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By S. R. Seagle, R. Schuhmann, N. A. Parlee

Rates of CO evolution and CO absorption were measured for liquid-iron alloys containing from 0.15 to 4.4 pet C, using a modified Sieverts apparatus. The alloys were held in alumina crucibles, so that both crucible-metal and gas-metal reactions occurred simultaneously. The data are interpreted on the hypothesis that the C-O reaction rate is controlled by oxygen diffusion across the boundary layers at the gas-metal and crucible-metal surfaces. CARBON-monoxide evolution from liquid Fe-C-0 alloys is a key reaction in steelmaking processes, both in the steelmaking furnace and in the ingot mold. Also, this reaction probably is an essential step in the desulfurization of iron under blast-furnace conditions, for which carbon is the principal reducing agent or deoxidizer present in the iron. The thermodynamic properties of the solutions of C and 0 in Fe and the equilibria of these solutions with gaseous CO and CO, have been investigated in some detail and are reasonably well understood. However, while these equilibrium data have accumulated in the laboratory, other data have accumulated to show that equilibrium conditions are often not achieved under plant operating conditions. Thus, an understanding of the rate and mechanism of the carbon-oxygen reaction not only has theoretical interest, but ultimately may assume considerable practical importance. Reaction Mechanisms and Rate Equations The over-all reaction under consideration is C (in liquid Fe) + 0 (in liquid Fe) + CO (gas) [I] Although this appears to be a straightforward heterogeneous reaction, involving just two phases (liquid metal and gas), a wide variety of reaction mechanisms has been proposed. Different authors have expressed divergent views as to the nature of the rate-controlling steps. Accordingly, a brief discussion of the possible reaction steps will be given. 1) Homogeneous Reaction Within Liquid Iron— Feild' and Jette2 have applied chemical reaction-rate theory as if the C-0 reaction were a homogeneous, second-order reaction occurring within the liquid-metal phase. This mechanism necessarily produces CO "molecules" dissolved in liquid iron. In order to yield CO gas, the dissolved CO must nucleate CO gas bubbles, and the dissolved CO also must be transported to the bubble surface where it enters the gas phase. However, this mechanism is inconsistent with present concepts of the structure of liquid-metal solutions. 2) Reaction at Gas-Metal Interface—At the surface of contact between gas and metal, a second-order reaction between dissolved C and 0 may occur to produce a CO molecule which enters the gas phase. This reaction presumably involves an "activated complex" structure in the interface. Some such surface mechanism appears essential because the carbon and oxygen do not occur in the same species in the two phases and therefore must react in some way at the surface. At liquid-iron temperatures, calculations based on reaction-rate theory indicate that the surface reaction must proceed extremely rapidly and thus cannot be a rate-determining step in the C-O reaction under ordinary conditions.3 ccordingly when the over-all reaction is measurably slow, the surface reaction may be considered at equilibrium; that is Cc* Co* = m'Pco [2] in which Co* and Co* are the concentrations of carbon and oxygen (weight per unit volume of metal), respectively, in the liquid-metal phase at the interface, Poo* is partial pressure of CO in the gas phase at the surface (atmospheres), and m' is the mass-action constant for Reaction [I]. Since activities of C and 0 are not strictly proportional to concentrations, m' is not a true thermodynamic equilibrium constant but varies with carbon content.' 3) Mass Transport—If the reaction is to proceed at the gas-metal surface, as described above, dissolved carbon and oxygen in the liquid iron must come to the surface and gaseous carbon monoxide must move away from the surface. Details of the mass-transport mechanisms depend on the kind of system under consideration. For a stirred metal bath in contact with a CO gas phase, the transport of C and 0 to the surface can be described by 1 Do Mols CO evolved per sec = — 1/16— Do/do Agm (CO-Co*) = 1/12 Do/do Agm *(Co-Co*) [3] In this equation, Do and D, are the diffusion constants for oxygen and carbon in liquid iron, 6, and 6,. are the boundary-layer thicknesses, A,,,, is the

Jan 1, 1959

By G. W. Healy

Activities of oxides in the ternary FeO-MnO-SiO system are calculated from data on the binaries, using the Gibbs -Schuhmann method. These activity data are used, together with thermodynamic relations, to calculate the contents of oxygen, silicon, and manganese in liquid iron, and the composition of the corresponding oxide phases in equilibrium with it. Excellent agreement was found between calculated and experimental metal compositions, indicating that thermodynamic methods, such as those presented, can supply useful data on slag-metal equilibria, and are therefore capable of wider application. When molten steel containing oxygen is treated with a deoxidizer, the product of the reaction is composed of the oxides of the deoxidizing elements together with more or less iron oxide. This assemblage of oxides is presumably very close to equilibrium with the melt since it is formed directly from elements dissolved in it. Therefore, it is likely that metal analyses corresponding to a given oxide phase composition are calculable with considerable precision where sufficient information is available on activities in both phases. The present study was made to test this hypothesis in the case of deoxidation by silicon and manganese. Here experimental data on the relationship among oxygen, silicon, and manganese in the metal phase are available, as are activity data for the MnO-SiO2, FeO-SiO2, and FeO-MnO binary systems. A further objective was to demonstrate in a specific example how gaps in the data may be filled by judicious interpolation, and how the Gibbs-Schuhmann method is applied to obtain activities in ternary systems. The rigorous derivation of the latter, requiring considerable facility in handling partial differential equations, tends to mask the real simplicity of the method, and repel the very engineers and experimenters who would benefit the most from its use. I) GENERAL PROCEDURE Deoxidation of steel with silicon and manganese results in the formation of two phases, metal and oxide. The number of components is four—Fe, Mn, Si, and 0. The phase rule then gives the number of degrees of freedom: If temperature and pressure are fixed, 2 deg of freedom remain. Consequently, it suffices to fix the concentration of two of the components of the system for all the concentrations to be determined and, at least in principle, calculable. The practical problem is then to discover a straightforward method of calculation with a minimum of trial and error solutions. The type of reactions to be dealt with are like the following: Si (in steel) + 2 O(in steel) = SiO2(in oxide phase) The standard free energy of this reaction is readily obtained from the literature, so that the equilibrium constant can be calculated by the expression: Since the metallurgist is concerned with percentages rather than activities, a real solution requires information that will permit activities to be converted to concentrations. This information is fairly adequate for the elements dissolved in molten steel, but is not available for the FeO-MnO-SiO2 oxide system. Therefore, the first step in this study was to find the relation between activity and concentration for the three oxides making up the system. The next step was the calculation of slag and metal compositions that are in equilibrium with one another. As shown by the phase rule, it is sufficient to assume the values of two composition variables in order to calculate the rest. But which two are picked makes a vast difference in how difficult the calculation turns out to be, so that it is necessary to make preliminary trial of several routes to find the easiest one. A convenient method is to begin with the slag, and to pick FeO concentration and that of one of the other oxides. Starting with the relation between oxygen dissolved in the liquid steel and FeO in the slag permits a good first estimate to be made of the oxygen content of the steel in equilibrium with FeO, because the iron content being fairly close to 100 pct, Fe has an activity close to unity. Using this first estimate of oxygen activity, approximate values of the manganese and silicon contents of the melt are readily calculated from the appropriate equilibrium constants. A minor correction for the depar-

Jan 1, 1963

By George E. Thackray

In December, 1894, the Cambria Iron Company made a number of heats of Bessemer steel to be used in structures by one of its customers, subject to inspection and tests by a firm of consulting engineers, one of the requirements being that the material should riot exceed .08 per cent. of phosphorus. In other respects the requirements were such that they could only be met by material of good quality; but the general spe cification is not introduced here, as it is not the purpose of this paper to deal with anything except certain difficulties encoun tered in determining the phosphorus-content of the material in a manner satisfactory to both seller and buyer. Preliminary determinations of phosphorus were made in sample-ingots from each of the heats from which material was rolled for the order in question, and these preliminary chemical tests, made in the laboratory of the Cambria Iron Company, showed that, with very few exceptions, every heat was within the prescribed limit of phosphorus. After the material had been rolled, sample-drilling8 of finished material were taken from the various heats in the regular manner in use at the works, these samples being thoroughly mixed and divided into two parts, one of which was analyzed at the works' laboratory and the other sent to the inspecting engineer. Several hundred determinations were made from this mate rial without reaching an agreement between the work of the inspector's chemist and that of the works' chemist; but as it is not the object of this memorandum to treat of this part of the subject at length, it is considered sufficient to present herewith only a few of these first determinations. The analyses given in Table I. are those of the original series made on the heats which were afterwards resampled for final determination by an arbitrator; and they are selected for this reason, as the entire " comparison is thus rendered more complete.

Jan 1, 1896

By A. S. Bower

Any process which has for its object the preservation of iron and steel from rust, and which will make these metals more applicable than they now are to the requirements of mankind, will be sure to meet with attention from members of this association, and from all those who are either engaged in the extraction of the ore, its reduction to metal, or the subsequent application of the metal itself. It is, perhaps, not too much to say that when iron and steel are rendered secure against corrosion and decay, they will be used to an indefinitely greater extent than they now are. The whole realm of science has, therefore, been explored in the attempt to discover some method by which the formed article may be preserved, leaving its strength undiminished by the destructive action of rust. Paints, oils, varnishes, glazes, enamels, galvanizing, electro-depositing and what is called "inoxidizing" are among the many systems now in vogue to effect the preservation of iron and steel from the corrosive action of air and water. The object of this paper is to show what may he done in protecting iron and steel from rust by forming upon their surfaces a film of magnetic oxide by an inexpensive process. It is no new thing to be told that magnetic oxide of iron is unaffected by exposure to the atmosphere or to salt water for any length of time. The black sand of Taranaki, in New Zealand, is a sufficiently good example of this. Dr. Percy has pointed out that the reason why Russian sheet iron is less affected by exposure than ordinary sheet iron is because of a coating of magnetic oxide; but this was not known

Jan 1, 1883

By John C. Draper

The principal object of an underground coal mine transportation system is to move coal from the face where it is produced to the outside of the mine where it is prepared for market. In addition to the movement of coal, a transportation system must also move supply materials to the inside ; it must move men in and out of the mine ; and it must move rock and other debris out of the mine for disposal. Usually, mine haulage is divided into three categories named for the various areas of the mine served : 1) Pace Haulage. This is used at face from the mining machine to the intermediate transport system. 2) Intermediate or Secondary Haulage. Generally this is used between face haulage and main haulage. Sometimes this is merely an extension of the main haulage. 3) Main Haulage. This extends from the secondary haulage to the outside and is usually either a track or conveyor system, sometimes a combination of both. Transportation modes of coal in the various areas pose different problems, but the whole system must be synchronized. For instance, at the face the coal should be removed quickly from the various places to facilitate the movement of machines, whereas the intermediate system just passes the same coal on to the main transportation system. Selection of the transportation system must be based on the seam height, mining methods used to extract the coal, capacity required, ease of coal handling, and haulage efficiency. When driving rooms, mine cars can be used. They often simplify supply haulage and rock handling because they can also handle these items. Conveyors could be used and would have a greater haulage capacity but they cannot handle supplies easily or segregate the rock. When using a different mining method, such as longwall, mine cars cannot be used because there is not sufficient space to move the cars at the face nor can the cars haul the coal without delays which would cause excessive losses in production. As for ease of handling

Jan 1, 1981

By Mary Barrett, Walter Rose

INTRODUCTION The conventional way to program reservoir problems* for solution on the electric analyzer1 is one which concentrates the block units towards the inner radius of the prototype system being represented by the analog model. This is achieved by the device of considering block units of equal value radial resistance, leading to the consequences: (1) the ratio of the external to the internal radius of each block unit is a constant (i.e. r1/ri-l = constant a); (2) the external radius of the nth block unit is equal to the innermost radius of the system times the constant a raised to the nth power: (3) the capacitance of the block units increase by a factor of a2 going out radially from the innermost to the outermost boundaries of the system; (4) given n block units in the radial direction, the capacitance ratio of the outermost to the innermost block unit is a (2n-2); and (5) the vertical resistance of the block units decrease by a factor of a going out radially from the innermost to the outermost boundaries of the system, such that the ratio of the maximum to minimum vertical resistance is also given by the factor a(2n-2) PRESENT PROGRAMMING METHOD While this conventional way of programming problems is quite adequate for routine uses of the electric analyzer, it leads to difficulties in those cases where the inner radius of the prototype system (e.g., the well-bore) is small compared to the external radius (e.g.. the external reservoir boundary). To handle such a case by the conventional method would require either that a large value be selected for the constant a or that a large number n, of radial block units be chosen. In consequence, the capacitance and vertical resistance ratios become impossibly large, as will be evident from the relations given above. In any event, the size of the smallest and largest capacitors will always be limited by the size of commercially available components, and the analyzer itself will determine how many mesh points are available for radial block units. For example, it can be shown that if the maximum capacitance ratio which can be electrically handled is a factor of l04, the maximum external radius of the system which can be considered (assuming an internal wellbore radius of 0.25 ft is: It is thus seen that in direct consequence of having the inner wellbore radius small compared to the external radius, models extending beyond 30 to 40 ft are not possible when the capacitance ratio is limited to l04. (NB. A value of 10-9 farads can perhaps be taken as the minimum electrical capacitance possible if corrections for the capacitance of the lead wires are to be avoided. Values greater than 10-5 farads would require the use of unstable and inaccurate electrolytic capacitors). On the other hand, models extending out to 500 to 5,000 ft may be desired in single-well problems, and hence the need for a revised method of problem programming. * REVISED PROGRAMMING METHOD The revised method of programming is one which attempts to retain the desirable features of the conventional method (viz. concentration of block units towards the inner boundary, simplicity in computation, etc.) without having as a consequence that impossible capacitance and vertical resistance ratios will be required. Other advantages will also be achieved by the revised

Jan 1, 1957

By Edmund C. Pechin

THE writer approaches this subject with a great deal of diffidence —first, because it is utterly impossible to treat it satisfactorily within the limits of a paper, and, secondly, because the larger development is of so comparatively a recent date as to make authoritative data on some interesting points unavailable. For over one hundred years small charcoal-fnrnaces have been in existence, at widely scattered points, making a few tons of iron daily, and then gradually increasing to a daily output of, say 10 to 12 tons, as the market widened. With the exhaustion of local supplies of wood, inaccessibility to market, and sharp competition, bringing lower prices, many were compelled from time to time to make temporary stops, and finally to cease altogether. During the first half of the century there were at different times in operation between 75 and 90 charcoal furnaces. The last Directory of the Iron and Steel Works of the United States (1890) gives 19 as the number of charcoal-stacks in Virginia. Of these several are cold, and, it is

Jan 1, 1891

The Ortiz Mountain property is located approximately 40 km (25 miles) southeast of Santa Fe and 13 km (8 miles) from the village of Cerrillos. The property embodies a Spanish mineral grant from which Gold Fields acquired about 2, 200 hectares (900 acres of surface and mineral rights. Following a period of exploration, metallurgical testing and development of a feasibility study in 1974, the decision was made, because of the higher gold price in the fall of 1978, to place the property into production. the gold is confined in a quartzite breccia; it is an unusual occurrence because the gold in this host rock is leachable at minus 19 mm (3/4 in. ). Total ore reserves are estimated at approximately 3.6 million mt (4 million st) averaging 1.89 g per mt (0.055 oz per st) based on a cut-off of 0.7 g (0.02 oz). The ore will be recovered by open pit mining at a stripping ratio of 1. 2:l. Production is scheduled for 13,600 mt (15,000 st) of ore per week or approximately 680,000 mt (750,000 st) per year. Primary crushing of pit-run material is by a 1,070 by 1,015 mm (42 in. by 40 in.) jaw crusher. Crushed ore is conveyed to stockpile and then to a 2.13 m (7 ft) standard crusher with the screened over- size crushed in a 1.5 m (5 ft) tertiary cone crusher. The screen undersize, the final product for leaching, is minus 19 mm (3/4 in. ). A 1, 360 kg (3,000 lb) sample is cut from the crushed ore stream, further crushed in a small jaw crusher and then sampled in two more stages by Vezin samplers to produce a final 13.6 kg (30 lb) sample for assaying. Pebble lime is then added to the ore on the belt as it is sent to the conveyor gantry spanning the leach pads. A tripper on this moving gantry stacks the leach ore without compaction. The entire crushing plant and conveying system is of open-air construction. Leach pads have a total length of 515 m by 60 m (1,700 ft by 200 ft) wide with usable dimensions of 490 m by 58 m (1,600 ft by 190 ft). The directional length slope is 3. 870 with 370 on the width. The pad is constructed of 175 mm (7 in. ) thick asphalt containing a rubberized asphalt membrane. It is divided by a 300 mm (1 ft) high curb into eight segments. Each segment is loaded with 13,600 mt (15,000 st) of ore, which is one week's production. Optimum working height of a pad is considered to be 3. 0 m (10 ft) with a maximum height of 4. 0 m (14 ft).

Jan 1, 1981

By T. Lane Carter

It is a curious fact that while in our Transactions there are papers dealing with mining-districts in all parts of the world, in Europe, Asia, Africa, and Australia, there is not one which describes the mining possibilities of Nicaragua, our near neighbor. To be most interested in distant objects, like the moon, and to neglect what lies at our feet, appears to be a trait of human nature. The neglect of Nicaragua is not confined to the American Institute of Mining Engineers. In no other transactions am I able to find papers dealing with mining in Nicaragua, some parts of which are as much in need of discovery and research as the North Pole. I hope this paper will be the precursor of many others to be printed in our Transaclions, dealing not only with the miniilg possibilities of Nicaragua, but with the whole of Central America, where there are vast areas a,waiting skill and capital for their development. Much of this capital and skill should come from the United States in the future, although it is probable that European capitalists, when they appreciate fully the possibilities, will investigate more and more the mining-resources of Nicaragua and ot'her Central American republics. Fig. 1 is a sketch-map of Nicaragua showing the principal mining-districts. 11. History. Mining in Nicaragua did not begin yesterday. It was commenced by civilized man when the Spanish conquerors pene-' trated into the interior and forced the natives to procure the precious metal for them. It is strange that the Spaniards did not find more gold, and work on a scale as extensive as in Colombia and other parts of South America. Probably in Nicaragua the Indians covered up most of the rich prospects

Jan 1, 1911

By H. N. Eavenson

Prior to 1907 nearly all coke was made in beehive ovens, and most of the gas produced was made in the old-style gas retorts, and while there were a few coke plants in southern West Virginia, southwest Virginia and Kentucky operating on high-volatile coals the proportion of the total product made by them was small and usually was used locally. The greater part of the coke made, and the coal gas produced, came from the Pittsburgh seam of western Pennsylvania and northern West Virginia, which was then regarded as the standard coking and gas coal of the country, and the best coal available anywhere for these purposes. With the advent of the byproduct oven and the building of coke plants at the furnaces, the restriction of the use of one grade of coal for making coke was removed and the use of mixtures of low-volatile and high-volatile coals began. The change in the locations of the coke plants removed the necessity of using Connellsville coal and also made sources of gas available to the public utilities other than of their own manufacture. Most of the first oven plants were built at points distant from the Connellsville region and this afforded an opportunity for the use of coals from the southern Appalachian fields, which were then at approximately equal distances from the ovens. Since that time development has been made on a number of seams of coal of great purity in southern West Virginia, southwestern Virginia and eastern Kentucky, which have been largely used for gas, cokemaking and metallurgical purposes where low amounts of ash, sulfur and phosphorus are determining factors. These coals are much lower in the objectionable elements than most of the coal shipped from the Pittsburgh seam, or than any northern coal, and when blended with low-volntile cod produce coke in byproduct ovens that is not excelled for any purpose by any coal mined in this country, and is equaled very seldom. Coal from several of these scams is shipped in great quantities without beneficlation and is lower in ash and sulfur than any but the best washed product from the Pittsburgh seam in the north. The writer has made a study of these coals to ascertain their relative qualities and the areas and reserves of coal available in each of them. No attention has been paid to the coals of Alabama, which do not compete with any of these coals, and no coal of equivalent quality is found in

Jan 1, 1934

By M. G. Nicholas

The influence of deformation, relative movement and surface cleanliness on the strength of room -temperature "interparticle" bonds between copper surfaces has been studied. No bonding resulted when clean surfaces were merely pressed together, even under pressures of 50,000 psi. Bonding resulted, however, when clean surfaces were simultaneously pressed and moved relative to each other, some bonding occurring no matter how small the pressure or relative movement. Exposure of the clean surfaces to various chemicals inhibited bonding, none at all being produced by small relative movements. The size of the movements which first produce bonding between exposed surfaces depends on the nature of the chemical, being less than 0.002 in. for cleansing reagents and greater than 0.004 in. for lubricants, water and hydrogen sulfide. It is concluded from the experimental data that the prime requirement for bonding is the dispersal of surface films such as oxides and adsorbed contaminants. THE formation of interparticle bonds during the room-temperature compaction of powder metallurgy components greatly increases the ease of handling in subsequent production operations prior to sintering. The strength of unsintered compacts follows the same general trends as their density and hardness, but quantitative data are extremely Scarce. Quantitative correlation of the data on the overall strength of a compact with that of the individual interparticle bonds is virtually impossible due to the extremely complex geometry of powder compacts. Qualitatively, however, the strengths of unsintered compacts can be correlated with variations in parameters known to influence the extent of cold bonding, and hence interparticle bonding, such as surface cleanliness, relative movement, and deformation of the mating surfaces. Kuzmic and seelig4 found that contamination of powder particle surfaces with lubricants reduced the strength of unsintered iron and copper compacts. Interparticle shear has been shown to promote bonding by Train and Hersey7 while Gregory has shown that die rotation is beneficial. Eilender and schwalbe6 concluded that most bonding occurred during the early stages of pressing iron powder compacts when interparticle shear is one of the principal processes occurring. mile there can be little doubt that these and other factors, such as particle size and shape, affect the extent of interparticle bonding produced by compaction, evaluation of the influence of individual factors is not easy. Particle deformation and relative movement, for example, occur simultaneously during compaction, making any precise measurement of their relative influences difficult. Because of these and other difficulties encountered in studying interparticle bonding in actual powder compacts, the approach adopted in this study was to

Jan 1, 1963

By W. L. Fink, R. S. Archer

This paper describes results obtained on aluminum-beryllium alloys and aluminum-beryllium-copper alloys in the preparation of which aluminum of 99.95 per cent. purity was used. The constitution and structure of the high purity binary alloys are given. The aluminum-beryllium eutectic occurs at 0.87 per cent. beryllium and 645° C. The solid solubility of beryllium in aluminum at 631° C. is 0.05 per cent, beryllium, and at room temperature is less than 0.013 per cent. beryllium. The densities of the alloys are substantially the same as the values calculated on the assumption that the densities of the elements are not changed by alloying. All of the alloys age-harden at room temperature after a solution heat treatment, and the chill cast aluminum-beryllium-copper alloys age-harden at room temperature without a prior solution heat treatment. Hardness and tensile properties are given. Salt spray corrosion tests on sheet specimens are described. It is shown that beryllium docs not lower the corrosion resistance of aluminum to salt spray provided the alloy has received a solution heat treatment. Commercial Possibilities of Beryllium Alloys Beryllium has certain properties such as low density, high hardness, good corrosion resistance, low thermal expansion and fairly good electrical conductivity, which would indicate that it is worthy of consideration as an ingredient of light alloys. It was not until recently, however, that beryllium could be produced with sufficient ease to encourage research along this line. The production of beryllium by electrolysis from a fluoride bath has now developed to the stage where it could be used commercially if there were sufficient demand for the element. Claims made in certain newspapers and technical articles in regard to thc strength and corrosion resistance of thc aluminum-beryllium alloys are not justified by experimental results. Moreover, beryllium is an expensive metal ($200 a pound at the time this work was done) and, on account of the nature of its ore and the consequent difficulty of its extraction, it will in all probability continue to be a relatively expensive metal, although the cost would undoubtedly be a great deal less than $200 a

By C. H. Cheng, C. E. Birchenall

The fundamental problem in the thermodynamics of solid solutions is the determinatiorl or calculation of the activities of the components as a function of temperature and composition. Since the theory of metals is not suficiently developed to allow a priori calculation of these quantities, they must be obtained from experiment. C. Wagner1 has reviewed the literature of this subject for the period before 1940. Although several important and extensive studies have been made in the meantime, the number of systems to which any sort of quantitative information can be assigned is vanish-ingly small. These data have become of great potential importance in studies of the structure of solid solutions2 and intermetallic compounds, the nature of the diffusion process,3,4 and perhaps even the mechanism of mechanical deformation.5 For these reasons, it. seems very worthwhile to extend the experimental data in this field. Although there is little use in duplicating Wagner's review, attention should be directed to the most recently reported investigations. A brief enumeration of the methods of measurement previously employed also should be valuable. The most direct method is the determination of the partial pressure of the components in the vapor phase in equilibrium with the solution. Both equilibrium and kinetic methods have been tried in metal systems, but almost exclusively on liquid phases. Only in the ease of carbon in iron alloys and in the copper-zinc system have extensive measure- ments been made which include solid phases. When one of the components is an element, such as nitrogen or carbon, which forms compounds which are very volatile and stable at normal temperatures and pressures (CH4, Co2, CO NH3), it is frequently possible to equilibrate mixtures containing these (such as CH4-H2, CO2-CO, NH3-H2) independently with the elernents (C, X) and with the metal (Fe, Ni, etc.). Such measurernents have been made for carbon in iron, iron-silicon, and iron-manganese alloys by Smith6 and in iron and iron-nickel alloys by Toensing.7 Differences between carbon activity values at the same temperature and carbon content when carboil is introduced from CH4-H2 rnixtures or CO-CO. mixtures indicate that the effects of hydrogen and oxygen in the system are not negligible, and one can only hope that the true value lies somewhere between these sets of results, probably nearer the CH4-H2 data since hydrogen is less soluble in iron than oxygen. This is essentially an equilibrium method, although flowing gas is employed. A kirletic method has been employed which consists of sweeping an inert gas (generally hydrogen) over the alloy at a series of rates, condensing the metal vapor out,, and analyzing it. The metal content can be extrapolated to zero flow rate (equilibrium). Wejnarth's8 work on Cd-Mg and Zn-Mg is a good example of this frequently used method. A variant of this consists of equilibrating a known volume of inert gas with the alloy, sweeping it out quickly, and analyzing for metal. In common with the above method, it has the disadvantage that the "inert" gas is generally somewhat soluble in the alloy. Moreover, the former continuously displaces the system from equilihrium and may give low values if solid diffusion is involved. The dew point method applied by Hargreaves9 to the alpha and beta brasses and by Schneider and Stolll0 to A1-Zn avoids the introduction of another component to the system, but is useful only in systems in which one component is much more volatile than the other. The alloy sealed in one end of an evacuated silica tube is heated to the desired temperature. The temperature of the other end is lowered until droplets of the volatile component condense. When the temperature is raised slightly, the droplets will evaporate. By careful adjustment of temperature, the range between evaporation and condensation can be narrowed appreciably. An independent determination of the vapor pressure of the . pure volatile component is necessary to give the partial pressure over the alloy. This is the method employed here to determine the vapor pressures of zinc and cadmium over their silver alloys up to 34 pct in cadmium and 76 pct in zinc. The former involves only the a solid solution, but the latter covers the a, ß, y, and e fields. In recent determinations, Herbenar, Siebert, and Duffenbarkl1 used the

Jan 1, 1950

By F. R. Brotzen, L. D. Whitmire

Single crystals of high-purity molybdenum were de-formed at temperatures from 195°to 473°K, and the effect of deformation on the electrical resistivily was deler-mined. To separale the resislivity components of point and line defecls some cryslals were annealed at 473°K. The vale of resislivily increase wilh strain was nearly linear and was strongly dependent upon the deformation temperature. Point dejects are annealed out without any effect on the flow stress. At low temperatures the flow stress is a linear function of the square root of the resistivity increase attributable to dislocations. ELECTRICAL-resistivity measurements have been used successfully to gain information on structural changes in metallic materials. During plastic deformation the electrical resistivity rises because of electron scattering from newly created lattice defects. Such measurements lend themselves, therefore, to corroborating results from direct observation of lattice defects and, to a certain extent, to correlating defect densities and distribution with mechanical properties. Published information on research with single crystals of the bcc metals of Group VI, particularly molybdenum, is still limited. Yet, molybdenum single crystals of relatively high purity can be readily prepared by electron-beam-melting techniques. Furthermore, some valuable information on the defect structure of deformed crystals by direct observation is available. Lawley and Gaigher,1 for example, have examined dislocation configurations in deformed molybdenum crystals by means of transmission electron microscopy. Their results revealed that the dislocation density and distribution were strongly dependent upon the deformation temperature. These findings differed from those by Keh and weissmann,2 who found that the average dislocation density in polycrystalline iron deformed between 138° and 298°K depended only on the degree of strain and not on the deformation temperature. Martin3 and peiffer4 showed that point defects introduced in polycrystalline molybdenum by cold work can be eliminated by annealing at a relatively low tempera-ture. In view of their work it became apparent that resistivity measurements of suitably annealed crystals could disclose changes in their dislocation structure and contribute to the understanding of the work hardening of molybdenum crystals. EXPERIMENTAL PROCEDURE Crystals were grown by electron-beam zone melting5,6 of 0.062-in.-diam molybdenum rods (99.99 pct) supplied by General Electric Lamp and Wire Division, Dover, Ohio. The crystals, about 4 in. long, were prepared by using five zone-refining passes at a speed of about 6 mm per min in a vacuum of about 5 X l0-6 Torr. The resistivity ratio of the crystal, p(4.Z°K)/p(273°K), was generally near 10-3. These crystals were used as tensile specimens of uniform diameter in the "as-grown" condition. They were oriented for maximum shear on the (011)[111] slip system (Schmid factor >0.49). The specimens were held in spherically seated Templin-type grips so as to minimize bending. Samples were deformed on an Instron machine at a strain rate of about 5 X 10-5 sec-1 in an isopentane bath with dry ice at 195°K, in ice water at 273°K, and in a vegetable-oil thermostat at 373° and 473°K. The temperature in the latter was maintained constant within +2°K. Resistance measurements were carried out with a Kelvin double bridge. The resistance of the potential leads was kept low by using large-diameter wires outside the low-temperature bath. Many of the resistance data were checked by measurements made with an ac bridge. Current and potential leads were spot-welded to the specimens. The distance between the potential leads, about 3 in., was also considered to be the gage length for the strain measurements. Diameter and gage length of the samples were measured optically with an error of less than 2 pct. These measurements were used also to insure that the deformation had been uniform over the gage length of the specimen. Resistivity changes were then determined from the resistance measurements at 4.2°K assuming constancy of volume. In the course of a test, the crystal diameter, gage length, and resistance at 4.2°K were determined first in the initial state and subsequently for various amounts of elongation.

Jan 1, 1968

By J. M. Bugbee

The engineer and the conservationist agree that effective water drive is the desirable reservoir production mechanism. Water drive may result either from the expansion of edge water, the reservoir water bordering an oil pool, or from the artesian flow of edge water from the outcrop. Thus, the extent of the reservoir has an important bearing upon both the rate and the ultimate quantity of water influx to an oil pool. Lens-type reservoirs are generally recognizable, but the complete structure of the more important domal types, having possible limitations from crestal and synclinal faulting, is not well understood. The delineation from cores, electrical logs and exploitation phenomena of the crestal portions of reservoirs is increasingly exact. This paper suggests that inference from these factual pictures, combined with the scattered well and geophysical data of the synclines and with consideration of the dynamics of structural formation, may be applied to solving the complete geologic structure. Since faulting on the domes and in the synclines may effectively seal and thus limit the size of a reservoir and bar additional water influx, consideration of geologic structure and its possible effects is essential to complete analysis and prediction of reservoir performance. Introduction Implicit in reservoir studies is the fact that the oil must be displaced from the reservoir rock by some other fluid, either gas or water, and this understanding yields the terms descriptive of the major reservoir production mechanisms, gas expansion and water drive' Three recent papers1-2-3 make clear the economic and conservation preeminence of Water drive as a production mechanism; in fact, the title of the latest of these is " Production under Effective Water Drive as a Standard for Conservation Practice." There appears to be an assumption at times among analysts that the effectiveness of a water drive is solely dependent on the rate of oil production; that is, if water drive appears to be insufficient or lacking, a lower oil-recovery rate would increase or reveal it. This assumption might result from the fact that the analysis has been wholly developed during the period of production curtailment; that is, since 1929. The writer takes it that the recurrent phrase in De Golyer's paper,3 "some degree of water drive," is related to this assumption. In California, an extraordinary phrase, "inactive water drive," is rather common and the connotation of uncertainty regarding our knowledge of reservoir performance is evident. Wyckoff2 speaks of the type of reservoir and performance as follows: "In general, reservoirs may be any one or a combination of domal, faulted, lenticular, or stratigraphic traps. Insofar as the dynamic performance of such reservoirs is concerned, the particular type merely determines whether regional flow is symmetrical as in a uniformly developed domal or lenticular type, or one-sided as in many stratigraphic or faulted traps." But whether the flow is

Jan 1, 1943

By J. M. Bugbee

The engineer and the conservationist agree that effective water drive is the desirable reservoir production mechanism. Water drive may result either from the expansion of edge water, the reservoir water bordering an oil pool, or from the artesian flow of edge water from the outcrop. Thus, the extent of the reservoir has an important bearing upon both the rate and the ultimate quantity of water influx to an oil pool. Lens-type reservoirs are generally recognizable, but the complete structure of the more important domal types, having possible limitations from crestal and synclinal faulting, is not well understood. The delineation from cores, electrical logs and exploitation phenomena of the crestal portions of reservoirs is increasingly exact. This paper suggests that inference from these factual pictures, combined with the scattered well and geophysical data of the synclines and with consideration of the dynamics of structural formation, may be applied to solving the complete geologic structure. Since faulting on the domes and in the synclines may effectively seal and thus limit the size of a reservoir and bar additional water influx, consideration of geologic structure and its possible effects is essential to complete analysis and prediction of reservoir performance. Introduction Implicit in reservoir studies is the fact that the oil must be displaced from the reservoir rock by some other fluid, either gas or water, and this understanding yields the terms descriptive of the major reservoir production mechanisms, gas expansion and water drive' Three recent papers1-2-3 make clear the economic and conservation preeminence of Water drive as a production mechanism; in fact, the title of the latest of these is " Production under Effective Water Drive as a Standard for Conservation Practice." There appears to be an assumption at times among analysts that the effectiveness of a water drive is solely dependent on the rate of oil production; that is, if water drive appears to be insufficient or lacking, a lower oil-recovery rate would increase or reveal it. This assumption might result from the fact that the analysis has been wholly developed during the period of production curtailment; that is, since 1929. The writer takes it that the recurrent phrase in De Golyer's paper,3 "some degree of water drive," is related to this assumption. In California, an extraordinary phrase, "inactive water drive," is rather common and the connotation of uncertainty regarding our knowledge of reservoir performance is evident. Wyckoff2 speaks of the type of reservoir and performance as follows: "In general, reservoirs may be any one or a combination of domal, faulted, lenticular, or stratigraphic traps. Insofar as the dynamic performance of such reservoirs is concerned, the particular type merely determines whether regional flow is symmetrical as in a uniformly developed domal or lenticular type, or one-sided as in many stratigraphic or faulted traps." But whether the flow is

Jan 1, 1943

By K. K. Clark, W. H. Somerton

The feasibility of reducing pressures needed to fracture formations by heating the borehole intensively has been investigated on a laboratory scale. Reductions in fracture pressures of heated Bandera, Berea and Boise sandstone cores were observed at various confining pressures, simulating reservoir stress conditions to a depth of 5,000 ft. Both permeable and impermeable borehole boundary conditions were tested. Three heating conditions were used in the tests. One group of samples was heated in a furnace to a temperature of 600C, cooled to room temperature., and then tested for fracture pressures. Two other groups of samples were heated with a borehole heater to maximum borehole wall temperatures of 625 and 792C, then cooled and tested. In all cases, heated samples showed substantial reductions in fracture pressures compared to unheated samples. The higher temperature borehole heated samples showed the greatest reduction, amounting to 70 per cent in the extreme case. In actual application to wells, it was concluded that fracture pressures may be reduced by 20 to 50 per cent by intensive borehole heating before fracturing. INTRODUCTION Hydraulic fracturing of oil and gas wells is an accepted and effective technique for increasing well productivity in many areas, but is notoriously unsuccessful in other areas. The technique becomes less interesting for production stimulation purposes when excessive fracture pressures are necessary. Formations which do fracture but require high pressures, probably form horizontal fractures. There is good evidence to indicate that some formations do not fracture at all, but yield plastically under high pressure. Thus, any technique which will make formations easier to fracture or will reduce fracture pressures is potentially interesting to petroleum producers. Horizontal fractures generally occur in planes of weakness, such as bedding planes, and at pressures equaling or exceeding the effective overburden stress. In the unusual case where planes of weakness do not exist, a slightly higher pressure must be applied to overcome the tensile strength of the rock. In general, high fluid-loss fracturing fluids are conducive to the formation of horizontal fractures.1 Vertical fractures, when they do occur, are initiated at pressures generally lower than overburden pressure and are favored by low fluid-loss fracturing fluids or impermeable boreholes. The pressure necessary to create a vertical fracture in an impermeable, elastic medium can be predicted from the so-called "thick-walled cylinder" equation: Pf = 2 or+ st.............(1) where pf = fracture pressure or = radial stress st = tensile strength of medium. This equation indicates that to fracture it is necessary to overcome a tangential compressive stress, induced by and equal to two times the radial confining stress, plus the tensile strength of the medium. If the above equation held strictly true for rocks, very little could be done to reduce fracture pressure. The tensile strength of the rock might be reduced somewhat, but any change in st would be small compared to the magnitude of the tangential stress at reasonable subsurface depths. Laboratory tests have shown that actual fracture pressures exceed values predicted from Eq. 1 by factors of 1.4 to 28.6.1,2 Eq. 1 thus does not properly describe the

Jan 1, 1966

By J. Ralph Finlay

In latitude 4" S., about fifty miles from the Pacific, and in the amphitheater on the west flank of the Andes, which is drained by the river Tumbez, is the ancient town and mining district of Zaruma. The town is picturesque in the extreme, perched on a ridge 1800 feet high, between two lovely mountain rivers, looking out upon neighboring hills and valleys clothed in rich green, relieved by many hamlets roofed in red tiles, and, at greater distances on all sides, upon mountain slopes of gloomy forest crowned by the bare summits of the Andes. General Description. The gold-mines, discovered in 1549, mere worked extensively by the Spaniards in the 16th and 17th centuries, until their success was curtailed by the exhaustion of the oxidized surfaceores, and the uncovering of the refractory and hard ores underneath. The industry slowly declined until it was nearly or quite at a standstill in 1878, when an unfortunate English company, organized by Chilian promoters, acquired some of the best properties and began to work them. This company, after an extravagant début, relapsed into a struggle against poverty and mismanagement, and finally collapsed in 1894. In 1896 the English mines and many others, covering most of the district, were acquired by the South American co., formerly the South American Development Co., of New York. (See Figs. 1 and 2.) The vein-formation of Zaruma is extensive and complex, and the ores are somewhat refractory. In the immediate neighborhood of the gold-bearing veins the formation seems to be altogether volcanic, consisting of rather fine-grained holocrystalline diorite; but a few miles away, on either side, some gueisses and crystalline schists are to be found. About four miles south of the mines, and beyond some intervening granites, appear

Jan 1, 1901

By Arthur F. Taggart

Some years ago, A. M. Gaudin and one of the authors published a paper showing removal of tar acids from solution by sulfides preferentially as compared to gangues (specifically by galena as compared to quartz).' The underlying phenomenon was classed as adsorption, and the paper went on to develop the general thesis that so far as water-soluble frothing and collecting agents in flotation are concerned, the phenomenon of adsorption is one of controlling importance. Adsorption was defined in that paper as "a process of rearrangement of a system, which results in establishing a difference in concentration, as between the interfacial layers and the bulk of the phases, of a substance or substances initially uniformly dispersed in one or several of the phases." The paper went on to develop the relation between adsorption and surface cnergy according to Gibbs' equation (which may be thrown into the form U/c = KdT/dc, where U = excess concentration in surface layer, c = concentration, T = surface tension, and K is a constant), and pointed out that, according to this equation, degree of adsorption and change in surface tension vary directly. The present paper offers a somewhat different definition for the term adsorption; and sets up, in sweeping terms, the generalization that simple chemical reaction underlies the functioning of the flotation reagents which control mineral collection, when these reagents are soluble in and act from solution in the water of the pulp. Adsorption According to the modified definition, adsorption means concentration at an interface between different phases in a heterogeneous system (thus far the definition runs as before), by the action of some mechanism, of which nothing is properly implied in the word, and concerning which the user of the word is probably in entire ignorance. Thus defined,

Jan 1, 1930

By V. Jares

DESPITE the fact that a combination of metals-aluminum-zinc-tin, and sometimes aluminium-zinc-cadmium-is extensively used for aluminum solders, as well as for die-castings, the constitution of these alloys has not yet been made clear. I. BINARY SYSTEMS The system aluminium-zinc is the basis of the ternary alloys under consideration. Their composition was made sufficiently clear by the investigations of Roscnhein and Archbutt,1 Bauer and Vogel,2 Sander .and Meissner,3 Hanson and Gayler4 and Isihara.5 Only the temperature of decomposition of the crystals s seems still to be doubtful, whether it is considered as a compound of Al2Zn3 (according to Bauer and Vogel) or as an intermediate phase of variant composition (according to Hanson and Gayler). This temperature is given by most of the authors, as in the neighborhood of 256° C., only Isihara giving 280° C. As its accurate determination is of special importance in the study of the ternary alloys under consideration it was experimentally controlled in the following manner: An alloy corresponding in composition to the formula Al2Zn3 was made, in which the temperature effect was found to be the greatest. This was drilled and a silver-constantan thermoelement inserted into the cavity so as to be in direct contact with the alloy. The whole was then very slowly heated and the heating and cooling curves determined. The transition temperature from the heating curve was found to be 281° C., whereas-from the cooling curve it was 252° C.

Jan 10, 1926