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The paper relates to the laboratory and pilot plant studies that have been carried out by Sherritt Gordon Mines Ltd., Metallurgical Research Div., in developing the ammonia pressure leach process for extracting Cu, Ni, Co, and S from high grade Ni concentrate produced from Lynn Lake ores and describes in some detail the chemistry of the process. In the leaching stage air, ammonia, and sulphide minerals react in a sequence of inter-related steps to produce soluble amines of Ni, Cu, and Co in a solution containing sulphate, thiosulphate, polythionate, and sulphamate ions and a controlled amount of free ammonia, the iron and other components of the concentrate remaining as an insoluble residue which is separated from the leach solution by filtration. The pregnant solution produced in leaching is further treated by boiling to precipitate and remove Cu as cuprous sulphide, leaving a copper-free solution with a composition suitable for subsequent precipitation of Ni and Cu by H,

Jan 3, 1955

By Richard D. Mills

Throughout the mining industry, many companies perform sophisticated business and financial analyses of proposed capital investments. However, once the project is approved, it is never reevaluated. At best, there is an attempt to control capital costs and minimize overruns. The post-installation appraisal, a formalized review of investment performance, may prove helpful. Typical Project Review A typical capital investment is approved after business and financial benefits have been reviewed with management.* The financial data shown to management often include a net income statement, cash flow analysis and summary economic data similar to those shown in Table 1 overleaf. These financials report the expected impact of the project on the corporation financial statements. This project is a rudimentary example of a capital investment decision. An actual project would undergo a more sophisticated analysis incorporating depletion benefits, deferred taxes and a detailed cost breakdown. The example project has several financial benefits that could result in management approval. For example, it provides an immediate net income benefit to the company, generates positive cash flows every year of the project life and has a discounted cash flow rate of return of 25 percent. However, it also has the disadvantage of a long payback period. A sensitivity analysis would show which areas of the analysis have the greatest impacts on profitability. Post-Installation Program Objectives The post-installation appraisal goes beyond the analysis shown in Table 1 by comparing actual results to those projected in the original economic analysis. The post-installation program has three primary objectives: 1. To provide a periodic performance review of major spending programs. 2. To review decision-making and evaluation procedures. 3. To provide a means of controlling individual project investments. The first major function of the post-installation program is the periodic review of actual performance of projects and investment programs, identifying those factors which proved critical to the health of investments. This review will serve to keep management abreast of progress, provide a comparison of actual performance against expectations, and provide valuable information that can be used for improving future economics. The second major function of the program is to perform a continuous review of the decision-making process. This includes testing of evaluation procedures, forecasting techniques, and logic used in making decisions. An information system should be set up whereby original evaluations and historical performance data gathered under the appraisal program are documented for use by evaluators and management when assessing past and future investment proposals. Such data should be particularly useful in evaluating new and developing types of operations and in activities where companies repeatedly reinvest. The primary purpose of this feedback system is to sharpen estimates to assure that they are realistic and attainable. The appraisal program also provides assurance that consistent evaluation procedures are being used throughout a company, leading to improved procedures

Jan 1, 1985

By J. William Fehnel

The health hazard due to the inhalation of certain dusts in the mining industry has been recognized, but was not subject to state or federal inquiry in the United States until about 1916. Reports on miners' phthisis and associated effect of dust inhalation were published as early as 1903 in South Africa and in 1906 in Australia. A report was made by Lanzal in January 1917 of a study of 433 cases of miners' consumption among zinc miners in southwestern Missouri. In a preliminary report issued in 1915 Lanza and Higgins2 concluded that, while there were general causes, such as housing and working conditions, that tended to produce a high incidence of tuberculosis, the flint dust constituted an unusual element of danger, to which it was reasonable to attribute the unusual prevalence of tuberculosis. Later a clinic established under the joint sponsorship of the United States Bureau of Mines, the mine owners, and the Metropolitan Life Insurance Co. carried on an extensive study covering a period of five years. The results of this study have borne out the conclusions reached in the earlier surveys. The early surveys in this country indicated the necessity of determining the extent of the dust pollution of air associated with the various mining operations. The first determinations were reported on the weight basis, undoubtedly to make comparisons with work previously done in Australia. Later studies of dust in industry led to the development of more refined methods of sampling and enumeration on the basis of count in place of weight, so that by 1919 Knowles3 reported 53 methods.

Jan 1, 1937

By AIME AIME

THE steel industry has always been noted for producing men of forceful and versatile personality, many of whom combine the practicality that results from wide experience with an excellent theoretical background that comes from a college training plus years of wide and constant study of metallurgical literature. One of the best known examples of this type is Earle C. Smith, present Chairman of the Iron and Steel Division. After graduating from Ohio State and from Columbia, where he studied under Campbell, Earle started his career at that grand old prewar training school for steel men the Illinois Steel Co., where in the days of the twelve-hour shift he worked on the open-hearth floor. Following World War I, when he was in charge of government inspection at the Central Steel Co., Massillon, Earle held successively jobs of increasing responsibility with Central Alloy Steel, and when this company was taken over by Republic in 1930 he was made assistant district manager and a few years later was appointed chief metallurgist of the whole corporation.

Jan 1, 1942

By R. B. Lincoln

THE function of a pyrometer protecting tube is to maintain an atmosphere about the thermocouple most favorable to its continued accuracy and long life, and at the same time permit the weld of the couple to attain the full temperature of the area or object being measured. In addition to protecting the thermocouple from the chemical or alloying effects of the products of combustion or bath being measured, the tube must also protect the couple from mechanical injury. The conditions met in practice vary so much that no one material is suitable for all applications. The usefulness as well as the expense of maintenance of a pyrometer system are influenced greatly by a choice of the most suitable protecting tube. The tube must protect the couple without itself becoming too great an expense item. The protecting tube should have the following qualities: (1) A melting point well above the highest temperature to be encountered. (2) Sufficient strength through the entire range of temperatures to hold up its own weight and resist such shock and jar as are unavoidable. (3) It must be impervious to the atmosphere or bath to which it will be subject. (4) It must not give off any vapor injurious to the couple. (5) It must not form any oxides fusible below the highest temperature to be measured. The proper location of the tube in the furnace is almost as important as the choice of material. The tube must be placed as near to the work to be heated .as possible. It must be kept out of the direct path of flame, both because that would give too high temperature readings and because partly burned fuel will destroy the tube faster than the quiet products of combustion.

Jan 9, 1919

By K. R. Van Horn, L. W. Kempf

Plastic deformation of most commercia1 metals within a sufficiently low temperature range results in profound changes in structure and properties, of which the causes and effects are not completely understood. One of these effects is the presence of internal residual stresses and strains, which ordinarily do not appear to require specific consideration in most structural applications but which may be quite undesirable in particular instances. For example, in heavy sections that require considerable machining before assembly, residual stresses may be undesirable because of the distortion they cause when their balance is disturbed by machining or otherwise. In addition, the distribution of stresses may be such that it acts in the same direction as the applied load, thus bringing about premature failure or reducing the load-carrying capacity of the member. One source of residual stress in metal structures is the plastic deformation that may occur during rapid cooling from relatively elevated temperatures, as in the cooling of a casting in the mold or the quenching of a heavy section from elevated temperatures during heat-treatment. These residual stresses are usually undesirable because their direction of operation and magnitude cannot be controlled well enough to permit utilization of the changes in properties of the metal that they may bring about. The most convenient manner of controlling such residual stress is by proper selection of the cooling rate or by reheating to a temperature at which plastic flow can take place, resulting in relief of the residual stresses and strains. Both of these methods of control, however, may cause a reduction in the optimum properties obtainable from the previous operation. A compromise must be struck, and if it is to result in the best possible combinations of properties, specific information must be available regarding the magnitude of the stresses and the rate at which they are affected by variations in cooling rate or in reheating temperature. The complete quantitative estimation of residual stress in complicated metal shapes is exceedingly difficult, if not impossible. In simple sections, however, relatively quantitative analysis may be applied and useful cstimations of stress distribution may be made. This paper is concerned largely with the rate of relief, upon reheating, of internal residual stress in simple aluminum-alloy structures. Since even with simple structures quantitative estimation of residual stresses is laborious and costly, an attempt was made to find other means of collecting data upon which commercial heat-treatments might be based. Incidentally, a few data were collected bearing on the problem of relaxation of aluminum alloys. Determination of Residual Stresses The magnitude and distribution of residual stresses in simple aluminum-alloy shapes rapidly cooled from elevated temperatures has been discussed in a previous paper.' Fig. I reproduces some of the data

Jan 1, 1942

By L. W. Kempf, K. R. VanHorn

PLASTIC deformation of most commercial metals within a sufficiently low temperature range results in profound changes in structure and properties, of which the causes and effects are not completely understood. One of these effects is the presence of internal residual stresses and strains, which ordinarily do not appear to require specific consideration in most structural applications but which may be quite undesirable in particular instances. For example, in heavy sections that require considerable machining before assembly, residual stresses may be undesirable because of the distortion they cause when their balance is disturbed by machining or otherwise. In addition, the distribution of stresses may be such that it acts in the same direction as the applied load, thus bringing about premature failure or reducing the load-carrying capacity of the member. One source of residual stress in metal structures is the plastic deformation that may occur during rapid cooling from relatively elevated temperatures, as in the cooling of a casting in the mold or the quenching of a heavy section from elevated temperatures during heat-treatment. These residual stresses are usually undesirable because their direction of operation and magnitude cannot be controlled well enough to permit utilization of the changes in properties of the metal that they may bring about. The most convenient manner of controlling such residual stress is by proper selection of the cooling rate or by reheating to a temperature at which plastic flow can take place, resulting in relief of the residual stresses and strains. Both of these methods of control, however, may cause a reduction in the optimum properties obtainable from the previous operation compromise must be struck, and if it is to result in the best possible combinations of properties, specific information must be available regarding the magnitude of the stresses and the rate at which they are affected by variations in cooling rate or in reheating temperature. The complete quantitative estimation of residual stress in complicated metal shapes is exceedingly difficult, if not impossible. In simple sections, however, relatively quantitative analysis may be applied and useful estimations of stress distribution may be made. This paper is concerned largely with the rate of relief, upon reheating, of internal residual stress in simple aluminum-alloy structures. Since even with simple structures quantitative estimation of residual stresses is laborious and costly, an attempt was made to find other means of collecting data upon which commercial heat-treatments might be based. Incidentally, a few data were collected bearing on the problem of relaxation of aluminum alloys. DETERMINATION OF RESIDUAL STRESSES The magnitude and distribution of residual stresses in simple aluminum-alloy shapes rapidly cooled from elevated temperatures has been discussed in a previous paper.1 Fig. I reproduces some of the data

Jan 1, 1941

By L. W. Kempf, K. R. Van Horn

Plastic deformation of most commercia1 metals within a sufficiently low temperature range results in profound changes in structure and properties, of which the causes and effects are not completely understood. One of these effects is the presence of internal residual stresses and strains, which ordinarily do not appear to require specific consideration in most structural applications but which may be quite undesirable in particular instances. For example, in heavy sections that require considerable machining before assembly, residual stresses may be undesirable because of the distortion they cause when their balance is disturbed by machining or otherwise. In addition, the distribution of stresses may be such that it acts in the same direction as the applied load, thus bringing about premature failure or reducing the load-carrying capacity of the member. One source of residual stress in metal structures is the plastic deformation that may occur during rapid cooling from relatively elevated temperatures, as in the cooling of a casting in the mold or the quenching of a heavy section from elevated temperatures during heat-treatment. These residual stresses are usually undesirable because their direction of operation and magnitude cannot be controlled well enough to permit utilization of the changes in properties of the metal that they may bring about. The most convenient manner of controlling such residual stress is by proper selection of the cooling rate or by reheating to a temperature at which plastic flow can take place, resulting in relief of the residual stresses and strains. Both of these methods of control, however, may cause a reduction in the optimum properties obtainable from the previous operation. A compromise must be struck, and if it is to result in the best possible combinations of properties, specific information must be available regarding the magnitude of the stresses and the rate at which they are affected by variations in cooling rate or in reheating temperature. The complete quantitative estimation of residual stress in complicated metal shapes is exceedingly difficult, if not impossible. In simple sections, however, relatively quantitative analysis may be applied and useful cstimations of stress distribution may be made. This paper is concerned largely with the rate of relief, upon reheating, of internal residual stress in simple aluminum-alloy structures. Since even with simple structures quantitative estimation of residual stresses is laborious and costly, an attempt was made to find other means of collecting data upon which commercial heat-treatments might be based. Incidentally, a few data were collected bearing on the problem of relaxation of aluminum alloys. Determination of Residual Stresses The magnitude and distribution of residual stresses in simple aluminum-alloy shapes rapidly cooled from elevated temperatures has been discussed in a previous paper.' Fig. I reproduces some of the data

Jan 1, 1942

By M. H. Loveman

THE orebody described below has been rediscovered and developed within the last 3 years. It has, however, been known and worked by the Chinese for hundreds of years. When assay values and size are considered, it contains what is probably one of the largest single bodies of zinc and lead sulphides yet found. The tonnages developed at other places, as at Broken Hill, are much greater but the average zinc and lead sulphide contents are considerably lower than at Bawdwin. Bawdwin is situated in the semi-independent State of Tawng Peng, one of the numerous units which make up the Northern Shan States. These States are under British rule and are generally considered as a portion of Burma. They are governed as a separate administrative unit, however, under the Lieutenant Governor of Burma. Each State is under its own chief, or Sawbwa, who has considerable power over his own subjects. Bawdwin is approximately in latitude N 23°6', longitude E 97°20', about 50 miles south of the nearest point on the Chinese border and 450 miles north of Rangoon (Fig. 1). The period at which mining was first begun at Bawdwin is unknown. The most reliable records have been obtained by deciphering local Chinese inscriptions and from these it is concluded that the work dates back to at least the beginning of the 15th century. The first undoubted reference to the mines by a European is by Symes in 1795. Crawford in 1827 estimated the output of silver from the mines at $600,000 annually. At about the middle of the 19th century the rebellion of the Chinese Mohammedans in the neighboring Chinese province of Yunnan so weakened the power of the Chinese that the incursions of hostile tribes (Kachins) made work extremely dangerous. The mines were finally abandoned by the Chinese about 1868. The closing down of the mines was probably not entirely due to outside causes but may have been influenced somewhat by the increasing difficulty of handling the water, as the workings gradually descended below the water level of the district. Several attempts were made by the Burmese kings, Mindon Min and Thebaw, to resume operations, but because of a

Jan 12, 1916

By Sandip K. Mukherjee, Anthony W. Laurito, Madan M. Singh, Jon C. Volkwein

In the past, little attention has been paid to the costs of ventilation, since it seldom represented a significant portion of the total mining cost. However, in recent years adverse mining conditions and increases in power charges have caused ventilation costs to rise. The federal regulations have set minimum standards for volumetric airflow rates in underground coal mines. As a mine develops, the air volume and pressure requirements increase. There are several methods by which the quantity of airflow to the mine and working faces can be increased. Some of the methods include (1) increasing main fan output or replacing the main fan by a new higher capacity fan, (2) reducing leakage across stoppings and overcasts, (3) adding a new ventilation shaft or borehole, (4) reducing resistance to airflow by reducing the resistance factor of the individual airways, increasing the number of airways (especially the parallel airways), or re- arranging the air courses by using the available entries, and (5) using auxiliary ventilation systems. This paper addresses the cost-benefit analysis of several of these alternatives as applied to a large operating coal mine located in southern Illinois. Pressure and quantity surveys were conducted under-ground, and measurements were taken at the main exhaust fans on the surface. The existing ventilation network was modeled by using the Penn State ventilation simulator. The input data included the configuration of branches, resistance of each branch (including a component for shock losses), and changes in pressure and volume. The results of the simulation were compared with the survey data to check the merits and accuracy of the model network. The net- work was designed to take into account shafts, major entries, overcasts, regulators, gob areas, working faces, and major leakage paths. The model network served as the basis for the cost analyses of networks designed for increased airflow. The applicable alternatives for increasing airflow were simulated. Performance data obtained from these simulation runs were utilized to conduct the cost-effectiveness analysis. The costs for each f the alternatives included capital, operating and maintenance costs. These costs were expressed as annual costs in terms of dollars per cfm of circulating air, taking into account the economic life associated with each of the alternatives. The benefits were expressed as increased airflow quantity in the critical sections. The result of these analyses show that for the short-range plans evaluated, the most cost-effective way of increasing airflow at this mine would be to reduce leakage through stoppings and overcasts.

Jan 1, 1982

POSITIONS VACANT (Under this heading will he published notes sent to the Secretary of the Institute by members or other persons.) In the course of the next few months, a mechanical engineer, who has specialized in the design and erection of copper-smelting plants, including steel work, power equipment, etc., may be required by a company operating abroad. Man speaking German preferred. No. 23. ENGINEERS AVAILABLE (Under this heading will he published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, 31 years of age, married, graduate of Massachusetts Institute of Technology, desires position with malleable iron or steel firm. Nine years' experience as chemist and metallurgist in malleable, gray iron, and steel. No. 123. Member, metallurgist, desires position with company making steel, castings, or tool steel. Has had six years' experience with the electric furnace, making steel castings and tool steel, also heat treatment of same. No. 124.

Jan 9, 1914

By C. Altstetter

THE work herein reported is restricted to the carbides which occur in quenched and tempered AISI 43XX steels with carbon contents up to 0.40 pct and silicon additions of up to 3 pct. In view of the instability and extremely small size of the carbides formed at low tempering temperatures, the technique for successfully preparing specimens for X-ray diffraction will be outlined. The alloys listed in Table I were obtained through the courtesy of the United States Steel Corp. in the form of 1/2-in. rounds forged from 100 lb. induction furnace heats (except for 4337 which was a commercial heat). The stock was normalized and then swaged and drawn to 15 mil wire with anneals at 1200F between passes. The wire was austenitized for 45 min in evacuated vycor capsules and quenched into iced brine with simultaneous smashing of the capsule. Tempering was done in air with a water quench after tempering. The carbides were extracted in a simple cell using a solution of 1M KC1 and 0.5 pct citric acid with an initial current density of 0.1 amp per sq cm. One end of a short length of wire was immersed in the solution, and the current at constant voltage was noted as a function of time. After about an hour the current dropped sharply because of the decrease in specimen cross-section. At this point it was found that the dissolution could be stopped and that the very fine wire which then resulted was just large enough to permit handling of the extracted precipitate still clinging to it, yet so small that it diffracted and absorbed only a negligible amount of the X-radiation. This rod of residue with a convenient handle of undissolved wire was rinsed in distilled water. alcohol, and acetone. Then it was dipped in a thin solution of cellulose-acetate cement and dried in vacuum. The resulting specimen was straight, uniform in density, easily handled, but most important, was completely sealed and never exposed to air. Furthermore, the residue had never been subjected to strong acids or rough handling such as in the extraction-replica technique or in the complete extraction to a powdered residue. It was found that improperly coated specimens were pyrophoric, turning to oxide with a dull red glow as they were exposed to air and yielding patterns of Fe2O3 and Fe3O4. The steels containing 3 pct Si were especially difficult to prepare for this reason. The specimens were put in a 57 mm Straumanis camera with double pinholes or slits and irradiated with filtered-chromium radiation. Readable patterns were obtained in less than an hour. A preliminary finding of some note was that for both tempered and as-quenched specimens of steels 4337 and 4337 (1.5 Si). M23C6 patterns were found along with the patterns of other constituents of the residues. This result was somewhat surprising in that previous investigators had reported that this carbide did not appear in a 0.38 pct C, 0.48 pct Mo steel1 or in chromium steels of less than about 10 pct Cr.2 Although the total amount of carbide-forming alloying elements is less than 2 pct, due to their mutual interaction and the action of the plastic deformation in promoting equilibrium, this carbide was able to form even in the steel containing 1.5 pct Si. M23C6 was not detected in the 4337 (3.0 Si) steel and the lower-carbon steels were not investigated in this condition. It is very likely then that the steels studied herein underwent a fourth stage of tempering during the anneals at 1200°F. This result has significance in that even a small amount of undissolved M23C6 in a low-carbon, low-alloy steel would exert a large effect on its hardenability. Its presence would also influence the mechanical properties by decreasing the carbon content of the matrix. Annealing in vacuum for 1 to 4 hr in the austenite field removed all traces of MZ3C+ The results on carbide precipitation during tempering, summarized in Table I, are in agreement with those of Klingler et al.3 for the higher carbon steels. For the AISI 4337 steels it is noteworthy that in the steels with added silicon the E carbide persists to longer times and higher temperatures and that silicon delays the formation of cementite. The results for the lowzr-carbon steels parallel those of the higher-carbon grade. The appearance of E carbide in the AISI 4315 is significant. There is considerable disagreem-nt in the literature as to whether this carbide forms in the tempering of steels containing less than about 0.2 pct C. Following the detection of E carbide in a 0.18 pct C plain-carbon steel,4 its occurrence in a steel containing chromium and molybdenum should be expected. The fact that the low-carbon steels have the same carbide-precipitation sequence as the high-carbon steels has bearing on the larger problem of the exact tempering reactions in all steels. Following the suggestion of Roberts et al.,' the first stage has been generally assumed to result in a metastable equilibrium of c carbide and martensite of about 0.25 pct C. From this it was concluded that a steel having less than 0.25 pct C should then be under-saturated with respect to c carbide and should not precipitate this carbide upon tempering. In view of the experimental findings of c carbide in steels hav-

Jan 1, 1962

By Harry M. Bendler, W. A. Wood

Electron metallography has been applied to the study of the torsional fatigue of polycrystalline OFHC* copper. The development of slip bands, fis- sures, and microcracks has been followed as a function of strain amplitude and number of cycles. Those factors that have been found to be relevant to a geometrical theory of the fatigue process are described. From the point of view of this theory it is important to distinguish between the effects of cycling at large amplitudes and at small amplitudes (true fatigue deformation). EARLY investigations showed metal fatigue cracking is caused by continued reversal of a small plastic strain. Fundamental study of fatigue, therefore, has been largely concerned with the cumulative effects of these plastic reversals on the metal structure. In particular, recent work has shown that the plastic reversals produce slip movements that are finer than the slip movements produced by unidirectional increments of plastic strain; individual slip movements in fatigue, for instance, are too fine to see by optical microscopy.2 It has also been shown that the fine slip movements of fatigue tend to concentrate in bands and that in this way they can build up, after enough cycles, a progressive surface disturbance. It is this disturbance which, in effect, makes the slip movement visible. It is also in this disturbance that the first cracks appear to form. From this point of view, therefore, the problem of fatigue becomes one of finding why the fine slip movements should concentrate in bands and why the. bands should finally open into cracks. Thus far, study of the slip bands has been limited to the changes they produce at the surface only. These studies have given interesting results. Ewing and Humfrey3 many years ago showed that the bands in iron could extrude debris. Forsyth found that bands in aluminum alloys could extrude thin tongues of material. Thompson showed that, after lightly dissolving away the surface of copper specimens, some bands persisted as superficial cracks might, and that the life of a specimen under fatigue deformation might be prolonged by dissolving away the surface at intervals. Thus these and related results have suggested that the metal structure in fatigue bands may disintegrate and that this may happen long before obvious cracking. These surface studies, however, have not shown definitely how cracking may begin, for they do not show sufficiently what is happening in depth. However, some advance in this direction has been made recently by a new approach, summarized later, which reveals slip bands and their surface disturbances in section. In the work done thus far, the sections have been studied by optical microscopy only. In the present work they have also been studied by electron microscopy with extended results. This paper also describes some observations on the surface disturbances prior to sectioning. These observations are relevant to a suggested theory of fatigue cracking. REVERSED SLIP MOVEMENTS Slip movements in fatigue deformation must reverse direction in each cycle. The question arises: DO the "backward" and "forward" movements take

Jan 1, 1962

By J. J. Frawley, W. J. Childs

PREVIOUS studies have shown that if a supercooled liquid metal was perturbed by vibration the probability of nucleation is is During a recent investi- gation to determine quantitatively the amount of energy needed to cause nucleation in a given supercooled liquid specimen, it was found that at low-energy values in the megacycle range, below the threshold energy value for cavitation, the amount of dynamic supercooling was greater than the amount of static supercooling. That is, if a specimen had a given amount of thermal supercooling under static conditions, its thermal supercooling could be increased by the addition of low-energy sound waves. The material used in this investigation was high-purity bismuth. This material was chosen because of its low melting point and the high degree of supercooling which could be easily obtained. The sound gener- ator employed in this work was a commercially built Sperry ultrasonic testing unit. This unit was equipped with a barium titanate crystal as a piezoelectric transducer. These sound waves were transmitted to the supercooled melt by a Pyrex rod, as shown in Fig. 1. The transducer was coupled to this Pyrex rod wave carrier by motor oil. The Pyrex wave carrier was approximately 1.5 ft long to prevent damage to the transducer by heat. The diameter of the Pyrex wave carrier appears to be critical. In the initial tests a wave carrier of 0.5 in. in diam was employed. However, the sound waves had no effect on the amount of dynamic supercooling. When the diameter of the wave carrier was increased to approximately the inside diameter of the Pyrex crucible, the sound waves were more effective. Approximately 200 g of metal was melted under a stannous chloride flux in a 30-ml beaker by induction heating. The temperature was recorded by a Pyrex-encapsulated chromel-alumel thermocoule which was placed in the beaker after the bismuth melted. The Pyrex wave carrier was immersed slightly below the surface of the liquid bismuth and the specimen was reheated to about 500°C. It was observed that the amount of supercooling depends on the amount of superheating the specimen receives; therefore, for meaningful results the amount of superheating was the same for all heating cycles. The specimen was allowed to cool in air and the change in temperature was continuously monitored with a potentiometric strip-chart recorder.

Jan 1, 1969

By L. E. Lynd

Ilmenite concentrates prepared from beach and dune sands of Florida, India, Australia, and other localities deviate to varying degrees from the theoretical composition of pure ilmenite, and generally contain more TiO2 than the formula FeTi03 would indicate, and some Fe2O3. This variation in composition is due to different amounts of altered ilmenite in the concentrates. (') The alteration has been shown to take place by oxidation and leaching of the iron in ilmenite, to yield residual products consisting of amaphous or very finely crystalline titanium dioxide and ferric oxide. Other studies(2) have stressed that ilmenite may alter first to an amorphous titanium-iron oxide, or to an amorphous mixture of titanium and iron oxides, with later alteration to crystalline titanium dioxide. There has been some speculation as to whether alteration of ilmenite is usually caused by weathering or by hydrothermal pr0cesses.(3,4,5 Three main methods of approach were used to study the mechanism and rate of ilmenite weathering. (1) Etch tests were used to learn the relationship between crystallographic orientation and the rate of chemical attack on ilmenite. (2) Altered ilmenites in New Jersey sands were compared with ilmenite in rocks of the area from which the sands were probably derived. (3) Experiments were carried out to determine at what rate, and by what agents, originally fresh ilmenite could be altered in the laboratory under simulated weathering conditions. ETCH FIGURES ON ILMENITE CRYSTAL PLANES A rather large ilmenite crystal from Sannidal, Norway, about 11/2 x 11/2 x 2 inches, bearing a few natural faces with imperfect surfaces, was prepared for etching by grinding and polishing crystal planes whose Bravais-Miller indices (referred to hexagonal axes) had been determined by X-ray methods to be 00.1, 10.0, and 10.2. Metallographic examination showed that the crystal was homogeneous, and uniform in orientation, except for the presence of twin lamellae which were oriented with their broadest surfaces parallel to the 00.1 planes of the large crystal. Since ilmenite is rather inert to standard etch reagents, strong solutions of hot sulfuric acid and cold hydrofluoric acid were used. Preliminary tests established that better etch figures were obtained using HF than with H2So4 solutions. The etch figures produced on 00.1 and 01.0 planes of ilmenite by etching 3 to 5 minutes in cold concentrated HF solution are shown in Figures 1, 2, and 3. The figures on 00.1 are "etch hillocks", rather than pits, and according to Honess(6), this phenomenon

Jan 1, 1961

By W. P. Sykes

In connection with a study of tungsten steels, Honda and Murakamil reported an investigation of the system iron-tungsten. This report included a tentative equilibrium diagram, photomicrographs of various alloys in the series, and qualitative measurements of hardness and magnetic properties. The present investigation originally had as its object the study of the hardness and tensile properties of a series of carbon-free iron-tungsten alloys. But, as the work progressed it became evident that the system possessed other features of interest, so the scope of the investigation was enlarged. Materials The iron powder used in preparing the alloys was obtained as follows : Iron oxalate was precipitated from a ferrous-sulfate solution by the addition of a solution of oxalic acid. This oxalate, after thorough washing, was ignited to iron oxide, which after reduction in hydrogen at about 1000" C. yielded iron powder containing but about 0.2 per cent. iron oxide and about 0.005 per cent. carbon. Tungsten metal in the form of powder, such as is used in the manufacture of filaments for incandescent lamps, was the other constituent. This material analyzed 99.8 per cent. tungsten and contained no carbon. The metal powders, in the desired proportions, were mixed by tumbling and formed, under pressure of 20 tons per sq. in., into rods 3/8 by 3/8 by 10 in. To form the alloys without contamination, sections of the pressed rods were placed on alundum slabs and heated in an alundum tube wound with a tungsten resistor and packed in heat-insulating material. While the resistor was heated, a stream of hydrogen was continually passed through both the tube and the case containing it. The tungsten winding on the tube, as well as the material heated within the tube, was thus protected from oxidation. Such a furnace will operate constantly for several days at temperatures up to 1500' C. and for shorter periods

Jan 1, 1926

By T. Price, H. A. Holl, A. P. Greenough, A

UdIN, Shaler, and ulff' first used wires for the determination of the surface energy of a solid metal. A gage length was marked by tying knots in the wires, which were then suspended in a cylinder of the same metal, heated in an inert atmosphere for the appropriate time, cooled to room temperature, and finally removed from the furnace so that the lengths of the wires could be measured. With iron wires, difficulties associated with deformation during the phase changeszp3 made it necessary to measure the gage lengths at the tem-

Jan 1, 1964

By Hugh P. Tiemann

The desirability of employing the centigrade scale for the measurement of temperatures is becoming more and more recognized in this country, particularly in view of the fact that this scale is used almost exclusively in technical papers and publications—exclusively in those published in French or German. There are, however, a large number of factories and laboratories which still employ the Fahrenheit scale. It therefore frequently becomes necessary to convert one into the other and the accompanying chart (Fig. I) has been found very convenient for this purpose. The formulas for conversion follow: (1) °F. = 9o /5+ 32 (2) oC = 5 (oF - 32 ) (1) 100° C X 9 900/5 =180 .'. 180 + 32 = 212° F. 5 (2) 5 (212° F - 32) = 5 X 180 =100o C 9 9

Jan 1, 1916

By A. A. Stripling

The Cretaceous limestone wells of the Mara/Maru-caibo Dist. of Venezuela are extremely prolific producers. To maintain production on cessation of natural flow, large scale gas-lift operations were commenced involving high production rates on caring Flow. For the design of these gas-lift installations it was essential to have some knowledge of the pressure gradients involved in casing flow, so that the required injection pressures, optimum gas injection raws, etc., could be forecast. This paper presents a method of calculating these annular pressure gradients. Basically the method makes use of an energy balance equation coupled with an empirical energy loss factor derived from field data. The calculations have been put in a form suitable for "punch card-type" calculating machines. A set of gradient curves for Mara/Maracaibo conditions covering flow rates up to 12,000 B/D, and GOR's of 500 to 2,000 cu fd/bbl is presented. From these curves the flowing BHP can be predicted from surface data and the vertical pow performance under varying conditions of gas injection can be estimated. The method has been applied to La Paz and Mam gas-lift operations for over three years and has given consistently accurate results. INTRODUCTION The Cretaceous limestone fields of the Mara/Maracaibo area in Venezuela are characterized by the presence of widely distributed fissure systems. Under these conditions individual wells frequently have extremely high potentials and such wells are generally flowed on the casing-tubing annulus in order to reduce the pressure loss in vertical flow. To maintain production on cessation of natural flow, an extensive gas-lift system was planned. As a first approach to this gas-lift design problem, an attempt was made to construct a set of empirical flowing gradient curves from the available subsurface pressure data. Such a method has been used successfully for tubing-flow conditions in California by Gilbert'. Unfortunately, the empirical construction of casing-flow gradient curves presents additional difficulties, as pres- sure bombs cannot bc run in the casing-tubing annulus against high rates of flow. Thus, the Full flowing gradients cannot be defined by actual measurement and the best that can be done is to obtain spot pressures at the tubing shoe. Under these conditions a vast accumulation of BHP data is required to construct a set of gradients. To the La Paz and Mara fields the majority of the available flowing pressure measurements fall into a relatively narrow GOR range, in the neighborhood of the solution ratio. While there appeared to be reasonable prospects of constructing gradient curves for this limited range, measurements at higher GOR's, which were of major interest for gas-lift operations, were relatively few and the prospects of constructing empirical curves cor~spondingly remote. As an alternative approach, the possibilities of a mathematical analysis of vertical flow conditions were investigated. May and Laird2fV n 1934 presented an excellent analysis of the vertical-flow conditions in the Anglo-Iranian Oil Co.'s fields. Their analysis was based on an energy-balance equation and calculated the losses due to kinetic energy, friction and slippage separately. By combining these losses with the total calculated available energy, the required depth-pressure traverse could be deduced. On applying the method to La Paz conditions, good results were obtained for tubing flow at high tubing-head pressures. However, for lower wellhead pressures (300 psi and under) the discrepancy between calculated and measured values increased appreciably. It was considered that this was probably due to energy losses caused by slippage or liquid hang-up in a continuous gas phase, for which it was difficult to visualize any analytical approach. In 1952 Poettmann and Carpenter4 presented a method of pressure gradient calculation which, while based on an energy-balance equation similar to that employed by May and Laird, made no attempt to evaluate the various components making up the total energy loss resulting from irreversibilities of flowing fluids. Instead, they proposed a method of analysis which assumed that all significant losses for multiphase flow could be correlated in a form similar to that of the Fanning equation for frictional losses in single-phase flow. They then derived an empirical relationship linking measurable field data with a factor which, when applied to the standard form of the Fanning equation, would enable the energy losses to be determined. The total available

By Monte J. Pool, Rudolph Speiser, George R. St. Pierre, William T. Ebihara

Standard free energies of formation of WO,, W O W20058 and WO3from oxygen and the lower oxide or tungsten have been determined in the tempel-ature range of 700° to 1220°C. A tentative W-O phase diagmm is presented based on the evidence that the oxide phases, "W18O49" and "W20058", are unstable at l~atm total pressure, below 585° and 485°C:, respectively. A HE need for a complete quantitative treatment of the phase equilibria of the W-O system has been establishedby metallurgists during the past few years. In an attempt to improve the endurance of tungsten exposed to oxidizing atmospheres at high temperatures, many research groups have studied the kinetics of tungsten oxidation. The reverse process, the reduction of the tungsten oxides to metal, has also been investigated to some extent. Regardless of the particular interest, metal to oxide or oxide to metal, a knowledge of the phase equilibria of the W-O system is required to properly interpret all of the kinetic observations. It should be possible to state the stable phases of the W-O system at any given values of the chemical potential of oxygen and the temperature.

Jan 1, 1962