Search Documents

By C. Kremer Bain

DURING the past several years of diamond drilling in Washington County, Mo., the St. Joseph Lead Co. has discovered a concentration of commercial lead-zinc ore at four different points within an area of 36 square miles. The largest and to date the most promising group of these orebodies is located in the Indian Creek area. It was considered to be of sufficient value to warrant development.

Jan 9, 1953

By J. D. Hunt, R. J. McDonald

It is proposed that extensive fluid motion occurs between the dendrites of a Partially solid casting and it is suggested the A segregates in steel castings are a direct result of this motion. The fluid flow arises because of density differences between liquid ahead of the dendrites and the interdendritic liquid. Experiments are described on a model system investigating this fluid motion. The importance of interdendritic fluid flow is discussed with reference to longitudinal segregation. SERIOUS macro segregation is often found in large killed steel ingots. Among the most common segregates are those known as A and V, Fig. 1. The A segregates are arranged over the surface of cones, the wide parts being at the base of the ingot. The A segregates are pencil like in shape and extend from the columnar into the equiaxed region. The V segregates are distributed over inverted cones but have a less well defined shape. They occur at the center of the ingot. Because of the commercial importance of macro inhomogenities these segregates have attracted wide-scale attention. The segregates contain alloying elements and impurities which depress the freezing temperature and are thus the last liquid to freeze. A number of explanations have been proposed to explain their presence. It has been suggested1'' that the segregates are the result of the equiaxed zone growing towards the columnar region together with the interaction of convection within the bulk liquid. It has also been proposed that the segregates are the result of nucleation and rapid growth ahead of the dendritic front.3 Neither of these explanations is completely satisfactory because A segregates are pencil shaped and are not found as continuous cones. In this paper an alternative mechanism is proposed, and experiments are described on a model system to determine whether the mechanism occurs in practice. It is thought that A and V segregates are not peculiar to steels but should occur in many other large castings. Fluid motion within the bulk liquid region of a casting has been extensively discussed. Little attention has been paid to fluid motion within the partially solid regions. The work415 that has been done has been mainly concerned with the fluid motion which results from the volume contraction on freezing. The volume contraction is used to explain various types of macro segregation. The present authors suggest that in many cases the fluid flow resulting from volume contraction will be small compared with that due to other causes. When the columnar region is growing, the liquid still remaining between the dendrites has a much lower temperature near the ingot walls than at the dendrite tips. The composition of the liquid in contact with solid will vary with temperature. The density of the liquid will thus vary both because of changes in temperature and composition. The layers of different density liquid will give rise to a slow but steady liquid flow through the interdendritic regions. If there is no density change with composition, the temperature gradient within the dendritic region should give rise to a downward flow between the dendrites, shown schematically in Fig. 2. When the liquid density changes appreciably with alloy concentration this motion could either be en-

Jan 1, 1970

By James B. Cathcart

The potash mine of the International Minerals and Chemical Corp. is about 18 miles east of Carlsbad, New Mexico, in sec 1 and 12, T 22 S, R 29 E, N.M.P.M. Potash is produced from two zones in the Salado formation of late Permian age. The lower zone, consisting of a mixture of sylvite (KCl) and halite (NaCl), lies at a depth of about 900 ft, and the upper zone, in which the principal potassium mineral is langbeinite (K2S04.2MgS0d), lies at a depth of about 800 ft. Because of the plastic nature of the material, fractures in the Salado formation are extremely rare and have been noted only on the 800 ft level of the International mine. The open fracture described below is almost unique. Only one other open fracture has been noted, and it was on a working face in the same general area as the one described, but was destroyed before the writer had a chance to examine it. According to J. E. Tong, foreman on the 800 level, this fracture was similar to, but smaller than, the one herein described.

Jan 1, 1949

By Virgil R. D. Kirkham

RECONNAISSANCE of a part of southeastern Idaho and small strip of western Wyoming lying between longitudes 111° and 111° and 45' W., and latitudes 43° and 43° and 30' N., comprising an area of approximately 1330 sq. mi., was undertaken during the summer of 1923 for the collection of data regarding the oil possibilities of the region. TOPOGRAPHY, SETTLEMENT, AND ACCESSIBILITY The entire area lies within the upper Snake River drainage basin. Snake River flows through the northeastern and eastern part of the area in a northwesterly direction. The entire drainage system has been controlled by the structure of the sedimentary beds in the area, which exhibit numerous alternations of hard and soft strata with consequent unequal erosion. The headwaters of the most important streams, as well as many others, flow in a northwesterly or southeasterly direction along

Jan 1, 1925

By Frank Schrader

J. DANA SPERR, Jerome, Ariz. (communication to the Secretary*).¬Very little accurate information has been published about this district. Most of the geological data appearing in the technical press are based on "careful observations" made from an auto stage and a casual glance through the U. S. Geological Survey Bulletins, No. 340 of 1908 or No. 397 of 1909, both by F. C. Schrader. Mr. Schrader's report is still the best publication on the district. A really careful study of this report will uncover only a very few statements which have since proven questionable. This is a remarkable record when it is considered that only a short time was spent by Mr. Schrader in the field and that there was very little development work done at that time. The mining world and especially Mohave County, Ariz., will feel a sense of gratitude to Mr. Schrader for revising his early report. on this

Jan 3, 1917

By S. H. Ash

More than 100 minerals are mined and processed in the U. S. Management and labor have negotiated wage-scale agreements that have balanced wages and affected cost of labor in such a manner that comparisons can be made of transportation costs. Transportation of materials underground has become of vital importance. This report describes underground haulage methods and equipment, presents cost analyses, and discusses future plans for underground transportation in metal mines. It does not cover hoisting in shafts or slopes by cage, skip, or cars. Advancements have been made by the metal mining industry in lowering transportation costs in several mines, making it possible to mine orebodies or portions of orebodies not considered economically recoverable a few years ago. Numerous reports have been written on transportation at metal mines; this report covers recent haulage at some representative mines throughout the U.S. The term metal mine is used to include all noncoal mines from which up-to-date information was obtainable.

Sep 1, 1956

By C. S. Allen

With increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration ? Deceleratien-or-retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. Types or Braking Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the srrew-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application—which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse Direction.-This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck,, them (which reverses the connections to the motors) and then to apply power. Theoretically, this should be done only in an emergency, but locomotives in mine service are frequently thus treated., Dynamic braking is retardation of the locomotive by the motors acting as generators, which take no power from the line.

Jan 1, 1942

By C. S. Allen

With increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration ? Deceleratien-or-retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. Types or Braking Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the srrew-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application—which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse Direction.-This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck,, them (which reverses the connections to the motors) and then to apply power. Theoretically, this should be done only in an emergency, but locomotives in mine service are frequently thus treated., Dynamic braking is retardation of the locomotive by the motors acting as generators, which take no power from the line.

Jan 1, 1942

By W. G. Jewitt

YELLOWKNIFE, the most northerly Canadian gold mining district, is once more in the throes of a boom. Touched off by spectacular and well-publicized diamond-drilling results on the property of Giant Yellowknife Gold Mines, Ltd., mining companies and the general public are competing for mining claims and for the shares of companies owning mining claims in the area, with little regard for values. Such a stock-market boom has various unfortunate consequences but undoubtedly one beneficial result is that considerable amounts of money are made available for serious development. The Yellowknife mining area lies on the north shore of Great Slave Lake, in the Northwest Territories, at a latitude of approximately 62°30' north. The topography is a low-relief phase of that usual in the Canadian Laurentian shield. Roughly, one third of the surface is lake-covered, one third muskeg or overburden, and one third is bare

Jan 1, 1944

By R. L. Sebastian

ALUMINUM'S war history is the record of a successful race to expand facilities fast enough to meet the multiple increases in military requirements, principally for aircraft. From the beginning of the war program in 1940 through 1942, requirements estimates were repeatedly lifted to new high levels, and plans for increasing capacity had to be constantly revised. In 1943, basic metal supply caught up with and exceeded requirements, and by 1944, the surplus of primary production was large enough to force reduction in output and plant closings. In the past two years, ingot capacity has been ample, though periodic critical shortages have been experienced for a few fabricated shapes as a result of sudden shifts in demand. And now with all controls lifted we are faced with surplus capacity, surplus stocks, and surplus scrap. In 1938 the Aluminum Co. of America was the only U. S. producer of primary

Jan 1, 1946

By E. P. Mathewson

DURING the past 35 years it has been my privilege to deal with hundreds of recent graduates from engineering schools all over the world. In consequence, I, feel that I have learned something about the training of, engineering students. In the first place, I believe that too great specializa-tion is a mistake. A student should receive general training in engineering for at least three out of the four years of the course, and any specializing that may be required should come in the fourth year. Too great emphasis can not be laid upon the fact that the four years' training does not make an engineer; on the contrary, the graduate is only fitted to enter the pro-fession. He becomes an engineer in the true sense of the word only after years of practice; the college train-ing merely shows him where to look for information and develops his intellectual powers. Some of our engineering schools have lengthened the term of study to five years and talk of increasing it still further. This, in my opinion, is a mistake. A young man who spends more than four years in college is apt to become too academic and theoretical. It is better to stiffen the matriculation examinations than to prolong the years of study in college. No matter how good the faculty may be and how carefully selected the course of study, the graduate can never become an engineer unless he has some natural qualifications for the vocation. There are one or two subjects in which most recent graduates seem to be weak; these are accounting, the command of English, and training in the writing of reports. A short course in general accounting should always be included in the curriculum. To this should be added instruction in the preparation of estimates and cost statements. In making reports it should be borne in mind that these reports are to be submitted to busy men,-and not to technical men. The busy man wants the gist of the report summarized on the front page of the report. He wants to know that if he expends a certain sum of money in a certain way, he will get certain results and make so much profit. This should be put clearly before him in short statements, free from technical terms. The details of the report can follow .at greater length; it should be remembered that the employer is not going to read these details, but will confine his attention to the summary.

Jan 1, 1923

By J. E. Johnson

OF the many items of information necessary to the successful management of the blast-furnace, few are more important than knowledge of the location and movement of the stock-line: whether the furnace is full and has. been kept so; whether the stock is settling regularly or slipping; and, if slipping, how often it has slipped, at what times, and how far at each time. To obtain these data, a man is sometimes stationed at the top of a. pair of mechanically-filled furnaces, simply to watch and gauge them by hand in the old-fashioned way. - A more recent practice is the suspension of test-rods from ropes leading over pulleys to the ground-level, where the ropes are wound on small drums with graduated peripheries and provided with crank-handles, whereby the skip-man or some other person can quickly and conveniently gauge the position of the stock-line in the furnace. I believe the credit for this great improvement belongs to Messrs. McClure & Phillips of Sharon, Pa., who were, as far as I know, the first to apply it, and who have a patent for it. The valuable indications gained by application of the Uehling pyrometer to the down-comer are Dot to be ignored; but the information thus furnished is somewhat indi¬rect, and there is no scale for the translation of "top-tempera¬tures " into " feet down." Moreover, this apparatus as a whole is delicate, and the cost of its installation and maintenance is high. If the record furnished by the Uehling pyrometer is not in the most desirable form, the test-rods, on the other hand, give no record at all, except through the memory, or notes of a man who, to say the least, is not gauging continuously, and who may omit to report an improperly low stock-line, if it be due to a fault of his own.

Mar 1, 1905

By J. L. Whitlock

An attached growth aerobic biological treatment process has been developed at Homestake Mining Co.'s Lead operation which not only oxidizes free and complexed cyanides, including the stable iron complexed cyanides, but also thiocyanate, and the oxidation byproduct ammonia. Through the employment of a mutant strain of bacteria which has been gradually and specifically acclimated to the waste, these potential pollutants are mineralized to relatively harmless sulfates, carbonates, and nitrates. The resultant effluent, through toxicological testing, has been shown compatible with the receiving stream, which serves as a cold water marginal trout fishery.

Jan 1, 1985

By Richard A. Boulay

The effects of capital, operating and debt cost variations on project performance criteria are examined using a theoretical model and an actual case history. On an after-tax basis, financial measurements are found to be most sensitive to operating cost changes, somewhat sensitive to reasonable changes in capital costs and relatively insensitive to interest rate fluctuations.

Jan 1, 1985

By L. F. Reinartz

FROM the earliest times when our prehistoric ancestors laboriously fashioned crude tools and weapons from meteoric iron until our day when we manufacture steel in 150-ton open-hearth furnaces, the production of iron and steel has played a dramatic and important role in the development of civilization. Progress in the science of refining iron ore into iron and steel was painfully slow for many centuries. The keen scimitars of Damascus, the broadswords of the English knights, the coats of mail of French knights, and the Iron Pillar of Delhi are well¬known examples of medieval metallurgical technique. Expense and the scarcity of raw materials originally limited the distribution of iron and steel products. It was not until the nineteenth century that a determined effort was made to adapt the use of steel to peaceful pursuits. The spectacular and rapid strides made in the manufacture of steel during the last hundred years were hastened by the invention during the decade 1860 to 1870 of two great steelmaking processes-the Bessemer and the open-hearth process.

Jan 1, 1936

By Charles S. Barrett

This paper is a progress report covering metallographic applications of the electron microscope that have been made during the past year at Carnegie Institute of Technology. An account is presented of the techniques that have been most satisfactory, the difficulties encountered, the resolution obtained, and the peculiarities that have been noted in the microstruc-tures. About 1200 exposures have been made during the year on the instrument, which is an RCA type B2 transmission microscope,' and a number of these have been selected to illustrate the results obtained. prints are also included showing the common types of falsities—to borrow a term from the biological field, the "artifacts." ln brief, the paper is a record of our attempt to determine the value of the electron microscope in the study of the structure of metals and alloys. In addition to comments on techniques and the quality of photomicrographs obtainable with them, the paper discusses the nature of the etch attack on a few metals, and the possible relation between the fine structure revealed by etching and the mosaic block structure of the grains, since numerous papers and reviews are available on the subject of imperfection in crystals, the comments here may be very brief; in fact, are restricted almost entirely to points having to do with recent theories relating the strength of metals to imperfections and to spacings of slip lines. Specimen Preparation and Photographs Mechanical polishing by hand was used throughout this work. Precautions that must be taken in microscopy at high magnification, which have been well explained by Vilella in his book on Metallographic Technique for Steel, are likewise important with the electron microscope. This applies particularly to the need for these polishing and etching (each successive polish becoming less severe and each etch lighter), since the fina1 etch should in general be no heavier than is used for oil-immersion optical microscopy and in many instances should be much lighter (compare Figs. 6a and 7a, 6d and 7b). An extremely light etch, of course, is incapable of cutting through a flowed layer of appreciable thickness. Unquestionably it would be very advantageous in each instance to compare the structures obtained by electrolytic polishing with those obtained by mechanical polishing, but difficulties with the electrolytic method have prevented this in the following collection of prints. The choice of etchant is important, of course; for example, picral proved superior to nital for tempered martensite. With the exception of Figs. Ib and 16, the replicas used were of silica, deposited upon polystyrene and floated from the polystyrene in ethyl bromide according to the method of Heidenreich and Peck.2 The samples were mounted in Bakelite, polished and etched, then the polished Bakelite

Jan 1, 1944

By Charles S. Barrett

This paper is a progress report covering metallographic applications of the electron microscope that have been made during the past year at Carnegie Institute of Technology. An account is presented of the techniques that have been most satisfactory, the difficulties encountered, the resolution obtained, and the peculiarities that have been noted in the microstruc-tures. About 1200 exposures have been made during the year on the instrument, which is an RCA type B2 transmission microscope,' and a number of these have been selected to illustrate the results obtained. prints are also included showing the common types of falsities—to borrow a term from the biological field, the "artifacts." ln brief, the paper is a record of our attempt to determine the value of the electron microscope in the study of the structure of metals and alloys. In addition to comments on techniques and the quality of photomicrographs obtainable with them, the paper discusses the nature of the etch attack on a few metals, and the possible relation between the fine structure revealed by etching and the mosaic block structure of the grains, since numerous papers and reviews are available on the subject of imperfection in crystals, the comments here may be very brief; in fact, are restricted almost entirely to points having to do with recent theories relating the strength of metals to imperfections and to spacings of slip lines. Specimen Preparation and Photographs Mechanical polishing by hand was used throughout this work. Precautions that must be taken in microscopy at high magnification, which have been well explained by Vilella in his book on Metallographic Technique for Steel, are likewise important with the electron microscope. This applies particularly to the need for these polishing and etching (each successive polish becoming less severe and each etch lighter), since the fina1 etch should in general be no heavier than is used for oil-immersion optical microscopy and in many instances should be much lighter (compare Figs. 6a and 7a, 6d and 7b). An extremely light etch, of course, is incapable of cutting through a flowed layer of appreciable thickness. Unquestionably it would be very advantageous in each instance to compare the structures obtained by electrolytic polishing with those obtained by mechanical polishing, but difficulties with the electrolytic method have prevented this in the following collection of prints. The choice of etchant is important, of course; for example, picral proved superior to nital for tempered martensite. With the exception of Figs. Ib and 16, the replicas used were of silica, deposited upon polystyrene and floated from the polystyrene in ethyl bromide according to the method of Heidenreich and Peck.2 The samples were mounted in Bakelite, polished and etched, then the polished Bakelite

Jan 1, 1944

By E. S. Davenport

IT is indeed an honor and a responsibility to have been selected to present the thirty-fourth in this series of Henry Marion Howe lectures, established to perpetuate the memory of a great teacher and one of America's outstanding scientists. Previous Howe lecturers have established high standards for this annual AIME event. It has been my good fortune to have enjoyed close association with five of these former lecturers; namely, Bain, Grossmann, Johnston, Sosman, and Vilella, all of whom have been prominently identified with the research activities of the organization with which I am connected. Some years ago I had an opportunity to examine a letter written by Professor Howe in 1904. This document was particularly interesting to me since I never had the privilege of personal acquaintance with Professor Howe and do not recall even having seen him during his long and active career. In view of the fact that the letter dealt, to some extent, with matters related to the subject of today's lecture, I would like to quote briefly from it. The letter is datelined, "Bad Kissingen, June 11, 1904." The salutation reads, "Dear Bradley," which suggests that it was probably addressed to Bradley Stoughton, who, I believe, was working with Howe at Columbia University at that time. The letter reads, in part, as follows: "Austenite and Martensite. I have not examined what Osmond says in his new book. His former remarks about austenite I found very confusing, indeed unintelligible. I think we can reconcile matters well enough for the present by assuming that martensite is a transition step between austenite at one end and ferrite and cementite at the other. Above critical range for steel of 0 to 1.80 carbon, austenite is normal state; below Ar1, ferrite and cementite are normal." The letter then continues with a discussion of Osmond's ideas on metallographic nomenclature, particularly his use of the terms martensite, troostite, and sorbite, including the following pointed comment: "For common purposes it seems to me unwise to drag them in, and much simpler to confine ourselves to the end stages Austenite Ferrite plus Cementite Osmond does not really know his own mind— or does not clarify his ideas to others—as to nomenclature." Thus we see that, as far back as 1904, the transformation of austenite, and the products of that

Jan 1, 1958

By A. D. Taylor

In recent years there has been an increasing effort to attract students into engineering. Obviously, the effort is necessary because young people find the image of the engineer unattractive. Some of the things they find unattractive are real, some are not, and part of the problem is too little knowledge of the field. First, I would like to comment on some of the ideas which appear to be justified. Engineering is a difficult course of study. True, and nothing can or should be done to change this. The education is continually being improved, but it is unlikely to be made easier.

Jan 1, 1970

By Homer W. Riley, C S. Jenkins

SMALL power-driven, toothed, cast-iron rolls were used first to break anthracite in 1844. Prior to that time, men with hammers, who stood on perforated cast-iron- plates, .broke the large lumps into commercial sizes. In order to convert run-of-mine into the various sizes required by the anthracite industry, about 20 million tons must be broken, annually, [ ] into smaller sizes. This phase of anthracite preparation is of major importance, because the degradation accompanying reduction in coal sizes should be kept at a minimum. The exclusive use of toothed rolls for that purpose indicates that comminution by rolls is the best solution of the problem. Many improvements have been made in tool design, but the most important was a reduction of the peripheral speed of the rolls from 1000 to 300 ft. per minute. The higher speed was based upon and approximated the velocity of a falling piece of coal when it entered the rolls. Exhaustive roll tests at the slower speed showed that the same size reduction could be affected with less degradation. The adoption, there- fore, of slow-speed, compound geared rolls, especially for breaking the

Jan 1, 1943