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By G. D. Oxx, L. F. Coffin

The concept of using a phase that is liquid at service temperatures as a component of coatings for refractory metals has been described. The liquid, an alloy of gold and silicon, is retained on a molybdemum surface by a capillary system made of molybdenum disilicide. The coating has the advantage of good thermal shock and has a self-henling chracteristic. In order for highly stressed structures to exceed a service temperature of 2000°F, it has become apparent that a development that does not depend on the traditional iron, cobalt, or nickel-base alloy is needed. Alloys of the refractory metals, i.e., molybdenum, tungsten, tantalum. niobium (colum-bium), and rhenium are potentially useful at extremely high temperatures that more conventional alloys would never be expected to achieve. A new alloy of molybdenum has become available that has a 100-hr rupture strength of 35,000 psi at 2200°F.1 As a result of this work, it may be assumed that a material with adequate mechanical properties at 2200?F is now available. Unfortunately, this alloy and all other known alloys of the refractory metals suffer from not being; serviceable in an oxidizing atmosphere for a very long time. In order to permit general use of refractory metals at high temperatures, it is necessary to prevent destructive oxidation by appropriate alloying or by protective coatings. The liquid phase coating reported here is representative of a concept for the protection of metals that permits higher service temperatures and introduces a new group of materials for selection as coatings. Coating Requirements—Service conditions that represent potential applications for refractory metals vary considerably: however, it is possible to consider two conditions that are usually present. The refractory metal1 component must be heated to the service temperature at least once and usually frequently. When a solid coating is used, usually the coating and basis metal do not have the same coefficient of expansion. This difference causes thermal stress in the coating that is aggravated by rapid heating and cooling and eventually causes coating failure. The second consideration is the probability that there will be damage to the coating by some environmental condition. In jet engines, for example, it is expected that large particles, stones, metal parts, and so forth, will strike a bucket at high speed and cut a hole in the coating. In addition to the above considerations, the coating must also have other fundamental properties. Obviously, it must be oxidation resistant. In addi- tion, it must prevent permeation of oxygen and subsequent oxidation of the basis metal at the interface. Also, diffusion of the basis metal to the outside surface and subsequent oxidation there must be prevented. Finally, the coating must not react with the basis metal to form a weak bond at the interface. It should be noted that the coating need not support a load: it must only remain intact. Liquid Phase Coating Design Factors—In the use of a liquid as a principal coating constituent, it would be expected that the two service conditions mentioned above would be satisfied. A liquid would flow under the influence of the thermal strain developed by coating-basis metal expansion mismatch such that failure from this source would not be expected to occur. It is also probable that the ability of a liquid to flow would provide a self-healing effect. Thus, damage caused by particles in the atmosphere would be repaired. A third advantage is evident in that vapor pressure rather than melting point limits the service temperature. This latter advantage permits use of low melting but oxidation resistant metals such as gold or copper that would be quite useless if the solid state was required. A low viscosity liquid alone. however, is a totally unsuitable coating because it will simply flow off a component, particularly under the influence of a high acceleration field. A method of preventing liquid loss must be devised. In this case, it is desired that the liquid have a low viscosity so that it may easily flow into flaws; thus, raising the viscosity is not a satisfactory solution. One other inherent difficulty is caused by the high mobility of atoms in the liquid state as compared to the solid state. Because of this mobility, it would be expected that gases would diffuse more rapidly through a liquid. It is also probable that the solubility of oxygen in the liquid would be comparatively high. These factors would tend toward rapid permeation of oxygen and oxidation of the substrate. It is most reasonable that this problem could be solved by incorporating a solid phase, which is impermeable to gases, as a component of the coating. To overcome the tendency of a liquid to flow easily, it is possible to use surface tension to advantage. If the surface were made up of a large number of capillary tubes of sufficiently small diameter, then surface tension would hold the liquid even against the acceleration of a centrifugal field.

Jan 1, 1961

By R. J. Lutton

Empirical data from 91 rock excavations have been used to construct a family of slope curves on a chart relating excavation height and inclination. The highest and steepest slopes from each excavation are plotted and connected by a line. The 31 1ines appear to establish one or two geometrical slope fields through which the curves are projected. The curves apparently represent a lumped eflect of many factors too complex to be considered individually. Important factors such as geological structure or ground-water conditions can dominate the picture, but where these factors do not overshadow others, the slope chart should be useful for estimating or checking optimum inclination. The U.S. Army Corps of Engineers (USAE) has been engaged since 1962 with the U.S. Atomic Energy Commission in a joint research program to develop nuclear excavation technology. The Corps is responsible for collecting the requisite data on engineering and construction problems associated with nuclear excavation. The ultimate objective is to develop a capability to use nuclear explosives as a construction tool on public works projects such as harbors and canals. The present study on empirical inclination-height curves for conventionally excavated slopes is an outgrowth of an investigation' sponsored by the USAE Nuclear Cratering Group on applicability of data from existing excavations in establishing guides for engineering judgment in crater excavation. Data were generously contributed by over 50 mining companies among other organizations. Inasmuch as several companies preferred that their contribution be anonymous, all data are treated so here. Some Factors Affecting Stability Many factors affect or are suspected of affecting the stability of excavated slopes, e.g., adverse structural orientation, degree of structural ordering, ground water, climatic conditions, mechanics of excavation, and plan-profile configuration. Such factors are lumped together in developing a slope chart. Obviously geological structure and ground water can overshadow all other factors. Where such is the case, the simplification of slope charts may give an erroneous picture (not conservative enough). A further complication results from the fact that the concept of stability may vary according to the use of the excavations. For example, slope adjustments that would be regarded as failure in a powerhouse excavation, might be tolerable in a mining operation. Mine slopes are continually being modified by further excavation, and instability that would develop in a similar permanent excavation slope over a period of years might not have time to develop in a mine. Inclination vs. Height Charts Charts of inclination vs. height for particular formations or conditions have been used in the past as an aid for designing excavation slopes. Some of these have been based upon empirical analyses of collections of data and experience. MacDonald" and Lane have presented slope tables and charts for excavated and natural slopes in relatively weak sandstone and shale. Coates' has shown an inclination-height chart for slopes in incompetent rock. Most organizations have developed slope design criteria which relate bench widths, heights, and inclinations to use in various rocks. Slope data collected in present studies can be similarly used to develop inclination-height charts; however, a plot of all slopes on such a chart shows very little because of the wide spread of the data. Reasons for the dispersion of points are: (1) many slopes are not carried at optimum inclination, particularly in mines where maintaining roadways and following irregularities of ore bodies are more important than achieving steep inclinations; (2) many engineers and geologists with varied backgrounds and viewpoints have been involved in designing these slopes; and (3) each slope is characterized by a unique combination of factors affecting stability and in turn optimum inclination. Significant curves can sometimes be constructed where the points can be grouped into related clusters from the same excavation. The essence of this approach appears when only two slopes from each excavation are considered—the highest slope and the steepest slope, connected by a line segment (Fig. 1). This reduces considerably the usable data because in many cases only one of these two slopes is available. Nevertheless, the concession seems justified. Construction of Slope Curves Ninety-one pairs of points and connecting line segments were assembled in this study. The line segments were assumed to approximate a geometrical slope field (Fig. 2), and a family of curves has been visually projected through to represent the slope field. It should be

Jan 1, 1971

By Lester F. Engle

Books have been written, complex charts drawn, great batches of punched cards handled by ever increasing numbers of computers, and innumerable meetings held-all for the purpose of making effective the ultimate objective of new, revised or improved process facilities. It is to the credit of management, engineers, and others that in the vast majority of cases, the outcome of their work has been technically sound and economically rewarding. There is a way, however, to insure even better results.

Jan 5, 1966

ROBERT E. TALLY,* Jerome, Ariz. (written discussion ?).-Mr. Sherman's paper, entitled "Measures for Controlling Fires at the Copper Queen Mine," embodies two new and very important features: First, automatic closing of doors communicating with the dangerous area; second, the use of a portable storage-battery fan. His other procedures, such as giving a general fire alarm, getting workmen to the surface, etc., are equally important, but have long been in use in other places. Fire and ventilating doors in connections leading to shafts, air raises, and other large timbered areas, have been in use at other mines; but the method described by Mr. Sherman for operating these doors by compressed air, through a valve on the surface, is, so far as I know, original, and should be installed in every mine where there is danger of fire. Nearly all large mines are now using artificial ventilation, with the result that there are strong air currents in the shafts and other important workings. The most important feature in mine fires is a quick and positive control of the ventilation, for it takes but a few moments for smoke to travel over a large area, with the usual results of suffocation, and destruction of property. A strong air current in an upcast shaft acts as a draft in case of fire, and unless quickly cut off the fire would soon get beyond control. An upcast shaft usually changes to a downcast when large amounts of water are used. Human lives are in more danger from downcast currents, as the smoke travels into the workings.

Jan 4, 1918

By H. S. Coe

ENGINEERS have long recognized the desirability of correlating the data obtained from small-scale slime-settling tests with commercial work as carried on in large tanks. This need, though most apparent in designing new installations, frequently arises also in existent plants, since a large range of experimental work can be performed without interfering with regular operation. GENERAL SETTLING PHENOMENA In order to develop rational methods of laboratory testing, it becomes necessary to study the general phenomena of settling. Since it was desired to give the public the benefit of these methods at as early a date as possible, together with the knowledge of the general principles of slime settling necessary for a clear understanding of the laboratory tests, we have ventured to discuss the subject in so far as brought out by the work which we now have under way. We realize that certain of our preliminary conclusions may be subject to modification, but it seems probable that, with but few exceptions, the general laws enunciated will cover the settling behavior of all pulps encountered in metallurgical plants. However, it must be recognized that there is still a vast amount of work to be done upon certain phases of the subject; therefore, at this time we will attempt only a discussion of the behavior of ore pulps during the process of settling or dewatering, under certain given conditions. The laws and principles controlling these conditions are not fully established, so that a complete discussion of them will not be attempted in this paper. In metallurgical practice, slime pulp consists of water, finely divided sand

Jan 3, 1916

By R. L. Orr, O. D. Sherby, J. E. Dorn

Creep data for pure metals at temperatures above those at which rapid recovery occurs (above about 0.45 the melting temperature) are correlatable by means of the equations and These correlations were applied successfully to data for aluminum, iron, nickel, copper, zinc, platinum, gold, and lead as well as for simple alloys. For a given metal, AH is a constant about equal to the activation energy for self-diffusion. THE early recognition that creep is stimulated by thermal activation prompted numerous investigators', ' to apply the same laws that are valid for the viscous behavior of liquids to analyses of creep data. To a good first approximation these laws are summarized by the equation were i is the creep rate; T, the absolute temperature; R, the gas constant in cal per degree per mol; T, the applied stress; AH, the activation energy in cal per mol; S', a constant dependent on the entropy of activation, the frequency of activation, and the contribution of each activation to the strain; and B', a constant dependent upon the size of the flow unit that is activated. Although Eq. 1 describes the flow of viscous fluids very accurately, its application to the creep of solids has been disappointing. Two reasons for the failure of Eq. 1 for creep are now known: First, the decelerating creep rates during primary creep demand that the internal structures of the metals are changing and that these changes might be reflected by changes in one or more of the three creep parameters S', AH, and B'. Consequently when the conventional methods of evaluating these parameters are employed by comparing the secondary creep rates at a series of temperatures and at a series of stresses, the true effects of temperature and stress are masked because of simultaneous changes in one or more of the creep parameters. Second, as will be illustrated more fully later, three distinctly different types of investigations have shown that the stress term for high temperature creep enters the analysis as and not as t/T. This rather unexpected result points sharply to a significant fundamental difference between the mechanisms for the viscous behavior of fluids and the high temperature creep of metals. More recent extensive investigations",'4 on the creep of high purity aluminum and several of its dilute a solid solutions have shown that where E is the total creep strain; temperature compensated time = for a constant temperature test; t, is the initial stress in a constant load test or the constant true stress in a constant stress test;" and t is the duration of test. • Eq. 2 is valid for either constant stress or constant load tests; but the total creep curve is difierent (i.e. the function, f, is differentl for each test. The fundamental origin of the validity of Eq. 2 is thought to arise from some equivalence of substructures in constant load creep tests at equal values of 0 or E. Both X-ray and metallographic examination revealed that practically identical lattice distortions and subgrain sizes are obtained for the same creep strain under the same load over wide ranges of test temperature.' Furthermore the room temperature tensile properties following equal creep strains at different temperatures under constant loads were also identical, illustrating that identical substructures were indeed obtained.' " A second type of correlation was obtained by differentiating Eq. 2 with respect to time, giving For the secondary creep rate, denoted by i,, But Eq. 2 reveals that 0, is a function of a, alone because the secondary creep rate in a given constant load test is always reached at a fixed value E,". Therefore where is the function that was introduced a number of years ago by Zener and Hollomon." Eq. 4 is not only valid for creep but will permit correlations between constant load creep and tensile data where e, is the rate of tensile straining and (TC is the engineering ultimate tensile strength.

Jan 1, 1955

By N. S. Keith

No one of the live subjects of the day, to which the attention of the mining engineer and metallurgist should be turned, is of greater practical interest to him than electricity in its applications to various mechanical, chemical, and metallurgical operations. The object of this paper is to call the attention of my fellow-members and associates of the Institute to various new, as well as comparatively old, developments in the science and art of electricity which seem to promise results of advantage. Too many of the comparatively old applications have been neglected by the mining engineer, which; if he had given them a place among his appliances, would have assisted him greatly. The telegraph may be noticed as one. Its. use is, however, confined to a person having skill in the. manipulations of the key, the reading of the alphabet, and familiarity with the sounder. One of the simpler forms-the call-bell-has a range of application far greater as to distance and convenience than the old wire-pull, or the hoarse voice of the windlass-man or the bucket-dumper. A few Leclanehé cells, two or more electric bells, and a mile or more of wire judiciously placed will put the superintendent, at his office, in communication with the foremen of his mills and mines, so that by the aid of a code of signals, great advantages may be gained without necessitating a knowledge of the Morse alphabet, or of the mechanical voice of the sounder. The telephone furnishes a means of communication be-

Jan 1, 1882

By Gregory Dybalski

The purpose of this paper is to illustrate the forecast capability of the econometric model of the cobalt industry1/ as utilized by the Federal Preparedness Agency. Forecasts from this model are illustrated from the premise that the leading producer continues production of cobalt. An alternate forecast is presented where the model structure is altered to reflect the condition where the leading producer leaves the market. All estimations and forecasts presented here are shown for illustrative purposes. The cobalt industry is highly concentrated; one company, owned by the Zaire government, accounts for approximately three-fifths of world production. The cobalt supply outside of Zaire is determined by the level of activity of copper or nickel markets, as cobalt is mined as a by-product of copper or nickel. The demand for cobalt reflects a diversified usage pattern; cobalt is used mainly in heat and corrosion-resistant materials, high- strength materials and permanent magnets. According to 1974 U.S. consumption data superalloys accounted for 22%, magnetic alloys 18%, cutting and wear-resistant materials 13%, and catalyst 7%. Foreign consumption is probably similar in terms of usage categories, but the relative order of the categories is in variance.2/ The Cobalt Model The cobalt model's object is to explain consumption, supply and price movements by utilizing statistically estimated equations. Central to the econometric model is the role of Zaire as the profit-maximizing "dominant firm". Zaire sets the price that is most profitable for itself. The price of cobalt depends on industrial demand, production of other firms, and net exogenous purchases, such as government

Jan 1, 1977

By P. K. Foh, C. G. Dunn

IN an investigation of the rolling and recrystalliz-ing textures obtained from single crystals of Si-Fe, Koh and Dunn included specimens in the (111) [lie] orientation.1,2 This note reports some additional results obtained on samples of this orientation set aside for further study. After, primary recrystallization longer annealing treatments at 980°C produced only normal grain growth; after 16 hr at 980°C the largest grains were approximately 0.010 to 0.020 in. in diam. The orientations of 13 of the larger grains were found by the transmission Laue method. The unidentified (110) poles of these grains have been added to the (110) pole figure obtained after primary recrystallization2 to give the plot shown in Fig. 1. When grain identifications are also included, such a plot reveals the following. Two orientations agree almost exactly with the peak pole ,density positions of component B of the primary recrystallization texture, one with component A, and one with component C. All the remaining orientations except one have (110) poles near weaker and unidentified pole density peaks. In fact, the correlation is good enough for an identification of eight components. Previously only components A, B, and C were certain. The results are perhaps even more informative when combined with the (110) pole figure of the cold-rolled crystal to give the plot shown in Fig. 2. Each of the 13 orientations is identified and uniquely determined by selecting two (110) poles per crystal, which are 90" apart. The plot shows that every grain of the 13, except grain 6, has a (110) pole in common with a (110) pole concentration of the cold-rolled crystal. The orientation relationship with the cold-rolled orientation may be expressed as approximately 25" rotations about <110> axes, which is in agreement with the results found for coarse-grained primary recrystallization.2 If primary recrystallization had occurred according to the <110> rule without preference, there would have been 12 components. Actually our limited data reveals nine of the possible 12. The integrated pole figure also shows preferences among them, since three are considerably stronger than the rest. In addition to the above direct information, the following conclusions may be drawn. Primary recrystallization of the (111) [110] cold-rolled crystal produces a limited number of weak and strong components with the larger than average primary grains from these components related to the cold-rolled crystal by 25° <110> relationships. In arriving at this conclusion of limited orientations the (111) [110] orientation has to be ruled out as a source of large primaries for two reasons. First, growth in this orientation was not observed, despite an expected high grain boundary mobility (due to its 25" <110> relationship with every component of the texture). Secondly, primary recrystallization usually produces grains in new orientations, particularly in a single orientation matrix; but (111) [110] is not new. Other orientations besides those of the <110> type may be considered unlikely, of course, because the <110> relationship holds quite well for primary recrystallization2 and should produce the large primaries. There are exceptions to this rule, but probably not enough to provide large

Jan 1, 1958

By Charles M. Bayer

Reading in the AIME annual reports that certain activities have been financed by the Rocky Mountain Club Fund, less senior members of the Institute may wonder. "What&apos;s the Rocky Mountain Club?" Less youthful members will not have to wonder. They will recall the Club as an intriguing, almost fantastic organization, largely of western mining men, that flared across the New York horizon, flamed brilliantly for a little more than two decades, then sputtered out of existence- glorious even in its last flash. It was the only product of its mold, a fabulous group of magnanimous men who unhesitatingly sacrificed a cherished dream for which they had raised millions of dollars so that the money, instead of creating a magnificent club house, could be used instead to save the lives of starving Belgian children in World War I.

Jan 12, 1964

By H. L. Miaw, A. M. Gaudin, D. W. Fuerstenau

IN spite of considerable study,1-5 the nature of slime coatings in flotation is still not completely understood. However, phenomena that control flocculation and dispersion of colloidal systems are now interpreted in terms of electrical double layers."&apos; Colloids will flocculate even though the particles carry the same charge, but when two dispersed colloids of opposite charge are mixed, flocculation ensues even more rapidly. Analogous phenomena seem responsible for slime coating on minerals in flotation systems. To shed new light on the issue it was considered desirable to devise a tool that would measure slime coatings. The usual method has been to examine photographs of presumably representative surfaces, after an intervening washing in running water. But such an examination is non-quantitative, and the changes in chemical environment represented by the washing may have removed the slime coatings that existed during flotation. To provide the possibility for a correlation with electrical double layer phenomena, the experiments were made with quartz, corundum, and iron oxide, for which electrokinetic data are available.8-12 Since the properties of the electrical double layers of these oxides depend on the pH of the solution, pH will be the most important variable. Furthermore, because the zero point of charge for silica, iron oxide, and alumina occurs at pH 3.7, 8, and 9.5, respectively, the relative charge on the slime and mineral can be changed over wide ranges. Because of its practical importance in quartz flotation, iron oxide powder was chosen as the slime. Also, its uniform composition, contrasting color, and ease of analysis make experimentation simple.

Jan 7, 1958

By James Douglas

No one mill attribute it to the partiality of friendship if I claim for Thomas Sterry Hunt the right to a place among that little band of men whom nature has endowed with what seems an almost magical power of insight into her mysteries. But those of us who knew him well, while me never ceased to wonder at the breadth of his genius, the fertility of his imagination, and the wonderful capacity of his memory, learned that these native powers would have availed little to win him his rank in science, had they not been stimulated by ceaseless mental activity, indomitable perseverance, and unflagging industry. Thomas Sterry Hunt was born in Norwich, Connecticut, on September 5, 1826. He came on his mother&apos;s side from that good old stock which gave to Puritan England the gentle mystic Peter Sterry and that uncompromising preacher Thomas Sterry, who wrote the notable tract, " The Rot among the Bishops " in 1667, and that gave to New England Consider and John Sterry, the mathematicians. While lie was a child the family moved to Poughkeepsie on the Hudson. There the father died when Thomas, the oldest son, was twelve. The mother and her family of six young children returned to the old home in Connecticut. For a short time Thomas attended the public school; but it was for a short time only, as he, thus early, was required to share the burden of the family support and to seek employment. This he found first in a printing-office, then with an apothecary, afterwards in a book-store. The surroundings may have been congenial, but the occupation probably was not; for he re-

Jan 1, 1893

By F. W. Schroeder

AT the annual meeting of the Institute 2 years ago, a paper,1 " Requirements of Refractories for Open Hearths," was presented by F. W. Davis and G. A. Bole of the U. S. Bureau of Mines. In a brief foreword, D. A. Lyon stated that the paper was not to report the results obtained but rather to present an outline to serve as a basis for discussion. The essential parts of an open-hearth furnace were described and the conditions under which they operate. Some constructive discussion followed the reading of the paper. One of the first fellowship investigations undertaken by the Bureau of Mines in 1924 under the cooperative agreement with Carnegie Institute of Technology, through the Metallurgical Advisory Board, was to determine service conditions of open-hearth refractories. The present paper gives the results of this work which was done in the Pittsburgh district and was in charge of the authors. Material contributions in the form of data were contributed by E. N. Bauer, J. W. Campbell, G. H. Pfeiffer and A. Grodner, Carnegie Institute of Technology research fellows. The study covered 18 mos.

Jan 7, 1926

By J. J. K. Daemen, C. Fairhurst

Introduction The stress field around a supported tunnel can be considered as being composed of: i) the virgin (pre-mining) stress in the rock ii) the (elastic) change in this stress field caused by creating the opening iii) the (time-dependent ) change in the stress field produced by (i) and (ii) as a section of the rock breaks up iv) the (time-dependent) influence of the stress build-up in the support. Several authors have examined the conditions necessary to produce static equilibrium between the support, the rock, and the regional (in-situ) stress field. The analysis used by Labasse (1) is typical. Consider a circular tunnel radius R in a hydrostatic stress field (P), and a radial pressure pi exerted by the support. According to Labasse, the radius ‘b’ to which the rock will break* for a given support pressure, pi, can be calculated from: - the equilibrium equation: [ ] As a zone of broken rock develops around the opening, the stress circle for a point on the elastic-broken rock boundary moves to the right in the Mohr diagram until the radial stress in the broken zone s equal to the radial stress in the elastic zone.

Jan 1, 1971

By Robert Anderson

OLIVER C. RALSTON, Salt Lake City, Utah- (communication to the Secretary *).-The literature on the theory of flotation has been enriched, of late, by the views of a number of excellent mining engineers who unfortunately were tyros in physical chemistry and physics. Hence the obscurity and mystery with which the process is supposed to be surrounded. The present paper goes far toward explaining some of the ideas which have seemed obscure or which have been poorly expounded by the men who advanced them, but there are a number of places where the author&apos;s explanations are unsatisfactory, or where he has fallen into the same mistakes made by the original propounders of the theories involved. While recognizing the value of constructive compilation, it is nevertheless disappointing to find a paper reviewing the recent theories of flotation which presents nothing-new-not even a new viewpoint. At the bottom of page 1121, there are stated to be present the following "phases" in flotation: "solid-liquid (ore-water), solid-liquid (ore-oil), solid-gas (ore-air)," etc. The writer could not possibly have meant to apply the word "phases" to the ideas involved. Each of the pairs of phases mentioned has an interface in which exists the interfacial tension that he is talking about.

Jan 12, 1916

By U. Andres

U. Andres (The Technion, Haifa, Israel)-The authors are to be congratulated on their research, new and interesting, in a field which, however, the present writer and his assistants have been trying since 1962 to bring to the attention of the scientific and technical world, by means of publications covering several different aspects of this many-sided problem. We announced, in these publications, the results of magneto-hydrostatic (MHD) separation of magnetic and nonmagnetic minerals which we made in magnetic fluids (in paramagnetic solutions and suspensions of magnetic particles) which interact with permanent" and impermanent" inhomogeneous magnetic fields. There is no doubt that the authors have succeeded in creating ferrimagnetic colloids made by dispergation of 10-30 wt % of magnetite in kerosene in the presence of 7-10 vl % oleic acid. It may be judged by [Figs. 3 and 4] that the suspensions represent great stability systems and also "hysteresisless" fluids [(Fig. 5)] which bear witness to the existence of superparamagnetic suspensions. If the viscosity of these colloids is not so high, and the cost of preparing them can be covered, the fluids which have here been received can possibly be of interest to the technology of mineral separation. The potential possibility and technological perspective of similar media is demonstrated in our joint work with G. Bunin18 in 1965. The research carried out on the pushing out of cylinders and spheres from magnetic fluid is impressive; it would, however, have been interesting if the authors had compared their results with those on the pushing out of bodies from magnetic fluids adduced from our work." In my books" there happens to be described an experiment on the pushing out of a sphere in magnetic wedge field, in which the pushing out force of suspension with 5 vl % of magnetite reached 125 g per cc. This testifies to interesting possibilities of these media. Our works&apos; shows also, on the basis of Laplace&apos;s equation the receiving of an interesting distribution of pushing out forces by selection of corresponding configurations of magnetic poles. Objection must be made to the authors&apos; introduction of the term "antigravity force." The direction of this force does not depend on the direction of the gravity force and their opposition, i.e., antigravity is only one particular case. I am in full agreement with the authors&apos; statement that magnetic pushing out forces "can be utilized to separate nonmagnetic objects according to variations in their densities." It is, however, necessary to make only one important addition, which can be found in our research on MHS at the Technion in Haifa, namely, that magnetic fluids in magnetic fields can be utilized in the separation of minerals according to variations in their magnetic susceptibility. The authors&apos; conclusion is especially important considering the fact that in our publications" (including one in English") some designs of MHS separators and some technological results received on MHS-separators have already been described. S. E. Khalafalla and G. W. Reimers (Authors&apos; Reply)We were aware (mostly through Chemical Abstracts of the American Chemical Society) of the use of solutions of paramagnetic salts such as manganous sulfate in agnetohydrodynamic separations by the Russian school headed by G. Bunin."n Professor Andres&apos; contributions to this school are also evident in his application of the ponderomotive forces in an electrolyte placed in electric and magnetic cross-fields to separate coal and other useful minerals." It must be realized, however, that the foregoing research by Bunin et al." involved the use of magnetic fields and field gradients of very large magnitudes, i.e., such that H • grad H - 101 Oe2 per cm. The magnetization of paramagnetic salt solutions range from 0.1 to 0.5 gauss (at fields of a few thousand Oersteds) and never reach saturation. The magnetization of our superparamagnetic ferrofluids ranges from 100 to 500 gauss and reach saturation at fields of a few hundred Oersteds. Hence, to effect the same separation, the quantity "H

Jan 1, 1974

By A. M. Rowe

A considerable quantity of experimental hydrocarbon K-factor data has been correlated as a function of component identity, temperature, pressure and convergence pressure. To utilize these correlations effectively, convergence pressure must be determined accurately, particularly for volatile mixtures near their critical states. This paper presents phase diagrams that illustrate physically the meaning of convergence pressure. A new method, referred to hereafter as the "critical composition method", will be outlined for calculating convergence pressure. An example calculation has been included to illustrate how to use this new technique. INTRODUCTION The principle of hydrocarbon phase composition calculations as applied to such diverse problems as optimizing separator performance or predicting fluid compositions at various stages of reservoir depletion is the same. Usually, temperature, pressure and the numbers of moles of the various components of the fluid contained in a given volume are known. Questions answered by the phase calculation are what fraction of the total mass of fluid exists in each of the equilibrium phases, and what are the mole fractions of the various components in the two phases? To answer these questions the Natural Gasoline Supplymen&apos;s Assoc. (NGSMA) has correlated a considerable quantity of K-factor data as a function of temperature, pressure, component identity and convergence pressure.l To use these correlations to obtain the best answers possible, one must be able to calculate the convergence pressure. This is particularly true for over-all fluid compositions in the neighborhood of the critical state. STATEMENT OF THEORY Use of convergence pressure as a correlating parameter is based on a postulate similar to the law of corresponding states used in correlating PVT data of hydrocarbon gases. This postulate, which proposes convergence pressure as a correlating parameter, has been stated as follows: "The equilibrium vaporization constant for one component in a complex system is the same as the equilibrium constant at the same temperature and pressure for the same number or kind of components, providing only that the convergence pressures of the two systems are exactly the same at the same temperature and that the components are of the same homologous series".2 This law, as with all laws of physics, cannot be proven theoretically. It can only be justified by experimental data supporting its premises. Arguments have been made that this law violates Gibb&apos;s phase rule. For example, consider a four-component system. By Gibb&apos;s phase rule, which is thermodynamically rigorous, f = c — P + 2 =4, for a four-component, two-phase system. Thus, four independent intensive variables must be specified to establish completely all the intensive variables of the equilibrium phases. On the other hand, according to convergence pressure theory, only three variables need be specified for any mixture containing four different components. These variables are temperature, pressure and convergence pressure. Thus, the two laws appear to be in conflict. However, the convergence pressure postulate is more restrictive than Gibb&apos;s phase rule. It applies only to mixtures of the same homologous series. Hence, these two concepts are not in disagreement. PHASE DIAGRAMS DESCRIBING CONVERGENCE PRESSURE This paper presents phase diagrams grading from the simple two-component system to the more complex four-component system to illustrate convergence pressure. A less abstract definition of convergence pressure will be stated that is

By Albert Arents

This test is based upon the fact that metallic copper will precipitate gold and silver upoil its surface from acid solutions. Of course, the fact is not new, but its application is probably so. I have used the method with success; it recommends itself by the rapidity and ease with which it may be carried on. An auriferous cyanide solution, if made acid with sulphuric acid and boiled with finely divided, pulverulent, metallic copper, will, within a short time, deposit its gold-content on the copper. Any silver in the solution is also precipitated. If this mixture is now filtered, the filter and contents may at once be subjected to a crucible assay treatment, and its lead buttons cupelled and determined. If, instead of taking cement-copper, or any metallic copperpowder, a solution of bluestone is used after acidification, and a few small pieces of sheet aluminum are added, and the solution boiled until all the copper has come down, the result as to the precipitation of gold and silver is the same. This modification takes more time and attention in boiling. If aluminum has been used, it should go into the crucible with the filter and

Jan 1, 1904

By K. C. Heald

THE places where, yesterday, oil was unknown contain tomorrow&apos;s fields. Unquestionably, some states that now yield little or no oil have great potentialities, and developments in these states, although perhaps of less immediate interest than those in regions where great pools now exist, may easily be of greater ultimate importance than the results of exploration closer to known fields. Not long ago, Montana had only a quarter of an oil pool, and that was regarded by many as an accident that had strayed from Wyoming. More recently, the northern line of Louisiana was a dead line that would not be crossed by any Louisiana operator who valued his reputation for sanity. Within the past few months, Colorado has shown that it is far from being a negligible factor in the oil supply of the Rocky Mountain states, and it is now known that western Kansas, long shunned by many reputable geologists and operators, should be reckoned with. There may be a vast difference between what a wildcat well yields and what the well signifies. The fact that no commercial production is encountered may be lamentable and may well be disastrous to an individual or a company, but the same well that spells ruin to one may convey to another the information that will result in opening a new field. In presenting the conclusions, in this paper, the writer recognizes fully the possibility of erroneous deductions, particularly since he has had contact with only a few of the wells that are mentioned. Information comes principally from the scout. maps and files maintained at the Geological Survey by M. E. Latimer and G. K. Drach, without whose cooperation this summary would not be possible, supplemented by some personal contact and second-hand information gained by. conversation and correspondence. However, it is felt that the data contain few errors, and that the conclusions are at least reasonable.

Jan 3, 1924

By A. R. Denison

To those who are unfamiliar with the nomenclature in common use among operators in the Mid-Continent, the Permian Basin is a term to cover several widely separated productive areas. It includes what is designated in trade journals as the Panhandle fields, the West Texas fields and Southeastern New Mexico fields. It is bounded roughly on the east by the 100th parallel, on the west by the 104th parallel, 011 thr south by the Rio Grande River and various mountain ranges and on the north by the north line of the Texas Panhandle. The name is derived from the location of these three widely scattered areas which are all in a broad geosyncline which is chiefly filled with sediments of Perrliian age. The oil fields as now known and the approximate limits of the Permian Basin are shown in Fig. 1. The major part of the production in these areas comes from liniestonc or dolomite of Permian age. Some granite wash and sandstone production has been developed but ordinarily does not yield as large initial production as the limestone or dolorliite. Introduction During 1926, Texas, exclusive of the Gulf Coast, produced 12G1SS-1,-952 bbl. of oil,&apos; of which 40,727,877 bbl., or 32 per cent., was produccd in the West Texas Permian Basin. During 1927 the same area in Texas produced 167,176,000 bbl. %f oil, of which 89,779,000 bbL13 or 52 per cent., was produced in the West Texas Permian Basin. The increase in the total production of Texas is about equivalent to the increase in production in the Permian Basin. Since production in the Panliandle District declined during the entire year, the increase of production in the West Texas Permian Basin, and also the increase in Texas, is due to the enormous increase from the West Texas fields. Daily average pl-oduction in the West Texas fields increased from 68,211 bbl. on ,Jan. 8 to

Jan 1, 1928