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By Josiah Royce

To evaluate chemically the sample of rock obtained by diamond drilling, it has long been recognized that the analyses of the two components of the sample, core and sludge, must be given appropriate influence in computing the average analysis of any unit of depth. The purpose of this investigation is to set forth what means are available for apportioning the effect of core and sludge on the final analysis, what variables affect the problem, and what combination of applied mathematics will closest approximate the truth under each condition as these variables proceed within their limitations. A drill hole is bored in iron ore exploration principally to test variations in rock composition with depth and is usually directed as nearly normal to the bedding of a horizon to be tested as possible. This practice has a tendency to minimize variation in composition laterally which in any event is not likely to be great. It is obvious that the opportunity for change in analysis of a particular rock is not statistically as great radially in a diamond drill hole where the distance in which such a change may occur is from 0.719 in. (EX bit) to 1.469 in. (NX bit) as there would be longitudinally even in a' run as short as 5 ft. Variations in composition of bedded or layered rocks are usually greater normal to the bedding than parallel thereto. Even in massive rocks, like porphyries, variations are functions of distance. Hence. in either case, variations along the hole are of greater effect than across it. Let us examine Fig 1 briefly to observe a cross section of a unit of depth of a typical diamond drill hole. If we neglect radial change in chemical composition, which we have seen is small compared to lengthwise variation, we can see that if core recovery was 100 pct, the core and its surrounding area, which would be recovered as cuttings (assuming 100 pct sludge recovery), must analyze the same if the sampling is perfect. This is the foundation of this paper, namely, that if core recovery is complete we may assume that the core constitutes as nearly as possible a perfect sample of the ground drilled. Now let us pass to the methods of weighting core and sludge in the final analysis and then develop each in turn. One might employ core analyses only, sludge analyses only, or apportion the influence of each by one of several methods. The most common apportionment is by direct proportion to relative theoretical vol- ' ume occupied by each component in the cylinder hollowed out by the drill, known as the Longyear formula. Another logical treatment would be to consider core and sludge in the final analysis according to the weight of each recovered. This procedure was elaborately set forth and refined by R. S. Moeh1man.l Then to be sure that we have embraced all the possibilities, we must admit that some other method or methods may be devised empirically or by mathematical maneuvers. Should a drill machine be capable of recovering 100 pct of the core in all types of rock, certainly core alone need be analyzed and no complicated mathematics are required; but although some companies have had fair success in obtaining high percentages of core in certain homogeneous ores on the Mar-quette Range, their same methods have proved disappointing on the Menominee, Cuyuna, and Gogebic Ranges where the iron formation often varies widely from flinty chert beds interstratified with soft hematite to wholly leached ore material composed of an unpredictable mixture of hematite and limonite with occasional zones of sugary, recrystallized chert. In spite of numerous mechanical improvements in core barrels, few drilling programs can count on complete core recovery. The sludge alone might be analyzed but for practical reasons this is inadvisable when core is obtained due to the numerous opportunities for contaminating or losing portions of the cuttings. The Longyear formula involves a weighting of the core and sludge in proportion to the theoretical volume of each, that is, where the volume of the core recovered is one-third of the total cubic volume of the cylindrical hole made by the drill, the analysis of the core is given one-third of the weight in the final analysis. This approach to

Jan 1, 1950

By D. B. McGilvra

ANY mining operation in the Altiplano of the Andean range presents problems and imposes obligations on the mining company not usually met with in the United States. The Aguilar mine is in a sparsely populated, semiarid region, 50 km by road from the Argentine State railroad station of Tres Cruces, Jujuy, Argentina. In starting an operation in such a location it becomes necessary for the mining company to prepare first for the needs of the required force of workmen and their families. This program calls for houses, schools, hotels, water, electric power, laundries, post offices, police

Jan 1, 1947

By H. T. Clark, S. Feigenbaum

The importance of measuring the temperature of molten steel in the open-hearth furnace has been recognized for many years. Poor temperature control may be costly to steelmaking operations and lead to a lowered quality of the steel. Low or excessive temperatures may shorten the life of the furnace, ladles and molds. Rates of reactions in the furnace and efficiencies of deoxidizers are known to change materially with a change in the temperature of the metal and slag. Ladle skulls and mold and stool stickers cause steel to be scrapped instead of being converted into useful products. Finally, the structure, segregation and surface condition of ingots are affected by the teeming temperature. Mill investigations of the effect of bath temperature upon steelmaking operations have been largely qualitative in character, based upon observations by practical melting men. The physical chemist has used the empirical information available and has reached reasonable and useful conclusions with respect to the various melting processes. The introduction of a reliable direct-reading pyrometer will permit accurate quantitative evaluation of the effects of temperature and should furnish a more rational basis for study of the thermochemistry of steelmaking. The problem is not merely one of making a small numbcr of temperature measurements in the open-hearth furnace. This has been done by several methods to a * Assistant Manager, Research and Development, Jones and Laughlin Steel Corporation, Pittsburgh, Pennsylvania. Issued as T.P. 2031 in MEtals Technology, June 1946; also in Open Hearth Proc., 1946. † Open-hearth Metallurgist, Jones and 1aughlin Steel Corporation, Aliquippa. Pennsylvania. degree of precision that was apparently satisfactory. Considerable effort by a number of investigators has been directed rather to the development of an open-hearth bath pyrometer that would be both accurate and practical for routine measurements. To be practical, the pyrometer should be inexpensive to operate; that is, the installation, operating and maintenance costs should be exceeded by the tangible benefits to the open-hearth operator. Temperatures from 2800' to 3100°F. are. encountered in the open-hearth furnace. The surface of the molten metal is covered by several inches of slag, which prevents direct observation of the metal surface for optical or radiation measurements. Both slag and metal are highly reactive at these temperatures and will attack to a greater or lesser extent any material immersed in them. Adequate protectioil of thermocouples, which of necessity must be brought to the temperature of the bath, has generally resulted in a large, heavy assembly made up of brittle materials, unsuited for handling on the open-hearth floor. The life of the equipment was short and maintenance was an important consideration. Earlier Work Any of a number of Physical Properties of liquid steel could conceivably be used a a basis for temperature measurement. Efforts to the present time, however, have been confined largely to measuring either the thermal electromotive force generated between two dissimilar materials immersed in the steel or the intensity of radiation from the surface of the steel. These

Jan 1, 1947

By E. V. Kleber, V. F. Novy, R. C. Vickery

The constitutional diagram for the gadolinium-cobalt system has been determined. Seven intermetallic compounds have been found at compositions corresponding to the follwing gadolinium-cobalt ratios: 3:1, 1:1, 2:3, 1:2, 1:3, 1:4, 1:5. The GdCor compound has a congruent melting point above 1600°C. whereas the remaining compounds melt incongruently. Eutectics exist at 16 wt pct Co and 84 wt pct Co, with melting points of 620° and 1260°C, respectively. PREVIOUS papers'" have recorded constitutional data for systems of gadolinium with iron and nickel. This paper presents data obtained on alloys of gadolinium with the remaining 3d transition element-cobalt. voge13 found that cerium forms, with cobalt, the intermetallic compounds; Ce3Co, CeCo, CeCo2, CeCo3, CeCo4, and CeCo5 Other workers4-' found the 1:2 compound in this series to exist in a C-15 (face-centered cubic) structure and the 1:5 compound to exist in a hexagonal crystal system. Comparison of earlier data with that now reported will be made subsequently. EXPERIMENTAL Methods of alloy preparation, annealing procedures, and experimental techniques have been previously reported.' The cobalt content of alloy specimens was determined volumetrically. RESULTS Microstructure—The alloy containing 10.5 wt pct Co corresponds closely to the composition of the first intermetallic compound Gd3CO. In Fig. 1 the microstructure is essentially single phase composed of Gd3Co which formed peritectically. The globular areas are remnants of the peritectic reaction which did not quite go to completion. A eutectic occurs between Gd3Co and the next higher compound GdCO, which is followed by a series of peritectic compounds. Fig. 2, an arc-cast alloy containing 20.2 wt pct Co, shows large primary crystals of GdCo etching either white or black (depending on crystallographic orientation), embedded in the eutectic. Similarly, in Fig. 3 at 31.2 wt pct Co, a compound, probably GdCo3, has separated from the melt. Subsequent peritectic reactions were almost completely by-passed as the alloy cooled, the residual liquid freezing as a fine eutectic. In the 47.5 wt pct Co alloy, Fig. 4, the high melting point compound, GdCO4, has solidified as massive, white-etching grains, which reacted with the liquid to form GdCo3 as the second phase. The microstructure of an arc-melted alloy containing 60.5 pct Co is complex, Fig. 5, and presents some difficulty in interpretation. The grey etching matrix is probably primary GdCO4. The dappled phase represents grains of GdCO5 which have separated from the melt on cooling. The discrete spots in this phase are eutectic liquid. Small light etching crystallites are probably GdCO5 formed by the incomplete high-temperature peritectic reaction. GdCO4 is retained in arc-melted specimens containing 70.5 wt pct Co, Fig. 6. White areas of this compound are held in a matrix of GdCO5 the appearance of which is mottled slightly by inclusions of the second eutectic in this system. The development of the spheroidized eutectic at high cobalt contents is depicted in Fig. 7 (80.3 wt pct Co) in which the white massive crystals are GdCO5 compound. Further development of this eutectic is seen in Fig. 8, the primary white phase here being pure cobalt. Thermal Studies—Differential thermal analyses and melting point determinations have yielded the data shown in Fig. 10. The high gadolinium eutectic, indicated by microscopy, was confirmed at about 16 wt pct Co, melting at 620°C . A eutectic also occurs at about 84 wt pct Co melting at about 1260°C. The thermal arrests at 8803 960°, 1060; and 1210°C,

Jan 1, 1962

By R. T. Hukki, P. Voutilainen

This paper describes a new apparatus for continuous wet fine-screening. Its preferred size range seems to be from 0.1 to 1 mm. The supercritical trommel screen is a short cylindrical trommel of wedge-bar type construction operated at a speed greater than the calculated theoretical critical speed and at a speed lower than the speed at which particles introduced into it will centrifuge. The paper describes results obtained with the prototype supercritical trommel screen in pilot plant scale. The results point to a high capacity and simultaneously to a high sharpness of screening. Finally, an analysis is presented of the forces acting in screening on a supercritical trommel screen. In the era of high speed, high capacity processing of raw materials the conventional slowly rotating trommel screen is often considered a relic from the times passed. A typical trommel screen is the cylindrical trommel rotated about a horizontal or slanting axis at a relatively low speed. Its screening characteristics are well known. Trommel screens of various types of construction, methods of operation, performances and other characteristics have been described in detail by Taggart.1 The theoretical critical speed of a trommel screen is defined by the same well known equation as that applied for grinding mills: where ncritical = the numerical value of the theoretical critical speed in rpm, D 1 = the inside diameter of the trommel in feet, and D2 = the inside diameter of the trommel in meters. ncritical corresponds also to the centrifuging speed provided that the coefficient of friction f between the trommel surface and the outer layer of the charge is = 1.0. In a general case: From Eq. 2 it is seen that in all cases where f < 1.0 the centrifuging speed of the trommel is greater than the theoretical critical speed. The supercritical trommel screen concerns screening operations within that speed range which is between the theoretical critical speed defined by Eq. 1 and the centrifuging speed defined by Eq. 2, under conditions such that the coefficient of friction f<1.0. It is reported by Taggartl that the optimum speed of a conventional cylindrical trommel screen 36 in. in diam was experimentally found to be about 16 rpm. From Eq. 1, the critical speed of this trommel is 44.2 tpm. The indicated optimum speed corresponds to (16/44.2) x 100% = 36.2% of the theoretical critical speed. The optimum speed range based on information available seems to vary from 33% up to 45% of the theoretical critical value. The trommel screen operated at a supercritical speed: operates at a speed greater than the calculated theoretical critical speed; operates at a speed lower than the speed at which the charge introduced into it will centrifuge; operates within the supercritical speed range in such a way that the coarse fraction of the charge must slide in respect to the inside surface of the trommel; the outer layer of the said fraction next to the screen tends to proceed in the same direction as any selected point on the trommel surface, but now at a lower speed, and indeed at a subcritical speed; allows to a certain degree adjustment of the maximum determining particle size x of the fine product simply by a variation of the speed of the trommel within the supercritical speed range. With increasing trommel speed, finer and finer material only will get the opportunity to find its way into the fine product while the screen opening remains constant. In conventional practice, the low speed trommel is generally used for sizing of coarse and medium coarse material, but seldom for fine screening. The characteristic feature of the product passed through the conventional trommel is that the determining size x of the biggest particle is barely smaller than the nominal size of screen opening. The supercritical trommel screen, on the other hand, is best suited for sizing of relatively fine material. Furthermore, the characteristic determining size x of the biggest particle in the fine product can be substantially smaller than the nominal width of the screen opening or slot. In the trommel screen best suited for the applications

Jan 1, 1965

By H. T. Clark, S. Feigenbaum

The importance of measuring the temperature of molten steel in the open-hearth furnace has been recognized for many years. Poor temperature control may be costly to steelmaking operations and lead to a lowered quality of the steel. Low or excessive temperatures may shorten the life of the furnace, ladles and molds. Rates of reactions in the furnace and efficiencies of deoxidizers are known to change materially with a change in the temperature of the metal and slag. Ladle skulls and mold and stool stickers cause steel to be scrapped instead of being converted into useful products. Finally, the structure, segregation and surface condition of ingots are affected by the teeming temperature. Mill investigations of the effect of bath temperature upon steelmaking operations have been largely qualitative in character, based upon observations by practical melting men. The physical chemist has used the empirical information available and has reached reasonable and useful conclusions with respect to the various melting processes. The introduction of a reliable direct-reading pyrometer will permit accurate quantitative evaluation of the effects of temperature and should furnish a more rational basis for study of the thermochemistry of steelmaking. The problem is not merely one of making a small numbcr of temperature measurements in the open-hearth furnace. This has been done by several methods to a * Assistant Manager, Research and Development, Jones and Laughlin Steel Corporation, Pittsburgh, Pennsylvania. Issued as T.P. 2031 in MEtals Technology, June 1946; also in Open Hearth Proc., 1946. † Open-hearth Metallurgist, Jones and 1aughlin Steel Corporation, Aliquippa. Pennsylvania. degree of precision that was apparently satisfactory. Considerable effort by a number of investigators has been directed rather to the development of an open-hearth bath pyrometer that would be both accurate and practical for routine measurements. To be practical, the pyrometer should be inexpensive to operate; that is, the installation, operating and maintenance costs should be exceeded by the tangible benefits to the open-hearth operator. Temperatures from 2800&apos; to 3100°F. are. encountered in the open-hearth furnace. The surface of the molten metal is covered by several inches of slag, which prevents direct observation of the metal surface for optical or radiation measurements. Both slag and metal are highly reactive at these temperatures and will attack to a greater or lesser extent any material immersed in them. Adequate protectioil of thermocouples, which of necessity must be brought to the temperature of the bath, has generally resulted in a large, heavy assembly made up of brittle materials, unsuited for handling on the open-hearth floor. The life of the equipment was short and maintenance was an important consideration. Earlier Work Any of a number of Physical Properties of liquid steel could conceivably be used a a basis for temperature measurement. Efforts to the present time, however, have been confined largely to measuring either the thermal electromotive force generated between two dissimilar materials immersed in the steel or the intensity of radiation from the surface of the steel. These

Jan 1, 1947

By R. E. Reed-Hill

A simple accurate graphical method for orienting fcc crystals using (111) slip traces on a single surface is described. Solutions placing the pole of the surface in a unit stereographic triangle are obtained using a Wulffnet, a (111) standard projection showing the four (111) planes, and a (111) standard projection ruled into unit stereogmphic triangles. The multiplicity of solutions is described in relation to this method. AN accurate, rapid single-surface technique for orienting fcc crystals, using (111) slip or twin traces, has been a matter of continuing interest, as evidenced by the periodic appearance of papers on this subject.&apos;-4 This note presents a new method possessing some advantages over those previously reported. It is an analog to the technique for hcp metals5 where the solution is based upon a stereographic rotation of the specimen surface on a (0002) standard projection that contains the planes of the possible features that might account for the observed traces. In the hexagonal solution, the axis of rotation is the basal-plane trace in the surface. In the fcc case, the axis of rotation is one of the observed ( 111) slip or twin traces. It has been observed that the solution is greatly facilitated if the indicated movements of the (111) traces during the rotation of the surface are plotted directly on a paper copy of a Wulff net as shown schematically in Fig. 1. The trace selected to represent the axis of rotation is assumed to fall at the north-south poles of the Wulff net. The directions of the other traces are then plotted as points at the proper angles around one-half of the basic circle of the net. The loci of points corresponding to the movements of these traces (directions) during a 90-deg rotation of the surface, about the polar axis of the net, are then easily and accurately drawn by following the appropriate small circles on the Wulff net. The solutions to the problem are obtained with the aid of a (111) standard projection of the (111) planes, see Fig. 2. This is normally a Xerox copy of a carefully drawn master made on high-quality tracing paper. The (111) standard projection is superimposed over the Wulff net and rotated about its center until the points of intersection of the loci of surface traces, drawn on the Wulff net, and the great circles representing the (111) traces, all lie along a common meridian of the Wulff net as demonstrated in Fig. 3. This latter great circle represents a possible position of the surface. The pole of this plane is then plotted on the (111) standard projection. Its location in a unit stereographic triangle may be readily obtained by superimposing (over the standard projection) another tracing paper (111) standard projection subdivided into unit stereographic triangles. The result of this last operation is shown in Fig. 4. MULTIPLICITY OF THE SOLUTIONS The maximum possible number of (111) traces on a single grain surface is four. Any one may be selected as the axis about which the surface is rotated. Corresponding to each such choice are three possible surface-pole orientations, related to each other by a simple 120-deg rotation about the pole of the (111) basic circle. This is a direct result of the threefold symmetry of the (111) standard projection. Since each of the four rotations will normally give a different set of three-pole positions, there are, accordingly, twelve possible solutions. Each of these twelve solutions places the surface pole in the same relative position in a stereographic triangle so that all are crystallo-graphically equivalent. Accordingly, only a single solution is required to obtain a basic orientation of the crystal. It should be noted, however, that the orientations obtained by reflecting* any of these twelve orien- *The reflected orientations may be obtained by a 90-deg rotation of the opposite sense to that shown in Fig. 1. This rotation places the correspond-ing trace loci in the lower hemisphere of the Wulff net rather than in the upper hemisphere. tations through the surface are also possible orientations that could account for the surface traces. Thus, a given set of four traces always corresponds to a pair of basic orientations related by reflection through the specimen surface. This ambiguity can only be re-

Jan 1, 1967

By R. H. Jacoby, V. J. Berry, R. C. Koeller

The experimental phase behavior of several field gas-condensate systems, one field volatile oil system, and a series of synthetic systems having gas-oil ratios from 2,000 to 20,000 scf/bbl stock tank oil was measured. The data were used to calculate the depletion performance of the field systems at their respective reservoir temperatures and of the synthetic systems at various temperatures. The results of the performance calculations were used to prepare correlations of total stock tank oil and separator gas in-place, and the amount of each recovered by primary depletion. Data needed to use the correlations are initial gas-oil ratio, initial tank oil gravity, reservoir temperature and reservoir pressure. The correlations presented should be useful for estiinating recovery from reservoirs producing volatile oils or rich gas condensates having gas-oil ratios from about 2,000 to 30,000 scf/bbl of stock tank oil. INTRODUCTION Prediction of depletion performance for gas-condensate reservoirs usually requires extensive laboratory work or lengthy phase-behavior calculations. For many small gas-condensate bearing zones the expense of such work is often not justified. Furthermore, where large holdings are involved, it is useful to have estimates of future oil and gas production in advance of the results of a laboratory analysis, even if such work is ultimately planned. For these reasons, it would be of value to have a method for rapidly estimating the depletion performance of gas-condensate reservoirs from the type of field data usually available. Few data on the reservoir depletion performance are available for the purpose of developing correlations. The increasing number of gas-condensate discoveries and the advent of high-speed computers have stimulated the development of methods for predicting performance. Such calculated performance data have been shown to be reliable and are becoming accepted as a basis for reserve estimates and for engineering studies. It therefore seems satisfactory to use results of performance predictions themselves for the purpose of developing the desired correlations. Such an approach is described in this paper. Several rich natural gas-condensate systems (gas-oil ratios of from about 3,600 to 60,000 scf/bbl) and one natural volatile oil system were studied (2,363 scf/bbl). In addition, to provide a more systematic basis for correlating purposes, a series of related, synthetic reservoir fluid mixtures was also studied (GOR&apos;s from about 2,000 to 25,000 scf/bbl). The purpose of this paper is to show how the recovery of oil and gas by primary depletion may be estimated from surface gas-oil ratio, reservoir temperature and pressure, and tank oil gravity. procedure Experiments Companion samples of gas and oil were collected from the high pressure separators in nine different fields at the time of their discovery. These samples were each recombined in accordance with the respective producing GOR to reproduce the reservoir fluids. Eight of these fluids, designated F-2 through F-9, were rich gas-condensate systems at the respective reser-

By F. Claisse, R. Angers

Self-diffusion in iron has been measured during rapid a-r transformations using a variant of the Kryukou and Zhukhovitskii diffusion method. The study was performed by thermally cycling iron foils (1 to 6 cpm) through the transformation (=910°C). Some foils have been subjected to over 1000 cycles and some have spent more than 15 pct of their total diffusion time in the process of transformation. The experimental results show that the a-r transformation has no measurable effect on self-diffusion in iron. The study is completed by a quantitative analysis of mechanisms which can affect the diffusion rate during the transformation. The analysis confirms the experimental results. SINCE diffusion is an important factor in many solid-state transformations, it is of interest to study how it is affected by the stresses generated during these transformations. Clinard and Sherby1&apos;2 were the first to make a study along these lines. They measured diffusion coefficients in Fe-FeCoV couples subjected to slow thermal cycling (1.5 cph) through the a-r transformation range. They found an enhancement of diffusion by a factor of about two. The purpose of the present paper is to report measurements of the self-diffusion coefficient of iron during much more rapid thermal cyclings (1 to 6 cpm) through the a-r transformation (-910°C). These more rapid cyclings produce higher strain rates during the transformation and should emphasize any possible influence of transformation upon diffusion. EXPERIMENTAL Iron foils, 25 to 35 µ thick, were cold-rolled from 99.92 pct pure iron and annealed in pure helium for 2 hr at 870°C; the resulting grain diameter was about 150 µ. Specimens 0.5 by 8 cm were cut from the foils and I7e55 was vapor deposited on one of their surfaces. A 38 gage alumel-chrome1 thermocouple was spot welded in the middle of one of the specimen long edges, Fig. 1. Two 38 gage chrome1 wires were also spot welded along the same edge on each side of the thermocouple; they were placed 2.5 cm apart and used for electrical resistance measurements. In order to prevent twisting and crumpling, the specimens were pinched between two quartz plates 0.1 by 1 by 7 cm and the assembly was close fitted into a 1 cm ID quartz tube. Four holes were drilled through the tube to let the 38 gage wires out: these were connected to the recording equipment by means of extension wires. 20-gage nickel wires fixed at both ends of the specimens were used to thermally cycle the foils by Joule heating. The above described device was placed in a 2.7 cm ID quartz tube which in turn was placed in a tubular furnace. Either a pure helium atmosphere or circulating hydrogen was used during the experiments. Specimens were subjected to thermal cycles between a minimum temperature To and a maximum temperature Tm at rates ranging from 1 to 6 cpm. This was obtained by maintaining the furnace at a constant temperature near the minimum temperature To and periodically passing an electric current through the specimen. Cooling was achieved by heat losses to the surroundings. The forms and periods of cycles were varied from one specimen to another; however, each specimen was subjected to one type of cycle only. The temperature and electrical resistance variations of the specimens were recorded as a function of time. The temperature curves were used for diffusion calculations while the electrical resistance curves were used to monitor the transformation and to determine its starting point and its approximate duration. Diffusion was measured by the method developed by Kryukov and zhukhovitskii3 and modified by Angers and Claisse.4,5 In this method a metallic foil is coated on one side with a radioactive isotope and the activity is measured periodically on both sides during the diffusion anneal. The following equation then holds: where: I1 Activity on the surface on which the deposit is made. I, Activity on the opposite surface. t Diffusion time. B Constant. D Diffusion coefficient. d Foil thickness including the deposit. G(t) A function of time; it is a second order correction term which is given graphically in Refs. 4 and 5. The diffusion coefficient D is found by plotting ln[(Il - I2)/(I1 + I,)] -G(t) against t; the resulting slope m leads to an accurate calculation of D through Eq. [2]. The effect of the a-r transformation on diffusion is expressed by the ratio DT/DU where:

Jan 1, 1970

By Bengt Helmerson

A new tankhouse was started in January 1959 at the Copper Refinery of the Boliden Co., Skelleftehamn, Sweden. In early 1961 a semiautomatic machine for looping and straightening of starting sheets was introduced to substitute previous manual operations. The machine as well as consequent, racking and handling is described. Finally, economic benefits achieved and new constructions for the future are discussed. HISTORY Tankhouse operations at the Boliden Co. &apos;s Smelter in Skelleftehamn started in 1932 on a scale that since then has been gradually increasing. In order to rationalize the operations, a new tankhouse was erected. It went into production in January 1959 and was designed for a yearly production of 35,000 metric tons at a current density of 16 amps per sq ft. Already from the beginning, however, the tankhouse has been run with a current density of 21.5 amps per sq ft, corresponding to a maximum capacity of 50,000 tons a year. During the time of planning of the new tankhouse, due consideration was given to the possibilities of mechanizing the operations. New ideas could be and were actually tested on full or pilot plant scale in the old tankhouse. In that way we developed a system for the cathode handling including washing, weighing, and transportation. A system using forklift trucks in combination with trailers and overhead cranes has been developed for transportation and racking of anodes and also for handling of anode scrap. With respect to the electrolyte, circulation and temperature control are partly automatic. Special attention was paid to the production of starting sheets, which operation normally requires a great number of man hours, and it was made the object of a particular survey as to the best ways of straightening starting sheets, attaching loops to the sheets, and so forth. As a result, a machine was designed during 1957-58 and built in our own shops. After a period of tests, the new equipment was put in operation commercially on the 10th of April, 1961. Since this date the machine has produced about 2 million starting sheets without interruption and has been the only source of looped starting sheets for the tankhouse. GENERAL DESCRIPTION Fig. 1 shows all the major parts of the system. These parts are: slitting machine with feeding table (I), standard roller leveler, type Ungerer (2), tilting roller table (3), conveyors for sheets and suspension bars (4, 7), storage of suspension bars (51, punching and stitching machine (6), two lift-turn-tilt tables (8) for discharging the starting sheets, two rack conveyors (9) for sheet assemblies. Included are a hy-daulic pump station and panels for pneumatic and electric controls. SLITTING AND STRAIGHTENING The machine is fed by hand by a man sitting in front of the slitting-machine table, Fig. 2. This operator inserts one sheet at a time into the slitter. After being trimmed, the sheet is automatically conveyed to the following step of handling, straightening. The slitting machine cuts away about 8 mm of the upper and lower parts of the sheet (in relation to its original position in the stripper section) for two reasons. The first one is to give the machine sheets of uniform dimensions; the second one is a matter of quality. Normally the starting sheets as stripped have a thick edge at the bottom end. This part would collect anode slimes and might also cause short circuits when inserted in the cells without trimming. The straightener used is of German construction

Jan 1, 1967

By H. S. Wang, Y. P. Gupta

Diffusion of zinc and germanium in liquid silver is measured in the temperature range 975" to 1400°C by use of the capillary-reservoir technique. The ex-perinzental results are discussed in terms of the fluctuation and the "hole" theories of liquid diffusion, assunzing the solute as a point charge equal to the difference in the valences of the solute and solvent atoms. The additional coulombic interaction term due to the excess solute charge is evaluated in terms of the Thomas-Fenni approximation. The theoretical and experimental results agree with both the fluctuation and "hole" theories of liquid diffusion. No perceptible effect on solute diffusion in liquid silver of the size difference between the solute and solvent atoms/ions is apparent. DIFFUSION in liquid silver of electropositive solutes indium, tin, antimony, and homovalent gold has been previously reported by Leak and Swalin1 and Gupta,&apos; respectively. These solutes have nearly the same atomic size but differ principally from one another in excess valence (+2, +3, +4, respectively). The observed differences in the temperature dependence and the rate of solute diffusion were explained in terms of an added coulombic interaction between the solute and the solvent atoms. In the case of diffusion of gold in liquid silver, the data were found to be consistent with an effective valence for gold of -0.85, as proposed by Le Claire.3 Recently, Wang and Gupta4 have reported a study of diffusion of ruthenium, iron, and cobalt in liquid silver. The results of diffusion of these solutes and their temperature dependence were found consistent with the hole theories and the fluctuation theories of liquid diffusion, if ruthenium, iron, and cobalt were diffusing in liquid silver with relative valences -2, -1.3, and -0.5, respectively, instead of -3, -3, and -2 as suggested by the relative position of these elements in the Periodic Table of Elements. Furthermore, the predicted valences for these solutes were observed to be consistent with the sparsely available information on the magnetic properties of some of the dilute alloys of copper and silver with these solutes. In theoretical calculations of solute diffusivity, the solute was assumed as a point excess charge equal to the difference in the valences of the solute and solvent atoms. Both the assumption of a point excess solute charge and the use of the Thomas-Fermi approximation to calculate the potential of a solute charge are less precise for the case of electronegative solutes. Therefore, it was not possible to infer from the data on ruthenium, iron, and cobalt an effect, if any, on solute diffusion of the relative differences in either the Period or the size of the solute and solvent atoms or the solute atoms themselves. A study of the diffusion of Period 4 elements, specifically zinc and germanium was, therefore, undertaken since zinc and germanium, respectively, have relative valences of +1 and +3 in liquid silver and the data obtained on diffusion of these solutes could be compared with the available data on diffusion of Period 5 electropositive solutes, indium, tin, and antimony in liquid silver. From such a comparison, it was hoped to learn something about the effect, if any, of the ion size or the structure of the ion core on impurity diffusion in liquid silver. EXPERIMENT The diffusion of tracer zinc and germanium in liquid silver was studied by the capillary reservoir technique, modified adequately for use at high temperatures. In principle, capillaries containing liquid silver

Jan 1, 1970

By Milton Glicken

THE airborne geophysicist is a busy man these days. In his plane he may have the airborne magnetometer, the airborne scintillation counter, and the airborne electromagnetic surveying system. Each of these is an independent tool, but all require additional auxiliary equipment for locating the aircraft in space: recording altimeters and Shoran or aerial cameras. Now there is still another piece of equipment, the airborne magnetic gradiometer, an accessory to the magnetometer. To understand its uses, consider the function of the magnetometer itself. Aside from detecting magnetic ore, the airborne magnetometer finds greatest use in spotting intrusions of igneous material. Where there is enough contrast in magnetic susceptibility of igneous rock and adjacent formations, it outlines the intrusion. Certain minerals also influence the magnetometer directly, but with the exception of magnetite and possibly one or two others, their effect is weak and can be detected only when there is sufficient ore and the magnetometer flight passes very close to it. An igneous intrusion of infinite depth with vertical sides is represented on a magnetometer record by an anomaly, as in Fig. 1. Amplitude of the high depends on susceptibility contrast of the igneous rock. Generally speaking, the edge of the intrusion lies below the point of inflection of the curve, and this point, where the curvature changes from positive to negative on the magnetometer profile, would be near A in Fig. 1, with a counterpart, of course, on the other side. Location of the contact is one of the principal objects of the survey, but finding the precise point is not always easy, as inspection of the curve near A will show. Mineralization is often found at the contact zones, as at B. Magnetic effects, if detected, may be small, as in B&apos;, and when superimposed on the anomaly due to the instrusion they are very difficult to discern and analyze. Furthermore, if these small fluctuations are to be perceived by the magnetometer the vertical scale should be large. This increases the slopes of the anomaly and makes detection of small deviations and inflection points even more difficult. The airborne magnetic gradiometer was designed to help overcome these difficulties. What it presents is the first derivative of the magnetometer record with respect to time, that is to say, the slope at any point. Fig. 2 represents an actual magnetometer record (solid line) with the corresponding gradiometer record (dashed line) superimposed. Both records read from right to left. Vertical lines on the original magnetometer record are automatic steps designed to keep the pen from going off scale. The slope of any curve is greatest at the point of inflection or point where the curvature changes sign, and this point is a maximum (or minimum) on the gradi- ometer. The chief advantage of the gradiometer is that maxima or minima are much easier to see and to locate precisely; hence an accurate location for the point of inflection can easily be found. Note that points C and D are more sharply defined than C and D&apos;. Similarly the small fluctuations of the original record, so important to the interpreter, are far more clearly shown at E, F, and G, than on the original record at E&apos;, F&apos;, and G&apos;. Though not necessarily highs and lows on the gradiometer, they do show up clearly what would take a painstaking analysis to detect on the original magnetometer record. Will the gradiometer have a particular configuration which indicates an orebody? Not necessarily. The total intensity curve, or original magnetometer record, can display an orebody in various ways, depending on dimensions, orientation, latitude, and composition, as well as on direction, flight height, and instrumental sensitivity of the traverse. Where the total intensity can take on so many different shapes the gradiometer must vary too. It is generally recognized that interpretation of total intensity magnetometer records requires an expert analysis; the gradiometer can be of considerable assistance to the expert but it does not replace him. Mechanism of the gradiometer is simple. A Leeds & Northrup recorder in the aircraft records the magnetic gradient simultaneously with the total intensity, which is on another recorder. Fiducial marks are put on both records simultaneously and the speed of the paper through the recorders is kept the same on both. This makes it possible to place one record over the other for direct comparison. In the laboratory the flights are positioned on a map. Maximum and minimum points on the gradiometer, which can then be posted on the map at their proper locations, may be expected to fall along a trend crossing the direction of flight. Trends should indicate the edge of an intrusion, or some other important features, and when superimposed on the total intensity contour map help greatly to locate the points of inflection, or line of zero curvature.

Jan 1, 1956

By William H. Breeding

The remarks that follow are based substantially on experience covering 45 years, 80% of which has been in placer work, rather than on a review of available literature. Most commercial placers have been deposited by the action of water. The richer and more- difficult-to-mine placers are those in the headwater areas where gradients are steepest. The most lucrative placers are generally in inter- mediate areas where volumes are greater, fewer boulders are present, and gradients are from 3% to 1-1/2%. The higher volume, lower grade placers are in the lower reaches of river systems where gradients are lower. Where gold-bearing rivers have discharged into the sea, wave action can concentrate values on beaches, past and present. Most of the rich, readily accessible placers were mined by our forefathers. Current opportunities exist: (1) in remote areas where infrastructure has been absent in the past, or development has been prohibited by adverse ownership - political or commercial; (2) in deposits that could not be mined by equipment available to our forefathers; (3) in deposits unidentified by our forefathers; (4) where the-price-of-product/cost ratio is substantially better than in earlier years; or (5) a combination of those factors. When I entered the placer business in the late 1930s, and subsequently, a prevailing opinion believed that glacial deposits should be avoided as irregular in mineral content and composition, and unrewarding to explore and develop; yet an operator has been mining a fluvio-glacial deposit profitably for the past 17 years. Rich buried placer channels, of ten called paleo-channels were worked in the last century, generally by hand methods, and under conditions that would be unacceptable today. Exploration and mining equipment now available make some of these channels attractive targets. Well-known examples are in California and Australia. The formation of a commercial placer requires a source of valuable minerals. Above primary deposits, there may be eluvial deposits formed by the erosion of gangue minerals and the concentration "in situ" of valuable minerals. Down slope from these deposits are the hillside or colluvial deposits, and below them are the alluvial deposits of redeposited material. Most of the great placer fields of the world are the result of several generations of erosion and deposition. Well-known examples are in California and Colombia. Gold is a very resistant and malleable material, and gold placers may extend for 64 or 80 km (40 or 50 miles) along a river system. Platinum is less malleable, but is very resistant to disintegration. Diamonds are extremely hard, and (especially gem diamonds) may be found over great lengths of a river system. Cassiterite is less resistant to disintegration, and tin placers seldom extend over two miles without resupply from an additional source or sources of mineralizaton. Tungsten minerals are generally more friable, and within a few hundred yards of the source disintegrate to the point that they are uneconomical to recover. Rutile, ilmenite and zircon placers generally result from the weathering of massive deposits, and may be encountered over extensive areas; most are fine grained and durable. What does a geologist or mining engineer look for in placer exploration? The old adage to look for a mine near an existing mine is still valid. You need a source of valuable mineral. Then you require conditions for concentration, which means a satisfactory gradient and/or other conditions that will permit heavy minerals to settle. Nicely riffled gravel, often called a shingling of the bars, is conducive to placer formation. Coarser gravel is logically associated with coarser gold. Excessive clay and/or high stream velocities in narrow channels can carry gold far downstream and distribute it uncommercially over a large area. When material is extremely fine, in situ weathering and concentration become more important. Placers frequently occur distant from lode mines, and one must remember that in a larger watershed the exceptional floods that occur once in a hundred or a thousand years can move great quantities of material long distances. The carrying power of water is said to vary with the fifth or sixth power of its velocity. I am not ready to disagree with Waldemar Lindgren and accept that many commercial placers are substantially enriched by the chemical deposition of gold from solutions; however, I have seen crystalline gold in clayey material quite distant from known sources of primary gold that is dif-

Jan 1, 1985

By T. V. Philip, R. E. Lenhart

When commercial silicon iron sheets of varying magnetic quality are isothermally annealed at high temperatures, extremely large grains develop in the material having good magnetic properties. These grains are of the (110) [001] orientation and are formed by secondary recrystallization. The primary driving force for this secondary recrystallization is grain boundary free energy. For the secondary grains, activation energies of 103 kcal per mole for nucleation, and of 75.5 kcal per mole for growth, were obtained. The activation energy for nucleation of the secondary grains is consistent with a model involving redistribution of a precipitate acting as the primary grain growth inhibitor. SINGLY oriented silicon iron sheet was first produced in 1935.1 The material as commercially produced today has a very highly developed preferred orientation or texture; up to 95 pct of the grains are crystallographically oriented with their (110) planes in the plane of the sheet and their [loo] directions parallel to the rolling direction. This texture, usually written as (110) [00l], is referred to as the "GOSS" or the "cube-on-edge" texture. Because the magnetic properties of this material are superior to those of the nonoriented sheets in the direction of rolling, the oriented silicon iron has acquired tremendous industrial importance especially in the manufacture of transformer cores and other electrical equipment. The commercially produced material is essentially an iron-silicon alloy containing about 3 1/4 pct Si with minor impurities totaling less than 0.15 pct. The silicon steel heat is melted in the open hearth or electric furnace. The ingots are hot rolled, with or without being slabbed, to strips of 0.100 to 0.080 in. thickness. They are then cold reduced to an intermediate thickness, recrystallized, cold reduced to final thickness, decarburized, and finally annealed at a high temperature. During this high-temperature anneal, extremely large grains with the cube-on-edge texture are produced in the sheet. Several papers have appeared in the literature2-10 relating to the production of the Goss-textured material. Most of these describe the textures produced on cold rolling and on subsequent annealing of single crystal or polycrystalline silicon iron. May and Turnbull11,12 have recently shown the necessity of a second-phase dispersed impurity in the material for the production of the Goss texture. However, none of these papers describes in detail the nucleation and growth kinetics of the (110) [001] grains during the final high-temperature anneal.* The present work, therefore, is an attempt to understand the nucleation and growth kinetics of the cube-on-edge grains in the silicon iron sheet during the final high-temperature anneal.

Jan 1, 1962

By William H. Bassett

COPPER is the world&apos;s most important non-ferrous metal, and brass is the most widely used non- ferrous alloy. Much of the utility of each may be credited to the work of metallurgists who have constantly improved the quality of the metals and alloys and the methods of fabrication. Standing in the front rank among these is William Hastings Bassett, the newly elected president of the Institute. Mr. Bassett, ,who is technical superintendent and metallurgist for the American Brass Co.,

Jan 1, 1930

By Felix A. Vogel

I (New York Meeting, February, 1912.) FLUE-DUST, to most blast-furnace operators, means a troublesome by-product, the formation of which should be curtailed, if not prevented entirely. However, with the increasing use of fine ores, larger furnaces, and high-pressure blast, the production of flue-dust is constantly increasing, and amounts annually in the United States to from 3,000,000 to 3,500,000 tons, An exceedingly high tonnage, of which a large part has been discarded as valueless. As a result of greater economy in the iron industry, the attention of our furnace-men has been directed towards the utilization of this enormous amount of waste material, a problem which had also been given due consideration by metallurgists abroad. Flue-dust is generally a fine material containing considerable coke and iron-ore, with a small admixture of lime and silica, depending upon the burden. The iron-ore is partly reduced, which shows that the dust originates largely in the reducing-zone of the blast-furnace. In the United States this dust usually contains 20 per cent. of coke and more than 40 per cent. of iron. Estimating coke to be worth $3.25 per ton, and iron-ore 7 cents per unit, a ton of flue-dust, unless made available, represents a loss to the furnace-man of $3.50. This accounts for the first efforts to recharge the flue-dust into the furnace, either by moistening it clown with an excess of water, or mixing it with clay to form balls of pulp, or treating it with lime-water. These methods, however, have been practically discarded, as they failed to produce the desired economies. To recover, in the blast-furnace, all the values represented by the material contained in the flue-dust, the following con¬ditions should be complied with

May 1, 1912

By H. A. Wilhelm, P. Chiotti, G. A. Tracy

A summary of analytical, X-ray, thermal, and metallographic data obtained in the study of the Mg-U system is presented. No intermetallic compounds are formed by these two elements, and their mutual solubility is limited at temperatures up to 1255°C. The compositions of the liquids which coexist at 1135°C under a pressure of 3 atm are 0.14*0.05 wt pet U in magnesium, and 0.004 wt pet Mg in uranium. The solubility of uranium in magnesium decreases to 0.0510.03 wt pet at 675OC, and to about 0.0005 wt pet at 650°C. Due to the reactivity of both uranium and magnesium toward crucible materials, the choice of a suitable crucible presented a problem. Crucibles made from high purity magnesia to which 10 wt pet MgF2 was added to reduce porosity proved to be satisfactory. Some observations made with the use of other crucibles are given. THIS investigation was made to establish the phase diagram for the Mg-U system. Ahmann,&apos; formerly of the Ames Laboratory, did some work on the system. He used several methods in an attempt to prepare Mg-U alloys. One of the methods involved the reduction of UF, with a large excess of magnesium. In these experiments, the magnesium wet the surface of the uranium, but there was no evidence for compound formation. The maximum solubility of magnesium in uranium was indicated to be 0.01 wt pet. In another set of experiments, uranium chips as well as uranium powder were heated in contact with molten magnesium in a graphite crucible for periods of time up to 48 hr. A reaction layer was found at the Mg-U interface in several instances. X-ray analysis of the layer material showed the presence of UC and some additional unidentified lines which were interpreted as indicating the possibility of an intermetallic compound of uranium and magnesium. These studies indicated the maximum content of magnesium in uranium to be 0.043 wt pet. One sample of magnesium which had been heated at 1025°C in contact with excess uranium was found by chemical analysis to contain 0.275 wt pet U. Rules, based on empirical or semi theoretical considerations, which attempt to predict the alloying behavior of metals have been presented in the literature. Although these rules are not infallible, they nevertheless serve as useful guides. Using them, several generalizations can be made concerning the Mg-U system. According to Hume-Rothery&apos;s&apos; atomic

Jan 1, 1957

By R. E. Reed-Hill, W. H. Hartt

High-purity magnesium single crystals, oriented with basal plane parallel to stress axis, were deformed in tension at room temperature so as to form second-order (1011)- (1012) twins. Investigation by optical and replica electron microscopy revealed that these twins can support very large internal strains approaching 1000 pct and that fracture follows as a direct consequence of these strains. At low strains the basal plane within (10i1)- (10i2) twins rotates with increasing deformation until it becomes approximately parallel to the twin boundaries. This rotation is not consistent with deformation by basal slip in the double twin, but may be rationalized in terms of nonbasal slip. Observations also indicate that basal slip in the primary (1011) twin, prior to second-order twinning, may contribute to this rotation. Deformation markings that are difficult to interpret in terms of slip on previously observed systems were noted in the twin bands. A possible means of rationalizing these markings is to relate them to grain boundary shear. The fracture associated with these twins is thought to initiate by formation of voids at the twin boundaries. These grow into microcracks, with ultimate fracture occurring by tearing of the interconnecting regions. THE significance of deformation and fracture along second-order (10i1)-(10i2) twins in polycrystalline magnesium1-&apos; and many magnesium alloys4 was discussed in a previous paper.5 It was noted that this double twinning mode effectively controls the room-temperature deformation and fracture of magnesium single crystals, oriented with the basal plane parallel to the tensile axis. Reed-Hill and Robertson6 observed that, although these crystals may fracture at a macroscopic strain of less than 1 pct, shear strains up to 1000 pct could occur within (1011)- (10i2) twin bands. They concluded that the fracture was "ductile" and resulted from concentrating the deformation into a very small volume. The present research was undertaken to obtain a better understanding of the deformation and fracture associated with these twins. EXPERIMENTAL TECHNIQUES The experimental procedure involved straining high-purity magnesium single crystals in tension at room temperature. Specimens were oriented so that the applied stress direction was within 2 deg of the [1010] crystal axis. The specimen cross section was rectangular with faces closely parallel to (1210) and (0002). The specimen preparation and testing procedures have been described in detail elsewhere.5 Second-order (1011)- (1072) twins nucleated during straining were studied using optical and replica electron microscopy techniques. For the latter, cellulose acetate-carbon double replicas were employed. Observations were made on the (1210) crystal surface, which is the plane of shear for twins of this type. In addition to the single crystals, some investigations were carried out on longitudinal polycrystalline specimens. These were obtained from high-purity magnesium plate with a texture in which the basal planes of the grains tended to be nearly parallel to the specimen axis. All. polycrystalline specimens were annealed prior to testing in order to produce a coarse grain structure, permitting Laue back-reflection X-ray photographs to be obtained from grains of interest. EXPERIMENTAL RESULTS a) Deformation Within ( 101 l )-( 1072) Twins. Fig. 1 is an optical micrograph demonstrating the extent of the plastic deformation that can occur in (1011)-(10i2) twin bands. Notice at the lower left corner of the photograph the large displacement of the dark band (a polishing step) where it crosses the twins. The shear strain in the twin band at this position was computed to be 700 pct, using the ratio of step width to twin thickness. It was previously shown5 that (1011)- (1012) twin bands are often composed of small, separate twins aligned close to the macroscopic habit plane. Fig. 2 is an electron micrograph from near the upper end of the twin band in Fig. 1. This illustrates that the twin habit often does not coincide exactly with the macroscopic band habit, but may be inclined at a slightly smaller angle to the matrix basal plane. Figs. 3 through 6 are electron micrographs of the twin band in Fig. 2 illustrating successive steps in the development of deformation inside the band. A twin band such

Jan 1, 1969

By B. H. Caudle, B. M. Hickman, I. H. Silberberg

Secondary recovery projects often are not started in oil reservoirs until dictated by rising GOR&apos;s or declining oil production. Such circumstances require a well dispersed injection pattern to prevent the oil bank from bypassing the production wells. Many times this purpose is served by using the five-spot or line-drive patterns, in which half of the wells are made injection wells. A regular injection pattern is proposed that is based on the same well spacing as the five-spot but in which only a third of the wells need be converted to injection wells. Fluid flow model studies on this proposed pattern show that production histories will be as good as those for a five-spot pattern at mobility ratios of three and above. The model data are presented in a form that may be used to predict recoveries from both homogeneous and stratified formations. Introduction The injection of fluid into a petroleum reservoir usually is prompted by an actual, or predicted, loss in the productivity of the reservoir. Often, an oil reservoir is produced by pressure depletion until high GOR&apos;s dictate a change in policy. Fluid injection also causes increased ultimate recovery, but this usually is of less importance to the operator than is the maintenance of the production rate. It is a fact that the ultimate recovery in any particular fluid injection project is relatively independent of the number and spacing of the injection wells as long as the reservoir voidage through the production wells is balanced by the total injection rate. However, the response of a production well is directly affected by the distance it lies from an injection well. In places where the well productivities are declining, the injection wells should be spaced as evenly as possible among the producing wells ("dispersed" injection pattern). More particularly, if the production response depends upon the formation (and subsequent production) of an oil bank, each production well should be surrounded by injection wells. Otherwise, the oil productivity will increase very little as the oil bank moves past the well.&apos;.&apos; An evenly spaced injection pattern has the best chance of generating an oil kick in the production wells. If reservoir voidage and injection rates are to be equal, the ratio of injection wells to production wells must be equal to the ratio of the average injectivity to the average productivity (in reservoir volumes). This ratio is in strumental in choosing the injection pattern. Table 1 shows the production well to injection well ratio for the dispersed injection patterns that have been described in the literature.&apos;-&apos; All of these patterns will have comparable recoveries and response times (for the same basic distance between wells). The choice of pattern there fore depends upon the relative injectivity and productivity of the wells and upon the type of drilling pattern employed. Another important factor may be the ability of the proposed production wells to make up the lost productivity from those wells converted to injectors. These factors become more pronounced at the higher oil viscosities (low gravity oils). All other things being equal, the probable ratio of single well injectivity to single well productivity will be equal to the water-oil mobility ratio of the proposed flood. Thus, high mobility ratios (due to low gravity oil) should call for fewer injection wells — as long as these injection wells are "dispersed" to obtain more even pro duction response for the remaining wells. Secondary re covery projects in oil reservoirs seldom, if ever, will have mobility ratios requiring more injection wells than production wells. Thus, only the last five of the patterns listed in Table 1 will be of significant interest in oil recovery. Almost every development drilling program calls for the wells to be drilled along equally spaced rows and

Jan 1, 1969

By N. K. Chen, R. B. Pond

IN the study of slip band* formation, there have been many examples to show that they do not always appear as lines traversing the entire crystal, but as segments whose ends seem to vanish in their path through the crystal. This characteristic appearance of slip bands has been witnessed under the optical microscope at various magnifications&apos;-&apos; and also under the electron microscope.&apos; A typical example of this behavior seen with the optical microscope is shown in Fig. 1. However, the slip band studies were generally conducted on polished surfaces of single or poly-crystalline metals which had been previously deformed; i.e., the load was generally released so that the observation could be made. Any picture of slip bands so obtained can represent the surface phenomenon only in a static state of the strained material. The conditions prior to their formation cannot be definitely and clearly assigned. Thus, while a segmented slip band may suggest that slip is a growth process as supposed by the theory of the nucleation of slip,V he usual appearance of suddenly and fully developed slip bands around the crystal has generally been considered as a consequence of uniform shear of the entire slip plane akin to a cataclysmic process. Little clear-cut information is available with regard to the speed at which a slip band forms, its direction of motion, the geometry of its position with regard to its neighbors, and its dependence on orientation. A description is given in this paper of experimental apparatus by which the progressive formation of slip bands can be recorded while the specimen is undergoing deformation. Qualitative and quantitative data on the dynamic formation of slip bands will be presented with special interest concerning the propagation of slip bands, the spacing of slip bands, and their relations to strain hardening. Views on the formation of slip bands are discussed and a mechanism of the unit process involved in the formation of a slip band is proposed. Preparation of Specimens Single-crystal specimens of high purity aluminum (99.997 pct), 1/8 in. square in cross-section and 1% in. long in gage length, were made by the method of gradual solidification from the liquid state. Since no machining work could be introduced in preparation of crystals of such small size, a special mold was designed for casting them to final shape. The mold consisted of two, separate, high purity graphite blocks. Generally, 20 molds were packed together in one container so that 20 specimens could be obtained by one casting operation. This was desirable since it was possible by this method to obtain groups of crystals with similar orientations. The as-cast crystals were carefully clipped from the gate, etched, and homogenized for 24 hr at 600°C. They were then very gently polished using a 4/0 paper, re-etched, and finally electrolytically polished after the method previously described by Chen and Mathewson.6 The crystallographic orientations were determined using a back-reflection, Laue method. Tensile Testing and Photographic Method The tensile testing equipment for these tests was composed of a specially designed microtensile machine, microload cell and microclip gage with necessary appurtenances. The members of the microtensile machine consisted of three parts, as shown in Fig. 2. The chassis is equipped with an oil cylinder, A, and piston, the piston being part of the movable cross-head, B. Pressure in the oil cylinder is controlled and regulated by an external pneumatic-hydraulic cell, C, which is connected to the cylinder by a Vs in. high pressure copper tube. This cell is half filled with hydraulic oil and has a needle valve, D, on the oil exit side as well as a needle valve, E, on the gas inlet side. A quick-acting valve, F, as well as a pressure gage is provided for the gas side. The oil exits into the load piston on the microtensile machine. By connecting a tank of inert gas to the gas inlet, regulated pressures were provided over the oil so that the oil would leave the cell at a rate determined by the setting of the exit needle valve, the gas pressure, and the pressure of the oil in the load piston of the microtensile machine. With this pneumatic-hydraulic appurtenance it was possible to

Jan 1, 1953