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By M. R. Geer, Franklin T. Davis, H. F. Yancey

COKE with low phosphorus content is required by some of the electrometallurgical and chemical plants recently attracted to the Pacific Northwest by the hydroelectric power available from Bonneville and Grand Coulee dams. Shipping such coke into the area from eastern points involves a high freight charge, and during wartime consumes precious rail and ship-bottom space, so it is highly desirable to produce coke from the coking coals of Washington to meet the requirements of these industries. Although coke has been made from Washington coals since 1884, little has been known about their phosphorus contents or about the extent to which phosphorus could be reduced by cleaning. An investigation was undertaken, therefore, to determine the manner in which phosphorus occurs in the coking coals of Washington and its amenability to removal by ordinary coal-washing methods. PREVIOUS WORK Phosphorus is a deleterious element in coke used for numerous metallurgical processes, including the production of pig iron, yet comparatively little published information is available on the occurrence and elimination of phosphorus in any of the coals of this country. A variation from 0.009 to 0.062 per cent phosphorus in various horizons of the Pittsburgh bed in the Connellsville region of Pennsylania has been reported,1 and a reduction in phosphorus content from 0.020 per cent in the raw coal to 0.018 per cent in the washed coal was obtained in washing coal from the same bed in the Pittsburgh area;2 the latter figures represent average analyses for a year's operation of the washery on about 800,000 tons of coal. A reduction in phosphorus content from 0.018 to 0.011 per cent in washing coal from the Pittsburgh bed at another washery was observed, and the same report provides data on the phosphorus reduction obtained by separating 10 other coals on a bath of 1.35 specific gravity.3 European investigators have been especially active in correlating phosphorus content with petrographic analysis; fusain and durain generally contain the highest percentage of phosphorus, but this relationship is not universal.4 Some of these investigators have found that phosphorus is removed in the coal-washing process,5 but others have observed that the clean coal contained as much or even more phosphorus than the raw coal.6

Jan 1, 1944

By Jack Washburn

The c axis indentations in zinc crystals were shown to undergo 100 pct strain recovery on heating. The mode of deformation and the details of the polygonization and collapse of indentations were found to be consistent with a number of predictions of dislocation theory. IT has been observed that indentations of the type made by Jillson in zinc crystals can, under certain conditions, be macle to shrink in size and even completely disappear on heating the crystal, Fig. 1. The details of the process are interesting in that they afford a simple experimental illustration of several predictions of dislocation theory. The indentations were made as shown in Fig. 2 by dropping a 0.2 g indenter with a hemispherical point on a cleavage face of a. zinc crystal. Such indentations can be made through relatively great thicknesses in the c-axis direction. The material close to the struck surface, where mechanical twinning and complex distortion occurred, was removed by cleavage. The remaining crystal, which was about 1 cm thick, contained a dent that was accurately round and almost the same size on both top and bottom surfaces. The indentation had the form of a flat cone of half angle approximately 89°, having a rounded apex and a rounded intersection with the unde-formed part of the crystal. The mode of deformation was primarily slip on the three equivalent systems in the basal plane. Six types of dislocation loop (plus and minus in each of the three directions) as shown in Fig. 3 are required by the geometry of the indentation. The maximum shear strain in the radial direction amounted to approximately 2.5 pct. Slip was distributed in the usual, microscopically nonuniform, manner among the possible parallel slip planes. When an indentation was made close to a (2110) surface, three separate sets of interpenetrating slip bands appeared as shown schematically in Fig. 3. A small biaxial tension strain in the plane of (0001) is also a geometrical necessity for the formation of an indentation. If the sides of the dent are tilted l° with respect to the undeformed surrounding crystal, and the surround-

Jan 1, 1957

By M. M. Wong, D. E. Couch, G. M. Martinez

The Bureau of Mines electrowon hafnium metal with an average oxygen content of' 150 ppm at 700°C from an electrolyte containing 27 wt pct LiCl, 62 wt pct RbCl, and 11 wt pct HfC14. The average anode and cathode current efficiencies were 90 pct at anode and initial cathode current densities of 86 amp per sq ft. Haf-nium metal with an average oxygen content of 440 ppm was electrowon at 800oC from an electrolyte containing 90 wt pct KC1 and 10 wt pct HfCl4. The average anode and cathode current efficiencies were similar to those obtained in the LiCL-RbCl-HfCl, electrolyte. The chlorine gas given off at the graphite anode was vented through either a silica or a graphite tube to prevent cell corrosion. THE current method for the commercial production of high-purity hafnium is the thermal decomposition of Hfl4.1 The iodide method is not adaptable to continuous process techniques. Nettle, Hiegel, and Baker2 studied the electrorefining of hafnium from hafnium sponge containing 800 ppm oxygen. They failed to obtain hafnium with 600 ppm oxygen in their initial deposits and obtained AEC specification for oxygen only after 75 pct of the soluble hafnium had been removed from the electrolyte. Calculations using their data indicated this was approximately 4 lb of hafnium. The electrolyte was then used to produce approximately 3 lb of hafnium with a low oxygen content. However, no data are shown concerning the amount of anode material initially used or what percent of it was dissolved, therefore, results are not suitable for evaluation of a continuous operation. In general, it was not possible to consistently obtain low oxygen content metal with the electrolytes described by Nettle, Hiegel, and Baker. Wong, Hiegel, and Martinez3 investigated the electrorefining process for hafnium and showed that even by strict control of electrolyte composition only relatively low oxygen reduction could be obtained. The oxygen contained in the hafnium anode material tended to transfer to the cathode deposit and only a limited purification was possible. Both the "iodide" and the "electrorefining" processes depend upon hafnium sponge as a starting material. The sponge is normally produced by magnesium reduction of HfC14 ' and does not meet AEC specifications for hafnium metal. Since only 30 pct of the anode feed could be utilized3 in the electrorefining cells, the Bureau of Mines developed an electrowinning process. HfC14 was used as the feed material for the electro-winning process described in this report. Many of the electrolytes used in the electrorefining studies3 ap- peared to be suitable carrier-electrolytes for HfC14. However, in the initial studies on electrowinning, it was desirable to use electrolytes that had low solidus temperatures and could be operated over a wide temperature range to investigate parameters of the process. Therefore, electrolytes containing LiC1, NaC1, KC1, RbC1, CsC1, and HfC14, in various combinations were explored. EQUIPMENT Chlorinator. Hafnium carbide was chlorinated to produce HfC14 in the batch-type chlorination shown in Fig. 1. Chlorination temperatures were measured with a thermocouple placed in the center of the HfC charge. A flow meter was used to monitor the helium and chlorine. The exhaust side of the silica chlorina-tor tube was equipped with a flask for collecting organic material released during the initial heating of the HfC. The temperature of an internal heater, which extended from the HfC14 condensing flask to the hot end of the chlorinator, was adjusted to prevent the HfC14 from condensing before entering the collection flask. Helium and excess chlorine were exhausted through the lid of the collection flask to an aqueous NaOH solution. Sublimer. Initial studies were conducted using a sublimer, Fig. 2, made by placing a 13/8-in. OD nickel thimble 11 in. long, inside a 11/2-in. ID nickel bell 12 in. long, and locking it in place. This unit was loaded with HfC14 and partially immersed in the molten electrolyte for sublimation directly into the electrolyte. In another sublimer shown in Fig. 3, the HfC14 was contained in a "resin reaction flask". Quartz wool, previously heated to 600aC, secured between two nickel wire screens, was placed just above the HfC14 powder. The lid contained a vacuum outlet, a gage, an argon inlet, and an air-cooled pipe for condensing the HfC14. This sublimer was evacuated and heated. The sublimation temperature was not critical and the sublimer operated satisfactorily at all temperatures between 250" and 350°C. Electrolytic Cell. The electrolyte chamber, Fig. 4, was made of mild steel 8-in. schedule 20 pipe, 30 in. long. The exterior was metallized with a Ni-Cr alloy. The electrolytes were contained in a 16 gage nickel or iron liner with a nickel heat shield on top. The cell was heated by a resistance furnace. A 21/2-in. ID by 25 in. long air lock was connected to one port of a two-port cell cover assembly through a slide valve. The cover assembly of the air lock was electrically insulated from the cell and was equipped with a rubber sleeve that provided for the passage of the cathode lead. This allowed the cathode deposits to be removed and a new nickel cathode to be introduced without allowing air to enter the cell. A tube-rod assembly was bolted to the other port on the cell cover assembly and was sealed by a packing seal. The tube-rod assembly consists of a graphite

Jan 1, 1970

By Cyril Stanley Smith, Earl W. Palmer

FOR several years an investigation has been in progress in the research laboratory of The American Brass Co. to determine the thermal and electrical conductivities of most copper alloys of commercial importance and several of scientific interest. This paper contains such data on the binary alloys of copper with silicon, aluminum, manganese and nickel, and on a large number of ternary or more complex alloys. Some interesting general relationships between the thermal and electrical conductivities for all copper alloys at all temperatures are pointed out. The data for the copper-zinc, copper-phosphorus and copper-tin binary systems have already been publishedl 1,2 † except for the electrical conductivity at 200° C., which is given in the appendix of this paper. LITERATURE ON THERMAL CONDUCTIVITY OF COPPER ALLOYS The papers referred to above contained a summary of the figures available in 1929 for the thermal conductivity of copper alloys. There is given in Table 1 herewith a selection of the data that have appeared since that time. The measurements of Hanson and Rogers3 are particularly interesting since they cover a series of alloys in the alpha solid solution range and show the effect of heat-treatment. Their alloys were tested as annealed castings, and are not therefore directly comparable to the worked alloys measured in the present investigation, although the difference is small. Bailey's determinations4 were carried out on the alloys used by Lees5 in 1906, and extend his results to higher temperatures. It is most unfortunate that the alloys were not analyzed, for the approximate compositions given are hardly sufficient identification of the

Jan 1, 1935

By E. H. Edwards, J. Washburn, E. R. Parker

The mechanism of strain hardening was discussed in connection with some recent observations on the stress-induced motion of dislocation boundaries and on the simple shear deformation of zinc, cadmium, and copper crystals. THE nature of work hardening accompanying plastic deformation of metals has long been the subject of speculation. As early as 1925, Becker' suggested a thermodynamic process to explain slip based on the statistical probability for the occurrence of local glide steps. The theory that plastic glide was due to the presence of lattice defects known as dislocations was first introduced in 1934 by Taylor: and Orowan, and Polanyi.4 Taylor presented a rather complete analysis of the behavior and interaction of dislocations. He assumed a certain type of stress field to be associated with a single dislocation, and postulated that work hardening would result from plastic flow in two ways. First, dislocations following one another across a slip plane might encounter a barrier which would impede their movement, thereby gradually diminishing and eventually stopping plastic flow on that plane. The second mechanism involved the concept of dislocations traveling in opposite directions on nearby planes attracting one another to form a meta-stable lattice. The interaction of dislocations in such an array was shown to be large enough to require an increase in stress before plastic flow would continue. Kochendorfer5,6 extended the concept of work hardening involving a back stress due to an accumulation of like dislocations on a slip plane. He suggested that the formation of a new dislocation is hindered by those dislocations already present. The hardening resulting from the interaction of newly forming dislocations with bound dislocations was designated as "formative hardening," and indicated to be the only type of hardening necessarily connected with the slip process. In another detailed picture of work hardening, Mott and Nabarro7 assumed that sufficient dislocations are primarily present in the crystal as a consequence of growth irregularities (mosaic structure) to initiate slip. Work hardening resulted from the interaction of migrating dislocations with localized internal stresses produced during deformation. More recently, however, Mott8 as modified his treatment to include the generation of dislocations at Frank-Read sources and he accounts for the hardening by the formation of sessile dislocations. It has been widely accepted that metals of hexagonal structure, usually possessing only one set of glide planes, exhibit mechanical behavior markedly different from those having cubic structures. However, the differences in behavior of the two classes may be less fundamental than suggested. Rohm and Kochendorfer9 have shown that a single crystal of aluminum subjected to approximately simple shear gives the type of stress-strain curve associated with the hexagonal metals. Similar behavior has been demonstrated for gold and silver crystals by Andrade and Henderson.'" Thus when glide in cubic metals is restricted to one plane, the strain hardening characteristics closely resemble those of the hexagonal metals. It would appear, therefore, that an investigation of some of the strain hardening properties of single crystals sheared in simple glide might provide a more complete understanding of the phenomenon of work hardening. This report relates a number of recent observations made on single crystals of copper, zinc, and cadmium tested in simple shear. In addition, pertinent observations of effects accompanying stress-induced movement of dislocation boundaries are reported. Experimental Procedure and Results Details of the production and advantages of the type of single-crystal shear specimen employed for the following tests have been presented in a previous publication.n The method of testing makes

Jan 1, 1954

SECTION I PAGE PAGE Bulletin Wanted v Northwest Mining Convention St. Louis Meeting v (Columbia Section) xvi Proceedings of the Meeting of Affiliated Student Societies... xvii the Board of Directors vii Harrison W. Craver, New Li-¬ John Fritz Medal viii brary Director xviii Herbert C. Hoover, Food. Con Library xx troller viii Pamphlets for Sale xxii President's Prize ix Membership xxxvi Emmons Memorial Fellowship. x Biographical Notice of Her¬ Meetings of Various Societies. x Mann A: Keller : lviii Personal xi Institute Committees lix Employment xii Officers and Directors lxvi Local Section News xiii

Jan 5, 1917

By Jr. F. M. Perkins.

Capillary forces play a controlling role in water-drive displacement processes both in laboratory experiments and in actual reservoirs, but their quantitative importance may be quite different in the two cases. Because of the importance of conducting laboratory experiments which are representative of field conditions, it is necessary to understand exactly the role of capillary forces in the displacement process. Though a number of experimental investigations related to this subject are contained in the literature, there appears to be a lack of information pertaining to unsteady-state experiments in water-wet media. This experimental study was conducted to obtain additional laboratory data to clarify further the role of capillary forces in both the macroscopic and microscopic flow of oil and water in porous materials. THEORETICAL CONSlDERATlONS The capillary pressure is defined as the difference in pressure between a continuous oil phase and a continuous water phase in a porous material.' The magnitude of this pressure difference depends on the interfacial curvature and the interfacial tension. The interfacial curvature is determined by the geometry of the pore spaces, the wettability of the rock surfaces, and the quantity of cach phase present. Capillary forces are involved in a water-drive displacement process in that they exert a controlling influence on the microscopic fluid distribution which in turn is reflected in the saturation or macroscopic flow behavior. Microscopic Fluid Distribution Because of the microscopic nature of the displacement of oil by water, it is necessary to consider the flow and the fluid distribution in individual pores. On this microscopic scale the capillary Forces, which act over a distance of one or two sand grain diameters, control the distribution of oil and water under static equilibrium conditions. When an external force is applied to the fluids, such as in a water-injection experiment, the applied forces tend to distort the oil-water interfaces. However, in most fine-grained, water-wet sands, the applied pressure difference across one or two grain diameters is usually several orders of magnitude less than the capillary pressure difference. These con-siderations lead to the theory' that even during flow the capillary forces continue to control the microscopic distribution of oil and water within the pores of a porous material for all practical reservoir and laboratory flow rates. This concept of capillary forces controlling the microscopic distribution of fluids has been substantially verified by other investigators3-7 who have found a lack of dependence of relative permeability and residual oil saturation on rate of fluid injection. Macroscopic Distribution The microscopic influence of capillary forces cannot be observed easily and only the effect on the macroscopic or average saturation can be detected. The saturation, of course, is really the point of interest. During a water flood, large differences in saturation at the flood front cause large capillary pressure gradients. This, in turn, causes water to advance ahead of the flood front thereby reducing the capillary pressure gradient in this region. The result is that in homogeneous porous media capillary pressure gradients tend to cause a diffuse displacement front. At low rates in laboratory columns, the front may extend over the entire column length. When the advancing water first reaches the outflow face of a core, the water, which is the wetting phase, cannot be produced because the pressure in the water just inside the core is lower than the pressure in the oil-filled space around the outflow face. This difference in pressure is equal to the capillary pressure for the water saturation existing at the outflow face. Water, therefore, accumulates at the outflow end of the core which causes a reduction in the capillary pressure. Because the capillary pressure does not vanish except at the residual oil saturation,7,8,9 water will not be produced until the residual oil saturation exists at the outflow face. This entire effect,"' which is called the "boundary effect", results in a region of relatively high water saturation near the outflow face. At low rates of injection in a short column, this region of high water saturation may extend over a considerable portion of the column. The influence of capillary forces on the macroscopic flow of oil and water have been described by Leverett.10 For unidirectional, viscous flow in the absence of gravity segregation, the expression in dimensionless form for the fraction of water in the flowing stream, f, is

Jan 1, 1958

By R. W. Brown, J. L. Loper

The process of sand erosion has been harnessed to perform a useful function—the directed perforating of oilfield tubular goods and formation rock. In this process the sand is carried by a liquid medium and the resrrlting slurry is forced through a nozzle at an extren~ely high velocity. Upon impingement against casing or formation, the fast-moving sand particles erode a perforalion in the casing followed by cavity formation in the medium behind the casing. The many factors influencing the rate and extent of this penetration are inherently difficult to establish experimentally. Equations describing submerged jet behavior have been applied to these conditions. The following paper develops the equations for predicting the performance of the perforating jet. INTRODUCTION The cutting power of high-velocity sand has been well known in the petroleum industry for many years. Sand carried by a high-velocity gas stream causes severe erosion. This effect has been the cause of numerous production problems in certain areas. It was logical to expect that this phenomenon would one day be adapted to useful industrial applications. Development of mobile, high-pressure, high-horsepower pumping equipment in the last decade has made this possible. The sand erosion process involves pumping a fluid containing abrasive solids through a set of nozzles at a high differential pressure (2,000 to 4,000 psi). The pressure conversion into kinetic energy imparts high velocity to the sand particles which, upon impact with the formation face or casing wall, erode the material in an organized pattern. This paper attempts to establish the effects of the various parameters and to predict the performance and limitations of the process. The following factors will be considered: nozzle differential pressure, perforation size, sand concentration, nozzle stand-off distance and backpressure. In general, this discussion is presented along theoretical lines and is substantiated by field results and data where reliable field data exists. POWER EQUATIONS The penetration rate of a high-velocity hydraulic jet is proportional to the power or energy of the jet at the point in quesion. The power of the submerged jet will decrease with distance (or penetration) into the cavity created by the jet. As the cavity is extended into the formation, the power of the jet diminishes to a value equal to the threshold cutting power of the particular formation which is defiined as the lowest power level at which the formation will be abraded by the jet. Obviously, when this point is reached, no further cutting of the formation can occur. It is assumed that this power level for a particular formation is a function of the hardness of that formation. The following equation can be written for the hydraulic process of formation abrasion.

Council PRESIDENT OF THE COUNCIL. JOHN HAYS HAMMOND NEW YORK, N. Y. (Term expires February, 1908 ) VICE-PRESIDENTS OF THE COUNCIL. HENRY M. HOWE NEW YORK, N. Y. J. B. GRANT DENVER, COLO. JAMES D. HAGUE NEW YORK, N. Y. (Term expires February, 1908.) SAMUEL B. CHRISTY BERKELEY, CAL. JOHN A. CHURCH NEW YORK, N. Y. PERSIFOR FRAZER PHILADELPHIA, PA. (Term expires February, 1909 )

Jan 1, 1910

By E. K. Soper

It has been observed that where veins or other types of orebodies are intersected by cross faults, the continuation of the ore deposit below the fault is often of lower grade than that portion above the dislocation.' In some mines, the reverse of these conditions has been noted, and the richest ore is found to occur in that portion of the vein beneath the fault intersection. Such instances seem to be less frequent than those where the richest ore is above the offset. The important and widespread influence of fault and vein intersections upon the localization of ore shoots is well known,2 but the factors that govern the position of the ore shoot relative to the fault intersection seem to be less clearly understood. The richest ore may be above or below the fault, or it may occur at the point of intersection, or there may be no change. Recent observations made by the writer in mines in Idaho and Montana suggested a possible explanation for the changes in the richness of ore below certain types of fault intersections. These observations have been supplemented by a study of the literature containing detailed descriptions of ore deposits at a large number of mines in North America. The results of these studies are presented herewith in the hope that they may lead to further discussion of this important phase of ore deposition. Relative Age oF Faults Faults which intersect veins and other ore deposits may be either pre-mineral or post-mineral in age—that is, they may be older or younger than the deposits which they intersect. Many veins are formed along

Jan 1, 1918

By Edward V. D’Invilliers

In connection with some recent professional work in the coalfields of Western Pennsylvania, with special reference to results of coking operations, I was asked to compile a statement giving the estimated cost of mining coal and manufacturing coke at two hypothetical plants of 500 ovens each, giving the relative yield of coal in coke at each plant; and, upon the average number of working days in each of the past five years, from 1899 to 1903, together with average selling price of coke at the ovens, to prepare an estimate of the relative commercial returns in each district. What seemed at first sight to be a comparatively simple proposition, involving only the ordinary elements of mining and coking costs, became complicated by the lack of standard published records of mining costs and sales, which would be applicable to the subject at issue. Upon searching through the usual channels of Government publicatious and the files of our technical societies and mining periodicals, I was surprised to note the absence of fundamental factors that would approximately meet the case in point. The very elaborate and interesting statistics annually published by the National Government' do not supply the required data for the following reasons:—1. Being reported by arbitrary districts, the average values are too general to be applied to special fields. 2. The value of coal charged to the ovens is apparently based upon the regional average value of the coal if sold in the market, and not upon the cost of production. 3. Some plants only use the slack (a by-

Jan 1, 1905

By Spencer Cragoe

I have read with much interest the elaborate and able paper of Messrs. Granger and Treville on the Mining Districts of Colombia, presented at the Atlantic City Meeting (ante, p. 33). Going into detail, however, as the paper does—and particularly with reference to the department of Antioquia, I am somewhat surprised that the property of the Frontino and Bolivia Company, probably one of the richest and most extensive in Colombia, should come off with such scant notice. The entire property embraces an area of some 28 square miles, and is situated at a distance of about 2 leagues from Remedios—after Medellin probably the most important town of the Department—and lying in approximately '7° N. latitude. The neighborhood of Remedios has been long celebrated for its production of the precious metal. Alluvial gold in large quantities has been obtained from the vicinity for upwards of two centuries; and even to-day a large proportion of the population finds a comfortable livelihood, during the dry season, in washing the sands of various rivers, notably the Rio Porce; while the amount of gold, in the form of nuggets, brought almost daily to Remedios and other points, from streams in the immediate neighborhood, is astonishing. These nuggets vary much in size. The majority, of course, are small, but larger ones are by no means scarce. I have been considerably surprised at the amount and value of the trade thus transacted between natives and merchants of the various towns. The property owned by the Frontino and Bolivia Company has been, I believe, for the larger part of the present century,

Jan 1, 1899

By Jerry R. Johanson

The practical application of rolling theory to the design of roll presses is reviewed along with aspects of plant operations which must be considered to produce the required product economically. Appropriate parameters to scale up from laboratory tests to full- scale press operation and improvements possible in existing operations are discussed.

Jan 1, 1977

By M. H. Richman, L. M. Markowitz

MUCH of the available information on which the heat treatments of a particular steel are based is found in the isothermal-transformation diagram. Such is the case despite the fact that the usual thermal treatments involve continuous transformations, i.e., transformations which occur on cooling, rather than isothermal transformations. This rather unusual practice is continued because of the abundance of published isothermal-transformation diagrams1, 2 which are relatively easy to determine experimentally as compared to continuous-transformation diagrams.3, 4 However, this can easily lead to the production of improper micro-structures and may not allow full advantage to be taken of the inherent hardenability of a steel. A mathematical method of estimating the continuous-transformation diagram from the available isothermal data was developed by Grange and Kiefer;5 but, due to the mathematical approximations required in the calculations, the computation of continuous-transformation diagrams has been limited to individual cases and no large-scale compilation of these diagrams is available. With the present availability of high-speed digital computers, the problem of time-consuming approximations may be minimized and continuous-transformation diagrams may be constructed with the insertion of isothermal data into a basic program. It is the purpose of this report to announce the availability of such a program and compare the computed and experimental continuous-transformation diagrams for two different steels. Let us first review the method of Grange and Kiefer5 and then compare the results of the machine calculations with the experimentally determined diagrams. In order to apply this method, one requires the isothermal-transformation diagram and a set of curves representing cooling at constant rates. A section of an isothermal-transformation diagram is shown in Fig. 1 together with a cooling curve of M0F per sec. The cooling curve is constructed to start from the A1 (eutectoid) temperature if the transformation product is the eutectoid microconstituent (i.e., pearlite or bainite), from the A3 temperature if the product is primary ferrite, or from the 4, if it is proeutec-toid cementite. The cooling curve in Fig. 1 intersects the curve representing the start of isothermal transformation at a point A' corresponding to a temperature TX and a time fX. An arbitrary lower temperature To (on the

Jan 1, 1968

By Lo-Ching Chang, J. Chipman

The perennial and increasing interest in the chemical behavior of steelmaking slags has led to numerous attempts to formulate the thermodynamic properties of these solutions. The classical view is that of a solution of the component oxides in which certain acidic oxides are more or less completely held in combination with basic or metallic oxides, the nature of the interoxide compounds being derivable from the chemical behavior of the slag or from the mineralogy of a solidified specimen. The known electrical conductivity of slags has pointed to the existence of ions in the solution and a number of attempts have been made to account for the observed facts of slag behavior on the basis of a theory of complete ionization of the solution. It is the purpose of this paper to examine, in the light of ionic theory, a number of recently published series of data on slag-metal and slag-gas equilibria, with the purpose of obtaining a more complete or more satisfactory generalization than has been possible on either of the single bases of simple compound formation or complete ionization. The attempt to formulate the ionic constitution of a complex solution is fraught with many uncertainties. An ion is not something that can be plucked from the solution and examined in detail, nor can its true formula be determined with certainty by any single experimental method. In attempting to express the composition of a slag by various ionic formulas it can be expected that alternative hypotheses of essentially equal merit will present themselves. In the present state of early development of the ionic theory of slags, it may be necessary to make some rather arbitrary choices of ionic formulas in the absence of su- cient information to yield complete certainty. Acids and Bases The classification of slag-forming oxides as acidic or basic apparently dates back into the days of Berzelius. It is difficult to see how the concept could have originated in the early twentieth century when it was fashionable to define an acid or a base as an aqueous solution containing hydrogen or hy-droxyl ions. It is, however, entirely consistent with the modern and more general theory of acids and bases. In this theory, as originally formulated by G. N. Lewis,' a basic molecule is one that has an electron pair which may enter the valence shell of another atom thus binding the two together by the electron-pair bond. An acid molecule is one which is capable of receiving such an electron pair into the shell of one of its atoms. The acid, the base, and the product of neutralization may be either ions or neutral molecules. The product of such a reaction may itself be a base or an acid if it is further capable of giving or accepting an electron pair. Thus a base is a donor of electrons, an acid, an acceptor. In oxide slags the typical and ever-present base is oxide ion, 0-—. In behavior and in importance it is analogous to hydroxyl ion, OH-, which is the typical base of aqueous solutions. There is nothing in the chemistry of slags which is quite analogous to the acid H30+ in aqueous solutions. This is not surprising for in slag systems there is nothing which can be designated as a solvent and no ubiquitous positive ion. The chemistry of slags is in fact more complex than the chemistry of aqueous solutions and the concepts which must be evoked in its study are correspondingly broader. In seeking a basis for a classification of slag-forming oxides as basic or acidic it must be remembered that these terms are not absolute but relative. A substance which acts as a base toward a second substance may act as an acid toward a third. This is less likely to happen among strong bases or acids than among the weak ones; there are numerous examples of weak acids which under the influence of a stronger acid behave as weak bases. Such substances are called amphoteric. A classification of the glass-forming oxides has been proposed by Sun and Silverman² and further developed by Sun3 in which the oxides are arranged in order of decreasing acidity or increasing basicity, each substance being potentially capable of acting as an acid toward substances below it in the list and as a base toward those above it. It is based upon the relative strengths of the metal-to-oxygen bond as determined by the energy required to dissociate the oxide into its component atoms.' Data are available for computation of this energy, at least approximately, for the oxides of slags and glasses. In general those oxides from which it is most difficult to remove the positive atom are the strong acids while those in which it is most loosely held are the strong bases. It is in the latter, of course, that formation of oxide ion occurs most readily as, for example, in CaO which in solution ionizes to form the weak acid Ca++ and the strong base O—. The order of arrangement found by Sun is shown in the first column of Table 1, to which have been added the data for

Jan 1, 1950

By Y. C. Kim, S. L. Barua

M. Armstrong's paper is very interesting and can be regarded as a pioneering work of applying geostatistics on washed coal. The density levels used in her study are uniformly spaced, which facilitated curve fitting through a proper experimental design. Most of the existing coal washing plants in the US, however, gather washability data at non-uniform intervals which, in turn, affects the goodness of curve fitting. We would like to emphasize the importance of having a proper experimental design, if a similar geostatistical application is to be conducted on washed coal. We, at the University of Arizona, tried the variogram on recovery (Kim, Barua, and Baafi, 1982, SME preprint 82-143) which showed a similar pattern as Fig. 4 of Armstrong's paper. In both cases, the first experimental variogram value is invariably and inexplicably higher than the second variogram value. Although Armstrong ignores the first point because of "small number of sample points," we did not do so because there were 17 sample pairs. As a consequence, we concluded that the obtained experimental variogram was unsatisfactory and that further research is warranted. In other words, this disagreement in variogram interpretation between M. Armstrong and the University of Arizona begs the question whether the experimental variogram of Fig. 4 truly reflects the spatial correlation in washed coal, assuming there is such a correlation. Finally, we wish that Armstrong could have done a similar study on clean sulfur, which is a vital interest to the coal mines in the US. Her implied remark on sulfur in the concluding section of the paper may turn out to be incorrect because our experimental variograms on clean sulfur at different density levels were even less satisfactory than those on recovery. ?

Jan 1, 1986

By E. H. Kelton, R. D. Grissinger

E. E. Schumacher.*—DO YOU control the humidity in your test room? What effect does the environment have on your results? E. H. Kelton.—We do not attempt to control the humidity. As a matter of fact, the humidity in the beam tests that were conducted in a constant-temperature room varied widely and, as far as we know, there is no effect. The tension tests were conducted largely in an oil bath. I suppose there would be an effect in highly corrosive atmospheres, sufficiently corrosive to notch the specimen; otherwise, I would say none. E. A. Anderson.*—The effect of the humidity on the corrosion of zinc does not become important until the relative humidity is 70 per cent. At that point the corrosion products are capable of absorbing moisture and the corrosion rate increases. Below that point corrosion is almost imperceptible. This does not take into account any effect due to stress. That may be important. E. E. Schumacher.—Recently 1 have become very conscious of the enormous effect that surface films can exert on the physical properties of certain alloys. Shortly, we are publishing an article in which it will be shown that the fatigue endurance of some lead alloys can be changed markedly by merely changing the type of film placed on their surfaces. Changes as great as tenfold were observed. These findings make me wonder whether in your creep test you might not obtain quite variable results, depending upon the type of liquid medium used to immerse your specimens. Did you use more than one type of oil and, if you did, what were your results? E. H. Kelton.—I think we have used no more than three different oils, and we could not see any difference in effect.

Jan 1, 1945

By S. Forgeron, W. Shaw, E. L. Zodrow

Trend-surface equations are proposed for volumetric coal estimation in collieries of Sydney Coalfield, Nova Scotia. The statistical technique was first tried on Harbour coal in #20 Colliery investigating resulting residuals for abnormalities. The trend model is accepted as probably being correct as a result of that investigation. Indeed, higher degree polynomial trend- surfaces account for over 80% of the total map variability; these are encouraging statistical results, backed-up by geological knowledge about the coal seam, suggesting that the trend model has economic significance for an off-shore colliery developed to exploit the Harbour coal several kilometers east of #20 Colliery. Specifically, the need for additional offshore drill holes for the new colliery (excepting quality assessment holes) should be considered in light of a developed estimating model for the new colliery. The trend model also finds application in coalfields structurally more complex than Sydney Coalfield.

Jan 1, 1983

By Herbert W. Huse

Nitrogen, and its compounds, unique among the materials described in this volume, is absolutely essential to the existence of the human race. Almost all minerals are important and the absence of any one of them would be sorely felt; but nitrogen is an integral part of the cycle of life itself. Man cannot live without nitrogen which, as an inert gas, composes the major part of the air he breathes; as compounds, nourishes the vegetation which he eats; and, as protein, forms a part of his very flesh and blood. Nature originally provided man with a vast reserve of usable nitrogen compounds in the form of fertile soil. She constantly replenishes the supply by "fixing" nitrogen in the air at the estimated rate of 400,000,000 tons per year (an insignificant 6 lb per acre) during electrical storms. She has also placed certain microorganisms in the soil which are able to "fix" nitrogen and convert it into forms which plants can use. Legumes like cow peas, soy beans, clover, and alfalfa have extraordinary roots which serve as stimulating hosts to these bacteria which, in turn, nourish the plant. By plowing in all or part of such crops, their above-average nitrogen content can be returned to the soil for other more useful crops. The mechanism for this recycle is supplied by "denitrifying" bacteria which attack the dead plant tissue and liberate nitrogen and ammonia. However, since one crop of grain, sugar beets, potatoes, tomatoes, etc., takes out a major portion of the nitrogen which a plowed-in legume crop can supply, this method of fertilization is obviously inadequate. Drastic intervention by man has become necessary to support the ever-growing population of the world.9,15,20 Old civilizations with a high population density, such as the Chinese, were able to exist for centuries by carefully tilling the soil, rotating crops, and returning to the soil all the nitrogen in vegetable wastes plus human and animal excreta. But the lack of a means for augmenting their supply of nitrogen placed a ceiling on further development and kept the mass of the population in a chronic state of undernourishment, frequently punctuated by famine. Nitrogen plays another important role in the life of mankind. In the form of explosives, nitrogen helps to wrest from the earth many materials needed for our material well-being. Also, in the form of explosives and propellants, nitrogen increased the destructiveness of wars to a point only exceeded by the fantastic power of atomic energy. Man's first really effective efforts to improve his position with respect to nitrogen began in the 18th Century with the mining of sodium nitrate. By the late 1880's this had become a big industry serving a large part of the world. In the late 1890's nitrogen, in the form of ammonia, was being recovered from coke-oven operations. In 1900 nitrogen, in the form of nitric oxide, was being obtained from the air by an electric-arc process. About 1904 another "fixation" process based on the reaction of nitrogen with calcium carbide to form cyanamide was commercialized. By 1913 the Haber-Bosch process of "fixing" atmospheric nitrogen by reacting it with hydrogen to produce synthetic ammonia was successfully applied on a large scale, first in Germany and then throughout the industrial areas of the world.9 All the above methods of obtaining nitrogen compounds are still in use and, between them, they assure mankind of adequate supplies for all time. While this fortunate situation is not unique amongst industrial raw materials, all too few of man's needs are so well in hand.

Jan 1, 1960

By Merrill Horine

IT has been stated and accepted for many years that the automotive industry was the instigator, the principal sponsor for and the largest user of alloy steel and nonferrous alloys. The only universally recognized standard specifications and heat-treatments for these materials are those adopted by the Society of Automotive Engineers. It is this same auto-motive industry that has been the chief inspiration for and consumer of modern production machine tools. The production curve of steel ingots is more sensitive to fluctuations in automotive production than any other influence or group of influences. In every other important steel-con-suming industry, automotive materials and automotive processes are the outstanding features of modern progress. In this connection I need only mention the prefabrication of buildings, following the automotive system of straight-line, interchangeable mass production; the motorization of ships and railroads, employing automotive types of prime movers; the production of pressed-steel stoves, plumbing and furniture by methods originated in the automobile-body industry and the extensive use of rubber for the cushioning of all manner of machinery as pioneered by the automotive and tire industries. Dr. Jeffries has brought out this point in his address (p. 21), assuring us that the transportation industry is the largest user of these materials. In the transportation industry, or as we might more accurately express it, the transportation group of industries, the. automotive industry pre-dominates as a user of light alloys. One out of every four tons of aluminum produced is consumed by the automotive industry. Similarly, the automotive industry ranks first in the consumption of the following metallurgical materials: steel, 24.04 per cent; malleable iron, .57; alloy steels, 72.2; nickel, 30; lead, 39 per cent.

Jan 1, 1936