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By M. H. Caron

D. C. Ralston—The fact that none of the organizations that have worked on these ammoniacal leaching processes have contributed discussion of Mr. Caron's papers today is a matter of some disappointment. Adaptations, modifications and improvements have been made by several organizations or individuals and to complete the record I want to document a number of them. The Nicaro Nickel Co. operated a Government owned plant at Nicaro, Oriente, Cuba, during the past war. A report on the project was written for Reconstruction Finance Corp. and is in the document file collected by the Office of Technical Services, Commerce Department and filed with the Library of Congress, where it can be consulted or bibliofilm or photostat copies obtained by asking for copies of PB 97271. Nicaro Nickel Co. has obtained a series of U.S. Patents, my list (probably incomplete) of which bears the following numbers: 2,400,098; 2,400,114; 2,400,115; 2,400,461; 2,400,612; 2,458,902 and 2,473,795. International Nickel Co. has also studied the problem and U.S. Patent 2,478,942 shows that some of the complications involving occasional low extractions have been unraveled. Forward, Samis, and Kudryk, of the University of British Columbia, have also published a study of copper-nickel sulphide concentrate.' Others are interested and it is evident that this type of hydrometallurgy is likely to find a happy application in the not-too-far distant future. Caron's two papers practically amount to a summation of his life's work on the important subject of nickeliferous iron ores and the American Institute of Mining and Metallurgical Engineers is fortunate to have been chosen the medium of publication. M. Rey—The ammonia leaching process has been the subject of certain studies in New Caledonia, but at the present time, the conditions are not very favorable to its adoption. The process is a combination of a thermal and a hydrometallurgical process. As a result, the first costs and the operative costs are rather high. To counteract this unfavorable situation, it would be necessary to make a very high extraction. But unfortunately, the process is delicate and in spite of all of Caron's valuable work, there are still many unknown factors. It is difficult to obtain regularly a high extraction, exceeding 75 to 80 pct. It would be interesting to have the opinion of Inter-national Nickel on the process and to know what the Dutch are doing in Celebes. M. H. Caron (author's reply)—I am quite familiar with the different types of nickel and cobalt ores as found on New Caledonia, and it may be pointed out that the Celebes ores are quite the same in their properties. Their behavior when treating the ores by the ammonia-leaching process is also alike and in my opinion, there is no reason why a high extraction of the New Caledonian ores could not be obtained if the process is properly applied. For the sake of completeness I may add that one of my patents has not been discussed in the papers. This patent deals particularly with the treatment of serpentine nickel ores. (Netherlands No. 62693 40a, French No. 965.786 April 21. 1948. and Cuban No. 13.625 Jan. 1950.) O F. A. Forward, C. S. Samis, and V. Kudryk: Trans. Canadian Institute of Mining and Metallurgy. (1948) 151 (Bull. 434) 350-355.

Jan 1, 1951

By Kenneth A. Moon

Kenneth A. Moon (U.S. Army Materials Research Agency)—The authors are to be congratulated for a very interesting and valuable paper. Their discussion of the structural implications of the results shown in their Fig. 5, however, requires a small correction. The model of Speiser and Spretnak with 0 = 1 and z' = 2 is perfectly reasonable for the Ti-O a phase, but Eq. [3] is valid only for solutions sufficiently dilute that the number of empty sites excluded by more than one filled site is negligible. The composition at which intrinsic saturation occurs therefore cannot be deduced from Eq. [3], but but must be decided by consideration of the structural details of the phase in question. In this case, intrinsic saturation is expected not at the composition Ti3O but at Ti2O, because Ti2O has the anti-Cd structurel4 for which each filled octahedral site has two nearby empty sites, one in the hexagonal plane immediately above it, and one in the similar plane below it. The other two models, with ?=1/3 and 1/2, imply a distinction between octahedral sites in pure titanium which is not easy to justify. The problem of extending Speiser's and Spretnak's treatment in a general way to more concentrated solutions will be the subject of a forthcoming publication by the writer. M. T. Hepworth and R. Schuhmann, Jr. (authors' reply)—The authors wish to thank Dr. Moon for calling to their attention the paper by Holmberg which presents the results of X-ray studies of Ti-O solutions ranging from 0 to 33 at. pct 0 and quenched from various annealing temperatures between 400" and 1800°C. Within these ranges, Holmberg found three types of phases: 1) At high oxygen contents (above 25 at. pct) and low annealing temperatures, he found the anti-Cd(OH)2 structure referred to by Dr. Moon. In this structure each titanium atom is in contact with 3 oxygens and each oxygen is in contact with 6 titaniums, the "available" oxygen sites corresponding to every other layer of octahedral sites in the titanium matrix. The limiting composition is Ti2O. However, this anti-Cd(OH)2 structure was not observed for samples containing 25 at. pct 0 or less. 2) For the specimen containing 25 at. pct 0 annealed at 400°C an ordered Ti3O structure was observed. This structure is related to the anti-Cd(OH)2 structure but differs from it by providing only two oxygens adjacent to each titanium atom and thus is consistent with the model represented by Eq. [5] in our paper, with 6 = 1/3, z' = 0. 3) For dilute solutions and for more concentrated solutions annealed at higher temperatures, the structure corresponds to that of the metal with random distribution of oxygens among all the octahedral sites. Thus, it is interesting to observe that the thermo-dynamic indications of ordering in the vicinity of Ti3O can now be supported qualitatively at least by Holmberg's X-ray evidence of the existence of an ordered phase of the composition Ti3O. That is, for solutions with oxygen contents close to that of Ti3O, both the thermodynamic data and the X-ray data are more consistent with models based on the ordered structure of Ti3O than they are with the model which Dr. Moon suggests corresponding to "intrinsic saturation" at Ti2O.

Jan 1, 1963

By W. A. Backofen

THE texture of cold-drawn copper wire has been described most often as a composite of [Ill] and [loo] directions aligned parallel to the wire axis.' Hibbard2 suggested that sufficient reduction will result in a single [111] texture and reported that after a reduction in area of 96.4 pct, such a texture was nearly obtained. Other work3-4 has shown that recrystallization within the temperature range of 300" to 1000°C does not alter the texture established by cold-drawing. In general, however, the texture of cold-drawn end annealed copper wire is not as well defined as the deformation texture. In the work reported here it was found that the double-fiber, deformation texture persists even after a reduction in area of 97.3 pct, and after recrystallization the texture is practically all [l00]. The wire used in this work was prepared in the following way. A 3/4-in. diam length of annealed OFHC copper was cold-drawn to a diameter of 1/8 in., a reduction in area of 97.3 pct. Each step in the drawing operation brought about a reduction in area that varied from 6 to 10 pct. Short lengths of this wire were etched in a 50-pct solution of nitric acid to a diameter of approximately 0.01 in. The texture of the cold-drawn specimens was determined with the conventional X-ray transmission diffraction technique using filtered copper radiation. The X-ray beam was directed perpendicularly to the wire axis and the diffraction rings were recorded on a flat film. Fig. la is typical of the photo-grams obtained and reveals that the cold-drawing schedule described above introduces a distinct, double-fiber texture with both [Ill] and [l00] directions aligned parallel to the wire axis. Supplementary measurements with a Geiger-Mueller counter of the intensity of reflection from (111) planes showed that the [111] component was much more predominant than the [l00]. Additional specimens of the drawn and etched wire were annealed in a salt bath at temperatures from 300" to 450°C. The texture of the recrystal-lized wire was studied with the same technique applied to the cold-drawn wire. Fig. lb is an X-ray photogram of a specimen annealed for 1 ½ at 300°C and is typical of those obtained from re-crystallized specimens. The photogram shows that recrystallization of this material is accompanied by the almost complete elimination of the [111] component of the deformation texture. A pronounced strengthening of the [100] component was evident from intensity measurements with a Geiger-Mueller counter. In summary, the deformation texture of cold-drawn OFHC copper wire, after a reduction in area of 97.3 pct, may still be described as a composite of [Ill] and [loo] directions aligned parallel to the wire axis. Recrystallization of such wire at temperatures from 300" to 450°C introduces a texture which consists almost entirely of a [loo] alignment. Acknowledgment Sidney Rolle of the Scomet Engineering Co. generously supplied the OFHC copper used in this work. References 'C. S. Barrett: Structure of Metals. p. 382 (1943) New York. McGraw-Hill Book Co. 2 W. R. Hibbard, Jr.: Trans. AIME (1949) -185, p. 598; Journal of Metals (Sept. 1949) TN 19E. 3 P. 422 of ref. 1. 'E. Schmid and G. Wasserman: Ztsch. Physik (1926) 40, p. 451.

Jan 1, 1952

By Robert G. Reno, Ralph E. Esarey

DriLLing activity and prospecting for oil and gas increascd in Indiana in 1941 over the previous year. The greater part of the drilling and development continued to centralize in the Indiana portion of the Interior Coal Basin, in the southwestern part of the state, but other parts of the state were not neglected. Many wildcat wells were drilled, including a series of core tests through the mantle of drift on the southern flank of the Michigan Basin. These core tests have been followed by several unsuccessful production tests. Production tests were made also along the axis of the Logansport-Kankakec branch of the Cincinnati Arch. In all, 411 field locations and 141 wildcat wells were completed in Indiana during 1941; that is, a total of 552 wells, an increase of 3 2 wells over the previous year. The field tests resulted in 260 oil wells, 57 gas wells, and 94 dry holes; wildcats included 16 oil wells, 3 gas wells and 122 dry holes. At the end of the year, 53 field wells and 34 wildcats were drilling. Gibson and Posey Counties led the state, with 154 and 155 wells drilled, respectively. However, 125 wells produced oil in Gibson County, while 98 produced oil in Posey County. Twenty-five per cent of all wells drilled were wildcat; II per cent of these produced oil and 5 per cent produced gas. Grifin field continued to lead in drilling activity, with 157 successful wells and 20 dry holes (including important wells defining the field). Production is found in five pay zones (Tar Springs, Waltersburg, Elwren, Aux Vases and McClosky). It produced a major part of Indiana's estimated 7,200,000 bbl. of oil during the year. Heusler field, Posey County, expanded with 11 oil ells and 4 dry holes in the Waltersburg and Tar Springs. Vienna field, Posey County, completed four oil producers in the Mansfield sandstone, between 1200 and 1250 ft. The College field, discovered late in 1940, received three oil producers and two dry holes in the Aux Vases. Two new fields were discovered in Posey County during the year: Lamott pool, in the Tar Springs, at 1950 ft., had initial production of 55 bbl. on discovery. One producer and one dry hole have been drilled since. Mt. Vernon pool found saturation in both the Waltersburg and Cypress formations. The discovery well tested about 1000 bbl. per day; it tested the McClosky at 2764 ft. Seven producers have been drilled since the October discovery. Welborne-Switch pool found oil in the Cypress sand at approximately 2500 ft., with an initial production of 33 bbl. One more well in the area proved a dry hole. Gibson County had the following discoveries in 1941: The Patoka field was opened by a McClosky producer of 300 bbl. Another producing well has been drilled. An attempt was made to extend the Illinois Mt. Carmel field into Gibson County, Ind., and one producer of 24 bbl, was completed on the Indiana side. A dry hole has since been drilled, one location south. One small well was completed in the Mans. field at 1105 ft. in sec. 31, T.2 S., R.12 W., Gibson County promising a new field

Jan 1, 1942

By J. H. Henderson, R. J. Wygal, J. Naar

Experimental work is reported which shows that consolidated rocks and unconsolidated porous media exhibit different imbibition flow behavior. At a given saturation the imbibition nonwetting permeabilities for a rock are smaller than the drainage permeabilities. The contrary happens for unconsolidated aggregates — imbibition nonwetting permeabilities are larger than drainage ones. A similar difference is observed for the wetting phase. Imbibition permeabilities are larger than drainage ones for a consolidated rock but smaller than drainage permeabilities for an unconsolidated medium. The results of these differences are examined for two cases. 1. Flooding Efficiency — Craig's1 scheme for the computation of production history of a five-spot water flood is shown to agree extremely well with experimental results obtained when using a system packed with glass spheres if imbibition relative permeability curves are used. 2. Alcohol-Slug Displacement — Published theory 2 on oil displacement by alcohol slugs has been questioned despite the apparent agreement between predicted and observed results. The present work suggests that, if imbibition relative permeability curves characteristic of the unconsolidated media used in the early experiments had been available to make the predictions, the inadequacy of the theory would have been immediately evident. The experimental work shows that poorly consolidated formations tend to behave like unconsolidated media. Finally, it is shown that the difference in imbibition behavior is directly related to pore-size distribution and cementation. PART 1 — THE FLOW BEHAVIOR OF UNCONSOLIDATED AGGREGATES Experiments on scaled models of field reservoirs are useful for studying new displacement processes which are incompletely understood. Even when a mathematical description is possible, the solution might be difficult and complex. An answer obtained from a scaled model is extremely valuable in such cases. A great amount of work$-5 therefore, has been devoted to the derivation of scaling laws. Similarity groups have been defined which assume (1) that the relative Permeability curves of the prototype and the model are the same whether the displacement is an imbibition or a drainage process and (2) that there is a linear relationship between the capillary pressure of the model and the prototype. For practical reasons (simplicity in the preparation of models, duration of the experiments, etc.), the porous media of laboratory models are usually unconsolidated packs of sand or glass particles. Hence, unless the capillary and flow characteristics of unconsolidated and consolidated systems are identical, the model data are applicable only to unconsolidated formations. The usefulness of scaled-model studies may then be seriouslyrestricted since most oil-bearing sands are consolidated. Perkins and Collins6 suggested the use of model and prototype curves normalized with respect to both relative permeability and saturation to improve compliance with scaling criteria. Even this technique does not give a satisfactory model-prototype match. This paper reports an observation of two-phase flow in unconsolidated sands which shows that, for most displacements, "scaling" in the strict sense of the word is not even qualitatively feasible with a sand model. It provides, however, a firm foundation for testing a theory by matching it with observed performance of laboratory-size models. EXPERIMENTAL AS a part of a basic study of packed aggregates, the relative permeability of glass-spheres and sand-grain packs was measured with capillary control. The fluids were oil and air' The spheres were packed in plastic cylinders 1-in. in diameter;

By R. B. Rosene, G. L. Foster, A. R. Hendrickson

he properties of some of the common fracturing oils, such as sand-falling rate, fluid loss and viscasity, are a function of the three major constituents of the oil. These are: asphaltic material, parafin waxes and a base oil. The base oil can be either high or low viscosity. Asphaltic material increases viscosity by thickening the oil, decreasing the rate of fall of sand through the oil. at temperatures up to 200" F. When large arnorrnts of parafin wax are present, much of the wax i.s not dissolved, but is present in the form of rnicroscopic crystals. 7'his, of course is limited to temperatures below the melting points of waxe.s. As a result, parafin waxes clo not function primarily as thickener.7, but rother as bullting materials. The functiori of wax, without asphaltic material, in a low viscosity base oil is uniquely unlike that of wax with asphalt coexistent in the oil. The resulting difierence in wax crystal size governs the sand-falling rate to a large extent. An ideal type of fracturing oil is one containing neither asphalt nor waxes. In such cases, the viscosity and resulting low sand-falling rate are apparently due to soluble resin- ous hydrocarbons, which are compatible with formation oils. INTRODUCTION Since the introduction of hydraulic fracturing as a method of stimulating production from oil and gas wells, a variety of fluids have been employed to open the fractures and carry the propping agent. Such fluids include gels, emulsions, and oils. In the latter category, the use of refined oils has increased tremendously, and it is probably safe to assume that such oils represent more than one-half of the total fluid used in fracturing. The general acceptance of refined oils for fracturing can be accounted for on the basis of their relatively low cost and general applicability. To minimize transportation costs, such refined oils are generally obtained within the local areas of operation. As a result there are several kinds of oil used in different areas, with a wide variation in the basic composition. These types may vary from a fair grade of lubricating stock to a highly viscous cut-back asphalt. or road oil. Originally, little attention was paid to the composition of the oils used for fracturing, and any oil which would carry sand was considered satisfactory. Recently, however, service companies and well operators have become more concerned with the type of oils used for fracturing. With this in mind, the present work was undertaken to evaluate and compare many widely used fracturing oils to determine which constituents were most desirable for fracturing purposes. Some of the important properties of fracturing fluids are sand-falling rate, viscosity, and fluid loss. Other properties, that are actually of no less importance, include flash point, pour point, emulsifying tendencies with formation brines, and compatability with the formation oils. This discussion has been limited, however, to the first mentioned properties in order to give some idea of the general composition of the refined oils, how they function, and why. PROPERTIES OF FRACTURING OILS The properties of fracturing oils are a function of the three major constituents of the oil. These may be designated as: (1) asphaltic material, (2) paraffin waxes and (3) a base oil, which may be of either high or low viscosity. The asphaltic material clas-

Jan 1, 1956

By John Griffen

This paper records over twenty years' experience with the use of the Rheolaveur system in the United States, showing its ability to meet changing conditions caused by the dirtier mine output of present-day mechanical mining methods. Data are given on size ranges handled, number and capacity of units installed, maintenance experience, and operating results on two-product and three-product separations. IT is not the purpose of this paper to discuss the principles employed in the Rheolaveur system of fine-coal cleaning as these have been fully covered in the technical literature of the Institute."2 Rather, our purpose will be to record the highlights of over 20 years' experience in the United States with Rheolaveur fine-coal launders, which will indicate their capabilities and costs of cleaning and their adaptability to meet the changing conditions caused by present-day mechanical mining methods. Rheolaveur fine-coal launders are used in the United States to treat a wide variety of size ranges of fine coal, the coarsest being 1/2 in. to 0 and the finest about 1/8 in. to 0. In Europe feeds as coarse as 5/8 in. and as small as 1/2 mm (28-mesh) to 0 are being cleaned. The size ranges usually handled in this country are 3/8 to 1/4-in. round to 0. Thirty five units with a combined hourly feed capacity of 3200 tph have been installed in the United States. Individual units are cleaning as little as 25 tph, while others are cleaning as much as 200 tph. Rheolaveur fine-coal launders offer cleaning units of high capacity and are outstanding in requiring a minimum of building space per ton of input. Experience has shown that maintenance costs are low. Several installations were made in the Pittsburgh district from 1928 to 1930, and since that time operation has been largely two shifts per day. Minor repairs to liner plates and Rheo boxes have been required during the intervening years, but no major replacement of launders was required until 1947 and 1948. At one of these plants, launders operated for 17 years before they were replaced and during that period over 26,000,000 tons of —5/16-in. coal were cleaned. The effect of the much dirtier raw coal produced by mechanical loading of the Pittsburgh seam is shown by the following tests. The data in table I summarize the performance of a Rheo fine-coal unit when cleaning hand-loaded raw coal. The —4-in. raw coal fed to the cleaning plant analyzed only 8.16 pct ash and 1.31 pct sulphur and contained 4.6 pct sink, 1.55 sp gr. Two years later, in 1945, mechanically-loaded coal from the same mine was cleaned in the same plant. The feed, —4 in., then analyzed 20.10 pct ash and 1.53 pct sulphur and contained 20.2 pct sink, 1.55 sp gr. The performance of the Rheo fine-coal unit when cleaning this coal is given in table 11. It will be noted that the +48-mesh coal is cleaned almost as thoroughly as in table I. The large amount of high-ash slimes produced from the dirtier feed are responsible for the higher ash of —--48-mesh washed coal in table 11. In this plant the Rheo fine-coal unit did not get the full load of refuse resulting from mechanical

Jan 1, 1951

By W. David Leyshon

This paper compares the general characteristics of Florida phosphate rock for the manufacture of fertilizers and phosphoric acid. The subjects covered are relative reactivity for superphosphate manufacture and various properties of the rock for use in phosphoric acid production, including gypsum filterability, sulfuric acid consumption, foaming, relative cor-rosiveness, chemical composition, and others. Comprison will include rocks of North Africa, the western U.S., and other locations. This paper reviews some of the important properties of phosphate rock, giving particular attention to a comparison of Florida phosphate with some of the major phosphates produced in the world. It also discusses some of the techniques available for evaluatine Phosphate. rock for phosphoric. acid and fertilizer use. The use of Florida rock outside the U.S. has been increasing steadily, evidence in itself of certain desirable properties of this rock. Table I is a list of the major producers and exporters of phosphate rock as of 1965. Florida, meaning in this case Central Florida, was the largest producer of phosphate rock and the largest exporter of rock. Of a total world production estimated at 60 million tons, about 50 million tons were produced during 1965 by the areas listed in Table I. One major producing area omitted from Table I and from subsequent evaluations in this paper comprises Nauru, Ocean, and Christmas Islands, whose output totaled about three million tons in 1965. This phosphate is marketed entirely by the British Phosphate Commissioners, primarily in Australia and New Zealand, and does not get into the world market elsewhere to a significant degree at the present time. South Africa, Egypt, Israel, and North Vietnam also produce lesser quantities of rock for the international market, and these materials are also excluded from this review. The phosphate industry is now seeing the introduction of several new areas that will be significant factors in the rock market in the future. The North Carolina and North Florida areas each have capacity at present or in the near future for producing about three million tons per year. The Djebel Onk mine in Algeria has a potential of about 800,000 tons per year. In addition, announcements have been made of significant development of deposits in Peru and in the Spanish Sahara, and sizable expansions are planned in several of the existing areas that are now of minor importance. Competition for the rock market appears to be increasing so that more attention will probably be paid to evaluating phosphates available from different areas. It is not possible here to go into all the properties of even a few of the materials listed in Table I. However, it is practical to discuss some comparative properties important for making phosphoric acid and fertilizers, and to touch on the techniques used for the evaluation of various phosphate rocks. Table II gives typical analyses of the major phosphate rocks available in the world as of 1965. There is, of course, an inherent danger in labeling any analysis as typical, but it appears that variations between two samples of rock within one given area are generally less than between two samples from different areas. The analyses listed were compiled from several years of data so they may not be representative of the present output of any particular area. The range of grades represented by these analyses goes from 66 BPL for Gafsa rock to 85 BPL for Kola

Jan 1, 1968

By Edwin A. Rides

HISTORICAL ORIGIN OF THE EXPORT CREDIT AGENCIES Almost since the inception of international commerce sellers, having manufactured and/or sold and shipped goods to an overseas buyer, have been obliged to accept the risk that they will not be paid for one reason or another. There are many reasons why payment may not be forthcoming, for example, the goods may be lost at sea, or rejected by the buyer or the buyer nay simply not be creditworthy. These risks were brought into sharp relief as international trading became more sophisticated and the practice of giving credit to buyers gathered momentum. Inevitably enterprises sprang up which offered same mitigation of this exposure, accepting houses and later confirming houses and banks were prepared to assure acceptable credit risks an behalf of the seller, usually by discounting trade paper, and for many years the market ticked over reasonably satisfactorily. However, after the 1914-18 War international trade was at an extremely low ebb and its inherent risks were accentuated to a point where they were often commercially unacceptable. Yet a healthy and vigorous international market was indispensable to recovery of the world economy and a number of governments, led by the United Kingdom, perceived a need to offer their exporters a comprehensive form of insurance, particularly to facilitate the extension of credit to foreign buyers. In the United Kingdom the Export Credits Guarantee Department (ECGD) was set up to encourage trade through the provision of export credit insurance. Over the ensuing years others followed suit and now most of the developed trading nations and many developing nations have similar agencies. PRESENT DAY IDLE OF THE EXPORT CREDIT AGENCIES (ECAS ) Traditionally then the BA's role was to encourage trade through the provision to exporters of insurance against the risks of non-payment by overseas buyers of their goods and services. However, during the 1970's the manufacturing industries of most of the developed nations found themselves facing severe competition for business, particularly in the developing world. As a result the more aggressive ECA's began to introduce ancillary forms of cover designed to reduce exporters' risks outside of the credit field. For instance, most of the European agencies now have a form of cover against foreign exchange risks here contracts are denominated in currencies other than that of the exporter's country. Most of the agencies also provide cover to exporters against the risk of unfair calling of bid, advance payment, performance bonds etc and in certain countries, where high inflation rates were endemic, a form of cover against cost escalation. In certain circumstances it is also possible for an exporter to obtain cover against losses arising as a result of the involvency of a partner in a consortium or joint venture. These are all forms of insurance but, also during the 1970's, many of the national export credit programmes took a major step away from their original raison d'etre by facilitating the provision of preferential financing terns for the acquisition of capital equipment by an overseas buyer. This new line of business quickly became an important ingredient of major export financing packages and, as we shall see later, turned out to be extremely costly for the countries providing it.

Jan 1, 1985

By F. R. Brotzen, A. R. Troiano, E. L. Harmon

Precipitation processes leading to drastic property changes are a frequent occurrence in titanium alloys containing large amounts of the retained high temperature P phase. In order to establish the kinetics and nature of these precipitation processes, a series of Ti-V alloys was studied. Time-temperature-transformation diqgrams were obtained for 12.5 and 15 pct V-Ti alloys. These diagrams consisted of two intersecting C-shaped curves: one in the high temperature region for the euilibrium transformation P +u+P, and another at lower temperatures depicting the formation of the meta-stable transition phase, o. Presence of the transition phase retarded the precipitation of the equilibrium a phase. Deformation of retained P resulted in the formation of the o phase. Reversion and retrogression phenomena of the transition phase were observed. A negative temperature coefficient of resistance was found in quenched alloys containing from 15 to 20 pct V. CERTAIN titanium-base alloys can be heat treated to produce appreciable changes in properties. For example, remarkably high hardness values may be obtained by aging or isothermal quenching treatments. Most of the information available to date on the hardening of titanium-base alloys has been systematized recently in an article by L. D. Jaffe.' It was pointed out by that author that the hardening was the result of the decomposition of the retained j3 phase to the equilibrium constituents, a and p, and that this decomposition had many of the characteristics of an age-hardening reaction. Recent work by Frost et al.' 3 has contributed much to the fundamental understanding of the hardening mechanism in titanium-base systems. These authors established the presence of a transition phase in the transformation from j3 to a + j3, which they designated o. The transition phase, in their opinion, was at least partially responsible for the hardening and embrittling effects which accompanied low temperature aging. The present investigation of the mechanism and kinetics of the hardening reaction was carried out for the Ti-V system. Ti-V alloys were ideally suited for a study of the decomposition of j3, since age hardening was known to occur readily in this system." Moreover, no intermetallic compounds occur in this system, Fig. 1, thus simplifying the interpretation of the results. Material and Procedure Alloys containing 12.5 and 15 pct V were prepared by Battelle Memorial Institute from iodide titanium furnished by Watertown Arsenal and vanadium of 99.8 pct purity. Ingots of 8 Ib each were prepared by arc melting in an inert atmosphere with a tungsten electrode and water-cooled copper crucible. Each of the ingots was melted once, forged at 1600°, and rolled at 1400°F. Following this, the ingots were remelted, forged, and then rolled to % in. sq bars, which were subsequently grit blasted, pickled, and wire brushed. Another set of alloys containing nominally 17.5 and 20 pct V was produced by the Research Div., New York University. These alloys were arc melted in an inert atmosphere in lots of 20 g each. Heat-Treating Procedure: Whenever feasible, specimens were heat treated in high vacuum resistance furnaces at pressures below 5x10." mm of Hg. Aging and isothermal quenching treatments were generally carried out in salt baths. Specimens were not attacked by the salt, provided the tempera-

Jan 1, 1956

By F. von Gemmingen, E. J. Fasiska, L. Zwell

EARLIER studies of the dependence of creep on structure1 and of the dependence of creep rupture on creep behavior2 did not include detailed discussion of the phases present in the specimens under examination. It is of interest to determine the nature and amounts of such phases present since it is well known that these are dependent on composition, heat treatment and creep conditions.3 This investigation has therefore been undertaken to identify these constituents and to determine their relative amounts. This report presents the results of this investigation and describes an improved "extraction replica" technique developed in the course of the work. The composition of the Type 316 austenitic stainless steels studied in this investigation is given in Table I. The specimens were solution treated at 2000°F for 1/2 hr and water quenched. Those specimens subjected to prestrain at room temperature Methods for extracting precipitate particles from materials for electron and X-ray diffraction analysis have been described by Fisher,4 Smith and Nutting: and Booker and coworkers.6'7 Electrolytic extraction methods have been described by Andrews and Hughes.8 The first two methods have been used at this Laboratory, but have not proved satisfactory for many problems requiring X-ray diffraction analysis. It has been difficult to remove the replicas or to avoid tearing them during removal. These difficulties are overcome by backing the replica with a water-soluble plastic such as Dupont 51-05 Elvanol (polyvinyl alcohol). The backing increases the thickness of the replica so that it can be mechanically stripped from unloosened particles without folding or tearing. This procedure eliminates the stripping of wet replicas, which usually have a low tear strength. By stripping replicas after drying, it is possible to extract partially loosened particles which otherwise would remain imbedded in the metal. The modified method is as follows: after the specimen is polished, it is etched for 60 min in modified glyceregia consisting of 30 ml glycerol, 7 ml nitric acid, and 4 ml of hydrochloric acid. The sample is then washed, air dried, and coated with a 20 pct Baker and Adamson 1611 collodion (85 pct amyl acetate by volume) film. After the collodion film is dry (about 15 min), the sample is again etched in the modified glyceregia for 50 min, washed with isopropyl alcohol (to prevent dissolving the collodion) and air dried. A very thick coat of polyvinyl alcohol (about 50 pct solution "Elvanol Dupont 51-05" in water) is poured over the sample and is permitted to dry for about 24 hr. The composite film containing the precipitates is then stripped from the specimen and floated, polyvinyl alcohol side down, in water (at about 50°C) until the polyvinyl alcohol dissolves. This usually takes about 15 min. Should any of the polyvinyl alcohol remain on the replica, it does not give a crystalline diffraction pattern and therefore does not hinder identification of the precipitates. The extraction replica, floating in water, is picked up on a glass fiber and mounted in the Debye-Scherrer camera for X-ray diffraction analysis. Concentration of the etchant, and also etching time, had to be increased for several of the samples. Fig. 1 shows two extraction replicas taken from different areas of spec. M74-37; X-ray analysis showed a strong diffraction pattern of M23C6 and a medium one of u phase. A

Jan 1, 1962

By S. A. Braley

THE first commercial production of bituminous coal in the United States was in 1820, and formation of acid in the areas from which the coal was removed began at that time. Thus it is 130 years since the development of mine acid began. The coal operator has had to deal with the acid water produced in his mines, and his losses from corrosion of pumps and equipment have been tremendous. Other industries and the public have been forced to spend large amounts for their water requirements because of the acid discharge from the mines. There are many contradictions in the literature on this subject probably because of variations in the analytical procedures followed and differences in the methods of calculation and reporting. The opinions previously expressed may be summarized as follows: The production of mine acid has been looked upon as a simple chemical reaction wherein the oxygen of the air has reacted with pyrite to produce ferrous sulphate and free sulphuric acid. This reaction appears in many chemistry texts and generally has not been considered worthy of further study. Since the measurement of hydrogen ion concentration or activity was developed and expressed in terms of pH, indicator and instrumental methods for pH determination have become readily available, making it natural to think of it as a measure of acid content. Special purpose analytical methods applicable to potable waters, sewage effluents, and boiler waters, based in general upon the determination of what may be regarded as impurities, have been applied to more concentrated solutions constituting mine discharges, without reference to the fact that these specialized procedures had been developed to serve as operating guides for water-treatment plants. It has been assumed that the pounds of acid deliv- Table I. Showing pH and Titratable Acid of Varying Concentrations of Ferrous and Ferric Sulphates Ferric Ferrous ion Acldfty Ion Acidity (Fe+++) ppm CaCO3 We++) ppm CaCOa ppm PA equiv. PPm pH equiv. 11.200 1.80 30,000 11,200 3.98 20,000 5,600 2.01 15,000 5,600 4.15 10,000 2,800 2.21 7,500 2,800 4.41 5,000 1.120 2.48 3,000 1,400 4.68 2.500 560 2.60 1,500 140 5.00 250 280 2.65 750 28 5.00 50 112 2.81 300 56 3.07 150 28 3.38 75 ered by a mine was roughly a constant varying with the number of acres mined, and that the concentration of the acid in the drainage was inversely proportional to the volume of flow. Increased flow was thought to result in a dilution of the acid produced. When the Sanitary Water Board of the Commonwealth of Pennsylvania established a fellowship at Mellon Institute, the first approach to the problem was to review some of the chemical reactions involved and their relation to acid production. Since the sulphates of iron were among the principal constituents of coal-mine drainage, the first studies were based upon solutions of chemically pure ferrous and ferric sulphate. These are both neutral salts, that is, the iron and the sulphate are equivalent, but they produce acid reactions in water solution because as salts of strong acids with weak bases, they hydrolyze to form acid solutions. Solutions of each salt, of varying concentrations, were prepared and the pH, titrable acidity and iron and sulphate

Jan 1, 1952

By H. W. Becker, C. C. Frye, A. V. Degau, A. Masuda

Natural gas containing 25.65 per cent hydrogen sulfide and 4.75 per cent carbon dioxicle is gathered frorn eight \veih arid tratzsporrcd 26 miles at a flow rate of 160 MMcf/D and at operating pressures of frotrl 1,200 to 1,800 psig. Dry desiccant dehydrators at each wellsite tnaintaitz the dew point of the gas below 17F. Telemetering facililies permit control of field operations from a central instrunlent console. Corrosion control ineasures, design coilsiderations and material specifications pertainitz to these specia1 conditions are cliscussed. INTRODUCTION Natural gas containing 25.65 per cent H2S and 4.75 pcr cent CO, is produced from the Pine Creek field, Alta. It is dehydrated at wellheads, gathered at 2.200 psig and transported 26 miles to the Windfall field where it is delivered to the inlet of injection compressors at 1,800 psig. The daily average volume of gas transported is 160 MMcf. The project is believed to be unique in its combination of percentage of hydrogen sulfide, operating pressure and transportation distance. This paper describes the project and presents details of some of the design features, corrosion control program and centralized automatic operational control. The Pine Creek field project is one phase of a joint operation of two fields—thc other being the Windfall field. The two fields lie about 30 miles north of Edson, Alta. and 20 miles west of Whitecourt, Alta., respectively, as shown on the map (Fig. 1). They are owned by the same interests and operated according to a plan for maximum economic recovery of products. The Windfall Leduc D-3 reservoir contains a rich condensate-bearing gas containing 15.5 per cent HIS. The gas from the Pine Creek field contains only very small quantities of butane and heavier products. The Windfall reservoir is being cycled to obtain maximum condensate recovery using gas from the Pine Creek field as the displacing fluid, while producing the residue sales gas for both fields from the Windfall field. The Pine Creek field development and gas-gathering facilities are shown on the map (Fig. 2). The producing formation is the Leduc D-3 reef at a depth of 11,300 ft. The original reservoir pressure was 4,590 psia at 7,400 ft subsea and the temperature is 245F. Eight wells are equippcd with dry desiccant dehydrators with the following capacity ratings: three at 35 MMcf/D; three at 20 MMcf/D; and two at 10 MMcf/D. WELLHEAD EQUIPMENT Dry desiccant dehydrators were designed to reduce the water content of the saturated wellhead stream to 2.5 lb of water/MMcf at 2,000 psig. This specification was necessary to prevent hydrates and corrosion forming in the pipeline which will operate at temperatures as low as 20F. A typical flow diagram is shown in Fig. 3, and Fig. 4 is a photograph of one of the wellhead installations. Some of the design details given below are subject to modification in the field. The well-stream flowing temperatures range from 135 to 170F. Wellhead flowing pressures up to 3,200 psig are reduced to the dehydrator-operating pressure of about 2,100 psig by throttling through a pressure control valve. The gas is then passed through an aerial cooler where its temperature is reduced to 105F. thus removing over half

By C. H. Gorski

A method for preparing titanium tetrachloride is described which consists of reducing rutile with coke and chlorinating the reduced product at 200° to 500°C. The crude distillate is purified by treatment with copper powder and distillation. Recoveries, exceeding 90 pct of the titanium in the rutile, were obtained. IN recent years considerable interest in metallic titanium has been aroused because of its outstanding physical and chemical properties. The present commercial processes for preparing titanium are modifications of the Kroll1 process and consist essentially of the reduction of titanium tetrachloride with magnesium in an inert atmosphere to produce metallic titanium with magnesium chloride as a byproduct. At present,' commercial titanium tetrachloride costs $0.32 a pound, which makes the price of the included titanium $1.28 a pound. As the titanium tetrachloride must be purified further before processing into metal, its ultimate cost obviously will be higher. Consequently, one of the prime requisites for the production of lower cost titanium metal is a source of low-cost titanium tetrachloride. Recently, Knickerbocker, Gorski, Kenworthy, and Starliper3 escribed a method for preparing titanium tetrachloride from low-grade Arkansas rutile by smelting the rutile with pyrite and coke to form a titanium matte and then chlorinating the titanium matte to prepare a crude titanium tetrachloride. This process had several inherent advantages. Low-grade rutile concentrates were utilized, the chlorination temperature was relatively low (approximately 200°C), and the reaction was strongly exothermic. However, this process had several disadvantages, chief of them being the rather low recoveries of titanium tetrachloride (65 to 81 pct) and the difficulty in purifying the crude titanium tetrachloride obtained. Because of the high-titanium and low-iron con- tents of rutile as compared to ilmenite, rutile should be of greater potential value as a source of titanium tetrachloride than ilmenite. Rutile, however, is not chlorinated directly in commercial practice, because reaction temperatures above 700 °C are required, at which point chlorine attacks most of the common materials of construction. The process now in use consists of converting the titanium in rutile to the cyanonitride by high-temperature reduction in an electric furnace, and then chlorinating this compound. The disadvantages of this process are the difficulty of producing the cyanonitride, the use of high-grade rutile concentrates in the charge, and the presence of several percent of silicon tetrachloride in the finished product. It would be of considerable interest to develop a new process for the preparation of titanium tetrachloride from rutile by chlorination at 200" to 500°C. Process Development Several investigators'-' have studied the reduction of titanium dioxide with carbon in an effort to prepare titanium monoxide. Invariably, the titanium monoxide formed in this manner was not pure, as it contained titanium carbide and one or more of the lower oxides of titanium. As these lower oxides of titanium are more reactive chemically than rutile, and as it is known that titanium carbide may be chlorinated readily, a study was made of the chlorination of carbon-reduced rutile. A sample of rutile concentrates from Hot Spring County, Ark., containing 76.19 pct TiO,, 5.65 pct Fe2O3, 4.18 pct SiO2, and 2.88 pct Al2O3, was used for this investigation. The experimental procedure consisted of making an intimate mixture of —100-mesh rutile and petroleum coke, adding water and molasses as a binder to foi-m a paste, charging into a graphite crucible that was covered, except for a vent to allow the

Jan 1, 1952

By P. R. Swann, J. G. Parr

Quenched structures were studied in alloys containing up to 12.5 pct cobalt. The subsequent decomposition of a 10 pct cobalt retained-ß phase alloy was investigated using metallographic and X-ray diffraction methods. Hardness measurements also were made during the decomposition process. Precipitation of Ti2Co is by nucleation and growth; and an activation energy of 50,000 cal per mole was determined. The values of the coefficient ß suggest that the precipitate is pearlitic at temperatures between 450 and 475°C, and spheroidal between 500 and 525°C. THIS paper describes part of a series of invesligations into phase transformations in binary alloys of titanium with transition elements. The general approach is similar to that taken in work on titanium-iron and titanium-nickel alloys.' Previous investigators'' have established the titanium-rich end of the titanium-cobalt phase diagram, reproduced in Fig. 1. Orrell and Fontana' showed that alloys containing more than about 6 pct" cobalt quenched from the ß range, produced 100 pcl retained-p phase. The isothermal decomposition of alloys containing between 0.8 pct Co and 15.5 pct CO was investigated by the same workers in the temperature range 650 to 1000°C. They reported that these alloys transformed into a or Ti,Co depending on the cobalt content, but no quantitative data were given. In the work to be described a series of alloys containing 0.8 pct Co to 12.5 pct Co was examined in the quenched condition. The 10 pct Co alloy (the lowest cobalt content to retain 100 pct ß on quenching) was selected for further work on the tempering kinetics of the ß decomposition. Experimental Procedure Since our own melting equipment was not installed at the outset of this work, the Physical Metallurgy Division of the Department of Mines and Technical Surveys (Ottawa, Canada) prepared the alloys. These were made of Japanese sponge, (which when melted had a value of 103 DPH, using a 1-kg load), and electrolytically prepared cobalt. The al- loys, made up to contain 0.8, 1.6, 3.3, 5.8, 8.3, 10.0 and 12.5 pct Co, were homogenized by swaging into rods at 900°C. Filings were taken from the rods, and any iron chips from the file were separated magnetically. Size fractions of both plus and minus 200 mesh (about 75p) were shown by their constitution, after annealing just below the eutectoid temperature, to contain the same cobalt content. Consequently, it was permissible to use the —200-mesh fraction, knowing it to be representative of the rod composition. Quenching in argon was carried out in a newly designed furnace, whose features include (1) an Inconel furnace tube, (2) a positive pressure of argon maintained at all times in the furnace—even when a sample is removed or inserted. The furnace is shown in Fig. 2 and is described in the Appendix. The tempering processes were carried out on powder samples sealed in evacuated quartz capsules. Since the highest tempering temperature was 525OC, no protection against reaction with the quartz was necessary. (Tests were made on filings of iodide titanium and showed no hardness increase after equivalent heat-treatments.) A thermocouple was attached to the capsule, which was heated to the

Jan 1, 1959

By D. J. Pye

Certain high molecular weight synthetic polymers in very dilute solutions decrease water mobility in porous media 5 to 20 times more than would be expected from the solution viscosity. This indicates that increasing water viscosity to reduce adverse mobility ratios in water floods is economically feasible in many situations. Laboratory results are consistent with accepted theory with respect to improved areal sweep, permeability distribution and displacement efficiencies as would be predicted from the solution mobility measured in the core. The laboratory results have been confirmed by field pilot floods which recovered 80 per cent and 100 per cent more oil than comparative water-flood pilots in fields containing 16 cp and 130 cp oil respectively. Economic analyses based on pilot data indicate the method to be profitable. INTRODUCTION The desirability of improving the water-oil mobility ratio in waterflood-ing operations has long been appreciated, especially for high viscosity crudes. Methods of reducing the oil viscosity by application of heat, gas resaturation and miscible drives have met with some success. Conversely, it has been generally conceded that increasing the water viscosity would also be effective, but the amount of thickening agent required to effect an appreciable increase in viscosity is discouragingly high. The use of such materials as glycerin, sugar, or glycols is completely out of the question economically, so that considerable attention has been given to the use of the much more efficient synthetic water-soluble polymers as viscosity improvers; but even these materials are not economically attractive. If increased water viscosity could be economically realized, marked improvements in areal sweep efficiency, as discussed by Caudle and Wittel and others, would be realized in field operations. Similarly, the improved mobility ratio would bring about increased recoveries by correcting permeability distribution problems as discussed by Stiles2 and Dykstra and Parsons,' and improvements in displacement efficiency would be obtained as recognized by Buckley and Leverett4 and Welge.5 LABORATORY STUDIES THE RESISTANCE EFFECT In the course of research to develop a more efficient water-soluble polymer viscosity builder, we discovered that a very few types of water-soluble polymers exhibited a most unusual and very interesting property not previously observed. Among the earliest materials showing such activity were polymers containing acry-lamide. Fig. 1 shows a typical plot of the solution viscosity vs concentration for one of these polymer solutions as determined in an Ostwald viscometer. As usual, such a plot is an approximate straight line on semi-logarithmic paper. Now, an inspection of Darcy's law, shows that a viscosity value can also be determined in a formation sample if the pressure, flow rate and permeability are known. If the core permeability is previously determined with wa- ter or brine, then the viscosity of another aqueous fluid may be determined from the equation. The viscosities so determined for glycerin (glycol or polyvinyl alcohol solutions, for example) agree with the viscometer determinations. However, in the case of the water-soluble polymer solutions in which we are interested, the viscosities measured in the formation sample depart very markedly from the viscometer values. A typical relationship for a polymer solution is also shown in Fig. 1. This unusual departure from the expected response is referred to as a resistance property of the polymer and is quantified as "resistance factor". Since the resistance factor R can best be determined in a core under study, the term has been defined on the basis of the ratio of the brine mobility to the polymer solution mobility at residual oil saturation so that:

Jan 1, 1965

By J. R. Kyte, C. C. Mattax

Previous workers have developed differential equations to describe oil displacement by water imbibition, but have not explicitly defined the relationship between recovery behavior for a single reservoir matrix block and its size. In the present work, imbibition theory is extended to show that the time required to recover a given fraction of the oil from a matrix block is proportional to the square of the distance between fractures. Using this relationship, recovery behavior for a large reservoir matrix block is predicted from an imbibition test on a small reservoir core sample. The prediction is then extended to analyze recovery behavior for fractured- matrix, water- drive reservoirs in which imbibition is the dominant oil-producing mechanism. Experimental data are presented to support the basic imbibition theory relating matrix block size, fluid viscosity level and permeability to recovery behavior. INTRODUCTION Imbibition has long been recognized as an important factor in recovering oil from water-wet, fractured-matrix reservoirs subjected to water flood or water drive. l-3 Recently, two approaches have been published which might be used to predict imbibition oil-recovery behavior for reservoir-sized matrix blocks. Graham and Richardson4 used a synthetic model to scale a single element of a fractured-matrix reservoir. lair,' on the other hand, used numerical techniques to solve the differential equations describing imbibition in linear and radial systems. This latter method requires auxiliary experimental data in the form of capillary pressure and relative permeability functions. These two approaches, i.e., synthetic models and numerical techniques, have been used to study a variety of reservoir fluid-flow problems. One pur- pose of this work is to present, with experimental verification, a third method for predicting imbibition oil recovery for large reservoir matrix blocks. This method uses scaled imbibition tests on small reservoir core samples to predict field performance. The imbibition tests are easier to perform than the capillary pressure and relative permeability tests required to apply the numerical method. Furthermore, when suitably preserved reservoir-rock samples are used, the properties of the laboratory system are the same as those of the field. This offers an important advantage over the use of synthetic models because there is usually some question as to how accurately reservoir-rock properties can be duplicated in such models. Based on the recovery behavior for a unit matrix block, an analysis is presented to predict oil recovery for a fractured, water-drive reservoir made up of many such unit blocks. In the analysis, it is assumed that the flow resistance and the volume of the reservoir fracture system are negligible compared with that of the porous matrix. These assumptions are generally consistent with observed characteristics of many fractured-matrix reservoirs, and have been employed in previous studies.2,3,6-8 further assumed that the effect of gravity on flow in the matrix blocks is negligible. On first thought, the latter assumption might appear to seriously limit application of the method. However, in a fractured reservoir, the effect of gravity on flow in a matrix block will be restricted by the height of the block. Furthermore, matrix permeabilities are often very low (10 md or less) in such reservoirs. This means that capillary or imbibition forces will be large, thus tending to minimize the relative importance of gravity. For these reasons, imbibition should be the dominant oil-recovery mechanism in many fractured-matrix, water-drive reservoirs. The predictive method presented in this report is applicable to such reservoirs. SCALING IMBIBITION THEORY The "scaling laws" applicable to the operation.

By D. J. DeLazaro, W. Rostoker, R. E. Riley, M. Hansen

KNOWLEDGE of the isothermal transformation behavior and the TTT chart method of graphically summarizing such information has been of invaluable aid to the ferrous metallurgist in understanding and developing heat treatments intended to provide specific mechanical properties. It is to be expected that similar lines of study directed to titanium-base alloys will be as profitable. This paper summarizes, on conventional TTT charts, the isothermal transformation products and pertinent reaction rate data for binary alloys of titanium containing 1, 3, 5, 7, 9, and 11 pct Mo, respectively. The results so presented were derived from metal-lographic examination. Some X-ray diffraction work was done to clarify certain points of question. Ti-Mo System To the authors' k.nowledge, TTT charts have only been used to describe the reaction rates of eutectoidal decompositions. It would seem that the kinetics of decomposition of any unstable solid solution might be conveniently described in this manner. The equilibrium diagram of the Ti-Mo system' is shown in Fig. 1. The similarity with the Fe-Ni system will be recognized. Additions of molybdenum serve to stabilize the /3 phase to increasingly lower temperatures. The solubility of molybdenum in the a phase is restricted to less than 1 pct at 600°C. Under normal conditions. a homogeneous ,8 structure quenched to a, temperature in the a f & field will reject a of invariant composition. The rate at which this occurs depends on the degree of undercooling and the degree of supersaturation of /3. The structural character of the rejected phase may also be expected to be related to the undercooling. Materials and Experimental Methods A sponge titanium was used which has a nominal impurity content as reported in Table I. The nominal composition of the molybdenum used is also included. The alloys were prepared in 150 g melts by arc melting in an evacuated water-cooled copper crucible of the type reported in an earlier paper.' The pancake-type ingots were forged to 1/4x1/4 in. bars and homogenized for 24 hr at 1000°C in evacuated Vycor bulbs. Specimens Vi in. thick were cut from these bars for heat treatment. The heat treatment cycles followed an invariant procedure. The specimens were soaked at 1000°C for 20 min under a helium protective atmosphere prior to quenching into a lead bath held at a temperature corresponding to a chosen degree of undercooling. After a prescribed period of time at this temperature, the specimen was removed and water quenched. A series of specimens so treated for progressively longer periods served to establish the times for initiation and completion of the decomposition of the /3 phase at a particular temperature. Although heat treatment of unprotected specimens in a lead bath does permit surface contamination by lead diffusion, this method is necessary to insure sufficiently rapid quenching rates. As long as the bath treatments were of less than 1 hr duration. the contaminated surface was not unduly deep and could be removed without excessive grinding. Metal-lographically, the contaminated zone could be readily distinguished from the pure binary alloy. Transformation Characteristics of Ti-Mo Alloys Metallographic examination showed that a supersaturated p phase may decompose by one of two processes. Alloys containing 1 to 9 pct Mo, when quenched in water from the homogeneous /3 field,

Jan 1, 1953

By Thomas W. Wälde

BACKGROUND Foreign investment has been a major factor in bringing about the substantial mining industries of Chile, Peru, Bolivia, Venezuela, Brasil and Guyana. But economic nationalism and sentiment against foreiqn domination of vital national industries grew in the 1960s and most major mining projects were transferred into state owner ship. Among the state mining enterprises formed were CODELCO - Chile, MINERO-PERU/ CENTRCMIN - Peru, CCMIBOL - Bolivia (in 1952), Hierro-PERU, GUY-BAU/BIDCO - Guyana, etc. New investment during that time was discouraged because it was subject to the restrictive conditions of the investment regulations of the Andean-Pact, a grouping of Chile, Bolivia, Peru, Ecuador, Venezuela and Colombia. The philisophy was that mineral resources were to be developed exclusively by national enterprises. Essential foreign inputs had to be acquired "depackaged" as separate purchases of equipment and technical assistance services. As a result of the worldwide economic recession which hit the mining industries in 1980-1982, many projects that were viable in 1970 were not developed by the new state enterprises due to lack of capital, managerial and technical abilities and due to problems with marketing. As a consequence of the long-term decline of metal prices, governments experienced difficulty in getting investment organized through national or foreign enterprises and have had to face up to the trade-offs between national control and active mineral development. A change has since taken place in governmental policies. The 1981 Peruvian mining law, the 1982 mining law of Uruguay, the 1979/1980 mineral promotion laws of Argentina, all witness the gradual shifting of emphasis from restriction to promotion. The investment rules of the Andean Pact have been progressively softened through national regulation and today are more or less irrelevant. Nationalizations and forced renegotiations have not occurred in the last few years. Countries have gone to great lengths (without much success) to re-attract foreign investment on terms that accommodate the political sensitivities of the South American countries and the practical requirements of investors and financiers. For this analysis, three contracts have been selected which reflect this accommodation in three South American countries, where miner a1 production plays a major role in the national economy. These con tracts reflect both the attitudes and traditions of the individual countries, but also mark the shift in mineral investment policies that has taken place. EL INDIO AGREEMENT The 1977 investment agreement between Chile and St. Joe Minerals marked a dramatic relationship between Chile and foreign mining investor s. In Chile, mining of copper has played a major role in the country's history. Large scale copper mining was initiated and developed by Kennecott and Anaconda. The nationalization of these two companies under the Allende government in July 1971 started a wave of nationalizations of foreign-held mining and petroleum operations since then in many parts of the world. The military government supported the new Chilean state mining companies ((30DELCO and ENMI) , but it also attempted to accelerate mineral development by prom ting foreign private investment, thus reversing the nationalistic policies followed by the Allende and the preceding Frei government. The new policy by the military government is expressed in Decreto-Ley 600 (1974) which governs foreign investment in Chile. Decreto-Ley 600 is

Jan 1, 1985

By N. S. Stoloff, R. G. Davies

The annealing behavior of a heavily cold-worked FeCo-V alloy has been studied at temperatures both above and below Tc, the critical temperature for ordering. It was found that re crystallization and grain growth can take place below Tc in the ordered state and that, in agreement with results for fcc alloys, order retards grain growth. The activation energy for pain growth is -55 kcal per mole in the disordered condition; it was not possible to assign a value to the activation energy for grain growth below Tc because the degree of order is changing rapidly over the temperature interval investigated. Precipitation of an fcc y phase was observed upon annealing the cold-worked alloy at temperatures of 675°C and below. SINCE it is known that diffusion constants are greatly affected by long-range order,' it is not unreasonable to anticipate that order will influence the diffusion-controlled phenomena of recrystallization and grain growth. In the course of a study of strain aging of ordering alloys around the composition Ni3Fe Vidoz, Lazarevic, and cahn2 noted that a disordered cold-worked alloy annealed at a temperature T1 just below Tc will order but not recrystallize; Tc is the critical temperature for order. The same alloy annealed at a temperature T2 just above Tc, or an alloy of different (nonordering) composition annealed at either T1 or T2, will recrystallize after equivalent amounts of cold work. Initially Selisskii and coworkers,3,4 who examined a series of cold-worked and annealed bcc Fe- Co alloys, reported that alloys forming the B2 FeCo super lattice could not be recrystallized below Tc. However in a later paper5 it was shown that FeCo ordered alloys could be recrystallized below Tc. Thus the first question to be answered by the present investigation was whether or not a heavily cold-worked Fe-Co-V alloy could be recrystallized below Tc. When it was found that the alloy would indeed re-crystallize below Tc, the influence of long-range order upon subsequent grain growth was studied. EXPERIMENTAL PROCEDURE The grain-growth measurements were made upon FeCo-2 pct V wire of 0.031 in. diam; the alloy was the same as that used in an earlier study of the mechanical properties of FeCO-v.6 The wire was produced by cold swageing and drawing a rod 0.125 in. diam that had been quenched into iced brine from 850°C to disorder the alloy; the initial grain size was 0.05 mm. Rates of grain browth were measured after isother-mally annealing the wire in the temperature range 675° to 825°C; T, is -720°C. Grain diameters were measured on the transverse cross section of the wires. The line-intercept method of determining the grain diameter was used; conventional light photomicrographs were taken when the grain size was greater than 10 . Carbon replicas were produced and examined in the electron microscope if the grain size was less than Dislocation configurations after recrystallization anneals were studied by electron transmission microscopy of foils produced by cold rolling a 0.125-in.-thick strip of the quenched material to 0.012 in. The foils, after heat treatments similar to the wire samples, were thinned by electropolishing in a chromic-

Jan 1, 1967