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ALBERT J. PHILLIPS, Chairman E. H. Dix, JR., Past-chairman R. H. LEACH, Vice-chairman R. F. MEHL, Vice-chairman W. M. COME, Treasurer LOUIS JORDAN, Secretary 29 West 39th St., New York, N. Y.

Jan 1, 1937

By David L. Holt, Walter A. Backofen, Anwar-uI Karim

Specimens of a hydrided Mg-0.5 Zr alloy were strained in tension at 500°C and constant rates of 2 x10-3 5 x 10-3, and 2 X 10" min-1. Hydride-denuded zones formed at grain boundaries normal to the tensile-stress direction as a result of magnesium transport during difusional flow. The width of the zones could be measured and the measurement used for calculating the diffusional component of the imposed tensile strain. The strain from diffusional flow was found to increase with imposed strain at a diminishing rate, tending to saturate at approximately 12 pct. Strain rate sensitivity of flow stress was low. The apparent non Newtonian character of the diffusional flow is attributed to a non Newtonian process acting in parallel with it which could be boundary shear. Fracture grows out of voids that form in the denuded zones. DEFORMATION of a grain by diffusion of atoms from boundaries stressed in compression to boundaries stressed in tension is Newtonian viscous,1-3 and evidence has accumulated in recent years that such a process may be responsible for the high strain-rate sensitivity of the flow stress of super-plastic alloys.4"7 One piece of evidence is that experimental stress: strain-rate relationships can be quantitatively explained.5-7 There is also metallo-graphic evidence of diffusional flow in superplas-ticity, but in a limited amount. The formation of striated bands on the surface of superplastically deformed specimens has been attributed to diffusional flow.5"7 The basis of that attribution came from experiments on a coarse-grained, nonsuperplastic and hydrided Mg-½ wt pct Zr alloy which formed hydride-denuded, light etching zones at tension-stressed boundaries when strained in tension at 270?C.6 The origin of these zones had already been traced to the diffusional flow of magnesium atoms to the boundaries.' The particular observations in the more recent work were of striated-band formation on the surface and denuded-zone formation internally, with both the bands and zones having the same width and appearing at tension-stressed boundaries. It was argued that the bands were a surface manifestation of the zones and hence of diffusional flow. Of course in superplastic alloys which do not contain internal metallographic "markers", the surface bands can be the only metallographic indication. In the present work, denuded-zone formation was utilized, as it has been by others,9-11 to extend the observations of diffusional flow and to measure the strain, ed, resulting from it. Grain size had to be large to measure ed with accuracy. The grain size chosen for this study was -30 , and with that a strain of 10 pct from diffusional flow produces a denuded zone only 3 µ in width. The large grain size naturally precludes superplasticity. The observations of diffusional flow were complemented by determining the strain from the other operative deformation modes: slip, e,, and grain boundary shear, egb. An incremental specimen extension is the sum of increments from slip, and grain boundary shear as well as diffusional flow. Division by a common length is required to convert to strain. If this length is taken as the initial specimen length, then imposed engineering strain, e, is given in terms of the component engineering strains by e = ed + es + egb [1] Stress:strain-rate relationships are determined by the way in which this "strain balance" is made up. EXPERIMENTAL Material. Zirconium hydride markers were introduced into the Mg-0.5Zr alloy by annealing in hydrogen at 450°C for 30 min. The hydride concentration was particularly high at zirconium rich stringers, which was fortunate in that the transverse boundaries at which denuded zones form lie perpendicular to the stringers. Grain size after annealing was 30 µ. Photomicrographs of unstrained and strained material are shown in Fig. 1. Procedure. Specimens were strained in tension with an Instron machine at crosshead velocities of either 2 x 10"3, 5 x X or 1 x 10-2 in. min-'. Specimen length and diameter were 1.0 and 0.2 in., respectively, so that initial strain rates in tests at constant crosshead speed were 2 x 10"3, 5 x X and 1 X l0-2 min-1. Tests were made at 500°C which is a compromise temperature at which diffusional flow is still measurable but grain growth is not active enough to interfere with metallographic measurements. The tests were made in a hydrogen atmosphere. Strain Balance. An equation additional to [I] is eg = ed + es [2] where eg is strain measured from grain elongation. Measurement was made of ed, eg, and, of course, e, which enabled all the strains in Eq. [I] to be determined. For this purpose, strained specimens were sectioned longitudinally, polished, and etched. The strain from diffusional flow, ed, was computed by measuring on photomicrographs the width in the tensile direction of denuded zones at either end of a grain XI, X2, adding them, and dividing by twice the initial longitudinal grain dimension L0, Fig. 2. Reported values are the results of measurements on seventy randomly selected grains; 95 pct confidence limits on ed were +1.5 pct strain. To measure eg, the maximum length, L, and the maximum width, W,

Jan 1, 1970

YOU must know, my Messer Bernardino, that all things in this world made by art or produced by Nature are made only for their own specific purpose. If there should be any that perchance should fail therein, they would be useless and imperfect, and those are in a state of imperfection that should have it and have not yet arrived at it. Thus, in short, when you have dug out the ore with so much labor and extracted the metals, when you have made from copper (in addition to other works) guns that are ready for military service and have then put them on

Jan 1, 1942

By W. D. Douglas, M. J. Hampshire, G. J. C. Young

This paper describes the replacement of a conventional filtration, clarification, and zinc precipitation plant by a carbon-in-pulp (CIP) electrowinning plant, with the objective of improving the recovery of gold from cyanide leached, acid plant calcines. The discussion covers early laboratory studies to the design and erection of the full-scale plant. Particular emphasis is placed on the problems encountered with commissioning and the strategies employed to solve them.

Jan 1, 1985

By W. H. Gauvin, N. J. Themelis

Jan 1, 1963

By F. Cadena, Fred C. Bond, Walter L. Maxon

Grinding is one of the major problems in present-day milling practice, and in many cases, it represents one of the main items of expense. It becomes necessary from time to time, to compare grinding practice in one plant with that in another plant, and in making such comparisons, it would be very desirable were there available accepted standards of grinding resistance for the materials involved. Such a set of grinding constants would also be of considerable value in planning new grinding installations. There have been some tests published, notably those of Lennox,' which have been generally cited as a basis for such comparisons. Most of the tests made have been based upon open-circuit grinding, in which a weighed sample of the ore was crushed to pass a certain mesh, and was then ground under certain conditions, either wet or dry. Grinding was continued until a certain desired fineness was attained, and the comparisons based on the grinding time, or the samples were all ground for a certain specified length of time and comparison based upon the screen analysis of the products. Such methods have been acceptable where the ore was to be ground in open circuit. However, in modern milling practice, many grinding problems involve closed circuits wherein the oversize returns to the mill and a large circulating load builds up. A method of testing that does not take the circulating load into consideration might yield results quite different from those to be expected in practice, because the minerals in the ore that offer maximum resistance to grinding will accumulate in the circulating load up to an equilibrium value. Thus the nature of the ore charge in the mill at any instant may differ greatly from that of the new feed, with a consequent error in the rate of grinding determined by such a method. For example, let it be assumed that an ore to be tested consists of equal parts of difficult grinding mineral and easy grinding mineral. This is to be compared with an ore used as a standard, and consisting of minerals which are all of about the same grindability. If a comparison

Jan 1, 1935

By Friedrich Wellmer

INTRODUCTION The Ramsbeck Pb/Zn Mine is located in the northern Sauerland area of West Germany, 150 km N of Frankfurt and 120 km E of Cologne. This is a vein deposit which has been worked from the middle of the 19th century to 1974. About 15 million tons of ore were mined and milled. The ore district contains several vein deposits and is roughly 14 km in length and 4 to 5 km in width. The host rocks are strata of Lower Middle Devonian age. The strata strike 60° to 70° NE and where overturned have a dip steeper than the veins (Fig. 1). The galena-sphalerite mineralization is in quartz veins, which are mineralized where they cut the "Main Ramsbeck Quartzite" horizon, a very competent host rock. Vein structures strike at 65º to 75º, dip about 20° to 25º SE and cut the quartzite at approximately 60 m intervals. The main or "steep veins" within each vein structure dip at 10º to 80° SE with an average of 30° and are offset by thrust faults dipping 5º N to 40° S with an average of 5º S. "Flat veins" usually weakly mineralized occur in the thrust faults between the "steep veins", thus forming the overall step-like vein structure. The mineralization is very irregular and changes a- long strike and down dip. It consists of thin veins of pure sphalerite and galena with quartz and pyrite. The thicknesses of the pure sphalerite and galena veins

Jan 1, 1977

By E. H. Crabtree, T. C. King

The ferrosilicon grinding unit at the Central Mill of the Eagle-Picher Mining & Smelting Co. near Picher, Okla., was completed in March 1947. The object of the plant was to grind pigs of ferrosilicon, having a size of approximately 1½ by 4 by 12 in. and an analysis of 85. pct Fe and 15 pct Si, to approximately 100 mesh by crushing and wet grinding in a ball-mill classifier circuit. The minus-100 mesh ferrosilicon had formerly been purchased, and was used as medium in the heavy media process for treatment of lead-zinc ores. From the standpoint of dollars and cents, the cost of minus-100 mesh ferrosilicon was roughly $40.00 per ton more than pigs of the corresponding alloy delivered to the mill. Estimated wet grinding costs were considerably below this figure. The possible saving in cost of make-up medium for the cone plant was particularly attractive since, at that time, the plant losses averaged over four tons of minus-100 mesh ferrosilicon per day. Aside from the probable saving on the grinding charge, the need for such a unit was twofold. First, periodic fluctuations in the differential between the top and bottom densities of the cone were thought to be detrimental to metallurgy. There was little doubt that an intermediate differential existed at which the heavy media separa- tion was most efficient, representing a compromise between concentrate grade and tailing loss. Furthermore, if a finer, but considerably cleaner, medium could be obtained, there was the possibility that the differential could be decreased without increasing the viscosity, or conversely, the viscosity of the medium decreased without increasing the differential. Preliminary to experimental work aimed at pegging the cone differential and circulating medium viscosity at whatever values were found to be most efficient, it was essential to have control over both the nonmagnetic content of the medium and the particle size of the contained ferrosilicon. The latter was possible by means of a grinding unit at the mill. Second, whereas the ferrosilicon alloys are made by a number of manufacturers, only two, to our knowledge, grind it in any quantity for use in heavy media plants. For all practical purposes, the Central Mill was limited to one source of supply, a particularly vulnerable position. In case the supply was cut off, it was thought that pigs of the 85 pct Fe, 15 pct Si alloy could be obtained elsewhere, providing means of grinding them was available. There was no published information available covering wet grinding of ferrosilicon. Dry grinding in batch mills and in continuous mills with air classification was being practiced, but the cost of grinding was excessive and the dust condition objectionable. It appeared that primary and secondary crushing was no particular problem, providing heavy duty equipment was used;

Jan 1, 1949

Butte Meeting. It is expected that the technical program of the Butte meeting will be a sufficient attraction to draw to that point every member who can possibly get away long enough to attend. Attention is particularly called to the papers already sent in by the Committee on Precious and Base Metals, and the papers which they are undertaking to secure for the meeting, as published on pp. ix and x. In addition to these papers, and in addition to those published in this Bulletin, the office of the Institute already has in hand several papers, which will be published at an early date, and presented in abstract and discussed at the meeting. Of the discussion of these papers a special feature is being made. Therefore, let every member come to Butte who can do so. A meeting of the Board of Directors of the Institute will also be held at Butte. In the May Bulletin, we stated for the information of members the railway excursion rates for two suggested tours in connection with the meeting, which included Glacier Park before the meeting and Yellowstone after it. The itineraries there given and rates quoted were planned and offered by the railway agent bureaus in New York. Circulars have been sent to the members of the Institute by A. E. Vaughan & Co., a tourist trip agency of New York City, containing details of tours nearly identical with those outlined in the Bulletin, and quoting rates covering, the expenses of the whole trip. Members can easily compare these rates with the rates offered by the railroads, and published in the last Bulletin. In order that no misapprehension may exist, the statement is here made that the Institute and its officers have no connection whatever with Vaughan & Co.'s proposals and that any such tours will be strictly personal matters between said company and the members of the Institute who take them. Nevertheless, the Board of Directors calls to the attention of members the circumstance that tours such as these will afford an opportunity for members to travel together to the meeting.

Jan 6, 1913

By Joseph E. Pouge

For the purposes of this analysis it is assumed that the petroleum industry has undergone a basic economic change whereby the degree of competition present in its operation is reduced by the collective control of production brought about by statme-directed proration. Formerly freely competitive in all its parts, the industry is now fully competitive only in its marketing, its manufacturing and transportation, its search for new oil supplies, its drilling operations (with some qualifications), and its capital movements. The practical problem before the industry in its new status is the maintenance of equilibrium, with planned control of crude-oil production (proration) substituted for competition and price as the regulatory mechanism at one point in the supply-demand system. It is further assumed that proration has become so firmly established in the legal and operating framework of the business that it may be looked upon as an institution. The purpose of this paper is to call attention to the effect of unregulated drilling upon the orderly functioning of proration. Economic Structure of Petroleum Industry The economic structure of the petroleum industry, under the current form of proration, may be visualized, in simplified form, as shown in Fig. 1. This diagram is designed to indicate the existing mechanism whereby supply and demand are equated. Demand is created largely by conditions external to the oil business, whereas supply is conditioned by a series of stages incidental to the discovery, development and production of a resource. The time elements involved in changes in demand and supply are of an entirely different order, the demand factor being much more flexible and "quicker" than the supply factors. It should be observed, also, that the position of price, formerly between "demand" and "supply," has been moved to a sidewise location where it still affects demand but influences current supply only through its bearing upon proration, drilling and search. Proration has been substituted for price as a throttle at the well head, but at this point only. The mechanism now works in this fashion: a declining price stimulates demand and the

Jan 1, 1936

By Joseph E. Pouge

For the purposes of this analysis it is assumed that the petroleum industry has undergone a basic economic change whereby the degree of competition present in its operation is reduced by the collective control of production brought about by statme-directed proration. Formerly freely competitive in all its parts, the industry is now fully competitive only in its marketing, its manufacturing and transportation, its search for new oil supplies, its drilling operations (with some qualifications), and its capital movements. The practical problem before the industry in its new status is the maintenance of equilibrium, with planned control of crude-oil production (proration) substituted for competition and price as the regulatory mechanism at one point in the supply-demand system. It is further assumed that proration has become so firmly established in the legal and operating framework of the business that it may be looked upon as an institution. The purpose of this paper is to call attention to the effect of unregulated drilling upon the orderly functioning of proration. Economic Structure of Petroleum Industry The economic structure of the petroleum industry, under the current form of proration, may be visualized, in simplified form, as shown in Fig. 1. This diagram is designed to indicate the existing mechanism whereby supply and demand are equated. Demand is created largely by conditions external to the oil business, whereas supply is conditioned by a series of stages incidental to the discovery, development and production of a resource. The time elements involved in changes in demand and supply are of an entirely different order, the demand factor being much more flexible and "quicker" than the supply factors. It should be observed, also, that the position of price, formerly between "demand" and "supply," has been moved to a sidewise location where it still affects demand but influences current supply only through its bearing upon proration, drilling and search. Proration has been substituted for price as a throttle at the well head, but at this point only. The mechanism now works in this fashion: a declining price stimulates demand and the

Jan 1, 1936

By R. E. Lund, D. E. Warnes

SELECTIVE sulfation of individual constituents in ores or metalliferous products has received increased attention in recent years. The fluid-bed reactor with its advantages of close control of both temperature and atmosphere promises to have ap-

Jan 1, 1958

By T. E. Brower

SHORTLY after our previous paper on this subject was printed,1 we located a source of uncertainty in the results arising from the unexpected fact that hydrogen slowly reduces silica at 1100° C. in presence of iron, even when the iron nowhere touches the silica, although in absence of iron it does not do so. This difficulty has been completely obviated by the use of a small high-frequency furnace, which enables us to heat the specimen for analysis without raising the temperature of the silica vessel to a point at which any appreciable reduction of the silica glass occurs. We now describe this modification of procedure, and present some typical results obtained with it. For any given specimen of steel, the results are entirely definite and. reproducible, but their precise significance is still open to some question, as indeed is true of all methods of oxygen determination so far developed. Further elucidation of this question is to be expected from the cooperative comparison of the several methods now under way under the auspices of the Bureau of Standards at the instance of the Iron and Steel Division of the A.I.M.E.

Jan 1, 1934

By D. J. Sellmyer

In order to orient single crystals by the back-reflection method it is necessary to know the angles between the various crystallographic planes. These angles have already been published for the hexagonal close-packed metals magnesium, zinc, and cadmium.'

Jan 1, 1965

By E. Mcl. Tittmann

Deep-seated human instincts urge us to positively mark the passage of time. We celebrate the passage of each year. Years give way to decades, and decades to half centuries and centuries. At all these mileposts we are inclined to pause, take a look around and catch our breaths before embarking on the next leg. We are at such a point now and this meeting I am sure will give direction to the road ahead into the decade of the seventies. In looking around at this point, 1973, it is obvious to all of us that the environment in which we must mine, mill, smelt and refine lead and zinc has radically changed. These changes have, of course, occurred over a long period of time. They have, however, all been in the same general direction. They have all had the same motivation. The period of greatest contrast is probably the fifteen years just before World War II and the fifteen years following the end of that war. I thought that I might review briefly with you what seems to me to be four of the more important changes that have developed since World War II that profoundly affect our activities in the lead and zinc industry. I mentioned before that all these changes have been in the same direction; that is, they have all tended to restrict our freedom of action in pursuing our objective of producing lead and zinc on a competitive basis at a profit. Consequently, in discus- sing them you may think that I am merely viewing with alarm. This is not the intent. This is merely supposed to be an objective analysis. I think it appropriate before discussing these trends in de- tail to examine the position of lead and zinc today.

Jan 1, 1970

ROBERT F. MEHL, Chairman ALBERT J. PHILLIPS, Past-chairman ROBERT H. LEACH, Vice-chairman E. M. WISE, Vice-chairman W. M. CORSE, Treasurer - Louis JORDAN. Secretary 29 West 39th St., New York, N. Y.

Jan 1, 1938

By R. G. Schaal

The Magma Mine at Superior, Arizona had an unimpressive beginning as a. worked out silver mine that was purchased in 1910 for $130,000 and then incorporated into the Magma Copper Company which has been continuously mining the deposit since 1915. Copper is the principal metal produced. However, zinc, gold, silver and iron have also contributed to the total metal product. Prior to 1973, the production rate of 1500 tons per day was maintained by hoisting 4 and 5 ton pay-loads at speeds up to 1100 FPM through four small hoisting shafts. The hoists used included 8' and 7' diameter double drum, double clutched doc. and a.c. motor driven geared units built as early as 1917. One old timer that did yoeman's service for many years was an 8' Bollen Pulley with a.c. geared drive that utilized an endless rope system with mechanical grip and release mechanism built into the pulley's throat. Primary power for all of these old production hoists was 25 Hertz. Exploration that was completed in 1967 developed a reserve of 10 Million tons of 5 per cent copper which was sufficient to justify new capital expenditures for enlargement of productive facilities to 3300 tons per day. To reach the new reserves a 22' I.D. concrete lined vertical shaft was sunk to an initial depth of 48431. A 12 ½ diameter adit was bored from the mill side of the mountain to intercept the shaft at a point about 1100' below the collar. This 9200' long adit provides the right-of-way for the mine to mill railway and egress for heavy supplies from rail head as well as a conduit for potable water, electric power, compressed air and mine drainage. Mine operating levels begin 3582' below collar and thereafter have been cut at 100' vertical intervals. Skip loading stations have been installed 4282' and 46821 below collar with an in-shaft skip dump station located 800' below collar. This provides for 4500 tons of storage above the mine to mill train loading station located 1100' below collar. Ore and waste are moved horizontally from stope chutes and drift headings by rail haulage to transfer raises which channel all material to the two mentioned skip loading stations. The 22' diameter shaft crossection is arranged with the two skip compartments on the south side separated from the manway and utility compartments by the cage compartment. The cage counterweight operates in a portion of the southwest quadrant of the shaft. The hoisting plant consists of two conventional Nordberg double drum, single clutch, geared, d.c. motor driven units that are identical except for the drives and automatic controls. The drums are 15' diameter x 105" face with LeBus grooving for 2-1/8" diameter wire rope wound in three layers. Mechanical design emp1o::ed is the same as has been used for the past twenty- five years. One drum is attached to the main shaft by 2 large bolted integral shaft flenge. The loose drum is engaged by a 4-arm positive tooth clutch meshing with radially cut teeth of the clutch ring which is bolted to the drum. The drums are one-piece steel plate weldments having a finished weight of 60 tons each and are mounted upon a 36" diameter shaft that also weighs 60 tons. With the addition of brake rings, clutch, bull gear and rope, the total dead weight adds up to nearly 250 tons that is supported by just three double row spherical roller pillow block bearings. There is no bearing between the drums. All pinion shafts as veil as all head sheave journals are supported in the same type of antifriction bearings.

Jan 1, 1975

If world oil prices stabilize at $ll/bbl, if the US decides on the "accelerated supply" case for domestic fuel resources, if investment capital is available, if environmentalists' demand become reasonable, if land withdrawals are halted, if government grants generous depletion allowances and fast depreciation write-offs, and if many other "iffy" conditions are met-then shale oil production may reach the 1-million-bpd level by 1985, according to the Project Independence Report. In the "base case" scenario, oil shale production would be, at best, about 250,000 bpd at $11 prices, and "much lower if expectations for $7 oil prices prevail." In this regard, the FEA study reflects the conclusion reached by companies engaged in oil shale development work. Thus, except for some new technological breakthrough in mining, the birth and growth of the US oil shale industry will occur only if oil prices stabilize at about $ll/bbl.

Jan 5, 1975

By A. G. Guy, T. B. Lindemer

A second intepation of the Fick law has been developed and applied to three-place data generated from the Gosting and Fujita solution of the diffusion equation. This integration provides new mathematical techniques for the analysis of experimental data. Through use of the synthetic data it is shown that for concentration-independent interdifiusion coefficients these techniques permit a more accurate determination of the coefficients than does the usual Boltzmann-Alatano analysis. Another technique, applicable to the most general concentration-dependent diffusion coefficients , can be used to determine whether given sets of coefficients are consistent with the experimental ternary concentration-distance curves. DURING the past 10 years the subject of three-component diffusion has advanced from the stage of a laboratory curiosity to the status of an accepted portion of physical metallurgy.1 In the course of this development the underlying treatment for two-component sys- tems was extended and generalized to accommodate the added component, but fundamentally the analyses currently employed for ternary systems are analogous to those previously developed for binary systems. There are several indications that an improved analysis is needed for the ternary case. First, the two cross coefficients, D312 and D321 are typically an order of magnitude smaller than the direct coefficients and consequently are difficult to determine with adequate precision. Second, instead of a single concentration-penetration curve (as in binary diffusion), there are four such curves in the usual determination of ternary diffusion coefficients. These curves have definite theoretical interrelationships, but actual experimental curves exhibit significant departures from these relationships. Finally, the amount of data needed to adequately describe the diffusion behavior of a ternary system is so large that radically new methods are needed to facilitate the gathering of these data. ICirkaldy2j4 has proposed several possible analyses of ternary diffusion data, including some of the methods in current use. A "second-integration" procedure proposed by him4 differed in important respects from that presented here and was not carried to the point of application. Two other methods have been explored by the authors and will be published separately; these are a numerical analysis technique and a method for the analysis of a single ternary diffusion couple. Still other analyses are being explored by various investigators. At present it seems likely that the final analysis of ternary diffusion that evolves will be a composite

Jan 1, 1968

By S. C. Oliphant, C. R. Houssiere, George H. Fancher

DRILLING mud can be an item of great expense on the Gulf Coast. In order to understand the nature of a drilling mud, it is desirable to know the composition and size of the mineral particles that are present, The supercentrifuge has been adapted to the fractionation of mud, and this paper discusses the calibration and methods of operation and control. An alignment chart has been prepared, which was found useful in this work. Typical data are included, showing the comparative reliability of the method.

Jan 1, 1942