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By J. Downie, H. A. Kendall, G. H. F. Gardner

Some cases of the motion of two miscible fluids in uniform linear models are discussed. There is no bulk flow through the models, and the convection currents are caused solely by density gradients. Horizontal, vertical and inclined positions of the models are treated separately. Analytical formulas for the motion of a narrow transition zone between the fluids are obtained and compared with measurements, and the limitations are discussed. Observations of the ultimate stabilizing effect of diffusion on the motion me compared with the theory. It is shown that fluid motion in an inclined model with a constant rate of bulk flow can be directly deduced from the cases discussed, provided the viscosity ratio is small. INTRODUCTION In some reservoirs, convection currents caused by variations in the fluid densities may be significant. For practical purposes it may be desirable either to minimize the effect, particularly in miscible displacement, or to maximize the effect as in some schemes for the production of heavy crude oils by combustion. Experiments by Craig, et al,l have shown the effectiveness of gravity in reducing the efficiency of a miscible displacement when the mixed zone between the displacing and displaced fluids is narrow compared with the height of the system. The presence of a board transition zone from one fluid to the other has been shown by Perkins, et al,2 to nullify considerably the influence of a difference in density. Indeed, the theoretical discussion given by Perrine3 has shown that when the transition zone exceeds a certain critical length the efficiency approaches 100 per cent. Many additional results 495 have been published on miscible and immiscible displacements which show the importance of density difference and also mobility ratio. The aim of the present paper is to discuss some cases of gravity segregation of miscible fluids in linear models such as are often used in the laboratory to evaluate recovery processes, and to supply additional experimental evidence in support of the conclusions. An attempt is made to calculate simply the magnitude of the fluid motion caused by density pdients and mobility ratios, and to quantify the modifications in the fluid motion produced by the combined effect of molecular and convective dispersion. However, it should be pointed out that the uniform permeability of the models and the use of only a single pair of fluids (whereas several pairs of fluids may be employed in a recovery scheme) severely restricts direct conclusions about natural reservoirs. For conciseness, the motion generated by density gradients is emphasized for the case of no bulk flow through the models. This is not a drastic limitation because, as shown in Appendix A, a fluid motion with a constant bulk flow through any linear model is equivalent to a fluid motion with no bulk flow in the same model inclined at a different angle to the horizontal, provided only that the density is a linear function of the viscosity of the fluid mixture. HORIZONTAL MODEL In this case the model is assumed to have a rectangular cross-section with a horizontal breadth b, vertical height and a great length L. Throughout.the paper it will be assumed that x-axis points along the length, the y-axis along the width and the z-axis along the height. Thus, in the present case the x, y plane is horizontal. Initially, the transition zone between the fluids is assumed to be thin and parallel to the y, z plane. An example of this situation in a practical problem arises in a scheme for using air for cushion gas in the storage of fuel gas in aquifers. 6 With the passage of time the denser fluid sinks and spreads along the bottom of the model while the lighter fluid rises. The interface extends from the top plane of the model to the bottom. Experiments have shown that for practical purposes this interface may be treated as a plane surface at all times. The surface is significantly curved, however, for viscosity ratios greater than about 10. Other complications arise with large viscosity ratios because of the nonlinear dependence of the viscosity on the composition of the mixture, so that the simple results given here are restricted to fairly low viscosity ratios.

By Nicholas J. Grant, Hanna Ibach, Bill C. Giessen

The system Ta-Rh was investigated over the entire comnposition range using metallogvaphic and X-ray techniques as well as thermal analysis. Terminal solubility limits, solidus temperatures, and the crystal structures of two new intermediate phases were determined. There are five intermediate phases: o, tetragonal, isostructural with o(Fe-Cr); a1, orthorhomnbic : a2, orthorhombic, isostructural with CozSi; 0 3, a high -temperature phase of unknozun structure; and a TaRh3, cubic, AuCu3 structure. a, aL, a,, and a melt peritectically; and a TaRh, has a maximum melting point. Five peritectic and one eutectic reactions occur. THE Ta-Rh phase diagram has not been fully treated in the literature; however, two inter metallic phases have been described.&apos;-&apos; This study attempts to work out the diagram covering the details of phase boundaries as well as the crystallography of the intermediate phases. EXPERIMENTAL METHODS Starting materials were tantalum powder of 99.8 pct purity, supplied by National Research Corp., Cambridge, Mass., and rhodium powder of 99.9 pct purity, supplied by Bishop Co., Malvern, Pa. Analyses as given by the manufacturers are presented in Table I. In addition to the spectroscopic analysis, an oxygen analysis has been made of the tantalum powder. After preliminary trials, the standard procedure employed in making the alloys was as follows (see Ref. 4 for further details). The powders were weighed, mixed manually, compacted under 16,000 psi, and arc-melted at not more than 500 amp under thoroughly titanium gettered welding-grade argon of 400 mm Hg pressure. The gettering process was repeated after each melt. It had been shown previously5 that under these conditions no oxygen pick-up exceeding 0.001 pct in a hafnium button could be detected. The buttons, ranging from 5 to 10 g in weight, were inverted or, if possible, crushed and remelted three times. Melting presented no difficulty, except for tantalum-rich al- loys, which showed considerable spashing during melting. The average weight loss of 1 wt pct rose to 2.5 wt pct in these cases. Subsequent melting, however, resulted in losses of less than 0.1 wt pct. The melts obtained frequently showed small in-homogeneities, mostly in the tantalum-rich part of the system below 25 at. pct Rh. This was not due to insufficient blending of the elements, but to crystallization taking place from the cooled bottom. This condition was not improved by further re-melting; therefore the following precautions were taken. Cross sections of as-cast buttons were made. For the investigation only buttons were used where these inhomogeneities did not exceed 1 at. pct (estimated from the amounts of haSeS resent). In addition, only the center portions of such buttdns were utilized to minimize errors. Smaller buttons showed smaller concentration gradients and were used as a check. Finally, all alloys were homogenized to eliminate coring (see below). After this, the error in alloy composition due to inhomogeneity was cl at. pct. In order to confirm the concentrations of the alloys and to provide an impurity check, wet-chemical analyses and oxygen-fusion analyses of four key alloys were carried out. The results, together with the concentrations as calculated with the weight balance method, are presented in Table 11. It was found that for three alloys the agreement is very good (< 0.2

Jan 1, 1964

By D. A. Flanagan, B. L. Landrum, P. B. Crawford, B. C. Norwood

Herern is described a heat conduction model which has been developed to predict the pressure distribution within a reservoir being subjected to rrnsteady-state depletion. Although potentiometric models have been widely used to study reservoir pressure distribution, their application is limited to the study of steady-state cases. Electrical analyzers may be used to study unsteady-state phenomena, but their application and simulation have certain limitations. Much of the now accepted theory of unsteady-state fluid flow in porous media has evolved from previous heat conduction knowledge. An analogy between the flow of fluid in an unsymmetrical reservoir and con-duct ion of heat in a similarly shaped unsymmetrical metal plate is made to show adaptability of the hear conduction principle to transient reservoir cases. A description of the model and necessary instrumenrarion is included. Data show influence of well location on pressure distribution during unsteady-state deple[ion. Application of results is made to a hypothetical reservoir and to a reservoir located in an irregular aquifer. INTRODUCTION Development of methods for predicting behavior of petroleum reservoirs has resulted partially from adaptation of electrical and thermal flow concepts to the flow of fluids through porous media. Extensive investigation of electrical and thermal flow problems has resulted in mathematical solutions applicable to many reservoir problems. The relative ease of measuring electrical flow has brought wide acceptance of the use of the potentiometric model to study certain field problems. Potentiometric models are restricted to the study of steady-state conditions because of the instantaneous response of electrical flow to changes in the applied potential. The electrical reservoir analyzer has been one of our most useful instruments for studying certain phases of unsteady-state behavior1. Other than approximation techniques, no method exists for determining pressure distribution in an irregular reservoir during primary depletion. Heat flow, like fluid flow, is inherently transient. The model described here was developed to use this transient nature of heat flow, measurable in the laboratory, to simulate transient flow of fluids in the porous medium of the reservoir above the bubble point. A metal plate shaped like the reservoir to be studied was heated by a "well" source. Temperature increase in the plate is analogous to pressure decline in the field if the field is being depleted, or pressure increase if fluid is being injected. This study is intended to determine the feasibility of using the transient nature of the heat flow to study the transient behavior of fluid flow. It is hoped that this new technique will aid in the understanding of one of the more complex phases of reservoir engineering. THE FLUID FLOW-HEAT CONDUCTION ANALOGY The similarity of the equations which describe the flow of fluids through a porous medium and the conduction of heat through a solid is well known2. Rate of flow of fluids is given by Darcy&apos;s law3. while the rate of flow of heat is given by Fourier&apos;, (I,, - KA 4T........(2) Combining Eq. 1 with the equation of continuity for a compressible liquid", i.e.,results in Expressing y in terms of the compressibility, i.e., pr = peey ,..........(5) and by expanding the exponential and neglecting higher orders of cp one can obtain

By W. C. Phalen

SALT-MAKING PROCESSES THE production of salt in the United States divides itself at the outset into two distinct classes: (1) The mining of rock salt and its purification and separation into marketable sizes, and (2) the production of salt by evaporation from brines, bitterns, and other solutions. The processes employed at the present time in the manufacture of salt by evaporation may be outlined as follows: 1. Solar evaporation. 2. Direct-heat evaporation (a) in open kettles; (b) in open pans. 3. Steam evaporation, (a) in jacketed kettles, (b) in grainers. 4. Vacuum-pan evaporation. In this paper only the solar-evaporation processes practised in different parts of the United States will be described. SOLAR EVAPORATION Localities In the Eastern States the solar-evaporation process is not generally employed for climatic reasons. In the Western States, particularly in California and Utah, the great bulk of the salt produced originates in the solar-evaporation process. Of the Eastern States producing salt, this process, so far as the writer is aware, is employed in New York State only.

Jan 9, 1914

By Oliver Bowles

Dimension stone is a term applied to stone sold in blocks or slabs of specified shapes and usually of specified sizes, contrasted with crushed, broken and pulverized stone covered in another chapter. Dimension stone includes cut stone, rough building stone, ashlar,* rubble, monumental stone, paving blocks, curbing, flagging, and many types of ornaments and novelties carved from stone. Riprap-large, irregular blocks used for shore protection-is classed with crushed and broken stone. Composition, Varieties, and Properties Dimension stones are of many kinds. The principal varieties are granites, trap rock (diabase, basalt, and gabbro), sandstone, limestone, and marble. Slate is covered in a separate chapter. Granite is a visibly granular crystalline rock consisting essentially of feldspar, quartz, and mica or hornblende. The basaltic rocks are darker in color than the granites. They contain little or no quartz and consist largely of plagioclase feldspar, augite, pyroxene, and hornblende. They are classed commercially as black granites. Limestone consists essentially of calcium carbonate. Dolomites and magnesian limestones used as dimension stone are classed with the high-calcium limestones. Marble is a crystalline form of limestone, but in the trade, any carbonate rock which will take a polish is called a marble. Many limestones which are fossiliferous but which will take a polish are sold as a decorative stone for lobbies of hotels and office buildings. Sandstone consists essentially of silica in the form of sand grains cemented into a coherent mass. Although rock occurrences are numerous and widespread, the exacting requirements of use condemn all but a small fraction of them for commercial use as dimension stone. No deposit that has closely spaced joints or planes of weakness can be used because sound blocks of moderate to large size are demanded. Uniform texture and grain size, constant and attractive colors or color pattern, and freedom from impurities that may cause stains or deterioration usually are demanded. Hardness is a variable property. Granites and diabases are as hard as or harder than steel, while limestones and marbles may be scratched with a knife. The hardness of sandstone depends upon the degree of cohesion of the grains. Workability depends to a considerable extent on hardness, but the degree of hardness has little influence on use except where stones are subjected to abrasion as on steps or floors. "Texture" as applied to stone relates to the arrangement, uniformity, and size of the constituent grains. Stones are of many colors and thus can satisfy a variety of tastes. For monumental stone, a marked contrast between polished and tooled surfaces is preferred in order that inscriptions may be read easily. Strength requirements usually may be disregarded because any sound structural stone suitable in other respects is almost invariably many times as strong as would be required for any ordinary use. The pressure on the base course of the Washington Monument, Washington, D. C., is less than 700 psi, and highgrade granites, limestones, sandstones, and marbles will sustain a crushing load of 10,000 to 25,000 psi. A structure made of stone with a crushing strength of 15,000 psi would have to be nearly 21h miles high before crushing of the lower courses would occur. However, stone disintegrates more readily under severe

Jan 1, 1960

By L. E. Young

The purpose of this paper is to start a discussion on: (I) methods of supporting the immediate roof, particularly of local areas of poor roof, during the mechanical loading of coal; (2) methods of increasing the rapidity of the movement of the mining faces so that, without the use of cribs, jacks, park walls, and filling, there will be no danger to men, equipment, and working places from the subsidence of the overlying strata. In the Pittsburgh district the application of mechanical loading devices in mines working in the Pittsburgh seam has been retarded by the difficulties of holding and handling the draw slate. Normally the thickness of this slate averages about 8 in. but the hardness varies, and a cut of coal cannot always be loaded without placing posts or crossbars to support the slate. Locally, the slate may be thicker and special methods of support may be required. If crossbars are placed to hold the slate when the coal averages 5 ft. in thickness, the standard methods of transporting the coal cannot be followed, and the use of conveyors may be desirable. Very little information is available on the effect of increasing the rate of movement of advancing or retreating break lines or longwall faces. A few British publications have presented some data but all such data relate to longwall faces that have moved not more than 6 ft. a day. The most rapid rate of movemerit of longwall faces in Germany is 6 ft. per day. In the ordinary hand-loading mine in western Pennsylvania break lines on full retreat will move about 2 ft. per day. If loading machines are used under similar conditions the rate of retreat may reach 4 ft. per day. In a mine where coal is loaded by hand on conveyors three shifts per day, the rate of retreat has ranged from 11 to 16 ft. per day, with an average of 13 ft. If mobile loading machines could be used to load on conveyors on break lines, the rate of retreat should be increased substantially During 1935 and 1936, the United States Bureau of Mines, under a cooperative agreement with the Pittsburgh Coal Co., carried on studies of roof movement at Montour To. 10 mine. The work war done urider the direction of Mr. H. P. Greenwald, Supervising En neer, Experi-

Jan 1, 1938

By H. A. Lequear, J. D. Lubahn

A sudden change from one constant strain rate to another during a tensile test causes an unusual transient in aluminum alloy 61ST. A sudden change from one constant stress to another during a creep test does not produce an unusual transient in this material. A specially devised test shows that the nature of the previous steady-state conditions, which the sudden change disturbs, is one of the factors affecting the transient behavior. Some of the observations may be explained in terms of strain aging. USUALLY a sudden change during a tensile test from one constant strain rate to another causes a small, abrupt vertical shift from one stress-strain curve to another, parallel one. This behavior is apparently characteristic of all metals at very low temperatures and of many metals for wide ranges of temperature. It is illustrated in Fig. 1 for some early data on 61ST tested at — 195oC, and in Fig. 2 for some recent data on copper at room temperature. The greater accuracy of the results of Fig. 2 over previous ones&apos; is due to the equipment shown in Fig. 3. Three levers apply the bulk of the load, while the changes in the small remainder load are indicated sensitively by a low capacity load scale. Refs. 2 and 3 describe the recording equipment. A test like those in Figs. 1 and 2 provides the information necessary to determine the rate sensitizrity, n,4 of the metal. ( a log s ) ? log s n = ------------------------ ----------------------------= ( a logs e, ? log e logS2-logS1 log S2/S1 log i2 — log e1 log e2/e1 where S equals stress: e is logarithmic strain or natural logarithm of (final gage length/initial gage length);" i is strain rate or de/dt: and n is rate sensitivity, rate of change of log stress with log strain rate at a given strain, or (a log S/a log i),. Normally, the rate sensitivity, n, is positive, which means that an increase in stress causes an increase in rate. However, certain exceptions, attributed to strain aging,5 have been observed. Fig. 2 indicates how rate sensitivity values are derived from the measurements. Table I summarizes the rate sensitivity values derivable from Fig. 1. In contrast to the behavior of copper in Fig. 2, the aluminum alloy 61ST, which strain ages when tested near room temperature, exhibits an unusual transient when the strain rate is suddenly changed,&apos; as shown in Fig. 4. Initially, there is a comparatively sudden vertical shift of the stress-strain curve in a direction corresponding to the rate change, but then the curve gradually shifts back again. The initial shift is not as sudden as might be expected, because the testing machine is unable to achieve the impressed rate change instantaneously, as illustrated in Fig. 2. The behavior shown in Fig. 4 will be referred to as a tensile transient, the word tensile implying that the behavior was observed in a tension type of test. The corresponding test, where the strain rate is maintained constant except for the sudden change, will be called a tensile transient test. A creep transient, by contrast, will be defined as a temporarily abnormal behavior in a creep transient test, where there is a sudden change from one constant load to another.&apos; In Fig. 4, a naive look at the gradually decreasing and then increasing load after a sudden rate incre-

Jan 1, 1957

By M. C. Udy, C. H. Lorig

THROUGH the years much interest has been centered in attempting to develop a direct method of iron-ore reduction, to replace or supplement the present indirect blast-furnace process. It would not be difficult to produce a list of more than 500 patents dealing with the direct production of iron and steel, but the few of this type of process that have proved successful do not produce in competition with the blast furnace; they produce special products. A survey of the literature reveals that the equilibrium conditions for the reduction reactions (iron oxides with carbon monoxide and with hydrogen) have been fairly well established but that data on the rate of reaction are discordant, although the general effects of the variables are known. This dissertation deals with the rate of reduction of a magnetite concentrate with hydrogen. The following variables have been studied: bed depth, gas velocity, particle size and temperature. The behavior of a single particle was also studied. LITERATURE Two general factors should he considered in a study of reduction of iron oxide: (1) equilibrium relations, and (2) rate of reaction. The first factor, equilibrium, has received the attention of many investigators and the equilibria Fe3O4-FeO-H2-H2O, Fe304-FeO-CO-CO2, FeO-Fe-H2-H2O, FeO-Fe-CO-CO2 are fairly well established. Of the second factor, the rate of reaction, much less is known. Data are comparatively scarce and there is very little concordance. The discordance probably results from the large number of variables influencing the reactions. However, the general effect of the variables is known. Among these variables are temperature, gas velocity, particle size, porosity, gas composition (distance from equilibrium), presence of impurities, greater or less prevalence of side reactions, and even design of the apparatus itself. Wetherill and Furnas1 published an excellent paper in 1934. They point out that any one or more of five processes (the chemical reaction, diffusion of the reactant through the gas film, diffusion of the reactant through the solid phase, diffusion of the reaction product through the solid phase, or diffusion of the reaction product through the gas film) may be the slow process, and thus the rate-controlling process. It is regretted that the work of these authors was limited to experiments at one temperature, and that the range of gas compositions was limited. Langmuir2 has shown that heterogeneous reactions take place at phase boundaries.

Jan 1, 1942

By W. O. Philbrook

An engineering analysis indicates that the coke rate in present blast-furnace practice is set not by chemical or thermal needs but to give adequate charge permeability for economical driving rates. An equation showing interrelations among pressure drop, gas flow, and charge characteristics has been derived. Flooding conditions and the location of the fusion zone are discussed. Maximum ore size is probably limited by chemical re-ducibility rather than by heat transfer. THE intention of this paper is to show that the ].imitations on the production rate and coke requirement of the iron blast furnace are not primarily chemical or thermal in nature but are related to characteristics of the burden and operation that govern gas flow, heat transfer, and stock movement. A semiquantitative analysis will be developed in terms of standard engineering principles to give a useful picture of the relative importance of physical and mechanical factors in contrast with the chemical features of the process that are more commonly emphasized. Most of the details of calculation have been omitted in the interest of brevity and to avoid submerging the rnain points in a sea of arithmetic. Numerical values have been arrived at by objective methods from reported operating data or by reasonable estimates of material properties where exact data are lacking and then tested to see how well they fit practice, rather than by working backward to find what assumptions are needed to give the desired answers. The analysis is oversimplified in many ways because exact engineering relations have not yet been studied for bed distributions as complex as are known to exist in the blast-furnace stock column. One objective of this paper is to show that the blast furnace, in spite of its complexity, can be at- tacked by engineering methods in the hope that this viewpoint will stimulate the kind of research needed for a more exact treatment. The basic ideas and many of the conclusions presented are qualitatively well known. A careful literature survey to credit the source of all observations not original to the author would indeed be voluminous, and such has not been attempted. T. L. Joseph&apos;s Howe Memorial Lecture&apos; gives an excellent background of what is known about the internal workings of a blast furnace. Other important reference works or sources of specific information will be noted. It is hoped that the present paper will contribute something new, in method of attack and interpretation, that will aid in a clearer understanding of how to operate the blast furnace to best advantage. Factors Limiting Production and Coke Rates The rate of combustion of coke in a blast furnace, as in any fuel bed, is exactly proportional to the rate at which air is supplied. It is axiomatic, then, that the production rate of a furnace is limited by the rate at which it will take wind, i.e., burn coke, and the amount of coke that must be burned at the tuyeres to make a ton of iron of suitable composition. These two possible limiting factors will be considered briefly in the order mentioned. One common restriction on wind rate is flue-dust production. Since the volume of top gas is nearly proportional to the blast volume (by a factor of about 1.35 on a dry basis), an increased wind rate causes a correspondingly increased linear velocity of top gas in the throat of the furnace. The higher

Jan 1, 1955

By M. J. Coolbaugh

Mining potash at depths of 3000 ft or more beneath thick water-bearing sediments in Saskatchewan presented a unique challenge to the North American mining industry. Potash is known to flow under pressure, but the knowledge of its flow characteristics at great depths was inadequate for safe design of mine workings and for assured protection from water above the salt formations. At the 3000-ft. depth of the Canadian mines, the potash is stressed beyond its elastic limit, and therefore mining design must deal primarily with its behavior as a plastic material. Recognizing that careful study would be required in order to assure safety and stability of mine workings in deep potash, IMC initiated an extensive rock mechanics investigation of structural properties of potash and salt under high-stress conditions. This presentation consists of a brief review of the development of some methods of testing potash in the laboratory and in the field; some of the rock mechanics concepts and principles derived; and their application to potash mine design. The mining of potash more than 3000 ft beneath the water-bearing sediments in Saskatchewan presented the unique challenge of designing stable mine workings and assuring protection from overhead water in a material that was believed to flow plastically, but whose behavior as a plastic material was not sufficiently known. Under the stress conditions ordinarily encountered in mining, most rocks behave as elastic materials; that is, they compress slightly under pressure, and rebound when the pressure is released. Salt and potash, however, are different. Even under the relatively low pressures encountered at shallow depths, these materials become slightly plastic and yield to stress by flowing.* The plastic properties become more pronounced at greater depth and pressure, and the question arises as to whether or not the plastic flow will be rapid enough and exert enough pressure to destroy underground structures or interrupt the mining process. It was found, however, that not only was there an insufficiency of information about the behavior of potash and salt, but conventional methods of testing these materials, such as determining the modulus of elasticity, Poisson&apos;s ratio, and uniaxial compressive strength, were inapplicable because of the high stress conditions prevailing at the 3000-ft depth. Potash under high pressure, for example, has practically no modulus of elasticity, its stress-strain relationship varies with time, and its compressive strength depends upon the degree of confinement. Elasticity and Stress/Strain Relationship: Fig. 1 shows a standard stress/strain chart for potash as made by the Department of Mines in Canada. Typically, when stress is applied to a hard-rock specimen, the specimen contracts, then expands to its original shape when the stress is withdrawn. This chart illustrates, however, that potash under stress yields to the stress by flowing, and does not expand when the stress is withdrawn. When the applied stress was held constant for 30 min, beginning at points A and C, the strain continued to increase and the potash flowed to points B and D, respectively. Points B, D, F, and H show that the potash did not return to its original shape when the stress was released. Thus it can be observed that potash has practically no elasticity and that the amount of strain depends upon the length of time that the stress is applied. Compressive Strength: The conventional method of determining the compressive strength of hard material is to find the maximum pressure that long slender specimens of the material can withstand without failing. As illustrated in Fig. 2,* line B, a standard 2-in. cube of potash subjected to a conventional type of uniaxial compressive test will exhibit a strength of about 5000 psi. However, the compressive strength exhibited can be made to change by changing the conditions under which the test is made. For example, if teflon plates lubricated with graphite are inserted between the press and the specimen, thus minimizing end constraint, the compressive strength is only about 2500 psi, shown in line A. If a specimen is cut in half, changing the width-to-height ratio to 2 : 1 instead of 1:1, and then tested without lubri-

Jan 1, 1968

By J. D. Doherty

That America&apos;s great coal deposits eventually will be our principal source of liquid as well as solid fuels is generally accepted. Moreover, the day when synthetic oil from coal will begin to supplement our petroleum supplies does not appear to be far off. The American petroleum industry has not spared effort or expenditure in its attempt to keep pace with the demand for oil, and recent production has exceeded expectations. However, the rapidly rising demand for liquid fuels plus the increasing difficulty of finding and developing the new oil needed even to maintain present production rates make it highly unlikely that oil from domestic wells can fully meet future oil requirements. Therefore, it appears that one or more of the following courses must be followed: 1. Curtail oil consumption. 2. Incr ase imports. 3. Develop new sources such as synthetic liquid fuels. All three courses may well be needed, as it is doubtful that any one of the three alternatives alone can satisfactorily solve the problem indicated by the prevailing trend in demand for oil. Curtailment of oil consumption is not a constructive policy, except where oil is being wasted or coal can be readily substituted as in stationary steam plants. Reduced oil supplies for most uses will curb our economic advancement and, in addition to inconveniencing consumers, will have a pronounced adverse effect on American industry. The oil-burner-manufacturing industry already has been dealt a hard blow. Shipments in the first 5 months of 1948 decreased 70 pct from those in the same period in 1947.1 The effect of a similar cut in the automobile industry can be imagined. A severe prolonged shortage of gasoline could seriously disturb our present economic well-being. It might be pointed out also that even the prospect of a shortage or lack of assurance for the future can discourage buyers of equipment, as occurred in the case of oil burners. An increase in our imports of oil seems to be a necessary expedient for the immediate future. Its advantages are that it will require a minimum of manpower and steel in a time of critical shortages and will conserve domestic reserves. Any major dependence upon foreign sources for our oil supplies should be avoided, however. Other nations are increasing their oil consumption more rapidly percentagewise than the United States and eventually will compete with us for the not unlimited world supplies. In peacetime, foreign countries might restrict ship- ments of oil to this country or impose exhorbitant prices. In the event of war, there is serious danger that such sources would be cut off, and American-developed oil fields overseas might even be used against us. Although synthetic fuels cannot relieve any oil shortage that might develop within the next year or two, an immediate start toward a substantial synthetics industry to supplement petroleum not only could help relieve shortages several years hence but also would help establish the much needed "know-how" for large-scale production. By assuring ample future supplies, such a start would permit sound planning by industries dependent upon oil and maintain or restore the confidence of prospective customers for oil-con-suming equipment. If it is agreed that domestic production of crude oil cannot be expected to meet future domestic demands, that oil rationing in general is undesirable. and that too great dependence on foreign oil should be avoided—and the weight of the evidence supports such conclusions—it is inescapable that commercial synthetic fuel production should be developed to supplement domestic petroleum supplies, which, of course, will furnish the bulk of our requirements for yean to come. Sources of Synthetic Oil The three principal sources of synthetic oil are natural gas, oil shale, and coal. A commercial plant using natural gas is under construction, and expansion of this industry is expected.

Jan 1, 1950

By C. S. Matthews, M. J. Fischer

Distortions caused by dip on five-spot sweep pattern were determined by visual experiments on a model composed of parallel plates of glass with holes drilled at the well positions. This model war designed to simulate a reservoir depleted of its primary oil and containing a gas phase. Prior to interference, it was found that the injected fluid took a nearly circular shape about the injection well for the cases studied. However, these circles moved down-dip considerably under the influence of gravity. It was concluded that pattern flooding should be practical for many dipping reservoirs. A quantitative measure is given of how much the well position should be altered to allow for dip. Experimental deternzinarions of injectivity showed this to be about the same in a dipping reservoir as in a horizontal one. INTRODUCTION This investigation was undertaken at the suggestion of the Pacific Coast area, Shell Oil Co., where a pilot water flood in a dipping reservoir was being carried out at the time this paper was in preparation. Prior to the undertaking of this flood there had been considerable speculation as to how gravity would distort a flood pattern in a dipping reservoir. The thought was expressed in some quarters that a five-spot flood would not be applicable to a dipping reservoir because the flood pattern would elongate in the direction of dip and would never form a "seal" around each five-spot. If the flood pattern elongated sufficiently, both the oil and the water might flow largely downdip rather than into the pattern producers. In view of the importance of the California water floods, it was deemed important to determine the effects of gravity on a five-spot pattern in a dipping reservoir. Previous work had also been carried out in this laboratory,1 but only for the single-fluid case. The present investigation extends these results to multifluid cases. Several sets of pictures of flood fronts are presented so that the process can be visualized. From these pictures, curves are obtained which show the correct drilling position for achieving equal times of oil-bank breakthrough. Several injectivity curves are also presented which may aid in prediction of injection rate. ASSUMPTIONS The present results were obtained with a model composed of two parallel plates of glass spaced about 1 mm apart. When the inertial forces are small, as in these experiments, the flow between the plates follows Darcy&apos;s law and is analogous to flow through porous media. In using these plates, it is not possible to scale effects of capillarity correctly as regards a transition zone between injected and displaced fluid. Calculations show, however, that effects of such capillarity should not be important in determining the gross flooding pattern in the field. In fact, in this model the capillary forces tend to circularize the pattern to a greater degree than in the field. To preserve a large ratio between the viscous forces and the circularizing capillary forces in the laboratory model, viswus glycerine was used as the flooding liquid and the rate of flooding was very high. The circularizing force is believed negligible in these experiments. In addition to the effect of the surface tension y, which tends to circularize the pattern, another capillary force must be considered. This is the adhesion tension y cos, which acts at right angles to the circularizing term y. If the plates in the model are "wetted" the same all around the periphery, then the adhesion tension,

Jan 1, 1957

By O. N. Carlson, W. M. Paulson

A phase diagram is proposed for the Y-C system based on the vesults of thermal analyses, microscopic obsevvations, and X-ray diffraction studies. Three intermediate phases occur in the system: a congru-ently melting fcc phase with a wide range of homogeneity about the composition Y2C, an intermediate solid-solution region between 55 and 58 at. pct C, and a bct dicarbide melting congruently at 2415°C. All three compounds undergo a phase transformation at elezlated temperatures. A continuous serzes of solzd solutions exists between the fcc phase and the high-temperature form of YC2 with a maximum in the solidus at 2000°C and 30 at. pct C and a minimum at 1805°C and 54 at. pct C. THIS investigation of the Y-C system was undertaken as part of a nuclear materials development program. Yttrium-base alloys are of interest as possible containers for liquid metals, and carbides are currently receiving increased attention as high-temperature materials for advanced reactors and other applications. Previous work on this system was limited in scope, and the results were somewhat inconclusive and at times contradictory. Spedding et al.&apos; reported the existence of a triyttrium carbide having an fcc structure with a wide range of homogeneity and Dean et a1.2 reported the existence of a rhombohedra1 phase having the stoichiometry of Y2C. Bachella et a1.3 observed that the latter was the result of ordering of carbon atoms in the fcc solid solution. The ordering range was placed at 800" to 1000°C. Vickery et a1.4 reported a high-melting compound which they identified as yttrium dicarbide, and Spedding and coworkers1 determined the structure of this phase as bct with lattice parameters a = 3.66 and c = 6.17A. Samsonov et al.5 reported the melting point of YC2 as 2300" * 50°C. Recently Bowman et a1.6 found a transformation in the dicarbide from the tetragonal to an fcc form at 1320 20°C. Samsonov and coworkers7 reported a monocarbide of yttrium melting at 1950" * 20°C and also a sesqui-carbide melting at 1800" * 50°C. The existence of the latter has also been indicated by others,1&apos;8 but neither compound has been definitely established. The Y-C phase diagram shown in Fig. 1 was proposed by Chubb and Keller8 in 1964 based on the data available at that time. The tentative nature of this diagram together with the uncertain status of the compounds indicated that additional work on this system was needed. EXPERIMENTAL PROCEDURE Yttrium metal of 99.9 pct purity was prepared for use in this study by the reduction of YCl, with calcium to form a sponge product.9 The major impurities in this material were as follows: 100 ppm C, 150 pprn H, 20 ppm N, 300 to 1000 ppm O, <20 ppm Ca, <100 ppm Cr, <80 ppm Cu, 150 ppm Fe, <30 pprn Mg, <400 ppm Ta, and <100 ppm Ti. Alloys were prepared by arc melting yttrium sponge together with pieces of high-purity graphite rod in a purified argon atmosphere. Homogeneity was insured by repeated melting, inverting the ingot between melts.

Jan 1, 1969

By Aloys IL. Wollrab

The conditions that govern the selection of a suitable type of detachable bit for the small, isolated mine, for rock work and tunnel contracting and for the large mine are quite dissimilar, therefore intelligent recommendation of a particular make of detachable bit must involve consideration of many factors. Small, isolated mines may find advantageous a detachable bit that a larger mine cannot afford to use, because of more efficient conventional steel sharpening and steel-distribution practice, but a small mine may not be able to adopt the practice of large mines because of necessary capital expenditures for equipment for detachable-bit sharpening and . shanking. The perfect detachable bit, suitable for all conditions, has not yet been developed. Conventional Drill Bit in Use That drilling speed increases as the bit gauge decreases is well known, but since small-hole drilling is the exception rather than the rule the rate of such increase is probably not so generally recognized. Tests carried out by Holman Brothers Limited1 with 7/8-in. steel show that when bit sizes are reduced from I½ in., I3/8 in., and I3/16 in-; to I3/8 in., I1/4 in.., and I1/8 in., respectively, the volume of the hole is I 5 per cent less and the drilling speed 49 per cent higher. Recent tests by the United States Bureau of Mines2,3 in hard, uniform basalt showed that a reduction in average gauge from 2.077 to I,826 in., a difference of o.25I in., gave an increased drilling speed of 65 per cent. The limits to which a drill hole may be extended depend upon the loss in gauge. Since the conventional bit with 5° and 14° clearances did not possess sufficient reaming edge to permit the smaller gauge changes that were required for small-hole drilling, experiments were made in bit construction with a view to correcting this deficiency. This resulted in the adoption of the full reaming cross bit (having full Carr charac1erist.i~~) by some mines4 In order to drill holes having a minimum taper from the collar to the bottom of the hole, full reaming center-hole cross bits with 90° cutting angles, 5° and 14° wing tapers, forged on 7/8-in. quarter-octagon drill rods, are used in the conventional drill-steel practice at Hollinger. In the steel shop close attention is given to the condition of the dies and dollies, which, combined with a rigid inspection of the finished bit, ensures as nearly a perfect bit as call be forged economically. Shop practices and costs have been discussed in earlier paper.5,6 The method by which the radii for the special dies used for forging bits of different gauge diameter are obtained so that the points and reaming edges cut circles of the same diameter has been discussed by Hibbert. Requiremnts for Detachable. Bit for Hollinger Under these it it was appar- ent that it would be difficult to introduce a detachable bit that could successfully compete with the conventional bit already in

Jan 1, 1943

By G. R. Love, C. C. Koch

The changes in superconducting properties with aging time have been studied ,for the pecipitation reaction in a Tc-30 at. pct V alloy. Superconducting critical temperature, upper critical field, and relative critical current density were determined by ac susceptibility techniques. Aging produces changes in critical temperature of both matrix and precipitate which can be rationalized by compositional effects. maximum flux pinning (critical current density) occurs at a time during aging when subgrain boundaries are completely decorated with precipitates and the subgrain centers remain precipitate -free. The particular effectiveness as barriers to flux motion of planar defects which enclose regions of low deject density is discussed. THE precipitation of a second phase can dramatically modify the superconducting properties of type I1 super-conductors. According to Livingston and Schadler1 one might expect changes in the primary, secondary, and tertiary superconducting properties of the material. Changes in matrix chemistry caused by precipitation can alter the fundamental superconducting parameters; critical temperature, Tc, and thermody-namic critical field, Hc. The concimitant changes in electron mean free path (reflected in normal state resistivity) can affect the critical fields Hc 1, IIc2, Hc3. Finally, the presence of precipitate particles may hinder the motion of flux lines and may considerably improve the current-carrying capacity in high-field superconductors. The influence of precipitation on superconducting properties has been studied in a number of systems.2 Magnetization measurements have been used to study the influence of precipitates on flux pinning in lead-base alloys by Livingston3 and Evetts et al4 In these alloys precipitates induced magnetic hysteresis and flux trapping. The amount of hysteresis increased with the volume fraction of precipitate and decreased with coarsening of the precipitate. Jn an Al-Zn alloy5 and an A1-Ag alloy6 the initial precipitate size was presumably smaller than a coherence length and coarsening increased magnetic hysteresis5 and critical current density.6 The influence of precipitation on superconducting properties has also been studied in several of the commercially interesting Ti-Nb7-10 and zr-Nb11 alloys. The maximum in critical current density for these alloys was confined to a narrow range of either isothermal aging time" or isochronal aging temperature7 during the precipitation reaction. Thus, experimental evidence and theoretical considerations suggest there is an optimum precipitate size, spacing, and density, and a critical composition with respect to the matrix for flux pinning. What these "optimum" values might be and the relative importance of each is still not clear, although a few generalizations can be made. It is generally accepted1&apos; that particle sizes smaller than the coherence length or larger than the inter-flux line spacing are poor pinning centers. In high Hc2 materials, precipitate sizes for maximum values of critical current density lie in the range of 50 to 2000Å,9,7 and there are indications that increasing dissimilarity between precipitate and matrix produces increasing pinning force.13 Because of several interesting features of the aging reaction in a Tc-30 pct V alloy, we have chosen to study the influence of precipitation on the superconducting properties of this alloy. The physical metallurgy14 and a survey of the superconducting properties" of the Tc-V alloy system have been reported. The Tc-V phase diagram is presented in Fig. 1. At 1500°C the Tc-30 pct V alloy is in the single phase 6 field. Samples quenched from the 6-phase field have a CsCl structure X-ray diffraction pattern at room temperature and it has been proposed that the 6 structure is closely related to the bcc lattice.14 When held isothermally below the eutectoid temperature, 115O°C, the 6 phase decomposes into the CsCl and hcp phases.

Jan 1, 1970

By T. S. Spicer, C. C. Wright

A CHARACTERISTIC property of bituminous coal is that upon being heated the coal becomes plastic, evolves volatile gases, and finally solidifies into coke This fundamental characteristic is of utmost importance and is utilized in the production of the high-temperature coke upon which the steel industry is so dependent, but from the standpoint of operation in the domestic underfeed stoker this coking tendency seriously interferes with efficient combustion When the coke formed has too strong a structure, certain difficulties result, such as low rate of burning, slow response to heat demand, and, in extreme cases, extinction of fire The plastic mass prevents uniform distribution of air through the fuel bed and, With strongly coking coals, large dense pieces of coke are produced which have much less reacting surface thin was possessed by the original coal In both ignition and combustion of solid fuels, the extent of the reacting surface is an accelerating factor Poor combustion permits a surplus of fuel to accumulate in the furnace because the rate of feed and the rate of combustion are not in equilibrium, and this produces an unbalanced condition detrimental to continued) automatic service In order to burn strongly coking coals satisfactorily in a conventional stoker during the three requisite types of operation continuous, intermittent and hold-fire, frequent attention is necessary Domestic stokers are defined by the industry as residential stoker heaters that burn 60 lb of coal or less per hour With a few exceptions, these units employ the underfeed principle of combustion in which both air and coal move in the same direction up and through the fuel-bed Domestic combustion equipment has difficulty in meeting the problems presented by the several variations in ash and volatile matter, in ash-clinkering tendencies, in coking properties, and in the particle size of bituminous coals The work of Bituminous Coal Research Inc at Battelle Memorial Institute has shown that, of these, coking characteristics and the clinkering tendencies have the greatest effect upon the operation of the conventional clinkering type of stoker Typical coke formations in a clinkering type of underfeed domestic stoker are illustrated in Fig. I, which shows (A) the ideal fuel bed obtained with a noncoking or free-burning coal, (B) the type of fuel bed formed -with, a coal that produces a weal coke, and (C) the type of fuel bed obtained with a strongly coking coal C is characteristic of the fuel bed developed when the average Pennsylvania bituminous coal is ,burned in an underfeed stoker of conventional type It is apparent from these pictures that the formation of coke trees will seriously interfere with the efficient automatic combustion of Pennsylvania bituminous coals

Jan 1, 1942

By W. T. Turrall, M. J. Cook

A discussion of modern developments in beneficiation of fine sizes of anthracite, this paper includes a description of the plant flowsheet, an analysis of operating results, and a summary of fundamentals of mineral separation relative to plant operation. DURING the past several years Lehigh Naviga-tion Coal Co. has installed equipment at Tamaqua and Lansford collieries for cleaning and sizing No. 4 buckwheat —3/32 + 3/64 in. and for recovering and cleaning flotation coal —20 + 200 mesh at Tamaqua colliery. Papers describing some of these installations have been presented to AIME. At Coaldale colliery, however, methods used to clean fine coal were inadequate and inefficient. Management decided upon a thorough investigation of all existing processes before building a plant to treat the combined three sizes mentioned. Investigation, carried out on company property and at other plants, entailed a study of hydrotators, hydroclassifiers, tables, spirals, flotation machines, methods of screening, and methods of dewatering. On the basis of this investigation a flowsheet was designed which necessarily excluded many processes in use, and the writers wish to emphasize that no criticism is implied by omission of processes or machines. A determining factor in selection of many machines was the policy of standardizing equipment wherever possible. Flowsheet and Operational Data The first principle to be considered in designing of any plant is efficiency of cleaning as related to laws of classification. Beneficiation of coal may be described as separation of two materials having different specific gravities. Although there is an inherent ash content even in the purest coal which slightly affects its specific gravity, it is recognized that many particles are true middlings. The percentage of these particles allowable in the final product depends upon the ultimate ash, or specifications of the consumer. Richards in his study of free settling and hindered settling classification&apos; determined that particles of equal size and different specific gravities had unequal settling velocities. He also determined a definite size relationship for equal settling velocities with free settling and hindered settling conditions. Considering the design of machines used to clean No. 4 and No. 5 buckwheat, it may be assumed that both free settling and hindered settling conditions exist and that ratio of size for practical operations is between the established values. The essential factor is that the more efficiently and closely sized the feed is maintained, the more nearly perfect the resulting separation. Flowsheet design was governed primarily by factors related to the 1200 to 1500 tons per hr feed to the main plant. It should be stressed that because of the many sources of supply from mine and stripping, the physical characteristics of this feed varied considerably. The most significant influence was varying percentage of fines, necessitating that all machines be capable of operating under maximum peak load during periods of surge. Since cleaning practice is a wet process, about 9000 gal per min containing 14 to 15 pct solids, or 350 tons per hr, must be treated. This slurry contained all the fines, or —3/32 in., but also percentages of oversize, up to 1 % in., dependent on spills or breaks in screen jackets, a not uncommon occurrence in preparation plant practice. The flowsheet developed is shown in Fig. 1. Circled numbers represent points of sampling. Table I gives operational data including size, ash by size, composite ash, rate of flow in gallons per minute, percent solids dry weight, and average tons of solids per hour. It should be noted that these results are subject to human error in sampling practice. Detailed information reported is a representative evaluation of plant operation.

Jan 1, 1954

By Alden Greninger

THE time-honored description of the growth of metal crystals to form polycrystalline aggregates is one in which two important steps are con-sidered: (1) nucleation, and (2) dendritic growth, each dendrite starting from its individual nucleus and resulting (upon slow cooling, assuming no solid phase changes) in a macrograin. This picture of the process of crystallization is incomplete, and it is with the hope of enlarging upon it that the following summary and correlation of experimental results are given. MOSAIC STRUCTURE For an exact definition of the mosaic structure of metal crystals-if, indeed, one can be found that will hold for all metals-one must await the results of much experimental work in this field. The writer&apos;s investiga-tions have been confined almost entirely to copper and a few of its alloys. The following terms are proposed, and will be used in this report: Macromosaic Structure l.-Large-scale mosaic structure; more specif-ically, mosaic structure of a scale large enough to produce splitting of Laue spots on back-reflection Laue X-ray patterns2. The deviation from exact parallelism of neighboring macromosaics varies from a few

Jan 1, 1935

By Donald D. Smythe

This paper describes briefly the topography and geology of the region where the mica-bearing pegmatites are found and discusses prospecting, the quality of the mica, its preparation, and evaluation of the deposits. Muscovite mica occurs in a number of widely separated localities in Brazil, but production has come largely from deposits in the southeastern and eastern part of the State of Minas Gerais (Fig. I). There the deposits form a discontinuous zone, which starts at a point go km. north of the city of Rio de Janeiro and extends north for some 500 km., roughly parallel to the coast. A maximum width of 180 km. is reached along the Rio Doce. To the west in Minas Gerais, and extending east into the states of Espirito Santo and Rio de Janeiro, the mica zone proper is fringed by areas in which there are scattered occurrences of mica-bearing pegmatites. A few of these outlying deposits have produced commercial mica, but most of them are unimportant. To the southwest, in the State of Sao Paulo, there are a number of mines, which at one time produced a very considerable amount of sheet mica, largely as a byproduct of kaolin mining. These deposits, and a few others lying between them and the main productive areas to the northeast, appear to be the southwestern continuation of the strong Minas Gerais mica zone. In the vicinity of Conquista, just north of the Minas Gerais boundary in the State of Bahia, and still farther north, near Jacobina, there are several known mica deposits. Their location indicates that they may be the northern continuation of the main mica zone. The major part of Brazilian mica production has come from four areas within the mica zone proper; from north to south, Governador Valadares, Raul Soares, Espera Feliz, and Muriaé.. The first is go km. from north to south and reaches a maximum width of 180 km. The Raul Soares area extends 135 km. from northeast to southwest, and in places is 80 km. wide. The Espera Feliz area is 100 km. from north to south, and reaches a width of 35 km. The Muriai. area extends 150 km. from northeast to southwest and its width reaches 40 kilometers. Between the known productive areas, and in the areas directly to the southwest and to the north of them, little mica has been produced. These gaps, as well as certain irregularities in the outline of the mica zone itself, are to be ascribed either to lack of prospecting or to conditions preventing the discovery of mica, rather than to its nonexistence. Elsewhere in Brazil mica has been reported from eastern Goiaz, Ceará, Pernambuco, Rio Grande do Sul, Matto Grosso, and Amazonas. Production from these sources is negligible at present. Because of the inferior quality of the mica from the more accessible of these localities, and the operational difficulties occasioned by the remoteness of others, it is improbable that they will become important producers for some time to come.

Jan 1, 1948

By Hjalmar W. Johnson

IT has long been accepted that blast-furnace practice varies to some degree with the coke used. While the qualities desirable in iron have been known for some time, the qualities in coke that produce such iron have not been established. There are no objective standards for blast-furnace coke, which is usually described in general terms, as good or bad. Many experienced operators believe that coke cannot be measured objectively except by using it in the furnace, noting the result, and labeling the coke according to furnace operations. This is admittedly unscientific, and besides is useless for the two main purposes for which a measure of coke quality is needed: (I) to produce the best possible coke from the coals and equipment on hand; (2) to test new coals and determine their value for blast-furnace coke. In seeking such an objective measure, much work has been done on tumbler tests, shatter tests, sizes of coke, porosity, specific gravity, reactivity or combustibility and other tests, but as yet very little has been published in which conclusive correlations have been established between such objective measures and furnace operation. In our study of the problem during the past 8 years we have developed no new measures of coke quality, but we have collected data that are presented here in the hope that they may assist in further work, so that at some future time there may be developed such positive measures. The purpose of this paper is to show that there are variations in coke and that such variations do influence the operation of blast furnaces. At the same time we must remember that there are variations in blast-furnace operation and it may be the blast furnace that is at fault. This correlation of coke properties with blast-furnace operation will be worked out in the following steps: I. Discussion of a period when a change in the coke resulted in an increase in efficiency on one furnace and a decrease in efficiency on another. 2. Adaptation of the inefficient furnace to the available coke so that normal efficiency was restored. 3. The use of radial distribution: a discussion of the effect of size of ore layer in adapting blast-furnace operation to the coke. 4. An example of a change in size of coke and the detrimental influence on the production of one furnace. 5. An example of a change in size of coke, together with manufacturing data, to show why it changed, the conclusion being that coke is a product with an optimum value. 6. Illustration of the fact that coke has different optimum values on two furnaces, with discussion on adaptation of operation so the optimum values will be the same. 7. Limitations of the use of screen tests as an objective measure of coke quality. 8. Importance of uniformity in coke. FUNCTIONS OF COKE AND QUALITIES REQUIRED TO PERFORM THESE FUNCTIONS Coke has three important functions in a blast furnace: (I) to furnish most of the

Jan 1, 1941