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By L. H. Simons, H. H. Spain

I NT RODUCTION Theory indicates that linear water-floods should exhibit scaling and stabilization properties in both oil-wet and water-wet porous media'. Experimental verification of these proper-ties in oil-wet media was obtained some time ago', and more recently, Perkins', employing a high permeability unconsoli dated sand and a low oil-to-water viscosity ratio, has obtained flooding data in a water-wet medium which follow the pattern of scaling and stabilization. Also, Root and Calhoun3 have found similar trends in the displacement of gas by liquids from unconsolidated sands. In general, however, the experimen-tal evidence appears still somewhat conflicting since scaling and stabilization of water floods in water-wet media has not been observed in most of the studies to date'.".'. The purpose of this paper is to provide a more comprehensive picture of waterflood behavior in water-wet media and to corroborate the validity of the scaling and stabiliza-tion concepts. The need for differentiating between the intrinsic nature of water-oil displacements inside a porous medium and perturbating secondary end effects is discussed, pertinent experimental procedures are outlined and the results of flooding tests conducted at low and at high oil-to-water viscosity ratios on con- solidated, water-wet Alundum cores are analyzed. END EFFECTS IN WATER-WET MEDIA Outlet End Effects The peculiar feature of the outlet end effect in water-wet cores is that it not only results in an excessive wetting phase saturation at the outflow face,'.' but that it also retards the moment of water breakthrough: i.e., causes an undue delay in the appearance of water in the produced effluent. Conditions existing in a water-wet core when water first arrives at the outflow face are schematically shown in Fig. 1. At this flooding stage the saturation distribution, Fig. la, has not yet been distorted by the outlet end effect. A water-invaded pore at the outlet core face, opening into the oil-filled void space between the end of the core and the end plate of the flooding cell, is illustrated in Fig. lb. The curvature of the water-oil interface is concave toward the outlet, and the pressure on the water side of the interface is lower than on the oil side by an amount equal to a certain capillary pressure (Fig. lc). Before the water (of this particular pore) can be produced from the core, it is apparent that the pressure in the water phase must exceed that in the oil outside the core. Accordingly. when water first reaches the outlet face, it will not leave the core but will accumulate inside, and only oil will be produced. Eventually, as the water injection is continued. sufficient pressure is built up in the water to reverse the curvature of the interfaces in the outlet pores, and only then will water be produced from the core. This stage, illustrated in Fig. 2. corresponds to the conventional "water breakthrough" observed in flooding experiments. For purposes of discussion, it is convenient to distinguish between the flooding stage at which water first arrives at the outlet face of a core (Fig. 1) and the stage at which water is first produced from the core ( Fig. 2). The former will be referred to as "water arrival" and the latter water breakthrough. In oil-wet media

By A. B. Cook, C. J. Walker, G. B. Spencer

Although water will displace oil from a petroleum reservoir to a greater extent than gas will, there are some reservoirs in which gas rather than water should be used for pressure maintenance. This is indicated by the high-percentage oil recovery in the case history reports on the Pickton field1 in East Texas and the Raleigh field2 in Mississippi. In gas cycling, total oil recovery includes vaporized products from the immobile oil in addition to oil produced by displacement. If a large part of the immobile oil is vaporized, total oil recovery may be higher than that obtainable from pressure maintenance by water injection. However, the amount of immobile oil vaporized may range from almost 0 to 100 percent, and no simple and reliable method has been presented in the literature for calculating oil vaporization. Development of such a method was the purpose of this study. Several papers concerning the calculation of oil vaporization have been published,3 6 and each is based on the concept dealing with K values — equilibrium constants for the various components in reservoir oils. (K for a component in a system of vapor and liquid in equilibrium is the mole fraction in the vapor phase divided by the mole fraction in the liquid phase.) This appears to be the most logical approach. Yet, the problem is too great for a perfect solution, even with modem laboratories to analyze oils and high-speed digital computers to perform calculations; the number of components in reservoir oils is too large. Because of their complexity no two reservoir oils are exactly alike. Also, K values change not only with variations in pressure and temperature but also with composition of the reservoir oil. In addition, during gas cycling, the lighter hydrocarbons tend to vaporize first. Thus, the reservoir oil becomes more dense and less volatile as gas cycling continues. Furthermore, the greatest amount of oil vaporization occurs near the injection well. Therefore, a simplified method is required for calculating oil vaporization because a rigorous method is not practical. The present methods of calculating vaporization generally require knowledge of the reservoir oil composition in which the mole fractions of the lighter components through hexanes are given; the remaining oil is described as C, + (heptanes and others of greater molecular weights). Assigning one K value for the C,+ system provides the simplest solution, but this incorrectly assumes that K for C, + does not change as gas cycling continues. This assumption can cause large errors because the K value may become less than a thousandth of the original after a large amount of oil vaporization. Another way to solve the problem is to determine changing K values for C, + according to how much of the C, + has been vaporized. To determine these values a sample of the reservoir oil is injected into a pressure-volume cell, and dry gas is batched in and out of the cell. Appropriate measurements and tests are made to determine K

Jan 1, 1970

By Percy A. Robbins

I. INTRODUCTION. THE central power-station. of the De Beers Consolidated Mines, Ltd., was designed and built under my supervision about five years ago. Since no detailed description of this plant has ever appeared, it may possess sufficient interest to warrant its publication, even at this late date. Although some additions may have been Blade to the plant, the following account, prepared from my notes, and accurate up to May, 1905 (at which time I severed my connection with the De Beers Com¬pany), will, I think, be found substantially correct. Certain local conditions governing the design of this plant should be stated first. If. GENERAL CONSIDERATIONS. The climate is hot and dry. The .region around Kimberley is arid and water is very scarce. The supply obtained from the mines contains so much material in solution that it is unfit for use in boilers or condensers (although tests recently made with a water-softening plant, built by Hans Reisert, of Germany, would indicate that water thus treated is suitable for boilers). And the amount of water required for concentrating about 30,000 tons of ore per day is so large that the question of adequate water-supply for this power-station had to be carefully considered. The rainy season extends from December to April, and the rainfall averages about 15 in. per year. Droughts are frequent; and in some years there is scarcely any rain at all. The water-supply for the town of Kimberley is brought from the Vaal river, 16 miles distant, and pumped into town by a private water company. The charge made for water, which is

Mar 1, 1908

By J. C. Detweiler

THE Jacksonville plant of Humphreys Gold Corp., operating under leases from National Lead Co. and Rutile Mining Co. of Florida, recovers rutile, ilmenite, zircon, and monazite from an ancient beach deposit containing about 2.5 pct of these minerals in combination. The location of the plant is unique, being situated about ten miles from the center of Jacksonville, Fla., surrounded by a thriving suburb. Two four-lane highways pass within 1 ½ miles of the plant. An expressway now under construction will pass over the tailing pile, within 500 ft of the mine office. The elevation at the plant site is approximately 50 ft above sea level. This is one of two mines producing titanium minerals and zircon in Florida. Another mine is also operated by Humphreys at Starke, about 50 miles southeast of Jacksonville. The Jacksonville deposit extends about six miles in a north-south direction, averaging approximately one half mile wide and twenty ft thick. Values begin at the surface over most of its length and ter-

Jan 1, 1952

By C. C. Harris

An analytical solution of the integro-differential equation of batch grinding is proposed as a first appoximation to the xYt surface. The size distribution equation (xY plane) is a three parameter equation previously suggested. Possible refinements are outlined. Comminution kinetics research is presently following several related courses. Some are equivalent, in that they represent different ways of viewing the same facet of the problem, though the entire endeavor cannot be described as being completely integrated. The purpose of this note is to propose and discuss a framework into which the various approaches might be fitted. This must clearly be founded upon an analysis of the xYt surface.' (See also Fig. 1 of Reference 26.) The investigations referred to above comprise mainly researches into the following: (1) The kinetics of the creation of the finer sizes during relatively small grinding times. This is the Fahrenwald-Arbiter-Bhrany 2-3 approach which leads to equations equivalent to a special case of the charles4 relationship. It emerges that initial production of fines follow essentially zero order* kinetics. (2) Disappearance kinetics of the coarser fractions. This appears to be a first order relationship.5-6 (3) Prediction of the xYt surface via the selection and breakage functions utilizing computer-programmed or approximate solutions of the integro-differential equation of batch grinding.5,8-17 A recent discussion by Mika et al.5 references the relevant literature up to about 1966. In addition to these main-stream researches there is some work on the minor topic of extremely long grinding time considered as a limiting case.18-19 The field is supported by investigations into the size distribution of fragments produced by breakage processes, some of this work being most valuably statistical-mechanical in nature.20-25 Better fitting equations, however, are obtained by statistical and curve-fitting methods.26 This

Jan 1, 1969

Jan 1, 1966

By Robert K. Linn

The New ldria Mining District is in the southern part of the Diablo mountains of the California Coast Range, 140 miles southeast of San Francisco. The district, noted primarily for quicksilver, also has become important recently as a producer of short-fiber chrysotile asbestos. Between 1853 and 1966, the New Idria district produced 568,092 flasks of quicksilver valued at about $55,600,000, 99 per cent of which was recovered from one deposit, the New Idria mine. In 1944, the district was ranked third in all-time production of North American quicksilver districts, and, since that time, the New Idria mine produced an additional 129,045 flasks, placing the district and the New Idria mine second in all-time production. The major structure of the region is the northwest-trending Coalinga anticline consisting of an asymmetric dome of sedimentary beds ranging in age from Jurassic to Quaternary and marked at its northwest end by an oval body of sheared serpentine 14 miles long by 4 miles wide. The serpentine core, rimmed by Franciscan sandstone of probable Jurassic age, was uplifted in stages between Jurassic and Quaternary time and was intruded along a ring of faults into beds of the Panoche Formation of upper Cretaceous age. The core of serpentine and Franciscan rocks is the locus of about 20 quicksilver mines that rim the faultbounded core and lie within the serpentine mass. The host rock of the most productive deposits is altered Panoche shale and sandstone that lies intermittently along the perimeter of the core. Deposits of the New Idria group of mines and those of a few other small mines lie along the northeast contact in the footwall of the New ldria thrust fault, and a few others occur on steep normal faults around the south and southwest. The chief ore mineral in all quicksilver mines is cinnabar, but minor amounts of metacinnabar and native mercury are found in some of the mines. Ore shoots were deposited in fracture zones and stockworks in altered Panoche shale and sandstone and in definite fissure veins in Franciscan sandstone. Rocks made highly amenable to fracturing by hydrothermal alteration were fractured extensively by late faults. The resulting fracture zones, located along the late faults and at changes in strike or dip of the hanging wall or footwall, are the principal controls of most ore shoots. The largest and richest ore shoots are those of the New Idria mine. The major ore bodies occur in fractured shale and sandstone beneath the New ldria thrust fault at its junction with major tear faults.

Jan 1, 1968

By R. L. Fullman, J. W. Cahn

A method is derived for obtaining the distribution of sphere diameters and plate thicknesses (or pearlite spacings) from size distribution functions obtained along randomly oriented lines. The method described offers several advantages over existing methods. IT is often of interest to measure not only the average particle size but also the distribution in sizes of particles dispersed in an opaque material, such as an alloy. Particles of a single size will exhibit a range of apparent sizes on the plane of polish. If the sample contains a distribution of particle sizes, the distribution of observed sizes on the plane of polish is related to the distribution of actual particle sizes by an integral equation, For example, a distribution of sphere sizes, N(r),

Jan 1, 1957

By D. W. Fuerstenau

In 1940 Schuhmann1 showed that the size distribution of a comminuted material can be expressed by the following empirical relationship: y = 100 (|f [i] where y is the cumulative percentage of material finer than size x, k is a size modulus, and a is a distribution modulus which is constant for a given material and machine. During the past few years, considerable emphasis has been given to the investigation of the extent of size reduction resulting from the expenditure of mechanical energy in crushing and grinding. Recently Schuhmann' presented a derivation of the energy-size reduction relationship by postulating that comminution in a device such as a ball mill can be considered to be the summation of many single comminution events, each of which yields a size distribution of particles following the Schuhmann size distribution equation. By grinding

Jan 1, 1961

By C. H. Mathewson

CONSIDERABLE progress has been made during the last few years in analyzing the action of plastic deformation in metallic crystals. This is due largely to the development of X-ray spectrographic methods for studying changes in the orientation of single crystals, or of conglomerates, as they occur during the process of plastic deformation, but partly to the widespread knowledge of suitable technique for preparing large (single or variously combined) crystals for direct crystallographic observation under stress or in various conditions of strain. These two methods of studying changes in the crystalline structure of metals may of course be used in conjunction with features of mutual support, but unfortunately the advantage of direct crystallographic observation is lost when we proceed to the study of severely cold-worked structures, owing to the occurrence of real or apparent crystalline discontinuities which become more and more complicated as the amount of plastic action increases. Furthermore, the X-ray methods do not appear to be adequate, at least in their present stage of development, to fix definitely the character of structural alteration in the parent crystal lattice by plastic deformation. The principal question at issue concerns the nature of the crystalline particles that remain after plastic deformation. These are generally known in our American metallurgical literature as crystalline fragments,' and they seem, indeed, to diffract as individuals causing the Hull pattern of a severely cold-worked metal to resemble the pattern of a fine powder,2 with certain features of preferred orientation among the particles deter- mined by the manner and intensity of cold working. We must freely concede that there are conceptions of lattice alteration, apart from that of simple fragmentation, which would account for an increasing number of lattice positions according to X-ray spectrographic observation as the degree of deformation increased.

Jan 1, 1927

By E. B. Johnson

Cleveland-Cliffs lron Co., which operates Marquette lron Mining Co.'s Republic mine, conducted a test whereby 35,000 tons of self-fluxed pellets were produced in the grate-kiln system from specular hematite flotation concentrates. A brief description of the pelletizing plant is presented along with pertinent operating details. Date is included which compare operating conditions and the chemical and physical properties of the green and fired pellets for the self-fluxing pelletizing test with the normal acid pelletizing operation. The success of self-fluxed sinter in enhancing the operation of the blast furnace during the past few years has reasonably led to the assumption that the use of self-fluxed pellets might result in even greater furnace efficiencies. A great share of development work in agglomeration has been directed towards techniques related to the production of self-fluxed pellets, but only a limited tonnage of self-fluxed pellets had been produced on a commercial scale until this past year when The Cleveland-Cliffs Iron Co. produced 35,000 tons of such pellets by the grate kiln system at the Republic mine during the period May 21-June 5, 1962. REPUBLIC'S GRATE-KILN PLANT The grate-kiln pelletizing process consists of four stages, namely: feed or balling circuit, traveling grate, rotary kiln and annular cooler (Fig. 1). The balling section is conventional and utilizes four 9x30-ft balling drums in closed circuit with 5x14-ft vibrating screens having 3/8-in. rod decks. The traveling grate is 12 ft wide by 126 ft long and has 14 windboxes — six in the drying section and eight in the preheat section. The rotary kiln is 15 ft ID shell and 114 ft long. The annular cooler is 40 ft in diameter and has 12 windboxes. The cooler is divided into two zones by a moveable curtain wall. The high temperature air from the first zone is used as secondary combustion air in the kiln. Normally the only heat supplied is through the burning of No. 6 oil in the single kiln burner. Hot gases pass counter to the pellet flow through the system. The exit gases from the kiln pass down draft through the preheat section through cyclones and are drawn through the drying bed prior to exiting via the stack. The temperatures are normally held within the following ranges: Kiln 2400-2445 °F Preheat 1850-1950°F Drying 480-520°F Exit gas 200°F Pellets 120°F The design capacity of the Republic mine grate-kiln system was 2500 Itpd. Sustained production in excess of 35% over design capacity has been achieved. No screening of the cooler product is practiced. PELLETIZING TEST CONDITIONS When a decision was made to proceed with a test at the Republic mine pelletizing plant to produce 35,000 tons of self-fluxed pellets, several potential failure factors had to be carefully considered. Research work on a batch and pilot plant scale indicated that the grate-kiln system at Republic would require some major changes in order to obtain optimum conditions. In many cases compromises were agreed upon as major equipment changes and revisions were not feasible. The pelletizing conditions which laboratory development tests revealed were required in order to insure successful production of self-fluxed pellets were: 1) Good mixing of limestone and concentrate and proper moisture control; 2) Higher gas flow rates in the preheat section than are normally used; 3) Higher preheat temperatures than normal; 4) Maximum kiln temperature 2350°F. There was just cause for concern about balling problems that might occur. Approximately 10% of dry pulverized limestone was to be added to the specular hematite concentrate just ahead of the Pekay mixers on the belt feeding the balling drum. Large scale

Jan 1, 1963

By K. G. Gorling, S. J. Wallden, N. B. Lindvall

It is the policy of The Metollurgical Society to provide, in the TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, a prompt and accurate medium for publication of reports of significant new research in both the scientific and engineering aspects of metallurgy. Papers submitted to the Society are judged by competent reviewers according to established criteria for technical merit, accuracy, originality, and presentation. STAFF: Editorial Director, Rixford A. Beals; Associate Editor, James J. Burke; Assistants, L. Capria and R. K. Larkin. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: A. W. Thornton, Choirmon; Dennis Carney, John Chipman, J. C. Fulton, J. H. Hollomon, H. tl. Kellogg, A. E. Lee, R. Maddin, J. D. Sullivan, and O. Swan. Review and selection of manuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division T. B. King. Cha~rmon; S. J. Dickenson, R. P. Hermsdorf, R. Schuhmann, Jr.. and P. T. Stroup. Institute of Metals Division: Robert Maddin, Chairman. F. Lincoln Vogel, Jr., Vice-chairman, W. A. Backofen, R. W. Balluffi, J. H. Bechtold, M. B. Bever, R. S. Busk, C. G. Goetzel, Paul Gordon, C. D. Graham. Jr., Robert F. Hehe-mann, R. I. Jaffee, F. E. Jaumot, Jr., lrving R. Kramer, A. J. Leno, Horold Margolin, C. J. McHorgue, Russell A. Meussner, J. 6. Newkirk, H. W. Paxton, G. E. Pell~ssier, I. S. Servi, Alan U. Seybolt, A. J. Sholer, and Sack Wahsburn. Iron and Steel Division: J. C. Fulton, Chairman; T. B King, F. C. Langenberg, W. O. Philbrook, and T. B. Winkler. Published bimonthly by the American Institute of Mining Metallurgical and Petroleum Engineers Inc., 29 West 39th Street, New York 18, N. Y. Telephonne pennsylvania 6-9220.Petroleum Subscription Engineers$20 per year for non-AIME members in United States and North South and Central 6-9220.SubscriptionAmerica $25 toreign; $5 for AIME members. Single copies, $4.00, iinalo copies Southfpr;ign,andCentral $5 00. The AIME 'is $25not responsible for any statement made or opinion expressed in its publications Copyright 1958 1958 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . Registered coble address, AIME New York . . . Indexed in Engineering Index, Industrial Arts Index, ...and Chemical Abstracts . . . Application for second class mail privileges IS pending at New Yark, N. Y. Volume 212, Number 2.

Jan 1, 1959

By S. R. B. Cooke, H. S. Choi, I. Iwasaki

In a previous article1 the function of various fatty acids as collectors for iron ores was reported for the two alternate processes; (a) the flotation of iron-oxide minerals, and (b) the flotation of calcium-activated siliceous gangue. The selectivity of separation was shown to be markedly dependent not only on such common parameters as pH and the levels of collector and activator addition, but also on the structure and the degree of unsaturation of the acids used. The iron ores employed consisted primarily of hematite, goethite, and quartz and as the effectiveness of any one acid on the separation depends on the individual response of each constituent mineral toward the given collector, a comprehensive knowledge of the floatability of the individual minerals is desirable for the interpretation of the results obtained. The mechanism by which a collector ion becomes attached to a mineral-solution interface has been a subject of much investigation. From quantitative studies of the properties of the electrical double layer on mercury2 and on several solid surfaces3,4,5,6 , the adsorption of some flotation reagents at the mineral-solution interface is beginning to be understood. For example, it has been demonstrated from streaming potential measurements made on quartz5 and corundum6 that the interfacial electrical condition is strongly dependent on the pH. Thisoccurs presumably through the following electrolytic reaction at the interface, and in the presence of a flotation collector, controls the floatability of the solids. A concurrent investigation of the flotation behavior of goethite and of quartz carried out at the School of Mines and Metallurgy7 has shown a positive correlation with the electrokinetic behavior of these minerals. The purpose of the present investigation was to collect general information on the floatability of hematite, and to investigate the function of various 18-carbon aliphatic acids on the floatability of hematite, goethite, and of activated quartz. Electrophoretic mobility measurements, simplified flotation tests using a modified Hallimond tube, and contact angle and frothability measurements were employed. The results are of direct application in the interpretation of the batch flotation results on natural ores as

Jan 1, 1961

By Elmer W. Pehrson

Minerals have played a prominent role in the affairs of man and nations since time immemorial but with the advent of the industrial revolution, expanding use of the products of the mineral kingdom became synonymous with the material progress of mankind. Individuals and business groups have recognized this fact so have been aggressive in searching for and utilizing mineral resources, with notable success. Indeed, their achievements are primarily responsible for the present Machine Age. On the other hand, until recently the body politic has failed to grasp fully the essentiality of minerals although, at times, access to mineral supplies has been an important factor in the political maneuvers of nations. This chapter is concerned primarily with the broader political and economic relationships of mineral resources to the world economy, and with the internal and external actions of nations in the field of minerals. Many factors that condition the mineral economy of regions and the world as a whole, influence the internal and external affairs of individual nations. The more important of these are: 1. The nature of man's dependence on minerals. 2. The problems resulting from the unique characteristics of mineral occurrence. 3. Geopolitical concepts. 4. Minerals and world power. Actions of individual nations affecting their mineral economy seek two basic objectives: 1. Attainment and maintenance of prosperity. 2. Military security. Other objectives may be cited but on careful analysis they become integral parts or extreme phases of the two points noted above. For example, the twentieth century aggressions of the USSR, Germany, Italy, and Japan might be considered as direct bids for world power but they also can be interpreted as exaggerated or mistaken efforts toward military security and peacetime prosperity. Similarly, trade barriers, nationalization of industries, foreign exchange manipulations, taxation, monopolistic prac-

Jan 1, 1964

By O. W. Shimer, D. C. Helms, C. E. Brown

THE early history and progress of anthracite stripping, from the first known operation at Summit Hill in 1821 through 1917, was covered in 1917 in a paper by J. B. Warriner,1 then chief engineer, now president of the Lehigh Navigation Coal Co., and stripping methods between 1917 and 1931 were the subject of a paper in 1931 by H. H. Otto,2 of the Hudson Coal Company. The present paper is confined to methods used today on pitching beds in the western middle and southern anthracite fields. The anthracite industry, not unlike other large industries, had been affected for more than a decade by the adverse economic conditions of the country. High development and operating costs and the competition of other fuels caused some collieries to be closed temporarily, while others were permanently abandoned. In order to obtain a larger tonnage at a lower development cost, a larger stripping program was put into effect by many companies. In 1932, stripping operations accounted for 334 million tons, or 7 per cent of the total anthracite production of the year, and in the next 10 years this increased until more than double that amount, or over 14 per cent of the total production, was from stripping operations. These figures represent the total production of the entire anthracite region; unfortunately, the figures have not been separated from the different fields. There are some operations in the southern and middle western fields where the tonnage obtained from stripping amounts to more than 30 per cent of the total colliery production. Stripping operations on pitching beds present difficult problems. Owing to the various geological formations, a different situation is encountered in nearly every stripping pit; and because of the proximity of an overlying bed, it is very often necessary to load the entire overburden into trucks and haul it out of the pit to the dump area, although back filling and casting is done whenever possible. Beds in the areas described in this paper pitch from 20° to 90° and some are on the invert in, many sharp folds and faults. PLANNING The more successful strippings have had adequate engineering analysis. Some work is being done without much preliminary planning, but many strippings would have failed completely if close supervision by the engineering department had not been maintained. Locations of stripping areas are determined as follows: 1. By constructing cross sections over the areas and drilling sufficient diamond-drill or well drill holes to study the strata and to determine the location, thickness and pitch of the beds.

Jan 1, 1944

By J. L. Lytton

The flow-stress recovery of high-purity aluminurn following a 10 pct tensile prestrain was studied in terms of a fractional flow-stress recovery parameter fr. The flow-stress recovery behavior was related to the dislocation arrangements using transmissiort electron rnicvoscopy. During recovery at 120° and 160°C, nearly stable strength levels were attained, the strength level for 120°C recovery being greater than that for 160°C. This stabilization of flow stress was related to the formation of meta-stable dislocation networks bounding nearly perfect cells. Both network formation and the annealing of dislocation loops were found to be recovery mechanisms, and the stronger metastable strength level joy 120°C recovery was related to a smaller average cell size. Analysis of the networks was consistent with the reaction of sets of dislocations with a/2 (110) Burgers vector to give product Burgers DURING isothermal annealing of cold-worked metals, a degree of softening occurs without re-crystallization, and the processes responsible for this change are termed recovery processes. During recovery annealing, the dislocations generated during cold work become rearranged into low-energy configurations, and as much as 50 pct of the stored energy is released."' The relationship between this rearrangement of dislocations and mechanical behavior is of considerable importance, since the dislocation substructures formed during recovery provide a significant degree of low-temperature strength3j4 and can favorably alter the course of primary creep at high temperatures.4 The purpose of the present study was to relate the flow-stress recovery behavior of high-purity aluminum to the substructural modifications that occur. Electron transmission microscopy was therefore employed for direct observation of dislocation substructures at various stages of recovery following 10 pct prestrain. Several investigators5-' have proposed that dislocations can become rearranged or lost during the preparation of thin foils. It was found early in the present study that the dislocation structures in the thicker regions of the foils changed in a systematic way during the course of recovery. Therefore, it is unlikely that substantial losses or rearrangements occurred during thinning. This point will be discussed in more detail later. The results of various investigators indicate that recovery processes in fcc metals can result in release of 50 pct or more of the total energy stored in the as-prestrained metal, this percentage decreasing with increasing prestrain.' Alloying elements or impurities tend to increase this percentage. The release of stored energy of fcc metals during recovery appears to occur by 1) annealing of point defects if the deformation occurred at sufficiently low temperaturesg and 2) rearrangement of dislocations into low-energy Configurations.1,2In bcc metals, the annealing of dislocation loops has also been observed during recovery after prestrain,10-12 and it has been proposed that this is a recovery mechanism for unidirectionally strained fcc metals.' The density of dislocations in bcc metals has not been observed to decrease appreciably during recovery,10 although the formation of regular dislocation networks has been observed. has shown that the formation of such networks can result in elimination of long-range stresses and can lead to significant release of stored energy without dislocation annihilation. It might thus be expected that network formation is a significant recovery mechanism in fcc metals, although extensive network formation has apparently not been reported in controlled recovery experiments. The formation of sub-boundaries in aluminum has been observed by various investigators13'17 during recovery studies of aluminum, but the structure of these boundaries was not resolved. In this regard, it is significant to note that Bailey and Hirsch,' using transmission electron microscopy, detected no network or sub-boundary formation during recovery of 99.99 pct Ag. Furthermore, Clarebrough et al.2 found no such rearrangements during recovery of copper. EXPERIMENTAL PROCEDURE The high-purity aluminum used in this investigation was obtained in the form of 0.125-in.-thick sheet. Spectrographic analysis revealed that the sheet was 99.995 pct A1 with the following weight-percent impurities: 0.001 Cu, 0.002 Fe, 0.001 Si, and 0.0004 Mg. The as-received sheet was in the heavily cold-rolled condition. The as-received sheet was cold-rolled at room temperature to 0.040-in.-thick sheet in the longitudinal direction, which was the original rolling

Jan 1, 1965

By E. H. T. Whitten

Fundamental principles of trend surface analysis are briefly reviewed. Recent analyses of several granite masses illustrate the method of estimating the quantitative regional composition and also variation trends. Mineralogi-cal, bulk chemical, and other quantitative variates can be employed. Such results should improve gravimetric surveys (etc.) relying on correction terms based upon estimated rock composition. For the first time realistic estimates of the mean composition of rock bodies can be made with the aid of trend components. Deviation maps hold promise for delimitation of disseminated mineralized areas. Deviations comprise residual "anomalies" after removal of trend components. In petrogenetic work such deviations have been shown to reflect local influences (e.g., contamination of magma by assimilation of xenoliths or country rocks of the envelope). Similarly, mineralization should be reflected as deviations standing out from background trends. Actual examples are given. Present results largely involved projection of data onto a horizontal plane, but if sufficient data are available use of three spatial coordinates increases accuracy for prediction in "unexposed" areas. Regression analysis shows that statistical correlations between variates for regionally distributed specimens are often strong (particularly with percentage data). Hence, in preliminary surveys more easily determined variates may sometimes be employed to gain first estimates of the distribution of components more economically significant. The sampling plan is of paramount importance. Unless a suitable sampling plan is devised and adhered to rigorously during collection of the samples, all subsequent analysis is liable to strong bias and to yield spurious estimates of the truth. For a wide variety of purposes it is becoming necessary to assess the quantitative composition and variability of rock masses and mineralized zones of various types. In petrology and petrography this is something of a break with tradition, because virtually all descriptions heretofore have been qualitative. Although vast amounts of qualitative data have been compiled, little is known about the quantitative behavior of rock components. However, if variability of rocks could be understood and expressed with sufficient accuracy, there would be considerable advantage to both economic and petrogenetic problems. For example, if, on the basis of a limited series of observations, the three-dimensional geometry of a disseminated orebody (or ore-bearing formation) could be predicted accurately, it would be possible to extrapolate with confidence the structure into unexposed areas. The following example based upon the geometry of an igneous cone sheet illustrates the point. The significant rock-unit gives outcrops at a number of points on the exposed surface ABCD (Fig. 1A). Study of n exposures may enable a geologist to predict that the rock-unit is circular in form and thus indicate where the unit can be expected in unexposed terrain. Such observations are made at sites with u, v coordinates, but, if subsurface information is available at sites with uvw coordinates, it will eventually become possible to predict accurately the three-dimensional form of the rock mass. Geologic rock masses or mineral deposits are not generally as regular and symmetrical in geometric form as the body illustrated in Fig. 1A. However, even where the broad limits of a major rock mass are known, a more acute problem arises in attempting to obtain detailed quantitative estimates of its internal variability; it is difficult to predict the variability of a mass from a limited number of observa-

Jan 1, 1961

Jan 1, 1962

By Mario L. Villa

Argentina's oil production continues in its upward trend. The year 1940 closed with an important increase over 1939; that is, 1,996,371 bbl., or 10.72 per cent. The Government oil fields (Y.P.F.) are responsible for these results, as their total output was 12,474,655 bbl., which compared with the 10,222, 533 bbl. produced in 1939 represent an increase of 2,252,122 bbl., or 22.03 per cent. Fields operated by private companies yielded 8,134,882 bbl., against 8,390,633 bbl. in 1939, a decrease of 255,751 bbl. (3.04 per cent). To the total of 20,609,538 bbl. produced in 1940 in Argentina, the Comodoro Rivadavia field contributed 14,976,222 bbl.; Plaza Huincul, 1,275,814 bbl.; the Province of Salta, 1,845,1977 bbl. and the Province of Mendoza, 2,51I,475 bbl. Table 3 compares the output of companies working in Comodoro Rivadavia. The total increase of 186,819 bbl. (1.26 per cent) registered in the Comodoro Kivadavia area is due only to an intensification of development programs in the known

Jan 1, 1941

By Mario L. Villa

Argentina's oil production continues in its upward trend. The year 1940 closed with an important increase over 1939; that is, 1,996,371 bbl., or 10.72 per cent. The Government oil fields (Y.P.F.) are responsible for these results, as their total output was 12,474,655 bbl., which compared with the 10,222, 533 bbl. produced in 1939 represent an increase of 2,252,122 bbl., or 22.03 per cent. Fields operated by private companies yielded 8,134,882 bbl., against 8,390,633 bbl. in 1939, a decrease of 255,751 bbl. (3.04 per cent). To the total of 20,609,538 bbl. produced in 1940 in Argentina, the Comodoro Rivadavia field contributed 14,976,222 bbl.; Plaza Huincul, 1,275,814 bbl.; the Province of Salta, 1,845,1977 bbl. and the Province of Mendoza, 2,51I,475 bbl. Table 3 compares the output of companies working in Comodoro Rivadavia. The total increase of 186,819 bbl. (1.26 per cent) registered in the Comodoro Kivadavia area is due only to an intensification of development programs in the known

Jan 1, 1941