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By F. C. Frischknecht

Most early development and application of electromagnetic prospecting methods took place in Scandinavia, where geological conditions favor their use. In other parts of the world these methods have aroused cycles of interest, but in Scandinavia they have been used continuously and successfully since the 1920's. Electromagnetic methods may be classified into two general groups. One group includes methods in which the source of the electromagnetic field remains stationary while the receivers are moved about to explore the area. The other includes procedures in which the energizing and receiving systems are moved together. Other classifications could be based on the size of the energizing source, the particular components of the electromagnetic field which are measured, or the mode of transporting the equipment. The difference between fixed-source and moving-source methods, however, is of such great fundamental importance that it will be emphasized in this discussion. FIXED-SOURCE METHODS Essentially, a fixed-source method consists of the measurement of electromagnetic fields about the source. The mutual coupling between the source and the earth is constant, but the mutual coupling between the receiver and the earth (unless the earth is homogeneous) and also between the source and the receiver changes at each station. The results are usually normalized by relating the field data to the calculated free space or primary field. Turam and Radio Reference Signal Methods: The turam or two-frame* (see Fig. 1A) is probably * Turam means two-coil. the most common fixed-source method. The energizing source is an insulated cable grounded at both ends or formed into a large rectangular loop. Measurements are taken along a traverse at 5 to 50-meter intervals using two small receiving coils, the lagging coil being placed at the position previously occupied by the leading coil. The complex ratio (i.e., inphase and out-of-phase ratios) of the voltages induced in the two coils is measured. Operating frequency range is about 100 to 800 cps. In a typical turam survey a straight, grounded cable several kilometers long is laid out parallel to the probable strike of the ore deposits or conducting strata being sought. An area extending 1 or 2 km on each side of the cable, and within 1 or 2 km of the ends of the cable, is surveyed. Measurements are made at stations 5 to 25 m apart along traverses perpendicular to the cable. Measurements may be made along lines parallel to the cable to serve as base lines for the traverses or for other special purposes. Commonly the receiving coils are oriented with their planes horizontal so that only the vertical component of the field is measured. If additional information is required, one of the hori- zontal components may also be measured by orienting the coils with their planes vertical. In a modified turam technique developed recently for both ground and airborne measurements (Fig. 1B) the amplitude of the complex voltage induced in a single receiving coil is measured and its phase compared with that of a reference signal transmitted from the energizing system by a radio frequency carrier. Thus the un-normalized field is obtained directly, whereas with the turam method it is obtained by calculation from the ratios. The turam method and its modifications have a greater working depth than the other electromagnetic procedures used in ore prospecting. Under favorable conditions conductors have been located at depths of 200 to 300 m. A modified turam method with one of the electrodes grounded in the upper end of a plunging orebody was used to follow the extension of this body to a depth of 200 m beneath a layer of conducting schists. Straight grounded cables are usually preferred to insulated loops because they are easier to lay out and because they often make the method more sensitive. The greater sensitivity of a grounded cable is a result of ground return currents which may flow in the orebodies in addition to the eddy currents caused by induction from the current in the cable. Anomalies in the vertical field due to eddy currents are characterized by a correspondence between high values for the inphase component and positive out-of-phase components and/or low values for the inphase component and negative out-of-phase components. Also the inphase component may approach zero, but it does not become negative. In very long continuous conductors that are parallel to a grounded cable the effect of ground return currents may far exceed the effect of eddy currents. These ground return currents cause a lack of correspondence between the inphase and out-of-phase components and may cause negative inphase or anti-phase components. It becomes difficult to carry out the measurements and often difficult to interpret the results. Such results immediately suggest the presence of graphitic strata, however, since ore deposits are rarely extensive enough to accumulate sufficient ground return current to cause these results. A cable laid out perpendicular to the strike or an insulated loop is sometimes used in areas where graphitic schists and slates are present. Anomalies are then completely or almost entirely due to eddy currents and are easier to interpret. The measured voltage ratios are normalized by either subtracting or dividing by normal field ratios calculated from free space considerations. The normalized ratios are then plotted as individual profiles. When significant anomalies occur in the ratio measurements, the actual normalized fields are calculated by beginning with a measured or an assumed value for the field at a point near the cable and successively multiplying this value by the normalized ratios. There is a similarity between this process and a numerical integration of the ratio curve. Conversely, in many respects the ratio curve is similar to the first derivative of the field curve.

Jan 1, 1960

By Emmanuel P. Papadakis

Ultrasonic velocity measurements have been made to study the preferred orientation in cube-textured copper. Methods applicable to thin specimens were employed since the specimens were necessarily of sheet material. The measured velocities in various directions in the sheet differed from the corresponding values in single-crystal copper by 1 to 6 pet. The distribution of the deviations indicated that the align-ment of the (001) planes with the rolling plane was better than the alignment of the [100]and [010] directions with the rolling and transverse directions. Ultrasonic pole figures (velocity us orientation) are shown to be useful in the study of preferred orientation. THIS paper describes one set of experiments in a continuing study of preferred orientation in worked metals. This study has been undertaken to investigate the fundamental properties of metals when used as propagation media for ultrasonic waves. Many such materials are of current or potential use in ultrasonic delay lines. Fundamental studies on ultrasonic propagation parameters such as velocity, attenuation, and diffraction (beam spreading) are of importance in the design of delay lines, in the development of nondestructive testing methods, and in the study of materials themselves. Preferred orientation in worked poly-crystalline metals influences all three above-mentioned parameters, and hence is of particular importance. When polycrystalline metals are subjected to mechanical working, they develop textures dependent upon their crystal structure and the symmetry of the working operation.' The texture consists in the alignment of the crystallographic axes of the grains in preferred directions with respect to the symmetry axes of the working operation. Since the grains are elastically anisotropic, the elastic moduli of worked metals are anisotropic. Hence the velocities of elastic waves in worked metals depend on the directions of propagation and polarization. The worked metal may be thought of as taking on the elastic symmetry of a single crystal: so it possesses the same number of independent elastic moduli as the crystal class it simulates. In general, a worked metal does not adopt the crystalline symmetry of its own grains. For instance, most rolled sheet becomes effectively orthorhombic while all bar stock and wire develop hexagonal symmetry. However, certain metals with cubic crystal structure develop a cube texture upon rolling and annealing.= Nearly perfect alignment of [100]-type directions with the rolling direction, transverse direction, and rolling-plane norma1 can be achieved in certain fcc metals and alloys. These cube-textured rolled metals provide an excellent opportunity to test preferred orientation by means of elastic waves, since a worked metal with 100 pct cube texture would have elastic moduli identical to the moduli of its constituent metal. It is the purpose of this paper to present the results of an investigation upon cube-textured copper. Ultrasonic waves were used. The methods of measurement and the experimental results on the effective moduli will be given. The ultrasonic measurements will be shown to complement X-ray pole figures for the determination of preferred orientation in worked metals. EXPERIMENT To study cube - textured material, it was necessary to use thin-sheet material since a severe reduction in gage (95 to 99 pct) is necessary to produce cube texture. Special ultrasonic methods were needed to investigate the thin material at megacycle frequencies. A) Materials. The cube-textured material tested was a copper alloy containing 1 pct Zn. Specimens already measured for Young's modulus4 by Alers were kindly supplied by him. The specimens were slabs 3.00 by 0.25 in. cut from sheet 0.047 in. thick. The orientations of the long axes of the specimens with respect to the rolling direction were taken in 15-deg steps from 0 to 90 deg. B) Measurements. Two distinct experiments were performed to measure the phase velocity in these specimens. One measured the shear wave velocity for propagation in the 0.25-in. direction and polarization in the 3.00-in. direction. The other measured the velocity of both shear and longitudinal waves propagating in the thickness direction in the sheet. 1) Plate-Mode Measurements. The velocity of the zeroth-order shear mode5 was measured in the 0.25-in. direction in each strip. The specimens were ground thinner over half their length to assure that the first-order shear mode would be cut off below 6 Mc per sec, leaving the zeroth-order nondispersive shear mode as the only propagating mode. Piezoelectric ceramic transducers of 5 Mc per sec resonant frequency poled in their long direction were solder-bonded to the edges of the thin part of the slabs as in Fig. 1 after these edges had been made flat and parallel by fine grinding. These transducers produced waves polarized in the 3.00-in. direction and propa-

Jan 1, 1967

By F. Weinberg

It has been suggested, for some time, that the behavior of metals under high-temperature creep conditions is strongly influenced by the behavior of the grain boundaries present in the material. This has led to a number of investigations1-6 in which attempts were made to measure the properties of the grain boundaries themselves, both to determine their contribution to the creep process and to obtain further knowledge of their intrinsic structure and properties. The present investigation was undertaken to extend the observed data under more closely controlled experimental conditions and to attempt to clarify sonie of the discrepancies in the literature. A brief report of the preliminary results has been published.7 EXPERIMENTAL PROCEDURE For the present investigation, controlled orientation specimens were used having plane boundaries which terminated at the specimen surface. Trierys-tal specimens were used instead of the bicrystal type of Puttick and King,' in order to simplify the gripping technique required to apply a shear stress along the boundary. The aluminum used was obtained from the Aluminum Francaise and was of 99.994 pct purity, containing 0.002 pct each of Cu, Fe, and Si. The aluminum tricrystals were grown horizontally from the melt, in graphite boats, and in an argon atmosphere, following the technique developed by Chalmers.' The orientation of the tricrystals was controlled by using seed crystals separated by mica inserts. Thermal conditions were adjusted to produce tricrystals having boundaries which were macroscopically straight, parallel to the growth direction, and perpendicular to the top surface. Following growth, the tricrystals were carefully cut with a jeweller's saw to the test specimen shapes shown in Fig. l(a) and l(b). In Fig. 1(a), the boundaries subjected to shear stresses are indicated AB and CD: Points A and C are the ends of the mica inserts separating the seed crystals; points B and D are at lateral cuts made in the specimen. It was found that the slots left by the mica inserts at A and C had to be enlarged slightly, by cutting, to ensure that the boundary terminated freely at these points. A shear stress was applied to the boundarks by gripping the upper two legs in file-faced Inconel grips and suspending a weight from the lower part of the specimen held in similar grips, as shown schematically in the diagram. The test specimens shown in Fig. 1(b) were cut from long

Jan 1, 1959

By Samuel B. Christy

The present paper is a continuation of a study of the reductionworks of New Almaden, the first part of which was published under the title " Quicksilver-Reduction at New Almaden," in the Transactions of this Society, vol. xiii., p. 547.* Frequent reference will be made to some of the data there given. The following is an outline of the contents of this paper: I. Condensing appliances used at New Almaden: a. Brick condensers, b. Iron condensers—flues and " water-backs," c. Glass and wood condensers, d. Friction-coudensers—filters and revolving screens, e. Flues, towers, and chimneys. II. Analysis of condensing-systems. III. Temperature of condeusers. IV. Product of condensers. V. Treatment of soot. VI. Losses of treatment: a. Nature of losses, b. Composition, weight, and volume of dry gases, c. Volume of wet gases, d. Specific weight of quicksilver vapor, e. Vapor-loss at various temperatures. VII. Comparison with New Almaden practice. VIII. Comparison with results at Idria, Austria. IX. Comparison with results at Almaden, Spain. X. Future improvements in quicksilver-condensation. I. Condensing Appliances. The complete condensation of mercurial fumes in a large way presents numerous practical difficulties, familiar to all who have had to retort amalgams. In condensing the quicksilver-fumes discharged

Jan 1, 1886

By C. K. Leith

CERTAIN ideas on iron and steel sanctions to follow originated in a series of conferences held under the joint auspices of the War Department and Brookings Institute in Washington last spring. The views presented may be regarded as those of substantial segments of the steel industry. In view of the fact that steelmaking capacity can be so quickly converted to the production of armament, any effective control must necessarily include the entire steel industry and not solely the parts devoted to the production of implements of war. It must also be exercised all the way from production and shipment of raw materials through their ultimate conversion into finished products and use. Control will be dis- cussed under two main headings: (I) control of raw materials at the source; (2) control of steel capacity within the Axis countries.

Jan 1, 1944

By Hsun Hu, R. S. Cline

A detailed studj) of texture formation in 2 pet Al-Fe single crystals with initial orientations of approximately (111) [112], (112) [111], and (112) [111] was made by examining the textures developed on the surface and at various interior sections of the crystal after rolling to various amounts. Depending' upon the initial orientation of the crystal, the surface and interior textures may differ only in sharpness, or may differ essentially in orientation. The orientation of the (111) [112] crystal does not change upon rolling up to 70 pet, but after rolling more than 90 pet a distinct component of (001) (110] orientation is developed. The texture formed in the two (112) (1111 type crystals consists of (111) (1121 and (001) (1101 components. The latter, however, is largely confined to the surface layers. The textures formed on both sides of the crystal are identical, and the texture composition profile is approximately symmetrical with respect to the central section of the strip thickness. The formation of these texture components is analyzed. DURING the past seven or eight years, deformation and recrystallization textures in rolled Si-Fe single crystals have been extensively studied by various investigators.1-7 From these studies, much knowledge on texture formation in bee crystals of various initial orientations was obtained. However, these results also raised many questions, regarding particularly the correlation between deformation and recrystallization textures, as well as the deformation texture itself of some particular crystals. To take a (111) [112] type crystal as an example, it was shown by Dunn and Koh2, 3 that this orientation does not change during deformation by rolling. This finding is consistent with the conclusion reached by Barrett and Leven-son8 with respect to iron crystals that (111) [112] is one of the stable end orientations. However, different recrystallization textures were observed by Dunn and Koh3 in (111) [112] type crystals of different initial thickness, which widened differently during rolling even though their deformation textures were identical. Another interesting example, also from the results of Dunn and Koh2'3 is that of texture formation in a (112) [111] crystal. This crystal developed a two-component deformation texture of (111) [112] plus (001) [110]. Its recrystallization texture, however, was found to be predominantly (110) [001], which is related to the (111) [112] component by a simple [110] rotation. This crystal, therefore, behaved as if the other deformation texture component, (001) [110], were not present. There are also discrepancies among the results of different investigators, as well as numerous unexplained fine features of the deformation texture of crystals of various initial orientations. In order to have a better understanding of all of these points, a detailed study of deformation textures is greatly needed. One of the obvious things that has been completely overlooked in previous texture studies is the possible effect of surface texture. All past work on the texture of Si-Fe single crystals was conducted in a rather simple manner, i.e., the rolled crystals were etched to a very thin sheet; then their textures were examined by transmission X-ray techniques. For recrystallization texture studies, unless precautions are taken by etching off a sufficient amount of the surface layer before annealing, the texture developed in the interior may be affected by the surface layer, which may well have a different initial texture and which may have undergone recrystallization earlier than the interior of the specimen. Because of this effect, it is now planned to reexamine the texture of various rolled and annealed single crystals at the surface, and at various sections below the surface by using reflection techniques. In some cases, both surfaces of the rolled crystal will be examined. In one of Dunn's early papers,9 he noted that at an early stage of rolling the crystal seems to divide roughly through the middle to become a sample which in effect consists of two layers having some what different orientations. This effect has never been further explored. The investigation described in the present paper constitutes the beginning of a series of thorough investigations of texture formation in deformed bee single crystals designed to clear up some of the uncertainties which have been discussed. We have chosen a high-purity 2 pet Al-Fe alloy for this investigation. It is known that the allotropic transformation of iron is eliminated by alloying with approximately 1petAl. Such an alloy, being very similar to silicon ferrite, can be heated to the solidus temperature without phase transformation. One reason for choosing A1-Fe instead of Si-Fe for the present investigation is that we have been able to make single crystals of a vacuum-melted high-purity A1-Fe alloy by the strain-anneal method without much difficulty, but were not successful in doing so with a vacuum-melted high-purity Si-Fe alloy. For many research purposes,

Jan 1, 1962

By W. A. Doble

Opinions differ as to whether the water-wheel almost universally known as the Pelton type belongs to the impulse, the tangential, the reactive, the jet or the percussion class, or to a cross between two or more of these classes. The fact is, that for an almost infinitesimal part of a second the axis of the jet of water strikes the bucket of this wheel at a true tangent to its base-line. The percussion of the water, striking the bucket, imparts an impulse to the wheel, causing rotation; and generally the bucket is so shaped that the direction of the jet is

Jan 1, 1900

By Lawrence Adler

In-situ rock has well-recognized rupture and yielding responses. Attention is called to an intermediate response, granulation, which consists of an evenly distributed, small-scale crumbling accompanied by swelling. Granulation results in a negative slope for the inelastic portion of the stress-strain curve as successive interlocks are destroyed, and the load-carrying capacity of the material is reduced. Volumetric swelling with softening also takes place. The prerequisites for such a response are moderate confinement and a uniformly distributed defect pattern. Since rock masses, as well as rock as an intact material, have such patterns in their jointing and texture, respectively, granulation is characteristic of them. The presence of granulation can be demonstrated for a very wide scale, ranging from laboratory testing to regional geologic phenomena. The response of an engineered structure is considered in detail. Granulation appears to be dependent upon internal moments, the formation of which can be controlled by engineering design. The practical implications of such control can be significant in optimizing underground instability and in improving excavation techniques. Rock is usually considered to behave inelastically under high load, by fracturing as a brittle material, or by yielding as a ductile material, ignoring time dependency. These responses, which are characteristic of metallic behavior, appear idealized in Fig. 1, where linear-elasticity approximates the initial behavior. However, another major deformation mechanism peculiar to rock has long been recognized in geology, the granulation of an interlocked material. Granulation consists of a uniformly distributed fracturing and crumbling of the material, accompanied by swelling and softening. Predictably, the associated inelastic portion of the load-deformation curve has a negative slope,

Jan 1, 1971

By William H. Morris

At the Glen Summit meeting, the question of controlling the silicon in pig-iron WAS raised; and as this has been deemed by most furnace-men for years past a matter of special difficulty, an account of our experience in the matter may be of interest. When running on mill-iron, some years ago, we aimed to keep

Jan 1, 1893

By C. H. Brehaut, W. N. Taylor, R. S. Douglas, H. A. Shannon

THE name for this new method of mining is derived from a composition of Horizontal, Radial, Diamond, and the drilling is from raises. This method, worked out at Copper Mountain, B.C., is believed to be distinct in many features from other known methods. GEOLOGY The ore deposits of Copper Mountain are related to the Copper Mountain stock, which is an ideal example of the magmatic differentiation in that it grades from a basic gabbro at the border to an almost pure orthoclase-pegmatite core. The "contact" ore bodies lie along the contact of the gabbro and an older complex of volcanics and sediment termed the "Wolfe Creek" formation. These older rocks, collectively referred to as greenstone, had been fractured prior to the intrusion of the stock and were highly metamorphosed during the intrusion. The "outlying" ore bodies are somewhat different in character, though a similar structural pattern prevails. It is believed that a deep-seated magma of which the Copper Mountain stock is a part has given off solutions that caused a partial granitization of some of the volcanics. Mining problems are caused further by the presence of a series of soft barren dikes intersecting a great many of the ore bodies, which are about 30 ft. wide, strike north-south, and dip at a high angle to the east; and are further increased by the presence of four major faults, with a great many minor faults running at acute angles from them. Fault zones average 8 ft. in width, and consist of gouge and breccia. They strike northeast and dip steeply to the northwest. The faults cut through the ore zones and the dikes, and continue on into the gabbro. The general mine structure with two types of ore bodies, bounded by weak walls and intersected by several series of soft barren dikes and major faults, indicated that a method of mining should be devised that would remove the ore at low cost with the least disturbance of the waste walls and dikes. THEORETICAL ESTIMATE OF STOPING WITH THE DIAMOND DRILL After consideration of various methods, the most suitable one appeared to be horizontal drilling to break the ore in a manner similar to shrinkage stoping. Drilling vertical holes or rings from a bench and breaking to an open slot was eliminated because the weak walls of ore, dike or waste would not permit this type of opening. It was then decided to drill either horizontal radial holes from a raise or parallel holes from a slot cut across the ore body. After discussion, the latter method was believed unsuitable, for the following reasons:

Jan 1, 1945

By Joseph C. McCaskill

The writer assumes that this volume is not intended to serve as a source of statistics on international trade and that the reader is not interested in wading through a lot of statistical tables copied from the various reporting agencies. Generalizations therefore are made whenever possible and not always is the source of the information meticulously cited. The United Nations regularly publishes trade data on mineral commodities. E. J. Gealy, and C. L Kimbell, of the U S Bureau of Mines (USBM), work with these data and estimate that they cover approximately 78% of total mineral commodities traded. In addition the General Agreement on Tariffs and Trade (GATT) publishes analyses of certain trade data The most complete report of production and trade in minerals 1s probably the international volume of the U.S. Bureau of Mines Yearbook The latest available edition is for 1968, and some of the data in this edition cover only as late as 1967. Unless otherwise stated, the source of data used in the chapter is this Yearbook Other staff members of the Bureau were most helpful and cooperative They are not to be held responsible for conclusions or points of view to be found in the chapter. THE NATURE AND SCOPE OF INTERNATIONAL TRADE The two and a half decades since World War II have witnessed an unprecedented growth international commerce The end of the war found the world economy seriously crippled. Many countries had suffered severe war damage; international trade was disrupted and nations had to resort to exchange controls and bilateral trading arrangements. The postwar recovery, however, was remarkably rapid Within two decades, world Income more than doubled, and world trade which was less than $60 billion in 1948 exceeded $200 billion in 1968, 8 and reached $278 billion in 1970.18 The growing world trade contributed to world prosperity which in turn fostered growth of trade. This dramatic growth of international commerce was made possible by the progressive liberalization of trade and capital movements by the major trading nations of the world which began immediately after the War and has not yet completely lost its steam. The modern-day stimulus of the expanded trade movement was the enactment by the Congress of the United States in 1934, of the

Jan 1, 1976

INCREASING realization that pouring and ingot-mold practices involve many factors of fundamental importance to ingot quality and general steel-mill operations has caused these phases of steelmaking to become major concerns of operators and metallurgists engaged in control of quality and costs. Methods of pouring steel from the ladle into the ingot molds have some direct effects on ingot quality. The mold itself governs solidification and dimensions of the ingot and in so doing exerts some very tangible influences not only on ingot quality but also on product yields and general steel-mill processing. In addition, practices are employed in the handling of molds during daily open-hearth operations that are important to quality and production costs. Therefore, pouring and mold practices must be considered highly specialized and important steps in steel-mill operations. MOLD DESIGN Mold design is difficult to discuss in a precise manner because it varies greatly throughout the industry, both in theoretical concepts and practical application, and few well developed data are available. Most ingot molds are designed to meet conditions peculiar to a given plant wherein quality standards are dictated by end-use requirements, which may differ considerably even for the same grade of steel. The mold designer must also consider the equipment available to process ingots and the product obtained from them. Such equipment, used for stripping, heating, blooming and finishing operations, is seldom, if ever, exactly the same in any two steel plants. Thus, pronounced contrasts in mold designs can be expected to continue, even among plants making strictly comparable types of product, particularly because some producers are just beginning to realize the benefits possible from specialized designs. Certain fundamentals are used in mold design but even these

Jan 1, 1964

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 E. C. Truesdale

A FEW years ago H. M. Cyr, working in the Research Laboratories of The New Jersey Zinc Co., produced a few pounds of zinc1 of such purity that no other elements were detected in it by spectrographic analysis, using the facilities then available. This zinc contained less than one ten-thousandth of one per cent of metallic impurities.2 During the decade that followed upon the laboratory production of this "spectro-graphically pure" zinc, commercial developments brought about the production of large tonnages of zinc of purity exceeding 99.99 per cent, and today zinc of 99.999 per cent purity is produced and marketed as "chemically pure" zinc. Typical analyses of present supplies of high-purity zinc are given in Table 1. TABLE 1.-Typical Analyses Percentage by Weight Sum of Zinc Pb, Fe, Pb Fe Cd Al Cd Special High Grades 0.007b 0.005b 0.0056 none 0.0106 C.P. (chemically pure) <0.0002 0.0005° 0.000052 S.P. (spectrographically pure).. <0.0002d <0.00005d a A.S.T.M. Standard Specification for Special High Grade Slab Zinc (A.S.T.M. Designation: B 6-37). b Maximum. c Fe chemically determined. Pb and Cd are spectrographically determined. d Differences between composition of C.P. and S.P. zinc are discussed later in this paper. The availability of commercial tonnages of special high-grade zinc has been the basis for the development of the zinc-base die-casting alloy industry which, in the year 1936, consumed one-eighth of the zinc used in the United States for all purposes. This and the C.P. and S.P. grades have given impetus to scientific investigations into the properties of pure

Jan 1, 1939

By G. Howell Clevenger

FORMERLY great divergence of opinion existed in regard to the influence of copper in steel, as affecting its various physical properties. More recently the investigations of Stead,1 Breuil,2 Wigham,3 Burgess and Aston,4 Ball and Wingham,5 Miiller,6 Dillner,7 and others have shown fairly good agreement in the major points. Copper steel has been shown by these investigators to possess special properties which make it valuable for certain uses. The general range of composition of the useful alloys of copper and iron, and of copper, iron, and carbon, has been quite definitely established, for the former by Burgess and Aston,8 and for the latter by Breuil 9 and Stead.10 Stead 11 has removed one difficulty in reconciling certain of the earlier data by calling particular attention to the influence of carbon in copper steels. Another point which caused confusion in the earlier investigations, particularly in regard to " red-shortness," was the presence of sulphur. Failure to note the presence of sulphur often led to attributing " red-shortness " to the presence of small amounts of copper. Turner 12 has called attention to the fact that where copper exists in an iron ore it often occurs as the sulphide, so that the presence of copper in steel made from such ores might also, necessarily, mean the presence of sulphur. It is evident that the effect in this case might be quite different than where pure copper was added.

Jan 10, 1913

By James D. McClung, H. J. Gluskoter, M. R. Geer

INTRODUCTION The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1 ) cleaning to remove inorganic impurities; (2) sizing-crushing or screening, or both; or (3) special treatment, such as dedusting. The properties and quantities of impurities in coal are of major importance in the design and operation of steam generating equipment. Al- though boilers are often designed and equipped to use a wide range of coals, no boiler will perform equally well with all types of coals. All coals have certain properties that place limitations on their most advantageous use. These limitations are especially stringent for many of the older installations. Because of a general lowering of quality of raw coal in recent years, the need for coal cleaning has significantly increased. Among the factors contributing to the need for increased coal preparation are (1) increased demand for quality brought on by market and environmental requirements; (2) increased extraneous dilution caused by mine, health, and safety laws; and (3) depletion of the higher-quality coal seams.

Jan 1, 1979

By William Kelly

THE objeet of this paper is to describe the electric equipment at the iron-ore mines of Penn Iron Mining Co., Vulcan, Mich. and of Republic Iron Co., Republic, Mich.; to give the result&apos;s of tests; and to discuss the methods in use from an operating as well as from an efficiency standpoint. Electricity was introduced at the Penn mines for pumping, hoisting, and compressing air in the spring of 1907, upon the completion of a hydro-electric plant built by that company on the Menominee river about 4 miles from the mines. This plant was described in a paper1 presented before the Lake Superior Mining Institute. A paper2 presented at a meeting of the same Institute describes some of the operating features, and the safety devices of the electric hoist at the Curry shaft were briefly described in the Proceedings of the First Co-operative Safety Congress held under the auspices of the Association of Iron and Steel Electrical Engineers at Milwaukee, Wis., Sept. 30 to Oct. 5, 1912.

Jan 2, 1914

By G. L. Oldright, T. B. Brighton, C. M. Dice

The base bullion from the lead blast furnace contains varying amounts of the impurities left in the smelter feed by the concentrator, regardless of the method of smelter operation. These impurities may be held in part in mechanical suspension rather than being present as true alloys. However, usually there is little free space in the crucible in which to separate these drosses before the bullion is taken from the lead well. When such a dross is melted in a laboratory crucible and allowed to cool, the products obtained are lead bullion, speiss, and matte in well separated layers. Typical analyses of layers are: Analyses. Per Cent Element Bullion Speiss Matte Pb.............................................. 92.0 41.2 38.3 Cu.............................................. 2.4 36.3 40.6 As............................................... 4.0 16.5 4.3 Sb............................................... 0.7 0.2 0.4 S................................................ 0.6 1.9 13.1 Fe............................................... 0.0 0.0 0.0 Totals......................................... 99.7 96.1 96.7 The absence of iron in these products drossed from the blast-furnace bullion proves that the impurities for the greater part are not simply finely divided blast-furnace speiss or matte that has been dissolved or dispersed in the lead, but are held in solution by the liquid metal and rise to its surface as infusible compounds when the temperature of the bath is lowered. In general, the drosses made locally are metal sulphides and arsenides and not oxidized compounds. The large content of metallic lead also does not seem to be retained because of oxidized compounds

Jan 1, 1937

By E. H. Crabtree, J. D. Vincent

Probably no metallurgical process in the history of the mining industry has been responsible for such increased mineral production as has flotation. It has made possible the economic treatment of low grade and complex ores which, with the old methods of gravity concentration, would have been classed as worthless. Starting with the sulfide ores of copper, lead, and zinc, the process has been applied to almost all metallic and nonmetallic minerals. Today, the sulfides of the common metals not only can be readily recovered, but can be separated from each other. Thus, three or four mineral recoveries from the same ore, such as galena, chalcopyrite, sphalerite, and pyrite, are possible. Molybdenite is recovered initially with copper sulfides and the two are subsequently separated. Flotation of metallic gold and of native copper and graphite is being commercially practiced. The carbonates of some of the base metals, principally those of lead, can also be concentrated. Flotation of the oxides, silicates, phosphates, and other so-called non- metallic minerals represents the greatest advance in the art in the last few years. Today, commercial plants are successfully treating such minerals as feldspar, garnet, ilmenite, muscovite, cassiterite, cement rock, fluorspar, phosphate rock, sylvite, and a host of others. Flotation of the various types of iron ores along with other concentration methods is today the subject of a tremendous amount of investigation on the iron ranges. EARLY PATENT HISTORY OF FROTH FLOTATION Although what we call the froth flotation process as distinguished from bulk oil processes was not used commercially until 1905, many investigators had recognized its possibilities long before the twentieth century. The principal patents issued throughout the years give us a method of recording early flotation history. BULK OIL PROCESSES: In 1860, William Haynes patented (British Patent 488) a process for separating oil-wetted sulfide minerals from water-wetted gangue minerals by agitating the dry ground ore with oil and then the mixture with water. In 1877, the Bessel brothers patented (German Patent 42, Class 22) a process where a mixture of graphite ore was mixed with 1 to 10% oil; after adding water, the

Jan 1, 1962

By Russell Dayton

THE metallurgical polarization microscope has been utilized in several researches in the last few years, thus attaining a fair degree of prominence, but little has been written in a manner suitable to a metallurgist concern-ing the theory of this instrument. In this investigation the theory was carefully studied, and the results are presented here in a detailed manner, yet as simply as possible. The theory is discussed with particular reference to the three chief functions of the instrument: (1) determination of anisotropy; (2) effect of strain; and (3) identification of inclusions. Each of these is investigated experimentally, with especial attention to the mechanism of producing any effect. Where possible, the discussion is supplemented by photomicrographs. The instrument used had numerous defects as a polarization microscope; these and their remedies are discussed. In the microscopic study of transparent mineral sections (chal-cography) the use of polarized light has aided tremendously in the identification of a mineral. The determination of strain in transparent substances (photoelasticity) by the use of polarized light has lately become a commercial process, used in testing finished glass articles. The success of the use of polarized light with opaque materials has not been so great. The magnitude of the effects obtained is much less than that of the corresponding effects with transparent materials, and the mechanical difficulties are much greater. Konigsberger,(1)? in 1909, was the first to apply polarized light to the microscopic study of

Jan 1, 1935