Search Documents

By E. W. Filer, R. P. Smith, L. S. Darken

The solubility of nitrogen gas in purified iron and low alloy steels is determined for the y region (930° to 1350°C). The diffusivtiy of nitrogen is estimated from the rate of approach to equilibrium. The investigation of aluminum-killed steels, held in nitrogen, discloses precipitation of aluminum nitride, the solubility of which is determined. ALTHOUGH several investigations of the solu-bility of nitrogen gas in y iron have been reported, all have made use of the method adopted by Sieverts in his classic work, whereby the solubility is determined by the pressure or volume change of the gas. The agreement between different investigators* is rather poor, particularly as compared to the self-consistency of results of several individual investigators. The present report represents a portion of our investigation of the equilibrium of nitrogen and nitrogenous atmospheres with iron and steels. The method adopted in this temperature region (910" to 1400°C) consists of holding the specimen in gaseous nitrogen, quenching (or cooling), and determining the nitrogen content by direct analysis (solution in acid followed by distillation and titra-tion of the ammonia).** Up to 1050°C a 20 in. vertical wire-wound (Kan-thal) furnace was used; this was wound in three sections so that by proper adjustment of relative currents, and use of a modulator1 and a commercial controller (using a chromel-alumel control couple), a zone almost 6 in. long could be maintained uniform within a few tenths of a degree. Since the temperature coefficient of the nitrogen solubility is low, the full precision was not utilized and a variation of l° to 2" was tolerated; a variation of a similar amount also occurred occasionally between the beginning and end of the experiment. At higher temperature a vertically mounted, tubular Globar furnace and control unit was used; the zone of uniformity (l° to 2"C) was here limited to about 2 in.; fluctuations with time were comparable to those in the wire-wound furnace. Reported temperatures were measured by use of a platinum-platinum-rhodium thermocouple, which was frequently com- pared with a similar standard couple which was calibrated at the gold and palladium points and also compared with one certified by the Bureau of Standards; error from this source is believed to be less than 1 "C. Nitrogen gas from a commercial cylinder was mixed with slightly over 1 pct H by use of a gas mixer described previously.' This mixture was passed over hot copper and through ascarite and phosphorus pentoxide to remove oxygen and water vapor. The purified gas contained 1.05 pct H. This procedure was adopted to prevent the formation on the specimens of oxide film, which is well known to be nearly impervious to nitrogen; its success was attested by

Jan 1, 1952

By George F. Weaton, Carleton C. Long, H. I. Najarian

Partial descriptions of the operation of the St. Joseph Lead Company's Joseph-town smelter have been published. In, 1936 the electrothermic production of zinc oxide was described;' in 1939 appeared a description2 of the electrothermic method of producing zinc metal. Inasmuch as the plant capacity has more than doubled, and in view of the fact that operating practices have improved greatly since these publications, it seems worth while to prepare a fresh description of the present-day elec-trothermic zinc plant and practice. Josephtown smelter is situated on the south side of the Ohio River about 3 miles below its confluence with the Beaver River. In addition to river barge, the smelter is served by Pennsylvania state highway No. 18 and by a spur line of the Pittsburgh and Lake Erie Railroad (N.Y.C.). A recent extension of this spur line connects with the Pennsylvania Railroad. As originally contemplated the plant was to handle only the product of the com-pany's own mines in St. Lawrence County, New york, but owing to the incessant demand for zinc and zinc oxide, it has been necessary to supplement New York concentrates with foreign ores (principally from Quebcc and the Argentine). The general operational procedure followed comprises roasting the sulphide con-centrates, converting the sulphur dioxide into sulphuric acid, preparation of a strong-structure sinter from the calcine, crushing &lid sizing of coke, reduction of coke-sinter mixture by electrothermic means, condensation of the evolved zinc vapor to make zinc metal or burning of the zinc vapor to make zinc oxide, collection and packing of the zinc oxide. Dusts recovered by the roaster and sinter Cottrells are treated in the leach plant for separation of lead sulphate, cadmium metal and zinc sulphate. The general flowsheet is shown in Fig. I. Principal Items OF Equipment Roaster Plant Concentrate drier, 6-ft. 'ia. by 4O ft. 5 in., countercurrent, direct gas-fired. 3500-~on concentrate storage in three vertical steel tanks. Five modified Nichols-Herreshoff twelve-hearth roasters, 21 ft. 6 in. in diameter. Four fans for shaft-cooling air. One threedrum Stirling water-tube waste-heat boiler, 4'8 hp., 200 1b. Per sq. in., with connections to upper and lower balloon flues. Direct gas-fired countercurrent rotary-kiln roaster for Cottrell dust. Necessary conveying equipment, described below. Instrumentation consists of: draft indicators, (3d hearth); various manometers; pyrometer served by thermocouples in each hearth, entrance and exit of waste-heat Joseph. entrance and exit of each hot Cottrell; roaster draft recorder and shaft air-pressure controller; temperature recorder and controller (10th and 12th hearths); SO* recorder (waste-heat boiler n

Jan 1, 1944

By Frank S. McKenna, Myron A. Pugacz, Clarence E. Jackson

THE notched-bar impact test has proved worth while in certain applications as a test for control of the quality or the heat- . treatment of steel. In view of the serious thought that even so simple a test as the tensile test, has evoked during the past years, it is not surprising that the notched- bar impact test should have inspired much experimental work. The correlation of the great number of data has not been successful, although steady progress has been made toward a better understanding of this test. Progress has been made, especially, in the isolation of the effects of the many variables that control the results. The stress system imposed on a specimen with a notch is so complicated and un- predictable that no simple evaluation of the test has been possible. Because of this uncertainty, many engineers hesitate to use the notched-bar impact test, and this attitude may well continue until a better understanding of the effects of the variables in the test are available. Without doubt, any additional data that may be presented should be accompanied by as complete a description of the details of test as possible, so that it may be added to the general fund of information that is to serve as the basis for the theory of the notched-bar impact test. The many factors that may control the test results have been pointed out repeatedly. The importance of the effect of the type and dimensions of the specimen has been recognized. Most of the work reported by American investigators has been limited to small- size (Charpy) specimens tested as a simple beam; two types of notches (Fig. I) have been commonly used. Considerable data have also been presented by many investigators using a small specimen tested as a cantilever beam; this commonly being called the Izod test. Here, however, a shear component of stress makes the stress system even mare complex than that present in the simple beam type of test, hence a critical analysis is difficult. Much work has also been reported by investigators using the tension type of specimen. A second variable that must be con- trolled is the testing temperature. An indication that the tests were performed at room temperature is not sufficient, since in many steels a variation of a few degrees in the actual testing temperature may be sufficient to give an entirely different range of results. Other factors. such as the com- position and condition of the material being tested and the speed of test, should also be considered. Many investigators have contributed data and theoretical discussions on the problems encountered in notched-bar test-

Jan 1, 1944

By Avnulf Muan, Egil Aukrust

The activity-composition curve for cobalt oxide in (Co,Fe)304 solid solutions with spinel-type stmcture has been determined experimentally by studying the equilibrium between the spinel phase and a coexisting cobaltowüstite phase, "(Co,Fe)O", at 1200°C. A large negative deviation from ideal behavior prevails in the spinel at low cobalt oxide concentrations and a positive deviation at high cobalt oxide concentrations. The activity-composition curve for iron oxide in the solid solution is determined from the above curve by integvation of the Gibbs-Duhem equation along the join Co3O4,-Fe3O4. The standard free energy of formation of cobalt ferrite, CoFe2O4, from the oxide components CoO and Fe2O3 is calculated to be -8.2 kcal. ThERMODYNAMIC properties of (CO,Mn)3O4 solid solutions with spinel-type structure have been presented recently.' The present paper deals with similar relations in another spinel solid-solution phase, that represented by the system Co3O4-Fe3O4. The principles involved in measurements and calculations of thermodynamic properties for the system Co3O4-Fe3O4 are analogous to those used and discussed in detail in the work on (CO,Mn)3O4. A (CO,Fe)3O4 solid solution coexists in equilibrium with a (Co.Fe)Ot solid solution over a considerable Here acOo1.33 and aao are the activities of cobalt oxide in the spinel and the oxide solid solutions, respectively, pO2, is the oxygen pressure of equilibration, and pb, is the oxygen pressure at which CoO and CosO4 coexist in equilibrium in the binary system Co-O at the same temperature. The activity-com position curve for cobalt oxide in the (Co,Fe)O solid solution in contact with metal has been determined in a previous investigation by the present authors.' The system shows a small positive deviation from linear behavior. Because of the large defect concentration in wiistite and in (Co,Fe)O solid solutions, one cannot assume that the activity-composition relations in the oxide phase coexisting with a spinel phase at relatively high oxygen pressures are the same as those prevailing in the oxide solid solution coexisting with metal. However, a Gibbs-Duhem integration over the ternary Co-Fe-0 solution can be used to determine activities of cobalt and iron, and hence of CoO and FeO, from a knowledge of the oxygen potentials. Several papers have dealt with the subject of application of the Gibbs-Duhem equation to multi-component systems. 3-6 In the present case, it was

Jan 1, 1964

By Gray L. L., Max Littlefield, Godbold A. C.

The West Edmond pool of Central Oklahoma, a limestone reservoir, has an area in excess of 29,000 acres and as of Sept. 15, 1946, had produced 53 million barrels of oil from 731 wells at an average depth of 6900 ft. Water has encroached into the reservoir along the west side of the pool and although the area of water invasion is large the net volume of water influx is small, because encroachment has been primarily into a fracture system. The most significant part of this study concerns the character of the Hunton reservoir. Geological study of cores of the producing section was made to supplement core-analysis data. It was determined that approximately 90 pct of the pore volume was contained in intergranular or sand-like porosity and 10 pct in fractures (intermediate porosity). The porous limestone is divided into blocks by the fractures, although in the strongly dolomitic parts of the producing section, fractures are less well developed. The low-permeability intergranular porosity, largely subsidiary to the high-permeability fractures, will produce oil into the fractures by evolution of solution gas. The fractures in effect serve as drainage channels for production of oil from the inter-granular porosity. Because of such a large difference in permeabilities of the two com-ponents, a high degree of by-passing will occur, and, accordingly, the economics involved in undertaking full-scale high pressure gas injection operations have been seriously questioned. Introduction The West Edmond Hunton pool, which covers portions of Canadian, Logan, Oklahoma, and Kingfisher Counties in Central Oklahoma, is the largest reservoir producing oil from a limestone in the state. The total area of the pool comprises about 29,240 acres and development is considered to be essentially complete. In all, 731 producing wells have been completed in the Hunton reservoir at an average depth of approximately 6900 ft, and have yielded a cumulative oil production in excess of 53 million barrels as of Sept. 15, 1946. In addition to wells completed in the Hunton limestone, 21 wells have been completed in the Bartlesville sand at a depth of approximately 6500 ft, which have produced a total of 730,000 bbl of oil. One small producer has been completed in the Cleveland sand at a depth of 5700 ft. However, a study of only the Hunton limestone reservoir will be presented in this paper. The most significant phase of this study concerns the special type of geological core examination that was made in an effort to ascertain the type and degree of porosity in the rock in accordance with lithologic types. Results of this geological study showed the west Edmond pool to be of such a complex nature as to appreciably affect the behavior normally associated with homogeneous reservoirs. Recognition of this condition in the

Jan 1, 1948

By Robert E. Green, T. Hinton

The velocities of the three possible modes of elastic-wave Propagation have been calculated for single-crystal aluminum at 1-deg intervals throughout the standard steveographic triangle. The results are presented as isospeed contours. The deviations between the direction of maximum energy propagation and specirzen axes are presented as arrows drawn within the standard triangle. The orientation factors associated with dislocation nzotion on the primary slip system only and also on all twelve slip systenzs have been calculated for all three elastic waves. The orientation factors associated with a longitudinal standing--7aue resonant specivnen hazle also been calculated. The relevance of these results to ultrasonic attenuation measurements is discussed. DUE to the widespread use of ultrasonics in the investigation of the properties of solids a number of authors15 have discussed in detail the theory of elastic-wave propagation in solids. In this paper the modes of wave propagation are evaluated according to the procedure suggested by reeen' for the case of single-crystal aluminum at 1-deg intervals throughout the standard stereographic triangle. The wave speeds are presented in the form of contour diagrams within the standard triangle. The deviations between the direction of maximum energy propagation and the normals to the wave fronts are presented as arrows drawn within the standard triangle. The orientation-de pendent factors (orientation factors) associated with dislocation damping as derived in the preceding paper6 have been calculated for the case of aluminum at 1-deg intervals throughout the standard triangle. The orientation factors for dislocation motion on the primary slip system only and on all twelve slip systems are presented in the form of contour diagrams, for both the traveling- and the standing-wave conditions. The relevance of these results to ultrasonic attenuation measurements is discussed. ELASTIC-WAVE PROPAGATION Three waves can be propagated in a linear elastic homogeneous anisotropic medium. The velocity of propagation v of each of these waves in a medium of density p can be obtained from the determination of the eigenvalues and eigenvectors of the matrix equa- The A's are a series of moduli which are functions of the elastic constants cij and the direction cosines 1, m, and n of the specimen axis. In the case of cubic single crystals where there are only three nonzero elastic constants cll, c12, and C, the A's are, The solution of Eq. [I] will give the wave speeds (eigenvalues) and the direction cosines a, 0, and y of the particle displacements (eigenvectors). To obtain the direction of maximum energy flux requires the calculation of the energy-flux vector ET with com- w is the angular frequency, A, the amplitude, and v the velocity of the wave. The direction cosines a, b, and c of the energy flux vector are then given by

Jan 1, 1967

By Max Littlefield, Godbold A. C., Gray L. L.

The West Edmond pool of Central Oklahoma, a limestone reservoir, has an area in excess of 29,000 acres and as of Sept. 15, 1946, had produced 53 million barrels of oil from 731 wells at an average depth of 6900 ft. Water has encroached into the reservoir along the west side of the pool and although the area of water invasion is large the net volume of water influx is small, because encroachment has been primarily into a fracture system. The most significant part of this study concerns the character of the Hunton reservoir. Geological study of cores of the producing section was made to supplement core-analysis data. It was determined that approximately 90 pct of the pore volume was contained in intergranular or sand-like porosity and 10 pct in fractures (intermediate porosity). The porous limestone is divided into blocks by the fractures, although in the strongly dolomitic parts of the producing section, fractures are less well developed. The low-permeability intergranular porosity, largely subsidiary to the high-permeability fractures, will produce oil into the fractures by evolution of solution gas. The fractures in effect serve as drainage channels for production of oil from the inter-granular porosity. Because of such a large difference in permeabilities of the two com-ponents, a high degree of by-passing will occur, and, accordingly, the economics involved in undertaking full-scale high pressure gas injection operations have been seriously questioned. Introduction The West Edmond Hunton pool, which covers portions of Canadian, Logan, Oklahoma, and Kingfisher Counties in Central Oklahoma, is the largest reservoir producing oil from a limestone in the state. The total area of the pool comprises about 29,240 acres and development is considered to be essentially complete. In all, 731 producing wells have been completed in the Hunton reservoir at an average depth of approximately 6900 ft, and have yielded a cumulative oil production in excess of 53 million barrels as of Sept. 15, 1946. In addition to wells completed in the Hunton limestone, 21 wells have been completed in the Bartlesville sand at a depth of approximately 6500 ft, which have produced a total of 730,000 bbl of oil. One small producer has been completed in the Cleveland sand at a depth of 5700 ft. However, a study of only the Hunton limestone reservoir will be presented in this paper. The most significant phase of this study concerns the special type of geological core examination that was made in an effort to ascertain the type and degree of porosity in the rock in accordance with lithologic types. Results of this geological study showed the west Edmond pool to be of such a complex nature as to appreciably affect the behavior normally associated with homogeneous reservoirs. Recognition of this condition in the

Jan 1, 1948

By Raymond Ward

IN the past few years several papers have appeared dealing with different aspects of the oxidation of dilute alloys, especially with respect to the formation of internal oxides or subscales. Subscale has been defined1 as that layer or zone of oxide particles precipitated in a matrix of metallic metal in which the oxide particles are dispersed uniformly and occur by diffusion of the oxygen inward from the metal surface. Alloys composed of a solvent metal more noble than the alloying elements are subject to subscaling or internal oxidation. In these alloys the solute must be present in such quantities that if the alloy is exposed to an oxidizing atmosphere at elevated temperatures, the rate of diffusion of the oxygen into the metal will be greater than the rate of diffusion of the solute outward. There is a composition range of the iron-silicon system that falls into this classification. Knowledge of the nature and rates of oxidation of iron-silicon alloys is of great commercial importance, but very little information of this nature is available. Darken2 recently has made calculations to show the limits of concentration of silicon for which subscales are produced in iron-silicon alloys; however, the main thesis of his paper was to analyze and to explain the already existing data. The purpose of this paper is to present the effect of com position, temperature, time, and atmosphere on the type of scale-metal layer obtained and to give some qualitative indication of the effect of these variables on the rates of oxidation. Since this paper is a study of silicon steels that are available commercially, extremely low-silicon and high-silicon alloys are not included. EXPERIMENTAL PROCEDURE The alloys used in the experiment were taken from heats of silicon steel that ranged in analysis from 0.70 to 5.8 per cent silicon. This composition range takes in most of the commercial silicon steels. In Table I are listed the compositions of alloys used. Other than iron and silicon, the alloys normally contained approximately the following impurities: carbon, 0.03 per cent; manganese, 0.07; phosphorus, 0.008; sulphur, 0.02; copper, 0.07; tin, 0.01, and from nil to a trace of chromium, nickel and copper. All of the alloys used were melted in open-hearth furnaces, except where otherwise noted, and were hot-rolled to 0.100-in. plate. Samples approximately 1/2 in. square were then cut from these materials. So that the surface conditions of the samples used for oxidation would be standardized, each sample was ground through 000 emery paper immediately before oxidation. Two different techniques were employed in carrying out the oxidizing treatments. One consisted simply of heating the samples with free access to air. In this treatment the samples were set on edge on a refrac-

Jan 1, 1945

By F. L. Bosqui

NO metallurgical process developed in the last half century has been more widely advertised to both technologists and lay- men, or has done more to promote efficiency and economy in the extraction of the valuable portions of ores than has the flotation process. Practically everybody has heard of this strange procedure whereby the heavy portions of an ore are made to float while the light parts sink. Some- times it is called froth flotation, the mineral-bearing froth being from the first a distinguishing characteristic. Many times it is called oil flotation, because a thin film of oil was commonly applied to the particles to be floated to make them adhere to the bubbles that rise through the pulp to form the surface froth. Oil, though commonly used, is not, however, necessary for this purpose, which is one of the facts that has been learned as the process has been developed.

Jan 1, 1940

By L. C. Graton

At the Tenth International Geological Congress, Mexico, 1906, Waldemar Lindgren presented "The Relation of Ore Deposition to Physical Conditions." Retrospect ranks it as the outstanding offering at that Session and as the most fundamental contribution up to that date on the philosophy of ore deposition. Elaborating thereon in his text-book "Mineral Deposits," Lindgren analyzed ore-forming processes under conditions prevailing from great depth up to surface; explained the nature of deposition in each environment; and developed a comprehensive genetic ore classification, which brought wide acceptance and enriching contributions by many. Since Lindgren's latest edition (1933), have come wealths of material relevant to ore genesis, particularly through amazing renaissance and proliferation throughout science. Current publication regarding ores now emanates largely from a generation caught in pressures of the breathless modern tempo, which tempts scant reflection upon earlier truths. Consequently, today's thrilling output contains not a few offerings that need challenge because supplanting interrelationship and system by what seems, collectively, an assemblage of strange, ad hoc and often self-contradictory concepts. From these latter some merit may eventuate but at the probable cost of present confusion and delayed progress. The following pages, naming numerous post-Lindgren advances, record the conviction, held by many, that Lindgren's philosophy, progressively improved, remains the soundest approach to understanding ore genesis.

Jan 1, 1968

By BARONJUPTNER VON JONSTORFF, Andrew A. Blair, GUNNAR DILLNER

IT is a well-known fact that the results of different analysts, when operating on the same identical sample of steel or iron, are far from concordant, and it not infrequently happens that great annoyance and trouble in the commercial community are occasioned by these discrepancies. Attempts have been made at various times to investigate the causes of such differences and to obtain more reliable methods of analysis. The most important of these was made by the British Association in 1889: The following gentlemen, with Sir W. Roberts-Austen as Chairman, and Professor T. Turner as Secretary, were constituted as a committee to investigate the question, viz.: Sir F. A. Abel, Mr. Edward Riley, Mr. G. J. Snelus, Mr. John Spiller, Professor J. W. Langley, and Professor Tilden. Average .samples of steel were prepared in America under the superintendence of Professor J. W. Langley. The steels, in the form of turnings, were divided and distributed to sub-committees in Great Britain, America, France, Germany, and Sweden. In Sweden Professor Åkerman acted as Secretary to the Swedish committee. The Government Department of Tests was appointed in Germany; Mr. Ferd. Gautier in France; the British Association Committee in England; Messrs. William

Mar 1, 1905

By William E. Hughes, Roderick K. Davey

The objective of this chapter is to review and discuss interpolation techniques commonly in use in the mining Industry today, including simple examples. This chapter will not attempt to compare the relative accuracy of each technique as this subject has adequately been covered by several authors (Knudsen and Kim, 1967; David, 1974; and Barnes, 1979) When appropriate, methods will be compared relative to the results of simple examples and computational ease. The examples presented are based on metallic deposits. The techniques, however, are not restricted to metallic deposits and can generally be applied to nonmetallic ones. The purpose of interpolation, as applied to a mineralized deposit, 1s to extend the knowledge of the grade and geology of localized samples to an estimate of the grade and mineralogy of a larger block of ground or even an entire deposit. The word interpolation means to compute values between given values and is limited to that region between the known values. The distinction between interpolation and extrapolation is important and must be adhered to in the application of these techniques in general, the interpolation must be limited to the area enclosed by verified samples. The methods being discussed can be broadly broken into three categories. ( 1 ) geometrical methods, (2) distance weighting methods, and (3) geostatistical techniques.

Jan 1, 1979

By H. OSBORG

THE patent literature of alloys for the last two decades or so indicates that the number of liatents referring to smaller and smaller percentages of essential alloying constituents is on the increase, whereas the number of patents relating to considerable percentages of alloying additions becomes smaller. The claims regarding physical properties indicate consistently higher and more rigid values and show the possibility of modifying the physical properties by only slight changes in the percentage of minor constituents or by applying different methods - of treatment. Alloys of the same base have been made suitable for a number of different applications by intelligently and rigid- ly controlling their composition, melting, casting, working, and heat-treatments. Other trends indicated in the development of modern alloys are higher corrosion resistance, higher fatigue limits, and "stability" in volume.

Jan 1, 1937

By WM. HUFF WAGNER

Computations and allowances for mine depletion for Federal income tax purposes depend upon the meaning of certain terms in the pertinent provisions of section 114(b) 4 of the Internal Revenue Code. Unfortunately, but one of these terms is defined in the Code. Congress left it to the Commissioner to define the other terms in the Regulations. Even though the Commissioner, through his staff, labored long and earnestly to draft these definitions they have not been satisfactory to the mining industry, because the definitions in the Regulations and the interpretation placed thereon by the Commissioner do not state what the industry believes to be the clear and obvious intent of Congress. Consequently serious and prolonged disputes, unduly delaying the settlement of Federal tax returns involving percentage depletion deductions are continually arising between taxpayers and the Commissioner.

Jan 1, 1949

By D. R. Mitchell

MEETING for the thirteenth time in New York as part of the five-ring circus known as the Annual Meeting A.I.M.E., the Coal Division experienced a wartime boom in attendance. Technical sessions were crowded and whereas 65 seats were set up for the annual luncheon meeting of the Division over 100 members showed up, many of whom had to be fed elsewhere. Possibly the Coal Division should adopt "13" as its lucky number. Discussions at technical sessions, formal and informal, were lively. Those papers containing material directly concerned with the war, or containing information that might be usable for war industries, were enthusiastically received. Some criticism was made in regard to the present method of handling discussions and it was suggested that better success would be had in getting discussions in the record by the use of hired reporters. This is being considered by the executive committee of the Coal Division.

Jan 1, 1943

By R. E. Allen, A. C. Jephson

ELECTROLYTIC zinc plants of the American Smelting and Refining Co. are located adjacent to the present city limits of Corpus Christi, Texas. The original plant commenced operations during 1942, and is designed for the production of special high grade zinc from zinc sulfide concentrates.' Subsequent changes include the erection of an additional acid plant during 1950, and additions for increased generating and production capacity during 1951. New Electrolytic Plant—The new electrolytic plant is a separate unit erected for the treatment of densified fume produced at Asarco plants located in El Paso, Texas and Chihuahua, Mexico. Construction was completed and operation commenced during June, 1953. Decision for the erection of a separate plant for the treatment of densified fume is based on several factors. One of the principal reasons is the assurance of continued production rate of the original plant, which might have been jeopardized by combined treatment of calcine and fume. Of equal importance is the advantage of locating a plant on a site with adequate space for eventual expansion. General Description—The new plant for the treatment of densified fume consists of four main buildings for the following operations: storage and grinding of fume, leaching and purification, electrolyzing and casting, and rectifier units. Auxiliary buildings include a baghouse, reagent storage, and a lunch room. Leaching of ground fume with electrolyte from the cells is a batch type operation in tanks equipped with mechanical agitators and weightometers. Completed leaches are pressure filtered, the resultant residue being recovered for shipment to El Paso by conventional use of thickeners, drum type vacuum filters, and a direct-fired dryer. Filtrates from the filter section are purified in mechanically agitated tanks, filtered after completion through plate and frame presses, and then pumped to an evaporative type cooling tower. Solution discharged from the basin of the cooling tower is collected in storage tanks for use in the cells. The cool purified solutions are pumped as required from storage to the solution circuit for circulation of electrolyte through the cells. Except for the addition of purified feed solution and withdrawal of electrolyte for leaching, the circulating system for the cells is essentially a closed continuous circuit that includes the use of evaporative cooling towers for control of solution temperatures. Aluminum cathodes and Ag-Pb anodes are used for electrolysis, which is maintained at a current density of about 82 amp per sq ft. Cathode zinc produced is melted in a gas-fired reverberatory furnace and then cast into slabs on a straight line casting machine. Unloading and Storage—Fume produced by the Chihuahua plant is shipped in box cars, and fume by the El Paso plant in hopper bottom dump cars. Shipments as received are weighed on a 7 5-ton capacity railroad scale, sampled, and then moved over one of the two unloading hoppers with a car puller. The cars are then unloaded with mechanized equipment, a car scoop being used for unloading of box cars and a car shaker for the hopper bottom cars

Jan 1, 1958

By Philip J. Shenon

IN 1947 the mining industry strove desperately to regain operating normalcy. During the first part of the year the industry in this country was plagued with labor shortages, strikes, and portal-to-portal lawsuits. Then followed the uncertainty of Government policy with respect to subsidies and tariffs; and the long and bitter controversy as to whether we are a nation of mineral "haves" or "have-nots." As the year progressed the labor supply impoved somewhat and the Taft-Hartley law brought partial relief to strike-troubled industry. The uncertainty with respect to tariffs was partly answered by President Truman on April 29 when he announced the suspension of the 4¢ import duty on copper until March 31, 1949, and later, near the close of the year, by the announcement of the tariff agreement signed by the United Nations at Geneva. By this agreement tariff rates are to be adjusted downward, or "bound" at their present levels, for three years, on commodities amounting to some 60 per cent of United States trade. Effective Jan. 1, 1948 the rate of duty will be substantially reduced on ores, concentrates, or metals of zinc, aluminum, copper, manganese, tungsten, iron, steel, barytes, nickel, cadmium, and antimony.

Jan 1, 1948

By David C. Jonson, W. Bruce MacKenzie, Arthur A. Bookstrom, Vaughn E. Surface, Neil K. Muncaster, Stewart R. Wallace

In mid-Tertiary time a wet silici-alkalic magma penetrated the Precambrian rocks of what is now the Tenmile Range of Central Colorado and formed the Climax Stock. The stock is a composite one and was intruded in four separate irruptions, each giving rise to a major hydrothermal event. The first three of these produced large stockwork ore bodies that cap and flank the tops of their respective source intrusives; the fourth, and last, yielded almost no commercial mineralization. The ore bodies and their related zones of alteration are circular to ring-shaped in plan and arcuate in section. The different phases of the stock are so positioned with respect to each other that many of the circular and arcuate zones of mineralization and alteration overlap or are juxtaposed. Evidence of a time separation between the different ore bodies is found in certain dikes that were intruded between periods of mineralization and are well mineralized in one ore body but are barren in another. If it is assumed that the parent magma at Climax contained 10 per cent "water," that the "water" contained 0.1 grams per liter of molybdenum, and that the processes of extraction were 100 per cent efficient, then approximately 10 cubic miles of magma would be required for the formation of each ore body. The volume requirements, taken in conjunction with the cross-sectional areas of the different phases of the stock to explored depths, suggest to the authors that each magma chamber was columnar, extended to a depth of thousands of feet, and was connected with a much larger master reservoir. The repetition of similar intrusive, structural, and hydrothermal events, indicates periodic tapping of this reservoir. A regular chemical evolution of the parent magma is suggested by the systematic change in metal ratios and differences in the sites of deposition, relative to the source intrusive, in each of the four separate igneous hydrothermal stages. The preparation of ground was due to changes in magmatic and/ or hydrothermal pressures within the igneous-hydrothermal columns; small, repeated, up and down movements of the rock enclosing the tops of the columns formed the stockwork fractures into which the mineralizers penetrated. The forceful emplacement of each successive phase of the Climax Stock resulted in a slight doming and rotation to the westward of the earlier-formed geologic features. Postore normal displacement along the Mosquito fault is estimated at about 9000 feet. Part of one ore body was cut by the fault and lies at depth below the Paleozoic sedimentary strata on the hanging wall. On the footwall side of the fault, subaerial erosion and glaciation removed a large part of one ore body and uncovered the top of a second.

Jan 1, 1968

By Fred C., Fred C. Bond

Comminution energy is principally energy of deformation before breakage, which appears as heat. An empirical equation is presented which covers the entire comminution range. The new strain-energy theory considers comminution from the known principles of mechanics and the reduction ratio. Energy requirements according to the different theories are compared.

Jan 1, 1950

By L. R. van Wert

CAREFUL research into the nature of the metallic state has yet to discover, with any certainty, its essential quality. We do riot yet know, for sure, what it is that makes the metallic elements different from, if not actually unique among, all created things. We do know, of course, that metals have certain more or less characteristic properties-they are hard, strong, and tough, and good conductors of heat and electricity, and these so-called metallic properties provide a definition of a sort. How- ever, it is the structure rather than the behavior of the metals which gives the really fundamental information necessary to the understanding of metallicity. But this information is not easily obtained. Nature has a way of keeping secrets. But happily we do possess some knowledge of how a metal is built up, and it is this matter, rather than the presentation of a formal definition, that will be discussed here.

Jan 1, 1937