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By A. M. Alfantazi, M. Boissoneault, D. B. Dreisinger, J. Synnott

"The effects of five commercially available foaming reagents (range of 0 to 25 ppm) namely Dowfroth 250, Saponin, Yucca, Licorice and Meta-Para Cresol on acid mist control, current efficiency, polarization behavior, and deposit morphology and orientation were investigated. The deposition was carried out using a bench scale electrolysis apparatus (cell volume 3L) at 500 Nm-2 and 38°C for 3 hours from Kidd Creek zinc electrolyte. The acid mist control capability of the various reagents was studied and compared by characterizing the foam layer generated during actual electrowinning conditions and by direct quantitative measurements of acid mist levels on top of the electrowinning cells. Within the range considered, the addition of these reagents reduced the current efficiency, refined the grain size of the deposit, and changed to preferred orientation of most of the deposits. Among the reagents tested, acid mist measurements indicated that Licorice and Dowfroth 250 were the best acid mist suppressant at emissions of 0.30 mglm3 and 031 mg/m3 respectively while Yucca and MPC produced the most mist at 3.0 mg/m3 and 33 mg/m3 emission rates, respectively.IntroductionMost of the world's primary zinc is produced via a combined roast-Ieach-purificationelectrowinning process. Depending on the electrolysis conditions, several additives may be added to the electrolyte. Some (e.g. glue, antimony, sodium carbonate) are added to mainly counteract the detrimental effects caused by impurities while others (e.g. licorice, Saponin) are used as foaming reagents to prevent excessive acid mist formation. Acid mist emission is a problem in many electrolysis operations because it corrodes the equipment and is a health hazard to the workers in the tankhouse as well as it pollutes the environment. Due to recent trends towards more environmental protection and more stringent in-plant hygiene, there is an increasing need to minimize these aerosols. In order to eliminate or minimize these aerosols foaming agents are usually added to the electrolyte to produce a foam layer on top of the electrolyte, thus trapping most of the mist. The ideal foaming agent would trap all of the mist and would not interfere with the electrowinning process. It is also evident that the reagent toxicology, cost and availability are important factors that need to be considered.Review of the available literature clearly indicated that very little work has been done in the past on the subject of acid mist control in electrowinning operations particularly in the area of foaming and anti-misting properties of surfactants. Two papers [1,2] have reviewed briefly the existing technologies for acid mist control. Recently, most of the work in this area has focused on the development of special mechanical devices that could be attached to the electrodes and control the mist generation at the source before it is emitted to the cellhouse [2-5]. On the other hand, extensive body of literature exists that deals with the effects of anti-misting reagents on the electrowinning aspects [6-7]."

Jan 1, 1997

23.1-SOURCE, POWER-SYSTEM ELEMENTS A. J. T HUM Basic considerations in providing power for mine production and collateral operations are: 1. Mining operations of any size normally use electric motors for driving all equipment except mobile service units. 2. The electricity for power may be purchased or self-generated, depending on the location, size and specific operating circumstances of the individual property. 3. The major elements of the power system will be the source, either an incoming transmission line from a utility in the case of purchased power or the power plant if self-generated. Energy for the power plant may be water, hydrocarbon fuels, waste heat or nuclear, which will govern the type of prime mover selected. 4. The electricity normally is generated in the form of alternating current and must be distributed to the points of usage. This usually requires a primary substation for transformation to suitable voltages and secondary substations at points of usage throughout the operations, The power is delivered from the primary to the secondary substations over transmission lines or cables, depending on distances, voltages and local conditions. 5. At the points of use, there will be starting and protective devices for each motor. In some instances, direct current will be needed and rectifiers of various types can be used to provide it. 6. The entire electrical system requires suitable switching and protective devices to prevent damage to the equipment in case of power failues or faults; also, in most cases, sufficient metering to establish the demand and amount of electrical energy consumed. 23.2-PURCHASED POWER A. J. THULI 1. Where public-utility or government-generated power is available, it usually is advantageous for the mine owner to purchase rather than generate. Purchased power generally will be cheaper and more reliable than operating a small generating plant except in some cases where waste heat is available as the source of energy and can be used to supply all or a portion of the power requirements. 2. If it is decided to purchase power, the owner usually must participate in the cost of constructing the connecting line from the closest existing utility line to his point of usage. If the connected load is less than 1,000 lip, it probably is best to let the utility provide the primary substation. For larger connected loads the owner can obtain a more favorable "primary voltage" rate if he provides the primary substation to receive the incoming power and transform it to the distributing and usage voltages. 3. The cost of purchased power usually is made up of a demand charge, deter¬mined by the maximum amount of power the customer takes during any 15-min period throughout a month, and a graduated energy charge for the kilowatt-hours consumed-that is, so much for the first block of energy based on the demand,

Jan 1, 1973

On the following pages are abstracts of papers published by the Institute during the year 1932 as Technical Publications, Preprints, in bound volumes and in Mining and Metallurgy. For abstracts of papers that appear in bound volumes in 1932 but that were published as Technical Publications in 1930 or 1931, see the Transactions for those years. Papers that appear in this volume are not abstracted here. Many of the Technical Publications have been reprinted in bound volumes. Information regarding this disposition, and number of pages in each paper, may be found in the list beginning on page 309. Volume numbers are given as listed on page 3 and in the paragraph at the beginning of the index, page 315. The abstracts are grouped as follows: Page Page Metal Mining.................... 265 ferrous Alloys)................. 279 Milling and Concentration......... 268 Coal Division.................... 287 Iron and Steel Division............ 270 Petroleum Division............... 292 Nonferrous Metallurgy (Reduction Nonmetallic Minerals............. 299 of Ores)....................... 277 Mining Geology.................. 301 Rare Minerals and Metals......... 279 Mining Administration (Accounting, Institute of Metals Division (Found- Taxation, Industrial Relations). . 304 ing and Metallography of Non- Geophysical Prospecting........... 304 Metal Mining The Mineral Industry. By Scott Turner. (Min. & Met., June, 265. 3500 words.) Abstract of an address delivered before the Royal Canadian Institute, Toronto, April 16, briefly outlining the importance of mining in the United States, in Canada, and in the world. Comparison is made of the mineral production for 1886, 1900, 1910, 1920 and 1929, showing that in the 43 years from 1886 to 1929 that of the world increased nearly tenfold, of the United States over twelvefold and of Canada thirtyfold, but that Canada's output was equivalent to only 2 per cent of the world total and to 5 per cent of that of the United States in 1929. Statistical tables and graphs show value of production, percentage of world production contributed by Canada and the United States, etc. The mining situation in Canada is briefly reviewed: only those American engineers who have had occasion to examine the figures appreciate the rapidity of growth of Canadian mineral production. The treatment of minerals involves vast complex industries. When we are producing, say, 6 billion annually, the employment of 2 million workers provides indirect support to perhaps 10 million people. Exploiting mineral deposits is peculiar in certain ways, for the deposits are exhaustible, are of rare occurrence when measured in terms of outcrop area compared to total earth area, and may suddenly be handicapped or superseded by new discoveries; moreover, the economic position of the contained metals is 'affected by the use of scrap metal and the existence of invisible stocks. The largest and most valuable of the mineral deposits are not the metals, but rather the fuels. The record of the coal industry in recent years is one of brilliant technical achievement; its economic position is far from satisfactory. A so-called world fuel

Jan 1, 1932

By T. M. Waterland

A GREAT deal of work has been done at Britannia during the past three years in improving and standardizing rounds for development headings, and the results obtained have been very gratifying. The round which has recently been adopted as a standard for all drifts and cross-cuts has, in some instances, doubled the average length of break formerly obtained. It has also increased the footage of advance per labour shift and reduced explosives' consumption. At the present time, with a shortage of skilled labour, more control is necessar7 in directing the drilling of rounds. The use of a standard round has been o great assistance to the foremen and shiftbosses. NATURE OF GROUND Most of the ground encountered consists of a moderately silicified chlorite schist, known locally as G.M.S (green-mottled schist). It cannot be termed hard ground, because a three and one-half inch Leyner will drill at an average rate of twelve inches per minute. Due to the abrasive nature of the ground, the gauge of the steel wears rapidly and in most cases one set of steel is needed for each hole. The ground is not 'free breaking and holes must be spaced correctly to obtain a maximum break. DEVELOPMENT OF STANDARD ROUND FOR THREE-SHIFT OPERATION Late in 1940, a development programme was started involving 7,000 feet of drifting, 6 ft. By 7 1/2 ft. In cross-section, in two headings. Plans were drawn up to advance the headings on three shifts. Equipment used in the headings was as follows: D.A.35 Leyner?machines, Eimco Model 12B mucking machines, nine one-ton end-dump cars, one Mancha Little Trammer on the longest heading, 20-pound rail, 4-in. 15 compressed-air line, 15-in. Fan pipe connected to 5 h. P. Coppus fan. Diamond-drill cross-cuts, 16 feet in length, were cut every 250 feet. Switches were installed at these cross-cuts and they served as passing points for the cars. One siding seventy feet in length was cut in each heading at approximately the half-way point. The cycle of operations planned was to muck out, drill, and blast each shift. Previous performance in this type of ground indicated that a daily advance of 12 feet to 14 feet might be made. However, if a better type of round could be developed, an increased daily advance would be possible. A study of the time available for each operation in a net working shift of six and one-half hours indicated that the maximum depth of round that could be mucked, drilled, and blasted each shift would be six and one-half feet. When this maximum depth was decided upon, the next problem was to develop a satisfactory round. Due to ventilation difficulties and to the short net working shift, the whole round had to be blasted at one time. In other words, no blasting of the cut-holes could be done.

Jan 1, 1942

By E. T. Turkdogan, P. Grieveson, J. F. Beisler

Experimental results are given for the rate of reduction of silica from silicate melts by paphite-saturated iron in the presence of carbon monoxide. It is shown that, when gas bubbles are present at the slag-metal interface, the interfacial chemical reaction is the rate-controlling process in the transfer of silicon from slag to metal. From the silicon-concentration profiles in the metal sample, the diffusivity of silicon in paphite-saturated iron is found to be (5.4 * 0.4) x 10 sq cm per sec at 1600°C. Some consideration is given to the transport of oxygen from the slug-metal interface to the walls of the gvaphite metal container as becoming the rate-controlling process in the absence of gas bubbles at the slag-metal interface. ATTEMPTS were made by Fulton and chipman1 to investigate the kinetics of reduction of silica from calcium alumino-silicate melts by graphite-saturated iron in an atmosphere of carbon monoxide. In these experiments with 400 to 500 g of metal and slag, both phases were stirred in such a manner that the interface was essentially undisturbed. Initially, the graphite-saturated iron contained about 15 pct Si and, after about 8 or 10 hr of reaction time at 1600°C, the silicon content of the metal in- creased by about 0.2 pct. In a written discussion on this paper of Fulton and Chipman, schuhmann2 pointed out the possibility that this observed slowness of the reduction of silica could be due to the transport of oxygen across the liquid metal boundary layer at the slag-metal interface. Although this explanation of Schuhmann is quite feasible for the experimental data of Fulton and Chipman on silica reduction, such a reasoning should not be extended to other rate data on slag-metal reactions unless sufficient evidence is available satisfying the boundary conditions for such a transport process. The hydrodynamics of stirred liquids are very complex and even for a simple method of stirring there is no exact mathematical solution which will predict the mass transfer coefficient accurately. The best available solution of this problem is that given by Lewis' and later modified by mayers~ for a two-liquid system where liquids are stirred by counter-rotating stirrer blades without disturbing the interface. In such a system the mass transfer coefficient is estimated from an empirical relationship using the data on viscosity and density of the two liquids, rate of revolution, the length of stirrer blades, and the diffusivity of the element which is transferred from one phase to the other. It was found in these investigations' that the estimated and observed mass transfer coefficients, in systems containing two immiscible aqueous solutions, agreed within *40 pct. Although this is not considered to be an unreasonable error for the study of industrial processes, uncertainties of this magnitude cannot be tolerated in any theoretical study of reaction kinetics. In view of the complexity of the

Jan 1, 1963

By A. D. McMaster, M. L. Gimpl, N. Fuschillo

Low-power, high-speed, radiation-resistant, monolithic thin-film integrated circuits require thin-film resistors of high sheet resistance which are compatible with the processing requirements for monolithic silicon devices. For this purpose the structure and electrical resistance as a function of temperature were investigated for Nichrome-silicon monoxide cermet films on passivated single-crystal silicon substrates. A suitable material was found to be a mixture of 50 vol pct Nichrome-50 vol pct silicon monoxide. This mixture, when evaporated onto 300°C substrates. showed a low temperature coefficient up to 400°C, at both 270 and 1100 ohms per square. Resistors deposited on room-temperature, 300°, and 500°C substrates were heat-treated at 600°C in air for short periods of H- seed, low-power, radiation-re sis tant, monolithic thin-film integrated circuits'-3 require thin-film resistors of high sheet resistance and low temperature coefficients of resistance which are compatible with the processing requirements for monolithic silicon active devices. The present investigation is directed towards the replacement of the Nichrome in the sandwich-type SO2-Nichrome-SiO resistors, currently used for DTL monolithic thin-film integrated circuits, with codeposited Nichrome-SiO cermet resistors. These Nichrome-SiO resistors are provided with an overcoat of SiO and are deposited onto thermally oxidized silicon wafers used in monolithic mi-crocircuit technology. The cermet resistors are shown to provide a lower temperature coefficient of time totaling up to 45 min. Electron nzicrogvaphs and diffraction patterns were taken of the as - deposited and heat-treated films. These results were then compared with electrical-resistance measurements for each condition. The room-temperature and 300°C substrate films showed a large decrease in resistance. The 500°C substrate film remained stable throughout the entire cycle. Electron-microscopy results show that the increased stability after heating to 600°C is largely due to crystallization of the films which begins in the vicinity of 400°C. The slight oxidation of the films when heated in air had a negligible effect on the resistance. The resistance of the film was a function of the substructure. resistance and a more versatile compatibility with silicon monolithic processing. Previous work3, on chromium-SiO coevaporated cermet resistors on glass and ceramic substrates without overcoats of SiO has been reported. For the present application, the thin films should possess the following ideal requirements: a) a temperature coefficient of resistance as near zero as possible up to 300°C; b) have a sheet resistance higher than 200 ohms per sq to conserve space on the chip; c) be easy to evaporate; d) be oxidiation- and radiation-resistant; e) show long-time stability at 100°C; } be stable in N2 atmospheres up to 600°C for short periods of time (5 to 45 min). Requirements a to e are well-known. The last requirement was optional and was due to a mask elimi-

Jan 1, 1967

By Javier Ramirez

"Recent R&D pilot plant testing was done to validate a full industrial scale system for recovering residual magnetite from the tails of an iron ore concentration plant. The recovery system is based on an autogenous heavy media separator treating a tailings slurry at 0.45% solids by weight. A 3,100 m3/h capacity concentrator was installed based on the testing findings. Excellent metallurgical results have been observed in two years of continuous operation. This experience is the basis for the proposal of a novel process consisting of the preconcentration of base metals ores; the idea being to obtain a heavy bulk concentrate of the polymetallic minerals and discarding in one step the light gangue mineral components. The bulk concentrate then proceeds to conventional froth flotation. The reduced volumetric flow of the bulk concentrate allows a reduction in the size of the subsequent flotation circuit. A prerequisite for the heavy media separation is a fine size grinding of the ore and a correspondingly high degree of liberation of the mineral species to be recovered. A process scheme is also presented in which the gravity concentrator works in conjunction with a companion tailings thickener for process water recovery. The underflow from this thickener, having paste consistency, can be sent to a tailings dam or mixed with Portland cement for mine backfill. The process water in the system is managed at an estimated recovery in excess of 98%. Additional R&D work using this novel approach is being considered by a large iron ore concentrator for removal of liberated silica from the final concentrate; and for upgrading 3.5 million tons of a marginal hematite reserve owned by the mining company.INTRODUCTIONGravity preconcentration (static and dynamic) of sulphides prior to froth flotation has been and is being practiced at various concentrator plants (Asarco´s Young Mill: heavy media cone; Mount Isa: DSM cyclone; Afton Mines: Denver jigs; Tsumeb Mine: Reichert cone) (Burt, 1984). The idea behind installing preconcentration equipment is to reduce the volume of feed processed on flotation, thus requiring smaller flotation plants although other advantages may be of importance, such as obtaining richer concentrates due to higher grade feed, better process water and energy management, and reduced flotation reagent consumption.The SedconTM solid/liquid separator is a versatile process unit patented in Mexico (MX/u/2007/000305). As a gravity device, it may be classified as an autogenous heavy media dynamic concentrator. Figure 1 depicts the Sedcon (Sedimentador de conos) separator. The four main components are as follows: the feedwell for efficient mixing of the pulp with dilution water and flocculant (and coagulant for water clarification); the inner cones (passive elements for solid/liquid separation); the discharge underflow cone; and the scraper mechanism. The standard discharge cone is a 60° inclined cone for general applications. For paste tailings thickening applications, a deep cone with a 69° inclined cone is used."

Jan 1, 2016

By W. O. Philbrook, H. W. Hosking, N. B. Melcher

Rates and patterns of gas flow in an experimental blast furnace were investigated by measurements, at three levels, of gas compo-sitions and temperatures and by direct determination of gas transit time by a new method employing mercury vapor as a tracer. Infer-ences were drawn about localized reaction zones and the mechanism of the onset of' channeling. LACK of precise knowledge of the nature of gas movement in the blast furnace has always been an impediment to better understanding of the blastfurnace process as a whole. The effects upon operation of various types of charge distribution are very largely brought about by the modifications to gas flow which they occasion. Intelligent evaluation of these effects demands a better understanding of the factors influencing gas flow and the ways in which the flow pattern is altered by conditions existing in the stock column. The same knowledge is required before a fundamental approach can be made to the problem of establishing optimum lines for new furnaces. An experimental furnace is operated at the Bureau of Mines Central Experiment Station, Pittsburgh, Pa. Advantage was taken of experimental operation to conduct an investigation to develop and evaluate methods of study which could be applied later to industrial furnaces. The gas composition and temperature determinations were made as a preliminary study so far as gas flow was concerned but yielded significant information relating to other processes occurring within the furnace. The direct measurement of gas transit times by the mercury-vapor method constituted the major object of the investigation. Development of the mercury-vapor method was carried out while the data on gas composition and temperature were being collected. A complete description of the principle and development of the mercury-vapor method is beyond the scope of this paper but is available elsewhere. The results obtained and some consideration of the method's effectiveness and its potential value in the study of industrial problems will be treated here. DESCRIPTION OF FURNACE The general lines of the experimental blast furnace are shown in Fig. 1. The hearth diameter was 3 ft at the beginning of the investigation, and this was later enlarged to 3 ft 9 in. and finally to 4 ft to increase capacity. Tuyere to stockline height is 21 ft 4 in. The bosh depth is 3 ft 4 in. over which it opens to a width of 5 ft, and this diameter is carried up for 2 ft in a cylindrical section. The inwall batter of 1/2 in. per ft. is considerably less than in larger installations This may have influenced the movement of gaseous and solid materials. The furnace is inside a laboratory building and is charged from outside by a skip and hoist. Feeding into the first of three bell chambers, the stock is distributed by rotating the upper bell, the other two being used to obtain an effective gas seal. Three water-cooled tuyeres, with a nozzle dia-

Jan 1, 1960

By Potts N. L., Eilerts C. K., Summer E. F.

The second-order, nonlinear, partial- dillerential equation representing the transient radial flow of gas - condensate fluids in reservoirs has been integmted by using finite -dillerence equations and electronic computers. Effect was given to pressure -dependent permeability, viscosity, and compressibility and to distance-dependent permeability. The influence of a second-degree velocity term in the Darcy equation was investigated. Implicit methods were used and practical, convergent solutions were obtained with material balance to less than 6 x 10-4 for recovery of one- hall the reserve at constant flow rate. Integration results provide the productive period of a reservoir for a given constant rate and the fraction of the fluid initially in place that can be recovered in that period. The properties of a lean and a rich fluid are represented in a set of integrations designed to demonstrate the effect of different constant-recovery rates and significant variables emphasized one at a time. INTRODUCTION A method is needed for computing the availability or reserve of a gas in a formation, making use of all technical and engineering information that is pertinent. As a step in this direction, a program for computing transient linear flow1 was developed that utilizes principles of earlier finite-difference computing for a similar purpose2-4 and gives effect to significant pressure- and distance-dependent properties of reservoirs and their contents. The present paper pertains to transient, radial flow of gas-condensate fluids. In the partial-differential equation of flow, effect is given to the variables viscosity and compressibility,5 and also to permeability. Included in the study is the quadratic form of the Darcy equation of flow that has been the subject of field tests6 and that has been applied to a gas with constant properties in transient flow computing. 7 Inclusion in the differential equation of variable coefficients to represent properties greatly complicates the higher derivatives of the equation. Because it was impractical to make a required improvement in certain of the finite-difference derivatives by Taylor-series expansion, five-term derivatives were used in the implicit computing. Related methods were developed that can improve general facility in manipulating finite-difference equations. BASIC EQUATIONS PARTIAL DIFFERENTIAL EQUATION The basic partial differential equation for transient radial flow in the direction of decreasing radius is l_ a(vpr) _? .......(1) r gr at where r = radius, L v = apparent velocity aIong radius, L/t p = density, M/L3 t = time, t Ø = porosity, dimensionless. In this equation, only the porosity is regarded constant. The density is where p = pressure, m/Lt2 M = molecular weight of fluid, m T = constant temperature of fluid, T z(p) = pressure-dependent compressibility factor, dimensionless R = gas Constant, mL2/t2t. The physical boundary of the reservoir is at re, and the producing boundary is defined to be at tq with rq = re /200. By definition,

Jan 1, 1966

By A. Kurkov

Flotation process is based on the formation of primary collector-based supramolecular associates at the mineral surface and within the pulp. Supra molecular chemistry allows studying within a common framework, all kinds of molecular associates, from dimers to large assemblies, resulting from spontaneous association of a large number of interacting components of the flotation system, where the collective action of non covalent bonds can have an important role. Self-organization of supra molecular assemblies in the flotation process can be controlled by modifying the chemical structure of the collector, the nature and arrangement of functional group in it, by introducing secondary agents (SA) into the process, to adjust the interaction between the collector and the surface and to control the hydrophobicity of the adsorption bed. This offers broad opportunities to build supramolecular assemblies to improve the efficiency of flotation. Besides, the more complex is the system, the weaker are the interactions, that determine its behavior. This powerful factor still is not employed deliberately to control the flotation process. Organophosphorus compounds (OPC) - dialkyl phosphoric acids whose radicals contain ethoxylated groups ? are considered as nanocompounds, that can be used in building supramolecular assemblies. The presence in an OPC molecule of functional groups (P=O, P (O) O-, P (O) OH), ethoxylated groups, and aromatic rings is the basis for the formation of stable supramolecular associates. Gross formula: C54H94KO16P. Molecular weight is 1069.39. Phosphoryl anion has a regular tetrahedral structure with the angle of 109.5°. Lengths of -P-O- bonds in a PN molecule are 1.7345Å; length of the hydrocarbonic radical C42-C72 = 33.942Å. In an alkaline environment, PN is in the form of the anion, in an acidic environment ? in the form of the polycation due to protonation of the oxygen in the EO group. Chem Office software suite was used to generate three-dimensional images of an OPC molecule in acidic and alkaline environments, to reveal the OPC geometry (bond lengths, valence angles, aliphatic radical length), to identify the collector's binding sites with the mineral surface, to find the most stable and energy-efficient molecular conformations of an OPC molecule and its complexes with minerals under various conditions. Mechanisms of interaction between OPCs and the mineral surfaces are different. In ores whose minerals are dominated by ionic bonds (fluorite), the interaction mainly involves the anionic form of the collector; in ores, whose minerals are dominated by covalent bonds - the oxygen of the phosphoryl group (donor-acceptor interaction) and the oxygen of the ethoxylated groups. This difference is responsible for the formation of spatial associates with different surface layer structures. Introduction of supramolecular chemistry concepts into the analysis of flotation phenomena and mechanisms can become an effective tool for better understanding the flotation process and offers new means of consistently improving its effectiveness.

Sep 1, 2012

By B. G. Reisdorf

This paper describes the microstructural changes that occur when quenched ultrahigh-strength steels containing OA pet C and various amounts of nickel, silicon, and cobalt are tempered. The changes that occur in hardness, yield strength, and martensite diffraction-peak widths when these steels are tempered are related to the precipitation of the carbide phases. An unea$ectedly high silicon content (about 30 pct) was found in the E -carbide phase in a steel containing only 1.5 pct Si. TEMPERED martensitic steels have such wide-spread utility that they have been the subject of numerous investigations, and a sizable amount of literature has developed on this subject.M This investigation, which is a part of a larger program to correlate microstructure with mechanical properties at a variety of strength levels, is limited to the microstructural changes that occur when a quenched 0.40 pct carbon steel (USS Airsteel X-200 steel) is tempered, and to the effects of the alloying elements—nickel, cobalt, and silicon—on these microstructures. Used in this investigation were electron microscopy, electron-diffraction identification of the carbide phases, electron-probe micro-analysis of the carbides, X-ray determinations of retained austenite, and measurements of martensite X-ray diffract ion-peak widths. MATERIALS AND METHODS The chemical analyses of the eight heats examined eats No. 30 through 37) are shown in Table L Heat No. 30 has the chemical com~osition of Airsteel X-200, and the remaining seven heats contain various amounts of nickel, chromium, cobalt, and silicon. The heats were air-melted in an induction furnace and cast into 8 by 8 in. ingots that were subsequently heated to 2300 and rolled to 1-in.-thick plate. Oversize 0.505-in.-diam tensile specimens were rough-machined from the plates and austenitized in air at 1700° F for half an hour and oil-quenched. The specimens were then tempered in air at temperatures of 400° to 1000 for tempering times of 1, 4, and 16 hr, and finish-machined to 0.505-in.-diam tensile specimens. Electron micrographs were prepared from Formvar replicas of the midthickness of tensile-specimen shanks that had been electrolytically polished and etched in nital. Electron-diffraction patterns were obtained from carbon-extraction replicas. The replicas were prepared by etching the sample surface in the same manner as for microscopy, evaporating carbon on the etched surface, and re-etching the sample to free the carbon film and the precipitate particles. Electron-probe microanalysis was performed on some of the extraction replicas. To obtain adequate fluorescent X-ray intensities, several thicknesses of replica were exposed to the electron beam so that the results represent an average composition of the extracted particles rather than an analysis of single precipitate particles. The retained austenite contents of the specimens were determined by an empirical X-ray diffraction

Jan 1, 1963

By A. W. Dana, F. J. Shortsleeve, A. R. Troiano

The phenomenon of flake formation which may occur during cooling or room temperature aging of large steel sections is caused by a combination of hydrogen and stress. As such, the transformation characteristics of austenite in a particular section play a major role in the occurrence of flakes. Isothermal and continuous cooling studies demonstrated that flake formation is particularly sensitive to nature, distribution, and relative proportions of the microconstituents in the cooled sections. In the absence of transformation stresses, abnormally high hydrogen contents could be tolerated without flaking. Flakes were not found in the absence of transformation stresses. No correlation existed between average hydrogen content and flake formation where cooling stresses were low. Hydrogen in the steel was a necessary but not sufficient condition for flake formation. DESPITE a long history of laboratory and commercial investigations, the mechanics of hairline crack or flake formation in large steel sections remains unresolved. Recent publications1-5 emphasize that flaking is still a serious problem.* immediate cause of flaking is the pressure exerted by entrapped hydrogen gas that collects in small internal cavities or voids during cooling. When the temperature of steel is low enough to preclude extensive plastic flow, the cavity pressures cause local brittle fractures (flakes). 2—The microsegregation and transformation stress theory. According to this theory, flaking results from stresses arising from the volume changes accompanying the formation of martensite and/or low temperature bainite after a large portion of the section has transformed at elevated temperatures. The proponents of the hydrogen theory suggest that stresses from other sources may be additive to the stresses produced by hydrogen and may, in some cases, provide the increment of stress necessary to produce flakes. However, the critical aspect of this theory is that no stress, except that produced by hydrogen pressure, is believed to be sufficient in itself to produce flakes. For practical considerations, this means that the only safe thermal cycle is one that reduces the hydrogen content to some low critical level below which flaking will not occur regardless of the state of transformation. On the other hand, the transformation stress theory does not rule out the embrittling effect of hydrogen. This theory simply proposes that flaking does not occur in the absence of transformation stresses. With the transformation stress theory as a basis, commercial antiflaking cycles would be designed to complete the transformation of austenite prior to cooling to ambient temperatures. Both of these theories appear compatible with industrial experience. Antiflaking cycles, such as cooling at extremely conservative rates or soaking for periods of time in the upper subcritical temperature ranges prior to cooling to ambient temperatures, may allow the following: 1—diffusion of hydrogen out of the section and, as a consequence, reduction of the hydrogen content to some safe minimum value (hydrogen pressure theory) and 2—complete decomposition of the austenite at rela-

Jan 1, 1956

By S. -H. Jeon, Y. -S. Choi

"The three dimensional current distribution on the rectangular cathode is predicted using a boundary element method with a linear element of trigonal type. The effect of cell geometry and anode shape on current distribution is simulated. Calculated results compare well with experimental results. The proper combination of anode size and distance between electrodes increase the current uniformity.The importance of electrodeposition as a fabrication technology in the electronics industry is large and growing. The main advantages of this wet processing method, in comparison to other dry processing methods, lie in its high yield, rapid processing and low cost. In nearly every application of electrodeposition the pursuit of deposit uniformity, especially thickness uniformity, has been technically imperative. The thickness uniformity of the deposit depends largely on the current distribution over the cathode. The current distribution is primarily determined by the geometrical characteristics of the electrodes and the cell. Also the polarization at the electrode surface and the mass transfer affect the current distribution.The current distribution is an important consideration for those involved in designing electrochemical systems and electroplating systems in particular. Although it is important, the common practice in industry is to use trial and error method to design the cell that optimize the uniformity of current distributions in electroplating. The purpose of this paper is to illustrate the useof boundary element method to predict three-dimensional current distribution in rectangular cell.The calculation of the current distribution is possible by various numerical techniques, which include the finite difference method (FDM)1, the finite element method (FEM)2, and the boundary element method (BEM)3,4. These methods of the numerical calculation have various problems, respectively, but the BEM is considered to be the most efficient. This is due to the fact that the BEM has the advantage of solving field equations only on the surface of a calculation domain. A good comparison between the BEM and the FEM for the secondary current distribution in a Hull cell was made by Matlosz et al.5The fundamentals on the theory of current distribution in electroplating are well-established in the literature by a number of authors.6, 7, 8 However, a small fraction of these works have been specially addressed to three-dimensional analysis, and, mostly thel·10 have focused on the problem qualitatively rather than quantitatively.Extending the previous work to three-dimension, we developed the program for the quantitative calculation of 3-dimensional current distribution using a boundary element method with a linear element of trigonal type. Integrals with singularity from the fundamental solution have been analytically computed and it is shown in detail in the Iiterature11. This paper deals with the three dimensional current distribution for the electrode position of copper in a cubic type cell and the effect of anode shape, size and the distance between electrodes on current distribution is studied."

Jan 1, 1997

By L. Albert, A. M. Cameron, J. W. Gullick

International Nickel has 15 operating mines in Canada, and. 3 mines which are being maintained on a standby basis. Annual production is about 20 million dry short tons of ore, most of which is from underground mines, the remainder from open pit mines. Although some of the underground mines are served by ramps for trackless vehicles, most men, materials and ore are hoisted in vertical shafts. In addition to shafts and raises for ventilation and service purposes which are not equipped with hoisting plants, there are now 28 vertical shafts at Inco mines served by 47 hoists. Of these, 22 shafts and 36 hoists are located in the Sudbury District of Ontario, one shaft and two hoists are at the Shebandowan mine in Western Ontario, and 5 shafts with 9 hoists are located near Thompson, Manitoba. This paper describes the components of Inco hoisting plants-which have been applied at different times and under different conditions, and indicates the rationale for the various designs. Some engineering and maintenance practices, considered advantageous, are also described. MINE SHAFTS Many of the shafts sunk in the early days of the Sudbury District, on what are now Inco properties, were inclined shafts. Of the identifiable shafts sunk between 1885 and 1920, thirteen were inclined and at least four were vertical. Since 1920, thirty vertical and two inclined shafts have been sunk. All of the inclined shafts have been abandoned for hoisting purposes but the majority are still in use as service or ventilation ways. Shafts at Thompson- and Shebandowan are all vertical. The vertical shafts range from 2 or 3 compartment exploration and development shafts to 6 compartment shafts for ore, man and material hoisting. They vary in depth from 1,050 to 7,137 feet and in addition to hoisting compartments all contain manway and service compartments. Prior to 1948, unlined rectangular shafts with timber sets and guides were used. The rectangular cross-section was favoured since the rock is competent, the shape compatible with timber set framing, and since available shaft space could be used efficiently. Resistance to air flow was not of prime importance. Concrete linings were introduced for the first time at the Creighton No. 7 Shaft which was collared in 1948. All major shafts since that date have been concrete lined. Vertical set intervals were increased in steps, with the introduction of structural steel sets secured to the concrete linings. Whereas 7 foot set intervals were used with timber framing, this increased to 10 feet 6 inches with steel sets and more recently to 15 feet with steel and steel backed wood guides. With the advent of deeper shafts, or shafts which are expected to be deepened, the trend is to circular concrete lined shafts. The majority of shaft guides in service are of select Douglas Fir. This practice commenced as a component of timbered shaft design but continued as a

Jan 1, 1975

By A Fareth

Constructed between 1885 and 1891, the New Croton Aqueduct (NCA) in New York State is a 50 km long (31 mi) brick-lined tunnel conveying water from the Croton watershed north of New York City to distribution systems in the Bronx and Manhattan. Except at two siphons, the aqueduct operates as an open channel conduit from the New Croton Reservoir downstream 39 km (25 mi) to the Jerome Park Reservoir in the Bronx. The remaining 11 km (6 mi) is operated as a pressurised conduit and includes a major siphon, of circular cross-section, under the Harlem River. The aqueduct has a flow capacity of approximately 1100 million litres of water per day (13 m3/s or 290 million gallons per day) and supplies on average ten per cent of New York CityÆs drinking water. The CityÆs water supply system is operated and maintained by the New York City Department of Environmental Protection (NYCDEP). This paper covers the work done during the three main stages of the program to rehabilitate the entire NCA: inspections, design and rehabilitation. It also includes some of the more interesting structural findings of the original construction as well as documents and drawings from the NYCDEP archives. The rehabilitation program has been underway in phases since 1993, with inspections scheduled to minimise outages, allowing this strategic aqueduct to remain in service during critical seasonal periods. The open channel flow section of the aqueduct in the north is horseshoe shaped, with inside dimensions of 4.1 m (13.6 ft) in width and 4 m (13.5 ft) in height. The pressurised section is 3.7 m (12.3 ft) in diameter, and includes a 90 m (330 ft) deep siphon under the Harlem River. A total of 163 million bricks were used in the construction, enough to build a 48 km (30 mi) wall around Manhattan Island, 3 m (10 ft) thick and 15 m (50 ft) high.Between 1993 and 1997 a series of in-tunnel investigations were performed in the open channel portion of the NCA, consisting of field inspection, non-destructive geophysical testing, and coring of the brick liner. Between November 2004 and September 2005, a major inspection program was conducted to assess the condition of the 11 km (6 mi) long pressurised section and all shafts, headhouses and blow-off structures along the entire 50 km (31 mi) alignment. Inspection methods included using an underwater remote operated vehicle (ROV) equipped with sonar and cameras to inspect the deep siphon, fibre optics examinations of probe holes drilled through and beyond the brick lining, and core holes and geophysical inspections to assess properties of the liner and behind-the-liner materials. A water pressure and test grouting program was conducted to assess methods and expected grout takes for the rehabilitation work in the pressurised sections. The rehabilitation program is anticipated to be completed in 2010.

Jan 1, 2008

By Arthur Lubinski, K. A. Blenkarn

It is explained why the bottom portion of freely suspended tubing in a pumping well buckles and straightens in succession during the pumping cycle. Field evidence of resulting rod-on-tubing wear, excessive polished rod load, and excessive horsepower are given. The possibility that buckling hastens pump wear is strongly suggested. Means for either prevention of buckling or for mini-mizing its effects are explained, their relative merits compared, and field results of their use given. These means are: tension anchors, tail pipe, sucker rod guides, and corrosion inhibitors. Charts and formulas for best use of tension anchors, tail pipe, and guides are given. Use of tension anchors, or compression anchors with a heavy tail pipe, prevents both buckling and breathing, thus improving volumetric efficiency. Without tail pipe, buckling above compression anchors precludes such improvement. INTRODUCTION It is well known that a column must be subjected to some compression in order to buckle; and also that a structural member does not buckle if subjected to a tension. When consideration is given to a tubular column, the question may be asked, "How is the buckling phenomenon affected by inside or outside pressure?' At first, it seemingly should not be affected. However, this is not so. In order to arrive at a correct deduction one should first understand the basic reasons for buckling of a column under loading*. Then he should add to the effect of that loading the effect of pressure. Following this procedure, one may discover quite unexpected phenomena. In some cases, when subjected to more pressure inside than outside, a pipe may buckle under tension. In other cases, a pipe may remain straight, although subjected to a very large compression. In 1950 and 1951 it was explained why the bottom portion of a string of pipe freely suspended in a well does not buckle even when subjected to a large compression due to buoy- ancy.2,3 It was shown that the com-monly used concept of a neutral point, as being a point in the string with neither compression nor tension, is inadequate, and a more relevant definition of the neutral point was introduced. The findings were also generalized to cases of different pressures inside and outside a pipe.3a Later, in a further generalization, allowance was made for variations of stress and pressure with depth.' The findings were applied to the new technique of hydrostatic high pressure testing of lengths of pipe in the mill.5 In 1952 it was observed that previous theoretical findings apply to tubing in pumping wells. The lower part of freely suspended tubing buckles during the upstroke portion of the pumping cycle. Later, it was ascertained that this phenomenon is responsible for wear and malfunctioning of the equipment. Various remedial measures were devised and successful field trials conducted. Only brief mentions on the subject have been published.6,7 In this paper, the phenomenon of tubing buckling is explained, field

Jan 1, 1958

By R. S. Goodrich, G. S. Ansell

The microstructure of three Al-Al2O3 SAP-Type alloys (containing 2.0, 3.0, and 5.7 wt pct alumina, respectively) was studied utilizing transmission electron microscopy. These alloys were fabricated from aluminum powders by powder-metallurgical techniques, cold-rolled into thin strips, and recrys -tallized. Thin foils suitable for an electron-transmission study were then prepared from the strip material by electropolishing. The microstructure of these alloys is shown to consist of small (0.1 mean diameter) plate -shaped alumina particles finely distributed in an aluminum matrix. In the higher-oxide content alloys the platelets are somewhat larger and more irregular in shape. The distribution of oxide particles is not uniform and there is an increasing tendency toward clumping SINCE the discovery by Irmann1 that aluminum alloys produced by compacting, hot pressing, and extruding fine aluminum powders possess remarkable high-temperature mechanical properties, the Al-A12O3 SAP-Type alloys have been utilized extensively as model dispersion-strengthened alloys in both experimental and theoretical invest igations.2-8 The use of the SAP-Type alloys as model dispersion-strengthened alloys implicitly assumes that their microstructure has been completely delineated. This is, however, not the case. with increasing oxide content. In all the alloys studied, the mean center-to-center spacing of particles was quite small (0.2 u) due to the very fine oxide debris present. Selected-area diffraction of the specimen identified the oxide as either y Al2O3 or y' Al2o3. The re crystallized MD-5100 alloy exhibited a mean grain diameter of only 0.7u, while the grain size of the other alloys was several hundred microns. Severe pinning of the grain boundaries by oxide particles was rarely observed, and the grain boundary triple points in the small-grained MD-5100 alloy were often particle -free. Diffraction contrasts visible around the particles are attributed to elastic strain fields set up by differential thermal contraction during cooling from the recrystallization anneal. Early investigation demonstrated that optical metallography did not possess sufficient resolution to observe the microstructure of the SAP-Type alloys.' Later, extensive use was made of replication techniques to study the microstructure by means of electron microscopy.7-9 These studies indicated that the SAP-Type alloys consist of a dispertion of irregular Al2O3 platelets, approximately 150A thick 9 and a micron or so on edge,9 distributed in a matrix of commercial-purity aluminum. These oxide platelets tend to be oriented in the aluminum matrix, with their largest dimension parallel to the extrusion direction. 8,9 A study employing polarized-light techniques1' indicated that the grain size of a series of as-extruded SAP-Type alloys was several microns in diameter, while the grain size after re-crystallization was several millimeters in diameter. A more recent study 12 utilizing surface-replication techniques examined the particle morphology,

Jan 1, 1964

By J. D. Hanawalt, C. E. Nelson, J. A. Peloubet

The subject of the salt-water corrosion resistance of magnesium alloys is somewhat like that of the pitting of stainless steels, in that it involves a relatively small. percentage of the applications but receives a much greater proportion of the publicity. Actually magnesium alloys are in use in many exterior applications as well as interior, with no trouble from corrosion. Magnesium and its alloys have a striking stability against atmospheric attack, being far superior to iron. Specimens exposed unprotected to atmospheric weathering for Io Years show only a superficial surface-film formation. The basic nature of magnesium and of its important alloys is that they are also resistant to the attack of salt water even in an unprotected state, giving substantially no loss in weight after one year of alternate immersion in 3 per cent NaCl solution (Fig. 1). This basic behavior is often masked because of the extreme sensitivity of these alloys to certain impurities and combinations of impurities. It is known, and the subject of increasing emphasis, that higher purity leads generally to greater stability for many materials, non-metallic as well as metallic. However, a review of the literature on the corrosion factors in magnesium alloys shows that almost all researchers worked with base metal in which metallic impurities varied in uncontrolled amounts. The major factor, that of metallic impurities, Probably greatly overshadowed the effects of minor ones such as flux inclusions, nonmetallic impurities, porosity, metallographic state, which these researchers presumed to study. In the present investigation the first observation of interest is that whereas magnesium of commercial purity (99.9 per cent pure) has a corrosion rate in alternate immersion in 3 per cent NaCl solution at room temperature of anywhere from 5 to Ioo mg. per sq. cm. per day, the corrosion rate of high.purity magnesium is 0.15 ± 0.05 mg, per sq. cm. per day. The principle followed in the experiments was to add to such base magnesium other elements, singly and in inin in controlled and known amounts and to observe the corrosion behavior of the resulting alloy. These experiments show the existence of what may be called tolerance limits" of magnesium and some of its alloys for certain impurities. The extremely small percentages of impurities involved and the sharpness of the corrosion discontinuities appear to be quite unpredictable, In order to carry on this work, it was necessary to develop an analysis technique suitable to the problem. In some cases it was necessary quantitatively to analyze impurities to less than 0,001 per cent. The experimental data to be presented are based on observation of about 5000 alloy specimens and on more than 50,000 quantitative analyses. while the primary purpose of this paper is to present the experimentally obtained data on corrosion rates as a function of composition, and particularly to demon-

Jan 1, 1942

By J. D. Hanawalt, C. E. Nelson, J. A. Peloubet

The subject of the salt-water corrosion resistance of magnesium alloys is somewhat like that of the pitting of stainless steels, in that it involves a relatively small. percentage of the applications but receives a much greater proportion of the publicity. Actually magnesium alloys are in use in many exterior applications as well as interior, with no trouble from corrosion. Magnesium and its alloys have a striking stability against atmospheric attack, being far superior to iron. Specimens exposed unprotected to atmospheric weathering for Io Years show only a superficial surface-film formation. The basic nature of magnesium and of its important alloys is that they are also resistant to the attack of salt water even in an unprotected state, giving substantially no loss in weight after one year of alternate immersion in 3 per cent NaCl solution (Fig. 1). This basic behavior is often masked because of the extreme sensitivity of these alloys to certain impurities and combinations of impurities. It is known, and the subject of increasing emphasis, that higher purity leads generally to greater stability for many materials, non-metallic as well as metallic. However, a review of the literature on the corrosion factors in magnesium alloys shows that almost all researchers worked with base metal in which metallic impurities varied in uncontrolled amounts. The major factor, that of metallic impurities, Probably greatly overshadowed the effects of minor ones such as flux inclusions, nonmetallic impurities, porosity, metallographic state, which these researchers presumed to study. In the present investigation the first observation of interest is that whereas magnesium of commercial purity (99.9 per cent pure) has a corrosion rate in alternate immersion in 3 per cent NaCl solution at room temperature of anywhere from 5 to Ioo mg. per sq. cm. per day, the corrosion rate of high.purity magnesium is 0.15 ± 0.05 mg, per sq. cm. per day. The principle followed in the experiments was to add to such base magnesium other elements, singly and in inin in controlled and known amounts and to observe the corrosion behavior of the resulting alloy. These experiments show the existence of what may be called tolerance limits" of magnesium and some of its alloys for certain impurities. The extremely small percentages of impurities involved and the sharpness of the corrosion discontinuities appear to be quite unpredictable, In order to carry on this work, it was necessary to develop an analysis technique suitable to the problem. In some cases it was necessary quantitatively to analyze impurities to less than 0,001 per cent. The experimental data to be presented are based on observation of about 5000 alloy specimens and on more than 50,000 quantitative analyses. while the primary purpose of this paper is to present the experimentally obtained data on corrosion rates as a function of composition, and particularly to demon-

Jan 1, 1942

By James W. Halley

' FINE-GRAINED " steels have been standard products for many years. This paper describes an investigation of the effects of some of the more common grain-growth; inhibitors used to produce these steels. The properties, response to heat-treatment, and the deoxidation practice necessary to produce "fine-grained" steels have been the subjects of numerous papers. It has been shown that a substantial quantity of' aluminum is necessary to produce this type of steel, and it has been indicated that titanium and zirconium produce a similar result. For some time there was a lively argument between those who felt that aluminum refined the grain and those who felt that aluminum oxide was the effective agent. This argument subsided with an apparent victory for those promoting aluminum oxide. Most of the work on grain size has divided steels into two broad classifications based upon McQuaid and Ehn's original carburizing test at 1700°F. or some similar test at this temperature. If the steel coarsened at this temperature, it was coarse grained, while if it did not it was fine grained. Quantitative data concerning how much a certain amount of aluminum raised the coarsening temperature and affected the properties, all other factors being constant, are very meager. Similar information regarding titanium and zirconium is practically nonexistent. The published information on aluminum yields some quantitative information. Epstein, Nead and Washburn' gave the first quantitative information on the amount of aluminum necessary to prevent grain growth at 1700°F. They showed that the addition of a pound to a pound and a half of aluminum per ton (0.05 to 0.075 per cent) would assure steel that would not .coarsen during a McQuaid-Ehn test at 1700°F. Herty, McBride and Hough2 reported that a steel containing 0.020 per cent acid-soluble aluminum coarsened between 1742° and 1832°F., while steels containing 0.016 per cent and 0.017 per cent acid-soluble aluminum coarsened between 1652~ and 1742°F. compared with similar aluminum-free steels that started to coarsen at 1580°F. Herty3 also showed a marked improvement in low-temperature notched impact resistance with increasing acid-soluble aluminum up to 0.030 per cent. McQuaid4 compared the coarsening of steels containing 0.011 to 0.204 per cent total aluminum and found a maximum coarsening temperature at 0.098 per cent aluminum. He had no samples between 0.015 and 0.098 per cent aluminum. Houdrement5 found a marked decrease in coarsening temperature with aluminum contents above 0.50 per cent. Kinzel, Crafts and Egan6 found that aluminum and zirconium improved thy low-temperature impact resistance of a low-alloy steel, while titanium was detrimental. Sims7 shows that sulphur increases the coarsening temperature and that the maximum coarsening temperature is between 0.04and 0.06 Per cent added aluminum. The

Jan 1, 1946