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By Benjamin S. Lindsey, James Norman

Barite (BaSO4) is the most important industrial barium mineral from the standpoint of quantity consumed. In 1938 the amount was 365,000 tons. Its uses are numerous, some of the more important being in the production of pigments, as an inert filler in a wide variety of products, as a weighting material in oil-well drilling muds, in the manufacture of some binds of glass, and in the production of barium chemicals. The barite studied in this investigation occurs as the massive variety in a shale replacement formation near Magnet Cove, Ark. It is intimately mixed with quartz and small amounts of iron oxide and residual shale. Complete liberation of barite and quartz is not obtained when the rock is ground to I00 per cent through 325 mesh. The crude rock with which all test work was done assayed 85.1 per cent BaS04, II.II. per cent SiO2, and 2.85 per cent R2O3. Its specific gravity was 4.03. It was found in the course of the investigation that the barite contained a small amount of uniformly distributed carbonaceous material, so intimately dispersed that it could not be seen with the microscope, but gave a definite gray cast to the barite concentrates. The color of the barite in polished sections of the crude rock ranged from gray to almost black, while finely ground powder was a reddish gray. The reddish hue was due to the iron oxide present. In 1939, under the supervision of Oliver C. Ralston,* the Bureau of Mines, in cooperation with the Milwhite Company, of Houston, Texas, undertook to study the flotation of barite from Magnet Cove, Ark. Flotation of several southern barite ores had already been investigated by the Bureau of Mines.' The Magnet Cove barite was unique, however, in that it had to be ground to such an extremely small particle size for liberation. The flotation of non-metallic minerals in the presence of a large amount of slime is usually very difficult, and when done is an innovation calling for conditions different from those under which granular material is separated. Laboratory Flotation Work Preliminary investigation showed that the flotation reagents recommended by O'Meara and Coel for separating barite and siliceous material were suitable, but much larger quantities of reagents were required to separate such finely divided material. Moreover, it was found that careful control of the frothing was necessary. When oleic acid and sodium silicate were used a voluminous froth was observed at the beginning of a test, and toward the end there was not enough froth to effect complete recovery of barite. The addition of pine oil as a frother gave proper frothing for the duration of the test, and the substitution of coconut fatty acid (crude lauric acid) for oleic acid produced a more heavily burdened froth. Two different paper-mill fatty-acid products were tested

Jan 1, 1943

By A. N. Mitinsky

Discussion of the paper of A. N. MITINSKY, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1697 to 1705. LAWFORD H. FRY, Burnham, Pa. (communication to the Secretary*). -The author assumes that the proportional limit and the elastic limit are coincident or very nearly so, and then further assumes that the stress corresponding to these two points is the least stress which if repeated will cause failure. The point is extremely interesting and it is to be regretted that the author did not quote experimental data to show the relation between the limit of repeated stress and the other properties of the material. The author's suggestion that a steel of poor quality may have a normal value for the yield point and tensile strength (see Fig. 2) and an abnormally low elastic limit, and that this will correspond to a low resistance to repeated stress, may account for a number of failures of axles in which the tensile tests show normal physical properties. If so and if a determination of the proportional limit would have eliminated the material before it was put into service, this determination will merit most earnest attention. It appears, however, that considerable further research is necessary before any definite conclusion as to the quality of a steel can be drawn from its proportional limit. Mr. Mitinsky's paper is extremely interesting and if it stimulates thought and work along the lines indicated, it may prove of considerable practical benefit. H. V. WILLE, Philadelphia, Pa.-The paper discusses the difference between the proportional limit, or elastic limit, and the yield point, and refers to the fact that much harm results from confusion of the terms yield point and elastic limit. Similar confusion has arisen in this country; the American-Society for Testing Materials does not even consider the elastic limit and proportional limit to be identical and recently adopted the following definitions:

Jan 12, 1915

By K. M. Kolobova, E. Z. Kurmayev, A. Z. Menshikov, S. A. Nemnonov, V. A. Trapeznikov

The present work represents a review of our intestigations into the X-ray spectra of solids, which have been carried out by us along two lines of upproach: 1) St@ of the electronic structure of high -rnelting compounds of transition metals; 2) stzddy of the interatomic binding forces by the fine structure of absorption spectra under varying temperature and concentration conditions. With this in mind, int>estigations hare been made into the emission and absorption spectra of the K-series of atoms of transition elements in alloys and compounds. In the problem concerned with the electronic structure of high-melting compounds of transition metals, considerable importance is attached to the question of ascertaining the role played by 3d4sp electrons of metal and 2p electrons of metalloid in the formation of chemical bonds and of giving, on the strength of this data, an explanation of the properties which seem to be contradictory at first sight: good conductivity inherent in metals and high brittleness and high-melting characteristics typical of covalent compounds. Over the last few decades this question has attracted the attention of many investigators whose studies were devoted to this type of compound. Many works, both of theoretical1-3 and experimental4- l5 nature , have contributed much to the elucidation of the physical character of the phenomenon referred to. Alongside the investigations in the field of electric resistance, Hall effect, paramagnetic susceptibility, electronic heat capacity, and the temperature of transformation into a superconducting state, we should particularly emphasize the studies on X-ray spectra, which have played a significant role in the development of the zonal theory for high-melting compounds. This fact has become highly evident after the theoretical calculation of the energy spectrum has been made and the density of states curve in Tic, TiN, and Ti0 has been plotted by Ern and Switendick3 who used the method of augmented plane waves. Correlation of the results of the theoretical calculation of the band structure in the compounds listed above with the data obtained by X-ray spectroscopy studies showed that X-ray spectra can be a source of valuable information on the electronic structure of high-melting compounds within a wide range of ener- gies. It is well known that X-ray emission spectra basically give a direct picture of the occupied excited states above the Fermi level of a solid (valence band, conduction band) and that the absorption spectra (region of initial absorption) give a similar picture of states corresponding to the unoccupied levels near the Fermi surface. Full information on the density distribution of electronic states by energies can be obtained by combining the emission and absorption spectra. Such an opportunity arises from investigation

Jan 1, 1970

By Edward B. Durham

The refinery at the San Francisco Mint takes the bullion purchased by the receiving department, and carrying Illore than 200 parts of precious metals in 1,000, or, in mint parlance, over 200 fine, and separates and refines the various metals contained therein, using electrolytic processes exclusively. Bullion containing silver is treated in cells charged with a nitric electrolyte. These cells produce fine silver and leave a residue rich in gold. The residue from the silver-cells, together with crude gold-bullion, is treated in cells having a chloride electrolyte. These produce fine gold and leave a residue containing silver chloride. The latter is reduced to the metallic state with zinc and is then treated in the silver-cells. The various waste solutions and the wash-waters, after being freed from the bulk of their precious metals, still contain copper and other metals. These are removed by scrap-iron, and are then treated in the copper-cells, having a sulphate electrolyte. These cells produce pure copper, and collect a residue containing lead, some gold and silver, and all the metals of the platinum gronp that were in the bullion. This residue is relatively small, and is melted into bars and stored until suEcient accumulates to warrant treating it for platinum, etc. The refinery occupies three large and three small rooms. The large ones are, a melting-room, 30 by 34 ft.; a cell-room, 39 by 46 ft.; and a wash-room, 30 by 33 ft. The small rooms are used as foreman's osce, laboratory, and , re- spectively. The methods here described are those in use in December, 1909, when notes for the present paper were taken.

Jan 1, 1912

By C. Norman Cochran, James L. Brandt

ALTHOUGH gas in aluminum and its effect on aluminum products have been the subject of a number of papers, not many quantitative determinations of the hydrogen content of solid aluminum and its alloys have been recorded in the literature. For solid aluminum samples, four investigators have reported hydrogen contents which appear reasonable compared with the hydrogen solubility of 0.7 ml per 100 g, STP, in molten aluminum at 660°C established by Ransley and Neufeld' and verified by Opie and Grant' and Ransley and Talbot. Sloman," who used a vacuum fusion procedure, reported the hydrogen content of some high purity aluminum as 0.66 ml per 100 g, STP. Griffith and Mallett, employing the tin fusion method, reported the internal hydrogen content of six different aluminum alloys as ranging from less than 0.1 ml per 100 g, STP, for 1100 alloy to 0.7 ml per 100 g, STP, for 4043 alloy (previously 43S, a 5 pct Si alloy). Eborall and Ransley," using a solid extraction of the gases at 600°C, reported hydrogen contents ranging from 0.1 ml per 100 g, STP, to 1 ml per 100 g, STP. Ransley and Talbot reported that several thousand analyses on 99.2 pct and higher purity aluminum as well as Duralumin type alloys indicated hydrogen contents ranging from 0.1 ml per 100 g, STP, to 0.5 ml per 100 g, STP.

Jan 1, 1957

By I. R. Kramer

A delay time for yielding in cold-worked face-centered-cubic metals was found. Slip on (123) planes was observed. Glide on these planes occurred during the delay-time period before slip starts on the (111) planes. AN important approach to the study of the anchoring and blocking of dislocations is available through the delayed-yield phenomenon which has been observed in body-centered and hexagonal close-packed metal by several investigators. Clark and his associate1-5 showed that a delay time for yielding is present in mild steels and fine-grain molybdenum. Type 302 stainless, SAE 4130 normalized, SAE 4130 quenched and tempered, and 24s-T aluminum aid not have a delay time. Kramer and Maddin6 studied the delay-yield effect. in metal single crystals. While they found a delay time in body-centered-cubic metals none could be found in the face-centered-cubic metals. Later7 a delay time was found in hexagonal close-packed metals. cottrell8 has proposed an explanation for the difference in the yield phenomena of b.c.c. and f.c.c. metals based upon the anchoring of edge dislocations by the proper types of impurity atoms (C and N). In the body-centered-cubic lattice the interstitial atoms are near a cube edge and can interact with an edge dislocation, while in a face-centered-cubic lattice the distortion around an interstitial atom is of spherical symmetry and cannot anchor a screw dislocation which has practically no hydrostatic component. Cottrell's theory seems to account rather well for the behavior of body-centered-cubic . metals. EXPERIMENTAL PROCEDURE The apparatus used in these experiments is essentially of the same design as described previously.' Single crystals 1 in. long and having a diameter of % in. were placed in a pendulum which consisted of a bar 8 ft long designed with a crystal holder to accommodate the specimen at low temperatures. This portion of the apparatus was supported on fine molybdenum wires. A bar of the same diameter and length comprised the other portion of the apparatus. This bar was supported on a set of roller bearings arranged around the periphery of the bar to allow accurate alignment. This bar was propelled by means of a spring-loaded gun and allowed to strike the lead bar in front of the single-crystal specimen. SR-4 type A-8 resistance strain gages were cemented to the specimen and the strain measurements were obtained by amplifying the strain-gage output by means of a high-gain preamplifier. A tektronix 545 oscilloscope was used together with a polaroid camera to record the strain and time sweep. An Ellis Associate Bridge was used to calibrate the strain gages and calibration readings were obtained before each test. The sweep of the time signal was initiated by means of a miniature thyraton which was fired when the two bars came into contact. The single-crystal specimens were cut from single-crystal bars about 12 in. long, grown by a modified Bridgman technique. The aluminum crystals were made with material of 99.99 pct purity while the purity of the copper was 99.999 pct. A cut-off wheel was used to prepare the specimens which were then machined to the desired length. The two opposite faces of the specimen were parallel to each other and perpendicular to the axis of the specimen. The specimens were compressed 1 pct. No machining followed thereafter. In some cases prestraining was carried out in liquid nitrogen by impacting the specimens directly in the apparatus so that subsequent observations could be made without allowing the specimen to warm up to room temperature. The single crystals were compressed 1 pct at room temperature in a hand press without much control of the rate of deformation. In some cases specimens were recompressed to obtain the desired length change. As far as could be determined in these experiments this factor did not seem to influence the results. The SR-4 strain gages were glued with a cellulose type cement onto the specimen surface and baked at 45°C for 12 hr. As a check on the baking treatment gages were allowed to dry at room temperature. All delay time tests in this paper were conducted in a liquid nitrogen bath at -195°C. A schematic delay time oscilloscope trace is shown in Fig. 1. At point B the elastic stress wave caused by the impact reaches the strain gage on the specimen. The portion BC is the elastic strain. In this investigation the strain at point C was used to calculate the critical resolved shear stress by multiplying by the proper modulus depending upon the orientation of the single-crystal specimen. The time between C and D is the delay time portion of the curve. This portion of the curve is fairly flat but does have a definite microstrain associated with it. After the point D is reached the specimen deforms rapidly and the strain reaches a maximum at E. Following this, depending upon the length of the bar behind the specimen, the strain remains constant for a period and then decreases when the reflected elastic wave returns from the end of the pendulum bar. A permanent plastic strain is recorded on the oscilloscope trace and also measured by a strain-measuring bridge. The strain, E p,

Jan 1, 1960

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of quartz with oleic acid as collector and barium, calcium, aluminum, iron, and tin as activators were studied using a simple vacuum-flotation technique in glass-stoppered graduates. The detailed study of barium activation led to an interpretation based on ideal Langmuirian chemisorption.

Jan 5, 1950

By M. J. Duggin

Structural similarities between the E, X, and iron carbides are illustrated. Experimental evidence regarding phase transformations occurring during ternpering reactions in finely divided carbides, thin-film carbides, and carbides which occur in steels is considered and possible mechanisms for the E — x and x — 9 transformations proposed. HOFER1 has shown that within the appropriate temperature ranges carbon monoxide will react with finely divided a iron to form either iron carbide or x iron carbide. He has shown that at an elevated temperature the E iron carbide will transform to the x iron carbide (Hagg carbide) which, upon further elevation of temperature, will transform to 9 iron carbide (cementite). Jack,2,3 using X-ray diffraction methods, has observed that during the tempering reactions occurring in steel the E iron carbide formed in the first stage of tempering passes into two-dimensional platelets of 0 iron carbide during the second stage of tempering. The three-dimensional form of the 0 carbide is formed during the third stage of tempering. Jack suggested2 that the two-dimensional platelets of 0 carbide could be related to the faulted x iron carbide. Okada and Arata4 investigated a Swedish steel containing 1.05 wt pct C and approximately 1.0 wt pct Mn using permeability measurements at low field strength. A Curie point of 360°C was observed in the quenched steel, which indicated the presence of E iron carbide. On tempering at 400°C the specimen developed a Curie point at 230°C, indicating the presence of x iron carbide, and on tempering at 700°C the specimen developed a Curie point at 190°C which was assigned to 0 iron carbide. The carbides were extracted electro-lytically and the use of X-ray diffraction techniques4r5 indicated the carbide with a Curie point of 230°C to be x iron carbide. The Curie points of the carbides are 10 to 22°C lower than the accepted values which is probably due to the presence of manganese in the carbides, since it has often been observed (e.g., Ref, 6) that a partial substitution of manganese for iron in cementite will lower the Curie point of this carbide. Hofer' summarizes additional evidence of the tempering reactions in steel in which E iron carbide, formed during the first stage of tempering, transforms to x iron carbide during the second stage of tempering. During the third stage of tempering, the x carbide disappears as the 0 carbide is formed. By carburizing thin iron films in a CO gas stream, ~a~akura' has been able to produce the E, X, and 0 iron carbides. He found that below 250°C the E iron carbide was formed; between 250" and 350°C the x iron carbide was formed and above 350°C the 0 iron carbide was formed. He has shown that the E iron carbide transforms to form x iron carbide at 380" to 400°C and that the x ir°n carbide transforms to form the 0 iron carbide at approximately 550" C; both of these phase transformations are irreversible. Hofer' presents a review of evidence to show that the sequence of reactions occurring during tempering processes subsequent to the formation of E iron carbide formed by the direct carburization of finely divided a iron is the same as the sequence of reactions which occur during the tempering processes subsequent to the formation of E iron carbide in steel during the first stage of tempering. It is evident from Nagakura's work that identical tempering reactions are found in thin films of iron which have been carburized to form iron carbide. The purpose of this paper is to discuss the structural similarities between the E, X, and 0 carbides and to suggest a possible mechanism by which regions of the E carbide, formed during the first stage of tempering, may transform to the x carbide during the second stage of tempering. For the finely divided or thin film carbides a mechanism will be proposed for the transformation of the x carbide to the 0 carbide during the third stage of tempering, although it will be suggested that there is evidence that such a transformation may not occur in steels. STRUCTURAL DATA OF THE E, X, AND 0 IRON CARBIDES € Iron Carbide. It is evident from X-ray diffractions and electron diffraction', investigations that the metal atoms in the E iron carbide form an hcp structure with lattice constants ah = 2.752A, ch = 4.3534, using electron diffraction, reports the lattice paramet$rs of the superlattice cell to be a = 4.767A, c = 4.354, c/a = 0.9134. He finds that the carbon atoms occupy the octahedral voids in the metal atom structure so as to form a hexagonal stacking sequence with its basal plane parallel to that of the metal atoms. Considerable long-range disorder occurs in the positioning of the carbon atoms, however, which is in agreement with the possible range of composition Fe2C-Fe3C discussed by Hofer.' Barton and ale" have made X-ray diffraction measurements on a sample of E iron carbide extracted from a catalyst in an organic process. Although there were few reflections recorded on the obtained X-ray powder diffraction pattern, they have proposed that the structure could belong to one of the three possible space groups p3m1, P63/mmc, or Pbcn if one assumed the composition to be Fe2C. Nagakura, using electron diffraction data, suggests a space group of P 6322 for a specimen of c iron carbide of apparent composition Fez.&. x Iron Carbide. The x iron carbide has been studied by Duggin and Hofer" and by Jack and wild,' who

Jan 1, 1969

By C. Stansfield Hitchen

THE introduction of the logarithmic sector method of quantitative spectrography by Scheibe and Neuhäusser in 1928, and the subsequent .modification and improvement of the method by Twyman and Simeon, would seem to have marked yet a further advance in quantitative spec-trum analysis and its industrial application, inasmuch as it offers a simple means of eliminating some of the uncertainties inherent in the older methods based upon mere visual comparison of line intensities. In their recent admirable review of the position and capabilities of industrial spectroscopy, Brownsdon and van Someren1 say: Ways and means of facilitating the comparison of line-intensities so as to give them numerical values are helpful, and of these a logarithmic sector rotating in front of the slit appears to he one of the most promising; . . . the success recently experienced by the author in using this method for the examination of steels and solutions of metallic salts prompted him ,to investigate its possible use in estimating the impurities commonly present in crude and refined tin. The results of this investigation are submitted in the present paper. Details of a number of spectrographic analyses of tin for various impurities have already been published. Thus, Schweitzer2 describes the spectrographic examination of tin for lead, bismuth and cadmium, and was able to distinguish between such atomic percentages as 0.01, 0.05, 0.10, 0.30, 0.60, 1.20, 3.00 and 10.00. Negresco3 investigated the bismuth content of tin over a range of from 0.0005 to 35 per cent. Meggers, Kiess and Stimson4 compare spectrographic and chemical analyses of tin metal for copper, lead, iron, zinc, silver, nickel and bismuth. They stress also the value of spectrum analysis in the examination of tin used for boiler plugs, where the requirements that only minute quantities of impurities shall be present render the chemical analysis both tedious and difficult.

Jan 1, 1933

By F. George, W. Tice, M. Salkind

It was found that Al-A13Ni could be readily cold rolled perpendicular to but not parallel to the whiskers. Reductions of more than 98 pct were achieved without cracking by rolling perpendicular to the whiskers, whereas extensive edge cracking was noted after only 15 pct reduction when rolling parallel to the whiskers. The longitudinal and transverse tensile strengths were nearly doubled, and the longitudinal yield strength more than tripled by cold rolling 50 pct in a direction perpendicular to the whiskers. The whiskers exhibited some waviness (elastic bending) as a result of cold rolling, but at very high reductions (greater than 75 pct) whisker fracture and misalignment became significant. A fine dislocation substructure in the matrix consisting of cells attached to the whiskers was pro -duced by cold rolling. Most of- the substructure was readily removed by a 1-hr anneal at 500°C. Cold rolling was found to substantially reduce the thermal stability of the microstructure at 610°C but did not affect the stability at 500°C. FIBER and whisker reinforced composite materials promise significant improvements in properties over conventional materials. Before they find wide use, however, it will be necessary to understand the response of these highly anisotropic materials to common metalworking processes. Most of the nonmetal-lic fiber reinforced materials have very low elongations (a few pct or less) in the direction of fiber alignment. Thus, metalworking techniques such as rolling and forging would not be as broadly applicable to these materials. This investigation was initiated to determine how a composite system consisting of Al3Ni whisker reinforced aluminum responded to rolling, what changes in the microstructure occurred, and the effect of deformation on the mechanical properties. The composite material studied was produced by unidirectional solidification of the A1-Al3Ni eutectic alloy'-7 and consisted of 10 pct by volume of aligned whiskers of Alai in a matrix of aluminum. It should be pointed out that this system is not representative of all composite materials, and the results will therefore not be universally applicable. The A1-Al3Ni system is characterized by: 1) A strong fiber-matrix interfacial bond 2) A ductile matrix 3) A sufficiently low fiber content to allow significant plastic flow between fibers 4) Strong, completely elastic whiskers (tensile strength 400,000 psi, elastic modulus = 20 X 106 psi.1 These factors allow the material to be readily rolled perpendicular to the fibers. If the fiber-matrix bond were not strong, such a weak interface could fail during rolling. A measure of the ability of a composite to be rolled in the transverse direction can be obtained from noting the transverse tensile behavior. In the case of Al-Al3Ni,2 there is considerable ductility (15 to 30 pct). In the case of boron filament reinforced aluminum, for example, the transverse elongation is less than 1 pct,8 and the material could probably not be cold rolled as readily in that direction. EXPERIMENTAL PROCEDURE 3-in. diam ingots of A1-A13Ni eutectic were unidi-rectionally solidified in graphite crucibles. The starting materials consisted of 99.99+ pct pure nickel and aluminum, and the pure eutectic ingots were made with 6.2 wt pct Ni. The unidirectional solidification process (described in detail elsewhere1-3) consists of preparing a master heat of eutectic composition, remelting, and withdrawing the ingot vertically downward through the heat source at a controlled rate so that plane front solidification proceeds upward at a constant velocity. The resulting microstructure consists of 10 pct by volume of whiskers of very high aspect (length to diameter) ratio. The fiber lengths have not been measured because of the difficulty of detecting fiber ends9 but exceeds 104. There is some possibility that the fibers may be continuous within one grain. Flat sheet specimens 2¾ in. sq and approximately 0.2 in. thick containing whiskers parallel to the plane of the sheet and to one edge were used for this study. A1-A13Ni exhibits either a rod-like (high solidification rates) or a blade-like (low solidification rates) whisker morphology,1,3 and both types were studied. Rolling was accomplished using a two-high rolling mill at a speed of approximately 10 fpm. The rolling direction was either parallel to or perpendicular to the direction of growth (direction of whisker alignment). Reductions of from 0.002 to 0.03 in. per pass were used with the most common value being 0.005 in. per pass. Cold rolling of Al-Al3Ni to more than 98 pct reduction in thickness was accomplished with no intermediate anneals. In addition. a series of speci-mens was cold rolled 97 pct with a 1-hr, 500°C anneal in air after each 50 pet reduction. Tensile testing was accomplished using a Tinius-lsen four screw testing machine. Flat sheet specimens + in. wide and between 2 and 2; in. long with the thickness dependent upon rolling reduction, were used. The gage section was in. wide and 1 in. long. Strain was measured using a clip-on LVDT extensome-

Jan 1, 1970

By H. S. George

On one occasion when it seemed desirable to reveal under the microscope not only the metallic structure of an alloy, but certain small non-metallic inclusions that are ordinarily obliterated by etching, it was discovered that, by partly eclipsing the illuminating pencil of light rays, the residual light was thrown on the object from one side and the structure was brought out in relief. At the same time, the non-metallic inclusions were retained in clear view. In this first demonstration of lighting obliquely through the objective a card was thrust part way into the light beam between the arc iris and the light filter; the shadow of the card on the filter served to locate its position. Next several stiff-paper disks of various diameters were mounted on flexible wires; some plasticine on the other end of the wires made it easy to adjust and maintain a disk at any desired position in the light beam. To facilitate manipulation, an assortment of disks was mounted on a wheel, as shown in Fig. 1. The purpose of partly eclipsing the light beam was discussed in an earlier paper.' There it was pointed out that the usual methods of illuminating opaque objects for microscopic examination lend an unnatural appearance to the view, while the new method, which has been termed conical illumination, revels the true relationship of constituents by simulating natural lighting. In nature, all objects are lighted diffusely, or by light predominating from one direction, or by a combination of diffuse and directed light. Under these conditions, objects appear to have three dimensions—they possess relief. The kind of illumination known to metallographists as vertical or axial results in an unnatural appearance, as a large proportion of the illuminating rays are parallel to the line connecting the eye with the object, a condition almost never met in nature. Microconstituents

Jan 1, 1924

By A. G. Spillette, R. L. Nielsen

The purpose of this paper is to further the understanding of reservoir response to hot-water injection by desuribing a two-dimensional, mathematical model of the process. Key assumptions are that no gas phase is present, and that the injected fluid reaches thermal equilibrium instantaneously with the reservoir fluids and sand. The resulting system of three partial differential equations is solved simultaneously through the use of a "leap-frog" application of standard alternating direction implicit methods for the solution of the mass-balance equations and the method of characteristics for solution of the energy-balance equation. The utility of the mathematical model is demonstrated by comparing numerical and analytic temperature distributions for hot-water bank injection and by comparing calculated with observed field behavior. Additional calculations show that hot waterfioding can recover significantly more oil than cold waterflooding, and that a hot-water bank recovers, with less energy input, nearly as much oil us continuous injection. Introduction Consistent field success with hot fluid injection processes requires good reservoir description and a thorough understanding of recovery mechanisms. The latter is fostered by a combination of well designed experimental studies and physically sound mathematical modeling. The purpose of this paper is to further the understanding of reservoir response to hot-water injection by describing a two-dimensional mathematical technique, indicating its validity, and demonstrating its utility for studying the effects of reservoir and operating parameters. Published experimental studies of hot fluid injection processes are few." Even if extensive data were available, two considerations discourage exclusive reliance on laboratory or field work. First, because of the severity of scaling requirements," laboratory results must be interpreted with care. Second, because of the one-shot nature of field experiments — injectivity/productivity tests and pilot floods—results seldom are available over the desired range of operating conditions. These factors emphasize the need for devoting attention to mathematical modeling to complement laboratory and field work. Through the use of mathematical models, scaling uncertainties can be bridged and response can be predicted for unique combinations of reservoir and operating conditions. Numerous mathematical models developed during recent years enable us to calculate temperature distributions, thermal efficiency (or conversely, fraction of heat lost), and oil recovery behavior for hot fluid injection. Ramey" and Spillette' recently have provided reviews of these methods. Most models have concentrated on predicting temperature distributions and thermal efficiency; few have been directed at predicting oil recovery.'."1° Although these techniques are useful for estimating effects of reservoir parameters and operating conditions on process performance, results are limited by the assumptions made and by the methods of coupling independently solved fluid-flow and energy-balance equations. A computer-based method is presented for predicting total reservoir response to hot-water injection that obviates most simplifying assumptions. The model simulates fluid flow and heat transfer in two dimensions within a vertical cross-section spanning the oil sand and adjacent unproductive strata. Known numerical procedures are used to solve the governing partial differential equations. The mathematical model handles the effects of reservoir heterogeneity, gravity, capillarity, relative permeability and temperature-dependent fluid properties. In addition, a wide range of operating conditions can be modeled, including hot-water followed by cold-water injection. Mathematical Description of Hot-Water Injection Key assumptions in the mathematical model for hot-water injection are that (1) no gas phase is present and (2) the injected fluid reaches thermal equilibrium instantaneously with the reservoir fluids and sand. Relative permeability and capillary pressure are assumed independent of temperature. Darcy's law for multiphase fluid flow relates the velocities of the oil and water phases to the phase pressure gradients by the following relations:

Jan 1, 1969

By R. W. Smith, K. H. Lee

Bond type simulated closed-circuit grindability tests and batch grindability tests were run on six pure minerals plus a limestone and a taconite ore. The simulated closed-circuit tests were made at five different meshes of grind. The minerals tested varied widely in hardness and breakage pattern. For all simulated closed-circuit tests both Bond and Holmes work indices were calculated and compared. The Bond grindability testlm6 has been widely and quite successfully used for predictions of such items as ball mill power requirements and as an aid in plant comminution equipment selection. The test is interesting in that although run as a series of batch tests it is over-all a simulated closed-circuit test with a circulating load of 250%. The simulated closed-circuit feature is probably the primary reason for the notable success of the test. Perhaps the major criticism that can be brought against the test is that it is time consuming, since it normally takes a trained technician about an eight-hour shift to perform it.4 For many purposes this is an acceptable time requirement. However, if a grindability test is to be used for mill control purposes it should be performed in as short a time interval as possible, preferably under an hour. Sometimes in industry strictly batch tumbling mill tests are run and an attempt is made to correlate such batch tests with plant mill operation. Then an attempt is made to adjust operating tumbling mills based on data from the tests. The tests, however, frequently do not correlate well with operating data. The purpose of the present work was to explore some of the similarities and differences between a simulated closed-circui.t grindability test and a batch type test. Six different minerals plus a limestone and a taconite ore were tested in the experimentation. These materials varied widely in hardness, breakage characteristics, etc. Standard dry Bond grindability tests were mn on all materials at 48, 65, 100, 150 and 200 meshes of grind. Feed material was prepared by stage cmshing to -6 mesh. Initial feed volume was 700 cc. Care was taken to maintain the standard constant weight (about 20125 gm) and number of balls (283) during all the tests. Rotational speed was 70 rpm. Table I lists the materials studied along with pertinent data regarding the materials and Bond grindabilities obtained. In addition, dry batch tests were performed on all materials. These tests were made in the same mill as was used for the Bond tests. An identical ball charge and an identical feed volume were used. After rotating the mill for a predetermined number of revolutions at the same rotational speed as for the Bond test, the material was removed and separated from the ball charge. A screen analysis was performed on this product. Knowing the original size distribution of the feed and the size distribution of the product, it was possible to calculate the grindability or grams of a particular mesh produced per revolution of the mill. After the screen analysis of the product, the various fractions were recombined and placed back in the mill for further grinding. After grinding for additional revolutions of the mill the procedure was repeated. Thus, it was possible to obtain grindabilities for each material at a number of meshes of grind and for various revolutions of the mill. Grind-abilities obtained from batch tests are shown in Table 11. COMPARISON OF BOND AND BATCH GRINDABILITIES Figs. 1A through 1D show relationships between batch and Bond grindabilities. Figs. lA, lB, 1C and 1D show respectively graphs indicating the relationships for batch tests run for 100, 300, 500 and 700 revolutions of the mill. For a particular material on each graph, points are shown for 200, 150, 100, 65, and 48 meshes of grind except for several missing coarse meshes of grind for galena which did not fall conveniently on the figures. For each material and graph the point nearest the origin is for 200 mesh, the next for 150 mesh, the next for 100 mesh, etc. Considering Fig. lA, it is interesting to note that all relationships shown are essentially straight lines. There are, however, considerable differences

Jan 1, 1969

By W. H. Andrews

THE constantly increasing consumption of Portland cement in the State makes the above subject of partlcular interest at this time. The increasing demand is due to the rapid settling of the country and the fact that new uses are being found frequently for the above named commercial article. The industry is one that is bound to grow as the population increases, and this being the case, it may be well ,it this time to consider briefly- the matter of the chemical and physical com-position of proper raw materials. A cement mixture is one that contains approximately 75 per cent. carbonate of lime, 15 per cent. Silica, and 5 to 7 per cent. alumina, and iron oxides; the other elements being magnesium carbonate and small quantities of the rarer elements general associated with limestone deposits. It call be readily seen from the above composition that it is possible to build up this mixture from a number of different materials. First.-A rock high in carbonate of lime can be mixed with clay or shale in such proportions as to bring about the desired composition ; the chief difficulty in the building up of such a mixture is that it is hard to find a clay or shale in which the silica-alumina, ratio lies .between 4 to 1 and 3 to 1 and at the same time shows physical characteristics which will make certain its adaptability to the practical manufacture of Portland cement. Very often clays or shales are found which are right chemically but contain large quantities of grit or free silica. Such clays or shale must be ground to extreme fineness in the mixture in order to make the silica and alumina combine with the lime when the mixture is burned. On the other hand, clays or shales are often found that have the proper physical characteristics but in which the amount of alumina, is too great.

Jan 9, 1913

By George K. Burgess, Robert A. Hadfield

1. Introduction.—The methods of production of sound steel ingots have been described in several papers read recently before this Institute. It was thought by Director Stratton, of the U. S. Bureau of Standards, and ourselves to be of sufficient interest and importance, as a further contribution to this subject, to compare the properties of rails rolled in one mill according to American practice, from several types of ingot of substantially the same chemical composition but cast by several processes; and to compare in considerable detail the properties of an ingot manufactured by the Hadfield special-feeding process and one of the usual type for rolling into rails. We are greatly indebted to F. W. Wood, President of the Maryland Steel CO., who made this investigation possible by kindly placing his rail mill at our disposal; and he and his associates at Sparrows Point did everything possible to make the experiment a success, including the execution of several of the tests and analyses. 2. Classification and Manufacture of Ingots.—Of the ingots used in this investigation, eight were made in Sheffield and furnished by Sir Robert Hadfield, and one was made and furnished by an American steel company,l as a comparison ingot, and was supposed to represent the usual type of ingot from which rails are made. The characteristics of the ingots are given in Table I. Ingots 1, 2, 3, and 4 were cast large end up and fed by the Hadfield method in the usual manner with charcoal and blast continued until the molten steel has set on the top of the head, say varying from 20 to 40 min. To ingots 1, 2, and 4 was added 0.1 per cent. aluminum, and to the nickel-chrome ingot, No. 3, 0.125 per cent. For sake of comparison, there were also included two ingots, Nos. 8 and 9, cast with the small end up and fed by

Jan 1, 1915

By Walter S. McKee

When mixed with common cast steel in quantities ranging from 11 to 131/2 per cent. and properly treated, manganese increases the ductility of the metal and adds greatly to its toughness and resistance to abrasive action, which properties comprise the distinctive characteristics that make manganese steel so valuable for many purposes at the present time.. * At present the manganese-steel foundries of this country have an annual capacity of about 60,000 tons and most of the growth has occurred within the past 10 years. In the early days of the industry it was impracticable to make manganese castings weighing over a few thousand pounds, but at present crusher heads, rolling-mill pinions, and similar castings weighing up to 30,000 Ib. each are produced, and it does not appear that the limit of weight has been reached by a considerable margin. Manganese steel is similar in analysis to ordinary first-class converter metal except that it is high in carbon and contains from 11 to 13.5 per cent. of manganese. From one standpoint manganese steel is similar to malleable iron in that the casting as it comes out of the sand is hard and brittle and must be made ductile by a heat-treating process. The heat treatment is an essential part of the process of making manganese-steel castings and must be properly carried out to secure satisfactory results. The necessity for heat treatment limits the thickness of sections which may be made of manganese steel. Originally the annealing depth was comparatively small, but researches carried on during the past few years have resulted in an increase in the thickness of section up to 51/2 in., which it is possible to treat successfully. Large castings are cored out to a minimum thickness of 51/2 in., thus not only eliminating some of the internal stresses which are invariably set up in a very thick casting, but also reducing the weight and inertia of the piece, an important consideration if the casting is to be a moving part in a machine. At the same time, the thickness of 51/2 in. is sufficient to permit the use of manganese steel for the heaviest classes of machinery.

Jan 1, 1916

By A. L. Holley

The application of scientific methods to the investigation of natural laws and to the conduct of the useful arts which are founded upon them, is year by year mitigating the asperity and enlarging the outcome of human endeavor. More notably, perhaps, are these the facts in that system of productive and constructive arts of which engineering is the general name. In metallurgical engineering especially, within the period of our own recollection, how rapid has been the rate and how wide the scope of progress: the scientific discovery and mining of metalliferous veins; the economical separation and reduction of ores of every grade; the production and regulation of high temperatures; the varied improvements in the manufacture of iron, in saved heat and work, in uniformity and range of products; and, most important of all, the creation and the utilization, to be counted by the million tons a year, of the cheap constructive steels. Wonderful as this range and degree of development may appear to the public eye, the close and thoughtful observer must, nevertheless, conclude that neither the profession nor the craft of engineering may congratulate themselves too complaisantly, but that they should rather acknowledge to each other the embarrassing incompleteness of the union between engineering science and art. There is a small school of philosophers whom we may designate as original investigators, men who come close to nature, who search into first principles, and who follow that scientific and therefore fruitful method by which the relations of matter and force are discovered, classified, and brought within the reach of practice. These wonderful men do not indeed create the laws of nature, as they sometimes almost seem to, but they go up into the trembling mountain and the thick darkness and bring down the tables upon which they are written.

This listing of members is arranged to show company affiliation The primary breakdown is by state or country, then by company name and political subdivision At the end of each major group is a general list showing members affiliated with schools or colleges and those who did not indicate any company affiliation The listing, for countries outside United States, is broken down generally by continents and alphabetically within the continent by countries The various countries are indexed on the preced¬ing page *-The asterisk indicates members available for consulting work Anyone desiring to be listed with AIME as available for consulting work can do so by sending a written request to the office of the Secretary.

Jan 1, 1952

By Michael S. Roscoe

In order to more accurately predict longwall surface subsidence over the Pittsburgh No. 8 Coal in Eastern Ohio, North American Coal Corporation's Quarto Mining Company undertook or participated in several subsidence studies. Due to the changing roof geology and rapid variations in the amount of cover two separate areas were investigated at two different mines to determine the subsidence response if any to these changes. Data generated from these studies were compared with NCB derived,data for accuracy and then used to predict subsidence under houses, gas lines and other critical man made structures. The following report summarizes the results of these studies as well as the subsidence case histories of gas lines, transmission towers, houses and water wells. Problems that were encountered during both phases of this process (investigation and subsequent application) are also included.

By Thomas J. Crocker, Galen G. Waddell, Eugene H. Skinner

This paper describes a method of measuring initial and long-term deformations which occur in the medium surrounding mine accessways, and discusses the importance of this type of measurement in assessing support-problem areas. Delineated are (1) description of the rock-deformation monitoring equipment, (2) results of two field tests which monitored rock deformation around 4-foot-diameter raise bores, and (3) a numerical-analysis (finite-element) technique to correlate theoretical with experimental results. Instrumentation developed provided the sensitivity and resolution needed to measure rock deformation around a full-scale raise bore during excavation. Results of the tests conducted at the Lucky Friday mine, Mullan, Idaho, show the relationships between (a) de- formation vs. time, and (b) deformation vs. bit progress. Based on theoretical evaluation of the initial deformation, the medium appeared to behave elastically. Using an estimated field stress of 5,500 psi and Poisson's ratio of 0.20, the gross modulus of elasticity of the rock was calculated to range from 3.15 to 6.0 x 106 psi (with one outlier which was determined to be >12 x l06 psi).

Jan 1, 1971