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By A. G. Weber, R. L. Ledbetter, A. L. Hicks

A procedure which makes use of both analog and digital computers has been developed for predicting the pressure-production behavior. of water-drive reservoirs. The electric analyzer is used for matching the past pressure and production history of the reservoir and inferring the physical characteristies of the aquifer. When the history has been matched, a .set of base curves called influence functionce" are derived and the future behavior of the reservoir is calculated from these curves. INTRODUCTION Electric analog methods are particularly well-suited for complex water-drive problems. Like all other methods of analyzing water-drive reservoirs, however, analog methods are subject to certain limitations. One of the more obvious and serious of these results from inaccurate or insufficient knowledge about physical characteristics of the reservoir and aquifer. However, it is not insurmountable because the unknown characteristics can usually be inferred from the reservoir's previous behavior. Simons and Spain have shown that even with scant reservoir data and limited production history, electric analyzer studies can provide useful and reliable results. Aside from this limitation on analyzer predictions, the main disadvantage has been lack of a technique for keeping predictions abreast of latest production forecasts. Pressure behavior of a reservoir depends on the rate at which fluid is withdrawn; it is therefore necessary to specify the future withdrawal schedule before the future pressure behavior can be calculated. Conventionally, the electric analyzer predicts pressure behavior for a specific production schedule. If this schedule is abandoned in favor of some new one, as is frequently the case, either the study must be rerun or results adjusted in some manner. The usual procedure is to predict pressures for several different forecasts covering a wide range of production rates. Pressures for specific rates other than those studied can then be approximated by interpolating between the analyzer predicted curves. However, reliability of this type of prediction is doubtful. This paper describes a technique for predicting future behavior of water-drive reservoirs that retains all advantages of electric analyzer analysis and eliminates the main disadvantage. That is, the analyzer is used conventionally to infer unknown reservoir parameters from the pressure history, but not to predict the future behavior directly. Instead, a derived set of base curves, called influence l'unctions, can be used to calculate future behavior for any production schedule.

By J. S. Ross

Few Canadians realize the role of their domestic industrial minerals industry because it is over-shadowed in production value by a large metallic minerals industry. But since 1960, Canada has had a reasonably well balanced, mature industrial minerals industry; and although the nation's sparsely scattered population has not been able to support an industrial minerals industry in a manner comparable to the domestic and foreign support given the metal mining sector, Canada is, nevertheless, exporting large quantities of higher priced nonmetallic minerals. Production of many of the basic minerals had been firmly established long before 1960, but it was not until the late 1950's that the output of cement, salt, titanium dioxide pigment and slag, sulfur, gypsum and sodium sulfate reached relatively high levels. Shortly after 1960, the significant potash and lithium chemicals industries were established and their effect is just now being realized.

Jan 11, 1964

By F. M. Simonds, E. Z. Burns

The Rawley property is located in the Kerber Creek mining-district, Saguache county, Colorado, at an elevation of 10,600 ft. (See sketch-map, Fig. 1.) Ore was found in this vicinity as early as 1880, and claims covering a large area were located and in many instances patented. The ores, however, being of comparatively low grade, and the nearest railway station, Villa Grove, being some 20 miles away, it is extremely doubtful whether any considerable amount of ore was ever handled at a profit. It is safe to say that several hundred thousand dollars were spent (a large part in building mills) previous to 1902-03. About that time a very capable promoter gathered together a group of these claims and interested some New York people, who had had no previous mining experience, in the purchase of these claims. Following the organization of a company, this promoter became General Manager. As often happens under such conditions, the first step was to erect a mill to treat 100 tons per day. It may not be fair to this enterprise to say that the failure which followed might have been foretold, simply on general principles, but this much is certain—the water supply fluctuates in the course of a season through a wide range and for a considerable portion of the year was inadequate to run this mill at capacity. Further, it is currently reported that some of the mill foundations were placed on ice. However true this statement may be, it is a fact that, when first inspected by us, many of the belts in the mill were held on'their pulleys by means of idlers. A shut-down followed, with a material re-adjustment of interests, at which time we became consulting engineers for the company.

Jan 1, 1914

By N. J. Grant, E. Gregory

The creep rupture properties of wrought aluminum powder products made from five grades of sintered aluminum powder were investigated at temperatures from 400° to 900°F for rupture times up to 1000 hr. The effect of stress concentrations on materials of this type was investigated by means of notched creep rupture tests. A tentative correlation was obtained between the creep rupture properties and the structure as revealed by electron micrographs. SEVERAL papers have been published recently concerning the production and properties of wrought aluminum powder products and their possible high temperature applications. Most of the published work in this field has come from abroad, notably Switzerland, and articles by Irmann and his colleagues were summarized in English recently.'.' Most of the papers published by Dr. Irmann are principally concerned with the retention of properties (by a product which is produced from extremely fine flake powder and is subsequently hot extruded) after heating to high temperature for prolonged times. The powder may be in atomized or flake form, and during hot working the applied pressure is reported to plastically deform the aluminum powder, thus breaking the oxide skin and welding the particles together. Irmann attributes the remarkable properties to the dispersion of oxide inclusions. Specifically, the product described by Irmann is one labeled SAP (Sintered Aluminum Powder) in which the initial flake powder is so fine that at least 50 pct of the flakes have one dimension of 2 microns or less. The composition of the starting aluminum shows in percent, Fe, 0.18; Si, 0.19; Zn, 0.06; Ti, 0.03; Cu, Mn, Mg, all nil; balance Al, approximately 99.5 pct. Aluminum is not the only material that has been found to have increased resistance to deformation at elevated temperatures when produced by powder metallurgy. It has been reported by Middleton, Pf eil, and Rhodes- hat platinum has a higher recrys-tallization temperature when produced by powder metallurgy and exhibits peculiar properties, many of which are similar to those of the aluminum powder products. Difficulties were encountered in explaining the reason for the strengthening in the case of platinum since the existence of the oxide is doubtful. The authors attributed the special properties to "a small amount of suitably dispersed porosity." This theory was supported by von -~eer-leder4 in the discussion to the paper, and the similarity between this method of hardening and that suggested by Rohner in his theory of age hardening was pointed out. R. de Fleury5 attempted to explain some of the properties in terms of the modulus of elasticity and elastic limit of alumina and aluminum while von Zeerleder examined the relationship between the yield strength and the reciprocal of the powder particle size. Boenisch and WiderholtQ dealt mainly with the corrosion resistance of the powder aluminum material and compared it with other aluminum alloys. The diffusion rates of other metals in SAP and pure aluminum have been compared by Seith and Lop-mann.' They showed that the alloying metals diffuse particularly quickly in SAP possibly due to the very fine grain size. The properties of the Alcoa products were given by Lyle.' The creep rupture properties of SAP and two of the Alcoa experimental powder products were compared by Gregory and Grant hnd it was shown that these products are vastly stronger at 900°F than are the best cast and wrought alloys at 600°F. Since the publication of these data, the authors have investigated two further aluminum powder products and it is the object of this paper to show how the high temperature creep rupture properties of the five materials vary with oxide content and with the structure as revealed by electron microscopy. Materials One of the five products, SAP, a sintered aluminum product, was supplied by the Societe Anonyme pourl Industrie de l,Aluminium, Neuhausen a/RHF, Switzerland, through Dr. R. Irmann, while the others, M276, M257, M293, and M255 were supplied by the Aluminum Company of America as experimental powder metallurgical products. M255- and M293 were made from coarse and fine atomized powders, respectively. The other materials were made from flake powders with significant differences in oxide content, the details of the type of powders used in the manufacture of these materials

Jan 1, 1955

By H. L. Luo, P. Duwez, C. C. Chao

BY rapidly cooling alloys from the liquid state, it is possible to obtain solid solutions beyond the equilibrium concentrations, provided that the components are miscible in the liquid state. Typical such cases include CU-Ag,1 Pt-Ag,2 CU-Rh,3 nickel-base alloys with silicon, germanium, and tin,4 and cobalt-base alloys with silicon, germanium, tin, aluminum, and gallium.5 In the present note it is shown that terminal solid solutions can be appreciably extended in A1-Mg alloys. The alloys whose compositions are given in Table I were prepared by induction melting in tantalum crucibles under an argon atmosphere. Both aluminum and magnesium were 99.99 pct pure. Weight losses after melting were less than 0.2 pct for the aluminum-rich alloys and less than 0.4 pct for the magnesium-rich alloys. From these weight losses it was estimated that the compositions of the ingots after melting were accurate within 0.3 at. pct for aluminum-rich alloys and within 0.5 at. pct for magnesium-rich alloys. As indicated in Table I, the compound AuCd10 in which there is an ionic contribution to the bonding. The authors thank Dr. J. H. Westbrook of the Research Laboratory, General Electric Co., for arranging the supply of materials and for his interest. This investigation was supported by the U.S. Atomic Energy Commission under Contract AT(30-1)-1002, Scope I. some of the alloys were also chemically analyzed and the results confirmed the limits of uncertainty based on weight losses. Rapid quenching from the liquid state was achieved by techniques previously described.8,7 The principle of these techniques consists of propelling a small globule of liquid alloy (about 20 mg) onto a copper substrate. The thin foils easily detached from the copper substrate were analyzed by X-ray diffraction using a Debye-Scherrer camera 114.6 mm in diameter and either nickel-filtered copper Ka or iron-filtered cobalt Ka radiation. Since the back-reflection doublets were resolved, the wavelengths used in the computatioas were CuKal = 1.54050A and CoKa1= 1.78892A. Lattice parameters were obtained by extrapolation of the Nelson-Riley function, and the tables compiled

Jan 1, 1964

TITANIUM is one of the most abundant elements in the minerals that make up the earth's crust but its use in industry is only a generation old; yet probably no other important commercial mineral raw material (except possibly magnesium) has undergone more changes and developments in sources of supply, in processing techniques, in uses and applications, in the past 10 years, or stands on' such a threshold of still more advances. Its outstanding use today is as the oxide, and because of its extreme whiteness, high refractive index, chemical stability, and relative cheapness, it has become the white pigment used in the largest volume. New developments in the uses of titanium metal, potential and actual, may surpass the pigment use of the oxide before many years. TITANIUM-BEARING MINERALS Although a number of minerals contain titanium as the principal metal, only a few are of commercial importance. These are arizonite, ilmenite, and rutile. The other oxides, brookite, pseudobrookite, and anatase, occur in a few deposits, one at least of minor importance. The silicate titanite, and the double oxide of calcium and titanium, perovskite, occur in a few deposits in quantities sufficient to be considered as potential ores were not richer deposits of the oxides available elsewhere. Arizonite is a name given by Palmer46a to a mineral found some years ago in minute quantities in Arizona, which has the formula Fe203.3Ti02. Unexpectedly, it was found that the black titaniferous iron oxide found in large quantities on the beaches of many continental land masses corresponds in chemical composition to this formula (although ferrous oxide is always present). No one has yet been able to prove that the commercial mineral on the beaches is truly arizonite, or an allotropic modification of it, since X-ray investigations by Howard Carl and A. F. Gabriel, of the U. S. Bureau of Mines, and by the X-ray laboratory of the Chemical Department at the Experimental Station of the du Pont company, have shown only that the sand mineral gives just a jumble of lines, rather than an identifiable pattern. Lack of a better name,

Jan 1, 1949

By Charles C. Russell, Glenn C. South

A primary factor in the selection of coals for making coke at high temperatures is the amount of pressure the coal will exert upon the oven walls when carbonized in modem by-product ovens.l-3 This factor has become increasingly important in recent years because of demands for increased throughput and higher coke yields. As a result of the increasing necessity for assessing coals in regard to their carbonization pressures, more and more research work is being directed toward developing labora-tory-scale tests for predicting carbonization pressures and for showing how blends of coking coals may be modified to eliminate pressures liable to damage coke-oven walls. The specific reasons have never been defined as to why some blends of coking coals develop dangerous carbonization pressures and others do not, therefore specific procedures to eliminate dangerous pressures could not be prescribed. It is true that the major processes occurring during carbonization have been described by many writers,4 and there is a general agreement on the ideas of the changes that occur as coal is transformed into coke. However, there is little evidence relating the processes occurring during carbonization to the pressure developed and the available evidence is very incomplete and often contradictory. This deficiency arises in part from the fact that the fundamental causes of pressure development have not been defined, at least from experimental data, and in turn this is the result of the lack of satisfactory testing equipment for studying the problem. Operating experience has shown several ways of reducing or eliminating dangerous pressures,5 but probably none of these ways is applicable to all blends of coking coals, and such empirical methods often lead to production of inferior coke. They are trial-and-error methods, not designed to remedy specific causes of pressure development. The number of laboratory-scale testing devices designed to estimate the carbonization pressures that result when coals are carbonized in commercial ovens is probably well over a hundred.6 Few of these instruments have remained in use for any length of time, either because the predictions were not sufficiently accurate or, more often, because too many exceptions were found. Often testing devices are operated without any attempt at duplication of conditions in commercial ovens and erroneous and contradictory results are frequently obtained. Therefore, it has seemed desirable to study the properties of coal itself and to determine any relationships between the properties of the coal and the carbonization pressures developed. Relationship between Properties of Coal and Carbonization Pressure Attempts to determine relationships between various properties of coal and carbonization pressures, for the most parti have been indirect because no satisfactory and reliable laboratory testing device has

Jan 1, 1944

By Glenn C. South, Charles C. Russell

A primary factor in the selection of coals for making coke at high temperatures is the amount of pressure the coal will exert upon the oven walls when carbonized in modem by-product ovens.l-3 This factor has become increasingly important in recent years because of demands for increased throughput and higher coke yields. As a result of the increasing necessity for assessing coals in regard to their carbonization pressures, more and more research work is being directed toward developing labora-tory-scale tests for predicting carbonization pressures and for showing how blends of coking coals may be modified to eliminate pressures liable to damage coke-oven walls. The specific reasons have never been defined as to why some blends of coking coals develop dangerous carbonization pressures and others do not, therefore specific procedures to eliminate dangerous pressures could not be prescribed. It is true that the major processes occurring during carbonization have been described by many writers,4 and there is a general agreement on the ideas of the changes that occur as coal is transformed into coke. However, there is little evidence relating the processes occurring during carbonization to the pressure developed and the available evidence is very incomplete and often contradictory. This deficiency arises in part from the fact that the fundamental causes of pressure development have not been defined, at least from experimental data, and in turn this is the result of the lack of satisfactory testing equipment for studying the problem. Operating experience has shown several ways of reducing or eliminating dangerous pressures,5 but probably none of these ways is applicable to all blends of coking coals, and such empirical methods often lead to production of inferior coke. They are trial-and-error methods, not designed to remedy specific causes of pressure development. The number of laboratory-scale testing devices designed to estimate the carbonization pressures that result when coals are carbonized in commercial ovens is probably well over a hundred.6 Few of these instruments have remained in use for any length of time, either because the predictions were not sufficiently accurate or, more often, because too many exceptions were found. Often testing devices are operated without any attempt at duplication of conditions in commercial ovens and erroneous and contradictory results are frequently obtained. Therefore, it has seemed desirable to study the properties of coal itself and to determine any relationships between the properties of the coal and the carbonization pressures developed. Relationship between Properties of Coal and Carbonization Pressure Attempts to determine relationships between various properties of coal and carbonization pressures, for the most parti have been indirect because no satisfactory and reliable laboratory testing device has

Jan 1, 1944

By E. Bicknese, R. Clark

The mechanism and rate of reduction of FeO at conditions similar to those in the stack of a blast furnace have been determined for temperatures from 980" to 1165°C. Preliminary studies of the reduction of Fe2O3 with activated coconut charcoal in a static system (no flow of reducing gas) have shown that the CO2-CO ratio of the product gas depends upon the relative reactivities of the Fe2O3 and charcoal. In a systern with a "hot blast" of CO and Nz (simitar to dry bosh gas), synthetic FeO, and actiuated coconut charcoal, the rate of reduction was not sensitive to the flow of reducing gas, and the rate-controlling step alas the chemical reaction at the metal-oxide interface. Wherz solid carbon was not present, a critical flow rate of reducing- gas had to be met in order to prevent a lowering of the reduction rate. The effect of a less-reactive carbon (blast-jurnace coke) and of a "natural" FeO on the mechanistn and rate, and the mininum amount of carbon necessary in the charge to tnaintain the reducing potential of the gas phase, have been determined. THE importance of iron oxide reduction processes has encouraged many studies of the process reaction kinetics. Despite this, the mechanism is not well-understood and three main theories have evolved, which can be stated as follows: A) the rate-controlling step is diffusion, either gaseous diffusion of the reductant or product gas through a porous solid,' or solid-state diffusion of iron and oxygen atoms through the so1id.2 B) The slow step is diffusion of reducing gas through a stagnant boundary layer. C) The reaction rate is controlled by the chemical reaction occurring at the metal-oxide interface and is proportional to the area of this interface.3 By increasing the velocity of the reducing gas to a flow rate beyond which no increase in the reduction rate is observed, critical flow rate, it may be possible to eliminate B as the slow step. However, as warnere points out, the establishment of a critical flow rate may only assure that the reaction is not limited by a reduction in the reducing potential of the gas and that B may still be the rate-determining step. Edstrom and Bitsianes and Seth and Ross8 show that A and C may both be correct for the reduction of the same oxide, depending upon the stage of the reduction, and that the relative importance of the two mechanisms varies with the porosity of the oxide. Themelis9 has derived expressions which express A, B, and C in terms of the fraction reduction, Rx, of a spherical particle. Thus, in the case of A a plot of In (1 - Rx) vs time must be linear and the time to reach a given reduction is proportional to the square of the particle diameter. For B a plot of (1 - Rx) vs must be linear and the time to reach a given reduction is proportional to the square of the diameter. For C a plot of 1 - (1 - RX)1/3 vs f must be linear and the time to reach a given degree of reduction should be proportional to the diameter. In the case of mixad controlled reactions, none of the plots are linear over their entire length. The results of previous studies, in which the rates of gaseous reduction of iron oxide were measured in the absence of carbon, may not correspond to blastfurnace practice because they ignore the effects of the Boudouard reaction. CO2 +C — 2CO The presence of carbon may alter the mechanism or the rate of iron oxide reduction through an enrichment of the gas phase by Eq. [1]. In this case, the presence of and reactivity of carbon become important. If the Boudouard reaction has no effect on the rate of reduction, the reducing gas could be supplied by some means other than the gasification of carbon at the tuyeres and carbon could, theoretically, be eliminated from the burden. Preliminary studies of the reduction of Fe2O3 with activated coconut charcoal were made to determine if the reactivity (surface area) of the Fe2O3 had any effect on the product gas composition. Two size fractions of Fe2O3 were reduced with charcoal in a static system (no flow of reducing gas). In each case the charcoal was -100 + 325 mesh and was 25 pct of the total charge. One fraction of the reagent-grade Fe2O3 was submicron in diameter. The other fraction was -100 + 200 mesh and was prepared from the former by compacting, sintering at 1300°C, crushing, and screening. In each experiment, the reaction vessel was filled with a mixture of CO and CO, which would be in equilibrium with FeO and iron at the reaction temperature. A furnace was heated to the desired temperature, the vessel was placed in the furnace, and the gaseous products of the reaction were collected and analyzed. The results of these experiments, Fig. 1, show that the gas phase associated with the submicron oxide is more oxidizing than that with the -100 + 200 mesh oxide. Therefore, in a static system, the relative rates of the reduction reaction and the gasification of carbon depend upon the reactivities of the Fe2O3 and charcoal. The reduction of FeO to iron is the most important reaction occurring in the blast furnace and is probably the slowest of the several reduction steps. The mechanism and rate of reduction of FeO in a system containing carbon and a flow of dry bosh gas have been studied. TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AlME

Jan 1, 1967

By George F. Comstock

It has been known for many years that the alloy containing 90 per cent. copper and 10 per cent. aluminum can be hardened, like steel, by quenching from a suitable temperature, and that the hardened alloy can be softened again by annealing or drawing the temper. It does not seem to be generally appreciated, however, that the effect of the first slight reheating after quenching is actually increased hardness, the softening effect not taking place until a certain temperature of "drawing" has been exceeded. This paper gives the results of a few experiments on various specimens of cast 10 per cent. aluminum bronze, quenched for maximum hardness, and subsequcntly annealed at different temperatures. The hardness measurements were made with both a scleroscope and a standard Swedish Brinell machine; some peculiarities of the scleroscope test on this material are described. The author is not aware of many previous investigations of the hardness of this alloy when quenched and drawn, but two important papers on the subject should be mentioned. The earliest was by Portevin and Arnou,1 in which it was stated that tempering quenched 10 per cent. aluminum bronze at 400" C. increased the hardness as compared with the quenched untempered alloy and that reheating above that temperature ' was necessary to obtain any softening effect. A later paper was by Seidell and Horvitz,2 who mentioned Portevin and Arnou's work, but did not report any increase in hardness obtained

Jan 1, 1925

By H. K. Work, G. H. Enzian

In the manufacture of steel for commercial purposes, the deoxidation practice used, i.e., the method and degree of deoxidation, is an important factor affecting the structure and mechanical properties of the finished steel. Deoxidation practice exerts a pronounced influence not only on the soundness of the ingots but also on the reaction of the steel to a number of mechanical and thermal treatments. The first mentioned effect of deoxidation is more or less obvious and was first demonstrated, though perhaps not fully appreciated, by Robert Mushet when, in 1856, he added speigeleisen to low-carbon bessemer blown metal. In 1861. Bessemer patented the addition of one pound per ton of silicon to his blown metal to "cause the metal to lie quietly in the mold." The second effect of deoxidation-—that is, the effect on the properties and behavior of the steel—is, one might say, more subtle, and certainly not as well understood as the first, although in many cases it is the more important consideration. This paper is limited to a discussion of only the second effect of deoxidation and: in particular, to the effect on the strain-sensitivity of low-carbon steels. General Discussion Originally it was thought that the function of a deoxidizer was to combine with the oxygen present in the steel as iron oxide and prevent its subsequent evolution as a gas. -More recently it has been realized that a deoxidizer does more than this. Frequent reference has been made to the effect of deoxidizers on the nitrogen in the steel, and some attention has also been paid to hydrogen. As a consequence of the above situation any study of deoxidation must be concerned with the gas content of the steel and the effect of the deoxidizer on the gases involved. The term "gas content" as used here refers to gases extracted from steel during melting in vacuum rather than to elements present in steel in the gaseous state. The extracted gases, at least in the case of oxygen and nitrogen, are generally accepted to be products of decomposition of oxides, nitrides, or other more complex compounds. The manner in which deoxidation affects the gas content of steel and the significance of gases in steel have been and still are subjects of considerable speculation. No attempt will be made here to give a complete discussion of the literature on this subject but a few references will be cited for purposes of illustration. N. Hamilton1 found a correlation between the oxygen content of alloy steel and the behavior of the steel during tube piercing. Davenport, Bain, and others associated oxygen with aging properties of steel while Köster5 and a number of others6-lo made similar claims for nitrogen. Daniloff, Mehl, and Hertyll stated that "deoxidation decreases the susceptibility of steels to aging directly

Jan 1, 1945

By Richard P. Rothwell

The anthracite coals of Pennsylvania are all mined from large veins. A seam less than four feet. in thickness is generally considered as unworkable, those from which most of the coal now comes being from 8 'to 30 feet thick. The system of mining employed is, almost without exception, that known as " chamber and pillar work;" that is, the coal is taken out of chambers of from 18 to 30 feet in width, and pillars of from 12 to 20 feet are left between these to support the roof. In general, the entire thickness of the seam, even

By W. L. Finlay

Size effects in quenching steel are particularly prominent and well recognized because of the existence of a critical cooling rate separating nuclea-tion and growth transformations, as exemplified by the formation of pearl-ite, from the shear type of transformation characterizing the martensite reaction. The absence of a similar, sharply demarcating cooling rate is characteristic of precipitation hardening systems and size effects in these are correspondingly less prominent. This paper is concerned with a size effect in high-purity, precipitation-hardenable alloys which appears not to have been recognized previously. This effect is believed to result from the thermal fluctuations which inevitably occur in quenching a specimen of finite size into a cooling liquid rather than from the existence of a critical cooling rate. QUENCHING "ANOMALIES" The precipitation hardening literature contains many references to so-called anomalous quenching and aging results. By "anomalous", investigators usually meant that their alloys did not consistently harden on aging after quenching according to some anticipated pnttern: not infrequently virtually no age hardening occurred with compositions known to be precipitation-hardenable. Perhaps the most prominent series of anomalies was reported over a 15-year period by Gayler and coworkers on aluminum-copper.l,2,3,4 Working with silver-rich copper alloy, Cohen5 secured some very interesting Rockwell F hardness changes of from 1-5 Rockwell points between the first peak and valley. Fink and Smith borrowed one of Cohen's specimens and, following his heat treatment and quenching practice to the letter, secured6 very different results in which only one peak was obtained and in which the hardness level at the aging lime of Cohen's first peak was 20 Rockwell F points higher. Fink and Van Horn7 encountered serious deviations in age-hardening high purity aluminum-zinc alloys. They stated that "the discrepancies were larger than might be expected from possible experimental errors in the Brinell readings." Geisler, Barrett and Mehl8 likewise encountered anomalous hardening results in aluminum-silver alloys, securing quite different age-hardening curves from two identical specimens. They stated that "the treatments of these samples had been the same, so that the different behaviors could be attributed only to accidental variations in the quenching practice."

Jan 1, 1950

By Dan G. Cojocariu, E. Ene-Danalache, I. Huber-Panu

A general model which represents not only batch but also continuous flotation in multi-cell machines is presented. This model considers both the size distribution and the distribution of flotabilities in a size class for valuable mineral particles in the pulp. The general expression is shown to reduce to several previously reported models. In addition, a number of new models are found to arise for different specific assumptions concerning the flotability distribution and/or the size distribution of the particles undergoing flotation. Several of these new models are tested experimentally using laboratory-scale batch and pilot-scale continuous data. Model parameters are estimated from this data and a comparison of calculated recoveries and those experimentally determined are presented. Finally, the influence of the feed rate, aeration rate and valuable mineral content of the feed on the recovery is examined.

Jan 1, 1976

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared for these tests by high-temperature methods, especially by crystallization from borax melts.

Jan 1, 1950

By S. P. Burke

THE presence of gas in coal mines necessitates the use of costly ventila-tion arrangements and the use of expensive mining methods. On the other hand, the gas itself in many instances is of considerable intrinsic value, and its separate recovery might conceivably be a profitable under-taking. This paper is concerned with a study of the movement of gas in coal strata with the object of determining the laws governing gas move-ment and thus making at least a preliminary step toward the solution of the more practical problem of its control or recovery. Naturally, so important a subject has received much attention from scientists and engineers. In most cases, however, the studies have been concerned with the origin1?, the amount2, the composition3 and the method of retention4 of the gas in coal; or, from the more practical side, have been concerned with the phenomena and conditions associated with outbursts5 or explosions and their control. Numerous studies also have been made of the permeability of coal to gas6, of gas pressures measured in coal seams, etc. The authors are unaware, however, of any attempt to present a consistent or complete picture of the laws governing the movement of gas through the coal.

Jan 1, 1935

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metalliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land of which the surface is suitable for: agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago has become valuable agricultural land dotted here and there with growing towns. Frequent references will' be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are applicable to all coal-mining states. Briefly stated, the question is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1928

The Library of the above-named Societies is open from 9 A. M. to 10 P. M. except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions are forced to spend a portion of their time in localities isolated from sources of information. To these the Library; through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention: The Library is prepared, to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general Information on the geology and mineral resources of-all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. HARRISON W. CRAVER, Director.

Jan 4, 1919

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939