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By J. G. Early, F. V. Lenel, G. S. Ansell

The isothermal shrinkage rates of copper-powder compacts were determined in the temperature range from 760o to 1060oC. The rates for compacts fabricated from a pure spherical copper powder were compared, on the one hand, with those fabricated from a spherical powder containing a dispersion of aluminum oxide in the copper matrix and, on the other hand, with those fabricated from a pure copper powder having irregularly shaped particles. The irregular copper-powder compacts shrank much faster than the spherical copper-powder compacts and these, in turn, shrank faster than dispersion -strengthened copper -powder compacts. The experiments were run under a small external load. By varying this load, the stress dependence of the isothermal shrinkage rate could be measured for compacts from spherical-copper powders. This stress dependence was found to be approximately proportional to the 4th (dispersion-strengthened alloys) or 4.5th (pure metals) power of the stress. It is concluded that the material-trans port mechanism is due to dislocation climb rather than to Herring-Naharro creep. In this investigation the isothermal shrinkage rates of compacts made of copper powder with an average particle size of 70 g in the temperature range from 780o to 1060°C were studied. The aim of the investigation was to determine the mechanism of material transport responsible for the shrinkage of these compacts. Since the phenomenon observed in this investigation was shrinkage of compacts at high temperatures, it will be necessary to consider all the material-transport mechanisms possible in sintering. It is unlikely that evaporation and condensation, surface diffusion, or even volume diffusion of vacancies, in which surfaces of small radius of curvature are vacancy sources and those of larger radius of curvature vacancy sinks, will materially contribute to a sintering process involving shrinkage, i.e., one in which the centers of adjacent particles move towards each other. The two principal mechanisms which were considered were the so-called Nabarro-Herring mechanism and a plastic deformation mechanism by dislocation movement. Both of these mechanisms were originally conceived to explain creep, i.e., the plastic deformation of metals at elevated temperatures under a constant applied stress. The shrinking of metal-powder compacts which was studied in this investigation can be readily treated as a creep process. This means that the shrinkage rates observed are considered as creep rates under the influence of an applied stress. It is true that the stresses in sintering experiments are generally not constant but decrease continually with time, but, by considering creep rates or shrinkage rates over a relatively short time interval, the small changes in stress during this time interval can generally be neglected. Nabarro-Herring microcreep is a high-temperature deformation mechanism which is caused by a diffusional flow of vacancies from boundaries under a tensile stress towards those under a compres-sive stress. Herring1 has shown that in this type of microcreep the strain rate e is proportional to the applied stress and follows an equation of the form ma, aexp(-Q/RT) [l| where <j is applied stress, Q is the activation energy for self-diffusion, R is the gas constant, and T is the absolute temperature This type of creep can explain the shrinkage of a porous compact. The surface of the pores are subjected to the tensile stress of surface tension, while the grain boundaries are under a compressive stress also due to surface tension. Vacancies diffuse from the pore surface through the lattice to the grain boundaries, where they are eliminated. In order to maintain vacancy equilibrium at the pore surface the vacancies leaving the region of the pore surface are replenished from the volume of the pore, which means that the pores shrink.

Jan 1, 1964

By R. S. Busk, E. G. Bobalek

The relation between gases and metals has been a subject of increasingly active investigation during the past years, principally devoted to the study of metal-hydrogen systems. It has been found that hydrogen is soluble in most molten metals to an appreciable extent and somewhat soluble in most solid metals.l,2 In every known case there is a sudden decrease in solubility at the melting point. Thus a freezing mass of metal containing hydrogen in excess of the solid solubility must in some way expel that excess during the freezing process. This leads to internal blowholes, and such effects as pinhole porosity. Gas trapped in metal that is to be fabricated by a working process such as extrusion or rolling may be the cause of blisters. For some cases, notably in copper and iron alloys, the presence of hydrogen can lead to extreme embrittle-ment of the metal. The aluminum-casting industry has long recognized the importance of hydrogen in its techniques. Excess gas in molten aluminum alloys often leads to the formation of "pinhole porosity" in the solid casting.= To prevent this hydrogen pickup it is necessary to avoid overheating the melt and to protect it from such sources of hydrogen as water. In spite of all precautions, it is sometimes necessary to extract hydrogen from the melt just before pouring by bubbling with a gas such as chlorine or nitrogen. Reccntly it has been found that somewhat similar effects are possible with magnesium alloys, in that the presence of hydrogen can induce or aggravate micro-p~rosity.4-6 This paper is primarily concerned with a presentation of some facts concerning the solubility of hydrogen in magnesium and its alloys, with some discussion of the significance of these facts in a practical sense. In any study of gas-metal systems it is important to bear in mind a clear distinction between adsorption on surfaces and absorption within the lattice.&apos; Considerable attention has been directed toward determining whether hydrogen is truly soluble in any solid metal, or whether the gas extracted from a sample was present at surfaces (external and internal) only.7 Most present day evidence supports the idea of true solution in addition to adsorption. A second important factor when dealing with gas solubility is the dependence of such solubility on external pressure. For diatomic gases such as H², solubility in both liquid and solid metals apparently is proportional to the square root of the pressure, indicating a breakdown to a monatomic gas before diffusion into the lattice.= For true equilibrium values of solubility, therefore, the pressure at the the surface must be constant and, preferably, known. Very little has been published concerning the hydrogen-magnesium system. Winterhager has presented the most

Jan 1, 1947

By R. S. Busk, E. G. Bobalek

The relation between gases and metals has been a subject of increasingly active investigation during the past years, principally devoted to the study of metal-hydrogen systems. It has been found that hydrogen is soluble in most molten metals to an appreciable extent and somewhat soluble in most solid metals.l,2 In every known case there is a sudden decrease in solubility at the melting point. Thus a freezing mass of metal containing hydrogen in excess of the solid solubility must in some way expel that excess during the freezing process. This leads to internal blowholes, and such effects as pinhole porosity. Gas trapped in metal that is to be fabricated by a working process such as extrusion or rolling may be the cause of blisters. For some cases, notably in copper and iron alloys, the presence of hydrogen can lead to extreme embrittle-ment of the metal. The aluminum-casting industry has long recognized the importance of hydrogen in its techniques. Excess gas in molten aluminum alloys often leads to the formation of "pinhole porosity" in the solid casting.= To prevent this hydrogen pickup it is necessary to avoid overheating the melt and to protect it from such sources of hydrogen as water. In spite of all precautions, it is sometimes necessary to extract hydrogen from the melt just before pouring by bubbling with a gas such as chlorine or nitrogen. Reccntly it has been found that somewhat similar effects are possible with magnesium alloys, in that the presence of hydrogen can induce or aggravate micro-p~rosity.4-6 This paper is primarily concerned with a presentation of some facts concerning the solubility of hydrogen in magnesium and its alloys, with some discussion of the significance of these facts in a practical sense. In any study of gas-metal systems it is important to bear in mind a clear distinction between adsorption on surfaces and absorption within the lattice.&apos; Considerable attention has been directed toward determining whether hydrogen is truly soluble in any solid metal, or whether the gas extracted from a sample was present at surfaces (external and internal) only.7 Most present day evidence supports the idea of true solution in addition to adsorption. A second important factor when dealing with gas solubility is the dependence of such solubility on external pressure. For diatomic gases such as H², solubility in both liquid and solid metals apparently is proportional to the square root of the pressure, indicating a breakdown to a monatomic gas before diffusion into the lattice.= For true equilibrium values of solubility, therefore, the pressure at the the surface must be constant and, preferably, known. Very little has been published concerning the hydrogen-magnesium system. Winterhager has presented the most

Jan 1, 1947

By Harry A. Roe

The power drag scrapers and the slackline cableway excavator have been called "long-range excavators." Broadly, their field of usefulness is restricted to work in which their long range of action permits them to operate economically, and which other, possibly more conventional, excavating units cannot do. Both of these machines dig or lift material and transport it to a remote dumping point. They combine these two functions in a single machine, nearly always in a single straight-line motion. The purpose of this paper is to examine the important features that distinguish the machines in this group from each other, as well as from other groups. The Machines The "power drag scraper" is a long-range excavating machine that employs a bottomless drag scraper operated back and forth between digging and dumping points by two haulage cables. The typical arrangement is that of Fig. 1. This is the "slusher" of the underground mine, as well as the "dragline scraper" of the sand and gravel industry, and other open-pit mining operations.

Jan 1, 1938

By Harry A. Roe

The power drag scrapers and the slackline cableway excavator have been called "long-range excavators." Broadly, their field of usefulness is restricted to work in which their long range of action permits them to operate economically, and which other, possibly more conventional, excavating units cannot do. Both of these machines dig or lift material and transport it to a remote dumping point. They combine these two functions in a single machine, nearly always in a single straight-line motion. The purpose of this paper is to examine the important features that distinguish the machines in this group from each other, as well as from other groups. The Machines The "power drag scraper" is a long-range excavating machine that employs a bottomless drag scraper operated back and forth between digging and dumping points by two haulage cables. The typical arrangement is that of Fig. 1. This is the "slusher" of the underground mine, as well as the "dragline scraper" of the sand and gravel industry, and other open-pit mining operations.

Jan 1, 1938

By Godfrey T. Vivian

Very often important discoveries are made in one industry that may be used to advantage in another, but, owing to the rarity that men step out of one industry into another, these discoveries remain unknown outside of the trade or profession in which they are made. The present paper is written solely with the object of bringing to the notice of mining and metallurgical engineers a centrifugal ore-concentrator which eventually may have a great application. Ore- Grading. Fig. 1 represents the action which takes place when solids of different dimensions are stirred up in a box and allowed to settle as minerals of the same size but of different specific gravity. This principle is applied practically in grading china-clay and in enriching tin-slimes. In the latter case the slimes are stirred around in a tub with water and allowed to settle while at the same time the side of the tub is struck with a hammer. The colloidal slimes are then poured off and various slices taken off horizontally. The great drawback of this process is that the particles are deposited horizontally and all the colloids are lost. Fig. 2 represents the action in which the particles are deposited side by side. Here the drawback is the great length of the box needed in order to prevent excessive loss. The alternative to lengthening the box is to increase the force of gravity. Centrifugal force may be regarded practically as the force of gravity augmented. Fig. 3 illustrates the Gee centrifugal machine for grading ores. The drum, A, fitted with a box, B, is mounted on a shaft or spindle, C, the whole being suspended from a ball-bearing of special design at D, supported between girders, E. Rota-

Jan 1, 1913

By H. F. McCullough

THE success of a coal-mining venture as relates to operations at the gob or break-line, such as the drawing of pillars or the working of long-faces, depends upon the control of face conditions. The measures required to control the latter are dependent upon the action of the coal seam, roof and floor at and in the vicinity of the faces, but the manner in which these will act is dependent upon the rate of face movement as well as upon the face characteristics and upon the forces exerted. Yet the merits of a method of working-the practicability of controlling face conditions and the means required for such control when applied to any particular case-are usually judged only upon a consideration of the characteristics of coal seam, roof and floor, and the manner in which they have been observed to act. Practically every coal-mining man knows that face conditions are influenced by the rate of face movement, but few have appreciated that this is as much of a factor in the control of face conditions as are the face characteristics and the forces exerted. Fewer yet have recognized or taken advantage of faster rates of face movement as one of the principal means of establishing control of face conditions or of securing more favorable face conditions. Seemingly inherent difficulties, particularly in the control of roof conditions, but also in the control of conditions of the coal seam and floor, are frequently mitigated or disappear when the rate of movement of the faces is sufficiently increased. The characteristics of the coal seam, roof and floor and the forces exerted upon them do determine the general trend or tendency of face action, but the manner in which the coal seam, roof and floor will act and be acted upon and the magnitude of the action during the time the site of mining operations remains at any particular point is very largely determined by the rate of movement of the faces.

Jan 10, 1926

By V. Koump, T. F. Perzak, R. H. Tien

A series of experiments were carried out in which the rates of propagation of the liquidus and the eutectic fronts Mere measured during essentially one-dimensional freezing of Al-Cu alloys. The dimensions of the ingots were 3 by 5 by 6 in. Three different alloys containing 0.1, 4.5, and 17 pct Cu were used in these experitments. For each alloy the rate of heat removal was varied to give a total jreezing time in the range 3 to 30 min. The results of these measurements cowlpared favorably with the theoretical model of freezing of binary alloys with time-dependent surface temperature. IN engineering analysis of solidification of commercia1 steels and nonferrous alloys it is a common practice to assume that an alloy freezes by propagation of an isothermal solidification front, i.e., essentially as a pure metal. In two recent theoretical investigations&apos;j2 the present authors explored the possibility of a more realistic approach to the problem of solidification of alloys. In the proposed model the freezing of an alloy is assumed to take place by propagation of two isothermal fronts, i.e., the liquidus front and the solidus (or eutectic) front. The region between the two fronts contains both liquid and solid and is referred to as the solid-liquid region. The width and the solid content of the solid-liquid region vary with alloy type, solute concentration, and cooling rate. For a given alloy system, initial concentration of solute, and the mode of heat removal, the proposed model yields the temperature distribution within the solid skin, temperature, solid fraction, and concentration distributions with the solid-liquid region, and the rates of propagation of the liquidus and the solidus fronts. This model is obviously of considerable practical importance in engineering analysis of solidification processes, since it gives a more realistic estimate of skin strength during solidification and a better estimate of the total freezing time. Before the new model can be used with confidence, however, it is necessary to test this model experimentally. The experimental testing of the proposed model is a relatively simple matter since the effects to be measured are large and a relatively simple experiment will suffice. The theoretical model predicts, for example, that during freezing of an alloy containing substitutional type solute (negligible diffusion in the solid during freezing) the solid-liquid region occupies an appreciable portion of the ingot, even at low concentration of solute.&apos; Another prediction of the theo- V. KOUMP, formerly with U. S. Steel Corp., is now with Research and Development Center, Systems and Process Division, Westinghouse Electric Corp., Pittsburgh, Pa. R. H. TlEN is Senior Scientist, Fundamental Research Laboratory, U. S. Steel Corp., Research Center, Monroe ville, Pa. T. F. PERZAK, formerly with U.S. Steel Corp., is now with Fiber Industries, Greenville, S. C. Manuscript submitted March 6, 1968. IMD retical model, easily verifiable by experiment, is that the rate of propagation of the solidus (or eutectic) front increases as the solidus front approaches the center of the slab. This prediction is contrary to well-known behavior of the solidification front during freezing of pure metals, where the rate of propagation of the solidification front decreases with time and freezing is completed at the lowest rate. A rather severe test of the proposed model is provided by comparison of theoretical predictions and experimental measurements of the effects of cooling rate and composition on the rates of propagation of the liquidus and the eutectic fronts. In order to test the soundness of the formulation and the method of solution of the problem of solidification of alloys a series of experiments were carried out in which the rates of propagation of the liquidus and the eutectic fronts were measured during essentially one-dimensional solidification of A1-Cu alloys. The A1-Cu system was chosen strictly as a matter of convenience. Three different alloys containing 0.1, 4.5, and 17 pct Cu were used in these experiments. For each alloy the rate of heat removal was varied to give the total freezing time in the range 3 to 30 min. The results of these measurements are compared with the predictions of the theoretical model of solidification of binary alloys, with time-dependent surface temperature.&apos; Before the experiments described in this paper were undertaken, a serious attempt was made to utilize the measurements of previous investigators to test the theoretical model. In the course of this preliminary study a careful review was made of experiments of Pellini and coworkers3 and Doherty and Melf~rd.~ The measurements in Pellini&apos;s work were carried out using a steel containing at least four major components. Evaluation of the solid fraction-temperature relation for this steel (required in the theoretical model) is difficult and uncertain. Doherty and Melford, on the other hand, measured the solid fraction-temperature relation experimentally, but did not give sufficient data to explore the effects of composition and the cooling rates on solidification. Hence it was not possible to utilize these measurements to test our theoretical model. EXPERIMENTAL METHOD The experimental technique used in this investigation differs somewhat from the more conventional techniques employed in solidification studies. This technique was developed primarily to eliminate con-vective mixing in the molten metal caused by pouring of molten metal into the mold. In our experiments A1-Cu alloys were melted directly in the mold. The mold assembly used in solidification experiments is shown in Fig. 1. The mold was fabricated from *-in. stainless-steel sheet. The dimensions of

Jan 1, 1969

By Chase Palmer, Edson S. Bastin

While the reducing action of organic matter, of ferrous sulphate, and of hydrogen sulphide has frequently been invoked to account for the deposition of native gold and silver from ore-forming solutions, the high efficiency in this respect of certain of the metallic minerals which form the ore itself has not been suffciently recognized. If a little finely powdered chalcocite is placed in a test-tube arid 2 or 3 cc. of a dilute solution of gold chloride are poured over it, two or three shakes of the tube suffice to remove all the gold from the solution. The color of the solution changes from yellow to pale green, showing that copper is dissolved simultaneously with the precipitation of metallic gold. If a piece of chalcocite is hung in a dilute aqueous solution of silver sulphate (1/40 normal), a coating of silver begins immediately to form on the mineral, and within a few moments a beautiful silver tree has developed, similar to that formed when metallic zinc is immersed in a similar solution. When similar experiments are conducted with other sulphides and with certain arsenides and sulph-arsenides, especially those known to be commonly associated with native silver in ore deposits, it is found that these minerals differ greatly in their efficiency as precipitants, especially in their effect on silver solutions. The tests made with most of the minerals were qualitatipe only, but the reactions of a silver sulphate solution on chalcocite and niccolite were submitted to quantitative study to determine the nature of the reactions involved. Quantitative studies of the reactions with other minerals are now in progress

Jan 1, 1914

The Similkameen mine is located about 100 miles east of Vancouver, British Columbia, and ten miles west of Princeton, where the mine personnel live. Princeton was the first town in the British Columbia interior, originally the home of Cree and Blackfoot Indians and later settled by men of the Hudson&apos;s Bay Company, miners, cattlemen, and others looking for gold. After gold, there were coal mines and then copper mines . The Granby Consolidated Mining Company, Limited, operated the Copper Mountain ore bodies from 1926 to 1930 and from 1937 to 1957, mining 34 million tons of about 170 copper ore, mainly from underground. In 1966, Newmont Mining Corporation acquired the Ingerbelle property on the west side of the Similkameen River. Newmont then purchased the assets of Granby and formed Similkameen Mining Company to develop and operate the Ingerbelle and Copper Mountain ore bodies on both sides of the Similkameen River canyon. The Ingerbelle and Copper Mountain ore bodies lie within rocks composed of andesite tuffs, agglomerates, and argillites. Chalcopyrite mineralization occurs as a dissemination. Original ore reserves were estimated at approximately 75 million tons grading 0.52% copper. Mining is carried out on a three-shift, seven-day-week schedule at a rate of about 60,000 tons of ore and waste per day with four 10 cu yd P & H 1900 shovels which mine and load a fleet of 100-ton Lectra Haul trucks. Among the unique features of the design and construction of the Similkameen project was the construction of 4. 5 miles (7. 24 km) of new Trans-Provincial No. 3 highway by the company to the specifications of the British Columbia Department of Highways. The old highway traversed the Ingerbelle pit area. Along the relocated highway is a 4, 000 ft (1219 m) long berm which conceals the mine pit. This area has been replanted and now looks like the original forest scenery. Another interesting feature is that the tailings from the concentrator flow by gravity over a 1000 ft (34% m) suspension bridge, which crosses the Similkameen River canyon then passes through a tunnel to the dam site, a distance of 59,000 ft (17,980 m) to the cyclone station. When the Copper Mountain ore bodies are mined, the ore will be transported by belt conveyor on a second suspension bridge across the canyon to the Ingerbelle concentrator. After being loaded by the shovels into the 100-ton trucks, the ore is

Jan 1, 1978

By Basil B. Zavoico

The symposium on production for the year 1942 contains no papers on the foreign situation except those on Argentina and Mexico. It has always been the policy of officers in charge of the symposium to refrain from publishing information that might possibly injure national or private interests. At the close of the war we hope again to publish full and accurate records of production abroad. Excerpts From Circular to Authors In order to facilitate interpretation of the data in this chapter, we print the following excerpts from the Circular to Authors. The field is the unit in this tabulation. In cases of fields extending across State boundaries, such as Rodessa, it is suggested that each State author treat the section of the field in his State as a unit, and by a footnote indicate that the field extends into an adjacent State. Each space in Table I may represent one of four possibilities; either it is not applicable to the particular field, or the proper entry is not determinable, or the proper entry may be determinable but is not determinable from data available to the author, or the proper entry is determinable. When spaces are not applicable, leave blank; in spaces where the proper entries are determinable but not determinable from data available to the author, please insert y; in spaces where the proper entries are determinable by the author, make such entries. y implies a Rope that in some future year a definite figure will be available. The entry of a zero is a positive declaration, and it is an important declaration where it is in order. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries are not subject to precise determination. In such cases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces the correct entries represent the opinion of the author (for example, "Area Proved") and in such cases the entry need not be hedged to such extent as when the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use x. It is thought that the nearest whole numbers are sufficiently accurate for our purposes except as to percentage of sulphur in oil. If an author desires to report any other figures to tenths, he may do so. The quantity of gas produced should include, where possible, gas sold or otherwise marketed, and gas blown into the air, burned as flares or otherwise wasted. Segregation of these figures would be interesting if the authors can make such segregation. In any event, the figures should represent as nearly as possible the total quantity of gas removed from the reservoir. Under the columns on "Depth," the average depth to the top of the productive zones and to the bottom of the productive wells, when subtracted, should give the approximate thickness of the productive zone. For fields where this is not true because of unusually high dip or for some other reasons, it is suggested that the authors indicate in their text the approximate average thickness of the productive zone.

Jan 1, 1943

By E. A. Beck

For a number of years many attempts have been made to use thermit in order to do away with piping in ingots. Some of these attempts were successful, while others did not give the expected results. Nearly every plant had its own method of using the thermit, and no special care was taken to study the results or to find the causes for lack of success. Formerly the principle of the process was to decrease the piping by introducing a can filled with thermit, attached to an iron rod, into the head of the ingot directly after it had been poured. In this case the thermit reaction took place in the upper part of the ingot, and it was thought that through the heat produced the head would keep liquid longer and piping thus be reduced. In other words, the aim was to keep the head of the ingot open by making use of the heat of the thermit reaction, which would thereby give the gases in the steel sufficient time to escape. This result can be attained by the application of a large enough quantity of thermit, but it would not be economical in general practice, and could only he used for high-grade material. Many steel-makers abroad and in this country have had this experience. The Th. Goldschmidt A. G., Germany, has, therefore, made a special study of this question with the cooperation of a well-known steel company, and has worked out a new method for the application of thermit for this purpose. The results obtained have been most satisfactory and reliable, and this process is now used in Germany on a large scale in many prominent steel-works. The thermit is applied in cans, as in former years, but the principle of the process is entirely different. The object of using the thermit is not to heat the steel and keep it liquid,

Jan 1, 1914

By Paul D. V. Manning

MAGNESIUM is an exceedingly strategic material but the importance of its production at the time this war started was not realized. Our Government then suddenly became much alive to the need of a tremendous increase in magnesium output, and became a participator in the industry. In this paper an attempt will be made to given an over-all picture of the industry as it has been, and is being, developed. The present war is giving a great acceleration to the use of lighter metals. Development of facilities for production of great tonnages of aluminum and magnesium is bound to bring about some interesting changes in later peace times because costs will be low and production capacities high. As our knowledge of the metallurgy of magnesium alloys increases, this metal will become of vital peacetime importance and will be used in ways we do not now imagine. Household refrigerators, furniture, automobiles, even houses will all be lightened through the use of magnesium.

Jan 1, 1943

By K. J. Brondyke, P. D. Hess

Lack of correlation between densities of aluminum alloy samples solidified under reduced pressure (vacuum gas test) and hydrogen content of the metal is explained on the basis of inclusions serving as nuclei for hydrogen bubble formation. As a result of these findings, the vacuum gas test is suggested as a practical tool to indicate metal cleanliness and the potential effects of hydrogen. Visual obseroation of the sample during solidification under vacuum provides more useful information than that obtained either from density meas -urements or sectioning of the solidified sample. A rapid, practical method of detecting and measuring gas in molten-aluminum alloys has been sought for many years. The development of the vacuum gas test appeared to solve this problem. However, the vacuum gas test is subject to certain limitations, and the results must be interpreted mindful of these limitations, as described herein. Since the only gas which is appreciably soluble in aluminum is hydrogen, the terms gas and hydrogen will be used interchangeably in this paper. In the early days of the aluminum industry, when techniques were not as refined as they are today, it was customary to pour small "pancakes" of alumi- num on a metal plate. These were allowed to solidify under atmospheric pressure. Excessive gas in the metal was evidenced by the appearance of small bubbles on the surface of the "pancake".&apos; It is obvious that such a method would only show very high gas levels far above any which could be tolerated by today&apos;s standards of quality required for most applications. Various attempts were made to develop methods which would be more sensitive. Among these were measurements of density of aluminum alloys solidified under controlled conditions, radiography of cast slabs, and examination of fractures. The method which showed the greatest promise and appeared most practical was the solidification of a sample of the molten aluminum alloy under vacuum. The samples so solidified are evaluated either by observation for bubble emission during solidification, by sectioning the solidified sample and examining for porosity, or by determining the density of the solidified sample. This test is known internationally as the Straube-Pfeiffer test or the reduced-pressure solidification test, but in America it is commonly referred to as the vacuum gas test2-&apos; and will be so designated in this paper. The determination of density appeared an attractive and convenient means of providing a numerical rating for the samples. Attempts were made in some instances to correlate densities to hydrogen contents. Unfortunately, the visible loss of gas during solidification of samples with high gas contents precluded a correlation of vacuum gas test densities with the observed gas evolution. This led to Alcoa&apos;s use of two different pressures; 50 mm of

Jan 1, 1964

By William Kelly

An extensive swamp covers a large part of the town-site of Norway and adjacent laud. Through this swamp run two parallel oreformations. In the north one is the Aragon mine. The south one passes into the swamp on the Harrison property. On the edge of the swamp, about 1000 feet from the Aragon mine, a diamond drill, in the fall of 1889, located the ore-bearing formation and a probable ore-body. To explore further and develop this ore, the Penn Iron Mining Company proposed, in the spring of 1890, to sink a shaft. The drill had shown the depth of the glacial drift to be more than 60 feet. A test-pit near the location of the proposed shaft had struck, at a depth of 20 feet, an amount of water which a 200gallon pump was unable to lower. At the Aragon, a few years before, a shaft had been sunk to hard pan with great difficulty and many delays by the usual method of driving laths. Under the conditions it was decided to sink a caisson- or dropshaft. Two 40-horse-power boilers, a Lidgerwood engine with 4foot drum, and a good derrick were set up; and two No. 10 Kuowles

Jan 1, 1892

By Earl R. Hoskins, James E. Russell

The electrical resistivity of rocks has been studied quite extensively, in particular, the effects of temperature and confining pressure on resistivity. References 1 through 6 at the end of this chapter pertain to electrical resistivity of rock and contain further references on the same topic. The present study is motivated by an interest in determining the in-situ properties of rock as well as the stress state of the rock and how these quantities are changing with time. Most of the previous work on the electrical resistivity of rocks has been directed toward saturated rocks at relatively high confining pressures and temperatures. The present study was oriented towards air-dry surface rock that might occur in mine pillars. The mean stress and temperature under such conditions are comparatively low. It has been demonstrated that the resistivity of rock is highly dependent upon the porosity. In fact, for saturated rocks, a relationship referred to as Archie&apos;s law has been established between porosity and electrical resistivity. In the case of saturated rock, the property that is actually being measured is the resistivity of the solid/fluid system. Since the resistivity of the fluid alone is usually much lower than that of the dry rock, it is understandable that the resistivity of a saturated rock is in general several orders of magnitude lower than the resistivity of a relatively dry rocli. For dry rock, it seems reasonable that the electrical resistivity should increase as microcracks open within the material. Since microcracks open as material is stressed closer and closer to its failure point, it appears that there should be a correlation between electrical resistivity

Jan 1, 1970

By Arthur Taggart

FOREWORD THE tests herein described are part of an extended series of experiments, performed by the authors together with J. F. McClelland and L. W. Bahney, on the reclamation of metallics from foundry and manufacturing-plant scrap. The most obstinate problem encountered was the proper cleaning of the metal. INTRODUCTION In the manufacture of brass and brass products the weight of the finished product leaving the plant is much less than the total weight of copper and zinc entering. A small part of this discrepancy is due to the unavoidable oxidation of the metals in melting, but by far the largest part of the loss is in the form of metallic particles of copper, zinc, and brass. These losses occur principally at three points in the process: (a) in the casting-shop ashes; (b) in the slags from furnaces melting scrap brass; (c) in material spilled on the floor throughout the manufacturing process. The amount of these products in some plants is nearly 100 tons per 24 hours. Casting-shop ashes contain the metal spilled from the crucibles during melting and pouring, and the metal included in the slags formed in the melting process. The ashes also contain pieces of broken crucibles with adhering metal; 20 to 30 per cent. of unburned coal is also present. The metal in casting-shop ashes contains clean pieces of zinc or copper ingots weighing 1 to 2 lb., jagged pieces of metal of all shapes ranging in size from several inches down to the finest dust, and shot and botryoidal shapes ranging in size from 2 or 3 in. down to 0.01 mm. or less in diameter. Slags from furnaces melting scrap brass contain metal in the form of small shot.

Jan 2, 1916

By AIME AIME

AS director of Battelle Memorial Institute and as Chairman of the important O.P.M. advisory committee on metals and minerals, Clyde E. Williams numbers his acquaintances in the mineral industries by the thousands and h because his principal hobby is liking human beings, most of his acquaintancs are also his friends. Clyde is one of the many outstanding metallurgist, in the United States who started as a chemist. After graduating from the University of Utah in 1915 he was successively chemist for U.S. Smelting Refining and Mining Co., and at the Bureau of Mines station at Ithaca, N.Y. He then got into, metallurgical work and in 1920 he was appointed superintendent of the Northwest Station of the Bureau of Mines at, Seattle. Subsequently he was assistant to H. Foster Bain in metallugical work for the

Jan 1, 1942

By W. C. Winegard, E. L. Holmes

The effects of the solute elements lead and bismuth on grain growth in zone -refined tin have been investigated. At low temperatures, viz. below 160°C. or at high concentrations, viz. greater than 0.03 at. pct, the temperature dependence of grain growth was found to be constant. A correlation was found to exist between the rates of grain growth in the presence of solute impurities and the factor [C Ir - 1]2 , where C is the solute concentration, r is the radius of solvent atom, and r&apos; is radius of solute atom. It is shown that the Liicke and Detert theory does not give a satisfactory explanation of the results obtained. INVESTIGATIONS of grain growth in zone-refined lead and tin and some effects of solute elements on grain growth in these metals have been reported by Bolling and winegardly2 and Holmes and winegard? The present investigation is an extension of the previous work, and was undertaken to provide additional results which might make it possible to discover the mechanism whereby the rate of grain growth is affected by the presence of foreign solute atoms. The experimental procedure was exactly the same as that described previously.3&apos;4 Figs. 1 and 2 show the results obtained with lead and bismuth additions over the same temperature range, viz. 167" to 220°C, as that used for the investigation of grain growth in zone-refined tin.3 Fig. 3 shows the results obtained for zone-refined tin and for this tin with lead solute additions over an extended temperature range. DISCUSSION OF RESULTS As mentioned previously,3 the character of grain growth in the particular zone-refined tin used in these experiments appears to change as the temperature of annealing falls below about 160°C. The grain growth became somewhat irregular and was characterized by a jaggedness of many of the grain boundaries. The reason for this change is not known, but may be due either to residual impurity effects or possibly an oxide precipitation. It was obvious that normal grain growth only occurred in the zone-refined tin through the high-temperature range 167" to 220°C, and so the effects of solute atoms on grai11 growth over the two temperature ranges will be discussed separately. a) Effect of Impurity on Grain Growth in the Temperature :Range Above 167°C. It is apparent from Figs. 1 and 2 that, for low concentrations of solute, the rates of grain growth tend towards a common value as the melting temperature of tin is approached. As the concentration of lead is increased, the rate of grain growth close to the melting temperature is also reduced, and at high concentrations the temperature dependence of the rate of grain growth appears approximately constant. It should be noteil that the effect of bismuth is greater than that of the same concentration of lead, but both these solutes have a smaller effect on the rate of grain growth than silver, as seen from an earlier investigation of Holmes and Winegard. It should

Jan 1, 1962

By C. S. Barrett, P. Coheur

AXnealing twins are common in the microstructure of copper that has been rolled and recrystallized. In such samples it follows that a twin relationship should exist between components of the re-crystallization texture,&apos; and several examples of this have been reported. For example, twin relationships have been found in recrystallized electrolytic copper sheet, as indicated in Fig. I, from a paper by Coheur and Lejeune.2 In this pole figure the cube texture (100) [001] is indicated by the hollow squares in the lower half of the figure (the pole figure for 200 reflections) and in the upper, (III), part of the figure. The texture contains, in addition to this orientation, the first-order twins of it, shown in the figure by the filled triangles. This orientation relation has been suggested by others also, under certain annealing conditions,3&apos;4 although pole figures have not been published to confirm it. Some orientations in recrystallized sheets are identical with their twins, because of the symmetry elements of the texture— this is true, for example, with the (113) [ZII] texture so commonly reported for brass—hence it appears impossible in such samples to decide whether the twin relationships result from twinning or merely from the symmetry of the deformation process. The present investigation of a commercial copper strip seems to yield an example in which annealing twins account unambiguously for the principal orientations present. It proves to be a case, also, for which the recrystallization texture cannot be viewed as derived from the deformation texture by a first or second-order twinning mechanism. Materials and Methods The samples investigated were of secondary copper (melted in belgium) to which 0.19 per cent iron had been added to raise the recrystallization temperature. How much the orientation characteristics of this metal can be ascribed to the iron content and how much to other impurities or to melting and pouring practice have not been investigated.* The rolling was done in one direction only, on a mill with rolls of about 20-cm diameter. A strip I. cm wide was reduced from 5 mm thickness to 0.05 mm by several cold passes at commercial speeds. The samples cut from this 99 per cent reduced strip were X-rayed throughout their entire thickness. A pole figure made soon after rolling and annealing was identical, within experimental error, with one that was made when a two-year interval occurred between rolling and annealing. X-ray patterns were made on a camera2 that traversed

Jan 1, 1947