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Lake Superior Iron Ore Association, 3100 East 45th St , Cleveland, Ohio W L Tinker, Secretary This Association does not issue scientific technical bulletins, strictly speaking, but statements, etc , are published containing information of interest to mining engineers and geologists To show the type of information published, mention may be made of material issued in 1931: 1 Directory of mine operators and statistical data. 2 A bulletin, Distribution of Lake Superior iron ores, also Eastern and foreign ore 3 A booklet, Analyses of Lake Superior iron ores, season 1931 These publications, or information on others may be had by addressing the above

Jan 1, 1933

By J. G. Morlet, A. R. Troiano, H. H. Johnson

Delayed failure in steel occurs by controlled initiation and growth of a crack. The incubation period for crack initiation was measured. Crack initiation and Propagation are controlled by interaction between hydrogen concentration and triaxial stress state. The incubation period results from stress-induced diffusion of hydrogen to the point of crack initiation. THIS paper describes the phenomenon of delayed failureland the kinetics of crack initiation and propagation in uniformly hydrogenated steel. The investigation was prompted by service failures of high-strength-steel components at applied stresses far below the conventional yield strength, after the part had successfully sustained equal or higher stresses for an extended time interval. This delayed failure phenomenon, often termed static fatigue, is associated1 with the presence of hydrogen. This is not surprising, since the voluminous literature on flaking and hydrogen embrit-tlement demonstrates that hydrogen may exert a potent embrittling influence. Flakes, or internal hairline cracks in alloy-steel forgings, are related to the presence of hydrogen retained from the steel-making process.2 On the other hand, embrit-tlement arises from hydrogen introduced during surface treatments such as acid pickling or electroplating. Laboratory delayed failures have been induced in notch specimens of 4340 steel by electrolytic charging of the specimen surface with hydrogen and subsequent static stressing.l,4,5 Static fatigue was observed over a wide range of applied stresses; however, failure did not occur below a critical applied stress, designated as the static fatigue limit. In this instance the extended time for failure resulted primarily from the macroscopic redistribution of hydrogen. A crack formed to the depth of the hydrogen enriched "case* upon loading; further crack growth naturally awaited diffusion of hydrogen into the material ahead of the crack. The crack-propagation rate was therefore controlled primarily by the macroscopic diffusion of hydrogen into the specimen interior during the test. Thus, in this instance static fatigue was associated with the movement of a gross concentration gradient. However, delayed failure in steel of uniform hydrogen concentration is of greater fundamental interest, as well as commercial significance. With a homogeneous hydrogen distribution a different mode of delayed failure might be expected. As the heterogeneous hydrogen distribution became more uniform,4,5 the initial crack-propagation rate decreased markedly and, in fact, what appeared to be an incubation period for crack initiation was observed. However, the macroscopic concentration gradient precluded an accurate evaluation of these observations. Although the existence of an incubation period, up to this time, has not been established definitely, it is not amiss to point out some implications of the concept. It is of interest in all hydrogen-induced embrittlement phenomena, such as flaking, delayed failure, and hydrogen embrittlement. Much discussion has centered around the possibility of an

Jan 1, 1959

By R. E. Miner, J. K. Jackson, T. L. Wilson

THE nature of the decomposition reactions producing hardening in aluminum-rich A1-Ag alloys is now fairly well understood. The silver is not uniformly dispersed even at temperatures above the solvus line: rather, it is clustered into zones and associated with dislocations.' During quenching, nearly all of the silver segregates into zones' and some is attracted to dislocations, producing stacking faults. Growth of these faults produces the semicoherent y precipitate.1 During aging, the larger zones and the y precipitates grow at the expense of the smaller zones. The large zones persist up to about 350°C; where they redissolve in favor of the y' and y precipitates.' The equilibrium hcp y precipitate occurs both by a cellular reaction at the grain boundaries1 and by growth of the Y' plates to a critical size where incoherency results. Damask and Nowick 4 observed an internal friction peak in an A1-6 at. pct Ag alloy at about 140°C (0.25 cps). The peak was found to exhibit a systematic instability. After aging at successively higher temperatures between 155' and 23Z°C, the peak first migrated to higher temperatures while increasing in height, then returned to lower temperatures and decreased in height. After aging at temperatures above about 200°C, the peak position remained constant while the height decreased very slowly. In quenched specimens, elastic after-effect measurements inhcated a rapid initial transient in peak position from low temperatures up to 155°C. The authors concluded that a stress induced growth and resolution of the clusters and the 7' was the most reasonable mechanism to account for the behavior. It would seem, however, very unlikely that both the clusters and the y' precipitate would provide damping contributions whose relaxation time and activation energies were identical, which is required for them to produce the same internal friction peak. The present investigation was motivated by this apparent anomaly and the development of a very low thermal inertia torsion pendulum5 capable of monitoring transient behavior. Low frequency internal friction measurements were made on four binary A1-Ag alloys nominally containing 5, 10: 15, and 20 at. pct Ag. The results of measurements made on a 10 at. pct Ag alloy in the quenched condition are shown in Fig. 1. There are two peaks apparent in the spectrum, one centered at about 160°C, the second at about 210°C. The two peak spectrum was observed in each alloy, but it was best resolved in the 10 pct Ag specimens. Because of the instability in the internal friction, 4 it seemed possible that the second peak was not a peak at all, but simply a manifestation of a single, sharply transient, peak. This effect has been observed in Au-Ni alloys.6 The existence of the higher tempera-

Jan 1, 1970

By E. A. Jones

THE Southeast Missouri division of the St. Joseph Lead Co. normally hauls and hoists over 5 million tons of lead ore each year. This ore is mined in the stopes and headings of 20 mines, hauled to a main line system, see above, and transported up to 6.4 miles to ore-hoisting shafts. Average haulage distance is 2.16 miles. A few years ago a distinguished mining engineer visiting this area for the first time remarked, "You do not have a mining problem; yours is a haulage problem." Its relative importance may be gaged by the fact that mine haulage represents about 25 pct of the total cost of mining ore, the most costly single underground operation. The Southeast Missouri lead belt is a mining district located about 65 miles south of St. Louis. This district is roughly 6 miles wide and 10 miles long. The ore horizon lies about 400 ft below the surface where most of the ore is mined from flat-lying beds of dolomitic limestone. This paper deals with the central part of the district, namely, that portion which contains a group of interconnected mines all in a central haulage system, serving four hoisting shafts. The two major hoisting operations are carried out at Federal No. 17 shaft and Leadwood No. 12 shaft. No. 17 accounted for about 70 pct of the ore hoisted in the district during 1950, averaging about 14,000 tons per operating day. The underground dumping and skip-pocket system at this shaft is similar to those of the other shafts except that it has two rotary dumps. The other ore-hoisting shafts have only one. It might be mentioned that waste rock is hoisted at still other shafts, hauled off, and dumped on the surface by trucks. The hoisting shafts are on a connected system of about 200 miles of underground 24-in. gage main line railroad. There is also the Bonne Terre system, with its own ore-hoisting shaft, which consists of 13.5 miles of 24-in. gage main line, located in the extreme north portion of the lead belt area. Smaller outlying mines such as Doe Run No. 12 and Hayden Creek operate on trackless or shuttle car haulage. In addition to the system of main line haulage, each contributing mine group has its own extensive system of stope or heading railroad. Trackless mining is making considerable headway in the Lead-wood and Desloge mines. Here the shovel loads into a shuttle car which in turn dumps into mine cars spotted on the main line track system. When the merits of underground haulage and surface transportation are compared, it must be remembered that in early days there were many individual

Jan 1, 1954

By W. Rostoker, R. P. Elliott, B. W. Levincer

Phase equilibria in the Ti-Cr-Mo system have been investigated for alloys containing 100 to 40 pct Ti in the temperature range 550° to 1300°C. Five experimental isothermal sections and a surface of incipient melting are presented in addition to a summary projection of the space. Seven vertical sections have been constructed from the isothermal sections. A STUDY of the system Ti-Cr-Mo was undertaken as part of a program sponsored by Watertown Arsenal toward the development of titanium-base phase equilibrium diagrams of potential technical importance to alloy development. The scope of the investigation included the composition range contained by the titanium corner and the line of 64 pct Ti (all compositions are by weight) and the temperature range 550" to 1100°C. A surface of incipient melting was constructed from measurements on a large number of alloys. The system Ti-Cr has been established.&apos;-? The phase diagram is characterized by a wide miscibility field of the solid solution at elevated temperatures and a eutectoid reaction of the type: (15 pct Cr) + TiCr, (685C). The a solid solution has a very limited capacity for solution of chromium (< 0.5 pct Cr). The intermediate phase TiCr2 has at best a very narrow composition range. It has been shown that two allotropic modifications of this phase exist. However, this behavior does not appear to be perceptibly reflected in the form of phase boundaries of the type + TiCr,. In the system Ti-Mo,9-10 the phase is stabilized to successively lower temperatures with increasing molybdenum content. There are no known intermediate phases. The a solid solution is limited to less than 0.5 pct Mo. Because of the very extensive range of the phase, the ternary system was ideally suited to the determination of the phase boundaries by the parametric method of Andersen and Jette." A parametric surface was constructed to provide the necessary basis for the application of this method. Preparation and Treatment of Alloys More than 60 alloy compositions were prepared for the study of this system. Alloy buttons of 10 grams were arc-melted in a nonconsumable electrode furnace using inert atmosphere protection and a water-cooled copper crucible. The construction and operation of this type of melting unit have been adequately described elsewhere.&apos;&apos; To insure complete solution of alloy additions, the buttons were remelted alternately on top or bottom as many as five times. This was accomplished by a suitable mechanism for "flipping" over the ingots. Iodide titanium (99.97 pct Ti) was used as the alloy base. An especially high quality chromium (99.9 pct Cr) was obtained from the National Research Corp. Molybdenum sheet (0.005 in.) of 99.9 pct purity was used.

Jan 1, 1954

By Henry T. Mudd

FLUORSPAR is a nonmetallic mineral aggregate or mass containing a sufficient quantity of fluorite (CaF2) to be of commercial interest. It has only moderate value per unit of weight and its cost as a percentage of the cost of finished consumer products is nearly negligible. Nevertheless, it has wide and great industrial importance. In periods of national emergency it is a mineral without which many very necessary manufacturing processes would be greatly handicapped; a few could not exist. Fluorite contains 51.1 pct calcium and 48.9 pct fluorine. Industrial grades of fluorspar prepared for the consumer normally contain from 85 to 98 pct fluorite, depending on the use. The ores may contain as little as 30 pct fluorite, depending on many factors such as accessibility to transportation and markets, character of ore, and prices. Fluorite is a lustrous, glasslike mineral, generally translucent to transparent; it may be clear and colorless or range in color from slightly bluish through various shades of violet, amethyst, purple, green, and yellow. It crystallizes in the isometric system and possesses perfect octahedral cleavage. Commonly it occurs in masses of very pure crystal- line material with aggregates of cubical crystals in open spaces, but - it is also found in fine to coarse granular form. Banded veins and masses with fibrous, radiating structure occur locally. It is usually found associated more or less intimately with other minerals and rocks, from which it must be separated for commercial use. The specific gravity of fluorite is 3.18 and the hardness is 4 in the Mohs scale, compared with 7 for quartz and 3 for calcite. It is distinguished from calcite by its failure to effervesce with dilute hydrochloric acid. Heated with sulphuric acid, it gives off fumes of hydro- fluoric acid, which etch glass.22,25,33.34,35.41

Jan 1, 1949

By W. L. Fink, L. A. Willey

This paper is the nineteenth of a series from the Aluminum Research Laboratories, presenting the results of the investigations of equilibrium relations in aluminum-base alloys made from electrolytically refined aluminum. In previous papers equilibrium relations have been determined and correlated for 12 binary systems. Equilibrium relations have also been determined for portions of the aluminum corners of three ternary systems (aluminum-iron-silicon, aluminum-magnesium-silicon and aluminum-copper-magnesium). The object of the present paper and those to follow is to increase our knowledge of the aluminum corner of the more important ternary systems. In 1926 Dix and Keith † suggested a new method for designating the phases encountered in alloy systems. The system has been used to a very limited extentl,2,3 The system has since been slightly modified and will be used in this and future papers. In the system as modified, a phase is designated by placing in parentheses the chemical symbols of the elements essential to the formation of that phase. The symbols in the parentheses are separated by dashes in order to clearly distinguish them from a chemical formula. Elements that are not necessary to the formation of the phase in question, but which may be present in solid solution, are not indicated in the designation. If two or more phases would have the same designation according to these rules, they are distinguished by prefixing Greek letters, and are definitely identified by X-ray diffraction patterns. Previous Investigations The solid solubility of magnesium in aluminum has been well established by the work of Dix and Keller4, Schmid and Siebe15, and Saldau and Sergeev6. There is no agreement as to the composition of the magnesium constituents at the aluminum end of the binary aluminum-magnesium system. Hanson and Gayler7 report Mg2Al3; Boyer8 found that the alloy

Jan 1, 1937

By Howard I. Smith

POTASH is of prime importance as a plant food and is also widely used in industry. The term "potash was applied to a crude pearlash obtained by evaporating, in iron pots, solutions leached from plant ashes. Later it included caustic potash obtained by treating pot ashes with lime, and now it is applied generally to various compounds of potassium used by agriculture and industry. Herein it applies to the theoretical equivalent in potassium oxide (K20)--a compound never found in nature or manufactured in commerce but generally used as a common denominator for comparison of all potassium compounds. Potash was made from plant ashes at an early date, but potassium in mineral form was not noted until 1797, when it was identified in leucite.3 The importance to plant life of potash in the soil was first recognized by von Liebig3 and his published reference thereto appeared in 1840. In 1843, potash was discovered in the brine of a well drilled for salt near Stassfurt. HISTORY OF THE AMERICAN POTASH INDUSTRY Among the colonists reaching Virginia in 1608 were men from Poland skilled in making potash from wood ashes19 and records show that the production of potash was begun in other colonies also, soon after their establishment. The American product entered the trade in 1635, and at various times since that date the production of potash for industry has been subsidized by the Government or protected by tariffs. The production of potash from wood ashes reached its peak in 1825. Beginning in 1823, a cheaper product, sodium carbonate, made by the Leblanc process, was substituted for much of the potash used in industry. Production rapidly declined after the Civil War, when the forests most productive of potash had become depleted and labor had become

Jan 1, 1949

By S. H. Gelles

Samples of poly crystalline zinc of 99.999+ pct purity were observed metallographically after having been exposed to hydrostatic pressures of up to 27 kbars. The deforrnation produced by this treatment was analyzed using X-ray and metallogaphic techniques. Basal-plane slip occurred universally in all grains exumined at the lowest pressure used (8 kbars). At pressures of >23 kbars, {1012} twin nucleation and growth were noted as well as slip. Formation of bend planes, complex kink bands, and recrystallization at the gain boundaries were also observed in this pressure range. These observations are discussed in reference to the expected deformation behavior of zinc under high hydrostatic pressure. It has been shown over the past few years1&apos;3 that anisotropic, poly crystalline metals can be made to deform plastically by the application of a hydrostatic pressure. The effect is greater 1) the larger the anisotropy of linear compressibility and 2) the smaller the stress level needed to produce plastic deformation. Zinc having both very anisotropic linear compressibilities and a very low critical resolved shear stress (CRSS) for basal-plane slip has been shown to exhibit large amounts of plastic deformation when subjected to a hydrostatic pressure.2,3 At pressures up to 15 kbars, grain boundary migration and slip on one set of glide planes have been reported.&apos; After exposing samples to 20 kbars pressure, grain boundary migration, single slip, multiple slip, and twinning have been noted.&apos; The identification of the deformation modes operative under these conditions has not been reported. It was the purpose of this research to identify the deformation modes induced in poly crystal line zinc by the action of a hydrostatic stress and to study the strain accommodation at grain boundaries. Hydrostatic pressure could affect the operational modes of deformation by altering the Peierls-Nabarro stress. This may be roughly approximated by the relationship4

Jan 1, 1967

By C. H. Mathewson

ABOUT fifty pages of Henry M. Howe&apos;s profound treatise, "The Metallography of Steel and Cast Iron," are devoted to twinning with special reference to the origin, nature and general significance of the Neu-mann bands in ferrite. Howe believed with Osmond and Cartaud1 that the Neumanns are mechanical twins and his careful observations leave no doubt that these straight-sided narrow bands habitually occur parallel to trapezohedral planes of form {211}. Attempts to develop the structure of the bands by various methods so that their identity could be established beyond question have not been conspicuously successful. Howe thought that they deflected slip bands. Some of the etching figures which have been developed within and adjacent to Neumann bands support the contention that they are twins. A good example of this effect in ferrite containing 0.6 per cent. of nickel and 1.3 per cent. of phosphorus, originally due to Harnecker and Rassow,2. was reproduced in the 1928 lecture before the Institute of Metals Division on twinning in metals.3 In this case, the sides of the figures might represent the traces of cubic planes laid bare by etching a properly oriented grain of ferrite, twinned along a plane of form 12111. Our own observations in this direction may be represented by Fig. 1 which shows in a deeply etched cavity in the boundary region between a Neumann band and the original crystal two small crystal surfaces which resemble the faces meeting at a reentrant angle in the simple cube twinned along a bisecting plane of form {211} as sketched in Fig. 2. Rosenhain and McMinn4 in 1925, after a careful study of slip bands in ferrite containing Neumanns previously produced by shock, concluded

Jan 1, 1928

By G. H. Edmunds, C. H. Mathewson

About fifty pages of Henry M. Howe&apos;s profound treatise, "The Metallography of Steel and Cast Iron," are devoted to twinning with special reference to the origin, nature and general significance of the Neumann bands in ferrite. Howe believed with Osmond and Cartaud1 that the Neumanns are mechanical twins and his careful observations leave no doubt that these straight-sided narrow bands habitually occur parallel to trapezohedral planes of form {211). Attempts to develop the structure of the bands by various methods SO that their identity could be established beyond question have not been conspicuously successful. Howe thought that they deflected slip bands. Some of the etching figures which have been developed within and adjacent to Neumann bands support the contention that they are twins. A good example of this effect in ferrite containing 0.6 per cent, of niekel and 1.3 per cent. of phosphorus, originally due to Harnecker and Rassow,2 was reproduced in the 1928 lecture before the Institute of Metals Division on twinning in metals.3 In this case, the sides of the figures might represent the traces of cubic planes laid bare by etching a properly oriented grain of ferrite, twinned along a plane of form (211). Our own observations in this direction may be represented by Fig. 1 which shows in a deeply etched cavity in the boundary region between a Neumann band and the original crystal two small crystal surfaces which resemble the faces meeting at a reentrant angle in the simple cube twinned along a bisecting plane of form (211) as sketched in Fig. 2. Rosenhain and McMinn4 in 1925, after a careful study of slip bands in ferrite containing Neumanns previously produced by shock, concluded

THE problem of reaction rates in the open-hearth process is essentially that of trying to form a fairly clear picture of the "chemical mechanisms" in the bath. Quantitative data on reaction rates would not be very useful even if they were available; however, what few , approximate data there are, can be used in combination with data given in Chapters XVI and XVII to sketch a picture of the "chemical mechanics" of the open-hearth process that is consistent with essentially all the present available evidence. The result may later be found incorrect in many details but even so it will illustrate certain useful methods for obtaining a clearer understanding of the process. As discussed in the last portion of Chapter XIII chemical reactions in general involve the following factors: 1. The reacting molecules are mixed together in space in such fashion as to favor collisions among them. 2. A certain number of collisions occur per unit time among the reagent molecules, depending on their concentration and on temperature. 3. A certain percentage of these collisions result in reaction, these being the collisions between those molecules possessing at the moment energy levels above certain minimum values. The temperature factor enters mainly through (3), and its effect is very marked. (What is called temperature is really the mean energy content of all the molecules of the substance involved; at any one temperature a certain proportion of the molecules will have much higher energy content than the mean value.) Various reaction rates measured at around room temperatures have been found to be speeded from 1.6 to 4.0 times by an increase of only 15 to 20°F., simply because increasing temperature produces a rapidly increasing percentage of molecules with energy levels above the minimum needed to produce chemical reaction in a collision.

Jan 1, 1944

By Harold L. Hinds

The Homestake Ledge or Lead was discovered by Fred and Moses Manuel on April 9, 1876. They recovered a small amount of gold from the quartz outcrop, but, unfortunately, they were prospectors not hardrock miners. Their claim was sold to a group of experienced California mining men in 1877. These mining men incorporated their holdings as the Homestake Mining Company. This was the beginning of one of the greater gold mining enterprises of the Western World. Metallurgical operations progressed over the years from an eighty- stamp grinding circuit using amalgamation for recovery to the more complex circuit of today. The Homestake Mine, today, is an underground mine with the deepest winze reaching the 8,000-foot level. The ore is hoisted to the surface by two primary shafts, the Ross Shaft and the Yates Shaft. See Figures 1 and 2. It is crushed in three-stage crushing plants located in the headframes. From here, it is trammed to the mill fine- ore bins by electric locomotives. The Lead grinding plant milling circuit, known as the South Mill, receives ore from the crushing plant at minus 112 inch (Figure 3). This material is dumped into overhead fine-ore bins from five- ton rail cars. The fine-ore bins have a live capacity of about 3,700 tons. The South Mill bins can also be fed by a conveyor system which reclaims ore from an 80,000-ton capacity stockpile. This stockpile is built up from peak mining production periods and available surface low grade material. It is then reclaimed during low mine production periods. The grinding circuit at the South Mill consists of four rod mills in open circuit followed by four ball mills in closed circuit. Three of the rod mills are 6-foot by 12-foot Marcy&apos;s. The other is

Jan 1, 1983

By Richard W. Lodge

Several methods, both wet and dry, for the assay of zinc-box residues from the cyanide process, have been described in recent years, and each of them has been claimed to be superior to all others. In the year 1901, a paper, entitled "Assay of Zincy Precipitates," was published ill the School of Mines Quarterly to the purport that the scorification method for the assay of zinc-box residues was absolutely unreliable. In order to shed light on this matter, the following experiments were undertaken by Messrs. C.B. Hollis and F. D. Kehew, undergraduate students at the Massachusetts Institute of Technology. The zine-box residues used were obtained through the courtesy of Mr. H. R. Batcheller. The samples were very rich and varied greatly in the fineness of their condition. SCORIFICATION-ASSAYS. In the preliminary tests, the charge, which was weighed on a chemical balance, consisted of 0.1 Assay Ton of residues mixed with from 30 to 35 grammes of test-lead and placed in a 3-in. scorifier, over this an additional quantity of test-lead (from 30 to. 35 grammes) was placed for a cover, and borax-glass, varying in quantity from 3 to 15 grammes, was sprinkled over the top of each charge of the various assays for a cover. The charges were scarified in a muffle-furnace heated to the ordinary temperature which is used in scorification; in some cases the door of the muffle was left open, while in others it remained closed. Generally, the charges spit badly, especially in the assays that were made with door of the muffle left open, or in those in which the door was opened too quickly. The results of the preliminary assays showed: 1. That in order to obtain approxi-

Jan 1, 1904

By L. VOGELSTEIN

OUTSTANDING among the year&apos;s events in copper has been the reimposition of an import duty of 4r. per pound in this country which became effective June 21. In consequence of this action by Congress, the Ottawa Empire conference recommended a duty of 2d. per pound equivalent at normal rate of exchange to our 4c. duty, on all copper originating outside of the Empire. Lip to the middle of this year only Russia and Japan had a closed market; the import duty on copper in Russia is 30 per cent ad valoremm and in Japan about 2c. Russia&apos;s consumption has always been in excess of production and she has imported from 2(1,000 to 40,000 ton, of copper per annum. Japan, with a production of 6,000 to 7,000 tons per month, has absorbed, in normal times, its production, but during recent: sears has exported varyiug quantities in 1929. 2,200 ton-: in 1930, 2,700 tons, and in 1931. 3,600 ton-. Aside from the-e two countries, the international market has heretofore been free. It and when the British Empire duty become, effective the world&apos;s markets will be divided into four unit: 1. Russia and Japan, 2. United States. 3. British Empire. 4. Rest of the world. The world&apos;s production at present is rennin it the rate of 930.000 tons per annum. This year&apos;s production will be over 1,000,000 tons because the several curtailment did not become effective until the second quarter. consumption will be slightly in excess. Deducting from 30,000 tons Russia&apos;s and Japan&apos;s production of 121.000 tons, 806,000 tons is left divided a, follows:

Jan 1, 1932

By Richard L. Ash

7.3-1. Introduction. All phases of mining competent materials are affected directly by the results achieved from primary blasts. It is imperative that their design suit each particular set of mining conditions. In general, the round design must provide an adequate tonnage of material, properly placed with suitable fragmentation, to ensure that loading, haulage, and subsequent disposal or processing are accomplished at the lowest possible cost. Blasting rounds are designed by the proper application of cratering relationships developed for the single, concentric, confined explosive charge. Blasting for surface mining and most open-cut heavy construction, however, is characterized by the use of rounds, composed of a number of explosive charges with relatively long lengths, which are placed in benches with specific finite dimensions. Therefore, modifications must be made to the classical, single point-charge cratering concepts. It is the purpose of this discussion to outline the basic principles, significant variables, and procedures for their integration in the design of rounds that are applicable to conditions characteristic of surface mining. Because relatively insensitive blasting agents will be used in most instances, particular attention must be given to priming, control of confinement, and selection of charge diameters that ensure complete explosive-reaction execution. 7.3-2. General Considerations. The primary requisites for any blasting round are that it ensure optimum results for existing operating conditions, possess adequate flexibility, and be relatively simple to employ. It is important that the relative arrangement of blastholes within a round be properly balanced to take advantage of the energy released by the explosives and the specific properties of the materials being blasted. There are also environ- mental and operational factors peculiar to each mine that will limit the choice of blasting patterns.

Jan 1, 1968

By J. Q. Ehrgott

INTRODUCTION The U. S. Army Engineer Waterways Experiment Station (WES), under sponsorship of the Defense Atomic Support Agency, has recently developed a unique dynamic high-pressure triaxial testing device (DHT). The device permits acquisition of both axial and lateral deformation data while undisturbed soil and/or rock specimens are subjected to various states of controlled impulsive-type stresses produced by varying both the axial stress and the radial stress rapidly with time. The device is used to develop controlled dynamic pressure pulses within the triaxial chamber fluid on soil or rock test specimens to 3 inches in diameter. Controlled dynamic axial pulse loads are delivered to the specimen by a piston driven by an existing pneumatic ram loader (SECO). The DHT consists of a triaxial cell and a pressure supply and decay system which permits the chamber pressure to be varied with time. Together the DHT and SECO operate in a testing program so as to provide time varying confining pressures and axial loads to test specimens at independently controlled but synchronized programmed rise, hold, and decay times. Rise time is defined as the time from zero load or pressure to peak load or pressure; hold time is the time of constant peak load or pressure; and the decay time is the time from peak load or pressure to zero load or pressure. The maximum dynamic confining pressure attainable is approximately 15,000 psi and the fastest rise and decay times are 3 millisecond (msec) and 20 msec, respectively. This paper presents a description of the DHT, the necessary support equipment, and details of the measurement system. Performance evaluation tests conducted on clay siltstone and a Cretaceous sandstone are presented since the results demonstrate some of the capabilities of the device and show some of its characteristics.

Jan 1, 1971

By Franklin H. Allison

The influence of cobalt and nickel on the properties of steel might be readily expected to be very similar. The two elements occupy close and somewhat unusual positions in the periodic table, their chemical behavior and compounds are so completely analogous and their various physical properties, including the ferro-magnetic characteristic, show such 3 remarkable correspondence, that there is no doubt of a strong resemblance existing between these two metals. However, the variety of properties that are obtained from steel is due largely to the fact that the element iron possesses allotropic forms. Alloying elements that affect these allot ropic forms, or alter the nature of the allotropic changes, exert a profound influence on the resulting steel. In the case of nickel and cobalt, although these elements are very similar chemically and physically, it is found that they differ distinctly in their individual effects on the critical points of iron. Both nickel and cobalt form a series of homogeneous solid solutions with iron at temperatures above 1500" F. The difference in their behavior does not occur until changes begin to take place in the solid state below this temperature. An inspection of the respective thermal equilibrium diagrams at the lower temperatures makes the opposite effects of nickel and cobalt clearly evident. Effect of Nickel and Cobalt in Binary Alloys with Iron The binary diagram of iron-nickel has been investigated by a number of workers. The lower temperature portion in Fig. 1 is reconstructed from the data of D. and H, Hanson.1 The diagram of iron-cobalt, shown in Fig. 2, is taken from the work of Ruer and Kaneko.2 Masumoto3 has recently discovered a lower critical point in cobalt and this has been added to the diagram. In both diagrams the space lattice structures as determined by Andrews4 have been included. It is interesting to note

Jan 1, 1927

By M. King Hubbert

DuRing the past summer the writer was asked by the Illinois State Geological Survey to make a study of some of its economic geological problems with regard to the applicability of geophysical methods of prospecting to their solution. The following four problems were suggested for investigation: (1) the fluorspar area of Southern Illinois, (2) oil structures in the south central part of the state, (3) the lead and zinc-bearing area of northwestern Illinois, and (4) the water supply and gravel deposits of the glacial drift. The prime requirements were to find a means of obtaining a maximum of useful information with a fairly modest outlay of expenditure for technical staff and equipment. The method of procedure adopted was that of making a preliminary study of each of the problems named by means of available office data and published reports with supplementary field reconnaissance where necessary. Preliminary Studies Fluorspar.—The fluorspar deposits of southern Illinois as shown by Weller,1 Bastin2 and others are of two main types: (1) vein deposits along steeply dipping normal fault planes, and (2) "blanket" deposits occurring practically horizontally along a certain sedimentary horizon. The vein deposits are composed mostly of calcite and fluorspar in sheetlike veins of thicknesses, where mined, ranging from about 2 to 12 ft. The surrounding topography is in a mature state of development with a relief of about 100 ft. or more. Any geophysical prospecting for this ore would have to depend either upon the physical properties of the ore and associated minerals or upon the properties of the geologic structure containing them. Fluorspar has a density of 3.18, which is somewhat greater than 2.7, that of calcite. Its

Jan 1, 1934

By Ralph W. Bailey, William B. Price

During the past three or four years, the fabricators of silicon-bronze alloys have endeavored to induce users of phosphor bronze to use instead the silicon-bronze alloys, claiming that the silicon bronzes are superior to the phosphor bronzes for switches and springs, or where high fatigue resistance is desired. This paper gives the results of tests comparing several phosphor bronzes with a 3 per cent silicon bronze and a copper-nickel-tin alloy (Adnic), all processed by the Scovill Manufacturing Co. So far as the authors are aware, sheet-metal fatigue tests have not been made on any of the alloys included in this report, except on one phosphor bronze, material C, Table 1, which was tested by Townsend and Greenall1. Endurance Limit The majority of fatigue tests are designed to determine the endurance limit of a material. The number of repetitions of stress that will serve to establish an endurance limit varies with different materials. For ferrous materials, H. F. Moore2 has shown that stresses that do not cause failure up to 10,000,000 stress cycles will not cause failure up to 100,000,000 (and sometimes to 1,000,000,000) cycles. Thus an endurance limit for ferrous materials can be determined with a minimum of 10,000,000 stress cycles. For nonferrous materials, no such generalization holds. R. R. Moore3 has shown that for manganese bronze and elektron metal, 13,000,000 and 28,000,000 cycles, respectively, will serve to determine an endurance limit, while certain duralumin specimens gave no indications of having reached an endurance limit up to 400,000,000 stress cycles. J. B. Johnson6 showed that an endurance limit for duralumin was not found by tests running up to 500,000,000 cycles. H. F. Moore2

Jan 1, 1937