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By E. H. Rose

IN the realm of ore dressing the most pregnant feat of all time was announced in 1945: the winning of the mineral raw materials which made the harnessing of atomic energy possible. Lost in the stupendous implications of the end result, in the two billion dollar hugeness of the project, and in the famous names attached thereto, the fact that crude uranium ores had to be concentrated received relatively little notice in the press. Only the final link in the concentrating chain was publicized-ether extraction of uranyl nitrate, developed by Hoffman and carried on by the Mallinckrodt Chemical Works, or methods developed by the Ames group under Spedding. Some of the earlier links represented less glamorous but equally difficult and exacting research. One may only speak a word of admiration for those who worked hard, accomplished much, and said nothing. The universal lament for most of the year was "man shortage." A group of Canadian engineers expressed it as "being so short of labor that no labor was available to develop laborsaving devices." . Despite this, an outstanding amount of mineral-dressing progress was made in 1945. Necessity allowed no alternative. The insatiable demand of war for minerals forced the exploitation of lower and lower grade ores, and of others not before considered of commercial character or use, requiring the mineral dresser to fight for and win new bridgeheads on the home front.

Jan 1, 1946

By H. K. Birnbaum

The effect of 1ow-temperature stabilization anneals on the structure of the 0 phase Au-Cd alloys and on the diffusionless transformations observed in these alloys was examined by X-yay diffraction techniques. A phase separation in the ß-phase region was proposed to account for the experimenta1 results. The effects of quenching from elevated temperatures on the transformation behavior of these alloys were shown to be consistent with the proposed mechanism. IT has been shown that the high-temperature ß phase (CsCl structure) of the Au-Cd alloy system transforms to a phase having an orthorhombic (D2) ß&apos; structurel1-3 for compositions near 47.5 at. pct Cd and a tetragonal (4/m, m, m) ß" structure* in the vicinity of 50.0 at. pct Cd. Both transformations are diffusionless, crystallographically reversible, and occur on cooling at about 60° and 30°C respectively. The temperature interval from the beginning to the end of the transformation is of the order of 5°C in each case. Although the transformations are normally athermal, some of them have been reported to occur isothermally.= wechsler6,7 has shown that the effects of quenching a 49.0 at. pct Cd alloy from elevated temperatures are consistent with the retention of a nonequilibrium number of lattice vacancies. Annealing of these quench effects results in a broadening of the X-ray reflections.8 After a suitable quench, the 47.5 at. pct Cd alloy transforms to a phase having not the p&apos; orthorhombic structure but another structure which has properties similar to that of the ß" tetragonal structure.5.9 This change in the type of transformation has also been obtained after long anneals in the ß-phase region at about 70oC10 The present investigation was primarily concerned with the structural changes accompanying the above transformation phenomena. The change in transformation product and accompanying physical changes during an anneal in the ß phase have been termed stabilization effects. Experimental Procedure —The results reported in this investigation were obtained with the use of a Norelco diffractometer fitted with a temperature-controlled cryostat. The specimen temperature was controlled to better than ± 0.l°C during the measurements. CrKa radiation monochromated electronically with the use of a scintillation counter and pulse height analyzer was utilized. Specimens containing 47.5 and 50.0 at. pct Cd were prepared by sintering filings obtained from homogenized ingots of the proper alloy composition. (Gold of 99.999 pct purity and cadmium of 99.98 pct purity were used). All heat treatments were carried out with the specimens capsulated in vacuum ( < 10 % mm Hg) or in a He-H gas mixture. The quenching technique used in these experiments was to drop the pyrex capsule which contained the specimen from the annealing furnace into water, the temperature of which was controlled. The pyrex capsule shattered on contacting the water resulting in a relatively rapid quench. After the heat treatment, the specimens were mounted in the diffractometer and were left undisturbed in the diffractometer specimen holder during each sequence of measurements. EXPERIMENTAL RESULTS A) Low-Temperature Annealing—The transformations which were considered "normal" for these alloys were those obtained athermally during furnace cooling at approximately 50°C per hr after an elevated temperature anneal. Under these experimental conditions, the specimens were observed to transform to phases having structures whose diffraction patterns could be indexed as the ß&apos; orthorhombic structure for the 47.5 at. pct Cd and as the 0" tetragonal structure for the 50.0 at. pct Cd alloys. The transformation temperatures on cooling were approximately 60" and 30°C, respectively. Under the "normal" conditions both transformations were observed to go to completion, i.e., the entire volume of the ß phase was transformed to the product phase. In some specimens an extremely weak ß 110 reflection was observed at 20°C indicating that a small amount of retained ß was present. The effect of low-temperature annealing on the nature of the diffusionless transformations was examined for the 47.5 and 50.0 at, pct Cd alloy. The specimens were annealed in evacuated capsules at temperatures in the vicinity of 600°C (as specified in Table I) for 24 hr and were then cooled to 100°C at a rate of 50°C per hr. The specimens were then removed from the capsules and mounted in the diffractometer without allowing the specimen temperature to drop below 80°C. Annealing at the low temperatures was accomplished in the diffractometer by means of the cryostat which was mounted around the specimen. During the low-temperature anneals the lattice parameter, integral breadth of the reflections, and ratios of the integrated intensities of the fundamental and super lattice reflections for the 0 cubic phase were periodically determined. After annealing for the required time, the specimens were slowly cooled in the diffractometer and the diffraction patterns were recorded as a function of temperature. The specimens were cooled until the phase transformations were completed, following which the specimens were heated and diffraction

Jan 1, 1960

By S. K. Kawatra

In order to take full advantage of the use of manipulatable variables to effectively control the response of coal flotation circuits to disturbances and to optimize circuit performance, the effects of each manipulatable variable must be understood with respect to the mechanisms responsible for particle recovery. This paper pays particular attention to the critical role of the froth phase and its effect on circuit behavior and control and emphasizes that in order to optimize the separation of coal from gangue by flotation it is necessary to consider particle behavior in both the pulp and in the froth while developing a control strategy. Data obtained from the extensive sampling of the flotation circuits in two coal preparation plants are used to illustrate this concept; by showing first the effects of reagent addition levels on the mechanisms responsible for particle recovery and second how this information can be used for control strategy development.

Jan 1, 1984

By R. Frenkel, O. D. Sherby, J. E. Dorn, J. Nadeau

A method is shown for the study of the creep rate dependence of metals on the applied stress under the condition of constant structure. The method was applied to pure aluminum and to dilute solid solution alloys of magnesium, copper, germanium, zinc, and silver in aluminum. A linear relationship was found to exist between the true stress and the logarithm of the creep rate. ALTHOUGH extensive creep data are now avail-Aable, the fundamentals of the creep phenomena are as yet only vaguely understood. Many attempts have been made to formulate theories for creep. Eut their agreement with fact has been disappointing. It appears that merely pyramiding more of the same type of data that is now available will not provide the essential aid toward formulating a better understanding of the complicated process of creep. Perhaps attempts to construct better models for the mechanism of creep might have to be tentatively abandoned until new types of definitive creep data are uncovered. The question therefore arises regarding what type of data might be needed to provide the essential knowledge for formulating better and more realistic theories of creep. Perhaps one source of the failure to uncover an adequate theory arises from the fact that practically all theories for creep and nearly all analyses of experimental data on creep disregard the well-known fact that the structure of metals changes during creep. For example, it is customary in evaluating the effect of stress on the creep rate to correlate the secondary creep rate with the applied stress. But, as has been demonstrated recently,&apos; the structures obtained during secondary creep tend to exhibit deformation banding at high stresses and polygoniza- tion at the lower stresses. Consequently the stress-secondary creep rate relationships found in this way are not fundamental, inasmuch as they reveal not only the effect of stress but also the effect of differences in structure on the secondary creep rates. It is the purpose of the study reported here to isolate the effect of stress alone on the creep rate in an attempt to provide new data for possible formulation of a better theory of creep. In addition an attempt will also be made to ascertain how structure, temperature, and alloying might affect the stress-creep rate relationship. The procedure that was adopted was simple: A specimen was precrept at a given engineering stress U, (initial engineering stress during creep under constant load, namely the load divided by the initial area of the specimen) and temperature T to a selected engineering strain, e (engineering strain, namely, the instantaneous gage length minus the initial gage length divided by the initial gage length), at which time the true stress was reduced to some lower value of the true stress, ^ (the true instantaneous stress, namely, the load divided by the instantaneous area). The instantaneous true creep rate, i, (the true strain rate; with E, the true strain, namely, the natural logarithm of the instantaneous over the initial gage length) following reduction of the true stress to U, was then determined. Second, third, etc., tests were conducted under identical conditions except the stress was reduced to yet lower values, us, u,, yielding yet lower instantaneous creep rates, ;, and i,. Inasmuch as the precreep conditions were identical in each series of tests, the instantaneous structures obtained immediately after reducing the stress were presumed to be identical.

Jan 1, 1955

By C. W. Allen, B. D. Cullity

The proportional limit of iron crystals in torsion is governed by the resolved shear stress in the most highly stressed slip systems, averaged around the specimen circumference, and does not obey a critical resolved shear stress law. Crystals of most orientations exhibit a stage of easy plastic deformation, akin to easy glide in tensile or shear specimens. Transient deformation, similar to that which occurs in single crystals of other materials, is also observed. THE torsional deformation of single crystals of magnesium (hcp) and aluminum (fcc) has been described recently by Choi et al.,&apos; especially with respect to the criterion for the orientation dependence of the onset of plastic flow in these materials. The purpose of this paper is to present results of torsion tests of iron single crystals and thus to extend this yield criterion to a bcc metal. In addition to considering the variation of proportional limit with crystal orientation, this paper also briefly treats work hardening, transient deformation, and the mechanism of plastic flow in iron. The effects of the method of surface polishing and the chemical purity of the iron have been investigated. STRESS DISTRIBUTION It is convenient to express the stress at any point of a cylindrical crystal stressed in torsion in terms of t0, which is the shear stress acting at the surface on a plane normal to the axis of the cylinder and in a direction tangential to the cylinder. This stress is given by To = 2T/pr3 [1] where T is the applied torque and r the specimen radius. The shear stress t, resolved in any chosen slip system is given in terms of 7, by1 Ts/TO = sin 0, cos d sin (0, -) + cos , sin d sin d - ) [2] where 0 and d are the angles between the specimen axis and the slip plane normal and slip direction, respectively; h is the angular circumferential position on the specimen at which t, is being determined, measured from an arbitrary reference plane which includes the axis;o and d are the angular coordinates of the projections of the slip plane normal and slip direction on a transverse section with respect to this same reference plane. Slip in iron occurs in a <1ll> direction on the {ll0}, (1121, and (123) planes, which together comprise 48 slip systems. A complete evaluation of the stress distribution in an iron crystal stressed in torsion would therefore require a calculation of Ts/T0 as a function of for 48 different slip systems. Fortunately Gough,&apos;who studied the behavior of iron crystals in alternating torsion, was able to simplify this problem considerably. He showed that it was sufficient to consider a kind of average slip plane for each slip direction, namely the mathematical plane of maximum resolved shear stress containing the slip direction considered. This simplifying approximation is possible because, for each slip direction, the active slip plane or planes lie very near this mathematical plane of maximum shear stress. Vogel and rick&apos; have critically reviewed the early work of Taylor and Elam,13 Taylor,14 and Fahrenhorst and schmid8 from which the identification of the above crystallographic planes as slip planes in the bcc lattice largely stems. While their criticism is clearly justified, their own results do little to clarify the issue. The role of cross slip (screw dislocations changing glide planes) is evidently so important in this case, as Read3 has suggested, that methods for deducing slip systems from observations of gross slip traces are inadequate, such traces commonly arising from complex dislocation motion. Thus the treatment given here involving the plane of maximum resolved shear stress seems a logical simplification especially in view of Gough&apos;s2 study of a iron. There is, however, an assumption built into the subsequent treatment the comparative validity of which is difficult to assess, namely, that slip in all slip systems in iron may be characterized by a common critical resolved shear stress. The shear stress 7, resolved in a slip direction defined by d andd, and on the plane of maximum shear stress containing this direction, is found by first maximizing 7s/70 with respect to either Oo or 4,. The slip plane coordinates are then eliminated by using the relation between 0, ,o and d, d, namely,

Jan 1, 1963

By Nicholas J. Grant, Noboru Komatsu

Electron-micrographic studies and hardness tests were made of an internally oxidized dispersion-strengthened Cu-12 vol pct SiO2 alloy follozuing longtime annealing at elevated temperatures. The rate of coarsening of SiO2 particles and the relationship between hardness and interpavticle spacing were Dispersion -strengthened alloys exhibit a remarkable stability of structure and properties at elevated temperatures compared with conventional alloys; nevertheless, when they are exposed to high measured. The rate of coarsening of SiO2 particles is controlled by the decomposition of SiO, rather than by the diffusion rates of silicon or oxygen through the copper matrix. The mechanism of coarsening was also studied by using a diffusion-couple technique. temperatures, weakening takes place as a result of coarsening of the dispersed phase. The theoretical treatment of the coarsening of dispersed phases has been treated by Greenwood,1 wagner,, and others3 by considering the interfacial energy of dispersions and the diffusion of solute atoms. Recently, experimental work on the coarsening of relatively insoluble, finely dispersed cobalt particles in copper was reported by Livingston,4 and on aluminum oxide in nickel by Dromsky, Lenel, and Ansell;5 according to these investigations, the rate

Jan 1, 1964

PRESIDENTS DAVID THOMAS 1871 R W RAYMOND 1872-1874 A L HOLLEY1875 ABRAM S HEWITT 1876 T STERRY HUNT 1877 ECKLEY B COXE 1878 - 1879 WILLIAM P SHINN 1880 WILLIAM METCALF 1881 RICHARD P ROTHWELL 1882 ROBERY W HUNT 1883 JAMES C, BAYLES 1884-1885 ROBERT H RICHARDS 1886 THOMAS EGLESTON 1887 WILLIAM B POTTER 1888 RICHARD PEARCE 1889 ADAM S HEWITT 1890 JOHN BIRKINBINE 1891-1892 H M HOWE 1893 JOHN FRITZ 1894 J D WEEKS 1895 E G SPILSBURY 1896

Jan 1, 1923

Jan 1, 1883

PRESIDENTS DAVID THOMAS 1871 R W RAYMOND 1872-1874 A L HOLLEY1875 ABRAM S HEWITT 1876 T STERRY HUNT 1877 ECKLEY B COXE 1878 - 1879 WILLIAM P SHINN 1880 WILLIAM METCALF 1881 RICHARD P ROTHWELL 1882 ROBERY W HUNT 1883 JAMES C, BAYLES 1884-1885 ROBERT H RICHARDS 1886 THOMAS EGLESTON 1887 WILLIAM B POTTER 1888 RICHARD PEARCE 1889 ADAM S HEWITT 1890 JOHN BIRKINBINE 1891-1892 H M HOWE 1893 JOHN FRITZ 1894 J D WEEKS 1895 E G SPILSBURY 1896

Jan 1, 1923

By AIME AIME

HENRY DAYTON WILDE-"Date," informally- manager- of the technical and research department of the Humble Oil & Refining Co., was born at Aguascalientes, Mexico, Sept. 25, 1900. He is a graduate in chemical engineering: M.S. from the University of Texas and I Sc.D. fro111 the Massachusetts Institute of Technology. t For a year and a half in 1926 and 1927 he was a research : associate in the research laboratory of applied chemistry at M.I.T., under W. K. Lewis. In the latter year Dr. Wilde went with the Humble as head of the laboratory experimental division of its refining development department. In 1929 he was made director of production research. Dr. Wilde is the author of important papers in the TRANSACTIONS of the Institute, wherein are also mans dis-

Jan 1, 1938

By CYRIL W., William Campbell, Henry M. Howe

THIS paper gives the results of an investigation of the behavior of the argentiferous cobalt-nickel arsenides of Temiskaming, Ontario, in roasting, made in the metallurgical laboratories of the School of Mines, of Columbia University in the City of New York. The ore was kindly given by the owners of the La Rose and Trethewey properties at Cobalt, Ontario, and Mr. E. J. Hall, Tutor in Assaying in Columbia University, has helped us much. I. OBJECT OF THE INVESTIGATION. The object of the investigation was to learn:- 1. The temperature at which the arsenic is most rapidly expelled; 2. The thoroughness with which it is expelled by prolonged roasting at this temperature; 3. The effect of adding charcoal (a) near the end of the roast and (b) at the beginning of the roast. II. NATURE OF THE ORE. The important ores mined in the Temiskaming deposits are native silver-with small amounts of dyscrasite (Ag6 Sb), argentite (Ag2S), pyrargyrite (Ag3SbS3)-smaltite (CoAs2), chloanthite (NiAs2) and niccolite (NiAs). Mispickel (FeAsS) and cobaltite (CoAsS) also occur in smaller quantities. The average composition of the ore shipped from this district for the first six months of 1905 -was: silver, from 4.1 to 4.8 per cent.; cobalt, from 6.9 to 8.2 per cent ; nickel, from 3 to 4.7 per cent ; and arsenic, from 30.9 to 34.6 per cent. The ore which we treated consists chiefly of smaltite ; In our laboratory-work

Jan 1, 1907

By Kenneth M. Bravinder, Jonathan E. Koogle, Dean H. Sheldon

THE solution of subsurface geological problems requires an analysis of vertical and horizontal dimensional relationships. For many, the ability to visualize structures in three dimensions is not easily acquired, and for areas where the structural conditions are complicated by faulting the need arises for illustrative models. This has led to the many forms of peg models, in which the usual course of construction includes a peg for the well bore, and the suspension of strings from peg to peg to illustrate the formation correlation between wells, thus developing the usual folds and flexures. Such models proved unsatisfactory for the analysis of fault problems. Consideration was then given to the use of transparent materials. A model of the Dominguez oil field was constructed in 1935, which consisted of a series of glass panels from well to well on which the formations were shown in color. This model, though serving its purpose at the time, proved to be impractical from the standpoints of cost, breakage hazard, and extreme difficulty in maintenance. The cost of materials was estimated to be approximately $300, and the construction required the services of one man for a period of from 10 to 12 months. Maintenance after actual construction was an additional expense. Consideration was then given to the use of celluloid, and after some experimental work it was found that the advantages in its use were: (I) a short construction time, (2) ease of handling the material, (3) sections are easily reworked, (4) low cost. CONSTRUCTION It would be of little value to recount here the difficulties encountered in the building of the first celluloid model. The conclusions drawn, however, suggest the following procedure for those who contemplate the construction of such a model: I. Determination of the Scale.-Accurate geological interpretation requires the use of the same scale horizontally and vertically. It should be emphasized that the limited size of the celluloid sheets (20 by 48 in. maximum dimensions), the area to be studied, the maximum depths to be plotted, and area of possible future development are the controlling factors in adopting a scale to be used. 2. Construction of the Base.-A satisfactory base may be constructed by using two pieces of three-ply wood separated by strips of i by 2-in. material. This type of construction prevents warping of the base. The size of the base is determined by the dimensions of the area to be studied plus 5 in. on all sides. A map of the same scale as that adopted for the model, indicating the lines of section to be used, should be fastened to the base. 3. Construction of the Frame (Fig. I).-In the construction of the frame the use of 1/2-in. o.d. pipe welded in a box shape is suggested, with two horizontal rods on each of the four sides, top and bottom. The top rod should be at least I in. higher than the

Jan 1, 1941

By George Otis Smith

WHAT American can enter this Western empire without his imagination being stirred by the stories of its past-yes, and even more by visions of its future! Whether we travel by rail or by auto, our pathway has its traditions of exploration and its records of early settlement. The mountain passes and the routes used by today&apos;s commerce are lasting memorials of the pathfinders whose unconquerable purpose was to search out a way-Lewis and Clark, Bonneville, Pike, Long, FrBmont, their names still live in your rivers and lakes and peaks. It was the glory of these adventurers that they spied out the land so that others might follow that long pro- cession of pioneers who occupied the new country- fur traders, gold miners, cattlemen, and homesteaders. Each of these pioneers attacked the problem of transportation in his own way, and each sought by his own method to win the resources whose richness had been reported by the pen of the Government explorer or by the swift rumor of the unnamed and unfamed adventurer. Trails were worn deep by these home or fortune seekers as they passed through the mountain barriers in successive waves-and these were waves that did not ebb, for this was an army of occupation. Along these main pathways of the West, as one historian has pointed out, the figure of chief interest was the sad- faced woman sitting on the front of the covered wagon.

Jan 1, 1926

By R. K. Ham, M. L. Wayman

TD-Nickel has been broken in tension and in fatigue at voom temperature. Rod specimens failed in tension by necking, with axial cracks attributed to voids elongated in the extrusion direction. Fatigue specimens failed in shear. Thin-film electron microscopy showed that the subgrain structure of TD-Nickel was very stable, and that particle-matrix detachment was very difficult, in tension and fatigue. TD-Nickel softened slightly during fatigue but had a high fatigue ratio (0.5at 10&apos; cycles). Fractography suggested that Stage I fatigue crack propagation is greatly extended in TD-Nickel. Td-NICKEL* is a dispersion of 2 pct by volume of thoria (ThO2) in nickel, produced by powder-metallurgical methods including compaction, sintering, and extrusion. The spherical thoria particles, which may have a mean diameter of a few hundred angstroms, are dispersed with a mean planar spacing of a few thousand angstroms. By a combination of cold working and annealing, a subgrain or cell structure of dislocations intimately associated with the dispersion can be produced.&apos; This gives the material useful tensile properties which are extremely resistant to exposure to high temperatures.&apos;-= At the same time, the material shows considerable ductility.3&apos;4 At the beginning of the present work, it was considered of great interest to investigate the mechanical stability of TD-Nickel under conditions of fatigue. On the one hand, materials which derive strength from a cold-worked structure are unstable in that they are susceptible to fatigue softening: in addition, the presence of discontinuities such as the particle-matrix interfaces might be expected to assist in the initiation and propagation of fatigue cracks, in that they may provide local concentrations of internal stress and sites for the initiation of voids." On the other hand, the substantial ductility of TD-Nickel suggests that if it obeys Coffin&apos;s relation8 (or the more refined form proposed by Manson9) it should have good fatigue resistance. The initial purpose of this investigation was to assess the importance of these factors. Also, relatively little fundamental work has been done on the mechanism of fatigue in dispersion-strengthened materials. Work on overaged A1-4 pct CU10-12 revealed a very large Bauschinger effect indicative of internal stresses at the particles, and very great fatigue hardening1&apos; presumably due to the multiple slip stimulated by these internal stresses, followed by softening which was initially due to softening in the matrix, but later might have arisen from cracking at the particle-matrix interfaces. The study of overaged Al-4 pct Cu could not settle this latter point by the electron microscopy of thin films, since the dispersion is too coarse. A previous study of the fatigue of internally oxidized copper13 was complicated by inter granular failure, attributed to oxide particles at grain bouhdaries; internal oxidation of single crystals, however, improved their fatigue properties.&apos;3 Investigations of SAP (sintered aluminum powder) are complicated by the complex particle shapes, and the possibility of continuous internal oxide films.14 It was hoped to avoid these difficulties with TD-Nickel, which had the further advantages that it was commercially available and suitable for study by the thin-film technique. 1) MATERIALS AND EXPERIMENTAL PROCEDURE TD-Nickel was purchased from the Driver-Harris Co. as 3/9-in.-diam rod which had been extruded, swaged, and "stress-relieved" (normally at 1010°C for 1 hr). Continuous-radius fatigue specimens with a minimum diameter of -0.1 in. were ground to shape and electropolished in 40 pct phosphoric, 35 pct sul-furic, 25 pct water at 25oC, with a stainless-steel cathode, at -6 v. Fatigue tests were carried out at room temperature with a Sonntag SF-1-U machine operating in push-pull at 1800 cycles per min, and in an Instron TT-C-L modified for reversed stressing at 26 cycles per min as described elsewhere.10 Round tensile specimens were ground with 0.85-in. gage lengths of 0.135 in, diam, electropolished, and tested in a Tinius Olsen hydraulic machine. The surfaces of fatigue specimens were examined with a Reichert metallograph. Discs for electron microscopy with a Siemens Elmiskop I were spark-cut 0.01 in. thick with a modified Servomet 11 employing a tool of moving molybdenum wire, cleaned in 50 pct acetic, 30 pct nitric, 10 pct phosphoric, and 10pctsul-furic at 85oC, and thinned by the window method in the electropolishing solution at -20°C and -6 v. Two-stage replicas (parlodion, then Pt-50 pct C self-shadowed at 40 deg) were taken from fatigue fracture surfaces for electron microscopy. Plane sections parallel to the specimen axis and containing the direction of fatigue crack propagation were polished, etched with Carapella&apos;s reagent, and examined optically. Transmission Laue X-ray photographs of as-received material electropolished to a point were used to determine preferred orientation. 2) RESULTS 2.1) The Structure of As-Received Material. Grains -1 µ diam and elongated 20 to 30 u in the direction of the rod axis were observed, With&apos; elongated "intergran-ular" voids (-4 p diam and -90 µ long and identified as such using longitudinal and transverse sections and

Jan 1, 1968

By CHARLES M. SCHWAB

THE ENGINEERS have placed this great country of ours in a preeminent position with everything pertaining to manufacture, metallurgy, and the kindred arts. We are second to none in the world. We have a country which, another speaker has said, God has endowed with such riches in coal and natural resources as no other country in the world. But rich as these are, there is one thing greater; the sturdy character, energy, and integrity of its people, which will make these great resources an influence in the world&apos;s developments. Great as are these resources and the energy and integrity of our people, there is one problem of our .engineering, which I term human engineering, that is of far more importance than the creation of machines and methods, with which you have been so successful in the past. Of what value is the skillfully devised machinery, the complex process, unless manned and operated by people whose heart and soul are in sympathy with the work they are doing and who have before them the giving of a complete day&apos;s work for a day&apos;s pay?

Jan 1, 1920

By R. J. Reynik

A semiempirial small flunctation theory of diff- sion in liquids is presented, which employs a fluctuation energy assumed quadratic for a small atomic or molecular displacement and Einstein&apos;s random-iralh model. The resulting diffusion equation is given by In these equations. D is the diffusivity, is the average liquid shite coordination number (at interatomic distance d. cm. T is the absolute temperature, xu. em, is (the diffusive displacement. K, is the quadratic fluctuation energy force constant, and rg, cm, are the radii oj diffusing atoms A and B, respectively. The quantities Xn and K are calculated from the computer-filled values of the slope and intercept. respectively. The radius of self-diffusing atom or radii and of diffusing atoms A and B are eta United and compared with values reported in the literature.. The predicted linear variation of diffusivity with. It tempera lure htm been observed in approximately thirty-iire metallic liquid systems, and in over seventy-fiee other liquid systems, including the organic .alcohols, liquified inert gases, and the molten salts, ALTHOUGH the average density within a macroscopic volume element of liquid is constant for fixed total number of atoms. pressure. and temperature, there exist microscopic: density fluctuations within the respective volume element. As such the microscopic volume available to an atom and its Z first nearest neighbors at any instant of time fluctuates above and below the average volume available to these atoms. If one assumes that liquid state atoms vibrate as in a solid. and further postulates that the mean position of any atom in the liquid state is not stationary. but shifts during every .vibration a distance 0 5 j 5 xo. then every atom in the liquid state continuously undergoes diffusive displacements which vary in the range 0 5 j 5 ro. Mathematically. for a binary liquid system consisting of atcrms A and B. the maximum diffusive displacement. .YO, is defined by the equation: where d is the average liquid state interatomic distance at specified liquid state coordination number Z. and v~ \ and vg are the effective radii of diffusing atoms A and B: respectively. For self-diffusion. r^ equals rg , and Eq. [I.] reduces to: It is interesting to note that Eq. [l] or [2] can be used to compute the radii of the diffusing atoms, provided one had an experimental evaluation of xo. As such. the computed radii could be compared with metallic or crystallographic ionic radii to ascerlain the electronic character of the diffusing atoms. Thus it is proposed that in the liquid state the n~otion of an atom relative to its original equilibrium position of oscillation represents the thermal vibration of any atom and its Z first nearest neighbors. while the small and variable displacements. 0 5 1 5 xc,. of the centers of oscillation represent the complex diffusive motions of the atoms at constant temperature and pressure. This is consistent with data obtained from slow neutron scattering by liquids1 &apos; and resembles an itinerant oscillator model of the liquid state.&apos;" It is further postulated that the atomic displacements characterizing the liquid state diffusion process are essentially a random-walk process. As such. it nlay be described by Einstein&apos;s equation:&apos; where D is the diffusivity. sq cm sec-&apos;. j2 is the mean square value of the diffusive displacement. and i> is the frequency of density fluctuations giving rise to diffusion. FORMULATION OF DIFFUSION EQUATION The effective spherical volume occupied by an atom, as a consequence of a microscopic density fluctuation which enlarges the volume available to any atom, exceeds its average liquid state atomic volume by an amount: where AV is the enlarged spherical volume, v is the radius of the diffusing atom. and j is the elementary displacement distance from the original center of oscillation of the vibrating atom to a new center of oscillation position. For small atomic displacements. where c is a constant whose value depends upon the assumed geometry of the enlarged volume. For a spherical increase in volume, c equals 4nr2. Following the treatment of Furthl&apos; and ~walin." assuming the enlarged volu~nes AL7 for the diffusing atoms are distributed in a continuunl. the probability of finding a fluctuation in the size range 0 5 j 5 xo defined by Where c includes the geometric constant cl and Eij) is the fluctuation energy causing the volume change. But the proposed model assumes all the Z first nearest-neighbor atoms are centers of oscillation. and hence the probability that any of these atoms is adjacent to a fluctuation of magnitude 05j5xo is unity. Thus:

Jan 1, 1970

By M. N. Brodie, John Chapman

INTRODUCTION - DEFINITION & HISTORICAL PERSPECTIVE While this symposium is concerned with comminution which, by definition, relates to all stages of size reduction of an ore body to a form suitable for mineral separation, the electrical drive aspect of the grinding section will receive most attention in contrast to the crushing, screening and materials handling elements of the process. The reason for this is that today&apos;s large mills, thirty feet diameter and upwards, present mechanical and electrical problems which require a degree of sophistication in their solution not previously required. The ability to satisfy these demands, so far as electrical technology is concerned, largely results from the development of semi-conductor devices. These can now handle typical electrical distribution power levels within remarkably s m all volumes and with high efficiency when compared with the motor-generator sets, mercury arc rectifiers, rotating amplifiers, magnetic amplifiers and vacuum tubes which were commonly used to provide speed and torque controls as recently as the early nineteen-sixties. The hardware available to the electrical engineer has changed dramatically whereby even the simplest control system formerly using hard-wired relays is now superseded by the program m able logic controller with its computer-like memory containing the sequence of operation, in other words, the software. Reverting now to the mineral process itself, it is assumed that the ore body has been mined using explosives and is delivered to the concentrating plant in its &apos;run of mine&apos; form. The problem becomes one of reducing the material to a size which will permit an acceptable recovery of the mineral with the most economical use of energy. The size of &apos;run of mine&apos; material will range from about minus five feet for high tonnage open pit operations to minus two feet for the smaller underground mine. The final reduction in size may range from minus ten mesh to minus two hundred mesh (exceptionally as fine as minus six hundred mesh) depending upon the concentration method and dissemination of the mineral values within the ore. There is no single circuit that satisfies all applications, but the pattern of metallurgical equipment use shown in Table 1 appears discernable from current practice, in general terms.

Jan 1, 1982

By Louise B. Freeman

Kentucky for the first time in its oil history passed the 10 million barrel mark. Of the total 10,019,641 bbl., 8,262,516 bbl. were produced in Western Kentucky, and Union County surpassed all others, with 4,056,142 bbl., or 40 percent of all the production for the state. There were 930 wells known to have been drilled during the year; 510 in Western Kentucky and 221 in the gas-producing area of Eastern Kentucky.

Jan 1, 1946

By E. W. Engelmann

RAPID progress has been made during the past year in the copper mills throughout the country. Particular efforts have been made to increase the fine-grinding efficiency by the installation of larger classifying units operating in closed circuit with ball mills, such as the 78-in. high-weir Akins installation at the Phelps Dodge plant at Ajo, Ariz.; also the Type "FX" Dorr classifiers of Nevada Consolidated at McGill. Nev. and the "FX" Dorr bowl classifier of the Braden Copper Co. in Chile. Some of the copper milling plants in the Southwest, such as Chino in New Mexico and Ray Con. in Arizona, have replaced rolls operating wet in their fine-grinding circuit by rod mills. At Hollinger primary rod mills were formerly used in open circuit followed by pebble mills in closed circuit with classifiers. They now have primary ball mills in closed circuit with large extra heavy classifiers and no secondary mills. This new installation is producing the same grinding on 5000 tons per day with a reduction in cost of nearly 4c. per ton. At the Braden plant, in Chile, short-head Symons crushers have replaced 54-in. rolls, thereby in- creasing crushing capacity with some saving in maintenance cost.

Jan 1, 1939

By Paul A. Schafer

BALATOC mine, the principal gold-producing mine in the Philippines, is 10 miles southeast of Baguio, in the Cordillera Central of northern Luzon.1 The region is a deeply dissected plateau, ranging in altitude from 3000 t0 5000 ft. above sea level. The rocks consist chiefly of granodiorite, diorite, and remnants of metamorphosed sediments, cut by dikes of andesite porphyry and quartz-diorite porphyry. All are intruded by a volcanic breccia plug, oval in horizontal section, about 3200 ft. long and 2300 ft. wide, which is the north central part of the mineralized area. Three main vein systems have been developed (Fig. 1): q6, 231 and 364, which strike about N.70°E. and dip 5o to 90°S. Each system is a braided zone consisting of many individual components. They are disturbed by a series of premineral faults or shear zones striking about N.45°E. Twelve of these produce important effects on the persistence, character, and quality of veins. From west to east the faults are named (after claims): Hog, Big Gun, Bull, Pine, Lolita, Bar No. I, Bar No. 2, Curt, Sun, Helen, Itoe, and Frog. They are early breaks formed prior to the N.70°E. vein fractures. Mineralization occurs on them but, with several prominent exceptions, they are too low grade to mine. A number of northwesterly striking faults complete the structural pattern. Although they are relatively abundant, the effect on the veins is so small that they do not present any problems in mining or development. All of these faults that have been observed are later than the N.70°E. veins and offset them to the left. NORTHEAST FAULTS The early northeast faults* are notably continuous in spite of their small displacements, 20 to 100 ft. Frequently they appear so weak that their importance is masked and their identity clouded. The gouge along any of these faults may vary from exceedingly weak at one point to very strong at another point only a short distance away. In other words, the amount of gouge depends on the changes of attitude of the fault plane, and is no indication of the extent of the movement. Places where walls are spread apart are filled with gouge squeezed from tight places. Also, mineralization sometimes obscures fault gouges by replacement. The mineralization of northeast faults has produced several important ore bodies; namely, 231 west on Pine fault and q6 vein on the same fault. To a smaller extent, Lolita, Curt, Bull, Bar No. I, and Sun

Jan 1, 1942