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By G. F. Loughlin

More than 20 years have passed since the publication of Lindgren and Ransome's report on the Cripple Creek District,1 which was made when the district was much more active and prosperous than in recent years. They concluded that the output of the district, which had reached its maximum of about $18,200,000 in 1900, would gradually decline, and their conclusion has been confirmed by records of subsequent production. Between 1905 and 1915 annual declines were partly compensated by encouraging increases, especially in 1908, 1914, and 1915; but a rapid continuous decline followed, due largely to the war and its after-effect's, until in 1922 the value of output was only slightly more than $4,000,000. It rose to nearly $5,000,000 in 1924, but declined again in 1925 and in 1926, when it was about $4,400,000, and represented ores mainly from deep levels in the Cresson and Portland mines. The profitable operations of these two mines were the principal factors leading to a study of ore at deep levels in the district by the U.S. Geological Survey in cooperation with the Colorado Metal Mining Fund. The principal reasons for Lindgren and Ransome's conclusion were three: (I) the greater cost and difficulty of deep exploration; (2) the decrease in the number of veins with increasing depth, and (3) the probability that the telluride ore, believed to have formed at comparatively low temperature, would not persist indefinitely in depth. Operations since they made these statements have verified the first two, but call for some modification of the third. Rich telluride ore is being mined at a profit in the Portland mine 3000 ft. below the present surface, 07. 5000 ft. below the original surface of the Cripple Creek volcano, as interpreted by Lindgren and Ransome. The question arises, therefore, as to the number and extent of such deep deposits, and the answer, so far as it can now be given, must be based mainly on structural data, supplemented by data on the processes of ore deposition. Presentation of these data based on a study of deep mines in the southeast quarter of the district, the only

Jan 1, 1927

By C. K. Leith

WE face the postwar problem of the use of minerals as sanctions to control the armament and the re-armament of the Axis powers at the source, minerals being the raw material of armaments. That is the subject of today's discussion. It is one thing to talk about controlling minerals in the interest of rearmament, and it is another thing to put any such ideas into effect. A provision for min- eral sanctions-not by that name but under broader terms-was contained in Article 16 of the League of Nations, and an attempt was made to apply min- eral sanctions when Italy cut loose in Africa. That was a failure because the plan was badly thought out. They did not have the right minerals included in the list. Also, they did not have the machinery set up at all. Somebody said to the League of Nations: Let's apply the sanction, and it was assumed that that was all that was necessary. It turned out to be a rather sad perfor- mance. However, that certainly cannot be taken as an example of what will happen if a properly thought-out pro- gram is adopted.

Jan 1, 1944

By W. H. Adams

I doubt if many of our engineers know of the existence of coalfields extending over hundreds of miles of territory bordering on and lying contiguous to the Rio Grande River in Mexico. Essential as these facts are to those contemplating the starting of industrial works along our frontier, 1 have not been able to learn that any surveys or examinations have been made of these deposits, arid I trust the preliminary and unofficial investigations lately made by myself may be found of interest, especially to those of our members whose experience has been with poor fuel, or in districts remote from railway facilities. While it is true that Northern Mexico is generally bare of charcoal-making timber, yet no greater mistake can be made than to condemn the light, quick-growing woods found in profusion, and which cannot be excelled in flame or heat-pruducing qualities for boilers, reverberatory furnaces, or hearths. No country could be surer of a full supply of wood if wise legislation in regard to irrigation and preservation of young timber were adopted and enforced, but the beneficiation of the low-grade ores of Mexico demands a more dense fuel for furnace work, and, fortunately for metallurgists, who will hereafter make this frontier a base of operations, there have been disclosed, near the surface, seemingly inexhaustible beds of semi-anthracite and bituminous coals. No extensive openings have as yet been made, and my own workings at the Cedral mines are all that can yet be said to prove the quantity and quality of the coal, other openings furnishing only corroborative evidence. Our location (one hundred and ten miles west of the Rio Grande River) is on the western line of the depository basin, as it has existed since the period of activity along the volcanic line. The region farther inland I have not examined, but the elevations, as a rule, are much greater, though from the nature of the formation, they are not necessarily barren ground. Beginning at the base of the Santa Rosa Mountains (location of the Cedral mines), we find very interesting breaks in the foot-hills, disclosing the stratified rocks from the volcanic centres to the valleys.

Jan 1, 1882

By M. G. Corson

UNTIL recently, the characteristics of cast copper have seldom been studied and such study as has been made has been inadequate. The prevailing idea seems to be that since pure copper is infrequently used in the cast state, there is no reason for trying to establish precise data regard-ing the properties of the metal in that condition. On the other hand, wrought copper either in the shape of sheets or wire rarely fails in service, except as a result of the action of reducing gases at the annealing tempera-tures, so there is little incentive to study the properties of the cast shapes -cakes, bars, ingots and billets-for-the sake of tracing the causes of failures of the wrought metal to the cast stock. However, about a decade ago, wirebars of American origin often cracked badly while being hot-rolled in mills in Germany. This led to four investigations: by E. Seidl and E. Schiebold,1 by P. Siebe,2 by O. Bauer and G. Sachs,3 and by G. Welter.4 These authors came to the conclusion that failures in hot-rolling were due essentially to the presence .of a wide zone of columnar crystals between the thin layer of fine crystals near the surfaces of the bars and the large but more nearly equiaxed grains of the central core. This macrostructural defect was explained in turn by the probable upward deviation in the temperature of the metal while it was being poured into the molds of the casting machine. More recently, cast shapes of copper were investigated by N. P. Allen5 and by C. Blazey.6 Allen examined vertically cast wirebars and hori-zontally cast wedge cakes of electrolytic tough-pitch copper, but only for the distribution of densities; i.e., porosity. Blazey was interested mainly in the mechanism of the variations in electrical conductivity clue to cold-work and anneal, but gave introductively an account of the composi-tion and average densities of the tough-pitch horizontally cast wirebars used. As far as the present writer can tell, no investigation was under-taken for the sake of presenting a picture of the distribution of mechanical characteristics in the wirebars of copper, tough-pitch or otherwise.

Jan 1, 1938

Jan 9, 1950

By R. L. Bleifuss

Most pellets swell only slightly during reduction, but some swell so enormusly that their increase in size is termed catastrophic. Since catastrophic swelling produces irregularities in blast furnace operation, an understanding of the phenomenon is of practical as well as theoretical interest. Observations have shown that catastrophic swelling is characterized by the growth of a network of fine iron filaments. Evidence is presented to show that the growth of these filaments is promoted by the presence of calcium in the magnetite lattice of the original ore. During reduction, the limited mutual solubility of CaO and FeO produces an unstable condition that inhibits the uniform nucleation of metallic iron. Other elements in the magnetite lattice whose oxides are continuously soluble in FeO in the critical temperature range have no effect. Magmatic segregation or pyrometasomatic replacements are the most likely deposits to contain calciferous magnetite. Over the past few years there has been an increasing concern throughout the iron and steel industry over the tendency of pellets to swell during reduction. Although the tendency for swelling is only one of several attributes that determine the behavior of pellets in the blast furnace, swelling-reduction tests are now part of the normal evaluation procedure of many pellet consumers. During a swelling-reduction test, pellets display either the moderate increase in size known as normal swelling, or the enormous expansion known as catastrophic swelling. This paper is concerned with the origin and control of catastrophic swelling and how it is enhanced or inhibited by the presence of minor elements. Swelling Behavior The swelling behavior of pellets during reduction is indicated in Fig. 1. The lower curve represents normal swelling and the upper curve catastrophic swelling.' During the initial stages of reduction, that is, up to about 20-25% reduction, the two curves are considered to be equivalent. Beyond this point normal pellets undergo a gradual decrease in size with increased reduction. By contrast, pellets which exhibit catastrophic swelling show a second dramatic expansion between 25 and 70% reduction. The initial normal swelling develops as the hematite of the pellet is successively reduced to magnetite, and then to wustite. Work by Edstrom' and others has shown that the reduction of hematite to magnetite is accompanied by a 25% volume increase, whereas the magnetite to wustite stage shows a volume decrease. The volume increase overlaps the wustite field because magnetite is formed simultaneously with the wustite during topochemical reduction of the pellet. The catastrophic expansion is clearly related to the wustite, to

Jan 1, 1971

By L. L. Karafiath, S. G. Vick, E. A. Nowatzki

Computer analyses of the trafficability of copper mine tailings by four different commercially available BWEs were performed. A mathematical model incorporating the tailings' Coulomb strength parameters and the vehicles' geometry and operational characteristics was used to study the vehicle terrain interaction. The computer output provides the maximum tractive force (net drawbar pull) that each BWE can develop for given tailings conditions without bnngzng about a state of plastic failure in the tailings. Estimates of sinkage are also provided. The theoretical results for the BWEs and tailings studied compare favorably with the operating experience of similar BWEs used for remining gold tailings in South Africa. This lends some confidence to the validity of the mathematical model. The results of such analyses may be wed to evaluate, on a relative basis, which of a number of different machines would perform better than others under given conditions of a tailings deposit.

Jan 1, 1982

By L. J. Buteau, R. E. Reed-Hill, W. A. Slippy

In a zirconium {1121} twins tend to have coherelzt boundaries and thus do not usually taper to a point when they intersect a grain boundary. Under the proper conditions, a (1121) twin may deform a boundary in such a manner as to clearly rcveal the twinning shear. Measurements of these grain-bounrlary rotatzons yield a value of 0.63 for the (1151) twinning shear. The magnitude of the observed shear and its shear sense are in excellent agreement with the assumption that the second undis-torted plme (K2) for this form of twinning is the basal plane (0002). The present value of the tzvinninz shear, which is approximately three limes larger than Rapperport&apos;s value? is in excellent agreement with reported results of Sokuskii and Prolsenko.5 RECENTLY westlake&apos; reported a study of the twinning modes of zirconium based on ~ap~er~ort&apos;s2 values for the twinning elements. He observed that two of the modes, (1012) and {1122), can be explained by relatively simple dislocation models. A workable model for (1121) twinning, however, proved to be very complex and questionable. Because Rapperport&apos;s second undistorted plane, (K2), for (1121) twinning has large indices, {ll2l6), it is possible that the difficulty in defining a model for (1121) twinning lies in an incorrect value for K2. A measurement of this twinning element has therefore been made, using a method based on observations of the shear displacement of grain boundaries at positions where they are intersected by (1121) twins. EXPERIMENTAL PROCEDURES The zirconium specimens were deformed in tension on an Instron machine either at the temperature of liquid nitrogen (77ºK), or prestrained at liquid nitrogen temperature and then further deformed at room temperature. Straining at 77°K was employed in order to nucleate (1 121) twins in large numbers, since simple ropm-temperature tensile deformation favors (1012) twinning. Specimens were machined from 1/2-in.-thick plate. The material was arc-melted sponge zirconium annealed to an ASTM grain size 4 and containing, in parts per million, 380 Fe, 880 0, <40 Hf, 32 N, and < 5 H. The specimen gage length and diameter were 1.25 and 0.130 in., respectively. To insure a gage section initially free of twins, the last 60 thousandths of the specimen diameter was removed by acid machining.

Jan 1, 1963

By S. B. Casey

[ ] IN 1880, an electric arc was struck over metal for the first time to experiment with controllable melting. The glare of this arc has reflected on the stacks of the steel industry and continued to light the path of steelmakers in their never ending quest -for faster, more economical, and better ways of producing steel. William Siemens is credited with first employing the electric arc to melt metal in a closed hearth and produce basic metallurgical reactions. By the turn of the century, an Italian, named Stassano, was experimenting with ore reduction by the electric arc. In 1899, Dr. Paul Heroult, in France, used the direct arc principle for producing ferro-chromium. His experiments quickly led him to develop a dosed-top arc furnace for the production of steel, and his first commercial shipment was recorded in December, 1900. American steelmakers, quick to sense the possibilities of this method of melting, invited Heroult to our shores, where, in 1905, he was responsible for installing the first arc furnace on the North American continent. This furnace, at Sault Ste. Marie, was built for ore reduction. But Charles Holcomb, founder of Holcomb Steel. Co. of Syracuse, N. Y. contacted Heroult in 1905 and contracted for the first American direct-arc electric furnace for steelmaking. On April 5, 1906, the first heat was tapped from this 3-ton unit. The furnace was basic lined and powered by a single-phase, 500 kw generator, -producing high amperage at low voltage. It is interesting to note that, although the first few heats were made with cold charges, subsequent heats were duplexed. R. H. Bully, first superintendent of Holcomb Steel, persuaded the directors to purchase the unit to effect a more economical and efficient means of making tool steel by duplexing prime melting in a combustion fired furnace, and transfer of hot metal to the arc furnace for temperature adjusting, refining, and adding carbon and alloying elements. Today, duplexing is foreseen by some as the steelmaking process of the future. The promise shown by America&apos;s first arc furnace for ingot production quickly led to the purchase of a similar unit by The Firth Sterling Steel Co., in 1909, and to the purchase of the first arc furnace for production of steel castings, by the Treadwell Engineering Co., in 1911. From its humble start in 1906, production of arc furnace steel has never ceased to increase its yearly percentage of total steel production in the U. S., although certain other methods have declined or almost disappeared. By its ability to be used intermittently, the arc furnace gained favor and enhanced its reputation during depression days. When the attack on Pearl Harbor plunged us headlong into the long days of World War II, the arc furnace stood ready, flexible enough to be overburdened hearth wise 30 pct and power wise 25 pct, pouring its endless flood of alloy for the guns, tanks, ships, and planes which ultimately brought victory. During the post war boom, the now, proven virtues of low initial cost, faster installation, better yield, improved availability, and lower operating cost, enabled industry-particularly the small, new, independent producers-to locate strategically and profitably to meet the demand of an America that had been starved for new homes, appliances, cars, and highways. In the Korean police action, the arc furnace again proved itself by providing the latest alloys metallurgists could develop to meet the demands that the jet age and the innovations of guided missiles required. In today&apos;s peacetime prosperity, the arc furnace is continuing to provide the economic flexibility required to meet an ever increasing demand for better steel in the face of mounting costs, scrap shortages, and pressure toward decentralized location of industry.

Jan 1, 1961

By J. H. Henderson, H. J. Ledbetter, N. B. Gove, J. D. Griffith

INTRODUCTION The results of a series of laboratory flood tests using liquid Iso-butane to displace refined oils from test cores are pre- ented and interpreted on an empirical bask. The study Revealed the similarity of the miscible liquid displacement to that of the immiscible-fluid displacement mechanism. The efficiency of the iso-butane flood decreased markedly as the oil Viscosity increased. but the effect of injection rate on the effectiveness of the primary production stage was negligible over the range investigated. The presence of free-gas saturation prior. to iso-butane breakthrough increased the volume of iso- Butane required to recover a given percentage of the oil present. Injection of liquid i.e.-butane prior to water follicle sculpted in a marked improvement in oil recovery by the water flood. INTRODUCTION The production of petroleum is often enhanced by the injec-1i1)n of extraneous fluids into the reservoir. It has been suggeited that the injection or cycling of a wet gas or a liquefied petroleum gas would he instrumental in increasing the effic.ienr!; of oil recover! to a greater degree than the commonly injected fluids. dry pas and water. Although instances of injection of light liquid hydrocarbons are not unknown, a systrmatic recording of the result is unavailable and superfi- cially, the practice gives the impression of being economicaIIy unsound. For specific types of displacement, analytic: solutions have been advanced which aid in understanding the physical mechanisms involved. However, there is no generalized theoretical concept which permits adequate prediction of displacement efficiency from a knowledge of readily measured reservoir rock and fluid properties. The Buckley-Leverett approach to oil displacement by an immiscible phase is an admirable analysiy of that type of mechanism. Dykstra and Parsons have introduced a useful concept in their evaluation of the role of the mobility ratio and its merit in rationalizing displacement phenomena. Everett, Gooch and Calhoun3 in their report on the effect of viscosity ratio and miscibility have pointed out the lack of a comprehensive theoretical approach and the desirability of investigating the mechanism of miscible-miscible displacement. In lieu of a well-developed theory concerning miscible-111isci1)le displacement and in view of the scarcity of engineering information on actual LPG injection trials, the limited program of laboratory experimentation described below was undertaken. OBJECTIVES The original broad objectives of the program, to study the oil recovery process using LPG as the displacing phase, defined the direction and scope of the laboratory tests. The specific objective. of the experimentation were to evaluate

Jan 1, 1953

By P. H. Griffin

WHEN a subject, such as the manufacture and service of chilled car wheels, as has been fruitlessly discussed for ten or fifteen years, it is difficult to revive interest and action by the mere repetition of statements and arguments that have been made before. And when a situation involves serious responsibilities for conditions that have grown up under circumstances beyond the control of any particular individuals or authority, it is even more difficult to deal with. But there is one phase of every subject that need not involve these particular points if presented in a, proper manner; and that is, " the future state." I will try to present the subject of this communication from the latter standpoint and with the hope that all of those interested will feel disposed to give the matter attention from the basis that it is a, vitally important one to all that travel on railroads, whether as employees or officials, or as dependent on those in charge of the operation, or in the matter of materials and equipment used. The conditions of chilled wheel service have been changed so radically in the past ten or fifteen years by the use of freight cars of 40 and 50 tons capacity, that it is fair to say in the interest of all concerned in the use and in the manufacture of such wheels, that the increased strains and loads have been quite sufficient to account for much of the service results that have transpired. That proper provision was not made for increased possibilities of strength and wear, in fact that previous factors of the kind were allowed to deteriorate, is no proof that such wheels cannot be made equal to heavy service conditions as shown in the data given herein.

Jan 10, 1913

By R. H. McLean

Velocity, kinetic energy and shear in crossflow beneath three-cone jet bits may influence cleaning of the bottom of the borehole and the teeth of the bit. Laboratory investigation shows that each of these parameters is a function of the diameter of the borehole and the product of the volume rate of flow and velocity through the nozzles (QVn). Increasing QV, or decreasing the diameter of the borehole increases each parameter. These functions provide means of predicting the magnitude of each parameter and of scaling the cleaning forces. INTRODUCTION In drilling operations using conventional jet-type rock bits, the impinging jels create an important flow mechanism. Called crossflow, this flow mechanism originates in the impact area of the jets, spreads across the bottom of the hole and supplies the principal source of energy to clean the teeth of the bit and most of the bottom.&apos; Besides providing the means of cleaning cuttings from the bit and the hole bottom, crossflow may also have other, less direct, effects on the rate of penetration. The shear stress generated on the bottom by crossflow will inIluence the thickness and permeability of any filter cake of mud solids or crushed material which forms on the bottom.&apos; These factors may affect the rate of penetration. A previous pulblication introduced some fundamental concepts of crossflow.&apos; Crossllow was shown to occur in a thin layer adjacent to the bottom, and to cover the bottom completely. The maximum velocity in the crossflow above any position on the bottom was found to be directly proporlional to the square root of the product of the volume rate of flow and velocity through the nozzles—the jct QV,,—and inversely proportional to the diameter of the borehole. This information indicated that the effectiveness of crossllow in scavenging the bottom can be improved by maximizing the jet QV. The investigation reported herein amplifies the definition of crossflow. Complete velocity profile data above a representative position on the bottom are analyzed. These data better illustrate control of the capacity of crossflow to scavenge the bottom, and also relate shear stress on the bottom to known, controllable parameters. The conclusion reached in the previous publication that maximization of the jet QV. produces the maximunl cleaning beneath current jet bits is unchanged by these new data; rather, it is strcngthened. Data presented here show that the kinetic energy flux above a representative position on the bottom is maximized by maximizing the jet QV. The shear stress on the bottom will also be shown to be maximized in the same manner. Since the functions relating the jet QV. to velocity, shear stress and kinetic energy also involve the diameter of the borehole, means of equating, or scaling, these quantities in different sizes of boreholes will be illustrated. EXPERIMENTAL EQUIPMENT AND TECHNIQUE JET BIT MODEL Data were recorded from the same laboratory model as used in the aforementioned investigation of the flow around a jet bit.&apos; The model consisted of a 43/4-in. three-cone, jet-type rock bit in a smooth, flat-bottomed borehole constructed of lucite. The bit had a shape and nozzle placement closely resembling larger three-cone jet bits commonly used in field operations. Fig. 1 illustrates the impact area on the bottom of a jet from this bit. Details of the orientation of the jets may be found in the previous publication. TECHNIOU&apos;E OF MEASUREMENT Measurements of the crossflow were made by inserting a very small Pitot tube through the bottom of the simulatetl boreholc. Extreme thinness of the layer of crossflow necessitated accurate measurements of the height of the Pitot tube above the bottom to achieve close definition of the velocity profile. A cathetometer, which could be read to the nearest 0.005 cm, was used to make this measurement.

Jan 1, 1966

By Frank Foote, Eric R. Jette

In a recent article,1 the authors reported the results of an X-ray investigation on the range of solid solutions that occurs in the iron-oxygen system in the vicinity of the compound FeO, which frequently is called "wüstite." The object of that investigation was primarily to study the unusual type of solid solution phenomena involved in this range. Briefly summarized the results were: 1. The NaCl type of lattice found by earlier workers was confirmed. 2. The lattice dimensions decrease rapidly with decrease in iron content. 3. No alloy that was a homogeneous single phase was ever found at compositions beyond 76.80 per cent Fe, while the theoretical iron content of FeO is 77.73 per cent Fe. 4. Measurements of the densities and lattice constants led to the conclusion that the form of substitution was complex, an FeO group being replaced by oxygen. Such a substitution, of course, is equivalent to removing an iron atom (or ion). The ideal unit cell of FeO can be considered as containing four groups of FeO and, thus, when this type of substitution takes place, there remain in the unit cell three FeO groups and an oxygen, or a total of seven atoms with a gross formula of Fe3O4 instead of the original Fe4O4. 5. This was the only interpretation that would fit the experimental results and at the same time be consistent with (a) the previously determined fact that the FeO lattice is ionic (i, e., consists of Fe++ and O? ions) and (b) the chemical fact that as the oxygen content of the substance increases, ferrous iron becomes oxidized to ferric iron. The experimental results of this investigation are included in Fig. 1. The purpose of the present investigation was to determine the limits of this homogeneity range by means of the X-ray structure analysis. This method has been applied frequently to the study of solid solutions by Westgren and his coworkers as well as by other investigators. The principle is simple: if the change in lattice constant with composition is

Jan 1, 1933

FOR this Famous Mining Enterprise issue MINING ENGINEERING selected the company that started the zinc in dustry in the United States. The New Jersey Zinc Co. has been a supplier of zinc products to the nation&apos;s industries for more than 104 years. Its Horse Head trade mark is famous throughout the world.

Jan 12, 1953

By Ellis Clark

Within the last ten years the progressive party of China, headed by Li Hung Chang, the Viceroy of Chi-Li, has been making great efforts to develop the mining resources of that country, and particularly those that are within reasonable distances of the sea-board. Attention was first paid to the coal-deposits, especially those at KaiPing, which have been placed on a profitable basis with an output of 1500 tons per day, under the energetic management of Mr. Claude Kinder, M.I.C.E., and the successful financiering of Tong King Sing. These coal-mines were described in a report by Kwong Yung Kwang, edited as a paper for the Institute (Duns., xvi., 95.) The attention of the leaders of the progressive party has for the past five years been turned also toward the development of the precious and related metals—gold, silver, copper and lead. De-

Jan 1, 1891

By Daniel C. Jackling

WHAT is written here features some of the things that I would say if I were to de- liver a Presidential address during the Annual Meeting to be held this month in New York. I am aware that custom favors written rather than vocal delivery of such a discourse; and, as this accords exactly with my own preference, I assure readers that they will never be called upon to hear these remarks spoken- anyhow, not by me. My year as President is drawing to a close. As I look back I like to classify and analyze the impressions that have been left with me. It has been a delightful and fascinating experience to me personally; I have appreciated the courtesies and aids, and have been deeply gratified at the honors accorded me. Perhaps the source of greatest satisfaction is the opportunity I have had to sense more about the provinces of this Institute and about the useful functions of the profession that it represents. For 38 years I have been a member. I served two terms as Director-one in 1914-&apos;16 and again in 1927-&apos;29. I have been honored by selection as a Saunders Medalist. I thought I was reasonably familiar with the functions, the ideals, and the activities of the Institute. But the things that I have discerned during the past year have dispelled that conceit. I still think that, a year ago, I was as well informed as most members; but since then I have had the rare privilege of executive service and insight. That has given me a perspective that I feel can be obtained in no other way-as I think the illustrious engineers who have preceded me in office will agree. I wish that I had the power to translate to every member somewhat of the feelings of pride in our organization that a year as President cannot help but instill.

Jan 1, 1939

By V. R. Degner

The trend in both the metallic and nonmetallic mining industry is toward processing increasingly higher tonnages of lower grade ores, thereby resulting in a growing interest in progressively larger volume individual machines in the flotation circuit. Because of the relatively high cost of large flotation machine development and evaluation, it is important to establish a rational basis by which the existing smaller flotation machine experience can be extrapolated to establish the configuration of the next larger family of flotation machines with a minimum of development modification in the field. This Paper reviews the R&D approach used in translating smaller flotation machine experience to the configuration of a 28.3 m3 (1000 cu ft) induced air machine. Internal cell hydrodynamic principles, which governed this extrapolation, and cell (liquid) surface and froth management considerations will be reviewed, and prototype machine mill tests will be summarized.

Jan 1, 1981

By R. A. Swalin

IN this paper, the results of an investigation concerning the diffusion of three elements, magnesium, silicon, and molybdenum, in nickel are presented. The work represents a continuation of a diffusion program relating to solute diffusion in nickel. The program has the dual aim of obtaining useful diffusion data and of yielding insight into the factors governing solute diffusion in close-packed metals. The first paper of this series has been published earlier? In both investigations, in agreement with recent results from other laboratories, the activation energies for solute diffusion were found to be close but not identical to that of self-diffusion in the pure solvent in question. In order to obtain valid diffusion data, certain experimental pitfalls recognized only in recent years had to be avoided. Chief among these were the necessity for minimizing short-circuiting diffusion paths such as grain boundaries and the necessity for using low solute concentration gradients. In this series of investigations the following precautions were taken in an attempt to minimize such errors. 1) Samples with large grain sizes, 0.5 to 10 mm, were prepared. 2) The diffusion coefficients were measured at relatively high temperatures, since imperfections such as dislocations play a less important role at such temperatures than at lower temperatures. 3) Alloys containing less than 1 atomic pct were chosen for study. Experimental Work Materials—A diffusion couple technique was employed in the experimental investigation. Briefly, this technique consisted of the following. A diffusion couple was fabricated by placing a flat face of a cylindrically shaped alloy disk against a similar face of a pure nickel disk, and a bond was formed at an intermediate temperature under pressure. The diffusion couple thus fabricated was subjected to a diffusion anneal at higher temperatures for a measured period of time and then sectioned perpendicular to the direction of diffusion. After analyzing the sections for solute concentration the diffusion coefficient was determined from a probability, plot of concentration vs distance from the diffusion interface. Vacuum melted Mond nickel was used in the experimental program. The chemical analysis of this nickel is listed in Table I. Alloys used were prepared

Jan 1, 1958

TO THE BOARD OF DIRECTORS OF AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen:-I have the honor to present the following, report for the calendar year 1920. The activities which seem to call for special comment are: THE NEW FORM OF MAGAZINE MINING AND METALLURGY appeared every month during the calendar year and has been developed until it contains some ten departments. It has brought forth more commendatory letters than have been received at headquarters on any other subject throughout the year. Less than a dozen letters unfavorable to the change have been received, and the indications are that the magazine has met a want deeply felt, especially by members distant from headquarters. The technical papers printed by the Institute are published in abstract in the magazine and opportunity is given to members who desire them to receive full copies of any or all papers published. The Bound Volumes, as usual, contain all the papers in full and discussions thereof. FINANCES The greatly increased cost of paper and printing has put a tremendous burden on the Institute&apos;s finances, since the dues of $12 per year are only 20 per cent. greater than the members paid when the Institute was founded forty-nine years ago. This has resulted in a temporary deficit, similar to that encountered by many of our sister engineering societies. The fact that our Institute has lower dues and gives more in the way of publications to its members than any other of the national engineering societies has rendered the situation more difficult for us. MEETINGS The Annual Meeting in New York, the Field Meeting in the Lake Superior District, the meeting of the Petroleum and Gas members at St. Louis, and of the Institute of Metals Division in Columbus, Ohio, have all been described in full in the magazine.

Jan 1, 1925

By J. R. Dawson, J. A. Glunt

VESTA No. 4 and 5 mines supply most of the high volatile coal required for Jones & Laughlin&apos;s byproduct coke plants. Until 1944 all coal produced in these mines was loaded by hand. Pressure to mechanize at Vesta was brought on by the manpower shortage in World War 11, and in 1943 a decision was made to change to mechanical loading. It was the opinion of those concerned that by use of selective mining the coal would be clean enough to be processed by the existing preparation plants. At that time coal cleaning at Jones & Laughlin consisted of hand picking the larger sizes at the mine tipples and wet washing at plants located at the Pittsburgh and Aliquippa Works. A typical section of the Pittsburgh seam as it occurs at Vesta is shown in Fig. 1. The 14 to 16 in. of drawslate immediately over the coal is too soft to be used for roof and must be taken down, leaving the rooster coal just above for roof. In selective mining an attempt is made to mine the coal under the drawslate first and then load out the drawslate separately as refuse. In full seam mining slate and coal are shot down at the same time and loaded out. Mechanical loading at Vesta created new problems. It was found that selective mining, even when carefully applied, increased the refuse in the raw coal to such an extent that the washers at the mills were unable to handle it. Large tonnages of refuse were being transported, a reject disposal problem was created, and good metallurgical coal was being loaded out and lost. In addition, the selective method handicapped operation of the loading machines. Fig. 2 shows how the ash content of the raw coal increased as mechanization proceeded at No. 5 mine. New Preparation Plant: After an exhaustive study of this situation by J & L management, is was decided that a preparation plant should be constructed at the mines, capable of handling full seam mined coal and large enough to process full production of both No. 4 and No. 5 mines. It was decided that from the standpoint of inside operation and haulage the new plant should be located as near as possible to the old No. 5 tipple on the Monongahela River near Vestaburg. Full seam mining at Vesta could be expected to produce a tremendous volume of refuse along with the coal, since 14 to 16 in. of slate would be mined with an average 78 in. of coal. Disposal of this refuse required serious consideration in selecting a plant site. The only area near Vestaburg large enough for disposal of the plant refuse was across the Monongahela River at LaBelle. Ample space was available here, and construction at this location would not interfere with operation at the No. 5 tipple. It had been noted over the years that the sulfur content of the coal produced at Vesta was gradually increasing, and there was every indication that this increase could be expected to continue as the mines developed further from the river. It was decided to construct a three-part separation plant with complete blending facilities to produce both metallurgical and steam coal. In this system an attempt is made to reduce the sulfur in the metallurgical coal in a secondary cleaning process. Construction of the new preparation plant got under way early in 1947 and continued until the spring of 1950. The plant was designed to handle 2400 tph of raw coal containing 30 to 35 pct refuse. Cost of outside buildings and equipment was about $14 million. Total cost of the plant, together with improvements and changes made at this time, was approximately $21 million.

Jan 1, 1957