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By C. A. Rowland, R. C. Nealey

Until recently there were very few dry grinding rod mills used. The early installations performed as anticipated. In the last seven years a number of dry grinding rod mills have been made, most of which have been used for grinding iron ore. The recent installations have not operated as anticipated in accordance with practices learned from wet rod milling. The paper does not establish any definite rules for the application of dry grinding rod mills but does attempt to establish some guidelines that can be followed. The paper reviews a number of flowsheets describing the problems encountered and some of the solutions found. Completely dried compared to partially dried feed is reviewed. Problems encountered in scaling up from pilot plant to production-size mills are described. Rod sizing, effect of rod length, rod bending, rod breakage, and rod tangling are discussed. While wet grinding rod mills have been used for 50 years to grind ores and make specifications sands, dry grinding rod mills have only recently come into significant use in the mineral industries. Among the materials now being processed in dry grinding rod mills are (1) lead sinter, lead slag, and limestone; (2) iron ore; (3) silica; (4) cement clinker; and (5) coke. Because the application of wet grinding rod mills was well understood at the time that dry grinding rod mills were introduced, the criteria and guidelines for selecting the former were carried over to the selection of the latter - in some cases with the anticipated results, but in many cases not. It is the purpose of this paper to describe, through a series of flowsheets, some of the recent problems encountered with dry grinding rod mills, to point out the solutions to these problems, and to set forth some guidelines for the selection and application of these mills. When dry grinding rod mills came into use, the following facts about their wet grinding counterparts were already well established: (1) The performance of large-sized mills can be accurately predicted from the performance of rod mills 5 or 6 ft in diameter. Wet grinding mills as large as 14 ft in diameter (inside shell) by 20 ft long with rods 19.5 ft long can operate satisfactorily.

Jan 1, 1970

By E. E. Wark, J. Rogers, I. W. Wark, K. L. Sutherland

SOAPS have been used as collectors for many years, but only in the last eight years have other long-chain paraffin salts been used. It may be anticipated that these newer collectors will be used mainly with nonsulphide minerals, for which the xanthates and similar compounds are of little value. On the other hand, the xanthates are both cheap and effective for sulphide ores and seem likely to retain their present eminence in this field. During 1938 and 1939 two of us (E. E. W. and I. W. W.) commenced a comprehensive investigation of the principles underlying the use of paraffin chain salts as flotation reagents. This research was sponsored jointly by the University of Melbourne and a group of Australian mining companies.[t] A broad, semi quantitative survey was then made of the field covered in the present paper. This was followed in 1940 by further work by one of us (K. L. S.). In 1941 the investigation was taken over by the Division of Industrial Chemistry of the Commonwealth Council for Scientific and Industrial Research, Australia. Discovery of some principles upon which are based the flotation of minerals by paraffin chain salts was followed by their application in the development of processes for the recovery of certain strategic minerals from their ores. Promising results in the flotation of cassiterite from various ores will be described in a subsequent paper. THE PARAFFIN CHAIN SALTS The basic requirements for a "collector" in flotation are that it should form a film over the surface of the mineral to be floated, and that this film should be orientated so that hydrocarbon (nonpolar) groups form the effective surface. When modified in this way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince23 that such a film can be produced only if the collector compound contains an active (polar) group to attract it to the mineral surface as well as the nonpolar group. One section of this large class of polarnonpolar compounds is the paraffin chain salts: CH3(CH2) „X where X signifies a polar group that ionizes in aqueous solution. Though the compound can ionize, it may be a weak or a strong electrolyte, and the hydrocarbon chain may be in the cation or the anion (Table I). Many compounds of similar constitution are available, but the usual polar groups are: -CO2Na, -SO3Na, -SO4Na, - PO4Na2, or an aminonitrogen group, the

Jan 1, 1946

By Gerhard Derge

The rapidity of oxygen steelmaking has created renewed interesl in the mechanisms and kinetics of the various processes involved. These studies can now be approached with increased confidence because of the more adequate thermodynamics, physical chernislry, and relevant engineering infornzation available. These combine to offer promise of useful control and automation if the details of each specific problem can be sufficiently well-defined. The hot filament microscope provides new insig-hi into many of these problems by direct observation at temperature, allowing the appraisal of the relative importance of thermal gradients, convection, and intermediate phases. All of these have a direct bearing on the overall rates and control of most pyrometallurgical processes. It is one of the special privileges of the Howe Lecturer to become better acquainted with this distinguished man. All of us interested in the metallurgy of iron and steel have developed some sense of his widespread influence by the annual reference to his work in these Memorial Lectures. Each lecturer since 1923 has been able to identify his personal specialty with the broad interests of Professor Howe. This has become even more rewarding with the background information from Professor Gensamer's monograph, "Henry Marion Howe's Contributions to Metallurgy, which brings out his happy combination of intellectual and professional activities. Beyond this, I found my personal bond with Professor Howe in his book on The Metallurgy of Sleel first published in 1891.' After a detailed discussion of the dephosphorizing action of slags, he relates the mineral species identified in the frozen sample to the chemistry of the fused slag with the question, "Is it not most philosophic to hold that these independent entities were wholly integrated in the initial magma; that their presence in it was wholly

Jan 1, 1968

By P. B. Bucky

In previous publications1 it was shown that a scalar model of any weighty structure, where the stresses produced are mainly due to gravitational forces, will behave similarly to its prototype if the model and prototype material are the same and the model is placed in a centrifugal field of force (substituted for the gravitational field) which has been increased in the same proportion as the linear model scale is decreased. This principle is now being applied to a study of the behavior of mine structures in an attempt to determine the laws that control them. The importance of using models as a means of solving mining problems has been discussed previously, yet it may be well to reiterate here that this method of research and type of solution have been productive of far-reaching results in other engineering fields, notably those of hydraulics and aerodynamics. Model research is a comparatively cheap and time-saving method of checking practical experience. Up to the present time the best guide to what will happen underground has been the judgment of the man who has observed most and been longest acquainted with the local conditions. His experimental work underground is limited by the elements of cost, time and danger, while failure is seldom permissible. In a model, as in a test tube, all elements that affect the solution of a problem are under definite control. Each element may be varied independently at hill and its effects noted. Experimental work on a small-scale model may therefore be performed at a comparatively small expenditure of time and money, instead of on a full scale in the mine, where the cost, time, and danger elements are necessarily great. The experiments described in this paper are to be considered as part of a progress report and a continuation of Technical Paper 425. One object of the research program is to make each experiment point the way for further research on that particular phase of the general problem. The results and conclusions presented here are therefore not to be considered as final, but arc to be interpreted as

Jan 1, 1934

By A. M. Rahm

PROBABLY the majority of red brass sand castings are judged merely on the basis of outside appearance and the quality of machined surfaces. Many castings, however, must individually withstand a hydraulic or air-pressure test before being accepted as parts of more complicated machin-ery. Finally, there remains a comparatively small group of castings intended for uses of considerable responsibility where only the highest possible characteristics of the metal are acceptable, and for these specially cast test bars are required. The shape of the cast piece from which the test bar must be detached varies greatly from one country to another. The test bar as specified in the American Society for Testing Materials Specification B62-36 is widely used by the American foundry industry. The actual test piece is at the bottom of the cast block and has a riser about six times its mass. It is obvious that this test bar has an advantage over the actual casting. The latter rarely possesses a riser of as much as 30 per cent of its own weight and that riser cannot generally be located in so convenient a manner. Therefore, the characteristics of the test bar cannot possibly correspond to those of the casting itself. It must be taken into consideration that red brass if melted and cast in the best possible manner may show a tensile strength of 40,000 lb. per sq. in. with 35 per cent elongation in 2 in. Such a test bar would indicate that the metal was nearly perfect from the viewpoint of its gas and inclusion content. Barring some accidental defect, a casting cor-responding to such a test bar could be accepted as being quite sound. However, actual specifications do not demand such high characteristics; indeed, few specifications require over 30,000 lb. per sq. in. and 20 per cent elongation, while one Federal specification demands merely 27,000 lb. per sq. in. strength and 15 per cent elongation. It is obvious that

Jan 1, 1939

By Otto H. Henry, J. J. Cordiano

Though powder metallurgy is one of the oldest of metallurgical processes, it is in its infancy as a branch of the modern field of metallurgy. As early as 3000 B.C., the ancients produced implements and weapons of iron by reducing iron ore in a charcoal fire and forging the resultant sponge while still hot into the desired shape. Melting and casting soon superseded the powder metallurgy practice, and it was not until the turn of the twentieth century that powder metallurgy was applied to the commercial manufacture of tungsten lamp filaments. From this beginning, the use of the powder metallurgy process spread" to the manufacture of porous oil-impregnated bearings, cemented carbide tools, contact points, diamond grinding wheels, clutch facings, starter brushes, resin-bonded radio cores, magnets, metallic filters, and other parts. More recently, and particularly during the present war, there has been a definite trend toward the manufacture of machine parts by this process in competition with the more conventional fabricating methods. Notwithstanding these many developments, scientific progress has been slow. While many articles on powder metallurgy have appeared in the press and various publications, there have been too few contributions to our technical societies, with the result that there is a dearth of the type of information necessary for the full development of this science. It is of primary importance that the results of research and development be freely disseminated if powder metallurgy is to realize its fullest potentialities. Purpose of Investigation Excluding the refractory metal field, all commercial powder metallurgical products made by a cold compressing and sintering operation contain voids. These voids can be substantially eliminated by subsequent severe working and heat-treatment, but ' such practice has not proved economical in most applications. By applying heat during the compressing operation, plastic deformation of the powder particles is substantially increased, and the resultant compact or briquette is practically free of voids. However, hot-pressing has many attendant problems, which at present preclude its use in the manufacture of precision parts. The more important of these are to devise: 1. A die steel capable of withstanding high pressures at elevated temperatures. 2. A high-temperature lubricant capable of preventing excessive die wear and welding of the compact to the die walls. 3. A method of retaining a neutral or reducing atmosphere in the compacting zone of the die assembly. 4. A means of ejecting the hot-pressed specimen into a neutral atmosphere until reasonably cold.

Jan 1, 1946

By Harry K. Ihrig

THE hot-working of iron and steel is an art dating back to antiquity, but until about 25 years ago, relatively few alloying elements were used, and these were present only in small percentages. With the exception of sulphur, the amounts of other elements in steels did not markedly affect their hot-workability. The references in the literature on the effect of other elements on the hot-workability of steel are usually reports of failure of these steels in forging or rolling.1/8 With the increased use of alloying elements, and their use in larger amounts, it was observed that many of the new steels were red short in certain critical ranges or at all hot-working temperatures. The stainless steels are particularly difficult to hot-work. The determining of the correct conditions for piercing, rolling and forging of these alloys by experimentation in the mill often results in large losses of these expensive metals. It also is found that the hot-workability limits of many types vary from heat to heat, and hence poor results are obtained on changing to a new heat after a previous one has rolled satisfactorily. To determine the effect on hot-workability of iron to which various elements have been added, it was, necessary to devise a method that could be used on small quantities of metal. In such a method, the minimum number of variables should be present, and the procedure should be simple, quick and correlatable with large-scale hot-working operations. Sauveur,9 in the first Henry Marion Howe lecture in 1924, described the effect of carbon on the ductility of steels in torsion near their critical points. He found that carbon increases the plasticity of gamma iron. In the 1930 Campbell Memorial lecture,10 he gives the effect of carbon, chromium, and chromium and nickel on the ductility of steels under 2000°F. in torsion. Ellis11 has studied the malleability of steels at various elevated temperatures by means of a single-blow drop-hammer test. In this test the percentage decrease in height of standard cylinders is taken as a measure of their malleability. He has shown that in the low-alloy steels studied, carbon has a greater effect than nickel, chromium and vanadium. In 1938 the first tests were run on a new quantitative hot-workability test in the laboratories of the Globe Steel Tubes Co. Thum12 mentioned it in 1940. An illustration of the apparatus was published in January 1942.11 The effect of a few alloying elements on the hot-workability of metals was shown in a description of the test in 1944.14 DESCRIPTION OF TEST METHOD The method adopted after a trial of several others is a rapid twisting of bars to failure in a furnace. The standard-size bar was chosen as 9/16 in. It is prepared from larger pieces by forging and cold-

Jan 1, 1945

INTRODUCTION The regional characteristics of porphyry copper deposits in South America southward from Pantanos and Pegadorcito, Columbia, will be summarized. The age of formation of deposits spans the period from the Permian to the present. Where possible, the general characteristics and the individual structural features of the deposits are integrated into the plate tectonic model. Individual deposits cited in this chapter, located in Fig. 1, are the best known and most fully described, and form the Andean copper belt (Peterson, 1958). Smaller porphyry copper deposits fall both east and west of the line of large, high grade deposits (e.g., Chuquicamata and Toquepala) that make up the spine of this belt. Most of those smaller deposits (e.g., Mi Vida [Koukharsky and Mirre, 19761) are omitted from Fig. 1 and Tables 1 and 2, however. Neither the Andean orogen nor the individual deposits within it are as well de- scribed in the literature as are their counter- parts in the Cordilleran orogen of North America. Therefore, generalizations relying on regional geologic mapping, geophysics, and isotopic geochemistry lack details pertinent to this type of deposit in the Cordilleran orogen. The South American porphyry copper province has been described by Hollister ( 1974) to include most of the Andean orogen excepting the tin province of Bolivia. Porphyry copper deposits have not been commonly found within the tin belt, although copper-tin (e.g., San Rafael, Peru) and copper-tungsten (e.g., Llamuco, Chile) de- posits are known. James (1971) shows the depth to the Moho to be appreciably greater where the tin belt exists, but disclaims any genetic significance from the coincident appearance of the tin-tungsten province and the inhibition of porphyry copper development where the sialic crust thickens. Dates on tin mineralization in this belt (Clark and Farrar, 1973) are similar to some dates for porphyry copper mineralization known else- where in the Andean orogen. It seems that some mechanism is needed to explain the geographic separation of porphyry copper- molybdenum and simultaneous tin-tungsten- molybdenum metallization within the same tectonic system and appearing at similar distances from the trench. The thickened crust of the tin belt is one of the few known differences. Tables 1 and 2 list some of the most important porphyry copper deposits explored to date, but do not include Antaminas, Peru. or a number of other large skarn deposits

Jan 1, 1978

By Otto H. Henry, J. J. Cordiano

Though powder metallurgy is one of the oldest of metallurgical processes, it is in its infancy as a branch of the modern field of metallurgy. As early as 3000 B.C., the ancients produced implements and weapons of iron by reducing iron ore in a charcoal fire and forging the resultant sponge while still hot into the desired shape. Melting and casting soon superseded the powder metallurgy practice, and it was not until the turn of the twentieth century that powder metallurgy was applied to the commercial manufacture of tungsten lamp filaments. From this beginning, the use of the powder metallurgy process spread" to the manufacture of porous oil-impregnated bearings, cemented carbide tools, contact points, diamond grinding wheels, clutch facings, starter brushes, resin-bonded radio cores, magnets, metallic filters, and other parts. More recently, and particularly during the present war, there has been a definite trend toward the manufacture of machine parts by this process in competition with the more conventional fabricating methods. Notwithstanding these many developments, scientific progress has been slow. While many articles on powder metallurgy have appeared in the press and various publications, there have been too few contributions to our technical societies, with the result that there is a dearth of the type of information necessary for the full development of this science. It is of primary importance that the results of research and development be freely disseminated if powder metallurgy is to realize its fullest potentialities. Purpose of Investigation Excluding the refractory metal field, all commercial powder metallurgical products made by a cold compressing and sintering operation contain voids. These voids can be substantially eliminated by subsequent severe working and heat-treatment, but ' such practice has not proved economical in most applications. By applying heat during the compressing operation, plastic deformation of the powder particles is substantially increased, and the resultant compact or briquette is practically free of voids. However, hot-pressing has many attendant problems, which at present preclude its use in the manufacture of precision parts. The more important of these are to devise: 1. A die steel capable of withstanding high pressures at elevated temperatures. 2. A high-temperature lubricant capable of preventing excessive die wear and welding of the compact to the die walls. 3. A method of retaining a neutral or reducing atmosphere in the compacting zone of the die assembly. 4. A means of ejecting the hot-pressed specimen into a neutral atmosphere until reasonably cold.

Jan 1, 1946

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

By W. A. Backofen, D. Lee

The deformation of textured sheet of titanium and several of its all-a (hcp) alloys was investigated with two kinds of experiments: tension testing along different directions in the plane of the sheet, and combined-stress loading along the principal axes of anisotropy (the rolling and transverse directions). Texture and plastic anisotropy were evaluated with pole figures and by measurement, as a function of orientation, of the tensile transverse-strain ratio, or R parameter. The results as a whole can be rationalized qualitatively with the present understanding of deformation mechanisms in titanium. Quantitative agreement between the orientation dependence of tensile yield strength and the Predictions of continuum ANISOTROPY in the properties of engineering materials is more the rule than the exception because anisotropy in structure is so common, and the one generally follows the other. Two broad categories of structural anisotropy are represented by mechanical fibering and crystallographic texture. The former is important in many aspects of fracture.' The latter has more significance for yielding and plastic deformation, theory, using the R measurements, was relatively poor. However, in tension-tension quadrants of the yield-locus diagrams, the difference between theory and experiment was hardly more than 10 pct. The maximum texture-hardening effect was found in a 4Al-1/4O2 alloy to be nearly 50 pct. In the compression-compression quadrant, {1012} deformation twinning prevented the locus from expanding much beyond the Position predicted for isotropic material. With increasing temperature the trend in R was downwards, approaching unity (isotropy) near the a-transus temperature; an accompanying development was large amounts of neck-free extension. which are of special concern in this paper. The tendency has been to view crystallographic texture more as a liability or curio than as an asset. The prominent exception is found in silicon-ferrite sheet for power-transformer cores, which is processed to develop a new optimum texture for high electrical efficiency. Yet it should be possible to find other examples, involving other kinds of properties. More specifically, there is good analytical reason to expect improved combined-stress yielding resistance in suitably textured material,2,3 and it has now been shown by experiment that texture hardening or softening is a potentially useful phenomenon in certain engineering devices and processes.'-I To date, work has included measurements of the transverse (width to thickness) strain ratios in the

Jan 1, 1967

By A. L. Titchener, M. B. Bever

The stored energy of cold work was investigated in drawn gold-silver wires by tin-solution calorimetry as a function of strain, strain rate, initial grain size, and temperature of defornation. The energy expended in the deformation process was measured. Hardness was also measured and was correlated with the stored energy as a function of strain and strain rate. Mechanisms of energy storage are discussed. THE variables which determine the amount of energy stored in a metal during cold work are of two kinds: those involving the metal and its condition and those involving the process of deformation. For example, the stored energy differs between one metal and another and between different degrees of purity of a single metal. It also depends on the nature of the deformation process and particularly the extent, rate, and temperature of deformation. Most investigators have reported the stored energy as a function of strain (or some similar geometric parameter) or of the energy expended during deformation. In general the stored energy increases with strain, rapidly at first, but more slowly at large strains until a saturation level is reached. Information about the effects of other variables, however, is limited. Some data are available on the dependence of the stored energy on the purity of a metal1 and on the composition of

Jan 1, 1960

By James F. Kemp

The Bulletin of the Institute for March, 1911, is chiefly devoted to papers upon the iron ores of northeastern Cuba. At that time information about the new developments in the peculiar brown hematites of the region was becoming widely circulated and interest was especially keen. For some years exploration had been conducted with pits and trenches and so great an area had been shown to contain ore in the Mayari, Moa, and Cubitas or San Felipe districts, that the reserves conveniently situated for the consumption of American furnaces were estimated as quite two billions of tons. In the subjoined footnote will be found a list of the principal papers of special interest which have already been published.' The further remark may, however, be made that the

Jan 1, 1915

By J. W. Wolfe

The Benedict-Webb-Rmbin equation of state was used in digital computer programs to make rapid determinations of natural gas equilibrium phase compositions. Mixture components were the nine hydrocarbons, methane through heptane. Comparative tests were made with data from field separators, plant exchangers and literature sources. For most tests made, the B-W-R equations predrcted component K-vallles, mixture enthalpies and phase aensities within tile accuracy of available correlations for rune-component mixtures: significant deviations were noted when mixtures contained components heavier than heptune. INTRODUCTION Rapid, accurate methods for calculating the properties of hydrocarbon mixtures are needed for predicting the behavior of natural gas processes. For example, because of the common use of two-phase separation methods in gas proccssing, calculations must be made for the density and composition of equilibrium vapor and liquid phases. In addition, predictions must often be made for the temperature and pressure changes associated with the flow of single- and two-phase natural gas fluids through heat exchangers, chokes and turbines. The complex nature of non-ideal mixtures makes rigorous calculations for these natural gas properties difficult and time-consuming. Natural gas properties have conventionally been determined with generalized data correlations. These correlations, such as the K-values presented in the NGAA Equilibrium Ratio Data Book, are usually based on some average property of the mixture and have proven to give satisfactory estimates for the properties of most oil and gas systems. Digital computers, however, have not only increased the utility of these correlations, but also have made practical the use of equations of state for calculating the properties of natural gases. Potentially, if basic pure component data are available, all the desired thermodynamic properties of mixtures can be derived from a single equation of state describing the mixture. Currently. the best equation of state for describing the behavior of pure, light hydrocarbons over single-and two-phase regions, both below and above critical pressure, is that of Benedict. Webb and Rubin.' The equation contains eight constants which are determined by empirically fitting the equation to pure-component PVT data. Benedict and his co-workers presented the clevelopment of their equation as early as 1940.2 The B-W-R equation is a modification of the Beattie-Bridgeman equation of state and gives better PVT predictions than the Beattie equation at densities above the critical density. Benedict et al. made the equation applicable to mixtures by relating the mixture constants to composition and the constants for pure compounds. These authors, in a serics of articles in 1951,' showed the accuracy of the B-W-R equation when applied to light hydrocarbons and their simple mixtures, and demonstrated the equation's utility for making vapor-liquid equilibria calculations. Since its inception, the B-W-R equation has been the subject of many papers. Numerous additions and modifications have been proposed,'-',"'-':' the purpose of most being to improve the equation's ability to predict PVT properties of specific mixture systems. In 1959, Opfell, Pings and Sage summarized much of the work on the B-W-R equation in their book on equations of state." Since natural gases are primarily mixtures of light hydrocarbons, the B-W-R equation is a natural choice for an equation of state to compute both phase equilibria and thermodynamic properties of natural gases. Consequent-

Jan 1, 1967

By L. L. Swift

AT the present time there are four base metals being used for automotive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical, duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows in some types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and preventing overheating and rapid wear of parts. Less plasticity is required in a bearing metal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coefficient of friction. Under most operating conditions the friction depends on the unit pressure of the bearing, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the hearing., The hardness of, the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measurement of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual constituents was developed to, fill this need. MICROCHARACTER The Bierbaum microcharacter2.3 measures the scratch-hardness of a solid by pulling a weighted diamond point over the surface. The diamond point is ground. so that it is the corner of a cube, and mounted

Jan 1, 1938

By E. H. Jr. Dix

OF all the alloying elements used in commercial aluminum alloys, copper stands out as by far the most important, and it is perhaps for this reason that the constitution of the aluminum-copper system has received the attention of a number of experimenters covering a period of approximately 20 years. It would be expected that during this time the equilibrium relations had been thoroughly and exactly worked out. In a general way this is true, but there is a surprising lack of agreement in the details of the high aluminum end of the diagram, particularly in regard to the solid solubility of copper in aluminum, which has been given variously as 2 per cent. to 5 per cent. at the eutectic temperature. The importance of this is much greater than might at first appear to one unfamiliar with modern commercial aluminum alloys. This is true because, with one exception, the susceptibility of the strong alloys to heat treatment depends, in part at least, upon the solid solubility relations of copper in aluminum. In 1919, Merica, Waltenberg, and Freeman1 published the first detailed information on these solubility relations. They found that the solubility of copper decreases with falling temperature from about 4 per cent. at 5.25° C. to about 1 per cent. at 300° C. and is apparently still diminishing at lower temperatures. In 1921 there was published a brief account of the results obtained in the National Physical Laboratory, Teddington, England.2 This laboratory, however, reported that 5 per cent. of copper is soluble in aluminum at 540° C., and that this amount decreases to about 3 per cent. at 20° C.

Jan 2, 1926

APPROXIMATELY 3500 people thronged the Hotel Statler from February 18 to 24 for the 173rd general meeting of AIME. It was a technical extravaganza in that 82 technical sessions were held, at which 500 authors presented some 350 papers. Fortunately, Jerry Peirce, outgoing President, didn't have, to preside at all the events although after his year's stint as President, he has more than a nodding acquaintance with some of the latest problems in the mining, metals, and petroleum industries. Although the Welcoming Luncheon on Monday noon was the official opening of the meeting, Local Section Delegates and the Board of Directors convened on Saturday and Sunday, respectively. The large attendance and business like demeanor of these two groups was in accord with the energetic and competent service they have rendered the Institute through the year. To the applause of engineers and their wives who thronged the grand ballroom of the Statler for the Welcoming Luncheon, President Peirce introduced Oliver B. Hopkins, president of the Canadian Institute of Mining and Metallurgy and C. Gerow, secretary of CIM. Dr. Hopkins brought greetings from the CIM and expressed his satisfaction in the splendid spirit of cooperation that exists between the two Institutes. Dr. Hopkins is president, Interprovincial Pipe Line Co., Toronto, and counts as a close personal friend M. L. Haider, who is the 1952 President of AIME and lately of Toronto where he was a director and general manager of Imperial Oil Ltd. Mr. Haider will be known shortly as Mike to thousands of AIME members as he makes his Local Sections presidential tour. There was a pause in luncheon proceedings when Judge Harold R. Medina arrived amid the applause of the audience and somewhat breathless from his trip via motorcade from an antitrust trial against investment bankers at the courthouse downtown. With the Judge at his elbow, President Peirce took the opportunity in his introduction to good humoredly chide the Judge for the vixenish habits of public servants in their treatment of astute businessmen. The successful inventor who patents his inventions is a monopoly; the copper manufacturer who buys his competitors a drink is in collusion; but the business failure need only look to the government for a subsidy, Mr. Peirce pointed out. Judge Medina, quickly captured the admiration of his listeners. He spoke about justice, deploring partisan deals on nominations for judge-

Jan 1, 1952

Abdul-Ahad. A., Student, Montana School of Mines, Residence Hall Butte, Mont. '39 Abramovits, Charles, Student, Case School of Applied Science Cleveland, Ohio. '37 Abreu, Ovidio M., Student, Univ. of Nevada Reno, Nev. '38 Acker, Voscoe, Student, Agricultural & Mech. College of Texas College Station, Tex. '39 Adams, Albert, Student, New Mexico School of Mines Socorro. N. M. '38 Adams, Charles W., Student, Michigan College of Min. & Tech Houghton, Mich. '39 Adams, Hugh T., Jr., Student, Univ, of Oklahoma Norman, Okla. '39 Adams, Jack L., Student, Univ. of Oklahoma Norman, Okla. '39 Adams, Jack M., Student, Univ of Alaska College, Alaska. '39 Adams, Lewis J., Student, Agricultural & Mech. College of Texas, Box 2514, College Station, Tex. '39 Adams, Robert E., Research Engr., Battelle Memorial Inst Columbus, Ohio. '38 Adamson, George M., Jr.. Student, Univ. of Utah Salt Lake City, Utah. '39 Adkisson, J. F., Jr., Student, Agricultural & Mech. College of Texas, Box 1003, College Station. Tex. '38

Jan 1, 1939

By Charles H. Fulton

Experimental work on the process was begun on a laboratory scale at Cleveland, Ohio, in 1914, and transferred to East St. Louis, Ill. in 1916, where a commercial sized furnace was in technical operation until January, 1918. The essential steps of the process are as follows: Oxidized zinc ore or roasted zinc concentrate is mixed with crushed coke and coal-tar pitch and formed into briquets 9.25 in. (23.5 cm.) in diameter and 21 in. (53 cm.) long in a manner similar to that used in the manufacture of graphite or carbon electrodes, except that much less care and time are required. The composition varies with the nature of the ore; in one case, the composition was 100 parts ore, 70 parts coke, and 18 to 20 parts pitch. These briquets maintain their form and volume during and after the distillation of the zinc. This object is gained by using coke as the matrix and coal-tar pitch as the binder; this pitch becomes coke on heating and unites the ore particle and the original coke particle into a continuous mass. The briquet is an electrical conductor but only to such a degree that it can be used as a resistor. The size of the ore, as in the present practice of zinc metallurgy, ranges from fine material, such as flotation concentrate, to coarse table and fine jig concentrate. The process is not restricted to any particular kind of ore, but is applicable to pure high-grade ores, ores high in iron, and complex zinc-lead ores, since the residue from the distillation IS held immovably in place within the briquet. In the case of complex zinc-lead ores, the distillation is conducted with a carefully regulated temperature so that a high percentage of lead is retained in the distilled briquet, which may then be smelted for its lead content. In present zinc smelting practice, the reduction fuel is from 40 to 50 per cent. of the weight of the ore. In the briquet, it is from 60 to 85 per cent. of the ore; but unless the ore is exceptionally high in residue, the distilled briquet may be used over again as coke, or as a high ash coke for fuel purposes in power production. Baked briquets are hard and tough and may be handled roughly

Jan 1, 1921