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By R. D. Nelson, S. D. Dahlgren

The conditions of temperature, strain rate, and total strain favoring deformation by grain boundary sliding, slip, or deformation with concurrent recrystallization were evaluated for alpha plutonium. Grain boundary sliding and slip were studied by examining structures formed on polished surfaces with 4.5 pct compressive deformation. The conditions required for recrystallization were determined from compressive deformation us time curves. At 110" C and at a strain rate of 10&apos;per min, deformation was almost exclusively by grain boundary sliding whereas slip was the predominant deformation mode at -10°C and lo-&apos; per min. Defarmation at intermediate tenzperatures and strain rates produced structures showing mixtures of grain boundary sliding and slip. Recrystallization occurred concurrently with deformation only after a critical strain was reached. About 14, 6, and 3 pct strain was required at 105", llO°, and lZO°C, respectively, before recrystallization started, irrespective of the strain rate in the range of lo-&apos;1 to 10&apos;4 per nzin. L HE temperature and strain-rate dependency of the modes of plastic deformation were evaluated for high-purity as-cast alpha plutonium. The techniques used to study slip and grain boundary sliding were similar to those employed previously for alpha plutonium by Bronisz and Gorum,&apos; and spriet.&apos; Recrystallization was investigated using the methods reported by Nelson.3 Bronisz and Gorum&apos; found that slip occurred on more than one slip system at room temperature, and suggested that grain boundary sliding also contributed to the deformation. spriet2 found that deformation was predominantly by slip at room temperature, and observed one to three orientations of slip traces in individual grains. In addition, he deformed polished samples at 10O° C, but concluded that the deformation character of alpha plutonium at 100° C and at room temperature were not essentially different. Several investigators reported that twinning was only occasionally observed.1&apos;2&apos;4 Nelson3 recently found in creep tests that high-purity alpha plutonium would recrystallize concurrently with compressive deformation at temperatures between 25" and 115°C. EXPERIMENTAL PROCEDURE Electrorefined plutonium having less than 300 ppm total impurities was received from Los Alamos Scientific Laboratory in the form of +-in. diarn cast rods. Major impurities were americium, <I00 ppm, and tungsten, (60 ppm. Less than 25 ppm each of other impurities were present. The rods were cut into right half-cylinders 0.35 in. long and 0.25 in. in diam, and the flat faces along the cylinder axes were metal-lographically polished. To avoid loss of the metallo-graphic polish by oxidation, the polished samples were deformed in a silicone fluid heat treating medium contained in a chamber evacuated to a pressure of lo-&apos; torr. Deadweight loading was used to compress the samples between 4.5 and 20 pct at strain rates between 10"4 and lo- &apos; min-&apos;. Strain rates were determined by dividing the total deformation by the elapsed time of the test, even though the strain rate was not constant during deformation. Curves of strain vs time for samples deformed with a constant compressive stress3 show that the strain rate changes by less than a factor of four during the testing of a given sample, which is small compared to the three orders of magnitude change in strain rate investigated. Two samples were loaded into an ordinary metallographic mounting mold and impacted by striking the mold piston with one blow of a 2-lb hammer. Deformation temperatures for the two impact samples were 25" and 90°C. The samples, following deformation, were washed in carbon tetrachloride and their polished and deformed surfaces were immediately inspected metallographi-cally. Subsequently, the deformation structures were replicated with acetate replicating tape for later electron microscope examination, and the samples were then repolished and etched to reveal the microstruc-tures of the deformed metal. Second-stage carbon replicas were prepared from decontaminated acetate replicas using the procedure developed by Miller, Bierlein, and astel.&apos; Additional samples, which were 0.35 in. long by 0.25 in. in diam, were used to obtain constant load deformation vs time curves. These samples were deformed 10 to 20 pct with loads of 15 and 20,000 psi at 120°C; 30, 45, and 55,000 psi at 110°C; and 20 and 30,000 psi at 105°C. Samples were polished and etched to determine whether or not recrystallization or twinning had occurred during deformation. RESULTS AND DISCUSSION The experiments showed that alpha plutonium deforms by grain boundary sliding, slip, and deformation with concurrent recrystallization. Deformation by twinning was insignificant. Metallographic examination of polished and deformed surfaces revealed grain boundary sliding and slip. The start of recrystallization was ascertained from constant load deformation vs time curves. Deformed surface structures of samples compressed 4.5 pct under four different conditions of temperature and strain rate, Fig. 1, show how the deformation mode changes from predominantly grain boundary sliding to predominantly slip with increasing strain rate and decreasing temperature. Deformation at 110°C and 10" 4 min-&apos;, Fig. l(a), was predominantly by grain boundary sliding. Only a few slip traces can be seen in Fig. l(a).

Jan 1, 1969

By ROBERT E. CROCKETT

MAGNETITE mining and milling in New York, New Jersey and Pennsylvania continued to remain comparatively inactive during 1933, owing to the low rate of output of the steel industry and also to unrestricted importation of foreign ores. However, some improvement over conditions existing in 1932 was noticeable, particularly in New Jersey, where one plant, that of the Washington mine of the Alan Wood Mining Co., at Oxford, went on full production in August. At Lyon Mountain, N. Y., the Chateaugay Ore and Iron Co. resumed mining and milling operations in October, on a reduced scale, principally to provide employment during the winter months. The Chateaugay company produces a special low-phosphorus pig iron. During the year they obtained a contract to supply their product for use in the manufacture of the suspension cables of the New. Golden Gate Bridge.

Jan 1, 1934

By AIME AIME

IT IS impossible in this short sketch to give a detailed description of each part of the plant at Bethlehem, therefore, only such facts will be touched on as are necessary to give a general idea of the works. The extent of the plant, and the fact that the units making up the various departments are located in different parts of the works, make it impracticable to mention the departments in any regular order with regard to their location. They are, therefore, mentioned approximately in the order of their relation to each other with reference to their functions in the making of the various products.

Jan 1, 1924

By Robert B Sosman

The relative temperature distribution within a coke oven and among the ovens in a battery can be obtained automatically for the operator&apos;s guidance by sighting a total-radiation pyrometer on the face of the coke as it is pushed out, and recording the surface temperature. Keeping the instrument clean and keeping its view of the coke unobstructed by smoke and dust are the principal problems. Typical records from three plants are presented in this paper, showing that the temperature patterns are reproducible. Development OF Method The method of coke pyrometry described in this paper was introduced in 1936 by E. A. Lee, then Assistant Superintendent, now Superintendent, of the Coke Plant at Lorain Works, National Tube Co., Lorain, Ohio. At the request of the Coke Committee of the United States Steel Corporation, the Research Laboratory of the Corporation undertook to adapt the method to the somewhat different conditions met with at the Gary Works of the Carnegie-Illinois Steel Corporation, Gary, Ind., and at the Clairton Works of the same Corporation at Clairton, Pa. This work was done in cooperation with the Leeds and Northrup Co. of Philadelphia and later with the Brown Instrument Co. Division of Minneapolis-Honeywell Regulator Co., Philadelphia. We of the Research Laboratory wish to express our appreci- ation of the courtesies extended by Mr. Lee, by A. N. Cole, Superintendent of the Gary coke plant, and by D. P. Finney, Assistant General Superintendent in charge of coke-plant operations at Clairton. We are also indebted to the instrument companies for the loan of a part of the equipment. At Gary and Clairton the instruments were installed and various experiments were made by J. W. Bain, of the Research Laboratory of the United States Steel Corporation. Pyrometry of Coke The coke inside a by-product oven is almost completely inaccessible to pyro-metric instruments. The temperature in the walls can conceivably be measured with thermocouples, but the atmosphere is usually strongly reducing, a condition well known to be destructive to the accuracy of the customary high-temperature couples. In some plants, periodic readings are taken with an optical pyrometer sighted into the top of the combustion flues. This is a useful measure for safety and general control, as it tends to prevent the damage that would result from overheating of the ovens. It does not, however, tell much about the temperature of the coke itself, because of the continually changing gradient in the wall between the coke and the combustion chamber. The best indication of the temperature of the coke itself must therefore be obtained by observation of the product as it is pushed out of the oven. The human eye is very sensitive to variations in brightness of a surface, and particularly to differences in brightness over a continuous hot surface.

Jan 1, 1943

By Robert B. Sosman

The relative temperature distribution within a coke oven and among the ovens in a battery can be obtained automatically for the operator&apos;s guidance by sighting a total-radiation pyrometer on the face of the coke as it is pushed out, and recording the surface temperature. Keeping the instrument clean and keeping its view of the coke unobstructed by smoke and dust are the principal problems. Typical records from three plants are presented in this paper, showing that the temperature patterns are reproducible. Development OF Method The method of coke pyrometry described in this paper was introduced in 1936 by E. A. Lee, then Assistant Superintendent, now Superintendent, of the Coke Plant at Lorain Works, National Tube Co., Lorain, Ohio. At the request of the Coke Committee of the United States Steel Corporation, the Research Laboratory of the Corporation undertook to adapt the method to the somewhat different conditions met with at the Gary Works of the Carnegie-Illinois Steel Corporation, Gary, Ind., and at the Clairton Works of the same Corporation at Clairton, Pa. This work was done in cooperation with the Leeds and Northrup Co. of Philadelphia and later with the Brown Instrument Co. Division of Minneapolis-Honeywell Regulator Co., Philadelphia. We of the Research Laboratory wish to express our appreci- ation of the courtesies extended by Mr. Lee, by A. N. Cole, Superintendent of the Gary coke plant, and by D. P. Finney, Assistant General Superintendent in charge of coke-plant operations at Clairton. We are also indebted to the instrument companies for the loan of a part of the equipment. At Gary and Clairton the instruments were installed and various experiments were made by J. W. Bain, of the Research Laboratory of the United States Steel Corporation. Pyrometry of Coke The coke inside a by-product oven is almost completely inaccessible to pyro-metric instruments. The temperature in the walls can conceivably be measured with thermocouples, but the atmosphere is usually strongly reducing, a condition well known to be destructive to the accuracy of the customary high-temperature couples. In some plants, periodic readings are taken with an optical pyrometer sighted into the top of the combustion flues. This is a useful measure for safety and general control, as it tends to prevent the damage that would result from overheating of the ovens. It does not, however, tell much about the temperature of the coke itself, because of the continually changing gradient in the wall between the coke and the combustion chamber. The best indication of the temperature of the coke itself must therefore be obtained by observation of the product as it is pushed out of the oven. The human eye is very sensitive to variations in brightness of a surface, and particularly to differences in brightness over a continuous hot surface.

Jan 1, 1943

By G. G. Marino, J. W. Mahar

This paper provides an understanding of the behavior and potential damage of homes resulting from sag-type mine subsidence. This is done with extensive research of numerous case histories in Illinois collected by the authors. The house response to subsidence-induced ground displacements are summarized and evaluated. A damage level criteria, specifically developed for residential structures, is presented based primarily on repair costs. Damage levels and the associated subsidence profile characteristics for each case history are compared.

Jan 1, 1986

Jan 1, 1901

By V. H. Gottschalk

SEVERAL years ago a group in the metallurgical division of the U. S. Bureau of Mines began a study of the application of new developments in physics to metallurgical problems&apos;. Among these developments were the extensions of what may be termed by analogy the "sound spectrum." Electromagnetic waves, from X-rays to radio waves, have been quite thoroughly explored for metallurgical use, but the sound spectrum, extending from low-frequency vibrations involved in certain types of metal failure by fatigue through the range of audible sound to inaudible vibrations having frequencies of many kilocycles, has had only meager consideration from metallurgists. Because of the general interest in the process recently demonstrated by St. Clair3 for flocculating smoke by means of sound waves, this article is written to point out possible applications of sound and supersonic (ultrasonic) waves in the metallurgical industry.

Jan 1, 1937

By M. A. Schimmelpfennig, A. D. S. Gillies

Loss of visibility due to the occurrence of atmospheric fogging in underground mine airways can lead to longer travel times and loss of production efficiency, an increase in the frequency of vehicular and foot traffic accidents and difficulty in checking rock surfaces for instability and loose material. Where hot and humid surface air meets colder underground air, conditions for fog formation may be present. Further, suspended particulate matter from diesel exhausts or stoping operations together with slow movement of air along passageways may contribute to formation. This study describes an investigation being undertaken with the cooperation of Kennecott&apos;s Ozark Lead Co. to identify causes of the problem.

Jan 1, 1984

[PAGE PREFACE. A. B. PARSONS 3 OFFICERS AND DIRECTORS 7 STANDING AND SPECIAL COMMITTEES 8 PROCEEDINGS OF 1935 MEETINGS 10 NEW YORK, FEBRUARY 10 CHICAGO, OCTOBER 14 SAN FRANCISCO, OCTOBER 14 HOUSTON, OCTOBER 15 ST. LOUIS, OCTOBER 15 ABSTRACTS OF PAPERS PUBLISHED IN 1935 17 TECHNICAL PUBLICATIONS AND CONTRIBUTIONS, 1935 64 INDEX OF 1935 PUBLICATIONS 71]

Jan 1, 1936

By H. D. Wilde

GREAT emphasis is being placed today on petroleum as a source of chemicals. Such prominence is well merited, for rapid strides have been made in developing processes for the conversion of petroleum into synthetic chemical products, which are now being made on a huge scale. These marvelous accomplishments have resulted in some highly optimistic predictions as to what can be expected in the future. Many of these forecasts are well justified, but some writers, especially those contributing to the Sunday supplements and the popular-cience type of publications, have let their imagination run wild and present a rather distorted picture of the possibilities in this field in the postwar period. Commercial manufacture of synthetic organic chemicals had its beginning in England with the establishment of a plant by Sir William Perkin in 1857 for the manufacture of "Aniline Purple" or "Mauve." The preceding year he had discovered in the laboratory how this dyestuff could be made from aniline, one of the many derivatives of coal tar, and he soon made commercial application of his discovery. Influenced largely by his success, organic chemists began research on production of a vast array of synthetic dyestuffs, medicinals, flavors, scents, and explosives. Rapid progress was made and by the turn of the century hundreds of these products were being manufactured. Most of these synthetic chemicals were derived from materials obtained as by-products in the conversion of coal into coke. These by-products are generally referred to as "aromatics" and are obtained by processing coal tar recovered in the coking process, so they are popularly known as "coal-tar chemicals." During the early years of this century, coal-tar chemistry was the wonder of the age, and rightfully so, since the products so made seemed limitless.

Jan 1, 1944

By Edward Hart

The specimen of glazy iron used for analysis was highly characteristic in appearance. It was made at one of the furnaces of the Glendon Iron Works, working a light burden of ore with a highly silicious cinder. There are very few records of analyses of this variety of iron. I have been able to find but the two given by Bell, and I add these to my analysis for comparison. Bell. 1. 2. Iron,......89.47* 88.18 90.70 Carbon, combined,.... 0.00 0.79 0.71 Graphite,......2.88 2.59 2 68 Silicon,......5.47 5 13 5.13 Manganese,.....1.54 0.77 0.56 Sulphur,......0.04 0.17 0.23 Phosphorus,.....0.60 1.12 1.12 Titanium,.....- 0.26 0.18 Calcium,......0.00 0.22 0.20 Magnesium,.....0.00 0.06 0.03 100.00 9929 101.54

By R. Q. Shotts

Data are presented which show that fractions of varying densities from the same coals are oxidized at different rates by nitric acid. From oxidation data, the approximate quantity of "bright" and "dull" components may be calculated. Definite relationships between oxidation rate and rank are shown for density fractions from at least two bituminous coals. IN 1945, the Alabama State Mine Experiment Station initiated a program on the determination of fusain in certain coals of the state.1 Because of the lack of equipment and personnel necessary for microscopic examination, the chemical method2 was used exclusively. During studies of the distribution of fusain in fractions of various sizes and densities on a medium volatile coal, the author noted a higher rate of oxidation of the nonfusain part of the coal in the lower density fractions and the difference in rate became more marked the shorter the oxidation period used. Since durain and other "dull" components of coal have been reported3,4,5 to have higher densities than vitrain and the bright components, it appeared probable that the observed differences in rates of oxidation in the different density fractions were due to variations in petro-graphic composition. Such effects have been noticed by other workers.2,3 In order to obtain further evidence on this point, several Alabama coals of different rank have been separated into three or more fractions on the basis of density and their rates of oxidation determined, using the procedure specified for the determination of fusain, except that measurements were made at short time intervals as well as for the longer periods specified in the regular procedure. Significant differences in the rates of oxidation of the nonfusain part of the various fractions have been observed, and it is believed that studies of this type may make possible the identification of individual petrographic components or lead to methods for their semiquan-titative estimation. Properties of the Coals: Analyses and some properties of the whole coals studied are given in table I. The range in rank of the coals is not the widest possible within the state, but samples of the low volatile coals that occur in thin beds in the northeastern part of the state, were unavailable. The Clements bed is not, at present, considered workable. The coal is of medium volatile rank, quite friable, and very strongly swelling. Analyses of different size fractions show that the larger sizes are of higher rank than the smaller ones. Material passing the No. 50 sieve (all sieve sizes refer to the U. S. Standard Series) is close to high volatile A in rank, except for the size passing a No. 200 sieve, in which fusain is partially concentrated. Because of the variation in rank of the sizes of Clements coal, oxidation studies were made of two widely different size ranges. The + 1-in. material was crushed on rolls to about 1/8 in. and separated into five fractions by float-and-sink treatment in a benzene-carbon tetrachloride mixture. The — No. 4 + No. 8 and the — No. 4 + No. 50 size ranges tested overlap but the latter size was studied last with the expectation that it would include more oxidizable material than the first size. This proved not to be the case. Yields and properties of the specific gravity fractions oxidized are shown in table II. Milldale bed coal probably represents, as nearly as it is possible to do so, the "average" coal of the state. The material passing a No. 4 sieve was the only size range oxidized. It was divided into four specific gravity fractions. As in every case the heaviest fraction, which was essentially rock, was discarded. The Black Creek is the most extensive in area of

Jan 1, 1951

By R. Q. Shotts

Data are presented which show that fractions of varying densities from the same coals are oxidized at different rates by nitric acid. From oxidation data, the approximate quantity of "bright" and "dull" components may be calculated. Definite relationships between oxidation rate and rank are shown for density fractions from at least two bituminous coals. IN 1945, the Alabama State Mine Experiment Station initiated a program on the determination of fusain in certain coals of the state.1 Because of the lack of equipment and personnel necessary for microscopic examination, the chemical method2 was used exclusively. During studies of the distribution of fusain in fractions of various sizes and densities on a medium volatile coal, the author noted a higher rate of oxidation of the nonfusain part of the coal in the lower density fractions and the difference in rate became more marked the shorter the oxidation period used. Since durain and other "dull" components of coal have been reported3,4,5 to have higher densities than vitrain and the bright components, it appeared probable that the observed differences in rates of oxidation in the different density fractions were due to variations in petro-graphic composition. Such effects have been noticed by other workers.2,3 In order to obtain further evidence on this point, several Alabama coals of different rank have been separated into three or more fractions on the basis of density and their rates of oxidation determined, using the procedure specified for the determination of fusain, except that measurements were made at short time intervals as well as for the longer periods specified in the regular procedure. Significant differences in the rates of oxidation of the nonfusain part of the various fractions have been observed, and it is believed that studies of this type may make possible the identification of individual petrographic components or lead to methods for their semiquan-titative estimation. Properties of the Coals: Analyses and some properties of the whole coals studied are given in table I. The range in rank of the coals is not the widest possible within the state, but samples of the low volatile coals that occur in thin beds in the northeastern part of the state, were unavailable. The Clements bed is not, at present, considered workable. The coal is of medium volatile rank, quite friable, and very strongly swelling. Analyses of different size fractions show that the larger sizes are of higher rank than the smaller ones. Material passing the No. 50 sieve (all sieve sizes refer to the U. S. Standard Series) is close to high volatile A in rank, except for the size passing a No. 200 sieve, in which fusain is partially concentrated. Because of the variation in rank of the sizes of Clements coal, oxidation studies were made of two widely different size ranges. The + 1-in. material was crushed on rolls to about 1/8 in. and separated into five fractions by float-and-sink treatment in a benzene-carbon tetrachloride mixture. The — No. 4 + No. 8 and the — No. 4 + No. 50 size ranges tested overlap but the latter size was studied last with the expectation that it would include more oxidizable material than the first size. This proved not to be the case. Yields and properties of the specific gravity fractions oxidized are shown in table II. Milldale bed coal probably represents, as nearly as it is possible to do so, the "average" coal of the state. The material passing a No. 4 sieve was the only size range oxidized. It was divided into four specific gravity fractions. As in every case the heaviest fraction, which was essentially rock, was discarded. The Black Creek is the most extensive in area of

Jan 1, 1951

By AIME AIME

THE petroleum economics session," held on Wednesday morning, Feb. 20, 1929, presided over by Campbell Osborn, chairman, proved to be of un- usual interest and resulted in serious and constructive discussion of the papers presented. The first paper on the program, "Gasoline Economics and Refinery Operation," was by H. J. Struth, petroleum economist of the Gulf Publishing Co., Houston, Tex. While this paper was intended to cover the re- finery situation, it also presented the author&apos;s reasons for believing that the oil producer should give cognizance to gasoline demand as a most reliable barometer by which to parallel the production of crude petroleum. The discussion which followed brought out some interesting points in connection with the immediate outlook for the industry as a whole during the present year. Some advanced the opinion that, regardless of the out- come of proration efforts, the refiner is in a position to conduct his operations on a reasonably profitable basis, provided that he exercises control over them. This would mean running less crude and resorting to wider utilization of cracking to produce the gasoline demand. Thus, if the refiner uses diligent care in scheduling his still runs, the producer will be obliged to carry over a large stock of crude this year, unless he is able to keep production below the limits prescribed by the demand for gasoline.

Jan 1, 1929

By Arnulf Muan, R. W. Taylor

Activities of iron in Fe-Pt alloys have been dctermined by equilibrating mixtures of platinum metal and iron oxide at known oxygen Pressures in a thermobalance at 1300°C. Conzpositions and iron activities of the oxide phase at equilibrium are known from previous work, and compositions of the Fe-Pt alloy phase formed at equilibrium were detcvt?zined from the observed weight changes of the samples. The activity curve obtained shows a strow negative deviation from Raoult&apos;s law. THE present investigation was undertaken as part of a research program dealing with phase equilibrium relations existing among the oxides of iron and titanium at 1300°C. At low oxygen pressures of the gas phase in equilibrium with these oxides, the iron activity of the system is high, and considerable alloying of iron with the platinum used as a container material takes place. Thermodynamic data for Fe-Pt alloys at 1300°C are needed in order to evaluate quantitatively the extent of such reactions. Larson and chipmanlhave determined activities of iron in Fe-Pt alloys at 1550°C by equilibrating platinum metal with CaO-iron oxide-SiOzmelts in which the iron activities were known. Compositions of the resulting Fe-Pt alloys were determined by chemical analysis. Mundiath and Gerassimov2 have studied thermodynamic properties of Fe-Pt alloys by electromotive force measurements in the temperature range 550" to 1000°C. The experimental method used in the present investigation is a slight modification of that used by Grube and Ratsch3 in studies of NiCr-alloys. 1) EXPERIMENTAL METHOD 1) General. Mixtures of platinum metal and iron oxide were equilibrated at 1300°C in atmospheres of known oxygzn przssures, and the course of the reactions was followed by measuring the weight changes of the mixtures. The principles involved in the derivation of composition-activity relations from these measurements are illustrated by the composition triangle for the system Fe-FeZO3-Pt shown in Fig. 1. Take as an example a mixture of FeZO3 (hematite) and platinum such that the total composition is represented by point T. If this mixture is heated to 1300c in air (poz = 0.21 atm) and the oxygen pressure is then reduced gradually, the oxygen content of the oxide phase decreases and increasing amounts of iron enter the metal phase. As the oxide phase and the metal phase for all practical purposes are insoluble in each other, their compositions are represented by points moving toward Fe along the joins Fe-Fe,03 and Fe-Pt, respectively. The total composition of the mixture during this process also changes, but only with respect to oxygen content, because the vapor pressures of iron and platinum are negligible at 1300°C. Hence the change in total composition is described by a straight line (constant Fe/Pt ratio) radiating from the 0 apex of the composition triangle Fe-Pt-0, of which the triangle in Fig. 1 is a part. Only one such line ("oxygen reaction line", T-T",) is shown in Fig. 1. The total composition of the alloy-iron oxide mixture at any instant must, in addition, be located on the straight line (conjugation line) connecting the two points representing the compositions of the two coexisting phases. It therefore follows that the total composition of the mixture at any instant is represented by the point of intersection between the conjugation line and the oxygen reaction line. An example of the situation prevailing at a chosen oxygen pressure, po2, is shown in Fig. 1 by points a&apos; (alloy composition), b&apos; (oxide composition) and T&apos; (total composition). Point b&apos; is known from the work of Darken and Gurry,4 and point T&apos; is experimentally determined by the observed weight change of the mixture (distance T-T). Hence, point a&apos;, the composition of the alloy, is determined from the above data as the intersection between the join Pt-Fe and the extension of the straight line bl-7&apos;. The activity of iron in the alloy at equilibrium is identical to that of the iron oxide phase, if the same

Jan 1, 1962

By Frank Milliken

IN September 1937, the Ohio Copper Co. inaugurated the treatment of its copper-bearing mill tailings at Lark, Utah. These tailings had been accumulated during the regular operation of the Ohio Copper mine and mill over the period 1007 to 1019. Gravity concentration had been employed except for a comparatively short period in 1919, when flotation was used. The ore milled during that period assayed about I per cent Cu. The chief copper mineral, chalcocite, was dissemi-nated in a shattered quartzite, mainly along fracture or cleavage planes. The quartzite gangue was extremely hard and grinding to liberation resulted in excessive sliming of the "sooty" chalcocite, with consequent high tailings losses. Recovery on the seven million tons treated was prob-ably less than 6o per cent of the total copper content. As early as 1918, attempts had been made to sample the dump. In 1928, a com-plete sampling program was undertaken. The sampling consisted of seventy-four 5-in. post auger holes drilled to the full depth of the dump at regular intervals of 250 ft. Each 10-ft. portion thereof com-prised a sample for analysis. Each sample was screened, rolled, divided into three parts, dried and assayed. The reject was retained for testing purposes. From the depth of the auger holes a contour map of the dump was plotted, Fig. 1, which gives percentages of tonnage and copper content.

Jan 1, 1940

By S. J. Rothman, L. T. Lloyd

S. J. Rothman and L. T. Lloyd (Argonne National Laboratory)— Hagel&apos;s paperz0 discusses the question of the mechanism for self-diffusion in bcc transition metals. Recent work21"23 has led us to agree with him in reabandoning the ring mechanism in favor of a defect mechanism, most likely vacancies. On the other hand, we think that Hagel&apos;s attempt to group together all self-diffusion in bcc transition metals is wrong. We prefer the scheme of Peart, Graham, and omlin," who separate them into two groups. One group contains the anomalously behaved metals P titanium,&apos;, y uranium, and perhaps zirconim.&apos; The other group contains a iron," this alloy was held at 1800°C for 2 hr before quenching, its structure was all a. B. C. Giessen, I. Rump, and N. J. Grant (Authors&apos; reply)—We very much appreciate the discussion by Deardorff and Kato regarding the a to /3 transformation temperature of hafnium. In the W-Hf program, as well as in a current study of the system Cr-Hf, standard precautions were exercised against contamination, including vacua of less than 10"5 mm Hg and a weight control check of all specimens to insure an impurity rise of less than 100 ppm. Following receipt of the above discussion, a revision was made in the annealing process. Arc-cast specimens were etched with a 10 pct HF-90 pct HNO solution until 1 mm of surface, including a possible oxide film, was removed. Annealing was done in a hafnium container which provided a long diffusion path for gaseous contaminants. Finally, the heat treating time was shortened. Structural changes were noted to occur quite slowly. A 99.5 at. pct Hf alloy showed 70 pct /3 after 30 min at 1700°C and was 100 pct /3 after 10 min at 1715°C. After 24 hr at 1740C, the alloy was found to be 10 pct/3. This change is due to contamination; it was estimated that it corresponds to an increase of 60°C in the transformation temperature over a 24 hr period. The corresponding change in 30 rnin would be slight. Using the same hafnium as in the above publication, and three new alloys at 98, 99, and 99.5 at. pct Hf, the transformation temperature was indicated to be 1715" 15°C. Since this hafnium contained 4.4 at. pct Zr, a correction of 40 5C, based on an assumed approximately linear transformation temperature curve, must be made for pure hafnium. This yields a value of 1755 20°C in good agreement with Deardorff and Kato&apos;s value. Because the slope of the boundary is small, this permits a good extrapolation, and we regard the W-Hf alloys as well suited to check the Hf transformation temperature. niobirn,&apos;&apos; and molybdenum,22 whose activation energies correlate with the melting temperature and whose Do values follow Zener&apos;s predictions.28 We have no quarrel with Hagel&apos;s placing chromium into the second group; we disagree with his interpreting our data to make uranium fit into that group. Hagel considers that the measurements of self-diffusion in uranium below about 950°C represent combined volume and grain boundary diffusion. This contention is based on the curvature of the penetration plot for our 891°C run,4 which also has a nearly straight line plot of log c vs x. Hagel has extrapolated these characteristics to our 803.5C run and fitted his Arrhenius plot for self-diffusion in y uranium to our four highest temperature points only. We think this is wrong for the following reasons.

Jan 1, 1963

By Michael S. Roscoe

In order to more accurately predict longwall surface subsidence over the Pittsburgh No. 8 Coal in Eastern Ohio, North American Coal Corporation's Quarto Mining Company undertook or participated in several subsidence studies. Due to the changing roof geology and rapid variations in the amount of cover two separate areas were investigated at two different mines to determine the subsidence response if any to these changes. Data generated from these studies were compared with NCB derived,data for accuracy and then used to predict subsidence under houses, gas lines and other critical man made structures. The following report summarizes the results of these studies as well as the subsidence case histories of gas lines, transmission towers, houses and water wells. Problems that were encountered during both phases of this process (investigation and subsequent application) are also included.

The Industrial Minerals Div., of the AIME meeting scheduled for Nova Scotia Sept. 8-12, 1953, promises to be one of the outstanding gatherings ever attended by the group. Complementing the educational value of technical sessions will be the superb fishing, boating, golfing, and tennis facilities. [ ] Sponsor of the meeting is the Nova Scotia Mining Society. The Canadian Institute of Mining and Metallurgy and Industrial Minerals Div., AIME have been invited to participate. The land immortalized by Longfellow&apos;s poem, Evangeline, still contains much of the forest primeval-enough to make it a wonderful vacation spot for delegates and their families. Its scenic beauty is almost unmatched in the area north of the border. Quoting from the Nova Scotia tour book; "Nova Scotia, once known as Acadia, is 374 miles long, from 600 to 100 miles wide ... Excepting the Isthmus of Chignecto, 17.5 miles wide, the province is entirely surrounded by water, no portion being more than 50 miles from the sea . . . has 4625 miles of coastline, guarded by 356 lighthouses and fog alarms. The province is renowned for its picturesque coastline, its harbors dotted with islands, its deep valleys and multitude of beautiful lakes." A progress report on the plans for the meeting will be made monthly. Thus far, technical sessions will be held at Keltic Lodge, Ingonish, N. S. The lodge will also be the starting point for many of the field trips and social events which are in various stages of planning and development.

Jan 1, 1952