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By W. B. Gogarty

With flow of non-Newtonian fluids in porous media, effective viscosities are needed for use in the Darcy equation. These viscosities depend on the rock parameters and flowing conditions. In this investigation, rheological and flow results were correlated to develop an expression for calculating effective viscosities. Surfactant-stabilized dispersions of water in hydrocarbon were used with consolidated sandstone cores of different permeabilities. The average shear rate in a core was related to the permeability and porosity of the core and the frontal velocity through the core. By using the correlation obtained for determining effective viscosity, experimental and theoretical values were compared for each fluid system by determining average and maximum errors. For the fluid system showing the largest average error, the correlation fit 38 experimental points with an average and maximum percentage error of 4.3 and 14.8, respectively. For the fluid system showing the least error, average and maximum percentage errors of 1.8 and 4.3, respectively, were calculated using 29 experimental points. INTRODUCTION Use of non-Newtonian fluids in the petroleum industry is not new. Fluids of this type have been used for many years as fracturing agents and drilling muds. Recently, attention has focused on the use of high molecular weight polymer solutions for secondary recovery. Results have been reported on studies relating to the flow behavior of polymer solutions in porous media.1-4 Each study gives the viscosity in the Darcy equation as a function of the rheological properties of the fluid, the characteristics of the porous medium and the pressure gradient. The functional forms of the reported expressions differ somewhat in each study. The first three studies used unconsolidated porous media while the fourth used a single consolidated core. Because of the limited information available on the flow of non-Newtonian fluids in porous media, further investigation was undertaken in this area. We selected non-Newtonian fluids that did not contain high molecular weight polymers in order to minimize core plugging. The over-all objective was to gain a better understanding of the flow behavior of non-Newtonian fluids in consolidated porous media. Specifically, our goal was to determine the relationship between the average shear rate in a core and the frontal velocity. Because of this goal, it was necessary to determine the effect of permeability on the shear rate-frontal velocity relationship. We wanted to replace the viscosity in the Darcy equation with an expression relating to the average shear rate in the core and the rheological properties of the non-Newtonian fluid. THEORY For a time-independent, non-Newtonian fluid, the apparent viscosity is a function of the shear rate. This relationship is given by µ = F(v')...........(1) With Eq. 1, a single value of shear rate determines the apparent viscosity at that shear rate. With flow in porous media, a spectrum of shear rates occurs at any average throughput. An average shear rate v' can be used to represent the spectrum of shear rates that exists within the core. By using v' and the rheological data given by Eq. 1, an effective viscosity is determined for the flowing fluid. If v' is the correct average, µe becomes the appropriate viscosity for use in the Darcy equation. Under these conditions, flow rate-pressure drop relationships can be determined for non-Newtonian fluids. HOW the correct average shear rate might be related to the frontal velocity through the core and the characteristics of the porous media will now be considered. Later, the experimental data are presented that indicate the validity of these

By E. W. Davis

THE large iron-ore producers on the Mesabi Range are able to maintain the silica in their shipping products at from 8 to 10 per cent by mixing ores of various grades, some assaying 4 per cent silica and some as high as 18 per cent silica. For each ton of 4 per cent silica ore mined, a ton of 14 per cent silica ore can be mined and mixed with it and the average grade maintained at 9 per cent. This mixing operation has made possible the utilization of large cluantities of ore too lean to be used alone. and herein lies the advantage of the producers who operate a number of mines at the same time. As the grade of the ore from one of the properties falls off, a little high-grade ore from another property can be mixed with it and the average maintained, while if one property alone were being operated all of the ore below grade would be left behind.

Jan 1, 1930

By R. E. Boni, G. Derge

Application of surface tension measurements has been made to molten silicates in order to determine the effect of sulphur upon the surface tensions of synthetic blast furnace slags. In melts with the same molar ratios of AI2O3 + SiO2 to the basic oxides BaO, CaO, and MgO, the surface tensions increase in the order of oxides listed. Sulphur lowers the surface tensions of the basic BaO, basic CaO, acid BaO, acid CaO, and acid MgO slags in that order; and the concentration of excess sulphur at the slag surface increases in this same order of slags. The rate and amount of desulphurization of iron by these slags is favored by a low excess surface sulphur in the slag. IN a previous paper,1 the authors discussed the applications of surface tension measurements of molten silicates to problems of metallurgical interest. Of major importance is the aid that such studies lend to forming a working concept of slag structure. Since the ability of a slag to desulphurize metal depends strongly upon its composition,2"4 fundamental information about the structural differences between various slags which contain sulphur should aid the development of better desulphurizing media. For that reason, the present investigation concerns the effect of sulphur upon the surface tensions of synthetic blast furnace slags. Experimental Procedure , The maximum bubble-pressure method was used to measure the surface tensions of synthetic blast furnace slags in the temperature range 1300° to 1600°C. The method is based upon the equation which was developed by Schrödinger5 from a consideration of the forces of hydrostatic pressure and surface tension of a liquid which oppose bubble formation when a gas is forced through a tube immersed in the liquid. where y is the surface tension between argon and slag in dynes per centimeter; g is the gravitational constant, centimeters per second2; H is the manometer reading in centimeters; s2 is the density of manometer fluid in grams per cubic centimeter; S1 is the density of the medium in grams per cubic

Jan 1, 1957

By Ursula E. Wolff

The precipitation of carbides from an alloy containing 33 pct Ni, 21 pct Cr, balance iron, was investigated electron microscopically by means of extraction replicas and thinned metal foils. Annealing temperatures ranged from 565°to 870°C and up to several thousand hours. M23C6 precipitated in pain boundaries, incoherent and coherent twin boundaries in that sequence. The orientation relationship between carbides and austenite matrix was determined and correlated with the morphology of the carbides and with the type of boundary in which precipitation occurred. In large-angle grain boundaries, as well as in coherent twin boundaries, the carbides had the same orientation as one of the adjacent pains. These carbides formed sheets of individual flakes with shapes related to the orientation of the boundary. In incoherent twin boundaries carbides precipitated in ribbons composed of pavallel rods. An unidentified subcarbide was found to precede precipitation of M23C6 in these boundaries. The M 23 C6 rods had a kind of fiber texture with (110) parallel to the long dimension of the rods and ribbon, and with orientations of both of the adjacent twin-related austenite crystals Predominant in the texture of the carbide. A hard sphere crystal model has been used to discuss orientation and morphology of the carbides in terms of free volume and vacancies available in the boundaries. A number of papers have dealt with the morphology of chromium carbide (M23 C6) precipitated in austenitic stainless steels.1"7 In all these investigations, the carbides were examined in the electron microscope by means of extraction replicas. With this technique, the carbides retain the spatial distribution they had in the bulk sample. However, since the matrix is dissolved in the process, the particles can turn in an unpredictable way; and the orientation relationship between matrix and carbides cannot be established. In this paper the results of studies on extraction replicas and on thinned metal foils are reported. These studies were undertaken to determine the matrix-to-car bide orientation relationship, and to correlate the orientation of the carbides with their morphology. PROCEDURE The material used was an austenitic alloy with 33 pct Ni, 21 pct Cr, balance iron, containing approximately 0.05 pct C. Coupons of 1.25-mm sheet were first solution-annealed at 1050°C for 15 min and air-cooled. Then, to precipitate the carbides, samples were isothermally annealed in the range from 565" to 870°C for times up to several thousand hours. All further specimen-preparation procedures were carried out after the final anneal. Carbon extraction replicas from polished and etched surfaces were made with 10 pct bromine in methyl alcohol.' Thin foils were prepared from punched-out 3-mm-diam disksg which fit into the electron-microscope holder. The disks were prethinned by grinding to approximately 0.5 mm thickness, and then electro-polished in a polytetrafluoroethylene holder1' with a solution containing 5 pct perchloric acid in acetic acid to which 10 g per 1 Cro3 and 5 g per 1 nickel chloride were added (etchant modified from that of Briers et al."). This solution dissolves neither the carbides nor the austenite around the carbides preferentially. By using extraction replicas, electron micrographs and selected-area electron-diffraction patterns were taken from the same carbide arrays. By using thin foils, electron micrographs were made from a grain boundary area containing carbides. Electron-diffraction patterns were then taken from the same area and from each of the adjacent grains separately. In this manner, the orientation of each grain could be determined without interference by the carbide pattern. A peculiarity of extraction replicas should be pointed out. After the matrix is etched away, the carbide arrays float freely in the etching and washing solutions, and are held in place only at the anchoring points in the carbon replica. When the replica is picked up with a screen the carbide arrays tend to flip to one side. Thus, while the surface features are preserved, the original arrangement of the carbides may severely and unpredictably be disturbed whenever the specimen contains large amounts of interconnected carbides. Nevertheless, it is possible to correlate the different morphologies of the carbides with the type of boundary in which they have precipitated. RESULTS 1) Extraction Replicas. Fig. 1 shows that the grain boundaries usually are curved, multicornered surfaces of random orientation. The coherent twin boundaries (which are (111) planes) cut a grain into parallel slices. Incoherent twin boundaries occur at the ends and on the steps of twins and are often narrow, parallel-sided strips which are much longer than they are wide. Different morphologies can clearly be distinguished for the M23Ce carbides precipitated in each of these types of boundaries, and agree well with those observed by kinzel.2 The kinetics of this precipitation has been investigated." The first carbides precipitate in junctions of three grain boundaries and fan out from there into the adjoining boundary surfaces, Fig. 2(a). These carbides are oriented randomly, Fig. 2(b), and become coarser and thicker as annealing time increases. The large-angle grain boundaries are next to fill

Jan 1, 1967

By John T. Galey

An intensified search for gas, because of the shortage in the area, led to the completion of 482 wells in southwestern Pennsylvania during 1944. This number was 27 more than the number in 1943, but 118 of the wells were nonproductive. Shallow Development Oil The initial production of the 25 producers completed was slightly less than was obtained from four wells above last yearJs total. The largest well, 20 bbl., was found in the Big Injun (Miss.) sand in Morris township, Washington County, at a depth of 2085 ft. It is currently producing about 3 bbl. per day. Outside the main producing area, a well drilled in Nicholson township, Fayette County, obtained 15 bbl. per day from 1864 to 1866 ft. in the Gantz (U. Dev.) sand. The Federal subsidy of 75¢ per barrel, effective , 1, 1944, which increased to $3.40 the current pipe-line price in this area, seems to have been insufficient stimulus to materially increase drilling for oil, although more repressuring operations are contemplated. Gas The volume of initial open flow of gas developed is off slightly over 10 million cu. ft. from 36 more wells than were completed a year ago, and the average rock pressure of this new gas is more than 100 lb. less than that obtained a year ago. Apparently the best find of this year was reported in Patton township, Allegheny County, where an initial volume of over 4 million cu. ft, was encountered in the Speechley (U. Dev.) sand at a depth of from 3293 to 3303 ft. The rock pressure there, 1190 lb. per sq. in., is nearly virgin. However, this area is fairly well delimited by dry holes and docs not seem nearly so promising from the standpoint of reserves as the Armbrust area, which was discovered several Years ago. In the patton township locality another fair well with 1303 M cu. ft. open flow and 400 lb. Per 59. in. rock pressure completed in the Hundred-Foot (U. Dev.) sand at a a depth of 2125 feet. Armstrong County, as usual, leads in number of producing wells completed with lowest percentage of failures but ranks only fou th in volume of production developed. Only two wells here had more than one million cubic feet capacity, but the rock pessure was under 200 Ib. Per sq. inch. In Fayette County, where the largest portion of new gas was found, activity appears to be shifting eastward. In Luzerne township, four producers having a total combined initial open flow in excess of 10 million cu, ft, were found in the Big Injun (Miss.) sand. The best well was found also in the same area in the Speechley sand (U. Dev.) at a depth of 3460 ft. This was a 2500-M CU. ft. well in Georges township. Several wells of more than a million cubic feet capacity were found in Jackson, Washington, Wayne and Whitley townships, Greene County. None of these, however, was in a new pool.

Jan 1, 1945

By R. F. Mehl, M. Gensamer

Creep investigators have made extensive studies to determine the interrelation of stress, temperature and the tensile creep rates of metals. It has been suggested that at small stresses the secondary or constant creep rates obey a simple viscous law. Building upon this suggestion, departure from pure viscosity as stress increases may be expressed mathematically as a consequence of reversibly altered viscosity or "flowability" in the same sense that temperature change reversibly alters viscosity. From the index to alteration of viscosity, a value for the energy of secondary creep may be derived having the magnitude of the free energy of vaporized metal. The suggestion is made that application of stress alters the energy of secondary creep. Strain energy is argued to be but a minor factor in the energetics of secondary creep. A deformation mechanism involving the large energy associated with secondary creep implies a sort of solid self-diffusion process. Evidence indicates that creep strain above the recrystallization temperature takes place by crystallographically directed self-diffusion at grain boundaries and points of crystal defects. A self-diffusion theory of secondary creep is proposed, embracing the principles of the Dushman-Langmuir theory of solid diffusion. An equation is suggested whereby the rate of tensile creep may be related directly to the physical and structural character of the solid metal. Basis of Investigation Much of the investigation that has been given to the creep characteristics of metals and alloys has been directed toward studying the dependence of creep rate upon stress. Great interest has centered upon the approximately uniform rate of flow that has been demonstrated for numerous metals and alloys. At temperatures above the strain-hardening ranges of materials, this uniform rate frequently is attained after a relatively short period of initial rapid flow, and the period during which it persists determines for most practical purposes the useful life of the

Jan 1, 1938

By R. F. Mehl, M. Gensamer

Creep investigators have made extensive studies to determine the interrelation of stress, temperature and the tensile creep rates of metals. It has been suggested that at small stresses the secondary or constant creep rates obey a simple viscous law. Building upon this suggestion, departure from pure viscosity as stress increases may be expressed mathematically as a consequence of reversibly altered viscosity or "flowability" in the same sense that temperature change reversibly alters viscosity. From the index to alteration of viscosity, a value for the energy of secondary creep may be derived having the magnitude of the free energy of vaporized metal. The suggestion is made that application of stress alters the energy of secondary creep. Strain energy is argued to be but a minor factor in the energetics of secondary creep. A deformation mechanism involving the large energy associated with secondary creep implies a sort of solid self-diffusion process. Evidence indicates that creep strain above the recrystallization temperature takes place by crystallographically directed self-diffusion at grain boundaries and points of crystal defects. A self-diffusion theory of secondary creep is proposed, embracing the principles of the Dushman-Langmuir theory of solid diffusion. An equation is suggested whereby the rate of tensile creep may be related directly to the physical and structural character of the solid metal. Basis of Investigation Much of the investigation that has been given to the creep characteristics of metals and alloys has been directed toward studying the dependence of creep rate upon stress. Great interest has centered upon the approximately uniform rate of flow that has been demonstrated for numerous metals and alloys. At temperatures above the strain-hardening ranges of materials, this uniform rate frequently is attained after a relatively short period of initial rapid flow, and the period during which it persists determines for most practical purposes the useful life of the

Jan 1, 1938

By John V. Beall

WHEN asked a few weeks ago if we wished to visit the Coors plant at Golden, Colo., we agreed with alacrity being well acquainted with the high quality of Coors beer and having heard that the company was most liberal about sampling privileges. Instead of a brewery, we found ourselves in a pottery, the Coors Porcelain Co., owned and operated by the firm of beer fame. Our apparent disappointment was dispelled as the wonders of the porcelain products were unfolded.

Jan 2, 1953

By Walter E. Mingramm

The construction of rescue-apparatus on the principle of furnishing the wearer with air from a tank containing it under high pressure was given up by inventors about 20 years ago. Such an apparatus must supply continuously, for not less than two hours, nearly 50 liters of pure air at atmospheric pressure per minute, or a total of 6,000 liters (210 cu. ft.); and a cylinder containing this amount of air, under 2,000 lb. pressure, would weigh 180 lb. or more. Although apparatus has been recently constructed utilizing liquefied air, no experiments have been made to determine the regularity with which the air is generated, nor has its chemical composition been determined. Moreover, the chief objection to such an apparatus is the difficulty and cost of keeping on hand a large quantity of liquefied air. The system of furnishing the wearer of a breathing-apparatus with air which has given the best results, and has found

Jan 1, 1909

By Margaret G. Scroger, Luke L. Y. Chang, Bert Phillips

Using the sealed-system technique, isothermal sections at 1000°, 1400°, and 1700°C for the system Co-W-O hare been determined. The equilibrium data were obtained by microscopic and X-ray diffraction examination of samples winch had been equilibrated in pellet form fit sealed capsules and subsequcelly quenched. The only ternary phase in the system is CoWO, which mells congruentlly at approximately 1280°C. At 1000°C, this ternary phase exists in equilihrinm with all the allows and oxide compounds in the hounding binary systems. At 1400°C, liquid forms in thin oxygen-rick region near the CoWO4 composition and only one phase assemblage in the system (W + WO2 + H'5CV7) contains no In order for tungsten to be used to its full potential as a refractory metal. it is necessary that coatings be developed which will preclude oxidation of the metal. It is true that coatings now in use do protect tungsten for short periods at temperatures near 1700 °C. but no coating has been developed which protects adequately at or above this temperature where the use of tungsten is most required. This situation exists despite the great effort in recent years to develop such coatings. and it has become evident that success in this area can be achieved only after a more fundamental knowledge of the thermochemical and therrnophysical propertics of tungsten oxidation and tungsten -metal oxidation is obtained. In our 1aboratories. a project liclrriel. At 1700°C, tungsten is the ouly solid phase which is stctble, and a large range of compositions melt to two liquids, one metallic and one oxidie. The sealed-system method of etjuilibra lion prevents the determination of the partial pressure of oxygen and the total gas pressure orer the condensed phases at equilibrium. This data is not available and can be obtained only by some other method. We can generalize on these unknowns and indicate that both partial pressure of oxygen and total pressure of the gas phase must increase as compositions change from the W-Co binary toward the oxygen apex and as temperatures increase. has been initiated which is directed at providing some of this fundamental information through a study of metal-tungsten-oxygen reactions and equilibria and the properties of any intermediate phases which result. This paper is based on a part of this program in which the system Co-W-O was studied between 1000° and 1700°C. I) RELEVANT INFORMATION FROM THE LITERATURE A) The Notable Lack of High-Temperature Work on Metal-Tungsten-Oxygen Systems. It should be pointed out that there has been no published report (of which we are aware) which deals with the study of a metal-metal-oxygen system at 1700°C. Also, there has been no report on a complete metal-luugsten-oxgen system at any temperature. As a matter of fact. before this program started. The

Jan 1, 1965

By H. W. Hitzrot, R. H. Limons, L. V. Fegan

The testing of a new method for measuring pellet-bed temperatures in the traveling-grate or shaft furnace is presented in this paper. This method, using silver-palladium alloy wires as indicators, overcomes disadvantages existing in the methods based on the use of thermocouples which are costly and time-consuming. The authors have developed and tested a new method for measuring pellet-bed temperatures in the traveling-grate or shaft turnace through the use of silver-palladium alloy wires as indicators. This method overcomes the disadvantages of existing methods, which, based on the use of thermocouples, are generally costly and time-consuming. For example, in the case of the traveling-grate furnace, the installation of an instrumented pellet, together with its attached thermocouples, requires stopping the furnace, with resulting loss of production time. As for temperature measurement in the shaft furnace by the existing method, the movement of the shuttle-car feeder seriously interferes with both the actual insertion and the resulting distribution of continuously fed thermocouples. The authors have overcome these difficulties by using, as temperature indicators, a range of silver-palladium alloy wires that can be easily recovered, after firing at any desired location in a pellet furnace. Silver-palladium wires having specific melting points from 2000°F to 2500°F are enclosed in ceramic capsules. Each capsule is placed in a ni-chrome wire basket filled with a sample of green pellets, the baskets being the means for recovering the capsule after firing. After the encapsulated wires have been exposed to the firing cycle, the alloy wires are examined to determine the maximum temperatures attained by the pellet sample. This method gives accurate, rapid determinations of maximum temperatures attained during pellet induration in either the traveling-grate or shaft furnace The new method has the following advantages over existing methods: 1) it is less expensive; 2) no furnace downtime is required; 3) the testing units can, be made in quantity in advance; 4) measurements can be made in rapid succession at all desired locations; 5) measurements of maximum firing temperatures are more accurate; 6) on the basis of points 4 and 5, the new method gives a more reliable picture of the correlation of pellet quality, petrographic textures and maximum temperatures, thus providing a more effective quality-control tool. A disadvantage of the method is, of course, that the measurements are not continuous and only maximum temperatures are determined. TEST PROGRAM Preparation of Materials: CALIBRATION OF ALLOYS - In the following discussion the term "bead point" (see Fig. 1) refers to the temperature at which each alloy begins to melt and form a bead. Fig. 2 gives the bead point curve for silver-palladium alloys. Before the alloys are used in plant tests, the bead point of each alloy should be determined in the laboratory to verify the alloy compositions. Once a given alloy has been calibrated, it can be

Jan 1, 1965

By W. V. Green

Creep of tantalum was measured at temperatures from 0.6 to 0.89 of the absolute melting temperature. The creep curves include first, second, and third stages. Steady-state creep rate depends on the fourth power of stress. The activation energy for creep throughout this temperature range is approximately 114 kcal per mole, measured by the aT technique. Subgrain formation occurs as a result of creep strain, and pile-up dislocation arrays are observed in etch-pit patterns. BECAUSE of its high melting point-which is exceeded only by those of rhenium and tungsten—and its high room-temperature ductility compared to most of the other high-melting-point metals, tantalum will undoubtedly be utilized in an increasing number of high-temperature applications. Alloying studies directed toward increased high-temperature strength must use data on tantalum itself as a base line in order to evaluate the effectiveness of the alloying additions. However, to date, no systematic study of creep of tantalum at temperatures above one-half of its melting point has been reported in the literature. Conway, Salyards, McCullough, and Flagella1 have measured linear creep rate of tantalum sheet as a function of stress, but at only one temperature, 2600°C. This paper describes a relatively thorough study of the high-temperature creep of tantalum. METHOD Material Tested. The commercially supplied, l/2-innch-diameter tantalum rod used for this work was electron-beam-melted, cold-forged, rolled, swaged, cleaned chemically, and vacuum-annealed for 1 hr at 1000°C, all by its manufacturer. The vendor's analysis included 60 to 170 ppm C, 3.4 to 4.2 ppm H, 60 to 80 ppm 0, 15 ppm N, and a hardness ranging from 66 to 81 Bhn and averaging 76 Bhn. Creep eimens Used. Two creep-tested specimens are shown in Fig. 1. The 1/4 in.-diameter gage section was 3/4 to 1 in. long, and terminated either at shoulders 5 mils high or at 20-mil-diameter tantalum wires spot-welded to the circumference of the gage section. Both kinds of shoulders served equally well as fiducial marks for optical strain measurements. The spot welding did not alter the creep behavior in any detectable way; the 5-mil- high sharp shoulders did not result in any detectable localized effect on the strain. Before testing, each tensile bar was first mechanically polished -id then electrochemically polished according to the method referred to by Forgeng2 as the "Thompson Ramo Woolridge" method, which was suitable for tantalum after small adjustments of technique were made. Two tensile bars tested at low stresses had 1/8-in.-diameter gage sections and utilized only the weight of the bottom grip for the applied load. Although these diameters were smaller than were desired for other reasons, applied loads were known with high precision in the tests in which they were used. Testing Procedure. Two different constant-load creep-testing machines were employed, one of which has been described by Smith, Olson, and Brown.3 In both, the tensile bar is held vertically on the axis of a cylindrical tungsten tube or screen heater by threaded tungsten grips. The tensile bars and associated grips are heated by radiation from the incandescent heaters, which are heated by their own electrical resistance. Both testing machines use pins to hold the bottom grips in place. The load is applied to a tensile bar through hanging weights, a constant force-multiplication lever, a pull rod sealed to the chamber lid, and a top grip threaded to the pull rod at one end and to the tensile bar at the other. In one machine, the vacuum seal is a bellows with a low spring constant; in the other, the seal involves a rotating "0 ring". With the latter, rotation is converted to translation with a crank shaft, so that elongation of the tensile bar is accommodated with no change of tensile load. The incandescent tensile bar is viewed by an external optical system through slots in the radiation shields and heater, and an enlarged image is projected on a ground-glass screen. Gage-length measurements are made on this image with cathetometers on traveling microscopes. With regard to creep-test results, the two machines were identical. Thorium oxide coatings were applied to the threaded ends of the tensile bars, to prevent diffusion welding of the tensile bars to the grips during testing. Specimen temperatures were measured with an L. & N. optical pyrometer which had been calibrated against a standard carbon arc, and were corrected fir window absorption by calculation from the measured spectral transmittance of the quartz observation windows. Longitudinal temperature gradients in the tensile-bar gage length and temperature drifts during testing were detectable but small, and were estimated to be 10°C or less. Accuracy of temperature measurement was confirmed by comparing the temperature measured on the surface of a special

Jan 1, 1965

By A. K. Chakravarti, A. Lihiri, G. G. Sarkar

One primary objective of India's third Five Year Plan is the expansion of coal production. The goal: boost present output of 45 million tons to 95 million tons by 1965--an increase of more than 100 pct!

Jan 7, 1961

By Frank G. Breyer

C ONDITIONS have not been favorable for new developments in any line. It has been a period, how- ever in which recent developments have been subjected to the severest tests. Those which have been able to hold their own in the severe competition of 1932 must be considered fully proved commercial processes. The continuous vertical-muffle retort plant at Palmer- ton is reported to have been in operation at practically full capacity throughout the year. The high quality of metal produced and the low operating costs are factors which have kept this plant running when many of the older furnaces were shut down. The plant at Meadow- brook, W. Va., is also reported to have been in steady operation throughout the year. Average retort life is said to be better than two years with about three-quarters of the original retorts still in operation after 2 ½ years.

Jan 1, 1933

By Frederick Jr. Prime

THE first catalogue of Geological Reports of the United States was prepared by Prof. O. C. Marsh, and published in the American Journal of Science and Arts for 1867, vol. xliii, second series. Since then the list has more than doubled, and it was thought that the publication of a new catalogue, brought down to date, would be useful to many of the members of the Institute of Mining Engineers. The compiler will be most thankful to have any omissions or inaccuracies in the list sent to him, to be published as a supplement in the next volume of the Transactions. Especially to have the correct title, number of pages, plates, and maps of any volume on the list to which an * is prefixed, as he has been unable to personally consult such works. A preliminary list was issued last February, which has been almost doubled by the kindness of many friends. The writer desires more especially to express the obligations he is under to the following gentlemen The Chief of Engineers, U. S. A.; Principal Dawson, Mr. G. M. Dawson, Drs. B. J. Harrington and T. Sterry Hunt, of Montreal; Mr. H. Engelmann, of La Salle, Ill.; Dr. F. V. Hayden and Prof. J. W. Powell, U. S. Department of the Interior ; Prof. E. W. Hilgard, University of California; Prof. Henry Y. Hind, Windsor, N. S.; Prof. C. H. Hitchcock, of Dartmouth College; Mr. Henry A. Holmes, State Librarian, Albany; Maj. Jed. Hotchkiss, Staunton, Va. ; Prof. W. C. Kerr, Raleigh, N. C.; Dr. J. S. Newberry, of Columbia College ; Prof. W. H. Pettee, of the University of Michigan ; Dr. Samuel H. Scudder, Prof. N. S. Shaler, and Prof. J. D. Whitney, of Harvard College ; Mr. Sanderson Smith and Prof. J. J. Stevenson, of New York ; Mr. Addison Van Name, of Yale College, and Lieut. Geo. M. Wheeler, U. S. Engineers. PHILADELPHIA, 907 Walnut Street, October 1st, 1879.

Jan 1, 1879

By H. F. Ramstad, F. D. Richardson

The equilibria (a) SiOz +Hz =SiO +H20 and (b) Si + SiO, = 2Si0 have beet1 studied at temperatures of 1425"to 1600°C ad 1310°to 1485°C respectively. The stattdard free energy changes for the tzrro reactions are given by the equatiotts Combination of the results for both equilibria leads to tiotz removes certain anomalies in existing high-terlzperature data for equilibria involving silica and silicon in iron. In many metallurgical processes and in many laboratory investigations silicon monoxide undoubtedly plays an important role. It is unfortunate therefore that wide differences exist between the results obtained by different investigators1-7 in their studies of such equilibria as In an attempt to put our knowledge of SiO on a surer basis, an exhaustive study has been made of equilibria [I] and [2] at temperatures ranging from 1300" to 1600°C. Reaction [I] was studied by measuring the amounts of silica which could be condensed from streams of Hz or Hz + HzO which had previously been brought into equilibrium with silica at temperatures ranging from 1425" to 1600°C. Reaction [2] was studied by measuring the material that could be condensed from streams of Hz or argon which had been brought into equilibrium with mixtures of silicon and silica at temperatures ranging from 1310" to 1485°C. EXPERIMENTAL Materials. The silicon was "superpure" grade and contained less than 0.1 pct impurities. The silica was prepared from pure mineral quartz; this was crushed and treated with concentrated hydrochloric acid to remove particles of iron, washed with water, and finally dried at 120°C. For the hydrogen + silica reaction, the silica was sized to —20+100 mesh. For the silicon + silica reaction, the two materials were ground to a fine powder in an agate mortar. The hydrogen and argon were commercial oxygen-free gases. The gas streams were controlled with capillary flow meters and the volumes were measured by wet gas meters. After passing through the meters, the gases were partially dried by silica gel. The hydrogen for the HZ + SiOz reaction was then passed through palladised asbestos at 300°C and dried with magnesium perchlorate. The efficiency of oxygen removal was checked throughout the experiments by passing the gas over an electrically heated strip of nichrome, used as an indicator as described by Rathman and de itt.' When mixtures of HZ + Hz0 were required, the partial pressures of water vapor (1.8 to 22 mm) were obtained by passing the hydrogen through oxalic acid dihydrateg' lo held at various controlled temperatures, O.l°C, by means of a water bath. The hydrogen for the Si + Si02 reaction was purified by passing it over a mixture of 3 parts of magnesium to 5 of lime heated to 600°."l1 u The argon for this reaction was passed through titanium powder (-3/16 in. + 100 mesh) heated to 900°C. The nitrogen used to prevent the reaction products escaping from the condenser (see later), was deoxidized by copper or iron at 600°C. All these gases were finally dried with magnesium perchlorate. Furnace, Temperature Contr01, and Measurement A molybdenum resistance furnace was used for both sets of experiments. The reactions were conducted inside a high-grade alumina tube, 36 in. long and 1 in. in diam as indicated in Fig. 1. With this arrangement an even temperature zone (2"C) 4 cm long was satisfactorily obtained. The temperatures were kept constant by means of a proportional controller actuated by a Pt-Pt 13 pct Rh thermocouple. This was placed between the two alumina tubes, so that the temperature at the junction was 1400" to 1450°C. Up to 1485"C, the temperatures were measured with Pt-Pt 13 pct Rh thermocouples. For higher temperatures an optical pyrometer was used, this being sighted (through the glass window 1 in Fig. 1) on the end of the alumina tube, that held the SiOz or Si +SiOz mixture, 10 in Fig. 1. The optical pyrometer was recalibrated whenever a change was made in any part of the apparatus situated in the hot zone. Successive readings with the optical pyrometer were reproducible to within 1"C. Equilibrium Apparatus and Procedure. Hydvogen and Silica Reaction. The apparatus is shown in Fig.

Jan 1, 1962

By G. C. Kuczynski

Two particles in mutual contact form a system which is not in thermo-dynamical equilibrium, because its total surface free energy is not a minimum. If such a system is left for a certain period of time, the bonding of the two particles will take place in order to decrease the total surface area, even though the temperature is lower than the melting point. This phenomenon of bonding of two or more particles with the application of heat only and at temperatures below melting point of any component of the system will be called sintering, although the powder metallurgists use this term in a broader sense, including the presence of molten phase and pressure. It is the objective of this paper to study this process and the mechanisms involved in it. This problem is of utmost importance to powder metallurgy and powder ceramics, and its technological aspects have been studied for a good many years. However, the powder metallurgical operations are too complex and include too many superimposing mechanisms, and too many variables for a direct study. It was therefore advisable for the purposes of this study to reduce the variables to a minimum. In this work the radius of the interface formed during bonding in a simple system composed of a spherical particle and a large block of the same metal was studied as a function of time and temperature. It is believed that the mechanism involved in this simple process is fundamental to any sintering operations. Previous Work J. Frenkell was the first to make a serious attempt to develop a theory of sintering. He assumed that the process consists of a slow deformation of crystalline particles under the influence of surface tension which reduces to a viscous flow where the coefficient of viscosity n is related to the self-diffusion coefficient D by the following equation 1 _ D D6kT [1] where 6 is interatomic distance, k the Boltzman constant, and T the absolute temperature. This type of viscous flow of a crystalline substance is essentially different from the ordinary plastic flow. The latter is a specific propcrty of crystals and cannot take place in amorphous bodies. According to Frenkel this viscous type of flow is due to the diffusion of the holes or vacancies arising in the lattice. He was able to derive an equation relating the growth of the interface between two spherical crystalline particles or between a particle and a semi-infinite crystal (Fig 1) to time t at constant temperature. This relationship can be written as follows: x²— 3/2 a/nt [2] where x is the radius of the interface assumed to be circular, a the original radius of the sphere and a surface tension of the material. The other assump- x tions are that x is less than 0.3 and that during the period 1 the original radius, a, of the metallic particle did not change appreciably. A. J. Shaler and J. Wulff2 followed closely the ideas of Frenkel in their theory of sintering of a mass of metallic powder. Neither Frenkel nor Shaler has validated his theoretical speculations with conclusive experimental data. Two measurements reported by

Jan 1, 1950

By H. L. Riley, B. W. Gandrud

AS far as the present writers know, this system of flotation has not been used elsewhere in this country, but in the last couple of years it has been introduced, with minor variations, at one plant in England and one in Wales.' The system has been described and discussed in a number of publications.2-5 The following is quoted from an abstract of the latest of these,5 a paper presented at an International Conference on Industrial Combustion in 1952. On the basis of experience to date with the commercial plants, it is believed that the kerosene-flotation process incorporates all the necessary elements to make it greatly superior to anything else now available for treating of fines in wet processes of coal preparation. Additional study and investigation are still needed, however, to determine if certain phases of the process can be improved to such an extent as to make it generally satisfactory and acceptable to the industry. Further improvements will be needed with respect to the capacities of the flotation cells and the reagent consumption. The situation referred to above explains why an investigation is being made of the possibilities of achieving better cell capacities. Results obtained from this investigation, which is still in progress, are believed significant with regard to both cell capacity in general and the relation of cell design to cell capacity in particular. Commercial equipment now being used in a laboratory-type investigation should have performance characteristics similar to those of the larger machines. Equipment and Procedures: All flotation tests have been made in a standard Denver sub-A 24x24-in. unit cell of 12-cu ft volume. Cell modifications to make it more suitable for the tests were an adjustable front-wall section for varying cell depth and a perforated scraper-drag assembly for removal of the float product. There is also an apron dry-coal feeder, a gravity-feed water supply, reagent feeders, and a centrifugal pump that feeds the mixture of coal, water, and reagents into the flotation cell. A wattmeter connected into the drive-motor circuit records the power requirements of the impeller throughout each run. Dry coal, water, and reagents are all fed through a pan-type intake to the feed pump. A Sturtevant blower was set up to furnish air for supercharging. A centrifugal pump with a garbage-can intake provides for disposal of refuse flow to an outside settling tank. Figs. 1 and 2 show the flotation cell; Fig. 2 also illustrates the blower for supercharging. For purposes of this investigation, the percentage by weight of the feed coal recovered in the float product under a standard set of conditions has been considered as the criterion of cell capacity. The authors realize that such a criterion may be somewhat unorthodox, as the term cell capacity is usually understood to refer to feed input and ordinarily takes into account the ash analyses of the float product and refuse. However, the word capacity is flexible enough so that Webster gives one definition as maximum output, a definition which seems to justify, at least partly, acceptance of the above criterion. It has been the authors' experience in the Birmingham district that the ash-reduction efficiency of the coal-flotation process is generally satisfactory and that the only real problem is to increase the rate of float recovery so that the feed rate to any given bank of cells can be increased without undue loss of coal in the refuse. Originally it was planned to operate the flotation cell to simulate continuous operation during sampling periods. It was assumed that operating for reasonable time with feed coal, water, and reagents turned on would stabilize conditions so that the weight of float coal discharged during a fixed time interval would be an accurate measure of the rate at which the coal was being floated. It developed, however, that this supposition was erroneous. The float coal, caught for fixed time intervals and weighed, gave widely varying results in duplicate runs. Efforts to correct this trouble failed, and it was decided to try to operate on a batch-test basis, whereby all the float coal produced during a run on a known weight of feed coal would be caught in tubs, dewatered, and weighed. This method gives consistent and reproducible results, with total float product weight rarely varying by more than 3 or 4 pct on duplicate runs. The standard test procedure is as follows: A 132-lb sample of dry feed coal is weighed and placed in the feed hopper. The feeder is adjusted for a rate of 800 lb per hr. Feed water and reagents are turned on, and the feed and refuse pumps are started. One minute later the impeller is started. Six minutes are allowed for the cell to fill up with the water-reagent mixture. The feed of dry coal is started at the end of this 6-min period. One minute later the float-coal removal drag is started. The float coal is caught in one tub for the first 6 min after the flow of feed coal starts. Tubs are then changed, and the float coal is caught in a second tub until the feed coal runs out, when the tubs are again interchanged to catch the float coal for the remainder of the run in the first tub. The cell is kept running for 3 min with the water and reagents on after the feed stops to allow residual float coal to be removed. At the end of a test the wet float coal in both tubs is weighed and the total weight recorded. The product in the second tub is used for moisture determination and screen-size analyses. When the

Jan 1, 1956

By A. H. Larson, R. J. McClincy

Laboratory-scale decopperizing experiments with multiple sulfur addifions were conducted at 330°C on ternary Pb-Cu alloys containing, as the third elenlent, Sn, Ag, As, Sb, Bi, Zn, and Au, common impurities in lead blast-furnace bullion. For silver and tin, an increased rate and extent of 'cofifier removal was obsert3ed. The elements As, Sb, Zn, Au, and Bi had no effect or less effect as compared to sulfur additions with no i)npurily additions. THE production of primary lead in the blast furnace yields an impure lead frequently containing such impurities as copper. antimony. arsenic. tin, gold, silver iron, oxygen. and sulfur. By cooling this lead to a temperature near its melting point. most of the iron, sulfur, and oxygen and part of the other impurities are removed in the form of a dross. With incipient solidification of the lead, the copper concentration wil have been reduced to 0.02 to 0.05 pct. depending upon the concentration of the other impurities. according to Davey.' Since copper interferes with the treatment of silver after the desilverizing process, it is desirable to decrease the copper content of the lead still fur-ther before the lead is desilvered. The decopperizing of the lead is accomplished by stirring a small quantity. approximately 0.1 pct. of elemental sulfur into the lead at a temperature near its melting point, 330" to 360°C. The copper is removed as a copper sulfide which constitutes a small fraction of a voluminous dross consisting mostly of lead sulfide and entrained metallic lead. The residual copper concentration following the decopperizing operation is frequently as low as 0.001 to 0.005 pct. Thi fact has aroused considerable interest because the equilibrium copper concentration of lead in contact with solid PbS and solid Cu2S is at least an order of magnitude greater, 0.05 pct Cu at 330C. 1, 2 Most investigators have suggested that various impurities in the lead bullion are responsible for the very low copper concentrations frequently encountered in practice. There is little agreement, however? as to which of the impurities are helpful and which are not.3"11 Also. few investigators have sought to explain the mechanisms responsible for the removal of copper to very low concentrations. Willis and Blanks9 have proposed that a nonstoichiometric copper-deficient cuprous sulfide forms in place of the supposed Cu2S. Being copper-deficient, this sulfide phase would possess a low copper activity, and the diffusion of copper dissolved in the liquid lead into this phase would be greatly facilitated. Pin and wagner2 have investigated the removal of copper from liquid lead by studying the effect of impurity-doped lead sulfide on the decopperizing of pure Pb-Cu alloys. Samples of the doped PbS were held in contact with copper-saturated lead for 1 week at 33'7°C. They reported a beneficial effect on decopperizing with bismuth and antimony and no effect with tin or silver. which is directly opposite to the results observed in practice and those reported by Davey 3 and this studv. The purpose of this paper is to describe the effects of certain additive elements on the extent to which copper can be removed fro111 liquid lead by successive additions of sulfur. The impurity elements were added individually to prepared Pb-Cu alloys. The resulting ternary alloys as well as a binary Pb-Cu alloy were then decopperized with repeated additions of sulfur. EXPERIMENTAL Materials. Granulated test lead with a purity of 99.999 pct and the additive elements Cu. Ag. Sb. Bi. Zn. Sn. and Au with purities of 99.99 pct were American Smelting and Refining Co. research-grade materials. The major impurities in the lead were 1 ppm each of iron and copper. all others being less than 1 ppm. The arsenic used was a technical-grade arsenic of 98+ pct purity. Reagent-grade flowers of sulfur were melted under argon to provide small pieces free of fines. Apparatus. The decopperizing experiments were carried out in a 25-mm-OD by 375-mm-long Pyrex tube sealed at one end. The tube was mounted vertically in a resistance-heated. hinge-type tube furnace controlled to within ±lcC. Temperature measurement was accomplished by means of a standardized chromel-alumel thermocouple sealed into the base of a silica. paddle-type stirring rod. All decopperizing experiments were carried out under an argon atmosphere. Procedure. A Pb-Cu starting alloy containing 0.05 pet Cu was prepared under carbon and poured into cold tap water to produce shot. The ternary alloys were prepared by melting together 100 g of the starting alloy and a sufficient amount of the impurity element to yield the desired concentration. The resulting alloy was then homogenized in a Pyrex tube at 450C with continuous stirring. The furnace temperature was then lowered to the operating temperature of 330°C. When thermal equilibrium had been obtained at the operating temperature, individual additions of 0.2 pct (0.2 g) of solid sulfur were added to the melt and stirred in. Stirring was continued for a period of 3 min. discontinued for 5 min. and resumed for the remaining 2 min of a 10-min cycle. This cycle was repeated for as many sulfur additions as desired. When the decopperizing experiment had been completed the lead bullion was quenched and samples of the bullion and dross phases were taken for analysis. Results. The results obtained in the decopperizing

Jan 1, 1970

By H. Case Willcox

AERIAL photographic surveying and mapping is not new or unknown to geologists. However, it has been utilized but little before, principally because it is only within the last few months that practical means of adapting this method to the requirements of petroleum companies have been discovered. No American aerial survey company has taken up aerial surveying and mapping as an engineering service to be offered to petroleum companies and their geologists for use in undeveloped and jungle-covered petroleum areas. This method of surveying and mapping, however, is used by the War Department, the U. S. Reclamation Service, and Geological Survey, and the corresponding Departments of the Canadian Government. ADVANTAGES OF AERIAL PHOTOGRAPHIC SURVEYING AND MAPPING The advantages of aerial photographic surveying and mapping to petroleum companies and their geologists are many. One of the most valuable is presented in the very first phase, or the exploration period. It is assumed that, when convinced that petroleum possibilities are present, a petroleum company has secured a concession of 8000 sq. mi. of unexplored area in Eastern Venezuela. The company may either have the entire area surveyed and mapped by the aerial photographic method, or send its chief field geologist up in an airplane so that he, from-an aerial reconnaissance, may reject certain portions that, for geological reasons, the company would not be interested in. He will then point out the regions that are to be surveyed and mapped. After the air-work is completed, the results are brought down, developed, and printed; then the resulting "contact prints" are given to the field geologist. They may be roughly assembled to give a general idea of the property in its entirety, or they are in shape to be examined in adjoining pairs under the stereo-scope. With this instrument, the geologist is enabled to make a minute examination of surface indications. The work of assembling and constructing a complete general or detailed map, according to the scales desired by the petroleum company and for the later office use, is continued by the aerial photographic company.

Jan 3, 1925