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By C. Ernest Birchenall

TWO recent papers1,2 cite measurements of surface contour changes on copper which, when attributed to surface self-diffusion, can be interpreted to yield activation energies for surface self-diffusion that approach1 or exceed2 those reported for volume self-diffusion in the same metal.3 It is acknowledged2 that AS must be assigned much too large a value to be physically reasonable in order to make the theoretical Do's agree with the experimental values, if the jump distance is of the order of the interatomic distance. However, long jumps would probably lead to marked anisotropy on planes that consist of ridges and valleys (like (110) in fcc) whereas only mild

Jan 1, 1963

By B. H. Bergstrom, C. L. Stevenson

In any process wherein materials must be pelletized, a crucial period exists during the interval between the manufacture of the green pellets and their subsequent heat treatment. The pellets must possess sufficient strength and plasticity to withstand conveying and sizing. Also, they must be neither excessively brittle nor excessively plastic when placed in a bed on a traveling grate for heat treatment. An acceptable pellet, in the event sufficient forces are applied to cause its fracture, will merely split into two or three large fragments which would not drastically alter the permeability of the pellet bed. However, when brittle pellets are broken, they shatter so that the resultant fine particles either decrease the perimeability of the bed or become entrained in the gas stream and thereby cause dust problems. On the other hand, excessively plastic pellets may not break at all but may merely flatten. This would seriously hamper bed permeability. In the past, pellet evaluation has usually been left to the creative and artistic talents of the balling operators. A multitude of techniques have evolved, of which the most common is the simple compression test. For this test a hand-operated device loads single pellets to fracture, but reliability is strictly operator- dependent. Probably the next most common test is the drop test, which is conducted according to several different procedures. This is an important quantitative test for estimating the amount of handling a pellet will withstand. There are many other tests, such as pinching a pellet between the thumb and index finger, but none are capable of producing reproducible results.

Jan 4, 1962

[ ] (14) SCREENS: Description of Allis-Chalmers' complete line of vibrating screens for the mining industry is contained in a new 8-page bulletin. Primary scalping, secondary scalping, and conventional screens for wet or dry sizing and screens for heavy media separation are included. Also given is a typical fiowsheet showing how horizontally operated Low-Head screens are used in the sink and float process. (15) MILLS: Forty-six years of experience and 4000 installations throughout the world lie behind the seven basic types of mills illustrated in a recent bulletin from the Hardinge Co. Fields of application and materials handled in various installations are listed. (16) BLOWERS & COMPRESSORS: A brochure describing the manufacturing facilities and the axial and centrifugal blowers and compressors made by the Sawyer Bailey Corp. is now available. (17) LINATEX: The first catalog of the Linatex Corp. of America has been issued, outlining the advantages claimed for this special form of natural rubber, when used in corrosion, abrasion, and vibration resisting applications. (18) WIRE ROPE: Twenty-four pages packed with concentrated wire rope data is the way E. H. Edwards Co. describes a booklet which they are now making available. It was condensed from the Edwards general catalog to provide users with a concise guide to every important phase of wire rope production, maintenance, and use.

Jan 1, 1952

By P. W. Bridgman

THE thesis of this article is that the age of Newton is now coming to a close, and that recent scientific discoveries have in store an even greater revolution in our entire outlook than the revolution effected by the discovery of universal gravitation by Newton. The revolution that now confronts us, arises from the recent discovery of new facts, the only interpretation of which is that our conviction that nature is understandable and subject to law arose from the narrowness of our horizons, and that if we sufficiently extend our range we shall find that nature is intrinsically and in its elements neither understandable nor subject to law. The new experimental facts are in the realm of quantum phenomena. Comparatively little has been written for popular consumption about this new realm which has opened in the last fifteen years. The man in the street has been much more interested in relativity, which to him has seemed extremely interesting and revolutionary. Occasionally, however, there has filtered down to him the news that nearly all the theoretical physicists are occupied with a new order of phenomena which they find very much more exciting and revolutionary than any in the realm of relativity. For after all is said and done, the practical effects of relativity, measured in ,dollars and' cents or in centimeters and grams, are exceedingly small, and require specially de- signed experiments executed by men of the highest skill to show their existence at all. The phenomena with which quantum theory deals, on the other hand, are of the greatest practical importance and involve the simplest aspects of everyday life. For example, before the advent of the quantum theory no one could explain why a tea kettle of water boiling on the stove should not give out enough light in virtue of its temperature to be visible in the dark; the accepted theories of optics demanded that it should be visible, but every burned child knew that it was not.

Jan 1, 1929

By R. S. Shrode, R. F. Bunting

Transportation is one of several important increments in the total market cost of most commodities. On a national average it has been reported that transportation accounts for about 25% of the total cost of a product at the market place. And industrial minerals are no exception. In fact, the proportionate cost frequently exceeds the 25% average. Further, it may actually determine the economic value of a deposit. Transportation possibly may be thought of as a specialized subject, of concern only to a traffic manager and of only nominal interest to the mining engineer, the geologist or other technically oriented member of a mineral producers' staff. However, in the industrial minerals field, interest is not commonly confined to exploration, development, production or marketing, but is in contrast an overlapping one. In a very real sense this broad area of interest in the total economics of the business is the specialty of the industrial minerals man. And transportation is a vital part of the total picture.

Jan 1, 1970

By L. L. Peterson, W. C. Morgan

This paper discusses some of the problems involved in predicting the productivity of a shovel and truck fleet in a new set of operating conditions. More specifically, it concentrates on the problems of predicting the travel times on the haul and return portions of the truck cycle under new profile conditions and the prediction of the interaction effect between the shovel and truck at the loading point. The ability to calculate the travel times for a new road profile is not new. Additional corrections of these calculated times for expected actual operation can be made. In considering the interaction between the loader and the hauler, there are two approaches that can be taken. Probably the most accurate method of predicting the shovel-truck interaction is a simulation of the step-by-step operation considering the variation in cycle times of the shovel and trucks. This is usually called a stochastic simulation and requires input describing how these cycle times vary. However, by understanding the causes of this shovel-truck interaction it is possible to make sufficiently accurate predictions with much simpler methods. Haulage Cycle Established from Existing Operations For the purpose of this discussion let us assume that the problem involves trying to predict the productivity of a single shovel-truck fleet at some future time in an existing operation. Let us also assume for simplification that the new operation to be simulated has the same loading and pit conditions and the same dumping conditions as did the existing operation. Therefore, the only difference would be the difference in the hauling profile for the new operation. The problem then becomes one of predicting the change in the travel times on the haul and return portions of the cycle, and in determining the change in interaction between and the shovel and trucks with the new truck cycle times.

Jan 12, 1968

Jan 1, 1934

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Jan 1, 1938

Jan 1, 1944

THE distinction btween price reduction as a re-sult of lowering of production cost and price re-duction through unrestricted competition cannot be made too clear, because they are often interwoven in actual experience. Take the whole population of a town whose principal industry is shoe manufacturing as a concrete example. If the manufacturer is able to cut his price per pair in half because he has found out how to make a pair at half the cost, he will com-monly let a number of his men go, because reduction in production cost usually results from substituting cheap mechanical energy for expensive human energy. These people will normally find other employment. The workmen who remain employed usually earn more in dollars than they did before, and in spending it give employment where there was less before. Mining companies that initiate considerable enter-prises in foreign lands where the economic level is low, and where most of the people are busily but in-efficiently engaged in raising enough food to support themselves and their families, often find themselves confronted with an acute labor problem. If any con-siderable number of workers leave the land to work in and about the mines, those left on the land cannot raise enough food to keep them all unless they are taught better methods of agriculture and provided with equipment that will enable them to produce more with less expenditure of effort. Add to this the fact that managers commonly find that the "natives," as our British cousins designate them, usually need more food and a better balanced diet than they have been accustomed to in order to show anything above the lowest order of efficiency in industrial work,. and it is clear that to make a new industry possible in what may be termed an economic province involves increas-ing the productivity, not only of those who are em-ployed in it, but of the whole social group. It has already been pointed out that the employ-ment of large numbers of men in automobile manu-facture is only possible because the others have in-creased their productivity enough to turn out every-thing else that is needed without the help of the auto-mobile workers.

Jan 7, 1928

By G. K. Dumbauld, B. E. Morgan

A satisfactory well-cementing composition must retain its fluidity long enough to be pumped into Place; then it must develop within a reasonable length of time sufficient strength and impermeability to anchor the casing in position and to form an effective seal between the casing and the formations. These properties may be evaluated by pumpability, strength (compressive or tensile), and permeability tests. Laboratory test procedures for the determination of pumpability time and strength development have been outlined previously and are readily available,1 but a satisfactory and convenient laboratory procedure for the measurement of the permeability of set cement has not been developed heretofore. some permeability data have been obtained previously by passing air through dried cement specimens.2 such a procedure is unsatisfactory because the drying of set cement alters it physical and chemical properties and subjects it to conditions dissimilar to well conditions. A more realistic method would be one wherein the cement remains water-saturated durin

Jan 1, 1952

Jan 1, 1930

By Scott Turner

IT has been considered that the training of an engineer is too often vocational training; that it is a pity all engineers cannot have had a period of liberal training before taking up' pure engineering. Offhand, the so-called liberal courses should bring more ready adaptability to deal with the unexpected, to face with assurance situations which have had no parallel in one's experience, and to move without hesitation under conditions which were heretofore unknown to one, than the specialized course in mining engineering. We hear increasing talk as to the necessity of making the engineer articulate and bringing him into public life. The social implications, and responsibilities of engineering are pointed out, as of equal importance with the prodigious marvels of engineering ingenuity. You often read of this as the logical result of the in¬creasing consciousness of the engineer as to his rela¬tive position in our modern industrial civilization. , Some wag has noted that man is the noblest work of God, but that man is the only one who has said so. Perhaps engineers are the only claimants as to the necessity of their going in for public life and service; at any rate, some liberal educators' still maintain that a well-rounded general education is the better training.

Jan 1, 1930

PRESIDENT OF THE COUNCIL. JOHN HAYS HAMMOND NEW YORK, N. Y. (Term expires February, 1909 ) VICE-PRESIDENTS OF THE COUNCIL SAMUEL B. CHRISTY BERKELEY, CAL. JOHN A. CHURCH NEW YORK, N.Y. PERSIFOR FRAZER PHILADELPHIA, PA. (Term expires February, 1909 ) J. PARKE CHANNING NEW YORK, N. Y. FREDERICK W. DENTON PAINESDALE, MICH. JOHN B. FARISH New York, N. Y. (Term expires February, 1910)

Jan 1, 1910

By Stephen Krickovic

As it is commonly understood in the bituminous coal mining industry, pillaring means removal, as completely as is practical, of all pillars formed in the development of headings and rooms on first mining. The degree to which this can be accomplished, termed percent of recovery, is of course dependent generally upon the physical conditions of the bottom and the overburden, the system of min-

Jan 2, 1955

By William Kelly

I AM-glad to have the opportunity at this time to say that I consider it a very great honor to be elected President of the American Institute of Mining and Metallurgical Engineers. It fulfills the proudest hopes of my ambition. There is, ,however, one drawback to my personal gratification-a feeling of unworthiness to have my name placed on the list with former Presidents of the Institute, with the brilliant Raymond who guided our society for so many years, with the versatile and lovable James Douglas, my first employer and my friend, a most generous benefactor of our Institute, with the skilful Holley, who gave to the manufacture of steel in this country, its first great impulse, to mention only three of the accomplished men who have preceded me. I assume that the honor of my being elected President of the Institute is not merely a personal one but that it should be considered a tribute to the wonderful progress in the art of mining, both underground and in open pits, and in the beneficiation of native copper and iron ores, which have been shown in the Lake Superior District and also a recognition of our members there and elsewhere who are living at the mines and directing the operations, upon the success of which the whole mineral industry depends.

Jan 1, 1924

By Denis Yeung, B. H. G. Brady

A hybrid finite element-boundary element code with eight noded isoparametric finite elements and three noded boundary elements is described for plane strain and linear isotropic elasticity. In the direct formulation of the Boundary Flement Method, quadratic variation of geometry and displacements, and linear variation of tractions with respect to the element intrinsic coordinates are used. The boundary element region is treated as a "super-element" in the finite element sense.

Jan 1, 1982

By Carter S. Cole

Mr. Chairman, Fellow Members and Guests, our chairman this morning got over into the geneological field, so perhaps I may be pardoned if I revert to some of my ancestral training and give you a text. I always like to talk about some special little text that may illustrate what we want to say. So the text that I will take for this afternoon is a very simple one, "Win the War." That is the guide for all of our actions, or should be. We should question everything we do to see what it does to contribute to winning the war. If we fail to do that, nothing else is going to count. On the wall of the office of one of the branch chiefs in the Copper Division in Washington there is a little slogan which I think we should take very deeply to heart, "The difficult we do right away. The impossible takes a little longer." I think that is a very good guide for us to follow in the work that lies ahead of us in the metallurgical field and in the handling of these secondary metals and the things that result therefrom. My subject is "Conservation and Specifications." Some people would wonder just where that fits in, and how you might define "conservation." One very good definition would be "the utmost use of our resources." If you will pardon my going back to some of my earlier experience for a little simile, those of you who know me know that for ten years after the last war I was in the railroad business. If we are with the engineman in a cab, and we have a green signal ahead of us, that is a clear signal and tells us to proceed at full authorized speed. Now suppose we come to a yellow signal that is caution, slow down to one-half authorized speed and be prepared to stop. Now if you do slow down, the chances are that that obstruction that was ahead of you will move out of the road, and you may get another yellow or caution signal at the next block, and be able to keep going at a slow speed. As of the date of Pearl Harbor our tin supply took on a very yellow tinge, and it threw the caution sign right in our faces. If we had not heeded that sign, and cut down our consumption of tin, we would not have any today; but because we have done so we are in a much better position today than we were a year ago, that is comparing our visible supply with our present rate of consumption as contrasted with the visible supply a year ago and our then rate of consumption.

Jan 1, 1943

Oklahoma Geological Survey, Faculty Exchange, Norman, Okla The Oklahoma Geological Survey was closed for lack of funds July 1, 1931. However, a list of publications "will be sent and requests for publications will be filled in so far as possible Address the above.

Jan 1, 1933

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