Search Documents

By E. O. Kirkendall

The investigation reported herein was undertaken to obtain data to supplement those presented in an earlier paper,l particularly for longer times at a higher temperature. This information may further develop our knowledge of the mechanism of diffusion in substitutional solid solutions. Diffusion of solute atoms interstitially dissolved is not difficult to visualize: it can take place without much disturbance of the solvent atoms. The mechanism of diffusion of solute atoms substitutionally dissolved is not so easily understood. Many theories have been advanced. Rosen-hain,2,3 Frenkel,4 Smekal,5 Langmuir,3,6 Steigman, Shockley and Nix,' and Johnson8 all proposed theories to explain diffusion. Langmuir's proposed mechanism consisted of a simple cyclic interchange of atoms involving an interchange in lattice positions of four or more atoms. This mechanism, accepted by the author at the time of his previous publication,1 and apparently quite generally accepted, required a net exchange in positions of both solute and solvent atoms in equal numbers. In other words, the rate of diffusion of the solvent and solute atoms would be the same. That this cyclic interchange in lattice positions of solute and solvent atoms in equal numbers is the only true mechanism of diffusion is denied by the evidence presented in this paper. Experimental Procedure This modification of similar procedure1 will be outlined briefly. The method consisted of the following steps: I. A pure Muntz metal (60.6 per cent Cu, 0.1 per cent total impurities) that was almost all beta brass at 780°C. was chosen. 2. The brass was turned between centers in a lathe to a diameter of 0.5965 inches. 3. After the brass was cleaned, it was electroplated with pure copper to a diameter of about one inch. 4. The sample was heated slowly to 400°C. under reduced pressure and held at that temperature for 4 hr. to remove occluded gases. It was then cooled to room temperature. 5. The sample was heated to 780°C. ± 3°C. and held at that temperature for different lengths of time; then quenched. Samples were cut off each time after quenching. Metallographic samples 1/4 in. thick were removed at I hr., 6 hr., 24 hr., 96 hr. and 701 hr. After 96 and 701 hr. samples of about I in. were removed for X-ray analysis. 6. The metallographic samples were polished on the cross section and photomicrographs were taken. 7. The I-in. samples were polished and etched on both ends. With the aid of a microscope each was carefully mounted in a four-jaw chuck in a lathe, so that they could be accurately bored for an arbor. 8. Turnings were taken for each X-ray sample. After each set of turnings, the sample was heated in an oil bath for about 1/2 hr. at 300°C. It was then etched in 25

Jan 1, 1942

By E. O. Kirkendall

The investigation reported herein was undertaken to obtain data to supplement those presented in an earlier paper,l particularly for longer times at a higher temperature. This information may further develop our knowledge of the mechanism of diffusion in substitutional solid solutions. Diffusion of solute atoms interstitially dissolved is not difficult to visualize: it can take place without much disturbance of the solvent atoms. The mechanism of diffusion of solute atoms substitutionally dissolved is not so easily understood. Many theories have been advanced. Rosen-hain,2,3 Frenkel,4 Smekal,5 Langmuir,3,6 Steigman, Shockley and Nix,' and Johnson8 all proposed theories to explain diffusion. Langmuir's proposed mechanism consisted of a simple cyclic interchange of atoms involving an interchange in lattice positions of four or more atoms. This mechanism, accepted by the author at the time of his previous publication,1 and apparently quite generally accepted, required a net exchange in positions of both solute and solvent atoms in equal numbers. In other words, the rate of diffusion of the solvent and solute atoms would be the same. That this cyclic interchange in lattice positions of solute and solvent atoms in equal numbers is the only true mechanism of diffusion is denied by the evidence presented in this paper. Experimental Procedure This modification of similar procedure1 will be outlined briefly. The method consisted of the following steps: I. A pure Muntz metal (60.6 per cent Cu, 0.1 per cent total impurities) that was almost all beta brass at 780°C. was chosen. 2. The brass was turned between centers in a lathe to a diameter of 0.5965 inches. 3. After the brass was cleaned, it was electroplated with pure copper to a diameter of about one inch. 4. The sample was heated slowly to 400°C. under reduced pressure and held at that temperature for 4 hr. to remove occluded gases. It was then cooled to room temperature. 5. The sample was heated to 780°C. ± 3°C. and held at that temperature for different lengths of time; then quenched. Samples were cut off each time after quenching. Metallographic samples 1/4 in. thick were removed at I hr., 6 hr., 24 hr., 96 hr. and 701 hr. After 96 and 701 hr. samples of about I in. were removed for X-ray analysis. 6. The metallographic samples were polished on the cross section and photomicrographs were taken. 7. The I-in. samples were polished and etched on both ends. With the aid of a microscope each was carefully mounted in a four-jaw chuck in a lathe, so that they could be accurately bored for an arbor. 8. Turnings were taken for each X-ray sample. After each set of turnings, the sample was heated in an oil bath for about 1/2 hr. at 300°C. It was then etched in 25

Jan 1, 1942

By T. Saburi, C. M. Wayman

The massive and martensitic transformations in ß Cu-Ga alloys were studied by optical microscopy and by transmission electron microscopy and diffraction. These types of transformation are distinct and do not merge into one another. An internal fine structure due to stacking faults was found in both the massive phase (m) and the martensite, but the origin of the faults is believed to be different in each case. The faults in the martensite are due to the lattice invariant or "second" shear of the phenom-enological theory, while those in the are probably growth faults and deformation faults arising from the transformation volume change. Evidence is presented for ordering in the ß phase prior to transformation into martensite, and the crystal structures of and ß' and ßi martensites are discussed. THE results from some previous investigations1,2 have led to the suggestion that martensitic and massive transformations have certain common characteristics. It presently seems established that massive transformations like martensitic transformations are essentially diffusionless,1,2 but unlike martensitic transformations, when a new phase forms massively there is no shape change or surface relief.= If the massive-type transformation is crystallographically similar to martensitic transformations, one would expect a fine structure as a result of the lattice invariant shear4 which is a part of the transformation mechanism. The existence of such a fine structure (i.e., slip, twinning, or faulting), if any, can be verified by transmission electron microscopy, and thus the present investigation was undertaken to compare the internal structure of massively and martensitically formed phases in Cu-Ga alloys which were derived from a parent of the same composition. The transformation characteristics of ß Cu-Ga alloys were also studied. The bcc ß phase in the Cu-Ga system, Fig. 1, is stable above 616oc.' Depending upon the cooling rate, ß Cu-Ga alloys can undergo three different types of phase transformations. The ß phase of eutectoid composition (23.7 at. pct Ga) decomposes into the ? phase (hcp) and the phase (complex cubic) by means of a eutectoid reaction. When the cooling rate is increased so that the decomposition of 0 into [ and ? is suppressed, the ß phase transforms into a nonequilibrium hcp phase, herein denoted ?m by a process of very rapid growth called a "massive" transformation. At even faster quenching rates the massive transformation can be suppressed and the ß transforms martensitically. Massive transformations, apparently similar to those in the Cu-Ga system, have also been studied in the Cu-Zn2,6-8 and Ag-Cd systems.9 Definitive characteristics if the Massive Transformations in 0 Cu-Ga Alloys1 1) The most remarkable feature of the massive transformation in Cu-Ga is that there is no bulk composition change on transformation. According to Massalski,1 the resulting [, phase is a supersaturated extension of the equilibrium [ phase. The lattice parameters continue the trend exhibited

Jan 1, 1965

By E. T. Turkdogan, P. Grieveson, J. F. Beisler

Experimental results are given for the rate of reduction of silica from silicate melts by paphite-saturated iron in the presence of carbon monoxide. It is shown that, when gas bubbles are present at the slag-metal interface, the interfacial chemical reaction is the rate-controlling process in the transfer of silicon from slag to metal. From the silicon-concentration profiles in the metal sample, the diffusivity of silicon in paphite-saturated iron is found to be (5.4 * 0.4) x 10 sq cm per sec at 1600°C. Some consideration is given to the transport of oxygen from the slug-metal interface to the walls of the gvaphite metal container as becoming the rate-controlling process in the absence of gas bubbles at the slag-metal interface. ATTEMPTS were made by Fulton and chipman1 to investigate the kinetics of reduction of silica from calcium alumino-silicate melts by graphite-saturated iron in an atmosphere of carbon monoxide. In these experiments with 400 to 500 g of metal and slag, both phases were stirred in such a manner that the interface was essentially undisturbed. Initially, the graphite-saturated iron contained about 15 pct Si and, after about 8 or 10 hr of reaction time at 1600°C, the silicon content of the metal in- creased by about 0.2 pct. In a written discussion on this paper of Fulton and Chipman, schuhmann2 pointed out the possibility that this observed slowness of the reduction of silica could be due to the transport of oxygen across the liquid metal boundary layer at the slag-metal interface. Although this explanation of Schuhmann is quite feasible for the experimental data of Fulton and Chipman on silica reduction, such a reasoning should not be extended to other rate data on slag-metal reactions unless sufficient evidence is available satisfying the boundary conditions for such a transport process. The hydrodynamics of stirred liquids are very complex and even for a simple method of stirring there is no exact mathematical solution which will predict the mass transfer coefficient accurately. The best available solution of this problem is that given by Lewis' and later modified by mayers~ for a two-liquid system where liquids are stirred by counter-rotating stirrer blades without disturbing the interface. In such a system the mass transfer coefficient is estimated from an empirical relationship using the data on viscosity and density of the two liquids, rate of revolution, the length of stirrer blades, and the diffusivity of the element which is transferred from one phase to the other. It was found in these investigations' that the estimated and observed mass transfer coefficients, in systems containing two immiscible aqueous solutions, agreed within *40 pct. Although this is not considered to be an unreasonable error for the study of industrial processes, uncertainties of this magnitude cannot be tolerated in any theoretical study of reaction kinetics. In view of the complexity of the

Jan 1, 1963

THE fall meeting of the Petroleum Division at Fort Worth, Texas, Oct. 19 and 20, attracted even a larger number of members and guests than had been expected. Over three hundred registered the first day though the attendance and interest in the program was so keen that it was necessary to begin technical sessions without. waiting for registration. Members were present from as far away as Venezuela and while the larger attendance was from the Mid-Continent and Texas fields, California and the eastern states were represented by influential delegations. One pleasing feature of the meeting was the presence of a number of the older executives of the oil industry who evi-dently have come to realize the importance of the work the Division is doing in advancing technology. The meeting was held under the auspices of the Production Engineering section of the Division. E. 0. Bennett, chief production engineer for the Marland Oil Co. of Texas, and chairman of the Fort Worth Sec-tion. of the A.I.M.E., served as general chairman. J. B. Umpleby, president of the Petroleum Reclamation Co. and vice-chairman of the. Division was in charge of. the program with a special committee in charge of the technical sessions, of which A. C. Rubel of the Union Oil Co. was chairman. The sessions were held in the ball room of the Texas Hotel, which also served as general headquarters. The Wednesday morning session was devoted to the air-gas lift, John M. Lovejoy, chairman of the Division, presiding. The first paper, on the "Principles Under-lying the Air-Gas Lift." by J. 0. Lewis, was presented by R. R. Brandenthaler and discussed by Messrs. Love-joy and Millikan. Mr. Brandenthaler's own paper on the "Effect of Gas Lift on Physical Properties of Oil" followed and was discussed by Messrs. Umpleby, Walker, Mills, Bennett, Williams and Van der Gracht, the dis-cussion turning mainly on what is known and what unknown regarding oxidation of oil under various con-ditions. The third paper of the morning, "Handling Recirculated Gas," by R. D. Gibbs, was presented by Mr. Taylor. The discussion that followed was general and brought out a large amount of data on the costs and results of compression versus, absorption in total gasoline recovery from gas. The next group of papers dealt with "Mechanical Installations of Air-Gas Lift," the first by E. V. Foran on the Texas district outside the Gulf Coast, the second by L. L. Brundred on the Gulf Coast, the third on Kansas and Oklahoma other than Seminole by R. W. Bond, the fourth on Seminole by C. R. Swartz, and the fifth relating to California by H. C. Miller. Some of these were read by title in order to give more time for discussion which was active and participated in by. Mills, Griswold and others.

Jan 11, 1927

By Earl Ingerson

BORE surfaces of used guns commonly show a pattern of cracks in various degrees of development. It has been suggested that these cracks may aid erosion by providing channelways for the gases, eventually leading to the tearing out of blocks of metal. Under the general studies of gun erosion conducted at the Geophysical Laboratory it appeared desirable to consider this factor, and to determine the resistance to surface cracking offered by gun steel and by various other materials that might be used in the bores of guns. METHOD AND APPARATUS In order to make such a determination it is necessary to have (I) an arrangement in which the surface to be studied can be subjected to conditions similar to those in a gun with respect to temperature, pressure (developed by explosion gases), composition of the gases and length of time the surface is exposed to the gases; and (2) a specimen that can be examined readily after any number of shots, and then fired again, if necessary. The first of these conditions can be met by using an explosion vessel designed by H. S. Roberts of the Geophysical Laboratory. Fig I shows a cross section of the apparatus. The "gun" G from which the charge is fired is made from the receiver of a caliber 0.30 army rifle, M1903, and the charges are prepared in caliber 0.30 cartridge cases. The test specimen S is held in place by a cone-shaped plug P and by a steel ,bridge B which is bolted to the outside of the explosion vessel on either side of the section shown. The plug, in turn, is held in place by a screw collar C. Maximum pressure is controlled by a brass rupture disk R. Part of the explosion gases flow past the two flat areas on S. st the two flat areas on S. Temperature and composition of gases, and the time before the rupture disk breaks, can be controlled by amount and kind of powder used, and pressure can be controlled by using rupture disks of different thickness. While the explosion vessel used was not designed so that temperature and pressure could be measured, in other vessels of closely similar size and shape containing proportionate charges of the same kind of powder as that used for standard testing procedure, values of 2700°K and 5000 psi were obtained. Since the orifices past the flat areas on the plug are small compared to the rupture disk hole (1:16), most of the gas goes out through the rupture disk when it breaks. The amount that goes by the plug depends on (I) the pressure attained before the rupture disk breaks and (2) the time it takes for this pressure to be built UP. The second condition (examination at will after any firing) is met by using for specimens short rods that have flat areas ground on opposite sides. These flat

Jan 1, 1947

By Leo Horvitz

PETROLEUM and natural gas are composed principally of the saturated hydrocarbons ranging from methane, the lightest, to nonvolatile liquids and solids containing approximately thirty-five carbon atoms. A technique for locating buried accumulations of these hydrocarbons before drilling obviously requires that some of the hydrocarbons leave the deposit and migrate toward the surface of the earth where they may be detected in their original form. Earliest attempts to link near surface hydrocarbons to petroleum at depth were apparently made by Laubmeyer1 in Germany and by Sokolov2 in Russia. These investigators collected samples of soil air from boreholes one to two meters deep and analyzed them for traces of hydrocarbons. They found that soil air over producing areas is richer in these constituents than is soil air over barren areas.

Jan 12, 1954

By T. H. Weldon, L. V. Whiton, R. R. McNaughton, J. H. Hargrave

Oxygen enriched air is being used quite extensively in the metallurgical plants of The Consolidated Mining and Smelting Co. of Canada, Limited, at Trail, B.C. The oxygen used for this purpose is a by-product from the Company's chemical plants located in the area. Most of the ore treated in the Trail metallurgical plants comes from Com-inco's Sullivan Mine at Kimberley, B.C. At Kimberley the ore is milled to produce lead and zinc concentrates which are shipped to Trail for further treatment to metal. One section of this paper deals with the use of oxygen enriched air in the suspension roasting of the zinc concentrates. In this process the concentrate is calcined for leaching preparatory to electrolytic recovery of the zinc. A second section of the paper describes the use of oxygen enriched air in operations at the lead smelter. There oxygen enriched air is used in the blast to the lead blast furnaces and in the slag fuming furnace which recovers the lead and zinc contained in lead blast furnace slag. The final section of the paper outlines the precautions necessary for the safe use of oxygen enriched air in any plant operation. The Use of Oxygen Enriched Air in the Suspension Zinc Roasters The suspension roasting of zinc concentrate developed at Trail, B.C., has been described in AIME Vol. 121, "The Electrolytic Zinc Plant of The Consolidated Mining and Smelting Company of Canada, Limited" by B. A. Stimmel, W. 11. Hannay and K. D. McBean. Since the publication of that paper, the use of oxygen enriched air in suspension roasting has been introduced as regular practice with marked advantage. The relative importance of a specific advantage may vary with changing conditions, but, in general, it may be stated that improved operation has been achieved at increased capacities. Suspension roasting is carried out at Trail in converted standard 25 ft diam Wedge roasters. The 2nd, 3rd, 4th and 5th roasting hearths have been removed and the drying hearth covered over. Drying of the concentrate is done on the drying hearth and the 1st roasting hearth. The dried concentrate, after any lump's have been broken up in a ball mill, is fed to a single burner located in the upper part of the combustion chamber. Oxygen is introduced at the burner fan along with the gases from drying, returned combustion gases from the waste heat boiler outlet and the required amount of new air. Up to 60 pct of the concentrate settles out on the 6th roasting hearth, the rest passilig out of the roaster. The product collected in the waste heat boiler is finished calcine, but the dust collected in the cyclones after the boilers is returned to the base of the combustion chamber where the sulphate is decomposed. Gases from the c'yclones go to a Cottrell precipitator. The discharges from the 7th roasting hearth and the waste heat boiler are combined with the Cottrell dust to give the finished calcine. Following small scale tests started in 1933, oxygen enriched air has been used continuously in the suspension roasting of zinc concentrate in Trail, beginning in 1937. A significant factor in promoting its use in this operation was the availability of by-product oxygen from the Company's near-by Chemical and Fertilizer Division. To-day it is standard practice at Trail to use oxygen enriched air for zinc concentrate roasting. The most important requirement in roasting a zinc concentrate for an electrolytic plant is that the zinc in the calcine should have maximum solubility. It is also desirable at Trail that the gas produced for the manufacture of suhhuric acid should have a ~naximum concentration of SO2 and that a substantial recovery of waste heat from the gas be achieved. High solubility of zinc requires that the sulphide sulphur and zinc ferrite in the calcine be kept low. These are both functions of temperature and time, with formation of zinc ferrite also dependent on contact between the iron and zinc particles. One of the inherent advantages of suspension roasting is that minimum time and contact are achieved. The limit on temperature is imposed by the fusion point of the concentrate and not by the need to control zinc ferrite formation. Operating temperatures are normally maintained within the limits of 1725" and 1850°F. A relatively low zinc sulphate in the calcine is required at Trail, and this results from discharging the calcine from the high sulphur dioxide atmosphere at a temperature above 1600°F.

Jan 1, 1950

By Carl R. Christiansen

Since the first pay hole in Missouri's "New Lead Belt" was drilled in 1955, this district has become one of the world's leading sources of lead. The belt extends from north of Viburnum in a southerly direction to near Eminence, a distance of about 35 miles. The St. Joseph Lead Company was the discoverer and first to develop new mines in the Viburnum area. Since the discovery of the New Lead Belt, many companies have engaged in exploration programs and several major companies have become active in development of new mines. These include Cominco American, Inc., which operates a joint venture with Dresser Industries; Ozark Lead Company, a subsidiary of Kennecott Copper Company; and Missouri Lead Operating Company, a joint venture of Arnax and Homestake. St. Joseph Lead Company, with over 100 years of experience in the Old Lead Belt, has served as a leader in development of equipment and mining techniques, making its properties some of the most efficient mining operations in the world. The new producers give the district the benefit of fresh viewpoints, as their engineers are mostly from outside of Missouri and their previous experience has been considerably different from conventional lead belt practices. While all operations are similar in that they are room-and-pillar, the diverse experience of the operators has produced a group of mines that employ a variety of equipment and mining techniques to give increased efficiency

Jan 1, 1970

By Franklin Allison

THE influence of cobalt and nickel on the properties of steel might be readily expected to be very similar. The two elements occupy close and somewhat unusual positions in the periodic table, their chemical behavior and compounds are so completely analogous and their various physical properties, including the ferro-magnetic characteristic, show such a remarkable correspondence, that there is no doubt of a strong resemblance existing between these two metals. However, the variety of, properties that are obtained from steel is due, largely to the fact that the element iron possesses allotropic forms. Alloying elements that affect these allotropic forms, or alter the nature of the allotropic changes, exert a profound influence on the resulting steel. In the case of nickel and cobalt, although these elements are very similar chemically and physically, it is found that they differ distinctly in their individual effects on the critical points of iron. Both nickel and cobalt form a series of homogeneous solid solutions with iron at temperatures above 1800° F. The difference in their behavior does not occur until changes begin to take place in the solid state below this temperature. An inspection of the respective thermal equilibrium diagrams at the lower temperatures makes the opposite effects of nickel and cobalt clearly evident.

Jan 3, 1927

By A. Patton, F. N. Speller

The use of roll scale in the Bessemer process dates back, to the best of our knowledge, at least 20 years. It was first used by the Ohio Steel Go., Youngstown, Ohio (now the Ohio Works of the Carnegie Steel Co.) under the direction of Sam McDonald, Superintendent of the Bessemer Department at these works. Two 10-ton vessels and one blowing engine capable of blowing one heat at a time were employed. The object of using the scale was to shorten the length of the blow, or in other words, to increase the production with the same equipment. Various means were tried out for introducing the roll scale into the bath of molten iron: It was shoveled into the vessel before the heat was charged, so that the metal would flow over the scale; it was shoveled into the bath after the vessel was turned up; it was dumped into the empty iron ladle by the wheelbarrow-load, and at times was dumped on top of the molten metal in the iron ladle. But the practice of introducing the scale into the iron ladle had to be abandoned on account of danger from explosions and of skulling the ladles. It was soon learned that the proper place to charge the scale was in the empty vessel, so that when the molten iron was poured into the vessel it flowed over the scale, causing a considerabIe reaction to take place before the heat was turned up. Eventually, cylindrical chutes similar to those now in use were installed. Into these chutes the scale is dumped and carried into the empty vessel. Before this convenient means of introducing the scale was adopted, the Ohio Works had satisfactorily demonstrated that roll scale would increase production, by blowing 107 heats in one 12-hr. turn (1,087 tons) with one blowing engine, blowing one heat at a time; whereas, prior to the use of scale, the best practice at these works was about 80 heats under the same conditions. In using roll scale and other oxides of iron to facilitate and control the refining of pig iron in the converter, the Bessemer plant has borrowed one of the most active agencies used in the open-hearth process with, as would be expected, much the same results. The effect of such additions to the Bessemer charge may be discussed as to the influence of this practice on quality, production and cost.

Jan 1, 1917

By P. L. Weston, S. E. Khalafalla

A systematic study was made by the Bureau of Mines on the effect of so me hypothesized accelerators for the process of wustite reduction in carbon monoxide. When small concentrations of promoter materials in the order of 0.69 at. pct were added to the reducible charge, the rate of reduction to iron was increased. Promotion phenomenon prediction was made in light of a suyface reduction mechanism with the aid of Vol'kenshtein's effect regarding the propagation of crystal lattice disturbances by small amounts of relatively larger interstitial ions. The acceleration produced by a typical promotor, such as potassiunl, increases with protnoter concentration up to a maximum, beyond which the reduction rate decreases. Concentration for maximum promotion depends on the nature and physicochemical properties of the promoter. The extent of reduction rate enhancement is found to be directly proportional to the atomic volume and electronic charge of the additive. DESPITE the enormous volume of literature on iron oxide reduction, very little is reported concerning additive or impurity effects on this important metallurgical process. The beneficial effect bf calcium compound additions on the reducibility of iron oxide sinters has been reported by Tigerschiold,1 vor dem Esche,2 and Edstrom. Doi and Kasai~ found that the addition of lime or limestone to iron ores helps to break up any unreducible compounds, such as fayalite or ilmen-ite. and thus free the combined iron for reduction. Schenck et al. 5 suggested that the increased reduction rate obtained when adding lime could be accounted for by the instability of wustite in the presence of lime. Acid-base slagging reactions resulted in wustite disproportionation according to The dicalcium ferrite formed will yield iron and calcium oxide during reduction. Regenerated calcium oxide dissociates more wustite. This mechanism has been used by Seths and white7 to explain their experimental results. Recently, Strangway and ROSS' attributed the calcium carbonate acceleration of iron oxide agglomerate reduction to increased porosity, both initial as well as that developed during reduction. Aside from calcium carbonate, or oxide, no other promoter was noted in the literature, except for a brief mention by Barrett and woodg on the effect of sodium carbonate and aluminate as activators for the hydrogen reduction of magnetite at 600°C. The present investigation systematically studied a host of other promoters, including calcium and sodium, in an attempt to elucidate the mechanism by which promotion takes place and to fit the results into a simple chemical model. To attain this goal, the effect of promoter physical properties, such as atomic volume, electronic charge, and concentration are related to wustite reduction kinetics in this paper. Wustite reduction to iron, rather than the overall hematite reduction, was chosen since this reaction is known to be the slowest, and hence the rate-deter mining step for the overall iron oxide reduction process. EXPERIMENTAL PROCEDURE Raw Materials and Their Preparation. The pure or impregnated wustite pellets were prepared from minus 400-mesh chemically pure hematite powders. A known weight of hematite was thoroughly and uniformly mixed with a calculated weight of the additive. The mixed paste containing 35 wt pct water was gradually heated from 400" to 1200° C and fired at 1200°C for approximately 4 hr in an air atmosphere. After cooling, the sinter was pulverized to minus 100 mesh and pelletized into minus 4- plus 5-mesh spheres. Pellets were fired, similarly to the paste mix, air-cooled, sized, and stored. An appropriate weight of the charge (20 g) was placed in a zirconia reduction tube maintaining a uniform oxide bed height of 1 cm and a cross section of 7.1 sq cm for all of the test runs. The samples were supported in the vertical reaction tube by a bed of fragmented insulating firebrick plus 3- to 6-mesh alumina beads. The hematite was then transformed to wustite by reduction with a 30 pct CO2-70 pct CO gas mixture at 1000°C in a globar furnace. Complete conversion to wustite was ascertained by a continuous infrared gas analyzer recording the CO-CO2 content of the effluent gas until no carbon monoxide was absorbed from the inlet gas, and inlet-outlet gas analysis remained constant for 30 min. The wustite sample was then reduced with 100 pct CO at 100WC. From the recorded data, an initial rate of reduction was determined by the initial slope of the graph percent reduction vs time. In order to estimate the accuracy of the data, five separate determinations of the reduction curve of pure wustite, under otherwise identical conditions, were performed. The maximum deviation from the average reduction at 14 min amounted to 2 2 pct reduction. This deviation corresponds to 3.8 pct variation based on the percent reduction of the sample. Aiiy impurity effect below the limits of this maximum deviation was considered a spurious result. If the effect exceeded + 4 pct, then it was considered as a positive one. Considerable care was exercised in determining the initial rate from the slope of the initial segments of the curve. Each reduction curve was examined separately on large graph paper and the best tangent to the curve at zero time was drawn. The slope of this tangent was taken as a measure of the initial fractional reduction per minute. Although the time required to reach 50 pct reduction may be of special practical significance, initial rate measurements are invaluable in fundamental studies. These rates provide a measure of the process kinetics on the initial

Jan 1, 1968

Jan 1, 1955

By James E. Lawver, James L. Wright

This paper discusses the design and calibration of a Faraday pail for measuring electric charge. The paper also shows that at least for two minerals, quartz and calcite, the phenomenon that Johnson termed "reversibility" can be explained in terms of the contact electrification between the minerals and the metal rotor of an electrostatic machine. Each year the free world produces about 13 million tons of mineral concentrates by electrical separation. However, despite the rather general acceptance of electrical concentration as an industrial process, research in this area has lagged far behind the efforts devoted to competitive processes such as froth flotation. The purpose of this paper is to describe the design and calibration of a Faraday ice pail for measuring charge density on mineral grains and to show some of its applications in the area of electrostatic and electrodynamic research. THE DESIGN AND CALIBRATION OF FARADAY PAILS FOR ABSOLUTE CHARGE MEASUREMENT The electric charge on mineral grains at a given time during an electrical concentration process is de- pendent on many factors and cannot, in general, be accurately calculated a priori. It is thus important to devise a method of measuring absolute charge. One method of measuring electric charge is to note the potential rise of an electrometer when charged particles drop into a Faraday pail. Two types of Faraday pail have been constructed and calibrated. The first type, Faraday Pail I (Fig. 1), is a vertical pail originally designed to measure the charge due to contact electrification between mineral grains and a metal rotor or due to conductive induction when mineral grains are passed over a rotating cylinder in the presence of an electric field. The second type, labeled Faraday Pail II (Fig. 2), is a horizontal pail designed to determine the charge distribution of mineral grains after they pass through the separating zone of the electrical concentrator shown in Fig. 4. The main advantage of the horizontal pail is its low head-room requirement and the long opening which enables the experimenter to sample the entire width of the stream of minerals being separated. The Faraday pails were calibrated in the following manner: A calibration head was constructed in the form of a hollow brass sphere that could be held in an insulated metal cylinder by vacuum (Fig. 1). The capacitance of the sphere was calculated by measuring the capacitance of the sphere and cylinder combined and that of the cylinder alone and subtracting the latter measurement from the former. The sphere was then charged to a known potential (V) and allowed to drop into the Faraday pail which was attached to a Keithley Model 610A electrometer. This instrument has an accuracy of 2% full scale and has

Jan 1, 1969

By W. C. Leslie

W. C. Leslie (Edgar C. Bain Laboratory for Funda mental Research)—This investigation, with its com bination of high-purity metal, calorimetry, and metallography, will serve as a model for annealing studies for a long time to come. The evidence for a competition between recovery and recrystalliza-tion is particularly convincing. The demonstration of edge-nucleated recrystallization was so clear that it may obscure the necessity for other types of "nucleation" sites; otherwise, single crystals of aluminum could not be recrystallized after cold work. At least three types of sites have been found to operate in iron: 1) high-angle boundaries, probably in the same manner as in aluminum, 2) matrix sites, 3) inclusions or second-phase particles. In each instance, the cells developed during cold work and perfected during recovery are the "nucle for recrystallization. Observations by ourselves and others of the dislocation structure of cold-worked metals and of the structural changes that occur during annealing have led us to doubt the validity of the basic assumption of the Lucke-Detert theory, and of the modification developed by Gordon and Vandermeer, that during recrystallization of a metal containing foreign elements in solid solution a high-angle boundary is ad vancing into a cold-worked matrix having a random distribution of solute atoms. We contend that an es sential part of the cold-working and annealing of solid solution alloys is the trapping of solute atoms by the low-energy "wells" afforded by individual dislocations and by dislocation arrays. If cells are formed during cold work, the cell walls are stabilized by this concentration of solute atoms. Thus, solutes inhibit recrystallization not only by decreas-ing the rate of high-angle boundary migration, but also by preventing the formation of high-angle boundaries by subgrain growth or coalescence, i.e., solutes can inhibit both "nucleation" and growth. In addition to stabilizing the dislocation Structure, the solute-dislocation interactions may produce clusters of solute atoms which are not as readily assimilated into the recrystallized grains as are individual solute atoms. There is an additional complication. The dislocation structure formed upon cold working a dilute solid solution may not be the same as that formed during cold working of the pure solvent metal. The solute can either enhance or minimize the formation of cells during cold working. Both effects have been observed in binary alloys of iron. The annealing process is inextricably connected with the mechanisms of strain hardening and solid solution hardening. Although the correlation between experimental boundary migration rates and the predictions made from the theoretical equations are impressive, it should be mentioned that in at least four other instances (Pb-Ag and pb-Au,15, Fe-Mn,16, Fe-Mo)17 the agreement was rather poor. In brief, while it is probable that the migration of high-angle boundaries is held back by solutes in the manner described, this is only a partial explanation of the total effect of solutes upon recrystallization of cold-worked alloys. Paul Gordon and R. A. Vandermeer (author's reply)— The authors first wish to thank Dr. Leslie for his compliments of this work. It is perhaps worth pointing out that some of Dr. Leslie's remarks are directed toward subject matter covered in two earlier papers in our work.18,19 We agree with Dr. Leslie's main contention that the exact nature of the metal structure in the vicinity of a boundary should have an effect on the boundary migration. The theory of Lucke and Detert does not take such detail into account, nor does it account for orientation effects on the migration rates. We assume that since our data checks the theory so well, the effects of detailed structure are statistically averaged out by the polycrystalline techniques used just as are the effects of orientation factors.

Jan 1, 1963

By W. E. C. Coxe

Many of you who are interested in the manufacture of iron and steel, have no doubt heard of the "Wheeler process for combining iron and steel." Mr. Wheeler has formed a company, styled the "Combination Trust Company," whose business is to grant licenses for the use of this patent process in producing what he calls "iron-clad steel." It has been proposed to apply it in the manufacture of car or wagon axles, also to shafting, having steel cores or centres covered with iron; to tubes of steel with an inner and outer skin of iron ; to structural purposes, such as girders and beams; bridge and tie-bolts, where the strength of the iron and the rigidity of the steel would be desirable. In answer to a request from Mr. Wheeler, permission mas accorded him to make some experiments at the rolling mill of the Philadelphia and Reading Coal and Iron Company, at Reading, Pennsylvania, with a view to manufacturing some steel-headed rails. In making this kind of a rail two difficulties are encountered. If the iron is brought to the requisite heat to weld properly, the steel is likely to be burned; if the steel is cared for, to prevent burning, the several layers of iron are not brought up to the proper welding heat. Mr. Wheeler claimed that the steel slab covered with iron which he furnished for the head of the rail could net be injured by any heat to which it might be subjected in the ordinary course of heating the rail-pile. He claimed, also, that by this method the porosity, which he thought was characteristic of all solid rails of Bessemer steel, would be overcome. Four steel slabs were furnished for this experiment, being Bessemer steel of .61 carbon, made at the Edgar Thomson Steel Works, and covered with iron in one of the Pittsburgh mills. The slabs were in section seven inches wide by three inches thick, and the iron covering was one-eighth to three-sixteenths inch thick. Each slab was placed on a pile of iron made up in the ordinary way for a rail fifty-six pounds per yard and thirty feet long. The heating was under the personal direction of Mr. Wheeler, and

Jan 1, 1879

By Cyril Stanley Smith

Jan 1, 1949

By Cyril Stanley Smith

Jan 1, 1949

[FUQUA, H. B. and Thompson, B. E.: Oil and Gas Development and Production in North Texas for 1933, 107, 320; for 1934, 114, 417 Oil and Gas Development in West Texas 114, 438 FURMAN, W. F.: Heat and Corrosion-resisting Alloys. Printed in Oil & Gas Jnl., June 13, 1935 Furnace-bottom sand, uniformity, 73, 390 Furnace control, Isley apparatus, M27, 502 Furnaces (See also Holt-Dern; Blast Furnaces; Roasters; Wirebar, etc.): annealing: electric, 89, 424 gas-fired, 89, 425 gas vs. wood for nonferrous metals, 89, 422]

Jan 1, 1936

By W. W. Eckles

This paper is presented as a suniniary report of the use of well gas composition correlations obtained from mass spectrometer recordings as a means of identification and determination of reservoir continuity. Conventional methods for detecting composition differences are en-pensive, elaborate, and difficult to obtain. This excludes the use of extensive composition data for most applications. During recent years the mass spec-trometer has come into general use as an analytical tool in petroleum refineries. The use of mass spectrometer composition patterns ir~ characterizing or "finger-printing" the produced gas from a reservoir, presents a novel method for correlatitlg gas samples from well to well. The mass spectrometer provides a trace similar to an electric log. having peaks which represent the abuntlnnce of certaitz hydrocarbons in the well gas sample. Without going further into the detailed analysis the idea has been advanced that these traces or patterns could be used as a means of identifying a particular natural gas. This theory has proven to be essentially correct. The mass spectrometer pattern method is simple and cheap as COi?7pared to other standard methods. It greatly facilitates the solution of reservoir and geological problems in which correlation of well gas Com-positions is a factor. Specific field applications have been made. This paper concerns the results obtained in 465 individual gas analyses from 35 fields and 77 res- ervoirs. In a number of cases it has been found that such data have been extremely valuable in the determination of reservoir continuity. In at least one case, the method was a valuable contribution in tracing a reservoir from sand to sand in a coinplex fnulted field involving n11rnerous gas reservoirs. Field applications are presented to illustrate the possibilities of the method at the present stage of developnient and to stimulate the ernployrnent of this new approach by geologists and petroleum engineers in the industry. INTRODUCTION Identification of producing horizons and the determination of reservoir continuity are often a problem in those areas where dome structures and highly faulted sands are encountered. To complicate the picture further, there may be numerous sands, one on top of the other which dip and diverge in different directions. Even though it may be possible to develop some solutions to the preceding problems on the basis of the geological and reservoir data on hand. it is readily recognized that substantiating data based on independent methods would he extremely valuable. It has been found through field studies that correiation of well gas composition can be used to advantage in the geological and engineering study of a complex reservoir identification problem. METHOD FOR COMPARISON AND CORRELATION OF WELL GAS SAMPLES Since a large number of well gas samples are required in a gas identification or reservoir con- tinuity problem, it is necessary that a method of analysis be employed which can detect differences in composition readily and inexpensively. Although detection would be possible by means of low temperature fractional distillation (POD) analpsis, the method requires a relatively large sample and is comparatively slow and expensive to run. The mass spectrometer affords an inexpensive and precise analysis of small well gas samples taken at the surface which are about 1/300 as large as a POD sample. These samples can be obtained by regular field personnei and shipped to the spectrometer for analysis. It is, therefore, a practical approach to the problem. A typical record from the mass spectrometer is illustrated in Fig. I. The peaks on the record represent the abundance of ions produced from the different hydrocarbon molecules making up the gas sam-ple. In well gas comparisons only five peaks are employed, since the other peaks are formed from the same gas molecules and furnish no additional information. The five peaks used represent the abundance of methane, propane, ethane, butane and heavier, and oxygen. They are referred to respectively as the 16, 29, 30, 43, and 32 peaks. The oxygen peak is used to correct for air content in

Jan 1, 1958