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By G. Sachs, G. Espey

Simple methods can be used for the determination of the residual stresses in thin walled tubing if the stresses consist of high tensile stresses at the one surface and high compressive stresses at the other surface. Such a stress distribution is approximated in sunk tubing and in deep-drawn shells. It is possible to cut sections from such articles in such a manner that a major part of the residual stress is relieved by a bending of the Part that is separated from the adjacent metal. The circumferential stress is evaluated from the change in diameter D, occurring on splitting a length of tubing (Fig. Ib) or from deflection resulting from the cutting out of a circumferential tongue (Fig. Ia) .6 The bending moment M released by such a flexure is. M - EI (I-I) = EI R1-R0 I - u2(R0-R1) I -V2 R0XR1 where E = modulus of elasticity, v = Poisson's ratio, I = moment of inertia of the section, R0 =. mean radius before splitting, R1 = mean radius after splitting. The release of this bending moment corresponds to the release of stresses, which, in a thin section, vary linearly from one surface to the other, and have the following value in a particular fiber a certain distance (x) from the surface: S = c d I - V2 x c x d 2 2 RI - R0____E (d ) R1 - R0 X R0 X R1 ~ i - u2 (2 x) Ro X R1 where C is the section modulus and d is the thickness of the section, the ratio M:C being d: 2 for a rectallgular section.* The maximum stress values at the surfaces are. Smax = +E X d X R1-R0 I — u2- 2 R0 X R1 For most purposes the simpler equations: EXd AD1 = ± I - u2 x dm2 and will be satisfactory, where D,, is the aver. age of the mean diameters of the tubing

Jan 1, 1942

By C. O. Burgess, A. B. Kinzel

Although vanadium is an important constituent of almost every brand of high-speed steel manufactured today, little is known as to its role in this series of alloys. The now standard 18 per cent tungsten and 4 per cent chromium constituents were the result of developments and improvements before 1903. In that year, vanadium was added to the steel by Dr. J. A. Mathews. This proved to be an outstanding contribution, so that the standard high-speed steel of today is generally referred to as the 18-4-1 type—18 per cent W, 4 per cent Cr and 1 per cent V. Various modifications have been attempted since then, but with the exception of the introduction of cobalt, no striking improvements have occurred. Vanadium has been increased to 2 per cent in many of the common brands, and at least one brand contains 5 per cent V in addition to the usual tungsten and chromium. The carbon has been gradually increased so that it is not uncommon to find 0.80 per cent in the standard grade, although the carbon in the 5 per cent vanadium steel mentioned above is approximately 1 per cent, and even 1.2 per cent has been made experimentally. The role of vanadium has never been well understood, and although vanadium has been increased to 2.5 and even 5 per cent in certain high speed steels, it has not been generally established that the higher vanadium contents result in superior cutting properties. However, in all of the investigations, of which the writers are aware, the interrelation of the vanadium and carbon contents was not considered as a prime factor. The carbon content was held at 1.2 per cent or less—generally at the usual 0.65 to 0.75 per cent. Theoretical Aspects Although the role of vanadium is not understood, there are theoretical considerations which indicate definite reasons for the improved cutting effciency due to vanadium. Refinement of the secondary grain is one distinct possibility. The well-known action of vanadium in limiting grain size might well be expected to operate in high-speed steels, and even though its action were not evident in the parent austenite grain.

Jan 1, 1932

By John Blizard, Ralph A. Sherman

The experimental investigation described in this paper was conducted to determine the relative combustibilities of different samples of blastfurnace coke when burned in a current of air in a small furnace. It was undertaken in connection with the work done by Perrottl and Kinney2 on the process of combustion in the blast-furnace hearth.3 Reference is often made to the "combustibility" of coke by blastfurnace men, but exactly what is meant by the term "combustibility" is somewhat vague. Brassert,4 in a paper before a meeting of blastfurnace men in 1914, refers to combustibility as follows: The value of the coke in relation to the heat reactions in the furnace is determined not only by the carbon content but even more so by its combustibility. This, in turn, is governed by its size, the physical and chemical composition of the carbonaceous substance forming the cell walls, and the interior and surface structure of the coke pieces. These properties are, in turn, influenced by the chemical and physical properties of the coals used for coking, the density of the cake of coal in the oven, the coking time, temperature and heat regulation of the ovens, and last, but not least, by the method of quenching, screening and handling the finished coke. What principally concerns the blast furnace is the rate of progression of the combustion, which depends not so much on the chemical analysis as on the physical qualities of the coke. It is this rate of progression that we term combustibility, which is the speed at which the carbon molecules in the coke combine with oxygen under given conditions. In general, what the blast furnace requires is a coke which will burn rapidly and with intensity at the tuyeres, yet which has a sufficiently strong structure and hard surface to resist abrasion and solution by CO2 in the upper part of the stack.

Jan 1, 1923

By J. Bruce Wagner, Roger L. Levin

Integrated forms of two solutions of Fick's second law for the movement of a plane interface through a sample of wustite, and for diffusion into a semi-infinite slab of wustite, are shown to yield nearly identical values of the chemical diffusion coeffcients of cation vacancies in wustite, over the temperature range 900° to 1100°C. The chemical diffusion coefficients, the values of D obtained for the propagation of a concentration gradient through samples of undoped and doped wustite, are obtained from the equations It is becoming increasingly important in metallurgical practices to understand the role of the chemical diffusion coefficient, i.e., the diffusion coefficient of a species across a concentration gradient. During the first stages of sintering, one of the mechanisms by which the bonds between neighboring particles develop is by volume or bulk diffusion. This diffusion coefficient as deter- where ?m is the weight change at any time t, ?W is the total weight change at t =8, A is the area of the specimen, and AC is the total change in the cation concentration after the establishment of equilibrium, as determined by reduction experiments in different carbon monoxide -carbon dioxide mixtures within the limits of existence of the single-phase field. mined from the standard equations for volume diffusion during sintering is actually a chemical diffusion coefficient, and it has been observed to be many times larger than the self-diffusion coefficient as determined on the same materials by experiments using radioactive tracer techniques. Kuczyn-ski1 has noted that, if the controlling mechanism of sintering of A12O3 in an oxidizing atmosphere is the diffusion of oxygen, then this diffusion coefficient as measured from sintering rates is about 2.2 x 104 higher than the self-diffusion measurements obtained by tracer techniques. He has also reported the diffusion coefficient obtained from the rate of sintering of Fe2O3 powder to be about 10 6 times faster than the self-diffusion coefficient of

Jan 1, 1965

By C. D. Keen

IN the latter part of the summer of 1913 the Conservation Commission of the State of Louisiana, under presidency of M. L. Alexander, decided to stop the waste of natural gas going on at the "burning gas-well," located about 3/4 mile southeast of Oil City, La. On several occasions, both in newspapers and in reports, comment had been made on the condition of this well, its harmful effect on the Caddo gas field, and the considerable loss, estimated at several thousand dollars each month, caused by the escape of the valuable fuel. But nothing had been done to bring the well under control and prevent further waste of gas until the State Conservation Commission took the matter in hand. The gas fields of Louisiana are among the greatest in the country. So far most of the gas has been found in the Caddo field proper, although considerable development has been done in and around the city of Shreveport and near the town of Mansfield in DeSoto parish. To extend the life of the gas fields and to prevent the quick exhaustion of the supply of the natural fuel are matters of vital importance for this section of the country. Four gas companies have entered the Caddo field and supply the surrounding towns and cities with gas. The Arkansas Natural Gas Co. has pipe lines to Little Rock, Ark., and supplies gas to the following cities and towns in that State: Texarkana, Hope, Garland, Emmet, Prescott, Boughton, Beirne, Gurdon, Arkadelphia, Gum Springs, Malvern, Donaldson, Gifford, Perla,- Beaton, Beauxite, Mabelvale, Bryant, Sheridan, Pine Bluff, Little Rock, Argenta, Pulaski Heights, and Hot Springs. The Southwestern Gas & Electric Co. transports gas to Mooringsport, Blanchard, Caddo, Rodessa, Oil City, Vivian, Bloomburg, Hosston, Ida, Dixie, Belcher, and Shreveport. The Marshall Gas Co. supplies gas to the town of Marshall, Texas. The Louisiana Co. has a line to Shreveport.

Jan 3, 1914

Cycle, automatic, in mine hoists, LV, 17. Cylindrical furnaces, repairing partly collapsed, XXXVI, 215-222. Dacite-porphyry, San Jose, Tamaulipas, Mex., percentage composition, XXXVI, 186. DAGGETT, ELLSWORTH: The Extraordinary Faulting at the Berlin Mine, Nev., XXXVIII, [liii], 297. Daiquiri, Cuba: geology, LIII, 3, 43. iron deposits, LIII, 40. Magdalena mine, LIII, 9, 23, 24. mines, bibliography, LIII, 59. situation of mines, LIII, 42. [ ]

Jan 1, 1918

By Geo Ashley

THE following paper is intended to be suggestive only, and to open the way for discussion and further observation. Its preparation was requested only two days before the time limit set for the submission of the papers comprising this symposium. Thus no time existed for detailed studies so it is largely a memorandum of such facts as have come incidentally to the notice of the writer in the study of coal in the field. The field study of sulfur in coal has received very little special attention or description from coal students. The presence of sulfur concretions is noted in hundreds of descriptions, and certain benches of a coal bed may be described as "sulfury" or the presence and position of sulfur bands may be noted in coal sections in connection with sampling. It may be accepted that some sulfur is present in all coal. The amount varies greatly in different regions, in different beds, and in the same bed in different areas. The anthracite of Rhode Island comes the nearest of any coal known to the writer of being free from sulfur, several analyses of that coal showing less than 0.1 per cent. Subbituminous coals in Colorado in a few places have close to 0.2 per cent. of sulfur on the dry-coal basis and in other states subbituminous coals approach this lower limit. Bituminous coals seldom run under 0.4 per cent. of sulfur on the dry basis, though in a few places dry bituminous coals in Colorado and Washington have between 0.3 and 0.4 per cent. The better known bituminous coals have almost everywhere over 0.4 per cent. The best of the Pocahontas and New River coals run close to 0.4 per cent., but there is very little commercial coal in Pennsylvania, Ohio, Indiana, Illinois, Kentucky, or the other states that runs under 0.5 per cent. on the dry basis. From these minimum figures, the amount will range up to 5 or 6 per cent. or higher if visible sulfur is not excluded. It must be remembered that the usual -analysis of a coal bed is not intended to give the total proportion of sulfur in the bed but the amount in the coal after the removal of the more obvious and larger sulfur masses.

Jan 9, 1919

By D. B. Hobbs, H. O. Burrows, T. D. Stay

Aluminum which has lost its original identity as to source may be considered as secondary. This would include scrap originating in the fabrication of aluminum, which is not consumed at the plant of fabrication, and all material resulting from fabrication, which has lost its original identity regardless of whether it be consumed at the plant of fabrication or not. In general, secondary aluminum may be divided into two classes, commercially pure and alloyed. The chief impurities found in commercially pure aluminum are copper, iron, titanium and silicon; while in aluminum alloys, copper, iron, titanium, silicon, zinc, manganese, magnesium, nickel, or tin, may be present in varying proportions. Occasionally lead and antimony are found in secondary aluminurn alloys, especially if the alloy results from remelting vender's automotive scrap. Such alloyed elements as are found in the scrap cannot be removed on remelting. In this, the remelting of secondary aluminum differs from the smelting of secondary copper or most other secondary metals. The majority of secondary materials reach the consumer in the form of remelt ingot or remelt No. 12 ingot. This ingot varies greatly in quality, depending upon the source of the material, and the manner in which it is refined and blended. The principal differences between primary and secondary ingot are: 1. The composition of secondary ingot may be more or less inclcfinite. 2. Secondary ingot may contain more dross and oxide. Secondary ingot may, however, be used successfully in a great itiany products. Relation of Primary Production to Secondary Production Table 1, compiled from data published by The Ameriran Metal Market, gives an approxirnatc idea of the relation of primary to srcondary production. Information obtained from other sources leads the authors to believe that the figures for secondary production are somewhat low.

By David J. Dunn

GENERAL NOTES Liner Design for Comminution Liners in crushers and mills are the mechanical link between machine and ore. The way liners transfer energy to media and ore determines to large degree the production rate, liner wear rate, maintenance cost, energy use, and availability of the comminution process. Plant capacity and mineral recovery economics, and return on investment, are thus strongly dependent upon these simple, low cost metal shapes of which so much is demanded. The complexity of dynamic relationships between liner configuration, material properties, ore characteristics, and operating parameters defy simplistic generalization. Rules-of-thumb and axioms of years past fall into disuse almost daily as new analytical methods, assisted by computers and sophisticated control systems, are applied to crushing and grinding processes. Recent literature is well supplied with references citing production benefits that improved liner designs produce. This chapter is intended to review especially promising liner designs and material developments and presents cameo case studies showing the benefits derived from their application to comminution circuits (Tables 1,2,4,5,7). Complete discussions of liner design and wear materials are beyond the scope of this chapter. Norman's comprehensive studies in references (1) and (2) and Mclvor's analyses of mill speed/configuration effects (3) are especially useful reading for designers and operators of crushing and grinding circuits. Changing trends in ore, product value, and costs of wear materials, interest, labor, and energy, make ongoing evolution of liner design equally important for existing mines and for projects still on the drafter's board. Original designs supplied as new equipment must, of necessity, be best estimates. These can usually be improved as operating experience replaces engineering forecasts. Advent of new materials or design concepts such as the Angular Spiral Liners (Korpi (4) ) or Norman's Bimetallic design (2) offer improvement potential that must be evaluated if a given circuit is to be kept competitive versus others making similar products.

Jan 1, 1982

By E. F. Loiseau

In a paper on the manufacture of artificial fuel, read at the Philadelphia meeting of February, 1878, I enumerated the difficulties which I had to overcome before succeeding in the mixing of coal-dust and clay, the compressing of the same mixture, and the water-proofing of the lumps. The drying of the lumps, after leaving the press, was the remaining difficulty, and it mas expected that a plan devised by Dr. Charles N. Cresson, of Philadelphia, would enable us to dry the fuel as rapidly as it was moulded, and that a continuous production could in that way be obtained. The company was reorganized. The works were purchased by the new company at an assignee's sale, and the oven was modified, according to Dr. Cresson's plan. Anticipating a possible failure, I had prepared a plan by which I expected to be able to demonstrate that anthracite coal dust nixed with pitch, could be manufactured with our present machinery slightly modified ; so that after all, if we were compelled to give up the attempt to make fuel for domestic use, there was a possibility of succeeding in the manufacture of a good steam-fuel. The plan suggested by Dr. Cresson for drying the pressed lumps of coal-dust cemented with clay, did not work as well as we expected. It enabled us to dry more fuel than we did before, but it could not be made to dry more than one half of the lumps produced by the press. The plan mas abandoned, and I was authorized to experiment with coal-dust and coal-tar pitch. The cement which is used in Europe to conglomerate coal-dust is usually dry pitch, which is prepared by separating from the tar, at a temperature of 572' Fahrenheit, the volatile matters which it contains. Some manufacturers, however, employ crude tar, others, a rich tar, which has been cleared of 25 per cent. of its volatile substances, by heating it to 392' Fahrenheit. But with common tar very weak fuels are obtained, which do riot burn well, and give out a strong smell and a great deal of smoke ; it is also necessary to subject them to a baking process, in order to solidify them, and to eliminate the more volatile of the materials contained. This operation of course requires a special plant, the cost of which increases sensibly the price of manufacture, without counting the products

Jan 1, 1880

By Alan K. Burton

An industry-wide demand for bigger and more efficient trucks, with their supposed economies of scale, is well established. Some trucks have been, and often are brought "off the shelf," with the manufacturer offering only certain minor options, much as in the private automobile industry. The market is well established; there is keen competition; in recent years there have been few significant changes, and few are expected. With large trucks (100-ton-capacity and over), however, the situation is different. Here, with an individual truck costing several hundred thousand dollars, there is an ever in- creasing trend to engineer a truck for a specific application. The body will be designed and sized for the material that the truck will carry; the engine and transmission will be geared to the haul profile, and tires will be designed to suit road conditions and work requirements. Early Truck Development Haulage trucks designed expressly for open-pit mine service were introduced during the 1930's. The first models to arrive on the scene hauled about 15 tons, and easily outperformed the modified highway trucks that had been used for mine haulage up to that time.

Jan 8, 1975

By S. F. Emmons

THE first paper which appears in the published Transactions of our Institute is that read by our respected Secretary at its first meeting in Wilkes-Barre, in May, 1871. It is entitled The Geological Distribution of Mining Districts in the United States, and presents a brief but masterly review of what was known of the distribution of our deposits of useful minerals, particularly the metals, not only from a geographical but from .a geological stand-point. At the request of Dr. Raymond, I agreed, somewhat hastily, perhaps, to write for this occasion a brief sketch of the geological distribution of the deposits of the useful metals in this country, in the light of the increased knowledge of the present day. In the time given no personal investigation was possible, and as it was therefore out of the question to attempt to make anything that could be considered an original contribution to the history of our ore-deposits, I have been obliged to limit myself to an examination of such published data within my reach as bore upon this subject, and could be consulted in the brief time I have been able to give to it. Had the geological investigations undertaken by the Tenth Census been continued systematically by the United States Geological Survey or by the Eleventh Census, it might have been possible to make a fairly-complete review of the subject. As it is, the principal result of my examination 1 has been to show how very unequal

Jan 1, 1913

By P. Ramachandrarao, T. R. Anantharaman

CONSIDERABLE interest has lately been evinced as regards the nature of chill zones in solidified metals and alloys. Biloni and Chalmersl were the first to show through their study of segregation substructures in some nonferrous alloys that the formation of the dendritic region may be preceded by a diffusionless solidification process, viz., predendritic solidification. Subsequently Bower and Flemings2 tried a special solidification technique wherein the liquid was drawn into a narrow copper mold with polished surfaces and concluded that convection might trigger some multiplication mechanism leading to grain refinement. Using uncoated and partially coated surfaces for molds in the Bower-Flemings technique as well as in conventional molds, Biloni and Morando3 have very recently brought out the importance of the rate of heat extraction on the mechanism of solidification. We report here on the surface structures and substructures observed in a Sn-1 wt pct Pb alloy solidified at even higher cooling rates (riz., l05 to l07 ºc per sec) than those employed by earlier workers. The alloy was made by melting tin (99.99+ pct) and lead (99.9+ pct) in a silica tube under vacuum. Small quantities of the homogenized alloy (0.5 to 1.0 g) were then quenched (or splat-cooled) from the melt by the "gun technique" developed by Duwez et al.4 The thickness of the resultant foils varied from specimen to

Jan 1, 1970

By E. F. Loiseau

IN a paper on the manufacture of artificial fuel, read at the Philadelphia meeting of February, 1878, I enumerated the difficulties which I had to overcome before succeeding in the mixing of coal-dust and clay, the compressing of the same mixture, and the water-proofing of the lumps. The drying of the lumps, after leaving the press, was the remaining difficulty, and it was expected that a plan devised by Dr. Charles M. Cresson, of Philadelphia, would enable us to dry the fuel as rapidly as it was moulded, and that a continuous production could in that way be obtained. The company was reorganized. The works were purchased by the new company at an assignee's sale, and the oven was modified, according to Dr. Cresson's plan. Anticipating a possible failure, I had prepared a plan by which I expected to be able to demonstrate that anthracite coal dust mixed with pitch, could be manufactured with our present machinery slightly modified ; so that after all, if we were compelled to give up the attempt to make fuel for domestic use, there was a possibility of succeeding in the manufacture of a good steam-fuel. The plan suggested by Dr. Cresson for drying the pressed lumps of coal-dust cemented with clay, did not work as well as we expected. It enabled us to dry more fuel than we did before, but it could not be made to dry more than one-half of the lumps produced by the press. The plan was abandoned, and I was authorized to experiment with coal-dust and coal-tar pitch. The cement which is used in Europe to conglomerate coal-dust is ,usually dry pitch, which is prepared by separating from the tar, at a temperature of 572° Fahrenheit, the volatile matters which it contains. Some manufacturers, however, employ crude tar, others, a rich tar, which has been cleared of 25 per cent. of its volatile substances, by heating it to 392° Fahrenheit. But with common tar very weak fuels are obtained, which do not burn well, and give out a strong smell and a great deal of smoke ; it is also necessary to subject them to a baking process, in order to solidify them, and to eliminate the more volatile of the materials contained. This operation of course requires a special plant, the cost of which increases sensibly the price of manufacture, without counting the products

Jan 1, 1880

By John Sullivan

Resources for Freedom, a report by the President's Materials Policy Commission, commonly termed either the Paley report, after its chairman, or the PMPC report, was issued in June 1952. The data collecting and assembly work for its preparation were done in 1951. The statistical base in most cases was 1950. It reviewed our economy and predicted what it will be in 1975.* The bases for the predictions were given. Consideration was given not only to statistical data and trends but also to technological changes taking place and likely to take place in the ensuing 25 years that will affect our economy. The supply of raw materials was studied and predictions made as to the availability of supply and the sources in 1975. One of the industries covered was iron and steel. For the most part the report did not attempt to provide a curve showing annual growth for any industry or commodity. It contrasted 1950 with the probable status in 1975. Interpolation between these dates is difficult and the Commission did not intend that it be used for short interim intervals. It is possible in 1958 to show the actual changes from 1950. The magnitude of the changes illustrates the agreement with some interpolation of the Paley report. Statistical comparisons can be general only because the Commission did not postulate a linear change. A study of the iron and steel industry will show if the general predictions have been realized or if gross errors were made. This paper is concerned with such an analysis. It is concerned with the production and consumption of crude, not fabricated products. It attempts to bring various facets of technical and statistical information on the industry up to date.

Jan 8, 1959

By Arthur Zentner

The electrolytic zinc plant of today is foreshadowed in the patents issued to Léon Létrange of Paris in 1881 and 1883l. He proposed roasting zinc blende to make the zinc soluble in water or sulphuric acid, thus obtaining a sulphate solution. His purification was apparently that used in the lithopone work of the day. For electrolyzing he proposed anodes of carbon or lead, for cathodes zinc, copper or brass. Numerous patents by other workers were taken out in the first 10 years, most of which dealt with sulphate solutions. It is easy to presume that the formation of chlorine gas in zinc chloride electrolysis caused early emphasis on sulphate work. Lack of success with this invited further work with chloride solutions. Efficient and cheaper oxidizing agents for use in the chloride processes were more generally available. Carbon anodes could be used instead of lead anodes, which were blamed for much of the early electrolyzing troubles and remained in disfavor for many years. Carl Hoepfner received his first zinc patents in 18902. He was the most persistent of those who worked with chloride solutions and met with the largest measure of success. Hc built three plants, only one of which remained in operation. This was built in 1896 at the plant of Brunner, Mond & Co., Winnington, England, now part of Imperial Chemical Industries Ltd. It leached with by-product calcium chloride from the company's Solvay alkali plant and returned to it the chlorine formed in electrolyzing. The zinc plant had a capacity of 5 long tons of zinc, said to have been doubled later, and remained in operation until 1924. No commercial plant using chloride solutions has operated since then. E. A. Ashcroft experimented in the middle nineties with chloride, alkaline and sulphate solutions on materials from Broken Hill, Australia. He built a plant with a rated capacity of 10 long tons of zinc per day, at Cockle Creek, New South Wales, in 1898. This figure was never approached nor was cyclical operation achieved. The work in the plant appears to have been largely with sulphate solutions. The plant suffered from a multitude of troubles: poor roasting, gclatinous silica, liberal use of live steam in solutions to combat the gclatinous silica with considerable

Jan 1, 1937

By R. A. Flinn, John T. Norton

A CONSIDERABLE number of experiments in recent years have definitely established the fact that the internal friction or mechanical hysteresis of a metal under cyclic stress is a property that is highly "structure sensitive." Because of this fact, it has been suggested that an observation of this property, which often is referred to as "damping. capacity," might be a useful indicator of structural. changes taking place when a metal or alloy is subjected to any of a number of metallurgical treatments. Damping capacity is of interest to both engineer and metallurgist, but from a rather different point of view, and the information that each desires from such observations is of a different nature. The metallurgist is in search of various external indications of changes taking place in the interior of a metal; changes which are in themselves not directly observable. Even if the observed phenomenon cannot be explained in fundamental terms, it may be empirically related to certain characteristics of the material and prove of real value in research. Internal friction os mechanical hysteresis occupies such a position, and, although it is nor well understood in terms of basic metallic theory, an observation of itt changes can serve in a very useful capacity. Of course, there is nothing new in the measurement of damping, but the use of this property in metallurgical research constitutes a vast field, which has received all too little attention: The present work is essentially of an exploratory nature in this field and is an attempt to evaluate the process as a research tool. The phenomenon of age-hardening was chosen as a typical example of a structural change and one method of measuring damping was examined in considerable detail.

Jan 1, 1938

By L. W. Eastwood

THE recrystallization and grain-growth phenomena of cold-worked metals have considerable industrial importance because of their role in the fabrication of metals. For this reason, and because of the general academic interest in the subject, these processes have received consider-able attention since the time of J. E. Stead's paper1 on The Crystalline Structure of Iron and Steel. There are considerable differences of opinion regarding the theory of recrystallization and grain growth and also differences in the observation of the modus operandi of the processes themselves. The value of many of the existing quantitative data on grain growth is decreased by the failure to distinguish between the grain sizes just after complete recrystallization and those resulting from coales-cence. For this reason also, the value of the diagrams of stable grain sizes, like those produced by Bass and Glocker2 and Czochralski3, is lessened in so far as an interpretation of the facts of recrystallization is concerned. It is hoped that the data presented in this paper will help to clarify and to simplify the facts relating to recrystallization, and at the same time will show that some of the present-day conceptions are unten-able. A paper on the theory of recrystallization, with additional data, will be completed in the near future by the writers.

Jan 1, 1935

By Alexander L. Holley

THE Pernot system of rotating and withdrawing the hearth of a Siemens regenerative gas furnace for the production of Martin or open-hearth steel, is, perhaps, the most conspicuous of the several improvements which have lately been made in the steel manufacture. These several improvements in the open-hearth plant are not combined in any existing works, but most of them will be combined in not less than three works now erecting in the United States; and it seems probable that their joint result will not only reduce the cost of products of ordinary grades to Bessemer rates, but that it will produce new and better grades of products. The open-hearth steel furnace and its operation are so generally understood that but a few words of general description are necessary. The ordinary furnace is not unlike the common reverberatory puddling furnace, except that an intense, uniform, and controllable temperature is maintained by the Siemens gas regenerative system. The materials. employed are various : melted or unmelted pig with ore, and with or without scrap; pig iron purified from silicon and phosphorus, with or without scrap; pig iron and scrap, melted together in a cupola, or charged hot or cold, together or separately, into the steel furnace; a pig-iron bath, and hot or cold steel or iron scrap, direct sponge or Catalan or puddled blooms charged into the bath. The operation is, to a greater or less extent, according to the nature of the materials used, a desiliconization and decarburization of the pig or other crude iron, and its dilution by already purified materials. Manganese is employed at the end of the operation to remove oxide of iron and silica, a regulated amount of manganese remaining in the product. Figs. 2 and 3, Plate IV, represent the hearth and roof of the Pernot furnace; Fig. 1 shows, in cross section, the general arrangeent of open-hearth plant with Pernot furnaces, as generally designed by the author, and now building at two works. The engrav-

Jan 1, 1879

By C. V. Millikan

New developments in air-gas lift practices in the Mid-Continent area since our Pall meeting in Fort Worth have done much to increase the efficiency of installations, and thus bring within economic limit of air-gas lift many wells which could not have been flowed profitably before. After the gas-lift had so thoroughly demonstrated its value in the Seminole field, its use spread to other areas and many installations were made of which the economy could be questioned. In the Seminole area, when production began to decline it was necessary either to increase the efficiency of the air or gas-lift or to put the wells on the pump, and pumping was not a process of lifting oil to which any operator looked forward with confidence. These conditions have resulted in the development of many practices which increase the efficiency and permit wells to be flowed with air or gas which earlier could not have been flowed economically, and wells which have been flowing to continue to a lower rate of production. The practices which have come into more common usage in the Mid-Continent area recently are mostly revivals of and improvements on practices which have been known in air-lift work for several years. Many arc peculiar to the individual well on which they are used. Intermittent Flowing Some interesting results are being obtained in Seminole and other districts by intermittent injection of gas. Gas is introduced during per-iods iods of 3 to 5 min. at a rate considerably over that necessary to acquire the production at a steady rate of injection, and is then cut off for a period of 3 to 15 min. Two to five wells are run from the same group of conlpressors. The total volume of gas required is sometimes reduced as much as one-third of that required when it is introduced at a constant rate, without changing the amount of oil production. The maximum pressure required is usually higher, but the average equal to or lower than that required for constant rate of flow. The effect on the wells is usually an irregular rate of flowing which may cause inconvenience where recycling is practiced. It would seem that this increase in efficiency is due to less slippage when the gas is introduced intermittently than when it is intro-

Jan 1, 1928