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By M. F. Hawkes

Austenite grain size has long been recognized by metallurgists as an important property of steels because of its influence on toughness, hardenability, ma-chinability and creep strength. Much research has been carried out on wrought steels to develop methods for disclosing austenite grain size, and to, provide knowledge of the grain-size characteristics of steels produced and heat-treated in various ways. Much less work in these fields has been done on steel castings; partly because, owing to the variable and complex microstruc-tures of cast steels, it is frequently very difficult to obtain results that are not questionable. The object of this investigation, therefore, was to establish, for a wide variety of carbon and alloy cast steels, suitable methods for disclosing austenite grain size and some knowledge of the grain-size variations to be expected. The steel foundryman is interested in austenite grain size at two different stages in the manufacture of his products; one is just after the steel is cast, and the other is after any reheating operation carried out above the critical temperature range. In both, it must always be kept in mind that the grain size being sought is actually a previous austenite grain size, and that the austenite no longer exists once the steel has cooled to room temperature. The prob-lem of the investigator is always to use evidence obtained from the structure at room temperature to deduce this previous austenite grain size, which was established the last time the steel existed at a temperature above the critical range. Since most steel castings today are at least annealed or normalized, the measurement of austenite grain size established by heat-treatment will he considered first. More than 50 commercially produced cast steels rcpresenting a wide variety of compositions and melting practices were used in the study. For each steel, grain-size determinations were made after each of three widely varying heat-treating schedules namely, one hour at I550'F, one hour at I700°F, and six hours at 1700 F. The list of steels and results obtained on them will be found in the appendix. (See page 530.) A discussion of the knowledge gained on the applicability of various test methods and on grain-size characteristics of cast steels in general follows. MEASUREMENT OF AUSTENITE GRAIN SIZE ESTABLISHED BY HEAT TREATMENT Methods Suitable foR Determining Austenite Grain Size after Heat-treatment at Ordinary Temperatures and Times It was desired, as one of the results of this investigation, to be able to recommend to steel foundries a method, or methods, of disclosing grain size best suited to accurate

Jan 1, 1948

By M. F. Hawkes

Austenite grain size has long been recognized by metallurgists as an important property of steels because of its influence on toughness, hardenability, ma-chinability and creep strength. Much research has been carried out on wrought steels to develop methods for disclosing austenite grain size, and to, provide knowledge of the grain-size characteristics of steels produced and heat-treated in various ways. Much less work in these fields has been done on steel castings; partly because, owing to the variable and complex microstruc-tures of cast steels, it is frequently very difficult to obtain results that are not questionable. The object of this investigation, therefore, was to establish, for a wide variety of carbon and alloy cast steels, suitable methods for disclosing austenite grain size and some knowledge of the grain-size variations to be expected. The steel foundryman is interested in austenite grain size at two different stages in the manufacture of his products; one is just after the steel is cast, and the other is after any reheating operation carried out above the critical temperature range. In both, it must always be kept in mind that the grain size being sought is actually a previous austenite grain size, and that the austenite no longer exists once the steel has cooled to room temperature. The prob-lem of the investigator is always to use evidence obtained from the structure at room temperature to deduce this previous austenite grain size, which was established the last time the steel existed at a temperature above the critical range. Since most steel castings today are at least annealed or normalized, the measurement of austenite grain size established by heat-treatment will he considered first. More than 50 commercially produced cast steels rcpresenting a wide variety of compositions and melting practices were used in the study. For each steel, grain-size determinations were made after each of three widely varying heat-treating schedules namely, one hour at I550'F, one hour at I700°F, and six hours at 1700 F. The list of steels and results obtained on them will be found in the appendix. (See page 530.) A discussion of the knowledge gained on the applicability of various test methods and on grain-size characteristics of cast steels in general follows. MEASUREMENT OF AUSTENITE GRAIN SIZE ESTABLISHED BY HEAT TREATMENT Methods Suitable foR Determining Austenite Grain Size after Heat-treatment at Ordinary Temperatures and Times It was desired, as one of the results of this investigation, to be able to recommend to steel foundries a method, or methods, of disclosing grain size best suited to accurate

Jan 1, 1948

By Mark T. Atwood, Franklin B. Carlson, Louis H. Yardumian

The Oil Shale Corp. (TOSCO) is investigating the application of its oil shale retorting technology to coal processing in its 25-tpd retorting pilot plant. Low temperature char, with a high heating value, plus tar and gas have been produced from high moisture content, low heating value, subbituminous coal. The process, which has been named the TOSCOAL process, uses heated ceramic balls to provide the heat for retorting the coal. One ton of as-mined, subbituminous coal produces approximately 1/2 ton of char, 1/2 barrel of tar, and 1600 standard cubic feet (scf) of gas when the retorting is conducted at 970°F. Properties and yields of the products are presented and compared with Fischer assay yields.

Jan 1, 1975

By Frank M. Randall

The Buick mill is located at the site of the old Buick general store, approximately 4 miles south of Bixby, Missouri on route KK. It is a part of the operations in the area now called the "New Lead Belt". The ore body lies at an elevation of 270 feet above sea level, and is fairly flat lying, becoming slightly deeper toward the south. The mineralization is due to the secondary deposition of galena, sphalerite, chalcopyrite, pyrite, calcite, dolomite and some localized drusy quartz in a country rock of dolomitic limestone. The galena is fairly coarse grained with some large crystaline structure, and some oxidized surfaces. The sphalerite is fine grained- small crystals containing Cd (about 0.7%) and Ag (about 10 oz per ton) in solid solution. The chalcopyrite is fine grained, fine crystals that are sometimes massive in nature. The mine plan is a modified room and pillar system. Broken ore at the mine face will be transported to several different ore passes by rubber tired load-haul-dump units. Ore passes will drop the ore to a rail haulage level some 90 feet below the mining level where bottom dump cars will deliver it to a 42 in. Nordberg gyratory crusher. Two 12 ton capacity skips in balance carry the ore some 1,200 feet to the surface. The hoist is equipped with automatic controls for loading, hoisting and unloading.

Jan 1, 1970

By William N. Poundstone

To forecast the future of coal intelligently, one must first consider the market outlook. Coal can be used for many purposes, but currently about 25% of it goes into metallurgical coke, while 75% serves as fuel. Coal for metallurgical coke should show a modest growth for at least the next decade, primarily because of increased exports, but the important factor in the coal outlook is energy. Today, this country faces a serious shortage of energy, and its requirements are growing at an almost unbelievable rate. Last year the United States consumed 68 quadrillion Btu, or double the energy it consumed in 1950, and, if projections are correct, this figure will grow to 150 quadrillion Btu by 1990. Thus, in one working lifetime, the nation's energy consumption is expected to increase by roughly five times. The future of coal hinges on its degree of participation in meeting this energy need. The Federal Power Commission predicts that coal consumed by electric utilities will increase about 4-576 per yr, reaching 472 million tons by 1980 and 615 million tons by 1990. If this projection proves correct, 1980 consumption will be double that of last year and, even more startling, the utility industry alone will use more coal in 1990 than the entire coal industry produced in 1970. This is a tremendous increase, but in view of the projected energy growth, it is difficult to see how this country's needs can be satisfied with- out a coal contribution of this magnitude. Unless some new source such as solar energy is discovered, it must be assumed that the projected energy will come principally from the present-day sources-oil, gas, nuclear materials and coal.

Jan 1, 1971

By E. W. Dewing

The nature of solid solutions of sodium in non-paphitic carbon at temperatures near 1000°C has been investigated by an electrolytic technique. The activity coefficient is found to vary strongly with the heat-treatment temperature of the carbon, and an analysis of the energy terms involved suggests that this is due to variations in the Fermi level. The diffusion coefficient for sodium is in the range implying that the sodium atoms (or ions) are not bound to specific sites on the carbon, in agreement with lack of evidence for specific compounds in the activity -composition curves. In the light of These results phenomena occurring in aluminum reduction cell linings are dis-cussed. It is concluded that sodium migrates by diffusion through the carbon lallice and not the pores, and that A14C9 is formed within the lining hy The excess of NaF invariably found in used linings is formed by this reaction and by air oxidation: There has recently been much interest in the swelling of carbon which occurs when it is made cathodic in an aluminum electrolysis cell, and there is general agreement that the phenomenon is due to the penetration of sodium atoms, derived from the reaction on the carbon lattice. (NaF and AlF3 are constituents of the fused-salt electrolyte.) The low-temperature lamellar compounds of potassium with graphite are well-known, and one compound between sodium and graphite has been reported.4 There is, however, virtually no information on the basic chemistry of the interaction of sodium with nongraphitic carbon at high temperatures, although Dell3 has made some fundamental studies of rates of penetration. At the time the present work was carried out these were not available. Rapoport and samoilenkol had measured rates of physical expansion in a dilatometer, using the fractional increase in length of a carbon specimen after electrolysis in a cryolite bath for 2 hr as an index of susceptibility to cathodic swelling. Work here with a similar apparatus showed that expansion (of a 1.5-in.-diam cylindrical specimen) ceased in less than 20 hr, and that the final expansion was much more reproducible than the value at some intermediate time. This suggested that an equilibrium was being set up, and that a thermodynamic approach was required. The results obtained are not as accurate as had been hoped, but they are the only ones of their type available and have enabled useful conclusions to be drawn. The experimental work was divided into two parts: an investigation of the activity-concentration diagram for sodium in carbon, and a rough determination of the diffusion rate. For the former, most of the experiments were made with petroleum coke even though this is not a form of carbon used in cell linings. It has the advantages, however, that it is a homogeneous material, that it is low in ash, and that its structure is reasonably well understood. Anthracites and coal cokes gave results of the same type as obtained with petroleum coke, but the reprodu-cibility from specimen to specimen was extremely poor. EXPERIMENTAL 1) The Activity-Composition Diagram for Sodium in Carbon. The petroleum coke was ground, pressed at 40,000 psi into plates 19 by 9 by 2 mm without added binder, and heat-treated. The sodium activities were established by an electrolytic technique. The carbon was made anodic in a cryolite bath with an aluminum cathode, and a controlled potential, E, applied so that the sodium activity at the anode was given by ln Na = 1n asa - EF/RT [21 where as, is the sodium activity generated by Reaction [I]. The relative activity is sufficient for many purposes and is simply given by The value of Na not at present known, but when the thermodynamics of the Na-A1 system have been worked out it can be derived from the equilibrium

Jan 1, 1963

By J. N. Houser

THE industrial relations between the Tennessee Copper Co. and its employees have developed a number of interesting things and have been most, profitable to the employees and to the company. It is noteworthy that considerable has been done without a formal organization of any kind built up through the efforts of the company. From time to time there have been discussions regarding the advisability of a formal organization and the decision has always been in favor of the present method. In the year 1919, the company was dealing with its employees through union committees and, after an understanding was reached, satisfactory results began to be obtained, but as time went on the committees did not function and it came to a question of how to reach the men. For the past two years, about once a month, but at no stated time, there has been a meeting with a committee of employees consisting of 40 or 50 men out of 700. This committee is secured by notify-ing the locals. In addition, the Service Department notifies a number of men not represented in the union, so as to have a large representative committee. The meetings are on company time and the men are rotated, so that in time every employee attends , at least one meeting. All department heads and a number of foremen also are present. The operating plans and policy of the company are set out at the meetings and the market outlook for products is discussed. Explana-tions are also given of anything that has come up since the last meeting which affects the employees, and an effort is made to inform them of what will probably happen in the next month or two. Once a week there is a meeting of department heads with the manager, for discussion of all operations as a whole and such depart-mental details as seem advisable. When the depression started, it was necessary to curtail operations and the reasons were carefully explained; before the men were laid off, the employees as a whole were advised of the coming layoffs through these meetings. They were also advised generally who would be retained and given an opportunity to express their agreement or their. disapproval. In fact, an effort was and is being made to keep the employees advised in advance of matters affecting them and to give them full opportunity to express themselves.

Jan 12, 1922

By Fred W. Gordon

It is my purpose to call attention to the close approximate correctness of certain coefficients and formulas concerning the flow of gases, and their applicability to the practical construction of flues and

Jan 1, 1886

By AIME AIME

PRESIDENT BASSETT'S gavel called the Annual Business Meeting to order shortly after 10 a. m. on Tuesday. On motion of Eugene McAuliffe, reading of the minutes was dispensed with and Mr. Bassett read his annual report of the year's activities as follows : During the year I have visited eighteen of the twenty- seven sections, making an average of GG 2/3 per cent. The invitation to come again has always been extended, but in only one case have I been able to visit the same section twice. Chicago entertained the president twice during 1930. Mrs. Bassett accompanied me on visits to ten sections. Everywhere we have found the most cordial hospitality and a gratifying enthusiasm for the Institute. If anyone had fault to find with the management or felt dissatisfied with what was being done, it was carefully concealed. I am happy to report to you an agreeable, helpful and progressive spirit in each of the sections visited.

Jan 1, 1931

By Richard Pearce

I am deeply sensible of the honor you have conferred on me in electing me your president for this year. It is difficult to understand why I have merited such distinction at your hands, except that I may possibly have helped, in some small way, in the develop ment of metallurgical practice in the West. I fear, however, that I shall fall far shirt of the expectations you may have in regard to my fitness for such a position. The responsibility of preparing an address for this occasion has caused me considerable thought and anxiety. Unlike my predecessors in office, many of whom have dealt in their presidential addresses with subjects covering a wide field, which they could survey with the confidence born of their own extensive knowledge, I have been confined by my experience, during the last twenty-five years, almost wholly to that portion of metallurgical science which bears especially on the treatment of gold and silver. Yet perhaps some sort of general review of the progress of this branch of metallurgy in the West, besides being the contribution I feel myself best qualified to offer, may prove acceptable to many of the members of the Institute. Some few of the gentlemen present will remember the crude condition of metallurgical practice as it was conducted in Colorado only twenty-five years ago. My own personal experience covers a period of eighteen years; and during this comparatively short time I have seen the most astonishing changes in the conduct of metallurgical works. In all probability the marked progress which this country has exhibited could hardly be reached anywhere else, and this result has been achieved mainly by the activity and enterprise so characteristic of the men of the West. The first little successful attempt at smelting made at Black Hawk, in 1867, by Ex-Senator N. P. Hill, representing the Boston and Colorado Smelting Company, proved a great boon to the miners,

Jan 1, 1890

By Glenn R. Zellars, J. P. Morris

The carrier gas method was used to measure the vapor pressure of copper over liquid copper and Fe-Cu alloys. From these results, the activity of copper in the alloys was determined at 146°, 1550°, and 1600°C. Calculations of the activity of iron were made from the results for copper. The activities of copper and iron show strong positive deviations from Raoult's law. KNOWLEDGE of vapor pressures of liquid metals has both practical and theoretical value. Fuming of metal baths is directly related to vapor pressure, and the data should bc particularly important to the technology of vacuum metallurgy. Theoretical applications include determinations of heats of vaporization, heats of solution, and activity coefficients in alloys. Methods for measuring vapor pressures of metals have been reviewed by Speiser and Spretnak.' High-vacuum procedures, such as the Langmuir and Knudsen methods, have been used most widely in recent years. However, these methods are not applicable to vapor pressures greater than lo-' mm Hg and often cannot be used in the temperature range of greatest interest. The purpose of this investigation was to develop a procedure for measuring vapor pressures of pure metals and alloys that would be applicable to pressures greater than lo-' mm Hg. The transportation or carrier gas method has been used. Copper was chosen for the initial work because its vapor pressure has been established fairly well and the reliability of the technique could be ascertained. Applicability to alloys was studied by determining the vapor pressure of copper over liquid Fe-Cu alloys. Experimental Procedure The tests were carried out in a graphite-spiral resistance furnace. The charge consisted of 50 g of metal contajned in a covered sintered-alumina crucible 1/2 in. deep and 13/8 in. ID. Two sintered-alumina tubes led from outside the furnace to within the crucible, passing through close-fitting holes in the crucible cover and radiation shield. The arrangement of the crucible and the two alumina tubes is shown in Fig. 1. The small-bore tube (1/16 in. ID by 5/16 in. OD) served as the inlet for the carrier gas. The tip of this tube touched the metal surface and the flow of gas imparted a rippling motion to the metal. In this manner the gas was brought into close contact with the metal and became saturated with metal vapor. In most of the tests the flow rate of the carrier gas was 560 ml per min, measured at room temperature. Approximately half of this saturated gas was allowed to escape from the crucible through the second alumina tube (3/16 in. ID by 5/16 in. OD) and was discharged to the atmosphere through a

Jan 1, 1957

By K. E. Brown, A. R. Hagedorn

Continuous, two phase flow tests have been conducted during which four liquids of widely differing viscosities were produced by means of air-lift through 1%-in. tubing in a 1,500-ft. experimental well. The purpose of these tests was to determine the effect of liquid viscosity on two-phase flowing pressure gradients. The experimental test well was equipped with two gas-lift valves and four Maihak electronic pressure transmitters as well as instruments to accurately measure the liquid production, air injection rate, temperatures, and surface pressures. The tests were conducted for liquid flow rates ranging from 30 to 1,680 BID at gas-liquid ratios from 0 to 3,-270 scf/bbl. From these data, accurate pressure-depth traverses have been constructed for a wide range of test conditions. As a result of these tests, it is concluded that viscous effects are negligible for liquid viscosities less than 12 cp, but must be taken into account when the liquid viscosity is greater than this value. A correlation based on the method proposed by Poettmann and Carpenter and extended by Fan-cher and Brown has been developed for 1¼-in. tubing, which accounts for the effects of liquid viscosity where these effects are important. INTRODUCTION Numerous attempts have been made to determine the effect of viscosity in two-phase vertical flow. Previous attempts have all utilized laboratory experimeneal models of relatively short length. One of the initial investigators of viscous effects was Uren1 with later work being done by Moore et al.2,3 and more recently by Ros.4 However, the present investigation represents the fist attempt to study the influence of liquid viscosity on the pressure gradients occurring in two-phase vertical flow through a 1¼-in., 1,500 ft vertical tube. The approach of some authors has been to assume that all vertical two-phase flow occurs in a highly turbulent manner with the result that viscous effects are negligible. This has been a logical approach since most practical oil-well flow problems have liquid flow rates and gas-liquid ratios of such magnitudes that both phases will be in turbulent flow. It has also been noted, however, that in cases where this assumption has been made, serious discrepancies occur when the resulting correlation is applied to low production wells or wells producing very viscous crudes. Both conditions suggest that perhaps viscous effects may be the cause of these discrepancies. In the first case, the increased energy losses may be due to increased slippage between the gas and liquid phases as the liquid viscosity increases. This is contrary to what one might expect from Stokes law of friction,' but the same observations were made by ROS4 who attributed this behavior to the velocity distribution in the liquid as affected by the presence of the pipe wall. In the second case, the increased energy losses may be due to increased friction within the liquid itself as a result of the higher viscosities. The problem of determining the li- quid viscosity at which viscous effects becomes significant is a difficult one. Ros4 has indicated that liquid viscosity has no noticeable effect on the pressure gradient so long as it remains less than 6 cstk. Our tests have shown that viscous effects are practically negligible for liquid viscosities less than approximately 12 cp. Actually there is no single viscosity at which these effects become important. These effects are not only a function of the viscosities of the liquids and of the gas but are also a function of the velocities of the two phases. The velocities in turn are a function of the in situ gas-liquid ratio and liquid flow rate. Furthermore, the role of fluid viscosities in either slippage or friction losses will depend on the mechanism of flow of the gas and liquid, i.e., whether the flow is annular. as a mist, or as bubbles of gas through the liquid. These mechanisms are also a function of the in situ gas-liquid ratios and the flow rates. It would thus seem that the best one could hope for is to determine a transition region wherein the viscous effects may become significant for gas-liquid ratios and liquid production rates normally encountered in the field. The viscous effects might then be neglected for liquid viscosities less than those in the transition region but would have to be taken into account when higher viscosities are encountered. There are numerous instances where crude oils of high viscosity must be produced. The purpose of this study has been to evaluate the effects of liquid viscosities on twephase vertical flow by producing four liquids of widely differing viscosities through a 1 % -in. tube by means of air-lift. The approach used in this study was as follows:

Jan 1, 1965

By Leonard Austin

WHAT Colonel Dwight says regarding the treat-ment of oxidized ores1 holds true also of the silver-lead smelting operations in Utah. The ore sought for was such as would, with appropriate fluxes, yield slag, and "lead bullion," as the lead reduced from the ore and carrying its gold and silver, was called. No matte, and probably little or no speiss, was yielded, and hence there was nothing to roast, either of ore or matte. But, by 1880, when I first took hold in smelting, there was quite a production of matte at the works of the Ger-mania Smelting and Refining Co., Utah, because, by that time, ores containing some pyrite and galena were being smelted. This was due, as at the Grant Works, Denver, to the more attractive price paid for the treatment of such ores. The matte, containing about 5 per cent. copper, was accordingly heap-roasted and returned to the blast furnace for the recovery of its contained metals. By this time there had been built a long-bedded, hand-rabbled reverber-atory roaster with a hearth of about 40 by 10 ft. in size, and in this matte and ore, crushed at the sampling mill, was treated. When, in 1892, I took control of this works, called& now the Germania Lead Works, three other roasters had been added, but the prac-tice of heap-roasting continued. This had the merit of needing no equipment, and of doing good work, because the pieces that were imperfectly roasted went back upon the next roast heap. At this time, when some suitable lump ore was obtainable, I roasted in heaps, in a satisfactory way. By 1892, the Bruckner cylinder roaster had been installed, which, compared with the reverberatory roaster, reduced labor. As such a cylinder revolves, a talus of ore is formed within it and at the same time fresh surfaces are exposed to the air, but the trouble was that the air did not reach to the bottom of the cylinder. This we corrected by placing a steam jet at the fire-box end, to project the air down-ward upon this stagnant ore, thus increasing the speed and completeness of roasting without at the same time increasing dust formation. The firing, if skilfully done, gave a somewhat sintered product, but with certain ores a slight access of heat over the normal would cause accretions to form within the cylinder near the fire end. These could be cut off by running back the fire box and barring off the crusts. It was in 1895 that the Bruckner cylinders at the Arkansas Valley plant, Leadville, were giving unsatis-factory service and I was called in to investigate. The steam jet was put in use as at the Germania Lead Works, but we found that, due to the altitude (10,500 ft.), combustion was feebler than at sea level or even at 4000 to 5000 ft. Later it appears, as Colonel Dwight states, that R. D. Rhodes and Mots sought to increase the air supply by admission through perforated tiles, but the trouble was due to the air itself.

Jan 8, 1922

By W. L. Austin

The advance made in recent times in this branch of metallurgy is indicated by the attention the subject is receiving from important American copper-producing companies. Reference to the files of publications devoted to the mining industry discloses that some 20 American companies are actively investigating the amenability of their ore, or other material, to leaching methods, and that plants of varying capacities up to 10,000 tons per day arc under construction or are projected. Several leaching works are in commercial operation. It has been frequently pointed out that no method of leaching is universally applicable, for the reason that each ore differs in some particular from apparently similar ore found elsewhere, and also because local conditions are rarely the same even where the ore closely approximates in character that being worked at some other point. For this reason the older companies are approaching the matter in a conservative manner, experimentally determining for themselves the salient features in each instance. In considering a leaching proposition three factors at once fix the attention: (1) disengaging the metal from mineralized forms in which it is found in nature; (2) recovering the metal in a commercial state after it has been dissolved; (3) the apparatus best adapted to carrying out the several operations. Bringing the Metal into Solution This feature.has been found to present no serious difficulties. Numerous solvents for copper are known, and it has been repeatedly demonstrated on a commercial scale that from 80 to 90 per cent. of the metal contained in an ore can be rapidly brought into solution. It is interesting to note, however, that all of the companies above referred to have selected sulphuric acid as the basis for a lixiviant. Where oxidized ore practically free from precious metals is treated simple leaching with

Jan 1, 1915

By W. H. Smith

IN connection with some recent work on the effect of impurities on the ductility of chromium, it appeared desirable to know the solid solubility of carbon in chromium. A literature survey indicated that this information was not available. Although considerable work has been done on the Cr-C phase diagram,&apos;.&apos; previous investigators have been more concerned with the structure and phase boundaries of the carbide phases than with the terminal solid solution. The phase diagram shown in Fig. 1 is taken from the work of Bloom and Grant&apos; and represents the most recent determination. As indicated by the dashed line, the a solid-solubility limit was not determined. Experimental Procedure Alloys of chromium were prepared from hydrogen-treated and vacuum-degassed electrolytic chromium plus spectrographic grade carbon. The oxygen and nitrogen content of the alloys was <0.002 pct. After melting, analysis of the alloys showed them to contain 0.02, 0.08, 0.15, and 0.55 pct C. Pieces of the alloys were heated in a protective atmosphere to various temperatures and then quenched after holding for a time sufficient to insure equilibrium. Microscopic examination of the as-quenched alloys for the presence of a second phase was used as a measure of the solubility limit. The heats were made in a multiple hearth arc-furnace using a zirconium-gettered static argon atmosphere. A zirconium melt was made before each Cr-C heat. Triple melting was used to insure ingot homogeneity as shown by microscopic examination. The alloys were prepared by adding portions of a 4.5 pct C-Cr master alloy to high purity chromium. The carbon contents listed previously were those obtained by analysis. The nitrogen and oxygen contents after arc melting were both <0.002 pct. Sections 1/8X1/4X1/2 in. were cut from the 100-g ingots and a hole drilled in one end in order to suspend the sample from a molybdenum wire. After the surface was carefully cleaned, a sample of each melt was hung in a mullite tube heated externally by a platinum resistance furnace connected to a vacuum system. The lower portion of the mullite tube was sealed to Pyrex and closed off several inches below the furnace. This was filled with sili-cone oil kept cold by circulating cold water around the outside of the Pyrex. Quenching into the oil bath was achieved by melting a fuse wire supporting the sample. It required about 4 sec for the sample to cool from 1400" to 600°C. This severity of quench was considered satisfactory to freeze-in the high temperature equilibrium. For tests made at temperatures of 900" to 1200°C, heating was done in vacuum; for tests above 1200°C, an argon atmosphere was used. The holding time employed ranged from 12 hr at 900°C to 6 hr at 1400°C. Experiments were performed at temperatures of 900°, 1000°, 1100°, 1200°, 1300°, and 1400°C. Microscopic examination for evidence of a second phase was done at X1500. Experimental Result The microstructures of a 0.08 pct C-Cr alloy as-cast and after quenching from 1300°C are shown in Figs. 2 and 3. A 0.15 pct C-Cr alloy quenched from 1300°C is shown in Fig. 4. The data obtained from the quenching experiments is shown graphically in Fig. 5. If the Van&apos;t Hoff equation is obeyed, a plot on a logarithmic scale of the mol fraction of solute vs the reciprocal of the absolute temperature should give a straight line. For dilute solutions the weight percentage can be substituted for the mol fraction without introducing any appreciable error. The Van&apos;t Hoff equation can then be written as where H is the heat of solution in calories per mol. The slope of the straight line on the log pct C vs 1/T plot gives the value of AH. Assuming that the Van&apos;t Hoff equation is obeyed, which is probably justified for the dilute solution of carbon in chromium, the heavy straight line shown on Fig. 5 represents the best fit of the data. This line was obtained as follows. On Fig. 5 the results of the microscopic examination of all alloys following quenching were plotted and designated as to whether one or two phases were seen. Below 1100°C all alloys showed a second phase on quenching. The heavy vertical lines shown in Fig. 5 therefore represent the possible range of the ter-

Jan 1, 1958

By John M. Lovejoy

NATURAL resources become a source of wealth as they are exploited and made available to the people in usable form. Experience has taught us that Nature does not readily give up her treasures, but the ingenuity of man in the field of techologic progress is required to find and efficiently exploit these resources. History has also demonstrated that with advancing technologic knowledge the. world has become progressively richer in its resources. Those that could not be commercially exploited are now being turned to beneficial use. Through expanding technology and the use of substitutes and synthetics, availability of the world&apos;s sources of natural wealth is today many times that of a hundred or a thousand years ago. And so it is with petroleum. Technology is also the great multiplier of our petroleum resources. Through improvements in the art of finding, drilling, and producing, our ability to meet rapidly increasing demands over the last quarter century has been maintained. On the other hand, had our

Jan 1, 1944

By J. E. Forciea, O. E. Palasvirta, L. G. Hendrickson

AH pilot and commercial plants working with Mesabi Range taconite employ wet magnetic separation. Progress is being made with a dry magnetic process, but this has not yet been applied to taconite except in the laboratory and pilot plants. Flowsheets in all five plants are similar, including multiple stages of grinding, each followed by magnetic separation, which rejects a finished tailing. The flowsheet in Fig. 1 is used in the preliminary and commercial plants of the Erie and Reserve mining companies and in Unit C of Oliver&apos;s Pilotac plant. At Erie the desliming operation is omitted. In the Reserve plants two ball mills are used with each rod mill. Pilotac uses flowsheet 2 in Unit A-B and has also tested flowsheet 3. Principal differences in the three flowsheets are the number of grinding stages and the type of roughing. The terms open-circuit roughing and closed-circuit roughing are best defined by the diagrams. Special Test Data Given in Table I: For the Erie and Reserve commercial plants, Table I reflects routine conditions. Pilotac, the experimental plant, has been run with several flowsheets, including those followed at Erie and Reserve&apos;s commercial operations. Pilotac data for these last two flowsheets are similar to commercial plant results and are not repeated in Table I; statistics are given, however, for special test conditions. using other flowsheets. when the objective was to &apos;to extra-grade concentrate, Variations Among Taconites: Although crude ore tributary to these plants is generally classified as taconite, there are important differences in mineralogy and fineness of dissemination.

Jan 1, 1959

By B. M. Larsen

Attempting to review the fundamental aspects of segregation in steel ingots of all types in a paper of reasonable length, we encounter two difficulties: (I) the fact that a large number of different physical and chemical effects are involved, and (2) rather incomplete and confusing evidence on certain aspects of detail and mechanism in the freezing process in which the segregation effect is involved. The best solution seemed to be to link together most of the underlying factors into a simplified theoretical picture that appears to the writer to explain most of the observed data, in the hope that this will serve as a reasonably good target for discussion and criticism. Segregation effects, especially in steel ingots or castings, are often divided into " microscopic" and "macroscopic," depending on whether the variations in concentration of solutes or dissolved elements in the iron occur as: (I) a periodic variation over the small distances between the nuclei and the surfaces of the primary grains, or (2) as a larger scale effect involving concentration gradients over distances of the order of several inches, more or less. The reason for this somewhat artificial division is, of course, that it is only the macroscopic scale effect that has much practical importance. About the only effect of practical importance that results from microscopic segregation is the banded structure often left in rolled sections, and even this is relatively harmless in most cases. However, the causes of microscopic segregation also untlerly the larger scale effect, so we must first consider matters such as the formation and growth of crystal nuclei, selective freezing and diffusion, and others that are fundamental to all sepregation effects. Undercooling and Nuclei Formation It is probable that although the degree of undercooling is small in iron, as in metals in general, a certain amount of it takes place, and also that the number of crystal nuclei increases very rapidly with increased undercooling below the liquidus temperature. In practical terms this means that the nuclei number illcreases very rapidly with increased cooling or freezing rate, thus being dependent on the rate of heat flow out from the zone of crystallization. Temperature Gradients and Heat Dissipation during Freezing Each pound of steel evolves about 100 B.t.u. when freezing. In addition to this, the temperature gradient in the solidified portion (required to dissipate the heat as freezing progresses into the axis) necessitates a loss of heat required to cool the solid metal below its freezing range, which is equivalent to an amount of not so much less in magnitude. In a 5-ton ingot, the total would include about one million B.t.u. for freezing alone and about 0.4 to 0.5 million B.t.u. for the gradient, up to the end of the freezing period. Thus the rate of freezing depends primarily on the rate of heat dissipation. In the ordinary ingot shapes, the axial rate of growth of the solid

Jan 1, 1945

By O. P. Dolph

SPANIARDS were probably the first to mine the rich surface ore in the veins cutting the rhyolite capping that outcrops on the hills of La Mazata, oil the Allyones side of the Magdalena valley in Jalisco, Mexico, although the name comes from a word of Indian origin meaning "deer". The camp is about 12 km. west of Magdalena, a town on the Southern Pacific Railroad, and about 17 km. north of Etzatlán, on the Mexican National Railroad, at an elevation of 4500 ft. The climate is subtropical with no extremes of heat or cold, the rainy season beginning in June and ending in October.

Jan 1, 1938

By O. Nomland

The work of The Bahrein Petroleum Company, Ltd., on Bahrein Island consisted mainly in continuing development work and prospecting previously reported. The exploratory work, however, has been greatly minimized and new wells are being drilled, chiefly for the development of larger production; 20 wells had been completed by the end of 1935 and 8 were being drilled. In addition to what has been referred to as the &apos;&apos;main pay," two deeper productive horizons have been discovered, which apparently will greatly increase the potential of the field although the areal extent of this lower production has not yet been determined. The proven acreage of the "main pay" is more than 12,500 acres. Current production (principally from the upper horizons) is about 13,400 bbl. a day. The construction of a 10,000-bb1.-a-day refinery has begun and is to be in operation by July, 1936. It is expected that the capacity will be considerably increased at a later date. The construction of office buildings and a permanent camp has been almost completed. In Saudi Arabia the California Arabian Standard Oil Co., a wholly owned subsidiary of the Standard Oil Company of California, spudded in a well in April, 1935, near the village of Dammam, on the Persian Gulf coast of A1 Hasa. Although several important showings of high-gravity oil and considerable gas have been found, the well is not yet considcred a commercial producer. Dammam well No. 2 has been started farther south on the same structure. A great deal of reconnaissance and some detailed geological work has been completed during the last three field seasons. In order to overcome difficulties of transportation over the desert sand, unusual methods have been used. The parlies penctrating the interior by the use of automobiles and trucks have been supplied with gasoline and provisions by caravans of camels. Mail and supp1ies of lighter weight urgently needed have been carried to the field men by an airplane operated by the geological division of the company. Each party has been supplied with a radio receiving and transmitting set to keep in contact with the airplane as well as with geological headquarters at Jubail on the coast of A1 Hasa.

Jan 1, 1936