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By Harry K. Ihrig

The hot-working of iron and steel is an art dating back to antiquity, but until about 25 years ago, relatively few alloying elements were used, and these were present only in small percentages. With the exception of sulphur, the amounts of other elements in steels did not markedly affect their hot-workability. The references in the literature on the effect of other elements on the hot-workability of steel are usually reports of failure of these steels in forging or rolling.1-8 With the increased use of alloying elements, and their use in larger amounts, it was observed that many of the new steels were red short in certain critical ranges or at all hot-working temperatures. The stainless steels are particularly difficult to hot-work. The determining of the correct conditions for piercing, rolling and forging of these alloys by experimentation in the mill often results in large losses of these expensive metals. It also is found that the hot-workability limits of many types vary from heat to heat, and hence poor results are obtained on changing to a new heat after a previous one has rolled satisfactorily. To determine the effect on hot-workability of iron to which various elements have been added, it was necessary to devise a method that could be used on small quantities of metal. In such a method, the minimum number of variables should be present, and the procedure should be simple, quick and correlatable with large-scale hot-working operations. Sauveur,9 in the first Henry Marion Howe lecture in 1924, described the effect of carbon on the ductility of steels in torsion near their critical points. He found that carbon increases the plasticity of gamma iron. In the 1930 Campbell Memorial lecture,10 he gives the effect of carbon, chromium, and chromium and nickel on the ductility of steels under 2000°F. in torsion. Ellis11 has studied the malleability of steels at various elevated temperatures by means of a single-blow drop-hammer test. In this test the percentage decrease in height of standard cylinders is taken as a measure of their malleability. He has shown that in the low-alloy steels studied, carbon has a greater effect than nickel, chromium and vanadium. In 1938 the first tests were run on a new quantitative hot-workability test in the laboratories of the Globe Steel Tubes CO. Thum12 mentioned it in 1940. An illustration of the apparatus was published in January 1942.'' The effect of a few alloying elements on the hot-workability of metals was shown in a description of the test in 1944.14 Description of Test Method The method adopted after a trial of several others is a rapid twisting of bars to failure in a furnace. The standard-size bar was chosen as 9/16 in. It is prepared from larger pieces by forging and cold-

Jan 1, 1947

By Harry K. Ihrig

The hot-working of iron and steel is an art dating back to antiquity, but until about 25 years ago, relatively few alloying elements were used, and these were present only in small percentages. With the exception of sulphur, the amounts of other elements in steels did not markedly affect their hot-workability. The references in the literature on the effect of other elements on the hot-workability of steel are usually reports of failure of these steels in forging or rolling.1-8 With the increased use of alloying elements, and their use in larger amounts, it was observed that many of the new steels were red short in certain critical ranges or at all hot-working temperatures. The stainless steels are particularly difficult to hot-work. The determining of the correct conditions for piercing, rolling and forging of these alloys by experimentation in the mill often results in large losses of these expensive metals. It also is found that the hot-workability limits of many types vary from heat to heat, and hence poor results are obtained on changing to a new heat after a previous one has rolled satisfactorily. To determine the effect on hot-workability of iron to which various elements have been added, it was necessary to devise a method that could be used on small quantities of metal. In such a method, the minimum number of variables should be present, and the procedure should be simple, quick and correlatable with large-scale hot-working operations. Sauveur,9 in the first Henry Marion Howe lecture in 1924, described the effect of carbon on the ductility of steels in torsion near their critical points. He found that carbon increases the plasticity of gamma iron. In the 1930 Campbell Memorial lecture,10 he gives the effect of carbon, chromium, and chromium and nickel on the ductility of steels under 2000°F. in torsion. Ellis11 has studied the malleability of steels at various elevated temperatures by means of a single-blow drop-hammer test. In this test the percentage decrease in height of standard cylinders is taken as a measure of their malleability. He has shown that in the low-alloy steels studied, carbon has a greater effect than nickel, chromium and vanadium. In 1938 the first tests were run on a new quantitative hot-workability test in the laboratories of the Globe Steel Tubes CO. Thum12 mentioned it in 1940. An illustration of the apparatus was published in January 1942.'' The effect of a few alloying elements on the hot-workability of metals was shown in a description of the test in 1944.14 Description of Test Method The method adopted after a trial of several others is a rapid twisting of bars to failure in a furnace. The standard-size bar was chosen as 9/16 in. It is prepared from larger pieces by forging and cold-

Jan 1, 1947

By A. A. Blow

The productive area of the Leadville mining district immediately adjoining the city of Leadville, which, by its wonderful richness, has attracted the attention of the mining world for the past twelve years, may, with a few exceptions, he considered as divided into seven local mining centers, separated one from another by the topographical features of the country, and designated by common consent as Fryer Hill, Yankee Hill, Breece Hill, Rock Mill, Printer-Boy Hill, Iron Hill, and Carbonate Hill. Of these seven distinot mining localities, or groups of mines, the central one, Iron Hill, is the one of greatest importance and interest. It was the scene of the earliest discovery of carbonates, as far back as 1875, and since that time has always maintained its position

Jan 1, 1890

By T. E. Eagan, W. R. McCrackin

IN dealing with segregation in babbitt, and its effect on the final cast structure, which is a bearing, it is obviously impossible to cover all of the compositions manufactured. Each composition, of course, will exhibit certain specific types of segregation. However, as examples,, two compositions of babbitt are presented: one a tin-base of well-known analysis and the other a lead-base, which in the past few years has found wide usage. Bearings usually are cast either statically or centrifugally; therefore the effect of these two methods on segregation is presented. EXPERIMENTAL PROCEDURE A slab of babbitt 1/2 in. thick by 5 in. wide and 17 in. long was cast, using a book mold with the long edge vertical. An A.S.T.M. grade 2 babbitt was used (3.5 per cent copper, 7.5 per cent antimony, remainder tin), to which 0.10 per cent tellurium had been added. Unfortunately, no metal without tellurium was available. The mold to hold the babbitt was heated to approximately 300°F., the temperature being judged by the babbitter. The pouring temperature of the babbitt was 875°F. (470°C.). One slab was made by allowing the babbitt to cool without stirring. The other slab was stirred during the entire cooling cycle. This stirring consisted of a vigorous churning or puddling into the mold until complete solidification had taken place. Three samples were removed from these slabs. One was taken at the extreme bottom, another half way to the top, and another at the extreme top, all at the center of the width. Chemical, macroscopic and microscopic examination was made of all samples. Table I shows the chemical analyses obtained at the described positions [ ] in the slab. The analyses show no serious amount of gravity segregation. Microscopic examination from edge to edge of the slab showed little change in structure. From top to bottom there was a progressive coarsening of the grain size in the stirred slab but little change in the slab that was not stirred (Fig. I). No definite exhibit of segregation could be detected. In line with our experimental study on the tin-base babbitts, we cast an almost duplicate slab using A.S.T.M. Alloy No. 15, containing 0.9 to 1.25 per cent tin, 14.75 to 15.5. per cent antimony, 0.80 to 1.25 per cent arsenic and 0.4 per cent copper. The slab was 16 in. long and 3/8 in. thick, cast with the long side vertical. One slab was allowed to cool normally and the other was stirred continually during cooling. The pouring temperature of the babbitt was

Jan 1, 1944

By Clarence Seyler

THE technical difficulties of cutting thin sections of coal for examination by transmitted light have hitherto restricted the investigation of the important subject of the microstructure of coal to the few possessed of the requisite skill and time. Apart from this, the method fails with anthracites and other coals rich in carbon, owing to the opacity of the material. Occasional use of the method of polishing a surface, with or without etching, has been made, but it was not until Winter1 published an account of his results that attention was seriously directed to the method. In May, 1923, a specimen of dull anthracite came into my hands; I tried Winter's method on it and the presence of megaspores and other vegetable structures became clearly visible. A preliminary notice was published by me;2 but I soon abandoned the use of Schulze's solution having found that a mixture of chromic and sulfuric acids gave far better results. In the meantime Turner and Randall, in America, had independently developed the method of flame etching, as applied to anthracite, with great success. I have spent a year studying the method of chromic etching, which gives excellent results with bituminous coals and cannels, as well as with anthracite. For anthracites, I have used the chromic method and Turner's method of flame etching, whichever was the more convenient or as a check one on the other. The polishing is done, according to metallurgical practice, by the use of a polishing machine and successively finer emery paper, followed by polishing on cloth moistened with a suspension of levigated green oxide of chromium, and a final rubbing on "selvyt" (a cotton velvet polishing cloth) moistened' with alcohol. The polished sample is examined by reflected light with a 2/3 and 1/6 in. objective. Bituminous coals usually show considerable structure, and even anthracites show it faintly in places. The sample is then etched by immersion in a boiling solution made by adding 10 c.c. of concentrated sulfuric acid to 30 c.c of a saturated solution of chromic acid; enough water is then added to dissolve

Jan 3, 1925

By S. E. Bronisz, R. E. Tate

s-plutonium samples possessing a strong growth texture have been produced by allowing them to transform under pressure from p to a. A fiber texture with [010] parallel to the pressure axis results. The textured samples are expected to be useful in determining the effects of crystallographic orientation on the physical properties of a plutonium, and initial results of measurements of resistivity and mechanical properties are described. THE crystal structure of a plutonium1 is mono-clinic, P21/m, and many of the metal's properties should reflect the crystallographic anisotropy. Unfortunately, it has not yet been possible to grow useful sizes of single crystals of a plutonium. Therefore, few of plutonium's orientation-sensitive properties have been determined as a function of crystallographic orientation. One way to gain information about at least some of the orientation-dependent properties is to study a highly textured sample. Such samples have been produced by cold rolling a plutonium,2 but they are necessarily very small in one dimension. We have now successfully used two other techniques to produce highly textured samples, not limited to small thicknesses. METHODS OF PRODUCING PREFERRED ORIENTATION The texture is produced by causing the plutonium to transform from ß to a while under pressure. It was observed by Gardner3 that applying a compres-sive load during the transformation resulted in the formation of columnar grains of a plutonium, and Cramer4 observed a similar structure in some diffusion couples rolled in the P phase. Neither of these workers, however, investigated the subject beyond these observations. The more flexible of the two methods developed is that of compressive loading. The technique is to enclose a sample of plutonium in a die assembly before applying the load. It is possible, of course, to dispense with the die and simply press the sample between two platens. In this case, however, the unrestrained sample deforms during the pressing, making it difficult to maintain the load and to control the final sample thickness. This compressive loading technique has been used on specimens ranging from 1/4 to 3 in. diameter, with height-to-diameter ratios ranging from 5 : l to 1:6. The procedure begins with loading the sample, a right cylinder of a plutonium, into the pressing die. Plastic deformation of the sample while it is being pressed is minimized by machining the sample so that its diameter is nearly the same as that of the die barrel. Then the loaded die assembly is placed in a vacuum pressing can that fits on a hydraulic press. After a vacuum is achieved the die assembly is heated to 180°C and equilibrated. The load is then applied and the specimen and die are allowed to cool to about 40° to 50°C before the pressure is removed. The resulting sample is composed of rod-shaped a -plutonium grains, the rod axes being parallel to the cylinder axis and the pressing direction. Photomicrographs of the oriented structure are shown in Fig. 1. Although most of the specimen is composed of grains whose rod axes are parallel to the cylinder axis, a thin, peripheral layer consists of rod-shaped grains whose rod axes are perpendicular to the cylinder axis. Presumably, the highly plastic nature of p plutonium leads to approximately hydrostatic conditions during the initial stages of the P — a transformation under pressure. At this time, the grains in the peripheral layer would have grown parallel to the local force direction. During the latter stages of the transformation, the accompanying volume contraction would have eliminated the radial forces, leaving only the axial force and resulting in the growth of the observed structure. The growth texture did not form without the application of pressure. Attempts were made to produce the texture by repeating the standard temperature cycle without

Jan 1, 1965

By Nathan C. Rockwood

LIME is a very general term applied to products of limestone, in popular treatises often incorrectly, including ground or pulverized limestone used in agriculture. When used without qualifying adjective, the term usually means burned or calcined limestone, or quicklime, or calcia. The corresponding calcined product of magnesite is magnesia. If the calcined rock is relatively pure calcium carbonate, the resulting lime is a "high-calcium" lime; if the rock is dolomite, or a combination of calcium and magnesium carbonates, the lime is a "dolomitic" or a "high- magnesium" lime. There are various grades in between, depending on the percentage of magnesium carbonate and other ingredients in the raw rock. For some industrial purposes only high-calcium limes are suitable; in other processing-as, for example, neutralizing acid wastes -the relative percentages of magnesium and calcium carbonates in the raw material are not important. Limestone is burned (roasted or calcined) in furnaces known as lime kilns by direct exposure to the hot gases and flames. When heated to incandescence, the carbon dioxide content of the rock is expelled, leaving calcium and magnesium oxides, according to the formula usually written: [ ] This thermal reaction is reversible, which requires that the lime be withdrawn from the "calcining zone" of the kiln about as fast as made. Pure calcium carbonate would lose 44 pct of its weight in the calcining process; dolomite, 48 pct. Generally, the lime will retain the approximate size and shape of the piece of rock from which it is made but some few limestones tend to break down into granules or dust. Hence lime (quicklime) comes from the kilns in lumps or granules and normally is packed in water- tight containers in these forms, or is pulverized after calcination.

Jan 1, 1949

By Charles W. Dickson

CONTENTS. [ ] I.THE RELATION OF NICKEL TO PYRRHOTITE. Introduction. The Sudbury district is to-day one of the two great sources of nickel in the world. The peculiar geological relations of

Jan 1, 1913

By George M. Fowler

THE Tri-State district, as outlined in this paper, refers to the entire mineralized area in southwestern Missouri, southeastern Kansas and northeastern Oklahoma (Fig. 1). The part of the district in Missouri and near Galena, Kans., is still sometimes referred to as the Joplin district (Fig. 2). The Picher-Miami area is that part of the Tri-State district located contiguously in Kansas and Oklahoma in the vicinity of Baxter Springs, Picher and Miami. This paper is confined almost wholly to the ore deposits of the Tri-State district and particularly to the Picher-Miami area. Our study of the ore deposits of this district dates from late in 1925 (by Fowler) and early in 1927 (by Lyden) to the present. Our work has been confined almost entirely to the search for ore for numerous companies and individuals. It was not possible for us to undertake numerous highly interesting investigations which presented themselves but which would not immediately help in finding ore. We particularly refer to the general structural geology of the Ozark uplift, the genesis of the ore, and other problems of a similar nature. The local and general structural problems of the district are being solved gradually as the work progresses. The factors that control the loci of the several orebodies are evident. This paper is based almost exclusively upon our own observations. Most of the important mines in the Picher-Miami area were studied in detail. A map (Fig. 5) is included which shows this area and the properties we have examined to date. When it was convenient we visited, studied and compared structural relations in numerous mines in states outside the district. Some of these observations are noted in this paper.

Jan 1, 1932

By W. P. Sykes

ThiS investigation was undertaken primarily to establish the relations existing between temperature and mechanical properties in molybdenum, nickel, and an aluminum-copper alloy. Mlolybdenutn (m.p. 2500" C.) was chosen because it is partly similar to tungsten and partly similar to the common ductile metals. Also it is known to furnish, by proper treatment, a desirable material to use in studying relation of grain size and physical properties. The molybdenum used was of the quality that is drawn into wire 0.003 in. in diameter for use as filament supports in incandescent lamps; Chemical analysis shows less than 0.1 per cent. of impurities. Nickel belongs to the same class as iron. Its melting point is 1450" C. and an allotropic change at about 370" C. results in a loss of magnetism above that temperature. This feature made nickel doubly valuable for the purposes of these tests. The nickel used was obtained from the Driver-Harris Co. as 0.090 in. (2.3-mm.) wire, annealed; analysis showed 99.8 per cent. nickel and 0.150 per ccnt. iron. Aluminum is one of the low melting-point metals. Some tensile tests at clevated temperatures have been reported by Bengough but the possibility of learning more with the low temperature and sensitive apparatus available rccommendcd this metal. The samples marked A1 arc an aluminum-copper alloy that contains 3 per cent. copper, 0.42 per cent. iron, and 0.21 per cent. silicon. The presence of the copper somewhat coniplicates the analysis of the results; but the action of copper in aluminum has been studied so that its influence might have been foretold, in part at least. The material and analyses were furnished by the Aluminum Castings Co. The nickel wire, which was deformed at 400" C., was drawn under a bath of molten lead and through a die, which also was immersed in the bath. A thermocouple was suspended in the molten metal to indicate the temperature. Hot oil was uscd as the heating bath for drawing the

Jan 1, 1921

By AIME AIME

Acid Open-Hearth Manipulation.. By ANDREW MCWILLIAM and WILLIAM H. HATFIELD, ii, 279. Discussion by J. J. MORGAN, iii, 647; E. H. SANITER, iii, 648; MCWILLIAM and HATFIELD, 111, 648. ADDICKS, LAWRENCE. The Effect of Impurities on the Electrical Conductivity of Copper, iii, 559. Address of Welcome to the U. S. National Museum, Washington, D. C. By RICHARD RATHBUN, .iv, 923. ALLDERDICE, TAYLOR. Discussion of MR. ROE'S paper, The Mann¬ facture and Characteristics of Wrought Iron, v, 1091. American Mining Engineer. Discussion by ARTHUR JARMAN, iii, 641. An Automatic Stock-Line Recorder for Iron Blast-Furnaces. By J. E. JOHNSON, JR., iii, 509. Anthracite-Washeries. By GEORGE W. HARRIS, vi, 1263.

Jan 1, 1907

By Chas. Y. Clayton, Francis B. Foley, W. E. Remmers

DuRing the summer of 1919, the late Dr. Henry M. Howe, then Chairman of the Division of Engineering of the National Research Council, organized a committee to obtain a better insight into the behavior of carbon steels under the influence of various treatments by a proper control of the time and temperature factors. During part of 1919 and 1920, work in connection with this investigation was carried on at Dr. Howe's laboratory at Bedford Hills, N. Y. During 1921 there was an enforced hiatus in the work, occasioned by the illness which resulted in Dr. Howe's death in 1922. At that time one of the present authors compiled the results of the work which had been done and this was published in 1923.' Following the publication of this work, it seemed desirable to carry on in the same manner an investigation of steel of C 0.75 per cent., which steel had not been as fully treated as had the other steels of C 0.34 and 0.52 per cent., used in the published work. Furthermore, certain unusual results have been obtained in the treatment of C 0.52 per cent. steel by quenching and drawing, and repetition of this part of the work seemed advisable. This has been done during the past year at the School of Mines and Metallurgy of the University of Missouri at Rolla, Mo., by a cooperative undertaking of the School and the Bureau of Mines, working in conjunction with the Committee on Heat Treatment of Carbon Steels of the National Research Council. The present paper is a report of the results obtained in this work.

Jan 1, 1926

By F. W. Jessen

The Mechanism of solution of salt and mixed halites of sodium and potassium is reviewed. The variation in the rate of salt removal under both laminar and turbulent flow conditions is discussed. Many changes are possible in the development of solution cavities whether used for production of salts or for storage of hydrocarbons. The parameters influencing the type and shape of cavity formed with single well or multiple well systems are examined and information presented regarding field application of techniques developed and the means of controlling overall configuration of solution cavities.

Jan 1, 1972

By A. W. Fahrenwald

The physics and chemistry of the flotation process are not well understood. Many papers dealing with the theory of flotation have been published but most have been narrow in their viewpoint. No theory advanced has done more than explain, more or less satisfactorily, various isolated phenomena. Scientists have done little with the problem, doubtless because they have not seen sufficient of the practical side of the subject to have their interest aroused. Any attempt to explain the mechanism of flotation that considers only contact angles, surface tension, adsorption, the floating of needles, flocculation, or any other single and narrow phase of the question is sure to be disappointing. Flotation is a problem of colloid chemistry and must be studied as such. In a broad general way, flotation is a process involving and operating by virtue of surface reactions. The term "surface reactions" may be open to criticisms. Many chemists give the term "reactions" a definite and restricted meaning and to such the term may connote change in atomic grouping in strict stoichiometric ratios. While Langmuir looks upon adsorption as a reaction, and there is much evidence in support of this view, we may look on adsorption as a physcial process as far as this paper is concerned. The term seems well suited to the work in general. Presumably these reactions are reactions between the same kinds of forces (electrical) and differ only in degree and in the surface manifestations produced. This premise seems logical if we accept the theory that the atoms of dl elements are made up of grains of electricity, having mass and charge, called electrons; and that atoms differ from one another only in the number and arrangement of the electrons about a positive nuclear

Jan 1, 1924

By John McCaslin

ONE of the most common technical terms in the U. S. today is automation-a word not listed in the 1946 dictionary. The influence of automation on the national economy has been tremendous. It has even been the subject of congressional investigations. Automation, writes Aronson, substitutes mechanical, hydraulic, pneumatic, electric, and electronic devices for human effort and decision? Automatic devices and instruments are used extensively in some industries, but many others have yet to take full advantage of these great discoveries. The petroleum industry has been a leader in using automatic controls-some refineries are almost completely controlled by automatic devices. The field of geophysics is entirely dependent on instruments and has progressed at almost exactly the same rate as improvements in instrumentation. In metallurgy and mineral dressing use of instrumentation is increasing very rapidly. Mining engineers throughout the country are beginning to think in terms of instruments and controls.

Jan 3, 1958

By R. T. Southin

Cast ingots of 99.99 pct purity A1 and aluminum/copper alloys containing up to 2 pct Cu have been found to contain four zones rather than the three previously accepted, i.e., chill, colummar, and equiaxed zones. The fourth zone consists of a coarse dendritic layer across the top surface of the ingot which is open to the atmosphere. It is also found that the grains in the equiaxed region have a "cornet" shape, with a head which is coarsely dendritic and a tail which grew with the same structure as the columnar grains. Experiments using mechanical barriers, and others involving the elimination of the surface dendrile layer, have indicated that nucleation of the equiaxed zone is caused by the showering of dendritic particles from this surface dendrite layer. These particles are the dendritic heads found in the comet grains. A mechanism of nucleation and growth of these comet grains is put forward. Experiments with a number of other metals and alloys suggests that these conclusions may apply generally to ingots cast without the addition of nucleating agents, and solidified under normal conditions. THE macrostructure of cast ingots may contain the following three zones: i) a peripheral zone of fine equiaxed grains, commonly called the chill zone; ii) a zone of columnar grains extending inwards from the chill zone; iii) a central zone of equiaxed grains; these are normally larger than the chill grains. All three zones are not necessarily present in any particular ingot since their existence and magnitude depend upon the casting conditions and composition of the cast material. The mode of formation of zones i and ii is fairly well understood. However, the cause of the central equiaxed zone remains a matter of conjecture. Previous theories put forward to explain the mechanism of nucleation in the equiaxed zone have been examined by Chalmers1 and Winegard.2 At the time when the present work was carried out the most re -cent hypothesis was that due to Chalmers,1 who recognized more fully than previous workers that conditions in this zone during solidification were not conducive to nucleation. In his hypothesis, he suggested that nuclei were formed near the mould wall during the very early stages of solidification, and that they can drift into the central zone by convective motion. This was supported by evidence from experiments using mechanical barriers to stop the drift of nuclei. A similar hypothesis had previously been put forward by Genders.3 More recently, Jackson et al. 4 have observed that dendrite arms in organic compounds can melt off during solidification. They have postulated that this occurs in metals and alloys, and that the dendrite arms which have been freed from the main dendrite act as nuclei for the equiaxed zone. In the present work, critical metallographic examination has shown that there is a fourth zone in the macrostructure of cast ingots which is a dendritic layer over the top surface of the ingot. It is also shown that there is a relationship between this zone and nucleation of the equiaxed zone. EXPERIMENTAL DETAILS The alloys examined were prepared from super -purity aluminum of 99.99 pct min purity (spectro-graphically detected impurities of Cu, Fe, Si, and Mg) and copper of 99.98 pct min purity (spectrographically detected impurities of Si, Zn, As, Fe, Pb, Bi, Ni, Sn, Mn, Ag, Cr, and Al). Three compositions of ingots were examined, containing 0.0, 0.1, and 2 pct Cu, respectively. The alloys were melted in an alumina-lined salamander crucible using a medium-frequency electric induction furnace; when the appropriate casting temperature was reached, the alloys were cast without degassing or fluxing treatment. The mould used was made of electrode graphite and had the following dimensions: external diameter 6 in., height 9 in., with a mould cavity 8 in. deep and a diameter tapering from 5 in. at the top to 4 in. at the bottom. Casting temperatures used were generally in the order of 70" to 90°C above the liquidus and the mould was at room temperature before casting. Inserts kere placed in the mould cavity in some experiments. These consisted of either an 18-g stainless-steel tube of 2 in. diam held axially in the mould i in. off the bottom and extending 1 in. out of the top of the mould or a "trap-door" barrier of stainless-steel gauze of 24-mesh held horizontally in the mould 31/2 in. down from the top. The construction of this insert is shown in Fig. 1. All inserts were preheated prior to casting to prevent chilling. RESULTS The macrostructures of ingots of the three compositions are described, in terms of the three generally recognized zones, in Table I, and illustrated in Figs. 2(a) to (c). The most interesting observation in this table is that relating to the shape of the equiaxed grains, which were not in fact equiaxed but of almost tear-drop shape. Closer examination of these grains showed that each consisted of a head which had a coarse dendritic structure and a tail which always grew in the opposite direction to heat flow, and which had the same structure as that of the columnar material of the ingot concerned; i.e., in the pure aluminum and 0.1 pct Cu alloy it was cellular and in the 2 pct Cu alloy it was cellular-dendritic. Identification of original cast grains was greatly hampered in the super-purity aluminum ingots, and to a lesser degree in the 0.1 pct Cu alloy,

Jan 1, 1968

By J. D. Price, G. V. Woody

MANY producers of by-product coke have spent considerable time and given considerable thought to the use of a substitute for low-volatile coal as an admixture with high-volatile coking coal for charging high-temperature by-product coke ovens. Generally speaking, there are two principal reasons for this, one being occasioned by the lack, in certain localities, of low-volatile coal delivered at a cost sufficiently low to permit its use, and another being the desirability of finding a substitute product with a delivered cost lower than the cost of the low-volatile coal. It was for the first of these reasons that the Colorado Fuel and Iron Corporation was particularly interested in this subject. This paper deals with the experimental work and the results obtained by that company in producing and using low-temperature char. OVERCOMING DEFECTS IN COKE FROM COLORADO COALS Colorado coking coals are all of the high-volatile type and were all laid down during he Cretaceous period, which makes them something like 80 million or so years younger, geologically, than eastern coals. They behave, when coked alone, something like the Pittsburgh-seam coals. They make a very brittle, highly cross-fractured, fingery coke of fair shatter value but quite low in resistance to abrasion. Mixed with a low-volatile coking coal such as Pocahontas or certain Oklahoma coals, they make a coke that is equal to virtually any of the eastern cokes. The inferior quality of Colorado coke has long been recognized, and a considerable amount of time, effort and money has been spent upon investigations of means for improving its physical properties. While it has been found that some improvement in quality of coke can be secured by the adjustment and control of such variables as pulverization, moisture content, oven temperature and bulk density of charge, and through the addition of certain inert materials such as pulverized coke breeze, pitch, high-volatile noncoking or semicoking coal, the benefits so gained have been comparatively small. There are no low or medium-volatile coking coals available within a reasonable freight-cost distance. Therefore a substitute for low-volatile coal was developed through low-temperature carbonization-or, more correctly speaking, through the partial devolatilization-of high-volatile coals. The blending of this lower volatile char with the high-volatile coking coal distinctly improves the quality of coke made from Colorado coal. There is nothing especially new about this idea. In 1908 a Japanese patent was taken out by Kotaro Shimomura, whose claim was: The method of making a nonfingery coke out of bituminous coals, without using natural coals of low-volatile matter; according to which a certain coal is heated at a temperature between about 300°C. and about 600°C. so as to leave about 15 to 25 per cent volatile matter in the coal; this coal is mixed with the

Jan 1, 1944

By J. F. Lewis

Much has been written on this great engineering work, principally from the civil engineer's stand-point. In presenting the subject to the Institute, it seems necessary to include something of geology as well as engineering. In this case, it is particularly the glacial and post-glacial periods with which we are concerned; for it has been clearly proved that the canal recently excavated has not for the first time opened the Des Plaines valley for drainage away from Lake Michigan, and that this valley, as well as the site of this city, is very closely connected with the processes and effects of the ice period. We have simply renewed a channel and a drainage direction which formerly existed. As the days of deep water-ways for commercial purposes are fast approaching, engineers may find the consideration of ancient topography and geologic changes highly useful. For what I may say on this subject I am greatly indebted to Mr. Ossian Guthrie, who has made an earnest study of glacial geology and labored especially to decipher the records of its history in this region. * Chicago is situated in the track of one of four great glacial ice-streams that swept down from the North: one moving due South from Marquette and entering the Illinois valley at Ottawa; one through the Lake Michigan valley, entering the Illinois valley near Lemont; one from Saginaw Bay diagonally across the States of Michigan and Iadiana, entering through

Jan 1, 1898

By Henry Hebley

IN preparing this paper it has been the aim of the writer to keep the problems of both producers and consumers in mind. Until now, no attempt has been made to familiarize each group with the other's practice and limitations. This paper is an effort to acquaint the readers with some of the factors pertaining to the problem and cost of mining and preparing steam coal, and also to the economics of producing steam with such coal. In recent years all lines of endeavor have turned to intensive mechani-zation in order to lower the unit cost of production. The average fuel consumption in steam electric generating stations has dropped in 20 years from 4.0 lb. to 1.4.1b. per kilowatt-hour; while the modern power station can generate 1 kw-hr. on a fraction under 1 lb., or 13,000 B.t.u. coal. Also, the amount produced per man has in that same period risen from 3.8 to 8.2 tons, owing to the use of modernized equipment below ground for coal cutting, drilling, shooting, loading, hauling and hoisting. Unfortunately, the rapid speed of 5 tons per minute of operation at which the coal is loaded mechanically precludes any appreciable removal of impurities at the coal face, so that the raw coal is hoisted containing a markedly higher percentage of impurities than the hand-loaded coal, which was subjected to the scrutiny of the miner during loading. Also, during the past 20 years, certain seams of coal lying close to the surface have been made economically available by the improved design of electrically operated shovels and draglines for the removal of overbur-den running as high as 56 ft. This strip coal frequently contains so much ash in the raw state (Table 1) that it would have no sales value. There-fore, coal preparation must be adopted to beneficiate the raw product. Some seams in the United States have a decreasing ash content with decreasing size, owing, in all probability, to the fact that the coal is friable while the impurities are hard, causing a concentration of the low-ash material in the fine sizes. Illinois No. 6 coal being rather hard, naturally the reverse is true.

Jan 1, 1937

By H. A. Kuhn

THE Pittsburg coal field in western Pennsylvania, is conceded to be the most important in the world. To measure its importance it is necessary to understand the extent of its service in the various industries of the country. Probably 90 per cent. of the pig iron manufactured in the United States up to the present time has been made by using coke manufactured from the Pittsburg coal seam in western Pennsylvania. This coal field is the foundation on which the city of Pittsburg rests and is the reason for the great growth of the iron industry in the Pittsburg district. Iron ore is brought to this district, not because Pittsburgh is a. natural location, over other locations, for the iron and steel industry-as its position places the manufacturer at the mercy of the railroads-but the ore is brought 1,100 miles to meet the fuel. It can be said that the illuminating-gas industry in the United States has used this coal exclusively to the same extent that the pig-iron maker has used it. It may be also said that 20 to 25 per cent. of the fuel used on railroads in the United States conies from this coal field. The Pittsburg coal field is unquestionably the center of the industrial population of the United States, for in addition to the industries of the district and those closely adjoining, it has tributary to it all the cities and industries along the Great Lakes and practically all of Canada with the exception of the extreme western and eastern ends. It supplies the industries and population west of Duluth and Superior many hundreds of miles. This coal is floated down the Ohio and Mississippi rivers, supplying the towns en route, and is delivered in New Orleans, a distance of 2,200 miles, for approximately SO to 90 c. per ton transportation cost. It is delivered on the docks of Superior and Duluth at a cost of transportation 50 c. a ton less than the cost of transporting the same coal from Pittsburg to a local consumer in Philadelphia. With other Appalachian coals it has large markets east and along the seaboard, especially for byproduct-coke making and the illuminating-gas industry. It is considered the premier railroad fuel of the world on account of the fact that this coal in a given-sized locomotive will probably haul more cars than any other coal in the

Jan 10, 1914