Search Documents

By N. J. Grant, F. B. Cuff

DURING a recent investigation of high-purity aluminum,' evidence was found for grain-boundary sliding and migration at room temperature. The investigation was concerned primarily with an electron-microscopic study of a fine (approximately 1 micron) network that appeared on the surface of chemically polished aluminum. The nature of the network will not be discussed since it serves only as markers showing relative displacements in this instance. The pertinent observation, shown in Fig. 1, was made on a flat tensile specimen which had been strained about 8 pct at room temperature. As can be seen in this electron micrograph, a grain boundary has undergone a certain amount of sliding. The reason for the existence of the two differently appearing networks is given in the foregoing reference. For present purposes, however, the transition region can be disregarded. A close study of this picture reveals that in addi- tion to sliding there is a narrow band adjacent to and above the grain boundary. Fig. 2 is a schematic drawing showing the essential features of this band.

Jan 1, 1959

By Wilson D. Michell

The Magma copper vein trends east-west, dips 70" south, and cuts through a 6000-ft thickness of limestones, quartzites,. shale, diabase, and schist. The vein is itself a fault with a horizontal offset of 500 ft on the formation contacts in the two walls. There are two principal faults of large displacement and numerous smaller steep and flat faults that complicate the prediction of ore occurrence. A study of the geology, its systematic recording to facitliate ready reference, and graphic methods of interpretation of mineralization have aided the exploration, development, 2nd mining of the ore. In making predictions of the distribution of mineable ore bodies and their shape in critical areas, studies are made of "mineralization contours" and "mineralization trends," which are developed on a longitudinal section of the vein from variations in the concentration of the combined base metal content as shown by assays of available openings in the mine. Introduction This paper describes an example of geological work applied directly to mining and exploration problems in a deep vein deposit, and it is presented as being of interest especially to those engaged in working more or less similar veins. In 1944 to 1945 the writer spent a year as assistant to J. K. Gustafson in a thorough geological examination of the Magma mine. Much of the writer's subsequent independent work described in the present paper had its inception in ideas originated by Gustafson during that examination. Objectives of Geological Work at Magma Mine The objectives of geological work at Magma, as at operating vein mines of a similar nature, can be summarized as follows: 1. Direct assistance to the mining department by means of predictions as to the size, shape, grade, and location of ore bodies; by solution of fault problems and irregularities in the veins; by prepara-?ion of detailed ore-reserve estimates in specific areas; by keeping a complete record of the geology and assay results in the mine; and by guiding development work. In short, geology can aid in the realization of the prime purpose of the mining department, which is that of producing the greatest amount of ore in the most economical and expeditious manner possible. 2. Guidance for exploration, especially diamond drilling, in undeveloped areas of the mine. 3. Contributions to the understanding of the general geology of the deposit and its regional setting, including ore genesis, structure, and mineral relationships. Magma Ore Deposit The east-west trending Magma vein, dipping about 70" south, cuts through a 6000-ft thickness of concordant limestones, quartzites, shale, diabase, and schist, named in descending order. These

Jan 1, 1949

By Wilson D. Michell

The Magma copper vein trends east-west, dips 70" south, and cuts through a 6000-ft thickness of limestones, quartzites,. shale, diabase, and schist. The vein is itself a fault with a horizontal offset of 500 ft on the formation contacts in the two walls. There are two principal faults of large displacement and numerous smaller steep and flat faults that complicate the prediction of ore occurrence. A study of the geology, its systematic recording to facitliate ready reference, and graphic methods of interpretation of mineralization have aided the exploration, development, 2nd mining of the ore. In making predictions of the distribution of mineable ore bodies and their shape in critical areas, studies are made of "mineralization contours" and "mineralization trends," which are developed on a longitudinal section of the vein from variations in the concentration of the combined base metal content as shown by assays of available openings in the mine. Introduction This paper describes an example of geological work applied directly to mining and exploration problems in a deep vein deposit, and it is presented as being of interest especially to those engaged in working more or less similar veins. In 1944 to 1945 the writer spent a year as assistant to J. K. Gustafson in a thorough geological examination of the Magma mine. Much of the writer's subsequent independent work described in the present paper had its inception in ideas originated by Gustafson during that examination. Objectives of Geological Work at Magma Mine The objectives of geological work at Magma, as at operating vein mines of a similar nature, can be summarized as follows: 1. Direct assistance to the mining department by means of predictions as to the size, shape, grade, and location of ore bodies; by solution of fault problems and irregularities in the veins; by prepara-?ion of detailed ore-reserve estimates in specific areas; by keeping a complete record of the geology and assay results in the mine; and by guiding development work. In short, geology can aid in the realization of the prime purpose of the mining department, which is that of producing the greatest amount of ore in the most economical and expeditious manner possible. 2. Guidance for exploration, especially diamond drilling, in undeveloped areas of the mine. 3. Contributions to the understanding of the general geology of the deposit and its regional setting, including ore genesis, structure, and mineral relationships. Magma Ore Deposit The east-west trending Magma vein, dipping about 70" south, cuts through a 6000-ft thickness of concordant limestones, quartzites, shale, diabase, and schist, named in descending order. These

Jan 1, 1949

R. H. THURSTON, Cornell University, Ithaca, N. Y. (communication to the Secretary): The " tri-axial diagram" was, I think, first employed by me in the work of the " U. 8. Board Appointed to Test Iron, Steel and Other Metals." A model was exhibited to the American Association for the Advancement of Science, and the diagram was first published, and the model described, in a paper presented to the same society at its Nashville meeting in 1877." The problem then presented to its inventor was to find a method of planning a research involving proportions of ternary compositions in such manner that, a limited number of such compositions being tested, the results should give the law of variation in the physical properties of all possible combinations of the three elements, and the actual numerical values of such as were important to the investigator. The investigation of the binary alloys, copper and tin, copper and zinc, and tin and zinc, had been completed and satisfactorily discussed, employing the usual bi-axial diagram, of which the ordinates represented the one, and the abscissæ the other, of the characteristic properties to be studied, the composition being commonly indicated by the abscissæ. In these cases it was easy to ascertain, by the study of a limited number of compounds, the law of variation in strength, ductility, etc., with composition; but, for a long time, the ternary alloys were not attacked, because no simple and satisfactory method presented itself of securing results significant for the whole field by the investigation of a comparatively small number of alloys. The tri-axial diagram was finally hit upon as a means of representing and interpreting results, and researches were at once begun, and in due time satisfactorily completed.

Jan 1, 1899

THE book covers principally the assaying of silver and gold and the determination of these values in ores, sweepings, and base metal. It seems to have been written more for the goldsmith and jeweler than for the primary producer of metals. There were approximately sixty different substances needed in the operations described and not over a dozen different types of raw material (ore, matte, crude or alloyed metal) are mentioned. The methods of separation used were essentially simple and reasonably reliable, though the processes were not sufficiently understood to permit the selection of the simplest effective ingredients, and there was a great tendency to employ complicated fluxes, with unnecessary repetition of long-continued heatings indicative of a leisurely pace of life. Practically all the processes described are based on a few chemical facts: the inability of gold to combine with sulphur, while silver and the base metals form easily fusible sulphides; the ready oxidation of base metals; and the ii- solubility of gold in nitric acid. Fluxes serve to make earthy impurities fusible, and to carry oxidizing or sulphurizing ingredients. Many of the processes of assaying had changed little up to the beginning of the present century. Even as late as 1924, when the writer took a University course in fire assaying, the crucibles, cupels, scorifiers, molds, and tongs were identical with those of the sixteenth century, though the wind furnace had a stack on it and the muffle for cupelling was gas-fired.* The fluxes were purer, but of the same essential composition. That this branch- or twig-of metallurgy had not advanced in any funda-

Jan 1, 1949

By Tracy L. Atherton

The mapping of slant-hole oil fields is complicated by the fact that relationships between wells are subject to variations in three dimensions and are not readily adaptable to representation on a plane surface. Formalized perspectives usually expand into an undecipherable maze of lines and peg models with the necessary supporting dividers serve only to awe the beholder with their perplexity. The usual compromise arrived at is a plotting of the projection of the courses of all of the wells in the field onto a horizontal plane (Fig. I). These complicated plots, when used in conjunction with the individual vertical projections of the wells, heretofore have been the most practical foundation for the study of general field problems. This method has many shortcomings, however, which arc not found in the recently developed straight-hole equivalent projec-tion method. The new method supplies a series of maps similar to the type now in common use in straight-hole fields. It is remarkably simple to use and supplies a ready check on clearances between wells. Perhaps the method can best be understood if the steps that led to its development are described. Common practice of oil-well surveyors is to supply the owner with a tabling of the survey and a plan view plotted against the true meridian. If a vertical projection is plotted, it is usually plotted separately and shows vertical depths against the projection of the stations along a section line joining the top and bottom of the hole on the plan view. A more practical method would be to plot the section line of the plan parallel to the abscissa of the vertical projection (Fig. 2). If this is done, any line parallel to the "base line1' will pass through the points on each projection that represent a single point in the hole. Another very useful graph, which the well surveyor could provide, would be plotting of vertical depths against measured depths. Fig. 3 illustrates the next step facilitated by this form of plotting. The lines designated "well A" represent the proposed course of a hole to be drilled. Superimposed on the drawing, in its proper relative position, is the plan view and a portion of the vertical projection of a present producer, well B." From an inspection of the plan view we arrive at the correct conclusion that the only indicated possibility of collision is at the point of crossing of the wells on the plan view. Referring to the vertical projection, note that the vertical depths of stations on B, in the vicinity of the crossing, are plotted on the same plane of projection as A. The clearance is the indicated distance between the two vertical sections measured along the parallel to the "base line," which passes through the point of intersection of the plan view. Repeat this process for the other wells crossing the proposed course of A on the plan view and you have a preliminary check of clearance for the proposed course. A similar comparison of crossings on the vertical projections of all >

Jan 1, 1941

By Tracy L. Atherton

The mapping of slant-hole oil fields is complicated by the fact that relationships between wells are subject to variations in three dimensions and are not readily adaptable to representation on a plane surface. Formalized perspectives usually expand into an undecipherable maze of lines and peg models with the necessary supporting dividers serve only to awe the beholder with their perplexity. The usual compromise arrived at is a plotting of the projection of the courses of all of the wells in the field onto a horizontal plane (Fig. I). These complicated plots, when used in conjunction with the individual vertical projections of the wells, heretofore have been the most practical foundation for the study of general field problems. This method has many shortcomings, however, which arc not found in the recently developed straight-hole equivalent projec-tion method. The new method supplies a series of maps similar to the type now in common use in straight-hole fields. It is remarkably simple to use and supplies a ready check on clearances between wells. Perhaps the method can best be understood if the steps that led to its development are described. Common practice of oil-well surveyors is to supply the owner with a tabling of the survey and a plan view plotted against the true meridian. If a vertical projection is plotted, it is usually plotted separately and shows vertical depths against the projection of the stations along a section line joining the top and bottom of the hole on the plan view. A more practical method would be to plot the section line of the plan parallel to the abscissa of the vertical projection (Fig. 2). If this is done, any line parallel to the "base line1' will pass through the points on each projection that represent a single point in the hole. Another very useful graph, which the well surveyor could provide, would be plotting of vertical depths against measured depths. Fig. 3 illustrates the next step facilitated by this form of plotting. The lines designated "well A" represent the proposed course of a hole to be drilled. Superimposed on the drawing, in its proper relative position, is the plan view and a portion of the vertical projection of a present producer, well B." From an inspection of the plan view we arrive at the correct conclusion that the only indicated possibility of collision is at the point of crossing of the wells on the plan view. Referring to the vertical projection, note that the vertical depths of stations on B, in the vicinity of the crossing, are plotted on the same plane of projection as A. The clearance is the indicated distance between the two vertical sections measured along the parallel to the "base line," which passes through the point of intersection of the plan view. Repeat this process for the other wells crossing the proposed course of A on the plan view and you have a preliminary check of clearance for the proposed course. A similar comparison of crossings on the vertical projections of all >

Jan 1, 1941

By J. E. Burke

THE origin of so-called annealing or recrystalli-zation twins in face-centered-cubic metals continues to be a matter for speculation, and in the present report an attempt is made to explain their origin and to account for at least a majority of the observations concerning their behavior. The fact that annealing twins are prominent only The speelmen was deformed 8 pet in compression and then indented over the lower left-hand corner in a Rockwell in-denter, and then annealed to cause partial recrystallization. Note intense twinning in heavily deformed part and slight twinning in less deformed part. The upper right-hand corner is unrecrystalized. Area reduced approximately 25 pot for reproduction. after recrystallization suggests that deformation may be necessary for their formation. In 1926, Mathewson1 reported the observation by Phillips that annealing twins are frequently parallel to strain markings which delineate octahedral planes in the deformed (and partially recrystallized) matrix, and suggested that strain markings are mechanical twins which grow into annealing twins during recrystallization. Later work by Burke and Barrett' has shown that strain markings are traces of planes upon which slip has occurred, and that there is no evidence for the formation of mechanical twins of microscopically resolvable width in face-centered-cubic metals. Mathewson3 has pointed out, however, that slip may produce twin faults, and later modifications of this hypothesis have assumed that twin faults rather than true mechanical twins serve as the nuclei for annealing twins. Carpenter and Tamura5 suggested, also in 1926, that annealing twins might form by accidents of growth. A close-packed layer of atoms can be added to the octahedral plane of a face-centered-cubic metal in two possible positions, the right position

Jan 1, 1951

By John W. Pack

AT present the manufacture of metallic zinc, or spelter, in Missouri, is carried on only at the establishments located at Carondelet, or South St. Louis. Although the development of the industry has not yet reached that fulness which it has attained elsewhere in the United States, still the commanding advantages of position of these establishments are so evident that the prospective importance and magnitude of spelter manufacture in this State, and especially at this locality, can hardly be doubted. A study of the chemical and technical aspects of the business of these points cannot be without interest to the metallurgist as well as to the capitalist. I have endeavored to investigate, as far as was practicable, within the limits of a paper of this character, some of the problems connected with this industry, at the same time making a few comparisons of the results attained at some of the Carondelet works with those of other establishments with regard to which information could be obtained. In the prosecution of these studies I have been kindly aided by the managers of Carondelet establishments, and by Prof. Charles P. Williams, Director of Rolla School of Mines. To the latter I am especially indebted for assistance in regard to methods of analysis. To all these gentlemen I return my thanks for their valuable aid. Other sources of information will be duly credited in their proper places.

Jan 1, 1875

By Donald B. Gillies

WE HAVE come a long way since the time of the old steel master who declared that chemistry would ultimately bring the steel business to ruin. Yet I sometimes doubt whether even now we fully recognize the great debt we owe to the institutions that today are initiating young men into the fascinating mysteries of science and training them in the art of engineering. I am not sure that we recognize the importance of the contribution that the schools of applied science and the technical colleges are making to our industrial economy. That contribution is neither narrow nor restricted. It covers the whole range of industry. Dr. Compton, himself, has shown in his survey of leading American corporations that the engineer is twelve times more likely than the nonengineer to become president, five times more likely to become treasurer, and thirty times more likely to become an officer. So the hand of the engineer not only is all-powerful in the laboratory and in the drafting room but his control is increasing in all departments of management.

Jan 1, 1940

Reply to discussion of the paper of C. W. Washburne, presented at the New York meeting, February, 1914 (Trans., xlviii, 687 to 694 (1914)). C. W. WASHBURNE, New York, N. Y. (communication to the Secretary*).-Professor Lane makes an interesting contribution to the study. of chloride waters, in saying that calcium chloride waters occur not only in the greenstones of the Lake Superior copper mines, but also in the interbedded -felsitic conglomerates and "in far-removed sandstones, e.g., near Whitefish lake, and Ontonagon, in the Michigan iron mines, and in the Storm King granite." Surely these are not connate waters preserved from the Algonkian sea, assuming that the Algonkian sediments are marine rather than continental. Finding the same type of water in the Storm King granite points rather toward an abyssal source. The possible connection of these waters with the magma of the greenstone is immaterial, although some basic calcic magma is the most probable source. It is to be expected that the ascending water of the region would be found not only in the greenstones, but in all the rocks which it could penetrate. The ascent of water of this kind along vertical passages, and the consequent addition of a common ion: to the circulating sedimentary salt solutions, would explain the precipitation and localization of the "giant, concretionary" salt plugs of the Gulf Coast, without making the ex-excessive demand for an improbable quantity of salt in the adjacent sediments that is required by the unmodified theory of Harris. With-out such a precipitating medium most of the dissolved sodium chloride would have been lost by passing on to the surface without precipitation. The base to which the chlorine ions were attached is immaterial, providing they were sufficiently concentrated, but the presence of the chlorides of calcium and magnesium in the solutions is indicated by the associated bodies of secondary dolomite.

Jan 4, 1915

By James H. Allen

The development of large diameter rotary drilling techniques and equipment in the last nine years has been the main factor for the rapid advancement made by this method of shaft construction. In 1959, less than 5000 ft of large diameter hole was drilled in the United States for the mining and construction industries. By 1967, large diameter hole footage had increased to 117,000 ft. Part of the increase in footage for holes drilled represents AEC requirements due to the discontinuance of atmospheric testing of nuclear devices. The increase in footage for holes drilled for the mining industry can be attributed to cost savings of shaft construction by rotary methods as compared to conventional blasting methods. Until the late 1950's most large diameter holes were drilled with positive displacement rig pumps or air compressors, direct mud or air circulation, conventional sized oil well drilling strings, and multipass reaming techniques. In some very soft formations it was possible to run a pilot bit with one or more hole openers in tandem to drill the hole in a single pass. The main problem with single pass drilling using tandem hole openers was in providing sufficient circulation fluid for proper hole cleaning through conventional sized drill pipe.

Jan 11, 1968

By A. M. Gaudin, D. W. Fuerstenau

IN concentration of certain ores by soap flotation, prevention of quartz flotation is desired; the contrary is true in treatment of some oxide iron ores. Experimental study of the flotation of quartz goes back at least a quarter of a century.' Clean quartz does not float with fatty acids or soaps but does float when activated by one of many metallic salts. Control of pH is important. Broadly speaking the problem of quartz flotation has been approached from the empirical side, as was the related topic of flocculation or dispersion of quartz suspensions? Empirical studies indicated the existence of critical relationships between the additions of collector and activator. These additions were not stoichiometric for the formation of soaps of the activator cation. For example, Gaudin and Rizo-Patrona found optimum quartz flotation at pH 10.6 using barium activation and oleate collection when the molar ratio of oleate to barium was 1 to 1 instead of 2 to 1, as would be called for formation of Ba(OL),. Cooke and Digre" ' found that if calcium is the activator, a minimum quantity of that agent is required for effective flotation when the pH is 11.5. In other words, if the concentration of Na' exceeds 10 -2.5 mols per liter or if the concentration of H exceeds 10-11 mols per liter, the concentration of Ca++ in solution required for quartz activation is increased. This suggests that H+ is much more effective than Na+ on 10-2.5 quartz, perhaps in the ratio ofp or 108. Schuh- mann and Prakash6 studied anew the activation of quartz by barium, calcium, aluminum, and ferric iron. Salts of these metals are activators provided they are in stoichiometric excess over the collector used with them. Alkaline-earth salts are effective only in alkaline circuits. Important as they are in giving data on the effect of various agents on quartz, all these studies fail to give information on the detailed structure of the quartz-solution interface. A beginning in this direction was made by Gaudin and Chang,? who measured the adsorption of radioactively marked barium and laurate ions at quartz surfaces, and by Gaudin. Spedden, and Laxen,8 ho measured the adsorption of radioactively marked sodium at quartz surfaces. Work has also been done by Bell0 n measurement of the adsorption of sodium ion and chloride ion at quartz-solution interfaces. In all these experimental measurements of adsorption, the solid was centrifuged or filtered from the bulk of the liquor with which it had been associated; and the composition of the solid surface was ascertained by analysis, after allowance was made for the ionic composition of the liquor included with the centrifuged solids on the assumption that it is identical to the bulk liquid. Adsorption measurements give only the total amount of collector adsorbed at the quartz-solution interface; they give no indication of the distribution of these adsorbed ions at the interfacial layer. It is the ionic structure of the solid-solution interface and its importance to flotation that is the subject of this paper. The structure of this interfacial layer can be investigated by means of electrokinetic methods so that by combining electrokinetic studies with adsorption measurements, a more complete picture of the quartz surface may be obtained. The following studies were made to ascertain how electrolytes used in the soap flotation

Jan 1, 1956

By John M. Pitt

Shear strength assessment and the associated variability in rock masses historically have been hindered by high costs and biases in laboratory testing programs. An in situ direct shear device was developed on the principle of the previous borehole shear device for soils. Using wedge action to simultaneously apply normal and shear stress to an envelope of material on the periphery of a borehole, the device develops a complete Mohr-Coulomb failure envelope. Tests performed in homogeneous materials show expected strengths and their variability equivalent to laboratory tests. However, tests in a structurally non- homogeneous coal did not display significant variability. A 38 mm diam borehole was used in this work; however, larger or smaller bore- holes may also be used within the size limits of the device. The device is employed in holes commonly drilled for rock bolt placement, at 1 to 2 minutes per test.

Jan 1, 1984

By J. E. Cannaday, R. J. Austin, R. K. Saxer

PREVIOUS investigators have determined activation energies and have postulated various controlling mechanisms for creep.'-' Recently Barrett et 01.I5 have suggested, as the result of their work with cadmium, that the apparent activation energies for creep (AHc) above 0.5 T, could be correlated by means of activation energies for self-diffusion (AHSD) and modulus of elasticity functions: AHC = AHSD - (5RT/E) dE/dT. The wide disparity of apparent activation energies previously obtained with nickel compared to those reported for other fcc metals and the desire to test the postulate of Barrett el al. prompted this study. The as-received 17.5-mil nickel wire used during this work assayed 99.87 pct pure, Table I. X-ray analysis indicated that the wire was in a stress-re- lieved state and metallographic examination revealed an equiaxed grain size of approximately 0.01 mm. Specimens degreased in acetone and cut to 1-1/2 in. lengths were tested in a cam-mechanized constant-stress creep machine. A vacuum of at least lo-5 mm Hg was maintained during all tests. Stresses were applied when thermal equilibrium was established. When a measurable (at least 0.5 pct) secondary creep was observed, the temperature was pulsed to a higher temperature. Pulsing time varied from 30 sec at 480°C to 2 min at 1300'C and above. Slopes of creep curves were determined after the initial acceleration in the strain rate had subsided and steady-state creep was achieved. To confirm the results obtained, additional tests were performed incorporating a temperature pulsing method suggested by sherby. In this method the load was removed during temperature pulsing and reapplied after thermal expansion had occurred. No appreciable differences in results were obtained. Tests were performed over a wide range of temperature (470" to 1310°C) and stresses (250 to 17,000 psi). The expression was used to calculate activation energies. In this expression T1 and T2 are the initial and final temperatures, and el and i2 are the creep rates at T, and T2. The variation of the apparent activation energies with the mean test temperature calculated by means of Eq. [I] are shown in Fig. 1. The mean test temperature (Tmean) was calculated from the relationship

Jan 1, 1967

By C. H. Jr. Herty

THE elimination of metalloids in the open-hearth process depends on oxidation of the metal by diffusion of FeO from the slag (or absorption of FeO by the metal), with subsequent reaction between dissolved iron oxide and the metalloids carbon, manganese, phosphorus, and silicon. During an investigation on deoxidation with silicon, data on rate of oxidation of the metal were obtained, and these combined with certain other information, are presented here in an attempt to show the fundamental principles governing the diffusion of FeO from slag to metal. Inasmuch as the aim of the investigation was not a study of diffusion, certain data are lacking and it has been necessary to make assumptions on metal viscosity and effect of temperature on diffusion. These factors are known to exert a considerable effect on diffusional processes. Overoxidation, or supersaturation of the metal with iron oxide, is not taken up in this paper. Overoxidation has little effect on diffusion except under a few special conditions, and the discussion has therefore been limited to diffusional processes. Though the results given in this paper should be regarded as preliminary, certain of the conclusions drawn are definitely applicable to any steelmaking process.

Jan 1, 1929

By R. W. Gurry

Thermodynamic calculations indicate that boron is a better deoxidizer than silicon but probably is not quite as effective as aluminum. Boron should, therefore, be readily oxidized out of the open-hearth bath, which implies that it is not recovered in significant concentration from any scrap charged; also that, if added in the ladle, it tends to oxidize out during teeming unless protected by the presence of a better deoxidizing agent. These conclusions do not apply to liquid cast iron, in which the oxygen content is much lower than in liquid steel. The possibility of conserving certain strategic alloying elements widely used in steelmaking, notably manganese, chromium and molybdenum, by the use of boron, which in small concentration appears to be extraordinarily effective in promoting hardenability, raises a question as to what extent any boron present in the scrap charged into the open hearth is oxidized out during melting and subsequent refining. This question is significant because the optimum concentration of boron in the finished steel, which is fairly critical, would be very difficult to attain if the boron in the charge were largely retained in the metal. Moreover, unless boron is substantially eliminated in the open-hearth process its use on a large scale would eventually make it impossible to produce boron-free steel except by restricting the charge to virgin material. There is at present, unfortunately, virtually no satisfactory direct evidence to provide an answer to this question; but there are indications from practice that boron is oxidized out in the open hearth in the production of medium or low-carbon steel, although it may be retained if the carbon content remains fairly high; that is, if the oxygen is kept fairly low. In the absence of direct data, it is necessary to rely upon the indications of indirect evidence, the best approach now available being a thermodynamic calculation of the deoxidizing power of boron in liquid steel by the general method used so successfully by Chipman1 in his study of the reactions in the open-hearth process. The thermal data for boron, upon which such a calculation must be based, are reasonably satisfactory; the only quantities not directly determined are the entropy of melting of boron, the activity coefficient of boron in liquid steel, and the activity coefficient of B2O3in an open-hearth slag; but these values may be estimated with ample accuracy. The results of this calculation, which is presented later, are given in Table I, together with corresponding data for other deoxidizing elements. This table shows the calculated residual content of oxygen in equilibrium with different residual concentrations of the deoxidizer in the metal;

Jan 1, 1944

By R. W. Gurry

Thermodynamic calculations indicate that boron is a better deoxidizer than silicon but probably is not quite as effective as aluminum. Boron should, therefore, be readily oxidized out of the open-hearth bath, which implies that it is not recovered in significant concentration from any scrap charged; also that, if added in the ladle, it tends to oxidize out during teeming unless protected by the presence of a better deoxidizing agent. These conclusions do not apply to liquid cast iron, in which the oxygen content is much lower than in liquid steel. The possibility of conserving certain strategic alloying elements widely used in steelmaking, notably manganese, chromium and molybdenum, by the use of boron, which in small concentration appears to be extraordinarily effective in promoting hardenability, raises a question as to what extent any boron present in the scrap charged into the open hearth is oxidized out during melting and subsequent refining. This question is significant because the optimum concentration of boron in the finished steel, which is fairly critical, would be very difficult to attain if the boron in the charge were largely retained in the metal. Moreover, unless boron is substantially eliminated in the open-hearth process its use on a large scale would eventually make it impossible to produce boron-free steel except by restricting the charge to virgin material. There is at present, unfortunately, virtually no satisfactory direct evidence to provide an answer to this question; but there are indications from practice that boron is oxidized out in the open hearth in the production of medium or low-carbon steel, although it may be retained if the carbon content remains fairly high; that is, if the oxygen is kept fairly low. In the absence of direct data, it is necessary to rely upon the indications of indirect evidence, the best approach now available being a thermodynamic calculation of the deoxidizing power of boron in liquid steel by the general method used so successfully by Chipman1 in his study of the reactions in the open-hearth process. The thermal data for boron, upon which such a calculation must be based, are reasonably satisfactory; the only quantities not directly determined are the entropy of melting of boron, the activity coefficient of boron in liquid steel, and the activity coefficient of B2O3in an open-hearth slag; but these values may be estimated with ample accuracy. The results of this calculation, which is presented later, are given in Table I, together with corresponding data for other deoxidizing elements. This table shows the calculated residual content of oxygen in equilibrium with different residual concentrations of the deoxidizer in the metal;

Jan 1, 1944

By G. C. Wallick, W. R. Foster, J. G. Savins

Inasmuch as the differentiation and integration methods represent different modes of rheological analyses, a dual scheme of analysis using both methods should lead to a generalized method of data analysis. A dual differentiation-integmtion method of analysis is applied here to the Poiseuille flow of a variety of ideal Generalized Newtonian and viscoplastic models. Using machine-processing techniques, the result is a spectrum of response patterns which are expressed in terms of certain derivative functions. It is shown that these characteristic functions form the basis of a highly-sensitive analytic technique for optimizing the selection of the most appropriate functional relationship between shear rate and shearing stress. INTRODUCTION In the first paper of this series, Savins, Wallick and Foster1 presented an historical review of the salient features of the differentiation method of rheological analysis in Poiseuille flow, and also indicated how the method could be applied to problems involving plane Poiseuille flow. It was shown that the differentiation and integration methods, although basically not incompatible, do represent different modes of rheological analysis. This suggests that valuable background information regarding the probable response characteristics of real data obtained with the differentiation method can be obtained from an integration method-differentiation method analysis of the response of a variety of ideal rheological models. The present paper describes how this dual method of analysis has been applied to suites of idealized models representing a wide variety of Generalized Newtonian and viscoplastic behavior which have received attention at various places in the literature.

By T. W. Smoot

Bentonites are composed chiefly of montmorillonites which are clay minerals generally distinguished from other clay minerals by their surface activity and extremely fine particle sizes. The uses of bentonite are many and varied, depending principally on one or more of the following characteristics: 1) Thixotropy, 2) Dispersion, 3) Plasticity, 4) Swelling, 5) Surface area, activity, ab- and adsorbtive properties. Some of the major uses of bentonite are briefly reviewed as are the mineralogical and physical properties. The uses of X-ray diffraction, differential thermal analysis and other tests for physical properties are reviewed as to their uses in evaluation. In the past 40 years, the industrial uses of bentonite have grown to include many applications. The physical and chemical properties of bentonites are such that they can be used as catalysts, adsorbants, plasticizers, binders, drilling muds, and pelletizers. Not all bentonites, however, can be used for all of these purposes and some are probably of little or no value for any use. The purpose of this paper is to briefly review the mineralogical, physical, and chemical characteristics and variations of bentonites. The determination of these characteristics and their uses in industry are also reviewed so that these determinations can be used as guides for evaluation. DEFINITION OF BENTONITE The word bentonite, as used in this paper, refers to a clay material, usually (but not necessarily) the result of the in-place-weathering of volcanic ash. Its mineralogical composition is dominated by the clay mineral montmorillonite and generally carries other clay minerals and silica minerals as the major 'impurities'. For this discussion, such a definition is justified since most of the economic uses of bentonite~ depend upon the physical and chemical characteristics of the montmorillonite minerals involved. The terms montmorillonite and bentonite have been used almost interchangeably in industry although the latter is much more commonly used. Therefore, where montmorillonite is discussed, it should be understood that the major feature of a bentonite is the subject. STRUCTIJRE OF MONTMORILLONlTE The economic importance of bentonites is generally based on one or more of the following characteristics of montmorillonite: 1) high-thixotropy and easy dispersion in water, 2) high-plasticity, 3) swelling properties, 4) large surface area/unit mass, 5) high surface activity, and 6) adsorptive properties. To understand these properties, an appreciation of the structural scheme of montmorillonite is helpful. Montmorillonite IS one of the three-layer clay minerals composed essentially of hydrous aluminum silicates. The essential building blocks of these layered silicate:; are: 1) silica tetrahedron composed of a silicon atom surrounded by four oxygen atoms, and 2) aluminun (iron, magnesium, etc.) octahedral unit that, ideally, has one of these atoms surrounded by six hydroxal units. Fig. 1 is a diagrammatic sketch of the montmorillonite structure. In the montmorillonite structure, the tetrahedron are pointed inward and attached to the octahedral units so that the O= atoms replace the hydroxal units where they are bonded; hence two-thirds of the hydroxal units

Jan 1, 1962