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By Robert K. Warner

When a new mine is opened, and often when an operating mine must adapt itself to physical or economic changes, a mining system must be selected in complete detail. In the past the plan chosen was usually the product of the local staff alone, however limited the training and experience of that staff might be, which often resulted in the introduction of methods that were familiar to the staff, but not so well suited to the conditions as others unknown to the local men. A new management, noting the difficulties with the existing layout, might make modifications or complete changes, so that many mines in their history have seen a whole series of mining systems, each somewhat laboriously grafted on to its predecessor. This should not be interpreted as a condemnation of the older staffs for sticking to the tried systems, such as open square-sets in the early days at the Homestake, because they knew it would work after a fashion, nor does the statement apply to the technically trained, and usually broadly experienced staffs of most present-day properties. The older miners did not have the variety of tools and methods, nor the present freedom of transfer of information as to what the other man is doing, and so did the best they could under the circumstances. Finally, the higher grade of the ores made the choice less vital. The ever-increasing need to mine low-grade orebodies, with a fixed or even lower price for the metal produced, has caused an increasing need for low-cost mining. In most new mines this has simplified the problem of selection by eliminating from consideration all of the high-cost systems, but it has also complicated the choice by the necessity for refinement in detail and a close adjustment of the plan selected to all the conditions at the property. In these low-cost problems any textbook division of mining systems as applied to "beds, veins or masses" avails little as a guide. It should be realized at the outset that to be successful under modern competitive conditions a system of mining must be worked out with elaborate detail, with careful time scheduling and control of the various elemental operations, and that after it is introduced it must be run with a large amount of technical direction.

Jan 1, 1934

By Robert Warner

WHEN a new mine is opened, and often when an operating mine must adapt itself to physical or economic changes, a mining system must be selected in complete detail. In the past the plan chosen was usually the product of the local staff alone, however limited the training and experi-ence of that staff might be, which often resulted in the introduction of methods that were familiar to the staff, but not so well suited to the con-ditions as others unknown to the local men. A new management, noting the difficulties with the existing layout, might make modifications or complete changes, so that many mines in their history have seen a whole series of mining systems, each somewhat laboriously grafted on to its predecessor. This should not be interpreted as a condemnation of the older staffs for sticking to the tried systems, such as open square-sets in the early days at the Homestake, because they knew it would work after a fashion, nor does the statement apply to the technically trained, and usually broadly experienced staffs of most present-day properties. The older miners did not have the variety of tools and methods, nor the present freedom of transfer of information as to what the other man is doing, and so did the best they could under the circumstances. Finally, the higher grade of the ores made the choice less vital. The ever-increasing need to mine low-grade orebodies, with a fixed or even lower price for the metal produced, has caused an increasing need for low-cost mining. In most new mines this has simplified the problem of selection by eliminating from consideration all of the high-cost systems, but it has also complicated the choice by the necessity for refinement in detail and a close adjustment of the plan selected to all the conditions at the property. In these low-cost problems any textbook division of mining systems as applied to "beds, veins or masses" avails little as a guide. It should be realized at the outset that to' be successful under modern competitive conditions a system of mining must be worked out with elaborate detail, with careful time scheduling and control of the various elemental operations, and that after it is introduced it must be run with a large amount of technical direction.

Jan 1, 1933

By J. C. Motz

Introduction The variations in crushing plant design seen during the past 30 years provide a valuable source of information and experience from which one can select the optimum arrangement for a specific requirement. The purpose of this paper is to examine some specific equipment configurations as they relate to operating efficiency, plant availability and final product size in the form of mill feed. Due to the varied ore properties, physical space limitations, size of ore body and financial resources, there is no single crushing or grinding flowsheet that is best. Since energy costs have risen dramatically during the recent past, it became obvious that significant savings are possible by selecting equipment and a circuit which offers low power requirements balanced with low wear metal and installed equipment costs. Relatively clear and measurable are the metal and maintenance costs and the ever increasing cost of energy. Metal costs in the form of crusher liners have not quite doubled in the last 20 years, while power costs have increased by a factor of four or five, depending on the region considered. Estimates made only a few years ago on the increased cost of energy are obsolete in view of the recent unstable conditions. Since power is therefore becoming the largest cost area, it behooves us to investigate potential cost saving methods in the form of lowering the KWH/Ton of crude. Crushing To reduce run-of-mine to mill feed requires reduction in a series of stages. The physical size and power requirements of a crusher capable of reducing hard rock vary depending on the application. Extended experience in most crushing plants show that a minus 19MM (3/4 in.) rod mill feed can be and is being produced in three stages of crushing. In the majority of cases, the last crushing stage is closed circuited using anywhere from 19MM (3/4 in.) to 14MM (9/16 in.) slotted openings on the sizing deck. In some copper concentrators, the mill feed is all passing 13MM (1/2 in.) using three stages of crushing and 14MM (9/16 in.) square openings on the closed circuit screens. It was felt by some that crushing to this fine size is only possible if the ore is friable and is relatively soft in comparison to the harder ores. Our results show that some of the copper ores are as hard as taconite and are crush-

Jan 1, 1982

By H. l. Burghoff, J. S. Porter

This paper presents the results of an investigation of the effect of cold-working and annealing treatments upon the occurrence of preferred orientation in annealed brass wire. The subject has received less consideration than has the same phenomenon in annealed brass sheet or strip, and perhaps very properly so in view of the obvious and undesired results obtained in the forming or drawing of strip having preferred orientation, which results are in contrast with the lack of any spectacular visual evidence in wire. The factors of cold-working and annealing that control preferredness in strip are naturally expected to function similarly in wire. Indeed, one might expect the condition to be commoner in annealed wire, because the severity of the cold-working between anneals in commercial Practice is usually much greater for wire than for strip. For example, a wire that is to be finished in the annealed condition on a diameter of 0.040 in. is commonly subjected to a final reduction of 90 per cent between the last two anneals, the large reduction being accomplished in the successive drafts of a multiple-die machine. Wire for rivets, for instance, on 0.125-in. diameter, although given a slight reduction of about Io per cent after the final anneal, may have been given a prior reduction of 75 to 80 per cent. Barrettl states the fiber axis of annealed 70-30 brass wire to be [111], with some indication of [IOO] as a secondary fiber axis. Croft and Sachs2 have reported briefly on some differences in brass wire with random and with preferred orientations. They showed statistical plots of the twin-band angles with respect to the wire axis or direction of drawing as observed on an axial plane. They also pointed out that the resistance of the wire to corrosion-cracking when externally stressed and exposed to a mercurous nitrate solution decreased as the degree of the preferred orientation increased. Material and PRocedure All the wire for the investigation was processed from one portion as cut for extrusion from a cast billet of the following analysis: 70.13 per cent copper; 0.01 lead; 0.01 iron; 0.02, nickel; 29.83 zinc (by difference). The billet section, 8 in, in diameter, was extruded hot to 3/4-in. diameter, after which it was processed by alternate cold-drawing and annealing treatments as indicated in Fig. I. The earliest anneals in process were at about 1100°F. and the next to the last reductions by drawing were 58 per cent. The diameter of the finally annealed wire was 0.132 in. Semifinal anneals were at 800°F., 950°F. and 1100°F. and reductions of 47.5, 74, 83.5 and 89.5 per cent were employed in drawing to 0.132 in. The final anneals were at 87s°F., 1050°F. and 1250°F. and were

Jan 1, 1944

By H. l. Burghoff, J. S. Porter

This paper presents the results of an investigation of the effect of cold-working and annealing treatments upon the occurrence of preferred orientation in annealed brass wire. The subject has received less consideration than has the same phenomenon in annealed brass sheet or strip, and perhaps very properly so in view of the obvious and undesired results obtained in the forming or drawing of strip having preferred orientation, which results are in contrast with the lack of any spectacular visual evidence in wire. The factors of cold-working and annealing that control preferredness in strip are naturally expected to function similarly in wire. Indeed, one might expect the condition to be commoner in annealed wire, because the severity of the cold-working between anneals in commercial Practice is usually much greater for wire than for strip. For example, a wire that is to be finished in the annealed condition on a diameter of 0.040 in. is commonly subjected to a final reduction of 90 per cent between the last two anneals, the large reduction being accomplished in the successive drafts of a multiple-die machine. Wire for rivets, for instance, on 0.125-in. diameter, although given a slight reduction of about Io per cent after the final anneal, may have been given a prior reduction of 75 to 80 per cent. Barrettl states the fiber axis of annealed 70-30 brass wire to be [111], with some indication of [IOO] as a secondary fiber axis. Croft and Sachs2 have reported briefly on some differences in brass wire with random and with preferred orientations. They showed statistical plots of the twin-band angles with respect to the wire axis or direction of drawing as observed on an axial plane. They also pointed out that the resistance of the wire to corrosion-cracking when externally stressed and exposed to a mercurous nitrate solution decreased as the degree of the preferred orientation increased. Material and PRocedure All the wire for the investigation was processed from one portion as cut for extrusion from a cast billet of the following analysis: 70.13 per cent copper; 0.01 lead; 0.01 iron; 0.02, nickel; 29.83 zinc (by difference). The billet section, 8 in, in diameter, was extruded hot to 3/4-in. diameter, after which it was processed by alternate cold-drawing and annealing treatments as indicated in Fig. I. The earliest anneals in process were at about 1100°F. and the next to the last reductions by drawing were 58 per cent. The diameter of the finally annealed wire was 0.132 in. Semifinal anneals were at 800°F., 950°F. and 1100°F. and reductions of 47.5, 74, 83.5 and 89.5 per cent were employed in drawing to 0.132 in. The final anneals were at 87s°F., 1050°F. and 1250°F. and were

Jan 1, 1944

By J. C. Bayles

Jan 1, 1886

By J. B. Macelwane

Geophysics differs from geology and physics in in many respects. In the first place, geophysics is a complex science embracing the fields of seismology, geomagnetism, geoelectricity, geodesy, meteorology, vol-canology, physical oceanography, physical hydrology, tectonophysics and exploration geophysics. Geology is also a complex science and so extensive in its various fields that no one can master them all, and no part of geology deals in any sense with several of these fields of geophysics. In the second place, geophysics makes use of methods and instruments that are derived primarily from the science of physics. Geology, on the other hand, has methods of its own and it draws its borrowed techniques and its instrumental equipment not only from physics but also and perhaps primarily from chemistry and biology. The difference, therefore, between the geophysicist and the geologist lies partly in the phenomena that are observed, partly in the methods and instruments with which each carries on his exploration; but partly also, and perhaps principally, in the habitual attitude of mind and in the background of specialized training with which each approaches the problems presented by this planet of ours. The geologist as such, therefore, is no geophysicist. On the other hand, the physicist is not a geophysicist either. Isolation of each problem in a closed laboratow system under complete control is fundamental to the methods of the physicist. The geophysicist must apply physical instruments and physicomathematical reasoning to the study of physical quantities in their undisturbed natural environment. What, then, is a geophysicist? In the sense that he is a trained expert in all of the geophysical sciences, I do not believe that such a person ever existed. It would be beyond the possibilities of a single lifetime. I think there is confusion in our ideas and in our use of terms. We are not all thinking of the same thing when we say geophysics or geophysicist; yet we seem to talk as though we were. It is as absurd to say that the whole of geophysics belongs to geology because the field of a particular type of geophysicist—the exploration geophysicist —calls for some knowledge of geology as it would be to say that the whole of biology belongs to geology because a particular type of biologist—the paleontologist— needs some knowledge of geology. Development of a Geophysicist Since it is impossible to become an expert in all the fields of geophysics, and since students entering college seldom know the field they will choose as a career, what would we suggest as the best general preparation for work in geophysics, whether as a meteorologist, an oceanographer, a seismologist, a geodesist, a geomagneticist, a volcanologist, a tectonophysicist, a hydro1 ogist, or an exploration geophysicistp we may distinguish five phases in the development of a geophysicist: (I) his mathematical and scientific studies in high school; (2) the general mathematical and scientific

Jan 1, 1946

By J. B. Macelwane

Geophysics differs from geology and physics in in many respects. In the first place, geophysics is a complex science embracing the fields of seismology, geomagnetism, geoelectricity, geodesy, meteorology, vol-canology, physical oceanography, physical hydrology, tectonophysics and exploration geophysics. Geology is also a complex science and so extensive in its various fields that no one can master them all, and no part of geology deals in any sense with several of these fields of geophysics. In the second place, geophysics makes use of methods and instruments that are derived primarily from the science of physics. Geology, on the other hand, has methods of its own and it draws its borrowed techniques and its instrumental equipment not only from physics but also and perhaps primarily from chemistry and biology. The difference, therefore, between the geophysicist and the geologist lies partly in the phenomena that are observed, partly in the methods and instruments with which each carries on his exploration; but partly also, and perhaps principally, in the habitual attitude of mind and in the background of specialized training with which each approaches the problems presented by this planet of ours. The geologist as such, therefore, is no geophysicist. On the other hand, the physicist is not a geophysicist either. Isolation of each problem in a closed laboratow system under complete control is fundamental to the methods of the physicist. The geophysicist must apply physical instruments and physicomathematical reasoning to the study of physical quantities in their undisturbed natural environment. What, then, is a geophysicist? In the sense that he is a trained expert in all of the geophysical sciences, I do not believe that such a person ever existed. It would be beyond the possibilities of a single lifetime. I think there is confusion in our ideas and in our use of terms. We are not all thinking of the same thing when we say geophysics or geophysicist; yet we seem to talk as though we were. It is as absurd to say that the whole of geophysics belongs to geology because the field of a particular type of geophysicist—the exploration geophysicist —calls for some knowledge of geology as it would be to say that the whole of biology belongs to geology because a particular type of biologist—the paleontologist— needs some knowledge of geology. Development of a Geophysicist Since it is impossible to become an expert in all the fields of geophysics, and since students entering college seldom know the field they will choose as a career, what would we suggest as the best general preparation for work in geophysics, whether as a meteorologist, an oceanographer, a seismologist, a geodesist, a geomagneticist, a volcanologist, a tectonophysicist, a hydro1 ogist, or an exploration geophysicistp we may distinguish five phases in the development of a geophysicist: (I) his mathematical and scientific studies in high school; (2) the general mathematical and scientific

Jan 1, 1946

By J. B. Macelwane

GEOPHYSICS differs from geology and physics in many respects. In the first place, geophysics is a complex science embracing the fields of seismology, geomagnetism, geoelectricity, geodesy, meteorology, volcanology, physical oceanography, physical hydrology, tectonophysics and exploration geophysics. Geology is also a complex science and so extensive in its various fields that no one can master them all, and no part of geology deals in any sense with several of these fields of geophysics. In the second place, geophysics makes use of methods and instruments that are derived primarily from the science of physics. Geology, on the other hand, has methods of its own and it draws its borrowed techniques and its instrumental equipment not only from physics but also and perhaps primarily from chemistry and biology. The difference, therefore, between the geophysicist and the geologist lies partly in the phenomena that are observed, partly in the methods and instruments with which each carries on his exploration; but partly also, and perhaps principally, in the habitual attitude of mind and in the background of specialized training with which each approaches the problems presented by this planet of ours. The geologist as such, therefore, is no geophysicist. On the other hand, the physicist is not a geophysicist either. Isolation of each problem in a closed laboratory system under complete control is fundamental to the methods of the physicist. The geophysicist must apply physical instruments and physicomathematical reasoning to the study of physical quantities in their undisturbed natural environment. What, then, is a geophysicist? In the sense that he is a trained expert in all of the geophysical sciences, I do not believe that such a person ever existed. It would be beyond the possibilities of a single lifetime. I think there is confusion in our ideas and in our use of terms. We are not all thinking of the same thing when we say geophysics or geophysicist; yet we seem to talk as though we were. It is as absurd to say that the whole of geophysics belongs to geology because the field of a particular type of geophysicist-the exploration geophysicist -calls for some knowledge of geology as it would be to say that the whole of biology belongs to geology because a particular type of biologist-the paleontologistneeds some knowledge of geology. DEVELOPMENT OF A GEOPHYSICIST Since it is impossible to become an expert in all the fields of geophysics, and since students entering college seldom know the field they will choose as a career, what would we suggest as the best general preparation for work in geophysics, whether as a meteorologist, an oceanographer, a seismologist, a geodesist, a geomagneticist, a volcanologist, a tectonophysicist, a hydrologist, or an exploration geophysicist? We may distinguish five phases in the development of a geophysicist: (I) his mathematical and scientific studies in high school; (2) the general mathematical and scientific

Jan 1, 1941

By William A. Johnson

The fundamental role of diffusion in many reactions occurring in solid metals has long been recognized, and there have been careful measurements of rates of diffusion in numerous alloy systems; but our understanding of the atomic mechanism by which diffusion occurs is scarcely in an advanced state.l-3 It is doubtful that this mechanism can ever be directly ascertained; rather, all imaginable mechanisms must be examined and the one that is in best accord with such data as can be obtained from suitably chosen experiments should be selected. Because of its relative simplicity, diffusion in a system containing only one kind of atomic species—commody called self-diffusion—is of considerable theoretical interest. It may be expected that diffusion theory will not be advanced appreciably until a wide variety of diffusion experiments—of which diffusion in a chemical concentration gradient and self-diffusion are two important types—are carefully performed and inter-compared. Aside from the purely theoretical interest in self-diffusion measurements, such studies will be of considerable engineering importance. The rate of any process in a pure metal requiring the movement of atoms, of which recrystallization and creep are two familiar examples, will be understood more readily with the aid of self-diffusion data.† Self-diffusion implies the diffusion of something into its exact counterpart; the detection of such a process is patently impossible, and it is necessary to substitute for it the diffusion of one isotope (in this case radioactive) into another isotope (in this case stable) of the same chemical element. There is, however, no reason to suppose that a radioactive atom will not diffuse at the same rate as its stable isotope, for all of the isotopes of the same element have exactly the same chemical properties; neither the difference in nuclear energy nor the difference in mass would be expected to exercise an important influence in this phenomenon. In this sense, self-diffusion may be thought of as the diffusion of radioactive atoms down a radioactivity concentration gradient, just as usual diffusion is the diffusion of one kind of atom down its chemical concentration gradient. The first measurements of self-difiusion were made by von Hevesy4-6 using the radioactive lead isotope thorium B in ordinary lead. The recent development of means for producing artificial radioactive elements has made possible similar measurements on gold,7, 8 copper,2, 9 and zinc.10, 11 Many of the data that have been obtained are rather poor, and no adequate reason has been given for their poorness; it appears, however, that the unsatisfactory results are characteristic of the particular experimental procedure employed, and not of self-diffusion measurements in themselves. The experimental technique that has yielded the poorer results is the deposition of a thin layer of radioactive atoms on the surface of a specimen and the determination of the rate of inward diffusion

Jan 1, 1941

By William A. Johnson

The fundamental role of diffusion in many reactions occurring in solid metals has long been recognized, and there have been careful measurements of rates of diffusion in numerous alloy systems; but our understanding of the atomic mechanism by which diffusion occurs is scarcely in an advanced state.l-3 It is doubtful that this mechanism can ever be directly ascertained; rather, all imaginable mechanisms must be examined and the one that is in best accord with such data as can be obtained from suitably chosen experiments should be selected. Because of its relative simplicity, diffusion in a system containing only one kind of atomic species—commody called self-diffusion—is of considerable theoretical interest. It may be expected that diffusion theory will not be advanced appreciably until a wide variety of diffusion experiments—of which diffusion in a chemical concentration gradient and self-diffusion are two important types—are carefully performed and inter-compared. Aside from the purely theoretical interest in self-diffusion measurements, such studies will be of considerable engineering importance. The rate of any process in a pure metal requiring the movement of atoms, of which recrystallization and creep are two familiar examples, will be understood more readily with the aid of self-diffusion data.† Self-diffusion implies the diffusion of something into its exact counterpart; the detection of such a process is patently impossible, and it is necessary to substitute for it the diffusion of one isotope (in this case radioactive) into another isotope (in this case stable) of the same chemical element. There is, however, no reason to suppose that a radioactive atom will not diffuse at the same rate as its stable isotope, for all of the isotopes of the same element have exactly the same chemical properties; neither the difference in nuclear energy nor the difference in mass would be expected to exercise an important influence in this phenomenon. In this sense, self-diffusion may be thought of as the diffusion of radioactive atoms down a radioactivity concentration gradient, just as usual diffusion is the diffusion of one kind of atom down its chemical concentration gradient. The first measurements of self-difiusion were made by von Hevesy4-6 using the radioactive lead isotope thorium B in ordinary lead. The recent development of means for producing artificial radioactive elements has made possible similar measurements on gold,7, 8 copper,2, 9 and zinc.10, 11 Many of the data that have been obtained are rather poor, and no adequate reason has been given for their poorness; it appears, however, that the unsatisfactory results are characteristic of the particular experimental procedure employed, and not of self-diffusion measurements in themselves. The experimental technique that has yielded the poorer results is the deposition of a thin layer of radioactive atoms on the surface of a specimen and the determination of the rate of inward diffusion

Jan 1, 1941

By William A. Johnson

THE fundamental role of diffusion in many reactions occurring in solid metals has long been recognized, and there have been careful measurements of rates of diffusion in numerous alloy systems, but our understanding of the atomic mechanism by which diffusion occurs is scarcely in an advanced state 1-3 It is doubtful that this mechanism can ever he directly ascertained, rather, all imaginable mechanisms must be examined and the one that is in best accord with such data as can be obtained from suitably chosen experiments should be selected Because of its relative simplicity, diffusion in a system containing only one kind of atomic species-commonly called self-diffusion-is of considerable theoretical interest It may be expected that diffusion theory will not be advanced appreciably until a wide variety of diffusion experiments-of which diffusion in a chemical concentration gradient and self-diffusion are two important types-are carefully performed and inter-compared Aside from the purely theoretical interest in self-diffusion measurements, such studies will be of considerable engineering importance The rate of any process in a pure metal requiring the movement of atoms, of which recrystallization and creep are two familiar examples, will be understood more readily with the aid of self-diffusion data † Self-diffusion implies the diffusion of something into its exact counterpart, the detection of such a process is patently impossible, and it is-necessary to substitute for it the diffusion of one isotope (in this case radioactive) into another isotope (in this case stable) of the same chemical element There is, however, no reason to suppose that a radioactive atom will not diffuse at the same rate as its stable isotope, for all of the isotopes of the same element have exactly the same chemical properties, neither the difference in nuclear energy nor the difference in mass would be expected to exercise an important influence in this phenomenon In this sense, self-diffusion may be thought of as the diffusion of radioactive atoms down a radioactivity concentration gradient, just as usual diffusion is the diffusion of one kind of atone down its chemical concentration gradient The first measurements of self-diffusion ii ere made by von Hevesy4-6 using the radioactive lead isotope thorium B in ordinary lead The recent development of means for producing artificial radioactive elements has made possible similar measurements on gold,7,8 copper,2,9 and zinc 10 11 Many of the data that have been obtained are rather poor, and no adequate reason has been given for their poorness, it appears, however, that the unsatisfactory results are characteristic of the particular experimental procedure employed, and not of self-diffusion measurements in themselves The experimental technique that has yielded the poorer results is the deposition of a thin layer of radioactive atoms on the surface of a specimen and the determination of the rate of inward diffusion

Jan 1, 1941

By Herman Van Fleet, Frederick W. Neil, O&apos

The object of this paper is to describe the present status and possil~ilities of liquid oxygen as an explosive based upon the investigations, research and practical work of the Ingersoll-Rand Co., and of the Air Reduction Co., from early in 1922 to date. The following work was done. 1. A study of the history and physical theory of L. 0. X. as an explosive. (No attempt will be made in this paper to give the history or theory, as this has already been covered by the literature on the subject.) 2. An investigation of the use and the practice with L. 0. X. in the iron mines of Lorraine where L. 0. X. has its largest application in Europe. Although L. 0. X. is extensively employed in the iron mines of Lorraine, many of the mines using it exclusively, and blasting with it a total of approximately three million tons of iron ore per year, the fact that the mining practice in Lorraine1 is to drill comparatively shallow holes and blast only a few holes at a time, renders the data obtained there of very little value in estimating the possibility of replacing dynamite with L. 0. X. in American mining methods. In fact, in the iron mines in Lorraine, L. 0. X. replaced black powder, or its equivalent. 3. Laboratory research work on properties of absorbent materials. 4. Work in the Bureau of Mines explosive laboratory at Pittsburgh, Pa., on the properties of L. 0. 3. cartridges. 5. Practical work underground with L. 0. X. cartridges in the Kitherbee-Sherman iron mines at Mineville, N. Y. 6. Practical work in the quarries of the Calcite Quarry Co., Myers-town, Pa. 7. Practical blasting in several quarries and open-pit mines.

Jan 1, 1927

By E. Eichen, G. S. Ansell. L. R. Sefton

A Technique for the Preparation of Thin Films of Two-Phase Alloys Suitable for Use in Transmission Electron Microscopy In order to obtain foil sufficiently thin to permit transmission electron microscopy of two-phase alloys, particularly alloys in which the second phase is present as a very finely dispersed second phase, a technique has been developed to permit the thinning of these materials without either the large degree of pitting present in the electrochemical or chemical thinning process or the slicing of the second phase particles accompanying the mi-crotoming process. The metal or alloy to be thinned is first ground to initial sheet thickness of approximately 0.002 in. by hand grinding on 4/0 emery paper. This starting sheet of material is then reduced in cross section by an air-abrasion technique using an S. S. White dental abrasive unit. This unit consists of a supply of compressed CO, which provides a stream of high velocity gas impinging on the metal surface. Incorporated in the machine is a hopper-type of device in which fine abrasive particles of alumina are introduced into this high velocity gas stream. The abrasive particles are irregular in shape, approximately 30 across. If any particles are introduced into the sample during thinning, they should be readily observable. Impingement of this gas abrasive mixture on the metal surface causes rapid removal of the metal in a rather uniform manner. The rates of metal removal may be adjusted by both regulating the gas pressure and amount of abrasive material introduced into the gas stream. By moving the gas stream abrasive mixture slowly about the specimen or sheet surface, a large area of the sheet may be uniformly reduced to a thickness which is then suitable for use in transmission electron microscopy. Attendant with this metal removal is a result in cold working of the metal surface due to the impingement of the abrasive particles. The resultant foils, therefore, if made from materials which are desirable to view in the annealed condition, have to be subsequently heat treated. If the alloy from which these foils have been made has been initially heavily worked or deformed during manufacture, then no subsequent heat treatment is, necessary as in the case of the SAP-type alloys. Following this initial abrasive thinning technique, the material is then given a final electropolish which is just sufficient to remove any oxide which has formed on the metal surface during the abrasion technique. Care has to be exercised in this technique to make sure that none of the attendant problems associated with the chemical or electrochemical removal process are encountered. An electrolyte solution which has been found suitable for aluminum-aluminum oxide SAP materials is one containing 78 ml of perchloric acid, 120 ml of distilled water, 700 ml of ethanol, and 100 ml of butylcellosolve. The current density used is 1 amp per sq cm and a polishing time of 3 sec on each side of the foil is used. Extreme care must be used in choosing the current density and time to ensure that just the oxide film on the specimen is removed. Times or current density which are greater than this will lead to perforation of the film due to the removal of the A1,0, particles or a complete loss of the film due to complete solution of the matrix. Once the oxide film is removed the specimens must be kept in alcohol until placed in the microscope to prevent any further oxidation. Fig. 1 shows -an electron micrograph at X28,000 of a thin foil of an aluminum-aluminum oxide SAP-type alloy prepared using this technique. The alloy consists of a matrix of commercial purity aluminum containing a very finely dispersed second phase of aluminum oxide flakes. In the electron micrograph, the dark patches are the aluminum oxide particles. The lighter portions of the micrograph are the aluminum matrix. Within the aluminum matrix, the dislocation structure of the alloy is clearly visible. This structure consists of intersecting twin boundaries and single dislocations. No abrasive particles were observed in the samples. In addition, thin films of commercial purity aluminum were prepared using this method and observed in the electron microscope. Here also, there was no evidence of abrasive particles introduced in the samples. The technique presented provides a satisfactory method for the production of thin films of aluminum-aluminum oxide SAP-type alloys for use in transmission electron microscopy where none of the usual thinning techniques appears to be satisfactory.

Jan 1, 1962

By M. Kitada, U. Kawabe, F. Ishida, T. Doi

The relations between micros tructures and critical current density in transverse magnetic field were experimentally investigated due to each transformation of the 0 to 0' + P" phases at 700' C for superconductmainly examined using replication electron microscopy. The ß' or a precipitates were found to pin down magnetic flux lines in these alloys. The effects of precipitation upon the critical current density were discussed in relation with the size, spacing, and characler of these precipitates. HIGH magnetic field superconductors, such as Nb-Zr, Nb-Ti, and Nb-Zr-Ti alloys, have been recently put to extensive practical use as winding materials for superconducting magnets.13 The critical current density of these hard superconductors under an applied magnetic field is an important characteristic for magnet materials and is very sensitive to metallurgical structure. It is generally known that the critical current density is increased by introducing dislocations and precipitates into a superconductor; that is, dislocations and precipitates are presumed to be barriers that hinder quantized flux lines from moving.4'5 Theoretical6'7 and experimental analyses of the motion of flux lines and the interaction between flux lines and various defects have already been reported by many authors. Metallographic analysis of high magnetic field superconductors such as Nb-Zr and Nb-Ti is difficult, so that no quantitative relationship between microstruc-ture and critical current density has been established yet. In this paper, the effect of precipitation on the critical current density in magnetic field was investigated for two superconducting alloys, Nb-40Zr-10Ti and Nb-5Zr-60Ti. In these alloys the resistive critical field H, at 4.2oK was about 100 kG and the critical current density Jc at 80 kG was of the order of 104 amp per sq cm.13-l5 The superconducting properties were examined in relation to the microstructural changes due to transformation of i) the ß to ß' + ß" phases at 700°C for Nb-40Zr-10Ti alloy and ii) the ß to a + ß phases at 500°C for Nb-5Zr-6OTi alloy. The effect of size, spacing, and character of precipitates on flux line pinning was in particular examined. The microstructures were studied by means of residual resistivity, microhardness, and tensile strength measurements as well as by X-ray diffraction, optical, and replication electron microscopies. I) EXPERIMENTAL PROCEDURE Pure niobium, zirconium, and titanium, in the form of rods 0.8 cm in diam, served as raw materials. Results of chemical analyses of these rods are given in Table I. Ingots of the alloys, 0.4 cm in diam and 3 cm in length, were prepared by means of levitation melting, utilizing a copper mold in an argon-gas atmosphere. Samples from the ingot then were cold-worked by grooved mill to 0.2 cm in diam, heat-treated homogeneously (in the ß phase region) for 5 hr at 1100° in a vacuum of 1 x 106 Torr, and finally cold-drawn to 0.025 cm in diam. For heat treatments, samples were wrapped in niobium foil and sealed in an argon-gas atmosphere in fused quartz capsules. Water quenching was done after each heat treatment. Subsequently H-J, were performed at 4.2° by slowly transporting the current through the samples 4 cm long, under transverse magnetic field, until the least detectable resistive terminal voltage was observed. The resistive critical field H, was taken as the field at which 100 pv appeared at 4.2°K across a sample 3 cm in length, with a current of 5 ma. The critical temperature T, was measured by means of a conventional four-probe resistivity technique and taken as the temperature at which the sample resistance reached one-half of full restoration of the normal-state resistance with a current l ma flowing through a sample 2 cm in length. Precipitates were observed by means of optical microscopy and carbon replication electron microscopy. The etching solution consisted of 5 ml HF, 10 ml H2SO4 10 ml H2O2, and 50 ml H2O, and shadowed carbon replicas were examined in a itachi HU-11 electron microscope operated at 50 kv. X-ray diffraction photographs were taken by a 11.46-cm-diam Debye-Scher-rer camera using copper Ka radiation. The micro-hardness was measured under a load of 200 g using

Jan 1, 1969

To the Members It has been, and is the endeavor of the A. I. M. E. to serve each and every member. One of the means of letting the membership know what is going on in the mining; metallurgical and chemical fields, and by far the most important, has been our monthly Bulletin. To publish this costs money, and to partly defray the costs, it was decided to accept such advertising as could be secured. The A. I. M. E. is the only one of the American National engineering societies whose dues are as low as $10 per year, and it actually spends more upon the Bulletin and Transactions than the sun total it receives for clues. Hence the need of advertising revenues. We are planning even greater improvements for your Bulletin-improvements that will help you in your work. It will mean a better publication, with more information than ever before. To successfully carry out our plans, we must have your co-operation. We are not asking you for financial, but for your moral support. With that we shall accomplish a great deal. What we ask of you, brother member, is to give evidence to those patronizing our advertising pages, that you not only read the editorial pages, but the advertising section as well, and that you have in mind the welfare of your Institute by consulting the advertising pages when in the market for equipment. Do you realize that if you mention your Bulletin when writing advertisers or purchasing supplies, that not only would your publication secure more advertising, but better satisfy present advertisers. We have reason to know that our advertisers secure business as a result of our publication, but they demand some evidence that you see their advertisement. Unfortunately, our members do not as a rule mention where they saw the advertisement, and as a consequence advertisers have no means of knowing whether their investment in the Bulletin is paying. The A. I. M. E. Bulletin can be made the best advertising medium in the mining, metallurgical and chemical fields, simply by each member doing his bit. It is very little to ask of you, and the returns to the mining industry will be enormous.

Jan 9, 1915

By R. L. Manegold

IN RECENT years there has been a decided trend toward bringing ores and coal out of open-pit and underground mines by long, sloping single-stage belt conveyors. Because the high investment cost of haulage conveyors dictates maximum speed and full loading for economy, conveyor belts are running faster than ever before, with a greater burden on the belts. In addition, larger blocks of ore are being mined and conveyed. Rougher use of large mining equipment generates more tramp iron; mechanical loading rejects nothing. Therefore the extraction of tramp iron and other deleterious materials for the protection of haulage conveyors at transfer points, chutes, and idlers is becoming an increasingly difficult job. In our experience, the best method of protecting long haulage conveyor belts is to extract the tramp iron, at least the large tramp iron, ahead of the main haulage conveyor or series of conveyors. It is most practical to collect the tramp iron at the earliest source -possible, usually directly after the primary car unloading dump or after the primary crushers, which are ordinarily not affected by tramp iron, see Fig. 1. The coal or ore from its primary source is fed by chutes or feeders onto a buffer or shock belt conveyor, a short, ruggedly built conveyor system that can be considered somewhat expendable. Its primary function is to bring the ore up to speed for transmission to the haulage conveyor. There is no assured method of protecting this conveyor from tramp iron damage at its feed end. Likewise, there is a possibility, although remote if the magnet applied to this belt is installed correctly, that the tramp iron extraction process will damage the shock belt, which is, however, short and comparatively inexpensive. Magnetic head pulleys with their maximum effective range of about 8 or 10. in. cannot be considered for large installations, even though they are desirable because of the continuous and, automatic tramp, iron removal feature. Further, the most dangerous form of tramp iron with respect to potential damage to a haulage conveyor is the long rod, roof bolt, or rail segment, which is not extracted satisfactorily because of the limited tangential contact of such an iron shape with the magnet. Magnetic head pulleys are also undesirable because the dribble or fines from the head pulley discharge at the same point as the tramp iron. Screens must be used to separate the fines from the magnetics, resulting in additional expense and loss of head room. Magnetic detectors have been used with success, but they only indicate the, presence of iron, and the conveyor belt must be stopped for its manual removal. The, stoppage of any conveyor means that all preceding equipment must be stopped or a cascade of material on the idle conveyor will result. Occasionally combinations of detectors and magnetic, head pulleys are used. The detector precedes the magnetic head pulley and detects only large pieces of tramp iron, while the magnetic pulley subsequently takes out the smaller ferrous metals. Suspended magnets overcome the disadvantages of magnetic head pulleys, detectors or a combination of both. There are several magnetic extraction problems involved in applying a suspended magnet at this

Jan 1, 1952

By Henry Drinker

The Institute has lost a valued member by the death of Eckley B. Coxe, Jr. He bore the name of one who was largely instrumental in founding the Institute, and to whose support and guidance as active member, Vice-President, and President, the Institute owes. much. Eckley B. Coxe, Jr., was the nephew of the late Eckley B. Coxe. He held a large interest in the coal estates owned and developed by his family, and he was thus naturally led to take a continuing interest in mining matters, and for years and up to the time of his death was a full member of the Institute. He died at his residence, Drifton, Pa., on Sept. 20 last, aged 44. He was a member of the class of '93 of the University of Pennsylvania,. of which great institution he was a devoted alumnus. His educational and charitable activities were numerous, but his chief life-work and interest was in archeological investigation and research in Egypt, carried on through the Museum of the University of Pennsylvania of which Museum he was President. The discoveries made by the various expeditions financed and directed by him, and the notable publications issued by his direction and at his expense, chronicling the results, are among the most important researches ever made of buried Egypt. Mr. Coxe was a member of the International Historical Society and of many educational and charitable organizations. By his will, among other bequests, he left $500,000 to the Museum of the University of Pennsylvania and $100,000 to the University, the income of the latter fund to be applied to increasing the salaries of the professors of the Institution. He also left $100,000 to the Children's Hospital of Philadelphia, of which he was a manager, and in addition thereto $10,000 of which the income is to be applied in providing Christmas presents for .the child patients, and in providing an annual dinner for the patients and attendants of the hospital. He bequeathed $50,000 to Leonard Hall, an associate mission of the Episcopal Church, at South Bethlehem, Pa., $25,000 to the Epileptic Hospital and Colony Farm (Philadelphia) ; $50,000 to the Philadelphia Orthopaedic Hospital and Infirmary for Nervous Diseases; $15,000 to the United Charities of Hazleton, Pa., the income to be applied to the salaries of nurses; and $25,000 to the Mining and Mechanical Institute of the Anthracite Coal Region of Pennsylvania, founded by his uncle, Eckley B. Coxe, and of which Eckley B. Coxe, Jr., was an active trustee up to the time of his death. This Institute is known as one of the best preparatory schools for technical education in Pennsylvania, and is mainly devoted to extending an opportunity for education by day and night schools to the boys and young men of the Anthracite Region. Its principal is an alumnus of Lehigh University; it has an able local Board of Trustees, and an Advisory Board consisting of the Provost of the University of Pennsylvania, the President of Lafayette College, and the President of Lehigh University, all three of which institutions have established prize scholarships in the institute. Mr. Coxe carne of a distinguished ancestry, the record of which is fully given in the biographical notice of his uncle, Eckley B. Coxe, by Dr. R. W. Raymond, in Vol. XXV of the Transactions.`

Jan 12, 1916

By F. M. Stewart

A paper by Hurst and van Ever-dingen in 1949 led to the practical solution of many nonsteady-state flow problems.' Subsequently, applications of this material have been discussed by several authors. The purpose of this note is to outline a simplified direct procedure for water-influx pressure predictions for pressures above the bubble point. The prcposed procedure is unique in that after the "time-conversion factor" and the "influx constant" are obtained, predictions are made without trial and error. The elimination of trial and error is made possible by expressing certain PVT characteristics as explicit functions of pressure. The procedure is applicable to fields producing at pressures above the bubble point and under radial water drive from an infinite aquifer. In the usual applications it is required to predict (1) withdrawals given future pressure history or (2) reservoir pressure, given future withdrawals or production. The theory, assumptions and conditions under which the nonsteady-state solutions hold are covered in the references and are not repeated. The simplified direct procedure outlined here has been developed from published solutions for the so-called "pressure case". A similar direct procedure for the same special conditions has been developed for the "rate case"; however, in this instance the procedure is lengthy and offers no advantage over the trial-and-error solution. Consequently, this paper covers only the procedure based on the pressure case. DISCUSSION Under the pressure case prediction of withdrawals from a water-drive field, given the future pressure history, involves the use of a nonsteady-state water-influx term together with the material balance equation. The solution of a particular problem requires the following steps: (1) division of past pressure and production data into equal time intervals; (2) computation of cumulative water influx vs pressure drop for each time interval of past history using the material balance equation; (3) determination of the best values for the "time-conversion factor" and the "influx constant" by equating the nonsteady-state influx term with the influx computed in Step 2 (this requires a trial-and-error procedure); (4) prediction of influx for a given pressure drop using the influx term and the computed factors from Step 3; and (5) calculation of fluids produced using the predicted influx in the material balance equation. A forecast of the water-oil ratio or water production rate is required to complete the calculation. It is assumed that a reliable estimate of original oil in place is available, as well as the production and pressure history, and data on reservoir fluid characteristics. If the original oil in place is unknown, it may be computed simultaneously with the tinie-conversion influx factors2,3. However, the oil in place so computed may be considerably in error3; consequently, it is usually preferable to use oil in place estimated from pore-volume data unless there is considerable doubt as to its accuracy. The Material Balance Equation Above the Bubble Point Above the bubble point the simpli-

By Arthur F. Taggart

The quality of aggregate materials is. of major importance in governing durability and permanence of concrete structures. The problem of selecting suitable aggregate materials is two-fold. Geological factors include the type and character of the aggregate source, presence of known or suspected reactive constituents, and presence of thermally incompatible materials. Laboratory investigations include petrographic studies, soundness and reactivity tests, and tests of thermal properties. The importance of each factor in the selection of satisfactory aggregate material is considered in detail.

Jan 1, 1950