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By W. C. Knoblaugh

Rotary kilns are adaptable to many fuels, but this paper deals principally with the use of powdered coal. The observations and conclusions presented are based on rotary kilns used in the manufacture of basic refractories for steel furnaces. Solid fuels are pulverized for two principal reasons: (I) ease of control, and (2) rapidity of combustion. By the use of pulverized coal, the operator can increase or decrease the fuel supply by small increments and with very little time lag between the change of control and the resultant change in the flame. This is extremely important in this type of furnace, as the temperature range for maturing the clinker is very narrow. By fine grinding, it is possible to increase the rate of burning of the coal, thereby liberating great quantities of heat within a small space in a short time. Under given conditions, temperature is a measure of the heat liberated per unit of time. To attain the temperatures of 2950° to 3150ºF., which are encountered in the manufacture of various steel-furnace refractories, it is estimated that it is necessary to liberate 125,000 to 175,000 B.t.u. per cubic foot of the burning zone per hour. The manufacture of dolomitic refractories is a ceramic process and, as is true in most such processes, the material must be subjected to a certain critical temperature for a certain length of time in order to complete the reaction. If the time of reaction is reduced, the temperature must be increased; in other words, if the rate at which the material flows through the hot zone of the kiln is increased, the temperature of the hot zone must be increased to compensate for this shorter exposure to the flame. Firing with Pulverized Coal Fig. I is a line drawing of a rotary kiln with the attendant equipment indicated in their relative positions. The kiln proper consists of a sloping, refractory-lined steel tube rotating slowly about its longitudinal axis (0.75 r.p.m.), and is countercurrent in operation in that the raw feed is introduced at the stack end and gradually approaches the zone of highest temperature at the lower end, where the fuel is introduced. Before 1930, the usual method of firing a rotary kiln was to store the coal in the pulverized form and then feed from this storage to the kiln as needed. This proved unsatisfactory and dangerous because of dust explosions and the inability to obtain an even feed to the kiln caused by arching of the coal in storage and flooding of the coal feeders. In later years the practice has been to store the raw coal and grind it as it is needed. Such a layout is indicated in Fig. I. The coal is stored in bins, charged from the top and drawn from the bottom into recording scales and then into some type of unit pulverizer. There are a number of good pulverizers .on the market, each incorporating features that the manufacturer considers outstanding.

Jan 1, 1948

By Forrest V. Williams

The dislocatiorl and stacking-fault structuve of epitaxial GaAs1-,PX lms been examined by chemical etching. The layers were groun in the (100) direction and etch Pils were developed on (111} planes which nad been lapped and polished on the epiLaxia1 layevs. Tile effecL of the jollolcing cariables on the quality of the epilaxial layers has been examined: doping leuel, grouth rate, and composition. High stacking-faullL densilies weve found in the GuAsi_xpx layers. These are not observed in heavily dolled epitaxial layers tzar in layers with low phosphorus compositions. The dislocatiorz density in GuAsi-x px was highest at the sub-stvate- epilaxia1 layer interface. Composilion changes introduced dislocations in the epitaxial layers. ManY semiconductor p-n junction lasers of Group TIT-Group V compounds and their alloys have been reported in the past several years. Laser action at visible wavelengths in GaAsl-x,Px was first reported by Holonyak and Bevacqua. GaAs, a direct transition semiconductor which lases, and Gap, an indirect transition semiconductor which does not lase, form a continuous series of solid solutions.2 Laser junctions can be fabricated in GaAsl-xPx crystals with phosphorus compositions up to about 40 mol pct. In addition to the production of coherent radiation in these crystals, the efficient recombination radiation of p-n junctions in this material has equally important potential in the development of low-power semiconductor lamps. To achieve a high conversion efficiency of electrical to optical energy in p-n junctions in this material, the relation of physical properties of the crystal to luminescence efficiency must be better understood. Although the electrical, optical, and device properties of GaAsl -xPx junction lasers are understandably of considerable interest, the work to date indicates that the more serious problems are the chemical and metallurgical difficulties encountered in the growth of this material.3 In addition to the problems of chemical purity, crystal imperfections, such as dislocations and stacking faults, can be expected to affect both the efficiency of the radiative recombination process and the perfection of the p-n junction.3 The last requirement, i.c., that of the perfection of the p-n junction, is a particularly troublesome one in the fabrication of laser diodes. To obtain good laser diodes, the p-n junction must be flat, which permits the radiation to be reflected from the resonant cavity boundaries. Junction planarity is extremely sensitive to the crystal perfection of the semiconductor material. Also, it is known that at high dislocation densities (-105 per sq cm) it has not been possible to build laser junctions in GaAsl-xPx . Few studies have been reported on the crystal defect structure of GaAsl-,P,. The first serious study seems to be that of Wolfe, Nuese, and Holonyak,3 who examined the dislocation structure of monocrystalline bulk (nonepitaxial) material grown by halogen vapor transport. In this paper are reported some observations on the dislocation and stacking-fault structure of GaAsl_,P, crystals grown by a vapor transport process on substrates of GaAs. EXPERIMENTAL Crystal Growth. The GaAsl-xPx crystals were grown in an open-tube flow system, using two sets of reagents. GaAs, Pr(red), and HC1 were employed in one method. The transport reaction is =950JC GaAs+HC1 = GaCl +1/4As4 +1/2H2 and the deposition reaction is 2GaAs1-xPx +GaCl3 Composition control is obtained by the flow rate of the HC1 and the vapor pressure of the P4, which is maintained in a separately controlled furnace. The second method has been described by Ruehr-wein4 and utilizes gallium, AsH3, PH3, and HC1. The same transport and deposition reactions as above are involved. Composition control is obtained solely by the flow rates of the three gases involved. All of the crystals were grown on chemically polished GaAs substrates oriented on the (100) plane. The thicknesses of the epitaxial layers were typically 100 to 300p. Revealing of Dislocations. Dislocations were re-vealed on both the( 111 ) and { l l l }b faces by chemical etching. The specimen to be examined was mounted at 54.7 deg, lapped on glass with 3-p alumina, polished on cloth with 3-p diamond paste, and, to remove work damage, chemically polished at room temperature for

Jan 1, 1968

By W. A. Backofen, G. Y. Chin, W. F. Hosford

The effect of machine stiffness on discontinuous flow and fracture of the 2024 aluminum alloy was studied in tension at 4.2OK. An increase of machine stiffness was found to decrease the amount of elongation and drop in load during discontinuous flow, thereby postponing fracture to larger strains and higher stresses. The possibility of utilizing stiffened tools in deformation processing to suppress shear fracture originating from unstable flow was indicated. The problem of nucleating discontinuous flow and the role of the effective mass of the system in discontinuous flow were also considered. AT low temperatures the plastic flow of metals is often discontinuous, with sudden load drops and elongations.1,3 Basinski1,4 has presented strong evidence that discontinuous flow, at least in aluminum alloys, occurs under nearly adiabatic conditions. During testing the load may drop suddenly and flow become localized when the thermal softening, due to heat generated in plastic straining, is greater than the strain and strain-rate hardening. This instability criterion is more easily satisfied at low temperatures because 1) the volume specific heat is reduced so that relatively large temperature increases are possible in straining, and 2) the flow stress is relatively temperature-dependent. The important role of adiabatic shear in ductile fracture processes has been emphasized,5-1 and consideration has already been given to the influences of thermal and mechanical properties on the tendency of a material to undergo adiabatic shear.17677 By focusing attention on how the mechanical loading system influences low-temperature discontinuous flow, additional insight into adiabatic shear and its effect on fracture may be gained. EXPERIMENTAL PROCEDURE Because of its low thermal conductivity, the 2024 aluminum alloy exhibits a highly consistent discon- tinuous-flow behavior at 4.2°K and was therefore chosen as the material for study. Machined specimens of 0.113 in. diam and 1.125 in. gage length were solution heat-treated at 490°C for 3 hr, quenched into cold water, and immediately immersed in liquid nitrogen until just before testing. Testing was done at 4.2°K by immersion in liquid helium at a crosshead drive rate of 0.03 in. per min. As normally used (hard-machine basis), the spring constant of the testing machine was k = 25,000 lb per in. By inserting beam springs in series with the specimen, this value could be lowered by a factor of about 100. Details can be found elsewhere.? As a result of variable machine stiffness, the actual strain rate ranged from about 3 x 10 5 to 3 x 10-4 per sec from one test to another, as well as within any one test. However, preliminary tests had established that the tensile curves were not altered significantly by this strain-rate variation. Fig. 1 shows a typical load vs plastic-elongation curve for a solution heat-treated 2024 aluminum alloy specimen pulled in the standard hard machine (k = 25,000 lb per in.) at 4.2"K. The elastic extension has been subtracted. Plastic flow proceeded smoothly from yielding at approximately 22,000 psi (load = 220 lb) to a strain of about 4 pct at which point the flow became discontinuous. The magnitude of the load drops as well as the plastic elongation per drop increased with increasing strain until the specimen finally broke abruptly. The load-elongation behavior of a sample tested with a relatively soft machine under otherwise identical conditions is given in Fig. 2. In general, there

Jan 1, 1964

Air-sand Process of Cleaning Coal Discussion of paper by THOMAS FRASER and H. F. YANCEY, presented at the New York Meeting, 1926, and issued, as Pamphlet No. 1561-F, with MINING AND METALLURGY, February, 1926. T. DEVENNY, Edgarton, W. Va.-How near the size of the sand can the coal to be treated be brought? Do you use an 8-mesh coal on that cleaner? J. J. RUTLEDGE, Baltimore, Md.-From the little I have seen of the apparatus in operation, I should say 8-mesh. In my experience in metalmine concentration work, trying to separate different minerals on one jig, sometimes I have succeeded and sometimes not. This apparatus has appealed to me; something of this kind should be useful with the silicates and carbonates of zinc. I think this apparatus has possibilities in metal mining. Recently in our coal field a screen has been introduced for cleaning coal; it is giving excellent service. When I asked the inventor why he did not take it to the metal mines, he said there was a good and sufficient reason, in a patent way. There may be reasons why it would not be applicable for metal mining; but the simplicity of it appeals to me and I cannot see why it could not be so used. T. FRASER (written discussion).-We feel that 8-mesh would be about -the minimum size of coal practicable to treat by the air-sand process. This would depend partly upon the friability of the coal. The more nearly the lower size limits of the coal- approaches the size of the sand, the more .time will be required in screening the sand out of the cleaned coal, which would mean a little more chance of breakage. In regard to the treatment of ores; this would necessitate the use of some heavier mediums than ordinary silica sand, or some other means of making the separation at a higher specific gravity than is required for coal. We are now working on a method of obtaining this effect for the preparation of anthracite coal without resorting to the use of heavier and more expensive material than common sand.

Jan 1, 1927

By Robert Bell

THE " Tar-Sands." is the name which has been given to the extensive horizontal deposit of fine Cretaceous sand, blackened by tarry petroleum, which forms the banks of the last or lowest 130 miles of the Athabasca river before it terminates in Athabasca lake. The Cretaceous strata, to which these sands belong, extend northwesterly from Dakota all the way to this lake and for 500 miles beyond it. The Athabasca river forms the uppermost section of the Athabasca-Mackenzie, one of the great rivers of the world. It rises on the Pacific side of the Rocky mountains, westward of Edmonton, and flows north of east to a point called Athabasca. Landing, 100 miles north of Edmonton, where it turns northward and runs about 280 miles before it falls into the west end of Athabasca lake. The section of this river-system which discharges the lake just named into Great Slave lake, is called Slave river, and below the latter lake it becomes the Mackenzie river. Along the section of 280 miles of the Athabasca river above mentioned, the Cretaceous strata consist of bluish-gray and drab-gray marls, on top, from Athabasca Landing to Drowned rapid, 110 miles down stream; then heavily bedded gray sandstones, 225 ft. in greatest thickness, underlying these, form the banks for about 40 miles further. The strata appear to be horizontal, but they really clip very slightly to the southward. At Drowned rapid, we see the first of the tar-sands resting on almost horizontal beds of bluish-gray limestone of Devonian age. In some places the limestone is associated with shaly or marly bands. Notwithstanding the great hiatus between the two series, the horizontal tar-sands lie conformably upon the almost level upper beds of the limestone wherever the two formations are seen together, all along the river, throughout a

Mar 1, 1908

By G. W. Nabor, H. J. Ramey

A blotter-type electrolytic model was utilized to prepare flow diagrams for a field test of the in-situ combustion process. It is pointed out that the areal sweep of a combustion pattern is similar to sweep patterns that would be developed at an infinite mobility ratio, which exists (approximately) across a combustion front because of the complete removal of liquids from the sand behind it. The precision of the blotter method was tested by comparison with results obtained by other techniques and was found to be satisfactory. The blotter-type model will not furnish as much information as more elaborate and expensive potentiometric models, but its speed of operation and ease of construction make it a highly satisfactory tool to determine areal sweep patterns. A tabulation of sweep efficiency and mobility ratio is furnished for various well geometries. INTRODUCTION In connection with the first field experiment with the in-situ combustion method of oil recovery," flow diagrams for the unique well geometry and boundary conditions involved in the subject test were developed. From these diagrams, information concerning the areal sweep and distribution of flow was obtained. A survev of the literature on potentiometric models, utilized to solve two-dimensional flow problems,1,2,3,4,5,6,8,9,10 indicated that the information desired could be obtained by means of a blotter-type model by making certain modifications in the technique. The following discussion describes the application of the modified blotter-type electrolytic model to the solution of the problem of the flow of gases in an oil reservoir for an engineering appraisal of the progress of the combustion front during the first field experiment. Considerable information has been published on the theoretical aspects of electrical model techniques. One author stated that:' "The models are based on the observation that since the velocity of an ion in an electrolytic system is proportional to the potential gradient, just as the velocity of a fluid particle in a porous medium is proportional to the pressure gradient, the paths of the ions in the electrolytic systems must be similar to those of the fluid particles in a porous medium with the same geometry and equivalent boundary conditions." This suggestion of a real analogy has been established repeatedly by comparisons of analytic derivations with model results. The analogy between the movement of a combustion front and the model results is not as apparent, since the combustion process differs from water flooding and gas cycling in that the velocity of the burning front is different from the velocity of the injected fluid at the front in combustion. Analogy between electric current flow and movement of the burning front exists because the local velocity of the burning front is proportional to the air (mass) velocity at this point (assuming frontal temperatures are at least as high as the ignition temperature of the fuel). Most model studies fall into one of two categories: (1) electron conduction, or (2) ionic conduction models. Examples of these are models which employ as flow media either a thin metal sheet, or a porous blotter saturated with an electrolyte, respectively. Of the two, the porous blotter model, an ionic conduction model, appears to be the most adaptable to the flow problem that results when using in-situ combustion. This problem requires that the mobility of the particles in the model be controlled analogous to the mobility of gas flowing through burned sand of high permeability to gas and then through oil sand of lower permeability to gas. Although the blotter model has heretofore been

Jan 1, 1955

By Arthur A. Center

HIGH GRADE zinc stocks were reported short early in 1943, but not Prime Western. Maximum production of High Grade was expected to be reached before the middle of the year, and demands of new brass mills were to take all of the increase. In February three premiums (A, B, C) of 2 3/4c. per lb. of zinc in ore were announced to encourage production from high-cost mines, the number of premiums being in proportion to estimates of ore-production costs.

Jan 1, 1944

By L. V. Pirela, S. M. Farouq Ali

Some interest has been expressed recently in the application of solvents in conjunction with a thermal drive, such as a steamflood. At least one field project of this type has been reported. This paper makes the first attempt to provide some of the basic information necessary for choosing a solvent for such an application. Results of displacements conducted at elevated temperatures are also discussed. This paper shows that, in the case of alcohol-hydrocarbon-water or brine ternary systems, the system miscibility may increase, decrease, or both increase and decrease within the same system when the temperature increases. The distribution coefficient was consistently found to increase in favor of the oleic phase with an increase in temperature, which is advantageous from the standpoint of oil recovery. Results of solvent displacements in a sandstone core showed that even a relatively small temperature effect in the favorable direction (increase in miscibility and distribution coefficient) can lead to a 50 percent increase in oil recovery. On the other hand, if the system miscibility decreases with the temperature, even though the distribution coefficient increases, the oil recovery at the higher temperature may not increase. INTRODUCTION Miscible displacement has been the subject of many investigations. Miscible-phase solvent flooding, employing solvents such as alcohols that are miscible with both oil and water, has received considerable attention. Investigations conducted by Gatlin and Slobod,l Taber, Kamath and Reed,2 Holm and Csaszar,3 and Farouq Ali and Stah14 have helped in understanding the mechanism of solvent flooding. While the use of alcohols and similar solvents as oil recovery agents is economically unattractive, these solvents nevertheless provide a means of understanding the mechanistic aspects of important miscible-phase oil recovery processes such as the Maraflood process (discussed by Gogarty5). As shown by Taber et a1.,2 the phase behavior of a solvent-oil-water system is of .utmost importance in determining the efficiency of the oil displacement. This paper makes the first attempt to obtain the ternary phase behavior data for nine alcohol-hydrocarbon-water/brine systems at elevated temperatures. Results of core tests at elevated temperatures are also presented which corroborate the effect of temperature on oil recovery, as judged on the basis of phase-behavior data. The use of solvents at elevated temperatures has been suggested earlier by Farouq Ali.6 At least one field test of this type has been reportedO7 With the widespread use of thermal recovery techniques, it is possible in some situations (especially in steamflooding) that the use of a suitable solvent in conjunction with the heat carrier may be economically feasible. This paper attempts to provide some of the basic information needed for judging such feasibility. LOCATION OF THE PLAIT POINT The phase behavior of a typical ternary system consisting of a solvent, hydrocarbon and brine (or water) can be represented by a triangular diagram such as the one shown in Fig. 1 (for temperature TI). Point Pon the binodal curve represents the plait point, being the limit of tie lines such as Y1 Y2 The compositions of the coexisting oleic and aqueous phases are given by points Y2 and Y1, respectively, for any mixture composition along Y1Y2. The characteristics of ternary diagrams have been discussed by Findlay8 and others. Taber et aL3 have shown that the position of the plait point in a particular ternary system plays the decisive role in determining whether or not theoleic phase would be displaced in a continuous manner during an alcohol displacement. The area above the binodal curve also is important, since it represents

Jan 1, 1969

By R. W. Raymond

Since the foregoing paper (see p. 387) was printed, I have received the decision of Judge William E. Church, of the first District Court of Dakotah, in the case of Michael Duggan et al. v. John H. and Frank J. Dnvey (Silva Terra—Sitting Bull case), published in full in the Black Hills Weekly Pioneer of August 9th, 1584. The journal mentioned gives also several interlocutory decisions rendered in earlier stages of the case; but I shall quote here only so much of the final decision as bears upon the .construction of the Revised Statutes concerning the apex, the end-lines, and the extra-lateral mining right, together with a sufficient statement of the facts of the case to explain the scope of the decision. " This is an action in equity, brought in the first instance to restrain a threatened trespass by the defendants upon certain mining property in the possession of the plaintiffs, known as the ' Silver Terra' claim ; the allegation being that the defendants were about to enter, through underground workings, the ground of the plaintiffs, and remove therefrom valuable bodies of silver ore. " The answer of the defendants, admitting the acts constituting the alleged threatened trespass, further averred that they had, in fact, at the time complained of, reached and passed, in their underground workings, throngh and beyond the vertical side-line of the Silver Terra claim, and therenpon justified the acts complained of, and claimed the right to pursue their workings into and through the Silver Terra ground, by virtue of their alleged proprietorship of a vein, lode, or ledge of rock in place, hearing silver, having its top or apex within the lines of a certain other mining claim called the ' Sitting Bull,' of which they claim to be the owners, which vein, lode, or ledge extended in a continnons body of mineral-bearing rock from such top or apex to the ground in controversy, and constituted the body of ore in dispute; and that it was in the pursuit of this vein, lode, or ledge in its downward course that they had passed beyond the vertical side-lines of the Sitting Bull claim, and for some hundreds of feet beyond, into the ,ground in controversy " Subsequently, a supplemental complaint was filed, setting up the entry into plaintiffs' ground by the defendants, and their claim of right to do so, and asking fnrther relief by a decree restraining the assertion of such claim, and quieting the title of plaintiffs. "The case was tried before the court without a jnry..... " Custer hill, upon which these claims are located, is situated in the village of Galena, in Bare Butte mining district, in this county. The village lies at the base of the western slope of the hill, which presents a lateral face from south to north

Jan 1, 1884

By J. H. Henderson, R. J. Wygal, J. Naar

Experimental work is reported which shows that consolidated rocks and unconsolidated porous media exhibit different imbibition flow behavior. At a given saturation the imbibition nonwetting permeabilities for a rock are smaller than the drainage permeabilities. The contrary happens for unconsolidated aggregates — imbibition nonwetting permeabilities are larger than drainage ones. A similar difference is observed for the wetting phase. Imbibition permeabilities are larger than drainage ones for a consolidated rock but smaller than drainage permeabilities for an unconsolidated medium. The results of these differences are examined for two cases. 1. Flooding Efficiency — Craig's1 scheme for the computation of production history of a five-spot water flood is shown to agree extremely well with experimental results obtained when using a system packed with glass spheres if imbibition relative permeability curves are used. 2. Alcohol-Slug Displacement — Published theory 2 on oil displacement by alcohol slugs has been questioned despite the apparent agreement between predicted and observed results. The present work suggests that, if imbibition relative permeability curves characteristic of the unconsolidated media used in the early experiments had been available to make the predictions, the inadequacy of the theory would have been immediately evident. The experimental work shows that poorly consolidated formations tend to behave like unconsolidated media. Finally, it is shown that the difference in imbibition behavior is directly related to pore-size distribution and cementation. PART 1 — THE FLOW BEHAVIOR OF UNCONSOLIDATED AGGREGATES Experiments on scaled models of field reservoirs are useful for studying new displacement processes which are incompletely understood. Even when a mathematical description is possible, the solution might be difficult and complex. An answer obtained from a scaled model is extremely valuable in such cases. A great amount of work$-5 therefore, has been devoted to the derivation of scaling laws. Similarity groups have been defined which assume (1) that the relative Permeability curves of the prototype and the model are the same whether the displacement is an imbibition or a drainage process and (2) that there is a linear relationship between the capillary pressure of the model and the prototype. For practical reasons (simplicity in the preparation of models, duration of the experiments, etc.), the porous media of laboratory models are usually unconsolidated packs of sand or glass particles. Hence, unless the capillary and flow characteristics of unconsolidated and consolidated systems are identical, the model data are applicable only to unconsolidated formations. The usefulness of scaled-model studies may then be seriouslyrestricted since most oil-bearing sands are consolidated. Perkins and Collins6 suggested the use of model and prototype curves normalized with respect to both relative permeability and saturation to improve compliance with scaling criteria. Even this technique does not give a satisfactory model-prototype match. This paper reports an observation of two-phase flow in unconsolidated sands which shows that, for most displacements, "scaling" in the strict sense of the word is not even qualitatively feasible with a sand model. It provides, however, a firm foundation for testing a theory by matching it with observed performance of laboratory-size models. EXPERIMENTAL AS a part of a basic study of packed aggregates, the relative permeability of glass-spheres and sand-grain packs was measured with capillary control. The fluids were oil and air' The spheres were packed in plastic cylinders 1-in. in diameter;

By M. Muskat, H. H. Evinger

ALTHOUGH the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.1 In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was. measured and an attempt was made to determine the effectiveness of 'sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to determine the effect of tamping were performed by Snelling and Hall,2 Small charges (20 grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.3 The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.5 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

IN the early period of steelmaking, ingot structure and segregation were of no practical importance. Crucible melting required very small ingots that gave little segregation, and a small inserted hot top prevented pipe. As larger ingots were poured from bessemer converters and open-hearth furnaces, segrega- [ ] tion, piping, and gas evolution became increasingly important. The techniques of making semikilled and rimmed ingots were developed with little knowledge of the actual mechanism of the process. The first studies of solidification were made by the Brearleys1 and Gathmann,2- who used stearine to show the effects of shrinkage and mold shape. Fig 11-1 is a picture of a series of stearine ingots at various stages of solidification. These studies showed that the liquid solidifies at a nearly uniform rate from the sides and bottom of the mold and demonstrated the formation of

Jan 1, 1964

By Roscoe Bell

An economic appraisal of the western phosphate industrial potentials made between 1945 and 1948 revealed possibilities for a considerable expansion in the production of high analysis phosphate fertilizer. The most significant facts are: (1) a rapidly increasing and a much larger potential market which might be reached from the western deposits, (2) the existence of large undeveloped deposits of phosphate rock, (3) potential energy from sulphuric acid, coal, or hydroelectric power in the general vicinity of the deposits. The challenge to the mining and metallurgical engineering profession is in the economical development of phosphate mines and in improving processes for utilization of the western ores and the recovery of byproducts to make the expanded western industry satisfactorily compete with the industry in the East and South in meeting the fertilizer needs of the Midwest and Far West.

Jan 4, 1950

By J. M. Eldridge, P. Balk

Phosphosilicate glass films were formed, by reacting gaseous P2O5 with SiO2, over a large range of temperature (800° to 1200°C) and gas phase composition (nearly two orders of magnitude of effective P2Ospressure). The film compositions generally corresponded with the liquidus curve, delineating the maximum solubility of the tridymite Phase of SiO 2 in phosphosilicate liquid solution at the temperature of film formation. It is shown that the P2O5 concentration of the phosphosilicate liquid film tends to decrease by reaction with the underlying SiO 2 layer until the liquidus curve is reached. The validity of the thermodynamic argument used in this explanation is supported by the results of a determination of the composition of borosili-cute films, prepared by reacting gaseous B2O3 with SiO2 at different temperatures. The kinetics of phosphosilicate film formation were described by a model predicated on a steady-state diffusion of P2O5 through the film. UNDERSTANDING of the processes leading to formation of phosphosilicate and borosilicate glasses is of great importance for producing passivating layers on FET devices. Passivating films with optimum characteristics are preferably formed in a separate step, independent of the doping of the semiconductor.' The results of an investigation carried out to gain improved insight into the mechanism of glass formation are presented in this paper. It would be expected that application of the known Pz05-Si02 and B 2 O 3-SiO2 phase diagrams should be useful in extending understanding of the glass-forming processes. However, the question of the propriety of treating thermally grown SiO2 in these binary oxide systems by the methods of equilibrium thermodynamics must be considered when this application is attempted. Although Sah et a1.' and Allen et al. 3 investigated the kinetics of formation of phosphosilicate glass (PSG), they failed to adequately relate their diffusion models to the occurrence of experimentally observed phases in the PSG/SiO 2/Si system. Horuichi and yamaguchi4 investigated the diffusion of boron through an oxide layer and described their results in terms of a model similar to that of Sah and coworkers. More recently, Kooi 5 and Snow and Deal6 reported the compositions of PSG films formed by depositing P2 O 5 onto SiO2. These compositions apparently coincide with those at the liquidus curve delineating the maximum solubility of crystalline SiO2 in phosphosilicate liquid solutions. These authors did not discuss the thermodynamic implications of their results on the structure of thermally grown SiO2 films. The structure of thermally grown Sio2 films and that of vitreous silica are generally thought to be quite similar. Since the solubility of a substance depends on its structure, it is relevant that the solubility of vitreous silica in water7 is highly reproducible, like the solubility of thermally grown SiOz in phosphosilicate liquid. Furthermore, the vitreous silica-water system appears to be in true thermodynamic equilibrium (viz., the same solubility value can be approached from both supersaturated and under-saturated solutions). Sosman7 suggested that a type of two-dimensional lattice may form at the silica/solution interface, resulting in the observed solubility behavior that is characteristic of a crystalline solid. An alternative explanation may be that vitreous silica has a microcrystalline grain structure. Other investigators have suggested that vitreous silica has essentially the structure of B cristobalite,' or is composed of microcrystals of p tridymite or cristobalite, or a mixture of both. Presumably the grain size would be sufficiently large to minimize any appreciable contribution of the grain boundaries to the solubility of the crystalline matrix. The present investigation was carried out to clarify the significance of the boundaries in the Pa,-SiO, and B2O3-SiO2 Systems in determining PSG and BSG (borosilicate) film compositions. Furthermore, the kinetic data for PSG film formation were extended, using a wider range of formation parameters than were previously reported. One model describing the kinetics of film formation will be presented that is compatible with the thermodynamics of the Pa5-Si02 system. EXPERIMENTAL PROCEDURE Glass Film Preparation. SiO2 films (1000 to 8000A thick) were obtained by oxidation of silicon substrates in dry O2 at 1100°C. PSG and BSG films were prepared by exposing these layers to gaseous oxides obtained by reacting high-purity POC13 and BBr3, respectively, with O2. A double-columned saturator was used to ensure complete saturation of the N 2 carrier

Jan 1, 1969

By E. W. Cawthorne, R. I. Jaffee, C. M. Craighead

SOLUTION of a solid metal or alloy in a molten metal bath is used daily in melting operations, extractive metallurgical processes, and in brazing. It is generally recognized that temperature, time, agitation, and the composition of the solute metal and the solvent bath all affect solution rate. However, there is little information available in the literature on the kinetics of the process or the relative effect that these variables have on solution rate. In connection with an aluminum brazing study, data on the solution of aluminum in an A1-Si* bath to promote rapid solidification. The chemical analyses were made on drillings taken from the cast plates. The results of this work are listed in Table I. The thermal-analysis data were obtained on 200 gram samples cooled at approximately 1.5" per min. A calibrated chromel-alumel couple was used. The thermal arrests were recorded autographically on a General Electric photoelectric potentiometer recorder. The instrument was calibrated to 22.5 pct. The thermal emf was bucked with a Leeds and Northrup semiprecision potentiometer so that 1 mv represented the full scale of the GE recorder. Referring to Table I, it will be noted that the analytical results tend to be lower than the intended compositions by about 0.3 pct Si in the higher ranges. In view of the known difficulties in obtaining accurate silicon determinations by wet analysis when the silicon content is high and in view of the care that was employed in weighing and preparing the alloys, the intended compositions are believed to be more accurate than the analyses. Furthermore, when the thermal-arrest data are plotted against the intended compositions, a smooth curve is obtained, as shown in Fig. 1. This is not the case when the data are plotted against the analytical results. It will be noted from Table I that the 12.5 pct Si alloy (melt 4) showed a primary arrest at 577.6"C and the eutectic at 576.l°C. The metallographic examination of this chill-cast plate sample showed a small amount of primary silicon. These results, Fig. 1, place the eutectic at slightly less than 12.5 pct Si and are in rather good agreement with the unpublished Hanford data. In all of the subsequent work, the composition of the A1-Si dipping baths was determined by thermal analysis (spread between the primary arrest and the eutectic temperature) employing 12.5 pct Si and 577.2 °C as the composition and temperature of the eutectic. Material Preparation and Selection of the Techniques: At the beginning of this work, it was anticipated that, owing to oxide film present on the surface of the aluminum, difficulty would be encountered in obtaining rapid uniform wetting of aluminum specimens dipped in the A1-Si bath. The following etchants were investigated as possible methods of providing a thin uniform oxide film on the specimen surface: 1—phosphoric acid (H³O4), 2—fluoboric acid (HBFI), 3—sodium hydroxide (NaOH), and 4—hydrofluoric acid (HF). Tests with sheet .specimens (2x½x0.06 in.) of 2s aluminum prepared with these etchants indicated that the fast uniform wetting required for this work could not be obtained if any oxide film existed on the specimen surface. Tests were then conducted by dipping similar specimens etched in 5 pct NaOH and given a thin

Jan 1, 1956

By Shiou-Chuan Sun

THIS paper presents the design and operation of a frothmeter capable of measuring the frothing characteristics of pine oils and other frothing reagents. The experimental data show that the froth-ability of pine oil is governed by: 1—rate of aeration, 2—time of aeration, 3—height of liquid column, 4—chemical composition of pine oil, 5—pH value of solution, 6—temperature of solution, and 7—concentration of pine oil in solution. The effect of mineral particles on the behavior of froth also was studied, and the results can be found in a separate paper.' The results also show that the relative froth-abilities of pine oils in the frothmeter generally correlate with those in actual flotation, provided that other factors are kept constant. In addition to pine oils, the other well-established flotation frothers were tested, and the results are included. In this paper, compressed air frothing is the frothing process performed by means of purified compressed air, whereas sucked air frothing is the frothing process accomplished by purified air sucked into the glass cylinder by a vacuum system. The term vacuum frothing denotes that froth was formed by degassing of the air-saturated liquid under a closed vacuum system. Apparatus The frothmeter, shown in Fig. 1, is capable of re-producibly measuring the volume and persistence of froth as well as the volume of air bubbles entrapped in the liquid and is capable of being used for compressed air frothing, sucked air frothing, and vacuum frothing. Fig. la shows that for compressed air frothing, the apparatus consists of an airflow regulating system, 1-3; a purifying and drying system, 4-8; a standardized flowmeter to measure the rate of airflow from zero to 500 cc per sec, 9; and a graduated glass cylinder, 13; equipped with an air regulating stopcock, 10; an air chamber, 11; and a fritted glass disk to produce froth, 12. The fritted glass disk, 5 cm in diam and 0.3 cm thick, has an average pore diameter of 85 to 145 microns. The pyrex glass cylinder has a uniform ID of 5.588 cm and an effective height of 63 cm. The inside cross-sectional area of the glass cylinder was calculated to be 24.53 sq cm, or 3.8 sq in. For sucked air frothing, Fig. lb shows that the apparatus for compressed air frothing is used again, with the following modifications: 1—compressed air and its regulating system, 1-3, are eliminated; and 2—a vacuum system, 16, equipped with a vapor trap, 15, and a vacuum manometer, 17, is added. The vacuum system can be either a water aspirator or a laboratory vacuum pump. Any desired rate of airflow can be drawn into the glass cylinder, 13, by adjusting the opening of the air regulating stopcock, 10. The sucked air stream is cleaned by the purifying and drying system, 4-8, before entering the glass cylinder, 13. When this setup is used for vacuum frothing, the air regulating stopcock is closed. The frothmeter has been used for almost 3 years and has proved to give reproducible results, as illustrated in Table I. With a magnifying glass and suitable illumination, the frothmeter also can be used to study the attachment of air bubbles to coarse mineral particles.' Experimental Procedures Except where otherwise stated, the data presented were established by means of the compressed air method. The volume and persistence of froth were recorded respectively at the end of 4 and 6 min of aeration at a constant rate of airflow of 29.3 cc per sec, which is equivalent to 71.6 cc per sq cm per min, or 462.6 cc per sq in. per min. The aqueous solution for each test, containing 1000 cc of distilled water and 19.2 ± 0.5 mg frothing reagent, was adjusted to a pH of 6.9 0.2. The volume of froth is expressed as cubic centimeter per square centimeter and is equivalent to the height of the froth column (the distance between the bottom and the meniscus of the froth). The volume of froth was obtained by multiplying the height of froth by the cross-sectional area of the glass cylinder, 24.53 sq cm. Before each test, the glass cylinder, 13, was cleaned thoroughly with jets of tap water, ethyl alcohol, tap water, cleaning solution, tap water, and finally distilled water. The cylinder with stopcock,

Jan 1, 1953

By Shiou-Chuan Sun

THIS paper presents the design and operation of a frothmeter capable of measuring the frothing characteristics of pine oils and other frothing reagents. The experimental data show that the froth-ability of pine oil is governed by: 1—rate of aeration, 2—time of aeration, 3—height of liquid column, 4—chemical composition of pine oil, 5—pH value of solution, 6—temperature of solution, and 7—concentration of pine oil in solution. The effect of mineral particles on the behavior of froth also was studied, and the results can be found in a separate paper.' The results also show that the relative froth-abilities of pine oils in the frothmeter generally correlate with those in actual flotation, provided that other factors are kept constant. In addition to pine oils, the other well-established flotation frothers were tested, and the results are included. In this paper, compressed air frothing is the frothing process performed by means of purified compressed air, whereas sucked air frothing is the frothing process accomplished by purified air sucked into the glass cylinder by a vacuum system. The term vacuum frothing denotes that froth was formed by degassing of the air-saturated liquid under a closed vacuum system. Apparatus The frothmeter, shown in Fig. 1, is capable of re-producibly measuring the volume and persistence of froth as well as the volume of air bubbles entrapped in the liquid and is capable of being used for compressed air frothing, sucked air frothing, and vacuum frothing. Fig. la shows that for compressed air frothing, the apparatus consists of an airflow regulating system, 1-3; a purifying and drying system, 4-8; a standardized flowmeter to measure the rate of airflow from zero to 500 cc per sec, 9; and a graduated glass cylinder, 13; equipped with an air regulating stopcock, 10; an air chamber, 11; and a fritted glass disk to produce froth, 12. The fritted glass disk, 5 cm in diam and 0.3 cm thick, has an average pore diameter of 85 to 145 microns. The pyrex glass cylinder has a uniform ID of 5.588 cm and an effective height of 63 cm. The inside cross-sectional area of the glass cylinder was calculated to be 24.53 sq cm, or 3.8 sq in. For sucked air frothing, Fig. lb shows that the apparatus for compressed air frothing is used again, with the following modifications: 1—compressed air and its regulating system, 1-3, are eliminated; and 2—a vacuum system, 16, equipped with a vapor trap, 15, and a vacuum manometer, 17, is added. The vacuum system can be either a water aspirator or a laboratory vacuum pump. Any desired rate of airflow can be drawn into the glass cylinder, 13, by adjusting the opening of the air regulating stopcock, 10. The sucked air stream is cleaned by the purifying and drying system, 4-8, before entering the glass cylinder, 13. When this setup is used for vacuum frothing, the air regulating stopcock is closed. The frothmeter has been used for almost 3 years and has proved to give reproducible results, as illustrated in Table I. With a magnifying glass and suitable illumination, the frothmeter also can be used to study the attachment of air bubbles to coarse mineral particles.' Experimental Procedures Except where otherwise stated, the data presented were established by means of the compressed air method. The volume and persistence of froth were recorded respectively at the end of 4 and 6 min of aeration at a constant rate of airflow of 29.3 cc per sec, which is equivalent to 71.6 cc per sq cm per min, or 462.6 cc per sq in. per min. The aqueous solution for each test, containing 1000 cc of distilled water and 19.2 ± 0.5 mg frothing reagent, was adjusted to a pH of 6.9 0.2. The volume of froth is expressed as cubic centimeter per square centimeter and is equivalent to the height of the froth column (the distance between the bottom and the meniscus of the froth). The volume of froth was obtained by multiplying the height of froth by the cross-sectional area of the glass cylinder, 24.53 sq cm. Before each test, the glass cylinder, 13, was cleaned thoroughly with jets of tap water, ethyl alcohol, tap water, cleaning solution, tap water, and finally distilled water. The cylinder with stopcock,

Jan 1, 1953

By E. A. Holbrook

AS A whole, engineering schools have not awakened A to the fact that the workmen compensation laws passed in most of our states between 1914 and 1917 effected a quiet but none the less real revolution in. the relations between labor and management; no longer are industrial accidents unfortunate or careless happenings over which we feel a humanitarian interest and sorrow, they are a cost of the process and the finished product, as vital as improved design and increased efficiency. Last year the writer and others made a committee report to. the American Institute of Mining and Metallurgical Engineers on the cost of accidents in the coal industry of Pennsylvania. Comparatively the accident record in Pennsylvania coal industry is not high, yet the direct compensation cost plus the interference with operation cost of accidents was over 5 per cent. of the total cost of producing the coal. This stands out more vividly -if you realize that about 70 per cent. of the' cost of producing the coal is for payment of labor, wages that are fixed and over which engineering efficiency and management skill have little or no direct effect. This leaves 30 per cent. of the cost chargeable .to hoisting, haulage, overhead 'and other items subject to engineering control. One sixth of this is due to cost of accidents. Surely a direct place 'for an engineering attack.

Jan 1, 1925

By R. E. Cole, A. M. Gaudin

OLEIC acid, a standard flotation reagent, has generally been preferred to other fatty acids. Because oleic acid differs from saturated fatty acids by the presence of one carbon-to-carbon double bond and because the flotation operation is one in which extremely intimate exposure of the reagent to oxygen is obtained, it appeared possible that the value of oleic acid as a flotation collector was related to the oxidizability of its double bond. To test this hypothesis, the floated mineral, fluor-ite, was leached with a solvent capable of extracting the adsorbed reagent and the extract was analyzed.' Results show that oleic acid is not oxidized during flotation, although some oxidation can be obtained if the flotation operation is repeated many times and if oxygen in place of air is employed as the gas during flotation. Incidentally, it was found that lino-leic acid which has two nonconjugated double bonds is not affected appreciably more than oleic acid. Linolenic acid which has three nonconjugated double bonds is measurably altered even during one flotation step, using air. The fatty acids used, from the Hormel Foundation, were of the highest purity. The quantity of fatty acids employed in each test was sufficient to float the mineral, but less than the theoretical amount required to form a monolayer at the mineral surface. The purpose of this limitation was to eliminate droplets of oil smeared on the adsorbate-covered mineral surface. The mineral was dried in vacuum at about 60 °C. Effective leaching was obtained by use of a solution of 1 pct hydrochloric acid in absolute alcohol. The extract was separated from the solvent by distillation, with final recovery of the extract in carbon tetrachloride. The identity of the extract was tested by a combination of analytical procedures including infrared spectroscopy, saponification number, iodine number, and index of refraction. At the outset, great hopes for accurate quantification of oleic acid oxidation had been entertained in regard to the method of infra-red spectroscopy. Unfortunately, because the double bond in the oleic acid is so sym- metrically located at the center of the molecule that it provides very weak absorption bands, accurate quantitative analyses were not obtained. Nevertheless, infra-red spectrograms suggested the absence of double-bond oxidation during flotation. Iodine number, semi-micro method, provided a critical test of the extent to which fatty acids oxidized during flotation, see Table I. The index of refraction was used in a qualitative rather than quantitative fashion, and its findings corroborated those obtained by the iodine-number method. It is concluded, in the case of fluorite and C-18 fatty acids having one or two nonconjugated double bonds, that there is practically no change of the fatty acid molecule or ion during the flotation operation. It would appear, therefore, that the extraordinary utility of these reagents is related to some property of the compounds other than the oxidizability of their double bonds. Acknowledgment The research reported herewith was sponsored by the Research Division, U. S. Atomic Energy Commission, and for this help the authors express their appreciation. Reference 'R. E. Cole: "Double-Bond Reactivity of Oleic Acid During Flotation." Thesis submitted in partial fulfillment of the requirements for the degree of M.S. at the Massachusetts Institute of Technology.

Jan 1, 1954

By R. A. Burmeister, G. P. Pighini, P. E. Greene

An open tube vapor phase epitaxial growth system has been used for large area (multiple substrate) growth of GaAs1-xPx on GaAs substrates. The GaCl-GaCl transport reaction is used with either a GaAs or Ga (nonsaturated) source. Selenium and tellurium have been used for donor impurities, and zinc as an acceptor. The useable substrate area in this system is approximately 20 sq cm. The uniformity of thick-ness of the epitaxial layers are typically better than ±5 pct across a given wafer. Electrical and optical measurerments indicute comparable uniformity in electrical and luminescent properties within a wufer. The application of this system to the large scale pro-duction of GaAs1-x Px for display devices, both discrete and arrays, is discussed. Typical electrical and luminescent properties of light emitting diodes fabricated front material produced by this technique are presented. THE most promising materials currently being utilized for visible injection electroluminescence are GaAs1-xPx, Ga1-xAlxAs, and Gap. All have reasonably efficient emissions in the red portion of the visible spectrum at room temperature; Gap also has an efficient green emission.' At present, GaAs1-xPx has a technological advantage over Ga1-xAlxAs and Gap for display applications, since relatively large (several sq cm) areas of GaAs1-xPx suitable for use in electroluminescent devices may be readily grown by vapor phase growth techniques. In contrast, the preparation of Gap and Ga1-xAlxAs for electroluminescent device applications generally employs solution growth techniques which are at present not well suited for the growth of large areas of uniform thickness and doping level. The capability of uniform growth over large substrate areas and the use of multiple substrates is necessary for the practical utilization of electroluminescent devices. This is particularly important when quantity production or monolithic devices are required. Furthermore, in many display applications arrays of light emitting devices are used, the individual elements of which are of a size resolvable by the unaided eye. Thus the overall dimensions of display are substantially larger than those of most semiconductor devices. It is also necessary to achieve a high degree of control over the growth parameters to attain the required degree of reproducibility of materials properties for electroluminescent devices. In the case of GaAs1-xPx it is necessary to accurately and precisely control the phosphorus content of the alloy, both on a macroscopic and microscopic scale, in addition to the parameters generally associated with epitaxial growth such as thickness and doping level. This value is critical, as it has a major effect on the performance of electroluminescent devices. This paper describes the epitaxial growth of GaAsl-xPx suitable for electroluminescent display devices using a system developed specifically for this purpose, and which contains several novel features. The results of studies of selected physical properties of the epitaxial layers are also discussed. Finally, a brief summary is given of the characteristics of display devices fabricated from GaAsl-xPx grown in this system. EXPERIMENTAL A) Reactants. A number of techniques suitable for the vapor phase epitaxial growth of GaAs1-xPx have been reported in the literature.'-' The method selected for this investigation is that in which the Ga is transported by the GaC1-GaCI3 reaction in an open tube process. The results reported here were obtained using either the combination of GaAs, AsC13, and pH3, or Ga, AsH3, pH3, and HC1 as the initial re-actants.* The ASH3 and pH3 were obtained as dilute *Several different sources of supply were used for these reactants, y~elding comparable results._____________________________________________________ mixtures in HZ; the HC1 was obtained from the reduction of AsC13 by Hz at elevated temperatures. Both selenium and tellurium were employed as donor impurities, and zinc as an acceptor impurity. Selenium was introduced in the form of H2Se, tellurium in the form of tellurium-doped GaAs, and zinc in the form of diethy1 zinc. B) Apparatus. The prinicipal difference between the apparatus used in the present study and that of Tietjen and Amick,8 in addition to size and other related design features, is that RE induction heating is utilized in place of resistance heated furnaces. Induction heating was selected for this application because it appears to have several advantages, including: 1) It is possible to keep all fused silica portions of the apparatus at temperatures well below those of the reaction zone, thus minimizing a possible source of contamination. 2) The thermal mass of an induction heated system can be made small, thus reducing the total time required for the growth process. 3) Sharp temperature profiles (desirable for high deposition efficiency) are easily achieved. 4) The volume of the system for a given substrate area can generally be made smaller than a comparable resistance heated unit. This results in shorter time

Jan 1, 1970