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By Charles A. Schaeffer

IN the early part of last year I received a small amount of powdered mineral from Williamson County, Texas, to be examined for silver. The specimen proved to be limestone, slightly colored

Jan 1, 1883

By Charles R. Keyes

I. INTRODUCTION. FOR a period of several years, and in a large number of cases, the Metallurgical Laboratories of the New Mexico School of Mines were employed in umpire work. During this time many important local problems were solved. Against the results of careful chemical analyses of ores, assay-returns were often checked. In many cases the assay-methods of mine and custom-smelter were compared, and both often found faulty for the ore concerned. A wide range of ores was covered. Many of the chemical analyses and assays were made by Dr. F. C. Lincoln, Professor of Metallurgy, now of the Montana State School of Mines. A varied series of instructive assays was prepared by Prof. R. B. Brinsmade, now of the West Virginia State University. Single assays and given series of tests were undertaken by H. T. Goodjohn, now chief chemist to the Cia. Metalurgica de Torreon, Coahuila, Mexico; by H. J. Hubbard, now superintendent of the Butters Divisadero Mines, Jocoro,. San Salvador, C. A.; by E. D. Morton, now superintendent of the Arizona & Nevada Copper Mining Co., at Lunning, Nev. ; and by A. W. Edelen, now superintendent of the Angangueo Unit of the American Smelting & Refining Co., in Michoacan, Mexico. A critical comparison of assay-methods that were found to be followed in the case of certain gouge-ores mined in the Mimbres range in New Mexico, and about which there had been much controversy, was made by D. F. Riddell, then Acting Professor of Assaying, and now superintendent of the Providentia Mines Co. of Parral, in Chihuahua, Mexico. To him is due the credit of much that is contained in the following notes, which be has generously permitted -to be used in advance of the publication of the complete results.

Jul 1, 1911

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Member, aged 25, recent graduate, with some experience in laboratory of steel plant, desires position as metallurgist or assistant in copper, aluminum, or steel works. No. 118. Member, aged 52, technical graduate, with 20 years' experience as engineer with coal-mining companies, desires position as engineer or superintendent of coal mine. No. 119. Member, aged 39, technical graduate, with extended experience in surveying, assaying, milling, and copper smelting, desires position along cyaniding, concentration, or copper-smelting lines. No. 120. Member, aged, 38, technical graduate, with several years' experience in research work, in mine operation and as professor of mining engineering, is desirous of engagement in planning concentration and metallurgy of odd and difficult ores. No. 121. Member, aged 32, graduate M. I. T. in mining and metallurgy, at present and for last five years superintendent of Western lead smeltery, will consider engagement with solid company, if opening promises advancement. Specialty, smelting of lead ores, high in lead and zinc content. Ten years' experience in the operation, design, and erection of a large lead plant. Now desirous of bettering position.. No. 122.

Jan 8, 1914

By Cecil H. Desch

THE progress of metallurgical practice and the demands made by the engineering industry on our foundries and mills have made the crystalline structure of metals a subject of far more than academic interest. Metals and alloys are made up of crystals. Even if we accept the view, so ably maintained by some metallurgists, that the crystals are separated from one another by an amorphous layer, it remains true that all but a very minute fraction of any metallic mass is crystalline. The conditions which affect the growth of crystals are therefore of importance in metallurgy. It is not only castings whose properties depend on the arrangement of their crystals, for the more we learn of the behavior of forged, rolled and drawn metals, the more certain it becomes that it is profoundly influenced by the size and arrangement of the crystals in the original ingot, deter- mining a structure which may persist in a modified form through a long series of mechanical operations and annealings. This is mainly due to the concentration of much of the impurities in the last portions of the liquid to freeze, so that the boundaries between single crystals or groups of crystals are marked out by a zone of segregated material, differing in properties from the mass, and offering a barrier to diffusion and equalization of composition throughout the whole. The importance of this fact has been fully recognized by steel manufacturers, who have to deal with ingots which are sometimes very large, and are cast at a high temperature, containing impurities which have a marked effect on the properties even when present in very small quantity. For this reason the Iron and Steel Institute has set up a committee to examine the whole question of the heterogeneity of steel ingots,(l)f and a report has been issued, containing an account of the structure of 16 ingots, ranging in weight from 15 cwt. to 172 tons, each of which was sectioned and examined by chemical analysis and by etching. A valuable body of data concerning segregation has thus been collected. The work of the committee is being prosecuted with great activity, and at the same time researches are in progress to determine the physical

Jan 1, 1927

By Thomas A. Simpson, Russell A. Walker

Hydrogeological techniques were used to solve problems of slope stability in open-pit mines of the Eufaula bauxite district, Ala. Geologic and hydrologic data were evaluated and used to design a system of dewatering wells to enable the operators to mine bauxite more efficiently and economically. Walls of open-pit mines in the district were subsequently stabilized by the operation of the dewatering system. Three open- pit mines, each at varying stages of the mining process, of the A.P. Green Refractories Co., were used to develop a sequential series of guidelines that indicate how to effectively remove ground water from the formations surrounding the ore bodies in the district. The use of sound engineering principles in well design, in combination with the correct interpretation of the pit hydrology provided the basis for solutions of the slope-stabilization problem and aided in the economical removal of bauxite from mines of the district.

Jan 1, 1976

By William E. Galloway, Gary E. Smith, Christopher D. Henry

INTRODUCTION Studies relating to the Oakville aquifer as presented in this report and by Henry et al. (this volume), are part of a larger , comprehensive examination of regional and local stratigraphic, hydro- geologic, and geochemical parameters within the Oakville Formation recently completed by the Bureau of Economic Geology. The Oakville serves both as a major Gulf Coast aquifer and an important uranium host (Fig. 1). Regional and local controls on hydrodynamics and hydrochemistry have important implications for hydrochemical exploration, the establishment of premining baseline parameters, and the design of post mining restoration procedures. Investigations of the Oakville Formation were de- signed for the purpose of determining the response of the aquifer to uranium extraction and were funded by the U.S. Environmental Protection Agency under grant numbers R-805357-01 and R-805357-02. Physical Stratigraphy Physical stratigraphic analysis shows that the Oakville Sandstone, a lithostratigraphic unit deposited by a major coastal-plain f luvial system, consists of five mappable, component depositional elements (Figs. 2 and 3). Each major component element is the product of one or more rivers traversing the Miocene coastal plain. In turn, each river possessed a unique sediment load, discharge characteristics, and source terrane. Consequently, each element exhibits distinguishing geometric and compositional parameters that potentially influence the flux and hydrochemical evolution of contained ground waters (Galloway, Henry, and Smith, in preparation). The Oakvil le Sandstone, as mapped and interpreted as a lithostratigraphic unit in the study area, corresponds closely to the Jasper aquifer system, an equally well-defined Gulf Coastal Plain hydrogeologic unit (Baker, 1978). Principal surrounding hydrogeologic units include the underlying Catahoula confining system, the Jasper aquifer system itself, and the overlying Burkeville confining system (lower Fleming mudstones). The Evangeline aquifer system includes much of the Fleming Formation. The Jasper aquifer system is bounded above and below by relatively less transmissive, finer grained confining systems, although absolute transmissivity varies greatly within both the Jasper and confining units. Lithostratigraphic and hydrogeologic boundaries coincide almost exactly within the Hebbronville flu- vial axis (Fig. 3). Correspondence of geologic and hydrostratigraphic boundaries is good within the George West axis; farther to the northeast the correlation of the Jasper aquifer with units mapped as Oakville Formation diverges to varying degrees. A complete analysis of these trends and a study of the depositional facies comprising the Oakvillle are included in Galloway, Henry, and Smith (in preparation). REGIONAL HYDROGEOLOGY The stratigraphic, compositional, and structural framework of the Oakville Formation and the mosaic of interrelated depositional facies that are combined in this framework play a key role in defining the hydrogeology of the Oakville. Furthermore, a combination of climate and hydrogeology, as well as past and present socioeconomic conditions, has determined water and land use patterns within the region of Oakville outcrop. Utilization of Oakville Ground Water Stratigraphic control for determining which wells produce ground water from the Oakville aquifer was established by preparing structural and isopach maps of the Oakville Formation using regional electric log cross sections. Surface elevation and screened interval data (or total well depth, if open-hole completion techniques were used) from each water well, combined with the stratigraphic data, allowed accurate assessment of the producing aquifer for individual wells. Information on well and screen depths, water levels, and usage of water from

Jan 1, 1980

By C. D. Ramsden

During the war years of 1941 to 1945, maintenance of mine locomotives and other mine equipment took the form of rebuilding rather than of renewing. Purchase of new parts became increasingly difficult and mine operators found it necessary to maintain equipment by salvaging old parts. Mine-locomotive wheels, although not representing a high cost per pound of material, contain a considerable amount of steel and without rebuilding would have to be scrapped long before even a moderate percentage of the steel in the wheel is actually consumed. Many mine operators have been rebuilding locomotive wheels for several years with automatic open are-welding equipment. In 1927, the Pittsburgh Coal Co. started such a program, using a single Westinghouse automatic welding head. Since that time, many refinements have been added, until in 1944 the setup was operating very efficiently. A desire to increase wheel life and to hold down rising costs led the company in 1944 to investigate the possibilities of the under-flux are-welding process for wheel rebuilding, although at that time, little or no work had been done on multiple pass or "build-up" welding with the underflux arc. Work with this process had been confined largely to welding together flat plates in a "down hand" position. Possibilities for savings were intensified by the fact that the company has 300 locomotives in operation, using actively or as spares 1200 sets of wheels. During 1942 and 1943, about 500 sets of wheels were sent each year to the company's maintenance shop at Library, Pa., for rebuilding. Based on having 800 sets in service (many of the company's heavy locomotives have three sets of trucks), the average life of a set of wheels was approximately 19 months. Anything that could be done to increase wheel life promised sizable annual savings. Open Arc Welding With the open arc process, a set of wheels could be rebuilt for about 40 pet of the cost' of new wheels. Underflux arc welding gave promise of greatly increased welding speeds, more homogeneous, dense deposits and the chance for use of a wider range in welding-wire compositions. Against this was ranged the higher cost of materials and the cost of developing the process from the theory to a practical reality. Since 1927, when a single open arc head was placed in operation, fixed welding procedures had been gradually developed, a positioner for handling a set of wheels was built, and a second head was placed in operation in order to weld two wheels simultaneously. The fixture, or positioner, which was built to position and turn the wheels under the two welding heads, included a motor drive, controlled by a rheostat, which rotated the wheels through a double set of speed reducers and a removable jaw coupling attached to one end of the axle of the wheel truck.

Jan 1, 1947

By C. D. Ramsden

During the war years of 1941 to 1945, maintenance of mine locomotives and other mine equipment took the form of rebuilding rather than of renewing. Purchase of new parts became increasingly difficult and mine operators found it necessary to maintain equipment by salvaging old parts. Mine-locomotive wheels, although not representing a high cost per pound of material, contain a considerable amount of steel and without rebuilding would have to be scrapped long before even a moderate percentage of the steel in the wheel is actually consumed. Many mine operators have been rebuilding locomotive wheels for several years with automatic open are-welding equipment. In 1927, the Pittsburgh Coal Co. started such a program, using a single Westinghouse automatic welding head. Since that time, many refinements have been added, until in 1944 the setup was operating very efficiently. A desire to increase wheel life and to hold down rising costs led the company in 1944 to investigate the possibilities of the under-flux are-welding process for wheel rebuilding, although at that time, little or no work had been done on multiple pass or "build-up" welding with the underflux arc. Work with this process had been confined largely to welding together flat plates in a "down hand" position. Possibilities for savings were intensified by the fact that the company has 300 locomotives in operation, using actively or as spares 1200 sets of wheels. During 1942 and 1943, about 500 sets of wheels were sent each year to the company's maintenance shop at Library, Pa., for rebuilding. Based on having 800 sets in service (many of the company's heavy locomotives have three sets of trucks), the average life of a set of wheels was approximately 19 months. Anything that could be done to increase wheel life promised sizable annual savings. Open Arc Welding With the open arc process, a set of wheels could be rebuilt for about 40 pet of the cost' of new wheels. Underflux arc welding gave promise of greatly increased welding speeds, more homogeneous, dense deposits and the chance for use of a wider range in welding-wire compositions. Against this was ranged the higher cost of materials and the cost of developing the process from the theory to a practical reality. Since 1927, when a single open arc head was placed in operation, fixed welding procedures had been gradually developed, a positioner for handling a set of wheels was built, and a second head was placed in operation in order to weld two wheels simultaneously. The fixture, or positioner, which was built to position and turn the wheels under the two welding heads, included a motor drive, controlled by a rheostat, which rotated the wheels through a double set of speed reducers and a removable jaw coupling attached to one end of the axle of the wheel truck.

Jan 1, 1947

By C. D. Ramsden

DURING the war years of 1941 to 1945, maintenance of mine locomotives and other mine equipment took the form of rebuilding rather than of renewing. Pur¬chase of new parts became increasingly difficult and mine operators found it necessary to maintain equipment by sal¬vaging old parts. Mine-locomotive wheels, although not representing a high cost per pound of material, contain a con¬siderable amount of steel and without rebuilding would have to be scrapped long before even a moderate percentage of the steel in the wheel is actually consumed. Many mine operators have been re¬building locomotive wheels for several years with automatic open arc-welding equipment. In 1927, the Pittsburgh Coal Co. started such a program, using a single Westinghouse automatic welding head. Since that time, many refinements have been added, until in 1944 the setup was operating very efficiently. A desire to increase wheel life and to hold down rising costs led the company in 1944 to investigate the possibilities of the under¬flux arc-welding process for wheel rebuild¬ing, although at that time, little or no work had been done on multiple pass or "build-up" welding with the underflux arc. Work with this process had been confined largely to welding together flat plates in a "down hand" position. Possibilities for savings were intensified by the fact that the company has 300 locomotives in operation, using actively or as spares 1200 sets of wheels. During 1942 and 1943, about 500 sets of wheels were sent each year to the company's maintenance shop at Library, Pa., for rebuilding. Based on having 800 sets in service (many of the company's heavy locomotives have three- sets of trucks), the average life of a set of wheels was approximately 19 months. Anything that could be done to increase wheel life promised sizable annual savings. OPEN ARC WELDING With the open arc process, a set of wheels could be rebuilt for about 40 pct of the cost of new wheels. Underflux arc welding gave promise of greatly increased welding speeds, more homogeneous, dense deposits and the chance for use of a wider range in welding-wire compositions. Against this was ranged the higher cost of materials and the cost of developing the process from the theory to a practical reality. Since 1927, when a single open arc head was placed in operation, fixed welding procedures had been gradually developed, a positioner for handling a set of wheels was built, and a second head was placed in operation in order to weld two wheels simultaneously. The fixture, or posi¬tioner, which was built to position and turn the wheels under the two welding heads, included a motor drive, controlled by a rheostat, which rotated the wheels through a double set of speed reducers and a removable jaw coupling attached to one end of the axle of the wheel truck.

Jan 1, 1946

By Tom Bilson

TO recover the remaining ore tonnages along the south side of the Inspiration orebody, the company began open-pit operations in early 1948 in addition to underground mining. Due to the differences in elevation between the orebody and the existing ore handling and treating plants, the truck haulage operation is up hill. Road grades were established at 7 pct maximum.

Jan 8, 1951

By George A. Roberts, Robert F. Mehl

When austenite first forms from aggregates of cementite and ferrite, it is not homogeneous.' This inhomogeneity, consisting of both undissolved carbide and carbon concentration gradients, has a profound effect upon the characteristics of the austenite-pearlite reaction. The rate of formation of pearlite is increased by the presence of inhomogeneities2,3 and because of this (when the inhomogeneity is sufficiently pronounced) the hardenability of the steel is reduced.4,5 In addition to this kinetic effect, inhomogeneities will cause the direct formation of spheroidite from austenite at temperatures just below the Ael.6-11 The present report attempts quantitatively to evaluate the effect of inhomogeneity upon the rate of the austenite-pearlite reaction, presents a method of determining the austenitizing cycle necessary to obtain "practical homogenization," and considers the effect of inhomogeneity on hardenability. Effect of Inhomogeneities on Reactions Near Ae1 Few quantitative data are available representing the effect of undissolved carbide or of carbon concentration gradients upon the rate of the austenite-pearlite reaction. In procuring such data it is necessary to separate the effect of undissolved carbide from that of grain size, and this is not an easy task. The solution of carbide is always accompanied by an increase in the grain size, both effects contributing to the retardation of the reaction rate. It has been possible to make this separation and to obtain data that are independent of the grain size by the use of steels that differ only with respect to their tendency toward grain-coarsening. Steels C and D in Table I are such steels. These steels have been studied previously ;l,2,12 they differ only with respect to deoxidation practice; C was deoxidized with silicon while D, teemed from a portion of the same heat, was deoxidized with additional auantities of aluminum in the mold. C therefore is what is normally termed a "coarse-grained steel" and D is a, "fine-grained steel." These steels can be compared at the same grain size by heating c to a low temperature and heating D to an elevated temperature, producing a structure of austenite plus residual carbide in the former while forming homogeneous austenite in the latter; in such

Jan 1, 1943

By George A. Roberts, Robert F. Mehl

When austenite first forms from aggregates of cementite and ferrite, it is not homogeneous.' This inhomogeneity, consisting of both undissolved carbide and carbon concentration gradients, has a profound effect upon the characteristics of the austenite-pearlite reaction. The rate of formation of pearlite is increased by the presence of inhomogeneities2,3 and because of this (when the inhomogeneity is sufficiently pronounced) the hardenability of the steel is reduced.4,5 In addition to this kinetic effect, inhomogeneities will cause the direct formation of spheroidite from austenite at temperatures just below the Ael.6-11 The present report attempts quantitatively to evaluate the effect of inhomogeneity upon the rate of the austenite-pearlite reaction, presents a method of determining the austenitizing cycle necessary to obtain "practical homogenization," and considers the effect of inhomogeneity on hardenability. Effect of Inhomogeneities on Reactions Near Ae1 Few quantitative data are available representing the effect of undissolved carbide or of carbon concentration gradients upon the rate of the austenite-pearlite reaction. In procuring such data it is necessary to separate the effect of undissolved carbide from that of grain size, and this is not an easy task. The solution of carbide is always accompanied by an increase in the grain size, both effects contributing to the retardation of the reaction rate. It has been possible to make this separation and to obtain data that are independent of the grain size by the use of steels that differ only with respect to their tendency toward grain-coarsening. Steels C and D in Table I are such steels. These steels have been studied previously ;l,2,12 they differ only with respect to deoxidation practice; C was deoxidized with silicon while D, teemed from a portion of the same heat, was deoxidized with additional auantities of aluminum in the mold. C therefore is what is normally termed a "coarse-grained steel" and D is a, "fine-grained steel." These steels can be compared at the same grain size by heating c to a low temperature and heating D to an elevated temperature, producing a structure of austenite plus residual carbide in the former while forming homogeneous austenite in the latter; in such

Jan 1, 1943

By Louis A. Rosales, Kanji Ono

The anomalous behavior of hydrogen in iron is examined and a new model is proposed It is postulated that hydrogen single and di-interstitials are in equilibrium with each other. When the binding enthalpy of the di-interstitial, B, is assumed to be about 10 kcal per mole, the predicted temperature dependence of the solubility agrees reasonably well with the reported data. Effective diffusiuity is calculated assuming the di-interstitials to be immobile. Since the number of mobile single interstitials is greatly reduced at lower temperatures, the effective diffusivity is decreased. A good agreement in the temperature dependence of diffusivity between theory and experiment is provided with B - 10 kcal per mole. The predicted diffusivity is also a function of total concentration of hydrogen and this appears to be Partly responsible for the large scatter in the reported data. HYDROGEN is known to form an interstitial solid solution with iron.''' At elevated temperatures, it has been well-established that hydrogen enters iron in the dissociated form and occupies the interstices, and that diffusion of hydrogen in iron is via the interstitial mechanism. The concentration, c, permeability, P, and diffusivity, D, of hydrogen in iron have been separately determined and are consistent with each other under the steady-state condition for temperatures above approximately 400°C; that is, the relationship P = c-D holds. At lower temperatures, however, anomalous behavior of hydrogen in iron has been observed by many investigators. The results of experimental studies4-'' of the diffusion of hydrogen in iron are summarized in Fig. 1, in which the values of D are plotted against the reciprocal temperature. Although there is an increasing divergence in observed values of D with decreasing temperature, the values of D at temperatures below approximately 200°C are definitely small as compared with the extrapolation from high-temperature data. The lines shown bracket the region containing the most probable data. The observed values of c6," are plotted against the reciprocal temperature in Fig. 2, where the dashed lines represent Geller and sun's'' most probable isobars at 1 and 100 atm. At high external hydrogen pressure and low temperatures, the values of c observed are higher than those expected from high temperature data. It is generally accepted that certain trapping mechanism is responsible for the anomalies, but the nature of the trapping mechanism has not been clarified. Various types of hydrogen traps were suggested in the literature, such as "rifts" in the lattice dislocations, voids, microcracks, and so forth. However, no quantitative account of the observed behavior has been given in terms of these trapping mechanisms. Formation of methane in hydrogen-charged steel was found by ~odgurski." This appears to explain the existence of the so-called "residual" hydrogen,4 but not the observed anomalies of hydrogen in iron. McNabb and Foster' proposed a mathematical analysis in terms of a trapping mechanism. However, the physical significance of the traps was not clarified. The necessity of evaluating five parameters in their theory made comparison with experiment difficult. In the present paper, a model is proposed in which the anomalous behavior of hydrogen is attributed to the formation of hydrogen di-interstitials at lower temperatures. In this model, it is postulated that single and di-interstitials are in equilibrium with each other. (The hydrogen di-interstitial is to be distinguished from a hydrogen molecule which may exist in voids.) It can then be shown that most of the anomalies can be explained by assuming that the di-interstitials are virtually immobile and that the binding enthalpy of the di-interstitial, B, is approximately 10 kcal per mole. Predictions of the theory agree with the available experimental data reasonably well. THEORY The basic postulate of the present analysis is that single and di-interstitials are in equilibrium with each

Jan 1, 1969

By Mark J. Klein, A. H. Clauer

The Snoek peak induced by solute nitrogen in chromium was studied. A rapid quenching rate is required to maintain nitvogen in solution in sufficient concentrations to be detectable by internal-friction techniques. An expression for the tertninal solubility, c, of nitrogen in weight pevcent is log,,c = -4130/T + 1.05. The diffusion of nitrogen in zhromium determined by internal friction is SNOEK&apos;S theory1 of the stress-induced ordering of interstitial solute elements in the bcc lattice has been used to deduce information on the behavior of interstitials in a number of bcc metals. Under the proper conditions, internal-friction studies of "Snoek peaks" permit a determination of diffu-sivities, solubilities, and precipitation kinetics of interstitial elements. Internal-friction studies of this type have been reviewed by Nowick,&apos; Wert,= Powers and Doyle,4 and others. The behavior of interstitial atoms in Group V-A metals and iron has been rather extensively studied in this way, and results are reasonably self-consistent. However, the study of interstitial elements using internal friction in the Group VI-A metals—tungsten, molybdenum, and chromium—is much less clear. Thus far, internal-friction studies have revealed a peak in tungsten tentatively attributed to carbon5 and a peak in chromium associated with nitrogen. In chromium, Bungardt and Preisendanz6 observed a peak at 180°C for a frequency of -1 cps which they associated with nitrogen. More recently, de Morton7 determined the diffusivity of nitrogen in chromium from studies of a nitrogen peak at 160°c for a frequency of -1 cps and from elastic aftereffect measurements. The objective of this investigation was to study the nitrogen peak in greater detail, to obtain information on the behavior of nitrogen in chromium. This information is of interest because nitrogen is known to have an embrittling effect on chromium. However, efforts to deduce the role played by nitrogen in influencing the mechanical behavior of chromium are handicapped by lack of information on its behavior and distribution in chromium. EXPERIMENTAL PROCEDURES The chromium wires used in these studies were drawn from arc-melted iodide-chromium stock that had been extruded, swaged, and centerless-ground to 0.25 in.-diameter rods. Internal-friction measurements were made in an evacuated torsional pendulum similar to the one described by Kê,8 utilizing wires 0.048 to 0.030 in. in diameter. A series of analyses of the fabricated wires showed that the major impurities were approximately 100 ppm Fe and a combined interstitial content of 50 to 100 ppm C, O, N, and H. A typical interstitial analysis of the wires after processing is 15 ppm C, 2 ppm H, 50 ppm O, and < 5 ppm N. Interstitial concentrations were determined by vacuum-fusion, combustion-conductimetric, and micro-Kjeldahl analyses. In general, vacuum-fusion analysis yielded a lower nitrogen concentration than did micro-Kjeldahl analysis. For consistency, the nitrogen concentrations reported in this investigation were determined by the former method. Heat treatments were carried out by encapsulating the specimens in quartz tubes containing argon. The fabricated wires were annealed at 1150°C for 1 hr to produce uniform recrystallized grain size of about 0.015 mm. Nitrogen and carbon were added to the fabricated wires by encapsulating them in a quartz tube containing ammonia or methane, and annealing them at 1150°C for 48 hr. In some instances, carbon was also introduced by coating the wires with carbon black prior to annealing.

Jan 1, 1965

By Ernest M. Spokes, Martin A. Thieme

A simulation model developed to analyze scraper-pusher utilization in open pit mining systems is described. The mining simulator discussed was developed as a tool to aid management in evaluating alternative open pit haulage schemes and to reduce the risk involved in the selection of equipment.

Jan 1, 1973

By Kenyon E. Richard, James H. Courtright

SILVER Bell is situated 35 airline miles northwest of Tucson, Ariz., in a small, rugged range rising above the extensive alluvial plains of this desert region. Its geographical relation to other porphyry copper deposits of the Southwest is shown on the inset map in the lower left corner of Fig. 1. The climate is semi-arid. Altitudes range within 2000 and 4000 ft. Opening of the Boot mine, later known as the Mammoth, in 1865 was the first event of note in the district&apos;s history. Oxidized copper ores containing minor silver-lead values were mined from replacement deposits in garnetized limestone and treated in local smelters. Copper production had approached 45 million pounds by 1909 when the disseminated copper possibilities in igneous rocks were recognized. Extensive churn drill exploration carried out during the next three years resulted in partial de- lineation of two copper sulphide deposits, the Oxide and El Tiro. Although the then submarginal tenor discouraged exploitation of these disseminated deposits, selective mining of orebodies in the sedimentary rocks continued intermittently until 1930, providing a production total of about 100 million pounds of copper.

Jan 11, 1954

By W. C. Spence, Burt C. Mariacher

Methods employed to beneficiate ores utilize relatively few fundamental principles to effect size reduction and concentration. In crushing and grinding only impact and compressive forces with a minor amount of shear are employed. In concentration, gravity, magnetic, electrostatic and flotation constitute the major methods of concentration with minor use of sizing, hand picking and adhesion. This industry, as all others, can expect in the near future to see the development of new techniques for improved efficiency, cost reduction, and exploitation of raw materials hitherto considered unmanageable. NATURAL AND INDUCED RADIOACTIVITY At the Canadian Department of Mines in Ottawa in 1946, C. M. Lapointe developed a picker belt system whereby radioactive ores could be concentrated by electromechanical means. This invention ultimately led to development of what is now refer- red to as the Lapointe Picker and which has been used commercially at Port Radium and Port Hope for the upgrading of jig concentrates. Basically, the system consisted of conveying sized uranium ore on a belt under a radioactivity detection device which in turn electronically operated a kicker or plunger that separated the ore from the gangue constituents. Thus, a new principle for mineral concentration, radioactivity, was introduced commercially.

Jan 7, 1962

By Samuel S. Arentz, Dorsey A. Lyon

Introduction % •................. 789 The Present Sources of Zinc ..:.......... 791 Zinc Ores.................. 791 Lead-Zinc Ores................. 793 Loss oF Zinc at the Mine.............. 793 Present Method oF Extracting Zinc From Ores....... 795 Class oF Ores Suited to Zinc Retort Smelting....... 795 Concentration Processes Used for Treating Zinc Ores .... 795 Hydro-Mechanical Processes............. 795 Electro-Mechanical Processes............. 796 Flotation Processes............... 797 Losses of Zinc in Lead and Copper Blast-Furnace Smelting .. 798 Possible Future Sources oF Zinc Supply.......... 800 The Problem oF the Metallurgist and the Present Status of New Processes................. 801 Introduction A great deal of attention has recently been given to the metallurgy of zinc, and much of that which has been said and written on this subject has been in the nature of a criticism. For instance, we are quite accustomed to hearing it said that the metallurgy of zinc has stood still, that it is antiquahed, out of date, etc. We are, however, inclined to agree with George C. Stone1 when he says that, although there have been no such spectacular and radical changes as were worked in the metallurgy of copper and iron by the introduction of converters, there has nevertheless been a decided and marked progress in the metallurgy of zinc, and especially during recent years. However, it must be admitted that, due to the fact that the chemistry of zinc is so different from that of the other metals, the retort process is the only process by which zinc is produced commercially; and, moreover, that losses which occur in the zinc industry— that is, in the mining, milling, and smelting of zinc ore—are very great, for it is stated2 that probably less than 50 per cent. of the zinc mined, even

Jan 1, 1915

By M. Bevis, A. G. Crocker

A. G. Crocker and M. Bevis (Battersea College of Technology)— Richman and Richman and conard17 have recently published the very interesting results of their studies on the plastic deformation of Fe-Ni-C martensites and of an Fe-5 wt pct Be alloy. Other work on the range of Fe-Be alloys containing between 16 and 27 at. pct Be has also been reported by Richman." One of the fascinating features of this work is that the materials investigated deform primarily by means of twinning and that several twinning modes are operative in addition to the well-established (112 ) mode of bcc materials The composition planes of these unusual twins were determined using a single-surface analysis and reported as (0131, "{045)" or "{089)", and It is now thought1&apos; that the "{0,1,13)" habit reported for the Fe-Ni-C alloys&apos;&apos; is more likely to be near "{127)". Although the full twinning elements of these unusual twinning modes could not be determined directly from the experimental results, the authors attempt to deduce the elements by considering twin intersectionslQ and by using the projection technique of Jaswon and Dove. The basic assumption of their approach is that the (013) habits are truly rational planes but that the other habits are irrational and merely approximated to by the indices quoted above. They thus deduce that the twinning mode describing the (013) habit is either Type I or compound and that the modes describing the other habits are Type 11. This deduction must however be false as all twinning modes in cubic structures obeying the classical orientation relationships of deformation twinning must be compound. Type-I and Type-I1 modes can occur in all of the other crystal systems (indeed in the triclinic system compound modes are not allowed), but in the cubic system only compound modes can arise. This fact, which does not appear to be well-known, fol- lows immediately from the relations between the four twinning elements defining a twinning mode. Thus for a Type-I mode which is uniquely defined by the rational twinning elements K1 = hi and given by: where the summation convention of the tensor calculus has been adopted. For cubic materials the metrics and reduce to the unit tensors and j so that we have It is clear from these equations that both ki and ui must take on integral values; i.e., Kz, and ql must be rational, if hi and vi are integers, i.e., if K1 and are rational. Thus for cubic materials a Type-I mode must degenerate into a compound mode and the same result also arises for Type-II modes. The apparently irrational habits observed by the authors can thus not be explained in terms of Type-I1 twinning if the classical laws of deformation twinning are to be obeyed. An alternative explanation of the irrational habits is that they may arise from twinning modes with four irrational twinning elements. These modes, which do not obey the classical orientation relationships associated with deformation twinning, have been shown to arise as the result of double twinning processes in magnesium,22 but may also describe a simple shear on an irrational plane in an irrational direction. Indeed double twinning processes in bcc

Jan 1, 1963

By M. Bevis, A. G. Crocker

A. G. Crocker and M. Bevis (Battersea College of Technology)— Richman and Richman and conard17 have recently published the very interesting results of their studies on the plastic deformation of Fe-Ni-C martensites and of an Fe-5 wt pct Be alloy. Other work on the range of Fe-Be alloys containing between 16 and 27 at. pct Be has also been reported by Richman." One of the fascinating features of this work is that the materials investigated deform primarily by means of twinning and that several twinning modes are operative in addition to the well-established (112 ) mode of bcc materials The composition planes of these unusual twins were determined using a single-surface analysis and reported as (0131, "{045)" or "{089)", and "{2,3,10)" or "(127)". (It is now thought1&apos; that the "{0,1,13)" habit reported for the Fe-Ni-C alloys&apos;&apos; is more likely to be near "{127)". Although the full twinning elements of these unusual twinning modes could not be determined directly from the experimental results, the authors attempt to deduce the elements by considering twin intersectionslQ and by using the projection technique of Jaswon and Dove.&apos; The basic assumption of their approach is that the (013) habits are truly rational planes but that the other habits are irrational and merely approximated to by the indices quoted above. They thus deduce that the twinning mode describing the (013) habit is either Type I or compound and that the modes describing the other habits are Type 11. This deduction must however be false as all twinning modes in cubic structures obeying the classical orientation relationships of deformation twinning must be compound. Type-I and Type-I1 modes can occur in all of the other crystal systems (indeed in the triclinic system compound modes are not allowed), but in the cubic system only compound modes can arise. This fact, which does not appear to be well-known, fol- lows immediately from the relations between the four twinning elements defining a twinning mode. Thus for a Type-I mode which is uniquely defined by the rational twinning elements K1 = hi and tj2 = vi (i = 1, 2, 3), the Kz qd 771 elements are given by: where the summation convention of the tensor calculus has been adopted. For cubic materials the metrics cij Iand cij reduce to the unit tensors 6ij and 6ij so that we have It is clear from these equations that both ki and ui must take on integral values; i.e., Kz, and ql must be rational, if hi and vi are integers, i.e., if K1 and 77~ are rational. Thus for cubic materials a Type-I mode must degenerate into a compound mode and the same result also arises for Type-II modes. The apparently irrational habits observed by the authors can thus not be explained in terms of Type-I1 twinning if the classical laws of deformation twinning are to be obeyed. An alternative explanation of the irrational habits is that they may arise from twinning modes with four irrational twinning elements. These modes, which do not obey the classical orientation relationships associated with deformation twinning, have been shown to arise as the result of double twinning processes in magnesium,22 but may also describe a simple shear on an irrational plane in an irrational direction. Indeed double twinning processes in bcc

Jan 1, 1963