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By R. V. Norris

THE wage rates and working conditions in the anthracite. region of Pennsylvania have been governed for nearly 20 years by the award of the Anthracite Coal Strike Commission, appointed Oct. 16, 1902, by President Roosevelt. The report of this com-mission, made in March, 1903, was accepted and, with eight modifications made at various dates, has had .almost the force of law, and has kept this great indus-trial region free from strikes for almost a generation. In 1920, President Wilson appointed an Anthracite Coal Commission, and its report, accepted Aug. 30, 1920, governed wage conditions to April 1, 1922. Actually, the agreements have been for terms of two to four years, and lately, in 1916 and 1920, the employ-ees have continued at work pending the negotiation of new agreements which were made retroactive, and which have all been modifications of the original 1903 award. With the expiration, April 1, 1922, of the 1920 award approaching, Mr. Lewis, president, of the United Mine Workers of America, addressed a letter, on Feb. 20, to the operators, suggesting a meeting on March 15; this date was accepted by the latter, with the notation that the time was short. At the meeting, the Mine Workers presented 19 demands, and advised that if a satisfactory agreement was not reached by April 1.a suspension of mining would occur, contrary to the practice since 1916 of continuing work with a retro-active adjustment.

Jan 6, 1922

By P. D. I. Honeyman, P. A. Faust

At the Miami plant of the International Smelting Co., Inspiration, Ariz., there are four reverberatory furnaces, all 120 ft. long. At present only one of these furnaces is in operation. It is operated as a wet-charge furnace, the charge being distributed for about 65 ft. down the furnace length. Usually this charge contains about 12 per cent moisture and runs 25 per cent sulfur, of which there is eliminated in the furnace from 25 to 30 per cent. The furnace is oil-fired, the fuel being burned in a battery of Cananea-type, low-pressure burners. The flame is kept short and conditions so adjusted as to obtain complete combustion within the furnace. The average furnace draft, taken through the verb arch, amounts to only 0.02 in. of H2O. Draft is purposely kept low to cut down infiltration through the flues and boiler settings, and control dampers are regulated to maintain this uniform condition throughout the charging as well as the smelting period. Hot gases discharge from the furnace uptake through a common header flue to the waste-heat boilers. The general layout and dimensions of the plant are shown in Fig. 1. Four Stirling boilers, two of class M-26 (713 hp.) and two class M-31 (850 hp.), serve the furnace. Three usually are sufficient to take care of normal operation, the fourth boiler being used as a spare when necessary. The distribution of hot gases to the various boilers is regulated by the dampers in the boiler exit flues. Normally the boilers closest to the furnace uptake would evaporate more water than do those farther away, but dampers are regulated so as to distribute fairly well the load between the several boilers. Steam from the waste-heat plant is delivered to the adjoining power house of the Inspiration company, where it is used both in the Nordberg blowing engines and for electrical generation. Steam pressures and temperatures recorded are those in the main power-plant header and are thus inclusive of all losses in about 500 ft. of 10-in. line. Steam for smelter heating and auxiliary use is taken from the main waste-heat header, is reduced to 125 lb. and distributed through separate lines. Boiler feed water is supplied by the power plant and consists of returned condensate, augmented to a large extent by make-up water

Jan 1, 1934

By S. C. Sircar, D. R. Wiles

The rate has been studied of the hydrogen reduction of nickel ions in acetate -buffered solutions, using a nickel catalyst. At temperatures between 130°and 160°C, the rate is found to be proportional to the catalyst area, the nickel ion concentration, and the hydrogen pressure. The effect of hydrogen ions is to reduce the observed rate, likely by causing the reverse reaction (dissolution) to proceed. The experimental activation energy was found to be 25 kcal per mole. THE precipitation of metals and lower oxides from solution by hydrogen reduction has been quite actively investigated during the past few years.1 In the case of nickel, the kinetics of the precipitation have been studied in ammonia solution2 but extension of this study to acid solutions has not attracted much interest, largely because of the unfavorable thermodynamics at all but the lowest acidities. For example, Schaufelberger foundg that only 10 pct reduction of nickel could be effected in sulphate solutions. One kinetic study of the reduction of Ni++ has been reported by Knacke, Pawlek, and Sussmuth,4 in which the order of the reaction was found to be one in nickel ion and one-half in hydrogen pressure. No mention was made as to the part played by the nickel catalyst, or by the pH of the solution. Moreover, the activation energy reported (4 .12 kcal per mole) is so low as to lead to some question as to whether diffusion might be playing a major role in determining the kinetics. We have recently completed a study5 of the kinetics of the hydrogen precipitation of nickel from acetate-buffered acidic solutions whose results confirm and amplify those of Knacke et al. EXPERIMENTAL PROCEDURES The work was done in a high-pressure autoclavee by the usual technique of removing small samples of the solution for analysis. Nickel analysis was done colorimetrically by the dimethylglyoxime method.' The catalyst used was carbonyl nickel powder (Standard A powder of the Mond Nickel Co., Ltd.) which was found to be composed of spheres of less than 350 mesh. The surface area of the powder was determined in this laboratory by the B. E. T. method to be 1.85 sq m (m2) per g. The catalyst was added to the solution only after the proper temperature and pressure had been reached. Agitation of the baffled system was by a turbine-type impeller, rotated at speeds between 400 and 750 rpm. The reduction rate was found to be independent of the stirring rate, so it was assumed that diffusion in the liquid does not limit the rate. In typical experiments, the nickel concentration was unchanged during an induction period of variable length. The concentration then decreased sharply, and gradually levelled off to approach the final equilibrium value. In some cases, notably at high stirring rates, the nickel concentration was found to increase considerably during the induction period, and then to decrease. In all cases, the rate was determined from the slope of the tangent to the rate curve as the concentration first decreased below the initial value. This is seen in Fig. 1. The rate measurements were found to be reproducible to within about 5 and to be quite independent of the nature or duration of the induction period. The range of conditions used is given in Table I.

Jan 1, 1961

By AIME AIME

UNQUESTIONABLY the Coal Division has never had a meeting in which so many outstanding technical papers were presented of immediate practical application to problems of personnel, mining, safety, preparation, combustion, and carbonization. Should there have been those present with the lingering idea that all that was needed for success in the coal industry was a strong back and a weak mind they must have had a rude awakening.

Jan 1, 1942

By A. Coskun, J. F. Elliott

The activity of aluminum in liquid Al-Fe alloys .has been measured by an improved version of the transportation method in which the metallic vapor has been collected by its solution in a metallic condenser. The results can be represented by the equation: log yAl = -3.0(1 - xAl2) (0.6 < XAl < 1.0) This equation applies at 1315°C. MORRIS and zellarsl adapted the transportation method for measuring the vapor pressure of a com- ponent of an alloy at high temperature. We have modified their technique further2 for use with metals that are strong oxide formers. In the present case the method has been applied to the Al- Fe system to obtain the activity of aluminum in the liquid region at 1315°C. Dried ultrahigh-purity hydrogen (Matheson) is the carrier gas. The operations, Fig. 1, of deoxidizing the gas, equilibrating the gas with the sample at 1315";, and then collecting the aluminum vapor are all accomplished within a single, continuous alumina tube to avoid contamination of the system by leaks. De-oxidation to a very low level of PO2 (<10-25 atm) is Obtained by passing the hydrogen through a tightly packed bed of aluminum powder. The temperature of this bed increases to approximately 550°C in the direction of the gas flow. The boat containing three pellets of the alloy is supported on the end of a

Jan 1, 1969

By W. E. Keck

THERE is a considerable tonnage of iron ore in the Menominee Range Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a rela-tively large quantity of finished concentrate would be obtained (deleteri-ous sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal min-erals in a nearly puree state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,000&apos;. Of this quantity and value, Michigan produced approxi-mately 19 per cent4. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1937

By F. R. Hensel

Up to the present time few attempts have been made to produce hard nonmagnetic materials by heat treatment of austenitic steels. The usual result has been to cause them to pass into the martensitic stage, thus destroying to a great extent the typical austenitic properties, since this involves a transition of a portion of the iron from a face-centered to a body-centered type of atomic arrangement. High-strength nonmagnetic materials such as might be provided by properly hardening austenite are required in the electrical industry for different machine parts. In Europe nonmagnetic retainer rings for restraining the end-turns of the rotor windings in turbo-alternators have been developed as a special application of high-strength austenite. In testing1 a 28,000-kva. three-phase Siemens turbo generator running at 3000 r.p.m. at full load current, the losses in the short-circuit test were 450 kw. for the magnetic ring and 286 kw. for the nonmagnetic, and the difference should be attributable to the magnetic ring. The differences in temperatures during the same test are given in Table 1 and these show the advantage of a nonmagnetic over a magnetic retainer ring.

Jan 1, 1931

By E. J. Rapperport, J. P. Pemsler

The thermodynamic activities of zinc in six solid solution Cu-Zn alloys ranging from 5 to 35 at. pct Zn were determined experimentally in the temperature range 400° to 600°C. This low temperature investigation was canducted in order to evaluate techniques developed to utilize the inherently high sensitivity of atomic absorption flocesses in the measurement of thermodynamic activities. Analytical expressions ,for the activity and actizlity coeflcient are given for the six alloys in the temperature ranges investigated. RELATIVELY few experimental methods are available for investigation of thermodynamic activities of alloys, especially in the solid state. The techniques most frequently used have been the electrochemical potential and the effusion methods, both of which have severe limitations in many instances. It is therefore desirable to expand the ability to perform such measurements in order to obtain new information as well as to provide an additional independent verification capability. In this work, we present a significant improvement in the spectrophotometric method for sensing small vapor pressures in static absorption cells. Similar techniques have been used previously;1"5 however, applications had been limited to relatively high pressures, often greater than 1 torr. Prior investigators have, for the most part, used broad spectral sources such as xenon or mercury lamps, and high intensity arcs. Hollow cathode sources were first suggested in 1956 6 and were used soon afterwards.4&apos;5 These sources offer significant improvements in sensitivity and freedom from interfering spectral lines.&apos;-&apos; EXPERIMENTAL High purity zinc was obtained from Cominco Products, Inc., and copper from American Smelting and Refining Co. Both elements were of 99.999 pct purity. Copper-zinc alloys were vacuum melted in a high fired carbon crucible with each alloy pulled from the melt as a 4 -in. diam bar. The bars were swaged to -1/4 in. rods and vacuum annealed for 160 hr at 800° + 1°C. Samples for gross chemical analysis were taken at intervals along the length of the rods to ascertain the axial zinc gradient. Electron microprobe analysis of homogenized specimens indicated that the alloys had uniform compositions over their cross sections on a macro (200 p) and micro (1 u) scale to better than *1 pct (20) of the gross composition. This tolerance was determined by counting statistics, rather than assured composition fluctuations. All SiO 2 windows were high-ultraviolet-transmission grade to minimize intensity losses. Silica absorption cells were scrupulously cleaned consecutively in organic solvents, dilute HF, and distilled water before use. The empty cells were then flamed while under a dynamic vacuum, cooled, and removed to an argon-filled glove bag. Alloy pieces were cut and filed in the glove bag to produce fresh surfaces, and then loaded into the cells. The loaded cells were temporarily sealed, removed from the glove bag, reevacuated to 10-5 torr or better, and permanently sealed. The instrument used is schematically shown in Fig. 1. The spectral emission from a commercially made hollow cathode lamp (A) of a selected element is focused through an absorption cell (B) inside a well-controlled furnace (C). The intensity of the transmitted beam is measured using the spectrometer* (D) &apos;Techtron model AA4 atomic absorption spectrometer. which contains a grating (E) that disperses the light prior to impingement on the photomultiplier (F). The monochromator grating is adjusted so that only the wavelength of interest is measured. The power supply delivered an interrupted voltage to the lamp, causing a chopped radiation output to be transmitted. The detector read only the intermittent component of radiation incident upon it, so that all continuous noise signals (furnace radiation, and so forth) were eliminated. Three recording thermocouples contained in the muffle furnace were positioned along the length of the absorption cell: one at each end and one at the center. An effort was made to keep the ends of the cell several degrees hotter than the center to avoid window condensate. Appropriate thermal corrections were then necessary to relate cell pressure to radiation attenuation. Water-cooled heat shields, as shown in Fig. 1, were found to aid signal stability by protecting the hollow cathode and the photomultiplier from furnace radiation. The furnace had a 2-in. diam muffle, Kan-thal wound, with SiO 2 windows at its ends to minimize convective effects. The hollow cathode radiation was masked and focused to form a conic beam that was a maximum of { in. diam within the furnace. Thus, the 1.5 in. diam absorption cell easily contained the entire beam. The furnace was mounted on ball-bearing slides with positive positioning detents. This arrangement allowed the removal of the entire furnace assembly from the radiation path, position [I], Fig. 1, so that frequent sampling of the unattenuated beam intensity could be obtained. In all cases the beam intensity was kept constant to 0.1 pct as judged by readings taken immediately before and immediately after data collection. Only data for absorptions of less than 80 pct were utilized, as systematic deviations from linearity were found for greater absorptions.

Jan 1, 1970

By J. Richard Maier

Short-range mine planning (less than five years) previously was accomplished using contour and isopac maps, pencil and paper, an abacus, and our lucky quarter. Through the use of both micros and mainframe time sharing, Glenrock Coal Company (GCC) has been able to virtually put the old equipment away (except the problem solving quarter). In the process, GCC has saved many man-days and eliminated the more tedious parts of mine planning, such as picking elevations off a map with an engineer&apos;s scale and repetitive calculations. These savings have allowed GCC to do a more extensive job of mine planning as well as offer more alternatives, making GCC better prepared for possible economic changes. Mine planning, simply, involves looking at what has been done and deciding what needs to be done using various constraints. The application of this concept is not as easy as it sounds. The need for experience and insight cannot be replaced by a machine, but machines can supplement a person&apos;s ability by doing the bookkeeping and the repetitive work. Through the application of computers and their accessories, GCC has brought mine planning to a more modernized state. The following paper will detail the development and use of one system as used at GCC. Please note: In the figures and tables following, some of the data has been altered to protect confidential information used in mine planning.

Jan 1, 1983

By Francis P. Sinn

LOW prices have made 1938 a difficult year for the zinc industry of the world. Particularly in the United States, output had to be radically curtailed to bring production into line with consumption. Despite these unfavorable conditions, some additional plant construction is contemplated. In Jugoslavia, through co-operation with the Government, Trepca Mines is lo build a zinc plant to produce 10,000 metric tons annually, the plant to be ready for operation in July, 1941). Cerro de Pasco is proceeding with its plans for an electrolytic plant in Peru. A pilot plant, to be ready next summer, is under construction. In eastern Canada an electrolytic plant is planned in Quebec to treat concentrates from Yoranda and other mines but no defi-

Jan 1, 1939

By E. V. Kleber, V. F. Novy, R. C. Vickery

The constitutional diagram has been determined in part for the sgstem Gd-Fe. Seven intermetallic compounds have been found at compositions corresponding to the following Gd-Fe ratios; 2:3, 1.2, 1:3, 2:7, 1:4, 1:5, and 2:17. The GdFe, com-pound has a congruent melting point above 18000C, whereas all of the remaining compounds melt incongruently, A eutectic exists at 13 wt pct Fe at a temperature of 860°C. ALTHOUGH an increasing amount of information is becoming available on the metallurgy of pure rare earth metals, relatively few studies have been made on alloy systems of the rare earths with the transition metals; iron, nickel, and cobalt. Even less data are extant on gadolinium alloys although it could be expected that such alloys might possess interesting structural and magnetic properties. In this paper, we report investigation of the gadolinium-iron alloy system. Studies on systems containing nickel and cobalt will be presented in subsequent papers. Previous data on gadolinium-iron compounds have been reported by Endter and Klemm1 and Jep-son and Duwez.2 Both reports agree on the existence of the GdFe2 phase, which crystallizes with the C-15type structure (face-centered cubic). This is in accord with results of the present work. EXPERIMENTAL The gadolinium metal used was prepared by met-allothermic reduction of high purity gadolinium fluoride. A typical analysis of the metal thus produced indicated the principal impurities to be oxygen, 0.24 pct, and tantalum, 0.2 pct. The iron metal used for alloying was a reagent grade material. Alloys were prepared by arc melting mixtures of the respective metals. Appropriate quantities of the two component metals were carefully weighed, blended and compacted. The compacts were then melted in an arc furnace consisting of a water-cooled copper hearth plate and a water-cooled tungsten-tipped counter electrode contained in a brass vacuum chamber. The furnace was evacuated to an absolute pressure of less than 1 with the leak rate established as being less than 20 per min. The furnace was then back-filled to a pressure of 25 mm of Hg, with a 75 pct He-25 pct Ar mixture. Arc melting at 25 v and 300 amp was maintained for about 30 to 60 sec until the entire visible area of the sample became molten, by which time surface tension had drawn the molten metal pool into a large bead. After allowing the furnace to cool, the alloy button was inverted and the melting process repeated. A series of melts was made covering entire composition ranges from 100 pct Gd to 100 pct Fe. All samples were examined metallographically in the as-melted condition. As the phase diagram became rationalized, and differential thermal analysis had given indications of temperature arrests, annealing was carried out in vacuo or in argon. Generally, compositions containing more than about 60 pct Gd were heat treated at 750°C and alloys containing less than this quantity of gadolinium were annealed at 1000°C. Prolonged annealing times were of the order of 100 to 200 hr. Metallographic examination was repeated on the annealed materials. Although little material loss was noted during alloy preparation, chemical analyses were made on all specimens prepared. The following standard, analytical techniques were used. Samples were dissolved in hydrochloric acid; insoluble material was filtered off, ignited and fused with potassium pyro-sulfate. The cold melt was leached with dilute acid and the solution thus obtained added to the main sample solution. Gadolinium was always determined gravimetri-callv as oxide from oxalate ignition. Iron was removed from an aliquot sample by electrolysis on a mercury cathode at approximately six volts. Gadolinium in the iron-free electrolyte was then precipitated as oxalate which was subsequently ignited to oxide. Iron was determined volumetrically in an aliquot solution by reduction with stannous chloride fol-

Jan 1, 1962

By L. T. Larson

The spectral reflectivity of zirconium in light of 441 to 668 nanometers (nm) wavelengths and air immersion has been determined. Bireflectance and apparent-angle -of-rotation measurements show zirconium to be optically isotropic when examined in light of approximately 484 nm wavelength. There is a direct relationship between bireflectance and the tilt of the basal pole of zirconium from the surface normal. This relationship allows the determination of the spatial orientation of the basal pole of an individual single crystal within a coarse-grained poly crystalline section to within± 2 to 3 deg for angles of basal pole tilt from 0 to 90 deg. In recent years considerable attention has been given to the quantitative determination of optical properties of opaque minerals by use of vertically incident, plane-polarized light. In particular, Cameron&apos; and Cameron et a1.2 have developed criteria for the identification of a large number of anisotropic ore minerals based upon measurement of the apparent angle of rotation and the ellipticity or phase difference of the reflected light. It was shown by Larson and Pickle-simer3 that apparent-angle-of-rotation measurements may also be used to determine crystallographic orientations of grains of noncubic metals. In particular, it was shown that the basa.1 pole orientation in space of zirconium grains can be determined to ±3 deg for those grains with basal pole tilts of 10 to 90 deg from the plane of the section. Another, even more widely studied, optical property is reflectivity. cameron4 has commented upon measurement of the reflectance of plane-polarized, vertically incident light and Bowie and Taylor5 have made such measurements an integral part of their system of ore-mineral identification. Leow6 has reported on the spectral reflectivity of molybdenite and has used reflectivity values to calculate refractive indices and absorption coefficients. Cameron7 has made use of reflectivity values to ascertain aniso-tropic ore mineral symmetry and Piller and v. Gehlen8 have evaluated sources and importance of errors in reflectivity measurements as applied to calculation of optical constants. cambon9 has shown that reflectivity measurements using vertically incident, plane-polarized light are useful in the investigation of metals and in the identification of phases present in alloys. Bronson10 has made preliminary measurements on the optical anisotropy of beryIlium and Mott and Haines11 have published qualitative data on the intensity of light reflected from sections of bismuth, tin, and aluminum when these metals are microscopically examined under crossed polarizing plates. Koritnig12 has correlated the reflectivity of homogeneous solid solutions with their chemical compositions. From the above work and investigations in progress by this author, it is apparent that accurately determined values for the reflectance of vertically incident, plane-polarized monochromatic light from carefully polished surfaces of noncubic metals can prove useful in identification, composition determinations, and crystallographic orientation applications. Finally, reflectivity values, when measured in two media of differing refraction index and related to standards whose spectral reflectivities in these media are known, can be used to calculate optical constants such as refractive index and absorption coefficient. These constants may prove of use to those concerned with problems of electron band configuration. This paper reports the spectral reflectivity of zirconium measured in light of 441 to 668 nanometers (nm) wavelengths and air immersion. It also gives maximum bireflectance values for a prism section of zirconium in these wavelengths and shows how bire-flectance may be used to determine the crystallographic orientation of zirconium single crystals. Because of the lack of information on the reflectivities of the standards in oil immersion, no attempt is made to calculate the refractive indices or absorption coefficients although it is recognized that such values may be of fundamental importance. METHOD Single crystals of zirconium were cut by electro-discharge machining from a single-crystal rod grown from iodide bar by an electron-beam zone-melting process.13 The crystal sections were mounted in cold-setting epoxy resin and mechanically polished to a plane, uniform, bright surface. Each crystal was then chemically polished in a 26/26/43/5 mixture (by vol) of water, nitric, lactic, and hydrofluoric acids to remove the mechanically damaged and smeared surface layer. Final polish was obtained by electropolishing at 30 v in a bath of methyl alcohol and perchloric acid (98/2 by vol) at -70oc.14 Reflectivity measurements were made using a photometer system designed and developed at Oak Ridge National Laboratory and described in detail by Larson.15 Briefly, the reflectivity measuring system consists of a reflecting microscope; a double-beam, null-balancing photometer array; a mechanically driven microscope stage; and a direct X-Y readout of the reflectivity of the specimen relative to its orientation on the microscope stage. The measuring photometer receives its signal from the specimen through a slotted Wright occular placed on top of the photovisual head of the microscope. The reference photometer receives light through a flexible glass "light pipe" from a mirror in the reflecting system of the microscope. Monochromatic light is attained through use of interference filters (15-nm half-peak width pass bands) placed in front of a stabilized Vickers 12 v, 100 w, tungsten-filament, quartz-iodide lamp.

Jan 1, 1970

By B. Haimson, C. Fairhurst

A criterion is Proposed for the initiation of vertical hydraulic fracturing taking into consideration the three stress fields around the wellbore. These fields arise from (1) nonhydrostatic regional stresses in earth, (2) the difference between the fluid pressure in the wellbore and the formation fluid pressure and (3) the radial fluid flow through porous rock from the wellbore into the formation due to this pressure difference. The wellbore fluid pressure required to initiate a fracture (assuming elastic rock and a smooth wellbore wall) is a function of the porous elastic constants of the rock, the two unequal horizontal principal regional stresses, the tensile strength of the rock and the formation fluid pressure. A constant injection rate will extend the fracture to a point where equilibrium is reached and then, to keep the fracture open, the pressure required is a function of the porous elastic constants of the rock, the component of the regional stress normal to the plane of the fracture, the formation fluid pressure and the dimensions of the crack. The same expression may also be used to estimate the vertical fracture width, provided all other variables are known. The derived equations for the initiation and extension pressures in vertical fracturing may be employed to solve for the two horizontal, regional, principal stresses in the rock. INTRODUCTION Well stimulation by hydraulic fracturing is a common practice today in the petroleum industry. However, this stimulation process is not a guaranteed success; hence, the deep interest shown by the petroleum companies in better understanding the mechanism that brings about rock fracturing, fracture extension and productivity increase. Geologists and mining people became interested in hydraulic fracturing from a different point of view: the method may possibly be employed to determine the magnitude and direction of the principal stresses of great depth. Numerous articles in past years have dealt with the theory of hydraulic fracturing, but they all seem to underestimate the effect of stresses around the wellbore due to penetration of some of the injected fluid into the porous formation.1-4 Excellent papers on stresses in porous materials due to fluid flow have been published5,6 but no real attempt has been made to show the effect of these stresses in the form of a more complete criterion for vertical hydraulic fracturing initiation and extension. This paper is such an attempt. ASSUMPTIONS It is assumed that rock in the oil-bearing formation is elastic, porous, isotropic and homogeneous. The formation is under a nonhydrostatic state of regional stress with one of the principal regional stresses acting parallel to the vertical axis of the wellbore. This assumption is justified in areas where rock formations do not dip at steep angles and where the surface of the earth is relatively flat. This vertical principal regional stress equals the pressure of the overlying rock, i.e., S33 = —pD, where S33 is the total vertical principal stress (positive for tension), p is average density of the overlying material and D is the depth of the point where S33 is calculated. The wellbore wall in the formation is considered to be smooth and circular in cross-section. The fluid flow through the porous elastic rock obeys Darcy&apos;s law. The whole medium is looked upon as an infinitely long cylinder with its axis along the axis of the wellbore. The radius of the cylinder is also very large. Over the range of depth at which the oil-bearing formation occurs, it will be assumed that any horizontal cross-section of the cylinder is subjected to the same stress distribution, and likewise that it will deform in the same manner. STATE OF STRESS PRIOR TO DRILLING OF WELLBORE At a depth D from the earth surface within the oil-bearing strata, it is assumed that the following are 1References given at end of paper.

By R. S. Rickard, M. C. Fuerstenau

Anodic polarization curves for iron dissolution and cathodic polarization curves for copper deposition and ferric and hydrogen ion reduction were studied. These results were used to predict the relative rates of the reactions: The rates of the first two reactions were found to be first order with respect to the reacting ion, and the rale-controlling step was diffusion of the ions to the callzode surface. The rate of hydrogen ion reduction in an oxygen-free solution is dependent on the reciprocal of the square root of the hydrogen ion activity. In solutions containing oxygen, the rate of hydrogen reduction becomes dependent on the square root of the partial pressure of oxygen. At equal concentrations copper precipitation occurs about twice as fast as ferric ion reduction. In an air-saturated solution containing 0.01 M cupric ion at pH 2, the rate of hydrogen ion reduction zs about 10 times slower than that of copper precipitation. At pH values below 3, the rate of hydrogen reduction in oxygen-free solutions is very slozu. COPPER cementation has been utilized industrially for many years as a means of recovering copper from aqueous solutions. There are many different types of cementation plants, but all simply provide a means of contacting iron with relatively dilute copper solutions. In the past little or no attention has been paid to rates or mechanisms of the reactions involved. As a result, this and other studies&apos;-3 have been undertaken recently to establish the important parameters in this system. The reactions involved in copper cementation by iron are: Since transfer of charge is involved in every case, these reactions should be considered from an electrochemical point of view. In any electrochemical system involving electrolytic conduction, passage of electrons necessitates ion transfer to the respective electrodes according to Faraday&apos;s law. The current in the system will be proportional to the rate of ion transfer, and, therefore, when the current in the galvanic cell is known, the rates of the reactions involved can be determined. Galvanostatic electrode measurements5" are applicable for these electrochemical studies, in that with this technique polarization curves (current density vs electrode potential) are established by impressing a constant current through an electrode and measuring the electrode potential. Once the current density, electrode potential, and reacting area are known for each reaction in this cementation system, the rates of the iron-consuming reactions can be determined. EXPERIMENTAL MATERIALS Several metal electrodes were used in this investigation; they are shown in Table I. Solutions were made with reagent-grade salts and conductivity water. Air, nitrogen, and oxygen were employed. All of these gases were saturated with water and degreased prior to use. EXPERIMENTAL PROCEDURE The experimental work was divided into two general areas. The first area involved galvanostatic measurements, which were used to determine the rates of reactions as a function of various parameters. The second area comprised actual cementation experiments to check the rates predicted from the electrode measurements. Galvanostatic Electrode Experiments. Polarization curves were obtained using a standard galvanostatic technique5&apos;= with the apparatus shown in Fig. 1. The various electrode polarization experiments were run the same way except for changes in solution composition, polarity, and type of measured electrode. The general procedure involved the following steps: 1) a solution was made 0.5 M in sulfate ion and to the desired cation concentrations; this solution was placed in a constant-temperature bath and saturated with the desired gas; 2) the electrodes were cleaned and placed in the electrode holder; 3) the previously cleaned apparatus was assembled and immersed in a constant-temperature water bath (temperature controlled to ± 0.05"C); 4) the electrode was then positioned; the solutions were introduced, and the polarization meas-

Jan 1, 1969

By P. D. I. Honeyman

Changing trends in concentration, involving regrinding with the subsequent production of a finely divided, high-grade flotation product, presents a real problem to the modern copper smelter. In the treatment of such a material, handling difficulties are numerous and potential possible losses may be very great. In many plants, of course, preliminary roasting of the furnace charge remains an economical necessity. Under such circumstances, the operator has no alternative except to follow orthodox roaster reverberatory practice, though taking all possible precautions to avoid excessive dust losses and bad working conditions. In other plants, roasting is not only unnecessary but would be highly undesirable, and at best the charge would be merely dried before entering the reverberatory furnace. In the latter case the possibilities of raw charging loom large. The Miami plant of the International Smelting Co. handles the entire output of concentrates of the several mining companies operating in the Globe-Miami district. All of these companies produce a flotation concentrate which, at the Miami Copper Co. particularly, is all reground and is high in grade. In addition, the Inspiration Copper Co. ships a substantial tonnage of high-grade cement copper to the smelter from its leaching plant. Following the flow sheet of the original plant, all such material received was bedded, dried in Wedge furnaces and smelted in reverberatory furnaces. At times during the history of the plant it has been necessary to carry the drying operation further, to a partial roast, before reverberatory smelting. Since the charge contained over 80 per cent flotation concentrates, the handling of which in a dried condition was at best a dusty job, unusual precautions were taken to cut down dust losses. The Wedge furnace plant was equipped with a Cottrell treater and all hoppers and calcine cars were carefully designed to cut down dust loss in transferring the so-called calcine from hoppers to car and from car to furnace. In the furnace itself the dusting problem was a severe one. Arch erosion was very rapid and flues and waste-heat boilers rapidly filled up with a partly smelted flue dust.

Jan 1, 1934

By E. I. Larsen, E. F. Swazy, F. R. Hensel

High strength, high-conductivity copper-base alloys have found considerable use in the resistance welding and electrical industry in the form of castings, forgings, or wrought products. There are a number of parts utilized by these industries which would lend themselves to manufacture by powder metallurgical methods provided the required physical and electrical properties are obtainable with such methods. The present paper describes the results of a study of certain copper-base powder metallurgical products susceptible to precipitation hardening. Copper Powders The general types of commercially available copper powders are flake, spherical and electrolytic. Micrographs of these three types are shown in Figs. I, 2 and 3. The difference in particle shape is pronounced and obvious. The type of powder used is determined, or at least indicated, by the final properties desired in the finished article. The type of powder employed during the present investigation was electrolytic powder shown in Fig. 3, and was chosen because of its particular adaptability to the work described in this Paper. The screen and chemical analyses of this powder are shown in Table I. In the preparation of compacts of high electrical conductivity, the purity of the copper powder is of importance in addition to other factors, such as density and the state of internal stresses. These variables were studied briefly by pressing a number of compacts to various pressed densities, sintering them for one hour in hydrogen at 975OC and repressing. The size of the finished compacts was 1/4, by % by 8 in. The time interval from the application to the termination of pressure was approximately 20 sec. Some of the compacts were annealed before testing. The results are listed in Figs. 4 to 8, inclusive. In Fig. 4 the curves of pressed density vs. compacting pressure, and sintered density versus compacting pressure show the typical direct relationship of pressure and density. Compacting pressures exceeding about 30 tons per sq. in. result fiequently in expansion during sintering for the type of powder used. Fig. 5 indicates that variations in the initial pressed density within the range of about 5 to 6 grams per c, c., affect only slightly the pressure required to obtain a

Jan 1, 1946

By E. I. Larsen, E. F. Swazy, F. R. Hensel

High strength, high-conductivity copper-base alloys have found considerable use in the resistance welding and electrical industry in the form of castings, forgings, or wrought products. There are a number of parts utilized by these industries which would lend themselves to manufacture by powder metallurgical methods provided the required physical and electrical properties are obtainable with such methods. The present paper describes the results of a study of certain copper-base powder metallurgical products susceptible to precipitation hardening. Copper Powders The general types of commercially available copper powders are flake, spherical and electrolytic. Micrographs of these three types are shown in Figs. I, 2 and 3. The difference in particle shape is pronounced and obvious. The type of powder used is determined, or at least indicated, by the final properties desired in the finished article. The type of powder employed during the present investigation was electrolytic powder shown in Fig. 3, and was chosen because of its particular adaptability to the work described in this Paper. The screen and chemical analyses of this powder are shown in Table I. In the preparation of compacts of high electrical conductivity, the purity of the copper powder is of importance in addition to other factors, such as density and the state of internal stresses. These variables were studied briefly by pressing a number of compacts to various pressed densities, sintering them for one hour in hydrogen at 975OC and repressing. The size of the finished compacts was 1/4, by % by 8 in. The time interval from the application to the termination of pressure was approximately 20 sec. Some of the compacts were annealed before testing. The results are listed in Figs. 4 to 8, inclusive. In Fig. 4 the curves of pressed density vs. compacting pressure, and sintered density versus compacting pressure show the typical direct relationship of pressure and density. Compacting pressures exceeding about 30 tons per sq. in. result fiequently in expansion during sintering for the type of powder used. Fig. 5 indicates that variations in the initial pressed density within the range of about 5 to 6 grams per c, c., affect only slightly the pressure required to obtain a

Jan 1, 1946

By W. R. Bean

Probably few, if any, of the many serious problems confronting malleable foundries have been more difficult of solution than the question as to why malleable that is ductile, black in fracture, and normal in all respects before galvanizing should, by that process, be rendered brittle, brilliantly crystalline or "white" in fracture, and of low resistance to shock. So far as we are aware, the technical literature contains no data or discussions on this subject, except two referencesl,2 of a general character. It is apparently a question that every one concerned, producer and consumer alike, has been willing to evade as far as possible. Various theories as to the cause of the deterioration have been given but such checking of these theories as we have done indicates that there was no sound basis for most of them. This work on the galvanizing of malleable was first undertaken in 1916, and has continued until the present time. We now feel that for all practical purposes we have reached a solution and are glad to be able to offer it in a form that can be readily applied to production processes. It is impossible to give here a detailed account of the early work done on this problem. A great number of tests were instituted and an enor-

Jan 1, 1923

By W. R. Bean

Probably few, if any, of the many serious problems confronting malleable foundries have been more difficult of solution than the question as to why malleable that is ductile, black in fracture, and normal in all respects before galvanizing should, by that process, be rendered brittle, brilliantly crystalline or "white" in fracture, and of low resistance to shock. So far as we are aware, the technical literature contains no data or discussions on this subject, except two referencesl,2 of a general character. It is apparently a question that every one concerned, producer and consumer alike, has been willing to evade as far as possible. Various theories as to the cause of the deterioration have been given but such checking of these theories as we have done indicates that there was no sound basis for most of them. This work on the galvanizing of malleable was first undertaken in 1916, and has continued until the present time. We now feel that for all practical purposes we have reached a solution and are glad to be able to offer it in a form that can be readily applied to production processes. It is impossible to give here a detailed account of the early work done on this problem. A great number of tests were instituted and an enor-

Jan 1, 1923

By J. L. Gillson

The big mass of anorthosite in the Lake Sanford district and the bodies of titaniferous magnetite that occur in a small area near the south margin of the mass have been described repeatedly, and the puzzling problems of the genesis of the rocks and ores have stimulated the deductive reasoning of geologists for a hundred years. Some of these men have taken a leading part in describing the anorthosite rock and forming hypotheses concerning its origin; some have contributed most to the study of the ore deposits; and some have made classical Studies introducing a basic approach to the problems of the anorthosite rock and genesis of the titaniferous magnetites. Much of the writing on the problems of rock and ore genesis has been based on physical-chemical reasoning rather than on field and microscope observations of the rocks and ores. Most of these geologists conclude that the anorthosite was formed by true magmatic crystallization, involving previous settling or squeezing out of ferromagnesian minerals from the parent magma. The associated gabbro is a separate segregation or later intrusion, and the lighter colored and finer grained facies of the anorthosite is either a chilled border zone of the anorthosite or the result of granulation by crushing of the coarse, dark blue rock of the main mass. This blue rock, called the Marcy type, is named after the highest peak in the range. The finer grained and lighter colored rock is called the Whiteface, after another mountain appropriately named for a cliff colored by this facies of the anorthosite.

Mar 1, 1956