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By N. Tiner

THE mechanical properties of magnesium-alloy castings are greatly improved by grain refinement, and at present considerable attention is being paid to methods of obtaining fine-grained castings. One method of achieving this end is the use of proper melting and superheating techniques. These have been employed commercially to a great extent, but no comprehensive study of the subject appears to have been published at present. Numerous investigations found in the literature include some reference to superheating techniques, 1-4 and Achenbach, Nipper and Piwowarsky,5 based principally on thermal analysis, ascribe the grain-refining action of superheating to the influence of solid foreign particles or dissolved gases present in the melt upon the course of crystallization. The primary purpose of this paper is to present the principal facts concerning the effect of superheating on grain size of magnesium alloys. Attempts are also made to explain the experimental results in terms of a general hypothesis. The investigations are limited chiefly to common commercial casting alloys. In order to carry on this work, it was necessary to determine the factors influencing grain size and to develop a proper technique for the preparation of samples. The preliminary tests made by the author indicated that the grain size of magnesium alloys resulting from the solidification of a melt is determined by alloy composition, presence of impurities, rate of cooling during solidification, thermal history of the melt and to some extent the structure of the charge used. The rate of cooling is in turn dependent upon the mass of the melt, pouring temperature, and dimensions, properties and temperature of the mold into which the melt is poured. The final grain size of the alloys is still further modified by heat-treatment subsequent to casting. It is not within the scope of the present paper to discuss all of these factors, and it would suffice to note here that when equal amounts of magnesium alloys are prepared from the same alloying materials, melted in graphite crucibles under the same thermal conditions, then cast into graphite molds at a constant temperature, the .resultant solids have the same grain size. By maintaining all other factors constant, it is thus possible to vary thermal conditions of a melt and to examine the grain size of resultant castings. PREPARATION OF SAMPLES AND GRAIN-SIZE TESTING The alloys investigated in this paper were taken from ingots made by Permanente Metals Corporation or prepared by the author with pure carbothermic magnesium and necessary alloying elements. Melting was carried out under a flux in a graphite crucible heated uniformly by an

Jan 1, 1945

By Joe B. Alford

Founding of the Institute The advance of population and civilization in the U. S. moved through the woodlands of the East, and reached the edge of the great central plains about the middle of the nineteenth century. There the advance paused for almost a generation - ahead were vast reaches of prairie country, uncharted, forbidding, and populated by hostile tribes of the native Indians. The turmoil of the Civil War, and the readjustments following it, further delayed the advance. By about 1870, the Nation was becoming stabilized again, the conflict with the Indians was closing, and the pressure of growth was forcing population to resume its westward movement. In addition to geography, the Nation had another frontier: the development of its immense natural resources. Conditions of the time brought into sharp focus the need for coal, iron, steel, gold, silver, and other minerals. The application of engineering and science was necessary for the production of these minerals and their manufacture into products to meet the needs of a growing nation. The requirements of the time were eloquently expressed in a paper by AIME member Edmund C. Pechin in 1872 : We find, the world over, the most intense activity everywhere displayed in enterprises requiring prodigious quantities of iron. Railways of colossal magnitude are projected. . . . The growing scarcity of timber is compelling the use of iron in buildings; bridges of wonderful size and strength; huge ocean steamships; barges and boats for lake and river traffic; churches; cars, and thousands of minor articles of every shape and size. . . . The time has come when scientific research is to assume its true position - the day of "sheer force and blind stupidity," whose only protection is a high tariff, has gone forever . . . the physicist, the geologist and mineralogist; the chemist, the engineer, are as essential to success as the [blast] furnace itself. . . . There is no merely practical man, no matter how varied may have been his experience, or how long his practice, that will not benefit from the results of scientific investigation. That there is a growing sense of the importance of having thoroughly prepared scientific men in every department of business is evidenced by the institutions [of learning] that are springing up in different quarters, provided with

Jan 1, 1971

By J. J. Arps

n approach to the study of the electrical properlies of drilling muds, their cakes and their filtrates was made by treating the drilling fluid as a porous medium. Lluring this study it was found that the weight pararneter was omitted from previous investigations on electrical properties. Patnode in 1949 made a similar approach to ,his investigation. His work showed that there was a variation of resistivity relationships with per cent Puid present in a given suspension. This present study ex-tends Patnode's investigation to one in terms of the solids fraction of the drilling fluids. Previous investigations were made on low weight muds where the effect of the rolids fraction was obscured. The following equationr were fitted to data taken from 94 field muds and 47 laboratory muds (see Tables I and 2). The parameter, C, is a complex function of the solidr content, or mud weight, of a drilling fluid. It was also found that for all drilling muds examined. A nomograph is presented combining Eqs. I and 2. INTRODUCTION It is generally recognized that the materials present in drilling muds affect the relationship between mud filtrate and mud resistivities. However, most electric log interpretations proceed with the assumption that the mud resistivity and temperature are the only important parameters needed to obtain a filtrate resistivity or a mud cake resistivity. Lamont1 suggests that only average relationships exist between mud cake, mud filtrate and mud resistivities. He indicates that there is limited accuracy when these intercorrelated factors are used since no other measure-able variable is apparent. A previous paper by Patnode indicates that drilling fluids may be considered to be a system of fluids in solid particles which may be correlated electrically in a manner similar to rock solids. 1 he equation for the resistivity factor. F = (per cent fluid) is satisfied for a given clay type in water, but the value of m varies as different materials are used in the water. The resistivity factor is not constant for a given amount of clay. As is suspected it varies as the solids fraction conducts electrical current. Since both weighting material and clay solids are present in commonly used drilling fluids, it is expected that both materials contribute to the variation of the m factor in Eq. 3. An extension of Patnode's work is presented in this paper to show some of the interrelations which exist between the resistivities of mud cake, mud filtrate and mud. Use of these data enable a more accurate calculation of mud filtrate and mud cake resistivities if only the mud resistivity and weight are measured. EXPERIMENTAL The measurements of mud weight, fluid and solids resistivity, alkalinity, and chloride content of mud samples were made in this research. Mud samples representing drilling fluids from 94 Louisiana and Texas wells (Table 1) and 47 laboratory-constructed systems (Table 2) were used in the experimentation. The measurements of the mud properties were made both in the field and in the laboratory. The tests on the properties of weight, alkalinity and chloride ion were standard tests as described by API specifications. The resistivity measuring devices were constructed in the laboratory for this study. For details on the resistivity equipment see Fig. 1. The fluid cell

By C. A. Stout, S. W. Nicksic

The materials that stubilize emulsions of some Southern California crude oils were isolated from the produced crude. These substances were separated into acidic and nonionic fractions by ion exchange chromatography. Each fraction was further broken into groups of homogeneous molecular weight composition by gel permeation chromatography. Both ionic character and molecular weight of the individual fractions are reflected in the properties of the original crude oil emulsion. Specifically, the more acidic and the higher molecular weight fractions appear to be the most effective stabilizers. INTRODUCTION The treatment of oilfield emulsions is a continuing problem for the oil industry. In almost all cases, these are water-in-oil emulsions. Much more is known about the formation and stabilization of oil-in-water (O/W) emulsions than of the water-in-oil (W/O) type. To understand W/O emulsions, more information is needed on the materials responsible for their formation and stabilization. This is especially true in the case of oilfield emulsions where the stabilizing materials are complex mixtures of large asphaltene-like molecules. To study the chemical and physical properties of these emulsion stabilizers, it is necessary first to separate them from crude oil. This separation was achieved in the case of two Southern California crude oils. The materials that were isolated appear at first to be little different from an asphaltene mixture. However, if a mixture of distilled water and mineral oil containing about 1 percent of the natural emulsion stabilizers is passed through a colloid mill, the W/O emulsion formed may be stored in the laboratory for many months without any sign of breaking. This could not be done using undifferentiated asphaltenes from the same wells, indicating that there is a real difference between these materials and ordinary asphaltenes. The colloid mill used to generate the emulsion was required because tile natural emulsion stabilizers had very little effect on oil-water interfacial tension. The one characteristic — complexity of composition — that emulsion stabilizers share with asphaltenes makes virtually impossible the exact structure determination of the components of the mixture. For this reason, it was decided to investigate first the influence of molecular weight on the ability of these materials to stabilize emulsions. The emulsion stabilizers were first separated into acidic and neutral fractions according to whether or not the material was retained on a weakly basic ion exchange column. The extraction procedure was not designed to remove basic components from tile oils, and no attempt to isolate such a fraction was made. Following this separation, selected fractions were analyzed by gel permeation chromatography. Gel permeation separates according to molecular size, largely independently of chemical or polar characteristics. A heterogeneous mixture is separated into a number of fractions having much more homogeneous molecular weight distribution. A number average molecular weight of each fraction is therefore close to the true molecular weight of the principal component of that fraction. The fraction weights, expressed as weight percent of the sample, and the number average molecular weight of a representative selection of the fractions, will be referred to in this paper as the molecular weight profile of the original sample. DESCRIPTION OF GEL PERMEATION ANALYSIS The first reported gel permeation analyses were for separating partially hydrolyzed protein molecules in an aqueous system using expanded starch granules. Most of the theoretical work on gel permeation has been done by biochemists.1 This theoretical treatment is still incomplete, but the

Jan 1, 1969

By O. R. Bergmann

Two approaches were taken to obtain direct experimental evidence jar the existence oj a jet in the explosion-cladding pvocess: 1) direct observation of the claddirg jwocess by rtzeans ojf kig-h-speed photography using a fvartziiy catnera and 2) use of a plated-surface experiment in contribution with clzetrzical analysis. The framing-camera records showed clearly the presence of a jet it1 the form of what appears to be a line spray. The jet velocity is considerably highev than the detonation velocity arid in vacuum it is almost twice as high as the detonatiou velocily. The results jrorrz the plated-surface experiment also corzfivtned the preseizce of- a jet. The artzoutlt o,f etzergy dissipated in the jetting process was foundd lo be consislent with the basic theovetical model o/ the cladding mechanism.. MaNY reports on metal working with explosives have appeared in the literature during the last few yearsThis paper describes experiments concern- ing the mechanism of the explosive metal-cladding process. It has become increasingly important as a unique method for bonding metals and a typical cladding arrangement is shown in Fig. 1. A theoretical analysis of the mechanism of explosive bonding and a description of the nature and types of bond zones obtained was given by Cowan and oltzman." A further discussion of the basic principles of the process, a detailed description of the different bond-zone types, and extensive information on the properties and the applications of explosively bonded metals was recently published by Holtzman and cowan. " The process is now in commercial use by E. I. du Pont de Nemours & Co. The concept of the existence of a jet during metal bonding with explosives forms a central part in the theoretical analysis of the cladding mechanism described by Cowan and Holtzman When a layer of explosive is detonated on a metal plate that is separated from a second metal plate by a small distance the metal plate in contact with the detonating explosive is accelerated by the detonation pressure. An angle is established between the undeflected and deflected portions of the plate. Subsequently the deflected portion of the first plate collides with the second metal plate.

Jan 1, 1967

By F. Keller, J. D. Edwards

The anodic treatment of aluminum presents problems of scientific as well as of commercial interest.l-3 Of particular interest is the fact that, during the anodic oxidation process, the oxide continues to form at the metal-oxide interface under any oxide previously formed. This has led to speculation as to the mechanism involved in the formation of the relatively thick oxide coatings that are used commercially for decorative or protective purposes. Furthermore, the ability of certain types of oxide coatings to adsorb dyes and other substances has stimulated research to determine the actual structure of these adsorptive coatings. It has been found that anodic oxide coatings on aluminum are composed essentially of aluminum oxide. They are formed by the action of oxygen ions penetrating to the metal surface during the electrolytic oxidation treatment. These coatings can be formed in a number of different electrolytes, as for example, those which contain sulphuric acid, chromic acid, oxalic acid, or boric acid. These are the commonest and most useful electrolytes employed commercially. Except for certain specific conditions of formation, the coatings in general have been found to be amorphous alumina, as far as can be determined by X-ray or electron-diffraction methods. Anodic oxidation processes can be arranged in three rather general classes if they are grouped in relation to the solvent action of the electrolyte on the coating.4 In the first class, the electrolyte has little or no solvent action on the coating that is formed. In general, coatings produced under such circumstances are nonporous and non-adsorptive. In the second class, the electrolyte exerts an appreciable solvent action on the coating. These coatings are porous and adsorptive. Finally, for the third class, the electrolyte tends to dissolve the coating about as rapidly as it is formed. This action produces electrolytic brightening or anodic polishing of the aluminum surface and at most leaves only a very thin film of oxide. The nonporous and nonadsorptive type of oxide film is represented by the coatings that are formed when solutions of boric acid are employed as the electrolyte. It is especially significant that these impervious films are formed in electrolytes that exert little or no solvent action on the coating. Where a boric acid electrolyte is used, the coating tends to form rapidly, with the result that the flow of current is soon reduced to substantially zero. This indicates that the growth of the coating has stopped. As a rule, the thickness of the coating is roughly proportional to the voltage employed for formation and the coatings of this type are exceedingly thin. In an electrolyte of this type, the coating has a high resistance when the aluminum is made anode; consequently, any current that may flow (leakage current) is very

Jan 1, 1944

By F. Keller, J. D. Edwards

The anodic treatment of aluminum presents problems of scientific as well as of commercial interest.l-3 Of particular interest is the fact that, during the anodic oxidation process, the oxide continues to form at the metal-oxide interface under any oxide previously formed. This has led to speculation as to the mechanism involved in the formation of the relatively thick oxide coatings that are used commercially for decorative or protective purposes. Furthermore, the ability of certain types of oxide coatings to adsorb dyes and other substances has stimulated research to determine the actual structure of these adsorptive coatings. It has been found that anodic oxide coatings on aluminum are composed essentially of aluminum oxide. They are formed by the action of oxygen ions penetrating to the metal surface during the electrolytic oxidation treatment. These coatings can be formed in a number of different electrolytes, as for example, those which contain sulphuric acid, chromic acid, oxalic acid, or boric acid. These are the commonest and most useful electrolytes employed commercially. Except for certain specific conditions of formation, the coatings in general have been found to be amorphous alumina, as far as can be determined by X-ray or electron-diffraction methods. Anodic oxidation processes can be arranged in three rather general classes if they are grouped in relation to the solvent action of the electrolyte on the coating.4 In the first class, the electrolyte has little or no solvent action on the coating that is formed. In general, coatings produced under such circumstances are nonporous and non-adsorptive. In the second class, the electrolyte exerts an appreciable solvent action on the coating. These coatings are porous and adsorptive. Finally, for the third class, the electrolyte tends to dissolve the coating about as rapidly as it is formed. This action produces electrolytic brightening or anodic polishing of the aluminum surface and at most leaves only a very thin film of oxide. The nonporous and nonadsorptive type of oxide film is represented by the coatings that are formed when solutions of boric acid are employed as the electrolyte. It is especially significant that these impervious films are formed in electrolytes that exert little or no solvent action on the coating. Where a boric acid electrolyte is used, the coating tends to form rapidly, with the result that the flow of current is soon reduced to substantially zero. This indicates that the growth of the coating has stopped. As a rule, the thickness of the coating is roughly proportional to the voltage employed for formation and the coatings of this type are exceedingly thin. In an electrolyte of this type, the coating has a high resistance when the aluminum is made anode; consequently, any current that may flow (leakage current) is very

Jan 1, 1944

By M. H. Loveman

THE orebody described below has been rediscovered and developed within the last 3 years. It has, however, been known and worked by the Chinese for hundreds of years. When assay values and size are considered, it contains what is probably one of the largest single bodies of zinc and lead sulphides yet found. The tonnages developed at other places, as at Broken Hill, are much greater but the average zinc and lead sulphide contents are considerably lower than at Bawdwin. Bawdwin is situated in the semi-independent State of Tawng Peng, one of the numerous units which make up the Northern Shan States. These States are under British rule and are generally considered as a portion of Burma. They are governed as a separate administrative unit, however, under the Lieutenant Governor of Burma. Each State is under its own chief, or Sawbwa, who has considerable power over his own subjects. Bawdwin is approximately in latitude N 23°6', longitude E 97°20', about 50 miles south of the nearest point on the Chinese border and 450 miles north of Rangoon (Fig. 1). The period at which mining was first begun at Bawdwin is unknown. The most reliable records have been obtained by deciphering local Chinese inscriptions and from these it is concluded that the work dates back to at least the beginning of the 15th century. The first undoubted reference to the mines by a European is by Symes in 1795. Crawford in 1827 estimated the output of silver from the mines at $600,000 annually. At about the middle of the 19th century the rebellion of the Chinese Mohammedans in the neighboring Chinese province of Yunnan so weakened the power of the Chinese that the incursions of hostile tribes (Kachins) made work extremely dangerous. The mines were finally abandoned by the Chinese about 1868. The closing down of the mines was probably not entirely due to outside causes but may have been influenced somewhat by the increasing difficulty of handling the water, as the workings gradually descended below the water level of the district. Several attempts were made by the Burmese kings, Mindon Min and Thebaw, to resume operations, but because of a

Jan 12, 1916

By J. Paone, S. Tandanand

This paper studies the behavior of rock at the initial state of crater formation resulting from stresses created under a drill bit. The purpose of this study is to determine which mechanical properties of rock are important in rock fragmentation by drilling. Although a definite relation between the drilling strength and relevant mechanical properties has not been established, maximum yield strength or hardness of rock is apparently a parameter of drillability of rock. The strengths of rock were considered from the Mohr-Coulomb criterion from which the surface of failure was constructed. The results from previous triaxial tests on Solenhofen limestone were adopted in establishing a limit of failure. Inelastic behavior of Solenhofen limestone was observed under a low velocity impact of a hemispherical bit and under static indentation with a similar bit. Permanent set at low applied loads in the indented area was measured with an interferometric technique. A quantitative determination of strengths of the rock was made under static indentation. The maximum yield strength estimated from the average stress over the contact area for plastic deformation was used as the crushing strength of rock under a drill bit. Much research has been done on energy requirements and mechanisms of energy dissipation to perfect rock fragmentation by a drilling process. But more needs to be done. More needs to be known about the mechanisms of energy dissipation or failure criteria of rocks in the drilling process in order to evaluate the efficiency of energy requirements in specific rock fragmentation. This paper examines some published studies on rock failure and energy dissipation and presents some findings in that phase of research concerned with rock fragmentation by drilling. This work is specifically concerned with rock behavior at an early stage of failure induced by a concentrated load. Consideration is limited to the primary phase of the crater formation under drill bit, i.e., before chipping takes place. Failure Phenomena of Rocks: Failure of rocks can be classified into two types, fracture and plastic flow. Both involve separation of material to form new surfaces with complete or partial loss of cohesion. Fracture is further classified as extension (or cleavage) fracture and shear fracture. Extension fracture involves separation in a plane without shear stress component, while shear fracture involves slippage along a plane as a result of combined stresses. Then, shear fracture inclines to the axes of the principal stresses. Plastic flow occurs under combined stresses, especially at high confining pressure and temperature, and denotes macroscopically irrecoverable deformation of rocks. Flow mechanisms have been classified as in-tergranular failure, intragranular gliding, and re-crystallization of mineral constituents.6 Failure phenomena in rocks are complicated because they include fractures and plastic flow as well as a friction process developed intrinsically as the internal stresses increase. All can occur in one rupture process, depending on the varying stress conditions. Both fracture and plastic flow are encountered in rock drilling. Rock failure under a drill bit as observed in drop tests simulating a single blow of a percussion drill, consists of two types, crushing and chipping. Crushing is considered as a separation of material particles by many fractures resulting from the application of high compressive stresses exceeding the strength of rock at the contact area. Chipping results from subsurface fractures extended to the face surface; this phase is preceded by crushing or surface deformation. The state of stress under the drill bit and the strength of rock create and control these two types of failure. The state of stress under the bit and in the vicinity of the contact area depend on the bit configuration and the magnitude of applied force. The strength of rock, characterized by its ability to resist penetration, depends on its composition and structure. However, the term "strength" quantitatively defined, is still ambiguous and may or may not correspond to the tensile, compressive and shear strength obtained from simple tests. Rock Failure Criterion: Rocks are weak in tension, their tensile strength being many times less than their compressive strength. This characteristic excludes

Jan 1, 1967

AT THE beginning of February the British Government announced acceptance of the American terms for funding the war debt, the main features-being as follows: Interest rate of 3 per cent. for the first 10 years and then 3 ½ per cent. up to the final extinguishment of the debt at the end of 62 years. The interest from the time since the loans were made to the actual beginning of the funding arrangement to be recomputed at 4 1/4 per cent. instead of the 5 per cent. rate now in effect. Congress ratified the contract respecting the British debt. The ship subsidy bill was relegated to the rear, which is indeed an end to the project. The natural consequence of this will be a liquidation of the Govern-ment's shipping business. The joint committee on the reorganization of Govern-ment departments made its report to the President. In general this seems to offer a well-considered plan for the coordination of Government service. The pro-posals respecting the bureaus that are particularly associated with the mining industry may be subject to criticism. According to the committee's plan, the Geological Survey remains in the Department of the Interior, but the Bureau of Mines and the compilation of the statistics of mineral production are transferred to the Department of Commerce. The Lausanne conference among the European powers came to an end early in February, without any treaty having been signed, owing to the refusal of the Turks to accept the ultimatum of the Allies. Theoreti-cally this left conditions in a state-of war between the Allies and Turkey. However, no actual movements have resulted. The French and Belgians continued to hold the Ruhr district of Westphalia, extending their lines and administration of the region. The Germans adhered to the policy of passive resistance. In the Parliament of Great Britain the French and Belgian policy was plainly declared to be unwise and dangerous. French and Belgian industries, moreover, were troubled by strikes among their own coal miners for higher wages. The Poles and Lithuanians engaged in border war-fare;. the civil war in Ireland continued. The rest of the world was quiet insofar as military operations are concerned.

Jan 2, 1923

By Joseph Jensen

Recent developments related to petroleum engineering discussed in this paper are: 1. Drilling wells in with oil or the use of chemical compounds or (Imud solvents" for removing rotary mud from wells in order to increase or make possible oil production. 2. Comparison of results of electrical logging methods in locating water, as shown in a recent test on a well in the Los Angeles Basin. 3. A new method for logging formations through casing, known as the Stratagraph. Drilling Wells in with Oil or the Use of Chemical Compounds or Mud Solvents During the time that the California fields showed high gas pressures, the pressure of the gas within the formation was sufficiently great to break down the mud wall or cake formed while the well was drilling. That this did not always occur was demonstrated by the fact that in some of the older fields new wells sometimes had substantially higher initial productions than other wells near by. The explanation seemed to be that some sands were mudded off in the original drilling. Their pressure was then not great enough to break down the mud wall in competition with the higher pressure of the sands, but the situation reversed itself so that a later well benefited by the pressure in these originally weaker sands. As time passed, in wells deeper than 5000 ft. the difficulty of bringing wells on production became more pronounced. This led to a hunt for substitutes, of which a number have been tried. The one that has proved most successful in our experience at Ventura is known as the Nobs solvent. At well No. 1 of the Associated-Ventura Land & Water Co. when it was recompleted in February 1936, about 10 days were spent in trying to bring the well in in the regular manner, but only about 113 bbl. of water could be swabbed from the well, and even this quantity decreased as time passed. The Nobs solvent was spotted in the bottom of the hole opposite the perforations, inverted Guiberson swab rubbers were used on the drillpipe and the hole was down-swabbed in stages, beginning

Jan 1, 1937

By S. C. Schaeker, A. W. Schlechten, A. H. Larson

PARRAVANO and Malquori' studied the equilibrium of H2S-Hz with molybdenum and its lowest sulfide which they believed to be MoS2. Mc Cabe' has shown that its composition is actually Mo2S3 and determined its dissociation pressure by means of Knud-sen effusion measurements. Stubbles and Richard- son3 have recently studied the equilibrium of gas mixtures of H2S-HZ with the two-phase solid mixtures of Mo-MozS3 and Mo2S3-MoS2. The latter investigators found that M02s3 deviated slightly from the stoichiometric composition, but they did not determine the homogeneous region of the disulfide phase. Morimoto and Kullerud, studied the Mo-S system by quenching, microscope, and X-ray methods and concluded that the disulfide is stoichiometric. The present investigation was concerned with the measurement of the sulfur vapor pressure variation with composition at 1100°C in the homogeneous region of "MoS2". These measurements were made by reacting: 1) molybdenum powder (99.97 pct Moj with sulfur vapor, and 2) MoS1.g9 (formed by reaction of Mo + H2S) with sulfur vapor in a quartz capsule. Conditions were controlled to form an equilibrated phase within the homogeneous region of the disulfide. The quartz capsule was sealed off initially under a vacuum and the residual gases were gettered by titanium powder contained in one end of the capsule. A mixture of Mo + S or MOS,., + S was in the other end. The section containing the titanium powder was heated for 24 hr at 700°C and then removed by flame sealing. The end of the capsule containing the charge was then heated to 1100°C. The other end of the capsule was maintained at a temperature which would produce the desired sulfur pressure in the capsule (liquid sulfur distilled from the charge mixture was retained in this end). After equilibration, the capsule was removed from the heating assembly and rapidly air-cooled. It is assumed that equality existed between the total sulfur pressures (PT) in the two ends of the capsule and not between the partial pressures of the different molecular species (S, SZ, Three separately controlled heating elements were used to maintain the proper temperature gradient over the length (approximately 12 in.) of the capsule. A thermocouple-Wheelco "Capacitrol" system was used for temperature control of the two end heating elements within 2"C. The center heating element was controlled directly by a " Power -stat". Separate controlling and measuring thermocouples were used for both end heating elements. Pt-Pt(l0 pct Rh) thermocouples were used for 1100°C and Chromel-Alumel thermocouples were used for lower-temperature control and measurement of the assembly. Silver foil was wrapped around the end of the capsule containing the liquid sulfur to insure a constant temperature zone. The thermal gradient over the entire length of the capsule was measured to: 1) ascertain that the length of the constant temperature zone of the liquid-sulfur end and the sulfide end was sufficient, and 2) ascertain that the liquid-sulfur zone was the zone of lowest temperature. The data obtained in this investigation are shown in Fig. 1 and Table I. The total sulfur pressure (PT) and p(S2) were calculated from the data of Braune et UZ.~ The compositions of the equilibrated disul-

Jan 1, 1964

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

By Henry Fay

THE erosion of guns is a complex problem which can be solved only by a detailed study of all the factors involved. In the present paper it is proposed to submit the results of observations and experiments which have extended over several years. Certain facts have been established and preliminary reports have been published.' Conclusions have been reached since then which, it is believed, are worth presenting for the purpose of promoting discussion, and with the hope that ultimately the whole truth will be known. The particular phase of the problem which will be presented here is the hardening of the inner surface of the gun tube. It has been known for a long time that after firing a large caliber gun for some time, the surface of the metal becomes hard and brittle, cracks, and wears away.2 The character of this phenomenon may be learned by an examination of some results which are typical, obtained from a detailed study of a 12-in. gun. The gun was trepanned and rings representing various sections of the gun were cut out for examination. The first ring represented the metal at the muzzle end, and the other rings were removed at approximately 120, 240, 325 and 337 in., respectively, toward the breech end. The appearance of the surface of the metal in the different sections is shown in Fig. 1. The greatest amount of wear and maximum amount of hard surface layer was found in section marked E, which is nearest the powder chamber and at the beginning of the rifling; the maximum amount of cracking in D; the maximum amount of copper deposition in C. Section B showed heat cracks on both lands and grooves, and section A showed heat cracks on the driving edge of the lands only. There was much flow of metal in both sections E and D, and there was progressively less effect noticeable toward the muzzle end. The polished cross-section of these same pieces is shown in Fig. 2. The

Jan 12, 1916

By L. C. Brown, E. B. Hawbolt

The formation of grain boundary precipitates has been studied in Ag-5.64 wt pcl Al alloys at 688°C. Large-grain specinzerzs were used and the boundary misorientation measured by X-ray diffraction. At low-angle grain boundrrries Primary sideplates form. u)hile abore a 17-deg misorientation lenticular precipitates predominate. Growth of the lenticular precipitates was studied on individual grain boundaries using a statistical technique. The thickening and lengthening rates appeared to be independent of &apos;pain boundary misorientation, indicating that grain boundary diffusion was not significant in this system. The precipitates grew urith constant shape, with both the length and thickness increasing parabolically with time. The parabolic lengthening rates were unexpected since previous theory and experimerztal results had indicated linear growth. By approximating the shape of the precipitate to that of an oblate spheroid grouling with constant shape an equivalent diffusion coefficienl was calculated. The zlalue obtained was in good agreement with nleasurements obtained fron, diffusiorz couples. IF a single-phase alloy is heated or cooled to a temperature such that the phase becomes supersaturated, there is a tendency for a second phase to precipitate from it in order to remove the supersaturation. Precipitation takes place initially on grain boundaries due to preferred heterogeneous nucleation, but subsequently Widmans kitten plates may form in the grain interiors if the grain size and supersaturation are sufficient. The type of grain boundary precipitate formed depends on the nature of the boundary. Aaronson1 and clark2 have shown that grain boundary misorientation can be characterized by the simple parameter R, where and X, Y, and Z represent the minimum rotations about three orthogonal axes required to bring the two lattices forming the grain boundary into coincidence. The maximum value for R is 60 deg. In using this parameter the orientation of the grain boundary itself is, of course, neglected. However it was found in both Fe-si3 and A1-Ag2 that the precipitate shape depended only on the parameter R. Clark found that the vast majority of precipitates formed were allo-triomorphs— lens-shaped precipitates that grew along the grain boundaries. At low-angle boundaries, however, (R < 15 deg) Widmanstatten sideplates nucleated at the grain boundaries and grew into the adjacent grains. It has been reported that the rate of growth of grain boundary precipitates is controlled by diffusion within the supersaturated phase.&apos; The theories which have been developed for growth rates have assumed the diffusion coefficient constant over the composition range of the supersaturated phase. This is a fairly good approximation if the composition range involved is not large. Thickening rates have been calculated using the theory developed by Zener4 and by Frank5 for the growth of planar precipitates. A parabolic growth law

Jan 1, 1968

By W. O. Philbrook, H. W. Hosking, N. B. Melcher

Rates and patterns of gas flow in an experimental blast furnace were investigated by measurements, at three levels, of gas compo-sitions and temperatures and by direct determination of gas transit time by a new method employing mercury vapor as a tracer. Infer-ences were drawn about localized reaction zones and the mechanism of the onset of&apos; channeling. LACK of precise knowledge of the nature of gas movement in the blast furnace has always been an impediment to better understanding of the blastfurnace process as a whole. The effects upon operation of various types of charge distribution are very largely brought about by the modifications to gas flow which they occasion. Intelligent evaluation of these effects demands a better understanding of the factors influencing gas flow and the ways in which the flow pattern is altered by conditions existing in the stock column. The same knowledge is required before a fundamental approach can be made to the problem of establishing optimum lines for new furnaces. An experimental furnace is operated at the Bureau of Mines Central Experiment Station, Pittsburgh, Pa. Advantage was taken of experimental operation to conduct an investigation to develop and evaluate methods of study which could be applied later to industrial furnaces. The gas composition and temperature determinations were made as a preliminary study so far as gas flow was concerned but yielded significant information relating to other processes occurring within the furnace. The direct measurement of gas transit times by the mercury-vapor method constituted the major object of the investigation. Development of the mercury-vapor method was carried out while the data on gas composition and temperature were being collected. A complete description of the principle and development of the mercury-vapor method is beyond the scope of this paper but is available elsewhere. The results obtained and some consideration of the method&apos;s effectiveness and its potential value in the study of industrial problems will be treated here. DESCRIPTION OF FURNACE The general lines of the experimental blast furnace are shown in Fig. 1. The hearth diameter was 3 ft at the beginning of the investigation, and this was later enlarged to 3 ft 9 in. and finally to 4 ft to increase capacity. Tuyere to stockline height is 21 ft 4 in. The bosh depth is 3 ft 4 in. over which it opens to a width of 5 ft, and this diameter is carried up for 2 ft in a cylindrical section. The inwall batter of 1/2 in. per ft. is considerably less than in larger installations This may have influenced the movement of gaseous and solid materials. The furnace is inside a laboratory building and is charged from outside by a skip and hoist. Feeding into the first of three bell chambers, the stock is distributed by rotating the upper bell, the other two being used to obtain an effective gas seal. Three water-cooled tuyeres, with a nozzle dia-

Jan 1, 1960

By Y. Okahara, I. Iwasaki

Chlorination behaviors of pure iron and manganese oxides were investigated by combining a thermogravimetric analysis (TGA) technique with batch-boat roasting followed by leaching. Ferrous and manganous oxides could be chlorinated readily, but, in the absence of a reductant, the higher oxides of both iron and manganese were dificult to chlorinate. Thermogravimetric analysis curves were drawn to illustrate the complexities of the reactions, and the possible mechanisms were discussed. Then three manganif-erous materials from the Cuyuna Range of Minnesota were treated by a process involving the selective chlorination of manganese followed by leaching. The results were interpreted in the light of the chlorination mechanisms observed on the pure iron and manganese oxides. One of the unsolved problems challenging Minnesota&apos;s mining industry is the development of an economic process to utilize the manganiferous iron ores of the Cuyuna Range. Although these ores constitute one of the major domestic reserves of manganese (estimated at 432 million tons&apos;), their grade is too low for them to be mined solely for manganese. The nearly exclusive dependence of the U.S. steelmaking industry on foreign manganese ores has stimulated research over the years in treating the low-grade Cuyuna ores. As a result, a number of processes have been proposed.&apos;-&apos; Among these processes is chlorination. Chlorination is the high-temperature conversion of metallic oxides to chlorides by either chlorine or hydrogen chloride gas, or by solid chlorides of sodium, calcium, or magnesium. The metallic chlorides are then recovered by either vaporization or leaching. Although chlorination is an old art, it has become popular in recent years for the recovery of such new metals as titanium, zirconium, and niobium; for the removal of impurities like copper, lead, and zinc from pyrite cinder for ironmaking raw materials;&apos; and for the segregation roasting of coppera and nickel&apos; ores. The chlorination processes proposed for manganifer-ous iron ores have been relatively few (hydrogen chloride chloridization-leaching, hydrogen chloride and calcium chloride chloridization-volatilization,&apos; and chlo-rination-selective condensation6), due presumably to the economics and to the corrosion problems involved. However, the successful application of chlorination processes to other ores will undoubtedly contribute to technological advancements in the chlorination of man-

Jan 1, 1971

By Attilio Ligasacchi

The production of magnetite in copper smelting has been the subject of wide investigation in the past.1-9 It is accepted that most of the magnetite is produced in the converters and returned to the re-verberatory furnace with the converter slag. Part of this magnetite is circulated back to the converters in the matte. As a result, if proper fluxing practice is not followed, and temperatures in the converting process are not strictly controlled, an undesirable circulating load of magnetite may occur. This might ultimately lead to saturation in the reverberatory bath with consequent settling of the magnetite at the furnace bottom. This paper contains the cumulative results of a series of investigations on the formation and control of magnetite presently being conducted by the metallurgical department of the Chino Mines Division of Kennecott Copper Corp. THE METHOD USED FOR THE DETERMINATION OF MAGNETITE AND OTHER MAGNETIC MATERIALS Conventional wet chemical magnetite analyses are neither reproducible nor theoretically sound. These analyses are sensitive to time, temperature, and heating rate-all factors which tend to decrease their accuracy and reproducibility. To overcome the unreliability of the above method, H. W. Mossman1 developed an inductance bridge magnetite "meter" which completely replaces the wet chemical analysis with the advantage of quicker and reproducible results. Fig. 1 is a schematic diagram of the meter in use in the Chino metallurgical laboratory. When a pulverized specimen with magnetic properties is placed in coil A of the inductance bridge circuit, the permeability of the core is increased, causing a voltage drop across the coil. The unbalance is amplified to operate the balancing motor which adjusts the movable iron core in coils C and D to bring the bridge back to balance. An indicator arm connected to the movable iron core indicates directly the percent, or weight, of the magnetic material in the specimen. Coil B acts as a reference coil and a zero adjustment. The meter is standardized with a set of various amounts of -100 mesh pure magnetite crystals (99.8 pet Fe3O4) thoroughly mixed in a test tube with -100 mesh quartz sand. These mixtures are combined with inert transoptic powder and heated to 140° to 160°C (melting point of the powder) and subsequently cooled to room temperature, solidifying the whole mixture, in this manner eliminating any possible preferential orientation of the magnetite grains. In order to determine the effect of the particle size" of the magnetite and other magnetic materials on the meter determinations, five size fractions were obtained by wet screening of the 99.8 pet pure magnetite and several reverberatory matte and slag samples. The following size fractions were investigated: -80 + 100; -100 + 150; -150 + 180; -200 + 250; -250 + 300 and -100 mesh. The deviation of the meter readings for the various sizes of each sample never exceeded ±0.3 pet. This deviation is considered well within the accuracy needed for common smelter operation procedures. Further investigation proved also that grinding slag and matte samples in our laboratory disc grinder normally produced a powder constituted of 95 pet -200 + 300 mesh. For practical purposes a - 100 mesh size was used as standard for our studies. It was also found that for rapid determinations tamping of the sample in the test tube was sufficient and gave comparable results with those samples solidified with transoptic powder. For the purpose of this study we define the magnetite content in copper smelter slags and matte as the equilibrium amount of crystalline Fe3O4 existent in the specimen at a given reference temperature, excluding any secondary magnetite precipitated in the specimen during nonequilibrium conditions. MAGNETITE DETERMINATION IN SLAGS Since it is impossible to ascertain the status of equilibrium of a conventional slag sample, due to

Jan 1, 1965

By R. W. Fountain, J. Chipman

THE solubility of nitrogen in iron and steel has been of considerable interest due to the role of nitrogen in strain-aging and in quench-aging. It is generally considered that quench-aging is the result of precipitation of carbide and nitride particles from supersaturated solid solution, while strain-aging results from the segregation of carbon and nitrogen atoms to dislocations.1-9 The rate of strain-aging is controlled primarily by the amount of carbon and nitrogen in solution and the temperature. In experiments on strain-aging of pure iron with only carbon or nitrogen as impurities, Fast" has shown that even after 40 hr at 50°C carbon did not give any strain-aging while

Jan 1, 1959

By George A. Grandy, D. W. Fuerstenau

Simulation of nonlinear grinding systems is discussed in the context of the size-discretized batch-grinding model. A linear approximation of environment-dependent (or nonlinear) selection functions is postulated for systems which exhibit feed grinding orders less than unity. For this, a convex linear combination of zero and first-order selection function forms is used to obtain an analytical solution that can be used for simulation. An example in which marked nonlinear behavior occurs is rod-mill grinding. Accordingly, a series of grinding experiments was carried out in a batch laboratory rod mill to test these techniques; agreement between experiment and the model was found to be very good. Recently, significant progress has been made in the simulation of linear grinding systems by using a population balance mathematical model. Herbst and Fuer-stenaul presented a parameter estimation scheme that can be used with the size-discretized batch-grinding model, and Gumtz and Fuerstenau3 have extended these techniques to the simulation of locked-cycle grinding. Grandy et aL." summarized the simulation of linear systems and noted important alternate solutions to the batch-grinding equation. Kelsall et a1.&apos;-" discussed the dynamic simulation of linear batch grinding, as well as linear open and closed-circuit grinding. In all of these, the key word is linear, which certainly restricts the engineer trying to simulate a variety of grinding systems. This paper discusses an approach for the simulation of non-linear grinding systems, particularly those which exhibit grinding orders less than unity. Experimentally, dry rod-mill grinding is used to evaluate the technique presented. Batch Grinding Model The size-discretized batch-grinding model has been discussed in detail by Mika et al.&apos;.&apos; and by Herbst and Fuerstenau,&apos; and therefore, will only be briefly developed here. The model is formulated by making a differential mass balance of each size fraction in such a manner that the equation parameters are precisely defined in terms of selection and breakage functions,&apos; which can be either calculated&apos;.&apos; or estimated1 from experimental data. The model is phenomenological because it averages all stress-application events in the system and, therefore, does not distinguish the manner in which individual particles are stressed.&apos; For this average environment, the resistance of all particles in a size fraction to breakage is defined by that size-frac-tion&apos;s selection function; and when fracture occurs from an average event, the breakage product size distribution is defined again by that size-fraction&apos;s breakage function. The model is deterministic and is derived in terms of a continuous time variable and a discretized size variable,&apos; i.e., the n mass fractions associated with the n defined size intervals (see Table 1 for nomenclature).

Jan 1, 1971