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By Eugene Guccione

It would be extremely difficult and unfair to compare the United States to Australia when wondering about which of the two countries offers the best opportunities for running a mining operation. However, if somebody would ask "Where is the best place to mine outside the US?"-I'd answer without reservations: Australia. Some of my Australian mining friends will disagree with me for my giving their country such a high rating. And they'll probably accuse me of being an optimist by telling me, as one of them did, that "the difference between an optimist and a pessimist is that the pessimist is better informed."

Jan 1, 1977

By J. D. Ridge

The geologic setting and mineral relationships of seven European massive sulfide deposits that more or less conform to the bedding of the largely noncal-careous sedimentary rocks and/or bedded volcanics in which they are found are considered here. These orebodies consist largely of massive beds or lenses of sulfides usually surrounded by halos of disseminated sulfides and distorted by tectonic activity. The formations containing these deposits have been metamorphosed in varying degrees at times subsequent to their lithification. The ore-forming process is thought to be essentially volcanic, with the ore constituents being brought to the shallow-water site of deposition through tectonic fissures from magma chambers at depth as gases or relatively concentrated hydrother-mal solutions. Certain European ore deposits of base metal sulfide have previously been considered to be of hydro-thermal or magmatic origin, but today a number of European mining geologists consider them to be syngenetically produced. In an effort to provide American geologists with some idea of the reasons behind this change in thought, the geological settings of seven of these deposits have been studied. These are: Ldkken, Meggen, Rammelsberg, Ergani-Maden, Outokumpu, Boliden and Roros. These deposits lie in bedded rocks that have undergone metamorphism from causes not universally agreed upon; most of the formations were originally shales, and may have been intercalated with limey and occasionally quartzitic beds, volcanic tuff, agglomerate, extrusive lavas and usually basic intrusives. Deposits of the conformable type, however, are not confined to these rock types but may be in calcareous and associated igneous rocks or almost entirely in volcanics. These deposits may be closely associated in space with igneous rocks that, again, are usually basic types. Although the ages of the enclosing rocks range from mid-Precambrian (Boliden and Outokumpu) to Eocene (Ergani-Maden), the bulk of them are Paleozoic, with two (Meggen, and eammelsberg) being upper middle Devonian and two (LØkken and RØros) being Cambro-Ordovician. Geographically, two are in West Germany, four in Scandanavia and one in Turkey. Of the seven deposits, six are mined for copper, with three of these also producing zinc, and two lead; one is mined for zinc and minor lead. In the discussions of the seven conformable deposits that follow, I have attempted to present as uniform a treatment as their varying characters will permit. For each deposit, I have considered the stratigraphy of the area, its major structural characteristics, the form of the orebodies, their mineral content, and the origin of the ore. In the last of these subdivisions, I have presented only the viewpoint of those who believe the ores to have been formed by syngenetic processes, processes that went on at the same time as those which produced the beds that enclose the ores but that are not, in the deposits in question, thought to have been sedimentary in the strict sense of the term. The materials of which these orebodies are composed, it is suggested, did actually collect by falling through sea water to the floor of that portion of the sea in which they accumulated. The ore constituents, however, are believed by a considerable number of European geologists to have been added to the sea water from intratelluric sources, probably igneous magma chambers, as exhalations — hydrothermal solutions or volcanic gases. The effect of the encounter with sea water on these ejected gases or water-rich vapors was to precipitate their potentially solid constituents with great rapidity; they were deposited so quickly, in fact, that the amounj of normally accumulated mechanical or chemical sediment deposited over the same period of time was essentially negligible. The ores formed in this manner, however, are generally interbedded with normal sediments or with lava flows, or with any combination of these two types of rock-forming materials. Such departures as these deposits may have from their original mineral content and attitude are thought to be directly related to the degree of dynamic or static metamorphism that they may have undergone after their accumulation. I have not attempted here to present alternate hypotheses to that of so-called exhalative sedimentation although, of course, such exist and, in my

Jan 1, 1963

By J. E. Pogue, F. G. Coqueron

This paper describes the sources of funds required by the petroleum industry to finance capital expenditures and also presents a discussion of the effect of rising construction costs on these expenditures. The petroleum industry obtains its capital funds from several sources: (I) internal, from retained cash earnings; and (2) external, from borrowings and the sale of securities to the public. The upward trend of capital expenditures of the petroleum industry is caused in the main by the influence of two powerful factors: (I) the physical growth in the demand for oils; and (2) the rising cost of drilling wells and constructing refineries, pipe lines, and other facilities. The segregation of these factors is accomplished by deflating the actual capital expenditures so that they are shown in terms of 1939 costs and then subtracting the adjusted series from the actual figures to yield a set of data representing the expenditures made on account of higher costs. Rising costs affect prices and the portion attributable to this factor had to be generated from the cash earnings of the industry, which called for higher oil prices. Introduction Capital may be defined as "wealth employed in or available for production." All production requires capital. Expanding industries require more capital than static ones, and technological industries employ more capital than. those in which little equipment is needed. The petroleum industry is both rapidly growing and highly technological, and, being a large industry, its capital requirements are prodigious, amounting to about one-seventh of the total of all American business, excluding agriculture.* Capital formation may be defined as the method by which the wealth or capital needed in the productive processes is created. There are various ways in which capital funds may be obtained but there is only one way in which capital can be created—out of production in excess of consumption, that is, savings. The physical realities are simple, but the monetary concepts are complicated because the mechanism of credit can draw upon future savings. Source of Capital Funds An industry, such as the petroleum industry, can obtain its capital funds from

Jan 1, 1949

By Robert H. Merrill, David W. Wisecarver, Raymond M. Stateham

The US. Bureau of Mines, in cooperation with US. Borax and Chemical Corp. and Kennecott Copper Corp., has investigated the use of the microseismic method to evaluate the stability of large, open-pit slope walls. The method is based on the phenomenon that stressed rock normally emits subaudible rock noises, and the number of rock noises per unit time (noise rate) and the magnitude of the rock noises (amplitude) increase as the stresses in the rock approach the failure stress of the rock. Therefore, the detection and recording of those rock noises serve as a semiquantitative method of predicting the incipient failure of rock. This report briefly describes the three different types of micro-seismic apparatus, the procedures, and the results of microseismic investigations in the slope walls of the Boron mine near Boron, CaL, and the Kimbley, Liberty, and Tripp-Veteran open-pit mines near Ely, Nev. Microseismic monitoring within a frequency band of SO to 5000 Hz indicates noise rates in stable, inactive mining areas are between 0 and 10 noises per hour; the rates in stable, active mining areas are between 10 and 50 noises per hour; and the rate in unstable areas is as high as 2500 noises per hour. High microseismic noise rates in the Liberty pit correlate with the time of nearby earthquakes, indicating that the earthquakes affected the slope wall. The results provide evidence that the microseismic technique is applicable to large pit walls, and that the wide-band, wide-range microseismic equipment appears to be suitable for open-pit investigations. The microseismic method is based on the phenomenon that stressed rock normally emits subaudible rock noises, and the number of rock noises per unit time (noise rate) and the magnitude of the rock noises (amplitude) increase as the stresses in the rock approach the failure stress of the rock. Therefore, the detection and recording of those rock noises serve as a semiquantitative method of predicting the incipient failure of rock. The method has been used for many years to detect incipient failure in roofs or pillars in underground mines. In 1963 the U.S. Bureau of Mines (USBM) started an investigation of the microseismic method in large, open-pit slope walls. The purpose of this investigation was to evaluate the method in open-pit slopes where the rock may be fractured and broken and where the size of the rock mass under investigation is much larger than normally encountered underground. In addition, both the stresses in the rock and the strength of rock near pits are lower than usually found underground. Consequently, there was some doubt concerning the feasibility of the method for open pits, and the economics of such an investigation may have been prohibitive especially if large walls had to be monitored with closely spaced geophones. The successful application of the microseismic method to underground operations has improved safety at little, or no sacrifice, to production or extraction ratios. The anticipated reward in open-pit mining would be the improvement of safety with a minimum sacrifice to mining operations. There is also a possibility that the method could be used to optimize the unloading (stripping) of potential failure areas by the removal of intact rock from the slope wall rather than the cleanup of a slide from the bottom of the pit. This report contains a brief description of three types of microseismic apparatus used in four different pit walls, each of which is different in height, slope, rock types, or has different planes of weaknesses, such as faults, fractures, or joints. Because the geologic features of the pit walls are varied and complex, for brevity, this report dwells mostly on the microseismic apparatus, techniques, the rock noise rates, and the slope movements measured at the various sites. PROGRESS AND DEVELOPMENT The microseismic method was developed over 20 years ago; and the method and examples of investigations in underground mines are summarized by Obert and Duvall. 1 In more recent years, the method has been applied in several underground mines, and an in-situ test under controlled stress conditions is described by Morgan and Merrill. 2 Experience has shown that, on occasions, the microseismic noise rate and amplitude reach a peak value and then start to decrease before a failure occurs in an underground mine; on other occasions, the noise rate steadily increases to a maximum at failure. The method has been applied to slopes by Goodman and Blake,3 and by Paulsen. 4 Goodman and Blake found that the noises corresponded with failures in the slope

Jan 1, 1970

By J. J. Pye, J. B. Drew

The surface-diffusion coefficients of Ni63 diffusing on low-index planes of nickel single crystals have been measured over the temperature range from 400° to 1000°C using a precision autoradio-gvaphic technique. The activation energy for sur -face diffusion appears to he the same on the {111}, {110), and (100) planes and amounts to -0.60 ev. This is in good agreement with the value (-0.62 ev) reported for (111) planes obtained by mass-transport techniques. In an earlier paper, the authors have reported self surface-diffusion coefficients on silver.' In that work, a deviation of the diffusion coefficients from linearity in the Arrhenius plot was observed at high temperatures. This effect was attributed to a loss of tracer atoms into the bulk by volume diffusion. The purpose of the present work was to extend the technique developed to the nickel surface-diffusion system up to the point where volume diffusion would come into play. The nickel system especially lends itself to this technique due to the high efficiency of the isotope in darkening the film and the large absorption of the weak radiation (0.063 mev /3- particle of the trapped tracer atoms. The diffusion coefficients and ictivation energy for different orientations on nickel can also be compared with a report published by Blakely and Mykura 2 where a mass-transfer technique was used. This paper reports the self surface diffusion of nickel on the low-index planes over a wide temperature range using a precision autoradiographic technique. EXPERIMENTAL PROCEDURE The experiment is similar to that described in the earlier publication consisting of a radioactive needle as a source resting on a flat, smooth, chemically polished surface annealed in a dynamic dry-hydrogen atmosphere. The needle is held snugly on the surface by a holder fabricated from commercially pure nickel. The point source is made by grinding down a small-diameter nickel rod until a tip of approximately 0.1 mm radius is formed. It is then etched and the needle tip plated with the radioactive isotope Ni63. Nickel single crystals were used whose main impurities were spectrographically determined as Co 0.05, Fe 0.007, C 0.005, and S 0.003 pct. The surfaces, oriented to within 1/2 deg of the low-index planes, were carefully mechanically polished and etched in a 50-30-10-10 hot solution of acetic, nitric, sulfuric, and phosphoric acids giving a smooth polished surface. The crystals were then washed in distilled water and alcohol. Annealing temperatures ranged from 400° to 1000°C with a furnace arrangement in which the crystals could be brought up to temperature in times short compared to diffusing times. The temperature was maintained constant to ±10°C. In the temperature range investigated, the ratio of the surface-diffusion coefficient to the volume-diffusion coefficient (Ds/Du) was 105 or more and the mean bulk-penetration values, calculated from literature values of volume-diffusion coefficients,3 were on the order of 10-5 cm. After the diffusion anneal, the sintered needle is removed, and both the radius of the needle point and spot left on the crystal face are measured. The crystal is then placed on photographic film. Diffusion profiles are obtained by scanning the film with a recording microdensitometer which has a slit width of 10µ. DISCUSSION AND RESULTS The experimental conditions are such that the source strength and needle radius are essentially constant and the time is adjusted such that the mean bulk penetration is small. An exactly analogous heat-flow problem has been considered by Carslaw and Jaeger4 and the solution can be written in integral form as:

Jan 1, 1964

Jan 1, 1885

By W. C. Leslie, R. M. Fisher, K. G. Carroll

A nitride, believed to be Si3N, has been separated from three nitrided silicon steels. Germanium nitride, Ge3N4, has been prepared from pure germanium. Comparison of the diffraction patterns indicates that the two nitrides are isomorphous; on orthorhombic structure is suggested in place of the rhombohedral structure previously reported for Ge3N4. THE possibility that a nitride of silicon may, under appropriate conditions, precipitate in silicon steels or in steels killed with silicon makes it desirable to have some positive means of identifying such a compound. One such means is the X-ray or electron diffraction pattern of the nitride. A review of the meager data in the literature indicates that the nitride most likely to form is Si3N4, a conclusion supported by the results of a study of nitrided silicon steels to be published shortly by L. S. Darken and R. P. Smith, of this Laboratory. Unfortunately, there is available no diffraction pattern for this nitride. Data have been reported, however, for Ge3N4 which, judging from the similarity between germanium and silicon, might be expected to be isomorphous with Si3N4. An effort was made, therefore, to form such a silicon nitride, to determine its composition and diffraction pattern and, if possible, its structure. To this end a series of three silicon steels was nitrided under controlled conditions with the resultant formation of nitride particles which yielded an electron diffraction pattern in situ. The particles were then extracted from the steel and an attempt was made to determine their chemical composition. X-ray and electron diffraction patterns were also obtained from the extracted particles, which indicate that the nitride is isomorphous with Ge3N4, although a complete determination of the structure has not been possible. These results show that a silicon nitride with a well-defined diffraction pattern can form in silicon steels, and they suggest that this nitride is Si3N4. Materials and Procedures The sillicon steels investigated were In the form of thin sheet or strip and had the composition shown in Table I. The 0.58 and 1.21 pct Si steels were nitrided by holding them at 1110°F in an H2-NH3 atmosphere containing 3 pct ammonia for 48 hr. The nitride particle size was increased by subsequent heating at 1500°F for 13 1/2 hr in helium. The resulting microstructure is shown in Fig. 1. The steel containing 3.20 pct Si was nitrided at 1200°F for 16 1/2 hr after which it was held in helium at 1500°F for 4 hr. Its structure as seen under the electron microscope is illustrated by Fig. 2. As would be expected from the higher silicon content and the shorter holding time at 1500 °F, the nitride particles are smaller and more numerous than those in the 1.21 pct Si steel. The ammonia-hydrogen treatment reduced the carbon content of the steels to a very low level, so no interference was encountered from carbon or carbides. In the case of the 3.2 pct Si steel, the carbon was reduced to 0.003 pct before nitriding by heating in dry hydrogen. Attempts to obtain an X-ray diffraction pattern from polished and etched surfaces of the 1.21 and the 3.20 pct Si steels were unsuccessful. However, an electron diffraction pattern was obtained from the surface of the steels. The interplanar spacings obtained from these patterns arc shown in Table 11, col. 5. The nitride particles were then extracted from all three steels by dissolving the ferrite matrix in bromine-methyl acetate, the solution used in the Beeghly method for the extraction of aluminum nitride from steel. X-ray diffraction patterns of these residues, obtained by means of a spectrometer and by a 57 mm Debye-Scherrer powder camera using filtered cobalt or chromium radiation, are given in Table II along with the pattern obtained by

Jan 1, 1953

By T. Sterry Hunt

Jan 1, 1884

By A. B. Kinzel

IT is with sincere appreciation and a deep sense of responsibility that I accept the honor of delivering the Howe Memorial Lecture. In our time metallurgical research has delved into phenomena ever more complex in character, so that much of this work must be done by organized teams. We, of the Union Carbide and Carbon Research Laboratories and the Electro Metallurgical Co., are truly a team and the lecture which is to follow is due largely to a few of the outstanding members of that team here cited and well known to you in their own right: John Lamont, whose work deserves special recognition, Walter Crafts, William Forgeng, William Binder, Robert Fowler, and David Swan. Thus it is a fitting pleasure to accept this honor for the research institution which I represent. Henry Marion Howe was truly inspirational and his breadth of view was such that he could use either the method of rigid proof or implied mechanism to further the broad understanding. But perhaps his outstanding characteristic was his sound judgment and his ability to weigh observations. The following is replete with observations and judgment as to their implication. We would like to feel that it is the type of dissertation which Howe, himself, would have enjoyed. Chromium carbides in stainless steel have, in a sense, been a key to the progress of the stainless steel industry. Brearley's first stainless steel, containing approximately 0.30 pct C, was successful because it differed from previous Fe-Cr alloys in that the carbides were present in such amount and form as to provide the stainless and cutting properties. Again, the 12 pct Cr die steels with a carbon content of 1.5 pct or more achieved their properties by virtue of the form and distribution of the chromium carbides. In the straight chromium steels with from 12 to 25 pct Cr, chromium carbide amount and distribution are once more the determinants with respect to physical properties and corrosion resistance. In each of the cases just cited the role of the carbide is in essence similar to that of iron carbide in carbon steel and this story is so well known that we need not dwell on it. In the austenitic stainless steels, the chromium carbide plays only a minor positive role with respect to mechanical properties, and for corrosion resistance the objective is to achieve maximum homogeneity. Thus the tendency has been to ever lower the carbon and correlatively the chromium carbide content of the austenitic steels. Today stainless steels with carbon less than 0.03 pct are beginning to find their true place, and this is being aided in major degree by our Company's introduction of a new type of ferrochromium having negligible carbon. The role of carbon in these austenitic steels has long been recognized, and a truly enormous amount of research has been devoted to the subject. Much has been learned about corrosion resistance, but the attack on the problem from the point of view of carbide precipitation and the nature thereof has left much to be understood. Because of its fundamental importance to the future of stainless steels, further study of the mechanism of carbide formation in austenitic steels is of interest. In the 18-8 Cr-Ni steels, which are typical of the austenitic class of steel, carbon is soluble in the aus-tenite to the extent of approximately 0.15 pct at 1832°F (1000°C). The solubility becomes less with decreasing temperature, so that at 1652°F (900°C) the solubility limit is approximately 0.06 pct, at 1472°F (800°C) it is about 0.03 pct, and at 932°F (500°C) it is approximately 0.01 pct. Obviously this is the ideal situation for the classical precipitation phenomenon. It is true that, in a sense, 18-8 austenite resulting from annealing is in a metastable state, and the phenomenon of ferritic precipitation from this austenite should be considered. However, in a so-called fully austenitic 18-8 steel this is secondary with respect to the carbides and can be neglected. A wide variety of chromium carbides is known. Only one chromium carbide, Cr,,C,,, frequently referred to as Cr,C, has been found in unmodified low carbon 18-8 steel. This, fortunately, simplifies the study of the precipitation phenomena. For this study an A.I.S.I. type 304 stainless steel of commercial quality was selected. Analysis showed C 0.07 pct, Mn 0.49 pct, Si 0.33 pct, Ni 9.34 pct, Cr 18.91 pct, and N 0.033 pct. As expected with this composition the steel was homogeneous after annealing except for a few pools of ferrite, which were disregarded in that their location was not coincident with subsequent carbide precipitation areas. On corrosion testing the steel was normal and typical of good commercial quality. Specimens 1/2xlx4 in. were annealed and subjected to precipitation heat treatment for 100 hr at 100" temperature intervals from 1000° to 1500°F and for ten selected intervals ranging from 5 min to 64 hr at 1300°F. These blocks were then cut into small pieces for metallographic studies. The first problem

Jan 1, 1953

By H. C. Chang, N. J. Grant

Creep of very coarse grained high purity aluminum was studied at 400°, 700°, and 1100°F at initial stresses of 50 to 1200 psi. Local strain measurements were made across the grain boundaries and in different regions of various grains during creep, thereby permitting the drawing of component creep curves. The relative amounts of elongation as measured across a grain boundary and in the grains adjacent to the boundary depend on the temperature of testing. The significance of creep curve equations and activation energies is discussed. THIS paper presents some of the results of a research program devoted to the study of the mechanism of creep in high purity aluminum. Previous publications have dealt with the cyclic processes of alternating grain boundary sliding and migration, and the deformation in the grains caused by these processes;' the direction and the driving force of grain boundary sliding and migration;' the deformation in the grains and the restricting effects of the grain boundaries on this deformation." These previous papers were based mainly on either microscopic observations or X-ray data, or both. Sometimes creep curves across two closely spaced reference marks (about 0.6 to 0.7 mm apart) were also presented with a view to correlating the elongation values with the optical observations in general, and with certain deformation processes in particular. These curves shall henceforth be referred to as component creep curves. No attempts were made, however, to compare either the component creep curves which were obtained in different regions of a specimen, or those obtained from different specimens subjected to different creep test conditions. It is the purpose of this paper to present these component creep curves. Among the factors influencing the behaviors of these curves, those studied were stress, temperature, and grain arrangements in the specimens. It is proposed to show how greatly the deformation can vary from grain to grain and within an individual grain in a coarse grained specimen. The experimental technique and procedure have been presented.' It remains necessary to emphasize that the reference marks were produced by pressing a thin sewing needle into the surface of the specimen before the final annealing at 900°F for 24 hr and at 1150°F for 12 hr. The cold work around the needle indentations was therefore removed. The depth of these holes after electropolishing the annealed specimens was about 0.01 mm. This depth and area were negligible in comparison with the thickness of the specimens, 2.3 mm, and hence would not affect the creep behavior. Results Fig. 1 shows a development diagram of specimen P-8. The dots on the surface locate the needle point reference marks used to obtain the component creep curves. A curve obtained between two dots across a grain boundary measures not only the boundary deformation but also the deformation associated with boundary sliding occurring in the grains in the region between these indents. The original distance between two reference marks was about 0.6 to 0.7 mm. The maximum error of measurement was 0.01 mm, or in terms of percentage elongation, of the order of & 1.5 pct. Whereas the component creep curves shown in the figures to follow were drawn as a gross average of the points, in view of the fineness of some of the steps of grain boundary sliding and migration, as shown in the previous publications,¹,2 it appears logical to expect that some of the finer cycles of movement have not been delineated for the strain sensitivity of the measuring system. It seems justifiable to say that the curves are not as smooth as shown. 700°F Tests: Fig. 2 shows component creep curves across four of the grain boundaries in specimen P-8, tested at 700°F and 85 psi. These curves clearly show alternate cycles of increasing and decreasing

Jan 1, 1954

By L. F. Tedsen, A. E. Flanigan, J. E. Dorn

SINCE aluminum-alloy sheet may be used occasionally at moderately elevated temperatures, the effects of temperature en the mechanical properties are of interest. Recently the short-time tensile properties of several high-strength materials have been studied at temperatures up to 375°F. This paper deals with stress-rupture and [ ] creep properties at the same temperatures. The work was done at the University of California as a portion of the project NRC-548. It was financed by the War Production Board and was supervised by the Office of Production Research and Development. This paper has been released for publication by the latter agency. The following materials were studied, all in the form of 0.040-in. sheet: Alclad 24S-T Alclad 24S-T8I Alclad 24S-T86 Alclad 75S-T R301-T (clad) [ ] Specimens were loaded in tension in the cross-grain direction. Testing temperatures included 94°F., 211°F., 300°F., and 375°F. Stress levels were selected to cause rupture in times ranging from several minutes to boo hr. In each test the following data were obtained: (I) fracture time, (2) elongation at fracture, (3) the complete strain-versus-time curve (creep curve), (4) creep rate (defined in a later section). MATERIALS Materials for specimens were obtained from the manufacturers' commercial

Jan 1, 1946

By Tedsen L. F., Dorn J. E., A. E. Flanigan

since aluminum-alloy sheet may be used occasionally at moderately elevated ternperatures, the effects of temperature on the mechanical properties are of interest. Recently the short-time tensile properties of several high-strength materials have been studied at temperatures up to 3750°F.l This paper deals with stress-rupture and creep properties at the same temperatures. The work was done at the University of California as a portion of the project NRC-548. It was financed by the War Production Board and was supervised by the Office of Production Research and Development. This paper has been released for publication by the latter agency. The following materials were studied, all in the form of 0.040-in. sheet: Alclad 24s-T Alclad 24s-T8I Alclad 24s-T86 Alclad 75s-T R3oI-T (clad) Specimens were loaded in tension in the cross-grain direction. Testing temperatures included 94°F., 2II°F., 300°F., and 375°F. Stress levels were selected to cause rupture in times ranging from several minutes to 1000 hr. In each test the following data were obtained: (I) fracture time, (2) elongation at fracture, (3) the complete strain-versus-time curve (creep curve), (4) creep rate (defined in a later section). Materials Materials for specimens were obtained from the manufacturers' commercial

Jan 1, 1947

By Tedsen L. F., Dorn J. E., A. E. Flanigan

since aluminum-alloy sheet may be used occasionally at moderately elevated ternperatures, the effects of temperature on the mechanical properties are of interest. Recently the short-time tensile properties of several high-strength materials have been studied at temperatures up to 3750°F.l This paper deals with stress-rupture and creep properties at the same temperatures. The work was done at the University of California as a portion of the project NRC-548. It was financed by the War Production Board and was supervised by the Office of Production Research and Development. This paper has been released for publication by the latter agency. The following materials were studied, all in the form of 0.040-in. sheet: Alclad 24s-T Alclad 24s-T8I Alclad 24s-T86 Alclad 75s-T R3oI-T (clad) Specimens were loaded in tension in the cross-grain direction. Testing temperatures included 94°F., 2II°F., 300°F., and 375°F. Stress levels were selected to cause rupture in times ranging from several minutes to 1000 hr. In each test the following data were obtained: (I) fracture time, (2) elongation at fracture, (3) the complete strain-versus-time curve (creep curve), (4) creep rate (defined in a later section). Materials Materials for specimens were obtained from the manufacturers' commercial

Jan 1, 1947

By Walter Harvey Weed

The Republic of Mexico is traversed by many mountain ranges, and presents a great diversity of climates, soils and geographical features, yet its grander geographic provinces are few and peculiarly well defined. The Gulf plain, the Cen tral plateau, the Sierra Madre, and the lowland or Tierra Cali ente of the western coast are the main features of the geogra phy of the Republic, and in the northern half these provinces are particularly well defined. The Sierra Madre separates the Republic into eastern and western parts, and from the City of Mexico north to the Texas line presents an almost impassable barrier to east and west travel. On the north, the first wagon road pass from east to west is at El Paso del Norte, the site of the Texan city of El Paso. Southward for many hundreds of miles the Sierra Madre, traversed by well-worn trails, over which all travel from the west coast to the interior must pass, is a stupendous barrier to social and commercial intercourse. The Sierra Madre is commonly described as a range or con geries of mountain ranges. In fact, it is, in Chihuahua at least, a great plateau, fringed by mountains on the east, trenched by deep canons in its center, and bordered by a wild and rugged complex of mountains carved out of the plateau on the west. Professional duties took me across this region from Parral westward to the Gulf of California via Guadalupe y Calvo. As it includes some of the great ore-deposits of Mexico, and its geological features have never, so far as I am aware, been described, I have prepared a diagrammatic section made from my observations on a horseback trip across the Sierra, and added such notes as seem to be of general interest.

Jan 1, 1902

By L. I. Cothern

The introduction of mechanized mining has created a demand for long working faces. It has also prompted mining men to contest the old theory that longwall methods can be used only where roof conditions are ideal and where pack-wall material is plentiful. "Longwall" as used in this paper means "modified longwall," "semi-longwall," or any of the various ''wall" or "long-face" methods of mining. Many mines are now using long conveyor faces that differ only in their methods of development, types of roof support and method of loading coal onto the conveyor. Some types of longwall operations are being carried on successfully under conditions heretofore considered impossible by men experienced in longwall mining. With possibly one or two exceptions, long-face methods in Alabama are a direct result of the need for lower mining costs. The advantages over room-and-pillar systems were clearly expressed in an article by Messrs. Fies and Lacy of the DeBardeleben Coal Corporation1 as follows: (1) increased tonnage per miner; (2) increased percentage of lump coal; (3) reduction in cost of development; (4) elimination of the cost of room yardage; (5) reduction in the cost of haulage, from ability to use larger cars; (6) reduction in the cost of machine cutting; (7) reduction in cost for tracks; (8) reduction in the cost of deadwork; (9) reduction in the cost of supervision. An attempt on the part of the operator to gain these advantages by changing from room-and-pillar to longwall requires considerable courage, and credit should be given to those men who have done their bit to meet the competition of rival fuels. The initiatory problems to be solved are in reference to: (1) retreating or advancing system, (2) length of wall, (3) method of roof support, (4) method of entry development, (5) type of conveyor or loader, (6) hand vs. machine loading (onto conveyors), (7) hand vs. machine loading in entries, (8) control of roof pressure,

Jan 1, 1940

By L. I. Cothern

The introduction of mechanized mining has created a demand for long working faces. It has also prompted mining men to contest the old theory that longwall methods can be used only where roof conditions are ideal and where pack-wall material is plentiful. "Longwall" as used in this paper means "modified longwall," "semi-longwall," or any of the various ''wall" or "long-face" methods of mining. Many mines are now using long conveyor faces that differ only in their methods of development, types of roof support and method of loading coal onto the conveyor. Some types of longwall operations are being carried on successfully under conditions heretofore considered impossible by men experienced in longwall mining. With possibly one or two exceptions, long-face methods in Alabama are a direct result of the need for lower mining costs. The advantages over room-and-pillar systems were clearly expressed in an article by Messrs. Fies and Lacy of the DeBardeleben Coal Corporation1 as follows: (1) increased tonnage per miner; (2) increased percentage of lump coal; (3) reduction in cost of development; (4) elimination of the cost of room yardage; (5) reduction in the cost of haulage, from ability to use larger cars; (6) reduction in the cost of machine cutting; (7) reduction in cost for tracks; (8) reduction in the cost of deadwork; (9) reduction in the cost of supervision. An attempt on the part of the operator to gain these advantages by changing from room-and-pillar to longwall requires considerable courage, and credit should be given to those men who have done their bit to meet the competition of rival fuels. The initiatory problems to be solved are in reference to: (1) retreating or advancing system, (2) length of wall, (3) method of roof support, (4) method of entry development, (5) type of conveyor or loader, (6) hand vs. machine loading (onto conveyors), (7) hand vs. machine loading in entries, (8) control of roof pressure,

Jan 1, 1940

By Pierre R. Hines

The first progress in American ore dressing practice was made in the mills of the Mother Lode in Calif., the Comstock Lode in Nev., and Gilpin County in Colo., during the years 1861 to 1870, when the ancient wooden stamp battery, with square wooden stems, was converted into the 'California' stamp made of wrought and cast iron, with round stems which rotated. Eli Whitney Blake invented the jaw crusher in 1858 for stone crushing, and it was soon used for crushing ore. F. W. Gates' gyratory crusher followed twenty years later. S. R. Krom, Thomas A. Edison, and others improved the Cornish rolls by increasing their size and spring pressures; the Symons Brothers made horizontal and vertical disc crushers; W. Ball and E. T. Leavitt designed powerful steam stamps for Lake Superior native copper ores; and jigs were mechanized. William B. Frue, a mill superintendent in the Lake Superior copper district, invented the vanner in 1874. Arthur F. Wilfley built his riffled concentrating table in 1895, just after Dr. Robert H. Richards commenced his Ore Dressing. The Wilfley table so changed concentrator flow sheets that Dr. Richards was compelled to revise his text, and its publication was delayed until 1903. The value of sizing or classifying before concentration was recognized. Dr. Richards had persuaded the Anaconda Copper Mining Co. to install round tables with special surfaces to catch the 'extremely fine free mineral.'l Gravity concentration had achieved almost every refinement for recovering or separating minerals by the difference in their specific gravities. However, one serious problem remained unsolved, i.e., how to retrieve the enormous loss of the extremely fine mineral in the slime portion of the ore. Slime, then, as now, was not a precise term due to the variation in the mineral composition of the ores and the different requirements in crushing, grinding, sizing, and classifying. At that time, slime was considered to be fine sand and colloidal material passing 100 mesh.2 Most sulfide ore minerals are more friable than their associated gangue minerals, so that crushing and grinding increased the proportion of the extremely fine ore minerals in the slime. Sparkling specks of galena, chalcopyrite, argentite, or ruby silvers, according to the ore, floating away on the tailing stream from vanners and slime tables, were familiar sights in the old gravity concentrators. Gravity concentration practice was aimed at recovering the ore minerals at the coarsest possible size because the recovery was higher and unnecessary

Jan 1, 1962

By H. R. Hanley

ONE of the most important contributions to the art of electrolytic zinc production-has been the aluminum cathode. This has been used in all major production: since its commercial development in 1916. The literature is replete with important contributions, some of which may have been replaced by better ones, but thus far there appears no other metal to take the place of aluminum as cathode material. Credit for this innovation goes to Sherard Cowper Coles, of England. When experi-menting on the extraction of-zinc from Broken Hill ore at Hayle, Cornwall, in 1893, he introduced the aluminum cathode, and in 1895 obtained British Patent-No. 20073. The reason for this dominant position of aluminum as cathode mate-rial in zinc sulphate electrolytes is its unique surface, to which electro-deposited metals usually do not tightly adhere. The metal must be of high purity for best results. It is possible to develop a starting-sheet method by which thin electro-deposited sheets of cathode zinc are made and stripped from a smooth aluminum plate. Such thin sheets of cathode zinc may be used as arc tine copper sheets in standard electrolytic copper-refinery practice. However, complications arise because of extreme warping of the zinc starting sheet after a .few hours of deposition, and thus special arrangements must be made to compensate for this abnormality.

Jan 1, 1938

By V. C. Smith

Reliable and detailed statistical data available for Kentucky, Ohio and West Virginia are the most meager and unsatisfactory of any of the producing states. Detailed histories and statistics are available for only a few pools. The antiquity of these pools, loose nomenclature, particularly where several names are applied to the same pool or various parts of the pool or a new namsed when the pool was rediscovered, made the collection of accurat historical and statistical data almost impossible. So many of the data reported are unreliable that a breakdown by pools or even by counties, until more accurate information is available, would lead to gross errors. Rather than perpetuate inaccuracies, we have endeavored to go to original sources wherever possible, sift these and provide data that may serve as an incentive and basis for future work. The necessity for accurate information is thoroughly recognized by the operators, particularly because of the effect of recent government regulations and request? for data in connection with the preparation of the various codes a pending legislation. Producers, both major operating companies and individuals, . freely given their time and assistance in the compilation of these data. Valuable information was obtained from tax records, rate cases, statistics published by the oil and gas publications and the Bureau of Mines. So many individuals cooperated in the preparation of these data that individual credit cannot be given. Undoubtedly many errors will be found. Some of the data are open to controversy, and many have been omitted in the hope that new information of a more reliable character may become available. Other omissions are due to an inability to contact the proper individuals, many of whom are no longer connected with this industry. Pennsylvania grade crude sold in 1933 for the lowest price since 1895. Gas production could not find sufficient new markets to fill the void left by industrial stagnation. In the gas industry, where the market price is fixed by contract, uncertainty persisted because of impending legislative action affecting both taxes and utility rates. As a result of these factors and a lack of new money, drilling was restricted to a new low. The lifting of proration toward the end of the year in the Pennsylvania

Jan 1, 1934

By Oscar E. Harder

THE TERM "physical metallurgy' is used in the title of this lecture in preference to "metallography ?because the former has a broader meaning with most audiences, some people thinking of the latter as being limited to work with the microscope. This distinction, how- ever, has not been held by the out- standing workers in the field of metallography, such as the late Professor Sauveur. In the broadest sense metallography is essentially the same as physical metallurgy. The American Society for Testing Materials has adopted-the following definition: "Metallography is that branch of science which relates to the constitution and structure, and their relation to the properties of metals and alloys." This definition might be improved by adding after "properties" -"and their industrial and scientific uses." Metallography has also been defined as the science of metals and alloys. Physical metallurgy is to be distinguished from process metallurgy in that the latter relates particularly to the production of metals from the ores.

Jan 1, 1940