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By R. J. Wasilewski

Electrical resistivity variation with temperature was measured on a series of alloys containting up to 33 at. pct of oxygen over the range 77° to1500°K. The resistivity behavior is highly anomalous and itzconsistent with simple metallic conduction. Both composition and temperature-depended resistivity singularities were observed. A few experiments carried out on Ti-N and Zr-O alloys indicate the presence of similar anomalies. These observations, together with the published data on effects of substi-tutional alloying on the resistiuity of titanium, suggest that the anomalies are inhevent in the electron structure of this group oj metals. The existence of two-band conduction, and a significant shift of bands relative to each other with temperature and/or the electron concentration are suggested. CONSIDERABLE advances have been made in recent years in the alloy theory of simple metals. Very little, however, is known about the bonding in transition metals and their alloys.&apos; Titanium, with its relatively few electrons, may be expected to show simpler alloying behavior than the more complex transition elements. Its alloys with the interstitial elements appear particularly attractive in an investigation of bonding characteristics because of a) the simple nature of the solute elements, b) the remarkable similarity between the equiatomic structures Tic, TiN, and TiO, and c) the extensive solid solubility ranges of oxygen and nitrogen in a titanium reported.2,3 The Ti-O system was chosen for the most extensive investigation because of the relative ease of preparation of suitable specimens. Since the main object of the work was to obtain data on the bonding and its changes on alloying, electron-sensitive properties were primarily investigated. The present work describes the investigation on the electrical resistivity-temperature-oxygen content relationships. A few experiments were also carried out at selected compositions in the Ti-N and Zr-O systems. EXPERIMENTAL Materials and Method. Polycrystalline specimens were prepared in the form of hairpin strips some 50 by 5 by 0.15 to 0.50 mm by direct metal-gas reaction. This was carried out by controlled oxidation followed by a homogenizing anneal at a higher temperature. All the test specimens were fully homogenized as judged from the uniform microstructure and microhardness. To avoid preferred orientation, each strip specimen was annealed in the ß range prior to the oxidation, this procedure assuring random orientation in the strip;4 hence any texture resulting from the oxidation reaction itself affected all the specimens to a similar extent. Titanium used was of high purity (66 DPN, 10 Kg load; major impurities 0,-43G ppm, N,-70 ppm, C-25 ppm, Fe-14G ppm). The solute content of the alloys was determined by weighing, after the reaction with a known amount of oxygen. The specimens in which the discrepancy between the volumetric and gravimetric measurements exceeded 2 pct (or 0.2 mg for the low oxygen alloys) were rejected. The mean between the two measurements was then taken as the oxygen content of the alloy. Check analyses showed no measurable nitrogen contamination. All oxygen contents are given in atomic percent. Zr-O alloys were prepared in identical manner from hafnium-free crystal bar metal, cold-rolled to strip 0.25 mm thick. Ti-N alloys required very long reaction times at the maximum temperature available (1250°C). In order, therefore, to detect possible oxygen contamination, duplicate specimens were reacted in every experimental run, and one of these was analyzed both for oxygen (vacuum fusion) and for nitrogen (Kjeldahl). Only the specimens in which the check analysis showed < 1000 ppm O were then used for resistivity investigation. Since only relatively high nitrogen alloys (7.1 at. pct; i.e., 2 wt pct N,) were investigated, this oxygen contamination was considered permissible. Dc resistance was measured by the four-probe method as previously described.= The temperature was determined with a calibrated thermocouple placed in the center of the specimen hairpin. The errors in the specimen resistance values thus obtained were estimated at 1 pct due almost exclusively to the finite thickness of the potential wires and the consequent uncertainty as regards the true resistance length of the specimen. For the calculation of the specific resistance, however, no dimensional measurements could be carried out on most of the

Jan 1, 1962

By G. Austin Schroter

ALTHOUGH there is now an extensive literature on the bleaching clays, not a great deal of material is to be found concerning the geological fea-tures of these deposits and their bearing on problems of exploration and development. At the same time, chemical and crystallographic research on the clay minerals during the past few years has laid a suitable founda-tion upon which to base conclusions of economic value drawn from field observations. All of the criteria and deductions herein presented are based upon extensive field work by the senior author, both in the United States and Canada, and when subjected to the ultimate tests of development and exploitation they have held up remarkably well, despite the fact that many of these conclusions apparently have not been reviewed in the litera-ture heretofore. The nomenclature of the bleaching clays is rather confusing in the light of present-day commercial standards and has even led to litigation.76 The old term "fuller&apos;s earth" is largely based upon trade usage and the definition of the term therefore is dependent upon the changing standards of commerce. For statistical purposes the Bureau of Mines81 classes as "fuller&apos;s earth" all natural bleaching or filtering claylike materials that possess high adsorptive capacity without previous chemical treat-ment or activation. Conversely, the so-called activated or acid activated clays are now generally recognized as any clay mineral or mixture of the clay minerals whose adsorptive capacity has been developed to commercial standards by chemical or physical treatment. Therefore, without attempting to propose any additions to the nomen-clature of bleaching clays, this paper will refer to naturally adsorptive clays and activable clays, respectively, for the two types indicated.

Jan 1, 1940

By Paul F. Kerr, Raymond F. Robinson

Uranium mineralization occurs in the footwall of the Sunshine vein from the 2900 to the 3700 level. Veinlets of uraninite associated with pyrite and jasper have been so extensively divided and recemented that units more than a few feet in length are seldom observed. The wall rock is St. Regis quartzite of the Belt series. The age of the uraninite, on the basis of isotopic analyses, is 750 * 50, which agrees with geological data suggesting that phases of the Sunshine mineralization are pre Cambrian. THE Sunshine mine in the Coeur d&apos;Alene district, Idaho, is well known for its silver-bearing veins but prior to the summer of 1949 had not been recognized as a possible source of uranium. At that time, during a geiger counter reconnaissance by T. E. Gillingham, R. F. Robinson, and E. E. Thurlow, high radioactivity was noted and radioactive specimens were collected from the footwall of the Sunshine vein.&apos; The detection led to the identification of uraninite-bearing veins, since explored jointly by the Atomic Energy Commission and the Sunshine Mining Co. After the occurrence was noted, the geology of the uranium deposit was studied by the Sunshine staff, and a laboratory examination of the ores was conducted at Columbia University. Several types of laboratory work were undertaken. Differential thermal curves were made of selected siderite samples and results from many more were secured through the work of Mitcham.2 X-ray diffraction and X-ray fluorescence analyses were employed on uraninite, jasper, and siderite. Chemical analyses were made through the cooperation of the Division of Raw Materials of the Atomic Energy Commission. General Geological Features Several silver-bearing veins cut the overturned north limb of the Big Creek anticline as mapped by Shenon and McConne1,³ while the Osburn fault, a long-recognized regional feature about a mile away, marks the north boundary of the Silver Belt. The Sunshine vein, Fig. 1, has a south dip more or less parallel to the 60" axial plane of the fold and cuts rocks of the Belt. Series, starting with the Wallace formation near the surface, continuing downward through the St. Regis formation, and probably extending into the Revett quartzite which lies below the bottom or 3700-ft level. The limb of the anticline is locally modified by secondary folds, one being prominently exposed in the uranian area along the Jewel1 crosscut near the Sunshine vein. Crumpling of the limb resulted from compression which formed the anticline and probably preceded the faults in which the vein deposits accumulated. Evidence of drag along these faults points to reverse movement in the uranium-bearing area and elsewhere. This is true of major faults in the mine workings, and the majority of faults which can be mapped, as pointed out by Robinson.&apos; The St. Regis formation, as measured in the mine, appears to have an initial thickness of some 2000 ft, but the apparent thickness due to thickening during folding is some 3400 ft. Along the Sunshine vein the purple and green rocks characteristic of the Wallace formation in the nearby Military Gulch section p. 37 of ref. 5) have been completely bleached because of introduced sericite. Hydrothermal solutions acting on the wall rock have substituted for the original color a pale greenish cast, although no pronounced mineralogical change has resulted, as Mitcham has observed.&apos; The silver and the uranium depositions appear to belong to distinct epochs resulting from several periods of emplacement. Likewise, multiple periods of deformation account for the faulting. Uraninite is generally associated with silicification, while silver . mineralization accompanies carbonate veins. Rarely, uraninite may be found in a matrix of siderite. Ordinarily uraninite formed prior to ar-gentian tetrahedrite. Where clusters of veins form a stockwork, uraninite-jasper veins often favor one trend while tetrahedrite-siderite veins favor another. During deformation, brecciation of the St. Regis quartzite provided openings between broken rock fragments for precipitation from vein-forming solutions. Fractures due to major breaks were filled during the first stages of vein formation, while later deformation displaced the first veins and provided new channels along which further mineralizing solutions proceeded. The uraninite veins, as the first formed, have suffered fracturing, displacement, and segmentation. Uranian vein segments uncut by faults and more than a few feet in length are rare or nonexistent. Siderite veins are more massive and often extend without a break for tens and even hundreds of feet. In general they show much less segmentation. While the siderite is usually later, there is an overlap in the periods of deposition, some earlier siderite veins being extensively segmented in much the same way uraninite veins have been broken. Vein silica is more extensively distributed than the uranium and iron mineralization it carries. Along the vein course concentrations of uraninite frequently fade away and barren white quartz continues, the transition often occurring within a few feet along strike or down dip. An example appears on the 3700-ft level where a uraninite vein, see Fig. 2a,

Jan 1, 1954

By Philip Lindstrom

T he Radon mine is in the north end of the Big Indian mining district in San Juan County, Utah. Hecla Mining Co. operated the mine from early 1955 to early 1964 through an operating agreement with Federal Resources, Inc. Development consisted of a 3-compartment, 690-ft shaft, 4 main levels driven on the ore horizon and a haulage level below the ore. Evaluation of physical and economic factors showed that this flat-dipping ore occurrence could be mined by a low-cost coal mining method. The value of the deposit was high and unusual pre¬miums were possible by clean mining. Complete extraction without loss of ore pillars, minimum ore dilution and high production per man were obtained by longwall mining.

Jan 12, 1964

By George B. Clark

7.1-1. Introduction. The fundamentals of blasting involve both the properties of explosives and of the rock being blasted. While the knowledge of property correlation between rocks and explosives for most effective blasting is far more complete, many quantitative evaluations have been made. Four of the most important explosive properties appear to be energy density, bulk density, rate of energy release, and the pressure-time history of the gases produced. Important rock properties are density and porosity strength, and energy absorption properties, including the effective moduli of elasticity. Rock structure also has a marked effect on its breaking properties, i.e., joints, bedding, fractures, alteration, etc. Several mechanisms enter into rock fragmentation by blasting. These include slabbing, radial fracturing, crushing, and bursting by the gas bubble. All of these factors are closely related to properties of both explosives and rock. Slabbing depends upon the character of the first generated stress wave, whose shape and magnitude are a result of the pressure generated by the explosive, its time history, and the resultant response of the rock, including its ability to sustain the stress wave. Actual slabbing, in turn, is a function of the magnitude and shape of the pressure pulse and the tensile strength of rock. Further fragmentation depends to a great extent upon the amount of gas in the bubble and its energy and pressure. Blasting rounds are best designed by taking the above factors into consideration. This is effectively accomplished by use of cratering curves which relate breakage- parameters to the explosive energy. Optimum depths from single charge cratering curves must be adjusted to changes in shot geometry and related to multiple hole blasting. Blasting damage may occur from either air blast or ground waves, and in the latter ease may be due to direct vibration or to settlement caused by vibration. Technical information indicates that blasting damage is often

Jan 1, 1968

By Robert S. Schecter, Mark P. Walsh, Michael J. Humenick

In recent years in situ leach mining has emerged as a viable technology for the recovery of uranium from strata in South Texas which contain relatively low concentrations of uranium ore. Because the ore bodies lie within ground-water aquifers, a significant determinant in the economics is the requirement that such aquifers be protected from contamination. Since ammonia is one of the constituents of the leach solutions now being field tested, one environmental problem to be resolved is the removal of ammonia at the end of mining. A second related question is the fate of the ammonia which is not removed by the restoration procedure. This paper considers the displacement and migration of ammonium in a flowing electrolyte with concomitant ion exchange. The ion exchange is an important feature since, during the solution mining phase, ammonium saturates the mineral exchange sites and must be removed from these sites. A mathematical model is used to simulate this process and the model is tested against the results of laborator.y experiments. It is found that the simulations are adequate if an appropriate selection of parameters is made. The model is then used to investigate the effect of cation composition and concentration of the restoration medium as well as dispersion on the overall effectiveness of the process. It is concluded that increasing the concentration of monovalent ions in a solution containing a mixture of both monovalent and divalent ions decreases the adsorption selectivity of the divalent ions with respect to all monovalent ions including ammonium. Thus increasing the ionic concentration of a restoration fluid by increasing the concentration of a nonselectively adsorbed (with respect to ammonium) ion may have a very limited benefit.

Jan 1, 1979

By N. J. Myers, S. J. Nemeth

POWER in the mill at Appalachian Sulphides Inc. is provided by 86 electrical motors ranging from 1 to 200 hp and totaling 1200 hp. After a careful study of different types of support for these cables an expanded metal trough was chosen as the most suitable. One hundred and twenty feet of trough were installed in 18-in. width and 150 ft in 6-in. width. This trough carries all the power as well as the control circuits. Now that the electrical distribution system is complete it is clear that this type of cable supporting system offers many advantages. To handle the same amount of cable in conduit, for example, would have required such a jungle that wiring all the different motors and controls would have been very difficult, even for the original hook-up. In the Appalachian Sulphides operation it has been necessary to make changes from time to time in the wiring of the different motors. These changes are readily made with the present cable supporting system because the trough leaves the wires accessible for rerouting as needed.

Jan 1, 1958

By W. M. Weigel

The general term "sand" applies to a multitude of similar materials consisting of fine granular mineral. As usually understood, it means the ordinary natural product used for structural purposes and made up largely of grains of quartz. Quartz sand constitutes by far the greater bulk of the production, but there are other grades used for industrial purposes, such as molding sand, glass sand and many others, that may be grouped under the general name of special sands. Under this general group would fall filter sand, sand-blast sand, engine sand, potter&apos;s sand, abrasive sands of all kinds, sand for pulverizing, roofing sand, flooring sand, fire or furnace sand, standard sand, burnishing sand, sand for magnesium oxychloride cement-plasters and sand for chemical and metallurgical purposes. Sources of Supply Sand is a widely distributed natural product and even the better grades are low-priced commodities. For these reasons development has occurred near points of consumption where sand meeting the requirements is available. Some special grades, however, cannot be prepared from any sand bed and shipments are often made over considerable distances when the only developed deposit is remote from the consuming center. This is true of filter sand, sand-blast sand, sand for pulverizing and some of the others when chemical purity or grain size, coupled with the need of a properly equipped plant for preparation, are required. New Jersey is a large producer of filter, engine, sand-blast, fire, and pulverizing sand. Pennsylvania, and West Virginia produce special sands for pulverizing, fire sand, abrasive sand, engine sand and sand for chemical and metallurgical use. Ohio produces much sand-blast, fire and abrasive sand, and some filter sand. Illinois and Minnesota produce

Jan 1, 1926

By C. Richard Tinsley, Norman Miskelly, S. James Hodge

Construction of the Ranger uranium project, located 230 kms east of Darwin in the Northern Territory, Australia, commenced in January 1979. Energy Resources of Australia Ltd (ERA) was incorporated in February 1980 to acquire all the rights in the project. The total cost to ERA of these rights was A$407 million, made up of A$125 million in cash to the Federal Government and the issue of 125 million A$1.00 shares at par, plus a payment of A$16 million in cash to each of Peko-Wallsend Ltd. (Peko) and EZ Industries Ltd. (EZ). ERA&apos;s cash requirements to complete the project were estimated in October 1980 to be A$553 million. Project loans, secured by first ranking debenture stock, were arranged for a total of US$390 million, while second-ranking debenture loans totalling A$60 million were [ ] obtained from the vendors, Peko and EZ. Overseas participants (power utilities who had agreed to purchase uranium yellowcake under contract) arranged to take up 25% of the equity capital for A$102.5 million; Peko and EZ were allotted 30.5% each as satisfaction of vendors&apos; consideration; and 14% representing A$57.5 million was issued to Australian residents in an underwritten public flotation in November, 1980. The loan and equity financing arrangements required the successful resolution of many complex and interlocking factors, including technical and economic feasibility, agreement with Aboriginal interests, compliance with Government policies, and securing of sales contracts.

Jan 1, 1985

By Norman Gerald

THE lack of a continuous operating balance in petroleum refining, which is analyzed in this paper, is by no means a feature solely of this division of the oil industry. Serious disequilibria of a capital as well as an operating nature exist both in the producing and marketing departments, while problems in the former and to some degree the latter are complicated by political involvements. Attention has previously been directed to the unstabilizing influence of present proration formulas in stimulating unnec-essary drilling.1 While equilibrium in petroleum refining operations has been fairly well maintained in the past decade, examination of departures may prove fruitful. Economic analysis is the application of time and motion study to the functioning of management, rather than labor. Properly applied it may reveal changes in policies that would increase the utility of the properties and facilities of the industry for stockholders, employees and the public, while contributing a stabilizing influence to the general economy. The study of economic equilibrium is essentially one of measurement and interpretation, requiring adequate data and the development of a tech-nique of analysis that employs statistical and mathematical methods as a supplement to the broad descriptive phase of economics. Economic equilibrium in petroleum refining is a dual concept. It embraces both the over-all balance between total storage and total demand for major products and the internal balance between the demands and inventories of the various products. The latter is the more complex of the two for it is concerned with proportionating the supplies of the several products stemming from the joint source to the demands for the individual products which are subject to wide variations. All the products are essentially nondurable goods, and they are used both by producers and consumers but in varying proportions. Motor fuel is very largely a consumer&apos;s good, while residual fuel oil is almost entirely a producer&apos;s good, the other products falling between these extremes. The peculiar-

Jan 1, 1939

By H. W. Kropholler, L. A. Cramer, E. T. Woodburn, J. C. A. Greene

A generalized mathematical structure is proposed whereby internal species mass flows within a flotation network are defined uniquely by a matrix of enhancement factors. An element of the enhancement factor matrix is defined as the ratio of the mass flow of that species leaving a given cell in the concentrate to the species mass flow leaving the same cell in the tailings. To predict the enhancement factors, knowledge of flotation kinetics effects is required. Recently experimental data has become available relating to the performance of industrial flotation circuits which indicate that the discrete or discrete-distributed kinetic schemes are capable of reasonably effective simulations. These simulations show the importance of including froth effects. The prediction of performance of networks from small-scale batch tests on flotation streams shows that the model for the froth phase used in the simulations does not scale-up well and that aeration effects are also difficult to predict. The network analysis should be useful in differential flotation of complex ores and it is disappointing-in this context that little information on the kinetics of activation and depression is available.

Jan 1, 1976

By Leo Dana

As a part of an investigation conducted by the Cement Section of the Bureau of Standards, at the plant of the Security Cement & Lime Co., Security, Md., the High-temperature Measurements Section was called upon to measure temperatures in a dry-process, coal-burning kiln. Although the measurements were made only under the conditions existing in one plant, the methods employed and the conclusions drawn apply, in a general way, to those existing in most plants. As far as we have been able to learn, no sufficiently thorough methods of making accurate pyrometric measurements in the sintering zone and in the rear end of rotary cement kilns have been described. It is believed that in this investigation, data were obtained that can serve as a foundation for further study of the problems of pyrometry in cement kilns. IMPORTANCE OF TEMPERATURE MEASUREMENTS IN ROTARY CEMENT KILNS The manufacture of Portland cement is today fairly well standardized. The various steps in the manufacture have been developed to such an extent that the process is almost automatic. In spite of these strides the efficiency of utilization of heat in the kiln is very low and an undue proportion is wasted; for example, about 50 per cent; ordinarily goes up the stack. In order to prevent these losses, not only should means be provided to utilize the waste heat but instruments, such as pyrometers, should be installed to study and control the operation with the view of minimizing the losses. At the same time, such control will produce a more uniform product. The saving in-fuel that may be effected by the proper use of pyrometers would be much more than their cost. Where these pyrometers should be installed and what they can show are very briefly indicated in the following paragraphs and discussed in greater detail later.

Jan 9, 1919

By James Norman

DIATOMACEOUS earth occurs in deposits widely distributed throughout the nation. The chief producing areas are in the Western States, where many high-grade deposits are known. Eastern deposits of diatomite are unsatisfactory for many purposes either because of impurity or because of the extremely fine particle size. Eastern users of diatomite, on the whole, must pay for transportation of the material from the west coast. The freight rate is necessarily high because of the great bulk of the diatomite. A satisfactory process of purifying the diatomaceous earths of Maryland and Virginia, which are unsuited for wide use only because of impurities, should be of value to eastern users. In the past, benefication of diatomite by wet processes has been limited to classification or sedimentation for the removal of sand from diatoms. Calcination with salt is used to produce a white diatomite when iron is present in the impurities, and small amounts of clay are rendered inactive in the process. No treatment has been developed whereby a large proportion of clay can be removed from a low-grade diatomaceous earth to give a diatomite of very high purity. In August 1937 the Federal Bureau of Mines, in cooperation with Dr. R. C. Williams, of Baltimore, undertook the problem of purifying low-grade Maryland diatomite by froth flotation. Work was done at the Eastern Experiment Station, College Park. Unless otherwise stated, the crude diatomite used was from the Patuxent River deposits near Dunkirk. This material, consisting of roughly one-third each of clay, quartz sand and diatoms, was representative of the usual low-grade marine diatomite found in the Coastal Plain Miocene beds of Maryland and Virginia and sporadically in other Atlantic coast states. As received, it contained 50 to 60 per cent moisture and probably had been wet since its formation.

Jan 1, 1940

By S. L. Payne, J. P. Morris, R. L. Kipp, G. R. Zellars

The activities of iron and nickel in liquid Fe-Ni alloys were determined by measuring the vapor pressures of iron and nickel above the alloys and comparing with the vapor pressures of the pure metals. Nickel was found to deviate negatively from Raoult&apos;s law over the entire composition range. Iron behaves ideally down to 0.7 mole fraction but shows negative deviations at lower concentrations. At 1600°C the activity coefficients at infinite dilution are 0.40 for iron and 0.66 for nickel. 1 HE formulation of the conditions of chemical equilibrium between liquid metals and gases or slags is an important application of thermodynamics to pro- cess metallurgy. Usually the metal and slag phases are solutions of several components; and for accurate calculations, it is often necessary to use the activities of the components in place of their concentrations. Data concerning activities, however, are quite meager. The evaluation of the activities of iron and nickel, presented in this paper, is part of a project to determine activities in iron alloys at elevated temperatures.

Jan 1, 1960

By C. E. Reinhard

A USEFUL accelerated weathering test should be capable of placing any series of metals quantitatively in the same order of endurance as that noted under a particular set of actual exposure conditions. The development of such a test must necessarily depend to a considerable extent upon data obtained from a wide variety of exposures. This paper offers preliminary data from exposure tests on nine metals placed in 11 locations in the Lehigh Valley, within a radius of 20 miles from Palmerton. The exposure conditions vary from a severe industrial atmosphere to a pure rural atmosphere. The data are offered as evidence of the necessity for the identification and evaluation of the variables of corrosion and as illustration of some of the variations to be considered in the development of a useful accelerated test. It is quite clear, from this evidence, that a useful accelerated test must be versatile to the extent of showing the probable variations of corrosion resulting from differences in atmosphere as well as from differences in the metals. The paper is presented solely with the object of pointing out the wide variations in relative merits of several common metals in resisting corrosion and without any thought of initiating controversy regarding the, merits of particular metals. For this reason the metals are designated only by symbols in the tables and no key is given to these symbols.

Jan 1, 1929

By R. H. Swallow, George Hess

C. G. BALL*—These maps are obvi-~,usly quite helpful in many types of mining engineering, but I want to find out if the prints which you obtain in the first step toward making any aerial contour map have already been corrected for tilt. Is that done afterwards only if you are going into the process of making a contour map ? GEORGE HESS (authors&apos; reply)— The tilt correction is the first step in either compiling the mosaic or compiling the total map. They must be corrected. C. G. BALL—But are the contact prints themselves corrected for tilt? GEORGE HESS—They are not corrected. E. R. KAISER†—I enjoyed this paper very much, and am glad to learn that the methods have a high degree of accuracy and are in use in the coal industry. Accuracy in dimensions is understandable from the paper. Would you tell us how accuracy can be obtained in the vertical dimensions by means of the photographs so as to permit drawing contour lines? GEORGE HESS—To explain our process, even in a limited way, is quite a large order. However, the basic principle involved is the measurement of parallax by viewing two overlapping photographs stereoscopically. It would almost be necessary to have the various instruments here on view to adequately explain their operation. E. R. KAISER—Are the elevations for reference obtained at more than four points ? GEORGE HESS—The pattern of control is four points obtained in the corners. Primarily. that is to restitute the picture and horizontalize it. The vertical control points are read ill on the stereometer and a direct comparison is made while draw- ing the contour lines. You do have to have those four points. But one stereoscopic pair of 5 ft contours has some 340 acres on it, consequently for every four points picked up 340 acres are contoured. E. R. KAISER—How does your method compare with that used by the military reconnaissance during World War II? GEORGE HESS—The Army did not get into this refined mapping. Most of their work has been reconnaissance mapping by taking one vertical and two oblique views. Basically, the same principle is used. Our maps are for engineering purposes. The Army was primarily interested in reconnaissance. E. R. KAISER—You could take more than 48 pictures in one flight? GEORGE HESS—Yes, the Brock camera accomodates 48 pictures per magazine. We are limited by the hours of greatest light, though, 2 hr before high noon, and 2 hr after high noon. Shadows do affect the picture. The shadows can-

Jan 1, 1950

By Chauncey Berrien

THE Hawkesworth detachable drill steel shank and bit were invented by A. L. Hawkesworth; while he was a mechanical foreman for the Anaconda Copper Mining Co., at Butte, Mont. Mr. Hawkesworth died on June 16, 1925, at the time that his invention was practically a proved success. The first application for patents was made by him in November, 1918, and the bit is now being manufactured under patents issued in 1922 and 1923. The credit, for its development in the early stages belongs to A. L. Hawkesworth, Roy S. Alley, Harry A. Gallwey, E. J. Bowman and various officials of the Anaconda Copper Mining Co. Later improvements, manufacturing problems and the direct usage in the mines were originated and perfected by the mechanical department under C. D. Woodward, E. R. Borcherdt, head of the Rock Drill Equipment Department, Robert E. Kelly of the Mechanical Department, and various operating department heads of the Anaconda Copper Mining Co. The author wishes to acknowledge the assistance of these officials in the preparation of this paper.

Jan 1, 1930

By E. J. Duggan

It is a coincidence that the two plants in this country for treating copper ores by ammonia leaching came into existence at almost the same time, that of the Kennecott Copper Corporation at Kennecott, Alaska, in March, 1916, and that of the Calumet & Hecla Mining Co. in July of the same year. The success of both from their very beginning attests the merits of the process under widely different sets of conditions. As would be expected, in the time they have been operating these two pioneers in this field have greatly perfected their methods and improved their technic. The early difficulties inevitably encountered in undertakings of this nature have been largely surmounted and the process may now be considered to be well seasoned and matured. There have been no other commercial plants built in this country and but one elsewhere, the Bwana M&apos;Kubwa in Northern Rhodesia, for the reason that this method of treatment may be employed on comparatively few ores. However, it has certain advantages, some of which are inherent to sand leaching processes generally and some to ammonia leaching in particular. Among these may be enumerated: (1) the avoidance of fine grinding; (2) the small amount of water required; (4) a high-grade product; (5) little likelihood of deleterious gangue constituents and fouling of solutions. It is true that great progress has been made in recent years in the flotation of the ores that come within the province of ammonia leaching. Nevertheless ammonia leaching has its possibilities and these may be overlooked in the present tendency toward the use of flotation for all ores. Probably the chief requisite to its further extension to suitable ores will be a cheap source of steam. Ammonia, the only reagent required, is unlimited in supply, readily transported and the price that is likely to obtain in the future should not make its cost at all onerous. Choice of Method for Kennecott Ores The Kennecott ores are typical limestone replacement deposits. The milling ores have a copper content of approximately 8 per cent in a limestone dolomite gangue. About half the copper occurs as sulfide, mostly chalcocite with some covellite, and the remainder in the form of the two carbonates, malachite and azurite. A comparatively coarse grind followed

Jan 1, 1934

By Robert K. Warner

Is an accurate measurement of the efficiency of a screen under a given set of operating conditions valuable? If so, what is the efficiency of a screen and how can it be measured? Sizing, especially of the finer sizes of material, has increased in importance in the development of flow sheets as a result of the perfecting of the rapid vibrating screens. More consideration should be given screens in the preparation of ball-mill feed, where they permit the admission of a dryer feed than the classifier. Where possible, the introduction of a screen ahead of the primary ball-mill, and the diverting of ore below, say, 4 mm. to a secondary mill, might result in a greater overall economy because of the thicker feed and the better adjustment of crushing media and mill operation to the reduction demanded. With the present trend back toward a combination of gravity methods and flotation, rather than flotation alone, the accurate, economical sizing possible with the new screens makes fine jigging a method to be considered. W. o. Borcherdtl and John Bland= discuss the screening problem and also the value of close sizing in the concentration of some of the rare-metal ores. If a screen is to be used, it should be selected in competition with others; other things being equal, that screen which makes the cleanest oversize should be preferred. The quality of the screening and the tons handled per dollar together determine the choice and, therefore, both of these must be accurately measured if a correct decision is to be reached. Too frequently in mill design, the capacity has been considered almost to the exclusion of the completeness with which the undersize is separated from the oversize. It is, of course, possible to increase the aperture of the screen, and thus insure the removal of a sufficiently coarse

Jan 1, 1924

By G. R. Heckman, H. J. Murphy, C. T. Sims

An incestigation has been made of the effects of heat treatment and alloy composition on the long-time stress-rupture properties and structural stability of the similar nickel-base alloys Udimet-500, Lrdimet-520, and Udimet-700. Rupture test data are presented at stresses ranging from 4 to 50 ksi at temperatures from 1450° to 1900°F for times up to 14,000 hr. Ductility response is emphasized. Optical and electron tnicroscopy were complemented by X-ray diffraction analyses of extracted phases to relate microstructural stability to the observed rupture properties. Particular attention is paid to Udimet-520 since structural characteristics of this alloy appear to vary somewhat from its sister alloys. Both cast and wrought performance of Lrdimet-500 are discussed. The computerized PHACOMP calculational technique, based on electron-vacuncy theory, is discussed and related to structural stability where appropriate. Electron microscopy and microprobe techniques were used to conduct evaluation of the oxidation characteristics of Udimet-500 exposed in air for 16,100 hr. The steady advance in strength and reliability of nickel-base superalloys continues to be one of the high points of modern metallurgy. The stress capability of these materials has increased steadily, allowing higher and higher operating temperatures in the highly sophisticated aircraft and industrial gas turbines now on the market. The attendant increase in efficiency, of course, means greatly improved power output. Gas turbines for industrial and marine use have long been designed with these objectives paramount the usual design requirements in terms of time of service being 100,000 hr. High-efficiency, long-life aircraft such as the supersonic transport require superalloy engine materials with high-strength and long-time structural stability. Thus, materials studied for and operating experience from industrial gas turbines provide a good reservoir from which technology of high value to the SST program can be drawn. This study is one such case. Three prominent nickel-base super alloys—Udimet 500, Udimet 520, and Udimet 700 were extensively evaluated for industrial gas turbine bucket use. Particular attention was directed toward structural stability as a requisite property. Within the present context, structural stability is defined as freedom from the propensity to form strength-robbing or embrittling phases such as u,p,x,or Laves, and the ability to maintain useful rupture strength and ductility throughout design life. MATERIALS The three alloys, cast Udimet 500 (U-500C), Udimet 520, and Udimet 700, were chosen for detailed evaluation based on preliminary studies which indicated that U-500C and U-520 possessed comparable rupture strength capabilities, and that U -700 had a greater strength capability but somewhat poorer ductility than wrought U-500. The nominal compositions of the three alloys, along with the compositions of the heats investigated, are presented in Table I. PROCEDURE Dimensionally rejected U-520 buckets from Special Metals Corp. heat 63370 were heat-treated using the four cycles delineated in Table 11. Cycle A was investigated to determine the effects of a shortened 1700°F primary age. Cycle B was considered a "standard" treatment. Cycle C investigated a higher solution temperature in combination with a shortened primary age, while cycle D assessed the effect of the higher solution temperature alone. These heat treatments were designed to produce optimum combinations of rupture strength and ductility through maximum y&apos; development, the development of a y&apos; grain boundary cushion, promotion of MC carbide degeneration reactions, and agglomeration of resultant M23CB. Since one of the premises of the evaluation of U-520 was that rupture strength would be equivalent to U-500, forged U-500 buckets from Special Metals Corp. heat 62916 were heat-treated with cycles A, B, and C to provide comparison. The heat-treated structures of U-520 and U-500 are illustrated in the 8700 times electron micrographs of Fig. l. The U-700 tested was all from 3-in.-diam hot-rolled and centerless-ground rod from Special Metals Corp. heat 2-1426. Two heat-treatment cycles were employed, E and F of Table 11. Cycle E is a standard four-step, triple-age treatment intended to provide an optimum match of strength and ductility through well-developed matrix and grain boundary y&apos;, as recommended by U-700 vendors. Treatment F is a shortened , single-age cycle which could provide a significant processing cost reduction should adequate strength and ductility be maintained. Following heat treatment, rupture specimens of U-500 and U-520 were machined from the buckets and tested. Standard rupture bars of U -700 were machined from the heat-treated rod and rupture-tested. Failed and withdrawn rupture bars were prepared and examined by optical and electron microscopy. Select specimens were electrolytically digested, and the residues analyzed for carbide and topologically close-packed phases using CrKa or CoKo radiation. Of the six different U-500C heats evaluated, five were cast by Misco Precision Casting Co. and one was cast by Haynes Stellite Co. Cast-to-size rupture bars

Jan 1, 1968