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ALTHOUGH it might seem more fitting to discuss this subject in the Ninth Book in connection with the smelting of iron where I had thought to treat of it in detail, this process of making steel appears to be almost a branch of the above chapter on iron itself; hence I did not wish to separate these two so far that they might seem to be [18v] different things. Therefore I wish to write of it here and to tell you that steel is nothing other than iron, well purified by means of art and given a more perfect elemental mixture and quality by the great decoction of the fire than it had before. By the attraction of some suitable substances in the things that are added to it, its natural dryness is mollified by a certain amount of moisture and it becomes whiter and more dense so that it seems almost to have been removed from its original nature. Finally, when its pores have been well dilated and softened by the strong fire and the heat has been driven out of them by the violence of the coldness of the

Jan 1, 1942

By G. G. Reed

G.G. Reed, Jr. The authors are to be commended for finding a material for pellets binding that we were unable to uncover during the investigations that led to US Patent No. 3,748,116, "Method for producing metallic iron powder from iron ore concentrate," July 24, 1973, by G.G. Reed, Jr., J.M. Karpinski, and S.V. Fox. This patent concerns a method of processing "super"-concentrates prepared from magnetite or "blue dust" into molding-grade metallic iron powder for use as a bulk commodity, in contrast to current methods which produce small batches that are custom-blended with additives and/or alloys to customer specifications. The one thing we had not found at that time was an organic binder (mineral-matter-free) that would allow induration to produce hardened pellets that would survive SL/RN Direct Reduction. Peridur appears to provide this missing link needed for large scale (200 t/a, or 220,460 stpy) single line plant capacity consistent with a low market price to ensure greatly broadened use of metallic iron powder. I hope that industry will adopt this combination so that metallic iron powder usage can fulfill its potential. ?

Jan 1, 1986

THE good and lofty men of intelligence are constantly discoverers of many beautiful things, because of their kindness or because they are driven by necessity. Either they shorten the method of making them after they have seen them, or they think how they can be increased in power or how they can be used for various effects in addition to the one intended by the inventor. Certainly all the effects described to you in this Tenth Book derive from gunpowder. When so many proper- ties and so much strength were observed in this, it was thought that by enclosing it in some strong thing that had the power to resist it, gunpowder would produce a marvelous effect. And thus they made a tube of bronze or iron [160v] which they closed with a wooden plug. They applied fire, and when they saw how forcefully this plug issued they thought of making one that would come out and strike in order to destroy things. They made an instrument of bronze or of iron and put some powder and a round stone inside, and called it a spingard. Developing then from this,

Jan 1, 1942

The regular activities of the Institute are financed mainly by income derived from members' dues, from advertising in MINING AND METALLURGY, and from the sale of publications to the public. In addition, collateral activities and special projects are financed each year by means of income from endowed funds controlled and administered by the Institute. In the aggregate, the principal sums of these endowments amount to more than $530,000. An active effort is being made to in¬crease the endowment funds of the Institute through a standing committee, of which H. T. Hamilton is chairman, and of which the other members are: W. H. Aldridge, George D. Barron, Cleveland E. Dodge, D. C. Jackling, Henry Krumb and J. V. W. Reynders. This committee feels that there exists a tremendous opportunity for the Institute to be of ever-growing service to the public, to the mineral industries, and to the profession. It welcomes suggestions as to names of men of means who are vitally interested in the mineral industries, and to whom the opportunity to make a contribution or bequest might appeal favorably if presented in the proper light by the committee.

Jan 1, 1944

By AIME

D R. GILLSON, who was born in Evanston, Ill., in 1895, is another one of those geologists who received his early inspiration and foundation in his science from that great teacher at Northwestern University, the late Professor U. S. Grant, and then went on to give his time and interest to Institute affairs-like those other Northwestern men, Arthur Blair, Gilbert Cady, Charlie Behre, Evan Just, Ian Campbell, Clayton Ball, and many others. After serving in the Navy in the first World War as, of all things for a geologist, a commissary officer on a transport, he went on to MIT and took his doctor's degree under Waldemar Lindgren in 1923. He even assisted in mineralogy at Harvard and thus had training under another great teacher, Charles Palache. He taught mineralogy and petrography at MIT from 1923 to 1928. After several summers of field work as an assistant in the U. S. Geological Survey, Dr. Gillson joined the staff of the du Pont company.

Jan 1, 1947

By H. Rumfelt

Surface excavators for mining coal and such non- metallic minerals as quarry stone, gypsum, phosphate and the like have advanced tremendously in the last 50 years, and their advancement has paralleled that of excavators used in the construction industry during the same period. Up to a certain stage, the construction industry led the way with this development and even pioneered in how the equipment was used. Afterwards, however, new mining machinery and related operating techniques progressed along a different path than their construction counterparts because of the different demands of the two industries. The word "stage" as used above quite generally connotes a transition period, possibly of several years' duration, during which mining development followed the construction industry. Later, mining branched out and responded to its own needs. Most readers are familiar with the events which led to the development of the power shovel. The first dredge was recorded as having been used in England in the latter 1700's and was no doubt developed along the lines of some notes written in the late 1400's by Leonardo da Vinci.

Jan 1, 1971

By A. G. Guy

Thermodynamic activity rather than chemical composition is basic to the analysis of diffusion. This is the essential conclusion reached by Darken1-3 and by Birchenall and Mehl.4 If so, it is reasonable to expect that diffusion calculations should be carried out using activities. This paper will illustrate a method of employing activities in analyzing interstitial diffusion. For interstitial diffusion (of carbon in iron and probably generally) the diffusion of the solvent atoms, volume changes, and other such complexities not explicitly provided for in the usual diffusion equations cause a negligible error of the order of 1 pct. Therefore it is relatively easy to test the validity of an analysis based on activities in the instance of interstitial diffusion. The mathematical treatment of the more complex substitutional diffusion could be simplified once the adequacy of the activity method had been established for substitutional diffusion. Thus the present work has the purpose not only of providing a superior analysis of interstitial diffusion but also of indicating a possible approach to the more important question of an adequate treatment of substitutional diffusion. Development of the Diffusion Equation Although activities are convenient quantities to determine experimentally, they are derived from the more fundamental fugacities.9 Possible confusion in using activities can be avoided by basing equations involving their use on the relationship, dP = -D1d/ax dt [I] where, dP = the number of grams of solute crossing one cm2 in the time dt sec. D, = the diffusion constant for use with fugacities; it is assumed to be constant at a given temperature, and has units of secs. f = the fugacity of the solute in the solid solution; the units are those of pressure, dynes per cm2. x = the distance in cm. Eq 1 can be considered to be the basic form of the first Fick Law for one-dimensional diffusion. In order to convert Eq 1 into an equation involving activities, a choice of a standard or reference fugacity, f°, must be made: then. a = f [2] where a is the activity corresponding to the fugacity f. However, the value of a is also determined by the relation, a = a\c [3] where a is the activity coefficient and c is the concentration. For a given value of a (such as a = 1) it is evident that the units used for expressing concentration will affect the numerical value of a corresponding to a given amount of carbon dissolved in y-iron. Since weight per cent concentration is so widely used, this unit will be adopted as the standard in this paper. When the value off given by Eq 2 is substituted in Eq 1, the first Fick Law becomes, dP= -D,f°dl [4] Since D,f° is constant (at a given temperature), the second form of Fick's Law can be obtained in the usual manner, -dt D'f° dx [5] where c' is the concentration in g per cm3. In terms of weight per cent concentration, c, Eq 5 becomes, dc _ 100 d2a Tt = T /f w [6] where p is the density of the solid solution and will be assumed to be constant. In order to simplify Eq6, it is necessary to consider the standard state, f°. Standard states are chosen for convenience. There appears to be one especially convenient choice for the analysis of interstitial diffusion. If the activity coefficient, a, is set equal to unity at infinite dilution of the solute, 100 then — 100D1fl° is approximately equal P to the usual diffusion constant in dilute solutions. This is true since the activity, a, in Eq 6 can be replaced by the concentration, c, with little error in an infinitely dilute solution.* Here f1° is the standard fugacity necessary to achieve this standard state. It is proposed that a diffusion constant Da' be defined, Da1=100/pD1f1° [7] where A is the metal whose diffusion is * The second derivative of a is equal to the second derivative of c in dilute solution only if -da/dr- is. zero. Although theory does not require this condition, in the systems C in Fe, and Zn in Cu, dc is in fact found to be essentially zero.

Jan 1, 1950

By P. L. Hendricks, J. W. Spretnak

The interstitial atom principally responsible for the yield point and strain aging in electron-beam-melted tantalum is identified by analysis of the kinetics of the return of the yield point after an increment of plastic deformation. Two sets of specimens contained two levels of oxygen with very low hydrogen contents and the third set had comparable oxygen and hydrogen contents. The activation energy for the return of the yield point agrees well with that for diffusion of oxygen for the first two sets of specimens. For the third set of specimens, the activation-energy value lies between those for diffusion of hydrogen and for diffusion of oxygen. The advent of the dislocation model of plastic deformation in metals has revitalized interest in the yield point and strain aging in bcc metals containing a certain minimum content of interstitial solute elements. Much theoretical and experimental work has been performed in recent years to elucidate the detailed mechanism of these phenomena. The purpose of this investigation is to attempt to identify the principal interstitial element responsible for the yield-point phenomenon in electron-beam-melted tantalum by analysis of the kinetics of the return of the yield point after an increment of plastic deformation. Some of the earlier theories of the yield-point phenomenon proposed a grain boundary film of iron carbide. Such models could not satisfactorily explain all features of strain aging and the yield-point phenomena. The most widely accepted explanation is that of Cottrell,1 later extended by Cottrell and Bilby.2 Strain aging is ascribed to "locking" of dislocations by interstitial solute "atmospheres". The yield-point phenomenon results when the dislocations are torn away from their atmospheres. The strain-aged condition is re-established after sufficient time to allow the interstitial atoms to diffuse to the dislocation lines and re-establish the locking atmospheres. Clearly, the Cottrell-Bilby model is concerned with the bulk of the grain and does not specifically involve the grain boundary. The recent modification of the Cottrell-Bilby model is a redirection of attention to the role of the grain boundary and the possibility of multiplication of a limited number of free dislocations rather than unlocking all of the dislocations. Theories have been advanced by Hahn3 and conrad4 which are modifications of the Cottrell-Bilby theory. The model proposed by Hahn indicates that, although the possibility of un- locking anchored dislocations is not excluded, it implies that unlocking is not necessarily required to explain yield drop. Locking of dislocations during the aging treatment is a necessary part of the theory; however, it assumes that dislocations once locked remain locked. It is suggested that the yield drop observed is a result of the following factors: 1) the presence of a small number of mobile dislocations initially, 2) rapid dislocation multiplication, 3) the stress dependence of dislocation velocity. In the case of bcc metals, locking is considered to be the means by which dislocations are immobilized. Cold working of the metal results in the generation of larger numbers of new dislocations and the stress dependence of the dislocation velocity accounts for yield drop observed. Conrad' has proposed a model similar to the one just described which applies to strain aging of iron and steel and which logically could be extended to other bcc metals. This model also does not require large-scale unlocking of dislocations. It is proposed that, during initial loading of a specimen below the upper yield stress, a few dislocations are torn free of their Cottrell atmospheres at regions of stress concentrations. With an increasing stress, some multiplication of dislocations occurs by a double cross slip mechanism, thus giving a preyield microstrain. At some critical stress represented by the upper yield stress, sudden profuse multiplication of dislocations occurs, enabling plastic flow to proceed at a lower stress. In this model, microstrain, preyielding, and flow represent the movement of free dislocations. It should be noted that this model also requires the locking of dislocations by interstitial solute atoms for the occurrence of a yield point; however, unlocking of large numbers of dislocations is not required. If it is assumed that the yield point will return when some fraction of free dislocations produced during pre-straining are pinned, the number of solute atoms required to pin unit length of a dislocation line can be calculated when prestrain and reloading are done at the same temperature and strain rate. Since the migration of solute atoms back to the stress fields of dislocation lines is controlled by the diffusion rate of interstitial solute atoms, it is to be expected that the activation energy for strain aging would be identical to the activation energy for diffusion. It would also be expected that the strain aging observed will be controlled by the fastest diffusing species capable of producing locking over the temperature range investigated. The rate of yield-point return has been found to be adequately expressed by an empirical rate equation of the form: rate=Ae-Q/RT [1] where A = constant, Q = activation energy, R = gas constant, and T = absolute temperature. Cottrell and Bilby2 have expressed the number of atoms per unit length of dislocation line which arrive

Jan 1, 1967

Mr. John J. Porter, Chicago Ill. (communication to the Secretary†):—Mr. Baker's account of his experiences with stock-distribution has been particularly interesting to me, as it

Jan 1, 1905

By Alexandre Mitinsky

The theory of elasticity, the science of the strength of materials, and all our calculations regarding engineering structures are based on Hooke's law, that in loaded bodies the deformations are proportional to the load producing them. Without this law it would be impossible to design intelligently engineering structures such as bridges, frames, axles, etc. This being the case, the proportional limit,l that is, the point at which deformation ceases to be proportional to load, is the most important factor in engineering design. Further, the working fiber stress should be fixed in reference to the proportional limit instead of, as is usual, in reference to the ultimate strength. The incorrect use of the ultimate strength instead of the proportional limit in setting the working fiber stress is probably due to two reasons: (1) it is a more delicate operation to measure the proportional limit; (2) it is usually assumed, though incorrectly, that the proportional limit is determined by the ultimate strength. In Germany the poin't at which permanent set first appears is often taken instead of the proportional limit. The two points will coincide if Gerstner's law, that elastic deformations are proportional to the loads producing them both before and after permanent set, is true; and the limit of proportionality and the elastic limit or point of permanent set will both be represented on a stress-strain diagram, by the point at which the line ceases to be a straight line and becomes curved or changes its inclination. It is to be further noted that the difference in definition between proportional limit and elastic limit introduces a difference in methods of determination in the testing laboratory. The German method of determining the elastic limit by alternately loading and unloading the test specimen is a lengthy process and time has in itself a very considerable influence on the results of physical tests.

Jan 1, 1916

By JOHN R. SUMAN

I WOULD like to spend a few minutes describing to you the present condition which exists in the oil industry and then point out some aspects of this deplorable situation in which I think petroleum engineers can be helpful. As you know, the oil business at this time is in a very critical condition, .due to the tremendous potential production in excess of current demand. This is a world-wide condition as well as a national problem, as it is estimated that the surplus production available for the market in foreign countries is of about the same proportion as that existing in the United States. Due to the inability within the United States to hold production within the bounds of demand prices have been slumping for the last four years and at this time have reached the point where the sales value of the average barrel of crude oil in the United States, is far below the cost, of production. In addition to the large amount of potential production available for the market in excess of demand we have in storage in the United States about six hundred fifty millions of barrels 'of oil. Unless something can be done to limit the amount of oil coming onto the market to a point well below the demand, which point will permit the reduction of stocks, it looks as though the 'oil business is facing demoralization.

Jan 1, 1931

By N. A. D. Parlee, I. D. Shah

ThIS reports on some work done on the solubility and diffusivity of oxygen in liquid silver. Solubility. Improvements in the measurement of the solubility of oxygen in silver and silver alloys were made because precise data were needed for calculating diffusion coefficients of oxygen in these alloys. The apparatus and the procedure used were similar to those of Parlee and Sacris.' The main improvement was in the temperature-measuring technique. A MV30 mullite protection tube containing a calibrated Pt-Pt, 10 pct Rh thermocouple was inserted in the reaction tube from the top through a vacuum-tight swage-lok fitting. The protection tube was well-immersed in the liquid silver, which was heated by induction. A Leeds and Northrup potentiometer was used in connection with the thermocouple. All runs reported were made at 1 atm. The temperature range investigated varied from 940" to 1200°C. The ternary point in Ag-0 phase diagram2 is at 939°C and 0.32 wt pct O. This point was reinvestigated using the above-described apparatus and was found to be at 939°C and 0.315 wt pct 0. It was determined by observing the sudden evolution of oxygen at this point while the solubility measurements were made. The point was easily reproducible if precautions were taken to keep the liquid silver essentially in equilibrium with oxygen and to lower the temperature very slowly. All of the results of this new solubility investigation are plotted in Fig. 1. They are represented by the "least-squares" line shown in the figure and the following equation for solubility at po2 = 1 atm: log% O =695.4/T - 1.086 This equation differs only slightly from that proposed by Parlee and sacrisl and that of Diaz, Masson, and Richardson.3 The points of Parlee and Sacris, using an optical pyrometer, are shown for comparison.

Jan 1, 1968

By HOMER L. WILLIAMS

WHILE some of the mining companies have been pumping a small amount of water for some time, it is only in recent years that large quantities of water have been encountered in the Tonopah district. The water appears to be in different zones or belts so that the draining of one property does not necessarily affect the one adjoining. Consequently, each company has its own pumping plant and its own conditions. The companies panes handling the largest amount of water are the Tonopah Extension Mining Co., Halifax Tonopah Mining Co., West Tonopah Consolidated Mining Co., and Great Western Consolidated Mining Co. The Halifax shaft is on the eastern end of the district and the other three properties on the western. The ore-bearing formation occurs at greater depth on -the eastern and western ends, hence the water problem in these properties.

Jan 1, 1921

By H. T. Bowman

FOR more than 80 years the Bessemer process has depended upon the ability, skill, and judgment of the blower, although as early as the 1860's it was recognized that the process would benefit by some type of instrumental control.1 However, instruments with sufficient recording speeds did not exist, so the end-point determination was always dependent upon the blower's eye. This placed an obstacle in the way of precise experimental work, because of the absence of the necessary records and reference points as reported by Work.2 The use of the photocell provided the instantaneous record of the blow that made this experimental work possible and provided more scientific control for the process as discussed by Graham3' A brief description of the progress of the blow will illustrate the recording function of the instrument. The silicon in the iron is being oxidized during the first minutes of the blow, as pointed out by Henning4 in a table showing the order of metalloid elimination. The product of this oxidation is a solid that remains in the converter, so there is virtually no flame during this part of the blow. This low flame luminosity is illustrated by the flame recording shown in Fig. I, where the silicon blow is plainly marked. The dull flame of the silicon blow gradually gives way to the brilliant carbon flame as the increasing quantities of carbon monoxide formed inside the converter burn to dioxide upon contact with the atmosphere above the vessel. When the carbon reaches some low value under 0.20 per cent, there is insufficient monoxide formed to maintain the dioxide flame, so its intensity drops. Throughout the flame drop carbon continues to burn, until at some value around 0.05 per cent an arrest occurs in the recorded drop. This point has been designated as the end point. The period of time from this end point until the vessel is turned upon its side and blowing has stopped has been called the afterblow. This afterblow is used as a measure of the degree of metal oxidation, and uniformity demands that it be controlled within narrow limits. Iron and blowing conditions are likely to change several times during a turn, necessitating corresponding changes in end-point control. It is the purpose of this paper to discuss these changes, the factors that make them necessary, and their bearing upon the quality of steel. CARBON-FEO RELATIONSHIP In the Bessemer process oxidation relationships are precise. Fig. 2 shows a graph of the carbon-FeO relationship. The familiar "bomb-test" method, described by McCutcheon and Rautio,5 was used for obtaining these and all other dissolved FeO values herein reported, all tests being taken from the converter before deoxidation unless otherwise noted. All tests of 0.10 per cent carbon and above were obtained from metal blown for duplexing. McGinley and Woodworth6 reported iron oxide values for blown metal, but their tests were obtained by a different method than were those

Jan 1, 1942

By Nathaniel Arbiter

T. M. Morris (School of Mines and Metallurgy, Rolla, Mo.)—Rate studies promise to help quantify flotation operations. The author's exposition of rate studies is therefore laudable. However his exposition of a second order rate equation rather than a first order rate equation is not convincing. It is important to use the correct equation, otherwise erroneous conclusions may be drawn. The data assembled by the author and plotted according to a second order rate equation can be plotted according to a first order rate equation. As a matter of fact much of the data used reveals that a second order rate equation is not applicable. According to the method used by the author for plotting data, the reciprocal of the slope of the line is the maximum possible recovery. Physically this cannot exceed 100 pct, yet several graphs yield maximum recoveries greater than 100 pct. For example: l—Curve 2, Fig. 1 yields a value of 120 pct; 2—Curve 2, Fig. 2 yields a value of 115 pct; 3—Fig. 7 yields a value of 110 pct. The real test of the graphical method is, as the author points out, whether or not the earliest points agree with a straight line. The second order rate plot does not fulfill this requirement. Fig. 10 shows the data used by the author to obtain Curve 2 in Fig. 1, plotted according to both a second and first order rate equation. Fig. 11 shows the two rate plots made from data published by Ludt and DeWitt.19 In Fig. 10 the first order rate plot gives a very good fit and obeys the boundary condition of passing through the origin. For the second order rate plot a straight line can be drawn through the last three points but the earliest points are not in agreement with this line. The reciprocal of the slope of the straight line gives a value of maximum possible recovery of 112 pct. The maximum possible recovery according to the first order rate plot is 78 pct. In Fig. 11 the first order rate plot again fits all of the points very well and passes through the origin. The second order rate plot shows wide deviation of the earliest point, indicating that the second order rate equation is not applicable. The reason for the fit of data to the second order rate equation during longer flotation times is that R, the cumulative percent recovery, changes slowly toward the end of the flotation operation, so that when t/R is plotted against time, one is, in effect plotting t against t and one would certainly expect a straight line. The author attempts to show that the second order rate equation is correct by citing evidence which shows that recovery is a function of initial concentration. This is a debatable point especially since, in the author's original presentation of this paper at the St. Louis

Jan 1, 1952

By J. Leslie Goodier

The International Law of the Continental Shelf, so far ratified by 35 nations, extends the national boundary of any coastal nation to the edge of the continental shelf, this normally being at a continuous water depth of 200 m. The Law further extends this boundary to include the floor of the deep ocean to any depth that can be mined by advanced mining technology. In effect, proof of mining can constitute proof of ownership of the subaqueous land and the minerals on or below the sea floor. Irrespective of the fact that present technology is too limited to permit mineral exploitation in the high seas-and the law regarding the right to mine appears hazy-the U. S. Treasury Department's Bureau of Customs, has a ruling that would further deter mining operations on the high seas. This law contends that minerals mined on the continental shelf of the United States are actually mined within the continental United States and are free of tariff, but mined products or other articles obtained from the ocean or the sea floor beyond the continental shelf, if brought into this nation, must be considered as imported and are subject to such customs duties as are applicable under the tariff schedules of the United States.

Jan 7, 1968

By AIME AIME

ASIDE from the annual dinner-dance, the two outstanding social events of the Annual Meeting were the dinner- smoker on Monday night and the informal dance on Tuesday night, both of which were held at the Commodore Hotel. Approximately 400 attended the former event, compared with 570 a year ago, and about 250, people were attracted to the dance.

Jan 1, 1933

By Ernest J. Stocking

ENGINEERS are the key men in our war program today. Upon the technical knowledge and skill of the engineer and upon his administrative and executive abilities rests the entire success for the production of vital materials of the war. Naturally the work load of the engineering examining unit of the U. S. Civil Service Commission has increased greatly since our active participation in the war. At present, over 550 separate requests for certification of eligibles are received by the engineering unit per week. These represent more than a fourth of the total requests received for personnel by the Commission's central office at Washington and represent a recruitment work load of three to four times that carried by the whole Commission previous to January 1940. These requests represent a minimum of a thousand vacancies to be filled each week, while an average week will produce, at present, approximately 1400 vacancies and a weekly maximum may approach well over 2000 vacancies.

Jan 1, 1942

By AIME AIME

THE statements quoted below range widely over the field of contact between education and industry. 'Their sources are as indicated. True Education "Education must escape from its traditional warped and narrow views as to what constitutes life and preparation for life. It must train young men and women for vigorous, wholesome development of every important element of personality. It must build physical and mental health. For each student it must inform and discipline thinking in literature, in physical, bio- logical and social sciences, and in philosophy. It must awaken appreciation of beauty.

Jan 1, 1929

Extremes in temperature and weather, along with the highly corrosive nature of acid leach solutions used at open-pit copper mines, necessitates the use of pipeline systems that are both corrosion resistant and impervious to the environment.

Jan 6, 1976