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By W. A. Backofen, G. Mayer

Single crystals of iron, copper, and a Cu-7 wt pct A1 alloy were pulled through conical dies to simulate the constraint in a polycrystalline aggregate undergoing axisymmetric reduction. With Taylor-type hardening, dependence of the drawing stress, od, on the Taylor orientation factor, M, is predictable from the polycrystal stress-strain curve; in particular, for a power-law relationship, it should follow that d log od/d log M = (1 + n). A first-order agreement with analysis was found in the data from iron. For copper, the implied n from the observed d log od/d l°g M was -0, while for Cu-7Al it was negative. The trend was in the direction of random polycrystal behavior. Thus the idea of hardening only in response to the amount of prior slip loses validity as stacking fault energy (SFE) is lowered. Two possible explanations have been suggested: as stacking fault ribbons are widened, barriers from dislocation reactions become increasingly effective in dispersing slip and reducing the orientation dependence of the total glide strain dm that appears in alternatively, or conjointly, the polyslip shear stress, 7, acquires an orientation dependence of a kind which has the same leveling effect on M. The problem of relating the strain hardening of polycrystalline material to that of an isolated single crystal is still largely unsolved. In a new experimental approach from recent work, single crystals of different orientations have been deformed under the constraints found in an aggregate while measuring their deformation resistance. Procedures have involved drawing cylindrical crystals through conical dies1 and compressing slab-shaped crystals in plane strain.2'3 Predictions for the outcome of such experiments were made first by Taylor~ and later, in more general form, by Bishop and Hill.5'6 Taylor's example was the axisymmetric extension of an fcc crystal slipping on the usual {111}(110) systems or, equivalently, a bcc crystal undergoing 'kestricted" slip on {110}(111). In his solution, the deformation work supplied was equated to that dissipated internally in slip on all active systems. With o the single applied tensile stress, dc the resulting axial strain, and dyT the total glide strain on systems operating at resolved shear stress, 7: The orientation dependence of M was found by minimizing dyT for each orientation while activating five independent systems, Fig. l(a).? The Bishop and Hill analysis, based on a principle of maximum work, leads to essentially the same conclusion; the need for at least five active systems is recognized in the finding that either six or eight are actually brought into operation. The mean value from the entire stereo-graphic triangle in either case is M - 3.06. More recently, Hutchinson8 made a Taylor-type analysis for pencil glide in a bcc structure, from which piehlerg prepared Fig. l(b) as the counterpart in Fig. l(a); here M = 2.75. The obvious weakness in such analyses is the indifference to slip-system interactions. A condition of what might be termed "independent"

Jan 1, 1969

By A. Ballester, F. Gonzalez, M. L. Blázquez

Pyrometallurgical process are usually used to recover valuable metals from metal sulphide concentrates. However, their use is diminishing as the cost of energy rises and pollution controls become strictes. An alternative method of treatment sulphides could be bacterial leaching due its simplicity and negligible contamination (1-2). This process is presently used commercially to re cover metals such as Cu and U from low grade ore concentrates. In spite of numerous researchs during recent years (3-5) there exists very little kinetic data concerning the speed of bioleaching process. The kinetic analysis of bacterial activity is related with the metabolism and growth of microox ganisms . This fundamental information permits ma- king the best utilization of bacterial oxidation and to suggest techniques which might increase the production of the products desired. However, bio- kinetic models are especially complicated due to the existence of many metabolic routes and parallel reactions which are important for the life of the bacteria. Microbiological oxidation of a mineral substrate is influenced by its own inicial concentration: This influence can be determined by means of a kinetic study. In a medium with sufficient concentration of nutrients (nitrogen, phosphorous and potassium) and an adequate supply of 0, and CO2, as the only & L source of carbon for the biochemical synthesis, the substrate concentration would remain the only limitation in the rate of leaching. In this case the Michaelis-Menten model could be applied (6). The model is based on an association of the enzyme (El with the substrate (S) with consequent decomposition of the latter into enzyme and products [ ] The rate of dissolution is defined by the equation : [ ] Were V is the rate of metal extraction (mg 1-1 1 h-1 ) ; S is the pulp density Mn is the maximum rate for metal extraction (mg 1-1 h-1) and K is the constant of Michaelis (concentration of substrate that yields Vm/2). This method is applicable only when the rate of bacterial growth is similar to the rate of metal extraction. It would therefore be sufficient to control the concentration of metal in the medium over the period of time. In the present work a systematic study of the kinetics of ZnS and CuFeS bioleaching in sphalerite and complex ore concengrates was carried out. The rate of dissolution of the Zn and Cu as function of the pulp density and temperature was determined. However, most oxidations of sulphide dissolution take place with a very slow kinetic; but, this can be accelerated considerably by the addition to the solution of suitable catalytic ions, as was Suggested many years ago by Bjorling (7). Such ions can exercise an important influence on the rate of the oxidation-reduction reactions, both homogenous and heterogenous, which take place during the leaching of sulphides; they also affect the nature of the reaction products. The action of catalytic ions has been fully developed in aqueous systems, but in the absence of bacteria (8 - 11) although the actual machanisms is not totally known. The mechanisms proposed as hypotheses in the literature (8) indicate that, in the case of ZnS, the catalyst ion act through an electrochemical mechanism according to the reactions: [ ]

Jan 1, 1989

By Alexander L. Field

IN a previous paper,' the experimental methods used and some of the results obtained in an extensive investigation of steels containing zirconium were described. The present paper considers in greater detail one of the most interesting of these effects, namely, the elimination of " red shortness" and the occurrence in steel of a compound of zirconium and sulfur. A consideration of the actual percentages of zirconium, manganese, and sulfur in numerous steels in the light of behavior during rolling has led to new conclusions of the most practical import regarding the reciprocal relationships of these elements. The microscopic examination of high-sulfur steels containing zirconium has also been productive of interesting results. Before discussing the experimental data in question, it may be stated, briefly, that the rettetion between zirconium and sulfur in molten steel may be represented by the simple equation, Zr + 25 = ZrS², and that the zirconium sulfide thus formed occurs in the finished steel in the form of gray-colored inclusions, closely resembling manganese sulfide and, like the latter, exhibiting plasticity at rolling temperatures. Molten steel containing zirconium retains such a negligibly small amount of oxygen in solution that the foregoing reaction goes to completion. Hot-rolling Properties of High-sulfur Steels with and without Zirconium The chemical composition of twenty-eight steel ingots embracing eleven heats made in a basic-lined electric furnace is shown in Table 1. The practice followed in the manufacture of these high-sulfur steels was described in the previous paper. Table 1 also gives the behavior of the

Jan 1, 1924

By James Johnston

Synopsis.-A description of the working of the mills of this company and the metallurgical practice in vogue, by which a remarkably. complex silver ore, averaging 54 oz. of silver per ton (run-of-mine ore), is treated to give a 95.66 per cent. extraction. The main features of the, processes are: The cyanide amalgamation of the high-grade ore. The cyanide treatment of the low-grade ore, after extremely fine grinding and close classification, in a caustic soda solution. The use of a wet desulphurizing process to break up refractory silver minerals. The substitution of aluminum dust for zinc dust as a precipitant. The recovery and shipment of over 13,000,000 oz. of silver in bullion at. 997 to 999 fine since this metallurgy was inaugurated, about 2.5 years ago. On the completion and successful operation of the mill to treat their . high-grade ore,1 the Nipissing Mining Co., under the general management of R. B. Watson, started a series of investigations of the possible treatment of the low-grade ore by the cyanide process, so that they would be in a position to market only silver bullion. These tests were run in July, 1911, on a large scale, by G. H. Clevenger, on an average mixture of Nipissing ore. The results obtained by a partial amalgamation followed by cyanide treatment gave an extraction varying from 90 to 93 per cent. and were sufficiently encouraging to warrant Charles Butters, the company's Consulting Metallurgist, in recommending that the new low-grade ore mill under contemplation should be a cyanide mill, instead of a concentrator. The cost of such a mill, capable of treating 200 tons per day, to obtain a 90 per cent. extraction at a working cost of $3 per ton of ore treated, was estimated at $250,000.

Jan 1, 1914

Maptek, an international development software company, released version 3.2 of its Vulcan three-dimensional mining and geological software package. This latest release is expected to give clients better graphics performance and improved overall solutions. In addition, the company also released the NT version of Vulcan for Unix and personal computers. More than 800 code changes have gone into the 3.2 release, the Lakewood, CO-based company said. Many of these changes were in response to requests from Maptek's customers. Others have been motivated internally by the company to achieve better performance in its Envisage graphics interface. The introduction of hot keys and user-defined menus makes Envisage a more flexible interface and a more productive working environment. A new animation option provides new ways to enhance the organization and display of data. The animated data can include point, string, grid, triangulation and photographic-draped data. The shaft-mapping facility is also included in version 3.2. It enables the cylindrical view of the shaft to be unwrapped and displayed on the screen while the data remains in its true world coordinates. Major upgrades to Vulcan include underground blast design and geotechnical modules. The new blast design module allows the user to develop a ring design in any plane defined by the stope layout. Radial and offset holes can be developed. User-friendly editing tools make adjustments to the initial design a simple task. The user defines the plotting and reporting of rings and plot style templates allow flexibility in reporting. New features in the geotechnical toolbox include options to create daylight windows and pitch lines on the stereo nets. Geotechnical databases can be directly updated from the interpretation of the stereo net. Direct annotation of the symbols on the net is now possible and the stereo net display can be customized. Improvements to the documentation and links within the text have made the on-line help easier to navigate. Maptek also released the NT version of Vulcan soft- ware. The comprehensive design of the software pack- age for Unix and personal computers provides a three-dimensional geological modeling and mine planning system within a natural graphics environment. Users who require the power to manipulate extra- large and complex data sets will still be served by the Unix platform. Users who handle small-to-large datasets can now choose between Unix and personal computer platforms. The NT version will appeal primarily to companies that already have a personal computer network. Response to industry feedback was the basis for developing the NT version. "We want to ensure that our clients receive the optimal product for their needs," said Nicolas Simon, vice president of Maptek in North America. Some advantages of the NT version include: ? Most mining professionals are familiar with the personal computer platform. ? All of the familiar personal computer tools are now available to Vulcan users. ? Resource modeling tools that previously required the powerful Unix workstations have been brought into the personal computer environment. This will help mining companies save money. From a binary data point of view, the personal computer NT version is compatible with other platforms, such as SGIIDECIHPISUN, allowing integrated personal computer and Unix environments For more information, contact Cherie LeDoux, Maptek, 165 So. Union Blvd., Suite 777, Lakewood, CO 80228, fax 303-763-4921, e-mail: info@maptek.com, Internet: http:llwww.maptek.com.

Jan 1, 1997

By P. R. Jochens, D. D. Howat, R. B. Atmore

INTRODUCTION The Miller chlorination process has assumed a preeminent position in the refining of gold bullion, a position it has maintained for over half a century. In the early sixties considerable interest was aroused by the idea of producing a consistently high grade bullion at the mine smelthouses themselves. However, as the use of chlorine in industrial plants is associated with considerable hazards, oxygen was considered a natural alternative, apart from bing less expensive than chlorine. Partial refining at the mine smelthouses would considerably decrease the requirements made on Rand Refinery Limited as well as indicating the possibility of reducing final refining costs. An added factor would be the purer silver chloride obtainable, after prior removal of the base metals by oxygen injection, which would facilitate the production of high-purity silver. The free energies of formation of the oxides of the metals;- silver, copper, lead, zinc, iron and bismuth indicate that, with the exception of silver, these metals should be capable of removal as oxides by oxygen injection. Rose1 had shown that during injection of gold bullion, considerable loss of silver to the boraxsilver slag occurred and, furthermore, that copper removal was not efficient and oxide attack on the refractories was severe. Plant test work2 had confirmed the difficulty of copper removal, but had shown that zinc and lead were almost completely removed. The difficulty of copper removal by oxygen injection warranted further investigation. Also, the high decomposition pressure of silver oxide suggested that by suitable control of the slag composition it might be possible to reduce to very small proportions the silver carried into the slag as oxide. The oxidation of copper by oxygen injection and subsequent dissolution of the oxide in a slag may occur according to the following reactions; Reactions 4 and 5 were considered because of the relatively high solubility of oxygen in molten silver and silver alloys. Thermodynamic data indicate that there is little possibility of any reaction involving the formation of CuO occurring at temperatures above 1 000 °C. To ensure that the operative reactions 1 and 4 take place to the maximum extent, the following factors He significant. (a) an increase in the activity of the copper in the bullion, (b) an increase in the partial pressure of oxygen in the system, (c) an increase in the activity of the oxygen in solution in the metal, (d) a decrease in the activity of cuprous oxide in the slag. From practical considerations, the operative variable most easily susceptible to control is the composition of the slag. SOLUBILITY OF COPPER OXIDES IN BOROSILICATE SLAGS Very scanty information exists on systems containing copper oxides but the indications are that slags containing considerable amounts of boric oxide would possibly prove to be the best solvents for cuprous and cupric oxides. This is attributed to the fact that the activities of copper oxides are much lower in boric oxide slags than in slags in which silica is the main network former. The number of possible slags containing boric oxide was limited by consideration of liquidus temperature, viscosity, corrosive action on refractories, volatilization, and ultimately cost (for industrial application). Slags in the systems soda-boric oxide-silica and lime-boric oxide-silica were selected paying due attention to the above limitations. Additions of 5, 10 and 15 per cent cupric oxide were made to the finely ground, premelted slags. These mixtures were then reground and 2g quantities held in re crystallized alumina crucibles at temperatures of 1150°C and 1 250°C respectively for 30 minutes. The crucibles were removed from the furnace, rapidly cooled, cut in half longitudinally, and a thin section taken from one half was subjected to microscopic examination.

By G. P. de Forest, G. O. Hiers

The object of the experiments reported in this paper is to determine the eutectic composition of copper and tin and to determine the location of the part of the liquidus line immediately above the eutectic composition in copper. Three methods were used in the investigation: (1) the method of dissolving copper in a bath of molten tin at constant temperature, with the idea that when the bath was saturated with copper its copper content, by analysis, together with the temperature at which the saturation took place would locate a point on the liquidus line; (2) the method of the differential cooling curves, and (3) the method of microscopic examination. This paper is principally concerned with the results of the last two methods mentioned. The results of the first method, that of dissolving copper in molten tin, did not agree with the results of Miller,' by the same method, nor with the results of other investigators by other methods, nor yet with the results of the cooling-curve experiments and microscopic examination reported here. Solution of Copper in Molten Tin To determine the amount of copper that would be dissolved by molten tin at a given constant temperature the apparatus shown in Fig. 1 was used. It consists of a cast-iron pot a, 6 in. deep and 8 in. dia., well cleaned inside and dressed with graphite. This pot, which holds 15 lb. of tin, g, rests on a hot plate b with resistance winding c. The thermocouple d leads to a Wilson-Maeulen temperature regulator for maintaining the temperahre at the heating coils at a fixed temperature to within ±5°C. There is a shallow bath of solder e on the top of the hot plate to improve the thermal contact between the plate and the pot. An insulating jacket f of asbestos prevents the irregular radiation of heat from the apparatus. The copper stirrer h slowly rotates in, and is dissolved by the bath of molten tin g. This bath is protected from excessive oxidation by a layer of charcoal j. The stirrer h is fixed to the lower end of the iron tube k, which is so mounted that it can be driven by a motor with reducing gear. The temperature of the bath is indicated

Jan 1, 1930

MR. ENZI: hank you very much. I'm sure there?s a lot of you out there just realizing that Rock Springs and Gillette is not one city. I'm sure there's a lot of you wondering why a person from a town who has the image in the national media that the town of Gillette has is talking to you about image. I had a person this morning ask me if Gillette wasn't the end of the world. The only response I can give is "no, but you can see it from there." We have been researched a lot and, I realize, we've been very lucky because I've observed that researchers cause cancer in rats. In fact a wonder drug is one that has no effect on mice. In fact I've been thinking of posting a sign in my office that would read "due to the large number of interviews by journalists who already have their articles written, we would most respectfully request that anyone wishing to insult the city of Gillette, please limit themselves to 3,000 words or 15 insults, whichever is shorter." I don't know if any of you saw the article in Playboy about three months ago on the city of Gillette. What you probably don't realize about that article is that that was an attempt by Playboy magazine to see if they couldn't change their image to a national municipal magazine. I think it's important to know Gillette is the frontier city, a pioneer city, it's a shopping center for northeast Wyoming and most importantly, we're the energy capital of the nation. We're on the threshold of the Powder River Basin and we will be the nation's energy solution. Besides coal, we're, already the heart of the state's leading oil producing area and we have vast uranium resources. But I, want to tell you the biggest resource that we have is, the people who have come to live in Gillette. You will find Gillette a busy, young, pulsating community. We're experiencing the excitement of growth. We're welcoming a higher percentage of newcomers than any other town in the nation. Yes, growth to us is exciting. Where else can you get ten years of experience in two years? We realize you can't maintain the status quo. Growth can be painful but not as painful as the alternative, recession and depression. For a little bit of background, we are now at 16,000 people and we have another 4,000 people who live on the outside but look like they live on the inside. The Census Bureau says that we have, 11,225 people but we have that many people in a traffic jam on the Douglas Highway in one day. I?ll , tell you about a few things happening in Gillette. I think it's very important to emphasize that I didn't , do these things; it's the youth and the energy of the community that has done these things. Right now the city of Gillette has 32 major projects underway. We have water for 50,000 people and we're seeking more water. The city in 1975 was 1 .8 square miles. Last year alone we annexed I square mile. We build 10 miles of paved streets a year. For the last 8 years we've doubled our parks' budget. I

Jan 1, 1982

By E. P. Fahrenthold, K. E. Gray

Introduction Brine reservoirs along the Texas and Louisiana Gulf coasts are currently under study to investigate the technical and economic viability of production wells designed to extract methane gas in solution. The effect of well pressure drawdown on reservoir rock and associated overburden material is important to well performance predictions and the analysis of potential subsidence problems. Consequently a series of compaction tests have been conducted on sandstone and shale cored from a test well drilled near Hitchcock, Texas, in order to determine the variation of mechanical properties to be expected over the producing life of the formation. Previous Work The referenced tests are part of an extended study of geopressured-geothermal reservoir behavior, including compaction (Jogi, Gray, Ashman, and Thompson, 1981 and Jogi, Kalra, Gray, and Thompson, 1981) and creep (Thompson, Jogi, Gray, and Richardson, 1981) tests of reservoir rock and related reservoir performance studies (Rago, Okhuma, Seperhnoori, and Thompson, 1985). Recent work has considered the nonlinear constitutive behavior of sandstone (Fahrenthold and Gray, 1985 and 19861, while additional experimental work is reported here. Geological structure and composition of the Hitchcock field from which the core samples were obtained is discussed by Light (1985). Experimental Procedure Compaction tests were conducted on cylindrical cores, nominally 2.75 inches in length and 2 inches in diameter, with independent control of the axial, confining, and pore pressures. Axial and radial deformation of the samples were measured in tests over a range of effective stress states expected to develop over the reservoir lifetime. The term effective stress as used here refers to the algebraic difference of the total stress and pore pressure, with compression taken as positive. Three types of compaction tests were conducted on the sandstone. In the uniaxial tests, axial total stress and radial strain were held constant as the pore pressure was reduced, similating one dimensional compaction which may occur during reservoir depletion. In the triaxial tests, radial total stress and pore pressure were held constant as the axial total stress was increased, duplicating conventional rock compaction test procedures. In the pore pressure drawdown tests, axial and radial total stresses were held constant while the pore pressure was reduced, in order to investigate differences in sample response to mechanical and pore pressure loading. Compaction tests were also conducted on shale material obtained from the reservoir overburden. The field coring process provided few consolidated shale sections sufficiently large to allow preparation of samples with the dimensions described above. With additional attrition during sample preparation of this brittle material, ultimate yield of the coring effort was limited. The few available samples were tested in uniaxial and triaxial tests similar to those described above. The use of displacement transducers to measure sample deformation avoided the difficulty of strain gauge installation on this material. Test Results The sandstone and shale both demonstrated nonlinear stress-strain behavior, with hysteresis and residual strain present upon unloading. Polynomial interpolation of the stress-strain curves was used in the calculation of incremental values for the loading and unloading moduli. Figures 1 and 2 show example axial effective stress-axial strain curves for triaxial tests conducted on sandstone and shale samples. The figures plot incremental stress and strain variables, defined as deviations from the state of prestress to which the sample was subjected. The state of prestress was varied between tests in order to investigate material behavior over the entire stress and strain space of interest. Tables 1 and 2 give the incremental moduli (Young's modulus and Poisson's ratio) as a

Jan 1, 1986

By Evert Hoek

Summarising a conference is never an easy task, but I will try to keep my comments brief and to the point. There are a number of lessons which we have learned from our deliberations together during these past three days, and I will try to give you my impressions of these lessons and of their practical implications in open pit mining. The first thing that has become increasingly obvious during these discussions is that it is no longer acceptable to offer an 'Act of God' as an excuse for a major slope or tailings dam failure. Disasters such as that at Aberfan in the United Kingdom have focussed the world's attention on the activities of the mining industry and the report of the commission set up to investigate the Aberfan disaster clearly showed that adequate knowledge was available and that failure to apply this knowledge did not qualify as an 'Act of God'. The courts and the world's press are certain to impose increasingly harsher penalties and criticism on those held responsible for major failures, particularly of tailings dams, in the future. One of the major problems in applying available knowledge to slope problems is that attempts to apply this knowledge are frequently left too late. To provide an engineering solution in the case of a slope in an advanced state of failure is an almost impossible task, and it is essential that those responsible for the stability of a slope must learn to recognise signs of distress at an early enough stage for effective remedial measures to be taken. As our ability to solve slope problems improves, the time at which slope stability problems are considered in a mining project must move forward to a stage at which these problems can be anticipated and dealt with before they arise. Conferences such as this are important in that they enable us to exchange ideas and advance our knowledge to a level at which such predictive engineering will be possible. It has been encouraging to hear of mining projects such as the Bougainville Copper operation where slope stability studies were carried out as part of the overall evaluation programme and it is hoped that this will become a more common procedure in the future. Providing a safe slope in an opencast mine obviously costs money, either in terms of the reduced ore to waste ratio given by flat slopes or because of the cost of stabilization techniques such as drainage or the use of rock anchors. An optimum slope design will provide maximum safety at minimum cost but achieving this optimum is not an easy task. Any one of us could design a slope which would be stable to the end of time, but it is probable that that slope would be so flat as to be totally uneconomic in most open pit mining situations. On the other hand, if the overall economics of a mining project are so critical as to require slope angles which the engineer responsible for these slopes considers to be unsafe, it is his duty to make us could design a slope which would be stable to the end of time, but it is probable that that slope would be so flat as to be totally uneconomic in most open pit mining situations. On the other hand, if the overall economics of a mining project are so critical as to require slope angles which the engineer responsible for these slopes considers to be unsafe, it is his duty to make

Jan 1, 1971

By W. W. Krysko

In order to calculate the critical particle size of lead oxide entrapped in lead, Stoke's Formula may be applied. All data were available except figures for the density of lead oxide at elevated temperatwes. The density of lead oxide was determined by means of dilatometmetrc and volumetric methods up to 1010°C. Graphs of the density of lead and lead oxide as well as the viscosity of lead are given and discussed, with the conclusion that the most unfavorable region for the separation of lead oxide from molten lead lies just above the melting point of lead. DURING previous investigations, particularly on the dedrossing of lead with aluminum1 and the oxygen solubility in lead,' the critical particle size of lead oxide which could be entrapped in solidifying lead was estimated by calculation, and it was shown that high values found for the oxygen content of lead may be due to the method of sampling and the entrapped particles of dross. Unfortunately, due to lack of data, an exact mathematical solution was not possible. The particle size which will separate under a given condition can be estimated from Stoke's Law, which states that where: d = diameter of the critical particle size ¦q = viscosity of lead in Poise V = constant velocity in cm sec-I g = 981 cm sec-2 61= specific gravity of lead 62= specific gravity of lead oxide The depth of the lead bath and the time before solidifying define the velocity. The viscosity of molten lead is known from earlier work by Krysko and is given in Table I. The specific gravity of lead is also known, see Table II. These values are according to Hofmann. A careful survey of literature revealed no values for the density of lead oxide at elevated temperatures. The present investigation was therefore conducted to provide this information. RESEARCH INVESTIGATIONS The density of lead oxide was determined from the following experiments: 1) Determination of the density of lead oxide at room temperature. 2) Dilatometric investigations on the same samples. 3) Determination of the shrinkage at the liquid-solid trans£ormation. 4) Density determinations on liquid lead oxide. 5) Time temperature curves during cooling. 1) The samples for the determination of the density of lead oxide in the solid state were prepared in the following manner. Molten lead oxide was cast into I hot mold which could be opened along the longitudinal (vertical) axis. The cast samples were cylinders of approximately 10 mm diam and approximately 80 mm length. The cylindrical hot mold was open at both ends and was placed on a large copper chill plate shortly before casting. The solidification of the lead oxides proceeded upwards without any formation of internal cavities. The sample was carefully checked with respect to density and crystalline appearance, and only the lower portions which were crystalline and free from porosity were used. The density was determined in a specially made pyknometer-like container, where the surplus liquid was squeezed out through an orifice approximately 1/10 mm in diameter. Mercury or water was used as the liquid. The densities of the samples were calculated from the weight, volume, and mean specific gravity of eight samples was 9.62 * 0.05 g cm"3 at 22"~. 2) The samples were machined to approximately 1 1/2 in. in length and fitted into a dilatometer. A

Jan 1, 1962

By J. S. Bryner

INTRODUCTION IN the study of metallographic specimens in the electron microscope, there is need for a method of locating the same field in both the light microscope and the electron microscope. This need arises chiefly from the fact that in the electron microscope the magnification and degree of resolution are so much higher, and the field so much smaller than in the light microscope that it is often difficult, if not impossible, to identify positively what is being observed. The difficulty is increased by the fact that, because a transparent film replica of the metal surface must be used in the electron microscope, micro-constituents can be identified not by their color but only by their texture and contours. For these reasons it is desirable to obtain a series of photographs showing the same field in both microscopes in order that the appearance of common microstructures and micro-constituents in the electron microscope may be identified and catalogued for future reference. The need for a method of locating the same field in both microscopes arises also when it becomes desirable to enlarge in the electron microscope for more detailed study a particular interesting structure observed in the light microscope. Using the standard polystyrene-silica1,2 replica technique, in which the silica film replica is fished from the ethyl bromide on a 1/3 in. diam 200-mesh specimen screen, the possibilities of locating a particular area on the film in the electron microscope are rather remote. The desired structure may be obscured by the wires of the specimen screen or unrecognizable at the high magnification. A solution to the problem would be provided if a specially designed specimen screen, containing an opening which could be absolutely identified and quickly located in the electron microscope, could be fastened to the silica film replica in such a position that the desired field on the specimen would be located at the identifiable opening in the specimen screen. The design for such a specimen screen, a method for producing it, and a technique for fastening it to the silica film replica are described below. DESCRIPTION OF METHOD The Specimen Screen A simple design for a specimen screen containing an opening easy to identify and locate in the electron microscope is one with two lines of openings at right angles in the form of a cross. Such a screen is shown in Fig I. The opening at the center of the cross is identified easily and can be located quickly in the light microscope and in the objective image of the electron microscope. The specially designed specimen screens for this work were produced in quantity by electroforming. On both sides of a polished strip of copper 1 X 3 X 1/8 in., twenty patterns of the cross of openings were punched with a diamond point micro-hardness tester, using a load of magnitude

Jan 1, 1948

By W. A. Bruce

This paper presents the essentials of a mathematical method of studying the pressure behavior of an oil reservoir as the fluids are withdrawn. Methods are shown Whereby the behavior of a reservoir can be used to predict the future relationship between withdrawals and pressure. The oil reservoir is considered as a small part of a large porous continuum, which contains for the most part water. The expansion of this water resulting from a decrease of pressure in the oil zone causes a movement of water that is an important factor in the relationship between fluid withdrawals and reservoir pressure. Examples are given to illustrate the methods of pressure prediction for a circular reservoir containing undersaturated crude, the pressure distribution over a field that has a uniform production rate, the effect of a fault line near a field, the mutual interference of near-by fields, and the perturbing influence of a gas cap. Applications of the analysis to well-spacing problems are shown. Introduction The pressure-prediction methods to be described here are based upon the conception of an oil pool as a small part of a large porous continuum, containing for the most part water. The formation containing this water may be thought of as extending over an area of many square miles and having one or more small bodies of oil or gas trapped in high spots or reservoirs. It will be treated as having the genera1 aspect of a thin, flat sheet with an over-all tilt to the horizontal and with numerous small high spots, tight zones, and irregularities This porous continuum will be treated as being much more extensive than the oil or gas zones, but will be recognized as terminating at such large boundaries as a general fault, outcrop, unconformity, or pinch-out. Throughout the greater part of this limited porous continuum it is likely that there is a hydraulic connection. If this is true, the removal of fluid in one place will cause a disturbance that eventually will travel to all parts of the continuum. This picture has led to the recognition of water as the major fluid in the porous continuum and in many cases the expansive nature of this water as the main driving force producing the oil. The next step is the solution of the general problem of compressible liquid behavior in porous media. The works of Hurst I and Muskat2 introduced the idea of using heat-flow mathematics to consider the problem of compressible liquid flow in a porous medium. Before their reports, it had been thought sufficient to use the incompressible fluid-flow work of S1ichter.3 Law Muskat4 pointed out in detail how far the incompressible-fluirl assumption, deviated from fact even for water, of which the compressibility is about 3 X 10-6 volumes per unit volume per pound per square inch. He showed that this deviation increased with increases of distance. For example, the incompressible-fluid formula might show good agreement with the

Jan 1, 1943

By W. A. Bruce

This paper presents the essentials of a mathematical method of studying the pressure behavior of an oil reservoir as the fluids are withdrawn. Methods are shown Whereby the behavior of a reservoir can be used to predict the future relationship between withdrawals and pressure. The oil reservoir is considered as a small part of a large porous continuum, which contains for the most part water. The expansion of this water resulting from a decrease of pressure in the oil zone causes a movement of water that is an important factor in the relationship between fluid withdrawals and reservoir pressure. Examples are given to illustrate the methods of pressure prediction for a circular reservoir containing undersaturated crude, the pressure distribution over a field that has a uniform production rate, the effect of a fault line near a field, the mutual interference of near-by fields, and the perturbing influence of a gas cap. Applications of the analysis to well-spacing problems are shown. Introduction The pressure-prediction methods to be described here are based upon the conception of an oil pool as a small part of a large porous continuum, containing for the most part water. The formation containing this water may be thought of as extending over an area of many square miles and having one or more small bodies of oil or gas trapped in high spots or reservoirs. It will be treated as having the genera1 aspect of a thin, flat sheet with an over-all tilt to the horizontal and with numerous small high spots, tight zones, and irregularities This porous continuum will be treated as being much more extensive than the oil or gas zones, but will be recognized as terminating at such large boundaries as a general fault, outcrop, unconformity, or pinch-out. Throughout the greater part of this limited porous continuum it is likely that there is a hydraulic connection. If this is true, the removal of fluid in one place will cause a disturbance that eventually will travel to all parts of the continuum. This picture has led to the recognition of water as the major fluid in the porous continuum and in many cases the expansive nature of this water as the main driving force producing the oil. The next step is the solution of the general problem of compressible liquid behavior in porous media. The works of Hurst I and Muskat2 introduced the idea of using heat-flow mathematics to consider the problem of compressible liquid flow in a porous medium. Before their reports, it had been thought sufficient to use the incompressible fluid-flow work of S1ichter.3 Law Muskat4 pointed out in detail how far the incompressible-fluirl assumption, deviated from fact even for water, of which the compressibility is about 3 X 10-6 volumes per unit volume per pound per square inch. He showed that this deviation increased with increases of distance. For example, the incompressible-fluid formula might show good agreement with the

Jan 1, 1943

By A. Kepeski

Cement industry relies heavily on the control of large volume of raw materials in the proximity of plant operations for clinker and cement manufacturing. These mineral resources are perhaps considered as ?low-profile? (mostly comprise limestone's, clays, marls and sands), but their availability, accessibility and suitability ? the later with respect to chemistry, mineralogical and physical characters ? are factors of paramount importance and may largely affect production cost and plant productivity. The combination of scarcity of good quality raw materials deposits and the growing environmental concerns have challenged the cement producers towards sustainability and the responsible exploitation of natural resources. In open pit mining and quarrying, the evaluation of mineral resources vs. handling of the non-usable overburden and other off-spec materials directly affects the medium to long-term production planning, quality control practices and environmental management. It is a general trend for many cement producers and a usual case for a number of Titan Cement plants worldwide, that redesign of quarry pits is necessary not only for stability purposes but also as a result of environmental constraints and emerging issues. The material reserves then have to be re-evaluated in the light of the new final pit design, safety distances from houses, other infrastructure and Law restrictions and according to criteria of safety of operations, reduction of environmental impacts, pit optimisation and proper future reclamation. The paper discusses the case of three active quarries of Usje Cement Plant, in Skopje (Macedonia), namely Usje (marl), Goverlevo (lime-stone) and Ljubosh (sand), where a large campaign of redesign and evaluation of recoverable reserves and the needs in rehabilitation took place in 2004. Technical and environmental issues and criteria are presented in the form of master plans and the highlights of the first attempts to propose and apply a reclamation scheme are discussed, by also examining alternative solutions for each quarry area. Finally, the 2005 progress in applying changes to the design of benches and pit layout, as well as experiences gained, are discussed.

Jan 1, 2005

By K. Barron

The glass insert stressmeter, or photoelastic stressmeter, is an instrument designed to determine stress changes occurring in rocks. It has several potential advantages over other such devices in that it is a biaxial device, it is simple and it is cheap to make. The object of this study was to assess the behaviour of the meter under biaxial loads and to examine some of the problems associated with measurement and interpretation of the fringe pattern. This assessment has been carried out by comparing theoretical and laboratory behaviour of the meter. It has been shown that: a) There are certain optimum measuring points in the meter at which measurements should be made for best accuracy. The position of the points depends on the ratio, n, of the biaxial stresses. b) The meter&apos;s sensitivity can be assumed to be independent of the rock modulus E provided that the rock modulus is < 2.5 x 106 psi and not, as previous workers have assumed, if E < 5 x 106 psi. c) There are several methods of separating the principal stresses; some of these are unsatisfactory. A new method is proposed and discussed. d) The meter sensitivity decreases as the ratio of the biaxial stresses approaches unity; the accuracy thus also decreases. e) The axes of symmetry of the fringe pattern give an excellent indication of applied stress direction. f) Laboratory calibrations are in good agreement with theory. The glass insert or photoelastic stressmeter is an instrument designed to determine stress changes occurring in rocks. It has several potential advantages over other such devices in that it is a biaxial device, it is simple and it is cheap to make. This stressmeter has been described in detail.l,2 Basically it is a hollow glass cylinder that has at one end a light source and filters producing circularly polarized light. The glass cylinder and source are grouted into a borehole in rock and the face of the cylinder is viewed through a quarter wave plate and an analyser. If, after installation, a stress change occurs in the rock, then a distinct colored isochro-matic fringe pattern is seen in the meter. The fringe order at any point in the meter can be determined by counting the fringes and measuring the fractional fringe orders by the Tardy compensation method. The relation between the fringe order at any point and the applied stress change can be determined either by calculation or by calibration. The object of this study was to assess the behavior of this stressmeter under biaxial loading conditions and to examine some of the problems of interpretation of the fringe pattern. THEORY Hiramatsu et a14 have determined the stress distribution in a hollow cylindrical inclusion in an elastic host material when subject to uniaxial stress. Using this solution, the biaxial case of stress p in the x direction and stress q in the y direction (Fig. 1) can be solved by superposition. This has been done in Appendix 1. It is shown that the principal stress difference (s1 -s2) at any point (r,?) in the cylinder is given by:

Jan 1, 1965

By N. Bartie

Realising the circular economy (CE) is faced with some significant challenges. Process metallurgy and its infrastructure play key roles at the heart of making the CE work. Therefore, the enabling role of process metallurgy within the CE will be central to the discussion in this paper, touching among others on product and system design as well as the key metallurgical and other process fundamentals that need to be investigated and understood to make the CE a reality. The central role of materials and its processing will be discussed in an integrated circular cities perspective. A key focus will be a discussion on designing a resilient “Smart Materials Grid” using and innovating metallurgical process engineering tools, which will manage the flows through Sustainable Circular Cities. The discussion will be using copper as leitmotiv of the discussion i.e. from copper ore, to metal, to complex products, recycling, product design and simulation and its impact. INTRODUCTION The transformation of our economies from linear to circular models in which waste materials become resources is the focus of the Circular Economy (CE) paradigm. Its important intentions: to take control of the damage we have been doing to the planet to ensure its livability and the welfare of future generations. This can only be achieved through careful utilisation of human, natural and economic resources. The concept is derived from several others (Beaulieu et al., 2015), of which Cradle-to-Cradle, Extended Producer Responsibility (EPR), Industrial Ecology, and Life Cycle Thinking are just a few. Other relevant concepts include resource efficiency (RE), design-for-recycling (DfR), and various others discussed by Blomsma and Brennan (2017) and Homrich et al. (2018), as well as various R-hierarchies e.g. Reduce, Reuse, Recycle (3R). However, does society comprehend these concepts, the actors and actions that influence them and how they interact? Do we know the limits of CE? Does society understand the key role of Copper and other metals to rendering the CE operable? True life cycle and systems thinking, focussed on simulation-based, process and metallurgical design are required to answer these questions. Lieder and Rashid (2016) identify nine widely-varying fields that study the concept ranging from sustainability sciences and engineering to economics, business, law, and social sciences. Overlap between questions addressed highlights the need for interdisciplinary collaboration (Nanz et al., 2017) in the assessment of the current status, and further steps needed to transform to CE. This doesn’t apply just in academia, but also in industry where concrete implementation of CE needs to occur at multiple levels, thus necessitating cooperation between government, civil society and other stakeholders (Beaulieu et al., 2015).

Jan 1, 2019

By L. S. Darken, H. A. Wriedt

In a previous paper,1 an experimental study of nitrogen dissolved in a cold-rolled ad heat-treated, low-carbon steel at 300° to 450°C yielded the equilibrium solubility relations and the concentrations of the two types of deject sites involved. In this paper, the probable identities of the defects that absorb nitrogen are restricted from the available evidence to screw dislocatioms for B sites, and to either micro crack surfaces or edge In a previous paper.&apos; we reported an experimental study of the excess nitrogen solubility in a low-carbon steel produced by a combination of plastic deformation and nonrecrystallizing heat treatment. The concentrations of the defect sites that absorb the excess nitrogen were measured in terms of their capacities for nitrogen. Also measured were the equilibria of nitrogen distribution among the sites. Several problems and questions arise from these measurements. We should like a physical identifi- dislocations for A sites. The concentrations of these defects in experimental steel specimens are estimated from the concentrations of defect sites. finally, the influence of chemical composition upon the nitrogen-trapping defects—the relative numbers generated in deformation, the relative numbers surviving as temperature is raised, the apparent numbers observed, and the distribution equilibria-is discussed. cation of the defects involved and of the two kinds of nitrogen-absorbing sites, called A and B types, upon those defects; the concentrations of the defects themselves could then be computed. We should also like to know how exclusively the findings apply to the "X steel" used in the experiments and to what extent they apply to cold-rolled steel given no subsequent treatment. By considering the data already given, together with results from a few specific tests which will be reported as they are invoked, we are able to eliminate some interpretations altogether and to secure an acceptable though limited interpretation from among the remaining possibilities.

Jan 1, 1965

By M. Gell, G. R. Leveran

The high- and low-cycle fatigue properties of the nickel-base superalloy, Mar-MBOO, in columnar-grained and single-crystal forms were determined at room temperature. It was found that the fatigue lives of these materials were greatly affected by the size of preexisting cracks in MC-type carbides contained in the micro structure. Most of the data falls on two curves given by: (zN)&apos;/A€= K, where Nf is the number of cycles to failure, Af is the total strain range, and K is a function of carbide size. No difference was observed in the fatigue behavior of the columnar-grained and single-crystal materials for the same MC carbide size. Matrix slip and crack initiation occurred at precracked MC carbides and, to a lesser extent, at micropores. Fatigue crack propagation was mainly in the Stage I mode, i.e., on cry stallo graPhic slip planes. The Stage I fracture in these materials was unusual in that distinct features were observed on the fracture surfaces. In high-cycle fatigue, these features resembled those commonly observed on the cleavage fracture surfaces of bcc and hcp materials. Yet, in this study, the cracks propagated slowly in a cyclic manner. In low-cycle fatigue, the Stage I facets contained equiaxed dimples, similar to those observed on the tensile fracture surfaces of ductile materials. These observations indicate that both local normal and shear stresses are involved in these Stage I fractures. A model is proposed to explain these results based on the weakening of the cohesive energy of the active slip planes by reversed shear deformation and the fracture of the bonds across the weakened planes by the local normal stress. RECENT developments in casting technology have produced cast nickel-base superalloys in columnar -grained and single-crystal forms.1&apos;2 The tensile and creep properties of the nickel-base superalloy, Mar-M200, cast in these forms have been shown to be superior to the corresponding properties of the conventionally cast polycrystalline material.lp2 This improvement in properties results, in part, from the elimination of grain boundaries in the single crystals and the alignment of the grain boundaries parallel to the stress axis in the columnar-grained castings. As part of a program to evaluate the fatigue properties of nickel-base superalloys cast in single-crystal and columnar-grained forms, a study has been made of the cyclic deformation and fracture of Mar-M2OO at room temperature. M. fiFl I .hininr Mpmher AIMF ic ^pninr Rocoarrh Accn^iata anH I) EXPERIMENTAL PROCEDURE The composition range of Mar-Ma00 in weight percent is: 8 to 10 Cr, 9 to 11 Co, 11.5 to 13.5 W, 0.75 to 1.25 Cb, 1.75 to 2.25 Ti, 4.75 to 5.25 Al, 0.01 to 0.02 B, 0.03 to 0.08 Zr, 0.07 to 0.12 C, bal. Ni. All of the castings met the above specifications. The castings were solutionized for 1 to 4 hr at 2250°F followed by aging at 1600°F for 32 hr which resulted in a 0.2 pct offset yield stress of 150,000 psi at room temperature. The microstructure of the material consisted of cuboidal, coherent particles of ordered, fcc Ni3(A1,Ti) (commonly designated y&apos;), approximately 0.3 p on edge, distributed in an fcc y solid-solution matrix. MC carbides together with shrinkage and gas micropores were also distributed throughout the materials. The MC carbides and micropores were located preferentially in the interdendritic interstices, as well as in the grain boundaries in the columnar-grained castings. The (100) direction of all the single crystals and the common (100) axis of the grains in the columnar materials were aligned within about 5 deg of the specimen axis. Fatigue testing was carried out in the high-cycle (HCF) and low-cycle (LCF) fatigue regions, with the major difference being gross yielding of the specimen occurred during the first cycle in the LCF region. This division also corresponded with the more usual one in which the life of a specimen in LCF is less than lo4 cycles and that in HCF is greater than lo4 cycles. The designs of the high-cycle fatigue and low-cycle fatigue specimens are shown in Figs. l(a) and (c), respectively. The gage sections of both HCF and LCF specimens were electropolished prior to testing. The HCF specimens were tested in an MTS, closed-loop, hydraulic fatigue machine at 10 cps in air. The specimens were cycled between a tensile stress of 5000 psi and a maximum tensile stress which ranged from 35,000 to 125,000 psi, Fig. l(b). The LCF specimens were cycled under strain control from zero to a maximum tensile strain, Fig. l(d), in a Wiedemann-Baldwin testing machine. The experimental procedure has been described elsewhere.3&apos;4 Both HCF and LCF tests were interrupted periodically in order to replicate the development of slip and cracking at the specimen surface. This was accomplished by placing plastic replicating tape around the gage section of the specimen while the specimen was in the mahine. The size of the MC carbides for all specimens was measured on a polished longitudinal section through the gage section after fatigue testing. The method of measurement consisted of carefully scanning the entire polished section in order to locate the largest MC carbides. Photographs were then taken of the six longest carbides oriented approximately normal to the

Jan 1, 1969

By Gokhan Inci

Stability problems with dam spillways on existing landslides and appropriate mitigation measures to remedy them are ongoing concerns for geotechnical engineers. The first successful application of drilled piers as stabilizing structures under the spillway was at the Trinity Dam in Sicily, Italy. ?Underpinning? was considered as an alternative to spillway relocation during the Alpaslan 2 embankment dam design in eastern Turkey. Based on the available literature the first application of drilled piers to stabilize a spillway chute in the U.S. was at the Ralston Dam in Colorado. Ralston Dam, which is a 175-foot-high zoned fill dam located 15 miles northwest of downtown Denver, was built in the late 1930s. The concrete spillway for the dam was built on the Pierre Shale Formation in the left abutment. Since reservoir operations began, mass movements have occurred downstream of the chute area. These movements have required periodic spillway maintenance. After the occurrence of recent movements and because of high piezometeric levels, URS was contracted by Denver Water to develop a more permanent solution by the installation and monitoring of additional instrumentation, analysis of slope stabilizing measures, design, repair, and reconstruction of the distressed section of the spillway chute. With state of the art modifications that include: 1) a stabilizing berm with a toe trench that improves the global stability; 2) seepage prevention and control measures that prevent the infiltration of water; and 3) the structural support of the replaced chute section with drilled piers and reinforced concrete the probability of future displacements or other problems have been reduced for the Ralston Dam Spillway.

Jan 1, 2007