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By R. Grierson, L. J. Bonis

The high-temperature Strength oF TD nickel has been observed to be dependent upon the previons thermal and mechanical history of the material. Variations in both the level and the anisotropy of strength have been observed. 01 this paper- these variations are correlated with the storing of annealing resistant elastic strain energy in the matrix of the TD nickel. An x-vay line -broadening tecknique is used to measure the maLrTis elastie strain. THE inclusion of a finely dispersed second phase into a ductile matrix has long been recognized as an extremely effective method of strengthening the matrix both at high and at low homologous temperatures. It has been found, however, that the factors which determine the high-temperature strength are not the same as those which are important at low temperatures. Below 0.5 Tm the size and distribution of the second phase particles are of prime importance in determining the strength,')' while above this temperature the strength is mainly dependent upon the previous thermal and mechanical history of the alloy,3-7 This paper is primarily concerned with explaining the response of the high-temperature mechanical strength of one of these alloys (DuPont's TD nickel) to various thermo-mechanical treatments. It will be shown that this response is not associated with the occurrence of any form of dislocation substructure within the matrix of the alloy. It has been found, however, that a correlation does exist between the elastic strain level in the matrix and the previous thermomechanical history of the alloy and that the observed changes in elastic strain level parallel the measured changes in high-temperature strength. It therefore must be concluded that variations in high-temperature strength are a direct result of the variations in elastic strain level. MATERIAL TD nickel contains approximately 2 vol pct of Tho2 in an unalloyed nickel matrix. It is formed, as a powder, by a chemical technique and this powder is compacted to form ingots which are then extruded to give 21/2-in.-diam rod. Rod of smaller diameter is prepared from the as-extruded rod by swaging. In the studies reported in this paper, 1/2-in.-diam rod was used. This rod received an anneal of 1 hr at 1100°C prior to being used in any of these studies. EXPERIMENTAL TECHNIQUES Two methods were used to examine the structure of the nickel matrix of the TD nickel. These were: 1) transmission electron microscopy; 2) the analysis of the position and profile of X-ray diffraction lines obtained using the nickel matrix as the diffracting media. To prepare thin foils for electron-microscopical examination, slices of TD nickel approximately 0.050 in. thick were cut from the as-received 1/2-in.-diam rod. These were then chemically polished down to 0.045 in., rolled to 0.009 in., given a predetermined heat treatment, and thinned, using a modified Bollman technique, to provide the foils for observation. All observations were carried out at 100 kv, using a Hitachi HU-11 electron microscope. Specimens of the undeformed rod were prepared by grinding down the 0.050-in.-thick slices to approximately 0.015 in. and then thinning chemically and electrolytically to give the thin foils. The X-ray specimens were prepared by rolling 0.375-in.-thick rectangular blocks down to 0.075 in. The surfaces of the rolled material were ground flat, chemically polished to remove the layer disturbed by the grinding, and given a predetermined anneal in an inert atmosphere. They were then ground lightly to check their flatness and given a final chemical polish prior to being examined. The X-ray diffraction line profiles were measured using an automated Picker biplane diffractometer. A special specimen holder was built to allow a more accurate and reproducible positioning of the specimen. The line profiles were determined by carrying out intensity measurements at intervals of either 1/30 deg or 1/60 deg over a range of 3 deg on either side of the nickel peaks of interest. A piece of pure nickel which had been recrystallized to give a large grain size was used as a standard to give the X-ray line profile generated by a strain-free matrix. The analysis of the X-ray diffraction line profiles is a modification of that due initially to Warren and Aver-bach8and has been described elsewhere.3 This analysis gives a measurement of two parameters associated with the structure of the nickel matrix. These parameters are: 1) the size of the coherently diffracting domains within the nickel matrix; 2) the magnitude of the elastic strains in these domains. Both of these parameters are first determined in terms of a Fourier series. These series are obtained from other Fourier series which describe the measured profile of the X-ray diffraction lines. Thus, for both the coherently diffracting domain size and the elastic strain level, it is possible to plot Ft (the Fourier coefficient) against t (the term in the Fourier series), where t can be expressed in terms of a distance L and the Fourier coefficient Ft(S) (associated with elastic strain level) can be expressed in terms of the root mean square strain (e2)1/2. Thus a plot of (F 2)1/2 vs L can be obtained. Plots of this type are shown graphically in Figs. 6 and 8. Interpretation

Jan 1, 1968

By Robert F. Mehl

METALLURGISTS are properly interested in papers dealing with subjects ranging from the theories of the metallic state to very practical details on the use of metals. A review of theoretical metallurgy naturally excludes papers concerned with the usefulness of metals and limits itself to those concerned purely with the science of metals. Even in this more limited field the reviewer is confronted with thousands of papers dealing with facts and theories of metallic behavior, from which he can select only a few hundred. The selection is necessarily highly arbitrary. Certain classes of papers definitely fall within the scope of this review. Thus, papers on the deformation of metals, on the structure of alloys, on recrystallization, to select only a few, are fully represented. Other subjects, which verge on what is generally accepted as the science of metals, such as the magnetic properties of metals, the less familiar electrical properties and theories, adsorption of gases by metal surfaces, and the like, are treated scantily. Particular attention is given to reviews of subjects that fall with in the groups chosen; in a summary such as this, which is largely in the nature of a progress report, capably written reviews are of importance, particularly since the monograph and text book literature is so meager in this field. THEORIES OF STATES OF AGGREGATION The electron theory of metals and the relation between possible electron structure and the magnetic properties have been discussed (317.307)† the electron theory of liquid metals, especially with respect to electrical conductivity, has been considered(306).

Jan 1, 1935

By Persifor Frazer

(Read at the Amenia Meeting, October, 1877.) IT has been the aim of the writer, by measuring his base line on the territory of theoretical chemistry, to attempt to fix by triangulation certain points within the domain of mineralogy. As the barest first experiment in this direction, a few of the hydrated oxides of iron have been selected, their theoretical construction reduced to percentage of the constituents into which the ordinary analytical methods would resolve them, and the results compared with actual analyses compiled from the most reliable sources; the accidental errors being as much as possible eliminated. This method seems to be a simple one and one easily pursued, but, as will shortly appear, it is beset with grave difficulties, all of which the writer does not pretend to have satisfactorily surmounted. In the first place arises the important question, what are we to understand by the hydrated oxides of iron ? In all books of chemistry and lexicons of minerals, the proposition, long ago taught by the earlier chemists, that water might exist in two forms of combination, viz., as water of crystallization or as water of constitution, is tacitly assumed. There is nothing in the principles of the new chemistry which is opposed to this ; for (to carry the mind's eye into .the process of construction of the least units into which a definite chemical compound is capable of being divided without losing its characteristic properties), however unlikely it may seem, it is, nevertheless, possible that a given molecule of iron may, under certain conditions of heat, pressure, etc., attract to itself as many molecules of the water in which it is natant as from the relative size, shape, attractive force, etc. of either, it is capable of taking up, and this complex system of associated molecules might oscillate as a physical unit so long as the conditions on which its existence was dependent remained unchanged. Moreover, it is highly probable that the first effect upon such a molecule produced by physical or chemical forces would be to separate it into two or more simple ones of different kinds, while a further application of these forces might rend asunder the bonds of the simpler compounds themselves.

Jan 1, 1878

By J. P. Savely, D. E. Nicholas, R. D. Call

Progress in the technology of slope design over the past 15 years now permits the selection of rational slope angles if suitable data on geology, hydrology, and rock properties are available for a specified project. Although a full-scale slope design study remains the best course of action, there are situations where an extensive study is not feasible due to time or budget constraints. Two typical examples are: (a) selecting pit slope angles for a preliminary feasibility study at the exploration stage; and (b) coping with a slope failure in an operating mine. In both instances, slope angles must often be chosen on the basis of data that are currently available or can be readily obtained. All too often during exploration programs, a feasibility study is initiated shortly before the decision deadline to drop the property or proceed to purchase. If the only existing data at this point are a few cross-sections at odd angles showing ore and waste contacts or a dog-eared map of the surface geology, there may not be time to collect and organize sufficient information for the design of slope angles. On the other hand, if during the drilling program geologic cross-sections were constructed and the structural data compiled in tabular form, rational slope angles could be computed within the allotted time.

Jan 4, 1977

By Baxter C. Madden

Stress corrosion is defined and certain examples are illustrated. A number of test methods, to determine the resistance of materials to stress corrosion, are being developed at Wright Field. The criterion as to the validity of a method is stated. Three types of specimens and the method of stressing each type are described. Five different corrosive conditions are set forth. The results of tests to date, although too few for any general conclusions to be arrived at, are presented. The program for the continuation of the investigation is indicated. A bibliography is included. The development of the method of loading a cantilever-type specimen, so that a nearly constant stress at a large deflection may be realized, is presented as Appendix I.

Jan 1, 1945

By R. G. Green, R. L. Dowdell

LEAD POISONING as a result of eating lead pellets deposited in marsh areas is a cause of high mortality among ducks, geese, and other waterfowl ingested lead shot become trapped in the gizzard with gravel and are slowly ground away by the grit. Absorption of lead as it passes through the intestine in a finely divided state produces severe lead poisoning which is usually fatal. Ducks and geese with lead poisoning develop first a typical green diarrhea. Later, paralysis of the wing muscles prevents flight. As the poisoning continues with further grinding of the shot trapped in the gizzard, increasing paralysis reduces the bird to helpless-

Jan 1, 1937

By Persifor Frazer

It has been the aim of the writer, by measuring his base line on the territory of theoretical chemistry, to attempt to fix by triangula tion certain points within the domain of mineralogy. As the barest first experiment in this direction, a few of the hydrated oxides of iron have been selected, their theoretical construe tion reduced to percentage of the constituents into which the ordinary analytical methods would resolve them, and the results compared with actual analyses compiled from the most reliable sources; the accidental errors being as much as possible eliminated. This method seems to be a simple one and one easily pursued, but, as will shortly appear, it is beset with grave difficulties, all of which the writer does not pretend to have satisfactorily surmounted. In the first place arises the important question, what are we to understand by the hydrated oxides of iron ? In all books of chemistry and lexicons of minerals, the proposition, long ago taught by the earlier chemists, that water might exist in two forms of combination, viz., as water of crystallization or as water of constitution, is tacitly assumed. There is nothing in the principles of the new chemistry which is opposed to this; for (to carry the mind's eye into the process of con struction of the least units into which a definite chemical compound is capable of being divided without losing its characteristic proper ties), however unlikely it may seem, it is, nevertheless, possible that a given molecule of iron may, under certain conditions of heat, pressure, etc., attract to itself as many molecules of the water in which it is natant as: from the relative size, shape, attractive force, etc. of either, it is capable of taking up, and this complex system of associated molecules might oscillate as a physical unit so long as the conditions on which its existence was dependent remained unchanged. Moreover, it is highly probable that the first effect upon such a mole cule produced by physical or chemical forces would be to separate it into two or more simple ones of different kinds, while a further ap plication of these forces might rend asunder the bonds of the simpler compounds themselves.

Jan 1, 1879

By J. S. Bryner

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

Jan 1, 1948

By Ernst A. Hauser

IN a paper published three years ago,' the term "silicic chemistry" was used for the first time to emphasize the increasing importance of the chemistry of silicon in science and technology. The development through which the colloid chemistry of siliceous matter has gone since then is in itself ample proof that the coining of this new term for this branch of colloid science was not presumptuous. Until quite recently, however, silicic chemistry concerned itself only with the composition and colloidal properties of natural and synthetic siliceous matter, but had not paid much attention to the genesis of this matter, particularly to that of the clay minerals. What is even more disturbing, particularly from an educational point of view, is the fact that neither mineralogy, geology, nor metallurgy has fully realized the important role colloidal phenomena must have played in the genesis of our planet and the formation of minerals generally speaking. Considering the importance of colloid chemistry today in the fields just mentioned, it is not surprising that the theories most agreed upon by geologists and mineralogists for the origin of clay minerals are not acceptable from a strictly colloid chemical point of view for the genesis of these most important and most abundant components of the earth. Of all the theories pertaining to the origin of clay minerals, those still most accepted by geologists and mineralogists are the "residual clay" and the "transported clay" theories.15 The former is based primarily on the assumption that the formation of clay minerals is the result of surface weathering of fresh rocks, or is due to the action of solutions. Taking the action of water on orthoclase as an example, the most recent ideas have been summarized by H. Jenny13 as follows:

Jan 1, 1952

By G. D. Van Arsdale

This paper describes a series of experiments leading to the development of a method for leaching the mixed ores of the Inspiration Consolidated Copper Co., containing chalcocite and silicates of copper, by the use of solutions acidified with sulfuric acid and carrying ferric sulfate. Iron is added to the solutions and ferric iron is regenerated electrolytically to a percentage high enough to act as an effcient solvent. The decreased yield is partly compensated for by a higher current density. An important problem in modern copper metallurgy, particularly in the Southwest, has been to obtain good recoveries from what are commonly known as mixed ores; that is ores in which the copper occurs partly as oxide and partly as sulfide compounds. The dividing line between mixed ores and ores commonly accepted as concentrating is not definite. In other words, much ore now being concentrated carries considerable copper in non-sulfide form, on which recoveries are not so good as on ores carrying less of these constituents. While treatment by concentration may be commercially profitable on ores carrying oxide copper within certain limits, there are large deposits for which the application of concentration could not be considered, and yet which have not been considered amenable to leaching because they carried too much sulfide. The Inspiration Consolidated Copper Co. has large amounts of such mixed ores, and this paper is an account of the experimental work by which a method was developed for their treatment, and for which a large plant is now being erected by the Inspiration Co. It is not claimed that the method is a general solution of the problem of mixed-ore treatment but it is apparently well adapted for leaching the ores of the Inspiration Co., for which it was designed. The work done has covered preliminary laboratory and test-plant investigation, and a pilot-plant run, extending from March to the middle of December, 1923. Thoroughly consistent and satisfactory results were obtained continuously for more than six months in the pilot plant; and it is believed that the results and probable costs that can be had on a large scale have been definitely proved. The method, however, was designed for local conditions; and while the basic principles are general, there are ores on which it will not work and other ores for which considerable modification may be required.

Jan 1, 1926

By H. F. Moore

AT PRESENT, I am connected with an investigation of the so-called fatigue of metals under stress. So far we have studied the more fundamental and simple case of the repeated stress, without the additional complexity of impact, which might bring in other factors. We feel that this investigation, which has been in active progress for a little over a year, has shown more conclusively than has been shown before that steel under repeated applications of stress, reversed from positive to negative, will not fail below some fairly clearly defined limiting stress that,, so far we can see, does not bear any definite relation to the ordinary elastic limit, being as large as the elastic limit in some cases and about one-half the elastic limit in others. I might be asked, first, what is fatigue. The old view is summed up "in the word "crystallization." The idea was that under repeated stress the material changed its crystalline structure. I do not know of any evidence in favor of the theory that metals materially change their crystalline structure under repeated stress. The crystals are broken under repeated stress. The second theory, advanced by Bauschinger, the German scientist, is that under repeated stress some inherent property of the material changes its elastic limit; it is an inherent property of the material, possibly some property of the amorphous cement between the crystal. The third view is that all fatigue of metals is the result of the spread of damage from little localized overstresses. I do not feel justified in stating my positive belief in the third view as against the second, but I have yet to run across a case of failure of steel or other metal, either in the laboratory or in service, that could not be explained by the gradual spread of damage from some nucleus. We have found, for example, that it is possible to subject a homogeneous steel, like Armco iron or a 0.90 per cent. carbon steel, that hag been thoroughly annealed, to one hundred million reversals f stress as high as the elastic limit of the steel with no sign of failure. We stopped the test at one hundred million because the machines Were required for other work. Forty-five days, continuous running at 1500 revolutions a minute is required to produce one hundred million repetitions. On the other hand, a complex structured steel, like a chrome-nickel steel that

Jan 6, 1921

EVERY English-speaking mining, engineer or geologist knows that some terms used by his profession are not rigid but vary regionally; for example: what is called a vein by some, is called a lode by others and is known as a reef to their Australian colleagues. There are parallels in, the German language. Since, in addition, the meaning of some words may change considerably in 450 years-and other words may disappear completely-and not only the terminology but the concepts of a science are subject to drastic changes over such a long period of time, translating the Bergbüchlein posed some interesting problems. Old German texts and glossaries such as C. T. Delius' Anleitung zu der Bergbaukunst (1773), Minerophilus' Neues and Curieuses Bergwercks-Lexicon (1730), and H. Veith's Deutsches Bergwörterbuch (1871) proved useful sources of information when defini¬tions of obscure terms were needed. The task of translating was made even more challenging by the author's personality. As Ulrich Rülein von Kalbe was primarily a physician, his information must have been mostly secondhand. Since the nomenclature of the miners of Saxony, where he gathered his material on silver ores, undoubtedly varied from that of the German miners in Hungary, for instance, who probably supplied him with data on gold ores, it is not astonishing that he is not consistent in his use of some expressions. To give an example: there is every indication that Flöz and schwebender Gang (see footnote p. 21) are used interchangeably in spite of his occasional disapproval of such usage. It is obvious that he was an educated man with a questing and active mind and, although he apologizes-not wholly sincerely, one might suspect-for the simple

Jan 1, 1949

By V. R. Garfias

A survey of the resources of mineral fuels, coal, petroleum and natural gas presupposes a clear distinction between the known amount underground and the "proven reserves"; the'portion that can be economically brought to the surface and made available for utilization. Only a fraction of the coal and petroleum in producing fields is or can be economically brought to the surface and not all of this is economically utilized; also, although practically all the natural gas can be economically recovered and utilized, in actual practice a large part of the total volume that reaches the mouth of the wells is wantonly blown into the air and wasted. It is thus estimated that of the total amount of coal underground about 40 per cent remains unrecovered, or is otherwise wasted, before it reaches the consumer; that only some 25 per cent of the petroleum in proven fields is actually brought to the surface; and that even if practically the entire volume of natural gas can be economically utilized, in actual practice close to 25 per cent of the total produced is now absolutely wasted. And the dissipation of this gas, unwarranted as it is, not only diminishes the gas supply but diminishes also the proven reserves of petroleum from such fields as the Panhandle of Texas, where petroleum and natural gas are produced simultaneously. Many factors affect the estimates of the proven reserves of mineral fuels, such as the capacity and nature of the reservoir, its depth, the quality of the product, the efficiency of recovery, the price of the fuel and its byproducts, etc., etc., but superseding at times all of these in connection with petroleum and natural gas deposits is the effect of "subsoil ownership" on the rate and methods of exploitation of the deposits. As a result it should be a comparatively simple matter to eliminate waste and overproduction, and thereby increase the proven reserves of petroleum and natural gas, in Russia, Iran and Iraq, where the subsoil rights are nationalized, or in any country in which there is or can be quickly established an effective legal control of the underground deposits and the manner of their exploitation. It has been and it is now, on the other hand, almost an impossible undertaking to intelligently regulate the petroleum and natural gas production in the United

Jan 1, 1935

By O. R. Bergmann

Two approaches were taken to obtain direct experimental evidence jar the existence oj a jet in the explosion-cladding pvocess: 1) direct observation of the claddirg jwocess by rtzeans ojf kig-h-speed photography using a fvartziiy catnera and 2) use of a plated-surface experiment in contribution with clzetrzical analysis. The framing-camera records showed clearly the presence of a jet it1 the form of what appears to be a line spray. The jet velocity is considerably highev than the detonation velocity arid in vacuum it is almost twice as high as the detonatiou velocily. The results jrorrz the plated-surface experiment also corzfivtned the preseizce of- a jet. The artzoutlt o,f etzergy dissipated in the jetting process was foundd lo be consislent with the basic theovetical model o/ the cladding mechanism.. MaNY reports on metal working with explosives have appeared in the literature during the last few yearsThis paper describes experiments concern- ing the mechanism of the explosive metal-cladding process. It has become increasingly important as a unique method for bonding metals and a typical cladding arrangement is shown in Fig. 1. A theoretical analysis of the mechanism of explosive bonding and a description of the nature and types of bond zones obtained was given by Cowan and oltzman." A further discussion of the basic principles of the process, a detailed description of the different bond-zone types, and extensive information on the properties and the applications of explosively bonded metals was recently published by Holtzman and cowan. " The process is now in commercial use by E. I. du Pont de Nemours & Co. The concept of the existence of a jet during metal bonding with explosives forms a central part in the theoretical analysis of the cladding mechanism described by Cowan and Holtzman When a layer of explosive is detonated on a metal plate that is separated from a second metal plate by a small distance the metal plate in contact with the detonating explosive is accelerated by the detonation pressure. An angle is established between the undeflected and deflected portions of the plate. Subsequently the deflected portion of the first plate collides with the second metal plate.

Jan 1, 1967

By H. R. Peiffer, R. Geckle

The silver phase of silver and finely divided alumina composites is shown to grow as single crystabs upon solidification from the melt. These crystals grow without the aid of an externally applied thermal gradient or a mold. The single-crystal growth is more readily disrupted as the alumina content varies from the optimum concentration of 20 wt pct. Pretreatment such as variation of fabrication pressure, and presintering of the specimens appear to play a lesser role in this phenomenon. In actual practice the growth of single crystals of metals from the melt is a tedious, painstaking process.' Care must be taken to insure the proper thermal gradients and rate of growth in a vibration-free environment. Excellent single crystals can be grown when these variables are controlled. When a second insoluble and finely divided phase is present in the melt the growth of single crystals is difficult, if not impossible, even under the most favorable conditions outlined above. During the past few years, a composite of silver and alumina has demonstrated an ability to resist flow even though the major phase, silver, is mo1ten. 2 A more surprising feature of this material is the ease with which single crystals of silver grow upon cooling the composite from temperatures above the melting point of silver to temperatures near room temperature. Observations have been made that demonstrate that single crystals of silver will grow even when conditions most unfavorable for growth of pure silver crystals exist. The crystals grown in this manner are imperfect in that a great deal of subgrain structure exists. It is the purpose of this manuscript to qualitatively describe this process and to attempt to isolate the influencing factors of this behavior. MATERIAL PREPARATION The composite material is prepared by powder-metallurgical techniques. Two items of great importance are the introduction of oxygen into the system and the obvious need for a thorough mixing of the metallic and refractory oxide phases. The oxygen is necessary in order that the silver wets the alumina. Without oxygen the phases separate and the material shows no unusual properties. In order to supply the needed oxygen the silver is added in the form of silver oxide which is readily decomposed to oxygen and silver upon heating. The silver oxide is readily obtained in a finely divided form that allows a uniform mixture of the alumina and silver oxide to be prepared. The correct ratio of alumina to silver oxide is mixed in the presence of alcohol in an ordinary food blender. The mixture has the consistency of a thin slurry and after mixing for approximately 20 min is dried and pressed into billets at various pressures. As is shown in Fig. 1, there is no limit to the shape of the specimens obtainable as single crystals. These billets are heated in air in a predeter-

Jan 1, 1964

By AIME AIME

THE American copper mining industry is threatened with disintegration and destruction. This threat is not one which may only materialize in the distant future. The destruction has already commenced. At present, many domestic mines have already closed down. .Others are operating on a greatly curtailed basis. Those operating are doing so only at tremendous loss-because the selling price of copper is below the cost of production and rapidly diminishing financial resources and credit clearly forecast the early suspension of operations in most of the industry. Unemployment in the mining districts is increasing by leaps and bounds. While this condition is due in some measure to the present unsatisfactory state of business in general, the copper industry, unlike other lines of business, sees no possibility of recovery without definite aid. The fundamental, underlying cause of present conditions in the American copper mining industry is the unprecedented rise in foreign production, and the basic change which has taken place in the world copper industry in the last three years. The American industry had begun to feel this change early in 1929 long before the general collapse of business in the fall of that year. While the distress in the industry is undoubtedly aggravated by the present economic depression, it nevertheless would have arrived and. have been present at this time, regardless of general business conditions.

Jan 1, 1932

By Robert Warner

The growing importance of screening makes an accurate measure of the quality of a sizing operation desirable. Screen efficiency is considered equal to the percentage of true undersize in the feed obtained as undersize from the screen. This method is unreliable, as it gives the same credit for removing minus 200-mesh material as for removing material just able to pass the aperature of the screen. A more accurate measure of screen efficiency is to consider only the work done on the "difficult" grains, that is, those grains of which the intermediate diameters closely approach the screen aperture.. The application of this method is given, together with the derivation of formulas and an example of their use. Is AN accurate measurement of the efficiency of a screen under a given set of operating conditions valuable? If so, what is the efficiency; of, a screen and how can it be measured? Sizing, especially of the finer sizes of material, has increased in importance in the development of flow sheets as a result of the perfecting of the rapid vibrating screens. More consideration should be given screens in the preparation of ball-mill feed, where they permit the admission of a dryer feed than, the classifier. Where possible, the introduction of a screen ahead of the primary ball-mill, and the diverting of ore below, say, 4 mm. to a secondary mill, might result in a greater overall economy because of the thicker feed and the better, adjustment of crushing media and mill operation to the reduction demanded. With the present trend back toward a combination of gravity methods and flotation, rather than flotation alone, the accurate, economical sizing possible with the new screens makes fine jigging a method to be considered. W. 0. Borcherdt1 and John Bland2 discuss the screening problem and also the value of close sizing in the concentration of some of the rare-metal ores. If a screen is to be used, it should be selected in competition with others; other things being equal, that screen which makes the cleanest oversize should be preferred. The quality of the screening and the tons

Jan 1, 1924

By W. C. Knopf, G. Samsel

For several years International Minerals & Chemical Corp. has used a radiation method to assay potassium content of products from potash and feldspar beneficiation. The procedure is rapid, accurate, and inexpensive and is easily handled, if necessary, by nontechnical personnel. Data are presented to show the accuracies that may be expected if the technique is used for control of pilot plants or large- scale plants. Natural potassium is composed of three isotopes -K39, K40 and K41. Five other isotopes, artificially produced, have been detected. In natural potassium only the K40 isotope, with a half life of 1.4 x 109 years, is radioactive. Its modes of decay are beta and gamma rays, positrons, and x-rays. Only the more abundant beta rays, however, are important in radiation measurements using geiger tubes.

Jan 10, 1958

By R. W. Raymond

In connection with the discussion of the paper of Mr. James Gayley, presented at the Baltimore meeting, in February, 1892, on " The Preservation of the Hearth and Bosh-walls of the Blast-furnace,"* I offered a translation of a letter received from our distinguished honorary member, Professor P. Ritter von Tunner, concerning the use of carbon-bricks at the Donawitz furnace, then (February, 1892) in the third month of its campaign. The purpose of this brief paper is to put upon record later results of practice with carbon-bricks, both in this country and abroad.

Jan 1, 1897

By A. G. Weber, R. L. Ledbetter, A. L. Hicks

A procedure which makes use of both analog and digital computers has been developed for predicting the pressure-production behavior. of water-drive reservoirs. The electric analyzer is used for matching the past pressure and production history of the reservoir and inferring the physical characteristies of the aquifer. When the history has been matched, a .set of base curves called influence functionce" are derived and the future behavior of the reservoir is calculated from these curves. INTRODUCTION Electric analog methods are particularly well-suited for complex water-drive problems. Like all other methods of analyzing water-drive reservoirs, however, analog methods are subject to certain limitations. One of the more obvious and serious of these results from inaccurate or insufficient knowledge about physical characteristics of the reservoir and aquifer. However, it is not insurmountable because the unknown characteristics can usually be inferred from the reservoir's previous behavior. Simons and Spain have shown that even with scant reservoir data and limited production history, electric analyzer studies can provide useful and reliable results. Aside from this limitation on analyzer predictions, the main disadvantage has been lack of a technique for keeping predictions abreast of latest production forecasts. Pressure behavior of a reservoir depends on the rate at which fluid is withdrawn; it is therefore necessary to specify the future withdrawal schedule before the future pressure behavior can be calculated. Conventionally, the electric analyzer predicts pressure behavior for a specific production schedule. If this schedule is abandoned in favor of some new one, as is frequently the case, either the study must be rerun or results adjusted in some manner. The usual procedure is to predict pressures for several different forecasts covering a wide range of production rates. Pressures for specific rates other than those studied can then be approximated by interpolating between the analyzer predicted curves. However, reliability of this type of prediction is doubtful. This paper describes a technique for predicting future behavior of water-drive reservoirs that retains all advantages of electric analyzer analysis and eliminates the main disadvantage. That is, the analyzer is used conventionally to infer unknown reservoir parameters from the pressure history, but not to predict the future behavior directly. Instead, a derived set of base curves, called influence l'unctions, can be used to calculate future behavior for any production schedule.