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By R. Priestner, R. F. Krause

Solid, cylindrical crystals of a iron have been fractured at 10°K by the simultaneous application of tension and torsion stresses. Thus, a complex distribution of normal (sN) and shear (ss) stresses existed in a cleavage plane at fracture. In every crystal the clearage-plane normal was inclined to the specimen axis, so that a unique point, M*, in the operative cleavage plane was defined where the quantities sn and s2 N + s2 S) were maximized. It is shown that the maxirrzum resolved normal stress on the cleavage plane at fracture decreased as the resolved shear stress in the cleavage plane at M* increased. Thus, a normal stress la?*! for fracture was not satisfied. A fracture law which takes shear stress into account. and which predicts that (s2 N +s2S) should be constant, is to be preferred. However, the data is best represented by a linear dependence of sN on sS, sS which 110 physical significance can be attached. It is suggested that the fracture-nucleating -mechanism is a short-range one. A critical stress law has not yet been unequivocally established for the propagation of cracks in metals. Measurements of the tensile fracture stresses of variously oriented zinc single crystals1 failed to establish the normal stress law expressed by In Eq. [1], sN is the fracture stress, P, resolved normal to the fracture plane, and 0 is the angle between the fracture -plane normal and the stress axis. Similarly, a comprehensive investigation failed to verify the normal stress law for the tensile fracture of a-iron single crystals.' However, a subsequent investigation,3 using iron from the same ingot, presented fracture data which obeyed the normal stress law. It has been shown previously4,5 that the Griffith criterion for fracture6 does not predict such a normal stress law. This result is of particular significance in considering the fracture of metals, such as zinc and iron, which may fail by cleavage. In these metals fracture propagates in a well-defined "cleavage" plane, whether or not an applied stress is normal to it. When the cleavage-plane normal deviates from the direction of application of a uniaxial stress, for example, the crack propagates under the combined action of normal (sN) and shear (ss) stresses. When the presence of a resolved shear stress in the crack plane is taken into account, the Griffith criterion is expressed by4

Jan 1, 1967

By T. H. Weldon, L. V. Whiton, R. R. McNaughton, J. H. Hargrave

R. H. McNAUGHTON*—The Smelting Co. and Mr. Reid and his men at Selby are to be congratulated on the job they have done on sinter gas recircula-

Jan 1, 1950

By W. H. Herrnstein, F. H. Beck, M. G. Fontana

Sulfur solubility in a iron was measured in the 750 to 890°C temperature range and was found to be insensitive to ferrite purity within a limited composition range. The permeability of sulfur in ferrite was determined from the internal sulfidation of Fe-Mn alloys. From the solubility and permeability results, the diffusivity of sulfur in ferrite could be calculated. These results are summarized as follows: Dissolved sulfur decreased the lattice parameter of ferrite. The effect of dissolved sulfur on the tensile properties of ferrite at low temperatures was also determined. SINCE sulfur is an important residual impurity in commercial irons and steels, effects associated with the presence of sulfur as a solute in iron are of considerable practical interest. Unfortunately, certain basic information relative to the Fe-S system appears to be lacking in the literature, e.g., the effect of dissolved sulfur on the lattice parameter and mechanical properties of ferrite. In addition, discrepancies exist in previously reported results for the solubility of sulfur in ferrite. These discrepancies raise questions regarding the sensitivity of sulfur solubility to the purity and microstructure of iron. This study was undertaken primarily in an effort to obtain reliable data on the solubility of sulfur in ferrite. Additional objectives included determination of the permeability and diffusivity of sulfur in ferrite by the internal sulfidation method and determination of the effect of dissolved sulfur on the lattice parameter and tensile properties of ferrite. EXPERIMENTAL METHOD Three grades of iron, encompassing a range of impurity levels, were employed in the study. The grades were designated VME (vacuum-melted electrolytic), SPZR (single-pass zone-refined), and MPZR (multipass zone-refined). The composition of each grade is given in Table I. Poly crystalline and single-crystal strip specimens were employed in the solubility experiments. Uniform grain size strip (ASTM 3 to 5) of 0.005 to 0.020 in. thickness was obtained by alternate cold reductions of 60 thickness 60 to 80 pct and recrystallization at 650°C for i hr in pure, dry argon. Single-crystal specimens were produced in 0.010-in.-thick SPZR iron strip by the strain-gradient anneal technique. Recrystallized strip 0.25 in. wide was strained until a Luders band or bands had propagated over the length of the strip; the strip was then annealed by drawing it through a 150°C per in. gradient (890°C peak temperature) at 1 in. per hr in an atmosphere of pure, dry argon. Laue photographs of the crystals produced exhibited no discernible asterism. Specimens were equilibrated with H-H, atmospheres at temperatures between 750" and 890" by one of two methods, each of which makes use of the reaction: The encapsulation sulfurization method was employed in the majority of the solubility experiments. A strip

Jan 1, 1969

By Frank G. Norris, William C. Marshall

The term "total operation" is meant to include problems that cannot be answered from the standpoint of either the blast furnace or the open hearth separately but must be studied by considering the interrelations of these two processes. There are other ways of expressing this idea, such as reference to the blast furnace and the open hearth as an integrated process or by emphasizing the interrelation and interaction of the two processes. Much progress has been made in metallurgy and other fields by breaking complicated processes and reactions into simpler parts and studying each of these intensively. This intensive study frequently is done under the controlled conditions of the laboratory experiment. The entire process is understood better by this specialized study of each of its parts. This procedure is so satisfactory that an understanding of unit operations is a fundamental requirement of chemical engineering. Much discussion of the open-hearth process is in terms of one heat or one furnace. By this is meant that the conclusions apply to one furnace, wherever it may be. Furnaces seldom occur singly; they are located in groups and these groups are located in steel plants having characteristic blast-furnace equipment. Problems that are affected by the number of furnaces operating, by the number of blast furnaces in the plant and by the fact that the open- hearth shop is dependent on the bla furnace capacity rather than on its o needs for the amount of iron available among those which, in contrast to "u operations," we have chosen to call "to operations." Many of these problems, such as cha ing delays and the general mechani problem of material handling, are familiar that merely to define " total op ations" brings them to mind. These pr lems are of such importance that alrea they have received careful thought 2 study and probably will merit furt study. As will be shown later, these mechan problems are so intimately related metallurgical problems of total operati that the effect of certain changes cannot ascribed with certainty to either a mech ical or a metallurgical cause entirely. Although the problems coming under general term of "railroading" are inclu in the problems of total operations, ' others are selected for the discussion of paper, One of these is strictly a problem composition; the other is strictly a prob of tonnage production. The problem of phosphorus is pres whenever basic open-hearth slag is used the blast-furnace burden. This practice not secured universal acceptance chi because of difference in preference for h manganese or low-manganese pig iron hjgh-manganese (2.00 per cent) iron is to made, open-hearth slag as a source manganese is usually cheaper than m

Jan 1, 1943

By E. C. Babson

In order to explore the possibility of predicting reservoir performance from laboratory data, behavior of a hypothetical low-permeability reservoir has been estimated by applying data and methods currently available in the literature. A method of calculating decline in productivity index is discussed, and recoveries by internal gas drive, external gas drive and water drive are estimated. Introduction During the life of a producing oil property an operator is faced with many perplexing problems. Any attempt to determine proper well spacing, optimum rate of production, or the desirability of pressure maintenance requires the evaluation not only of a host of economic and practical operating factors but also of the future performance of the reservoir. Although in some cases economic or operating con-siderations may be of primary importance in planning a development or production program, the anticipated effect on ultimate recovery is more likely to be the decisive factor. The soundest basis for evaluating reservoir performance is past experience with oil fields, but pertinent data are difficult to obtain or apply under conditions normally encountered in California fields. Many of these fields are characterized by thick sections of alternating sands and shales complicated by faulting and rapidly changing lithologic conditions. Further compli- cations are introduced by haphazard development and production practices resulting from competitive conditions, changing demand for oil, and insufficient knowledge of structural conditions during early development. Even in the rare cases where development has been systematic and adequate, production policy has usually been controlled by economic and competitive factors rather than a desire to obtain information for use in future operations. In other words, comparable reservoirs in which development and production practices have been systematically varied are seldom found. In the light of these conditions, conclusions based on experiences usually lack the certainty required for decisions involving large sums of money. Some other method of attacking these problems is needed to supplement and orient field experience. Progress in laboratory investigations of the flow of oil, gas, and water through sands has been so rapid in recent years that these data may furnish such a supplementary approach in the near future. In order to explore this possibility the author has attempted to predict the behavior of one type of reservoir by applying published data and methods. Basic Data and Assumptions Calculations outlined in this paper are dependent upon a detailed knowledge of the properties of oil, gas, and water present in the reservoir and the portion of the total pore space originally filled by each. It is also necessary to know how the permeability of the sand to oil, gas, and water varies with the saturations of these fluids 20

Jan 1, 1944

By Lloyd R. Jackson

In the past 15 years there has been a great deal of interest in the fundamentals of plastic flow and rupture in metals and a number of papers have presented substantial advances toward a fundamental insight into the mechanism of these two processes. This paper is an appraisal of the present position with respect to the following: 1. The relative importance of shear and hydrostatic stresses in controlling the plastic flow of metals. 2. The relative importance of shear and hydrostatic stresses in determining the amount of flow before rupture in metals. 3. The use of generalized strains in determining the effect of plastic flow on the work-hardening of metals. FundamentalS Involved in Plastic Flow In attempting to devise a quantitative description of plastic flow in metals, it has been customary to assume that metals are homogeneous and isotropic. The fact that neither of these assumptions is correct complicates the experimental appraisal of relations developed. Nevertheless, as will be shown, metals are close enough '0 being isotropic and homogeneous so that considerable insight into the mechanism of plastic flow can be obtained. The assumptions of isotropy and homogeneity allow both the elastic and plastic behavior of metals to be described in terms of 12 variables—six being stress variables, and six being strain variables. From this viewpoint, it should be possible to represent the stress-strain relations in the plastic range for metals by a surface in 12 dimensions. One boundary of this surface would be the surface of transition from elastic to plastic behavior; the other would be the surface of rupture. These two surfaces would be joined by the surface of plastic flow. The shape of this composite surface would depend on the test temperature and speed of straining This paper is concerned only with results obtained at constant temperature and constant speed of straining. While such a representation is conceivable, the demonstration of such a surface would present almost insurmountable obstacles. The most fruitful simplification of this concept has been the recognition that the behavior of metals in the plastic region is primarily a result of shear stresses and strains. Based on this viewpoint, it is possible to utilize stress and strain invariants that are independent of hydrostatic components to define an effective stress and strain. In effect, this amounts to reducing the task of representing stresses and strains in 12 dimensions to one of representation in two dimensions. The two invariants (one for stresses and one for strains) that have received most attention are the following: q2 = ½[(Txx= - Tyy)2 + (Tyy - Tzz)2 + (Tzz - Txx)2 + 3(Txy2 + Tyz2 + 7xx2) [1]

Jan 1, 1947

By William C. Marshall, Frank G. Norris

The term "total operation" is meant to include problems that cannot be answered from the standpoint of either the blast furnace or the open hearth separately but must be studied by considering the interrelations of these two processes. There are other ways of expressing this idea, such as reference to the blast furnace and the open hearth as an integrated process or by emphasizing the interrelation and interaction of the two processes. Much progress has been made in metallurgy and other fields by breaking complicated processes and reactions into simpler parts and studying each of these intensively. This intensive study frequently is done under the controlled conditions of the laboratory experiment. The entire process is understood better by this specialized study of each of its parts. This procedure is so satisfactory that an understanding of unit operations is a fundamental requirement of chemical engineering. Much discussion of the open-hearth process is in terms of one heat or one furnace. By this is meant that the conclusions apply to one furnace, wherever it may be. Furnaces seldom occur singly; they are located in groups and these groups are located in steel plants having characteristic blast-furnace equipment. Problems that are affected by the number of furnaces operating, by the number of blast furnaces in the plant and by the fact that the open- hearth shop is dependent on the bla furnace capacity rather than on its o needs for the amount of iron available among those which, in contrast to "u operations," we have chosen to call "to operations." Many of these problems, such as cha ing delays and the general mechani problem of material handling, are familiar that merely to define " total op ations" brings them to mind. These pr lems are of such importance that alrea they have received careful thought 2 study and probably will merit furt study. As will be shown later, these mechan problems are so intimately related metallurgical problems of total operati that the effect of certain changes cannot ascribed with certainty to either a mech ical or a metallurgical cause entirely. Although the problems coming under general term of "railroading" are inclu in the problems of total operations, ' others are selected for the discussion of paper, One of these is strictly a problem composition; the other is strictly a prob of tonnage production. The problem of phosphorus is pres whenever basic open-hearth slag is used the blast-furnace burden. This practice not secured universal acceptance chi because of difference in preference for h manganese or low-manganese pig iron hjgh-manganese (2.00 per cent) iron is to made, open-hearth slag as a source manganese is usually cheaper than m

Jan 1, 1943

By E. C. Babson

In order to explore the possibility of predicting reservoir performance from laboratory data, behavior of a hypothetical low-permeability reservoir has been estimated by applying data and methods currently available in the literature. A method of calculating decline in productivity index is discussed, and recoveries by internal gas drive, external gas drive and water drive are estimated. Introduction During the life of a producing oil property an operator is faced with many perplexing problems. Any attempt to determine proper well spacing, optimum rate of production, or the desirability of pressure maintenance requires the evaluation not only of a host of economic and practical operating factors but also of the future performance of the reservoir. Although in some cases economic or operating con-siderations may be of primary importance in planning a development or production program, the anticipated effect on ultimate recovery is more likely to be the decisive factor. The soundest basis for evaluating reservoir performance is past experience with oil fields, but pertinent data are difficult to obtain or apply under conditions normally encountered in California fields. Many of these fields are characterized by thick sections of alternating sands and shales complicated by faulting and rapidly changing lithologic conditions. Further compli- cations are introduced by haphazard development and production practices resulting from competitive conditions, changing demand for oil, and insufficient knowledge of structural conditions during early development. Even in the rare cases where development has been systematic and adequate, production policy has usually been controlled by economic and competitive factors rather than a desire to obtain information for use in future operations. In other words, comparable reservoirs in which development and production practices have been systematically varied are seldom found. In the light of these conditions, conclusions based on experiences usually lack the certainty required for decisions involving large sums of money. Some other method of attacking these problems is needed to supplement and orient field experience. Progress in laboratory investigations of the flow of oil, gas, and water through sands has been so rapid in recent years that these data may furnish such a supplementary approach in the near future. In order to explore this possibility the author has attempted to predict the behavior of one type of reservoir by applying published data and methods. Basic Data and Assumptions Calculations outlined in this paper are dependent upon a detailed knowledge of the properties of oil, gas, and water present in the reservoir and the portion of the total pore space originally filled by each. It is also necessary to know how the permeability of the sand to oil, gas, and water varies with the saturations of these fluids 20

Jan 1, 1944

By Lloyd R. Jackson

In the past 15 years there has been a great deal of interest in the fundamentals of plastic flow and rupture in metals and a number of papers have presented substantial advances toward a fundamental insight into the mechanism of these two processes. This paper is an appraisal of the present position with respect to the following: 1. The relative importance of shear and hydrostatic stresses in controlling the plastic flow of metals. 2. The relative importance of shear and hydrostatic stresses in determining the amount of flow before rupture in metals. 3. The use of generalized strains in determining the effect of plastic flow on the work-hardening of metals. FundamentalS Involved in Plastic Flow In attempting to devise a quantitative description of plastic flow in metals, it has been customary to assume that metals are homogeneous and isotropic. The fact that neither of these assumptions is correct complicates the experimental appraisal of relations developed. Nevertheless, as will be shown, metals are close enough '0 being isotropic and homogeneous so that considerable insight into the mechanism of plastic flow can be obtained. The assumptions of isotropy and homogeneity allow both the elastic and plastic behavior of metals to be described in terms of 12 variables—six being stress variables, and six being strain variables. From this viewpoint, it should be possible to represent the stress-strain relations in the plastic range for metals by a surface in 12 dimensions. One boundary of this surface would be the surface of transition from elastic to plastic behavior; the other would be the surface of rupture. These two surfaces would be joined by the surface of plastic flow. The shape of this composite surface would depend on the test temperature and speed of straining This paper is concerned only with results obtained at constant temperature and constant speed of straining. While such a representation is conceivable, the demonstration of such a surface would present almost insurmountable obstacles. The most fruitful simplification of this concept has been the recognition that the behavior of metals in the plastic region is primarily a result of shear stresses and strains. Based on this viewpoint, it is possible to utilize stress and strain invariants that are independent of hydrostatic components to define an effective stress and strain. In effect, this amounts to reducing the task of representing stresses and strains in 12 dimensions to one of representation in two dimensions. The two invariants (one for stresses and one for strains) that have received most attention are the following: q2 = ½[(Txx= - Tyy)2 + (Tyy - Tzz)2 + (Tzz - Txx)2 + 3(Txy2 + Tyz2 + 7xx2) [1]

Jan 1, 1947

By W. R. Hibbard

Although extensive pole figure studies have been reported by Brick1 and others2,3 showing preferred orientations in rolled and annealed 70-30 alpha brass, and by Hermann and Sachs4 in 70-30 alpha brass cups, comparatively little information has been published on textures in drawn 70-30 alpha brass tubes. Crampton5 reported a (110) , [111] texture in drawn brass tubes based on selected individual X ray photograms following the method of Norton and Hiller,6 but the extent and ease of developing this texture and the annealing texture have not been reported and pole figures of these structures were not found in the literature. The present investigation was further stimulated by the possible influence of textures on the mercury stress-corrosion cracking of brass tubes. According to Snoek,7 iron-nickel alloy sheet with a strong cubic texture was more resistant to corrosion than a randomly oriented sheet. Crampton5 reported that single crystals of 70-30 alpha brass drawn into tubes did not crack after 24 hr in a standard mer-curous nitrate test. Edmunds12 found that single crystals of 70-30 alpha brass did not crack in a standard mercurous nitrate test but did crack when subjected to ammoniacal vapor. Wasserman11 reported a similar failure of a single crystal of brass in ammonia. A tube with a strong texture might approach single crystal behavior and tend to resist mercury cracking if the differences in orientation between adjacent grains were sufficiently slight. Preparation OF Specimens Crampton's5 tubes drawn 28 pct reduction in area developed a slight degree of preferred orientation while in tubes drawn 48 pct it was more marked. Based on this information, in order to obtain specimens with markedly different degrees of preferred orientation but with the same final draw, two sets of 70-30 alpha brass tubes were made following the mill schedules shown in Table I. The final draw involved a large reduction in outside diameter, and a ratio of reduction in area to reduction in outside diameter similar to that reported by Crampton,5, 10 to cause mercury cracking of brass tubes. The brass contained 71.31 pct copper, 0.01 pct lead, 0.01 pct iron and zinc by difference. Determination of Pole Figures A 6-in. length from each tube was rotated rapidly by an electric stirrer in 25 pct nitric acid until the gauge was reduced to 0.003-0.005 in. The tubes were carefully cut longitudinally and the walls gently flattened. They were further etched in 25 pet nitric acid to 0.0015 in. thickness and (111) pole figures were determined using copper K-alpha radiation in the manner described by Brick.' The three general types of pole figures

Jan 1, 1949

By W. R. Hibbard

Although extensive pole figure studies have been reported by Brick1 and others2,3 showing preferred orientations in rolled and annealed 70-30 alpha brass, and by Hermann and Sachs4 in 70-30 alpha brass cups, comparatively little information has been published on textures in drawn 70-30 alpha brass tubes. Crampton5 reported a (110) , [111] texture in drawn brass tubes based on selected individual X ray photograms following the method of Norton and Hiller,6 but the extent and ease of developing this texture and the annealing texture have not been reported and pole figures of these structures were not found in the literature. The present investigation was further stimulated by the possible influence of textures on the mercury stress-corrosion cracking of brass tubes. According to Snoek,7 iron-nickel alloy sheet with a strong cubic texture was more resistant to corrosion than a randomly oriented sheet. Crampton5 reported that single crystals of 70-30 alpha brass drawn into tubes did not crack after 24 hr in a standard mer-curous nitrate test. Edmunds12 found that single crystals of 70-30 alpha brass did not crack in a standard mercurous nitrate test but did crack when subjected to ammoniacal vapor. Wasserman11 reported a similar failure of a single crystal of brass in ammonia. A tube with a strong texture might approach single crystal behavior and tend to resist mercury cracking if the differences in orientation between adjacent grains were sufficiently slight. Preparation OF Specimens Crampton's5 tubes drawn 28 pct reduction in area developed a slight degree of preferred orientation while in tubes drawn 48 pct it was more marked. Based on this information, in order to obtain specimens with markedly different degrees of preferred orientation but with the same final draw, two sets of 70-30 alpha brass tubes were made following the mill schedules shown in Table I. The final draw involved a large reduction in outside diameter, and a ratio of reduction in area to reduction in outside diameter similar to that reported by Crampton,5, 10 to cause mercury cracking of brass tubes. The brass contained 71.31 pct copper, 0.01 pct lead, 0.01 pct iron and zinc by difference. Determination of Pole Figures A 6-in. length from each tube was rotated rapidly by an electric stirrer in 25 pct nitric acid until the gauge was reduced to 0.003-0.005 in. The tubes were carefully cut longitudinally and the walls gently flattened. They were further etched in 25 pet nitric acid to 0.0015 in. thickness and (111) pole figures were determined using copper K-alpha radiation in the manner described by Brick.' The three general types of pole figures

Jan 1, 1949

By F. R. Hensel

PuRe silver and silver-lead alloys have been studied as to their suitability for bearing~.' A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materia1s. t The silver-rich end of the diagram as reported in the literatureg-" was found to be sketchy and it was necessary to carry out corisiderable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. Test Materials In the beginning of the work, only fused alloys were investigated. Later, research Table i.—Composition of Fused Silver-thallium Alloys Tested for Antifriction Properties Percentage Alloy No. of Thallium 1533...................... 0.48 1534.................... 1.06 a31 HT................... 2.04 231....................... 2.10 232 HT................... 3.83 Balance 232....................... 4.07 Silver 233 HT................... 5.86 a33....................... 6.38 a34....................... 9.84 a34 HT................... 10.07 was carried out on electroplating methods and diffusion processes. In preparing the fused alloyst care was taken to exhaust the toxic fumes caused by the thaillium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in, diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr207, 8 C.C. H2S04, and IOO C.C. H20. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475OC. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not iesiilt iii complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1946

By F. R. Hensel

PuRe silver and silver-lead alloys have been studied as to their suitability for bearing~.' A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materia1s. t The silver-rich end of the diagram as reported in the literatureg-" was found to be sketchy and it was necessary to carry out corisiderable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. Test Materials In the beginning of the work, only fused alloys were investigated. Later, research Table i.—Composition of Fused Silver-thallium Alloys Tested for Antifriction Properties Percentage Alloy No. of Thallium 1533...................... 0.48 1534.................... 1.06 a31 HT................... 2.04 231....................... 2.10 232 HT................... 3.83 Balance 232....................... 4.07 Silver 233 HT................... 5.86 a33....................... 6.38 a34....................... 9.84 a34 HT................... 10.07 was carried out on electroplating methods and diffusion processes. In preparing the fused alloyst care was taken to exhaust the toxic fumes caused by the thaillium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in, diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr207, 8 C.C. H2S04, and IOO C.C. H20. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475OC. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not iesiilt iii complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1946

By Norman P. Goss

What would appear to be a very simple process on paper has proved to be overrun with a multitude of unseen difficulties. For more than 70 years attempts have been made to cast metals in a continuous manner, but it has been only within the last Io years that some degree of success has been achieved.1 Historical Development Bessemer's Experiments—Method I Bessemer was the first to try to cast molten metal in a continuous manner. His method is fully described in U. S. Patent No. 49053, issued in 1865. The patent drawing is shown in Fig. I. In this method the molten metal was poured between a pair of rolls of large diameter, which were cooled by water sprays. Means were provided to prevent moisture from coming into direct coptact with the molten metal. The width of the strip was controlled by the flanges. On paper this should work to perfection, but it is beset with many difficulties still awaiting solution. Bessemer failed to reduce his invention to commercial practice. About 1890 Bessemer's method was revived by Norton and associates (U. S. Patent No. 441375). They formed the Fluid Metal Rolling Co. at Maywood, Ill., and spent $250,000 in endeavoring to develop the technique for this simple method. Finally they had to abandon it. Naturally, they did carry the technical development far beyond anything Bessemer had done, but even so it was far from being a useful commercial success. In recent years it has undergone further development by C. W. Hazelett (U. S. Patent No. 2058447), who has succeeded in obtaining long lengths of copper, brass, aluminum, and even stainless steel. He introduced many' ingenious devices but the greatest obstacle still remained—the disintegration of the roll surface when the surface is heated and chilled in rapid succession. Difficulty is also experienced in maintaining a uniform supply of molten metal to the rolls. The patents pertaining to this method would indicate these to be the major obstacles. Experimental work by Mellen—Method 2 A departure from the method introduced by Bessemer, was tried by Grenville Mellen, of East Orange, K. J., sometime between 1914 and 1920, who obtained a number of patents.2 His method is illustrated in Fig. 2. This method failed to make an impression upon the art; however, it is of value in pointing out the difficulties the inventor ran into and the way in which he tried to meet them. The split mold sections form two endless chains. When going through the center of the apparatus, these sections engage each other to form a complete mold. As the engaged mold section moves downward at a constant speed, molten metal is teemed into it. As this is going on, another set of cooperating mold sections move into position on top of the one being filled. The molten metal is teemed into the mold through a silica tube. According to the teachings of this patent, the level of molten

Jan 1, 1945

By Howard R. Keil

Reactor at Carlton mill successfully calcines pyrite-telluride flotation concentrate for cyanidation. CARLTON mill in the Cripple Creek district, 45 miles southwest of Colorado Springs, Colo., has been in operation for approximately three years, treating the custom sulpho-telluride ores formerly handled by the Golden Cycle mill in Colorado Springs. At the new mill the pyrite-telluride flotation concentrates have been roasted, prior to cyani-dation, in a Dorrco FluoSolids reactor, which has proved capable of yielding calcine readily amenable to cyanidation. Incoming ores are crushed at Carlton to % in. and sampled in 30 to 75-ton lots before the individual lots are mixed in the fine ore bin. The composite ore then goes to the grinding circuit. Classifier overflow from the grinding circuit is treated by flotation to produce a concentrate containing approximately 85 pct of the values in 5 pct of the weight. The flotation concentrate goes to the FluoSolids reactor prior to cyanidation. Cyanide solution values are recovered by zinc dust precipitation. Flotation tailings are thickened and cyanided, the values from this part of the circuit being recovered from solution by activated carbon. Gold values in the flotation concentrates consist of a small amount of finely divided metallic gold; the tellurides, sylvanite and calaverite; and gold very intimately associated with the pyrite. The metallic gold and a part of the telluride values can be extracted from the concentrates by cyaniding without roasting. However, extraction on the tellurides by this method is not satisfactory, and the pyrite values are so intimately associated with the pyrite that very fine grinding and cyanidation for a prolonged period under ideal laboratory conditions does not yield good recovery. Upon roasting, the tellurides are oxidized to very finely divided metallic gold which is readily soluble in cyanide. The pyrite is oxidized mainly to a porous iron oxide which allows cyanide solution to penetrate to gold particles and take them into solution. Feeding the Reactor Flotation concentrates move by gravity to a thickener. Thickener underflow is discharged at approximately 60 pct solids, by means of a diaphragm pump, into a storage and blending agitator. From here the concentrates are pumped to a disc filter. The filter cake, at 84 to 88 pct solids, drops directly into a repulper where it is repulped into a slurry of 78 to 80 pct solids. The repulped filter cake flows into a 6x6-ft slurry agitator from which it is fed directly into the reactor by the Moyno pump. The Moyno pump has eliminated a large number of difficulties that were first encountered in feeding a wet concentrate to the reactor. On the original installation in Canada a screw feeder was used to introduce the filter cake directly into the reactor. Since the reactor is under a slight positive pressure it was necessary to have a suitable seal to prevent gas escaping from the reactor at this point. When the concentrates produced in flotation were coarse or granular they could be readily fed to the reactor but when fine-textured, clayey concentrates were produced a great deal of trouble was encountered.

Jan 1, 1955

By W. Julian Patron

TREATMENT of the breaker wash-water discharges to remove the suspended particles of finely divided material is usually most efficiently and economically accomplished in settling or thickening tanks. The purpose of these tanks is to separate the excess water from the solids by sedimentation whereby the solid particles suspended in the water are thickened by the force of gravity. The water overflowing these tanks is either reused for coal cleaning or discharged directly to the streams. The settled solids, which are in a relatively concentrated condition, forming a sludge or thick pulp, can be disposed of by pumping to a storage dam, by slushing into mine workings, by processing for recovery of coal, or filtering by vacuum or centrifugal means and discharging with the breaker refuse. The scope of this paper will be limited to the discussion of settling and thickening equipment, the factors that influence the settlement of solids, and a brief description of tests that can be made to determine the size of settling facilities required for any particular condition. The practical application of sedimentation to the treatment of coal falls into two groups, one of classification or hydro- separation, and the other of clarification and thickening. Classification may be employed to prepare a relatively low- grade fuel, which can be used as is or can be further processed separately. Clarification and thickening is employed where the primary objective is to recover a relatively dewatered solid and return a satisfactorily clear water to breaker or streams. When a stream of water flows across a tank, the time required for a particle to travel from the feed inlet to the overflow must be a little greater than that required for the finest particles or flocs in the feed to settle out of the stream. OPERATION AND TYPES OF SETTLING EQUIPMENT Theoretically, the liquid in a settling tank should rise at a more or less constant rate throughout the area of the tank Under these conditions the rising velocity of the water must be less than the settling rate of the finest particles if clarification is to be obtained. When classification of particles is to be made in the tank, the overflow velocity must be greater than the settling velocity of the particles that are to be removed with the tank overflow. The performance of a settling tank, then, depends on the settling rate of the solids and the current velocities in the tank. The oldest types of sedimentation employ intermittent types of settling tanks of any convenient shape. Means are provided for filling the tank with pulp and allowing it to settle until quiet, for moving the clean liquor and for removing the thickened sludge. The operation is necessarily intermittent but a sufficient number of tanks is employed so that a continuous flow of clear water is maintained. Continuous methods for the sedimentation of slurries were developed in the metallurgical industry. Cones from which settled solids were discharged by gravity

Jan 1, 1946

By W. Julian Parton

Treatment of the breaker wash-water discharges to remove the suspended particles of finely divided material is usually most efficiently and economically accomplished in settling or thickening tanks. The purpose of these tanks is to separate the excess water from the solids by sedimentation whereby the solid particles suspended in the water are thickened by the force of gravity. The water overflowing these tanks is either reused for coal cleaning or discharged directly to the streams. The settled solids, which are in a relatively concentrated condition, forming a sludge or thick pulp, can be disposed of by pumping to a storage dam, by slushing into mine workings, by processing for recovery of coal, or filtering by vacuum or centrifugal means and discharging with the breaker refuse. The scope of this paper will be limited to the discussion of settling and thickening equipment, the factors that influence the settlement of solids, and a brief description of tests that can be made to determine the size of settling facilities required for any particular condition. The practical application of sedimentation to the treatment of coal falls into two groups, one of classification or hydro-separation, and the other of clarification and thickening. Classification may be employed to prepare a relatively low-grade fuel, which can be used as is or can be further processed separately. Clarification and thickening is employed where the primary objective is to recover a relatively dewatered solid and return a satisfactorily clear water to breaker or streams. Operation and Types oF Settling Equipment When a stream of water flows across a tank, the time required for a particle to travel from the feed inlet to the overflow must be a little greater than that required for the finest particles or flocs in the feed to settle out of the stream. Theoretically, the liquid in a settling tank should rise at a more or less constant rate throughout the area of the tank Under these conditions the rising velocity of the water must be less than the settling rate of the finest particles if clarification is to be obtained. When classification of particles is to be made in the tank, the overflow velocity must be greater than the settling velocity of the particles that are to be removed with the tank overflow. The performance of a settling tank, then, depends on the settling rate of the solids and the current velocities in the tank. The oldest types of sedimentation employ intermittent types of settling tanks of any convenient shape. Means are provided for filling the tank with pulp and allowing it to settle until quiet, for moving the clean liquor and for removing the thickened sludge. The operation is necessarily intermittent but a sufficient number of tanks is employed so that a continuous flow of clear water is maintained. Continuous methods for the sedimentation of slurries were developed in the metallurgical industry. Cones from which settled solids were discharged by gravity

Jan 1, 1947

By W. Julian Parton

Treatment of the breaker wash-water discharges to remove the suspended particles of finely divided material is usually most efficiently and economically accomplished in settling or thickening tanks. The purpose of these tanks is to separate the excess water from the solids by sedimentation whereby the solid particles suspended in the water are thickened by the force of gravity. The water overflowing these tanks is either reused for coal cleaning or discharged directly to the streams. The settled solids, which are in a relatively concentrated condition, forming a sludge or thick pulp, can be disposed of by pumping to a storage dam, by slushing into mine workings, by processing for recovery of coal, or filtering by vacuum or centrifugal means and discharging with the breaker refuse. The scope of this paper will be limited to the discussion of settling and thickening equipment, the factors that influence the settlement of solids, and a brief description of tests that can be made to determine the size of settling facilities required for any particular condition. The practical application of sedimentation to the treatment of coal falls into two groups, one of classification or hydro-separation, and the other of clarification and thickening. Classification may be employed to prepare a relatively low-grade fuel, which can be used as is or can be further processed separately. Clarification and thickening is employed where the primary objective is to recover a relatively dewatered solid and return a satisfactorily clear water to breaker or streams. Operation and Types oF Settling Equipment When a stream of water flows across a tank, the time required for a particle to travel from the feed inlet to the overflow must be a little greater than that required for the finest particles or flocs in the feed to settle out of the stream. Theoretically, the liquid in a settling tank should rise at a more or less constant rate throughout the area of the tank Under these conditions the rising velocity of the water must be less than the settling rate of the finest particles if clarification is to be obtained. When classification of particles is to be made in the tank, the overflow velocity must be greater than the settling velocity of the particles that are to be removed with the tank overflow. The performance of a settling tank, then, depends on the settling rate of the solids and the current velocities in the tank. The oldest types of sedimentation employ intermittent types of settling tanks of any convenient shape. Means are provided for filling the tank with pulp and allowing it to settle until quiet, for moving the clean liquor and for removing the thickened sludge. The operation is necessarily intermittent but a sufficient number of tanks is employed so that a continuous flow of clear water is maintained. Continuous methods for the sedimentation of slurries were developed in the metallurgical industry. Cones from which settled solids were discharged by gravity

Jan 1, 1947

By C. M. Signer, W. P. Hewitt

THIS is a story of a mine discovered in the days of the Conquistadores but that remained unimportant until the second decade of this century. Without the usual legendary history of romance and fabulous riches it has become famous for the development of unexpected metals and unusual problems. These developments and experiences, exciting and interesting as any legend, are the substance of the San Antonio mine of the Santa Eulalia district in northern Mexico. Originally opened for its silver-lead content, it developed a tin deposit of singular economic importance and unique geologic interest, a vanadium orebody that for a few years placed it among the leading vanadium producers of the world, and now lead and zinc sulphide ores. It has been the seem of a disastrous flood that brought deep-sea divers into Mexico's desert mountains and raised important problems regarding ground water, demanding unusual measures. Geology and operating questions relating to the above matters will be discussed and much of it is recent history which has become a part of Mexican mining lore. History Dates Back to 1325 Santa Eulalia is the oldest of American cities, founded in 1325 by the Aztecs under the name of Tenochtitlan and devastated in 1521 by Cortes and his rapacious band of iron-willed adventurers. Their lust for gold burned through the Aztec empire and onward into most of North America. Santa Eulalia was in the path of conquest. In 1591 the district's first ore discovery was made near what is now the San Antonio mine. The ores carried no gold and the silver-lead content was unattractive to the early pioneers. Not until 1700 was real mining activity undertaken.

Jan 1, 1952

By C. J. Osborn

The temperature dependence of the free energies of formation of metallurgically important oxides, sulphides, chlorides, carbonates and sulphates is presented graphically, whereby the task of deriving practical metallurgical information is greatly simplified. The diagrams have been revised according to the latest available thermodynamic data. WHILE it is true that much careful investiga-tional work remains to be done, there are already available in the literature sufficient thermo-dynamic data to enable the metallurgist to predict with reasonable confidence the equilibrium conditions to be expected in most important, and potentially important, metallurgical reactions. In this connection, the careful, critical compilations of K. K. Kelley and his collaborators in numerous U. S. Bureau of Mines Bulletins are particularly valuable. However, the translation of reliable thermo-dynamic data into metallurgical language unfortunately involves lengthy manipulations of the cumbersome formulas which can be set up from heat of formation, entropy, and heat capacity data. Many years ago, Kelley20 predicted that thermo-dynamic calculations would be made in the future "with the aid of free energy, heat content, and entropy tables, rather than by means of the algebraic methods employed at present", and where such tables are available they greatly simplify the task of deriving practical metallurgical information. However, in addition to these tables, there are also available one or two reliable graphical presentations, particularly of free energy data, which may be used in the same way as the tables, but which have the added advantages that interpolation is never necessary, and that the behavior of different metals or compounds may be compared at a glance. Some years ago Professor Robert Lepsoe, Head of the Department of Metallurgy at Norways Institute of Technology (N.T.H.), began a compilation of curves showing the temperature dependence of the heat contents of the elements, and the heat contents and heats and free energies of formation of the common metallurgical compounds. With such a compilation, the thermal and free energy requirements of a reaction may be read from curves in a matter of seconds; and this statement applies not only to the formation of compounds from their elements, and to the reverse dissociation, but to any reaction involving substances whose thermodynamic properties are available. This follows from the fact that heats and free energies of formation are completely additive. For example, the free energy change associated with the chlorination of a metallic oxide at any temperature, T, is given by the free energy of formation of the chloride at temperature T minus that of the oxide also at T; both of these quantities may be read directly from curves of the type suggested above. Since this early, unpublished work of Lepsoe, both Ellingham7 and Richardson and Jeffes46 have

Jan 1, 1951