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By Sir Albert E. Kitson

The manganese ore deposits of the Gold Coast, British West Africa, occur in very ancient rocks, of both sedimentary and metamorphic types. In certain respects they have a strong resemblance to those of India and Brazil, as contrasted with those of Tertiary age in Georgia, but in this paper no careful comparison with them can be made. Viewed from the present condition of the manganiferous rocks, the oldest deposits are in the sediments. Later than these are the progressively metamorphosed representatives of these sediments. Youngest are the products of decay and degradation with the concentration of manganese oxide in the rocks of both groups. The oldest occurrences are in argillaceous and siliceous phyllites and slates, which show only a moderate degree of metamorphism. They belong to a series which also includes mudstones, sandstones, grits, conglomerates and subordinate limestones, with tuffs and lava-flows, largely of basic types. This has been named the Birrim System. Its age is unknown, for no definite fossils have been discovered in it. Since these non-fossiliferous strata at many plaees are of a character which in many parts of the world are suitable for the preservation of fossils, and which contain them, it is assumed that the Gold Coast deposits are pre-Cambrian. These rocks of the Birrim System have normally a northeast-southwest strike, and are folded, but not to any very great degree except in certain belts. From the Eastern Province of the Gold Coast they may be traversed diagonally across their strike for upwards of 600 miles, to the extreme northwestern corner of the Northern Territories. Thence they probably extend much farther into French territory.

Jan 1, 1927

By Walter Lawson

THE first plans were made in 1930 for the mining by open-pit methods of the low-grade disseminated ore body now known as the Morenci open pit. It was not until 1937, however, that final plans were completed and the decision reached to go ahead with the actual development. Many advances were made in open-pit mining equipment during that period of seven years, therefore the ways and means of attack actually used were very different from those originally contemplated. Diesel-operated bulldozers, big trucks, full-revolving electric shovels and electric churn drills constitute the major equipment finally purchased for this modern stripping operation. Neither the bulldozers nor the big trucks were considered in the early operating plans, for at that time bulldozers had not, been used in mining operations and the trucks as yet were undesigned. The full-revolving shovel and the churn drills were not new developments in open-pit equipment, but both had undergone remarkable manufacturing transition, emerging far more efficient and far more dependable than their predecessors. Even the ordinary drilling steel had been fundamentally changed. It was now threaded so that the dulled cutting bits could be detached and replaced, thus eliminating the costly transportation of long bars to the drill shop for resharpening. The decision to use trucks in the preliminary stripping operations was based on the desirability of this type of transportation to economi-cally prepare the pit for rail haulage, coupled with the success that the contractors had had with them on other big excavation jobs. There are at present no plans for the use of trucks beyond the preliminary work, inasmuch as rail haulage will give lower costs after roadbeds and benches are once established.

Jan 1, 1938

By Frederick T. Williams

THE purpose of this paper is to discuss the relative merits of the large 31/8 in. machine and the small 21/4-in. tappett machine in driving development-headings ; and although the . data here presented were obtained from cross-cut headings alone, experience has shown that the results are equally true in drifting, raising and winning. Recently we drove two parallel cross-cuts through the same formation, using a 3k-in. machine at the breast of one cross-cut., and a 2k-in. machine of the same make at the breast of the other. The results of this work afforded an ideal comparison, since in both cases the headings were advanced through rock practically of the same hardness and breaking-properties ; the amount of sludging was equal, and there was no difference in the condition of the steel or the machines, in the air-pressure or in the experience of the operating-crews. Some operators in the Cripple Creek district contend that there is ground which cannot be handled with the small machine, the holes being too small to contain enough powder to pull the ground, etc. The results obtained in working the property of the Portland Gold Mining Co., however, show that the ground worked by them does not fall in this class. During a period of two years there have been driven, with the small machine, 4 miles and 308 ft. of development-headings, through a diversity of ground, including Pike's Peak granite (a coarsely porphyritic type of granite), highly indurated, andesitic or phonolytic breccia, true massive andesite, trachytic phonolyte, tuffas, and along dikes of decomposed basalt and hard phonolyte; in every instance a satisfactory record was made. The headings here described were driven through highly indurated, andesitic breccia, having a hardness of from 5.2 to 7.2

Mar 1, 1906

Report of the Secretary TO THE BOARD OF DIRECTORS AND THE MEMBERS OF THE AMERICAN INSTI¬TUTE OF MINING AND METALLURGICAL ENGINEERS GENTLEMEN As will be shown by the special reports of the Finance, Membership, Library, Papers and Publications, Increase of Membership, and other standing Committees, together with that of the Treasurer, the year 1927 was one in which the Institute made very satisfactory progress in a number of directions. In total numbers the membership is no larger but in revenue from dues there has been a marked increase. This has been due to the promotion to full membership of Junior Associates of earlier years, to the larger proportion that come in originally as members rather than juniors, and to the keener interest in the work of the Institute reflected in prompter payment of dues. The latter is important, since experience shows that of those who fall behind a large number must ultimately be dropped for non-payment. Conditions in the mining in¬dustries have been healthy though not booming. It has been much easier for members to find employment and meet their financial obligations but there has not been that flow of young men into mining, and hence in part into the Institute, that characterized certain earlier years. Rather the tendency toward centralization and larger industrial units has re¬stricted the number, though not the scope, of opportunities for technical men in the mineral industries. The Institute is constantly receiving resignations from members crowded out of mining into other lines of activity. On the other hand, those who remain in mining and metal¬lurgy have a greatly increased necessity for information and contacts with technology. A few years ago many superintendents and most foremen were non-technical men. Today the reverse rule obtains and shift bosses and men who occupy even lower positions in industrial units are called upon to know and to apply such an amount of technical knowl¬edge that graduate engineers are the rule rather than the exception. The curious situation has obtained that with a much smaller enrollment of students in the schools of mining and metallurgy there has been at times an actual shortage of young engineers for beginners' jobs. The young men retort that the conditions of employment and pay offered in mining are not equal to those in other lines and, while it is undoubtedly true that the young engineer beginning in mining is able to start under conditions markedly better as to pay, living, and responsibility than did the men who are now leaders, they are required to know much more and have usually spent more in time and money to qualify for their jobs. The whole matter is one which warrants much more attention than has been given to it. For the Institute it is important since the young men

Jan 1, 1923

By Robert D. Pehlke, Arden L. Bement

A mass transfer coefficient for the removal of hydrogen from liquid aluminum by inert flush degassing has been determined experimentally at 700°C. A mathematical model has been derived, assuming transport control, which adequately describes the experimental data. The removal of hydrogen is shown to increase with decreasing bubble size, and with increasing flow of flushing gas. The presence of hydrogen in liquid metals in amounts which exceed the solid solubility at one atmosphere hydrogen pressure is highly undesirable, causing unsound ingots or castings, or resulting in difficulties during further fabrication. The removal of hydrogen from liquid metals can be accomplished by several methods, the principal two being vacuum treating and inert flush degassing. The design of a process involving either of these techniques is based on the mass transfer coefficient for hydrogen between the liquid metal and a hydrogen-dilute gas phase. In an effort to extend our knowledge in this area, an investigation of the rate of removal of hydrogen from liquid metals by inert gas flushing was undertaken. In view of the difficulties encountered with gas porosity in the casting of aluminum and aluminum alloys, and because of certain experimental advantages, liquid aluminum was selected for the study. PREVIOUS INVESTIGATIONS The removal of gases from liquid metals, particularly steel, has received considerable attention in recent years, The first definitive work of a theoretical nature was presented by Geller1 who considered the case where equilibrium exists between purging gases and metal bath during flushing, and also deviations from this ideal case. Hulme2 has surveyed a number of experimental studies and discussed some of the practical limitations of removing dissolved gases from molten metals. More recently a number of studies have been reported on degassing of steel melts by flushing with an inert gas.3'4 Considerable work has also been reported on aqueous and organic liquid-gas systems, and an excellent summary prepared by Hovis.5 The treatment of liquid aluminum by a flushing gas to remove dissolved hydrogen has been known for several decades.6 A number of gases have been used for this purpose, including nitrogen, argon, and chlorine, or mixtures of these gases. Tikkanen and Erkko7 have studied the relative density changes of aluminum castings poured from melts degassed with chlorine, nitrogen, and mixtures of the two gases. Their

Jan 1, 1962

By P. R. Gage, R. W. Bartlett

At high temperatues and reduced oxygen pressuves, molybdenum silicicles oxidize to form SiO(g) vathev than a passivating SiO2 film. This is a sevious problem for low-pressure applications of sili-cide-coated rejvactory tnetals. As oxiclalion pvoceeds, the higher oxidntion potential of silicon initially suppresses oxidation of molybdenum and silicon is depleted near the surface. Eventually, silicon depletion causes secondary passivation (SiO2) mid an active to passiue transition in oxidntion behavior at moderately low pressures. At very low pressures, silicon depletion continues until steady-state oxidation of both silicon and rnolyhdenum can proceed at rates propovtional to their initial stoicliiorrzetvies. Ohsel-vations of 'oxidatiou-rate belzcriliov at temperatures from 1101° to 1700°C and oxygen pressures from 10-7 to 1 at in were made using thermogravimetn'c, X-ray diffraction, and elect?*on-rtric?ro/,vobe techniqrres. The experimental results are in good agreement with calculated lirnits for the various types of behavior that were based on tlievtnochernicnl atzd dffusion rate data for the Mo-Si system. A protective oxide film normally forms during the oxidation of elemental silicon. However, at elevated temperatures and reduced pressures this film is not present and oxidation is rapid. wagnerl has shown that this behavior occurs because SiO(g) is more stable than SiO2. The behavior of the silicides at high temperatures is similar but more complicated. Molybdenum and several silicide compounds are involved and the chemical activity of silicon, or the equivalent silicon vapor pressure, can vary considerably in these phases. Also, diffusion in the silicides resulting from reactions in which a higher silicide is reduced to a lower silicide, or molybdenum containing dissolved silicon, must be considered. EXPERIMENTAL AND ANALYTICAL METHODS Isothermal oxidation experiments were conducted using hot-pressed MoSi2 and Mo5Si3 wafers. Each experiment was conducted at a fixed oxygen pressure by controlling the flow of oxygen in and out of the furnace chamber. Most of the experiments were conducted in a molybdenum-wound tube furnace. Special construction features, including use of a high-purity dense A12O3 refractory tube, permitted operation in high vacuum to 1500°C. Higher temperatures could be obtained at higher working pressures and with a sacrifice of tube lifetime. Temperature was measured with three Pt 6 pct Rh/Pt 30 pct Rh thermocouples and controlled with a proportional controller. Weight changes were monitored with a quartz spring balance. The few experiments, at higher temperatures and low pressures, were conducted in a cold wall vacuum chamber using induction heating with direct susceptance of the sample. Because of the variable levitation effect of the induction coil on the sample, weight changes could not be monitored continuously in these experiments. All samples representing both experimental methods were weighed before and after oxidiation and examined with a microscope and analyzed by X-ray diffraction. The analytical treatment assumes equilibrium at interfaces and uses existing thermodynamic data. For convenience, equilibria are expressed as chemical potentials or as vapor pressures of the gases involved. The resulting differences in equilibrium vapor pressure between adjacent interfaces and between the surface and external atmosphere drive diffusion processes in the solid and gas boundary film, respectively. These diffusion processes govern the rate of oxidation. A bibliography of the sources of thermochemical data for the reactions pertinent to the Mo-Si-O system is given in Table I. Reactions are listed with the sources of free-energy data referenced. Since all of these reactions involve one or more gas species, usually oxygen, a plot of the product-gas chemical potential, -RT In Pg, vs absolute temperature for each reaction is given in Fig. 1. These curves can be used to determine equilibrium vapor pressures or to compare the stability of different compounds in the various gases: O2, Si, SiO, and Moo3,. The data of Table I and Fig. 1 were used to determine the analytical results presented in this paper. EXPERIMENTAL RESULTS The weight changes for three MoSi, samples oxidized at 1500°C are plotted against time in Fig. 2. The treatments were identical except for the indicated variance of oxygen pressure and each curve represents one of three characteristic types of behavior that were observed. The upper curve is an example of passive oxidation, which is defined as

Jan 1, 1965

By D. T. Peters, C. R. Cupp

Aging of commercial 18 pct Ni maraging steel and of related binary, ternary, and quaternary alloys has been studied by electrical resistivity, X-ray diffrac-tion, and hardness measurements. The aging process is in three stages: 1) recovery of martensite; 2) two precipitation reactions; 3) formation of nickel- rich austenite. The main objective of this work was to discover the nature of the Co-Mu interaction. Addition of cobalt to the Fe-18 pct Ni-5pct Mo alloy results in acceleration of the pvecipitation reaction by increasing the super-sat~lration 0f molybdenum. The cobalt-containing al- loys show no incubation period for the precipitation reaction, but the alloy without cobalt shows an initial slow reaction. These results are interpreted in terms of precipitation on dislocations. At low aging temperatures, the presence of cobalt leads to the appearance of a second type of precipitate which is a particularly effective hardener. Cobalt was found to retard the formation of austenite. Overaging is a combination of classical overaging and the formation of austenite in the structure. he- activation energy for the precipitation reaction determined from resistivity ,measurements is 42.8 kcal per mole and the growth of the precipitate is found to obey at law at high tenzperatures and a tU3 law at low temperatures. HE mechanism of strengthening of the 18 pct Ni maraging steels has been studied extensively since 1962.'-? The strengthening is due to precipitation hardening of the martensitic matrix. The main precipitate is an inter metallic compound involving molybdenum, but there is disagreement about its identity.

Jan 1, 1967

By C. H. Mathewson, A. U. Seybolt

As is well known, many questions affecting the properties and uses of a metal cannot be answered without careful consideration of the state of purity realized in the various operations of preparation, refining, or special treatment that have brought the product to its final state. The occurrellce of an impurity in minute quantity offers no guarantee that its effect will be inconsiderable because dissolved substances often modify the properties of a metal quite out of proportion to their concentration. In such cases the determination of solid solubility must be accepted as a problem of considerable difficulty, requiring the use of especially purified materials and methods not ordinarily used in the metallurgical laboratory. This aspect of the equilibrium between metals and their oxides is especially important and a search for fundamental data reveals little except conflicting opinion even concerning the systems of common occurrence and interest. Rhines and Mathewson1 in 1934 studied the solubility of oxygen in solid copper by annealing to equilibrium in air and gave reasons for the failure of other methods, notably the ordinary procedure of heat-treatment followed by microscopic examination, to yield reliable results. In this paper, a similar study has been made of the solubility of oxygen in cobalt. The simple theory of this method is outlined below. Conditions of Equilibrium between a Metal and Dissolved Oxide at Different Temperatures and Pressures The general conditions of equilibrium in any system are conveniently summarized in a projection of the triple curves of the P, T, X space

Jan 1, 1935

By A. U. Seybolt, C. H. Mathewson

As is well known, many questions affecting the properties and uses of a metal cannot be answered without careful consideration of the state of purity realized in the various operations of preparation, refining, or special treatment that have brought the product to its final state. The occurrellce of an impurity in minute quantity offers no guarantee that its effect will be inconsiderable because dissolved substances often modify the properties of a metal quite out of proportion to their concentration. In such cases the determination of solid solubility must be accepted as a problem of considerable difficulty, requiring the use of especially purified materials and methods not ordinarily used in the metallurgical laboratory. This aspect of the equilibrium between metals and their oxides is especially important and a search for fundamental data reveals little except conflicting opinion even concerning the systems of common occurrence and interest. Rhines and Mathewson1 in 1934 studied the solubility of oxygen in solid copper by annealing to equilibrium in air and gave reasons for the failure of other methods, notably the ordinary procedure of heat-treatment followed by microscopic examination, to yield reliable results. In this paper, a similar study has been made of the solubility of oxygen in cobalt. The simple theory of this method is outlined below. Conditions of Equilibrium between a Metal and Dissolved Oxide at Different Temperatures and Pressures The general conditions of equilibrium in any system are conveniently summarized in a projection of the triple curves of the P, T, X space

Jan 1, 1935

By Richard H. Jahns

Gem materials, comprising those minerals and closely allied natural substances used for personal adornment, for the fashioning of ornamental objects, or for other decorative purposes, have been valued in human commerce for thousands of years. Amber, jet, natural glasses, and at least 15 mineral species were sought and used by primitive man, and most of the materials in common use today were known well before the time of Christ. Their variety is remarkably great, and the traceable relationships among their respective sources, modes of occurrence, properties, and histories of production, preparation, and valuation are extremely complex. Their uses have been affected by numerous shifts in fashion, and from time to time by superstition, by decrees of church and state, by personal interpretations of religious significance, and by various presumptions concerning medicinal value and influence on human behavior (Ball, 1935, 1950; Kunz, 1913; Pogue, 1915, Whitlock, 1946). Thanks to their durability, portability, and relative scarcity, some gem stones have been employed as media of exchange, and the investment value of the more precious stones has long been recognized and exploited, especially in Asiatic and European countries. Demands for gem materials have stimulated trade among various peoples for centuries, and they also were responsible for much early geographic exploration. During more recent times they have prompted numerous geological studies and a considerable amount of research on the growth and properties of crystals. Apart from decorative uses, some naturally occurring gem materials also are employed directly in numerous fields of industry. Substances that are manufactured for gem or industrial uses are termed synthetic gem materials; most of these correspond in composition and crystal structure to certain minerals found in nature. Imitation materials are those whose use is based upon their resemblance to substances of different composition and greater intrinsic value. Gem stone is a designation commonly restricted to those materials suitable for personal adornment, and the complementary term ornamental stone is applied to the remaining materials not used industrially. This distinction is arbitrary and somewhat inconsistent, owing to numerous geographic differences and historical shifts in end uses. Further, there is a complete gradation between the category of ornamental stones and that of dimension stone. Substances that lose their identity in use are excluded from the gem category; thus a transparent crystal of beryl would not be classified as a gem stone if it were processed as a source of beryllium metal. The adjectives precious and semiprecious have been employed as a means for distinguishing different gem materials on the basis of recognized value. Diamond, emerald, ruby, and sapphire consistently have been regarded as precious stones, and in cut form they commonly are referred to as the noble gems. Opal, pearl, turquoise, and chrysoberyl also have been classed as precious at various times. In recent years, however, it has been increasingly recognized that no satisfactory distinction can be based upon assessed value or any group of specific properties, and now all gem stones normally are referred to as precious. Indeed, the tendency is to extend this term to include many of the so-called ornamental stones, and the designation semi- precious has been essentially discontinued. Unlike most mineral commodities of economic value, gem materials are little altered in processing for end uses. Some stones are used in essentially their natural form, and most are reshaped and polished without significant changes in their fundamental properties. Thus the preparation of gem and ornamental stones is intended chiefly to emphasize or enhance

Jan 1, 1975

CONTENTS PAGE ZAPFFE, CARL.-Manganiferous Iron Ores of the Cuyuna District, Minnesota. Discussed by A. K. Knickerbocker 1 MCCORMACK, C. P.-Economics of the Cuyuna Manganiferous Iron Ores. Dis-cussed by T. L. Joseph, J. Wilbur Van Evera, C. P. Perin, T. T. Read, L. E. Ives 4 READ, T. T.-Probable Error in Blast-furnace Records and Calculations Therefrom. Discussed by C. H. Herty, Jr., T. T. Read, T. L. Joseph, Ralph H. Sweetser 8 SCHWARTZ, H. A. and HIRD, (Mrs.) ANNA NICHOLSON.-Chemical Equilibria During Solidification and Cooling of White Cast Iron. Discussed by N. B. Pilling, Ralph H. Sweetser, H. M. Boylston, Albert Sauveur 10 HERTY, C. H., JR., BELYEA, A. R., BURKHART, E. H., and MILLER, C. C.-Some Factors Affecting the Elimination of Sulfur in the Basic Open-hearth Process. Discussed by Henry D. Hibbard, L. F. Reinartz,. C. H. Herty, Jr., Ancel St. John, A. L. Feild, C. R. Hayward, Ralph H. Sweetser, C. D. King, Haakon Styri, George A. Orrok 12 HIBBARD, HENRY D.-Finishing Melting Temperatures of Simple Ingot Steels. Discussed by Haakon Styri, George V. Luerssen, A. G. Zimermann, A. L. Feild, George A. Orrok, Albert Sauveur, R. F. Harrington, Henry D. Hibbard, I. A. Billiar, William J. Priestley, H. W. Gillett, W. P. Barba, Jerome Strauss, Harry H. Smith, H. LeChatelier, L. F. Reinartz 19 HERTY, C. H., JR., and TRUE, O. S.-The Reaction between Manganese and Iron Sulfide. Discussed by A. L. Field, H. S. Rawdon, C. H. Herty, Jr., T. L. Joseph, Haakon Styri 37 KAMURA, HEIHACHi.-Reduction of Iron Ores by Carbon Monoxide. Discussed by T. L. Joseph, R. Franchot, Ralph H. Sweetser, C. H. Herty, Jr 43 JOSEPH, T. L.-Effect of Sulfur on Blast-furnace Process. Discussed by R. Franchot, C. A. Meissner, T. L. Joseph, C. H. Herty, Jr., Ralph H. Sweetser, I. E. Waechter, F. N. Speller, T. T. Read 45 GOOSTRAY, JOB, HARRINGTON, R. F., and HOSMER, M. A.-Brief History of Metallurgical Practice in Cannon-making with Particular Reference to the Cast-iron Gun. Discussed by A. G. Zimermann, Geo. A. Orrok, Chas. Me-Knight, Jr., F. Brauer 51 Manganiferous Iron Ores of the Cuyuna District, Minnesota Discussion of the paper of CARL ZAPFFE, presented at the New York Meeting, February, 1925, and issued, as Paper No. 1390-I, with MINING AND METALLURGY, December, 1924. A. K. KNICKERBOCKER,* Virginia, Minn. (written discussion).¬The author makes a broad distinction between the "black" ores (the

Jan 6, 1925

By Eric Jette

THE results of an investigation of the ternary system iron-chromium-ilicon were reported in 1936 by the present authors.1 Partly for the sake of theoretical interest, and partly because of the possible commercial importance of these alloys, the present investigation was undertaken to determine the effect of some of the commoner elements likely to occur, deliberately or otherwise, in such alloys if made on a commercial scale. The elements thus added were carbon, nickel or manganese. The alloys studied were, therefore, parts of quaternary systems. This investigation was concerned primarily with the effect of these additional elements on .the alpha-iron phase and the boundary between this phase region and the alpha plus sigma two-phase region. The sigma phase is a ternary solid solution based upon the compound FeCr. The work was performed mainly by X-ray methods, but a number of microscopic examinations were also made and are reported. While isolated alloys in the composition ranges studied may have been discussed in metallurgical publications, no systematic investigation of any assistance to us was found. Of the earlier work, the investigations on the iron-chromium-carbon system and on the chromium carbides by Westgren and his coworkers,2,3 enabled us to identify the carbide phase. Several articles appeared after the present experimental work had been completed. Lucas and Wintrup4 determined the solubility of carbon ill molten iron-chromium-silicon alloys. Tofaute and his coworkers5,6 have made detailed studies of the iron-chromium-carbon system, which will he referred to later.

Jan 1, 1937

By Theo W. Robinson

The evolution of the modern blast-furnace from the embryonic stages of comparatively few years ago, has been the work of wide praetiee and experiment. That much is still to be desired, the experience of every furnace-manager mill testify. Mr. Walsh's paper on "The Irregularities of the Blast-Furnace Process, and a Practical Way to Avoid Them" (Trans., xv., 419), proposes a new solution of the problem of interior lines, and one that has given rise to not a little speculation and controversy. The investigation described in this paper was undertaken to test experimentally the theory of Mr. Walsh as to maximum reducing capacity. Briefly explained, Mr. Walsh's views (outside of his claim for increased efficiency due to having the bosh wholly within the meltingzone) are, that a furnace of contracted stack and throat, on his lines. may equal in product one of considerably greater cubical capacity. The explanation offered for the theoretical greater capacity per cubic foot of his furnace is, that the increased tension of gases caused by passing through the small area mill promote transpiration, thus facilitating reduction and permitting more rapid driving. This alleged relation will appear from a hypothetical case in which a furnace, A, constructed on Mr. Walsh's lines, has but 1/x of the cubical contents of a furnace, B, of modern type; the two being equal in height. In order that A shall have the same capacity as B, both working normally with the same mixture and burden, and

Jan 1, 1889

By Robert Mehl

THE mechanical behavior of metals and alloys is presumably conditioned by two factors; namely, the crystalline symmetry and the interatomic forces. Considerable attention has been given to the first of these factors through the recent advances in X-ray .technique. It is the purpose of the present paper to call attention to the importance of the second of these factors, to point out promising methods of investigation, and to present some pertinent data. Plastic deformation takes place by-slip along atomic planes.1 This slip may be inhibited in a number of ways: by the interatomic forces of cohesion which bind the atoms rigidly in a lattice structure, which in pure metals is usually of high symmetry; by lattice distortion caused by solid ,solution formation or by mechanical strain; by the intercrystalline boundaries where slip is restrained by the non-registration of the atom planes in adjacent crystallites;2 and by the presence of small hard particles which serve to "key" the slip along the atom planes.3 In pure metals, and perhaps also in solid solutions, the atom planes, of easiest slip are those exhibiting the greatest density of atomic population and the greatest interplanar distance4 and apparently can now be predicted from the analysis of the lattices. Concerning the interatornic forces, which resist this slip by holding the atoms firmly together, little is known. Most textbooks on physical metallurgy, following the work of Bot-tone,5 correlate the hardness of the pure metals with the atomic volume;.

Jan 1, 1928

By W. L. Saunders

This paper deals specifically with heading-driving as distinguished from the broader term tunnel-driving. A heading is a pilot or path-finder for the main tunnel. Some headings are complete tunnels in themselves; that is, conditions at times warrant driving a heading the full diameter of the proposed tunnel. A tunnel 10 ft. in diameter might be driven to advantage through a single heading, provided the nature of the material admits, but it usually pays to drive rock tunnels of large diameter through the heading-and-bench system. Much depends upon the material, as in soft ground tunnels of much larger diameter are driven in a single heading. In mines, the tunnels, drifts, cross-cuts, adits, etc., are usually of small diameter, hence the driving of headings applies to completed tunnels in mining-work, except, of course, in cases like drainage-tunnels and main entries leading into coal-mines, where conditions call for tunnels of large diameter, approximating those driven for railway-service. In building aqueducts the tunnels are driven from 6 to 8 ft. in diameter up to 15 or 20 ft., while in railway-service the dimensions vary from 18 to 30 ft. in diameter. There is no department of rock-excavation so difficult as that of heading-driving. This work also belongs to the most expensive class in rock-excavation. A heading is driven directly in the solid. There are no lines of lesser resistance towards which to direct the energy of the blast, but the material must be blown out by main force. The completion of the heading simplifies all the rest of the work of excavation. It is easy, for instance, to enlarge a heading either from above, below or on the sides, by breaking towards the open face through holes approximately at right angles to the axis of the heading; or the enlargement sometimes takes place by holes driven outside of the heading running approximately parallel with it, the rock

Jan 1, 1910

By G. A. Moore, D. W. Williams, C. E. Sims

During the past several years, the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture, and the ductility values can often be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Several types of abnormal loss of duetility can be distinguished, of which those caused by excessive amounts of inclusions of undesirable type and those caused by unsuitable grain size and inget structure are well known. The particular type of abnormal lowered ductility currently under consideration may be distinguished by the fact that the low-temperature aging treatment necessary for its relief is insufficient to cause any visible change in the micro-structure as ordinarily observed. As this aging will in fact eventually occur at room temperature, the phenomenon of present interest may be given the symptomatic definition, ''Temporary Abnormal Low Ductility." Some hundreds of previous investigations, largely qualitative in nature, have established, beyond reasonable doubt, that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, The Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-duetility effects and porosity. The interest of this investigation thus extends to permanent abnormal losses of ductility, such as are caused by the inclusions which sometimes result from special deoxidizing practices and possibly from metallic nitrides, but as these can he distinguished from the temporary effect of hydrogen, they have been excluded from the work reported here except when they

Jan 1, 1949

By C. E. Sims, G. A. Moore, D. W. Williams

During the past several years, the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture, and the ductility values can often be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Several types of abnormal loss of duetility can be distinguished, of which those caused by excessive amounts of inclusions of undesirable type and those caused by unsuitable grain size and inget structure are well known. The particular type of abnormal lowered ductility currently under consideration may be distinguished by the fact that the low-temperature aging treatment necessary for its relief is insufficient to cause any visible change in the micro-structure as ordinarily observed. As this aging will in fact eventually occur at room temperature, the phenomenon of present interest may be given the symptomatic definition, ''Temporary Abnormal Low Ductility." Some hundreds of previous investigations, largely qualitative in nature, have established, beyond reasonable doubt, that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, The Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-duetility effects and porosity. The interest of this investigation thus extends to permanent abnormal losses of ductility, such as are caused by the inclusions which sometimes result from special deoxidizing practices and possibly from metallic nitrides, but as these can he distinguished from the temporary effect of hydrogen, they have been excluded from the work reported here except when they

Jan 1, 1949

By L. L. Davis

The rapid increase in the use of pulvcrulent adsorptive materials in the so-called "contact filtration" process for decolorizing lubricating oils makes it desirable to consider some of the basic principles involved. The commercial methods and types of equipment now used arc fairly well known, having been extensively described in the trade journals. In spite of this very little has been published concerning the factors which must be considered in the selection of a process or of a decolorizing ing material. It is commonly understood that contact filtration more or less closely follows the laws of adsorption. These principles have been thoroughly drscribed by Gurwitsch.' The contacting of neutral mineral oils seems to be adsorptive in character and apparently follows Freundlich's law of adsorption which may be expressed by the formula: X = Color material adsorbed hy the clay. M = Amount of clay used. C = Concentration of color material after equilibrium. A and P = Constants for a given oil and clay. Fig. 1 shows the decolorization curve for a natural, dark colored cylin-der stock when contacted with various quantities of clay, curve R being made with natural Riverside Texas fuller's earth and T being made with an acid-treated clay from Texas. As the Tag-Robinson color is inversely proportional to the depth of color, the reciprocal of these colors ran be assumed to be a funct ion of the concentratlion of coloring matter. The values of and C' can, therefore., br calculated by using the reciprocal Tag-Robinson colors, and when these

Jan 1, 1928

By H. A. Jr. Koch, C. A. Hutchinson

Miscible phase displacement of oil from reservoirs has been emphasized in the past few years. The reason for this emphasis lies in the high oil recovery attainable by this process. Removal of capillary effects in the reservoir leads to recoveries approaching 100 per cent in the area contacted by the miscible phase. The miscible slug process is one means of obtaining a miscible displacement. Here a band or slug of I,PG is injected into the reservoir prior to gas injection. The idea is to maintain the band of LPG "wedged" between the gas and oil phases and thus achieve a miscible phase displacement. A second method lor achieving miscibility is through the injection of a gas which is not miscible with the reservoir fluid but which develops a zone of miscibility in [he reservoir through mass trans-ier with the reservoir oil.' This mass transfer results in either an enrichment of the lean injected gas by intermediates from the oil or an enrichment of the oil by intermediates from a rich injection gas or one that has been enriched on the surface by LPG addition. We are interested here in discussing the process in which miscibility is developed at the displacement front by the evaporation of interrnediatcs from the oil phase into the gas phase. This process "builds up" its own slug of miscible material at the displacement front and therefore does not require the injection of LPG to obtain miscibil-ily. Each process has its own area of applicability. Generally, the high pressure gas process is applicable only with reservoir fluids which con-!ain a high concentration of inter- mediates. If the high pressure gas process is technically feasible at pressures less than 4,500 psi, it is probably more desirable economically than the slug process. The slug process has broad applicability in the shallower reservoirs and with reservoir fluids which contain a relatively low concentration of LPG and natural gasoline constituents. This paper deals with some new concepts of the high pressure gas injection process where it is proposed that flue gas can be substituted for hydrocarbon gas without sacrificing our goal of miscibility. MECHANISM Introduction Considerable effort has been devoted to study of the mechanics ot the high pressure gas injection proc-one generalization result-ing from some of these studies was that the composition of the injected gas is relatively unimportant in establishing the miscibility pressure* for a given reservoir fluid. This generalization is correct for the composition range of gases typically encountered in the field. Two such gases are a gasoline plant tail gas containing 85 per cent methane and 15 per cent ethane, and a field separator gas containing 70 per cent methane and 30 per cent heavier components. The most important factor which sets the miscibility pressure in the operation is the reservoir fluid composition, particularly the concentration of LPG-natural gasoline constituents. The injected gas is the agent by which the LPG-natural gasoline constituents are concentrated at the displacing front to create a miscible displacement. Based on these results, it appeared feasible that some inexpensive gas, such as flue gas, might be substituted for hydrocarbon gas for use in the high pressure gas process. A re-examination of the phase relations of the high pressure gas injection process should clarify the principle behind using flue gas (essentially nitrogen) as an injection gas. Three Component Diagram The phase relations of the high pressure gas injection process have been illustrated by the use of the three component diagrams.'," In Fig. 1 we have arbitrarily represented the multi-component reservoir system by three components; methane, ethane through hexane, and heptanes plus. The solid curve ABC is the phase boundary curve. It represents the locus of compositions which have fixed saturation pressure at a fixed temperature; the lower branch AB shows bubble point compositions, the upper branch BC, the dew point compositions. Point B is the coniposition of the critical mixture at this temperature and pressure. The dashed lines (tie lines) connect vapor and liquid compositions which are in equilibrium. Let us consider Reservoir Fluid D which we wish to displace in 21 miscible manner by gas injection. Let us further restrict the discussion to the case where miscibility between an injection gas and the reservoir fluid at the displacement front is developed by gas enrichment in the reservoir. For this case, any gas whose composition lies between Points C and E on the right side of the three component diagram can be used to give a miscible displacement of Reservoir Fluid D. This is true because the more mobile injected gas moves faster than the displaced oil and is in continuous contact with virgin oil at the displacement front. This leads to a continuing enrichment 01' the gas at the displacement front by evaporation of the C, - C,

By W. O. Philbrook, R. H. Spitzer, F. S. Manning

A generalized mathematical model has been developed to describe the kinetics of gas-solid reactions with special attention given to the hydrogen reduction oj dense spheres of hematite. This reduction process must pvoceed through a sequence of transport and chemical .reaction steps acting in series. Under typical experimental conditions, none oj the individual transport and reaction resistances may be neglected in the development of a physically significant model. A linear vate of thickening oj the product layer, usually taken as evidence of interface-controlled .reuction, may be observed even though transport resistances play a dominant role in the over-all kinetics. The temperature and pressure dependencies of all terms have been carefully evaluated in order to .make fill use oj arailable expe-inzental data in evaluation oj the model. FOR obvious technological reasons, the kinetics of reduction of iron oxides has become the subject of intensive experimental and theoretical investigation during recent years. Continuing efforts to construct mathematical models to describe the kinetics of reaction between a gas stream and a granular bed of solid particles have demonstrated the necessity of a thorough understanding of the reaction kinetics of a single particle within the system as a prerequisite to the construction of physically significant models of complex, reacting systems. This paper presents a critical examination of the transport and chemical-reaction processes involved in single-particle oxide reduction and develops the mathematical expressions necessary to evaluate their importance. Comparison of theoretical predictions with experimental results contributes important new understanding of the complex nature of this process. The reduction process has been studied under a wide range of experimental variables, and it is not surprising that apparent conflicts in observation and interpretation appear in the literature. The interested reader is referred to the reviews of Themelis and auvin"? and Manning and philbrook3 for a description of much of this work. The course of reaction commonly has been followed by measuring the oxygen weight loss from the particle as a function of time. A number of authors have suc- cessfully correlated their data in terms of a model which assumes that the reduction process is controlled by the rate of reaction at a single, sharply defined, advancing interface. According to this model, the interface will advance linearly with time. A mathematical model for gaseous reduction in a packed bed developed by the present authors in an earlier paper4 recognized that reduction must proceed through the series hematite (Fe203), magnetite (Fe30,), wiistite (Fe,O), and finally metallic iron. The reduction scheme permitted a stepwise topochemical reduction of the individual particles to metal or to the lowest oxide thermodynamically possible for the local gas composition in the bed. The limiting situations of theoretically dense and very porous oxide structures were considered. On the basis of available experimental evidence, the simplifying assumption was made in each case that all product layers would thicken linearly with time. A generalized single-particle model has now been developed to determine the significance of transport resistances in the product layers and in the gas film surrounding the particle. The analysis shows that the interplay of transport and chemical resistances is such that an apparently linearly advancing interface may be observed despite the fact that the reaction may be under significant transport control. Attention thus far has been focused on the development of a model for the topochemical behavior of dense spheres of hematite in atmospheres capable of reducing them completely to metal. The formation of successive product layers of iron, Fe,O, and Fe304 is assumed to follow the mechanism originally described by dstrijm.' All oxygen removal from the core occurs at the iron/Fe,O interface, intermediate oxide layers being propagated by sol id-state diffusion without change in the oxygen density of the core. Since fractional reduction is operationally defined in terms of oxygen weight loss, the kinetics of the over-all reduction of FeZ03 to iron is properly studied in terms of the gas-solid reaction occurring at the iron-wiistite interface. The fractional reduction of a partially reduced oxide sphere is given by: here refers to the radial position of the iron/Fe,O interface. This model is not universally applicable because, as explained in the earlier paper,4 a consideration of porous particles or of dense particles in atmospheres not capable of reducing wiistite must allow for the possibility of gaseous reduction at interfaces other than the one between iron and Fe,O. However, evidence that certain hematite specimens actually do follow the dense-pellet mechanism developed here is provided by the data of cewan' and of Bogdandy and

Jan 1, 1967