Search Documents

By H. S. McQueen

THE central Ozark region of Missouri has inter-ested geologists and mining engineers for many years. Of particular interest are the mineralized sink-hole type deposits, some of which have produced large quantities of iron ore. Deposits of coal are also known in this part of the State, and in mode of occur-rence are similar to the iron ore deposits. Occurring in the same general area, and often associated with coal, are deposits of high-grade non-plastic flint fire clay, and high alumina or diaspore clay. At present these clays are the most important materials being mined from the sink-hole type deposits. Deposits of high-grade flint fire clay have been known to occur in this region for many years, the Kelley pit near Rolla, Phelps County, being discovered in drilling for iron ore shortly after the close of the Civil War. Mining operations had disclosed at an early date masses of rough, open-textured "sandy" clay associated with the flint fire clay. Some of the hard flint clay also con-tained rounded shot-like particles of "sand." Both types of clay were considered of inferior grade and unsuited to the manufacture of fire brick. These clays were discarded in mining as value-less, in some instances being used for road metal. Some knowledge of the high alumina content of this sandy material had been obtained by 1908 1, and by 1917 the high alumina content was gen- erally known, and commercial shipments of what is now called diaspore clay were being made. These deposits of diaspore clay associated with flint fire clay form the only known deposits of commercial importance in North America. The production of diaspore and flint fire clay at present exceeds that of any former year. Statistics covering the production and value of the former were not collected prior to 1922, and the figures given below do not cover the tonnage of clay mined by companies and used in their own plants, so that the total produc-tion probably is much larger than that indicated. The figures were collected by the U. S. Geological Survey and the U. S. Bureau of Mines in cooperation with the Missouri Bureau of Geology and Mines.

Jan 6, 1928

By G. R. St. Pierre, L. M. Adelsberg, R. Speiser

The rate of scale fot'~I~ti0n on tantalum held in H20-Hz-Ar gns mixtures at temperatures between 840" and 1250°C is related to gas composition and ternpevature. It is found that water vapor partial pressure determines the oxidation rate at a given temperature and that the oxygen potential as fixed by the water vapor to hydrogen ratio Ins no significant effect on the oxidation rate. The Ta205 scale formed during oxidation is composed of an inner lattice-dijf~ision barrier and an outer layer of- cracked/porous oxide 1 HE oxidation of tantalum at temperatures less than 800°C is characterized by solution of oxygen into the metal,'-' the formation and growth of suboxides into the metal,')2~10-15 and the delayed nucleation of the highest oxide, Above 800°C, Ta205 is found to nucleate rapidly10, 11, 15, 16 except at low oxygen pressures:15 however, there is uncertainty regarding which does not retard the oxidation process. For each gas con~position and temperature investigated, the oxidatioz rate becomes constant after a short adjustment period. It is shozm that a constant oxidation rate nzay pre~?ail even though the tlzickness of the inner lattice-dijjitsion layer of Ta205 is clanging. TFze initial czcrz!ature of the typical 'Paralinear" oxidation curve may result froprz causes other than an increasing thickness of tlze inner protective layer. the detailed mechanisms of the high-temperature oxidation. Peterson, Fassell, and wadsworth17 observed linear oxidation behavior for tantalum in oxygen at temperatures between 600" and 1000°C. They reported that equilibrium adsorption of 0, occurs on a surface prior to the rate-deter mining step of the reaction. Cowgill and stringer1' confirmed the observations of Peterson and his coworkers. They stated that the rate-determining step of the reaction could be either the incorporation of adsorbed oxygen into the anion lattice or the dissociation of 0, at the gas-oxide interface. The relative rates of the two surface reactions were proposed to be dependent upon the reaction temperature and the oxygen pressure. stringerlo subsequently reported that the reaction surface is located somewhere

Jan 1, 1968

By M. J. Sinnott, J. C. Tobin

A technique for collecting and analyzing the small quantities of gases desorbed on heating metal powders has been developed. The gases collected from copper powders of various types of manufacture have been analyzed and found to contain H2O, CO2, and SO2. The quantities of gas evolved vary from 0.05 to 1.0 milliliter, under standard con-ditons of temperature and pressure, per gram of powder. The source of the gas has been traced to surface films on the powder. IN the powder-metal industry it is recognized that the presence of gases in the powders affects the processing and resulting properties of the sintered product. Several sources for these gases are possible; namely, chemical reactions with the sintering atmospheres, inclusion. of gases during compacting, dissolved gases in the metal powder, and sorbed gases on the metal-,powder surfaces.1, 2, 3 Since the quantities of the gases are relatively small, no direct attempt has been made to collect and analyze them nor to isolate their source. The work that has been done has been concerned with the dimensional stability of the product., its porosity, density, or mechanical and physical properties. Conclusions are drawn on the basis of studies of this type as to the probable effect of gases on these properties. 4, 5, 0 In the present investigation an attempt has been made to obtain quantitative data on the analysis and quantities of gases associated with copper powders manufactured in different ways. Apparatus was constructed to collect gases evolved from loosely packed powder samples on heating to various temperatures under a reduced pressure of helium. The powders were outgassed thoroughly in a vacuum prior to starting the collection operation in order to eliminate mechanically entrapped gases and to prevent the possible reaction of the powder with these gases. Experimental Procedures Materials—The major portion of the investigation was carried out on a single heat of water-atomized, oxygen-free, high-conductivity copper. A relatively coarse fraction of this powder, 20 to 100 mesh, was tested as a mixed powder and as various graded size fractions. The microstructure of this powder showed equiaxed grains and was clean and free from oxides and oxide eutectic. The particle size, as determined

Jan 1, 1959

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1938 are available at Institute headquarters, unless otherwise noted. They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS. TECHNICAL PUBLICATIONS in Classes A-Metal A-Lining, B-Milling and Concen-tration, H-Industrial Minerals, and I-Mining Geology are distributed in MINING TECHNOLOGY, which is issued every other month. Technical Publications in Classes C-Iron and Steel Division, D-Nonferrous Metallurgy and E-Institute of Metals Division are distributed in METALS TECHNOLOGY, which is issued twice quarterly. TECHNICAL PUBLICATIONS ill Class G-Petroleum Division are distributed in PETRO-LEUM TECHNOLOGY, which is issued quarterly. TECHNICAL PUBLICATIONS in Classes F-Coal Division, .l-Mineral Industry Education Division, K-Mining Administra-tion, and L-Geophysical Methods of Exploration are issued as separate pamphlets. All Institute member is entitled to one copy of any TECHNICAL PUBLICATION or CON-TRIBUTION. Copies of TECHNICAL PUBLICATIONS listed have been mailed to members of the Institute according to their registration by classes. CONTRIBUTIONS and other TECHNICAL PUBLICATIONS will he sent upon request. A member may purchase an additional copy of a TECHNICAL PUBLICATION or a CONTRIBUTION at one cent. a page; in minimum charge, 256. If the TECHNICAL PUBLICATION has been published in METALS TECHNOLOGY, MINING TECHNOLOGY or PETROLEUM TECHNOLOGY, the number of either magazine containing it will be supplied at the sae cent a page (minimum charge, 25¢) rate for the particular TECHNICAL PUBLICATION requested. Nonmembers may purchase any CONTRIBUTION or a TECHNICAL PUBLICATION Of the F, J, K, or L classes at the same rate, butt the nonmember price per copy for METALS TECHNOLOGY, MINING TECHNOLOGY or PETROLEUM TECHNOLOGY is $1. TECHNICAL PUBLICATIONS (Separate pamphlet form), $2 per annum; Canadian and foreign postage 50 cents extra. METALS TECHNOLOGY, $7 per annum; Canadian and foreign postage 50 cents extra (Iron and Steel Division and Institute of Metals Division ferrous and nonferrous papers). MINING TECHNOLOGY, $6 per annum; Canadian and foreign postage 50 cents extra (metal mining, milling and concentration, Industrial Minerals Division, and mining geology papers). PETROLEUM TECHNOLOGY, $4 per annum; Canadian and foreign postage 50 cents extra.

Jan 1, 1938

By A. S. Rhea

SALT-WATER disposal in the East Texas field by means of injection into the Woodbine sand is a relatively new procedure. The purpose of this paper is to present what has been accomplished to date in this field, with-out detailed discussion of other means of disposal, such as surface impound-ing for evaporation or release into surface streams. Subsurface disposal of salt water is still in an experimental stage in the East Texas field, and, though water can be injected into the Woodbine sand, the economic problem is not as yet solved. As past experience has been that fields producing from the Woodbine formation produce large quantities of salt water, it was assumed early in development of East Texas that it would be necessary to dispose of a tremendous quantity of salt water in the later periods of production. There has been a gradual increase in the amount of salt water pro-duced in the field, until at present it is about 200,000 bbl. per day from approximately 4400 wells. It is only natural to expect an increase in the number of wells producing water, as well as the amount of water produced in the future, and it has been estimated that if present practices con-tinue the production of salt water may ultimately be as much as 700,-000 bbl. per day. The Woodbine sand is found in the East Texas field at an average depth of 3650 ft. The oil-bearing portion of the sand lies between the depths of 3050 ft. below sea level, on the east edge of the field, and 3320 ft. below sea level on the west, which depth was the estimated original average oil-water contact. The Woodbine sand under the field has the form of a broad tilted wedge pinching out on the eastern side of the field and dipping gently into the East Texas Basin toward the west. The Woodbine sand in the East Texas field has an average porosity of approximately 25 per cent and is highly permeable, the average being about 1300 millidarcys.

Jan 1, 1940

By George Collins

AT the meeting of the Western Division of the American Mining Congress, held in Denver last September, papers were read by F. H. Brownell, a vice-president of the American Smelting and Refining Co. and chairman of its finance committee, and by H. Foster Bain, former director of the United States Bureau of Mines and now secretary of the A. I. M. E.. which dealt thoroughly with certain phases of my sub-ject. These addresses can hardly have failed to awaken serious reflection in all who listened to them; but their implications have apparently not penetrated the con-sciousness of bankers, economists and statesmen, whose business it is, or should be, to prepare for the economic and social changes which must inevitably follow, if the conclusions which I shall outline hereinafter are true. In discussing this subject I wish to disclaim any intention or desire to forecast the course of the metal markets or the immediate prospects of the mining in-dustry. The facts' adduced must inevitably influence the value of metals, the activity and profitableness of mining, and perhaps also the social status of those en-gaged in it. But my forecasts do not refer to this year, next, year, or the year after. The nearest ap-proach to a date on which I will venture is that the relative scarcity of gold may begin to make itself felt in something like ten years from now, but its effect will not culminate for several years thereafter. Scarcity of new gold is likely to be offset, to some extent, by increasing use of currencies based on credit; but unless it is found possible to dispense with the gold standard altogether, this can hardly prevent a great ultimate fall in commodity prices. This fall, moreover, is likely to be more severe in manufactured goods than in what are, popularly termed raw ma-terials; and most of all in those manufactured goods which are susceptible to the greatest degree to cheapen-ing by mass production, and which are least counter-affected by increasing metal prices; by which I mean those in which the cost of metal contained forms a relatively small, element in the total cost of production.

Jan 6, 1927

By John Chipman

IT has been long known that the gas evolved during the boil in the open-hearth furnace is mainly carbon monoxide associated with smaller quantities of other gases. A number of attempts have been made to determine the precise effects of carbon and oxygen content of the bath, and of other factors, such as temperature, upon the evolution of carbon monoxide. In his investigation of the carbon-iron oxide product in liquid steel, Herty1 showed that the value of this product at equilibrium could be approximated by plotting the value of the product observed in open-hearth reactions against rate of carbon elimination, and extrapolating to zero rate. The results of this study showed a slight but definite effect of temperature upon the carbon-iron oxide reaction. Experimental studies of the evolution of gases from rimming-steel ingots have not yet attained the degree of precision necessary for an exact understanding of the effects of pouring temperature, carbon content, and iron oxide in the metal upon the composition of these gases. Klinger2 showed that the gas consists mainly of carbon monoxide, and that con-siderable variation in its composition occurs during the solidification of the ingot. In order that these variations may be understood in their proper relationship to the progress of solidification of the ingot and the segrega-tion that accompanies solidification, it is essential to have a knowledge of the condition of equilibrium in the several chemical reactions by which the gases are being formed. It is also necessary to understand the effects of temperature upon the equilibria, and further, to know the manner in which the temperature of the liquid metal within the ingot changes as the skin of the ingot is being built up. The reactions in which we will be chiefly interested are those involving in the one case the oxides of carbon, and in the other case steam and hydrogen, with iron oxide and carbon in the liquid metal. The reactions as they occur in unalloyed liquid iron, and their respective equilibrium constants are written as follows:

Jan 1, 1937

By John A. Church

When, in 1879,I examined the mines of the Tombstone Mill and Mining Company, at Tombstone, Arizona, I found a bed of tailings containing 12,000 tons, which had a value of 9 to 12 ounces of silver per ton and some gold. The ore had been amalgamated in pans, in which each charge had been ground for four hours, having been pre viously stamped through rough-punched screens, which gave a pro duct varying from 1-100th to 1-20th of an inch, according to the state of wear of the screen. It was certain that a large proportion of the tailings must be in fine slimes, and the question of recovering their value was difficult. Even now the concentration of slimes is . an unwelcome task, and at that day very little was known about it. Nevertheless, after considering the results of a test by repanning the tailings, I advised the company to concentrate and smelt, although they had to face the difficulty of making a smelting-product from slimes containing only 3 per cent. of lead. Limestone was abundant enough, but no iron suitable for flux was to be had for hundreds of miles. One of the company's claims con tained an argeutiferous manganese-ore, which gave but poor results by amalgamation. This was one reason for recommending smelt ing ; for if manganese would play the part of a precipitant, as iron does, the company could smelt by combining two of its silver ores, without other flux than the small amount of lime that might be needed. At that time no smelter had ventured to trust manga nese as a precipitant, though large quantities of this ore containing silver were bought and used by custom-smelters, who looked upon the manganese solely as a basic flux for silica. I believe that no other furnace has been obliged to trust this metal, and that the man ganese practice of Tombstone remains unique among the records of smelting lead-ores in the shaft-furnace. The bright side of the problem was given by the fact that the mines were shallow and that the enterprise would at least begin with oxidized ores. The tailings contained about 85 per cent. of silica,

Jan 1, 1895

By N. C. Fick, R. L. Rickett

DESPITE the large volume of literature on alloys of iron and silicon,1 there is little published information dealing specifically with the constitution, at various temperatures, of the alloys containing less than 0.10 per cent carbon and from 0.5 to 4.5 per cent silicon that are used extensively in the electrical industry. Because such information was needed by those engaged in the production of these alloys in, sheet and strip form, the constitution was determined of a series of commercial silicon steels containing 0.05 to o.08 per cent carbon and 0.20 to 4.31 per cent silicon, over the temperature range 1300° to 2500°F. These alloys were all from regular production heats and of commercial quality. The results of, the tests are given in Fig. I and for comparison the constitution diagram of iron-silicon alloys with 0.01 to 0.02 per cent carbon, taken from the literature, is also presented. MATERIAL AND PROCEDURE All steels were hot-rolled to a thickness of 0.060 to 0.080 in. and used in this condition. Their chemical compositions, including over-all check analysis, and "center" analysis for carbon and silicon, are given in Table I. The so-called center analysis was determined on samples pickled to remove the outer surface and leave only the center third of the gauge thickness-the portion of the sample on which metallographic ratings were based. In most, but not all, of the alloys, slightly higher carbon was found at the center than when the whole strip was sampled; the two methods of sampling show relatively little difference in silicon. Two of the steels, A and E, contain relatively high phosphorus, while I and K are somewhat higher in manganese than the others. [ ] The procedure consisted essentially of heating specimens (about 1/16 by 3/8 by 3/4 in.), protected from oxidation or change in carbon content, at a temperature in the desired. range and for a selected period, after which they were quenched in iced brine; the degree of transformation that had then occurred was determined by metallographic examination. The soaking periods were selected after preliminary investigation had shown that a con-

Jan 1, 1946

By S. Leber, R. F. Hehemann

Diffusion coefficients for the Cb-W system were measured using couples prepared from poly crystalline, commercially pure metals. The diffusion coefficients, measured in the temperature range between 1700° and 2300°C, decreased exponentially as the tungsten concentration was increased from 0 to 50 at. pct, then decreased abruptly at higher concentrations. A decrease of two orders of magnitude was observed over the entin? compositional range. The diffusion coefficients were in the range defined by the self-difiusion coefficients of the individual elements, indicating their general validity. An activation energy of 60,500 cal per mole was measured for the 20 pct W composition. Such low values, when compared with energies over 100,000 cal per mole for the pure constituent elements, indicated that transport mechanisnzs more rapid than volume diffusion were contributing substantially to inter dijfusion. Difference should, therefore, be expected between these data and the intrinsic diffusion coefficients. These differences should be significant in the kinetics of 'transport phenomena in practical systems. CONSIDERABLE attention has been devoted in recent years to the mechanical behavior and other properties of the refractory metals and their alloys. The Cb-W system has been of special interest as a base for the development of more complex compositions of commercial interest. In spite of the importance of mass transport to all aspects of elevated-temperature behavior, and especially to the production of alloys by powder-metallurgy techniques, little attention has been paid to diffusion in the Cb-W system. Results from a previous study of this system1 appeared to be anomalously high. The present investigation is, therefore, an attempt to obtain more accurate diffusion coefficients in this system. Intrinsic diffusion coefficients, of primary importance from the theoretical viewpoint, can only be obtained accurately from studies utilizing compositional gradients approaching zero. However, many practical problems involve diffusion under significant concentration gradients. The diffusion coefficients determined in this investigation were, therefore, obtained from couples prepared from elemental metals. The data obtained should be of value in the analysis of problems such as homogenization during powder-metallurgy alloying or reactions between base and clad in coated structures. In this vein, the investigation was conducted on poly crystalline materials of commercial purity. PROCEDURE Diffusion couples were prepared by sandwiching a columbium sheet between two sheets of tungsten. The composite was welded around all edges, the tungsten forming a protective can for the columbium. The composite was soaked for 4 min at 1600°C in a hydrogen-atmosphere furnace, quickly forged to 40 pct reduction in thickness, and then rapidly cooled to room tempera-

Jan 1, 1967

By R. H. Hiltz, R. W. Douglass

Large-grain specimens of iodide titanium prepared metal-lographically were stain etched using the technique of New York University as modified by Watertown Arsenal Laboratories. Orientations of grains showing an abnormal response to stain etching were determined by back-reflection X-ray techniques. X-ray results showed that a-titanium grains, oriented such that their basal planes were parallel to the polished surface, have a slower reactivity to stain etching than any other orientation. Grains oriented such that their basal planes made small angles with the polished surface exhibited reaction rates between that of the true basal orientation and the normal rate. As the angle with the surface increases the reactivity increases up to a maximum angle of 14 deg. Basal planes making an angle with the surface of greater than 14 deg show normal reactivity to stain etching. These data, plus work on polycrystalline specimens, indicate that the oxidation rate of titanium might be reduced by correct alignment of crystal planes. ThE earliest observed phenomenon in the micrography of titanium was the occurrence of a grains which exhibited no birefringency. Even though a titanium possesses a hexagonal-close-packed structure and should be optically anisotropic, it can appear optically isotropic, when the crystal is so oriented that its intersection with the polished surface is perpendicular to the axis of symmetry. During the develoment of color staining techniques for titanium: it was noted that the a phase did not stain uniformly. Staining of specimens of commercially pure titanium resulted in a micro-structure of blue-colored grains, among which were randomly oriented a few grains exhibiting colors between the initial yellow and the final blue color. Under polarized light, these off-colored grains appeared to be optically isotropic. More intense study with polarized light, however, showed only the yellow grains to be isotropic. The intermediate colored grains exhibited weak birefringency, which at first glance is not detectable due to the strong birefringency of the surrounding structure. Aminoff2 and Straumanis3 have previously shown that in zinc the basal orientation is less reactive than other orientations. Leidheiser4 showed the same thing to be true for the hexagonal-close -packed configuration of cobalt. Thus, it would appear that the basal-plane orientation is responsible for the abnormality in stained titanium. Later work by Leidheiser5 on cobalt has shown that other planes besides the basal plane exhibited reaction rates slower than the normal rate. Reported planes were the (100), the (1011) and several planes making small angles with the basal plane. The last observance appears not to be due to the reactivity of the reported plane but due to the reactivity of the basal plane which is very close to being parallel to the surface. There are, then, two possible explanations for the range of colors observed in stain-etched a titanium. Since extensive research on the effect of orientation on surface reaction has failed to provide any definite trend, these two explanations are not adequate in themselves. Planes showing the retarded reactivity differ not only for different crystal structures but for metals of the same crystal structure and even for different reactions of the same metal. Tragert,6 Leidheiser,7 Tammann,6 and wagner9 have shown copper to exhibit retarded reactivity on the (111) plane. However, Leidheiser10 has shown that under other conditions the retarded reactivity of copper is associated with the (100)

Jan 1, 1960

By R. D. Reiswig, J. M. Dickinson

The 0s-Ir equilibrium diagram was determined. The diagram is of the simple peritectic type, with a peritectic temperature of about 2660°C. The solid miscibility gap is narrower than previously reported, the nearly vertical solvus lines occurring at about 42 and 63 wt pct 0s. Widmanstaetten figures resembling martensite in some of the two-phase alloys account for a previously suspected transformation. In view of the long history of use of such alloys, it is surprising that the 0s-Ir equilibrium diagram has not yet been completely determined. The boundaries of the miscibility gap in this system have been estimated to be between 24 and 39 wt pct 0s and 79 and 100 wt pct OS. It has been predicted3 that alloys of ruthenium, osmium, and rhenium with the fcc platinum metals should solidify peritectically in their two-phase regions. The metallographic examination of natural osmiridium alloys has been said4 to indicate, by the presence of a martensitic structure, the existence of a transformation or a phase separation. On the basis of superconducting transition temperature measurements, a 70 at. pct 0s alloy was found5 to be two-phase prior to annealing. EXPERIMENTAL The elemental components used in this work were obtained from several suppliers as sponge. The purities, stated by each supplier to be in excess of 99.8 pct, were confirmed in each case by a semiquantitative spectrographic analysis. The pure components were premelted in an inert-gas tungsten arc furnace with the evolution of some fume, crushed, and pickled for use as alloy melting stock. Upon arc melting to the final compositions, no fume evolution was observed. Because weight losses of the order of 15 mg or less were observed in preparing alloy buttons weighing 15 g, "synthetic analyses" were used in determining the compositions of the alloys. Alloys used in this investigation contained 15, 20, 33, 40, 42, 43, 45, 50, 55, 60, 63, 64, 66, 70, 79, and 80 wt pct 0s. Heat treatments of the alloy buttons and pieces thereof were performed in a previously described6 tungsten tube furnace under pressures of 105 torr or less. It was found that homogenization treatments on the specimens were essential to remove the severe coring which was present, a 3-hr treatment above 2300°C removing all the metallographi-cally visible evidence of coring. Following the various heat treatments, the specimens were "vacuum-quenched" by melting a tungsten fuse wire and allowing them to drop onto a water-cooled copper plate. In a few instances, specimens were quenched into molten tin for comparison, but no difference was apparent. Vacuum-quenched specimens cooled from 2400°C to below a red heat in less than 60 sec. Typical equilibration times varied from 3 hr above 2300°C to 88 hr near 1100°C. The utilization of successively longer equilibration times and the approach to equilibrium from both directions indicated that the times used were sufficient to give a close approach to true equilibrium. Heat-treatment temperatures were measured with a calibrated Leeds and Northrup optical pyrometer through a 0.120-in. lateral sight hole in the tungsten heater tube. It was known that the assumption of black-body conditions inside the 1-in.-diam by 10-in.-long tube was unwarranted. The empirical results of work with thermocouples and melting

Jan 1, 1964

By W. H. Yarroll

This paper presents a general discussion of the utility of the statistical technique known as multiple correlation, and gives three specific examples of its application. The first demonstrates the most simple form, or straight-line, multiple correlation. The other two demonstrate multiple correlation analysis in best-fitting third-degree parabolas. With the increasing availability of digital computers, the method becomes entirely feasible where heretofore its use was impractical. The advantages of the method are discussed, and curves are presented which were developed by computerizing the regression equations developed in the examples. The method described in this paper is for use with complex systems, and the examples given are complex metallurgical systems. This subject falls under the general classification of cybernetics, which is defined' as "the science of control and communication, in the animal and the machine." Machine, in this case, can include chemical and physical processes which take place within machines and processing equipment of all kinds. The classical approach to scientific investigation has been the construction of simple models and the changing of variables one at a time. This method is wholly inadequate for obtaining useful information from the complex systems of modern technology including many of our flotation and hydrometallurgical processes. Cybernetics offers the method by which complex systems which have been implemented as an art in the past can now be analyzed with all the discipline of a science. Mathematical techniques for achieving multiple correlation analysis have decided advantages over some of the other statistical methods.2-4 Multiple correlation does not require a series of experiments that have been rigidly planned as do many of the other statistical methods. For this reason, it can be used effectively for interpretation of information from op- erating plants, where planned experiments are impractical, as well as for laboratory experiments. First-degree multiple correlation has been used for many years, and was useful, but limited to linear or nearly linear relationships. The technique described in this paper provides a method for analyzing systems which may be non-linear. This particular technique is multiple correlation analysis in best-fitting third-degree parabolas. It is quite possible that lack of reference to the technique has been due to the overwhelming mass of computations it requires even for relatively simple problems. With the advent of computers, however, its use has become entirely feasible. For the benefit of those who may not be familiar with the subject, it might be well to pause at this point to discuss multiple correlation analysis — what it is and what it achieves. To go back to the old familiar fitting of a set of points with a best-fitting straight line by the least squares procedure, it is conceded that this a good method where there is only one independent variable influencing the dependent variable under consideration, and providing that the relationship is linear. In most fields of investigation, however, there are usually a number of factors exerting important influence, and they frequently bear relationships with the dependent variable other than straight line. Under these conditions, it is easy to see how misleading a simple correlation study might be. Multiple correlation can be used for any number of variables. Within the experience of the writer, this technique has been used to establish regression equations for determination of carbon rate, burden permeability, and production rate on iron blast furnaces, production rate on open hearth steel furnaces, life of molds for steel ingots, rolled steel tensile strength and various defects in rolled products, the performance of ore dressing equipment, and optimization of extractive metallurgical process variables. The discovery of mathematical correlation does not prove, per se, true cause-and-effect relationship, but simply establishes a hypothesis. If the regression equation can be used to make successful predictions of what will happen with future arrays of independent variables, then one can feel reasonably assured that true cause-and-effect relationships have been discovered.

Jan 1, 1968

By M. J. Spendlove, H. W. St. Clair

An automatic surface-follower mechanism was used to measure the surface temperature and the rate of evaporation of molten zinc while undergoing distillation at low pressure. At pressures of 50 to 100 microns Hg, the rate of evaporation may be 60 to 80 pct of the theoretical maximum corresponding to the measured temperature. The rate decreases rapidly at pressures above 100 microns Hg, to only 7 pct of the theoretical maximum at 2000 microns Hg. Measured temperature gradients at the surface are in agreement with theoretical gradients calculated from the heat of vaporization, rate of evaporation, and thermal conductivity of molten zinc. THIS paper covers a series of careful measurements of the rate of evaporation of molten zinc at low pressures, undertaken as a part of a general investigation on the separation of metals by distillation.' Preliminary results on the rate of evaporation of zinc were described in a previous publication.' The results of the preliminary study are as follows: 1—The observed rates of evaporation of zinc were as high as 0.60 g per sq cm per min, corresponding to 75 pct of the maximum rate as determined by the temperature of the metal. 2—The evaporation rate was decreased from 0.30 g per sq cm per min at a pressure of 25 microns to only 0.09 g per sq cm per min when the pressure was increased to 5 mm. 3—The temperature of the surface during rapid evaporation may be 35" to 100°C less than the main mass of metal. Observed temperature gradients at the surface are consistent with those calculated from the heat of vaporization and the thermal conductivity of liquid zinc. In the preliminary experiments, the rate of evaporation was determined from the loss in weight of the metal in the crucible during the test. This was compared with the weight of the condensate. Obviously, this method was subject to error because of some uncertainty as to the period of evaporation that should correspond to the loss in weight. Furthermore, this method did not permit taking into account probable variations in the rate of evaporation during the test. A more serious shortcoming was that the temperature at the evaporating surface was not known, so the maximum theoretical rate of evaporation could not be calculated accurately. To improve the precision of rate measurements and to allow accurate measurements of the surface temperature, a refined experimental technique was developed whereby the temperature and position of the surface could be measured accurately. This was done by an automatic surface-follower mechanism that gave a continuous record of the surface temperature and the amount of zinc evaporated. These data permitted an instantaneous determination of the actual rate of evaporation and the surface temperature throughout the test. Pure zinc (99.99 pct Zn) was used in all experiments. Description of Distillation Furnace The details of construction of the distillation furnace are shown in Fig. l. The furnace is enclosed in a large quartz tube open at one end. The open end of the quartz tube is sealed by means of a water-cooled head. The entire enclosure is vacuum tight. The connection between the water-cooled head and the quartz tube is sealed by means of a rubber gasket which fits tightly against the smooth end of the tube. The metal is heated by induced current set up in the molten zinc and the walls of the graphite crucible by means of a water-cooled induction coil outside the quartz tube. High frequency current is passed through the induction coil from a 6 kw mer-

Jan 1, 1952

By C. Scala, F. Bernstein

General expressions are derived relating the streaming potential to the electrochemical potential of a permeable junction separating two electrolytic solutions. By the methods of irreversible thermodynamics, these potentials are related to the flux of mobile species arising from differences in pressure and chemical composition. The flux is conveniently expressed as a transference number, the equivalents of a mobile species transferred through the junction per faraday of electricity. At constant pressure, the flux equation gives the electrochemical potential across the permeable junction. The streaming potential across the junction is obtained by imposing the condition of constant chemical composition. The familiar expression for the borehole SP is shown to be a particular solution of the general flux equation. The derived exprersions were verified in experiments with seven shale samples. Both the theory and experimental data provide additional proof of the presence and magniturle of the streaming potential in shales. INTRODUCTION In the interpretation of electric logs, there has been much concern over the correction to be made to the recorded SP for an electrokinetic or streaming potential originating from the difference in pressure between the mud column and the formation. It was long recognized by M. R. J. Wyllie that such an electrokinetic potential source mas in the mud cake opposite permeable sands.' More recently, M. Gondouin and C. Scala2 showed an additional but opposing electrokinetic source of potential to be in shale beds. Their work was supported by the very extensive and excellent work of Hill and Anderson.3 n the present contribution, the general relationships between the electrochemical potential and the corresponding streaming or electrokinetic potential are examined and clarified. A notable advance towards understanding the relation between the various sources of electrical potential in a borehole has been the application of the now common methods of irreversible thermodynamics to describe the passage of ions and water through charged electrolyte junctions such as in shales.' The advantages of these methods are twofold. Unlike classical thermodynamics, they can be applied to non-equilibrium sys- tems, i.e., systems in which flow takes place, provided the flow processes have reached a steady state. They also permit conventional thermodynamic properties to be related to the steady-state dynamic properties. These methods arc used here specifically to derive expressions relating the potential behavior of shales in terms of ion and water transport. Experimental verification of the expression for the shale streaming potential is given which in turn offers theoretical support to the existence of a streaming potential in shales.' Importantly, the relative contribution of transport parameters to the SP is clarified. The theoretical treatment is essentially that of Lori-mer, Boterenbrood and Hermans3 ut has been extended to derive the general expression for the SP.

By Leendert de Witte, Fred J. Radd

In many areas caring failures can be directly related to electrical currents observed in the casings. It is the thesis of this paper that the observed casing currents are mainly due to electrochemical potentials of the type in evidence on spontaneous potential curves of electrical logs. The general nature of these potentials are discussed and an equivalent circuit is given for current and potential distributions around open holes. The casing forms a short circuit to these potentials and tends to average the effects of local cells. The case of casing corrosion opposite the Dakota water sands in the salt-mud area of Kansas is discussed anil used us a qualitative, illustration of the relation between SP's and casing currents. A method of quantitative derivation of casing current distribution frorn electric log SP curves, using linear transform theory, is described and results are compared with a measured current profile. The effects of hydrogen over-potentials at the cathodic portions of the pipe are considered and some laboratory data are given in support of conclusions regarding the over-1.01tuge.s. INTRODUCTION To date an appreciable amount of work has been done on the measurement of oil well casing currents and on the correlation of the anodic portions of the current profiles with corrosive casing failures. Speculations on the origin of the casing currents have, however, remained rather vague; and although almost every plausible cause has been mentioned, there is to the writers' knowledge no clear-cut expose' on the details of the causes of the corrosive currents in the literature. A study of current surveys and casing failures in the N.W. Burnett field, Ellis County. Kan.. indicated the probability that concentration cell emf's between the Wellington salt section and the relatively fresh waters in the Dakota sands were a major cause of the corrosion currents. A more general concept evolved upon analysis of the severe corrosive conditions in the Pleistocene sands in the Ventura Avenue and San Miguelito fields in California. In this area no major variations in the salt content of the formation waters occur and yet large casing currents are observed. An explanation is found in the fact that the local spontaneous potentials which are set up due to concentration contrast between the drilling fluid and the connate water are short circuited when casing is set. The very conductive path through the casing increases the magnitude of the currents and has the tendency to average local sources over fairly large intervals. Current will flow between the sections that are predominently shaly and the sections that are mostly sandy. At the places where the current leaves the pipe, corrosive attack will occur. This same phenomenon will be present wherever unprotected pipe is set through sections that show large SP kicks on the electric logs over reasonably thick interval~. GENERAL- NATURE OF THE SPONTANEOUS POTENTIALS When a sequence of sedimentary rocks is penetrated by a drill hole filled with a mud which has a different salt concentration from that in the formation waters, various types of electrochemical potentials are established between the formations and different parts of the mud column. Opposite clean sand sections. a simple liquid-liquid junction potential will be observed; while opposite argillaccous formations, a membrane potential, often referred to as shale potential, will be established. The first quantitative analysis of these emf's in terms of liquid junction and membrane potentials is due to Wyllie.1

Jan 1, 1956

By B. M. Larsen, L. S. Darken

SOME years ago we collated all laboratory data then available to us on the distribution at equilibrium of manganese and of sulphur between metal and simple slags, and used the results in setting up an equation, which proved to be in accord with determinations of the distribution ratio of manganese and of sulphur between liquid steel and open-hearth slag, over a wide range of operating conditions. We now present an outline of our calculations and inferences on these two closely related questions, which are of especial importance because of the advisability of conserving manganese wherever possible. In general, our results show that in the open-hearth furnace equilibrium between metal and slag, with respect to both manganese and sulphur, is substantially attained during the finishing period of the heat, or in about a half hour to an hour after any additions were made. This implies that the end result will be identical whether manganese is added as alloy or metal to the liquid steel or as oxide to the slag. The proportion of total manganese retained by the steel is favored: (I) by use of the minimum amount of lime, consistent with other operating limitations, required to give a lime-silica ratio of about 2.4, which usually corresponds to a minimum practical slag volume; (2) by a high concentration in the slag of MnO relative to FeO; (3) by high operating temperature. Absorption of sulphur by the slag from the liquid metal is favored: (I) by large slag volume; (2 by a high concentration of active (or "free") lime and of manganese oxide dis) solved in the slag; (3) by low concentration of silica, iron oxide, and phosphate dissolved in the slag. DISTRIBUTION OF MANGANESE BETWEEN SLAG AND METAL AT EQUILIBRIUM On the basis that the distribution of manganese between liquid steel and slag is controlled by the reaction [FeO + Mn = MnO + Fe [A]slag metal slag metal] the distribution at equilibrium, at a given temperature, is expressed by the equilibrium constant for this reaction, which is defined as [K" aMoO aFeI1 dFec) aMn] where a is the activity of the molecular species denoted by the subscript. The activity of each of the several components, although it is not known precisely, is approximately equal to the concentration of each component expressed as its mol fraction; that is, as the ratio of the number of mols of the given component to the total number of mols of all the molecular species present in the metal or slag, as the case may be. Moreover, since the activity, or concentration, of iron in the liquid metal is in fact substantially constant, the term [afe] may be combined with K" to give a new constant K'. Making these changes,

Jan 1, 1942

By Joseph C. Kieffer

The Duquesne property of the Callahan Zinc-Lead Co. is about 20 miles east of Nogales, in southern Arizona. One mine is near the mill, but most of the mill feed is hauled in by truck from a number of small mines. The same sulphides are found in all the ores, in general, but the amounts vary considerably. All ores contain silver, copper, lead and zinc minerals but one mine ships ore high in silver and lead and low in copper and zinc; while another mine ships ore high in copper and zinc, and low in silver and lead. The common sulphides are galena, carrying most of the silver; chalcopyrite; sphalerite, carrying iron in solid solution; and pyrite, in a gangue consisting of limestone, quartz and garnet. Mineralization is fairly coarse. At the present grind of about 66 per cent minus 200 mesh most of the sulphides are liberated A small amount of chalcopyrite is locked up with the sphalerite and cannot be liberated at an economic grind, and the copper carried into the zinc concentrate with the sphalerite accounts for the comparatively poor recovery of copper in the copper-lead concentrate. Production oF Two Concentrates The milling problem, which was complicated by the extreme variation in the grade of the feed, was first attacked with the idea of producing a silver-copper-lead con- centrate and a zinc concentrate, both with satisfactory grades and recoveries. By February 1941, it was felt that these objectives had been attained, when the grades of the various products and the recoveries were as shown in Table I. A rough outline of the flowsheet and reagents used is as follows: Minus ¾-in. feed to a 7-ft. by 36-in. Hardinge ball mill working in closed circuit with a 36-in. Wemco classifier. The classifier overflow passes to the second cell of an 8-cell bank of No. 18 Special Denver Sub-A flotation machines (volume, 22.5 cu. ft. per cell). A rougher concentrate is removed from the second to the fifth cells inclusive, and returned to the first cell, which is the cleaner. A scavenger concentrate is removed from the sixth, seventh, and eighth cells, and returned to the third cell. Consump-

Jan 1, 1943

By Joseph C. Kieffer

The Duquesne property of the Callahan Zinc-Lead Co. is about 20 miles east of Nogales, in southern Arizona. One mine is near the mill, but most of the mill feed is hauled in by truck from a number of small mines. The same sulphides are found in all the ores, in general, but the amounts vary considerably. All ores contain silver, copper, lead and zinc minerals but one mine ships ore high in silver and lead and low in copper and zinc; while another mine ships ore high in copper and zinc, and low in silver and lead. The common sulphides are galena, carrying most of the silver; chalcopyrite; sphalerite, carrying iron in solid solution; and pyrite, in a gangue consisting of limestone, quartz and garnet. Mineralization is fairly coarse. At the present grind of about 66 per cent minus 200 mesh most of the sulphides are liberated A small amount of chalcopyrite is locked up with the sphalerite and cannot be liberated at an economic grind, and the copper carried into the zinc concentrate with the sphalerite accounts for the comparatively poor recovery of copper in the copper-lead concentrate. Production oF Two Concentrates The milling problem, which was complicated by the extreme variation in the grade of the feed, was first attacked with the idea of producing a silver-copper-lead con- centrate and a zinc concentrate, both with satisfactory grades and recoveries. By February 1941, it was felt that these objectives had been attained, when the grades of the various products and the recoveries were as shown in Table I. A rough outline of the flowsheet and reagents used is as follows: Minus ¾-in. feed to a 7-ft. by 36-in. Hardinge ball mill working in closed circuit with a 36-in. Wemco classifier. The classifier overflow passes to the second cell of an 8-cell bank of No. 18 Special Denver Sub-A flotation machines (volume, 22.5 cu. ft. per cell). A rougher concentrate is removed from the second to the fifth cells inclusive, and returned to the first cell, which is the cleaner. A scavenger concentrate is removed from the sixth, seventh, and eighth cells, and returned to the third cell. Consump-

Jan 1, 1943

By Rossiter Raymond

This regiment, originally known as the First Engineer Reserve, will be remembered as the one recruited in New York City through the efforts of the Joint Military Committee of the National Engineering Societies. It was sent to England in August, 1917, and, after a few clays, forwarded to France and attached for immediate service to the British Expeditionary Force, without any opportunity for further field-training. This circumstance has led in some quarters to the impression that the regiment was one of engineers and mechanics merely, and had never been drilled under arms; whereas, in fact, it had received such instruction at Fort Totten for some time previous to its embarkation. It is true that in the famous affair of the German counter-attack after Byng's victory near Cambrai, the men of the Eleventh Engineers fought with pick-axes and tools, as well as with rifles borrowed from dead or wounded soldiers; but that was because they had left their own arms in camp, while doing the railroad-building work to which they had been detailed. The accomplishment of that work is really more remarkable than the behavior of the men under a German surprise-attack. It was before that counter-attack, and immediately after Byng's advance, that Field-Marshal Haig issued his despatch, announcing that the engineers deserved as much credit for that victory as the infantry, having performed miracles in keeping the railway transportation up to the fighting line. Indeed, the subsequent scrimmage, of which so much has been said, was ?Date possible only by the extraordinary position of the engineers at the very front, instead of in the rear, as might have been expected of them. A letter recently received from an officer of the regiment says: We have only recently been receiving the New York papers of early December, in which our regiment seems to have received much favorable mention. The stories were, in the main, true. Our men behaved themselves creditably, and certain of the officers received special mention for valor. Two of our 2d lieutenants were pro-moted to 1st lieutenant rank by special orders of General Pershing for "gallant con-duct in action," and about four others would have been decorated by the British,

Jan 4, 1918