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By A. R. Troiano, A. B. Greninger

There is need for an adequate working hypothesis that would describe at least qualitatively the crystallographic mechanism for the transformation from austenite to martensite in steel. A general theory would not only be of great assistance in the correlation of existing data and in planning future experimentation, but would also form the basis for an eventual explanation of the property changes that accompany lattice transformations. The mechanism of martensite formation described in the following pages is the outcome of two new experimental determinations: (1) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite, and (2) the measurement and analysis of the change in position that a volume of austenite undergoes when it transforms into a crystal of martensite. For this latter study, the stereographic analysis of shear was employed; this method greatly simplifies the solution of lattice-shear problems, and some space is devoted to its description. Lattiice Relationships and Habits PREVIOUS WORK The lattice relationships between austenite and martensite in carbon steels have been studied by Kurdjurnow-and Sachs,' and by Wassermann;2 and in iron-nickel alloys by Nishiyama.3 Wassermann,2 and Mehl and Derge.4 The studies by Kurdjumow and Sachs and by Wassermann were made on single (austenite) crystals of quenched 1.4 pct carbon steel, and the results of these two independent studies agree closely with the postulated lattice relationships: (III)r||(0ll)a [101]r [111]a [1] Both Nishiyama and Wassermann worked with an alloy of iron plus 30 pct nickel (all austenite at room temperature), and "martensitic alpha" was formed by cooling in liquid air. They agree that the lattice relationships for these conditions are: (lll)r||(011)a [112]r[011]a [2] Mehl and Derge worked with a range of iron-nickel alloy compositions centered about 30 pct nickel. They concluded that when the transformation takes place near room temperature or above, relationship [l] holds, but if the same specimen is made to transform at -195°C, relationship [2] obtains;intermediate temperatures evidently produced a combination of these two relationships. Sachs and co-worker~,1,7 as well as Nishiyama,3 have proposed transformation mechanisms for martensite formation.* Both of the mechanisms picture the transformation as initiated by shearing movements along the octahedral [Ill] plane of austenite, followed by suitable expansion and contraction to complete the transformation. These mechanisms have been described and commented upon by Mehl, Barrett, and Smith,8 Mehl and Derge,4 Wassermann,2 and others, and generally accepted by investigators in this field. Greninger and Troiano9 have recently published the results of a detailed study of the shapes and orientation habits of martensite crystals in plain-carbon and nickel steels. They found that, contrary to previous assumptions, martensite plates form not along the octahedral planes but along austenite planes of very high indices; these results were in line with those of previous studies of martensite reactions in nonferrous alloy systems by Greninger and coworkers.6,10 Greninger and Troiano concluded that the transformation theories of Kurdjumow and Sachsl and of Nishiyama3 are untenable. Phragmén11 reached a similar conclusion. EXPERlMENTAL METHODS The object of this particular study was the evaluation of (1) lattice relationship between austenite and martensite, and (2) relationship between the martensite lattice and the martensite plate. The technique used for solving these problems was similar to that used by Greninger6 on martensitic structures in 8 copper-aluminum alloys. Briefly, the method consists of grinding and polishing a specimen on a surface parallel to an individual martensite plate and thus exposing a single martensite crystal for an area of l to 3 mm. The orientation of this exposed martensite crystal is then determined by means of a back-reflection Laue X ray pattern.12 Another pattern is obtained from the matrix crystal, and a stereo-graphic plot of data from these two patterns then provides the solution to the problem. It is necessary to repeat this process on several crystals in order to determine whether or not the solution is unique.

Jan 1, 1950

By L. O. Millard

Stockpiles in the minerals industries serve a wide variety of purposes. Usually they are for surge between stages of processing, for a dependable plant feed in anticipation of delays, or to provide for single or double shift mining in conjunction with round-the-clock milling. Often surge piles are necessary to insure a uniform feed to continuous process equipment where the material is received as an intermittent or variable flow. Extensive use is made of stockpiling for the primary purpose of blending. The significant fact about all stockpiling of bulk materials is that storing and reclaiming are two separate and distinct operations and they may present widely different problems in the selection of methods and tools.

Jan 10, 1959

By B. F. Bush

THE coal-fields of Missouri, situated hi the northern and western portion of the State, are distributed, in whole or in part, over 57 counties, embracing an area estimated by Mr. Broad-head to be practically 23,000 sq. miles, including small detached beds and outliers in St. Louis, St. Charles, Lincoln and Warren counties in the eastern part of the State. This area includes about 8,000 sq. miles of Upper or Barren Measures, 2,000 sq. miles of exposed Middle, and 12,420 sq. miles of exposed Lower Measures. In a general way, the Missouri coal-field is bounded on the east by an imaginary line entering the northern part of the State just east of the 92c1 Meridian and passing across the State in a southwesterly direction to a point on the Kansas-Missouri line a little below the southern boundary of Barton county. An important part of the field overlaps this line and extends down the northern side of the Missouri river, under¬lying the greater part of Randolph, Howard, Boone and Audrain counties. In all, 34 counties produced coal during the year 1903. Fig. 1 shows the position of the coal-fields in Missouri. GEOLOGICAL FEATURES. The Coal Measure formations, all of the Carboniferous age, rest unconformably upon the rocks of the sub-Carboniferous or Mississippian series, and, in some cases, upon the rocks of the Devonian and Silurian ages. From their outcrop on the eastern and southeastern borders of the field, the Measures dip west to northwest at the rate of 10 ft. per mile, reaching a maximum thickness estimated by

Jan 1, 1905

By A. F. Peterson

MUCH has been said and written about the engineer shortage. The mining branch in engineering has lagged during the past several decades. I can think of two institutions, formerly prominent in that field, that have discontinued this department and another that has branched from a purely mining school into various forms of engineering. Conversely, I do not recall any institutions that have added mining to their curricula. I believe that this action is in direct response to the demands of incoming students. But I also believe that while there is a specific demand for civil, mechanical, and electrical engineers in the highly complicated mining operations of today, our need for mining engineers capable of assuming top responsibility for mining operations is unchanged.

Jan 3, 1957

By I. Cornet

INTRODUCTION WITH the greatly expanding use of magnesium during the war, it appeared necessary to the War Metallurgy Committee that the notch sensitivity of magnesium alloy extrusions be further investigated and the influence of various factors upon notch sensitivity be noted. Accordingly, the National Defense Research Committee of the Office of Scientific Research and Development placed a research contract with the University of California, supervised by the War Metallurgy Committee. The work discussed herein was done under "Restricted" Project NRC-21, reported in Dec. 1943 1; it has been released for publication by the O.S.R.D. SCOPE OF THE INVESTIGATION The notch sensitivity of various magnesium alloy extrusions was determined under axial tension, and also under several conditions of nonaxial tension. Hardness, grain size and other metallographic features were observed; stress-strain data were obtained, and the chemical compositions of the alloys were determined, in order to correlate these quantities with the notch sensitivity. Notch sensitivity under axial tensile load was determined for a few specimens which had been cold worked to various degrees by tensile prestraining. Magnesium alloy extrusions studied included Dowmetal 0, X, J, and M. For comparison, extrusions of aluminum alloy 24S-T, cast bars of aluminum alloy I22-T2, and cast bars of magnesium alloy C were also tested, The specified chemical composition of these alloys is given in Table I. All bars tested were within specification limits of composition. Investigation of the tensile notch sensitivity of various magnesium alloy extrusions, under conditions of axial and eccentric load, showed little or no correlation with stress-strain or other conventional data. Since the many uncontrolled variables present might mask significant relationships, one alloy was selected for intensive study. Magnesium 0 alloy extrusions were subjected to experimental heat treatments, and the changing hardness, tensile strength, microstructure, and notch sensitivity observed. EXPERIMENTAL TECHNIQUES AND PROCEDURES Tensile Testing Bars used for axial loading were machined with 3/8 in.- and with 1/4-in. minimum diam, and included specimens with 6o° V notches (Fig I and 2). Each V-notched specimen was roughed out carefully and then finished with a honed tool. These V-notched bars were sampled frequently, sectioned, polished, and examined at 500 X magnification to control

Jan 1, 1948

By Robert L. Voss, Richard D. Hagni

Sparry dolomite from all of the operating mines in the Viburnum Trend of Southeast Missouri have been found by cathodoluminescence microscopy to reveal a systematic pattern of banding resulting from a growth zoning within individual dolomite rhombs. Four principal bands have been recognized throughout the entire Trend and each of the major bands contain even finer internal banding. Minor bands a few microns in width can be correlated in specimens collected ten's of kilometers apart along the trend. The first three principal dolomite bands decrease from south to north. This feature, together with the fact that the white sparry dolomite crystals decrease in abundance from south to north in the Trend, suggests that a major source for the fluids was from the south. The application of cathodoluminescence microscopy to crystalline dolomite demonstrates a strong correlation between ore grade and the intensity of internal banding and dissolution textures.

Jan 1, 1985

By H. Rosenthal, A. L. Jamieson

The action of mercury on stressed brass to produce cracks was known before Moore, Beckinsale and Mallinson1 showed that actual season cracking did not occur spontaneously but could be induced by ammonia. These investigators studied other substances, including diphenylamine, without finding that anything other than ammonia could cause season cracking Grimston2 reported season cracking in cartridge cases stored in wooden boxes wetted with dilute sulphuric acid pickling solution. Season cracking associated with sulphur dioxide, water vapor and air has been reported by Johnston,3 although he reported that trimethylamine and pyridine did not cause cracking. Jevons4 has ascribed season cracking of brass in certain instances to trimethylamine, "aldehyde amine," "ketone amine" and pyridine, but no experimental work was done evidently to prove this definitely. Pyridine was investigated by Morris,5 who found it to have considerable cracking power. In the present investigation, the object was a qualitative evaluation of a number of representative amines with respect to their ability to cause season cracking. Thus it was desired only that an appreciable vapor pressure of each amine be obtained in order to make the test as severe as possible, without attempting to test equivalent concentrations for comparative purposes. MEthods Specimens TWO types of specimen were used: 1. Unannealed 70-30 brass CUPs formed from 0.040-in. thick sheet. Height of cup Was 13/8 in. and diameter was 17/8 inches. 2. First draw pieces of caliber .50 cartridge cases in the unannealed condition (70-30 brass)- The cups were representative of a thin wall and thin base specimen, whereas the draw pieces have a thick base (1/4 in.) and a thick wall (approximately 3/32 in.). Both types of specimens contained high residual stress and cracked in less than one minute in a solution of I per cent mercurous nitrate and I per cent nitric acid provided that this was receded by a 30-sec. pickle in 40 per cent nitric acid. Specimens were prepared as follows: (1) degreased in trichlorethylene, (2) rinsed in H2O, (3) pickled 5 min. in 10 per cent by volume H2SO4 (1.84 SP. gr.), (4) rinsed in H2O, and (5) dried. Amirtes Tested In selecting the amines, representatives of the three series of amines, and one series of substituted amines were chosen. The aliphatic series was represented by the methyl and ethyl primary, secondary and tertiary amines. These are the simplest aliphatic amines. For the aromatic series, the phenyl primary, secondary and tertiary amines were selected as being the simplest. The heterocyclic series was represented by pyridine, which is a simple heterocyclic base (tertiary amine).

Jan 1, 1944

By J. P. Givry

The bath and the liquid metal in the aluw~inuw~ electrolytic cells are moving under the action of the Laplace forces. Consequently there are differences in level at the interface of the liquid. This phenomena is studied by means of a computer; the characteristics of the mathematical model used are presented with the results corresponding to two typical cases. This study gives a new and origi~zal interpretation of magnetic ej-jects; their action depends very closely on the hydraulic phenomenon which explain the sensibility of the cells to the slope and thickness of solid bath frozen around the pot. MAGNETIC effects produced in the electrolytic cells used for the production of aluminum are known to exist, a factor whose importance is well-known by producers through its influence on cell operation and output. In particular, these effects bring about movements in both the bath and metal as well as interface variations in level that are detrimental to sound electrolysis . A direct study of these effects by means of an experimental device would raise a number of problems particularly difficult not to say impossible to solve in the present state of techniques. It is for this reason that we had recourse to an electronic computer for working out the speed and pressure distribution within the liquid in the cells. We have assumed that all other possible causes for movement, such as thermal convection and evolution of gas at the anode, are acting without any connection with magnetic effects, and that consequently we may study each of these causes separately. A basic cause for magnetic effects lies in the presence of Laplace forces within the bath and metal. Electric current and magnetic field distribution have been calculated with the help of an electronic computer, and two communications about it have already been made to AIME.* 1) PRESENTATION OF THE MATHEMATICAL PATTERN In order to solve this problem, it was essential to assume a number of simplifying hypotheses with regard to both the geometry of the actual cells and the phenomena themselves. A first simplification consisted in assuming that the movements of the conducting liquid modify neither the electric currents nor the magnetic fields. In consideration of the magnitude of the values involved this assumption seemed accep-tible. 1.1) Finding the Equation of the Problem. The problem raised consisted in determining the flow of two viscous immiscible liquids with different densities subjected in a complex environment to gravity and Laplace forces. As a matter of fact, the sum of the external forces acting on the liquids is: F = JAB +pg where F = volume energy, B = magnetic field, J = current density, p = specific gravity, g = gravity. In the case of a laminar flow and assuming that the liquids are Newtonian and incompressible liquids, the equations governing movements are the following: 1) Navier Stokes' equation written in vectorial form: In fact one tries to find a steady-state solution, so aVx/at = 0; besides, one assumes that the movements are slow enough for quadratic terms such as Vy(a Vx/ay) (of round about the square of speed) to be neglected in front of the viscosity term: pAV, so

Jan 1, 1968

By Dewey J. Sabin

THE Rio de Canada Honda placer property is situated at an altitude of 5500 ft. above sea level in the San Luis Mountains of the Province of San Luis, Argentina. The mine is reached by 70 km. of fair truck road, from the nearest railway station on the Ferrocarril Buenos Aires al Pacifico. The Pan-American airport at Villa Mercedes, 1.40 km. distant, serves as the most convenient point for shipment of gold. Placer mining in the Rio de Canada Honda dates from the time of the Incas and the present native population depends on the gold washed from this river and the adjacent arroyos as a means of livelihood as did the many generations before them. They dig pits to bedrock where they are not driven out by water, and mine the bedrock gravel by means of tunnels and caves. No timber is available and the ground is supported by rock cribs carefully built with the boulders encountered; or with angular blocks of slate rock taken from quarries on the surface.

Jan 1, 1936

The following is a partial list of members and guests who called at Institute headquarters during the period July 10, 1917, to Aug. 10, 1917: G. A. Collins, Seattle, Wash. Norman Picot, Melbourne, Aust. A. D. R. Galloway, Komfrodua, W. Africa. W. E. Pomeroy, El Paso, Tex. F. Lynwood Garrison, Philadelphia,; Pa. Francis R. Pyne, Elizabeth, N. J. Geo. M. Henderson, Bland, N. M. W. L. Remick, W. Norfolk, Va. L. B. Herr, Jr., So, Bethlehem, Pa. M. F. Sayre, Schenectady, N. Y. Zay Jeffries, Cleveland, 0. Leighton Stewart, New York, N. Y. H. H. Lauer, Allentown, Pa. Randolph D. Talmage, Joplin, Mo. Wm. B. McKinlay, Yonkers, N. Y. H. J. Volker, Ossining, N. Y. A. N. Mackay, Republic of Colombia. Dwight E. Woodbridge, Duluth, Minn. Edmund Newton, Minneapolis, Minn. Kwong Wu, Peking, China. J. N. Acosta has resigned his position as mining engineer for the Shannon Copper Co., Gleeson, Ariz., and is now engaged as consulting engineer for Lower California, Mexico, with headquarters at San Diego, Cal. L. D. Albin, formerly assistant general sales manager of the Ingersoll-Rand Co., was appointed general sales manager on July 25,1917.

Jan 9, 1917

By M. T. Martinson, I. W. Nicholson, C. J. Chindgren, F. P. Williams, L. C. Bauerle, S. F. Ravitz

THE vanadiferous shales of southeastern Idaho and southwestern Wyoming constitute the largest known reserve of vanadium in the United States.1 These deposits have never been exploited except for the relatively small amounts of vanadium recovered by the Anaconda Copper Mining Co. in the treatment of phosphate rock from southeastern Idaho. The major domestic source of vanadium has been the sandstone ores of southeastern Utah and southwestern Colorado. Early in World War II, it appeared that these ores could not meet the greatly increased demand for vanadium, so the investigation described in this report was undertaken to develop processes for the recovery of vanadium from the Idaho-Wyoming deposits. The utilization of these deposits became unnecessary, however, because of greatly expanded production from the Utah-Colorado sandstone ores and the continued availability of vanadium from other sources, chiefly Peru. The major use of vanadium is as an alloying agent in the manufacture of high-quality steels. Vanadium constructional steels usually contain 0.05 to 0.20 pct vanadium, which refines the grain and increases the strength, elastic limit, and resistance to shock and fatigue. Vanadium tool steels not used in high-speed work contain 0.10 to 0.60 pct whereas high-speed tool steels contain 1.0 to 4.0 pct. Vanadium compounds are used as catalysts (principally for the oxidation of SO2 to sulphuric acid and of naphthalene to phthalic acid) and in the paint, chemical, ceramic, dye, and printing industries. The selection of the particular ore deposit to be exploited would involve consideration of many factors besides the metallurgical results that might be obtained. Chief among these would be the reserves of ore available, the grade of the ore, and the mining costs. As very little was known about any of these factors, it was necessary to investigate methods of treatment of all the ores under consideration, working with samples obtained in the course of the exploration work, even though they were not positively representative of the whole deposit from which they were taken. Because of wartime conditions prevailing when this investigation was started, first consideration was given to processes that could be put into operation most quickly and would involve minimum use of strategic materials, even though these processes might not be the most economical.

Jan 1, 1947

By Roscoe E. Bell

BETWEEN 1945 and 1948 the author made studies of the western phosphate industry and its potentialities. These included an appraisal of the opportunities for western development of the industry, studies of production costs, of market potentials, of transportation economics, and of industry location. This paper will be directed toward pointing up the factors which have an important bearing on the establishment of fertilizer plants in the western area. Industry Location Factors: There are, of course, an infinite number of possible organizational setups which might require consideration. However, the phosphate industry is simple enough so that studies of the most probable alternatives can be made conveniently. The salient factors which require special consideration in such a study are: (I) the location of the raw materials, (2) the location, size, and character of the present and potential markets, (3) the location of energy sources and materials required for fertilizer processing, (4) the location and capacity of present manufacturing facilities, (5) the cost of assembling the materials and energy needed in manufacturing, and (6) the cost of distributing the manufactured product. Raw Material Supplies: Rock phosphate is the raw material for the manufacturing of phosphate fertilizer. In the United States the important known deposits of this material are located in three general areas (fig. 1). The western deposits, comprising about 60 pct of the nation's supply, are in the four-state area—Idaho, Wyoming, Utah, and Montana. The Florida deposits comprise roughly 38 pct of the national supply. The Tennessee deposits, comprising about 2 pct of the national supply, have been the most important source until recent years. The western deposits, which are virtually undeveloped, have not been used to any extent to meet the nation's need for phosphate rock and phosphate fertilizer. Fertilizer Markets: The large national markets for fertilizer are in the midwestern and eastern United States (fig. 2). The principal far-western markets are along the Pacific Coast, especially in California. Until recent years the western markets have been extremely limited, whereas the markets in the eastern United States have long been established and manufacturing facilities have been provided to meet these needs (fig. 3). In recent years the western markets have expanded very rapidly, continuing to grow throughout the war years and postwar period at a similar rate. The question always arises as to whether this is a temporary war-swollen market which will shrink back to its original size as soon as the present agricultural price levels drop. In order to answer this question consideration must be given to the character of the market (fig. 4). I have considered seventeen western and midwestern states in the western market area where transportation costs from the western deposits are equal to or lower than those from Florida. They include all states west of a line drawn through Chicago, Kansas City and the western boundary of New Mexico. In the mewar period this was a small market totaling only 37,000 tons of P,O, annually. The 1946 total for this same area was approximately 200,000 tons. Considerably more fertilizer would have been used in 1946 had adequate supplies been available. Estimates of future markets are difficult to make, but we do have some indices that are useful. The

Jan 1, 1951

By Roscoe E. Bell

BETWEEN 1945 and 1948 the author made studies of the western phosphate industry and its potentialities. These included an appraisal of the opportunities for western development of the industry, studies of production costs, of market potentials, of transportation economics, and of industry location. This paper will be directed toward pointing up the factors which have an important bearing on the establishment of fertilizer plants in the western area. Industry Location Factors: There are, of course, an infinite number of possible organizational setups which might require consideration. However, the phosphate industry is simple enough so that studies of the most probable alternatives can be made conveniently. The salient factors which require special consideration in such a study are: (I) the location of the raw materials, (2) the location, size, and character of the present and potential markets, (3) the location of energy sources and materials required for fertilizer processing, (4) the location and capacity of present manufacturing facilities, (5) the cost of assembling the materials and energy needed in manufacturing, and (6) the cost of distributing the manufactured product. Raw Material Supplies: Rock phosphate is the raw material for the manufacturing of phosphate fertilizer. In the United States the important known deposits of this material are located in three general areas (fig. 1). The western deposits, comprising about 60 pct of the nation's supply, are in the four-state area—Idaho, Wyoming, Utah, and Montana. The Florida deposits comprise roughly 38 pct of the national supply. The Tennessee deposits, comprising about 2 pct of the national supply, have been the most important source until recent years. The western deposits, which are virtually undeveloped, have not been used to any extent to meet the nation's need for phosphate rock and phosphate fertilizer. Fertilizer Markets: The large national markets for fertilizer are in the midwestern and eastern United States (fig. 2). The principal far-western markets are along the Pacific Coast, especially in California. Until recent years the western markets have been extremely limited, whereas the markets in the eastern United States have long been established and manufacturing facilities have been provided to meet these needs (fig. 3). In recent years the western markets have expanded very rapidly, continuing to grow throughout the war years and postwar period at a similar rate. The question always arises as to whether this is a temporary war-swollen market which will shrink back to its original size as soon as the present agricultural price levels drop. In order to answer this question consideration must be given to the character of the market (fig. 4). I have considered seventeen western and midwestern states in the western market area where transportation costs from the western deposits are equal to or lower than those from Florida. They include all states west of a line drawn through Chicago, Kansas City and the western boundary of New Mexico. In the mewar period this was a small market totaling only 37,000 tons of P,O, annually. The 1946 total for this same area was approximately 200,000 tons. Considerably more fertilizer would have been used in 1946 had adequate supplies been available. Estimates of future markets are difficult to make, but we do have some indices that are useful. The

Jan 1, 1951

By L. L. McDaniel

Copper smelters of various kinds have operated in the Morenci district since 1872, but all have been abandoned with the exception of the present Morenci Smelter of Phelps Dodge Corporation, which was completed in 1942. During the five-year period starting in 1937, the Morenci ore body was prepared for open pit mining, pilot mill test work was carried out, and a complete reduction works, of which the Smelter is a part, was designed and erected. Actual construction work on the Morenci Smelter was started in the fall of 1940, and warming up of the units began on April 1, 1942. Charging of the reverberatory furnaces commenced on April 18, 1942, and the first anode copper was produced on April 26, 1942. The smelter was originally designed to handle the production of the Morenci Concentrator on a 25,000 ton per day program, but by the time the smelter was in operation, plans were already underway to increase the smelter capacity to handle the production of the concentrator which was being enlarged to 45,000 tons a day capacity as a war-time necessity. This extension to the smelter was completed and the new units were put in operation toward the beginning of 1944. The original smelter consisted of a smelter crushing plant, bedding plant, two direct-smelting reverberatory furnaces with two waste-heat boilers on each furnace, three converters, an anode department, a stack, and all of the usual accessory smelting equipment. The extension consisted of increasing the bedding plant from three to five beds, the reverberatory department from two to four furnaces, and from four to eight waste-heat boilers, and the converter department from three to six converters. A third converter aisle crane was added and additions were made to the flue systems and conveyor systems throughout the smelter; but no change was made in the smelter crushing plant or the anode department, and the same stack was used for all additional Smelter units. A blister casting machine was installed at that time in the south end of the converter aisle to handle excess and emergency production above the capacity of the anode department and in 1947 a converter aisle skull breaker and a lime burning plant were added as the final units for a complete plant. The choice of direct smelting over calcine smelting for the Morenci Smelter was made after careful study by members of the Western organization of Phelps Dodge Corporation and after test runs on direct smelting of Morenci concentrate had been made at the Douglas Smelter of Phelps Dodge Corporation. The Morenci furnace charge is made up of comparatively high grade concentrate with no ores of smelting grade available and with only flux, a small amount of copper precipitate and the usual amount of smelter secondaries to be smelted with the concentrate. The simplicity of direct smelting for this charge and the large amount of waste-heat steam available from direct smelting operations were factors influencing the decision to adopt direct smelting for Morenci. The design of the Morenci Smelter and the type of units selected followed best experience at the Douglas Smelter of Phelps Dodge Corporation. A description of the original smelter before operations started was given in an article in the May 1942 issue of Mining and Metallurgy. The purpose of the present article is to describe the enlarged Morenci Smelter, with a discussion of metallurgy and operating practice and to show tabulations of operating and metallurgical results obtained. Because of beginning operations during the early years of World War 11, many problems caused by labor shortage were encountered, but no major difficulties developed in starting the new plant. However, because of labor shortage, full scale Smelter production was not reached until the fall of 1946. Fig 1 shows a general plan of the Morenci Reduction Works. The arrangement of the smelter equipment is shown in Fig 2, a sectional view of the smelter is shown in Fig 3, and the smelter flow sheet is shown in Fig 4. Metallurgy The metallurgy of direct smelting, being more or less fixed by the character of the charge, is not subject to the control available in calcine smelting. Slags may be modified by the addition of suitable fluxes, but the grade of the matte is determined almost entirely by the iron:copper ratio of the concentrate. The direct smelting operation involves distributing the wet concentrate along the sidewalls and in the bath of a reverberatory furnace by means of some suitable feeding device and raising the temperature of the charge so that first the moisture is driven off, then the first-atom sulphur is eliminated, and finally the sulphide portion of the charge melts and runs into the bath, carrying with it the non-sulphide portion which has been partially fluxed to form a suitable slag. The fusion of the non-sulphide portion is completed by contact with the irony converter slag which is regularly being poured into the reverberatory furnace. The smelting rate of the charge is influenced by the mineralogi-cal composition of the sulphide portion of the concentrate and by the composition and amount of the non-sulphide portion including the fluxes added. The copper in Morenci concentrate is chiefly in the form of chalcocite, intimately associated with pyrite, and non-sulphide content is very low so that

Jan 1, 1950

By F. O. Blackwell

It is roughly estimated that some three hundred companies in the United States engaged in mining and the kindred arts now employ electricity in their operations. As all these plants have been installed within the last few years, it is evident that mining engineers have been quick to appreciate the great advantages of the use of electricity and adopt it for their many requirements. In

Jan 1, 1894

PRECEDING chapters on thermochemistry, and the reactions in and between metal and slag phases in the bath of the furnace tend to emphasize the equilibrium or "static" conditions in the furnace and process, such as the total amounts of heat from fuel combustion or from certain bath reactions, the concentration relationships between slag and metal at the steady state for certain reactions, and the like. Such data are obtained essentially by means of the logic of thermo- dynamics, which helps to determine the energy change between initial and final states in a process as well as to define its equilibrium or steady-state condition, but which is not concerned with the rate of change in the process or with the mechanisms or path followed between initial and final states. These questions of just "how it works" and "how fast" belong to the kinetic aspect of any process; their answers are helpful in speeding up or slowing down and thus controlling intelligently its operation, and also to understand certain natural limitations which are especially important in many high-temperature processes. The kinetic aspects of interest here comprise mainly (1) the flow of gases through the furnace system, (2) the flow of heat in the system, and (3) the mechanisms and rate factors in the various chemical reactions. A really adequate discussion of the first two subjects would require at least three or four times the space available here; it has been tried, therefore, in this and the next chapter to outline but a few fundamentals necessary to an intelligent approach and to indicate some of the conditions of heat and gas flow more or less peculiar to the open hearth, since several good general discussions on these subjects may be found in the literature.(1) For the designer of open-hearth furnaces, the principles of gas flow are of paramount importance.(2,3,4,5) They are also important to the operation of the process, however, at least to the extent of a general qualitative picture of the movement of gases in the system, which is all that is attempted here.

Jan 1, 1944

By N. F. Schulz, H. A. Lex

Representative samples of typical manganiferous iron ores from the Cuyuna Range, Minn., were reduced to the metallic iron state at temperatures just short of fusion with an excess of coke in the manner prescribed by the R-N Direct Reduction Process. The magnetic separation characteristics of the reduced ores were determined at several grinds by means of the Davis magnetic tube concentrator. The efficiency of metallic iron concentration by magnetic separation was a direct function of the degree of metallization of the ore sample and of the degree of liberation at-tained in grinding. Some improvement of liberation characteristics was observed if a small amount of sodium chloride was present in the ore during reduction. Despite the extremely fine-grained structure of the crude ores, iron concentrates containing more than 90% Fe at iron unit recoveries of 90% or more were obtained from well-metallized samples of three of the four ores tested. The rejection of manganese to the tailings corresponding to such separations varied from 80% to 95%. The manganiferous iron ores of the Cuyuna Range in Minnesota constitute a major potential source of manganese in the United States provided that a technically and economically feasible process can be devised for its recovery. The iron and manganese of these ores occur chiefly as oxides or carbonates in the form of very small, irregular, discrete grains embedded in a matrix of quartz or other siliceous gangue. The present investigation was undertaken as a sequel to an earlier one conducted jointly by the U.S. Bureau of Mines and the R-N Corp. Those results indicated that the R-N Direct Reduction Process might be a means for recovering both a metallic iron concentrate and a marketable manganese by-product from Cuyuna manganiferous iron ores.' The R-N Process is one of many proposed schemes for the treatment of crude iron ores involving the di- rect reduction of the iron content to metallic iron followed by physical extraction of the iron. In general, it consists of the following stepsz2 1) Iron oxide in crushed natural ores or iron concentrates is about 95% reduced to metallic iron at elevated temperatures but without fusion in a rotary kiln in the presence of a solid carbonaceous fuel (usually coke), limestone, and combustible gases. 2) The kiln product, consisting of metallized ore, excess coke, lime, and coke ash is cooled. The excess coke is recovered and recycled to the kiln feed. 3) The metallized ore is ground for liberation and magnetically separated to yield a metallic iron concentrate. 4) The metallic iron concentrate is agglomerated by a briquetting process. The reduction kiln temperatures must be high enough for the desirable chemical reactions to proceed at practical rates without causing fusion of any of the ore constituents. The time of exposure of the ore to the reducing conditions must be ample for 90% to 95% metallization of the iron oxides present. If more than 95% of the iron is metallized, however, difficulties may arise in the briquetting step, presumably because of accompanying higher carbon content of the metallic iron. Although not always necessary, powdered limestone or dolomite may be added at some time during reduction to aid in eliminating sulfur and phosphorus from the final product.3,4 Other additives, notably sodium chloride, when present during reduction, result in improved liberation characteristics of the metallic iron from certain reduced ores.'v6 Under the reducing conditions normally employed, P(co + H2)= 1 atmosphere, and 1830' to 2150°F (1000° to 1170°C), the R-N Process is claimed to be adaptable to a wide variety of low, medium, and high grade iron and manganiferous iron ores. The manganese oxides and carbonates are reduced mostly to nonmagnetic MnO which is rejected to the nonmagnetic tailings. Manganese-bearing pyroxenes of the original ore, however, may be rejected poorly, if at all, apparently because these minerals occur within the iron lattice or are entrapped in the metal particles.7 The investigation was limited to studies of the Cuyuna ores listed in Table I, which were reduced to the metallic iron state under various conditions

Jan 1, 1969

By T. B. Gyles

Zinc is made by the National Smelting Co. and its associates by both the horizontal retort process and the vertical retort process developed by the New Jersey Zinc Co. This paper deals only with the horizontal retort practice at Avonmouth. That the horizontal retort process does survive in all countries in some form or other is due to at least partial success in overcoming some of the inherent difficulties of the process. The horizontal retort furnaces ran into considerable difficulties when the product of the selective flotation of mixed lead and zinc ores became the normal material for treatment. It is necessary, therefore, to make some reference in connection with the process to the preliminary treatment of the ore prior to distillation.. Therefore we include some small reference to this aspect in our description. Furnace Design and Structure Of the types of furnaces in operation at the company's various works, those at Avonmouth are perhaps more typical of the trend to utilize large units, with a subsequent saving in costs, such as heating and supervision.

Jan 1, 1937

Phase II of President Nixon's economic game plan will incorporate many top flight metals mining companies. The large corporations must receive approval from the Cost of Living Council before increasing prices and or wages. The theory here is that, with large companies complying with advance approval, smaller firms will be examined more closely by government, and thus will be forced also to comply. Rep. Paul McCloskey (R.-Calif.) called for a moratorium on strip mining for "the few years involved before we adopt a national energy policy and a national land use policy." McCloskey, who is a cosponsor of Congressional legislation that would outlaw strip mining, told a hearing that a "moratorium can scarcely hurt us until national energy and land use policies are adopted."

Jan 1, 1971

By Charles Fettke

IN THE present day manufacture of glass nearly pure quartz sands are used almost exclusively as the source of the silica, which is the major constituent of all common varieties of glass. Ordinary soda-lime, such as bottle, common tableware, plate, and window glasses, contain from 65 to 75 per cent. of silica. OCCURRENCE Glass sands occur in nature either in the form of loose, unconsolidated sediments or in deposits in which the individual grains have been more or less thoroughly bound together by some cementing agent so as to form sandstones. While deposits of sand and sandstones occur both widely and abundantly distributed, deposits that are sufficiently free from other constituents than quartz grains, so that they can be employed in the manufacture of the better grades of glass, are, comparatively speaking, of rare occurrence. The major portion of the glass sand produced in the United States comes from sandstones. In order to be suitable for glass sand, they should be rather friable. The rock should break down readily along the cementing material between the grains and should not break across the grains rather than along the bond. Some of the sandstones used are so friable that only light shots of slow-burning dynamite are necessary to disintegrate them sufficiently for hydraulic mining, while others have to be passed through crushers in order to disintegrate the rock into its individual grains.

Jan 2, 1926