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By P. W. Bridgman

Flow and fracture are admittedly complicated phenomena of which we are yet only partially masters. There is not even nni-.persal agreement as to the details of the language best adapted merely to describe the phenomena, to say nothing of any theory. Certain points of view, however, are widely held, and there are certain general expectations as to what sort of procedures will prove permissible. A complete description of any situation involving fracture would demand a complete history of all the variables in the control of the experimenter. The experimenter endeavors so to choose his independent variables that they are adequate to determine completely the situation in the sense that when an experiment is repeated on the same initial material and with the independent variables running through the same sequence, all the other measurable properties of the system will also run through the same course. It is, I think, the universal conviction that when we are dealing with phenomena of flow and fracture, the most important of the necessary variables are the external forces acting on the various parts of the body; when the force history repeats, with certain obvious restrictions such as that temperature must be constant and non-mechanical forces, such as magnetic field, must be small enough to be ineffective, then the history of all measurable properties will repeat; in particular the alteration of geometrical shape due to flow will run through the same course, and when fracture comes, the character of the fracture will be reproduced. Complete mastery of merely the descriptive aspects of flow and fracture would demand the ability to predict the entire course of flow and complete characterization of the final fracture for every possible combination of forces, varying in time in all possible ways, when applied to bodies of all possible shapes. This full situation is obviously of prohibitive complexity. The first stage in reduction to manageable simplicity is to resolve the total situation into the sum of contributions made by small elements. Our thesis is that if each of the elements is adequately characterized, the behavior of the whole system is fixed. The element is usually taken of a simple geometrical shape, suggested by the mathematics best adapted to the particular situation. The forces acting across the faces of the elements are ultimately determined by the forces acting across the free faces of the whole system. The detailed process of finding the precise forces on the faces of all the elements in terms of the external forces involves the use of a special mathematical invention, the stress, a constructional quantity consisting of six components. The stress at any point in the body is determined by both the external force system and by the physical properties of the body at all points; quite different stresses prevail at the interior of bodies of the same shape under the same external forces in the elastic and plastic ranges. The forces on the faces of any element are, however, uniquely determined by the stress system at the element. Our fundamental thesis

Jan 1, 1945

The total crude production from the Dutch East Indies, and the British Protectorates of Sarawak and Brunei for 1932 is given in the following table: Production, which had shown a rapid increase from 1921 to 1929, has since been reduced. Exploitation drilling in the majority of the larger fields was suspended and existing production kept within predetermined limits by beaning. Most of the smaller fields were shut down entirely. The depth of producing levels varies widely in the different fields. Shallow fields with drilling depths to 500 meters (1650 ft.) are still numerous as well as those with depths between 500 and 1000 m. (3300 ft.). A few of the newer fields reach greater drilling depths up to 1600 m. (5250 ft.). The deepest exploration well drilled to date (Djambi field, South Sumatra) reached a, depth of 2332 m. (7650 ft.) before abandonment in March, 1930. The specific gravities of the various crude oils produced range between 0.65 (86.2° A.P.I.) and 0.95 (17.5° A.P.I.). The lighter crudes have a high gasoline content and fuel oils are derived from the heavier crudes, which usually are rich in paraffin. Producing companies are: De Bataafsche Petroleum Maatschappij (Royal Dutch-Shell combine in Dutch territory); The Anglo-Saxon Petroleum Co. Ltd. (Royal Dutch-Shell combine in British territory); De Nederlandsch-Indische Aardolie Maatschappij (De Bataafsche Petroleum Maatschappij-Dutch East Indian Government combine); De Nederlandsche Koloniale Petroleum Maatschappij (Standard Oil Co. of

Jan 1, 1933

By Charles Will Wright

THE economy as well as the living standards of a country depends largely upon adequate supplies of raw materials at reasonable prices. Geological and climatic conditions responsible for the occurrence of commercial minerals and the growth of raw agricultural and forest products are so varied in different parts of the world that no country can be self-sufficient. The world is rapidly shrinking because of improvement in transportation facilities, but populations are steadily increasing and so are the needs for a greater production of raw materials and for their more equitable distribution. Too many barriers between nations prevent free access to the main sources of supply of the raw materials vital to neighboring nations and it is just such barriers that are often the cause of friction and even war. The International Trade Organization is doing a commendable job in helping to. break down barriers and to reduce friction, and we should now find ways to facilitate access to these sources of supply and encourage more efficient and greater production of the raw materials so urgently needed throughout the world. This cannot be done by individual selfish governmental agencies, influenced as they are by politics, nor by socialistic governments attempting to nationalize industries. It can be done efficiently only by the free individual through private enterprise properly protected against adverse governmental action. This protection can be supplied by the World Bank.

Jan 1, 1948

Members whose deaths were reported from Apr 7, 1923, to Apr 5, 1924 Elected Died 1918 ADKINSON, HENRY M 1923 1900 AGNEW, WILLIAM C 1923 1894 ASHLEY, H H 1923 1897 AUSTIN, KENNETH 1924 1903 AYERS, EMMA L C 1923 1913 BAECHTOLD, CHARLES A 1924 1900 BAIN, HUGH A 1924 1919 BASHORE, E GORGAS 1923 1920 BATTELLE, GORDON 1923 1923 BAYLES, GERARD L 1924 1881 BROCK, CHARLES 1923 1903 BROOKE, HENRY 1923 1876 BROWN, HARVEY H 1923 1904 BROWN, THOMAS E 1923 1919 BUCK, DANIEL M 1924 1906 CHALMERS, THOMAS S 1924 1881 CLEMES, JOHN H 1923 1896 COLLINS, HENRY F 1924 1871 COURTIS, WILLIAM M 1923 1915 CRESSON, B F, JR 1923 1921 CROWE, WALDO P 1923 1920 DARNELL, J ORA 1923 1911 DAVIS, HENRY G 1924 1918 DAVIS, ROBERT S 1923 1916 DEANE, WILLARD A 1924 1901 DEMPSTER, WILLIAM 1924 1911 DEVEREUX, W B, JR 1923 1895 DICKENSON, F M 1924 1904 DRUM, FRANK G 1924 1875 DUDLEY, P H 1924 1916 EATON, ARTHUR 1923 1919 EATON,SHERMAN 1924 1911 GRIFFITH, WILLIAM 1924 1919 HILSDALE, PAUL 1923 1922 HODGES, I F 1923 1916 HOFIUS, MAX, T 1924 1914 HUGHES, HOWARD R 1924 1919 HUMMEL, CARL B 1923 1874 HUNT, ROBERT W 1923 1921 JONES, ERNEST EVANS 1923 1917 JOSLIN, CHARLES T 1923 1918 KASJENS, JACOB G 1923 1899 KIRKEGAARD, PETER 1924 1920 KLAUS, HARRY C 1923 1892 KNOERTZER, HENRI1924

Jan 1, 1923

The following is an incomplete list of members and guests who. called at Institute headquarters during the period Dec. 10, 1917 to Jan. 10, , 1918: A. A. Arluck, Camp Merritt, N. J. W. Spencer Hutchinson, Boston, Mass. C. L. Bruns, Santiago de Cuba. William F. Jahn, New York, N. Y. Henry C. Carr, New York, N. Y. C. H. James, Tucson, Ariz. L. J. Charles, Santa Fe, N. M. Charles Janin, San Francisco, Cal. W. A. Deane, Waxhaw, N. C. Joseph T. Kupferstein, Shreveport, Pa. P. St. John Dixon, Rio de Janeiro, Brazil. Richard Lamb, New York, N. Y. M. C. Drake, Marquette, Mich. Walter R. Malm, San Francisco, Cal. F. W. Draper, Petrograd, Russia. W. H. Nash, Buffalo, N. Y. Paul W. Gaebelein, Boise, Idaho. Edmund Newton, Minneapolis, Minn. H. F. E. Gamm, Rutherford, N. J. Guy C. Riddell, Port Pirie, South Australia. C. A. Grabill, El Paso, Tex. Williams A. Simkins, San Francisco, Cal. William H. Hampton, New York, N. Y. Henry B. Smith, Northampton, Mass. R. M. Henderson, Brackenridge, Colo. H. E. Smith, Chicago, Ill. Geo. B. Holderer, Northpines, Ont., H: C. Spaulding, Washington, D. C. Canada. Y. Wakabayashi, Tokyo, Japan. H. H. Howry, Camp Upton. N. Y. A. P. Watt, Mine La Motte, Mo. L. Douglas Anderson", superintendent of the Midvale, Utah, smeltery of the United States Smelting Co., has been appointed manager of smelteries for the company at Salt Lake City, Utah.

Jan 2, 1918

By A. M. Gaudin

IN flotation lime is used to depress pyrite. For this purpose it is preferred to caustic soda. The low cost of lime and the widespread availability largely account for this preference. However, there is some evidence1 that pyrite is more readily depressed by calcium than by sodium ions at the same pH. To measure the difference in adsorption of calcium and sodium, which is thought to lie at the basis of the differences in depressing action, radionuclides of

Jan 2, 1953

By J. D. Mooney

(San Francisco sleeting, September, 1915) THE accompanying chart has been drawn for the convenience of engineers as a means of quickly determining the correct number of plies of conveyor belts operating under specific conditions. The calculations are based on the average safe strength (factor of safety, 15) of the various standard rubber conveyor belts. The, calculations assume maximum loading conditions; that is, the belt is considered as carrying the greatest load that it will handle without spillage at ordinary belt speeds. This not only produces the most economical operating conditions, but also the maximum tension in the belt. The chart is a graphical representation of the formula: p = kgW (L + 1OH) Where, p = the correct number of plies k = a constant, depending on the type of drive g = the weight in pounds per cubic foot of material handled W = the width of the belt in inches L = the length of the belt in feet (approximately twice the center distance). H = the difference in elevation between the head and tail pulleys, in feet. For a simple drive, with a bare pulley, k = 1/250,000 For a simple drive, with a rubber-lagged pulley, k = 1/300,000 For a tandem dive, with bare pulleys, k= 1/375,000 For a tandem drive, with rubber-lagged pulleys, k = 1/455,000 The chart is drawn for a simple drive, with a bare pulley (k =1/250,000;

Jan 9, 1915

By John Birkinbine

Four meetings of the Institute have been held in the anthracite coal-fields of Pennsylvania, and excursioris into the district, in connection with meetings elsewhere, have familiarized our members with

Jan 1, 1892

By AIME AIME

NO ADEQUATE salary scale, at the present time, can ignore the increase in the cost of commodities 'during the last few years or- afford to assume that this increase is merely temporary. A study of the change in prices and wages during and after the Civil War is of interest in connection with changes that have taken place from 1913 to 1919. The curves on the accompanying figure, based on reports of the War Industries Board and Department of Labor, show these changes. During the Civil War retail prices rose to 164,2 per cent. of the prices of 1860, during the next 8' or 10 years. It is interesting to note that the rise in wages during the Civil War was almost simultaneous with the rise in the prices of commodities. During the World, War, the rise in wages has lagged about a year behind the rise in prices. Furthermore, in the period immediately, following the Civil War, wages continued to rise after prices started to fall, The present price level is not considered merely temporary by such of our Government agencies as the Department of Labor and the Federal Reserve Board or by such economists as Irving Fisher' and J. S. Holden.2 Sub-

Jan 1, 1920

By John H. Harden

In the valuable paper of Mr. Dunbar D. Scott and its varied discussion, on the evolution of mine-surveying instruments, the tripod-head has not received the attention it merits. During the last 50 years this very necessary adjunct to the surveyor's instrument has been much improved. The legs are of better construction; and the devices for laterally moving the instrument over the station-point and for quick leveling, without the use of the screws, have given to the instrument fitted with the modern tripod-head the same facilities possessed by the oldfashioned ball-and-socket, with more perfect accuracy, not attainable in the latter, while saving from 30 to 50 per cent. of the time required for setting the instrument over a station. For the purpose of extending the discussion to this import-

Jan 1, 1902

By F. W. SUTTER

IN order to have ore available on the completion of the beneficiation plant at Clifton and to provide for continuous production while underground development was carried out, it was decided to develop an open-pit through the crest of a long hill in which the ore outcropped, using 40-ft. vertical benches.

Jan 1, 1943

By P. G. Shewmon, H. E. Collins

We have studied the effect of adsorbed sulfur on the surface self-diffusion of copper using eight diflerent surface orientations and the grain boundary grooving method. The eight orientations studied were the four lying near the low-index surfaces—(loo), (Ill), and two directions in the (110)-plus four higher-index surfaces. Surface-diffusion measurements were made over a range of HZS concentrations (in Hz) from 3 to 1500 ppm between 830°and 1050°C. The results can be divided into two groups—Group 1 contains the two (110) surfaces while Group 2 contains the remaining six surfaces. In Group 1, increasing the temperature increases the effect of Hz S on DS for the Hz S range 5700 ppvn. Qs and Do increase with increasing H2S concentration in this Hz S range. Beyond this range, increasing the temperature decreases this effect on D,; also Q, and Do decrease. In Group 2, increasing the telnperature decreases the effect of H2 S on D, for the H2S range studied, and Qs and Do decrease with increasing Hz S concentration. In any study of surface phenomena, there invariably arises the question of the possible presence of and effect of adsorbed impurities. Such questions are well-founded since the presence of adsorbed atoms can sometimes produce marked changes in the kinetics of surface-energy-driven processes. In the last few years, values of the surface self-diffusion coefficient, D,, have been determined on a variety of metals by studying the decay of scratches or the growth of grain boundary grooves.L~3-L0~L3 Yet there has been relatively little work done in which the concentration of an adsorbed impurity was systematically varied and the effects observed. Work of this sort would provide some basis in fact for the assertions often made about the ro1.e of adsorbed impurities in the differences between the results of different workers in different atmospheres and on different metals. It also is relevant to those cases in which surface monolayers produce profound effects in commercially important processes. The most marked example of such effects is the ability of nickel or palladium to increase the sintering rate of tungsten by many orders of magnitude.' The aim of this work was to study the effect of sulfur partial pressures on the surface self-diffusion of copper. It was felt that this in conjunction with a study of the degree of adsorption and type of active sites involvedL8 would provide a wide range of data for one system and hopefully lead to some insight into the mechanism by which sulfur adsorption influences copper diffusion. The main reasons for choosing the Cu-S system were, first, faceting was reported not to accompany the adsorption of sulfur. This is required if our experimental technique is to work. Second, Oudar has determined a high temperature adsorption isotherm for this system, an event which puts the Cu-S system almost in a class by itself.I4 EXPERIMENTAL PROCEDURE Initially, we considered studying the effect of an adsorbed impurity on surface self-diffusion of copper using isolated (or single) scratch smoothing as the technique and oxygen as the impurity. Copper was chosen as the material because the effects of orientation and anisotropy of the surface self-diffusion coefficient, D,, of copper in a dry hydrogen atmosphere had been studied extensively by Gjostein' and by Shewmon and ~hoi.~,~ The isolated scratch technique was chosen because both the effects of surface orientation and anisotropy of D, in a given surface could be easily studied with this method.~ Oxygen was tried as the impurity because Robertson and Shewmon""~ had studied its adsorption on copper at 1000°C over the range of oxygen partial pressures of 10"22 to 10-l3 atm. After several preliminary runs, it became evident that neither the scratch technique nor the impurity oxygen would be satisfactory for this work. Scratching deforms an annealed surface so that the region near the scratches recrystallizes, thereby disrupting the scratch profiles. One can avoid this by deforming the specimen sufficiently before scratching to give complete recrystallization on subsequent heating.4 However, as a result of Gjostein's success in scratching and annealing undeformed gold single crystals without local recrystallization,13 we attempted something similar with copper single crystals using a 0.7-mil diamond phonograph needle mounted in a Tukon hardness tester. All specimens recrystallized upon being annealed. Also, some copper specimens were sent to Gjostein to be scratched using his technique. The results were the same. As a result, the scratch technique was dropped in favor of the grooving of symmetric grain boundaries. Preliminary work using oxygen showed that faceting began to occur before oxygen adsorption had any measurable effect on D, at 938°C (at Pbo/P, = 0.12). Since heavy faceting would interfere with the measurement, we decided to use a sulfur-containing atmosphere (H2S/H2). Work by Oudar and Benard' and Robertson" showed that sulfur absorbed on copper and that faceting was not observed.

Jan 1, 1967

By M. E. Wadsworth, K. C. Bowles, H. E. Flanders, R. M. Nadkarni, C. E. Jelden

The kinetics of precipitation of copper on iron of various purity were carried out under controlled conditions. The rate of reduction has been correlated with such parameters as copper and hydrogen ion concentration, geometric factors, flow rate, and temperature. The character of the precipitated copper as a function of flow conditions and rate of PreciPitation has been observed under a variety of conditions. ThE precipitation of copper in solution by cementation on a more electropositive metal has been known for many years. Basile valentine' who wrote Currus Triumphalis Antimonii about 1500, refers to this method for extraction of copper. Paracelsus the Great2 who was born about 1493 cites the use of iron to prepare Venus (copper) by the "rustics of Hungary" in the "Book Concerning the Tincture of the Philosophers". Agricola3 in his work on minerals (1546) tells of a peculiar water which is drawn from a shaft near Schmölnitz in Hungary, that erodes iron and turns it into copper. In 1670, a concession is recorded4 as having been granted for the recovery of copper from the mine waters at Rio Tinto in Spain, presumably by precipitation with iron. Much has been published in recent literature on the recovery of copper by cementation, the majority of the articles being on plant practice.5-24 The rest include articles on investigation of the variables involved25-28 and a review of hydrometallurgical copper extraction methods." This literature has established: a) The three principal reactions in the cementation of copper are Cu + Fe — Fe+4 +Cu [ 11 One pound of copper is precipitated by 0.88 lb of iron stoichiometrically. In actual practice about 1.5 to 2.5 lb of iron are consumed. 2Fe+3 + Fe — 3Fe+2 [21 Fe +2H'-Fe+2 + H2 [3] Reactions [2] and [3] are responsible for the consumption of excess iron. Wartman and Roberson'28 have established that Reactions [ I] and [2] are concurrent and much faster than Reaction [3]. b) Acidity control is important in the control of hydrolysis and the excessive consumption of iron. he commercial workable range is approximately from pH = 1.8 to 3." c) Iron consumption is closely related to the amount of ferric iron in solution. Jacobi" reports that, by leaving the pregnant mine waters in contact wi th lump pyrrhotite (Fe7S8) for 3 hr, all the iron was reduced to the bivalent condition and scrap iron consumption was cut to 1.25 lb scrap per pound of copper precipitated. He also reported that SO2 has been used successfully to reduce ferric iron to the ferrous state. d) The ideal precipitant is one that offers a large exposed area and is relatively free of rust. e) High velocities and agitation show a beneficial effect upon the rate of precipitation, as it tends to displace the layer of barren solution adjacent to the iron and also dislodges hydrogen bubbles and precipitated copper to expose new surfaces. Little work, however, has been published on the reaction kinetics of copper precipitation on iron. Cent-nerszwer and Heller20 investigated the precipitation of metallic cations in solutions on zinc plates. They found the cementation reaction to be a first-order reaction. The rate constant was independent of stirring for high stirring rates and they concluded that the rate is governed by a diffusional process at low stirring speeds and by a "chemical" process at higher stirring speeds where the rate reaches a constant value. This conclusion has been challenged by King and Burger30 who could not find any region where the rate was independent of the stirring speed, although the rate constant they had obtained for high stirring speed was greater than the maximum value of the rate constant reported by Centnerszwer and Heller (by a factor of six). King and Burger, therefore, concluded that the rate of displacement of copper was controlled only by diffusion. Cementation of various cations on zinc has been summarized by Engfelder.31 APPARATUS A three-necked distillation flask of 2 000-mm capacity was used as a reaction vessel. A pipet of 10-mm capacity was introduced through one of- the side necks, the sample of sheet iron, mounted in a rigid sample holder, through the other, the stirrer being in the middle as shown in Fig. 1. The whole assembly was immersed in a constant-temperature bath. The stirrer was always placed at the same depth in the solution. EXPERIMENTAL PROCEDURE Reagent-grade cupric sulfate (J. T. Baker Chemical Co., N.J.) was used to make up a stock solution containing 10 g of copper per liter which was then diluted to various concentrations as required. Experimental data were obtained by measuring the amount of copper and iron ions in solution at successive time intervals. The initial volume of the solution was always 2000 ml, 10-ml aliquots being removed each time for chemical analysis. Because the total volume change of the solution was less than 10 pct, no correction was used for solution volume change. Nitrogen was bubbled through the solution before and

Jan 1, 1968

By M. O. Abo-el Fotoh, J. B. Mitchell, J. E. Dorn

The effect of strain rate and temperature on the tensile flow stress of a polycrystalline bcc alloy of magnesium containing 14 wt pct Li and 1.5 wt pct Al was investigated for strain rates of 3.13 x lom5 to 3.13 x 10-3 per sec over the range from 20° to 300°K. From about 180° to 300°K the alloy exhibited an ather-ma1 deformation behavior where the flow stress was independent of strain rate and increased only slightly with decreasing temperature. At lower temperatures the flow stress was strongly strain-rate- and temperature-dependent, characteristic of deformations controlled by thermally activated mechmzisms. The activation volume for thermally activated plastic defornzation was between 5 and 30 cu Burgers vectors, independent of plastic strain. This low-temperature thermally activated deformation behavior was found lo be in satisfactory agreement with the theoretical dictates of the Dorn-Rajnak1 formulation of the Peierls mechanism where deformation is controlled by the rate of nucleation of pairs of dislocation kinks over the Peierls energy barriers. SEVERAL studies of the low-temperature thermally activated deformation of bcc metals and alloys (molybdenum,1 tantalum,1 Fe-2 pct Mn,2 Fe-11 pct MO,3 and AgMg4) have revealed that the strain rate is controlled by the activation of dislocations over the Peierls-Nabarro energy hills. Although there is some uncertainty as to the nature and effect of solute atom-dislocation interactions during low-temperature deformation of bcc metals, it has been concluded by Dorn and Rajnak,1 Conrad,1 and Christian and Masters6 among others that overcoming the Peierls-Nabarro stress which arises from the variations in bond energies of atoms in the dislocation core as it is displaced is the probable mechanism controlling low-temperature deformation. The purpose of this research was to investigate the low-temperature plastic deformation of the bcc alloy Mg-14 wt pct Li-1.5 wt pct A1 to determine if the behavior of this alkali metal alloy might be analogous to that for other bcc metals. This alloy was selected because of its availability and its current industrial importance as a lightweight material for aircraft and aerospace applications. I) EXPERIMENTAL PROCEDURE Polycrystalline tensile specimens having cylindrical gage sections 2 in. long by 0.2 in. in diam were machined from as-received alloy sheet stock of Mg-14 wt pct Li-1.5 wt pct Al. Specimens were annealed in an argon atmosphere at 423°K for 4 hr and maintained in a kerosene bath together with the sheet stock to prevent corrosion. The resulting specimen microstructure consisted of a coarse uniform dispersion of incoherent precipitate MgLi2Al particles7 in a bcc 0 phase matrix having an average grain size of 150 p. Prior to testing the specimens were chemically polished in dilute hydrochloric acid. Comparison of tensile properties and microstructures of specimens cut from center and edge sections of the sheet stock revealed no effects of inhomogeneities in the sheet material. Tensile tests were performed on an Instron machine at crosshead speeds corresponding to tensile strain rates of 1.56 x 10-5 and 1.56 x 10"3 per sec. Stresses were determined to ±2 x 106 dynes per sq cm and strains to within ±0.0001. Average values of shear stress t and shear strain y reported were taken as one half the tensile stress and three halves the tensile strain, respectively. Flow stresses were taken at 0.05 pct strain offset. Test temperatures down to 77°K were obtained by immersing the specimens in constant-temperature baths. Lower-temperature tests were performed in a liquid helium cryostat to within ±2°K of the reported values. Prior to testing at the various temperatures and strain rates all specimens were prestrained at 2 35°K at a shear strain rate of 3.13 x 10-5 per sec to a stress level of 0.606 x 10' dynes per sq cm to obtain a uniform initial state. Additional tests were made to determine the effect of changes in strain rate and strain on the flow stress by rapidly changing the crosshead motion during testing. Shear moduli of elasticity, needed for analyses of the data, were obtained at several temperatures by a common technique of determining the resonant frequencies of vibrations of rectangular test specimens. 11) EXPERIMENTAL RESULTS Fig. 1 shows the experimentally determined flow stress vs temperature for two strain rates. Two distinct regions of behavior are evident. Below about 180°K the strong increase in flow stress with increased strain rate and decreasing temperature indicates that deformation is controlled by a thermally activated dislocation mechanism. At higher temperatures an athermal region is evident where the flow stress is independent of strain rate and only slightly dependent on temperature. The applied stress t to cause plastic flow was separated into two components:

Jan 1, 1969

By Layson, W. C.

ACCORDING to the records, Phelps Dodge made its original entry into the production of copper in the oldest copper mines of Arizona at Morenci in 1881. The ore body now being mined as the Morenci open-pit, as outlined by churn-drill holes, diamond-drill holes, and underground workings, is estimated to yield 230,000,000 tons of ore averaging 1.06 per cent copper. This development will add 2,500,000 tons of copper to the 900,000 tons already produced in the district. Some five years ago preliminary development of the ore body began, with big-scale production planned including the erection of a new treatment plant to be built near the mine. Inasmuch as the Morenci open-pit was an entirely new project this required the grading of roads, establishment of mining benches, construction of railroad grades, building of railroad tracks, erection of shops, as well as the purchase of the necessary equipment to satisfactorily and economically maintain the schedules of production forecast. Along with the preparation of the main ore body it was also desirable to mine and deliver to an experimental mill a relatively small daily tonnage of typical ore.

Jan 1, 1942

By AIME AIME

AT the Morenci branch of the Phelps Dodge Corporation, of which Frank Ayer is manager, several new types of machines that have been developed by Charles Mitchell, shop foreman in the drill steel shop, invite comment for their time and labor-saving qualities. Foremost of these is an adjustable gage-block and gaging device for attachment to drill-sharpening machines, developed and patent applied for by Mr. Mitchell. It replaces the blocks on the standard Ingersoll-Leyner drill steel sharpener No. 5. Features of the device are gage blocks with a flat surface which can readily be removed when worn and planed in any flat planer; blocks that can be adjusted with a templet to give a far more accurate gage than was formerly possible; and a center stop that is adjustable and can be accurately set to center any standard size drill steel.

Jan 1, 1930

By Waldemar Lindgren

No one would maintain that all ore deposits or all deposits of useful minerals have been formed by the same processes. Generally they have originated by special processes of concentration but these may be of many different kinds. Some deposits have their origin in chemical or biochemical processes of concentration in rivers, lakes or seas, others developed on land by means of chemical reactions of surface waters on various forms of rocks. Certain insoluble substances remained behind; others were dissolved and precipitated in favorable places. This action proceeded in the realm of the oxidizing surface waters or in the deeper zones to which the waters from the surface could find their way. Examples of the latter kind may be found in the extensive copper and vanadium deposits of some sedimentary beds or in the lead and zinc deposits of certain broad limestone strata. In these instances the evidence for any other mode of origin would seem to be very weak indeed.' Nor does it seem possible to deny that circulating waters may form deposits of the more common metals along fissures after having dissolved many constituents from paths traversed. Another very large class has been formed by magnetic processes of concentration. The last 40 years have been a period of intense activity in the investigation and description of a vast number of deposits; all modern methods have been employed and the result is an accumulation of data, difficult or impossible to master. It has been a period similar to that in petrography. The generalizations, the able deductions, have lagged behind. Evidently several geologists have become weary of this "infinite detail" and a mistrust of the microscope seems to have arisen. Although this feeling of being swamped in microscopic detail is a painful experience, nevertheless only through the detail in combination with the large features, and only by utilizing all the related sciences shall we

Jan 1, 1927

By Milton E. Wadsworth, W. Martin Fassell, William H. Dresher

A study of the rate of dissolution of molybdenite (MoS2) in alkaline solution was carried out under carefully controlled conditions. Effects of temperature, oxygen over-pressure, and KOH concentration were evaluated. Studies were made in the temperature range 100°C to 175°C and in the pressure range 0 to 700 psia of oxygen. Under these conditions molybdenite was found to leach according to a linear mechanism. Both oxygen over-pressure and KOH concentration were found to control the rate of leaching. The mechanism has been explained in terms of adsorption of oxygen at the molybdenite surface followed by configurational rearrangement of the adsorbed molecules. The hydroxyl ion dependency is believed to be diffusion-controlled. Laboratory batch studies have shown that molybdenite can be readily dissolved in alkaline solutions under moderate conditions of temperature and pressure. Commercial application of this process to the production of ferro-molybdenum and molybdenum chemicals is promising in view of the ease of dissolution of molybdenite and the relatively noncorrosive conditions involved in the process. HIGH temperature-high pressure techniques have long been used to great advantage in the organic chemical industry, the petroleum industry, and the paper industry. Only recently, however, have these methods been used to extract metals from their ores on a commercial scale. The Chemical Construction Corp., together with interested producers of nickel and cobalt, has done much to develop methods of producing nickel and cobalt powders by the use of high temperature-high pressure techniques.' The Howe Sound Co. is currently operating a plant near Salt Lake City in which the new Chemical Construction Corp. technique is applied to cobalt-arsenic sulfide concentrates. In this method the concentrates are leached in a dilute solution of sulfuric acid under air pressure at a high temperature. Near Edmonton, in Alberta, Canada, the Sherritt Gordon Co. is also using the new method in conjunction with its ammoniacal leach process.' National Lead Co., at Fredricktown, Mo., is operating a process similar to that of Howe Sound. In spite of the rapid growth of high temperature-high pressure hydrometallurgical processes, there has been very little work done on fundamental principles involved in this type of process. Conse- quently the literature lacks any significant data in this field. Oxidation of pyrite,3 phalerite,4 galena,5 and recently molybdenite" in alkaline solutions has been reported to some extent. This investigation was initiated, therefore, to broaden the application of high temperature-high pressure hydrometallurgy and also to contribute some insight into the basic mechanisms of oxidation in an aqueous medium under these conditions. In addition to the immediate consequences of these processes much valuable information remains to be learned about fundamental reactions when they are carried out at temperatures and pressures slightly higher than those normally encountered. Leaching of molybdenite by alkaline solutions under oxygen pressure has recently been reported in the Russian literature by E. S. Usataya,8 who found that leaching rate increased with an increase in the pH of the solution—the strongest effects being observed at a pH of 10—and also with an increase in temperature. Usataya also has reported the formation of a protective film on the surface of the molybdenite when the leaching solution was weakly alkaline, neutral, or acidic. He believes that this oxidation process explains the migration of Mo+ + in the oxidation zones of molybdenite ore deposits and the subsequent impoverishment of the ores. Equipment: The high temperature-high pressure reaction unit used in this work was especially designed for kinetic studies of this nature, emphasis being placed on accuracy of measurement and precision of control. As details of the unit's construction and operation have been discussed elsewhere,7 Only basic features and principles of operation will be discussed at this point.

Jan 1, 1957

By H. Majima, E. Peters

The oxidation rates of pyrite, pyrrhotite, chalcopy-rite, chalcocite, covellite, bortzite, galem, sphalerite, and stibnite have beet2 carefully compared at 120 oC, using aqueous phosphate solutions buffered at pH 2.7, 7.1, and 11.2 as zvell as in 1.0 M NaOH and in am~onia-containing solutions. Under conditions of these studies, variations in rates of more than a factor of two per unit of mineral surface area were not observed for different minerals in phosphate buffered solutions, except that pyrrhotite showed unusually rapid oxidation rates In acid solutions, and stibnite showed very rapid oxidation rates in basic solutions. In caustic solutions, oxidation vates varied considerably, the most rapid being for pyrite and the slowest for sphalerite. In the presence of ammonia, only copper minerals showed more vapid oxidation rates in neutral solutions. Oxidation rates were measured on the basis of oxygen-consunzption rates per unit surface area of exposed mineral, using equivalent surface areas, mineral mesh sizes, pulp densities, agitation, and oxygen pressure. OXIDIZING pressure leaching of sulfide minerals has been a commercial method of treating concentrates of nickel, cobalt, and copper for over a decade, and recently the treatment of lead and zinc concentrates,' and even the recovery of sulfur from pyrrhotite by such processes, have been shown to be technically feasible.' Furthermore, the leaching of uranium ores by solutions acidified through the oxidation of pyrite and other sulfides present in the ore is commercially practicable.3 5 The mechanisms by which sulfide minerals oxidize in aqueous environments are not yet understood. However, certain generalities can be made for systems containing no unusual reagents, in which oxygen is the oxidizing agent. In acid solutions the oxidation of many sulfide minerals leads to the formation of elemental sulfur.8'7 The attack of some sulfides, notably galena (PbS), sphalerite (ZnS), and pyrrhotite (FeS), at temperatures below about 110°C leads to an almost quantitative conversion of the sulfide mineral to elemental sulfur according to the equation: On the other hand pyrite (FeS2) and copper minerals do not yield elemental sulfur quantitatively. Not more than 50 pct of the sulfur in pyrite is converted to the elemental form in acid oxidation, and this percentage is lowered by higher temperatures and possibly higher oxygen pressures.8'9 Copper minerals sometimes yield elemental sulfurlo'" but, since sulfur can reduce cupric ions with the precipitation of CuS or Cu2S, it is not likely that elemental sulfur is obtained in good yield. In acid solutions sulfur that is not converted to the elemental form always appears as sulfate salts or sulfuric acid. Sulfide minerals that yield elemental sulfur nearly quantitatively on oxidation in acid solutions tend to generate H2S when the conditions are not oxidizing. However, although it has been suggested that H2S is an essential intermediate in the mechanism of oxidation," this is doubtful because it is oxidized very slowly by oxygen. In basic solutions elemental sulfur is never formed, as predicted by thermodynamical considerations, summarized in the form of a potential-pH diagram in Fig. 1. However in neutral and basic solutions, unstable forms of sulfur not shown in the diagram appear during oxidation, notably thiosulfate (SOT-) and polythi-onates (S,O;-, x = 2 to 6).l3,l4 On prolonged oxidation only hexavalent sulfur as sulfate (SOi-) or sulfamate (NHzSO;) is found to remain, the latter appearing only in the presence of ammonia. The oxidation kinetics for thiosulfate by oxygen are the subject of a separate paper,'5 and were studied on the presumption that thiosulfate may, in fact, be a primary oxidation product for sulfide minerals, at least in neutral and basic solutions. A survey of the literature indicated that comparative oxidation rates for different sulfide minerals were needed to establish the role of the mineral structure and its thermodynamic properties on the oxidation rates and mechanisms.

Jan 1, 1967

By H. C. Chang, N. J. Grant

Creep of very coarse grained, high purity aluminum was studied at 400° to 1100°F with an initial stress range of 50 to 1200 psi. The process of boundary sliding and migration was studied. The driving force of boundary migration under creep conditions is shown to be a combination of strain energy migrationand surface energy. A theory is presented regarding the strainenergyrole the grain boundaries play under creep conditions. From this thetheory intercrystalline failure of commercial alloys can be explained. Also from this theory an optimum grain size should exist for good high temperature properties of high purity materials. IN the investigation of the creep of very coarse grained, high purity aluminum previously reported,' the cyclic nature of the process of grain boundary sliding and migration has been established by microscopic observation of the actual creep process as well as metallographically. It was also substantiated by measuring localized strains across the grain boundaries. In addition, it was shown how extensive subgrain and fold formation may result from boundary sliding and how the slid grain boundary may become sharply wavy as a result of subgrain formation. Since the publication of those results, additional information on the process of grain boundary sliding and migration has been obtained. It is the purpose of this paper to report on the direction and driving force of boundary sliding and migration, the effect of grain size, and the effect of temperature. Finally the effect of decreasing purity (alloys 2s and 3s) on the process of boundary sliding and migration is noted. From these results, an explanation is presented for the intercrystalline failure of alloys under creep conditions. The effects of grain size on the creep properties of impure and high purity materials are discussed in the same light. The experimental procedures and technique have been presented elsewhere.' It is only necessary to state how the 2s and 3s aluminum specimens are prepared. Machined specimens were first annealed at 600°F for about 12 hr. In order to produce a large grain size the specimens were then stretched 3 to 8 pct. The specimens were marked with reference marks, electropolished, annealed at 900°F for 24 hr and at 1150°F for 12 hr, and repolished. The grain size of 2s aluminum produced by this treatment is comparable to that of high purity aluminum in the direction of its width of the specimen, i.e., there are 2 to 4 grains across the width of the specimen. However, the grains of 2s aluminum are 3 to 10 times longer in the direction of the specimen axis. On the other hand, the grain size of coarse grained 3s aluminum ranges from 10 to 20 grains across the width of the specimen due to the treatment just outlined and therefore is much smaller than that of both high purity and 2s aluminum. As in 2s aluminum, the grains are about 3 to 10 times longer in the direction of the specimen axis than in the direction of the width of the specimen. The arrangements of the grains in 2s and 3s aluminum were generally irregular; therefore it was difficult to follow the course of the grain boundaries. Results Method of Presentation: In order to show the arrangement of the grains, especially the direction and positions of the grain boundaries, traces of the grain boundaries on the four surfaces of the specimens were unfolded and mapped out after macroetching. Figs. 1 and 2 show the structural development drawings of specimens P-3 and P-8 respectively. The two flat surfaces (of which the front one faces the microscope) and the round-edged surfaces will be called the "front surface" and "back surface" and

Jan 1, 1954