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By C. Norman Cochran

The pllnse diagvam for the NaF-AlF3 system was used to calcutate an ionic model for the NaF-AlF3 system. Assuming an ideal solution,a series of simultaneous equations expressing equilibria be-tween solid and liquid phases at the euleclic, perilec-tic, and melting points were solved for the activities of the ionic species, the dissociation constants, and the entropies and heats of fusion. The calculations suggest the existence of A13F1415 ions in addition to the F-1+AlF6-3 , and AlF4-4 ions previously proposed by others. The calculaled valnes give better agreement with vapor pressures than the previous model without Al3Fl14-5. Additional possible vefinements of the model are proposed. CRYOSCOPIC1 investigations and density data2 for the NaF-A1F3 system have previously been used to study the dissociation mechanism of Na3A1F6 and to derive equilibrium constants for its dissociation to NaF and NaAlF,. Depending primarily on the heat of fusion assumed for cryolite, the dissociation constants ranged between 0.02 and 0.18 from cryoscopic studies, and from 0.09 at 1273°K to 0.16 at 1363°K from density data. In most cases the values were unable to reproduce satisfactorily the experimental liquidus lines very far on the A1F3 side of the Na3A1Fe composition. This suggested the existence of at least one other ionized compound in the melt besides NaA1F4 in the Na3A1F6-A1F3 side of the system. This is assumed to be liquid Na&13F14 (chiolite), which is already established as a stable solid in phase studies of this system. MODEL FOR THE MELT The melt is assumed to be an ideal solution with ion activities equal to anion fractions. The only cation in the model is sodium so that Temkin and simple anionic activities are identical. Although the compounds are completely ionized to Na' and the respective anion in the melt, molecular rather than ionic notation is used throughout this work. The Na3A1Fe is assumed to dissociate to NaA1F4 and NaF as in the former model, and Na&13F14 to dissociate to Na3A1Fe and NaA1F4. Other valid dissociation equilibria can be written involving these four compounds, but all of these can be obtained by combinations of the two described dissociation reactions and, thus, are automatically considered in these calculations. The model allows for no free AlF3 so that compositions for NAIF3 > 0.5 (mole fraction A1F3 on the NaF-A1F3 basis) cannot be treated. The question of the existence of free AlF3 in the melt will be discussed again later. The constants in the model were evaluated from points along the entire known liquidus line of the NaF-A1F3 system. Previous work employed only the liquidus line or densi- ties near the Na3A1F, composition. The liquidus line compositions used in the solution of the model are from unpublished work by Mr. P. A. Foster, Jr., for compositions between the Na3A1F6 melting point and the Na&13F14-A1F3 eutectic, and from the published works of Grjotheim,1 Phillips,3 and Foster4 for the remainder of the system. The relationships used in solving for the desired dissociation constants and heats and entropies of fusion are listed in Table I, and the points along the liquidus line at which each apply are indicated to the right of the relationships. The mole fractions of each of the separate species in the melt are symbolized by N. Relationships [I] and [2] are the respective dissocia-ation constants, Kl and K2, of Na3AIF6 and Na5A13F14 for this model. For simplicity, these constants will be assumed to be independent of temperature. Relationship [3] follows from the assumption of the ideal solution. The expression relating the values of N to the experimental values of NAIf3, is given in Relationship (41. Relationships [5], [6], and [7] each state the equilibrium between a compound in the melt and its pure solid phase for the portion of the liquidus lines where it precipitates. The heats of melting, AH,, and entropies of melting, AS,, used in [5], [6], and [7] are assumed to be independent of temperature. The compositions and temperatures of all five invariant points (two melting points, two eutectics, and one peritectic) along the liquidus lines from NAIF3 = 0 to NAIF3 = 0.5 were employed in the solution. The eutectic and peritectic compositions were particularly useful because each of these is involved in one more equation than other points along the liquidus lines and thus reduces the number of points required to solve for the constants. Also, their use assures that the inflection points in the derived liquidus line will correspond exactly with those on the experimental liquidus line. The total number of equations is 5k1 — 1, where n is the number of experimental composition points used. The number of unknowns is 4n + 5 (4n- 3 values of N, 3 values each of AH, and AS,, and 2 values of K). Thus, six points must be used in the solution to obtain an equal number of equations and unknowns. The one additional required experimental composition was taken on the liquidus line between the Na3A1Fe melting point and the Na3A1F6-Na5A13F14 peritectic. Previous work indicated this was a difficult portion of the curve to fit. The temperature used for the point was 1161°K, the same as for the NaF-Na3A1Fe eutectic. This choice of temperature gave two points with identical NNa3AIF6 values which simplifies the algebraic solution. The second point at this temperature is denoted 1161°'K. PROCEDURE FOR SOLUTION OF EQUATIONS Values were assumed for NNa,AIF and NNaF at the NaF-Na3A1F6 eutectic at 1161°k. By an iterative procedure, the corresponding values for NNa5A13F14 and NNaAlF4 at 1161°K were determined from 131 and 141. A value was assumed for NNaAlF4 at 1161°'K and

Jan 1, 1968

By F. V. Lenel, G. S. Ansell, M. J. Salkind

An experiment is described in which the growth of interparticle necks in an array of loose spherical silver powder at temperatures near 300°C was determined by measuring changes in the electrical resistance of the array. The activation energy for neck growth of contacts was derived by abruptly changing temperature and noting the change in the rate of neck growth. Since the experiments were run under an external load, the changes in activation energy with stress could he determined. The activation energy was found to decrease rapidly with increasing stress. It is concluded that the material transport in the experiments is one of plastic flow by dislocation motion. The variation of activation energy with stress is typical for cross slip of dislocations, an important material transport mechanism in the temperature range investigated. THE process in which powder compacts or aggregates of loose powder are held at an elevated temperature under an external load is called hot pressing or sintering under pressure by powder metallurgists. In this investigation the early stages of this process as applied to loose spherical silver- powder aggregates were studied. The powder particles were approximately 100µ in diameter and the temperature was near 300°C, i.e., below one half of the melting point of silver in degrees Kelvin, where volume diffusion is not expected to contribute to sintering. In the process, the contact or neck areas between powder particles grow. Since this involves plastic deformation of the particles under a constant external load (even though not under constant stress) it would be termed creep by mechanical metallurgists. On the other hand, the growth in neck area observed in compacts or loose-powder aggregates held at elevated temperature without the application of an external load is termed sintering by powder metallurgists. During sintering the major driving force is the stress due to surface tension. However, even when no load is placed on the compact or powder aggregate, an external stress, i.e., gravity, plays an important role in sintering in addition to those stresses arising from surface tension, as was shown in two previous investigations.'" It is therefore postulated that no sharp dividing line can be drawn between the phenomena of "creep" and "sintering". Different material transport mechanisms may be involved in either of these phenomena, but they will depend upon the temperature and the level of stress, but not necessarily upon the nature of the driving force: surface tension or external load. At the low temperatures of this investigation, an external stress much higher than the stress due to surface tension is necessary to obtain measurable rates of neck growth. In order to avoid misunderstanding this phenomenon will be called "creep". The rate of growth in contact area in the loose silver-powder aggregates was determined by meas-

Jan 1, 1965

By T. K. Perkins, W. W. Krech

Jan 1, 1969

By John V. Beall

BROMO Seltzer blue has gone to war. The blue of the Bromo Seltzer bottle is a product of cobalt, the Nation's No. 1 strategic metal. When the National Production Authority, on Nov. 21, 1950, ordered a 70 pct cutback in domestic use of cobalt, a stab of pain was felt in the hearts of the glass, porcelain enamel, steel, paint, pottery, and electrical and electronic equipment industries. The reason: A full-scale wartime economy with astronomical requirements for jet engines, high velocity projectiles, armor plate, electronic equipment, and the many products needed to win a war. There is little potential comfort for cobalt users in nonessential manufacturing, and the military will be pinched for optimum supplies of the metal. However, if proper measures are taken immediately and current plans are completed, in two years there will be far more cobalt available than ever before. When normal times return, cobalt supplies should be sufficient to meet peacetime military requirements, and greatly expanded domestic requirements that will result from new technological development for wartime but adaptable to peacetime products. The pres-

Jan 1, 1951

By Edmund C. Pechin

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

Jan 1, 1891

By J. H. Brophy

Experimental evidence in recent years shows that nickel coated hydrogen reduced tungsten powder can be sintered to 98 pct of theoretical density at 1100°C. New data indicate that the sintering rate is the same for nickel contents ranging from 0.125 wt pct (mon-atomic layer) to 5.0 wt pct Ni coated on 0.561. tungsten powder. Nickel tungsten made by coreduction from oxides sinters in a kinetically similar way, but the rate tends to increase with higher nickel contents. The activation of sintering can be accomplished with a minimum amount of nickel if coated powder is used. Transverse rmpture strength was found to increase in specimens containing 0.25 pct Ni as density increased during the initial stage of the carrier-phase sintering process. Upon the onset of grain growth in the final stage, strength was found to decrease. With increasing nickel contents up to 4 pct, strength increased. Maximum strengths in three-point loading were observed at 73,000 psi for 0.25 pct Ni and 93,000 psi for 5 pct Ni. These were comparable to that of massive tungsten recrystal-lized in the presence of nickel and tested in the same way. The results were sensitive to the mode of powder treatment and ductility was negligible in all cases. The study and application of sintered bodies of nickel and tungsten is not new; however, the analysis of the mechanism by which small additions of nickel increase the sintering rate of tungsten promises to Contribute new information regarding sintering theory in general. Initial experimental evidence was presented by the authors showing that nickel-coated hydrogen-reduced tungsten powder may be sintered to 98 pct of theoretical density at 1100°C in 16 hr.' Simultaneously, a kinetic analysis of the process showed that it took place in two distinct stages. In the first stage, nickel evidently served as a carrier phase through which tungsten atoms could move. This stage was kinetically similar to the 'solution-precipitationo step postulated when the carrier phase is liquid3 although in the nickel tungsten case, there is no evidence of the existence of a liquid phase either in equilibrium phase relationships or in mi-crostructures at the temperatures under consideration. In the present work, new data for nickel-coated tungsten powder are offered in support of the proposed mechanism, and a more explicit study of the second stage of densification is presented. Concurrently, the sintering kinetics of these coated powders are compared to Ni-W powder made by coreduction of oxides. In this way the present work can be compared to earlier results in nickel activated sintering of tungsten in which the coreduction process was emplyed. The ultimate utility of such an activated sintering process will be determined to some extent by the mechanical and physical properties of the final prod-

Jan 1, 1962

DAVID COLE, El Paso, Tex. (communication to the Secretary*).-I notice that Mr. Callow takes issue with me on certain points I have previously contributed to the Transactions, to which I would reply," follows: Regarding Inspiration: Mr. Callow's refinements of gravity methods made just prior to the advent of flotation in the Southwest were intended to be "down to the minute," and the gravity flow sheet for Inspiration ores which he brought out at that time as the result of his long campaign of experimentation was regarded by many as the last word in wet gravity work. It was not my intention to discredit this good work when I said "he threw small light on slime treatment." "Minus 200 mesh," however, is not-synonymous with "real slime." Repeated treatments by gravity methods will result in the separation of a very large percentage of the fine granular sulphides in sizes much finer than 200 mesh, and I gave him due credit for that. The unavoidable losses were made in the "real" slime which I mentioned in the paragraph which Mr. Callow refers to as my "statements on page 1871," and his refinements were not a solution to the real slime problem. Mr. Callow has called attention to the fact that his best results at. Inspiration in gravity work were obtained on Joe Bush ore and he presents a table, viz., Tests Nos. 68, 71, and 72; and asks us to consider and compare these results, made by his refined gravity methods, with the results obtained by 'flotation methods in the new mill "during the second half of 1915 and in August, 1916." Of course, the ore treated in the mill was what happened to come. It was not Joe Bush ore, and therefore comparisons of detail figures are of no value. In regard to Mr. Callow's statements under the caption "Callow Cells Adopted by Arizona Copper Company," I would say that those who have been sufficiently interested to read my paper and' his remarks will notice what amounts to contradictory statements on several points which I cannot allow to go unchallenged. I was on the ground constantly and got my information at first hand. The tables published were the official ones. Mr. Callow was not present during the period and has been laboring under that disadvantage.

Jan 5, 1917

By J. J. Taber, W. K. Meyer

Experiments on consolidated sandstones have shown that a variety of conditions are responsible for the wide range of behavior observed when oil and water are displaced simultaneously by a solvent which is miscible with both. The type of displacement is influenced most strongly by the relation between the plait point of the ternary phase diagram and the composition path followed by the system as it achieves mis-cibility. Neglecting viscosity, the displacement becomes less efficient as the distance between the composition path and plait point is increased in either direction so that a very wide spectrum of displacements is possible with different alcohol, oil and brine systems. It is possible by choosing various composition paths as miscibility is achieved to exercise some control over the actual displacement mechanism. Control over the composition path is exercised by adding oil or water in specific amounts to the alcohol prior to its injection into the porous medium. This technique apparently makes it possible to obtain piston-like displacements with systems which are usually characterized by the efficient displacement of only one of the two phases i.e., either oil or water, while the other phase lags behind. However, the simultaneous displacement of oil and water is not as efficient as other miscible displacements at a similar mobility ratio. The evidence indicates that both oil and water "leak" into the alcohol "piston" in compensating amounts. With oils of low viscosities the displacement is inefficient because the low oil saturation in the stabilized bank causes oil to be trapped by water before miscibility is attained. INTRODUCTION The simultaneous displacement of oil and water by solvents such as alcohol has been investigated in the laboratory and in the field. The laboratorv workers investigating all-liquid miscible systems have recognized the great importance that the nature of the traingular phase diagram exerts on the efficiency of the miscible displacement. Gatlin and Slobod pointed out that displacement efficiency will be improved if miscibility can be retained for long periods and that this behavior tends to be followed if the applicable phase diagrams have very low binodal curves. In their unconsolidated sand tests the alcohol was considered an ideal miscible piston displacing both oil and water phases. Later workers have pointed out that an important feature of the phase diagram as far as oil recovery is concerned is the location of the plait point. This is particularly true in the case of consolidated Sandstone.3 Since the original discussion of this effect, the importance of plait-point location has been confirmed and discussed by other author The early workers394 recognized that the position of the plait point could be altered by changing the oil or the alcohol used in an experiment. In addition, recent work has demonstrated that the plait point can be shifted by altering the nature and concentration of dissolved salts in the aqueous phase. However, the entire scope of the relationship between displacement and plait point has not been discussed previously and a technique for changing the composition path as miscibility is achieved in a particular ternary system, i.e., oil, water and solvent, has not been demonstrated. * The importance of oil viscosity on the efficiency of oil displacement by alcohol has not previously been observed, probably because the range of viscosities used in earlier experiments was too restricted. It is the object of this paper to describe the relationships between the ternary phase diagram, fluid properties and the displacement achieved. A technique for controlling the nature of the displacement is also presented. THEORY AND DEFINITIONS PISTON-LIKE THEORY The theory of alcohol flooding has been discussed in some detail.2-4 The concept was advanced that

Jan 1, 1965

CONTENTS PAGE. WHITE, DAVID.-Environmental Conditions of Deposition of Coal. Discussed by E. C. Jeffrey, George H. Ashley, Reinhardt Thiessen, S. W. Parr, David B. Reger, Wilbur A. Nelson, James F. Kemp, E. S. Moore, Homer G. Turner, David White, A. C. Noé, W. A. I. M. van Waterschoot van der Gracht 2 THIESSEN, REINHARDT.-The Constitution of Coal. Discussed by Edward C. Jeffrey, Reinhardt Thiessen, Ralph H. Sweetser, David White 12 TURNER, HOMER G.-Microscopical Structure of Anthracite. Discussed by E. S. Moore, Edward C. Jeffrey, Reinhardt Thiessen, H. J. Rose, James F. Kemp, David White, Clarence A. Seyler, A. C. Noé 14 JEFFREY, EDWARD C.-Coal in Relation to Coke. Discussed by H. J. Rose, David White, E. S. Sinkinson, S. W. Parr, James F. Kemp, Edward C. Jeffrey, Reinhardt Thiessen, Chas. R. Fettke 17 FRANCIS, W., and WHEELER, R. V.-The Resolution of Coal by Oxidation. Discussed by Edward C. Jeffrey, S. W. Parr, E. S. Sinkinson, Reinhardt Thiessen, David White 23 TIDESWELL, F. V., and WHEELER, R. V.-The Constitution of Coal. Discussed by David White, A. C. Fieldner 24 JOLLY, J., and WHEELER, R. V.-Organic Sulfur Compounds in Coal. Discussed by S. W. Parr 25 SINNATT, F. S.-Selective Combustion in Coal. Discussed by J. D. Davis, A. C. Fieldner, Geo. S. Rice, W. M. Grant, H. J. Rose, S. W. Parr, David White 25 COBB, JOHN W.-Nitrogenous Constituents of Coal. Discussed by S. W. Parr, H. J. Rose, Reinhardt Thiessen 28 PARR, S. W., and HOBART, F. B.-Coal and Oxygen. Discussed by J. D. Davis, W. T. Thorm, Jr., S. W. Parr, H. J. Rose, A. C. Fieldner, F. F. Jorgensen, David White, W. M. Grant 30 FIELDNER, A. C., and DAVIS, J. D.-Modern Views of Chemistry of Coals of Different Ranks as Conglomerates. Discussed by S. W. Parr, David White, Reinhardt Thiessen, A. C. Fieldner, Clarence A. Seyler 32 EBY, J. BRIAN.-Contact Metamorphism of Some Colorado Coals. Discussed by Geo. C. McFarlane, W. T. Thom, Jr 35 WHITE, DAVID.-Progressive Regional Carbonization of Coals. Discussed by A. C. Fieldner, Homer G. Turner, W. A. J. M. van Waterschoot van der Gracht, A. C. Noé 37 THOM, W. T., JR.-Moisture as a Component of the Volatile Matter of Coal. Discussed by A. C. Fieldner, S. W. Parr, Clarence A. Seyler, W. T. Thom, Jr., R. D. Hall 39

Jan 7, 1925

By J. J. Stokes

Literature on the electrolysis of aluminum from cryolite melts and on the structure of these melts is surveyed critically. Data on density, freezing point, and other properties are reviewed. Theories of the electrolysis are examined in the light of these data. Two theories are presented which account equally well for the observations. ALTHOUGH the production of aluminum is a large-scale industrial process, consuming approximately 3 pet of all of the electric current generated in this country, the mechanism of the Hall Process remains a 70-year-old mystery. It is a remarkable fact that the aluminum industry, which was established largely through research and owes much of its growth to research, still employs as its basic process the one developed by Charles Martin Hall while he was still a young man working in a woodshed. There are, of course, modifications in detail and a tremendous expansion of the size of the units used, but basically the process employs carbon anodes and a carbon-lined iron vessel as a cathode for the electrolysis of alumina dissolved in molten salt. Of the almost infinite variety of salts available, the relatively minor Greenland mineral, cryolite, 3NaF.A1F3, is still the only one which gives good performance in the electrolysis. In the early days, the process was thought of as a simple one. The dissolved alumina dissociated and, during the electrolysis, the aluminum was carried to the cathode where it was discharged and collected in a pool of metal. The oxygen was carried to the carbon anode where it reacted to form primarily carbon dioxide together with some carbon monoxide. About the only virtue that can be claimed for this hypothesis is that of simplicity. The actual mechanisms must be tremendously more complex. This paper is devoted to a rather narrow part of the whole subject, namely, what ions are present in the bath, and by what mechanism the current is carried. The complexity of the literature on this system is demonstrated in Table I, which shows the ions postulated as being present during the process. This system is not easy to investigate. Cryolite melts at about 1000°C, so that all the investigations are at relatively high temperatures. Molten cryolite fumes in air, particularly if excess aluminum fluoride is present. The cryolite changes composition on heating at 1000°C, principally by reaction with moisture in the air, but apparently also by reaction with oxygen. Cryolite reacts with most of the customary materials of construction, and those that are not attacked by cryolite seem inevitably to react with molten aluminum. Graphite is the only common material that is inert to the electrolytic bath. Pure cryolite can be held in platinum. There is hope that some of the newer refractories will stand up in bath, and their development for this purpose would be a major advance in the field. The techniques to be discussed, then, are not the most advanced ones. Rather, they are examples of old standardized methods applied under difficult conditions. The principal methods that shed real light on the mechanism are density, electrical conductivity, freezing-point lowering, transport number, viscosity measurements, and reactivity of bath with carbon dioxide. The first measurement to be discussed is density. This procedure is relatively straightforward. A hollow platinum bob is suspended by fine platinum wire from an analytical balance into the melt being investigated. Density1-4 of the system sodium fluoride-aluminum fluoride is shown in Fig. 1. There is a maximum in the density near the cryolite composition, but actually the maximum is on the NaF-rich side of cryolite, close to the composition NaF - Na3AlF8. Density measurements are also useful in giving a clue to the nature of cryolite-alumina melts.1, 4 On the first addition of alumina, density decreases, Fig. 2, although the density of alumina, either solid or liquid, is higher than that of cryolite. These density results indicate that the systems are not simple. A great deal of effort has been spent in measuring the electrical conductivity of molten cryolite and of cryolite with various additives. Conductivity measurements are quite easy for fused salts that can be measured in a dip cell, but no successful dip cell has been made available yet for cryolite. Recourse is had

Jan 1, 1959

By Harlan W. Nelson, James B. Purdy

A study of data obtained during laboratory tests to determine the suitability of bituminous coals for use in residential underfeed stokers of the clinkering type has led to the following general conclusions: 1. Performance data obtained during the test furnish useful and practical information upon which to judge the performance of stoker coals. 2. Conclusions derived from the results of evaluation tests are in general agreement with use experience of the coals in the field. The method is of practical use in this regard. 3. Few direct relationships were found between data furnished by the evaluation test and determinations by standard laboratory tests. This is particularly true with regard to coke formation and clinker formation, two of the most important factors in determining the degree of satisfaction to be obtained in applications of the small underfeed stoker. It has not been the intention in this paper to prescribe this evaluation test as the best method for the evaluation of coals for use in residential stokers. That there are other test methods having similar objectives serves to point out the necessity for full-scale laboratory tests. At the present time, a standard test procedure for the evaluation of coals for use in residential stokers is not available. For the past several years a joint committee, appointed from the membership of the Residential Stoker Committee of Bitulninous Coal Research, Inc., and from the Engineer- ing and Research Committee of The Stoker Manufacturers Association, has been working to develop a standard procedure for testing and evaluating bituminous stoker coals. This procedure has been completed to the extent that it has been drawn up in tentative form. It is now planned to install the equipment in several laboratories and to run check tests, using portions of identical lots of coal, to determine the degree of reproducibility offered by the method. Completion of this standard test procedure should greatly facilitate the evaluation of coals for use in residential stokers. Acknowledgments The cooperation of coal operators sponsoring the coal evaluation tests, in granting permission to use data and results from their tests, is gratefully acknowledged. Acknowledgment is also made to Carroll F. Hardy, Chief Engineer, Appalachian Coals, Inc., for his interest and timely suggestions on the preparation of this paper. Special thanks are due to Ralph Sherman, Assistant Director, Battelle Memorial Institute, who was largely responsible for development of the evaluation procedure, for helpful suggestions and advice. References I. H. A. Sherman: The Evaluation of Coal for Use in Domestic Stokers. Univ. of Ill., Eng. Experiment Station, Circular No. 39 (1939). 2. . Q. Shotts: The Relation of Free- swelling Indexes to Other Characteristics of Some Alabama Domestic Stoker Coals. TP 2314, Coal Tech., (Feb. 1948); Trans. AIME (1948) 177, 502. 3. . J. Helfinstine and C. C. Boley: Correlation of Domestic Stoker Combustion with Laboratory Tests and Types of Fuels 11. Combustion Tests and Preparation Studies of Representative Illinois Coals. Ill. State Geol. Survey, Re1. of Zntlestigations No. 120 (19467 ) p. 35. DISCUSSION E. R. Kaiser*—AS a former fuel engineer assigned to residential stokers at Battelle, the writer has read with considerable interest the paper by Messrs. I'urdy and Nelson. It is gratifying to note that earlier test techniques have been developed and that criteria found important in the years 1935 to 1938 are still important in judging the performance of stoker coals for residential heating. The authors have plotted a number of the primary coal data singly against performance data of the stoker in an effort to establish relationships. Unfortunately, wide scattering of points usually resulted, which did not illustrate what experience generally indicates to be the case. For example, Fig 3 indicates almost no trend in the percentage of released ash converted to clinker with change in ash-softening temperature. Other factors, such as fuel bed temperatures and zones of heat release must have influenced the results. In the present state of our knowledge, we cannot explain all of the reasons why suitable stoker coals perform satisfactorily, nor why one satisfactory coal may be better than another. It would therefore

Jan 1, 1950

By Howard N. Eavenson

WASTE of coal, or perhaps more properly the percentage of its recovery in mining, has keenly interested me during an experience of over a half century in coal mining. In the early part of that time and until a few ears after World War I the use of better mining plans and supervision resulted in an increased recovery. Since then, and particularly since controlled prices have been effective and mechanized mining has been extensively practiced, the tendency has all been toward lesser recovery in mining. The purpose of this paper is not to criticize the methods being used, which after all are the result of economic forces, nor to point to any particular mining method or to any locality where the best recovery is obtained. but to call attention to the tremendous waste of our national coal resources that is constantly continuing. A possible method of reducing this loss will be suggested. but without any illusions that it will be followed or that much attention will be paid to it.

Jan 1, 1946

By W. B. HILLHOUSE

AN excerpt from the Alabama State Mining Law, pertaining to, transporting men' into and out of the mines, reads as follows: "A trip of empty cars may be operated for the purpose of taking employees into and out of the mine, where the distance to and from their work exceeds one mile." The State Mining Department of Alabama includes in its inspection the transportation of men into and out of the mines, also studying and noting improvements, or progress made, that would tend to create a greater assurance of safety in this practice. Everyone is familiar with the original safety methods employed in man-trip transportation, such as passing a rope around the trip of cars, or through the cars, fastened in the conventional manner, and with the usual "clog," commonly called a drag, on the rear end. Also there is a more advanced method of transporting men, such as the double-rope system, which is feasible on slopes used exclusively for this purpose, and is very satisfactory. However, for the past eighteen months; the Republic Steel Corp. and the Tennessee Coal, Iron & Railroad Co. have adopted a practice that shows

Jan 1, 1935

By William Rawles

THIS report is the first of a series planned by The Mineral Inquiry, organized by the American Institute of Mining and Metallurgical Engineers to make factual studies of the world's mineral resources in their political and international relations. The efforts of The Inquiry are directed toward filling certain notable gaps in available information, without duplication of many other investigations touching this field which" are being conducted by other organizations, public and private. Much of its work is indirect-suggesting topics for study by other individuals and organizations and aiding in their planning and correlation. The present report is designed to show the nationality of the commercial control of mineral resources, in addition to the geographic distribution of production by nation-in other words, the overlapping of political and commercial control. Detailed accuracy cannot be claimed for the figures presented. For some companies division of ownership by nationality has been very difficult to ascertain, as many companies are reluctant to dis-close the extent of their holdings in other corporations, and the impossi-bility of tracing all stock ownership is obvious. Also there are frequent changes in the distribution of stock control. The percentages given rep-resent only the participation that has been identified definitely, even though it is known in some cases with fair certainty that larger interests exist, as, for instance, American participation in foreign chromite companies. In bringing' together these figures we have had the cordial co-operation of the United States Bureau of Mines, the United States Geologi-cal Survey, the Mineral Division of the Bureau of Foreign and Domestic Commerce, the Brookings Institution, and of many specialists connected with the mineral industries covered. The report does not cover the entire list of minerals. Coal, although it is one of the most important minerals, was omitted because not more. than one or two per cent of the world's production comes from mines that are owned by companies foreign to the countries where the coal is produced. Others, such as gold, are omitted because sufficient data have not yet been accumulated. It is hoped that some of these may be covered in subsequent reports. It is not our purpose here to discuss the significance of the figures sub-mitted, but only to point out the general nature of the problems on which they have a bearing.

Jan 1, 1933

By R. Simon, D. J. Graue

This paper presents correlations for predicting the solu-lility, swelling and viscosity behavior of CO2-crude oil sys8i.m~. The correlations were developed from experimental data obtained by the authors. These data are also presented. The data were determined by measuring the properties of mixtures of CO, and nine different oils. Experiinental conditions covered a range of 100 to 250°F and pressures up to 2,300 psia. Properties predicted by the correlations have average deviations, expressed as per cent of experimental value, of 2 per cent for solubility, 0.5 per cent for swelling and 12 per cent for viscosity. INTRODUCTION Interest in CO2 injection as an oil recovery process has led to the development of performance prediction methods which can be applied to specific reservoirs.1 iS To use these performance prediction methods, it is necessary to know the solubility, swelling and viscosity properties of CO2-crude oil mixtures at reservoir conditions. Some information on these properties has appeared in the literature; however, this information did not cover the range of different oils and conditions needed to prepare generalized correlations for reservoir engineering purposes. Consequently, an experimental program was undertaken to collect the data needed. The data obtained and the correlations developed from the data are described in the following sections of this paper. SOLUBILITY OF CO2 IN CRUDE OILS CO2 solubility data in the literature come from six principal sources. The solubility prediction method of Welker and Dunlop3 is limited to 80F. The information in Ref. 4 is of two types: the first includes binary and ternary mixtures of CO, and light hydrocarbons (C1 to C6), and the second gives data for CO1 and heavy hydrocarbons for a temperature range of 40 to 90F. Ref. 5 contains a KCO2 chart for systems whose convergence pressure is 4,000 psia. The KCO2's are based mainly on CO2-natural gas mixtures. Poettmann's work covered CO2 solubility in one condensate and one crude oil6,7 Ja-coby and Rzasa measured CO? solubilities as a function of pressure and temperature for two natural gas-absorber oil mixtures and two natural gas-crude oil mixtures.'8 CO, concentration in these four systems was fixed at 5 mol per cent. The work reported in this paper extends CO, solubility data to a variety of different crude oil types in a temperature range from 110 to 250F and pressures up to 2,300 psia. The experimental procedure used by the authors to obtain the solubility data consisted of combining known amounts of pure CO, and crude oil in a visual cell at a fixed temperature and measuring the bubble point of the mixture. Measurements were made for a total of 40 different CO2-oil mixtures and the results are shown in Table 2. The mixtures included nine different oils (seven crude oils and two refined oils) whose properties are listed in Table 1. All nine oils had vapor pressures less than 1 atm at the experimental temperatures. Consequently, analysis of the bubble-point vapor showed a CO, concentration over 99 mol per cent. At no time during these experiments was a second, more dense, liquid phase observed. The solubility correlation which was developed from the data in Table 2 is presented in Figs. 1, 2 and 3. In these figures, solubility is expressed as xco2 the mol fraction of CO, in the CO2-oil mixture. Fig. 1 shows solubility as a function of CO2 fugacity6 and temperature. Fig. 2 shows the same solubility data expressed as a function of saturation pressure and temperature. The solubility shown in Figs. 1 and 2 is for an oil whose UOP characterization factor is 11.7. UOP characterization factors of crude oils can be determined from Ref. 10 if the viscosity and APT gravity of the oil are known. Fig. 3 gives the solubility correction factor for oils whose UOP characterization factors differ from 11.7. The solubility correlation in Figs. 1, 2 and 3 predicted

Jan 1, 1966

By Leo Dana

INTRODUCTION THE object of this paper is to discuss the factors and conditions that affect the observed values of the melting points of refractory materials and to describe practical methods for the determination of these points. While it appeared to be necessary to discuss some of the general properties of silicates and refractories, these subjects have been entered into only in so far as they relate to the melting point and its determination. Refractory materials such as fireclays, firebricks, and minerals generally, may be considered to be composed of compounds of metallic oxides, solid solutions of the oxides, the pure oxides, or mixtures of the three classes together with small amounts of a variety of chemical compounds. The oxides of silica and alumina occur most commonly in refractory materials; in combination with. these, oxides of the alkali earth, the alkali, the iron group, and the rare earth metals are frequently found.

Jan 9, 1919

By Dell P. Williams, Howard G. Nelson

The tensile behavior of magnesium single crystals at a temperature of 26º ± 2ºC was investigated at varying pressure levels from 760 to 8 X 10-8 tow. For crystals deformed at a constant linear strain rate of 0.061 min-1. there was no apparent effect of the vacuum environment down to 10-8 torr. However, from a vacuum of 10-5 torr down to the lowest pressure attained (8 x 10-8 tor,), the effect of the vacuum environment was to increase the strain at the end of the first linear (or easy-glide) stage and to decrease the slope of this stage; the magnitude of this effect was found to be dependent on pressure. The slope of the second linear stage was also decreased at the lower pressure levels; however, this effect appears to be caused primarity by the vacuum effect on the first linear stage. The magnitude of the vacuum-environmrnt effect was also found to be dependent upon strain rate. The reduction in flow stress at 5 x 10-8 torr, as compared to the stress in air, was obserced to be about 10 pct for a strain rate of 0.0250 min-' and 70 pct for a strain rate of 0.67 min-1. No systematic effect of pressure on the critical resolvled shear stress was observed. The data interpreted in terms of a modified form of Mott's work-hardening mechanism for hexagonal metals. It has long been known that surface conditions influence the mechanical behavior of materials. Roscoe 1 demonstrated the importance of surface conditions on mechanical behavior by testing cadmium crystals with oxide layers. He found that the "apparent" critical resolved shear stress for cadmium was increased approximately 2.5 times by the presence of an oxide layer 1000 atoms thick. The magnitude of this effect was dependent on film thickness with crystals having films less than 20 atoms thick still showing a definite increase. This observed strengthening could not be attributed to any strength of the oxide film because of 1) the thinness of the films and 2) an observed increase in the flow stress as deformation proceeded. Harper and cottrel12 obtained similar results on zinc crystals which had been etched and steamed to give artificially thick oxide films. However, in the course of this study, they also carefully examined the very early stages of plastic flow for zinc crystals which in one case had been electrolytically polished and in the other had been lightly etched to produce a thin film. They then found that the critical resolved shear stress for both surface treatments of the crystals was actually identical but that the etched crystal exhibited a much more rapid initial hardening rate. This had not been noted previously. This result indicated that, in fact, the film caused an increase in the stress for continuation of slip, rather than for the initiation of slip. Lipsett and King3 investigated the effect of evaporated gold films on the plastic behavior of cadmium single crystals. For large angles (=75 deg) between the specimen axis and the normal to the slip plane, they found that the stress-strain curve of the coated specimen always lies above that for a clean specimen. The shear strain at the end of the first linear stage was greater in clean specimens than in coated specimens and the slope of the second linear stage was

Jan 1, 1965

By R. E. Mussler, F. E. Block, T. T. Campbell

An exploratovy study was made to deternzine the feasibility of preparing beryllium by the metallother-. mic reduction of beryllium oxide. The procedure involved heating a relatively nonvolatile metal reductant in contact with beryllium oxide in a vacuum. Beryllium vapors formed in the reaction were condensed as a coherent deposit on a heated surface. Reductants tested included tanthanun, yttrium, thorium, Th-Mg, and Zr- Ti alloys, and the hydrides of lanthaniir~z, yttriunz, and zirconiur?7,. Test ten7pevatures ranged from 1350'to 175O' C, and reaction times ranged frot 30 to 100 lzr. In most cases metal recoveries were lola, although yields close to 90 pct of theoretical were obtained with latzthanum, yttrium, and zirconium reductants. In most cases metal deposits were contanzinated by beryllides, /ls/cally of the Beln M or Bel3 M type. BERYLLIUM has a variety of unique properties including light weight (sp gr 1.85), low thermal neutron absorption cross section, high scattering cross section, excellent dimensional stability, high strength to weight ratio, high melting point (1285"C), high specific heat, and high thermal conductivity. Interest in beryllium as a structural material in aerospace and nuclear-reactor applications is based on these properties. In general, the potential of beryllium has been only partially realized, largely because of the brittleness of poly crystalline forms of beryllium, difficulties associated in its fabrication, and joining problems encountered in its use in structural applications. Several excellent books and monographs are available to those interested in the occurrence, extractive metallurgy, and utilization of beryllium.1"* Although an extensive amount of research on beryllium has been in progress during the past 10 years, much of the work has been concerned either with the so-called "ductility problem" or with the development of methods of fabrication and evaluation of properties of various commercial or purified grades of metal. A recent survey of the literature indicates that only limited efforts are presently being directed toward developing new methods for reducing beryllium compounds to metal. Two major commercial methods now used to produce beryllium are the magnesium reduction of beryllium fluoride and e lec trow inn ing of beryllium from fused sodium chloride-beryllium chloride salt baths. Only a limited amount of work has been done on the direct reduction of beryllium oxide. Major factors which complicate this method are the great stability of beryllium oxide and the reactive nature of beryllium metal. The stability of the oxide necessitates extremely high reduction temperatures and vacuum operation to liberate beryllium metal vapor and cause reactions of the following type to proceed: XBeO(s) +YM(s)-MYOX(s) + XBe(& As early as 1939, roll' used this reaction for the direct reduction of beryllia by zirconium and titanium, and later in 1952 ~a~el~ studied the reduction of beryl-

Jan 1, 1967

SAN FRANCISCO SECTION W. H. SHOCKLEY, Chairman, PRANK H. PROBERT, Vice-Chairman, T. A. RICHARD, Sec.-Treas., 420 Market St., San Francisco, Cal. C. C. BRAYTON, J. F. NEWSOM. The San Francisco Section met on September 11 to discuss the problem of Labor in its Relation to the Mining Engineer. Mr. W. H. Shockley was in the chair. T. A. Rickard opened the discussion under four heads: The recognition of the union, the rustling-card, the sliding scale of wages, and the' contract system. He expressed his belief that collective bargaining cannot be ignored, and insisted that the mining company represented a collective bargaining of its shareholders with the men. employed in its mine. He held that the contract system was often used unfairly, but that used fairly it was the best check on labor tyranny. The rustling-card he held to be right in principle, in so far as it gave the employer the choice of employees, but he believed that it was often used in an irritating way to black-list refractory laborers. The sliding scale of wages was easy to establish in prosperous times, but it would inevitably lead to trouble when conditions went against the miner. His conclusion was that the quarrels of labor and capital were due mainly to a lack of the sense of fair play and of social justice. Albert Burch agreed with most of the foregoing, and insisted that 90 per cent. of the men were inclined to be just, but that the 10 per cent: made all the trouble. He stated that he had introduced the rustling-card in the Coeur d'Alene in 1899, as a means for getting rid of agitators. E. L. Foucar considered that labor was irresponsible. He described his experience in Peru, where the authorities promptly stopped a strike of Italian miners by threatening prompt punishment for any display of violence. Morton Webber also gave a bit of his own experience, to show that the chief trouble is that the men do not think for themselves, and are therefore easily led by fomenters of trouble. F. H. Probert described his experiences in Germany and. also in Arizona, and insisted that too often the men were not given a fair hearing. E. T. Blake argued that a manager must get the workmen's point of view, in order to control them effectively. He believed that young men who started life doing manual labor were in a better position to understand their fellow workers. George J. Young suggested that the mine owners should encourage the good men to lead the unions, and not leave the direction of the unions to the noisy element.

Jan 12, 1917

By Sylvan Z. Beer

The factors that determine the yield and crystal size in the two-temperature synthesis of A lp were examined. Low yields and small crystals were associated with low temperatures and pressure. Attempts to grow large crystals in the critical and supercritical region of phosphorus were unsuccessful. Crystal size increases markedly at elevated temperatures. Crystals grown at temperatures as high as 1450° C fluo-resced, under uv excitation, at energies close to the estimated band gap of about 2.4 ev, while crystals grown at lower temperatures tended to fluoresce in the red region of the spectrum. Those grown in the supercritical region showed no ALP fluorescence. Heating the high-temperature-grown ALP under vacuum greatly increased its fluorescence efficiency and moved the emission peak to higher energies. I HE III-V compounds, with few exceptions, have been prepared by the two-temperature method. In its classic form this technique is applicable to closed systems where at least one of the components, in this case the column V element, is a liquid or a solid with a high vapor pressure. One advantage of this method over flow systems is in its simplicity. In addition, because it is a closed system, it can, under the circumstances to be described later, be run at higher pressures of the volatile species than in flow systems. In instances where the III-V compound is soluble in the parent III metal to about 1 mol pct or higher, solution growth can be made to take place by slow cooling. This, for instance, is one way in which single-crystal GaP1 and Inp2 have been grown. Initial attempts to synthesize and grow A1P by this technique were not too successful; the yield was low and the crystals obtained were exceedingly small. The conditions required for improving the yield and growth by this technique were, therefore, sought. Two obvious conditions which could be controlling were examined. These were the temperature of the aluminum and the pressure of the phosphorus. The range of temperatures studied extended from about the melting point of aluminum, 660° to about 1450°C. The latter is dictated by the vapor pressure of aluminum which reaches about 1 Torr at that temperature and the limitations of the materials of construction as described in the next section. The pressure range of interest covers from below 1 atm to above the critical pressure of phosphorus, 82.2 atm. EXPERIMENTAL The Temperature of Aluminum as a Variable. A series of experiments were run in the conventional two-temperature manner. All refractories and quartz were dried by heating at 800° to 900° for a minimum of 24 hr, and usually much longer, before use. The aluminum

Jan 1, 1969