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J. T. LITTLETON, JR., ? Corning, N. Y. (written discussion?).-This. discussion will add little that has not been brought out but will show how the problems encountered in the Corning Glass Works were overcome. The chief points of consideration in any equipment are, first, the work the equipment is called upon to do; second, the installation; and, third, the man who will use it. These three points should determine the type of apparatus adopted. If only rough measurements, merely a little better than the eye, are desired, the cost of the instruments should be considered; but if accurate temperature control is necessary, the cost of the equipment deserves only small consideration. There is no question that the real problem for any factory is the installation, making sure that the elements really give the temperatures desired; also, the instruments must be so designed that any man can use them.

Jan 12, 1919

By J. A. Botin, K. H. Singh

INTRODUCTION The Alfredo underground mine is one of the three mining operations of Rio Tinto Minera, S.A., all near the community of Rio Tinto in Huelva province of southwest Spain. The other two operations are Corta Atalaya open pit (Pyrite ore) and Cerro Colorado open pit (Copper ore 1. Underground mining of Alfredo Mine for pyrites started in the nineteenth century and continued without interruption until 1979 when it was discontinued due to economical reasons. In 1972, a new project was started for the mining of copper bearing ores on the footwall of the pyrite deposit. This copper ore is locally named “Cloritas” and it forms a nearly vertical and tabular shaped orebody which forms an envelope at the footwall of the San Dionisio pyrite orebody. Mining of the Cloritas commenced in 1975 using cut and fill stoping. In 1977, the original project was completely revised which led to the introduction of a bulk mining system to achieve a planned production of 3,000 tonnes of ore per day. This paper covers the economic and planning aspects of the mine and discusses the evolution of the mining method for the Cloritas orebody. A GENERAL DESCRIPTION OF THE CLORITAS OREBODY The “Masa San Dionisio” (figure 1 ) is a massive sulphide orebody located in the town of Rio Tinto, about 90 kilometres west of Sevilla, Spain. Extensive vein-type sulphide mineralization exists in the volcanic host rocks of the Masa San Dionisio. Within this area of stockwork veins, there is a higher concentration of copper in the form of chalcopyrite in a zone adjacent to and paralleling the contact with the massive sulphides. This copper envelope is locally referred to as the "Cloritas Orebody” and the ore within it is called "Cloritas”. The main zone of the Cloritas orebody, (figure 11, is tabular and nearly vertical having a length of 375-400 m east-west, a thickness of 20-50 m north-south, and a vertical extension of 500 m from the surface. In addition to this area, there is a second less important low grade area called zone 2A located to the north of the main zone below 26 Level which, in some sections, is not fully separated from the main zone. MINING METHODS Mining in Rio Tinto area can be traced back to the Phoenecians and the Romans. Modern day mining started with the demand for sulphuric acid during the last half of the nineteenth century. By 1971, more than 33 million tonnes of pyrite had been mined out of Alfredo Mine, (San Dionisio Orebody), using labor intensive drift and fill methods and also by open pit method. During the last decade, underground mining of the pyrite had become uneconomic due to lower prices and a slackening demand for pyrite, and the underground mining operations for pyrite were finally stopped in 1979. In 1971, a major change in the long range mining plans for Masa San Dionisio was established. Between 1971 and 1975, underground mining of pyrites was progressively reduced while open pit extraction was increased in

Jan 1, 1981

By Claude Ferquson

MORE men are killed and injured in the metal mines of the United States from falls of rock and ore than from any other cause. Dan Harrington, of the U. S. Bureau of Mines, recently stated that "falls of men and material continue to take about 50 per cent of the lives annually lost in our mines (coal or metal) and this kind of accident is now and has been one of the most difficult to prevent." The fact that comparatively little has recently been written on this important subject for the benefit of the metal miner is the incentive for the present paper. Little will be said that will be new, but I hope to place fresh emphasis on certain well-known' principles' and to reiterate and stress previously stated rules so that the average experienced miner, as well as his buddy who may not be so experienced,' will sit up and take notice. It is not within the scope of this paper to discuss mining methods from the standpoint of safety and the prevention of accidents from falls of rock. It is up to the mine management to select the system of mining best suited to the character of the ore deposit and its wall conditions. This is something that the miner can do little about; although in many mines the management encourages the workmen to make suggestions that will improve existing

Jan 1, 1938

By Frederick Laist

I AM APPRECIATIVE of the honor you have done me in electing me to membership in your Society. I value the contacts with men of imagination and ideals which this implies. I am grateful for the recognition of such small contributions as I may have made, or helped to make, to the vast fund of scientific and engineering knowledge. We like to think, as we grow older, that our lives have not been purely parasitical, and that through our efforts some forward step, however small, has been taken toward improving conditions under which we live and do our work. In these days of industrial depression, we hear much criticism of our "machine age." Modern engineering, mass production, the complexity of our lives, all come in for some share of blame. The farmer is said to have been spoiled by the tractor and the gang plow, the factory worker has become a slave of the assembly conveyor, the scientific worker is no longer free but has sacrificed much of his individuality to the research organization of which he is a part. We wonder whether our work as engineers has been worth while and whether our striving after more efficient ways of doing things has been a curse to mankind rather than the boon we thought we were conferring.

Jan 1, 1932

By William L. Batt

IT IS becoming increasingly evident to management that it has other obligations than merely to earn dividends for stockholders. The head of one of America's largest organizations has stated it in these words: "There rests upon them a far broader responsibility than the mere production of goods and services, or solely the interests of their stockholders. They must assume the important obligation, through proper policy, of attuning industry to a rapidly changing world, from social as well as economic standpoints." Stockholders might as well reconcile themselves, therefore, to the fact that management cannot always put their interests first in the obligation of business enterprise: and that the legitimate requirements of customers and employees have acquired a new significance which must be recognized if the business of today is to prosper.

Jan 1, 1938

By Mark J. Klein

The behavior of nitrogen in Cr-0.12 at. pct Y was studied in specimens of varying interstitial concentration and thermal history. It was found that soluble nitrogen can be introduced into this alloy by increasing the concentrations of either oxygen or nitrogen. For low nitrogen concentrations the nitrogen in solution is low relative to that in unalloyed chromium. However, the nitrogen in solution increases with increasing nitrogen concentration, approaching that in unalloyed chromium. When the alloy is supersaturated with nitrogen, the nitrogen precipitates readily from solution as a chromium nitride. The stress -induced relaxation of nitrogen is influenced by internal oxidation or internal nitrification of this alloy. THE addition of small concentrations of reactive elements such as yttrium have been found to enhance the low-temperature ductility of chromium.&apos; However, the mechanism by which the ductility is increased is not known. It has been suggested that this effect is caused by a drastic reduction in the concentration of nitrogen retained in solution and therefore a decrease in the number of dislocations locked by nitrogen, a factor that has been associated with an increase in ductility.1,2 However, a change in the type of interstitial precipitate induced by yttrium could also contribute to enhanced ductility of the alloy, since chromium nitride precipitates appear to be embrittling.&apos; In this regard, it has been shown that yttrium scavenges nitrogen in chromium to form YN,4 thus reducing the embrittling chromium nitride phase. However, the change in nitrogen solubility induced by yttrium and the partition of nitrogen between chromium and yttrium nitrides are not known. The object of this investigation is to study the effect of yttrium on the behavior of nitrogen in chromium to obtain information relevant to the mechanism by which scavengers enhance the ductility of chromium. EXPERIMENTAL PROCEDURES The experimental procedures used in this investigation have been described in detail elsewhere.5,6 Wires of Cr-0.12 at. pct Y, 15 cm in length and 1 mm in diam, were drawn from rods 0.6 cm in diam supplied by the General Electric Co. The grain size of the wires after recrystallization at 1150°C was somewhat nonuniform, varying from 0.006 to 0.06 mm in diam. The interstitial analysis for the wires in ppm by weight was about 160 0, 80 N, 12 C, and <2 H. Heat treatments were carried out after encapsulation of the specimens in quartz tubes containing argon. Changes in interstitial concentrations, or interstitial "loading" as it is termed in this study, were generally accomplished by annealing in oxygen, ammonia or methane at 1150°C. The internal friction was measured using a conventional torsional pendulum enclosed in an evacuated chamber. Electrical-resistivity measurements were made at liquid-nitrogen temperature.

Jan 1, 1967

By J. D. Grozier, W. W. Mullins, H. W. Paxton

The morphology of the nucleation and growth of austenite into high-purity iron in NH3-H2, gas mixtzires has been studied. The growth rate of an austenitic rim (planar interface) from scratched surfaces of- polycrystalline iron specimens was determined as a function of temperature and percent NH3 and found to he in reasonahle agreement with growth-rate calculations based on a model which assumes the diffusion of nitrogen to he the rate-controlling step. Under certain conditions, austenite pew as platelets; growth rates of these along the surface of single crystals were found to he dependent on surface preparation, orientation, THE development of microstructures can conveniently be thought of in terms of nucleation and growth. The complex topic of nucleation in solid-solid transformations will not be discussed at length, although a few qualitative experiments were performed. Growth is determined by the mobility of the various possible interfaces under the available driving forces in a particular situation. In homophase transformations, it has been clearly demonstrated that the mobility is very sensitive to small amounts of impurities, to the kind of impurity, and to the orientation relations across the boundary.&apos; A degree of quantitative knowledge has temperature and percent NH3. On electropolished surfaces with a (110) pole, the maximum growth rate of platelets was determined and found to be in agreement within a factor of 2 to 3 with theoretical calculations of the edgewise growth rate of a platelet. The calculations are based on a model which assumes that the diffusion of nitrogen in the ferrite in front of the moving curved attstenitic interface at the tip of the platelet is the rate-controlling step. The growth direction on the surface of the single crystal and resztlting habit plane of the platelets were determined and found not to he unique but to vary systematically with the pole of the surface. been obtained. In the case of heterophase transformations, which are significantly more complicated to treat, a comparison of theoretical and experimental studies often shows rather poor agreement.&apos;-&apos; The main purpose of the experiments discussed below was to obtain additional quantitative data on crystallographic effects on boundary mobility in a system which was otherwise as simple as possible, viz. the growth of iron-nitrogen austenite into fer-rite. In the course of the experiments, it became necessary to re-examine the theory for the growth of Widmanstatten plates, especially the influence of anisotropic interfacial free energy. Some other minor experiments in the Fe-N system were performed, and are described briefly. EXPERIMENTAL METHODS A) Material Preparation. The floating zone purified iron used for this investigation was supplied by Battelle Memorial Institute. The nominal composi-

Jan 1, 1965

By E. A. Gulbransen, W. S. Wysong, K. Andrew

INTRODUCTION THE reaction of carbon in solid solution in a metal with the surface oxide film on many metals may be inferred from thermodynamic calculations for high vacua and high temperature conditions. Holm1 has recently shown that oxide films may be removed from ferrous materials by heating in a vacuum at high temperatures and that carbon is the essential element in the reaction. Considerable work has been described in the literature on the decarburization reaction. Several general references may be noted.2,3,4 However, the nature of the mechanism involved in the decarburization is not well understood. Our interest in this reaction resulted from many attempts to degas and to reduce by pure and dry hydrogen the surface oxides 0n strips of various types of chrome-nickel alloys. Some of the early experiments on the behavior of 13 pct chrome-iron in vacua of the order of 5 X 106 mm and at a temperature of 600°C have been reported.5 These experiments showed a slow reaction with the residual oxygen or water vapor in the system and no reaction with hydrogen. This is in accord with thermodynamic data which would lead to the prediction that it is extremely difficult to maintain a hydrogen atmosphere at 600°C pure enough to reduce Cr203 formed on the surface. The crystal structure of the superficial oxide film formed on 13 pct chrome iron and Nichrome V has been investigated in the thin film range by Gulbransen, Phelps and Hickman,6 and shown to be Cr203. It was surprising to us to note that when a specimen of Nichrome V containing approximately 80 pct nickel and 20 pct chromium was heated to 850°C in a high vacuum, the specimen&apos; lost weight. The rate of weight loss was very temperature sensitive. A study of this reaction in vacua and in a hydrogen atmosphere is the subject of this communication. TYPE REACTIONS Let us consider the various reactions which may occur when a metal is heated in vacua, in a hydrogen atmosphere, or in an oxygen atmosphere. The number and kind of reactions will depend upon the chemical nature, of the metal, its alloying constituents and the location of the alloying constituents. The metals used in this study are chrome-nickel alloys of the heater type. They consist essentially of chromium, nickel and iron, small amounts of carbon, silicon and manganese and traces of zirconium, calcium, aluminum and magnesium. The trace elements are added to improve the lifetime and other characteristics of the alloy when used as a heater. Seven of the more important reactions with which we are going to be concerned here are as follows: [I. Metal • (gas) ;--* metal + gas - degassing of the metal 2. xM(s) + y ½ 02(g) tom- M.0„ (s) – oxidation]

Jan 1, 1948

By H. S. Rankin, E. C. Houston

OLIVINE is considered a valuable potential source of metallic magnesium in the chloride electrolytic process. Treatment of olivine with hydrochloric acid can be carried out under conditions that prevent the formation of gelatinous silicic acid, which would inhibit the reaction by forming a covering around the ore particles. It is our hypothesis that the formation of gelatinous silicic acid is avoided by the dehydrating action of the magnesium chloride, which takes up water to form a series of hydrates and leaves the silicic acid in granular condition. Leaching serves to separate the magnesium chloride from the silicic acid and unattacked ore, which can be treated with fresh acid in successive steps until extraction is essentially complete. The leach solution can be purified by the addition of caustic magnesia and the precipitated impurities removed by decantation or filtration. The resulting magnesium chloride contains: Fe, less than 0.001 per cent; Mn, 0.012 per cent; Ni, none. Chlorination[f] of olivine has two major defects: (1) a large part of the chlorine goes to form silicon and iron chlorides, (2) the anhydrous magnesium chloride is held by absorption in the finely divided silica. SUPPLY It is well known that olivine, a silicate of magnesium and iron, is present in large amounts in several localities in the United States. The largest deposits occur in the southeast and on the Pacific Coast.1 The southeastern deposits were surveyed by Lewis2 in 1896 and by Hunter3 in the period 1933-1940. It is estimated that high-grade olivine, conveniently located with regard to transportation and power, is present in excess of 230 million tons above local drainage level in western North Carolina and north Georgia. PREVIOUS TECHNICAL WORK In the past few years, olivine has attracted considerable attention in the refractory field. In the chemical processing industry, however, it has long been thought axiomatic that the cost of processing silicates is an economic barrier to their utilization, especially where more reactive minerals, such as carbonates, oxides or salts, are available. This attitude is not entirely justified in connection with olivine. Unlike most silicates, olivine is readily attacked by acids, chlorine and other reagents without resorting to fusion to break down the silicate structure. Olivine has been suggested as a raw material for making epsom salt by roasting with pyrites.4 Other processes include acid treatment5 and digestion with calcium chloride.6 Recently a small plant was built near Webster, N. C., for making epsom salt from olivine by treatment with sulphuric acid. This plant is now in commercial operation, producing approximately two tons per day. Olivine is also receiving attention from the fertilizer industry as an inexpensive source of soluble magnesium.

Jan 1, 1942

By W. A. Backofen, D. Lee, F. S. Jabara

THE empirical character of plasticity analysis insures a continuing need for measurements of the yield surfaces of anisotropic materials. Recently, Wheeler and Ireland (W-I) proposed that an octahedral yield locus could be constructed on the basis of six Knoop hardness indentations. Such simplicity would have obvious appeal, if it led to consistently dependable results. In other recent work, a much more straightforward (and more tedious) method of measurement was used to establish all quadrants of the plane-stress yield loci for two substantially anisotropic titanium alloys.2,3 The same materials have since been reex-amined by the W-I method with results being reported here. A full description of the stress state under a Knoop indentor would be complex. In principle, however, this can be avoided in relating the hardness number to a plane-stress yield locus, by the expedient of superimposing the appropriate hydrostatic component on that state of stress. Six possible orientations of in-dentor on orthogonal (symmetry) planes, along (principal) coordinate directions, are illustrated in Fig. 1(0). Pictured in Fig. l(b) are normal-stress components nominally associated with indentation n: o2(H), directly proportional to the Khn in this case, together with By overlaying a hydrostatic tension, ah, that in general is equal to the stress state around the indentation is reduced to one of plane stress in the x-y plane for which the stress ratio is a The key step in the W-I yield-locus construction is to represent the Khn for any indentor orientation as a vector quantity on the octahedral plane. In the plotting, the vector is given as deviatoric stress components along the principal axes in the ratio , where represents the direction of the minor (width) diagonal and 1 that of the major (length) diagonal. There is no attempt by W-I to justify the 7/1, although it might be supposed that the value originates in the usual ratio of major to minor diagonals in a Knoop indentation of about 7/1. If that were its origin, the link to the deviatoric stress ratio would presumably be made by first taking 7/1 and then turning to the Levy-Mises equation for isotropic material: Interpreted in this way, the W-1 approach seems arbitrary and even contradictory. Yet it would still be favored by two circumstances: the deformation under a Knoop indentor approaches plane strain: when dcw/del =a; and the shape of the locus where plane strain is represented is not overly sensitive either to the exact value of dc,/dcl or to the degree of anisotropy, within a rather wide range of both variables. The second point is illustrated below, after a few additional comments on applying hardness

Jan 1, 1968

By W. E. Hall

The Darwin mining district of California, 160 miles north of Los Angeles, has yielded an estimated $45 million in lead, silver, zinc, and copper since 1875. The deposits are in silicated limestone of Penn-sylvanian and Permian age close to a stock of horn-blende-biotite-quartz monzonite. Steep left-lateral strike-slip faults that strike N 50o 70o E served as feeder channels for the ore solutions, and minor folds, favorable beds, and faults close to the feeder channels localized the orebodies. The orebodies are irregular, steep, pipe-like replacements that cut across bedding, bedding replacements, and fissure fillings in a calc-silicate country rock consisting mainly of wollastonite, grossularite-andradite garnet, idocrase, and diop-side. Near surface the ore consists of a soft, crumbly mass of cerussite, hemimorphite, jarosite, limonite, and some secondary copper minerals. The primary ore consists of galena, sphalerite, pyrite, pyrrhotite, and chalcopyrite with smaller amounts of andorite, matildite, scheelite, tetrahedrite, and a high silver-lead-bismuth-selenium-bearing galena. Preliminary X-ray fluorescence study of the primary ore has indicated unusually high concentrations of bismuth, selenium, and silver in galena from certain parts of the mine. One phase of this study concerns the distribution of these elements. Twenty-two samples of galena and thirty of sphal- erite have been purified and analyzed or are being analyzed. The selenium in 21 samples of galena ranges from 0.0045 to 2.11 pct; four contain more than 1 pct. These four samples were collected from the Essex orebody, where most of the selenium is concentrated. Three are from high-grade, near-surface ore, and one is from the 700 level. Four of the seven analyzed galena samples from the Thompson workings immediately north of the Essex orebody contain 0.29 to 0.74 pct Se; the others show less than 0.05 pct. Galena from the Defiance workings about 2000 ft south of the Essex has less than 0.03 pct Se. The selenium-bearing galena also contains concentrations of bismuth and silver. Preliminary spectographic analyses indicate as much as 3 pct Bi and more than 1 pct Ag in galena with high selenium content. Antimony is the only other minor element present in galena in amounts greater than 0.02 pct; most galena contains between 0.1 and 0.2 pct and the maximum is 0.72 pct. A second phase of the study is an attempt to determine the temperature range of the formation of the ore. The iron content of sphalerite deposited in equilibrium with pyrrhotite is being used as a geologic thermometer as it is a function of the temperature of deposition of the ore.&apos; Preliminary results indicate temperature range from 430°C in replacement orebodies in the Defiance workings to 180°C in shallow fissure fillings.

Jan 1, 1960

The pressure of the gas in equilibrium with sphalerite has been determined in the temperature range of 680&apos; to 825°C, using the Knudsen orifice method. A comparison of these experimental pressures with those calculated from thermal data and from other equilibrium measurements shows that the vapor above sphalerite is predominantly dissociated ZnS. Equations have been given for correctly calculating dissociation pressures using the Knudsen orifice method. It has been shown that the experimentally determined pressure is the same, whether the zinc sulphide is sphalerite or not, or a mixture of wurtzite and sphalerite. CONFLICTING points of view appear in the literature on the constitution of the vapor in equilibrium with solid zinc sulphide in the vicinity of 800°C. By comparing the dissociation pressure calculated from thermodynamic data and the vapor-pressure determination of ZnS by Veselovski,1 Lumsden2 has concluded that the vapor consists largely of dissociated ZnS. Sen Gupta,&apos; however, concludes from his spectroscopic determinations that the vapor is largely ZnS molecules. In view of the fact that the thermodynamically calculated&apos; dissociation pressure is higher than that experimentally measured by Veselovski, it seemed in order to repeat Veselovski&apos;s measurements. Experimental Procedure The method used for the determination of the pressures in this papel- is the Knudsen effusion cell. The apparatus and procedure were described in a previous paper- from this laboratory on the determination of the vapor pressure of silver. The only difference is that the Knudsen cell in this work is made from platinum and there is no external cover around the cell. The cell is an ordinary platinum crucible of 2.2 cm top diameter with a capsule cover. It was thought that platinum might stand up at these temperatures to the solid and gaseous ZnS, since it was found that the weight of the platinum cell itself did not change appreciably on heating ZnS in it at the working temperatures. To insure that reaction of the zinc sulphide with the cell was not giving&apos; a false value, a stabilized zirconia cell was employed for check runs. Fig. 1 shows the comparison, which is satisfactory. Veselovski previously had measured the vapor pressure of ZnS using a silica Knudsen effusion cell. On repeating his experiment in this laboratory, it was found that ZnS at-tacked the silica cell, giving it a marked frosty appearance. This led to the belief that Veselovski&apos;s result:; may be in error. Also, he was operating at pressures above the range ordinarily considered safe for the Knudsen method. The effusion rate was measured by weighing the cell before and after each run. The weight loss during heating to temperature and cooling down was measured and subtracted from the weight loss during the actual run. The zinc sulphide used in this investigation was from two sources: Fisher cp grade, and a sample of pure sphalerite supplied by Mr. E. A. Anderson of the New Jersey Zinc Co. Before and after the series of runs with Fisher ZnS, X-ray analysis showed that both wurtzite and sphalerite were present. However, the ratio of sphalerite to wurtzite increased. All measurements were made below the transition temperature which has been reported" to be 1020°C. The data obtained in this investigation are tabulated in Table I. The pressure was calculated by the usual Knudsen formula" on the assumption that ZnS molecules were effusing. From these data, using pure sphalerite in the platinum Knudsen cell, the vapor pressure of ZnS, in mm of Hg, as a function of temperature is given by the solid line in Fig. 1. The best straight line, as determined by the method of least squares, is given by 14405 logpzns =-14405/T +11.032. A comparison of these results with Veselovski&apos;s shows that his results are about 50 pct lower. Discussion The vapor in equilibrium with solid zinc sulphide in the temperature range of this study will consist of Zn, S2, and ZnS mol, since other species of zinc and sulphur&apos; are relatively unstable. The question to be settled is whether or not ZnS is largely dissociated. The derivation8 which follows gives the method of calculating the pressure of zinc and sulphur over solid ZnS, assuming complete dissociation, from Knudsen cell data. The free energy of the reaction 2 ZnS(solid) ? 2 Zn(gas) + S2(gas) is given by ?F?° = -RT In K = —RT In p12p2 where p1 is the zinc pressure and p is the sulphur pressure. If dissociation occurs in a closed system,

Jan 1, 1955

By T. H. Alden, H. W. Schadler

The strain rate dependence of the flow stress of the eutectoid Zn-Al alloy has been determined as a function of mechanical processing, microstructure, and temperature. The best superplastic properties result from the ultrafine, equiaxed structure produced by solution treatment and isothermal transformation at 0°C. Lamellar structures produced by isothermal transformation and coarse equiaxed structures produced by annealing also exhibit strain rate sensitivity in excess of 0.5, but at higher stresses and lower strain rates than the finest structure. Solution treatment and isothermal transformation eliminate the effect of prior processing history. Small composition variations in the binary alloy do not influence the mechanical properties. Below the eutectoid transformation temperature (.275C) increasing temperature lowers the flow stress at all strain rates. The data do not favor any of the present proposals for the mechanism of superplastic flow. ALLOYS of zinc and aluminum, near the eutectoid composition, have been investigated for: 1) the flow stress-strain rate and elongation behavior,1, 2) the transformation kinetics,3 and 3) structure,3"5 but the structure sensitivity of the mechanical properties is poorly understood. Using a near eutectoid alloy water-quenched from 380°C, Backofen et aL2 estab- high and increases with increasing strain rate. They found a correlation between strain rate sensitivity and tensile elongation as expected from the increased resistance to necking that a high strain rate sensitivity provides.296 The large elongation at high strain rates is attractive for metal forming. Since most other superplastic alloys7-l3 do not show high strain rate sensitivity at such a high strain rate (for the exception see Ref. 12) there is the possibility of a unique deformation mechanism for this alloy. The sensitivity of the mechanical properties of the eutectoid alloy to thermal history1 suggests a structure sensitivity that has not been demonstrated. Gar-wood and Hopkins3 identified a lamellar product for material transformed between 200" and 260°C. The size of the lamellae decreased with decreasing temperature. They also demonstrated that an unresolved transformation product formed below 200°C. A granular two-phase material was resolved for specimens quenched to below 150°C by Mitbauer and sauerwald4 who observed coarsening of the structure after annealing. The role of grain boundaries in superplastic deformation is suggested by the strong effect of grain refinement in encouraging this phenomenon at high strain rateS7-11, 13 and is emphasized in several proposals about rnechanism7, 8, 12 and in a theory14 of high-temperature deformation. Alden8 showed metallographic evidence that grain boundary sliding is occurring extensively at strain rates where m is large but less at high strain rates where normal plasticity is observed. Holt and Backofen10 have shown that sliding also oc-

Jan 1, 1969

By N. A. Stockett

Southeast Missouri is the largest and oldest lead-producing district in the United States. For the year 1941, the statistical picture of pig-lead production, stated in short tons (partly estimated by the Engineering and Mining Journal) is as follows. Tons World production................. 2,000,000 United States Production .........- 460,000 Southeast Missouri production..... 142,000 The consumption of primary lead in the United States in 1941 was approximately 900,000 tons, or almost double the country&apos;s production. The largest previous year&apos;s in in the United States was 718,000 tons, in 1926. The largest quantities of lead are used for cable sheathing, storage batteries and white lead. During 1941 tetraethyl lead for auto and aviation gasoline consumed 50,000 tons of lead. The entire lead production of Southeast Missouri is now mined by the St. Joseph Lead Co., whose dominant position as the largest producer in the United States of lead directly from ores is best shown by the fact that in 1941 it produced approximately 31 per cent of the lead production of the United States from its mines in southeast Missouri, where 22,000 tons of ore, averaging over 3.00 per cent lead, is mined per working day. It is known that lead was mined at Mine La Motte, Madison County, Missouri, by Renault in 1723. Other white men and Indians probably did some mining prior to that time. Since 1865, the recorded production to Jan. I, 1942, shows that the St. Joseph Lead Co. and the various other companies that have operated in St. Francois County mined lead ore, which, after milling and smelting losses produced 5,980,000 short tons of pig lead. • About 95 per cent of the present lead production of Southeast Missouri is mined in St. Francois County. The northern part of this area is 60 miles south of st. Louis. The remainder of the lead is obtained at Mine La Motte, about 25 miles southeast from the center of the producing area in st.Francois county, Prospecting In this district, most of the ore is discovered by surface and underground diamond drills and by prospect drilling underground with rock drills. Each 2-ft. length of the cuttings from these Jack-hamer prospect holes is assayed for lead. These holes are marked and the records are entered on maps. It has been found that close drilling—100-ft. centers of holes, and sometimes less—is necessary in order to locate most of the smaller commercial ore bodies, many of which previously had been missed by drilling the areas with holes spaced 200-ft. centers or more. To date, geophysical and other methods of prospecting, apart from diamond and Mining Practices of the St. Joseph Lead Company in Southeast Missouri

Jan 1, 1943

By N. A. Stockett

Southeast Missouri is the largest and oldest lead-producing district in the United States. For the year 1941, the statistical picture of pig-lead production, stated in short tons (partly estimated by the Engineering and Mining Journal) is as follows. Tons World production................. 2,000,000 United States Production .........- 460,000 Southeast Missouri production..... 142,000 The consumption of primary lead in the United States in 1941 was approximately 900,000 tons, or almost double the country&apos;s production. The largest previous year&apos;s in in the United States was 718,000 tons, in 1926. The largest quantities of lead are used for cable sheathing, storage batteries and white lead. During 1941 tetraethyl lead for auto and aviation gasoline consumed 50,000 tons of lead. The entire lead production of Southeast Missouri is now mined by the St. Joseph Lead Co., whose dominant position as the largest producer in the United States of lead directly from ores is best shown by the fact that in 1941 it produced approximately 31 per cent of the lead production of the United States from its mines in southeast Missouri, where 22,000 tons of ore, averaging over 3.00 per cent lead, is mined per working day. It is known that lead was mined at Mine La Motte, Madison County, Missouri, by Renault in 1723. Other white men and Indians probably did some mining prior to that time. Since 1865, the recorded production to Jan. I, 1942, shows that the St. Joseph Lead Co. and the various other companies that have operated in St. Francois County mined lead ore, which, after milling and smelting losses produced 5,980,000 short tons of pig lead. • About 95 per cent of the present lead production of Southeast Missouri is mined in St. Francois County. The northern part of this area is 60 miles south of st. Louis. The remainder of the lead is obtained at Mine La Motte, about 25 miles southeast from the center of the producing area in st.Francois county, Prospecting In this district, most of the ore is discovered by surface and underground diamond drills and by prospect drilling underground with rock drills. Each 2-ft. length of the cuttings from these Jack-hamer prospect holes is assayed for lead. These holes are marked and the records are entered on maps. It has been found that close drilling—100-ft. centers of holes, and sometimes less—is necessary in order to locate most of the smaller commercial ore bodies, many of which previously had been missed by drilling the areas with holes spaced 200-ft. centers or more. To date, geophysical and other methods of prospecting, apart from diamond and Mining Practices of the St. Joseph Lead Company in Southeast Missouri

Jan 1, 1943

By R. D. Lee

A simplification of the method of Hurst and McCarty for conducting potentiometric model studies by the single probe method is presented along with experimentally determined invasion patterns for certain idealized flow problems. The analytical solution for one class of these problems is given. Finally, a general description is given of a newly developed instrument which permits direct mapping of flow lines and determination of transit times in potentiometric-model studies. Introduction The object of this paper is to present: I. A simplification of the method of Hurst and McCarty for conducting poten-tiometric-model studies of oil and gas reservoirs by the single probe method. 2. Results of a series of studies of certain idealized flow problems and the general conclusions to be drawn therefrom. 3. A description of a new instrument, the Chronocartograph, which greatly reduces the labor and time required for conducting potentiometric-model studies. Certain general conclusions may be drawn as results of the investigation of the idealized flow problems. They are: I. Injection and extraction areas should be separated by as great a distance as conditions permit since, in general, the recovery prior to first breakthrough tends to vary as the square of this distance. 2. Little advantage is to be gained by use of more than eight injection wells or groups of injection wells for the case of circular productive limits. 3. Elongated shapes of productive limits are best exploited by injection on the extended major axis only, with a line of extraction wells lying on the major axis. 4. The use of peripheral injection wells for elongated shapes is permissible, if necessary, but requires extension of the line of extraction wells. The exploitation of an oil or gas field is effected either by the expansion of the gas and oil, or by their displacement by another fluid. Both methods may be used simultaneously. When the displacement of the oil or gas is the controlling factor there arises the problem of mapping the progress of the boundary between the fluid in place and the displacing fluid. This problem is of particular interest in the operation of a cycling project in a gas-condensate field, where the wet gas is produced from one or more wells, commonly called "extraction wells.&apos;&apos; This wet gas is taken into a processing plant where the condensate is removed. The remaining "dry" gas is injected back into the field through one or more wells, called "injection wells," both to conserve the gas for future use and also to maintain the pressure in the field. In an operation of this type it is essential to anticipate the manner in which the dry gas will spread through the field, because the ultimate recovery of the wet gas depends

Jan 1, 1948

By R. D. Lee

A simplification of the method of Hurst and McCarty for conducting potentiometric model studies by the single probe method is presented along with experimentally determined invasion patterns for certain idealized flow problems. The analytical solution for one class of these problems is given. Finally, a general description is given of a newly developed instrument which permits direct mapping of flow lines and determination of transit times in potentiometric-model studies. Introduction The object of this paper is to present: I. A simplification of the method of Hurst and McCarty for conducting poten-tiometric-model studies of oil and gas reservoirs by the single probe method. 2. Results of a series of studies of certain idealized flow problems and the general conclusions to be drawn therefrom. 3. A description of a new instrument, the Chronocartograph, which greatly reduces the labor and time required for conducting potentiometric-model studies. Certain general conclusions may be drawn as results of the investigation of the idealized flow problems. They are: I. Injection and extraction areas should be separated by as great a distance as conditions permit since, in general, the recovery prior to first breakthrough tends to vary as the square of this distance. 2. Little advantage is to be gained by use of more than eight injection wells or groups of injection wells for the case of circular productive limits. 3. Elongated shapes of productive limits are best exploited by injection on the extended major axis only, with a line of extraction wells lying on the major axis. 4. The use of peripheral injection wells for elongated shapes is permissible, if necessary, but requires extension of the line of extraction wells. The exploitation of an oil or gas field is effected either by the expansion of the gas and oil, or by their displacement by another fluid. Both methods may be used simultaneously. When the displacement of the oil or gas is the controlling factor there arises the problem of mapping the progress of the boundary between the fluid in place and the displacing fluid. This problem is of particular interest in the operation of a cycling project in a gas-condensate field, where the wet gas is produced from one or more wells, commonly called "extraction wells.&apos;&apos; This wet gas is taken into a processing plant where the condensate is removed. The remaining "dry" gas is injected back into the field through one or more wells, called "injection wells," both to conserve the gas for future use and also to maintain the pressure in the field. In an operation of this type it is essential to anticipate the manner in which the dry gas will spread through the field, because the ultimate recovery of the wet gas depends

Jan 1, 1948

By R. W. Gurry

IN the course of a series of measurements of the rate of diffusion of carbon in austenite at about 960°C. (1760°F.) and 1110°C. (2030°F.), it became necessary to determine carbon concentration when austenite is saturated with graphite, because of indications that the hitherto accepted value of the solubility of graphite in this temperature range is too low. Specimens of carbonyl iron were saturated at temperature in a hydrogen-toluene atmosphere which was in equilibrium with graphite. The carbon content of the steel was measured either by combustion or by the loss of weight after substantially complete decarburization in an atmosphere of hydrogen saturated at room temperature with water vapor. The absence of carbide or graphite as a phase at temperature was demonstrated by microscopic examination of saturated specimens that had been drastically quenched. The mean result of concordant measurements is that gamma iron saturated with respect to graphite contains 1.39 per cent carbon at 957°C. (1755°F.) and 1.89 per cent at 1110°C. (2030°°F.). These two values, plotted along with what appears from the literature to be the best value (0.69 per cent) at the iron-graphite eutectoid temperature (738°C. or 1360°F.), yield a curve that is almost linear, and which, continued upward through a short interval, leads to a limiting solubility of 1.98 per cent at the iron-graphite eutectic temperature1135°C. (2095°F.) instead of the commonly accepted value of about 1.7 per cent. EXPERIMENTAL PROCEDURE The samples of carbonyl iron, with the exception of those for microscopic examination, were cylinders 3.8 cm. long, 0.475 cm. in diameter. They were placed in a graphite holder and suspended in a vertical furnace, the temperature of which was controlled precisely by means of the resistance of the platinum winding.1 In the empty furnace the range of temperature over a distance of 4 cm, at the heat center was 9°C. (16°F.) but at a given location the temperature remained within ±0.5°C. (0.9°F.); it was measured by inserting a platinum-rhodium couple calibrated at the melting point of palladium, 1555°C. Since the presence of the sample probably improved the uniformity of temperature, it was decided to consider the average temperature of the sample to be 3°C. lower than the maximum measured in the empty furnace with the same setting of the controller. Data were obtained in the vicinity of two temperatures, 960°C. (1760°F.) and 1110°C. (2030°F.). The samples for microscopic examination, 2.2 cm. long, 0.475 cm. in diameter, were suspended individually on pure iron wire; for these no temperature correction was applied. The carburizing gas passed into the furnace was dry, oxygen-free hydrogen saturated at room temperature with

Jan 1, 1942

By B. Wilshire, W. J. Evans

W. J. Evans and 8. Wilshire SEVERAL recent investigations1-6 have shown that the strain, c, during transient and steady-state creep is well-represented by the expression: € = e0 + et(l - e-mt) + Esl [l] where Eo is the instantaneous strain on loading, ET the total transient strain, C, the steady creep rate! and m a constant relating to the rate of exhaustion of transient creep. However, it has been noted6 that deviations from this equation occur over the first 10 to 15 pct of the transient stage, when the creep rate, (. decreases more rapidly than is predicted by this equation. This rapid decrease has been attributed to a large change in work-hardening coefficient. It 1s widely accepted that steady-state creep results from a balance between the rate of strain hardcning h and the rate of recovery r (=-s(st) as: dE/dt = Es = r/h [2] Comparison of values obtained for h at the end of the initial extension and during steady creep suggests that h increases several fold during the transient stage. which has the effect of reducing the creep rate proportionally.7 To examine the dependence, on r and h, of the deformation behavior during transient and steady-state creep. a series of constant-stress creep tests was carried out at 413°C at 6000 psi using 70-30 a brass. Prelinlinary investigation showed that. with this material. the transient stage constituted a significant portion of the total creep life (-0.4tf. where tf is the time to fracture). The alloy. obtained from Metals Research Limited. was made from high-purity copper, 99.999 pct. and zinc. 99.99 pct. Heat treatment at 675°C for 4 1/2 gave a uniform grain size of 5 mm-1. Details of specimen preparation and creep testing procedures have been given previously.6 Values of h (?s/?E) were determined by measuring the instantaneous strain. ?E. which occurred on increasing the stress during creep by a small amount. ?s. Similarly. v (= -?s/ ?t) was derived from the incubation period. At, after a small decrease in stress.&apos; Several values of v and h were obtained throughout duplicate creep tests. using different stress increments in the range 300 to 800 psi. The accuracy with which Eq. [I] represents the present creep curves was established by determining the best value of the constants Es, Et, m , and 6, using a digital computer program based essentially on the graphical solution for this equation devised by Conway and Mullikan.9 About 40 strain/time readings were taken during transient and steady-state creep. Over most of the creep curve, the average difference between the measured reading and the calculated strain at the appropriate time was less than 0.0001. However.

Jan 1, 1969

By V 7. 0 / 300 dpi

LAST fall, having a number of ore samples from mine-development work carried on in spite of the "Revolution," I was forced to do my own assaying again, after a lapse of many years. This gave me an opportunity to build a furnace for crucible assaying, using wood for fuel, along lines which had been developing in my mind since the time 20 years ago, when as general factotum at a little mining camp in western Chihuahua, Mexico, I had converted a crucible charcoal furnace into one using the reverberatory principle. Wood-burning furnaces have been described in technical literature, but I believe the present application will prove helpful to those of the profession who are working in out-of-the-way places. The furnace is shown in detail in Figs. 1, 2 and 3. Remembering the trouble caused by stoking my first charcoal furnace too heavily, I fired this one with but a few sticks of wood at a time. By this method I could run out a charge of 12 crucibles in 30 to 35 min., using 50 sticks of ordinary stove wood. Later I fill up the firebox, holding about 40 sticks, get everything ready, put the crucibles into the melting chamber and "fire up." Just as soon as the fire is well started the draft door is closed and the furnace allowed to heat up slowly for 5 min. Then the draft is opened (the door to the ash-pit) and the fire allowed to roar, which it does. In 20 min. from the time the fire is lighted the fire door is opened, the fire stirred along the grates, and 5 or 6 more sticks of wood thrown in. In 25 min. from the start, the draft is closed again, the cover of the melting chamber pushed back and the charges poured. The melts will be found to be perfect, and the crucibles to pour absolutely clean, if everything has gone right, as will usually be the case. A new charge may be put in, and fired with S to 10 sticks of wood at a tine, and be ready to pour within 20 min.; but it is just as well to leave the crucibles in the melting chamber a full 2.5 min. By using 10 sticks of wood to start the fire and adding 5 sticks as often as needed, which will be as soon as the last sticks fed in are in perfect combustion, the smelting can be completed in from 30 to 35 min., using from 35 to 40 sticks of wood. I consider this to be the best method of stoking.

Jan 10, 1914