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By D. A. Thomas, E. S. Meieran

Tungsten wires were examined by transmission electron microscopy after drawing and after high-temperature annealing. Drawn wire consists of highly elongated grains called fibers, whose long axis is parallel to [110]. Each fiber is ribbon-shaped, with the wide dimension of the ribbon parallel to (001) and the narrow dimension parallel to (110). Furthermore, most fibers are bent about [I10] and twisted along their length. The fibers are divided into cells, which in some cases contain a platelet substructure lying on (110) planes. The misorien-tations of these platelets accumulate to allow the macroscopic twist of the fibers. During annealing, several competing reactions occur, starting at different temperatures and progressing at different rates. Among these processes are fiber-boz~ndary migration, polygonization, dislocation rearrangement, and possibly impurity segregation. The fiber-boundary migration accompanied by the formation of transverse boundaries during polygonization leads to an equiaxed grain structure although recrystal-lization does not occur. There is a relationship between the flow stress of the wires and their average subgrain width in the form sy = s0 + kyd-1/2 . Also, there appears to be a relatio'nship between wire ductility and the formation of transverse boundaries during annealing at about 800°C. THERE have been many investigations of the structures and properties of tungsten wires1-4 due to their commercial importance for use as lamp filaments. The structural studies have so far been limited to optical microscope and replica electron-microscope studies. due to the difficulty of .-me- paring from wires thin foils which can be examined by transmission electron microscopy. However, this difficulty has been recently overcome,5 and it is now possible to examine tungsten wires by transmission electron microscopy as well as by other techniques. In this paper, the structure of drawn tungsten wire is described, as are the changes in the structure during high-temperature annealing. Some discussion of the relationship between structures and properties is also given. EXPERIMENTAL MATERIALS AND PROCEDURES Commercial 0.030-in.-diam doped tungsten wires drawn at progressively decreasing temperatures between about 1400° and about 800°C were examined. The composition, mechanical properties, and optical microstructures are described in detail elsewhere.' All experimental materials were vacuum-annealed for 10 ot 30 min at temperatures at 100°C intervals between 700° and 2000°C. Specimens were thinned for examination in the Siemens Elmiskop I electron microscope by the method of Meieran and Thomas.5 STRUCTURE OF AS-DRAWN WIRE The optical microstructure of as-drawn tungsten wire has been described by Peck and Thomas.7 They observed that wire in longitudinal section consists of highly elongated grains called fibers whose width varies between 1 and 10 µ, while in transverse section the fibers appear to be elliptical in cross section and bent about their common [110] wire axis. They explained this unusual appearance as being due to the drawing of a bcc material with a [110] texture, and predicted that the wide and narrow planes of the fiber cross section would be parallel to (001) and (110), respectively. The fibers apparently bend about the [110] axis during drawing to maintain grain boundary continuity during drawing. Transmission electron microscopy offers a way of checking these predictions as well as providing a more detailed picture of the wire structure. Figs. 1, 2, and 3 are typical electron micrographs of

Jan 1, 1965

By Sandford S. Cole

Manganese compounds occur in many mineral forms widely distributed throughout the crust of the earth. The most important of these commercially are the oxides which are usually found as irregular masses, but in some places (notably U.S.S.R.) occur as extensive beds of varying thickness and purity. The principal sources of ore have been U.S.S.R., Ghana (the Gold Coast of Africa), India, Union of South Africa, Belgian Congo, French Morocco, Cuba, Brazil, and Mexico. New developments of ore are being conducted in Brazil, British Guiana, French Equatorial Africa, and Northern Rhodesia. The production of the United States normally meets less than 10 pct of domestic manganese consumption. Manganese ore (35 pct or more Mn) is used principally by the ferrous metallurgy industry for production of manganese metal, ferromanganese, and other manganese alloys for use in production of steel ingots and castings. Some manganese is used in the nonferrous industry as an alloying element and cleanser in aluminum alloys, aluminum bronze, constantan, manganese bronze, Monel, Everdur, nickel-chromium resistance alloys, and nickel-silver. The metallurgical uses consume about 97 pct of the total manganese ore requirements of the United States. The balance goes principally for the manufacture of dry cells and for chemicals, with limited amounts for ceramic products, plastics, welding rods and varnish. The Materials Survey on Manganese, compiled in 1952 for Materials Office National Security Resources Board by the Bureau of Mines and Geological Survey, provides an excellent review of resources, reserves, specifications, uses, mining, beneficiation, metallurgical processes and deposits, and is worth referring to for greater details. Mineralogy and Geology The more common manganese minerals with typical characteristics are listed in Table 1 in order of importance. [ ]

Jan 1, 1960

By J. Chipman, N. J. Grant, H. L. Bishop

Lime and dicalcium-silicate crucibles were equilibrated with molten iron and liquid slags containing iron oxide and small amounts of sulfur. The oxygen content of metal, iron oxide activities, and desulfurization values of the slags were determined in the temperature range 1530 to 1700°C. The influence of magnesia in the slag and the temperature dependence of the solubility of lime in liquid iron oxide and the ferric oxide content were established. The temperature contour of the liquidus surface of iron-silicate slags saturated with lime and dicalcium silicate was also established at 1600°C. THE importance of the role that slag composition plays in the refining of steel has been known for many years. Numerous studies have been made using actual plant data in order to establish the relationship between the composition of the slag and metal during the refining of a heat of liquid steel. These results rarely represent equilibrium conditions since completion of the various chemical reactions involved in steelmaking is seldom realized. In order to establish quantitatively the equilibrium conditions existing between the slag and metal, several laboratory studies have been conducted in the past 20 years to determine the reactions important in slag control. These investigations have included studies of simple liquid basic and acid slags as well as more complex slag systems which approach those commonly found during the refining of a heat of steel. Since most of the previous studies of simple basic iron-oxide slags equilibriated with molten iron were made in magnesia crucibles, it was not possible to establish the distribution of sulfur and oxygen between molten iron and slags consisting only of the three essential components, lime, silica, and iron oxide. This investigation was undertaken to establish the equilibrium conditions for simple lime-iron oxide and lime-silica-iron oxide slags. Accordingly, it was expedient to prepare crucibles both of lime and dicalcium silicate to establish the equilibrium conditions between molten iron and iron-oxide slags saturated with the refractory materials and free from other components. The only other studies of the equilibrium between molten iron and lime-saturated slags are those of Fischer and vom Ende, 1, 2 in which the solubility of oxygen was determined in an air atmosphere. The

Jan 1, 1959

By David R. Poirier

Activity data of carbon as a function of both temperature and composition throughout the stable austenite range is correlated by mearts of an equation derived from a quasi-chemical model. The carbon activity data of austmite for temperatures between 800° and 1200°C are utilized in conjunction with the activity of carbon calculated for the y solidus using the activity of carbon in liquid iron and published austenite-liquid equilibria. The results agree very well with Chip-man's correlation; however, a small difference in the activity of carbon in the high-temperature range of the austenite field is evident. Excellent agreement is found for the heat of solution of graphite in infinitely dilute austenite; from this study the value is 10,550 cal as compared with Chipman's value of 10,680 cal. AS part of a program to study microsegregation in dendritic solidification of ternary Fe-C-Cr alloys, it was desirable to be able to describe the equilibria between austenite and liquid iron in Fe-C-Cr alloys. In this regard, it was necessary to correlate existing data on the activity of carbon in Fe-C austenite as a function of both temperature and composition. At that time, Chipman's analysis1 of the thermodynamics of binary Fe-C austenite was not available. It will be shown that this study and Chipman's study agree rather well throughout the stable austenite range of temperature and composition; however, some small differences appear at temperatures greater than the eutectic temperature. Benz and Elliott 2 presented isoactivity lines for austenite superimposed on their revised Fe-C phase diagram. Using an expression from Darken and Gury 3 representing Smith's4 activity data between 800" and 1000°C, they found that the activities extrapolated above 1000°C to the solidus did not agree with the activities determined from the corresponding liquidus compositions. It is the purpose of the following argument to reconcile carbon activity data of austenite with the activity in liquid Fe-C alloys as determined by Rist and Chipman. 5 In addition, a simple analytical expression is sought for computational convenience. ACTIVITY DATA OF CARBON IN ZRON Fig. 1 shows the activity of carbon in Fe-C austenite as determined by Smith, 4 Schenck and Kaiser, 6 Scheil et a1.,7 and Bungardt et al.' The lines are merely drawn to separate the data into the respective isotherms. These data are inadequate to determine the activity of carbon at temperatures greater than 1200°C. The activity coefficient in Fe-C liquid alloys was assumed by Rist and chipmans to obey the following

Jan 1, 1969

By J. M. Bugbee

The engineer and the conservationist agree that effective water drive is the desirable reservoir production mechanism. Water drive may result either from the expansion of edge water, the reservoir water bordering an oil pool, or from the artesian flow of edge water from the outcrop. Thus, the extent of the reservoir has an important bearing upon both the rate and the ultimate quantity of water influx to an oil pool. Lens-type reservoirs are generally recognizable, but the complete structure of the more important domal types, having possible limitations from crestal and synclinal faulting, is not well understood. The delineation from cores, electrical logs and exploitation phenomena of the crestal portions of reservoirs is increasingly exact. This paper suggests that inference from these factual pictures, combined with the scattered well and geophysical data of the synclines and with consideration of the dynamics of structural formation, may be applied to solving the complete geologic structure. Since faulting on the domes and in the synclines may effectively seal and thus limit the size of a reservoir and bar additional water influx, consideration of geologic structure and its possible effects is essential to complete analysis and prediction of reservoir performance. Introduction Implicit in reservoir studies is the fact that the oil must be displaced from the reservoir rock by some other fluid, either gas or water, and this understanding yields the terms descriptive of the major reservoir production mechanisms, gas expansion and water drive' Three recent papers1-2-3 make clear the economic and conservation preeminence of Water drive as a production mechanism; in fact, the title of the latest of these is " Production under Effective Water Drive as a Standard for Conservation Practice." There appears to be an assumption at times among analysts that the effectiveness of a water drive is solely dependent on the rate of oil production; that is, if water drive appears to be insufficient or lacking, a lower oil-recovery rate would increase or reveal it. This assumption might result from the fact that the analysis has been wholly developed during the period of production curtailment; that is, since 1929. The writer takes it that the recurrent phrase in De Golyer's paper,3 "some degree of water drive," is related to this assumption. In California, an extraordinary phrase, "inactive water drive," is rather common and the connotation of uncertainty regarding our knowledge of reservoir performance is evident. Wyckoff2 speaks of the type of reservoir and performance as follows: "In general, reservoirs may be any one or a combination of domal, faulted, lenticular, or stratigraphic traps. Insofar as the dynamic performance of such reservoirs is concerned, the particular type merely determines whether regional flow is symmetrical as in a uniformly developed domal or lenticular type, or one-sided as in many stratigraphic or faulted traps." But whether the flow is

Jan 1, 1943

By J. M. Bugbee

The engineer and the conservationist agree that effective water drive is the desirable reservoir production mechanism. Water drive may result either from the expansion of edge water, the reservoir water bordering an oil pool, or from the artesian flow of edge water from the outcrop. Thus, the extent of the reservoir has an important bearing upon both the rate and the ultimate quantity of water influx to an oil pool. Lens-type reservoirs are generally recognizable, but the complete structure of the more important domal types, having possible limitations from crestal and synclinal faulting, is not well understood. The delineation from cores, electrical logs and exploitation phenomena of the crestal portions of reservoirs is increasingly exact. This paper suggests that inference from these factual pictures, combined with the scattered well and geophysical data of the synclines and with consideration of the dynamics of structural formation, may be applied to solving the complete geologic structure. Since faulting on the domes and in the synclines may effectively seal and thus limit the size of a reservoir and bar additional water influx, consideration of geologic structure and its possible effects is essential to complete analysis and prediction of reservoir performance. Introduction Implicit in reservoir studies is the fact that the oil must be displaced from the reservoir rock by some other fluid, either gas or water, and this understanding yields the terms descriptive of the major reservoir production mechanisms, gas expansion and water drive' Three recent papers1-2-3 make clear the economic and conservation preeminence of Water drive as a production mechanism; in fact, the title of the latest of these is " Production under Effective Water Drive as a Standard for Conservation Practice." There appears to be an assumption at times among analysts that the effectiveness of a water drive is solely dependent on the rate of oil production; that is, if water drive appears to be insufficient or lacking, a lower oil-recovery rate would increase or reveal it. This assumption might result from the fact that the analysis has been wholly developed during the period of production curtailment; that is, since 1929. The writer takes it that the recurrent phrase in De Golyer's paper,3 "some degree of water drive," is related to this assumption. In California, an extraordinary phrase, "inactive water drive," is rather common and the connotation of uncertainty regarding our knowledge of reservoir performance is evident. Wyckoff2 speaks of the type of reservoir and performance as follows: "In general, reservoirs may be any one or a combination of domal, faulted, lenticular, or stratigraphic traps. Insofar as the dynamic performance of such reservoirs is concerned, the particular type merely determines whether regional flow is symmetrical as in a uniformly developed domal or lenticular type, or one-sided as in many stratigraphic or faulted traps." But whether the flow is

Jan 1, 1943

By Leonard Obert

The structural stability of any mine or under- ground opening in rock is dependent on the stress field, that is, the state of stress in rock before mining, the stress distribution in the rock created by the opening, and the in situ strength of the rock. In the past mine design problems have been considered by assuming that the stress field is due only to the weight of the overlying rock, the stress around the opening can be calculated from elastic theory using laboratory-determined elastic constants, and the in situ strength of the rock can be determined from laboratory tests on small specimens. Solutions to hypothetical problems using this procedure are given in a report by Obert, Duvall, and Merrill.' Because of the uncertainties of these assumptions, this method can give only a rough approximation to the solution of actual structural problems. Obviously, this approach to determining the stability of underground openings would be greatly improved if the rock stress could be measured in situ, and it is undoubtedly for this reason that in recent years many investigators have spent considerable effort on the development of procedures for measuring rock stress. In this report a method is described for determining in situ the absolute stress in rock. The method requires the measurement of the deformation of a borehole before and after the rock is stress-relieved. The magnitude and direction of the applied stresses are calculated from the borehole deformation and modulus of elasticity of the rock. Also, the results of absolute stress determination made in the walls and pillars of underground openings in five rock types are presented. From these results a number of conclusions are drawn regarding the accuracy and limitations of this method and the problem of stress measurements in general.

Jan 8, 1962

By William B. Phillips

The possible sources of potash salts in the United States have been considered from many points of view during the last several years, but it is only within the last two or three months that the situation has become acute. We import from Germany, the only sourcc of large supply, more than $10,000,000 worth of potash salts annually, and this business has been badly crippled by the European war. If there was ever a time in our industrial existence when the necessity of providing for our own needs was more acute than it is now, we are not aware of it. One has only to study the price lists of chemicals sent out by the large supply houses to see the change wrought within a very short time. Whether or not these prices are to maintain for a considerable time, no one can say; but it appears to be probable that we shall not see prices materially lower for a period of uncomfortable length, to say the least. It is not my purpose at this time to discuss the various sources of supply of potash salts that have been suggested or recommended. Some of them might afford a pleasing relief but all of them combined would not affect the situation seriously. If we are to have our own sources of potash salts, they will have to compare, in some efficient manner, with the sources upon which we have drawn during the last 20 or 30 years; i.e., they must exist in minable quantities. It seems to me to be quite idle to speculate upon our domestic sources of potash if those sources are not of a character similar to those upon which we have so long depended. A few thousand or, perhaps, a few hundred thousand dollars' worth of chemically derived potash may be produced under the stress of present conditions, but when we consider that each year demands more than $10,000,000 worth, we must look to underground sources; we must look to mines similar to the famous Stassfurt and Halle deposits. If we cannot mine potash salts, we shall have to do without them for a while.

Jan 1, 1915

By AIME AIME

BEGINNING Thursday, July 16, the National Broadcasting Co. is broadcasting from 6:30 to 6:45 p.m., over its nationwide network and possibly also by short wave a series of eleven radio programs dealing with the contributions of engineers to the prosecution of the war. The series is being arranged and sponsored by a committee of representatives of the national engineering societies, R. L. Sackett, chairman. The committee began its deliberations before Pearl Harbor and had scripts under way on blackouts, bombs, and damage to structures. The declaration of war emphasized the importance of the proposed radio program. The National Broadcasting Co. and the Office of Civilian Defense enthusiastically endorsed the committee's proposal and have been generous in their help and approval of scripts so far submitted. Controversial matters are included in the broadcasts and changes will be made when requested by O.C.D. up to the minute that a program goes on the air. In this way the latest and authoritative information will be given.

Jan 1, 1942

By George H. Eldridge

The existence of phosphate of lime within the State of Florida has been known for over a decade; but until the spring of 1887, the extent and value of its deposit.;, possibly with one exception, were unsuspected. In that year Col. T. S. Moorehead, induced by a statement made by Mr. J. F. Le Baron, examined the gravels of the Peace river, recognized the importance of the deposits, acquired such tracts as were regarded as desirable, and established the pebble-phosphate industry, making his first shipment in May, 1888, to the Scott Manufacturing Company, of Atlanta, Ga. The establishment of the pebble-phosphate industry upon Peace river was followed, a year later, by the discovery in Marion county of an entirely different class of phosphate, now commonly known as hard-rock phosphate. This discovery was made early in June, 1889, by Mr. Albertus Voght, in a well which he was sinking upon his place near the site of the present town of Donnellon, about 20 miles southwest of Ocala. To it, more than to any other cause, is due the rapid and remarkable development of the present great industry of the State. It was, however, Mr. John F. Dunn, of Ocala, who turned to advantage the accidental discovery of Mr. Voght. After acquiring a knowledge as to the chemical composition and value of the material, Mr. Dunn and hid associates purchased several thousand acres of land and organized the Dunnellon Phosphate Company for active operations. From Dunnellon as a center, prospecting rapidly extended in all directions, until at the present day important mines have been opened over a well-defined tract more than 200 miles long and about 6 miles wide. This tract lies par-

Jan 1, 1893

By Wllliam D. Davis

C OMMERCIAL production of oil in northeastern Oklahoma began in 1897 and in the next two decades this area became one of the greatest oil districts of the time. Its importance is now secondary, but thousands of wells in this area have produced uninterruptedly for more than thirty years. They are now classified as stripper wells. By means of what is known as water flooding their L. production can be considerably in- creased. This practice consists in injecting water under pressure into the sand surrounding an oil well, thus displacing the oil in the pores of the sand and forcing it into the oil well.

Jan 1, 1940

By D. Malhotra, R. M. Hoover

The effect of a surfactant, designated Syntex, on the wetting and spreading of hydrocarbon oil on molybdenite surfaces (faces) has been investigated experimentally through measurements of zeta potentials and factorially designed flotation tests. These studies indicate that Syntex has a positive effect in increasing molybdenite recovery in the rougher flotation circuit at the Climax mill. The analysis of experimental data using DLVO theory shows that the controlling factor in determining the magnitude of the repulsive energy barrier preventing oil from wetting and spreading on the molybdenite faces is the MoS2 zeta potential and the vapor oil droplet size. The role of Syntex in this case seems to be related to the decrease and stabilization of MoS2 zeta potential by Syntex adsorption and also to the emulsifying action of Syntex on vapor oil to provide a more favorable oil particle size.

Jan 1, 1976

By John L. JR. Schroder

INTRODUCTION-SYSTEM DESIGN The design of an underground mining operation requires the integration of transportation, ventilation, ground control, and mining methods to form a system which provides the highest possible degree of safety for mine personnel; the lowest cost per ton of product; the most suitable quality of final product, considering its intended use; the maximum percent recovery of the reserve, consistent with cost and subsidence rights ; and the minimum disturbance to the environment. The selection of mining method is generally the controlling factor in overall mine design. Some important considerations in the choice of mining method are : 1) Depth of cover over the coal seam. 2) Strength and thickness of rock strata in the overburden. 3) Characteristics of the coal seam, including thickness, nature and location of impurities or irregularities, dip (or pitch), nature and direction of cleavage, hardness, and structural strength of the coal. 4) Nature and strength of the immediate roof (top) over the coal seam. 5) Nature and strength of the floor (bottom) under the coal seam. 6) Presence and amount of explosive gas (methane). 7) Quantity of water likely to be encountered in the mining operation. 8) Any previous or concurrent mining in seams above or below the coal seam to be worked. 9) Any restrictions on recovery required for subsidence control. Topographical and geological reports and maps of the area are usually available from state and federal geological surveys, and contain excellent general information to guide more detailed investigations. Exploratory drilling, and the plotting and analysis of the information thus obtained, are essential steps in any development program, and aid in the correlation and evaluation of information gained by other means. Other good sources of information are operating coal mines that may be in the same

Jan 1, 1981

By B. G. Klugh

(New York Meeting, February, 1913.) THE present paper represents a preliminary investigation of the ultimate structure of iron-bearing materials which have been subjected to heat treatment for the purpose of agglormer-ating the fines, or for chemical changes, or for both. Primarily, the object of this inquiry was to determine the relation of the microstructure of each of these materials-to its specific susceptibility to the action in the blast-furnace. It is hoped that this small contribution will serve as a nucleus to a line of research that will throw some light upon the debated questions involved in blast-roasting. Thus far the investigation has been conducted along lines of analogy of known principles, rather than through the applica-tion of any well-defined system of microscopic petrography. This is obviously due to the fact that we are dealing with materials which are the artificial products of a new art, rather than with the natural materials from which the essence of the pure science has been evolved. In the limited tune allowed for this research, it has been conducted upon those materials the chemical content of which allows of their use commercially in the blast-furnace.

Jan 5, 1913

By John Wulff, David A. Stevenson

The solubility of iron and cobalt in liquid lead, the solubility of chromium in liquid tin, and nickel in liquid silver were determined up to 1300°C in an atmosphere of hydrogen. Liquid samples were taken at different temperatures and analyzed. The data obtained were plotted to show the relationship between log mole fraction of solute and the inverse of the absolute temperature. Resulting values for the differential heat of solution (AH) and the excesspartial molar entropy (S)are: for the iron-lead system = _24,200 cal per mole and AT = 5.0 e.u. for the a phase, and AH = 18,300 and S = -0.1 e.u. for the y phase; for the cobalt-lead system AH = 16,500 cal per mole and AS =0.7 e.u.; for the chromium-tin system AH = 15,600 cal per mole and AS = 8.5 e.u.; for the nickel-silver system AH =18,000 cal per mole and AS = 4.0 e.u. RECENT developments in coating, brazing, and heat transfer have focused attention on specific cases of solid-liquid interaction in metal systems, particularly those involving dilute liquid solutions. One fundamental quantity of interest in such systems is the equilibrium phase distribution between solid and liquid phases. In any effort to fully understand such interactions, one must be able to describe the equilibrium state precisely. Furthermore, in order to develop genera! relations for such systems, one must know the equilibrium state in a number of different cases. This investigation was devoted to a study of the equilibrium phase distribution in four binary systems: solid iron-liquid lead; solid cobalt-liquid lead; solid chromium-liquid tin; solid nickel-liquid silver. The iron-lead system was previously studied by Shepard and parkman' and later by Fleischer and Elliott2 with differing results. Both investigations were carried out by sampling the saturated liquid, and analyzing it chemically. The cobalt-lead system was previously reported by Pelzel,3 who noticed no discontinuity near the transformation. A limited investigation of the chromium-tin system was made by Wlodek and wulff4 using a weight loss method. This work was done in conjunction with the development of a process for coating molybdenum with chromium from tin solutions. To more fully under- stand the kinetics of the process, a more accurate determination of a solubility was desirable. No significant data were found in the literature on the nickel-silver system. Data on the latter system were, however, relevant to the investigation of the corrosion kinetics of copper-nickel alloys in liquid silver as carried out by Harrison and wagner,5 EXPERIMENTAL APPARATUS AND PROCEDURE Of the techniques available for the study of such systems the most effective appears to be that of liquid sampling,2,6,7 which is the method used in the present investigation. A schematic diagram of the sampling furnace is given in Fig. 1. Large pieces of solute metal, in excess of saturation solubility, were added to 200 g of the solvent metal, and the entire charge placed in an alundum crucible. Analytical reagent or materials of chemically pure grade were used in all investigations. The crucible was contained in a zircon muffle tube positioned vertically in the uniform hot zone of a Globar resistance furnace. The tube was provided with a number of ports which permitted sampling at temperature and in controlled atmospheres or vacuum; the ports were also useful for evacuation and introduction of gases as well as for thermocouple measurements. A chromel-alumel thermocouple Sheated in a porcelain tube was used for temperature measurements. A purified hydrogen atmosphere was employed in all experiments reported in this paper. The hydrogen was purified by passing it first over hot copper gauze to remove oxygen and then through a molecular sieve immersed in

Jan 1, 1962

GENERAL Broken Hill lies at latitude 31º58'S longitude 141º27'E on the semi-arid western plains of New South Wales. From discovery in 1883 until the end of 1969 the lead-silver-zinc orebody has yielded 107,570,000 tons of ore for an overall grade of 13.1% Pb, 6.9 oz Ag/ton and 9.4% Zn.* The orebody currently supports the activities of four mines which are, from north to south, North Broken Hill Limited, Broken Hill South Limited, The Zinc Corporation, Limited and New Broken Hill Consolidated Limited. It is estimated that in 1969 these mines produced about 8 ½ % of world lead production and about 6% of world zinc production. In 1905 The Zinc Corporation, Limited was founded to recover zinc from tailings dumps and moved into mining in 1911 on leases purchased from Broken Hill South Limited at the then southern extremity of the "line of lode". New Broken Hill Consolidated Limited was formed in 1936 to explore and mine for deep ore in the leases to the south of The Zinc Corporation which were purchased from Barrier South Limited. The Zinc Corporation, Limited and New Broken Hill Consolidated Limited mines are both managed by Conzinc Riotinto of Australia Limited, which wholly owns The Zinc Corporation, Limited and has a 32% interest in New Broken Hill Consolidated Limited. * Throughout this paper tons referred to are long tons of 2,240 lbs.

Jan 1, 1970

By D. Hanson

Fox most of their practical applications metals are required to with-stand stresses of appreciable magnitude: indeed, it is because they possess the quality of resisting stress without becoming permanently deformed that they find such extensive use in the service of man. Metals and alloys must, in service, usually behave as elastic substances-or nearly so. It is not difficult to satisfy this condition at ordinary temperatures. Iron and its alloys, especially the steels, are at normal temperatures excellent elastic bodies, capable of satisfying most of the mechanical requirements of the engineer: where electrical, chemical or other properties are impor-tant, which cannot be met by steels, it is usually possible to find a non-ferrous alloy such as nickel, copper or aluminum, which will prove satisfactory. When the metals or alloys are not inherently sufficiently elastic, cold-working or heat-treatment may develop elastic properties to a sufficient extent for practical needs. By means of relatively simple, rapid tests we can measure such properties as elastic modulus, limit of proportionality and proof stress, upon which design can be based with confidence. The case of the soft metals, such as lead and tin, is well known to be exceptional. They possess no definite limit of elasticity, and the value of proof stress or tensile strength depends to a great extent on the speed with which the test is carried out. Design here must be based on other considerations than a well-established theory of the proportionality of stress and strain. It is now generally recognized that steels and non-ferrous alloys possess at temperatures not greatly exceeding that of the atmosphere, characteristics quite different from those existing at ordinary temperatures, and that they assume qualities similar to those of the soft metals. Not only have they no limit of elasticity, but the proof stress and the ultimate stress depend on the time of application of the load. Flow under load may persist for long periods of time, possibly indefinitely, and the determination of a true maximum stress becomes a matter of great difficulty.

Jan 1, 1939

INTRODUCTION Data available on prophyry copper occurrences in the Andean, Caribbean, Appalachian, and Cordilleran orogens may be categorized in a manner to suggest a hypothetical evolution for deposits that occur in the western hemisphere. A classification of de- posits is also suggested. A classification dependent on internal structure of a porphyry copper deposit would lead to two broad categories, breccia pipe and stockwork models. A classification of this type is examined herein but it is not universally accepted in the literature. Modeling based on igneous petrography as well as metasomatism attendant with the sulfide mineralization is more widely accepted by economic geologists whose evaluation of porphyry systems is influenced by the presence or absence of a phyllic zone. Lowell and Guilbert model deposits ordinarily include a phyllic zone, whereas those of the diorite model do not. Position of the phyllic zone in the alteration sequence is a significant ore guide. Should the phyllic zone be absent, dependence on alteration zoning to identify metallization is weakened. Presence or absence of the phyllic zone therefore is a significant parameter in the economic evaluation of a porphyry copper deposit (Hollister. et al., 1975). The Lowell and Guilbert (1970) model commonly includes a phyllic zone in quartz- bearing rocks. Parameters of both calc-alkalic and the quartz monzonite models mentioned elsewhere in this volume are sufficiently close to the Lowell and Guilbert (1970) model that it should be expanded to encompass them. The diorite model remains separate and distinct because deposits of this type are characterized by an absence of quartz in the pluton, commonly highly gold: copper ratios, low molybdenum content, and regular absence of sericite in the alteration zones. Therefore, for the benefit of those

Jan 1, 1978

By M. S. Smani, P. Blazy, J. M. Cases

Investigations on the beneficiation of sedimentary Moroccan phosphate ores are reported in four separate parts. The first discusses electrochemical phenomena at the solid-aqueous solution interface for minerals of the apatite group. In the second part, the electrochemical properties of the calcareous gangue associated with the phosphate ore are investigated. The flotation of calcite and phosphate oölites, using both anionic and cationic collectors, is discussed in the third part. It is shown that selective recovery could be obtained for precise concentrations of collectors and pH ranges. Results of work aimed at optimizing depression of phosphate oölites during inverse flotation of the carbonate gangue with sodium oleate are reported in Part 4.

Jan 1, 1976

By Robert McKay

THE practical study of corrosion requires consideration off its economic aspects. It must be based on sound scientific principles, but it should be borne in mind that probably the most important object of a corrosion test is to determine what metal in corrosion-resisting construction will produce the greatest operating profit. Thus the corrosion test must be directly connected with money values or it is not a practical corrosion test. This, perhaps unusual, connection between corrosion and economics is partially due to the fact that corrosion deals only with the time factor or duration of equipment, and it is almost the only test which deals with this feature. In these statements a departure is made from the academic definition of the word corrosion and it is done deliberately. The use of the term corrosion is unusual. It is as though we spoke of a tensile test as. a "breaking" test. We are not interested primarily in the break but in the strength of the metal. There is no English word which expresses our main interest in corrosion-testing, but let us have clearly in mind that we make corrosion tests to prevent corrosion. Our real interest is in this corrosion-prevention, not in the corrosion. Previous to 1922, it was common comment that "it is impossible to determine the course of corrosion by laboratory testing." This statement was true at that time in that the technique of laboratory testing for corrosion resistance was so vague that tests in the laboratory gave untrue results almost as often as true ones. This was so, even in the simple case of determining which one of two metals better resists a given solution. While this is no longer true the number of misleading "corrosion tests" still being ground out by laboratories is too large in the light of our present knowledge. There are two important features of corrosion testing whose neglect is a large contributing factor to misleading results: (1) The economic relations of the corrosion tests to other tests; (2) testing technique.

Jan 1, 1929