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By Roger N. Dokken

It is well-known1-4 that Fe-Si alloys from approximately 9 to 27 at. pct Si show an ordered structure of the Fe3Si type at room temperature. Recently Meinhardt and Krisement,' through an investigation of Fe-Si alloys at room temperature by neutron diffraction, discovered that at 10.8 at. pct Si ordering of the FeSi type occurs while above this composition the normal Fe3Si-type superstructure appears. This FeSi type of ordering was also found by Davies8 as indicated by X-ray diffraction measurements on an Fe-8.7 at. pct Si alloy. Meinhardt and Krisement7 extended their neutron-diffraction work and determined the phase-boundary temperatures for both FeSi- and Fe3Si-type ordering. Ordering phenomena can also be studied by resistance measurements.4,8-11 Krivoglas and Maty-sina" carried out a theoretical development of the

Jan 1, 1965

Secretary of the Interior, Franklin K. Lane, has appointed a commission of five mining and metallurgical experts from the Bureau of Mines and the Geological Survey to visit Europe to observe and study reconstruction methods in the devastated regions of France and Belgium. The chairman of the commission is Dr. Frederick G. Cottrell, chief metallurgist of the Bureau of Mines. The other members are: George S. Rice, the chief mining engineer of the same bureau; Frank H. Probert, consulting engineer of the bureau, and. professor of mining in the University of California; F. J. Cameron, consulting chemist of the bureau and expert on potash matters; and Hoyt S. Gale, of the Geological Survey, another expert on potash.

Jan 4, 1919

By T. I. Moore, L. A. Painter

THE electrolytic zinc plant of the American Zinc Co. of Illinois was described by Davidson' in 1944. Since then, improvements as well as expansion of the plant facilities have been made. In order to increase the production of high grade zinc which was needed for war purposes, an expansion program designed to double the slab zinc capacity was started in 1942 and completed in March 1943. This expansion was propagated by a contract between the American Zinc Co. of Ill. and the Defense Plant Corp. The contract included the facilities of the Fairmont City, Ill., property of the American Zinc Co., where a suspension-type roaster with contact acid plant, cadmium distillation furnace, Waelz oxide and densifying plant, and horizontal retort furnaces were installed. The expanded Monsanto, Ill., plant and the additional facilities of' the Fairmont plant were designed to integrate the metallurgical treatment of zinc concentrates for the production of special high grade zinc at Monsanto with the production of acid, cadmium, high grade zinc from furnace skimmings and the Waelz treatment of leach residue at Fairmont. In general, the original flowsheet was not changed, except for the addition of the filtering, drying and reclaiming of leach residue, and the treatment of purification cake for the recovery of copper, cadmium sponge, and zinc. Fig. 1 is a flow diagram of present operations. The original plant facilities, desi-gned for 50 tons daily production of slab zinc, had some units which were more than adequate. Therefore, in expanding the facilities to 100 tons per day, it was not necessary to double all operating components. Table I gives the comparison of the changes made in the unit operating components for the original facilities, 1941, the 1943 expansion, and the 1951 facilities. During the past 11 years a number of improvenients have been made resulting in: 1—an increase in slab production, 2—higher recoveries on the calcine treated, 3—better quality of slab zinc produced, 4—higher current efficiencies, and 5—less man hours Table I. Changes in Operating Facilities Operating Unit 1941 1943 1951 Calcine unloading (pneumatic), 10 tons per hr 12 calcine unloading track hpr. and elev., 60 tons per hr 1 Calcine storage, tons 1,000 2,000 2,000 Leach tanks, 35 vol. tons. No. 3 5 6 slurry mixing 6x6 ft stainless tank, No. 1 Ball mill. 4.5 rt x 16 in. conical. No. 1 CLassifier duplex, No. 1 1 Thickeners. 50 it diam. No. 2 9 2 Filter thickeners, sq ft '-- Moore filters, sq ft 5.760 11,520 Drum filters, 10 ft diam x 16 ft, No. 3 3 Rotary arlers, No. 1 2 1st stage Cu-As purificatlon tank. 90 vol. tons, No. 3 Solution heaters, No. 3 Filter press, 30x30 bronze, No. 4 Zinc dust purification tanks, 45 vol tons. No. 3 5 4 Filter press, 36x36 bronze, No. 3 5 3 Cadmium recovery plant: Process tank. No. 5 2 Cake roaster, 20 ft diam x 4 hearth. No. 1 Filter press, 24x24, No. 4 1 Sponge wash box, 4x6 ft, No. 1 Evaporative cooling unit (vacuum), No. 1 Purified storage tank, vol. tons 400 400 400 Cell acid storage, vol. tons 400 400 400 Electrolytic cells, No. 180 372 372 Cell room ventilation, cu ft per min 35,000 125,000 125,000 Cell cooling water. gal per min 1,500 2,300 2,300 Deep well 16 in. x 95 ft, 1500 gal per min, No. 2 3 3 Melting and casting furnace, 130 ton. No. I Furnace fume scrubber unit, No. 1 Dross drums, No. 2 Dross roaster, 8 ft diam x 8 hearth, No. 1 Electrolysis power conversion, kw 6,250 23,750 23,750 Power transformers, 13,800/440, kva 1,000 1,500 2,000 Steam boilers fire tube, 15 psi, lb per hr 12,000 18,000 18,000 Steam boilers water tube. 125 psi, Ib per hr 30,000 Air compressor, 2 stage. 300 cu ft per min. 100 psi, No. 1 2 Air compressor, 1 stage, 300 cu ft per min, 20 psi, No. 1 Vacuum pumps, 18x7, 720 cu ft per day, No. - - . Vacuum pumps, 24x11, 1.633 cu ft per day, No. 3 3 Building area, sq ft 60,854 113,568 115,000 per ton of metal produced. In the summer of 1944, the "reverse" leaching process was placed in operation and since it has been described,' no further description will be given. Other facilities and changes which have contributed to the process improvements were the scrubbing of fume from the melting and

Jan 1, 1953

By E. A. Gulbransen, W. S. Wysong

The behavior of molybdenum and its surface oxides in oxidizing and reducing gas atmospheres and in high vacua at elevated temperatures is a question of scientific and technical importance. The use of molybdenum as a metal or as an important component in alloys in oxidizing atmospheres at elevated temperatures has been limited because of the unprotec-tive nature of its oxide film and the volatility of this oxide at moderate temperatures. This communication will present results of a vacuum microbalance studyl, 2 of the following problems: (I) the oxidation kinetics in the temperature range of 250°to 450°C; (2) the reduction with pure hydrogen of thin oxide films formed on molybdenum; (3) the volatility of the thin oxide films; and (4) the vacuum oxidation of molybdenum at high temperatures. Molybdenum is an interesting metal to study for the following reasons: (I) although the oxide-to-metal-volume ratio is greater than one, the metal is not considered protective; (2) the metal oxidizes readily at temperatures of 2 50°C and higher; (3) the oxides of the metal are reduced at temperatures as low as 500°C by pure hydrogen; (4) the oxide Moo3 melts at 795°C; and (5) the oxides of molybdenum are volatile at moderate temperatures. The following variables are studied in the oxidation kinetics: time, temperature, pressure, surface preparation, surface area, concentration of inert gas in the lattice, cycling procedures in temperature, vacuum effect and high temperature vacuum oxidation. The general interpretation of many of these factors has been previously discussed. Literature The oxidation of molybdenum has not been studied critically. Although many studies have probably been made on the kinetics of the oxidation process, none has been reported in the literature available to us. The crystal structures found in the oxidation of molybdenum have been studied by Hickman and Gulbransen." Their results showed that Moo2 is the oxide which is stable in contact with the metallic substrate throughout the temperature range 300 to 700°C. As the film thickens in the low temperature range, MoO3 becomes predominant on the surface. Above 400°C, Moos is no longer observed, MoO2 being the only oxide found. Hagg and Magneli6 have shown from an X ray study that the a-phase, orthor-hombic Moo3 is stable up to 1050°C. Two other phases, ß and ß with compositions close to MoO2.90 are also obtained. The formula for the 0 phase is not given but that of the ß phase is defined as Mo9O26 The 0' phase is found to be built upon a monoclinic unit cell. A ?-phase is isolated from a preparation MoO2.75 heated for 17 hrs at 670°C. This phase is

Jan 1, 1949

By W. Bonfield

The microstrain characteristics of a polycrystal-line Cu 1.9 wt pet Be precipitation-hardening alloy have been determined for various conditions of aging. The friction stress remained constant for all the conditions investigated, whereas the microscopic yield stress (the stress to produce a plastic strain of 2 x 10-8 in. per in.) and the three-stage stress-strain curve in the microstrain region were sensitive to changes in dislocation and precipitate distribution. Correlations between the measurements of microplasticity and electron-nzicroscope observations of substructure are considered. ALTHOUGH the macroscopic mechanical properties of Cu 1.5 to 2.0 wt pet Be precipitation-harden ing alloys were established' in some detail, there has been no previous investigation of the nature of microyield-ing in these alloys. This paper describes a high-sensitivity extensometer determination of microplasticity in polycrystalline Cu 1.9 wt pet Be, in which the friction stress, the microscopic yield stress (the stress to produce a plastic strain of 2 x 10-6 in. per in.), and the rate of strain hardening in the micro-strain region were measured for various conditions of precipitation. The structural changes accompanying aging in this alloy were examined using transmission electron microscopy, a study which differed from previous investigations as, in order to minimize grain boundary precipitation effects,' the solution-treated alloy was cold-rolled to 40 pet reduction prior to aging. Hence the extent of recovery and recrystalliza-tion, as well as the variation of precipitate morphology and distribution, were assessed. From these results possible correlations between the microstrain characteristics and the observed precipitate and dislocation structure are considered. EXPERIMENTAL PROCEDURE The material investigated was a commercial copper beryllium alloy (Berylco 25), which had a com- position of 1.9 wt pet Be and 0.2 wt pet Co. The alloy was solution-treated at 800°C, quenched in water, and then cold-rolled to 40 pct reduction. Tensile specimens of gage length 1 in. and rectangular cross section of 0.18 by 0.06 in. were prepared from the solution-treated, cold-rolled material and aged for 15 min, 2, 24, and 100 hr at 315°C and 24 hr at 425°C to produce a range of precipitate structure. The hardness values associated with these conditions are listed in Table I. It can be seen that a maximum value is obtained after 2 hr at 315oC, which decreases with continued time at temperature to a minimum after 24 hr at 425°C. For comparison some as-solution-treated specimens were also aged for 2 hr at 315°C. The specimens heat-treated to a given condition were examined in two ways. First, the nature and distribution of the precipitate and dislocation structure was characterized using transmission electron microscopy. Thin foils were obtained from the specimens by electrolytic polishing in a 30 pet nitric acid-alcohol solution at -20oC, and were examined in an RCA EMU 3 electron microscope. Second, the mi-croplastic behavior of the specimens was measured with a Tuckerman strain gage, using the load-unload technique previously described2, 3 to determine the friction stress, the microscopic yield stress, and the variation of plastic microstrain with stress. RESULTS 1) Structural Changes During Aging. a) Annealing Processes. The solution-treated, cold-rolled Cu 1.9 wt pet Be had an irregular dislocation-cell structure,

Jan 1, 1968

By Carl Lee

CHICAGO in the last week of June fulfilled all its promises to the visiting engineers except one. This holds true with respect to the activities of the Regional Meeting of the A. I. M. E. in particular and of Engineers' Week in general. No one expected to find much of the beautiful in the outward aspects of the Fair-the Century of Progress Exposition, to be more formal; but they expected novelty, color, and startling lighting effects at night, and they were in no sense disappointed. It has been said that the architecture is a portent of the style of the buildings of the future; most who have seen the Fair hope that this forecast will prove inaccurate. As to the exhibits themselves, they are splendid. They are in keeping with the theme of the Exposition-a Century of Progress in science, in engineering, in the industries based upon them. No attempt will be made here even to suggest the exhibits that are most interesting. There are plenty for every one; and any member of the Institute who has the opportunity should by all means visit Chicago before the end of October.

Jan 1, 1933

By R. H. Richards, A. E. Woodward

In Rittinger's Aufbereitungskunde of 1867 occurs (p. 195) the following table, which shows the rate of falling in water of fragments of minerals, of irregular shapes and of five different specific gravities: Diameter of particles in millimeters. 10 8 6 4 3 2 1 .5 Sp. Or. Velocity in meters per second. Auriferous silver, 16..9 .8 .7 .57 .5 .4 .29 .20 Galena,. ..7.5 .62 .55 .48 .39 54 .28 .20 .14 Pyrites,. ..5.0 .49 .43 .38 .30 .26 .22 .15 .10 Quartz,. ..2.6 -30 .27 24 .19 .17 .14 .10 .07 Coal,. ..1.3 .13 .12 .10 .08 .07 .06 .04 .03 With the purpose of extending this valuable table, to cover a larger number of minerals and sizes of each mineral, and of making it more easy of application in deciding upon a sieve-scale for any group of minerals, we have prepared the curves of velocity of fall of bodies in water shown in Plates I., XI., 111. and IV., using Rittinger's formula V= 2.44d(8 —1) where V= velocity in millimeters per second. " D = diameter of particles in meters. " 8 = specific gravity of the mineral. These curves embrace a large number of specific gravities, and for each specific gravity the relation of the diameter of the mineral particle to the velocity of its fall in water is given for all diameters and velocities used in practice. The second diagram is an enlargement of the lower left-hand corner of the first, the third bears the same relation to the second, and in like manner the fourth to the third. Plate I, therefore, covers the work of the coarsest jigging 2 inches in diameter; and under

Jan 1, 1890

By AIME AIME

ALL technical men who are planning to visit the Century of Progress Exposition in Chicago this summer-and all reports indicate that it will be worth visiting-should try to be there during Engineers' Week, beginning June 26. At that time most of the national engineering societies of the country will hold important meetings in that city. Engineers will thus have an opportunity not only to see the Fair at a time when special programs have been arranged for their benefit, but will have the opportunity to meet their professional brothers and to attend technical sessions of direct interest to them. The A.I.M.E. headquarters will be at the Stevens Hotel, and it will be to the interest of every Institute member who expects to attend the Fair at that time to secure his accommodations as promptly as possible. A request to the Chairman of the Chicago Section, A.I.M.E., or to the Secretary's office in New York, will bring a copy of the program as soon as it is available, together with any in- formation desired about hotel accommodations or other matters. The Chairman of the Chicago Section is J. R. Van Pelt, and his address is Museum of Science and Industry, 1525 East 53rd St., Chicago.

Jan 1, 1933

By R. W. Parsons

The over-all apparent single-phase permeability of fracture-rock systems was studied using two different two-dimensional models. In a strict sense the results are applicable only to these models, yet may give some insight into real reseruoir behavior. The regular fracture-matrix model can have any number of regular fracture sets. All fractures within each set have the same orientation, width and spacing. The gross behavior is amlytically equivalent to that of an anisotropic permeable medium. In the heterogeneous fracture systems, individual fracture conductivities vary within a two-dinensioml network pattern. A computer program calculates the overall permeability after the conductivities are randomly placed in the network. The calculated permeability depends upon the distribution of these conductivities and the particular fracture pattern into which they are placed. Although detailed information on actual reseruoir fracture systems is not available, this study shows how some of the possible variables may affect obserued gross reservoir characteristics. INTRODUCTION Characteristics of reservoir rocks are determined by direct (core analysis) or indirect (logging and production tests) examination. Both methods, singly and together, are widely used in reservoir evaluations. For fractured reservoirs a problem exists in relating characteristics of cores to the in situ reservoir properties. Knowing fracture characteristics can be of value in determining production mechanisms. Because of the limitations of observation, the intimate details of a fractured rock system will never be known. One approach in analyzing fractures is to study the behavior of some conceptually simple models. The two models analyzed contain features which may be realistic, yet are mathematically tractable. Flow is considered in two dimensions only, with the plane of interest at right angles with the fractures. This concept represents the horizontal flow in a reservoir system with the fractures oriented vertically. Only single-phase, laminar flow is considered. The regular fracture-rock system permeability is calculable from a simple analytical expression. The heterogeneous system requires a computer program for calculating overall permeability.

Jan 1, 1967

By F. M. Lewis, J. E. Goodman

A larger, slow-speed, under-loaded ball mill and hydraulic classifier have almost doubled grinding efficiency at the lsabella mill. TENNESSEE Copper Co. operates two ore con-A centrators, the London and Isabella mills near Copperhill, Tenn. In 1948 and 1949 the small ball mills and rake classifiers in the London concentrator were replaced by one large ball mill and one hydraulic classifier. This new ball mill was designed oversize so that it could be operated at slower than normal speed. The proper operating conditions were established and the results published.' Later it was found that this mill operated more efficiently with a small ball charge." While this London grinding practice was being developed, the Isabella grinding circuit was not changed in any way. It remained a conventional two-stage rod mill—ball mill combination, the rod mill in open circuit and the ball mill in closed circuit with a rake classifier. Study of the data indicated that grinding cost could be lowered by converting to the London practice, but not enough would have been saved to warrant the expense of converting. No plan for improving this grinding operation could be developed. In 1953 this study was reopened when plans were made to increase the Isabella mill output from 1150 to 1500 tpd. At this time the grinding circuit consisted of a 6x12 rod mill followed by a 6x12 ball mill in closed circuit with a 6-ft rake classifier. Another 6x12 ball mill and 6-ft rake classifier would have been sufficient equipment and would have been the simplest and cheapest installation. However, this would have offered no improvement in grinding efficiency or operating cost. If, on the other hand, the grinding operation could be converted to the London practice, by installation of one large 101/2x9x9 tricone mill and a 10-ft hydroscillator,2 lower operating costs would justify the additional investment. Economics: Table I presents estimates for the two schemes for enlarging the Isabella mill. In the first scheme, column 1, one 6x12 ball mill and one 6-ft rake classifier were to be added. In the second scheme, column 2, the existing small ball mill and rake classifier were to be retired and one large mill and hydroscillator were to be installed. Estimated savings from the difference in operating costs made an attractive return on the additional investment for the large mill and hydroscillator. Actual costs of carrying out this plan are tabulated in column 3b. It will be seen that these costs follow the estimates in column 3a very Closely. The return on the additional investment is calculated from the difference in the operating cost in column 1 and the actual operating cost in column 3b. This too come very close to the estimate. Power and Steel: Power requirements and steel consumption for the rod mills and ball mills, both actual and estimated, are presented in Table 11.

Jan 1, 1958

By Cyril Smith

IN the study of the structure or the properties of a series of alloys or nonmetallic compounds, it is often advantageous to express the com-position not as percentage by weight, according to which the material is always made up and analyzed, but as the atomic percentage of the two constituents. The conversion from the one to the other is repre-sented by the formulas: 100A 100x Y x 100 ? x/A A [1] A+ B x + A/B(100-x) X _ 100yA 100y [2] yA+(100-y)B or y+A(100-y) where x and y are the weight and atomic percentages respectively of the element of atomic weight A, and (100 - x) and (100 - y) are the per-centages by weight and by atoms respectively of the element of atomic weight B. While calculations according to these formulas are simple, they are' time consuming if several conversions have to be made. In 1931 Water-man' constructed a nomograph for performing the conversion, but this did not permit an accuracy greater than about 1 per cent to be obtained in the neighborhood of 50 per cent. Olander2 has proposed a graphic method simpler than Waterman's and one that gives a uniform precision throughout the entire scale. The possible accuracy is about 0.5 per cent of the whole, depending on the size and accuracy of the coordinate paper used. Recently, Hermann3 has described a slide rule for making the calculations. These devices make use of the simple rearranged equation:

Jan 1, 1933

By Ernest F. Burchard

A Reconnaissance of the manganese- and chrome-ore deposits of Cuba was made by the writer, as a representative of the U. S. Geological Survey, in company with Mr. Albert Burch of the Bureau of Mines, under instructions of the Secretary of the Interior, in the spring of 1918. The Cuban Government courteously detailed Sr. E. I. Montoulieu, a mining engineer connected with the Treasury Department, to act as escort and associate throughout the work on the island. The object of the study was to obtain authentic information for use of the United States Government as to the location, character, quantity, and availability of the manganese- and chrome-ore deposits in Cuba. Accordingly, the work comprised examination of such deposits as seemed to be of promise, without regard to stage of development, with a view to a determination of the quantity and quality of ore likely to become available for shipment during 1918 and 1919, and of the tonnage of ore in reserve. Wile it was possible to visit most of the deposits that seemed to be of promise, there was not sufficient time to visit all that were brought to our attention, some of which may have merit. Moreover, the necessity for paying particular attention to the ore deposits and the mines precluded the possibility of making more general studies of the geology of the region, and of making satisfactory collections of country rock and of fossils, and so for other details as to the geography and geology of Cuba the reader is referred to the report by Hayes, Vaughan, and Spencer.l Mr. Burch returned to the United States about 10 days in advance of the writer, who continued, in company with Sr. Montoulieu, investigations of reported deposits in Pinar del Rio, Matanzas, and Santa Clara Provinces. On his arrival in Washington, Mr. Burch submitted to the Director of the Bureau of Mines a summary of the results of the work to date. Later the writer published, as Press Bulietin 190. 380 of the U. S. Geological Survey, a statement concerning the chrome and man-

Jan 1, 1920

By AIME AIME

PLANS are now well advanced for the joint meeting of the Institute and over a dozen other engineering societies in Chicago during the week beginning June 26: Engineers' Week at A Century of Progress. All engineers planning to visit the Fair will find it to their advantage to be present at this time so far as the Chicago attractions are concerned, and Eastern members will also have the advantage of special transportation arrangements on June 24 and 25. The tentative program is given at the bottom of the next page. Monday morning, June 26, will be reserved for registration of members and guests and the Woman's Auxiliary at the Stevens Hotel, where special rooms will be provided. A luncheon will also be served there, and in the afternoon, a technical session on nonmetallics. Instead of having the big family dinner that evening at the Stevens, as at first proposed, the local committee has planned to have it at the Fair Grounds, where special facilities have been arranged. A meeting of the Board of Directors and a few invited guests will precede the dinner. All members and guests are likely to be interested in visiting the Museum of Science and Industry, so that will be the sole event on the program for Tuesday morning, June 27. The big attraction there at present is the model coal mine, the first operative coal mine ever built for exhibit purposes. It is based on the Deutsches Museum mine at Munich, but goes far beyond that in realism, and takes the visitor on an extended tour underground. It shows him in half an hour more types of modern mining machinery and coal geology than he would be likely to see in a week's underground study in the coal fields. The Institute members will be the first group to go through this mine.

Jan 1, 1933

By Edward H. Robie

Jan 1, 1971

By AIME AIME

FIVE days, extending from Monday, Feb. 18 to Friday, Feb. 22, inclusive, will be required for the annual meeting this year. The first fours days will be devoted to reading and discussion of papers, general and committee business meetings, two lectures, luncheons, dinners and all the pleasures of a big, general reunion. The fifth day will be given over to an all-day excursion for both men and women by special train to West Point, in celebration of the birthday of the first President of the United States. Washington having been an engineer and now after one hundred and thirty-one years the country having selected as President another engineer in the person of Herbert Hoover, our own past president and honorary member, it is proposed to celebrate with a good old-fashioned picnic and inspect the school. The authorities at the Military Academy have undertaken to welcome the engineers and do whatever they may to make our pilgrimage notable. Other social features planned for the week are numerous. Luncheon will be served as usual at the building each day of the meeting to all members and guests. This year a very nominal charge will be made, primarily to overcome deficits due to irregular attendance. Monday noon, the Non-metallic Minerals Committee will lunch at the Engineers' Club and in the evening the Milling Methods Committee will dine there. The Annual Smoker will be held at Hotel Astor after dinner. Professional entertainment of high order is promised, but not too much to interfere with the numerous group reunions that characterize this func- tion.

Jan 1, 1929

By Cyril Smith

IN the study of the structure or the properties of a series of alloys or nonmetallic compounds, it is often advantageous to express the com-position not as percentage by weight, according to which the material is always made up and analyzed, but as the atomic percentage of the two constituents. The conversion from the one to the other is repre-sented by the formulas: 100A 100x or 1 x/A+100-x/B B(100-x) _ 100yA 100y [2] X. yA + (100 - y)B or y (100 - y) where x and y are the weight and atomic percentages respectively of the element of atomic weight A, and (100 - x) and (100 - y) are the per-centages by weight and by atoms respectively of the element of atomic weight B. While calculations according to these formulas are simple, they are time consuming if several conversions have to be made. In 1931 Water-man1 constructed a nomograph for performing the conversion, but this did not permit an accuracy greater than about 1 per cent to be obtained in the neighborhood of 50 per cent. Ölander2 has proposed a graphic method simpler than Waterman's and one that gives a uniform precision throughout the entire scale. The possible accuracy is about 0.5 per cent of the whole, depending on the size and accuracy of the coordinate paper used. Recently, Hermann3 has described a slide rule for making the calculations. These devices make use of the simple rearranged equation

Jan 1, 1933

By Frank Armstrong

ALL the mining machinery of the Penn Iron Mining Co. has been operated by electric power for several years and when another shovel for stockpile loading was required the advantages of an electric shovel were naturally considered. After considerable study, serious objections suggested themselves the use of a shovel operated directly by electrical apparatus by reason of the complicated control, severe service on the motors FIG. 1.-ELECTRO-HYDRAULIC SHOVEL FIG:. 2-THE SHOVEL AS IT WAS OPERATED CINDER CONSTRUCTION. THE FIRST YEAR. and the heavy surges of current required from the line. It was finally decided to construct an electro-hydraulic shovel using water under pressure to perform all the necessary operations except that of propelling, for which a separate motor was best suited. A car body with boom, dipper handle and dipper of late design, but without any of the steam machinery, was purchased. A motor-driven centrifugal pump, a pressure tank, an air tank, a small air compressor and water cylinders with plungers, pistons and valves, were installed in place of the; steam equipment. Fig. 1 shows this shovel under construction and Fig. 2 shows it as it was operated during the first year, the summer of 1914. The large tank at the back of the car, in Fig. 1, carried air under

Jan 2, 1916

By M. W. BERNEWITZ

IT is 27 years since I last visited Broken Hill, New South Wales, one of the world's greatest lead-silver-zinc districts. Then, the flota¬tion of ores was in its infancy. The Minerals Separation process had its birth as a practicability in the Central Mill, which is still operating and yielding high recoveries. The average Australian knows that Broken Hill is an important mining center in a "corner" of New South Wales, but he does not know what a factor it is in the lead, silver, and zinc production of the world. Nor does he realize that among the ramifications arising from metal production at Broken Hill are the great lead smelter at Port Pirie, South Australia, 254 miles southeast; the electrolytic zinc works at Risdon, and the limestone mine at Davenport, Tasmania; the acid works at Cockle Creek, New

Jan 1, 1935

By R. E. Hudrlik, G. W. Preckshot

The diffusion coefficients of silver from solid silver in molten lead were measured to within ± 0.8 pet in a columnar type diffusion cell ower, the temperature range of 326° to 530°C. Fick's law describes the process up to 530°C where the laminar mechanism appareltly breaks down. These is negligible resistance at the interface as shown by mathematical analyses. The diffusion coefficients are found concentration independent. IT would seem that diffusion in liquid metals would be free of such effects as molecular structure, dissociation. polarization. and compound formation. This view was taken by Gorman and preckshot in their study of diffusion of copper from solid copper into molten lead. They reported diffusion coefficients which were independent of the concentration over the range of 478° to 750°C. They found that the Stokes-Einstein equation with constant radius of the diffusing specie represented the diffusion data better than Eyring's rate theory equation and Sheibel's correlation. The radius of diffusion was found to be that of the doubly charged copper. There appeared to be no resistance across the solid-liquid boundary. In the present work the diffusion coefficients for silver in liquid lead were measured over a range of temperatures of 350° to 505°C. The solubility of silver in lead over the range of 303° to 630°C was also obtained. These results are compared with calculated or correlated values or with data in the literature. EXPERIMENTAL Procedure—The experimental equipment techniques and procedures were those reported in detail by Gorman and preckshot9 and will not be repeated here. Measured values of WT, Co, A. L were obtained for various diffusion times and the diffusion coefficient was computed for the case of no resistance at the interface9, 11 by: WT/CoAL = 1- 8/p2 n=1 1/(2n - 1)2 exp[-(2n - 1)2p2 Dt/4L2] [1] or where there was resistance at the interface by: WT = 1- ?n=1 2h2/ap2L [sxp [-Dan2t]/[(h2 + an2) L + h] The roots an are those of the transcendental equation3 tan (an L) = Iz/cun. The diffusion coefficient is that defined by Hartley and Crank.7 The total silver in the lead cylinder and equilibrium slug was determined by a cupellation technique' with proper correction for losses. Analysis of known samples showed that this method is surprisingly accurate. The amount of silver in the lead adhering to the silver cylinder was obtained in the same fashion as shown by Gorman and preckshot.9 The small errors involved in this determination are not critical since the silver in this adhering lead layer is only 3 to 15 pet of the total diffused. Materials—Electrolytic silver containing 99.9+ pet Ag obtained from General Refineries of Minneapolis, Minn. was used for all but runs 7 and 8. For the balance of the runs this silver was reduced with hydrogen at 1100°C and its oxygen content was found to be about 0.017 pet. For the runs. 7 and 8, phosphorous-reduced silver of the same purity was obtained from Handy and Harman Co. of Chicago, Ill. The densities of the phosphorus-reduced silver and the hydrogen-reduced electrolytic silver were 10.484 and 10.487 g per cm3, respectively. These values agree with those reported for pure silver. Silver which was reduced at 900 C had an average density of 9.998 g per cm3, indicating porosity. This silver was used for a number of runs which were not tabulated in Table I. These are indicated by crosses on Fig. 2. The 99.999 pet Pb was obtained from the National Lead Co. Research Laboratory of Brooklyn, New York. DISCUSSION OF RESULTS The diffusion and solubility results are reported in Table I for eleven runs using either phosphorus-reduced electrolytic silver or hydrogen-reduced silver at 1100° C. The solubility data shown in Fig. 1 show the excellent agreement with that reported by Heycock and Neville.8 The data of Friedrichs5 apparently are in error. The experimental solubility data of this work are reported to 0.3 pet. The experimental diffusion coefficients computed from Eq. [1] are reported within 1.2 pet of the mean and are plotted in Fig. 2. These are expressed within +0.8 pet of the experimental values over the entire temperature range by: D= 8.26 x 10 -5 e-1925/RT . [3] There appears to be little difference due to the

Jan 1, 1961

By F. A. Seward

A1though the expanding Eltran1 configuration has been used in induced polarization exploration for several years, there has been little application of this method to straight resistivity problems. A comparison of results of resistivity exploration by this technique versus those obtained from Wenner configuration surveys reveals a number of advantages in interpretative resolution as well as in field operation. The application of electrical resistivity to ground-water exploration is well known.= In the past a major portion of this work has been accomplished by use of one or more variations of a technique employing the Wenner3 electrode configuration. With the introduction of the frequency domain technique of induced polarization measurements, used primarily in the exploration for disseminated sulfide deposits, there arose the need for an electrode configuration by which potentials could be measured externally to the current electrode spread in order to minimize coupling between current sending and potential receiving circuits. It was also deemed desirable that the configuration would provide information laterally along profile as well as with depth. To reach these objectives the expanding dipole-dipole configuration (which probably first was used in the electrical transient method of exploration and from which the name 'Eltran' was derived) has been adapted to induced polarization exploration. The author has successfully applied the same techniques

Jan 1, 1963