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By Carl Zapffe

THE object of the Bradley process is to free manganese oxide from its associated gangue and separate the contained iron oxide by dissolving the manganese and precipitating it from the solution. 'The fundamental features of the process are : making. both 1 a manganese ore and an iron ore; effecting a separation of manganese .and. iron by means of selective roasting; leaching- the manganese from the roasted ore by using ' ammonium sulfate; precipitating the manganese by using the ammonia gas generated during leaching; fixing the precipitate by oxidizing with air; breaking down and reforming the ammonium sulfate, so that daily very little additional ammonium sulfate beyond that originally charged into the system is required; washing the manganese precipitate and the iron-silica residue and evaporating the liquor to conserve the dissolved salts in the moistures of these two products and 'to reduce the sulfur content,; drying the precipitates; magnetic wet-concentration of the iron-silica residue; sinteriny the manganese-and .the' iron-concentrates.

Jan 1, 1929

By J. V. Vogel

Jan 1, 1969

By Horace Mann

A FEW years ago, it was generally thought that from 15 to 18 per, cent. of zinc oxide was the upper limit of a workable lead blast-furnace slag. With slags above this zinc-oxide content, the furnaces gave so much trouble because of hearth, wall, and crucible accretions that the campaign was very short. The time lost in cleaning out the frozen furnaces, for it was seldom possible to blow them out, and blowing in was so great that it was considered uneconomical to attempt the running of high-zinc slags, even if this were metallurgically possible. It is true that there are, references to one or two slags much higher in zinc than the foregoing,1 but the average smelterman regarded these, as freaks and not to be considered for regular furnace work. One or two plants, notably the plant of the United States Smelting Co, at Canyon City, Colo., ran charges, higher in zinc. At this plant, the zinc-oxide content of the charge was frequently 20 per cent. and higher but the slags from these furnace's seldom ran over 10 to 12 per. cent. zinc oxide. The furnaces were run with a large volume of air under a relatively low pressure, a low smelting column, and a very hot top; as a result, a large amount of zinc was volatilized. Even with the low smelting column and hot top, accretions caused much trouble and barring, down was a daily occurrence. At the time most of the theories on lead blast-furnace work were promulgated or worked out, it was necessary to run a furnace with a cold top in order to avoid an excessive loss due to fines and fume. At the same time, the smelting conditions had to be such that the lead and silver would be reduced and would enter the bullion. The slag had to be liquid but the charge must not give excessive accretions either in the hearth or on the walls of the furnace. This forced the operators to run the furnaces with a comparatively low blast, which, in turn, caused a small fuel consumption per unit of time with the accompanying result of a low working temperature.

Jan 8, 1925

By AIME AIME

A DOCUMENT of progress and of great interest to engineers is the report of the Military Affairs Committee of 'the Engineering Council, which has just been accepted and sent to the secretary of War. It provides .a plan whereby civilian engineers holding commissions in the Reserve Corps may; with their con- sent, be called into service of the army during peace at any time, either with troops in the field or in a consulting capacity on any government engineering work. The Military Affairs Committee finds ample authority in the military bill passed by Congress on June 4, 1920, for this arrangement and also for extending the privilege to military engineer, officer-s of the regular army to engage in civilian work during times of peace. It is hoped that the Secretary of War will adopt the suggestions and put the program outlined into effect. This is a constructive piece of work comparable to the efforts of the military Committee before the war which developed so much in the way of preparedness, particularly in the program of military lectures which, held in the auditorium in the Engineering Societies Building, became so popular that each lecture had

Jan 1, 1920

By K. E. Gray, M. S. Seth

Equations of elasticity for transversely isotropic, axisymmetric, homogeneous, porous media exhibiting pore fluid pressure were formulated. Using an analogy between thermal and porous body stresses, it was shown that the solution for a transversely isotropic porous body may be obtained by incorporating body forces and the stresses due to a boundary load into the corresponding solution for the thermal stress problem. Equations of elasticity ad the thermal analogy method were used to determine transient horizontal, tangential, and vertical stresses and radial displacement in a semi-infinite cylindrical region when either a constant pressure or a constant rate of flow is maintained at the wellbore. The vertical and tangential displacements are zero from the conditions of the problem. A numerical analysis was made of the solutions obtained by using a digital computer to determine the relative influence of each system variable. Considering rock as a porous body with internal fluid pressure generally gives results significantly different than considering the rock to be nonporous; the directional character of rocks leads to significant differences as compared to results based upon the common assumption of isotropy. Stress gradients are high near the wellbore but die out away from the well. Radial stresses are compressive or neutral, whereas tangential stresses are tensile, neutral or compressive, depending upon the boundary conditions and physical properties of the system Vertical stresses are compressive for an unbounded system. For constant wellbore injection rate, the vertical stress is proportional to the rate of fluid injection and decreases with time, whereas the radial and tangential stresses increase with time. At a given location, the radial displacement generally is very dependent upon time. INTRODUCTION A realistic appraisal of the state of stress in subsurface rock formations would be of considerable interest and use to the petroleum industry. For example, knowing the state of stress in proximity to a wellbore would be of fundamental importance in designing a fracturing operation or, more important, of clearly understanding the conditions necessary to produce rock failure of desired dimensions and geometry. Understanding conditions necessary for rock failure at the wellbore would also be of utility in a preventive sense. For example, borehole stability is an important consideration for many rock formations, and knowledge of the stress state at and near the wellbore under conditions of substantial pressure gradient due to fluid flow would be of great value. When fluid flows through a porous body which is initially at some uniform stress level, the following forces generate stresses at any point in the body. (1) Forces due to nonuniform pressure distribution. With increasing pressure the elements of a body are compressed. Such compression cannot proceed freely in a continuum when the pressure is not uniform throughout, and thus, stresses due to flow of fluid are set up. (2) Pore fluid pressure. This gives rise to normal stresses whose value at any point is the product of areal porosity and the fluid pressure. Although the fluid exerts uniform pressure, the stresses it creates in an anisotropic body may not be the same in all directions since the areal porosity in an anisotropic porous body is a direction-dependent quantity. This consideration leads to the concept of directional porosity. (3) Body Forces. The flow of the moving fluid imparts a force to the rock matrix, the magnitude of which depends upon the pressure

Jan 1, 1969

By D. M. Clippinger, J. J. Eidel, J. E. Frost

At Ithaca Peak, one of three peaks situated on Duval Corporation's Mineral Park property, a 'Single pulse of quartz monzonite magma intruded the isoclinally folded Precambrian Cerbat complex consisting of schist, quartzfeldspar gneiss, and amphibolite. The magma reacted with the Precambrian rocks, yielding a quartz-diorite rim. As the magma crystallized within the rim, it produced, progressing in'ward, annular bodies of quartz monzonite porphyry, quartz porphyry, and a distinctive quartz porphyry containing abundant podiform, tabular, and irregular quartz masses. These quartz masses are spatially associated with discontinuous crenulate and tabular quartz veinlets. Following crystallization, the Ithaca Peak stock and part of the surrounding Cerbat complex were fractured, producing a stockwork of predominantly northwest and northeast-trending fractures. The stockwork was then mineralized during a period of decreasing temperature by: ( 1) quartz-pyritechalcopyrite veinlets without distinct selvages and with distinct alteration envelopes in which orthoclase was altered to quartz and sericite; (2) quartz-pyrite-chalcopyrite veins and veinlets with distinct selvages and without distinct alteration envelopes; and (3) pyrite-chalcopyrite- galena-sphalerite veins. The Ithaca Peak stock was pervasively sericitized or argillized. The Mineral Park property is surrounded by a zone of propylitization Alteration and mineralization are coextensive in space and were, at least in part, coincident in time. The Mineral Park property possibly was elevated and exposed twice prior to its present exposure. The protore has been enriched by a factor of three. The Ithaca Peak supergene ore body is conformable with present topography and lies above the present water table. The shape of the ore body was controlled by erosion and oxidation of the previously enriched mineralization. Hematite, goethite, and jarosite present at the surface indicate a high primary pyrite environment, but it is possible to recognize that a small proportion of veins and veinlets contained greater amounts of chalcocite and chalcopyrite than pyrite. The igneous facies on Ithaca Peak are the products of differentiation within a solidifying rim according to Bowen's Reaction series. The innermost facies contain more quartz and orthoclase than the outer facies. Late magmatic quartz in the case of Ithaca Peak contains small amounts of pyrite and molybdenite. It is suggested that this quartz-sulfide mineralization, may also have been the product of differentiation the product of differentiation, may indicate that the later hydrothermal mineralization may also have been the product of differentiation.

Jan 1, 1968

Jan 1, 1903

By F. I. Stalkup

Vapor-liquid phase equilibrium experiments have been conducted in a static equilibrium cell on mixtures of a light, 45 API stock- tank gravity reservoir fluid and a rich hydrocarbon gas containing approximately 55 mole per cent of intermediate hydrocarbons. Both apressure-vs-composition study of the gas and a simulated reservoir fluid, and a multiple-batch contact simulation of the condensing-gas-drive oil recovery process were performed. In the latter experiments equilibrium gas and liquid compositions were analyzed. Also, conventional, "condensing-gas-drive", long-tube displacement experiments of the reservoir fluid and gases of various richness were performed. The results of these experiments could not be satisfactorily interpreted by the conventional pseudo-ternary-diagram representation of multicom-ponent phase behavior. The results seem to be explained better by considering a bubble-point surface and a dew - point surface joined in a plait-point locus. Portions of the plait-point locus cannot be "seen" directly by the rich hydrocarbon gas because of curvature of the dew-point surface. In such a system, continuous injection of the rich gas over stationary reservoir fluid might form a zone of contiguously miscible compositions from pure rich gas to pure reservoir fluid by: (1) saturating the reservoir fluid with injected gas to the bubble-point surface; (2) creating by mass transfer with fresh injected gas a path of contiguously miscible compositions along the bubble - point surface to the plait-point locus; and (3) creating by mass transfer with additional injected gas a path of gas compositions along the dew-point surface up to the point where direct miscibility results between dew-point fluid and the injected rich gas. INTRODUCTION The use of the pseudo-ternary-phase diagram to illustrate miscible displacement phase behavior has been discussed by several authors.5,7 Such a representation of phase behavior is not rigorous, but the ternary diagram nevertheless gives a qualitative picture of what actually occurs in a miscible displacement process. Fig. 1 is a typical illustration of miscible displacement phase behavior by a ternary diagram. The multicomponent hydrocarbon system is divided into three pseudo-components: a light fraction containing methane and nitrogen, an intermediate fraction containing ethane through hexanes plus carbon dioxide, and a heavy fraction containing heptane and heavier components. A two-phase region is bounded by a dew-point curve and a bubble-point curve, which are joined at the critical point. The concept deduced from such a representation for miscible displacement by a condensing-gas-drive process is as follows: a rich gas G, which lies to the right of the limiting tie line through the critical point C, is injected into the reservoir and contacts reservoir fluid L, saturating the reservoir fluid to give bubble-point fluid L1 and equilibrium dew-point gas GI. Continued injection of rich gas changes the composition of the saturated liquid L1 through a series of liquid compositions lying along the bubble-point curve, until the critical composition C is reached, at which point direct miscibility with the rich gas is achieved. Some equilibrium gas with compositions lying along the dew-point curve from G1 to C is also formed in this process. Thus, continuous injection of rich gas forms a

Jan 1, 1966

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By J. P. Smith

DURING the winter of 1946 to 1947 potash operations in Germany, France and Spain were visited by the author. The U. S. Department of Commerce, through its Field Intelligence Agency Technical, sponsored the inspection of German properties by representatives of the American Potash Industry. Vast deposits of potash salts occur in the above-mentioned countries, and the production and marketing of these salts are important in their respective economies. Germany An area of some ten thousand square miles of north central Germany is underlain by lenses of potash salts interbedded with greater thicknesses of sodium chloride or common salt. These salt measures are relict deposits from the evaporation of an arm of the Zechstein (Permian) Sea which formerly covered northern Europe. During the peak year of 1940, Germany produced salts containing 1,860,000 tons of K,O and, next to coal, potash is its most important mineral raw material. The German deposits are found in the synclinal areas flanking the Flechtingen, Hartz Mountain and Thuringian uplifts, and, to the north they lie beneath the plains of Hannover. The regional dip of the salt measures is to the north, hence, lenses of potash found at depths of 500 to 1000 m* in the Two general depositional provinces of potash concentrations are recognized: (1) the main basin, and (2) the subsidiary basin. The main basin embraces the producing districts of Stassfurt, Sud Hartz, Halle, and Hannover-Braunschweig. From J. P. SMITH, Member AIME, is Clzief Geologist, U. S. Potash Co., Carlsbad, New Mexico. New York Meeting, February 1948. TP 2621 H. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received May 26, 1948. 40 to 45 pct of the German production comes from this basin. The Werra-Fulda district, producer of 50 pct or more of the German potash, lies in the subsidiary basin. Salt Stratigraphy: Five commercial potash zones or beds are recognized. The three beds present in the main basin are: The Stassfurt bed that occurs near the top of the older salt, and the Ronnenberg and Riedel beds in the younger salt occurring 200 to 300 m, respectively, above the Stassfurt bed. The Stassfurt bed is found over the entire main basin, while the Ronnenberg and Riedel are restricted to the Hannover area. Two potash beds occur in the Werra basin. These are the Thuringian, or lower bed and the Hessen or upper potash bed that occurs 60 m above. These beds lie 210 and 150 m, respectively, below the position of the Stassfurt bed, and are restricted to the Werra basin. The upper bed is 2.5 to 11.5 m in thickness, and the principal ores are hartsalz with varying thicknesses of carnallite. The lower bed averages 3 m in thickness, and contains hartsalz. The upper bed is presently being mined, and the

Jan 1, 1951

By E. A. Anderson

THE copper-zinc phase equilibrium diagram has been the sub-ject of many investigations. Until recently, however, the boundary of the terminal solid solution of copper in zinc (eta) has not been thoroughly investigated. This paper reports determinations of the solid solubility of copper in zinc at temperatures from 100° to 400° C., the course of the liquidus and solidus for the eta solid solution and determinations of the peritectic temperature and peritectic point for the reaction between epsilon and the melt to form eta. The liquidus of the eta phase was determined by thermal analysis and the solidus by the microscopical examination of specimens quenched from temperatures above and below the solidus. The temperature of the peritectic horizontal was obtained by thermal analysis and the com-position at the peritectic point was determined by extrapolation of the solid solubility boundary of the eta phase to the peritectic horizontal. The solid solubility boundary of the eta solid solution was investigated very carefully. Particular care was used to achieve equilibrium in the alloys at each temperature selected. The X-ray, electrical con-ductivity and microscopical methods were used in determining the solid solubility limits. The X-ray method measures the changes in the solvent lattice with increasing solute content and in this manner locates the composition of the alloy at which no further change in the solvent lattice takes place, the limit of solid solubility. The method of electrical conductivity measures the conductivity of the alloys of a graded series of compositions, whereby the solubility limit is indicated by a discontinuity in the conductivity-

Jan 1, 1934

By Bobby P. Faulkner

The Tennessee Copper Co.'s flotation plant, refer- T red to as London Mill, processes approximately 4800 tons of a massive complex sulfide ore per day. The ore is predominantly pyrrhotite and pyrite, the other sulfides being chalcopyrite, sphalerite, and a small amount of galena. Magnetite of economic value is also present. There are four concentrates produced. In decreasing tonnage, these are iron, copper, zinc and lead. The ore feeding the mill is a composite of ores from five mines which vary in grade. Therefore, in order to provide a fairly constant feed to the mill, the ore is blended several times before reaching the flotation machines. The flotation plant is divided into three main sections: bulk, copper and zinc. Fig. 1 shows a simplified flowsheet. The first two sections, the bulk and copper, were the two sections studied most closely in utilizing the computer.

Jan 11, 1966

By W. V. Green

Creep of tantalum was measured at temperatures from 0.6 to 0.89 of the absolute melting temperature. The creep curves include first, second, and third stages. Steady-state creep rate depends on the fourth power of stress. The activation energy for creep throughout this temperature range is approximately 114 kcal per mole, measured by the aT technique. Subgrain formation occurs as a result of creep strain, and pile-up dislocation arrays are observed in etch-pit patterns. BECAUSE of its high melting point-which is exceeded only by those of rhenium and tungsten—and its high room-temperature ductility compared to most of the other high-melting-point metals, tantalum will undoubtedly be utilized in an increasing number of high-temperature applications. Alloying studies directed toward increased high-temperature strength must use data on tantalum itself as a base line in order to evaluate the effectiveness of the alloying additions. However, to date, no systematic study of creep of tantalum at temperatures above one-half of its melting point has been reported in the literature. Conway, Salyards, McCullough, and Flagella1 have measured linear creep rate of tantalum sheet as a function of stress, but at only one temperature, 2600°C. This paper describes a relatively thorough study of the high-temperature creep of tantalum. METHOD Material Tested. The commercially supplied, l/2-innch-diameter tantalum rod used for this work was electron-beam-melted, cold-forged, rolled, swaged, cleaned chemically, and vacuum-annealed for 1 hr at 1000°C, all by its manufacturer. The vendor's analysis included 60 to 170 ppm C, 3.4 to 4.2 ppm H, 60 to 80 ppm 0, 15 ppm N, and a hardness ranging from 66 to 81 Bhn and averaging 76 Bhn. Creep eimens Used. Two creep-tested specimens are shown in Fig. 1. The 1/4 in.-diameter gage section was 3/4 to 1 in. long, and terminated either at shoulders 5 mils high or at 20-mil-diameter tantalum wires spot-welded to the circumference of the gage section. Both kinds of shoulders served equally well as fiducial marks for optical strain measurements. The spot welding did not alter the creep behavior in any detectable way; the 5-mil- high sharp shoulders did not result in any detectable localized effect on the strain. Before testing, each tensile bar was first mechanically polished -id then electrochemically polished according to the method referred to by Forgeng2 as the "Thompson Ramo Woolridge" method, which was suitable for tantalum after small adjustments of technique were made. Two tensile bars tested at low stresses had 1/8-in.-diameter gage sections and utilized only the weight of the bottom grip for the applied load. Although these diameters were smaller than were desired for other reasons, applied loads were known with high precision in the tests in which they were used. Testing Procedure. Two different constant-load creep-testing machines were employed, one of which has been described by Smith, Olson, and Brown.3 In both, the tensile bar is held vertically on the axis of a cylindrical tungsten tube or screen heater by threaded tungsten grips. The tensile bars and associated grips are heated by radiation from the incandescent heaters, which are heated by their own electrical resistance. Both testing machines use pins to hold the bottom grips in place. The load is applied to a tensile bar through hanging weights, a constant force-multiplication lever, a pull rod sealed to the chamber lid, and a top grip threaded to the pull rod at one end and to the tensile bar at the other. In one machine, the vacuum seal is a bellows with a low spring constant; in the other, the seal involves a rotating "0 ring". With the latter, rotation is converted to translation with a crank shaft, so that elongation of the tensile bar is accommodated with no change of tensile load. The incandescent tensile bar is viewed by an external optical system through slots in the radiation shields and heater, and an enlarged image is projected on a ground-glass screen. Gage-length measurements are made on this image with cathetometers on traveling microscopes. With regard to creep-test results, the two machines were identical. Thorium oxide coatings were applied to the threaded ends of the tensile bars, to prevent diffusion welding of the tensile bars to the grips during testing. Specimen temperatures were measured with an L. & N. optical pyrometer which had been calibrated against a standard carbon arc, and were corrected fir window absorption by calculation from the measured spectral transmittance of the quartz observation windows. Longitudinal temperature gradients in the tensile-bar gage length and temperature drifts during testing were detectable but small, and were estimated to be 10°C or less. Accuracy of temperature measurement was confirmed by comparing the temperature measured on the surface of a special

Jan 1, 1965

By J. A. Pusateri, M. A. Orehoski, N. R. Arant

Plant studies on commercial-size ingots and laboratory experiments with induction furnace heats have demonstrated that the major source of ingot cracks is associated with two conditions arising during top-pouring practice: 1—solidification during pouring, and 2—turbulence created by the impact of the stream. Methods of controlling the two factors were effective in eliminating or significantly reducing ingot cracks. BECAUSE the process of removing surface defects from hot-rolled product is so costly, the steel industry is striving constantly to develop methods of preventing, or at least decreasing, the occurrence of surface defects. Investigations have revealed steel-making and processing variables related to major surface defects, and controlling these variables has led to improvements in surface quality. However, the fundamental causes of major surface defects, such as ingot cracks, have not been determined; consequently such defects persist. At the Research and Development Laboratory of the United States Steel Corp. in Pittsburgh, a seam research program was initiated to determine the fundamental causes of certain major defects. As a part of the program, ingot cracks in killed, finegrained C1020 steel were selected for study. A cost survey indicated that, of the steels produced in sizable tonnages, carbon steels in the range of 0.18 to 0.23 pct C content require the most conditioning. Since this is particularly true of C1020, any im-provement of surface quality that might be effected from the study would be beneficial. Also, since the frequency of ingot cracks is exceedingly high for this grade, the steel would provide an excellent opportunity for a thorough study of the ingot-crack-ing problem. Why steels in this carbon range tend to exhibit more ingot cracks than do other steels was not considered in the investigation; the mechanism of ingot-crack formation was of paramount importance. Also, only the top-pouring practice was considered in the investigation, because this pouring procedure is used more extensively than others. In this study, ingot cracks are defined. as deep surface defects that sometimes are observed in an ingot prior to rolling but usually are observed during the initial stages of rolling on the primary mills. These defects may occur at any angle to the rolling direction but are most prominent in the transverse or nearly transverse direction. The appearance of ingot cracks on the rolled product varies with respect to their angle of formation and with the extent of rolling after their first occurrence. Ingot cracks are also termed "deep seams," "arrowheads," "irregular cracks," and "transverse cracks." Fig. 1 shows ingot cracks in a rolled bloom. This report summarizes: l—the exploratory investigation of commercial-size ingots; 2—the labor-atory investigations related to determining the source of ingot cracks and developing corrective methods; and 3—the plant evaluations of laboratory methods of decreasing ingot cracks. Exploration of lngot Cracks in Commercial Ingots Materials and Experimental Work: At the Du-quesne Works of the United States Steel Corp., five heats of killed, fine-grained C1020 steel were selected for the exploratory phase of the seam-research program. The heats were made by open-hearth practices that are considered most conducive to good surface quality. They were top-poured into 22x25 in. big-end-up hot-topped molds. One as-cast ingot and four other ingots rolled to the following cross-sectional sizes were set aside from each heat: 16x20 in.; 9 1/2x10 in.; 5x5 in.; and 2x2 in. The processing of the heats, from the time of charging in the open hearth furnaces to the end of the rolling operation on the primary mill, was observed carefully and recorded. The cast ingot and the four rolled ingots from each heat were examined for surface defects. The cast ingots were split longitudinally near the vertical center plane to expose the ingot structure beneath badly cracked regions. Also, a series of transverse sections was cut at about 1 in. intervals in a badly cracked area of one ingot. All sections were ground, polished, examined by sulphur printing and deep etching, and photographed. The rolled ingots

Jan 1, 1955

By V. E. Christensen

AT most smelting plants, forced draft, induced by high stacks or fans, is used to carry the gases away from the furnaces, roasters, or sintering plants. Gases moving under forced draft carry varying amounts of solids in the form of dust and fume. Where the weight of the solids is material, and the metal content high, it is usually profitable to treat the gases to recover these solids. Baghouses, Cottrell treaters, and settling chambers are the common forms of plants used to recover solids from gases. To check on the efficiency of these plants it is necessary to know the volume of gas leaving the plant and the amount of solids carried by the gas. As the volume of gas is equal to the product of the velocity of that gas and the cross-sectional area of the flue, the determination of the volume includes the measurement of the area of the cross section and the determination of the velocity. The velocity is generally measured by means of the Pitot tube and Ellison differential pressure gage, although low velocities are best determined by means of an anemometer. The dust concentration is determined by passing a measured volume of sample through a filter and weighing the dust caught. From this the dust concentration per unit of volume may be calculated. It is necessary to assume that the gas is homogeneous or that each cubic foot of the gas contains the same weight of dust as every other cubic foot. Having the volume of gas passing through a flue per unit of time, and the dust concentration of the gas per unit of volume, the amount of solids may easily be calculated.

Jan 1, 1935

By R. M. Douthwaite, G. Birkbeck

The effect of grain size and specimen dimensions on the occurrence and magnitude of a yield point drop in pure iron has been examined. The tests were done at room temperature. The results indicate that gain size is the critical factor determining whether a yield drop occurs. The specimen diameter:gain size ratio does not influence the magnitude of the yield drop for the range of gain size and specimen diameters investigated. HUTCHINSON,' petchY2 and worthington3 have investigated the grain size dependence of the upper yield stress (uUYP) and the yield point drop, ouyp - aLYP, in Armco iron, mild steel, and Si-Fe, respectively. These authors used center-annealed wires to avoid stress concentration from specimen shoulders and to ensure uniformity of the applied stress. Coarsegrained specimens show no yield point drop; the yield point drop then increases as d-'I2 increases (where d is the grain diameter). These results can be understood in terms of Petch's analysis2 in which the magnitude of amp depends on the strain rate in the (limited) number of grains deforming plastically at the upper yield point. If N grains per unit volume are undergoing plastic deformation, the strain rate in the deforming grains is l/Nd3 times higher at the upper yield stress than when the whole specimen deforms homogeneously. If N is constant and independent of grain size at uUyp, then all the grains are deforming when ~d~ = 1, so there is no yield point drop. At finer grain sizes, the yield point drop is given by: where AU, is the friction stress increase corresponding to a tenfold strain rate increase. Christ, Smith, and Burton studied the upper yield point in 0.050-in.-diam wire specimens prepared from zone-refined iron. Each end of the 2; -in. specimens was soldered to a & -in. diam steel ball and the load applied through the two balls. There was a yield point drop in specimens with grain diameters less than 0.1 mm; no drop was observed in specimens of grain diameter greater than 0.1 mm that were free from veining substructure, but specimens of grain diameter 0.129 mm, annealed in the y range, showed an upper yield point. and this was associated with the presence of a veining substructure in these specimens. Christ et al. suggested the upper yield point occurs when more than a specific number of grains fill the specimen cross section so a multiplicity of slip is required to initiate plastic deformation. Table I summarizes the published data on the grain size at which the yield drop disappears. On the basis of this data the ratio of specimen diameter:grain diameter = 5 to 27 appears to be the critical value for the occurrence of a yield point drop. Thus, petch2 interprets the appearance and magnitude of the yield point drop in terms of the limited number of grains deforming plastically at uuyp, whereas Christ et a1. consider that the occurrence of the yield drop depends on the ratio specimen diame-ter:grain diameter. The published data cover a wide variety of materials so some variation between the results is to be expected, but the size range covered in the data of Table I is rather limited. In an attempt to discover whether the specimen diameter:grain size ratio or the grain diameter is critical in determining

Jan 1, 1969

By David Moskowitz, Ira Binder, Robert Steinitz

THE hard refractory borides of the transition elements of the 4th, 5th, and 6th groups of the Periodic System have been the subject of a number of recent investigations.'-' It is well known now that most of these elements form several different borides, and Kiessling8 has summarized the rules which govern to some extent the arrangements of the boron atoms in the various structures. Melting points of a few borides have been published." The systems Fe-B, Ni-B, and Co-B have been reported," but, as these borides are rather low melting, they are outside of the groups of boron compounds considered here. Brewer' has tested the stability of various borides and estimated a number of eutectic temperatures between different borides, but in no case was the complete system of a transition metal and boron investigated. The phase diagram becomes of special importance if the preparation of the borides from the elements in powdered form is considered; the lowest eutectic temperature will determine the first appearance of a liquid phase. Also, the knowledge of high temperature phases, if they exist, is important for the preparation of bodies from these borides by hot pressing or sintering. During the investigation of various metal borides,7 it was found that there were more boride phases existing in the Mo-B system than reported by Kiessling." They occur, however, only at temperatures above 1500°C and were, therefore, not found by him. This led to a study of the equilibrium diagram of the Mo-B system. ranging from 0 to 25 pct B and from room temperature to the liquidus. Part of this investigation was reported during the "Research in Progress" session at the 1952 Annual Meeting of the AIME.11 Raw Materials and Preparation of the Borides The raw materials used were commercial molybdenum and boron powder, both supplied by the Molybdenum Corp. of America. The molybdenum powder was 99+ pct pure? while the boron powder contained about 83 to 85 pct B. A large percentage of the impurities in this powder was oxygen, with the rest formed by iron, calcium, and unknown substances. The low purity of the boron used was, however, not considered detrimental to the final product, as most of the impurities evaporated at the high temperatures at which the borides were formed. The final product always had a minimum purity of 96 to 98 pct (figured as molybdenum and boron), with carbon, iron, and probably oxygen being the remaining products. Carbon is usually present as graphite. The chemical analyses always confirmed the compositions which corresponded to the crystallographic structures as determined by X-ray diffraction, and the boron content of the finished product agreed closely with that of the starting mixture; no boron was lost during the boride preparation. The chemical analysis methods employed for molybdenum and boron were previously described by Blumenthal.12,13 The powders were mixed by hand in the desired proportions, compressed at room temperature under low pressure, and then heated under hydrogen to about 1500" to 1700°C in a graphite crucible to form the borides. Usually, the three well-known borides Mo,B, MOB, and Mo,B,, which are stable at room temperatures, were prepared in this way, and all other compositions were made by mixing these borides in various ratios or by the addition of molybdenum or boron powders for the very low or very high boron contents. Preparation of two-phase compositions directly from the elemental powders was tried only occasionally to check whether equilibrium could be reached in this way. Experimental Procedures The stable borides were mixed in the desired ratios and heated under hydrogen in graphite crucibles to various temperatures. The well insulated crucibles were heated in a high frequency induction furnace. Special care was taken to obtain exact temperature measurement, which proved much more difficult than originally anticipated. It is believed that individual temperature measurements have an error of less than ±25ºC, while melting or transformation temperatures are accurate within ±50°C. The temperatures were measured with an optical pyrometer which was aimed at the closed end of a graphite tube extending down into the crucible. close to the samples. Attempts to measure directly through the hydrogen exit stack failed. The crucible arrangement is shown in Fig. 1. Heating was done at a slow rate to be sure that the temperature inside the crucible was uniform. The specimens were kept at the final temperature for about 30 min. For the investigation of high temperature phases, some samples were quenched. They were heated, without atmosphere protection, in a very small graphite crucible which could be rapidly removed from the high frequency coil, and dropped into water. These quenched samples were afterwards annealed to establish the equilibrium at lower temperatures. The melting points or the positions of the solidus and liquidus lines were determined by heating the specimens to various temperatures and examining them at room temperature for evidence of a liquid phase. These results were checked later on by thermal arrest curves, especially to determine the exact position of the eutectic temperature line. For this purpose about 200 g of the boride were melted in a graphite crucible, in an arrangement similar to Fig. 1. Slow cooling was assured by very good

Jan 1, 1953

By G. F. Comstock

In the literature of metallography there is a large amount of material describing the various non-metallic inclusions found in iron and steel, and the appearance of sulfides, silicates, oxides, or alumina in steel under the microscope is fairly well known. The inclusions found in non-ferrous metals are, however, not so well known, at least judging from published writings, and the author has been interested in examining small castings of copper, brass, or bronze with certain inclusions purposely mixed with the metal, to see what was the characteristic appearance of each kind of inclusion, and if they could be readily distinguished from one another. The method employed in most cases consisted in overheating and oxidizing a small charge of copper, then cooling it somewhat, and adding a suitable amount of the element whose oxide it was desired to observe. This element was stirred in well and given time to react with the oxygen in the copper, then the melt was poured in a sand mold in the form of a cylinder about 21/2 in. (63 mm.) in each dimension, with a sprue about 11/2 in. (38 mm.) in diameter and 3 in. (76 mm.) high on top of the cylinder, the sprue forming the only riser. Samples for examination were cut sometimes from the center of the casting, and sometimes from the sprue or riser. A few of these samples were cast in chill molds. The appearance of sulfides was studied in an alloy containing 10 per cent, each of tin and lead, with which a flux of plaster of Paris was used. The appearance of foundry sand was studied in several alloys, one of them having sand stirred into the metal intentionally, and others having cut into the molds badly when poured, so that the castings were spoiled by included sand. As all this work was done on alloys having copper as the chief ingredient, the natural starting point was copper oxide, the appearance of which in a micro-section is well known. Cuprous oxide is soluble in molten copper, but separates out in freezing and forms a eutectic containing 3.5 per cent. Cu20, or 0.39 per cent. oxygen. If there is less

Jan 1, 1919

By J. J. Luchessa

HAULAGE was one of the many problems to be solved in the successful handling of the Miami Copper Company's low-grade orebody. The ore extracted had to be increased from 1000 to 18,000 tons per 24 hours over the existing track-age and haulage way. This called for increased speed, longer trains, in¬creased car capacity, and a block signal system so as to maintain a fixed schedule and headway. The motive power in service at the time of this transition consisted of Baldwin-Westinghouse 6-ton trolley locomotives. (See Fig. 3.) These locomotives were purchased to handle twenty inverted-V-bottom side-dump cars of 60 cu. ft. capacity. Dimensions were limited as to height on account of ore chutes, width on account of short radius curves, and length of 12 ft. from bumper to bumper- so that the locomotives could be handled on the man and material hoist which has a cage length of 121/ ft. The limited length made it possible to bring the locomotives to the surface for periodic overhauling and major repairs such as changing wheel tires, gears, and

Jan 1, 1934

By S. Saito, P. A. Beck

The crystal structure of MoNi3 was determined by means of X-ray diffraction. This structure is isotype with that of ovgered TiCu3. The lattice parameters are: a. = 5.064A, bo = 4.224A, co = 4.448A, and zf 0.157. If the orthorhombic distortion (slight relative to the corresponding orthohexagonal unit cell) is disregarded, the structure may be described in terms of a close-packed ordered atomic layer, stacked in the sequence: abab. The structztres of ordered TiCu3 and TiAl3 are homotectic. The three types of ordered hexagonal phases, iso-structural with TiNi3, MgCd3, and VCo3, are known to occur in AB3 alloys of transition elements of the first, second, ad third long periods. It was noted1 that phases with the TiNi3 structure occur selectively in alloys of Ti-group elements with Ni-group elements. In AB3 alloys of Ti-group and V-group elements with Co-group elements the AuCu3-type structure predominates.' The vCO3 structure, which was determined very recently,' has hexagonal symmetry, but the actual atomic arrangement here, too, is rather closely related to the ordered cubic structure of AuCu3-type. However, an ordered hexagonal close-packed structure of the MgCd3-type occurs in MOCO33 and WCO3.4 Consequently, the question arises as to whether or not the crystal structure of MoNi3 is also of the MgCd3-type. Grube and winkler5 found that MoNi3 has a hexagonal close-packed structure with a = 2.54A and c/a = 1.65. They pointed out that some additional weak diffraction lines could be observed in the powder pattern, which may have been due to an ordered atomic arrangement in this phase. However, no detailed information was obtained by them and the structure was apparently not further investigated by others. The present work was, therefore, undertaken in an attempt to determine in detail the structure of MoNi3, and to investigate the possibility of ordering. EXPERIMENTAL METHODS Alloys used in the present work were arc-melted in a water-cooled copper crucible under helium atmosphere. Electrolytic nickel and molybdenum, both 99.9 pct pure, were used. Chemical analyses were not made, but the melting loss was not higher than 2 pct for any alloy. Ingots were first homogenized at 1200°C for 48hr, quenched, heavily cold worked, and then annealed at 820" or 860°C for 1 week, followed by quenching in cold water. Powder specimens for X-ray work were prepared by crushing the heat-treated solid specimens. In order to remove strains, the powders were reannealed in evacuated scaled fused silica capsules for 6 hr at the same temperature at which the corresponding solid specimens were annealed. X-ray photographs were taken with an asymmetric focussing camera, using unfiltered CrK or CuK radiation. EXPERIMENTAL RESULTS The X-ray diffraction patterns of alloys containing 20.8, 25, and 26.4 at. pct Mo, homogenized at 1200°C, showed the face-centered-cubic structure of the Ni-base a-solid solution. It was revealed, however, by micrographic examination that the 26.4 at. pct Mo alloy contained in addition very small amounts of a second phase, in accordance with the phase diagram.6 On the other hand, the 20.8 at. pct Mo alloy after annealing at 820°C gave the X-ray diffraction pattern of the ordered face-centered-tetragonal MONi4.7 In this pattern several additional weak diffraction lines were also observed, corresponding to the strongest diffraction lines of MoNi3. The alloys containing 25 and 26.4 at. pct Mo after annealing at 820" or 860°C gave X-ray diffraction patterns, as shown in Tables I and 11, corresponding to MoNi3. Each one of the reflections which could be tentatively indexed on the hexagonal close-packed cell of Grube and Winkler,5 with the exception of the basal plane reflections, was split into a doublet, as seen in Table I. Since microscopically the alloy consisted of a single phase, it seemed probable that the lattice of MoNi3 is actually slightly deformed, as compared with the tentative hexagonal unit cell. In addition to these diffraction lines, several weak lines were also present, as shown in Table 11, which could not be indexed at all on the hexagonal close-packed cell considered. Satisfactory indexing of all diffraction lines observed was found to be possible by using an orthorhombic unit cell with ao = 5.064A, ft = 4.224A, and c = 4.448A. These values, whose accuracy is estimated to approximately ± 0.008A, correspond to 95.14A3 for the volume of the unit cell, and to an X-ray density of 9.50 g per cm3. If no attention were paid to the weak reflections listed in Table II, a reduced -unit cell of half the volume (a = 2.532A, b = 4.448A, and c = 4.224A), closely related to the orthohexagonal cell, might be used. The dimensions of the orthohexagonal cell of the same volume as the reduced cell are: a = 2.562A, b = 4.437 A, and c = 4.183A. It may be seen that in the reduced cell the a axis is slightly shorter, while the b and c axes are slightly longer than those corresponding to the orthohexagonal cell of the same volume. This slight orthorhombic distortion is re-

Jan 1, 1960