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By K. Fallenius

Since 1970 a new series of pneumo-mechanical flotation machines has been developed by Outokumpu Oy. The cells have a completely new type of mechanism based on a recently-developed theory of conditions necessary for dispersion of large amounts of air. The mechanism was developed in 3 cu m cells and scaled to 16 cu m cells. Rotor and stator description, scale-up theory, and practical experience with the 16 cu m cell are presented.

Jan 1, 1976

By J. A. Herbst, K. Rajamani, M. Siddique

This paper presents an investigation of the accuracy of population balance model predictions for ball mill scale-up. Experiments performed in 25.4 x 29.2 cm (10 x 11.5) batch mill are used to estimate linear grinding rate parameters that, in turn are scaled according to specific power draft to predict performance in 381 x 292 mm (15 x 11.5 in.) and 762 x 457 mm (30 x 18 in.) batch and continuous ball mills, respectively. Results are presented for wet and dry grinding of two homogeneous solids, limestone (soft) and quartz (hard), and one heterogeneous solid, a complex molybdenite ore. In all cases good agreement between predicted and experimental product size distributions was obtained.

Jan 1, 1983

By J. J. Marcus

Mineral industry decision-makers are frequently required to select between competing equipment. Various criteria and methods are currently being used, and this writer would like to suggest a method recently tested on two large power shovels in an open pit mine. An initial examination of both shovel A and shovel B indicated that the latter should give the best overall results. since: 1) It swings 13% faster; 2) it carries a dipper with 23%: greater capacity; 3) purchase price is 8.6% lower; 4) shovel weight is 12.5% greater; 5) it has considerably greater bail pull under most operating conditions; 6) the electric controls are of a more modern design. However, shovel B has half the service life. With these points in mind, shovel A was selected by The Buckingham Method, an operations research technique.

Jan 9, 1965

By A. A. Rauth

In this paper, the author derives a series of formulas from basic principles and illustrates the application of these formulas to practical grinding charge problems. The paper establishes the nearly proportional relationship of mill power to charge level and shows how this relationship can be used to advantage in the design, manufacture and operation of grinding mills. The procedures outlined offer a rapid means of anticipating the power requirements for a given charge or determining makeup charges for a given power reading. The theories which have been developed concerning the dynamics of grinding have been motivated largely by the desire to derive workable formulas for the accurate determination of grinding mill power. This accurate determination has always been handicapped by the large number of variables to be considered, some of which are mill diameter, length, speed, liner design, grinding charge and material density, volumetric mill loading, internal friction, and charge size and gradation. In efforts to determine mill power, attempts have been made to utilize torque concepts. The formulas derived consider the grinding mass as a rigid body and utilize factors that are based on empirical data so that the movement of the charge within the mill is compensated for. These formulas are of principal interest to the mill designer since he is charged with the responsibility of analyzing all of the variables and from them predicting a mill size and a motor size which are compatible both with each other and with the grinding job for which they were intended. The mill operator, on the other hand, has an entirely different problem. The mill dimensions are already established and so is the driving motor. The operator's main concern is to obtain maximum performance from the mill he already has. For him, the many variables which perplex the mill designer are fixed values. Mill diameter, length and speed are set and, to a large extent, so are the conditions inside the mill from which the torque formula advocates derive their empirical data. It is conceivable that if the major mill dimensions which affect power demand are held constant, and if the variables influencing empirical factors are held fairly constant, as they are in an operating mill, then the only major variable remaining which affects power is the level of the charge itself. Under this condition.

Jan 1, 1970

By Donald W. Petrasek

The effects of selected alloying elements on the elevated-temperature tensile properties of copper alloy -tungsten fiber reinforced composites were invcstigated. A cornparison of the elevated-temperature tensile properties of copper alloy - tungsten fiber reinforced composites, representing soluble systems. was made with copper - tungsten fiber reinforced composites, representing a mutually insoluble system. A linear relation between tensile strength and volume percent fiber content existed at elevated temperatures for all the systenzs investigated. The copper alloy composites were weaker in tension at high volume percent fiber contents than copper composites in which alloying with the fiber did not occur. The tensile strength of the alloyed tungsten fiber decreased with increasing penetration of the alloying element into Ihe tungsten fiber. THE technique of combining strong fibers with relatively weak matrix materials so that the fibers are load-carrying members has been utilized for many years in the reinforcement of plastics with glass fibers. This type of strengthening is currently being extended to include the reinforcement of metals with metallic fibers. Investigations of the room-temperature tensile properties of metal-fiber-reinforced metallic composites have been numerous,'-" but the study of tensile properties at elevated temperatures has been limited. In previous work done at the Lewis Research Center' composites consisting of mutually insoluble constituents were investigated. Composites were made of copper reinforced with uniaxially oriented tungsten fibers. The stress-strain behavior and tensile properties of the composites were related to the tensile properties of the base materials. The tensile strength of the composite was directly proportional to the volume percent of tungsten fiber present, and the full strength of the fiber was realized. Few metal fiber - metal matrix systems exist that are mutually insoluble, and those that do exist are not generally practical. An extension of this work was an

Jan 1, 1967

By Charles L. Thomas

A novel, highly sensitive, and reproducible nzetlzod for the determination of hydrogen in solid materials is presented. The procedure requires equilibration of the specimen with hydrogen gas, rapid quenching, and hot vacuum extraction of the dissolved gas with subse-quent quantitative analysis by mass spectroscopy. Good linearity is obtained for the Arrl~enius plots of the investigated metals. The advantages in the use of this method over that of Sieverts aye discussed. The solubility data for copper are in reasonable agveewzent with a considerable number of other inuestigations, wllile those fov silver are considerably lower than previously reported. The first known solubility data for gold are presented. Solubility equations and heats of MUCH of the data which are available on the solubility of hydrogen in various metals and alloys have been obtained by the classical Sieverts method.' The method involves the measurement of a decrease in pressure of a gas in a calibrated system, and the calculated contraction in volume is attributed to the solubility of the gas in the metal sample. The procedure requires several corrections, such as the solubility of the gas in the container walls and the diffusion of the gas through these walls, as noted by Steacie and .Johnson2 and others. In addition, errors may be incurred due to reactions between metal surface impurities, such as oxides, and the saturating gas. The precise calibration of the measuring system where large thermal gradients exist can present additional difficulties. Also, accurate volumetric measurements of small quantities of gas are difficult. Many of the objections to the Sieverts method were overcome on solid materials by Ransley and ~eufeld,~ who first saturated the metal with hydrogen and performed a subsequent extraction and measurement of the gas by chemical means. Eichenauer and pebler4 and Eichenauer, Kiinzig, and pebler5 measured the diffusion coefficient and solubility by following the degasification of a sample as a function of a rate of increase in pressure in a previously evacuated system. Here again, however, the procedure involves many of the corrections of the Sie-verts method. The present investigation deals with the solubility of hydrogen in solid copper, silver, and gold by a technique which eliminates many of the aforementioned corrections and possible errors. This procedure requires equilibration of the specimen with gas, rapid quenching, and hot vacuum extraction of the dissolved gas with subsequent quantitative analysis by mass spectroscopy. EXPERIMENTAL Two completely separate systems were employed to accomplish first, the equilibrium saturation of the sample and second, the extraction of the dissolved gas. Saturation Apparatus. The saturation apparatus, illustrated in Fig. l, consisted of a vertically mounted quartz tube with a three-way valve for vacuum or hydrogen near the top and an outlet near the bottom leading to a butyl phthalate seal. The bottom end of the tube was terminated with a joint accommodating an O-ring sealed "Asco Stirring Gland" (The Emil Greiner Co.). This gland facilitated movement of the thermocouple without introduction of air into the system. The upper portion of the tube (above the furnace) was water-jacketed. A Welsh 1405-B mechanical pump provided the necessary system evacu-

Jan 1, 1968

By J. M. Cabal, M. Chica Olmo, J. P. Laille

One of the main goals of a simulation of a coal deposit mining is to predict a series of parameters considered by the miner to be useful, e.g. ash content, sulphur content, seam thickness etc). The idea is to simulate different ways of mining a multi-seam brown coal deposit (the Mine Puentes de Garcia Rodriguez deposit, ENDESA, Spain ), which is exploited by several bucket-wheel-excavators (BWE) . Two mining models are used: a geostatistical model which provides a numerical way of re- presenting the three-dimensional ore-body, then a deterministic model, consisting of simulating the technical aspects of the mining. The main purpose of this simulation is to show how the mining operations can be reproduced using these two techniques.

Jan 1, 1983

JOHN.B. HASTINGS, Los Angeles, Cal. (written discussion).-This paper reminds me that when I had an option on a Nevada mine, where the only orebodies assayed $4 gold, I went to San Francisco to learn the cost of putting broken ore in a 25-ft, vein on the mine cars, and sought Mr. Alfred Wartenweiler, who said "There is not a mine in California that can tell what it costs to move ore in the stopes." When building small mills in the mountains, and with only 30 or 40 employees, by entering in a log at night the work performed by each man, I have been able to plot the costs with the accuracy shown in this paper, and very good discipline it is. Cost of new construction and repairs is carefully kept by most companies, and is compiled after completion; probably the outlay of labor and material in pieces of work sufficiently important to call for blueprints is estimated beforehand, but numberless odd jobs of construction and repairs are so itemized. . Might it not be worth while, at a large plant, to have these smaller daily tasks described in advance in a central repair office, and then let inspectors look over the job, report time and material needed, and enter it in sufficient detail in proper ledgers, the men then being sent to accomplish it, and reporting when finished? The forecasts would soon be made quickly and correctly and would give the head mechanic, carpenter, and electrician easy supervision of their men, and the results could be seen at a glance by the managers.

Jan 4, 1918

By J. F. Martin, J. E. Friedline, L. M. Melnick, G. E. Pellissier

A method has been developed for determining gases in steel in which the gases are extracted by vacuum fusion and analyzed by mass spectrometry. This method is especially applicable for determining small amounts of oxygen and nitrogen. The lower limit of detection for both oxygen and nitrogen is 0.0001 pct with an average deviation of about 0.0001 pct for oxygen and 0.00008 pct for nitrogen. Hydrogen analyses by this method are in good agreement with analyses by vacuum tin-fusion. A complete analysis of all gases extracted from a steel sample can be accomplished in 40 min. It has long been known that certain of the gaseous elements exert particular effects on the physical and mechanical properties of steel. With the recent advent of new experimental steelmaking practices it is now possible to obtain steels with extremely low contents of such elements as oxygen and nitrogen. Present methods for determining these two gases are of insufficient sensitivity as applied to steels made by these newer practices, and therefore a new technique was considered necessary. A review of the literature showed that the conventional vacuum-fusion method1 was the procedure most suitable for modification to obtain a sensitive method for determining the gaseous elements present in steel simultaneously. However, for trace amounts of gases it is impractical to increase the sample size because of the physical limitations of the apparatus and the increased degassing time which would be necessary. Also, when only one of the desired gases is present in trace amounts, quantitative separation by conventional vacuum fusion is almost impossible. Since small analytical mass spectrometers are now commercially available, it was decided to use this instrument in conjunction with conventional vacuum fusion for both qualitative examination and quantitative determinations of the gaseous elements in steel. This technique has already been used with success for the analysis of copper and lanthanum.2"4 APPARATUS A vacuum-fusion unit was first designed and built, Fig. 1. This unit was designed especially for the determination of small amounts of nitrogen and/or oxygen in steel since an acceptable method (vacuum tin-fusion)5 was already in use for the determination of hydrogen in steel. The vacuum system was con- structed of Pyrex glass throughout. Mercury check valves were used in place of stopcocks in the high-vacuum section of the system. Ferromagnetic samples are normally introduced into the vacuum system through a mercury lift. In case of a break in the lift, the mercury is prevented from entering the furnace by a self-locking, mercury safety check valve, Fig. 2. This check valve, developed at our laboratory, is a modified T/S ball-and-socket joint placed in the sample inlet system between the mercury and the furnace. A sudden entry of mercury or air pushes this valve into the closed position, completely blocking the top of the mercury lift. The check valve is held in the closed position by the vacuum of the apparatus. A separate entrance tube also was placed in the system, so that samples which would amalgamate with mercury, or which are nonmagnetic, could be introduced into the furnace. A slightly modified Guldner-Beach furnace is used in this system.8 The optical flat was connected to the system by a ground-glass joint to facilitate cleaning, a quartz delivery tube was substituted for Pyrex, and the crucible was used uncovered. Fusion takes place in a high-purity graphite crucible insulated by — 200-mesh high-purity graphite powder. The crucible set (crucible and funnel) is suspended in a quartz crucible. The furnace envelope and the sample inlet system are exhausted by 2 single-stage, mercury-diffusion pumps in series. The first of these is a high-speed pump, which will work only with a very low backing pressure. This pump is used to exhaust the gases from the furnace as rapidly as possible. The second mercury-diffusion pump is used as a backing pump for the first; the capacity of this pump is much lower. However, it will work efficiently against a back pressure of 3 mm of mercury. To assure positive pumping, a modified Naughton and Uhlig condenser7 is used. With the use of proper valving the second pump is also used as a circulation pump in the catalyst system.

Jan 1, 1959

By J. K. Edgar

FOR a number of years the production and use of super-purity aluminum (better than 99.99 pct) has been steadily increasing. High-grade lots of such aluminum show certain outstanding characteristics not found in lower grades containing principally silicon, iron and copper as impurities. One such characteristic is the so-called "self annealing," that is, the recrystallization of the heavily cold worked metal at room temperature.' Interest therefore is aroused as to the effects of the impurities. It is well known that the amounts of silicon and copper which occur in aluminum of better than 99.95 pct are completely soluble, at least at elevated temperatures (above 200°C). Iron, on the other hand, is known to be fairly insoluble in solid aluminum. Thus, a knowledge of the limits of this solubility would be of considerable use in studying the characteristics of the high purity metal. All investigators have agreed that iron has very low solubility in solid aluminum. Rosenhain, Archbutt and Hanson2 reported traces of an aluminum-iron phase in the "purest samples of aluminum obtainable." Gwyer and Phillips3 reported that an iron constituent was visible under the microscope in metal containing ".0088 per cent iron." Roth1 found that in the solid state the solubility of iron in high purity aluminum was 0.01, 0.01, 0.017 and 0.022 pct at 225, 320, 500 and 600°C respectively. Dix5 working with alloys containing less than 0.03 pct impurities, concluded from microscopic and chemical analyses of eutectic areas that the eutectic composition was close to 1.7 pct iron. Dix placed the eutectic temperature at 655°C'. Archer and Fink,6 using high purity aluminum-iron alloys, found that the hypoeutectic liquidus intersects the eutectic horizontal at 1.7 pct. This is in fair agreement with the investigation of the aluminum-iron system by Gwyer and Phillips who placed the eutectic at 1.89 pct iron with a freezing point of 653° PREPARATION AND CHEMICAL ANALYSIS OF ALLOYS Electrolytically refined aluminum (99.991 pct aluminum) and a high purity aluminum-iron alloy (11.45 pct iron) were used in the preparation of the alloys for this investigation. To aid in controlling the iron content of the experimental alloys, an alloy of lower iron content was prepared first from these materials. The high purity aluminum was melted and heated to about 700°C in a plumbago crucible coated with alundum cement and the aluminum-iron alloy was then added. The alloy was thoroughly stirred, fluxed and skimmed and then chill-cast into notch bars. The analyses of the three materials are given in Table I. The alloys for the determination of the solid solubility of iron in aluminum were prepared by melting 600 g total of the aluminum plus the required quantity of the aluminum-iron alloy (No. 92531). These

Jan 1, 1948

By Kenelm C. Appleyard

In introducing to an American audience a description of the work done in dry coal separation in England and in Europe generally, it is perhaps desirable to give a short history of the development outside the United States of the particular processes with which the author is connected, and perhaps to stress a little the differences in the nature of the conditions to be faced. England actually presents one set of problems and the Continent of Europe another, since the character of the coals to be treated is entirely dissimilar, and the attitude of the coal industries towards coal preparation is also dissimilar. England for generations has been working by hand good seams of clean coal of the highest possible quality and has not felt any pressing need to clean its coal. Most Continental countries, however, especially in Central and Western Europe, have been working friable and often very dirty coals for so long that a washery is accepted as a part of the normal equipment of a colliery, with the result that the art of wet washing has reached a high state of perfection, particularly in Belgium and Germany. The advent of machine mining has intensified the problems to be faced in all countries, and in England has been coupled with the working out of the best seams in the older coal fields, thus bringing about the necessity of working thinner and dirtier seams with resultant difficulties as regards marketing the products, while Poland, with clean and well prepared coal, has in recent years been attacking established British markets in Scandinavia. In recent years, therefore, interest in coal preparation has been steadily gaining ground in England, although it has not yet reached Continental dimensions. Broadly speaking, the differences in preparation problems between England and the Continent boil themselves down to one of size. In England, for example, with the exception of the Kent coal field, the proportion of coal of a size less than ? in. to the coal less than 2 in. is very much less than on the Continent, and since the principal difficulties in dry cleaning lie in the fines it is easier to produce good figures on

Jan 1, 1931

By M. Muskat, H. G. Botset

Any information that will increase the accuracy of our knowledge of the conditions prevailing in petroleum reservoirs should be of direct value in the determination of the proper operating technique as well as in the estimation of reserves and of ultimate production. The obvious method of obtaining this information is by studying a sample of the reservoir rock and its contents. In any such study, the problem of primary importance and maximum difficulty is that of getting the core to the surface in such a manner that its original fluid content is undisturbed, which has so far proved to be an impossible task. Though it might be rash to say this will never be done, it is certainly safe to assume that a, method for the recovery of a core at the surface in its undisturbed original state may not be developed in the immediate future, and certainly will not be forthcoming without a great deal of costly experimentation. Therefore any information that may be obtained that will help to correlate the state of a core (its fluid saturation) at the surface with its condition at the time it was drilled should be of value to the petroleum industry. The experiments described in this paper were undertaken with the purpose of determining, if possible, any relationship that might exist between the saturation of a core at the surface and its original fluid content. No consideration has been given to the question of contamination by penetration of drilling water, since this problem has been extensively studied by other investigators.1-3 Furthermore, it was regarded as outside the scope of these experiments, which were concerned only with the effect of pressure reduction upon the liquid content of cores. In an experimental study of this sort involving a large number of variables, accurate control of all factors is very important. The essential and obvious procedure is to vary systematically one factor or condition while keeping all the others constant, which necessarily involves a rather protracted and sometimes tedious experimental program. The procedure adopted was essentially very simple, and consisted merely in filling a given core with fluid (gas and oil, gas and water, or

Jan 1, 1939

By E. C. Carris

THE particular field of application of machines utilizing air currents as the primary separating medium is in the cleaning of the fine sizes of bituminous coal. Approximately 12,000,000 tons of bituminous coal were cleaned by air machines during 1940.They have not found any application for cleaning anthracite. Since the development and introduction of the first successful commercial pneumatic oscillating machine for cleaning bituminous coal in 1916, by the Sutton, Steele and Steele Co., Dallas, Texas, and the American Coal Cleaning Corporation, formerly of Welch, W. Va., four other successful pneumatic coal-cleaning machines have been developed and introduced to the American coal-mining industry: 1. Peale Davis: "Pneumo-Gravity" machine, 1924. 2. Arms "Concentrator," oscillating table, 1924. 3. Hey1 and Patterson oscillating table, 1927. 4. "Stump Air-Flow," pulsating air jig, 1932. Out of these five developments only the Sutton, Steele and Steele, or American Oscillating, and the Stump Air-Flow Jig remain on the market. They are the predominating pneumatic coal-cleaning machines in use in the United States. HISTORY OF AMERICAX TYPE SEPARATOR The first successful American machine, the CJ table (Fig. 1) was developed by the Sutton, Steele and Steele Co. The SJ table was the first standard model designed specifically for the cleaning of coal. It was installed in the original Crane Creek plant, owned and operated by the American Coal Co. at McComas, West Virginia. This plant was designed by The Roberts and Schaefer Co., Chicago, Ill., working in cooperation with the American Coal Cleaning Corporation, which had taken over the patent rights and sale of the pneumatic separators. Eight machines were installed in this plant. They were known as the type SJ. They were 60 by 84 in., the short dimension being the width of

Jan 1, 1943

By Richard P. Schoemaker

Introduction In underground mining operations the effects of economic and mechanical factors on costs and profits can readily be appreciated and can perhaps be expressed in exact figures and percentages. Less apparent, but frequently more important, is the influence of physical stress. Stress causes failure of supports, collapse of openings, rockbursts, and other damage which directly affects the costs of maintenance, and also to a certain extent the accident rate. Stress can, however, if properly directed, be an aid to mining operations. The caving methods in metal mining and the long-wall method in coal mining are well-known examples. In large-scale mining operations it is almost impossible to neglect stress-control. A better understanding of the mechanism of rock pressure and the application of its principles to practical mining will inevitably lead to a reduction in operating costs. Many theories have been advanced to give the mining engineer a practical outline for stress-control but, although today most experts agree upon the principles of stress distribution around underground openings, there is still no generally accepted theory that explains all phenomena. The main reasons for this incomplete understanding of the problem are the lack of accurate knowledge of the physical properties of rocks under field conditions, and the great complexity of these conditions due to in-homogeneity of the rock, stratification, tectonic disturbances, and many other unknown factors. The research on the rock pressure problems has, however, yielded some valuable facts which, expressed in practical terms, and adapted to local conditions, may become a valuable aid for mining operations. The purpose of this paper is to give a review of the most important accomplishments of this research with respect to the stress phenomena around small underground openings, such as tunnels and shafts, so as to arrive at an outline of the problem as it stands today. Special emphasis is placed on a new theory by the German mining engineer, Rudolf Fenner, which has never before been published or discussed in English. The Pressure Dome Theory The formation of a dome-shaped space around underground openings is well known from field observations. When openings are made in rock under stress, the rock in the top of the openings will often fail, and caving will continue until the openings have assumed a dome-shaped form, after which equilibrium apparently is re-established. The oldest theory which attempted to explain the phenomenon is the "beam" theory, which postulates that the hanging wall consists of stratified measures that behave as independent beams with fixed ends and a uniformly distributed load. When failure of the beam occurs, inward shearing at the ends will cause the formation of a dome-shaped space. The pressure dome theory, which more or less evolved from the beam theory, merely

Jan 1, 1949

By M. T. Hepworth, A. K. Stewart

Iron containing 0.1 pct A1 and -0.9 pct P by weight was internally oxidized in the temperature range 900° to 1300° C, where the bcc structure is stabilized by phosphorous. By measuring the depth of penetration of oxygen with time in an internally oxidized zone for an imposed surface oxygen potential, oxygen permeability was determined. The dgfusion coefficient of oxygen in iron was then calculated using known solubility data, yielding the expression: where Do is the diffusion coefficient of oxygen in bcc iron in sq cm per sec and T is temperature in OK. RECENTLY Hepworth, Smith, and Turkdoganl measured the diffusivity of oxygen in bcc iron and reported the temperature dependence of diffusivity from data determined in the a, and 6 temperature ranges. Subsequently Swisher and Turkdogan' have measured the diffusivity of oxygen in fcc iron. Internal oxidation techniques were employed by these investigators and in this current study. The analysis of this technique is developed by wagner3 (presented in English by Hauffe4 and Rapp 5). In this present study bcc iron stabilized by phosphorous was used to determine oxygen diffusivity in the temperature range 900° to 1300°C. Meijerin 6 has studied oxygen permeability in this temperature range using bcc iron stabilized with 5 pct Sn. Other inves- tigators who have studied oxygen permeability in bcc iron at other temperatures are Schenck et al., 7 Bohen-kamp and Engell, 8 and Bradford. EXPERIMENTAL Electrolytic iron of 99.99 pct purity was alloyed to contain 0.897 pct P and 0.093 pct Al. The maximum weight percent phosphorous required to stabilize bcc iron between 910" and 1392°C is 0.51 pct as determined by Haughton,10 0.42 pct by Roquet and jegaden," and 0.58 pct by vogel,12 with the latter value preferred by Hansen.13 Microprobe analysis indicated that there was no segregation of the phosphorous either before or after permeability studies; therefore, the quantity of phosphorous added was assumed to be sufficient to stabilize the bcc structure. Furthermore, the permeability results of studies on this alloy agreed substantially with interpolated values from previous data on bcc iron.' An ingot of the Fe-P-A1 alloy was hot-rolled to a l-in.-thick slab. Specimens were machined to dimensions: 13/8 by $ by 1/4 in. The experimental apparatus and procedure used have been described before.' A constant oxygen potential was established by passing argon and hydrogen through a column of oxalic acid dihydrate, which has a water vapor pressure which is well-known as a function of temperature. Slab specimens were exposed to a gas mixture sufficiently lean in oxygen to prevent the formation of a surface oxide for predetermined temperature for selected times. The specimens were then quenched, sectioned, and examined metallo-graphically. All quenched specimens were iron-plated to provide protection from the outside sample edge during polishing. Fig. 1 shows a typical microstruc-ture for a specimen oxidized at 953°C for 48.00 hr at a water vapor-to-hydrogen pressure ratio of 0.20. DISCUSSION AND RESULTS The following equation was derived by Hepworth et al.' from Wagner's kinetic expressions for internal oxidation:

Jan 1, 1969

By J. King Hoyt

IN both Sweden and England rapid progress is being made in metallurgical development, and the steel industry in both countries is distinctly on the mend. There has been some industrial trouble in Sweden in the iron mines and the wood pulp mills, but at the same time all the steel works have a sufficient stock of pig iron and ore to continue their operations for many months to come. Consequently the strike, unless long protracted, will not affect the output of steel in Sweden. Several of the steel manufacturers in Sweden, most notably Forsbacka and Sandviken, have been very suc-cessful recently in securing large orders, particularly from the continent, for ball-bearing steel, both hollow and solid. Whereas some years ago they ran into-se-rious competition with the German mills, the quality of the steel from these Swedish mills is such that they are now firmly established, and are selling some of the lead-ing manufacturers of bearings on the Continent, as well as automobile manufacturers. The secret of their success seems to lie in a better selection of ores, in more careful control of blast-fur-nace operations and better equipment. Rule of thumb in steel making is taboo, and strict reliance is placed on the laboratory. They are constantly experimenting, and metallurgists and chemists are sent to different countries for study and investigation. In their native ores they have, of course, a unique advantage in pos-sessing iron ores extraordinarily free from phosphorus. At Forsbacka, they are not content with the ordinary chemical analysis of the ingot; but also test the physical properties, as well as make metallographic investiga-tions for slag inclusions, segregations and oxides. In both England and Sweden they watch the nitrogen con-tent of the steel very carefully, a feature which does not appear in the ordinary analysis. In testing carbon, they do not use the color test, but employ an electric .induction device.

Jan 7, 1928

(Members are urged to send in for this column any notes of interest concerning, themselves or their fellow-members.) Members and visitors who registered at institute headquarters during October A. Adiassewich, St. Petersburg, Russia. Charles W. Merrill, San Francisco, Cal. A. F. Lucas, Washington, D. C. Carl J. Trauerman, Butte, Mont. Allan J. Clark, Lead, S. D. Herbert B. Cox, Boston, Mass. Prof. Loewinson-Lessing, St. Peters- James W. Malcolmson, Kansas City, Mo. burg, Russia. A. E. Sunderhauf, Paramaribo, Dutch F. Maury Gillespie, Abangarez, Costa Rica. Guiana, S. A. M. Gardner Talcott, Irvington-on-Hudson, N. Y. D. W. Brunton, Denver, Colo. A. P. Watt, Newark, N. J. Dwight E. Woodbridge, Duluth, Minn. S. A. Taylor, Pittsburg, Pa. Alexander Fyfe, Boston, Mass. Ralph Wilcox, Miami, Ariz. Robert A. Seip, Wilkes-Barre, Pa. William J. Cox, Denver, Colo. A. J. Eveland, Boston, Mass. E. P. Ross, Duquesne, Pa. M. F. Sayre, Brewster, N. 1. H. Mortimer-Lamb, Montreal, Canada. Albert Sauveur, Cambridge, Mass. F. L. Grammer, Leesburg, Va. Robert H. Leach, Brockton, Mass. R. R. Moore, Mexico City, Mex. Steinar Foslie, Kristiania, Norway. Charles E. van Barneveld, San William A. Wong, Honolulu, Hawaii. Fran¬cisco, Cal.

Jan 11, 1913

By Albert D. Pernichele, Wayne C. Smith

Both water pollution and proposed solid waste disposal regulations have a definite effect on the copper leaching industry and some of the major factors affecting the industry are discussed in this paper. New developments of the NPDES are discussed with emphasis on the ‘toxic’ or priority pollutants, and EPA’s philosophy on the control of these pollutants. The protection of groundwater is the prime aim of RCRA through solid/hazardous waste management. Some of the major elements of the RCRA regulations that will effect the copper leaching industry are discussed.

Jan 1, 1980

By S. H. McFarlane, K. H. Zaininger, G. W. Cullen, C. C. Wang, G. E. Gottlieb

Heteroepitaxy of silicon on stoichiometric spinel has been studied. Both boron-doped (p-type) and arsenic-doped (n-type) single-crystal silicon films have been grown by the pyrolysis of silane on sioichiometric spinel (MgAl2O4) substrates prepared by a flux technique. The spinel crystals are free from strain and subgrains, and exhibit no thermal instability at temperatures employed for silicon deposition. The growth parameters of epitaxial silicon have been studied. Effects of substrate orientation, surface preparation, and growth conditions on the silicon Properties have been determined. The silicon-spinel composite was characterized by X-ray diffraction, electron diffraction, electron microscopy, and optical techniques. Information on epitaxial orientation relationship, defect structures and film-substrate interface has been obtained. A parallel orientation relationship was found between silicon and spinel. The silicon films exhibit no subgrain structures. However, growth pyramids, microtwins, stacking faults, and dislocations are the prevalent defects. The deformation of epitaxial silicon was measured by an X-ray technique. It was found that the epitaxial silicon is strained under compres-sive stress due to the thermal expansion difference between the film and substrate. The stress was estimated using the classical plate theory and beam equation. Electrical properties of the epitaxial silicon have been measured, including resistivity, carrier concentration, and Hall mobility. MIS and vertical through diffused junction structures have been fabricated wing silicon-spinel composite. Information on MIS characteristics, minority carrier life time, and junction properties has been obtained. THE achievement of single-crystal growth of large area silicon semiconductor films on oxide insulating substrates is of technical importance to many solid state electronic devices. The semiconductor-insulator composite structure is also of scientific interest because the heteroepitaxy is determined by the spatial relationship between the atomic arrangement in the substrate and that of the atoms in the appropriate crystallographic plane of silicon. The degree of crystalline perfection of the silicon deposits depends also on the physical condition of substrate surface. Epitaxial growth of silicon on commercial flame fusion Al-rich spinel (MgO:3.3A12O3) has been reported by several investigators.'-4 The lattice of spinel of this composition is distorted. The material cracks and exsolves the excess alumina in the lattice at temperatures (-1200°C) used in fabricating silicon devices. Stoichiometric MgA12O4 spinel exhibits neither lattice distortion nor thermal instability. Results are given on the epitaxial growth and characterization of silicon on stoichiometric spinel. EXPERIMENTAL Fabrication of Silicon-Spinel Composite Structures. The MgA12O4 spinel substrate wafers were prepared from bulk single crystals grown at about 1200°C by a flux technique5 using a PbF2 flux. The crystals are free from strain and subgrains, and exhibit a typical dislocation density of less than 50 lines per sq cm. The crystals are thermally stable without cracking and exsolution of alumina to at least 1500°C. The spinel crystals were oriented for cutting by the Laue X-ray back-reflection method.6 Substrate wafers (about 25 mil thick) of (Ill), (loo), and (110) orientations have been obtained bu cutting the X-ray oriented crystals using a standard type diamond wheel. An accuracy of better than 1/2 deg is maintained throughout the operation. The spinel substrate wafers were mechanically lapped and polished to produce the flat and smooth surface which is required for silicon epitaxy. Lapping was carried out with about 30-µ boron carbide abrasives to obtain a flat coplanar surface. The lapped surface was further polished using successively finer grades of alumina, ending with the 0.3-µ grade. After polishing the wafers generally have a flatness of ±0.4 µ per cm, as revealed by interferometry. Fig. 1 shows (111) oriented MgA12O4 spinel wafers of various shapes.

Jan 1, 1970

By F. W. Gibson

A detailed description of the smelting and refining operations of the Amax-Homestake Lead Toller's smelter at Buick, Missouri. This is one of two completely new lead smelting and refining operations to go into operation in the United States in over forty years. Incorporated into the operation are the new methods and equipment which have been developed and lend themselves to the particular metallurgy of this plant. The text, as well as the statistical data presented, represent actual current practice after 22 months of operation, and although the metallurgy is considered to be relatively simple, several metallurgical problems unique to Missouri concentrates are discussed.

Jan 1, 1970