Search Documents

By Thys B. Johnson

Traditional mine planning concepts are discussed and suggestions for improvement through use of the developed model are proposed. The approach developed in this paper allows optimal planning of the complete mining-concentrating-refining system over the entire planning horizon and permits the system to dictate how and when to process a block of material, i. e., a dynamic cutoff.

Jan 1, 1969

By Robert E. Green, Wolfgang Sachse

Simullaneous ultrasonic attenuation measurements of both quasishear waves propagating in single cryslals of aluminum indicate that, in the undeformed annealed state, the dislocation density is generally not uniform on all slip systems. Change oof attenuation measurements made during plastic defortnation of crystals , which possessed specific orientations ideal for studying the orientation dependence of dislocation damping, indicate that, for low strain levels, dislocation motion occurs on additional slip systems besides the primary one, even for crystals oriented for plastic deformation by single slip. THE sensitivity of internal friction measurements permits such measurements to be used successfully in studying the deformation characteristics of metal crystals. On the basis of experimental observations, T. A. Read1 was the first to associate internal friction losses with various dislocation mechanisms. Since that time further work2-' has been performed and a dislocation damping theory has been formulated by Granato and Lucke.6 In the amplitude independent region, this theory predicts the attenuation a to be dependent on an orientation factor O, a dislocation density A, and an average loop length L. if is a constant, independent of crystallographic orientation. For a given crystallographic orientation, changes in dislocation density and loop length give rise to the observed attenuation changes accompanying plastic deformation. The Granato-Liicke theory suggests the investigation of the orientation dependence of attenuation measurements in hopes of obtaining information to separate dislocation motion losses from other losses.7 An experimental study of the orientation dependence of attenuation in undeformed annealed single crystals should yield an insight into the uniformity of dislocation distribution throughout the entire specimen. A similar study on crystals plastically deformed in a prescribed fashion should give information about the alterations in the dislocation distribution on the slip systems activated during plastic deformation. The possible modes of elastic waves which can be propagated in aluminum,8 copper,9 zinc,10 and other hexagonal metals" have been calculated. Associated with each mode of wave propagation are dislocation damping orientation factors, which are based on the resolution of the stress field of that particular elastic wave onto the various operative slip systems in the material. These orientation factors have also been calculated as a function of crystallographic orientation in the papers cited above. Einspruch12 obtained agreement between predicted and observed attenuation values of longitudinal and shear waves in (100) and (110) directions of two undeformed aluminum crystal cubes. He ascribed the slight deviations between predicted and observed values to a nonuniform dislocation distribution, or to other loss mechanisms. In shear deformation of zinc crystals, Alers2 found that the attenuation of shear waves having their particle displacements in the slip plane was very sensitive to the deformation, while the longitudinal wave attenuation was affected only when the wave propagation direction was not normal to the slip plane. Using aluminum single crystals oriented for single slip, Hikata3 et al. found that during tensile deformation the change of attenuation of the shear wave (actually quasishear) having particle displacements nearly perpendicular to the primary slip direction exhibited the easy-glide phenomena, while longitudinal waves did not. Similar results were reported by Swanson and Green5 during compressive deformation of aluminum crystals. These results are in qualitative agreement with the calculated orientation factors for specimens of this orientation. In well-annealed, undeformed aluminum crystals, the damping is expected to be due to dislocations vibrating on all twelve slip systems. The orientation factors associated with this initial damping will be designated by O2 and O3, where a, represents the average orientation factor for the slow shear (or quasishear) wave and O3 represents the average orientation factor for the fast shear (or quasishear) wave. The calculation of these values for aluminum crystals by Hinton and Green8 shows that they vary very little as a function of crystallographic orientation—at most, by a factor of 2.47. If the dislocation density and loop length are uniform, then in the initial undeformed state, Here the subscript zero refers to the initial value of the attenuation. Also for aluminum, the calculations8 show that the orientation factors for primary slip only, associated with each shear wave, exhibit a sharp minimum for particular crystallographic orientations. A composite plot of the two shear wave orientation factors for primary slip only is shown in Fig. 1. Since these orientation factors are associated with dislocation motion occurring on the primary slip system only, the proper condition to check these factors might be attained by slightly deforming a single crystal oriented for primary slip. For dislocation motion on the primary slip system only,

Jan 1, 1969

By Donald M. Liddell, G. C. RIDDELL

THE cosmic ray continues to engage the attention of the physicists, and according to Millikan and Compton, experiments of the past summer indicate that these rays must come from interstellar space, but not from the stars themselves. According to press reports of the International Congress of Physicists at Rome, the view was given there that these rays have an initiating potential of over 750,000.000 volts. In the field of spectrographic investigation great strides have been made. The U. S. Naval Research Laboratories (R. F. Mehl and G. E. Doan of Lehigh) have just finished a year's work with a "radium torch" or "shadowgraphic apparatus" in the field of the X-ray, that bids fair to displace the latter to a great extent. The torch is more powerful., easier to operate and cheaper. Penetration of 10 in. of steel has been accomplished, which. is much -beyond the- -scope-, of the X-ray..

Jan 1, 1932

By Thomas T., Read

ANY discussion of State-supported schools of mining and A metallurgy needs to be prefaced by a definition, since the first school to offer a mining curriculum, the Pennsylvania Polytechnic College, was established by a grant from the State. But, so far as can be determined, it received no further State support. It would be tiresome to go into precise details,. and it will be enough to stipulate that by State schools are meant those which derive their main financial support from regular appropriations made by a State legislature. The University of Michigan was the first of these to offer a mineral industry curriculum; its story, as well as those of Wisconsin and Illinois, has been related in the preceding chapter.* Arranging the others in chronological order involves making a decision as to what weight to attach to plans for giving instruction, as contrasted with its , effective initiation. This may appropriately be illustrated by the history of mineral industry education in California. California Among those who came to California in 1849 and the following years were many New Englanders who had a keen interest in education. Some of them, mostly Congregationalists and Presbyterians, sought to establish a school of higher education around San Francisco Bay and eventually succeeded in opening the "Scientific and Classical School at Contra Costa' in Oakland, at Broadway and 5th St., on June 20, 1853. This prospered so well that it was chartered by the State as the "College of California" on April, 13, 1855. Developing so rapidly that its quarters became cramped, in 1864 it not only bought a tract of

Jan 1, 1941

By Louis D. Huntoon

After the completion, in 1905, of the Hammond Mining and Metallurgical Laboratory of the Sheffield Scientific School, Yale University, it became necessary to secure and assay a large assortment of ore-samples, and to arrange the results in such a manner as to admit of use with the least amount of work on the part of the instructor. At first, pulp-samples, together with their respective assays, were secured from the mines, smelters, and public aesayers, but this practice did not prove satisfactory. It was not only difficult to secure a suffciently large supply of material, but it was also impossible to secure the proper assortment required for instructing students. It involved considerable work for the donors to select the samples and furnish a record of the assays, and also for the instructors to examine each pulp and determine its character. Some of the samples did not contain a sufficient quantity of pulp for the student to check his work in case his first assay did not correspond to the record. In order to increase the number of samples and to vary the character of the material, pulp-samples were later mixed with barren rock and with sulphides, but this method also was unsatisfactory and has been discontinued. At present, small lots of ore are secured by gift or purchase from engineers, public assayers, and the managers of mines, mills, and smelters. These lots weigh from 10 to 100 lb. each, and are rarely finer than 0.25 in. in size. The larger samples permit of a careful study by the instructor in order to determine the best method of assaying to be followed. In universities in which assaying is taught the record of the samples should fulfill the following requirements:

Jan 1, 1910

There were two official representatives of Foreign Governments as guests at the Chicago Meeting. One was Frederick Goransson, managing director of the Saudvikens Steel Works, who represented the Jernkonteret, the Iron and Steel In-stitute of Sweden, and who came to this country especially for our meeting. The other distinguished guest was Commander Toublet, who repre-sented the French Embassy. Commander Toublet delivered a most polished address at the Banquet, dealing with the felicitous relations existing between this country and France for the last 150 years. Com-mander Toublet was accompanied by Mrs. Toublet, who won the hearts of all the ladies present, whose guest she was.

Jan 11, 1919

By J. Walter Snavely

PRESENT-DAY processing in many industries, calcining, sintering, briquetting, beneficiation and nodulizing, increasingly calls for the handling of large volumes of hot bulk materials. Various types of conveyors have been employed. This discussion will cover the factors governing their selection. For temperature ranges up to 400°F, or approximately 200°C, a wide range of conveyors is available. Special constructions of rubber conveyor belts. steel conveyor belts, vibrating and shaker conveyors, apron conveyors, and drag chain conveyors, all are used successfully. As temperatures go well above 400°F, however, choice of conveyors is narrowly limited. This paper will consider the problem of handling bulk materials only where the temperatures exceed 400°F.

Jan 5, 1953

MONDAY, FEB. 17 9.00 A.M. to 9.00 P.M. Registration at Institute Headquarters. 9.00 A.M. Meeting of Committee on Development of the Activities of the Institute, Room 905, 9th Floor. 10.00 A.M. Simultaneous Sessions of Institute of Metals Division, Room 2, 5th floor. Industrial Organization, Room 1, 5th Floor. 12.30 P.M. Luncheon at Headquarters, 5th Floor. 2.00 P.M. to 4.25 P.M. Simultaneous Sessions of Institute of Metals Division, Room 2, 5th Floor. Industrial Organization, Room 1, 5th Floor. Petroleum and Gas, Room 905, .9th Floor. 2.30 P.M. Sightseeing trip by automobile for the ladies. Among the points visited will be: The American Museum of Natural History. The Episcopal Cathedral of St. John the Devine. The Spanish Museum. The American Geographical Society. The American Numismatic Society. The visits will be followed by Tea. 4.30 P.M. Memorial Service to Dr. Rossiter W. Raymond, Auditorium. 8.30 P.M. Smoker, 5th.floor.

Jan 2, 1919

By R. S. Craig, W. E. Wallace, G. S. Kamath

The destruction of long-range order in Mg-Cd, has previously been thought to occur as a second order process. In the present work a variety of X-ray diffraction techniques are employed to show that in this case and in Mg-Cd alloys containing frorn 20 to 33 1/3 at. pct Mg the process more nearly resembles an ordinary first order phase transformation. It is found that the ordered alloy, which occurs as a single phase at lgw temperatures, transforms with increasing temperature into a Cd-enriched disordered (P) phase and an Mg-enriched ordered (a) phase. The interval over which these two phases coexist under apparently equilibrium conditiovs extends from 25" to 87°C content. At 33 1/3 at. pct Mg the two-phase region has disappeared. Measurement of the long range order parameter, s, for the ordered phase in MgCd, (from superlattice line intensities) shows that it disorders only very slightly before it is transformed into the p form. Kinetic experiments reveal that when the a phase is formed frorn the p phase by suitably quenching so as to suppress phase segregation, the transformation is essentially complete and the a phase has acquired its equilibrium value of S in less than 1 min. In an earlier investigation carried out in this Laboratory1 the rate of disordering of the MgCd3 superlattice was determined over an extensive range of temperature. The process was found to be first order and the rate constant, k, was established. At the lowest temperatures studied k was found to increase exponentially with temperature. At higher temperatures, however, it passed through a maximum and for the 100 deg interval below the point at which the superlattice was destroyed k was observed to decrease with increasing temperature. The various theoretical treatments1-3 of order-disorder phenomena lead to a negative temperature coefficient for k near the superlattice critical temperature but this region for MgCdB seemed unusually wide. Detailed analysis of the point indicated' that either the long-range order parameter, S, for MgCda varied with temperature in an anomalous way or the disordering in this instance is more complex than in the cases which have been treated theoretically. The original objective in the present work was simply to determine S vs temperature for MgCda to ascertain whether the disordering was in conformity with theoretical expectations.2° In an early stage of the work it was noted, however, that under equilibrium conditions ordered (a) and disordered (0) phases coexist in MgCd, over a considerable range of temperature. Since on thermo- dynamic grounds the coexisting phases must differ in composition, the investigation was enlarged to permit the compositions of the two phases in MgCd3 to be determined and to establish the extent of the two phase regions for alloys containing from 20 to 33 1/3 at. pct Cd.

Jan 1, 1963

By T. Cantwell, N. C. Rasmussen, H. E. Hawkes

Beryl is a mineral that may be difficult to distinguish from quartz by casual field inspection. The easily recognized green color and hexagonal crystal form of coarse-grained beryl are by no means universal, even in beryl from pegmatitic deposits. If it occurred as a fine-grained accessory mineral in an igneous rock, it would almost certainly escape detection unless samples were submitted for petrographic or chemical analysis. There may be substantial deposits of some beryllium mineral, other than beryl, that has been overlooked because that mineral also closely resembles the common rock-forming minerals. A reliable and simple method of identifying beryllium minerals and determining the beryllium content of a rock would be helpful in exploration. This article describes preliminary experiments in applying nuclear reaction to the qualitative identification of beryl and to the semiquantitative determination of the beryllium content of rock samples. Gaudin,1,2 the first to apply a nuclear reaction in detecting beryllium minerals, developed a method that irradiates the sample with gamma rays, which react with beryllium nuclei to produce neutrons. The neutrons are then measured with standard equipment. The cross section for this reaction is about 1 millibarn. The cross section is a measure of the probability that a reaction will take place, for example, between a beryllium nucleus and an incident gamma ray or alpha particles.3-5 At 1-millibarn cross section for the reaction, satisfactory performance required a source strength of the order of 1 curie (3.7 x 10"' disintegrations per sec, where each disintegration releases one or more gamma rays). The reactions will not take place if the gamma radiation is below a minimum energy, in this case 1.63 mev. The size of the source and the energy of the radiation made heavy shielding necessary for these experiments, both to reduce the background count of the neutron counter and to safeguard personnel. The original discovery of the neutron by Chad-wick in 1932 resulted from experiments with another nuclear reaction, induced by bombarding beryllium with alpha particles in which the products are carbon-12 and neutrons. The equation for this reaction is as follows:' " ,Be" + ,He'? 6C12 + 8,n' [1] re-particle neutron In the above nuclear equation (Eq. 1), the sub- script number indicates the number of protons in the nucleus (the atomic number) and the superscript the total number of neutrons and protons (approximately the atomic mass). For the alpha-neutron reaction the cross section is about 250 milli-barns, or 250 times that of the gamma-neutron reaction used by Gaudin. The positively charged alpha particle is repelled by the positive charge of the beryllium nucleus; it must, therefore, have a certain minimum energy in order to approach close enough to the beryllium nucleus to react. For reaction with the beryllium nucleus, the lower limit of the alpha-particle energy is 3.7 mev. The alpha-neutron reaction, with polonium-210 as an alpha source, was selected for the present experiments. Alpha particles are emitted by polonium-210 at 5.30 mev, which is adequate for the reaction with beryllium. Furthermore, this isotope of polonium emits alpha particles with negligible associated gamma radiation, thus eliminating the necessity of shielding. The half-life of polonium-210 is 138 days. Inasmuch as alpha particles carry a possible charge and are large compared with most nuclear particles, their energy is rapidly dissipated in passing through matter. Their range in standard air is 3.66 cm,3 and they penetrate only a few tens of microns into a mineral sample. The short range in air can be minimized by preparation of a flat sample surface that can be brought very close to the alpha source during analysis. On the other hand, short range of alpha particles in air lessens the radiological health hazard and makes it possible to use this method without shielding. It must be emphasized, however, that the alpha emitters are potentially very dangerous if they enter the human body. Polonium must be handled with extreme caution. The literature has reported experiments on the yield of neutrons from reaction of alpha particles with beryllium nuclei. Feld" reports that in intimate mixtures of polonium and beryllium, 3 x 106 eutrons per sec are produced per curie of polonium. Elsewhere in the same reference it is stated that a sandwich-type source yields about one third as many neutrons as an intimate mixture. A table of neutron yields for full energy polonium alpha-particles on thick targets as reported by Anderson7 is the basis of Table I. From Table I it can be deduced that the elements most likely to interfere, i.e., those that also produce neutrons when bombarded by alpha particles, are boron and fluorine. These data also show that it will probably not be possible to determine very small quantities of beryllium in rocks because of the masking effects of the major elements, sodium, magnesium, and aluminum. The neutrons emitted in the alpha reaction are detected by another nuclear reaction. Either of the

Jan 1, 1960

By P. Gordon

An isothermal jacket microcalorimeter, supplemented by metallographic, microhardness, and X-ray measurements has been used to study the isothermal annealing of high purity copper after room temperature tensile deformation. The amount of stored energy released during annealing has been measured as a function of deformation in the range 10.8 to 39.5 pct elongation. The data have shown the major heat effect to be associated with recrystallization and have allowed an analysis of the recrystal-lization kinetics and the calculation of activation energies of recrystallization. WHEN a metal is deformed plastically, some of the energy expended is dissipated as heat during the working process, while the remainder is stored within the metal in the form of lattice distortions and imperfections. During subsequent heating of the metal, the distortions and imperfections can be largely annealed out and the associated stored energy released as heat. It is apparent that measurements of the evolution of stored energy during such annealing may produce important information concerning the nature of the annealing mechanisms and the imperfections involved. Some excellent studies of this type have been made in the past, notably those of Taylor and Quinney,' Suzuki,2 Bever and Ticknor,3 Borelius, Berglund, and Sjöberg,4 and Clarebrough et al.5,6 None of this work, however, employed isothermal techniques, with the exception of the Borelius studies' in which only the early annealing stages were investigated. Since isothermal measurements, as compared with heating or cooling curve, have the merits that 1—they reveal the kinetics of a process more clearly, 2—the results obtained are more easily applied to theory, and 3—most fundamental investigations of annealing using techniques other than calorimetry have been carried out isothermally, it was considered important to apply calorimetry to the study of the isothermal annealing of metals. Accordingly, an isothermal jacket calorimeter of the Borelius type,' supplemented by metallographic, hardness, and X-ray measurements, has been used to study the annealing of high purity copper after room temperature tensile deformation. Experimental The microcalorimeter has been described fully elsewhere." Briefly, the specimen to be studied is placed in a constant temperature environment of virtually infinite heat capacity achieved, as shown in the drawing of Fig. 1, by means of a vapor thermostat. A high thermal resistance is provided between the sample and the environment and a sensitive differential thermopile (see Figs. 2 and 3) arranged with half its junctions in contact with, and thus at the constant temperature of, the environment, and the other half in contact with the sample. A reaction in the sample develops a small difference in temperature, AT, across the thermopile, which is followed by a recorder-galvanometer set-up as a function of time, t, and is converted to reaction heat per unit time, P, by the use of the equation AT P=a?T + b AT dt The constants, a and b, in Eq. 1 are determined by a simple calibration, making use of the Peltier heat developed by a small current run through the junction of a thermocouple located in an axial hole in the specimen (Fig. 2). In its present form, the limit of sensitivity of the calorimeter is a heat flow of 0.003 cal per hr. The copper used was the spectroscopically pure metal supplied by the American Smelting and Refining Co. in the form of 3/8 in. diam continuously cast rod, reported to be 99.999+ pct Cu. A small amount of the copper was available at the start of this work and is referred to hereafter as lot A. A second batch, lot B, was obtained later, most of the results described subsequently being for this lot. As will be seen, there is some indication that lot A was somewhat purer than lot B, but it is not known whether this difference was present in the as-received metal or arose during subsequent handling. The two lots of copper were remelted and cast into two 1½ in. diam ingots in vacuo, using high purity graphite crucibles and molds. The ingots were upset several times to break up the large cast grains, and then rolled and swaged to rods 0.391 in. in diameter, using several intermediate anneals with about 40 pct reduction in area between anneals. The penultimate anneal was 2 hr at 350°C. X-ray examination showed no marked general preferred orientation in the resulting rods. The grain structure typical of the two rods is shown in the micrograph of Fig. 4." It was found to be virtually im- possible to get an unambiguous measure of the absolute grain size in the two annealed rods because of the profusion of annealing twins and the lack of regularity of the grain boundaries. However, counts of the number of boundaries intersected per unit length along a random line on a polished section, making a correction for the proportion of boundaries (about half) estimated to be twin boundaries, gave a figure of about 0.015 mm for the average grain diameter. The grain size of the rod from lot A was about 5 pct smaller than that from lot B. The rods were cut into 1 ft long bars and these deformed in tension at room temperature to various total elongations in the range 10.8 to 39.5 pct. A strain rate of 1 pct per min was used. The deformed bars were then stored in a dry ice chest until such time as samples were to be cut from them. Five bars deformed as indicated in Table I were used for the subsequent tests. In all cases, all the calorimeter.

Jan 1, 1956

By George R. St. Pierre, John Chipman

METALLURGISTS have been studying the chem-ical behavior of sulfur in steelmaking for many years in order to have a better control of the sulfur content of finished steel. During the refining period in the open hearth, molten steel is separated from a gas phase by molten slag. Chemical reactions occur principally at the slag-metal interface and at the slag-gas interface. A need for physical-chemical investigations of reactions between sulfur-bearing gases and steelmaking slags was recognized some time ago.'.' From the early work, it can be qualitatively concluded that increased sulfur content and low partial pressure of oxygen in the gas phase favor the passage of sulfur from gas to slag. Using radioactive sulfur S Koch and Fink' have demonstrated the rapid rate of exchange of sulfur between gas and slag in an open hearth furnace. Gurry and Darken and Darken and Shields (as reported by Derge and Marshall') have equilibrated lime-iron oxide slags with SO—O2 gas mixtures. The major conclusion from the reported results is that sulfur content increases with increasing lime content in lime-iron oxide slags equilibrated with a gas of high oxygen pressure (10-2). The data were interpreted as indicating the presence of SO, and S,O, ions. Richardson and Fincham' have conducted the most extensive experimental study of sulfur equilibria between gas and slag. Their results confirmed many of the conclusions drawn from calculations of Richardson" and Withers. Richardson and Fincham's data fitted very well into the sulfur scheme represented by the reactions 1/2 s2 (g) + (0) melt - 1/202(g)+ (S) melt [II 1/2 S, (g) + 3/2 O (g) + (0) melt - (SO,) melt. [2] At oxygen pressures greater than 10 to 10 they found that reaction Eq. 2 was predominant while reaction Eq. 1 was controlling at oxygen pressures less than 10." to 10.". The slag compositions and gas mixtures used in their investigations were different from those used in the present study. Wherever possible, comparison has been made between their results and these, and agreement is excellent. It is evident that the distribution of sulfur between slag and gas depends upon the oxygen pressure of the gas. In FeO slags, a change in oxygen pressure produces a change in ferric oxide content, and a knowledge of this equilibrium is a prerequisite to studies of sulfur distribution. The data are found in the work of Darken and Gurry" on the FeO system and the more recent experiments of Gurry and Darken" and of Larson and Chipman" on FeO slags containing lime and silica. The effect of oxygen pressure on the ratio Fe /(Fe" + Fe ), the so-called j-ratio, reported by these investigators will be used in interpreting the results which follow. Experimental Method The purpose of the experimental program was to determine the equilibrium sulfur content in slags exposed to gases of known oxygen and sulfur pres- sures. The slag compositions selected for study were from the lime-silica-iron oxide system. Additions of magnesia were made to some of the slags. Apparatus—The apparatus used by Larson and Chipman was modified slightly to accommodate the addition of SO2 to the gas mixtures. As in their work, slag samples of 0.5 to 2.0 g were held at temperature (lcc) in platinum crucibles under a steady stream of gas, 100 to 200 ml per min, for several hours and then rapidly lowered to the bottom of the furnace where they were quenched in mercury. Preparation and Analysis of Gas Mixtures—Mixtures of SO,-CO were prepared from Virginia Smelting Co. Extra Dry liquid SO, and Pure Co. CO,. After removing traces of water vapor with an-hydrone, the CO, was passed over graphite at 1200°C, at which temperature the conversion to

Jan 1, 1957

ZAY JEFFRIES,* Cleveland, Ohio (written discussion?).-The microscope has, indeed, proved a mighty tool in the study of the structures of substances. It is limited in its resolving power to the wave length of the light used for illumination. A little in resolving power can be gained by using ultraviolet rays, which can only be detected by the photographic plate. Even the highest powered microscope only permits the study of aggregates of millions of atoms. The x-ray spectrometer, on the other hand, makes it possible to study the positions of the atoms in a crystal. The positions of the atoms in over fifty crystals have now been ascertained. But in amorphous substances the x-ray spectrometer is only able to tell us that the atoms seem to have no regular arrangement; the actual arrangement and method of grouping is still a mystery. In most perfectly formed crystals and in so-called "grains" in metals, the x-ray spectrometer teaches us that colloids seem to play no role inasmuch as the atoms are arranged in regular layers rather than in random clusters. In the boundary region between crystalline grains of like as well as unlike substances and in amorphous substances like glass, it seems probable that the random clusters, or colloids, play an important role. There still remains the application of wave lengths connecting the ultraviolet and x-rays both by direct reflection or diffraction and by the ultramicroscope. In the study of substances like glass, for example, it may be possible to identify the clusters or molecules by one wave length and to study the positions of the atoms in a cluster by using a smaller wave length. Any light that can be thrown on this important unknown subject and its relation to the properties of substances is therefore very welcome, and Mr. Alexander's paper is so written as to stimulate thought and experimentation in this direction. JEROME ALEXANDER (author's reply to discussion ?).-Col. Bancroft states' that in the case of alloys, the mass is always crystalline. While this generally may be so in the case of alloys, as ordinarily met with, before the alloy reaches this state or condition, its constituent particles must be in a still more finely dispersed state. In alloys, the speed' of transition between the finely dispersed state where the phases are amorphous, and the crystalline state where the phases are of known composi-

Jan 5, 1919

By A. U. Seybolt

The solubility of oxygen in a iron has been determined in the range between 700° and 900°C. The solubility is a function of temperature and varies from about 0.008 pct oxygen at 700°C to atureandabout 0.03 pct at 900°C. The heat of solution is approximately +15,500 cal per mol. AS pointed out in a recent paper by Kitchener et al.,1 there has been a lack of agreement among many investigators even as to the order of magnitude of the solid solubility of oxygen in the various forms of iron. This lack of agreement is attributable in large part to the difficulties in the determination of a small oxygen solubility; but because the problem has remained so long unsettled, it also indicates a lack of interest which is rather surprising when the demonstrated importance of small amounts of soluble nonmetallic impurities in iron is considered. The work of Kitchener et al. apparently leaves the solubility of oxygen in iron in a satisfactory state, but no attempt was made to investigate the solubility in a iron. The solubility of oxygen in a iron is actually of greater interest, since it is in this form that iron and mild steels are employed ordinarily. That the effect of oxygen in iron is of more than theoretical interest has been well established by Fast,' and more recently by Rees and Hopkins," who demonstrated that oxygen in the range between 0.0008 and 0.27 wt pct has a pronounced effect upon the mechanical properties. Previous Work and Methods Used To report in detail the literature relating to the solubility of oxygen in a iron would require an inordinate amount of space. For those interested in reviewing this work, a bibliography4-13 of the more significant papers is appended. In general, two methods of studying this problem have been used. One is the gas-metal equilibrium method where the H2O-H2-Fe or the CO2-CO-Fe equilibria have been used. The other is the more direct approach of the oxidation of thin strips of pure iron by packing in mill scale or by air or gaseous oxygen at some desired temperature. In this method oxygen is allowed to oxidize the surface and then to diffuse inward until saturation is obtained. In the gas-metal equilibrium method the oxygen dissolved in solid iron at a given temperature is proportional to the ratio of the water vapor-hydrogen pressures or the CO2-CO pressures over the sample for small ratio values. If the ratio becomes higher than a critical value, then an oxide phase makes its appearance (the solution becomes supersaturated). In principle, it is possible to use a series of H2O/H2 or CO2/CO ratios and to find by analysis the corresponding amounts of oxygen in solid solution at constant temperature. At the point where a very small increase in the gas ratio (increase in oxidizing powder) produces a large increase in oxygen content, the solid solubility limit is reached. Alternately, if the critical ratio is known, it is possible to use the procedure of Kitchener et al.1 and to use a ratio which is near but below the critical one. The solubility corresponding to this lower ratio will not be the saturation solubility at the temperature employed, but the saturation solubility can be calculated by multiplying the measured solubility by the critical ratio over the ratio used. However, in the case where oxygen gas is the oxidizing medium, the saturation solubility is not a function of pressure, providing the pressure exceeds the dissociation pressure of FeO in equilibrium with iron. This is 1.2x10-16 mm at 800 °C, according to Dushman." As pointed out by Darken17 in discussing the FeO phase diagram, most of the possible errors tend to yield high values of oxygen solubility. For example, one circumstance which evidently caused the reporting of many high values was the use of finely divided or powdered iron in the gas equilibrium method. Because of the large surface area of such a sample, and the likelihood of some surface contamination if only by exposure to air, the results tended to be high. The direct oxidation method which was used in this work has the advantage in that it is simple and direct, but it suffers from one disadvantage: equilibrium can only be approached from the low oxygen side. The important factors to be kept under control are the following: 1—use of high purity iron to avoid internal oxidation (oxidation of readily

Jan 1, 1955

By AIME AIME

BUFFALO, Queen City of the Lakes, singularly accessible by land, water and air, will be the mecca for metallurgists throughout the United States and Canada during the week of the National Metal Congress, Oct. 3 to 7. Headquarters during the National Metal Congress will be the Hotel Statler and there on Wednesday and Thursday, Oct. 5 and 6, the Institute of Metals and Iron and Steel Divisions, A.I.M.E., will hold a series of technical sessions, the annual Science Lecture, a dinner and executive committee meetings. The American Society for Steel Treating, American Welding Society, Production Division of the Society of Automotive Engineers, the Iron and Steel and Machine Shop Practice Divisions of the American Society of Mechanical Engineers, the Wire Association and the American Drop Forging Institute will present a carefully planned program extending throughout the week.\

Jan 1, 1932

By C. Dinis da Gama

In order to reduce the complexity of mechanisms influencing rock. fragmentation by blasting a simulation approach is proposed, using the capabilities of microcomputer interactive graphics. Situations involving cratering end bench blasting are simulated, and both jointed and intact rocks can be subjected to explosive action, taking into consideration its breakage mechanisms. Size analysis curves relating rock distribution before and after the blasts are determined and compared with field data.

Jan 1, 1984

By John L. Boardman

BECAUSE of the attention that has re¬cently been given to the health and safety of miners by various organizations such as the A.I.M.E., The American Congress, Mining Section, National Safety Council, as well as the Bureau of Mines and various state mining departments, your committee on health and safety deemed it best to call attention this year to the mine-accident cause that is by far the most important; namely, injuries due to falls of ground, rock, roof and coal. Each of several members of the committee contributed a brief outline of the importance of this accident cause in his district. While these papers were brief, it would require too much time and space to give them in full, therefore we present an outline of each and summation of all. REPORT OF M. D. COOPER, HILLMAN COAL AND COKE CO. M. D. Cooper, Division superintendent, Hillman Coal and Coke Co., Pittsburgh, Pa., contributed the following: During the period from 1930 to 1939, accidents from falls of roof in bituminous mines average 54.3 per cent of all accidents. In mechanized mining, there is a tendency toward reduction in this class of accidents because the operator of the machine is usually at a distance of 10 to 20 ft. from the face, whereas. in hand loading the miner is close to the face during most of the shift. No doubt the use of aluminum and light steel beams supported at regular intervals by jacks, a common practice in mechanical mining, has contributed to the favorable record so far developed. REPORT OF M. H. FIES, DE BARDELEBEN COAL CORPORATION Milton H. Fies, Vice-President, DeBardeleben Coal Corporation, Birmingham, Ala., says: With reference to the types of mining, it is suggested that a clear understanding be had as to the character and thickness of the directly overlying strata, with especial consideration to the strength and in some cases an analysis of it. In coal mining, generally speaking, overlying strata higher in silica than others is stronger. In changing from narrow to wide places, the procedure should be experimental, both as to the width and depth of places and as to the nature of the necessary timbering. Since most of the accidents in coal mining particularly are due to falls of roof and coal, this phase of mining should be attacked with vigor. There is no substitute for discipline and, in this connection, under present conditions it is important that cooperation by the labor organizations be sought and that a spirit of fairness prevail. Frequent and thorough inspection of all active working places should be made.

Jan 1, 1941

By B. Prof. Silliman

THE experiments detailed by Dr. Hunt,* having demonstrated the fact that the copper contained in the "clay ore" of Jones's Mine, was rendered completely soluble in the bath of ferrous chloride, used in the Hunt and Douglas process, after heating in contact with carbonaceous matter in a close vessel, I set myself to devise a form of muffle furnace adapted to the treatment of large quantities of these and similar ores by a continuous process. The result is shown in the diagrams on Plate X, reduced from the working drawings, after which this furnace was built early in 1876, at Phoenixville, by the Chemical Copper Company on their works at this place. The peculiar character of this ore determined the form, dimensions, and position, with reference to charging and discharging of these muffles. The ore arrived from the mine with from 20 to 25 per cent. of moisture, and when dried at 212° F., or more slowly at lower temperature, it falls to a light incoherent powder, with occasional lumps of undecomposed rock. In this condition it is readily mingled with coal-dust or any like reducing agent, and requires no other preparation for the muffle than the use of the shovel, to mix it well with the reducing agent. As it is a remarkably good non-conductor of heat, it was obvious that the mass, to be heated through in a reasonable time, must not be too thick, while the weight of the mass must be sustained in a way to avoid undue strain upon the walls of the muffle. These walls must be as thin as practicable, to favor the more rapid transmission of heat, and must, therefore, be so con¬structed as to admit of being stayed on the sides at frequent intervals to resist the lateral thrust of the very mobile mass of pulverulent ore, which, for obvious reasons, must be charged at the top and drawn from the bottom of each chamber. These considerations led to the form adopted, viz., two vertical muffles, standing upon very strong bridge tiles, seen in longitudinal section, on the line E, F, and in plan in Fig. 3, on the same plane. (Plate X.) The vertical section of the muffle is seen in Fig. 4, drawn in the plane G, H, of the longitudinal section, Fig. 6, which is the key to all sections. The walls of the muffles are built of the best firebrick, very care- * See paper by Dr. Hunt, page 325.

Jan 1, 1876

By William L. Batt

IT IS becoming increasingly evident to management that it has other obligations than merely to earn dividends for stockholders. The head of one of America's largest organizations has stated it in these words: "There rests upon them a far broader responsibility than the mere production of goods and services, or solely the interests of their stockholders. They must assume the important obligation, through proper policy, of attuning industry to a rapidly changing world, from social as well as economic standpoints." Stockholders might as well reconcile themselves, therefore, to the fact that management cannot always put their interests first in the obligation of business enterprise: and that the legitimate requirements of customers and employees have acquired a new significance which must be recognized if the business of today is to prosper.

Jan 1, 1938

By John L. Boardman

BECAUSE of the attention that has recently been given to the health and safety of miners by various organizations such as the A.I.M.E., The American Congress, Mining Section, National Safety Council, as well as the Bureau of Mines and various state mining departments, your committee on health and safety deemed it best to call attention this year to the mine-accident cause that is by far the most important; namely, injuries due to falls of ground, rock, roof and coal. Each of several members of the committee contributed a brief outline of the importance of this accident cause in his district. While these papers were brief, it would require too much time and space to give them in full, therefore we present an outline of each and summation of all. REPORT OF M. D. COOPER, HILLMAN COAL AND COKE CO. M. D. Cooper, Division superintendent, Hillman Coal and Coke Co., Pittsburgh, Pa., contributed the following: During the period from 1930 to 1939. accidents from falls of roof in bituminous mines average 54.3 per cent of all accidents. In mechanized mining, there is a tendency toward reduction in this class of accidents because the operator of the machine is usually at a distance of 10 to 20 ft. from the face, whereas in hand loading the miner is close to the face during most of the shift. No doubt the use of aluminum and light steel beams supported at regular intervals by jacks, a common practice in mechanical mining, has contributed to the favorable record so far developed. REPORT OF M. H. FIES, DE BARDELEBEN COAL CORPORATION Milton H. Fies, Vice-President, DeBardeleben Coal Corporation, Birmingham, Ala., says: With reference to the types of mining, it is suggested that a clear understanding be had as to the character and thickness of the directly overlying strata, with especial consideration to the strength and in some cases an analysis of it. In coal mining, generally speaking, overlying strata higher in silica than others is stronger. In changing from narrow to wide places, the procedure should be experimental, both as to the width and depth of places and as to the nature of the necessary timbering. Since most of the accidents in coal mining particularly are due to falls of roof and coal, this phase of mining should be attacked with vigor There is no substitute for discipline and, in this connection, under present conditions it is important that cooperation by the labor organizations be sought and that a spirit of fairness prevail. Frequent and thorough inspection of all active working places should be made.

Jan 1, 1941