Search Documents

By A. S. Nowick, E. S. Machlin

One of the main criteria used to rate the heat-resisting properties of alloys is stress rupture.' During a stress-rupture test a tensile specimen is held under a constant load at a constant temperature until it fractures. The chief measurement made during this test is the time requird for rupture at the specific test stress and temperature. It was found empirically from a series of stress-rupture tests at a constant temperature that when the logarithm of the time for rupture is plotted against the logarithm of stress a straight line is obtained within experimental error This method of showing stress-rupture data has been adopted by many investigators and the NACA.' By interpolation and extrapolation from these plots, values of the stresses required to rupture the specimens (the rupture strengths) in 10, roo, and 1000 hr are obtained for specific temperatures. Alloys are then rated for a particular application on the basis of their rupture strengths at the rupture life that most nearly represents the application. Inasmuch as stress rupture is an important criterion in rating heat-resisting alloys, it would be advantageous to know the quantitative dependence of the time lor rupture on stress, temperature, composition, and structure. In order to obtain this information, an investigation was made at the NACA Cleveland laboratory during the spring of 1945. The theory of rate processes was used because it has been found to apply to certain processes such as chemical reactions, viscous flow, and creep that occur at a definite rate for given conditions. It was thought that stress rupture was such a process. An equation was derived that gives, for a given composition and structure, the dependence of the time for rupture on stress and temperature. The investigation is part of a general program to provide information that will lead ultimately to the development of better alloys in order that the efliciency and power output of gas turbines used in aircraft propulsion can be increased. Theory The theory of rate processes will first be discussed as a general theory. It will then be shown that if stress rupture of heat-resisting alloys can be treated as a rate process, certain equations must be satisfied. Later sections will then show that these equations are satisfied. General Theory of Rate Processes The theory of rate processes5 developed by Eyring and others has been applied to chemical reactions as well as to other processes such as viscosity of liquids and diffusion. In every case in which rate-process theory can be applied, there is a small subdivision, so that the macroscopic process is the net effect of all the small processes. This smallest subdivision is called the "unit process." For example, in a chemical reaction the unit process is

Jan 1, 1948

By A. S. Nowick, E. S. Machlin

One of the main criteria used to rate the heat-resisting properties of alloys is stress rupture.' During a stress-rupture test a tensile specimen is held under a constant load at a constant temperature until it fractures. The chief measurement made during this test is the time requird for rupture at the specific test stress and temperature. It was found empirically from a series of stress-rupture tests at a constant temperature that when the logarithm of the time for rupture is plotted against the logarithm of stress a straight line is obtained within experimental error This method of showing stress-rupture data has been adopted by many investigators and the NACA.' By interpolation and extrapolation from these plots, values of the stresses required to rupture the specimens (the rupture strengths) in 10, roo, and 1000 hr are obtained for specific temperatures. Alloys are then rated for a particular application on the basis of their rupture strengths at the rupture life that most nearly represents the application. Inasmuch as stress rupture is an important criterion in rating heat-resisting alloys, it would be advantageous to know the quantitative dependence of the time lor rupture on stress, temperature, composition, and structure. In order to obtain this information, an investigation was made at the NACA Cleveland laboratory during the spring of 1945. The theory of rate processes was used because it has been found to apply to certain processes such as chemical reactions, viscous flow, and creep that occur at a definite rate for given conditions. It was thought that stress rupture was such a process. An equation was derived that gives, for a given composition and structure, the dependence of the time for rupture on stress and temperature. The investigation is part of a general program to provide information that will lead ultimately to the development of better alloys in order that the efliciency and power output of gas turbines used in aircraft propulsion can be increased. Theory The theory of rate processes will first be discussed as a general theory. It will then be shown that if stress rupture of heat-resisting alloys can be treated as a rate process, certain equations must be satisfied. Later sections will then show that these equations are satisfied. General Theory of Rate Processes The theory of rate processes5 developed by Eyring and others has been applied to chemical reactions as well as to other processes such as viscosity of liquids and diffusion. In every case in which rate-process theory can be applied, there is a small subdivision, so that the macroscopic process is the net effect of all the small processes. This smallest subdivision is called the "unit process." For example, in a chemical reaction the unit process is

Jan 1, 1948

By Francis T. Christy

One aspect of ocean mining that is frequently overlooked in discussions is the problem of establishing some form of legal control over the seas. Much of the discussion centers on mining in territorial waters, which are controlled by the various countries according to the Geneva Convention on the Continental Shelf, and perhaps by political subdivisions of countries such as the individual states of the U.S. But as technology improves and the mining of deeper waters becomes feasible, the problem of rights outside the continental shelf and territorial waters becomes a significant factor for anyone expending the time and capital for development. Several schemes are possible for regulating ocean mining but as yet none have been instituted, except what might be termed the "wait and see" approach. Even some of the coastal states in the U.S. have no regulations governing mining in the territorial waters under their jurisdiction. Until some regulation is formulated, there may well be little development in ocean mining due to the high risk of capital involved, both with respect to companies wishing to invest their own funds and financial institutions funding a venture to develop offshore mineral deposits.

Jan 7, 1968

By C. A. Kroetz, A. J. O’Neal

The Long Island Lighting Co. has operated an extensive monitoring system for over three years. Nearly 900,000 separate pieces of information have been recorded for a land area of some 600 sq miles, 15 miles north to south by 40 miles east to west. The data are composed of about a half million sulfur dioxide measurements at various locations, 290,000 of which were by the West-Gaeke method, about 160,000 pieces of weather data, and 220,000 measurements of sulfur dioxide as emitted from each of the power plant stacks on the system, all measured on an hourly basis and stored on computor cards and tapes. The computor has been programmed to collate stack emissions, weather information, and ground level sulfur dioxide measurements. The analysis shows that emissions from tall stacks do, indeed, contribute very little to ground level sulfur dioxide. For example, LILCO shows that its Northport plant contributes less than 2 ppb, hourly annual average. They also state that the plant converted to 100% natural gas or shut down, would reduce ground level sulfur dioxide by no more than 2 ppb.

Jan 1, 1973

By William E. Bruce

This paper is intended to provide an improved understanding of natural draft (natural ventilating pressure) and the effect of natural draft on underground mine ventilation circuits. Attention is focused on measurement of natural draft pressures during ventilation surveys in mechanically ventilated mines and on different methods for modeling natural draft using the measured data. A number of examples are presented which utilize data collected during absolute air pressure surveys made by personnel of the Ventilation Division of the Mine Safety and Health Administration's Safety and Health Technology Center, Denver, Colorado. Examples are used to illustrate how the data from absolute air pressure surveys may be interpreted to determine whether natural draft pressure is present and what its magnitude is. In addition, two different methods are described for mathematically estimating the magnitude of the natural draft pressure. Comparisons are made of results obtained using the different methods. Different procedures are described for modeling natural draft using the MSHA-modified Penn State computer program. Use of the routines is described and illustrated relative to drafts that aid or oppose the mechanical ventilation system. Tabulations of results facilitate comparison of outcomes obtained using the different modeling procedures.

Jan 1, 1982

By Martin J. Conway

DURING the past year, the intense interest shown by the metallurgical industry in the use of relatively pure oxygen has been evidenced by the number of papers dealing with its application and production. The reason for this interest is apparent when it is realized that, weight for weight, oxygen enters into the formation of steel equally with iron. In the manufacture of steel, approximately one ton of oxygen is required to produce one ton of ingots. Until the recent development of plants capable of producing oxygen at far lower costs than had ever previously been considered possible, the oxygen required for steel manufacture was used as it occurs in air, where it is associated with approximately four times its volume of nitrogen. Because of the diluent nitrogen more than 4 tons of total gaseous material per ton of steel must be handled rather than only approximately one ton required when pure oxygen is used. In addition, provision must be made to handle the large quantity of waste, gases resulting from the process. There are cases where the reduction in gas volume alone can justify the installation of an oxygen plant.

Jan 1, 1947

By Reynold Q. Shotts

Chemical methods, based on the relative rates of oxidation of fusain, bright coal, and dull coal by nitric acid, have been devised to determine these coal components.1-4 Results obtained by oxidation methods for fusain have been checked against results obtained from microscopic methods on duplicate samples of the same coals, but to the author's knowledge this has not been done for bright and dull coal components. For this reason it is not certain that the two methods of analysis identify essentially the same chemical or physical units. It would be highly desirable to see results of the application of both methods to duplicate samples, but in the absence of any such data the author has attacked the problem indirectly. From the U. S. Bureau of Mines samples were obtained of three Alabama coals which the USBM had analyzed optically and reported on over the past 30 years. These samples were subjected to analyses by oxidation rate methods. Results of this work, and comparisons with the USBM analyses, have been published. This was the first indirect approach to the problem. The present report attempts a second indirect approach by way of internal validation.

Jun 1, 1955

By Lyman H. Hart

Some of the significant facts that will affect the supply and demand for metals during the next few decades are given in this presentation. This is important because the only hope for intelligent guidance of the national destiny depends upon presenting a consistent and accurate picture of basic problems. The metals problems now fomenting are only slightly less important than those precipitating the energy crisis. Admittedly, it is difficult to generate serious thinking on this subject when the world is enjoying easy access to all metals at modest prices. This is possible because of the current world capacity to overproduce, and United States credit standing, at least up to now, has permitted buying freely on world markets. Although both these vital conditions are subject to change, there is little doubt that if the U.S. financial house is kept in order, we can muddle along for a while on a generally expanding, metalbased economy. But should our credit standing be permitted to collapse, or should there be a tightening of world supplies of metals, the nation would immediately find itself in trouble. Unfortunately, clear signals indicate that both of these conditions are threatening.

Jan 4, 1973

By E. William Heinrich

With the mounting emphasis on unconventional energy sources, total consumption of lithium minerals will increase significantly in the next decade. The recent development of the lithium battery, for example, may greatly boost the demand for lithium metal. At the same time, the growth in the ceramic, glass, and chemical industries is bound to increase the demand for lithium minerals. In fact, the entire consumption or utilization breakdown of lithium minerals will change considerably from its current pattern. Briefly, today's market for lithium minerals' can be grouped into three categories: (1) Lithium concentrates. Accounting for 57% of market use, these concentrates are beneficiated Li-A1 silicates for ceramic, glass, and glass-ceramic raw materials. The concentrates are chiefly spodumene; inverted iron-depleted beta-spodumene; and petalite or its isochemical decomposition product spodumene + quartz intergrowth ("squi"). In the past, lepidolite has also been used.

Jan 9, 1974

By Fred H. Brooks

INTRODUCTION The toughest job for any mining company, large or small, is to locate and identify a property which it feels has the potential for development and which can be tied up through location, lease or option under terms within their means. In the case of a small company, this precludes grass-roots exploration with its attendant high costs and the extended time required to develop a prospect to the point of being a project. The small mining company, therefore must limit its search to known properties which, for various reasons, have been shut down or were never thoroughly developed at the time of discovery. These types of prospects are located either through literature search, familiarity with many mining areas in general, or through contacts and submittals from a variety of sources. In order to develop a marketable presentation to any investor, the basic requirements are the same: - the property must demonstrate the potential to provide a satisfactory return on investment - the evaluation study must be thorough and professionally developed. In order to promote any mining property, it is first necessary to know what you have. INFORMATION DEVELOPMENT We normally begin with a detailed literature search of the district, assembling all available data on the basic geology, production records, and old reports of this or neighboring properties and any other information which can be found. This will aid in the general understanding of the basic geology and hopefully allow a fairly detailed knowledge of the specific occurrence. With this information one can begin to speculate on the reserve potential and develop some high and low figures for estimating purposes as to mining method, production rate, metallurgy and begin developing estimated capital and operating costs. Cashflow runs are developed for varying tonnages (high and low), estimated high and low grades of metal and at differing market prices for the product. FINANCE CONTACTS Brooks Minerals, from its inception, has been an operating company and we have been able to assemble a small but experienced operating staff. For this reason we try to put together projects and joint ventures where we can be the operator and maintain a certain degree of control. Whether due to familiarity with many colleagues in the mining industry or due to unfamiliarity with the banking houses and securities markets, the approach to raising finance has generally been to contact the established mining companies. This requires a familiarity with the corporate philosophies of these companies with respect to their development goals and financial capabilities. A common mistake is to shotgun the proposal to many companies of different sizes and goals in hopes that one might be interested. It is more beneficial, when possible, to tailor a proposal to each company, stressing the positive points where the specific proposal best meets their interests. One company may be more interested in a development program with fairly certain and conservative return potential. The property may well contain both possibilities but a lack of understanding of the individual company's method of operation could spoil the deal. In another instance, one company may look at a property as a moderate income producer over an extended life, yet a second may elect to high-grade the deposit over a shorter period in order to provide early cash flow or take advantage of a favorable market situation. MAKING THE DEAL There are as many types of deals as there

Jan 1, 1985

By C. S. Brooks

Several of the commonly used methods for deter-mination of effective grain densities of minerals have been evaluated for accuracy and precision, and their applicability to various types of petroleum reservoir minerals tested. Consideration was given to the effect of consolidation, swelling clay, and wettability on these grain-density determinations. Procedures with helium displacement, a modified low-pressure Boyle's law porosimeter, and liquid displacement (water, n-decane, and n-octanol) were tested. The helium-displacement procedure was used primarily as an independent reference for which the effects of fluid-solid interaction, e.g., adsorption and wettability, were negligible. The procedures with the Boyle's law porosimeter and with liquid displacement are the methods in common use. Minerals investigated included calcite, West Texas limestone core samples, California sandstone core samples, and Wyoming bentonite. The number of samples tested, while not large, was adequate to permit application of statistical methods. Grain-density measurements on calcite (Iceland spar) provided a basis of comparison for the accuracy and precision of the procedures under investigation for a material with a high degree of chemical and physical homogeneity and for which fluid-solid interactions were at a minimum. Liquid-displacement procedures (water or n-decane) provided the greatest reliability and precision for measurement of the grain densities of the limestone tested. Gas-displacement procedures (helium or Boyle's law porosimeter) provided the greatest reliability and experimental convenience, if not the greatest precision, for the measurement of the grain densities of the swell- ing clay, Wyoming bentonite, and the shah sandstones which -contained appreciable amounts of swelling, in-terstitial clays. These experiments were designed to evaluate the applicability of the grain-density procedures in common we to some of the less tractable minerals—tight limestones, shaly sandstones, and swelling clays. The results should provide a useful basis for a selection of the method most suitable for application to the various petroleum reservoir minerals encountered and especially for use in the estimation of formation porosity. INTRODUCTION These experiments were undertaken to evaluate the accuracy and precision of several commonly used methods for determination of effective grain densities of minerals, and to test their applicability to various types of petroleum reservoir minerals. Consideration was also given to the effect of consolidation, clay, and wettability on these grain-density determinations. Procedures used included measurements with helium displacement, with a modified low-pressure Boyle's law porosimeter, and with liquid displacement (water, n-decane, and n-octanol). The minerals investigated included calcite, West Texas limestone core samples, California sandstone core samples, and Wyoming bentonite. The accurate determination of the porosity of petroleum reservoir formations, in particular those of low porosity, has received much attention. Both bulk-volume and grain-volume measurements necessary in the evaluation of porosity have been examined by many investigators with the objectives of improving both the accuracy and the precision of these determinations. In this investigation statistical criteria for selection of the most reliable and suitable procedure for use with a given type of mineral are demonstrated. The grain-volume measurement procedures appear to be the most susceptible to improvement.

Jan 1, 1958

By C. H. Lee, R. Maddin

The diffusion rates of Ag110 in cylindrical single crystals of 99.99 pct pure silver, which were twisted to a total surface strain of 0.91 during the diffusion anneal at temperatures of 700°, 750°, and 800°C, were measured by sectioning and counting as a function of the strain rates. The ratio of the diffusivities while strain ing occurred (Ds) to those of the unstrained specimens varies linearly with the rate of twisting and attains values of near 100 for some of the rates used. The enhancement of diffusion by straining is inversely proportional to the temperature at which diffusion occurs. The activation energy for diffusion determined from the data plotted as a function of the rate of twisting decreases from 44,090 cal per mole for zero strain, to an asymptotic value of 21,000 cal per mole for the strain rates of 22 x it)"5 see-l. Qualitative explanation for the observations based on the generation of nonequilibrium number of defects by plastic deformation will be discussed. The initial research of Buffington and cohen1 on self-diffusion in a iron under compressive stresses contributed the first quantitative information concerning the effect of applied stresses on diffusion. These results were obtained from radioactive Fe55 plated on one of the horizontal surfaces and compressing the large-grained specimens while the diffusion-anneal was occurring. Enhancement of diffusion of a maximum of seventeen times was observed provided the strain was in the tertiary stage of creep and the rates of straining were at least as fast as rates used in the normal creep test. On the other hand, Darby, Tomizuka, and Balluffi,2 extending silver single crystals up to 30 pct elongation at rates of straining about equal to those used by Buffington and Cohen observed no effect. For the past two and a half years at the University of Pennsylvania, we have been investigating the effect or torsional strains on self-diffusion in silver single crystals. If enhancement is observed as has been reported1 a possible explanation may be based upon the generation of fairly large numbers of point defects and their role in the diffusion process. Hence, since torsion should produce an abundance3 of point defects, an increase in the diffusivity while the crystal is being twisted should easily be measured. EXPERIMENTAL PROCEDURE Our research uses single crystals of silver prepared from 99.99 Ag by the Bridgman method in a dynamic vacuum of less than 25 µ. As grown, they are about 25 cm long by 1.3 cm in diam. The crystals are cut into 7.5 cm lengths with a jeweler's saw and machined to the shape shown in Fig. 1. The test length of the crystal is machined to a 0.6 cm diam after which the ends are masked and the test section etched heavily in HNO3, and KCN:(NH4),S2Os , solution to remove the effects of machining. The specimen is then annealed in vacuum for 8 to 12 hr at 800°C to remove any residual stresses and also to recrystallize the end sections. The recrystallized ends are necessary since experiments showed that single-crystalline end sections are too soft to transmit the desired torque. Occasionally, recrystalliza-

Jan 1, 1960

By Henry A. Stiff, J. P. Hammond, A. B. Westerman, H. C. 195-000-000-014 Cross, and Lawrence E. Davis

The phases in Cr-Fe-Mo alloys have been investigated with homo-genization, aging temperature, composition range, and alloy addition as variables. Metallography, three X-ray methods, and hardness were used as methods of study. The behavior of s, M23,C8, and Z phase are reported for cornpasition range 60 pct Cr-15 to 25 pct Fe-15 to 25 pct Mo-<0.005 to 0.36 pct C with aging at 1400º to 2000°F. With 2 pct Ti, Tic and TiC-TiC are formed; with nitrogen Cr2N. THE recently developed class of chromium-base heat-resistant alloys shows appreciably higher strength than commercially used high temperature alloys. However, further developmental work is required to impart needed shock resistance and some degree of room-temperature ductility to these alloys. Extensive exploratory work on chromium-base alloys was begun in a program initiated by the War Metallurgy Committee of the National Defense Research Council at the Climax Molybdenum Co. in the early part of 1942.&apos; Alloys were sought for gas-turbine blades for use at 1600°F. A minimum of 5 pct elongation in the stress-rupture test was a requirement. From the Climax work, ternary alloys of chromium, iron, and molybdenum appeared to show the greatest promise as materials for gas-turbine blades. The composition line in the ternary diagram joining the 60 pct Cr-15 pct Fe-25 pct Mo and 60 pct Cr-25 pct Fe-15 pct Mo alloys was indicated as representing the most useful combination of strength and ductility.&apos; Strength increased while ductility decreased as molybdenum was raised in this composition range.&apos; The 60 pct Cr-15 pct Fe-25 pct Mo type alloy was thought to have the most suitable properties for gas-turbine blades.&apos; Concurrent with the study reported here, other investigations were being made on Cr-Fe-Mo alloys. The liquidus temperatures on a series of low carbon, ternary alloys were being determined, and isothermal sections drawn at 2370°, 2010°, and 1650°F (1300°, 1100°, and 900°C).2 Also, various methods of preparation and some mechanical and physical properties of chromium-base alloys, particularly the 60 pct Cr-15 pct Fe-25 pct Mo type, were being investigated., At the inception of the present program, only a limited study had been made of etchants for developing the microstructures of chromium-base alloys; X-ray analysis of the microconstituents had not been made. A review of the literature revealed that no phase-diagram work had been reported on the Cr-Fe-Mo system. Scope of Work The work on chromium-base alloys includes the following: 1—The development of etching methods for differentiating between the microconstituents; 2—The identification of microconstituents by X-ray diffraction methods; and 3—A comprehensive metallographic and hardness study after various heat treatments. The phases were studied by three standard X-ray techniques: 1—The block-sample focusing-camera method; 2—The powder-diffraction method on elec-trolytically separated residues; and 3—The powder-diffraction method on cold-worked aggregate samples. The results by the first two methods were correlated with the metallographic data. The third method was used largely to study conditions approaching equilibrium, since cold working prior to heat treating accelerated precipitation. Seven types of alloys were investigated: 50 pct Cr-50 pct Fe, 40 pct Cr-40 pct Fe-20 pct Mo, 55 pct

Jan 1, 1953

By Will Mitchell, Ford F. Miskell, C. L. Sollenberger

THE taconites in general are hard, tough ores, difficult to grind. Liberation of iron mineral constituents usually is accomplished by grinding the ore through at least 100 mesh, and often it has been found necessary to grind substantially through 325 mesh to achieve satisfactory recovery and grade in the concentration process. Because of the fineness of grind required and the enormous tonnages of material contemplated for treatment in the future, costs resulting from grinding media wear and power consumption, together with capital investment required for comminution, approach astronomical figures. Economy in any one of these elements per ton of material ground could very well reflect a considerable saving to the ferrous industry in yearly costs. With this in mind, the Research Laboratories of Allis-Chalmers Manufacturing Co. have launched a program to discover means of effecting this economy. The initial phase of the work as described here deals with a heat treatment of crushed raw ore, followed by thermal shock in cooling, for the preparation of rod mill feed. Several investigators 1-5 have noted an improvement in the grindabilities of ores treated in this manner. One investigator2 subjected low grade iron ores to heat treatment in an electric furnace. Basing his conclusions on screen analyses of crushed products, he observed that treated ore was more easily crushed than the untreated. He reported that observation of the treated and untreated ore through a microscope revealed cracks following the grain boundaries in treated ore, whereas no cracks were present in untreated ore. However, few if any have quantified the improvement in terms of total hp hours saved, reduction of wear of grinding media, or reduction of capital costs of grinding equipment involved. By means of Bond rod mill and ball mill grindabilities6 and by comparative wear tests, the conditions maintained during this investigation have been definitely evaluated. Heat treatment experiments have been made on a batch scale in a muffle furnace, followed by continuous scale experiments in a rotary kiln under various conditions of temperature, atmosphere, retention time, and quenching to determine the combination that would give the greatest improvement in the grindability of a taconite without affecting adversely the magnetic susceptibility of the magnetite. From these data, relative costs have been calculated for grinding both untreated and heat treated ore on a basis of plant capacity of 120 tons per hour. Heat requirements for a rotary kiln, as well as the kiln capacity required for the treatment, have been estimated. For these tests 50 tons of ore were obtained from the Aurora mine of the Erie Mining Co., Hibbing, Minn. The ore was reported&apos; to have been selected from the magnetic portion of the lower chert horizons. An average chemical analysis of this portion is shown in Table I and an approximate mineralogical analysis is shown in Table II. No attempt was made to differentiate between the various silicates because the compositions vary widely on the different horizons and depend on the degree of oxidation. Minnesotite, however, is the predominant silicate. The siderite grains were dispersed throughout the ore but were essentially associated with the rock-forming minerals. In a series of preliminary tests in which batches of -6 mesh ore were heat-treated in a muffle fur-

Jan 1, 1952

G. D. Kneip, Jr., and J. 0. Betterton, Jr. (Union Carbide & Carbon Corp., Oak Ridge, Tenn.)—The authors have contributed to the theory of zone melting by considering the effects of the solidification of the final zone on the distribution curves for the finite length bar. However, they do not consider in sufficient detail the restrictions imposed by the particular metals involved. Eq. 4 has the analytical solution which is equivalent to Pfann&apos;s&apos; equation for normal solidification of the final zone. For distribution coefficients less than one, it is apparent from this form of the equation that, as the solidification approaches completion, the concentration attains extremely large values which are inconsistent with the density of physical materials. The necessary restrictions then are that the solute concentration cannot exceed the density of the alloy, or more frequently, the solubility limit in the solid phase. Secondly, the distribution coefficient cannot be constant from 0 to 100 pet solute unless the liquidus and solidus coincide over this whole region. It would thus be more correct to impose limits on the solubility such as would be indicated by a typical eutectic diagram. Furthermore, in this case the assumption that the distribution coefficient remains constant is more likely to be realized. Eq. 4 should then be replaced by the following C,,(x) =k/L-x [ ?11 3 C11 (x)Ddx - ?11 4 Cn(x)dx= k[Cn (L-l)/k] [ L-x/l]x-1 L-l = x = L-l [kCenterlie/Cn (L-l)]1/k-1 The typical shape for the distribution curve in the final zone is indicated schematically in Fig. 12 for the simple eutectic case. The solidification proceeds according to Pfann&apos;s&apos; expression until the concentration reaches the maximum solubility in the solid phasc. At this point, the concentration changes abruptly to the eutectic composition and remains at this value for the duration of the solidification. The width of the flat region, and the back reflection of this effect into the concentration curve on subsequent passes, depends upon the ratio of the eutectic concentration to the original concentration, upon the distribution coefficient, and upon the number of passes. Similar effects on the concentration curves in the first zone length would be expected in many systems for which the distribution coefficient is greater than one, and where the maximum solubility is not too much larger than the original concentration. The discussers agree with the authors that the assumption that the liquid is uniform in concentration should be considered with caution. Kneip and Better-ton&apos; have shown, however, that in floating zone refining of zirconium, using induction heating, the distribution of iron agrees with theory which assumes a uniform liquid composition. Hence, in this case, the experimentally realized distribution coefficient agrees with the present phase diagram within the experimental uncertainty. L. Burris, Jr., C. H. Stockman, and I. G. Dillon (authors&apos; reply)—The authors are happy to have received the comments of G. D. Kneip, Jr., and J. 0. Betterton, Jr., which provide additional insight into the zone refining process. It is true that the equations developed are inapplicable if the solute solubility in the solid phase is exceeded. However, this restriction on the use of the equations was clearly stated in the paper. A closer approach to

Jan 1, 1957

By Porter W. Shimer

The solution used in the following method for phosphorns-determination is the filtrate obtained in the nitric and sulphuric acid method for the determination of silicon (Transactions, vii., 346). This filtrate, being easily and quickly obtained, and always quite free from silica, is a desirable one for phosphorus-precipitation. IN order, however, to get all the phosphorus in a precipitable form the solution must be made under conditions more strongly oxidizing than simple solution in boiling nitric acid. In a solution thus

Jan 1, 1889

Taking the Long View THE present international situation has serious implications for this nation. The possibility of total war is no more appalling than the threat of making the United States permanently into an armed camp. A period of ten years under such conditions could mean a Communist victory without firing a shot-if the present trend toward statism is allowed to continue. As individual citizens and as members of the mining profession we have the power to oppose the march toward socialism. We must not adopt shortsighted policies dictated by self-interest, but must endeavor to size up the situation as a whole and act according to what will be best in the national interest. The economic picture for the metal mining industry under present emergency conditions is apparently bright. Demand for metals exceeds supply. But there is danger that fluctuating prices will bring Government regulation. Care must be exercised in our pricing policies, or the calamity of Government intervention will be inevitable. President Truman&apos;s "loophole" reference to percentage depletion early in the year caused a brief flurry of excitement, but now that the immediate threat is over the industry has lapsed into sommolence on this subject. Special tax privileges accorded the mining industry because of inherent risks should be guarded by a continuing propaganda campaign to educate Congress and the public. If this is not done we may find ourselves losing the necessary tax protection which we now possess by a capricious act of legislation. Stockpiling minerals from abroad certainly lengthens the life of our own mineral resources. The present consumer demand for the base metals indicates foreign sources of supply for stockpiling. However, this is only one facet of the problem. For strategic military reasons it is necessary that the United States have quick sources of all minerals within our national boundaries. Undeveloped mineral deposits do not meet this need so that where it is possible to encourage our own mineral development by stockpile purchases, it should be done. A need exists for an overall controlling agency that would make purchases for the stockpile according to military necessity, current metal market conditions, and so as to strengthen the mining industry. In the course of the history of the United States we have been engulfed in several wars by the necessity of protecting our economic rights abroad trading privileges-and also because of moral obligations. Disregarding the moral side, it is difficult to reconcile fighting wars to protect world freedom of trade when in peacetime we attempt to restrain such trade by tariff barriers. When it comes to accepting subsidies from the Government in one form or another it is difficult to overlook the immediate personal gains and see in the future that where the Government lays out capital it becomes a partner in the business and not a silent one. It is apparent that hope for the traditional American way of life cannot be bought without some self-sacrifice; and we cannot wait for the other fellow to start it because it is the responsibility of each individual citizen. By taking the long view our course should be apparent and not diverge sharply from our own personal benefit.

Jan 10, 1950

By K. H. Coats

In tnany oil and gas fields, significant investments are required in piping networks for collection, injection and disposal of various fluids. This paper treats the problem of optimally locating the trunkline(s) for a given systet to nlinimize both the total length of piping connecting the individual wells or lease batteries to the trunkline and the length of the latter. Single and multiple trunklines, varying line sizes, and grouping of wells are considered. Some attention is paid to the case of a curved trunkline. A field case is treated and conclusions are that the problem of locating a single trunkline is relatively straightforward while the location of multiple trunklines requires further research. INTRODUCTION la many oil and gas fields, significant investments are required in piping networks for collection, injection and disposal of various fluids. A single field may concurrently require piping systems for gathering of oil, gathering of gas, injection of water or gas and disposal of salt water. Two problems arise in the consideration of any one of these networks. The first involves the sizing of the various segments of the network to minimize piping and compression costs. The second problem, treated herein, is that of optimally locating the trunkline(s) for a given piping system to minimize the total length of pipe connecting the individual wells or lease batteries to the trunkline. This minimization problem may arise in field automation if it involves replacement of individual lease batteries by a central field battery which will require trunklines and connecting pipelines to individual wells. The problem also arises in connecting a gas pipeline through a subsidiary trunkline to wells in a gas storage field. The first analysis given below treats the case of a single trunkline and of separate connecting lines for all field units.* The analysis is then extended to consider multiple trunklines and common connecting lines for groups of field units. Varying sizes, and therefore costs, of the connecting lines are taken into account. A simplified development is given to illustrate the manner in which line sizing calculations may be integrated with the line placement problem. This study is primarily directed toward the placement of straight trunklines, although for certain field shapes or well distributions curved trunk-lines might be preferable. Some mathematical consideration is therefore given to the placement of a curved trunk-line in a field. The determination of optimal locations for two or more trunklines involves some difficulties which are discussed below. The need for further research in this area is emphasized. The problem of a single trunkline is solved in relation to an actual oil field. The problem of optimally locating two trunklines in the same field is also treated and the results are compared to the single-trunkline case. All calculations reported were performed on an IBM 7072 digital compker. The importance of right-of-way, roads and terrain in locating trunklines and connecting lines is realized. The present analysis is advanced on the premise that in planning piping networks one should start with the optimal conditions whenever possible and proceed therefrom.

By A. D. Hodges

In May, 1850, the first gold from the Comstock lode was discovered in the sands near the Carson river. It had been washed down by natural agencies, through Gold Caflon, from the decomposed rock of the ledge above. Within a few weeks, the precious metal was traced more than three miles in shallow deposits along the bed of the canon, from the river to the Devil&apos;s Gate-—a narrow, rocky cleft, notable to the teamsters of a later day chiefly as the place where " Uncle Jimmy Fair" collected high tolls, and could not reduce the rates, because " this was all he had for the education of his poor children." From 1850 to 1857, a fluctuating band of miners, whose number varied from twenty to two hundred, washed the Gold Canon placers with rockers and long-toms, making four to five dollars a day each until the last-named year, when the deposits were in great measure exhausted. The chief settlement of these miners was at Johntown. During only a third of the year was the water-supply sufficient for their work. The remainder of the time they utilized in desultory prospecting of the hills and in occasional forays for supplies among the Mormons in Carson valley. In 1857, the Grosch brothers discovered the Comstock lode at some point, now unknown, in Gold Hill, but their discovery perished with them. Early in 1858, the " Pioneer Quartz Company," having located several of the small surface-veins around Silver City (whose connection with the main lode has never been definitely shown), built an arrastra, and worked some of their ore; but the returns were so small that they soon abandoned this business. The following winter, James Finney and his partners found gold in place in

Jan 1, 1891

By H. A. Shaw, H. G. G. Whitton

This paper describes the use of the electric-arc furnace for the production of tough-pitch, horizontal cast copper shapes and the production of copper anodes from tank house anode scrap. This installation is the only one of its kind in the United States. SINCE the initial use of electric-arc furnaces for refined copper melting on a commercial scale at Copper Cliff in 1936, this type of melting has been of extreme interest to everyone in any way connected with copper casting and fabricating. Early in 1948, Kennecott Copper Corp. decided to build an electrolytic copper refinery at Garfield, Utah. One of the major decisions to be made at that time was the type of furnace to be used for melting cathodes for casting into refined copper shapes and for melting anode scrap for the production of anodes. Based on the results obtained from arc furnaces by the Tnternational Nickel Co. of Canada, at Copper Cliff, and by the American Smelting and Refining Co., at Baltimore, coupled with certain important economic factors such as having an adequate amount of relatively cheap power available at the Magna Central Power Plant, high cost of poles and oil in the Salt Lake District, and the lack of natural gas at that time, the final decision was to install electric-arc furnaces rather than the standard type of rever-beratory furnaces. Experience has shown certain parts of the original installation to have been inadequate or in need of modification. Although the present status of arc-furnace melting at the Utah Refinery is far from perfect, nevertheless substantial progress has been made. At the Utah refinery, copper is melted in three 15-ft diam, size "M" Lectromelt furnaces, two of which are used for melting cathodes and one for remelting anode scrap. Each furnace is energized from a 13,800-225 v, 3-phase, 60-cycle, 6000-kva (at 40°C rise) oil-immersed water-cooled transformer. Auxiliary equipment for each refined copper furnace includes a charging machine, launders, ladle, 40 ft diam Walker-type casting wheel, bosh, and inspection conveyor. The anode furnace differs in that it is charged by hand from an elevated platform and the anodes are picked off the 24-ft diam casting wheel by a takeoff hoist and loaded directly into specially designed trailers, Figs. 1 and 2. Electrical Equipment Electric power to operate the arc furnaces is generated at the Kennecott-owned Magna Central Power Station two miles distant and transmitted to the Refinery outdoor substation at 44,000 v. At this point it is stepped down to 13,800 v and carried through concrete-lined underground tunnels to the switchgear and then to the primary side of the furnace transformers. The power is conducted from the Y-connected secondary bus bars of the transformer to the electrode arms by means of 22 flexible copper cable conductors per phase. Each cable has a cross-sectional area of 1,750,000 circular mils, giving a total area of 38,500,000 circular mils per phase. The power is carried from these cables to the three individual electrode holders by means of water-cooled copper bus tubing. The electrode clamps are incorporated in the electrode holders and are released by air pressure working against a spring in the clamp control cylinder. The movement of the electrode arms is either automatic or manual. The automatic control is used during melting and is regulated by three Westing-

Jan 1, 1954