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By J. A. Herbst, G. E. Agar

The effect of fluid viscosity on the classification of solids in a liquid-solid cyclone was investigated. The separation size was found to be proportional to Additionally, it was found that the prediction of flow rate through a cyclone is dependent on a Reynolds criterion. Above a critical value, the flow can be predicted by a simple equation, whereas, below this value a variable orifice coefficient must be introduced. INTRODUCTION The solid-liquid cyclone is widely used as a device for classification, thickening, and heavy media separations. The more important variables and how they affect the performance of a cyclone are known and have been the subject of several investigations.' In general, these studies have paid little attention to the viscosity and those which have, introduced it through Stokes settling considerations. Systems which contain appreciable amounts of swelling clays exhibit viscosities much greater than water, and in these systems the viscosity term becomes important in determining the separation size. The work described here was done to determine in a Newtonian system the dependence of separation size on viscosity. BACKGROUND The separation size for a cyclone classifier has been related to the parameters of the cyclone by an equation of the form: where a is probably between 1.3 and 1.5, ß is between 0.50 and 0.57, and 6 has a theoretical value of 0.5. where y has a value between 1.8 and 2.0. Although these relationships are empirical, equations that differ only in the exponents have been derived from theoretical considerations. Those interested in the origin of these equations are referred to some of the original work.6,7 MATERIALS AND PROCEDURE The laboratory apparatus used in this study is pictured diagramatically in Fig. 1. Feed slurry was pumped from an agitated 15-gallon plastic tank by a centrifugal pump driven by 3/4 hp motor. The static pressure of the feedstream and thus the pressure drop through the cyclone was measured on a gage located as close to inlet of the cyclone as possible. When samples were not being taken, overflow and

Jan 1, 1967

By M. Murakami, Y. Murakami, O. Kawano

The formation and growth of Guinier-Preston zones in Al-Zn alloys containing 4.4, 6.8, 9.7, and 12.4 at. pct zn have been studied by the X-ray small-angle scattering method. Particular attention was paid to the effects of small amounts of third elements silver, silicon, and magnesium on the formation and growth of G.P. zones. It was noticed that an appreciable number of G.P. zones were formed during the course of rapid cooling and that the size, volume fraction, and number of these G.P. zones were influenced by the existence of the third elements. During subsequent aging it was also found that the addition of both silver and silicon lowered the temperature for the growth of G.P. zones, whereas the addition of magnesium raised it. These results were explained in terms of the mutual interactions among zinc atoms, vacancies, and the third elements. A number of studies on the formation and growth of Guinier-Preston zones in Al-Zn alloys have been reported.1-4 Panseri and Federighii have found that the initial stages of zone growth take place at temperatures as low as around -100°C. For investigation of the mechanism of the initial stages of zone growth, growth studies must be carried out at low temperatures. In order to investigate the possibility of the formation of G.P. zones by the nucleation mechanism or the spinodal decomposition during quenching which was reported by Rundman and Hilliard,5 the examination of the as-quenched structure must be performed. In this paper the investigation of the early stages of the formation and growth were determined by means of the X-ray small-angle scattering method. With this technique, change of X-ray scattering intensities was measured while quenched specimens were heated slowly from liquid-nitrogen temperature to room temperature. At as-quenched state and after heated to room temperature, investigation of zone size, volume fraction, and zone number per unit volume was carried out. Measurements on these specimens yielded information on the early stages of zone formation and growth. Measurements were made also on specimens quenched to and aged at room temperature. From these measurements the previously reported model6 for the later stages of growth is confirmed; namely, the larger zones grow at the expense of smaller ones. Three elements, silver, silicon, and magnesium, were chosen as the third elements for the following reasons: Silver. In the binary A1-Ag alloy the spherical disordered 77' zones were observed immediately after quenching.7 Therefore, in the Al-Zn-Ag alloys, it is suggested that silver atoms might induce cluster formation during quenching. Also, since the migration energy of the zinc atoms was found to be raised by the addition of silver atoms,' silver atoms may have a great effect of the zinc diffusion, especially during low-temperature agings. Silicon. The effects of the addition of silicon atoms were found to be marked, especially at low-tempera-ture aging. In the binary Zn-Si system, no mutual solid solubilities between silicon and zinc9 and no in-termetallic compounds10 are reported to exist. Shashkov and Buynov11 investigated the behavior of silicon atoms in Al-Zn alloys and showed that silicon was not in the G.P. zones. The interaction between silicon atoms and vacancies is strong enough to increase the quenched-in vacancy concentration.* Magnesium. Magnesium atoms are reported to trap quenched-in vacancies and after much longer aging times these trapped vacancies will become free and act as diffusion carriers.13 Therefore at intermediate aging times, the diffusion of zinc atoms in Al-Zn-Mg alloys will be slower than in the binary Al-Zn alloys, whereas at longer times zinc diffusion will become faster. EXPERIMENTAL PROCEDURE The alloys used in this investigation had compositions of 4.4, 6.8, 9.7, and 12.4 at. pct Zn with or without 0.1 and 0.5 at. pct Ag, Si, or Mg. The alloys were prepared from high-purity aluminum, zinc, silver, silicon, and magnesium, with each metal having a purity better than 99.99 pct. The analyzed composition of the specimens is given in Table I. The measurements of the X-ray small-angle scattering were carried out with foils of 0.20 mm thick. The change of the scattering intensity was always measured at the fixed scattering angle of 20 = 2/3 deg. This angle exists nearly on the position of the intensity maximum. The value of the interparticle interference function14 which has large effect in this range of angles may not change abruptly in the case of the spherical shape of small zones. Therefore, from the above considerations, it is concluded that an increase of the intensity measured at this constant angle corresponds to an increase of the average radius and volume fraction of G.P. zones. The specimens were homogenized at 500°, 450°, and 300°C for 1 hr in an air furnace. For the study of the formation and growth at low temperatures, the foil

Jan 1, 1970

The Carol concentrator of the Iron Ore Company of Canada was completed in 1962 and through expansions .has become one of the largest iron ore beneficiation plants in the world with a new feed capacity of 147,000 It (149,350 mt) per day. The Carol ore contains specular hematite and magnetite having a bulk density of 166 lb/cu ft (2660 kg/m3) It is crushed to 7 in. (178 mm) for feeding to autogenous mills for subsequent concentration by Humphrey’s s spirals. Mine ore is loaded into 150 It (152 mt) trucks by 10 cu yd (7.65 m3) shovels and then, at a transfer station, is loaded into side-dump rail cars of 100 It (101.6 mt) capacity. Each train is composed of twenty cars and operates completely automatically as it hauls the ore to the primary crushing station, dumps its loads, and returns to the loading station, a 11.5 mile (18.5 km) round trip. The primary crushing station is composed of two 60 in. by 89 in. gyratories installed in 1962 and 1972. Neither crusher has a grizzly ahead of it. Rail cars are dumped into 300 It (305 mt) pockets which contain splitters for spider protection. What few oversize boulders which do not go through the crushers are drilled and blasted. Liners in the dump pocket and the crushed ore pokcet under the crusher are manganese steel. Both crushers are direct driven by 700 hp (5 15 kw) motors, and the hardness of the ore causes them to pull almost their full power. Crushed ore drops into a 160 It (163 mt) pocket equipped with radioactive level control units for low-intermediate, and high level indications. The low level unit stops and starts the apron feeder, the intermediate unit controls the feeder speed, and a high-level reading stops the car dumping. Apron feeders are 72 in. (1. 82 m) wide and are variable speed from 12 to 52 fpm (3. 7 to 15. 8 mpm). They discharge to 60 in. (1.52 m) wide takeaway belts. Crushing capacity, nominal and maximum for each crusher, is 4, 000 ltph (4. 064 mtph) and 4,600 ltph (4,674 mtph). The crusher eccentric is removed by a conventional cart which travels on removable rails. Mainshaft removal and maintenance is done by 65 and 75/10 ton cranes. Mainshaft replacement requires eight hours, a usual time, but concave replacement requires only sixteen hours, a result of a fine maintenance organization. Mantle relining is done at grade next to a repair track. Zinc is used for backing both mantles and concaves. Both the electrical rooms and the dust collectors are located below grade,

Jan 1, 1978

By A. Lee Barrett

MINE power systems are quite different in many respects from those usually found in industrial plants. Wide areas are served, usually by a circuit which is connected continuously throughout the mine. In some mines one circuit may run for several miles. There are usually a small number of branch circuits involved considering the areas covered. In all mines circuits are sectionalized at approximately 2500 ft by means of switches. All, or at least most branch circuits, are sectionalized by manual switches. In some mines automatic sectionalizing gear is used to give automatic overload protection at various strategic points in the system. However at the present time this practice is by no means general. Circuit hazards in mine electric systems are much greater than those encountered in industrial installation. Falls of roof or coal form a prominent hazard which may break the wire and may cause ground faults or partial ground faults. Ordinarily electric cables in mines cannot be insulated, there- fore n fall can easily cause a short circuit. The humidity in most mines is greater than 95 pct and at many points the floor is wet and water may be dripping from the roof over insulators, increasing the difficulties at that point. All electrical circuits must be contained in the mine entries and space must also be provided for moving equipment and men. Consequently, because of the proximity of the power circuit to the locomotives and other moving equipment a considerable hazard is introduced. Mine haulage track is not always good so that wrecks are not unusual. A wreck frequently does consider- able damage to the power circuit. A ground fault frequently results in heavy arcing which may be sustained. If the damage to the circuit is mechanical it may mean that a trip of coal has wrecked and a great deal of coal dust could be thrown into the air as a result of the wreck. The arc resulting from the ground fault could ignite the coal dust and a mine explosion would result. A continued ground fault, even if high in resistance, also may ignite the coal which may be on the bottom of the entry and a mine fire may result. The fire hazard is one of the most serious hazards in any coal mine. Since the mine circuit is completely interconnected, any power interruption resulting from a fault seriously affects the whole operation. Unless the mine is completely sectionalized the whole mine will be shut down until the fault is located and the proper switches are opened to isolate the fault; even then large areas may still be without power if they are supplied by a single power circuit which may be opened in isolating the fault. Further, mine power is usually supplied from a relatively small number of substations and the fault may be on a stub feed circuit, in which case power cannot be restored until the fault has been cleared. Practice varies widely with respect to placement of substations. Usually they will be spaced from I to 2 miles in 500V operations, and at 1 mile intervals or less, in 250 V operation. Actual mining operations govern substation placements and no general rules can be followed.

Jan 1, 1948

By T. M. Anderson

Open pit mining at Inspiration began in 1947 after 32 years of underground mining. Two separate pits are included in the operations: the Thornton pit, which measures approximately 2500 x 2000 ft, and the Live Oak pit, which is 1500 x 3000 ft. The geographic centers of the two pits are approximately 4000 ft apart, and at the closest point, the two slopes are only 500 ft apart. Today, much of the open pit mining is being carried out in areas which were broken by earlier underground block caving operations; less than 50% of the total material moved has required drilling and blasting. In the solid or virgin areas, the, material ranges only from soft to medium hardness, thus simplifying drilling, blasting and loading operations. As a result, most mining costs and problems have been centered around truck haulage, truck maintenance and the ever-increasing length of the grade haul.

Jan 3, 1963

By W. B. Hall, Joy D. Lewis

Mine-run ore is received at Vitro in gondola cars and fed directly to a Cedar Rapids impact crusher. Following screening, the undersize travels through a recently installed three-stage sampling plant where successive cuts are executed by conventional Geary-Jennings type cutters to produce a final sample of 1 lb per ton of raw ore fed. Crushed ore is transported to one of three storage silos or to stockpile, depending upon grade and type of amen- ability. This permits the blending of a mill feed with some degree of consistency. Final grinding is accomplished in one of two closed circuit ball mill-classifier systems allowing simultaneous processing of two basic types of ores. High acid consumers may be leached separately in the required environment. Part of the free acid remaining can then be utilized by an ore stream entering later whose component ores require much less free acid for leaching.

Jan 11, 1958

By W. R. Foster, J. M. McMillen, A. S. Odeh

The complete equations of average linear momentum balance for a single-phase fluid in an incompreisible, homogeneous, porous medium are derived. The derivation begins with Euler's equation of motion for a continuum and uses an integral transform recently developed by Slattery. 7 For steady flow of a compressible, Newtonian fluid, the usual equations of motion result. For transient flow, the space-time description of the pressure is determined in the lowest approximation by the telegrapher's equation. From the analysis a new phenomenological coefficient results which connects the viscous traction to the deriv ative of the linear momentum density. The magnitude of this coefficient determines the velocity of sound through the pore structure in this approximation to the pressure field. INTRODUCTION The modification of Darcy's law of momentum balance for steady, single-phase flow through porous media has been discussed for many years. The first modification was suggested by Forcheimerl who added terms of higher order in the velocity. These can be expected to appear because the underlying microscopic equations of momentum balance are themselves nonlinear in the point velocity field. The Reynolds tensor pvv, which represents the convective flux of momentum density, appears in the momentum balance equation. Only in rectilinear flow (parallel stream lines) does the divergence of this tensor vanish. Since the steady flow stream lines in most porous media are not parallel, nonlinear dependence of the pressure gradient on the velocity should naturally appear. This nonlinearity has nothing to do with turbulence in the ordinary sense of random fluctuations in the pressure and velocity fields. It arises simply because the stream lines converge and diverge, even for steady flows. Klinkenberg2 demonstrated that the permeability coefficient in Darcy's law depends on the absolute pressure or, alternatively, on the density field. However, because he neglected inertial terms of the Forcheimer type, his correction coefficient could not be represented by a constant but tended toward a constant as the velocity decreased. Forcheimer's and Klinkenberg's modifications can be combined in a rigorous way to account for both inertia and slip during steady flow. This will be shown in a future paper. The transient change of pressure in porous media has been described by the diffusion equation.3 This form results from eliminating the velocity and density fields from a combination of the equations of motion in the form of Darcy's law, the continuity equation and an equation of state. Fatt4 suggested that the cause of deviations from the prediction of the diffusion equation for pressure transients lies not in the choice of Darcy's law as the equation of motion but on the existence of dead-end pores which might invalidate the averaged equation of continuity. On the other hand, Oroveanu and Pascal5 noted chat the time derivative of the momentum density must be included in the equations of motion since this measures the local rate of change of momentum density. Their differential equation for pressure is the telegrapher's equation (neglecting gravity). However, their form of this equation predicts that the speed of pressure propagation through the pore structure is the same as that through the bulk fluid. M. K. Hubbert6 attempted a derivation of Darcy's law by volume averaging the Navier-Stokes equations. Since these equations represent momentum balance at a point within an open set of points containing the fluid itself, Hubbert's volume averaging cannot lead to tenns involving transfer of momentum between the fluid and the walls of the pores. Once these viscous tractions are lost by choosing a control volume containing only fluid, they cannot

By J. M. Bugbee

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

Jan 1, 1943

By L. F. Stutzman, George Thodos

The friction factor plot presented by Cornell and Katz4 and developed for the flow of fluids through consolidated formations has been directly adapted for handling fluid flow problems involvitrg both linear and radial flow. In this adaptation the friction factor plot is used directly for the solution of problems and thereby eliminates the use of conventional equations which are specific to laminar (Darcy) or turbutent flow. This upproach overcomes the disadvantages inherent in the use of these conventional equations. It eliminates the necessity of checking the type of flow occurring in order to identify the specific equation which must be used. In radial flow problems, because of the increasing mass velocity of the fluids as they approach the wellbore. the type of flow may no longer remain laminar. Consequently, it is necessary to use more than one equation in a problem and to identify the range over which each equation should be applied. Finally, in practice it has been found that much of the flow of gases through consolidated media occurs in a range that is neither laminar or turbulent. For this transitional region, no convenient equations are available. The method and presented friction factor plot are appficahle to both liquids and gases. INTRODUCTION The flow of fluids through unconsolidated media in packed beds has been treated extensively by a number of investigatorsl,2,3,5,7,8 Most of these studies present friction factors as a function of modified Reynolds number similar to those developed for conventional fluid flow through pipes. These friction factor plots are presented for linear flow; however, Elenbaas and Katz have extended these concepts to apply to radial flow. All of these studies on unconsolidated materials require a knowledge of packing properties such as sphericity. porosity, and particle diameter. Sphericity and particle diameter cannot be defined at the present time for consolidated formations such as those commonly found in gas or oil reservoirs. As a result many investigators have not utilized friction factors and Reynolds number in the study of fluid flow through consolidated media. However, Cornell and Katz4 present a plot (Fig. 1) for the flow of fluids through consolidated porous media, in which the friction factor defined as: The turbulence coefficient, P, is related to the formation permeability, K, as presented in Fig. 2. Three different types of flow may exist in the flow ot

Jan 1, 1957

By C. T. Cox

The title of this short paper necessarily implies that friction articles comprise a distinct and unique field and are different from the other metal-powder articles, such as bearings, electrical contacts, and magnets. However, this distinction is rather hard to define in that it is really one of degree and not Of kind. It would appear that the main distinction is that friction are are articles of rather large pressing area. In other words, they are articles in which the area Of the mold in which the metal powder is pressed is relatively large. Other articles made from meta1 powders are generally of rather small area, usually a few square inches, while in friction articles the area ranges up to several hundred square inches. The satisfactory production of meta1-powder friction articles involves many production problems and a large number Of these are accentuated by the large area' Since it is impossible in the short space of this Paper to describe adequately all the problems involved, I have thought it best to merely mention some Of them and to place particular emphasis upon a problem that is common to all metal-powder articles, although it is of greater importance in the making of friction articles. This problem has to do with the effect On the properties of a friction article of small variations in the composition. However, before discussing the problems, it is probably appropriate that some mention be made of the limitations on the use of friction articles. Most engineers are familiar with the general field that can be characterized as constituted by clutch facings and brake linings, and undoubtedly have heard many stories of how metal-powder friction articles have had a service life 10 times as long as nonmetallic friction materials, and of instances where metal-powder friction articles have operated satisfactorily where no other material could be used. These instances should not be regarded as criteria for the assumption that metal-powder friction articles are capable of universal use in the friction field and will always outperform other materials. On the contrary, metal-powder friction articles are unsuitable for numerous applications, either on a performance or on a cost basis. Metal-powder friction articles will not replace wooden block brakes for wagon wheels nor cast-iron brake shoes for railway car wheels, to mention just two obvious examples. Metallic friction articles cannot be used where they must act as heat insulatorsl for they have a relatively high thermal conductivity as compared with asbestos. This is a detriment in some uses, as in certain airplane brakes having hydraulic actuators provided with rubber seals. The metallic friction material readily transfers the heat developed at the braking surface back through the material to the rubber seal and destroys it. Within its limited field, metal-powder friction material has proved satisfactory, but many problems are involved in the Selection of the proper material to use in an application and in the commercial pro-

Jan 1, 1945

By M. R. Geer, H. F. Yancey

Coal washing assumed an important role in the mining industry of the Pacific Northwest long before washing practice became firmly established in the Appalachian field. A Scaife washer was operated in the state of Washington in 1887; and by 1927, the fist year for which complete statistics were compiled, nearly a third of the state's coal production was washed, in comparison with only about 5 pct for the country as a whole. Mechanical preparation was adopted in Alaska in 1922 in a plant constructed by the United States Navy at Chickaloon to provide bunker coal for naval forces operating in northern waters. Many of the coal beds mined in Washington and Alaska contained more impurities than those mined elsewhere, and this circumstance contributed to the early interest in mechanical cleaning. A much more important factor, however, was the inclination of the coal beds. With steeply pitching beds, hand sorting by the miner at the face is impossible; consequently, all material must be loaded and dealt with on the surface, just as is now proving the case with mechanical mining of flat beds. Thus "full-seam" mining afforded the same stimulus to the early development of coal washing in the Northwest that it is providing under mechanization in the rest of the country today. Objeet and Scope ' This report is intended to provide a general summary of the status of coal-washing practice in Washington, Oregon, and Alaska—an area in which some of the coals mined are more difficult to wash than those mined elsewhere in the country. Detailed flowsheets of plants, statistical data on production, and cost figures have been omitted, largely for the sake of brevity but also because such information is principally of only local interest. On the other hand, considerable washability data have been included because they are Washington At present Washington leads all other states in the percentage of its total production that is cleaned mechanically, 82.1 pct in comparison with the national average of 25.6 pct in 1945.' The washing problems encountered in this state are highly variable because the mountain-building forces that created the Cascade Range caused such intense folding and faulting of the beds in some fields that the rank of the coal was increased to anthracitic, while in other fields more distant from the mountains the beds were relatively undisturbed, and the rank of the coal ranges down through subbituminous to lignitic. The complicated and burdensome schedule of sizes prepared in most coal fields has never been required by the Washington market. With but few exceptions, lump is prepared on a round-hole screen of about 3 in. size, egg is about 3 to 1 5/8 or 1½ in., and nut is 1 5/8 or 1½ in. to either 1 or ¾ in. Some mines screen no finer than ¾ in. and market a slack coal of that top size, but generally the coal is screened at about ¼ in. to give a stoker coal of ¾ or 1 to ¼ in., and a ¼ in. to 0 "buckwheat." During recent years the market for lump coal has largely disappeared, and lump is crushed to supplement the pro-

Jan 1, 1950

Jan 1, 1969

By A. G. Preban, R. J. De Angelis, J. B. Cohen, P. Gordon, D. C. Brillhart

Changes in stored energy, resistivity, density, X-ray line broadening, and dislocation arrangements (from transmission electron microscopy) have been mensured on copper specimens shock-loaded at 75 to 435 kbars. The stored energy in shock-loaded copper and changes in density and resistivity are larger than those after conventional deformation. A high density of twins makes an appreciable contribution to all the measured quantities. Dislocation densities rise to values of 1011 lines per sq cm at the highest pressure. The resistivity, density, and X-ray In a study of the effects of shock loading on copper, changes in stored energy, resistivity, density, hardness, lattice parameter, line broadening, and dislocation structure have been examined after subsequent annealing of specimens shocked to various pressures. This paper presents certain aspects of the data, taken by two groups, one at the Illinois Institute of Technology, and the other at Northwestern University, and compares the changes in these properties, and what they indicate about the effects of shock deformation. measurements yield dislocation densities in substantial agreement at all pressures, after correcting for the effects due to the twins. At the higher pressures, electron microscopy yields dislocation densities that are lower by a factor of about 5 to 10. Dislocation densities from stored -energy measurements are high; this finding can be rationalized by the consideration that the deformation twin boundaries present are largely incoherent. There is no evidence for homogeneous dislocation nucleation during shock loading. Shock loading any metal or alloy, such as copper, causes a large increase in yield strength, with dimensional changes of the order of only a few percent."' Other properties have not been extensively studied, but this result clearly indicates the importance of examining the substructure. Previous studies of the substructure of conventionally deformed specimens have been made using electron microscopy,3-6 X-ray diffraction,7,8 and etch pitting.9,10 The dislocation density can reach values of about 10" per sq cm; and the dislocations are arranged in cells approximately 0.15 in size. The substructure varies widely, however, from point to point in the specimen. The substructure of explosively loaded copper consists of cells of about the same dimensions6,11 but their size is more uniform.6 Profuse twinning occurs12,13 and the twins are often too small to be detected optically.6,13 The boundaries outlining these twins appear to be incoherent.14 There is now ample evidence 13-15 that twinning is a strengthening mechanism in fcc metals but this is only part of the strengthening effect in shock-loaded copper.* From the twinning systems which operate in shock-loaded single crystals,13 and from changes in texture on shock loading,17 it has been shown that both the

Jan 1, 1968

By Howard Eavenson

PRIOR to 1907 nearly all coke was made in beehive ovens, and most of the gas produced was made in the old-style gas retorts, and while there were a few coke plants in southern West Virginia, southwest Virginia and Kentucky operating on high-volatile coals the proportion of the total product made by them was small and was usually used locally. The greater part of the coke made, and the coal gas produced, came from the Pittsburgh seam of western Pennsylvania and northern West Virginia-which was then regarded as the standard coking and gas coal of the coun, try, and the best coal available anywhere for these purposes. With the advent of the by-product oven and the building of coke plants at the furnaces, the restriction of the use of one grade of coal for making coke was removed and the use of mixtures of low-volatile and high-volatile coals began. The change in the locations of the coke plants removed the necessity of using Connellsville coal and also made sources of gas available to the public utilities other than of their own manufacture. Most of the first oven plants were built at points distant from the Connellsville region and this afforded an opportunity for the use of coals from the southern Appalachian fields, which were at approximately equal distances from the ovens. Since that time development has been made on a number of seams of coal of great purity in southern West Virginia, southwestern Virginia and eastern Kentucky, which have been largely used for cokemaking, gas and other metallurgical purposes where low amounts of ash, sulfur and phosphorus are determining factors. These coals are much lower in the objectionable elements than the best of the coal from the Pittsburgh seam, or than any northern coal, and in by-product ovens produce coke that is not excelled for any purpose by any coal mined in this country, and is equaled very seldom. Coal from several of these seams is shipped in great quantities without beneficiation and is lower in ash and sulfur than the best washed product from any seam mined in the north.

Jan 1, 1932

By H. A. Deans

A three-parameter mathematical model for one-dimensional flow in porous media is developed. The objective of the model is to predict accurately the longitudinal dispersion associated with the flow of either gases or liquids over a wide range of Reynolds number. A qualitative analysis of the model parameters is given. Published experimental pulse-response curves are compared with results predicted by the model. Several general types of problems are given for which the model can be used. INTRODUCTION The problem of multicomponent single-phase flow through porous media is encountered in the study of petroleum reservoirs, gas chromatographic and ion-exchange columns, industrial fixed-bed con-tacters and elsewhere. These particular examples span the wide range of flow conditions possible; Reynolds numbers of less than l0-4 are not unusual in oil-production problems, while values in excess of 103 are common in large fixed-bed operations. The study of flow-dependent transport phenomena is complicated both by the changes in the character of the flow over this range, and by the irregularity of the flow boundaries inherent to porous media. Dispersion is one of the important phenomena known to depend fundamentally on flow conditions as well as on fluid and medium properties. As used in this paper, the term "dispersion" refers to the observed mixing of fluid elements of different composition which occurs in flow systems. The actual mechanism may be one or more of a number listed below. Only dispersion in the direction of the mean flow (referred to as axial or longitudinal dispersion, or mixing) is considered here, although lateral dispersion arises as part of certain coupled mechanisms. MECHANISMS FOR LONGITUDINAL DISPERSION A number of distinct mechanisms are known3,5,7,8 to contribute to the phenomenon of longitudinal dispersion. The more important of these are as follows. 1. Molecular diffusion in the flow direction. 2. Turbulent (cell) mixing. 3. Lateral transport processes coupled with velocity and/or residence time distributions, including: (a) "Taylor" diffusion caused by the interaction of velocity profiles in individual voids with lateral molecular diffusion; (b) separation and remixing or interdiffusion of streams having different velocities around particles; and (c) the couplipg of gross velocity profiles, caused by viscous instability or inhomogeneous porosity, with lateral dispersion. 4. Finite mass-transfer rate between a porous matrix and the flowing phase, and finite diffusion rate inside elements of the porous matrix. It is a well documented fact that these mechanisms, whether acting individually or in combinations, produce essentially similar integral effects. The observed dispersion can be described approximately by solutions of the diffusion equation with a properly chosen dispersion coefficient. Necessary conditions for equivalence between dispersion and diffusion are discussed by Klinkenberg and Sjenitzer.7 Apparently these conditions are not satisfied exactly in many real systems. "Best fit" solutions of the diffusion equation often depart appreciably from measured breakthrough curves for the usual pulse- or step-forced experimental systems. In particular, pulse response curves usually show some degree of asymmetry and "tailing" which cannot be reproduced by the one-parameter diffusion model. The three-parameter model proposed herein attempts to produce these effects in a realistic manner. Asymmetry and tailing are predicted for certain sets of parameter values, while for other sets the new model agrees with the diffusion model. VELOCITY DEPENDENCE OF DISPERSION Molecular diffusion apparently controls at sufficiently low Reynolds number in both gas and liquid systems.*l3 At Re > 20, turbulent cell mixing is dominant for gases flowing at low pressure; the data of McHenry and Wilhelm8 show that the mixing cell is approximately 1 particle diameter long in random sphere packs. on the other hand, the data

By Ö. Valla, A. Muan, K. Grjotheim

The solid miscibility gap between CaO and "FeO" in the system CaO-"FeO" in contact with metallic iron gradually closes as MnO is added as a third component. On the liquidus surface of the system CaO-"FeO"-MnO, this situation gives rise to a boundary curve which originates in the bounding system CaO-''FeO", proceeds a short distance into the composition triangle of the ternary system, and then vanishes. A new approach has been used to follow the course of this boundary curve. It is shown that the curve vanishes at a much lower temperature and at much lower MnO contents than has been inferred previously. The oxides CaO, "FeO", and MnO together with SiO2 are the major components of the slag phase formed in the basic oxygen process. Hence, the system CaO-"Fe0"-MnO is of considerable technological interest. In addition, the system is theoretically interesting. The three oxides above all have sodium chloride structure. The size differences among the cations are such that in the bounding "binary"* systems CaO-MnO and "FeO"-MnO complete solid-solution series are formed,1,2 whereas in the system CaO-"FeO" there is only limited mutual solubility in the solid state,3 see Fig. 1. Hence, a solid miscibility gap exists in a part of the "ternary"* system Ca0-"Fe0"-Mn0, and a liquidus boundary curve originates at the peritectic point, point a in the insert in Fig. 1, in the system CaO-"FeO", extends a certain distance into the ternary system, and then vanishes. Very little quantitative information on the system Ca0-"Fe0"-Mn0 is available in previous literature. Fischer and Feischer4 sketched isothermal sections at 1600° and 1700°C, and estimated that the vanishing boundary curve extends to approximately 1650°C and a composition of 42 wt pct MnO. The work to be described in the following was aimed at locating experimentally the "vanishing" liquidus boundary curve, determining its end point, and deriving representative isothermal sections below and above the temperature of the end point of this curve. EXPERIMENTAL METHODS The phase relations were determined by the well-known quenching method. (For a description of this method as applied to oxide systems, see the original paper of Shepherd, Rankin, and wright.5) Prereacted oxide mixtures of desired compositions were contained in iron crucibles and heated in a vertical tube furnace in an atmosphere of purified nitrogen. After equilibrium was judged to have been attained, the samples were quenched to room temperature, the phases present were identified by microscopic and X-ray examination, and total iron oxide contents were determined by chemical analysis. "Fisher Certified" reagents (MnCO3, CaCO3, Fe2O3, and Fe) served as starting materials. The calcium carbonate and ferric oxide were heated in air at 400° and 800°C, respectively, for 24 hr prior to use. Manganese oxide was prepared by decomposing the carbonate in a graphite crucible in hydrogen atmosphere at 1000°C. The product was ground under acetone to -100 mesh. The iron powder was used directly without any preparation. Dicalcium ferrite was used as a starting material for some mixtures. It was made by mixing some of the above prepared CaCO3 and Fe2O3 in proportions corresponding to the formula 2CaO. Fe2O3. This mixture was then fired in air for

Jan 1, 1969

Annual Meeting, February 17 to 19, 1914.-The following Committees have been appointed to have charge of the arrangements for the Annual Meeting in New York City: . General Committee: Louis D. Huntoon, Chairman; Arthur S. Dwight, Vice-Chairman; W. deL. Benedict, George F. Kunz, Thomas T. Read, E. Maltby Shipp. Reception Committee for Each Day: Chairmen to be announced later. Banquet Committee : Theodore Dwight, Chairman. Luncheon Committee: E. Maltby Shipp, Chairman. Ladies' Committee: Mrs. Arthur S. Dwight. Badge Committee : George F. Kunz, Chairman; E. Maltby Shipp, Vice-Chairman. Program Committee: Thomas T. Read, Chairman. Bureau of Registration and Information: Burr A. Robinson, Chairman.

Jan 1, 1914

By R. A. Haney, S. J. Gigliotti

Over the past ten years, analysis of the acceptability of face ventilation systems has been based on numerical criteria rather than solely a study of air flow and methane patterns in the face area. This type of analysis has become possible primarily because of the instrumentation and mathematical models developed by the Ventilation Division, Pittsburgh Health Technology Center, Mine Safety and Health Administration (MSHA). To properly use these mathematical models, large amounts of methane and airflow data must be collected in the face area during mining activities. To supplement underground testing of face ventilation systems, a full scale model of a face area was built. This model includes a full scale model continuous miner, a face ventilation system, a gas release system, and a remote methane detection system. The remote methane detection system consists of an array of twelve methane sensors located throughout the face area. Data from the sensors are transmitted to strip chart recorders. Methane, air quantity, and other data collected during a test are entered into a computer for analysis. This paper presents the data entry system, the models used for data analysis, the test results, and the application of these results to a face ventilation system.

Jan 1, 1983

By C. G. Bieber, J. R. Mihalisin, R. T. Grant

A growing demand for longer service life of gas turbines has placed increasingly rigorous requiret~rents upon superalloys employed for that application. Long-titne testing at high temperature has revealed that phase transformations occur in all superalloys. A common one of particular interest is o formation. Presented here are studies made to identify a and to characterize its formation and effect on properties in three cast nickel-base superalloys—IN 100 alloy, alloy 713C, and alloy 713LC. Methods are discussed by which o can be eliminated or inhibited in IN 100 alloy and alloy 713C. Evidence was obtained to indicate that some types of o may be more detrimental than others. Limitations in the electron vacancy approach to o prevention are pointed out, and it is shown how alternative approaches, such as reducing a complex superalloy matrix to the form of a pseudo-ternary system permitting equilibrium diagram treatment, lead to additional insights into the formation of in these alloys. AROUND 1960. Beiber1 developed IN 100 alloy, which still remains one of the strongest commercially available nickel-base superalloys. The principle used in the design of this alloy was to produce large quantities of y' phase in a y matrix through the use of copious amounts of aluminum and titanium. In 1963, ROSS' showed that when certain heats of this alloy were held for a long time at 1650°F they formed an acicular phase, subsequently identified as a.3 a is a hard and brittle phase first discovered in the Fe-Cr system by Bain and Griffiths.4 They termed it the "B" constituent. Subsequently this same phase was found in other systems, primarily those of the transition elements, and acquired the name "a" by which it is now known. The crystal structure of the a phase was first determined in the Fe-Cr system in 1950.5 It was shown to be tetragonal with a c/a ratio of about 0.52. as is the case with a found in other systems. This characteristic crystal structure is now the means by which a is identified. In superalloys, such as IN 100 alloy. large amounts of o impair the high-temperature creep strength and drastically reduce room-temperature tensile ductility. Discovery of o phase in some heats of IN 100 alloy quickly led to investigations of other superalloys for similar transformations. It was found that many of the stronger, more highly alloyed. super-alloys were indeed susceptible to o formation. This investigation has been concentrated on three commercial alloys: IN 100 alloy, alloy 713C, and alloy 713LC. J.R.MIHALISIN,MemberAIME, and C.G.BIEBER are with The International Nickel Co., Inc., Paul D. Merica Research Laboratory, Sterling Forest, Suffern, N. Y. R. T. GRANT, Member AIME, is with The International Nickel Co., Inc., Pittsburgh, Pa. Manuscript submitted May 22. 1968. IMD A detailed study has been made of the phase transformations and their relation to a formation along with a consideration of electron vacancy approaches for predicting a-forming propensity in these alloys. EXPERIMENTAL PROCEDURE Phase transformations were studied by light and electron microscopy, electron diffraction, microprobe investigations, and X-ray diffraction. Specimens for light micrographic examination were prepared by conventional grinding and polishing followed by etching with glyceregia (2:l HC1/HNO3 + 3 glycerine by volume). Photomicrographs of stress-rupture specimens were taken adjacent to the fracture unless otherwise noted in the text. Negative replicas for electron microscopy were taken from surfaces electropolished with a solution of 15 pct H2SO4 in methanol. For carbon extraction replication, a solution of 10 pct HC1 in methanol was used. A Siemens Elmiskop I was used for all electron microscopy. Selected-area diffraction studies were made at 80 kv using evaporated aluminum for standardizing the patterns. A nondispersive electron microprobe attachment was used to analyze the extracted precipitates chemically. The fluorescent X-rays were recorded using a flow counter containing P10 gas (90 pct Ar-10 pct methane) with a beryllium window and a single-channel pulse-height analyzer. The pulses from the analyzer were passed to a scaler-ratemeter and differential curves of counting rate vs pulse amplitude were obtained. The base line of the analyzer was driven with a synchronous motor at 0.5 v per min and a channel width of 0.5 v. The time for 105 counts was printed out for each 0.5-v increment. The microscope was operated at 80 kv with beam currents of 1 to 20 pa. This equipment detects elements from atomic number 13 to 40. X-ray diffraction studies were usually made on residues electrolytically extracted in 10 pct HC1 in H2O, although in one case a pattern was obtained from an etched surface of a metallographic specimen. A Siemens Crystalloflex IV was used with iron-filtered CoKa radiation. X-ray patterns were recorded using a goniometer speed of : deg per min. The scintillation counter and pulse-height analyzer operated at a channel height of 10 v and a channel width of 12 v. The equipment was calibrated with a powdered gold standard. The residues usually contained a number of phases. several of which could not be found in the ASTM card file. In addition, as is shown for the case of a phase in IN 100 alloy, other phases had a somewhat different lattice parameter from that reported in the ASTM card file, making it difficult to separate and identify constituents by comparison with ASTM d spacings. For these reasons, phases were identified on the basis of the lattice parameter obtained by indexing the ob-

Jan 1, 1969

By Louis L. Stott

It is well known that the oxide of beryllium was identified as a new "earth" in 17971 and the metal first isolated in 18272. The history of the many difficulties encountered by early investigators, the laboratory achievements of Lebeau3, Fichter4 and Oesterheld5, and the eventual development of methods for commercial production are well covered in the literature, particularly in the authoritative published work of Siemens and Halskes reviewing their comprehensive investigation of the element. Accordingly it has seemed desirable to restrict this paper to the properties and uses of beryllium and its alloys. PRopeRties of Beryllium A comprehensive summary of the available data on the properties of beryllium is given in " Gmelius Handbuch der Anorganischen Chemie7." The metal is steel gray in color. A fractured surface exhibits a bright luster, which does not appear to change with long exposure to air, probably because of a thin, transparent protective oxide coating. The specific gravity is approximately 1.8. Although there is no recorded actual determination of Young's modulus of elasticity, it has been estimateds, according to Fessenden's law, to be 30,000 kg. per sq. mm., or about 30 per cent higher than steel. Beryllium appears to have an electrical conductivity approximately 1/12 that of copper. The physical constants as available in the literature are given in Table 1. One of the outstanding properties of beryllium is its great affinity for oxygen, nitrogen, sulfur and carbon. One gram of beryllium takes up 1.774 grams of oxygen and will liberate approximately 15.23 kilogram-calories in the combination. The metal apparently reacts with all known oxides at high temperatures; in fact, beryllium will alloy with thorium and zirconium if melted in crucibles of their oxides. The true physical properties of beryllium are still somewhat in doubt, since very small amounts of impurities appear to cause a large variation

Jan 1, 1936