and another gvoup with a high-iron content, 678 pprn Fe, were used in order to study the effect of a Pu-Pu,Fe eutectic network on the hardness and micro-structure. Hardness traverses indicated no significant variations in hardness with either cooling rate or quench temperature. Metallographic studies indicated major effects on microstructure. Grain size was found to vary markedly with quenching temperature and cooling rate. It was determined that the Pu-PueFe eutectic network could be modified extensively by heat treatment, including spheroi -dization in the y phase and 6 phase below 413°C. An unidentified spheroidal inclusion was observed to go into solution in the delta and higher temperature phases. 1 HE element plutonium is unique among metals in that it has six allotropic forms in the solid state.&apos; These have been designated&apos; as the a, ß, y, d, d&apos;, and phases. The respective phase transformations occur at approximate temperatures of 122", 210°, 319°, 450°, and 480°C with a melting point at 640°C. With this number of phase transformations it becomes pertinent to consider the effect of heat treatment and cooling rate in the various phases on the microstructure and hardness of plutonium. To determine; the effect of a wide range of cooling rates, the Jominy end-quenching technique was applied to cylindrical plutonium specimens. In addition, since the presence of iron in amounts greater than 500 pprn is common in plutonium and results in a network of the Pu-Pu6Fe eutectic, it was decided to study heat treatment effects on two bomb reduced plutonium buttons with different iron contents. A low iron button containing 165 ppm Fe and a high iron button containing 678 ppm Fe were selected for this comparison. EXPERIMENTAL PROCEDURE Experimental Material. The cylindrical bars for Jominy quenching were cast from button stock in vacuo in MgO coated graphite molds. Metal pouring temperature was approximately 950°C and the molds were preheated to 300°C. The castings were machined to 0.5 in. diam. by 2.5 in. long cylinders. Chemical analysis and density data for the two groups of Jominy specimens containing different iron contents are presented in Table I. Except for iron, heats 19-12-1 and 20-2-1 are comparable within the limits of analytical accuracy. Representative specimens from the low-iron and high-iron bars were taken for metallographic examination. The low iron specimen was found to have extensive microcracking, Fig. 1. In addition, numerous unidentified spheroidal inclusions were present, Fig. 17. The average grain size of the low-iron plutonium is 0.068 mm, Fig. 4. In the high-iron plutonium, a Pu-Pu6Fe eutectic network is prominent, Fig. 7. The average size of the network is 0.100 mm. Unidentified spheroidal inclusions were also common in the high-iron plutonium. The average grain size of the high-iron plutonium is 0.036 mm. Experimental Technique. A Jominy end-quenching fixture was fabricated for glove box use. A 2.5 in. water height was used with an orifice of 0.250 in. ID. The orifice to specimen distance was maintained at 0.5 in. Annealing temperatures of 160°, 265°, 400°, 465°, and 535°c were chosen for the study of the effect of quenching from ß, y, d, d&apos;, and e phases on microstructure and hardness. During quenching, cooling curves were obtained from the Jominy specimens at distances from the quenched end of 1/16, 1/8, 3/8, 3/4, 1-1/4, and 2 in. Cooling rate calculations were made from the cooling curves for temperature intervals of 100° to 110° 160" to 170°, 330" to 340°, 420° to 430°, and 490° to 500°c. These temperature intervals were chosen

Jan 1, 1962

By C. W. Arnold, H. L. Stone, D. L. Luffel

The purpose of this research is to determine (I) the efficiency of small banks of enriched gar driven by methane in displacing oil from a porous medium and (2) the effects of variation in bank size and composition of that efficiency. Most of the experiments were conducted in a sand-packed tube 20-ft long and 1/2-in. in diameter. The hydrocarbon system generally used was methane, butane and decane at 2,500 psia and 160°F. The results of these experiments indicate that, in the regions contacted by the gas, a small bank of an oil-miscible gas driven by methane can displace all of the oil in a piston-like manner. If the enriched gas is of such composition as to remain immiscible with the oil, displacement of oil is less efficient than for the miscible case, and the gas bank travels through the sand with a velocity less than that of the driving gas. These data along with theories discussed imply that smaller banks and less total gas are required when the enriched gas and oil are miscible. INTRODUCTION Widespread application of enriched-gas drive to the recovery of oil rests upon a key factor — the use of limited quantities, or "banks", of enriched gas. At the present time, the value of liquefied petroleum gas or other enriching agents discourages their use in a continuous injection technique, or even in a large bank, except in a few isolated reservoirs. If small banks of enriched gas driven by methane were as effective in displacing oil as is continuous injection, the enriched-gas drive process might be applied to a larger number of reservoirs. Previous research on the mechanics of the enriched-gas drive process reported by Stone and Crurnpl and by Kehn, Pyndus and Gaskell has utilized continuous injection of enriched gas. This work has shown that two types of displacements occur. With gases containing sufficient intermediates. the oil is displaced misciblv and complete recovery is obtained from the regions swept. When gases are used which contain insufficient intermediate hydrocarbon for miscible displacement, oil is displaced immiscibly. In the latter type, selective solution of the intermediate hydrocarbons causes a swelling and reduction in viscosity of the oil and leads to an increased recovery over that obtained by dry-gas (methane) drive. The size of the enriched-gas bank necessary for efficient displacement of oil is determined by those factors which cause deterioration of the bank. A differentiation may be made between those factors which operate on a microscopic scale and those which act on a macroscopic scale. On the smaller scale, the enriched gas mixes in the direction of flow by diffusion and convection with the fluids immediately preceding and following it. On the larger scale, the gas may by-pass the oil by flowing through permeable streaks, by overriding the oil because of density difference, or by fingering because of unfavorable viscosity ratios. In such cases, the enriching material tends to mix with the oil both laterally and in the direction of flow. The increase in effective area available for diffusion and dispersion of the enriching components leads to a faster degradation of the bank and a need for a larger bank than is necessary for those cases in which no by-passing occurs. The effects of such macroscopic factors in the deterioration of enriched-gas banks have been reported in a separate paper by Blackwell, Terry and Rayne. The present study was confined to the factors which operate on the smaller scale, in particular to the behavior of banks of enriched gas in sands uniformly swept by the gas. Experiments were designed to answer the following questions. 1. Can small banks of enriched gas driven by methane be used to secure oil recoveries comparable to those obtained by continuous injection of enriched gas? 2. What is the optimum bank size (the minimum bank size necessary to obtain a recovery comparable to that obtained by continuous injection of the same enriched gas)? 3. How many total pore volumes of gas must be injected to obtain the maximum recovery when the optimum bank size is used? 4. What is the effect of varying the number of enriching components in a gas bank? This report describes the experimental investigations and discusses the results in terms of their significance to reservoir behavior.

By JOHN S. HEARDING

ON the Minnesota Ranges, 600 million tons of material have been moved in the past three years to produce 172 million tons of direct-shipping iron ore. Increasing wage rates and cost of equipment and supplies, coupled with the larger amount of waste material to be moved in comparison with the quantity of ore make it imperative that tile industry adopt all practices and methods which will enable it to move earth at progressively lower costs. Drilling. Prior to and during the war practically all blastholes drilled were 6-in. in diameter and put down by drills using strings of tools weighing from 2000 to 3000 lb. Present trends indicate that heavier drilling equipment making 9-in. holes wit11 3000 to 6000 lb tools will be more economical. Holes up to 12 in. diameter will be made with this equipment. Forging and hardening practices for bits to increase footage is receiving attention. One manufacturer expects to market 9-in. bits having sintered carbide inserts in the reaming and cutting edges. Oxygen and oil to burn holes in the rock are being tested for making blastholes at a considerably greater speed than can be obtained with a blasthole drill on the same size hole. To dale, however, the cost has been prohibitive.

Jan 1, 1949

By James Douglas

PROBABLY no well-informed engineer would ques¬tion the accuracy of the statement that the piece of equipment that comes nearest to being in universal use in modern hydrometallurgical and ore-dressing plants is the Dorr continuous thickener. The function of the device is to separate a thin mixture of liquid and solid particles into a thick pulp and a clear liquor. Another machine in wide use is the Dorr classifier, the purpose of which is to separate the coarse and fine particles in a pulp containing solids of various sizes. It is in recognition of the invention of these two devices and the vast amount of technical work in the successful application of them in the beneficiation of ores that the James Douglas Medal for 1930 has been awarded to John Van Nostrand Dorr. To gage the importance of the development of the thickener, particularly, it is only necessary to imagine the loss of time, capacity, and metallurgical efficiency that would result if all the Dorr tanks in the world were put out of operation for a day and replaced by the old methods of intermittent settling and decantation. Truly, the record is one of "distinguished achievement in non-ferrous metallurgy" that deservedly ranks the medalist with those who have preceded

Jan 1, 1930

"Butte is in many ways an ideal location for a mining school. The student lives in the atmosphere of his intended profession. By the time he has spent four years at the school and in the community he has a fairly clear idea of what kind of a business he is entering upon, and is freed from any illusions about its being a primrose path he is about to follow. The mines and mills and smelters are his lecture rooms in part, and the shovel, pick and drill form part of his equipment. Most of the students work in the mines during part of their school life, which serves the double purpose of assisting them financially and increasing their practical knowledge.The School of Mines is a state institution, amply endowed and exceptionally well equipped. The school is strictly technical and no attempt is made to prepare men for any other work but mining engineering. The mining men of the community take an active interest in the welfare of the school and are of much assistance in securing employment for its graduates.The teaching staff is entirely composed of men who have had practical, commercial experience in their various specialties, and no expense is spared in securing suitable men for the faculty."

Jan 1, 1913

By Donald R. Mason, Daniel F. O’Kane

DIFFERENTIAL thermal analysis measurements have been used to determine the ZnTe-In2Te3 pseudo-binary phase diagram. Since ZnTe and In2Te3 are both semiconductors, any intermediate compounds formed in this system should also be semiconductors according to the rules delineated by Mooser and pearson.1 The compound ZnIn2Te4 was first reported by Hahn et a1.2 and it has subsequently been prepared and characterized electrically by several workers. A brief summary of this work has been presented by Mason and O&apos;Kane3 who also report that the compound appeared to melt peritec-tically. The Zn-Te phase diagram has been investigated by Kulwicki4 who found that ZnTe has a melting point of 1290° + 2°C. The In-Te diagram published in Hansen&apos; contains significant errors, and has been redetermined by Grochowski et al.6 However, both sources agree that the melting point of In2Te3 is 667°C, with the latter authors reporting the previously observed solid-solid transformation occurring at about 550°C. Hahn ef al.2 reported lattice-parameter values for the ZnTe-In2Te3 system. The 67 mole pct ZnTe-33 mole pct In2Te3 composition was the only

Jan 1, 1965

GENTLEMEN : Herewith are transmitted the reports of your Treasurer and the Chairmen of your standing committees on Admissions, Membership, Papers and Publications, and Library for the calendar year 1931. To these reports you are referred for further details of the year&apos;s activities. Finances.-Depressed industrial conditions prevailing throughout the year were reflected in a substantial decline in current revenue. Aside from interest on sundry special funds (but including that from the Life Membership, Library, and General Reserve Funds) total receipts amounted to $168,274, compared with $194,636 in 1930. The principal items of decrease were $17,000 in advertising income from the monthly magazine MINING AND METALLURGY, and about $9,600 in dues and initiation fees. Of this shrinkage $4,000 is accounted for by decrease in the number of new members enrolled; and $5,600 by diminished income from current dues and arrearages. This naturally has coincided with an \ increase in delinquency and "drops" or suspensions for nonpayment of dues. The decline in advertising income, amounting to 38 per cent as compared with that of 1930, in general paralleled the experience of all technical and trade publications; and it is problematical whether 1932 will show as large a return from advertising as did 1931.

Jan 1, 1932

By John L. Burns

The object of this chapter is to present data concerning the effect of the introduction of relatively slight amounts of carbon and nitrogen into supersaturated solution in iron. The study is confined to the alpha temperature range of both the Fe-C and Fe-N systems. The age-hardening characteristics of these two systems are considered. These data are compared to those of other age-hardening alloy systems and a "classification" is essayed. A.—Relation of Lattice Parameter and Electrical Conductivity to Changes in Physical Properties Due to Aging of Fe-C Alloys Since Whiteleyl in 1927 showed that some of the iron carbide that is normally present in slowly cooled low carbon-iron alloys disappears on rapid cooling from just below the A, point, interest has been manifested in the possibilities of age-hardening in these alloys. Masing and Koch,~ and at the same time and independently, W. Koster,~ proved these alloys to be age-hardenable. A. A. Bates4 a little later also published an interesting paper on changes in physical properties due to the aging of low-carbon steels. Many other papers have appeared showing changes in physical properties in specific instances due to this same phenomenon.

Jan 1, 1934

Activity with the legislation proposing to liberalize War Minerals Relief Act has now started before the Committee on Mines and Mining of the House. They are considering House Joint Resolution No. 170, which brings out the fact that war minerals claims in excess of $15,000,000 had been filed but that a considerable portion of the claims are being denied because of the Attorney General&apos;s. interpretation of the Act. The resolution states that it was the intention. of Congress in passing the War Minerals Relief Act "that all producers of the minerals mentioned should be repaid such sums as they are in equity and good faith entitled." The Attorney General&apos;s opinion is that the request or demand must have been made on the claimant direct. The resolution provides. that all claimants "who in response to any personal, written or published request or demand from any of the Government agencies-mentioned-in said Act in good faith expended money in producing or preparing to produce any of the ores or minerals named-therein *-*-* and have heretofore filed their claims within the time and-in the manner prescribed in said Act" are to be reimbursed for the n t-losses-incurred.

Jan 12, 1919

By Sylvain Pirson

THE number of seismograph field crews employed in the active survey of potential oil territories is still on the increase, owing to the ever pending threat of a shortage in the supply of crude oil. It is to be expected that for years to come the seismograph will be responsible for discovering many new oil fields, both in wildcat territories and in deeper formations, and that the seismographic campaign will go on unabated. Yet improvements in instrumental design, in the field and interpreta-tive techniques, are brought about year after year, and lead to the reshooting of areas many times surveyed previously. Notwithstanding the experience gained by the past eight years of active work in reflection seismographic surveys, the results given by this method of mapping deep formations have in many instances been at variance with the information subsequently obtained by the drill. To overcome this shortcoming, geophysicists have used closer spacing of the shot points and closer control of the depth points. The method dis-cussed here is being used actively in the Mid-Continent region and endeav-ors to reduce the interpretation work to a mere mechanical technique, leaving as little as possible to the opinion of the interpreter.

Jan 1, 1937

By C. F. Tolman

Discussion of the paper of C. F. TOLMAN, JR., presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 401 to 433. Louis C. GRATON, Cambridge, Mass.-Of particular interest at this time is any paper that deals with chalcocite, the characteristic product of secondary enrichment and the copper mineral of greatest commercial importance, and that seeks to aid in the distinction between primary and secondary chalcocite-a distinction of much scientific and practical importance but one which thus far it has proved difficult to draw. The present paper on this subject by Professor Tolman, like the ,many preceding it which he and his colleagues at Stanford have published in the last couple of years, contains much of interest and suggestiveness. Without endeavoring at this time to review or comment upon Professor Tolman&apos;s conclusions in detail, I may say that many of them are in accord with the findings that my associates and I have been accumulating in the course of studying secondary enrichment in many of the copper deposits of the country. On the other hand, it goes without saying that in this comparatively new field of research or, at least, a field in which

Jan 5, 1916

By J. A. Herbst, G. E. Agar

Beginning with the second paragraph in the second column of page 148, this paper should read: The Reynolds number in Fig. 6 was calculated from the inlet diam and it is evident from the graph that above NR = 5000 the value of K2 is as it should be, a constant. The data10 shown in Fig. 7 was obtained for fluids flowing in pipes of diam D with sharp edged orifices of diam d. To be consistent with the representation in Fig. 6 the Reynolds number was calculated with the orifice diam d. These two sets of data show similar patterns and the variation in the orifice coefficient C is believed to account for the variability of the cyclone coefficient K2. The values of C given in Table IV are derived from K2 by conversion of units. C more nearly represents an equivalent orifice coefficient for a cyclone. Armstrong1&apos; showed that data reported by Chaston 12 and Elcox13 yielded values for C of 0.24 and 0.27, re- spectively, Dahlstrom&apos;s4 data gives a value of 0.22. As a consequence of the variability of the cyclone coefficient some caution must be exercised in substituting for Q in the split size equation.

Jan 1, 1967

By James H. Allen

The development of large diameter rotary drilling techniques and equipment in the last nine years has been the main factor for the rapid advancement made by this method of shaft construction. In 1959, less than 5000 ft of large diameter hole was drilled in the United States for the mining and construction industries. By 1967, large diameter hole footage had increased to 117,000 ft. Part of the increase in footage for holes drilled represents AEC requirements due to the discontinuance of atmospheric testing of nuclear devices. The increase in footage for holes drilled for the mining industry can be attributed to cost savings of shaft construction by rotary methods as compared to conventional blasting methods. Until the late 1950&apos;s most large diameter holes were drilled with positive displacement rig pumps or air compressors, direct mud or air circulation, conventional sized oil well drilling strings, and multipass reaming techniques. In some very soft formations it was possible to run a pilot bit with one or more hole openers in tandem to drill the hole in a single pass. The main problem with single pass drilling using tandem hole openers was in providing sufficient circulation fluid for proper hole cleaning through conventional sized drill pipe.

Jan 11, 1968