Search Documents

By Walter Herd

FoR the past eight years No. 2 mine of the Cumberland Railway & Coal CO., Springhill, Nova Scotia—a subsidiary of the Dominion Coal Co., Ltd.—has had an unenviable reputation for bumps. As the workings extended in certain directions under a greater cover, these bumps increased in severity and it became apparent that some change in the system of extraction was necessary if the mine was to continue to operate. In September, 1924, following several fatalities resulting from bumps, the Mines Department of Nova Scotia requested from the U. S. Bureau of Mines the services of George S. Rice, Chief Mining Engineer of the Bureau, to report on the conditions then prevalent in No. 2 mine, Springhill. This request was promptly and courteously granted. Mr. Rice made a full investigation and a comprehensive and helpful report, which is embodied in the 1924 Annual Report of the Department of Public Works and Mines, Nova Scotia. Prior to 1925, the room and pillar method was employed and in January of that year (there being a cessation of work from March to August due to labor troubles) longwall retreating on the west side, on a limited scale, and in a small section on the east side of the mine was started. The major portion of the east side was not operated on this system till August, 1926, as there was developed a considerable area ready for pillar extraction between an arbitrary boundary and a point up to which bumps of any consequence had not been experienced. In the interval development work for longwall retreating below the 5900-ft. level was vigorously pushed. This longwall retreating system was suggested by Mr. Rice as a possible remedy and was heartily endorsed by the company officials. This paper describes the conditions and happenings subsequent to Mr. Rice's report and more especially the results with the longwall retreating system of mining under the peculiar circumstances pertaining to mining No. 2 Seam, Springhill, at depth, and records the conclusions which experience with several severe bumps under this mode of extraction would suggest. Except where necessary to make the paper intelligible as an entity any duplication of Mr. Rice's report will be avoided.

Jan 1, 1930

By John Wulff, J. H. Hollomon

The opinion has been widely held that the corrosion of alpha brass occurs by the selective solution of zinc. As late as 1939, Fink1 and Evans2 suggested that in the initial stage of the corrosion the selective solution of zinc produces copper-rich areas, which subsequently act as cathodes that facilitate the deposition of copper. Previously Abrams3 had shown that most of the copper found on corroded brass was re-deposited and not residual, although he did not consider the nature of the initiation of the corrosion process. Enough data exist to indicate that any metal surface is sufficiently heterogeneous to provide the anodes and cathodes necessary for the initiation of corrosion.4,5 Thus, for alpha brass we need postulate not an initial selective solution of zinc, but only the existence of local differences in electrochemical potential. The heterogeneity responsible for potential differences may arise from oxide and other films as well as from alloy concentration gradients. Even though selective corrosion may be possible in some alloy systems, previous data on alpha brass as well as the experimental work reported in this paper do not require this supposition. Bengough and May16 in a discussion of Abrams' paper, first suggested the addition of small amounts of arsenic (0.03 per cent) to a1pha brass to prevent the redeposition of copper (dezincification). This suggestion was later substantiated by Nixon.7 In their studies of the inhibiting influence of arsenic, Evans and Fink were led to the selective-solution hypothesis in order to explain the initial corrosion of such alloys. They believed that an arsenic film covered anode areas and prevented the formation of copper-rich spots capable of acting as cathodes for the deposition of copper. They did not consider, however, the mechanism by which the arsenical film was formed. Bengough and May,a in another publication, suggested that the commonly found gray or black arsenical film may act to: (I) carry oxygen to the brass surface, (2) increase the discharge potential of copper on brass, (3) precipitate cuprous chloride from colloidal suspension in chloride solutions. Masing9 assumed that the film found upon arsenical brass was metallic arsenic. His measurements of hydrogen overvoltage of bulk arsenic led him to believe that the inhibition of dezincification occurs because the overvoltage of a brass surface is lowered by the arsenic film. He reasoned that this film would permit the more rapid reduction of hydrogen at the cathode, which would prevent the redeposition of copper. In a recent paper,10 we have pointed out that the film formed during the corrosion of arsenical brass and copper in stagnant solutions is essentially arsenious oxide (As2O3),

Jan 1, 1942

By John Wulff, J. H. Hollomon

The opinion has been widely held that the corrosion of alpha brass occurs by the selective solution of zinc. As late as 1939, Fink1 and Evans2 suggested that in the initial stage of the corrosion the selective solution of zinc produces copper-rich areas, which subsequently act as cathodes that facilitate the deposition of copper. Previously Abrams3 had shown that most of the copper found on corroded brass was re-deposited and not residual, although he did not consider the nature of the initiation of the corrosion process. Enough data exist to indicate that any metal surface is sufficiently heterogeneous to provide the anodes and cathodes necessary for the initiation of corrosion.4,5 Thus, for alpha brass we need postulate not an initial selective solution of zinc, but only the existence of local differences in electrochemical potential. The heterogeneity responsible for potential differences may arise from oxide and other films as well as from alloy concentration gradients. Even though selective corrosion may be possible in some alloy systems, previous data on alpha brass as well as the experimental work reported in this paper do not require this supposition. Bengough and May16 in a discussion of Abrams' paper, first suggested the addition of small amounts of arsenic (0.03 per cent) to a1pha brass to prevent the redeposition of copper (dezincification). This suggestion was later substantiated by Nixon.7 In their studies of the inhibiting influence of arsenic, Evans and Fink were led to the selective-solution hypothesis in order to explain the initial corrosion of such alloys. They believed that an arsenic film covered anode areas and prevented the formation of copper-rich spots capable of acting as cathodes for the deposition of copper. They did not consider, however, the mechanism by which the arsenical film was formed. Bengough and May,a in another publication, suggested that the commonly found gray or black arsenical film may act to: (I) carry oxygen to the brass surface, (2) increase the discharge potential of copper on brass, (3) precipitate cuprous chloride from colloidal suspension in chloride solutions. Masing9 assumed that the film found upon arsenical brass was metallic arsenic. His measurements of hydrogen overvoltage of bulk arsenic led him to believe that the inhibition of dezincification occurs because the overvoltage of a brass surface is lowered by the arsenic film. He reasoned that this film would permit the more rapid reduction of hydrogen at the cathode, which would prevent the redeposition of copper. In a recent paper,10 we have pointed out that the film formed during the corrosion of arsenical brass and copper in stagnant solutions is essentially arsenious oxide (As2O3),

Jan 1, 1942

By Langtry E. Lynd

The predominant tonnage use of titanium is as a white pigment, in the form of rutile or anatase, which are allotropic modifications of titanium dioxide. Because of its whiteness, high refractive index and resulting light scattering ability, titanium dioxide is unequaled as a white pigment for paints, paper, rubber, and a wide variety of other materials. Consumption of titanium dioxide pigments for these uses has been rising steadily for many years, United States consumption in 1956 amounting to about 486,000 tons, worth $250,000,000. Production was off a little in 1957 and 1958. An outstanding development in the titanium field in recent years is the expansion of titanium metal production. Virtually nonexistent before 1948, United States production of pure titanium metal sponge reached a high in 1957 of about 17,200 tons, worth about $77,000,000. United States titanium sponge metal production in 1958 was cut back to about 4,600 tons because of reductions in military requirements. Another major use of titanium, in the form of the mineral, rutile, is for welding rod coatings. United States consumption of rutile for this purpose in 1958 amounted to about 11,000 tons, worth $1,100,000. Titanium-Bearing Minerals Although several minerals contain titanium as a major constituent, only a few of these occur in sufficient quantities and concentrations to be of commercial importance. These are ilmenite (FeTiO3), rutile (TiO2), and alteration products of ilmenite which have been referred to as weathered ilmenite, leucoxene, or arizonite. The other polymorphs of titanium dioxide, brookite and anatase, occur in a few deposits, of which only one has been of even minor importance. Considerable concentrations of titanite or sphene (CaTiSiO5) and perovskite (CaTiO3) are known, but do not compete with ilmenite and rutile deposits in grade or size. Rutile is very widely distributed as an accessory mineral in most rocks, but large deposits of commercial importance are rare. A few rock deposits have been worked for rutile but only one, in Virginia, is in operation (1959). Development of one in Mexico was discontinued recently. At present, the main sources of rutile are the beach and dune sands of Australia and Florida. A major use of rutile is for the manufacture of titanium tetrachloride, which is the intermediate compound universally used in titanium metal manufacture. Another main use of rutile is for welding rod coatings. Although the whiteness and brightness of titanium dioxide pigment is due to the high refractive index of rutile or anatase, natural rutile is too impure to be used directly as a white pigment, is too expensive to use for manufacturing pure oxide pigment, and is too scarce to provide the required tonnages. Instead, the cheaper, more abundant, mixed oxide of iron and titanium, ilmenite, which is readily decomposed by sulfuric acid, is used for manufacture of rutile and anatase pigments. Ilmenite is mined from both rock and sand deposits. Rock deposits contain ilmenite in massive or heavily disseminated form along with magnetite or hematite and are almost invariably associated with anorthositic and gabbroic rocks. Ilmenite also occurs as an accessory mineral in a great many igneous and metamorphic rock types. Concentrations of

Jan 1, 1960

THE composition and quality of finished steel depend upon selection and proportioning of the raw materials of the charge as well as on control of furnace practice. This chapter deals only with those raw materials of the basic open-hearth process which are important in determining the composition of the steel or slag. They are the metallic charge, oxygen-bearing materials, fluxes, and alloying and deoxidizing additions. Refractories, which may also affect the slag composition, are discussed in the previous chapter. Wide variations are possible in the type and composition of charged materials, but in all cases certain fundamental relationships among the elements of the charge must be maintained. Since the process consists essentially of refinement by oxidation of undesired elements, a balance must be established between the sources of oxygen and the elements in the charge that are subject to oxidation (see Chapters II and VII). For example, if it is desired to use a high ratio of blast-furnace hot metal to scrap, it is necessary to add an oxygen-bearing material such as ore or mill scale to eliminate the excess carbon and silicon that are present in the hot metal. An example of the opposite extreme would be the use of a metallic charge composed entirely of steel scrap. With this type of charge, it is common practice to substitute burnt lime for limestone as a flux and to charge some carbonaceous material such as coke to avoid an excess of oxygen in relation to the elements of the charge that are subject to oxidation. Elements such as copper and nickel, which are not subject to oxidation or other reactions resulting in their elimination, may be introduced into the charge only to the extent to which they are permissible in the finished steel. An example of adjustment of the charge for elements of this type would be found in the use of steel scrap high in copper. In this case, metallic components of the charge other than the scrap should below in copper, or a sufficiently high ratio of pig iron to scrap should be charged to dilute the copper from the scrap, so that the average copper content of the melt will be below the required maximum.

Jan 1, 1944

By L. L. Handy

Solvent floods using slugs of solvent have been found to show continuity in behavior from the vapor pressure of the solvent to the critical pressure for the two-component driving gas-solvent system. In the pressure region between the solvent vapor pressure and the critical pressure for the gas-solvent system, the gar and solvent are only partially miscible. Although complete miscibility cannot be obtained at these pressures, complete oil recovery is possible in principle. In two-phase solvent floods the solvent is propagated tllrough the reservoir, primarily, in the vapor phase. The carrier gas requirements constitute a significant factor in the economics of the process. A qualitative theory is proposed for estimating the amount of dry gas required to move the solvent through the reservoir. The theory shows that for two-phase solvent floods the total gas needed is a minimum at the vapor pressure of the solvent and at the critical pressure for the gas-solvent system, and is a maximum at some intermediate pressure. The predictions of the theory are supported by experimental studies using methane, butane and decane or methane, propane and decane in a natural sandstone core. INTRODUCTION Previously, solvent slug processes have been found effective for oil recovery in two pressure ranges. First, conventional miscible displacements are possible at pressures greater than the critical pressure for the gas-solvent system. Second, Jenks, et al,' have shown that, at pressures slightly in excess of the vapor pressure of the solvent, a solvent slug can be propagated through a reservoir by a gas essentially insoluble in the liquid solvent. The solvent bank displaces the oil ahead of it. Both of these processes, at least ideally, are capable of recovering all of the oil in the swept regions. Slug processes for which the gas and solvent are partially miscible have not been considered; that is, those systems for which the solvent and driving gas form two equilibrium phases in which the vapor phase contains a significant amount of solvent and the liquid phase an appreciable amount of the driving gas. Welge and Johnson' have shown that the gas needed to movc a solvent slug through the reservoir increases with increasing pressure above the vapor pressure of the solvent. It will be shown that solvent slug processes can, theoretically, recover all of the oil at any pressure greater than the vapor pressure of the solvent. But the amount of gas required to move the solvent through the reservoir depends very much on the pressure and temperature. In the present study a maximum in the gas requirements was both predicted theoretically and observed experimentally. This result has not been reported previously, and would not have been predicted from the Welge and Johnson model. The gas requirements are a minimum at the pressures corresponding to the vapor pressure of the solvent and again at the critical pressure for the gas-solvent system, and are a maximum at some intermediate pressure. AN APPROXIMATE THEORY FOR TWO-PHASE SOLVENT FLOODING The differences and similarities between conventional solvent floods and two-phase solvent floods are best understood by referring to concepts developed for miscible displacement in which miscibility is generated in the reservoir. In Fig. 1(A), a ternary diagram is shown for a hypothetical gas-solvent-oil system. To be rigorous the three components should each consist of a single molecular species. The pressure for Fig. 1(A) is greater than the critical pressure for the binary gas-solvent system at the specified temperature. Diagrams of this type are the ones most frequently referred to in discussions of enriched-gas drive and miscible displacement. A limiting tie line is shown tangent to the two-phase envelope and intersecting the gas-solvent line at Point A. To obtain generated miscibility with this type system, others have shown that, for an oil of Composition D, a mixture of gas and solvent must be injected which is richer in solvent than that composition indicated by A. An oil repeatedly contacted with a gas phase richer than A changes toward a composition which would be at equilibrium with the injected mixture, that is, a composition lying on a tie line which passes through the injected-gas composition. Since no such tie line exists, the oil is enriched to the point at which it becomes directly miscible with the injected mixture. At pressures lower than the critical pressure for the gas-solvent system, other types of phase diagrams are observed. The ones of interest in this paper are for pressures greater than the vapor pressure of the solvent, but less than the critical pressure of the gas-solvent system. Such a ternary diagram is shown on Fig. 1(B). In this case, two-phase behavior is observed not only for gas-oil mixtures, but also for certain compositions in the gas-solvent system. If a gas of Composition A (a dew-point vapor) is injected, once again the original oil is enriched by successive

By R. G. Vardiman, M. R. Achter

THERE has been interest recently in the conditions under which dislocation pipe diffusion may be observed. In order to extend the measurements to temperatures below Tm/2, where pipe diffusion becomes more important, a chemical sectioning technique was developed for silver single crystals which makes possible the removal of layers of 100A or less. The procedure is briefly as follows. Silver single crystals of 99.995 pct purity were cut in the form of discs t by 4 in., electropolished, and electropolated with Ag110 to about 1000A thickness. The thickness was determined by calibrating the activity with the weight of heavier platings, up to 10,000A. Both diffused and undiffused samples were sectioned in a two-step process. Reaction with a solution of iodine in alcohol formed a thin, even layer of AgI, which was then dissolved in a KCN solution. The reaction rate of the iodine solution varied slightly over a period of time, so that the thickness of the stripped layers, while quite even and regular for a given specimen, ranged from 65 to l00W for different specimens. This variation was checked by using a thickly plated standard with each run. Layer thickness was determined from undiffused samples by the point where the layer activity drops to half the maximum. This maximum intensity also provides, with appropriate corrections, the initial concentration per layer co. Because of the small penetration distances, it is necessary to use the exact solution of Fick's law for a source of finite thickness.' For a plating of thick- where c is the concentration at depth x. flj the error function, D the apparent diffusion coefficient, and t the time. The diffusion coefficient was obtained from the concentration-penetration data by extrapolating to x = 0 where c/co = erf h/2(Dt)1/2 Enough points were taken to impart confidence in the accuracy of the intersection, generally about ten layers. Four temperatures were used as in Table I. For best accuracy, t and h were chosen to give values of the parameter (Dt)1/2/h between 1.0 and 1.7. A typical concentration-penetration curve is shown in Fig. 1. The diffusion coefficients calculated from Eq. [I] are plotted in Fig. 2. For comparison, the high-temperature data of Tomizuka and sonder 2 which go down to 630°C are plotted as the solid line 2(a) from their expression D = 0.40 exp (-44,090/RT). Also for comparison, the lowest temperature point of Hoffman and Tumbull3 is plotted. It is apparent that our data diverge appreciably from the high-temperature extrapolation by 373°C. A better straight line fit for the low-temperature portion is obtained by subtracting the extrapolated volume diffusion coefficient from the apparent. or measured coefficient, and plotting the difference, curve (h) of

Jan 1, 1970

By F. W. Newhall, L. N. Plein

During the latter part of the year 1931, the Republic mine of the Republic Steel Corporation, at Republic, about 4 miles south of Brownsville, Pa., was mining coal along four rib or fracture lines. One of these lines, the west butt rib line, was retreating towards a concrete-lined air shaft, 320 ft. deep, which had been sunk in 1911 for ventilation purposes. With the normal rate of mining at that time, it was expected that this rib line would pass the shaft in three or four months and the shaft would then be abandoned and allowed to cave. Realizing the opportunity presented for the study of an unusual case of ground movement, the question of conducting the study was presented by the junior author to thechairman of the Institute's committee on Ground Movement and Subsidence, Mr. George S. Rice, who presented the matter to Mr. G. H. Morse, General Manager of the Northern Mines, Republic Steel Corporation, and he agreed to cooperate with the Bureau of Mines in making the study, the results of which arc presented in this paper. Acknowledgments are due to Mr. Morse for his full cooperation in this work and to Mr. G. S. Rice and Mr. J. W. Paul, both of the U. S. Bureau of Mines, for their advice and guidance during the course of the work. The authors are indebted to Mr. B. F. Herbert, mining engineer, Northern Coal Mines, Republic Steel Corporation, who assisted in all the surveys, and Mr. W. H. Smith, draftsman, U. S. Bureau of Mines, who prepared all illustrations for publication. Geologic Conditions The shaft is at Merrittstown, which is about one mile northwest of Republic. The topography in the immediate vicinity of Merrittstown consists of rolling country dissected by the meanders of Dunlap Creek and its tributaries. The surface slopes of the hills are gentle and their average gradient is less than 6º. The area at the point where the study was made lies on a hillside sloping towards the southwest, the gradient, varying from 1º to 14º. Fig. 1 shows contour lines at 5-ft. intervals on

Jan 1, 1936

By L. N. Plein, F. W. Newhall

During the latter part of the year 1931, the Republic mine of the Republic Steel Corporation, at Republic, about 4 miles south of Brownsville, Pa., was mining coal along four rib or fracture lines. One of these lines, the west butt rib line, was retreating towards a concrete-lined air shaft, 320 ft. deep, which had been sunk in 1911 for ventilation purposes. With the normal rate of mining at that time, it was expected that this rib line would pass the shaft in three or four months and the shaft would then be abandoned and allowed to cave. Realizing the opportunity presented for the study of an unusual case of ground movement, the question of conducting the study was presented by the junior author to thechairman of the Institute's committee on Ground Movement and Subsidence, Mr. George S. Rice, who presented the matter to Mr. G. H. Morse, General Manager of the Northern Mines, Republic Steel Corporation, and he agreed to cooperate with the Bureau of Mines in making the study, the results of which arc presented in this paper. Acknowledgments are due to Mr. Morse for his full cooperation in this work and to Mr. G. S. Rice and Mr. J. W. Paul, both of the U. S. Bureau of Mines, for their advice and guidance during the course of the work. The authors are indebted to Mr. B. F. Herbert, mining engineer, Northern Coal Mines, Republic Steel Corporation, who assisted in all the surveys, and Mr. W. H. Smith, draftsman, U. S. Bureau of Mines, who prepared all illustrations for publication. Geologic Conditions The shaft is at Merrittstown, which is about one mile northwest of Republic. The topography in the immediate vicinity of Merrittstown consists of rolling country dissected by the meanders of Dunlap Creek and its tributaries. The surface slopes of the hills are gentle and their average gradient is less than 6º. The area at the point where the study was made lies on a hillside sloping towards the southwest, the gradient, varying from 1º to 14º. Fig. 1 shows contour lines at 5-ft. intervals on

Jan 1, 1936

By Harry V. Welch

This paper presents a brief discussion of numerous devices and processes which have been utilized for the recovery of values from gases in copper reduction works and describes in greater detail the development and application in recent years of electrical precipitation, more familiarly known as the Cottrell process, to the problems of dust losses with furnace gases in copper-smelting and refining plants. The field for collection of suspended particles in gases is widely extended in our modern complex, congested .and industrialized mode of living, and its satisfactory solution is required by our increasing appreciation of the extravagant waste, unhealthful effects and nuisance which such uncontrolled emission of solid suspensions represents. Much of the special dust-recovery equipment in use today has been developed in one industry and carried over to many others. The early work of Cottrell was with sulfuric acid mists, aimed at the purification problem in contact acid manufacture, but the present uses of Cottrell equipment cover a diversified field—carbon black, combustible gas, oil mists, iron blastfurnace fumes and dusts, cement-kiln gases, as well as the purification of gases in contact and chamber acid plants and its wide and extended use in the nonferrous metallurgical field of copper, zinc and lead, and their associated metals. Dust and fume collection from furnace gases became a problem only with the modern development of large and amply powered auxiliary furnace equipment, which in turn permitted large furnace units, fast driving and large outputs of finished product per unit of furnace capacity. The ancient metallurgist with his small clay pot and hand-operated bellows had too little gas velocity to cause a real dust loss. As furnaces grew in size, flues and stacks were added, and undoubtedly the first observable dust losses were indicated by the deposits in the flue and stack base. Large flues, it was noted, collected more than smaller ones, and the expansion of a portion of the flue into a chamber represented the first serious attempt at recovery of furnace dust losses. For a century or more the settling chamber represented the best of skilled metallurgical practice in recovery of furnace dust, and it may be said to have reached

Jan 1, 1934

By L. Albert, A. M. Cameron, J. W. Gullick

International Nickel has 15 operating mines in Canada, and. 3 mines which are being maintained on a standby basis. Annual production is about 20 million dry short tons of ore, most of which is from underground mines, the remainder from open pit mines. Although some of the underground mines are served by ramps for trackless vehicles, most men, materials and ore are hoisted in vertical shafts. In addition to shafts and raises for ventilation and service purposes which are not equipped with hoisting plants, there are now 28 vertical shafts at Inco mines served by 47 hoists. Of these, 22 shafts and 36 hoists are located in the Sudbury District of Ontario, one shaft and two hoists are at the Shebandowan mine in Western Ontario, and 5 shafts with 9 hoists are located near Thompson, Manitoba. This paper describes the components of Inco hoisting plants-which have been applied at different times and under different conditions, and indicates the rationale for the various designs. Some engineering and maintenance practices, considered advantageous, are also described. MINE SHAFTS Many of the shafts sunk in the early days of the Sudbury District, on what are now Inco properties, were inclined shafts. Of the identifiable shafts sunk between 1885 and 1920, thirteen were inclined and at least four were vertical. Since 1920, thirty vertical and two inclined shafts have been sunk. All of the inclined shafts have been abandoned for hoisting purposes but the majority are still in use as service or ventilation ways. Shafts at Thompson- and Shebandowan are all vertical. The vertical shafts range from 2 or 3 compartment exploration and development shafts to 6 compartment shafts for ore, man and material hoisting. They vary in depth from 1,050 to 7,137 feet and in addition to hoisting compartments all contain manway and service compartments. Prior to 1948, unlined rectangular shafts with timber sets and guides were used. The rectangular cross-section was favoured since the rock is competent, the shape compatible with timber set framing, and since available shaft space could be used efficiently. Resistance to air flow was not of prime importance. Concrete linings were introduced for the first time at the Creighton No. 7 Shaft which was collared in 1948. All major shafts since that date have been concrete lined. Vertical set intervals were increased in steps, with the introduction of structural steel sets secured to the concrete linings. Whereas 7 foot set intervals were used with timber framing, this increased to 10 feet 6 inches with steel sets and more recently to 15 feet with steel and steel backed wood guides. With the advent of deeper shafts, or shafts which are expected to be deepened, the trend is to circular concrete lined shafts. The majority of shaft guides in service are of select Douglas Fir. This practice commenced as a component of timbered shaft design but continued as a

Jan 1, 1975

By Edward A. Capillon

The problem of scrap is probably of greater importance in the pro duction of gold, silver and other precious metal alloys than is the case for base metals and alloys. Remelting of gold and silver scrap in the shop is always a costly process because it involves losses by oxidation of thc base metals in the alloy with a consequent increase in the percentage of precious metal. This is most marked in the case of alloys containing the low-boiling and easily oxidized metals zinc and cadmium. Since it is not generally feasible to assay every shop remelt it follows that the possibilities of lost values arc large. So-called rolled gold and silver plate is made by soldering or welding the precious metal alloys onto base metal. Such plate when defective must be sent to the refinery to recover the gold and silver values, thereby involving additional expense in the form of refining charges. It is obvious therefore that gold and silver alloy scrap is an important item in manufacturing cost and must be reduced to a minimum. The amount of scrap resulting from poor metal will depend on a number of factors in the manufacturing operations, not least among which is the melting and casting practice. The notes which follow are a summary of experiments performed at various times to determine what variables in melting and casting are influential in the production of sound alloys. Metals Used in Alloying Pure gold, that is, gold of 24-kt. value is very much too soft for jewelry purposes and it is therefore always alloyed with other metals to increase its hardness and resistance to wear. For the same reason pure silver is seldom used alone but is alloyed with copper, the standard alloy being sterling silver which contains 92.5 per cent. silver and 7.5 per cent. copper. The metals commonly used for alloying gold are silver, coppcr, nickel and zinc. In addition to hardening the gold and producing alloys of different karat values the use of these metals makes possible the production of gold alloys of various colors such as yellow, red, green and white. The gold-silver-copper alloys vary in color from light greenish-white through green, yellow and red depending on the relative amounts of the three metals. Green or yellowish-green colored golds

Jan 1, 1930

By M. K. Barnett

Engineering research consists, broadly speaking, in the investigation of the effect of the variations in a number of factors on some property of a product or characteristic of a process. The unambiguous description of the product or process requires that the property or characteristic be expressible in quantitative terms. For the purpose of practical control, it is likewise desirable that the independently variable factors governing the product or process be quantities, although this ideal goal is not always attained. Maximum efficiency—i.e., the attain- ment of the maximum amount of reliable, useful information relating to the influence of, the factors on the property of the product or characteristic of the process, for the least expense—is an important requirement for the satisfactory operation of a research organization. Obviously, a necessary condition for the attainment of maximum efficiency is an adequate knowledge of the specialized field in which the experimental research lies. While necessary, this condition is not sufficient. Proper attention must also be given to the general principles of experimental design together with the modern methods for the analysis and evaluation of experimental data. The Present discussion is confined to a single design, the so-called "factorial" design. This design is of special interest in that it attains its goal, maximum efficiency, by directly departing from the

Jan 1, 1948

By M. K. Barnett

Engineering research consists, broadly speaking, in the investigation of the effect of the variations in a number of factors on some property of a product or characteristic of a process. The unambiguous description of the product or process requires that the property or characteristic be expressible in quantitative terms. For the purpose of practical control, it is likewise desirable that the independently variable factors governing the product or process be quantities, although this ideal goal is not always attained. Maximum efficiency—i.e., the attain- ment of the maximum amount of reliable, useful information relating to the influence of, the factors on the property of the product or characteristic of the process, for the least expense—is an important requirement for the satisfactory operation of a research organization. Obviously, a necessary condition for the attainment of maximum efficiency is an adequate knowledge of the specialized field in which the experimental research lies. While necessary, this condition is not sufficient. Proper attention must also be given to the general principles of experimental design together with the modern methods for the analysis and evaluation of experimental data. The Present discussion is confined to a single design, the so-called "factorial" design. This design is of special interest in that it attains its goal, maximum efficiency, by directly departing from the

Jan 1, 1948

By M. Muskat, H. G. Botset, R. D. Wycoff, M. W. Meres

The subject of the flow of homogeneous fluids—gases alone or gas-free liquids—through porous media may be considered at the present time to be fairly well completed. That is, analytical, graphical, numerical, or experimental methods are now available for obtaining detailed descriptions of the behavior of such homogeneous fluid systems of any reasonable geometry. Thus, satisfactory empirical techniques are now well established for the determination of the permeability of porous media for homogeneous fluids, the numerical magnitude of this permeability uniquely and completely describing a porous medium as a carrier of a homogeneous fluid. Considering this constant as known, the treatment of a wide variety of specific problems involving either the flow of gases or liquids has been carried through to satisfactory conclusions. Beginning with the simple case of strictly radial two-dimensional flow of a liquid or gas into a well under steady-state conditions, generalizations have been developed to apply for systems where the flow is not strictly radial, due either to a lack of uniformity in the reservoir pressures at points distant from the well or deviations from circularity of the external boundary whereby the fluid is being supplied, and finally, to the lack of complete penetration of the well into the producing strata. Satisfactory descriptions are now available for cases where gravity is acting as the driving agent inducing the flow of liquid into the well, either alone or as a supplement to the effect of pressure. The effect of acid treatment on limestone wells has been given a reasonable interpretation on the basis of the fundamental theory of the flow of homogeneous fluids through sands, as have the important features of the problem of water-coning. Then, too, systems in which the outlet of the fluid from the underground reservoir is of a predominantly multiple character may be now considered as in the domain of

Jan 1, 1937

By S. L. Payne, J. P. Morris, R. L. Kipp, G. R. Zellars

The activities of iron and nickel in liquid Fe-Ni alloys were determined by measuring the vapor pressures of iron and nickel above the alloys and comparing with the vapor pressures of the pure metals. Nickel was found to deviate negatively from Raoult's law over the entire composition range. Iron behaves ideally down to 0.7 mole fraction but shows negative deviations at lower concentrations. At 1600°C the activity coefficients at infinite dilution are 0.40 for iron and 0.66 for nickel. 1 HE formulation of the conditions of chemical equilibrium between liquid metals and gases or slags is an important application of thermodynamics to pro- cess metallurgy. Usually the metal and slag phases are solutions of several components; and for accurate calculations, it is often necessary to use the activities of the components in place of their concentrations. Data concerning activities, however, are quite meager. The evaluation of the activities of iron and nickel, presented in this paper, is part of a project to determine activities in iron alloys at elevated temperatures.

Jan 1, 1960

By Arthur Winslow

Introductory.—The following paper is based upon a report on the lead- and zinc- deposits of Missouri, prepared for the State Geological Survey, which is now being printed. This report is the outcome of work prosecuted by the writer, assisted by Mr. J. D. Robertson, during the past five years. The studies in the State were supplemented by examinations of the similar ore deposits in Wisconsin and Arkan- sas. The report will contain in all about 800 pages, and the aim has been to make it complete and exhaustive, especially in descriptive matter. Naturally, only a brief outline can be presented here, and the reader is referred to the report itself for further details. Contents. I.—History and Statistics, . . 636 II.—Topography of the Region, . 639 III.—General Geology, . . .639 The Archean, . . .639 The Algonkian, . . 640 The Silurian, . . .640 The Devonian, . . 640 The Lower Carboniferous, 641 Tie Coal Measures, . 641 The Tertiary, . . .641 Structural Geology,. . 642 IV.—The Ore-Deposits, . . .643 Geologic Distribution, . 643 The Forms of the Ore-Bodies, . . .641 The Composition if the Ore-Bodies, . . .645 Gangues, . . . 645 Minerals, . . .618 Paragenesis of Minerals, . . . 651 The Structure of the Ore-Bodies, .... 651 V.—Descriptions of Types, . . 652 The Eagle Mines, . . 652 Shaft No. 23, . . 652 The Western Zinc Company or Oswego Lands, 651 The Gobar and Tomlinson Shaft, . 655 The Alba Company's Mine, 656 The Victor Mine, . . 658 The Bonne Terre Mines, . 660 General Geology, . 660 The Ore-Bodies, . 661 The Vallé Mines, . . 664 The Garatee Mines, . 664 The Corn-Stalk Diggings, . . .665 The Virginia Mine, . 666 The Conlogue Mine, . 667 VI.—The Mode of Formation of the Ore-Bodies, . . 670 The Formation of the Cavities. . . . 670 The Filling of the Cavities, . . . .675 The Formation of the Breccia Deposits, . . 673 The Formation of Circle Deposits, . . .674 The Impregnated Deposits of the Southeast, . 676 VII.—The Origin of the Metalliferous and Other Minerals, 676 1. Originally Deposited in Concentrated Condition, 676 2. Derived from Great Depths, . . .677 3. Original Diffusion, Supplemented by Lateral Secretion, . . . 678 4. Concentrated Through Surface Decomposition, 681

Jan 1, 1895

By C. W. Washburne

Recently, Messrs, Mills and Wells1 published a thorough chemical study of the waters associated with oil in parts of the Pennsylvania, Ohio, and West Virginia region. Many of their conclusions are of general application and the writer wishes to discuss some of these. Messrs. Mills and Wells show that the composition of the deep brines oi the Appalachian fields is such as would be produced by the evaporation of sea water and the precipitation of sodium chloride, combined with reactions with hydrocarbons and other substances. The brines are altered, also, by considerable mixing with meteoric water. They give good reasons for believing that the concentration of the brines was produced by evaporation in the rock pores induced by migrating gas, much of which probably escaped to the surface of the ground. This hypothesis was considered by the writer in a former paperJ2 in which main stress was laid on a second hypothesis, that the excess of chlorine in the deep brines may have been due to the entrance of solutions rich in magnesium and calcium chloride which ascended from a deep, possibly intratellurie, source. Messrs. Mills and Wells present good arguments for the first hypothesis. Underground evaporation by ascending gases probably will be accepted as the best available explanation of the concentration and composition of deep well waters. They have not considered the possibility that salt waters in deep sands may be concentrated by the diffusion of water vapor through gas into shale. The writer has given reasons3 for believing that capillary forces concentrate gas and oil in the larger openings of rock, such as the pores of sandstones embedded in shale. The gas underground must be nearly saturated with water vapor at all times, because it always is in contact with the interstitial water of enclosing shales and of the sandstone. Experimental studies of soil moisture have shown that approxi-

Jan 1, 1921

By J. R. Long, E. T. Hayes, D. C. Root, R. S. Dean

THE U. S. Bureau of Mines has recently reported on the development of a process for preparing pure ductile titanium in substantial quantities' and on the physical properties that may be attained in the metal, when consolidated by powder metallurgy methods and fabricated by certain hot and cold-working procedures.2 The high physical properties (Table I), combined with excellent corrosion resistance and light weight, will lead no doubt to appropriate applications of the metal. In any application, methods of joining will be of considerable importance. The relatively high activity of the metal toward the common gases raises the question of weldability and conditions that might be required for successful welding. Since hydrogen, oxygen, and nitrogen embrittle the metal, it should be protected from these gases at elevated temperatures. This was demonstrated by a few preliminary trials of arc, gas, and resistance welding. In these trials only the resistance method proved to be immediately applicable. While atomic hydrogen welding of titanium may be successful in some instances, a considerable amount of development work will be required to prove its worth. In addition, it would be suited only to small assemblies that could be heated subsequently in a high vacuum to remove embrittling hydrogen. Heli-arc methods likewise would be limited to small assemblies, which could be completely protected by a helium atmosphere. It was quite apparent that titanium required more protection than was afforded by the normal flow of helium gas used for welding magnesium and aluminum. The hot metal is attacked by oxygen and nitrogen, and the rapid diffusion of the oxide into the metal prevents the formation of a protective coating and requires the helium atmosphere to be maintained until the weld has cooled nearly to room temperature. The preliminary work indicated that titanium could be successfully spot-welded without deterioration of the metal and that the microstructures of the welds were normal, exhibiting good bonding, and no oxidation. The high resistivity of titanium (53 microhms per cu. cm.) suggested that it would behave somewhat like stainless steel and allow considerable latitude in the several welding variables. The results reported here are intended to give a general picture of the effects of varying welding current, welding time, and tip pressure on single spot welds made on several different thicknesses of titanium sheet. The work was undertaken to demonstrate the feasibility of welding titanium rather than as an exhaustive study of spot welding. There are, therefore, a number of factors that will require further investigation to establish the specific controls required for actual applications.

Jan 1, 1946

By R. J. Sandrea, S. M. Farouq Ali

The results of an experimental and theoretical study of the effects of rectilinear impermeable barriers and highly permeable channels on the sweep efficiency and conductivity of a five-spot network are presented. The study was carried out using Hele-Shaw, and conductive sheet analogs for both. normal and inverted flood patterns. A functional relationship was developed which provides quantitative prediction of the above parameters; i.e., sweep efficiency and conductivity, for the nonhomogeneous system. To evaluate this, it is necessary only to measure the interference modulus of the obstacle using a simple expression. The results indicate that impermeable barriers, with an interference modulus greater than zero, always cause a decrease in the conductivity and the sweep efficiency of the pattern. On the other hand, permeability channels do not have a significant effect on these parameters, unless they are located along the streamlines. The study also discusses a method of formulating the difference equations pertaining to the two-dimensional Laplacian in a system containing rectilinear barriers. In addition, a technique is described for tracing the progress of a free surface, using marked particles, in a stream containing discontinuities SuCh as those occurring at the extremities of barriers. The above computational scheme was used in a digital computer program to simulate results of the Hele-Shaw analog. The computed values of sweep efficiency mere in good agreement with the experimental values. INTRODUCTION At the present time waterflooding remains the most widely used technique for the secondary recovery of oil. Among the numerous factors that affect the performance of a waterflood, the areal sweep efficiency constitutes one of the most critical parameters. It is a function only of the geometric distribution of the wells for a homogeneous medium and unit mobility ratio. Geological considerations, however, such as the presence of sealing faults or solution channels in the rock matrix, would generally exert an adverse effect on the areal sweep efficiency of a waterflood network. Surprisingly little information is presently available on the quantitative implications of such permeability interferences. It was the object of this investigation to consider the presence of rectilinear, impermeable and highly permeable interferences in an otherwise homogeneous five-spot pattern, and to analyze their effects on the resulting sweep efficiency and pattern conductivity. The experimental phase of the study was conducted using two different models: the Hele-Shaw flow cell and the field plotter. For experimental convenience, the geometric boundaries of the five-spot were assumed to constitute streamlines even in the case where the interference was asymmetrically placed with respect to a repeated five-spot pattern. A second object of the study was to develop a computational scheme for numerically calculating the pressure distribution in a five-spot flow pattern containing rectilinear, impermeable barriers, and to use this distribution to compute the sweep efficiency. EXPERIMENTAL PROCEDURE HELE-SHAW ANALOG The Hele-Shaw analog was used both as a visual model and for determining the sweep efficiency for systems involving impermeable barriers. The physical limitations of this model as a means of experimentally studying the motion of a fluid in porous medium have been adequately discussed elsewhere.2,7 Likewise, it can be easily verified that the analogy remains valid when a portion of the region between the plates contains an obstacle of the same thickness as the distance between the plates. The model used in this study was composed of