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By T. E. Wayland

The general geology and mineralogy of bentonite, including pertinent technological details of clay minerals in the montmorillonite group, are summarized. Worldwide occurrences of bentonite deposits are reviewed, with emphasis on geologic methods and economic principles of evaluation. Active mining districts are described and areas with potential for current and future development are assessed. The production history of bentonite, principal producers, major consumers, and indicated trends are noted; also attention is directed to the hundreds of minor industrial uses of this versatile material, ranging from the manufacture of (A)cid neutralizers to (Z)eolite water softeners. Recent significant results of both basic and applied research are reported, with suggested lines of investigation for current and near-future consideration.

Jan 1, 1972

By Karl Fetters

IN the process of making steel in the open-hearth furnace the refining of the metal during the working period of the heat is largely accomplished through the agency of the slag. From the birth of the process until the present day steelmakers have recognized the importance of the slag in determining the composition of the metal and the quality of the product. The general relationships between slag composition and metal analysis have long been known, at least in a qualitative or approximate fashion. For examples, the iron oxide content of the slag is higher on lower carbon heats; the more basic slags are higher in iron oxide for a given carbon content; certain amounts of iron oxide and lime are required for phos-phorus removal and a high lime-silica ratio is needed if the sulphur content of the metal is to be diminished. In recent years a number of quantita-tive relationships involving these and other variables have been developed through plant and laboratory studies by numerous investigators in this country and abroad. The direct comparison of laboratory and open-hearth data involves the question of the degree to which each approaches the conditions of chemical equilibrium, a question which, from the open-hearth standpoint, we are scarcely yet in position to answer. And, although a considerable body of dependable equilibrium data has been obtained in the laboratory, this work has not yet been extended to cover the ranges of slag composi-tion encountered in basic open-hearth practice. In the present study we shall not attempt to draw comparisons between data from the two sources; nor do we attempt to draw conclusions as to the approach to chemical equilibrium in the open-hearth furnace. Many of the operating variables that are likely to be erratic or unrecorded during the earlier stages of the heat become more consistent and are more readily subject to observation and control during later stages. For example, undigested lime or ore gradually goes into solution, the rate of carbon drop levels off, and the temperature of the metal is brought under control. For these and other reasons a greater degree of self-consistency is likely to be found among data obtained during the

Jan 1, 1940

By H. W. Graham

AS these annual occasions in honor of Henry Marion Howe continue through the years, there is progressively less likelihood that the lecturer will have had personal knowledge of Dr. Howe. The present speaker is one of those who unfortunately had no opportunity to come under the inspiring presence of this great metallurgist. A review of Howe's work shows it to cover a comprehensive range of interests and to evidence an impressive richness of detail. Not only was Howe at home in the laboratory, but he was familiar with the processes of iron and steel making and had a real understanding of them writings include much that is descriptive of processes with a wealth of material that is becoming of increasing historical value. He recorded his studies of the theoretical aspects of processes and published at least two process classifications, one in 1890 that was lengthy and somewhat theoretical, and a second in 1906 that was more of a practical listing. Wide as Howe's field of interest was, it is significant of the circumstances of his time that he gave little consideration to raw materials or to their effect on iron and steel making processes. In 1933, Waterhouse, Howe lecturer for that year, presented a descriptive summary of the major steelmaking processes, and in 1946 Joseph discussed the blast furnace process. Otherwise Howe lectures have not dealt with processes as major subjects. In today's lecture, with no effort to describe the mechanical arrangements of iron and steel making facilities, it is proposed to examine the essential technological elements of the processes, to explore the inter-relation of these elements, and particularly to seek recognition and understanding of those factors which determine why certain processes are or are not used. The discussion of this lecture will deal with the major well-known large tonnage processes, with only such attention to processes of minor tonnage and special character as may be warranted for explanation by contrast. Subject to the errors of generalization and the short- comings of condensation involved in presentation limited to a single hour, it is proposed to examine broadly but intensively those operations which convert raw materials into steel. It is an innovation for a Howe lecturer to discuss the raw materials of the iron and steel industry, but the changing circumstances of passing years intensify the influence of raw materials on processes and require the metallurgist to be alert for the process adjustments that may become advisable or mandatory. For a half century the metallurgical processing of iron and steel has followed a surprisingly straight path, but this does not necessarily mean that there are no curves in the road ahead. Ages ago primitive man came to know iron in its metallic form, not only by the

Jan 1, 1947

By Joseph Chalmers, E. L. Rawlins, D. B. Taliaferro

PRoblems dealing with the movement or migration of fluids through porous beds have been the subject of much research. The subject is not peculiar to the production of oil and gas, as many investigators have studied the nature of this movement and its relationship to the problems of other industries. Darcyl conducted a series of experiments relating to the percolation of water through filter beds. King2 carried on an extensive series of laboratory experiments with the object of formulating some conception of the rate of movement of water through soils and sand strata in the drainage of surface water into underground channels and subsequent recovery of this water through wells drilled into the source beds for irrigation purposes. Slichter3 undertook a study of the same problem from a mathematical standpoint, and more recently Furnas4 has investigated the flow of gases through beds of broken solids with particular reference to blast-furnace operation. With specific reference to gas production, Muskat and Botset5 of the Gulf Research Laboratory undertook an experimental study to establish quantitatively the characteristics of and laws governing the flow of gases through consolidated and unconsolidated porous materials of fine texture with a view of predicting the performance of gas in an underground reservoir. There seems to be a general agreement that many of the relationships between the numerousfactors influencing the flow of fluids through porous materials are far too complicated to be attacked by analytical methods based upon a knowledge of hydrodynamics. For gases, the laws of

Jan 1, 1932

By J. J. Bowman

The term "secondary aluminum" frequently is used loosely and often is considered synonomous with "inferior quality." Under war conditions, when every pound of material must contribute its share to the job at hand, this type of thinking is most unfortunate. Actually, given a supply of segregated scrap, an experienced smelter can produce remelted ingot of good quality, comparing closely to the analysis of the original material, and of considerable value of the war effort. The alloys he can produce are, of course, somewhat controlled by the analysis of the available scrap and, by the very nature of things, some of his production is not suitable for indiscriminate use. However, remelted scrap ingot provided about 273,2 per cent of this country's domestically-produced 1942 aluminum supply and probably will comprise about 39 per cent of the 1943 supply. (Canadian production is excluded from these figures.) That this part of the supply remains important is indicated by a recent report that "requirements" for the second quarter of this year were about 14 per cent greater than the supply, even though that supply will be almost twice the prewar annual production. (And those requirements, incidentally, were prepared after many conservation measures had been taken into account.) Since W. Bonsack recently has published a paper2 on the effects of the various alloying elements and impurities on the properties of aluminum, and such con¬siderations really are the important ones in a discussion of the metallurgy of secondary aluminum, it is planned to restrict this discussion more to a consideration of the sources, general characteristics and possible uses of these materials. For the purpose of this discussion, mill (or run-around) scrap may be disregarded and only plant scrap and obsolete scrap considered. Plant scrap, of course, is that scrap which is generated during the production of some part or assembly from a fabricated form of aluminum, such as sheet, tubing, forgings, castings or the like, and it may consist of solids (including rejected parts or subassemblies) or of machinings. To the extent that the several alloys are effectively segregated and the material is properly identified, the composition after remelting can be rather closely controlled or predicted. Obsolete scrap, on the other hand, is the "junk" which accumulates because of the wearing out or breakage of some piece of equipment. Although it is almost always in the form of solids, the accumulation includes many different alloys (often in the same assembly) and may include a considerable amount of nonaluminum material. The "metallics" recovered from drosses also contribute a portion of this class of material. The composition after remelting, therefore, may vary over rather wide limits and can not be very accurately predicted in any specific instance. SEGREGATION OF PLANT SCRAP Unfortunately, perhaps, it was not very common practice before the war to

Jan 1, 1943

By Clyde Wyman

THERE has always been a question as to the extent to which oxidizable alloys might he recovered from charged scrap in the, acid electric furnace. While qualitative information was not lacking, the quantities that might be recovered and the conditions best suited for such recovery were not clearly defined. The present investigation was carried out to determine the efficiency of alloy recovery from residuals contained in the bath, especially in regard to the recovery of vanadium. A series of 24 heats was produced at the Burnside Steel Foundry Co., including medium manganese-molybdenum-vanadium, manganese-chromium, and grade B steels, in which vanadium recoveries from the residual vanadium were investigated. Recoveries of other alloys were also studied from the accumulated data. These heats were produced in a 5-ton acid-lined electric furnace. The analysis of metal and slag samples and the micrographs were prepared by the Research Laboratories of the Vanadium Corporation of America. In addition to the vanadium contained in the scrap charge, ferrovanadium was added to the charge and to the molten bath to bring the residuals up to the desired level. Vanadium pentoxide (V2O5) in one series of heats was added to the bath after meltdown, for the same reason. In addition to the general furnace practice, the slags of these various heats were treated with coke breeze, Ferrocarbo-S (silicon carbide), and aluminum dross to determine the effects of different reducing agents upon the alloy recoveries and upon the final product.

Jan 1, 1947

By R. P. Smith

Iron-carbon alloys containing a single-phase austenite region and a two-phase azcstenite + cementite region at the desired temperature were prepared by partial carburization of iron or partial decarburization of carburized iron. Each sample was held at a fixed temperature until equilibrium was achieved. Analysis of the austenite for carbon then gave the solubility of cementite in austenite. Solubility measzcrements were made for the temperature range 734° to 1012°C. These values together with other data give 7560 cal for the mean heat of solution of cementite in austenite, and 0.765 pct C for the eutectoid composition of austenite. They also indicate that graphite is the stable phase at all temperatures between the eutectoid and eutectic temperature. Measurements of the solubility of cementite in austenite at 927oand 1011 "C, using a method based on the equilibration of iron with boro-cementites, are reported. The solubility of cementite in austenite (?-iron) has been computed by Darken and Gurry1 from the observed solubility of graphite in austenite, and the thermodynamic properties of pure iron and of iron-carbon alloys. They have shown that the solubility of cementite is greater than that of graphite in the temperature range between the eutectoid and eutectic, and thus that cementite is metastable with respect to graphite and austenite saturated therewith. Since their computation is not in accord with the earlier experimental work of Mehl and wells,' the present direct determination of the solubility of cementite in austenite was undertaken. EXPERIMENTAL PROCEDURE Each iron rod about 1/2 in. O.D. by 4 in. was first carburized at a temperature and with a H2-CH4 gas mixture such that the carbon content would be greater than that corresponding to the solubility of cementite in austenite at the desired (lower) temperature; sufficient carburizing time was allowed that the carbon content became substantially uniform, as illustrated by Curve A, Fig. 1. The sample was then partially decarburized with a hydrogen-water vapor mixture, giving a carbon distribution as schematically illustrated by Curve B. The sample was then held in a helium atmosphere at the temperature at which the solubility was to be determined until the decarburized portion of the sample came to equilibrium with that containing cementite. Curve C of Fig. 1 represents schematically the final carbon distribution; the horizontal portion corresponds to the carbon content of austenite saturated with cementite. To bring the sample to room temperature without change in the carbon distribution and in machinable condition, it was first quenched in a salt pot at 480°C, then in water at room temperature. Successive layers were machined from the center 2 in. of the sample and analyzed for carbon by the usual

Jan 1, 1960

By Richard W. Smith

There are three distinct varieties of phosphate rock, in Tennessee, known commercially as: (a) the "brown" rock, which is the residual product of the weathering and natural concentration of certain phosphatic Ordovician limestones; (b) the "blue" rock, which is an unaltered phosphatic stratum of Mississippian or Devonian age; and (c) the "white" rock, which is the result of chemical replacement and deposition. Before 1894, South Carolina and Florida had supplied most of the phosphate of the United States, South Carolina leading until that date and Florida from then until the present time. In December, 1893, the blue phosphate of Tennessee was discovered almost simultaneously on Swan Creek, in Lewis County, by two independent parties—by one as the result of a careful and systematic search for a workable deposit of the long known kidney phosphate, and by the other through mistaking it for a "bloom" of coal. Leases were taken and, with further prospecting disclosing other deposits in the region, the development progressed as rapidly as could be expected without railroad transportation. In January, 1896, Judge S. Q. Weatherly, who was interested in the development of the blue phosphate, while riding along the road south of Mt. Pleasant, noticed some slabs of a brown rock in place above the limestone. He took samples, and had them analyzed, thus discovering the high-grade brown phosphate of this district. This discovery was kept a secret until July, 1896, when mining was started at the village of Mt. Pleasant. Development proceeded rapidly, many owners obtaining their capital by the sale of their rock fences, which were largely composed of slabs of high-grade brown phosphate. The development of the brown rock, which is richer and more easily mined than the blue, caused Tennessee to advance from a poor third in production to second, surpassing the output of South Carolina, and being excelled only by Florida.

Jan 1, 1927

By A. M. Sarem

For the performance prediction of multiphase oil recovery processes such as steam stimulation, there is an acute need for three-phase relative permeability data. No fast and simple experimental technique, such as the unsteady state method proposed by Welge for two-phase flow, is available for the three-phase flow. In this paper, an unsteady - state method is presented for obtaining three-phase relative permeability data; this method is as fast and easy as Welge's method for two - phase flow. Analytical expressions are derived by extension of the Buckley-Leverett theory to three-phase flow to express the saturation at the outflow face for all three phases in terms of the known parameters. It is assumed that the fractional flow and relative permeability of each phase are a function of the saturation of that phase. Other simplifying assumptions made include the neglect of capillary and gravity effects. The effect of saturation history upon relative permeability is acknowledged and attainment of similar saturation history in laboratory and field is recommended. The required experimental work and computations are simple to perform. The test core is presaturated with oil and water, then subjected to gas drive. During the test, required data are the rates of oil, water, and gas production, together with pressure drop and temperature. The ordinary gas-oil unsteady-state relative permeability apparatus can be readily modified to measure the required data. The proposed technique was applied to samples of a Berea and a reservoir core. The effect of saturation history upon relative permeability was studied on one Berea core. It was found that increase in initial water saturation has a similar effect upon three-pbase relative permeability as it does in two-phase flow. INTRODUCTION In the light of increasing demand for three-phase relative permeability data for predicting the performance of thermal and other multiphase-flow recovery processes, a simple and accurate method of experimental determination of such data is extremely desirable. Leverett and Lewis 1 described the simultaneous flow method of obtaining three-phase relative permeability data. However, Caudle et al.2 reported that this method is very time consuming and cumbersome. Corey3 proposed calculating the three-phase relative permeability from measured krg data. Corey's theory is based on simplified capillary pressure curves,4 assuming a straight line relationship between I/Pc2 and saturation. Also, Corey's method assumes a preferentially water-wet system. The simplest and quickest method of obtaining three-phase relative permeability data is the unsteady-state method where, for instance, oil and water are displaced by gas. However, in such a test the correlation of average saturation with relative permeability does not give a valid relationship because the rates of oil, water and gas flow in the sample change continuously from the upstream to downstream end. This difficulty in calculating valid relationships was solved by Welge for two-phase flow by deriving an expression for determining the outflow face saturation from Buckley and Leverett frontal advance equations.5,6 In this paper, relations are established to determine the outflow face saturation and relative permeability to all phases in a three-phase flow displacement experiment. PROPOSED METHOD The fundamentals established by Buckley and Leverett5 for two-phase flow were extended to three - phase flow and used as a basis for the derivation of saturation equations. This approach is comparable to Welge's6 use of Buckley and Leverett theory in arriving at expressions to determine the outflow face saturation of the displacing fluid in a two-phase flow system.

Jan 1, 1967

By Richard F. Miller, W. E. Milligan

Work was undertaken two years ago at the Hammond Laboratory for the purpose of determining the magnitude of the elastic range in single crystals of pure metals by means of creep tests, the assumption being made that if a true elastic range exists, the elastic limit represents the maximum stress for no creep. A sensitive extensometer was constructed, and creep tests were made on zinc single crystals at a variety of loads and temperatures1. It was soon discovered that there is no measurable elastic limit in ductile zinc single crystals at, or above, room temperature. The inference that pure metallic single crystals may not possess a definite elastic range was not justified, however, since zinc had been tested in creep only above its recrystallization temperature, and several investigator2,3,4 had already shown that above the recrystallization temperature polycrystalline metals will flow under very small stresses, while below that temperature stresses of a much larger magnitude are required. For that reason, it was decided to extend the study of the elastic limit to other metals having a higher recrystallization temperature than zinc. Aluminum and silver were selected, because of the ease of obtaining pure materials and of preparing large single crystals, and because the crystallo-graphic glide system of these metals is well known. Owing to the limited time available, the elastic range was investigated by slow tensile tests rather than by creep tests. Production of Specimens A luminum Recrystallized single crystals were prepared from 99.95 per cent aluminum supplied by the Aluminum Company of America. The ingots were melted in an Acheson graphite crucible in a gas furnace, and cast

Jan 1, 1937

By F. V. Lenel

INTRODUCTION Two years ago in Chicago a seminar was held on the theory of sintering of pure metal powders As an introduction to this seminar Dr Rhines1 gave an excellent survey of the literature on this subject His method of presentation was to summarize the experimental observations on sintering and from them to develop a composite theory of sintering in which he combined all the important contributions to the theory into one organic whole In contrast to the mechanism of sintering of pure metal powders, which, of course, always takes place in the solid phase, sintering in the presence of a liquid phase, cannot be treated as one unified mechanism, such as the sintering mechanism of pure metals The reason is that there are really several mechanisms depending upon the type of alloy system which is sintered and the field of its constitutional diagram in which the sintering takes place Two mechanisms have been investigated and will be reviewed in this paper In the first mechanism the liquid is present during the entire time while the compacts are at the sintering temperature In other words they are sintered between the liquidus and the solidus of the alloy System and are heterogeneous during the entire sintering cycle The second mechanism applies to alloys in which the liquid phase is formed during the sintering process, but disappears before the sintering process is completed through diffusion and formation of a solid solution These alloys are therefore homogeneous at the end of the sintering cycle This second mechanism is more complicated because of the two stages of sintering, the liquid and the solid, as they may be called It is therefore not surprising that the few detailed investigations of sintering in the presence of a liquid phase have been concerned with heterogeneous sintered alloys, namely the tungsten-nickel-copper alloys, which is the so-called "heavy alloy," and the cemented carbides The mechanism of sintering of these systems is characterized by the fact that theoretical or near theoretical density is attained during sintering, while simultaneously a distinct grain growth takes place through solution of the smallest grains of the solid phase in the liquid phase and reprecipitation on the larger grains In the first part of the survey this sintering mechanism which is called for short the heavy alloy mechanism is treated in detail In the second part of the survey experimental observations for the sintering of homogeneous sintered alloys where the liquid phase disappears before the completion of sintering are discussed Much less systematic work has been done on these alloys to which the commercially important porous bronzes and the iron-nickel-aluminum permanent magnet alloys belong Emphasis will be laid throughout this survey upon the microstructural and density changes during sintering because the sintering mechanism can usually be described directly by these changes Other

Jan 1, 1948

By J. A. Younkins, J. A. Brooke

In 1931 the Philadelphia Company acquired by lease several coal mines in southern Greene County, Pennsylvania. These mines were known as the "Dora," "Seventh Pool" and "Rosedale" mines in the Sewickley seam, and the "Rosemary," "Seventh Pool" and "Warwick" mines in the Pittsburgh seam. All these mines are in the immediate vicinity of Greensboro, Pa., with considerable river frontage on both sides of that village. The mines in each seam are contiguous and to some extent the properties in the two seams lie one above the other. In 1938 the property known as the "Sandy Run mine," in the Sewickley seam, adjoining the Dora mine, was purchased from the Fredericktown Coal and Coke Co. Altogether, by purchase and lease, the company gained control of approximately 3400 acres of coal land in Greene County, from which it was estimated that some 20,000,000 tons of coal could be extracted. Geology of Warwick Properties Both seams of coal outcrop along or near the river on both sides of the town of Greensbgro. They lie on the eastern slope of the Lambert syncline, near the southern end of the axis, consequently the predominant dip of the seams is away from the river, so that development for river handling has the unavoidable disadvantage of adverse grades for haulage to the outside. Predominant grades away from the river at right angles to the "butt" cleat of the coal average about 2.25 per cent dipping in a westerly direction, but local dips occur, which are considerably greater. Predominant grades parallel to the river and at right angles to the "face" cleat of the coal average about one per cent dipping in a northerly direction. Both seams of coal lie in the Monongahela formation, the Pittsburgh bed being the bottom measure of the formation and the Sewickley bed lying about 90 it. above. Approximately midway between the two lies the Redstone coal bed, which is generally thin and of erratic occurrence and therefore of little commercial value. It is mined only locally where it attains sufficient thickness. Sewickley Bed The Sewickley bed is commonly called the "five-foot" or Mapletown" seam, because in Pennsylvania it reaches its greatest thickness and has been mined most extensively in the vicinity of the village of illapletown, approximately one mile west of Greensboro. In the early development of the Warwick properties, which occurred near the river, the seam had an average of 5 it. 2 in. in height. As development proceeded away from the river, however, the height gradually decreased until the average height of the present workings is about 4 ft. 6 in. Present development is encountering lower coal

Jan 1, 1947

By J. A. Younkins, J. A. Brooke

In 1931 the Philadelphia Company acquired by lease several coal mines in southern Greene County, Pennsylvania. These mines were known as the "Dora," "Seventh Pool" and "Rosedale" mines in the Sewickley seam, and the "Rosemary," "Seventh Pool" and "Warwick" mines in the Pittsburgh seam. All these mines are in the immediate vicinity of Greensboro, Pa., with considerable river frontage on both sides of that village. The mines in each seam are contiguous and to some extent the properties in the two seams lie one above the other. In 1938 the property known as the "Sandy Run mine," in the Sewickley seam, adjoining the Dora mine, was purchased from the Fredericktown Coal and Coke Co. Altogether, by purchase and lease, the company gained control of approximately 3400 acres of coal land in Greene County, from which it was estimated that some 20,000,000 tons of coal could be extracted. Geology of Warwick Properties Both seams of coal outcrop along or near the river on both sides of the town of Greensbgro. They lie on the eastern slope of the Lambert syncline, near the southern end of the axis, consequently the predominant dip of the seams is away from the river, so that development for river handling has the unavoidable disadvantage of adverse grades for haulage to the outside. Predominant grades away from the river at right angles to the "butt" cleat of the coal average about 2.25 per cent dipping in a westerly direction, but local dips occur, which are considerably greater. Predominant grades parallel to the river and at right angles to the "face" cleat of the coal average about one per cent dipping in a northerly direction. Both seams of coal lie in the Monongahela formation, the Pittsburgh bed being the bottom measure of the formation and the Sewickley bed lying about 90 it. above. Approximately midway between the two lies the Redstone coal bed, which is generally thin and of erratic occurrence and therefore of little commercial value. It is mined only locally where it attains sufficient thickness. Sewickley Bed The Sewickley bed is commonly called the "five-foot" or Mapletown" seam, because in Pennsylvania it reaches its greatest thickness and has been mined most extensively in the vicinity of the village of illapletown, approximately one mile west of Greensboro. In the early development of the Warwick properties, which occurred near the river, the seam had an average of 5 it. 2 in. in height. As development proceeded away from the river, however, the height gradually decreased until the average height of the present workings is about 4 ft. 6 in. Present development is encountering lower coal

Jan 1, 1947

By Richard McCaffery

WHEN we began the study of blast furnace slags we limited our work at first to a study of those slags containing only lime, alumina and silica. In our paper1 on some of the results of this first work, the solubility of. sulfur in slags containing no magnesia was reported and the question of sulfur solubility and slag viscosity discussed. There has been, for a long time, a very great difference of opinion among metallurgists as to .the effect of magnesia in blast furnace slags, and the literature is full of expressions of the most contrary opinions on the subject. As a result, our next publication2 developed the constitution of slags considered as a four-component system, silica-alumina-lime-magnesia, and advanced an explanation of slag structure which accorded with the facts and with scientific theory. The present paper continues our study of the general subject of slags. As blast furnace slags are included in the silica-alumina-lime-magnesia system, which is a particular case of four-component solutions, we have determined that there are 22 components (Table 1), which may enter into the silica-alumina-lime-magnesia system and that 10 or 12 of these components may be present in blast furnace slags which are within the ordinary ranges of composition. To have a very definite conception of the behavior of these components in a slag, we have developed the theory of the cooling of a four-component solution from the liquid state to the solid and the conclusions that we obtained have been made use of in this paper. On account of the importance of the four oxides and 18 compounds which enter into the silica-alumina-lime-magnesia system, some method of calculating the percentages of the various compounds that are present in the slag when the percentages of the oxides are given, seemed very desirable and we develop a method later herein for doing this, and finally we give illustrations of

Jan 10, 1926

By E. H. Crabtree, J. D. Vincent

Probably no metallurgical process in the history of the mining industry has been responsible for such increased mineral production as has flotation. It has made possible the economic treatment of low grade and complex ores which, with the old methods of gravity concentration, would have been classed as worthless. Starting with the sulfide ores of copper, lead, and zinc, the process has been applied to almost all metallic and nonmetallic minerals. Today, the sulfides of the common metals not only can be readily recovered, but can be separated from each other. Thus, three or four mineral recoveries from the same ore, such as galena, chalcopyrite, sphalerite, and pyrite, are possible. Molybdenite is recovered initially with copper sulfides and the two are subsequently separated. Flotation of metallic gold and of native copper and graphite is being commercially practiced. The carbonates of some of the base metals, principally those of lead, can also be concentrated. Flotation of the oxides, silicates, phosphates, and other so-called non- metallic minerals represents the greatest advance in the art in the last few years. Today, commercial plants are successfully treating such minerals as feldspar, garnet, ilmenite, muscovite, cassiterite, cement rock, fluorspar, phosphate rock, sylvite, and a host of others. Flotation of the various types of iron ores along with other concentration methods is today the subject of a tremendous amount of investigation on the iron ranges. EARLY PATENT HISTORY OF FROTH FLOTATION Although what we call the froth flotation process as distinguished from bulk oil processes was not used commercially until 1905, many investigators had recognized its possibilities long before the twentieth century. The principal patents issued throughout the years give us a method of recording early flotation history. BULK OIL PROCESSES: In 1860, William Haynes patented (British Patent 488) a process for separating oil-wetted sulfide minerals from water-wetted gangue minerals by agitating the dry ground ore with oil and then the mixture with water. In 1877, the Bessel brothers patented (German Patent 42, Class 22) a process where a mixture of graphite ore was mixed with 1 to 10% oil; after adding water, the

Jan 1, 1962

By David W. Mitchell

WHILE pure magnesium does not corrode rapidly the presence of even very small quantities of certain other metals accelerates corrosion remarkably. Because magnesium is such an electropositive metal (E° = +2.34 volts)' the presence of substances that permit galvanic activity is extremely undesirable. It is stated that as little as 0.017 pct of iron in magnesium causes a marked increase in the corrosion rate.2 Magnesium and its alloys are commonly melted in iron or steel pots; consequently the commercial metal has the opportunity to pick up iron if it has that tendency. Quantitative data on the solubility of iron in magnesium are of practical as well as of academic interest. Some magnesium alloy castings tend to have large grain size unless suitable treatment is given to the liquid metal just prior to casting. One method of grain refinement consists of "superheating" the metal just prior to casting. "Superheating" is heating to a temperature 100 to 200°C above the casting temperature and holding for a short period of time. Superheated metal has a much finer grain than unsuperheated metal. A satisfactory explanation of this phenomenon has not been forthcoming. One hypothesis attributes the grain refinement in the superheated metal to precipitation of some phase that is miscible at the temperature of superheat but not miscible just below the casting temperature and which is thought to provide nucleating centers for crystallization. This phase, if the foregoing hypothesis is correct, would probably be a metal or an intermetallic compound. Of the metals likely to be found in magnesium alloys, iron is one of the most likely candidates for the role of grain refiner for iron occurs in small quantities in all commercial magnesium and magnesium alloys. A. Beck' states that magnesium, in either the liquid or the solid state, cannot dissolve iron and that iron exists as a finely divided suspension which does not settle out because of its extreme fineness. Beck also presents a micrograph showing a large iron dendrite in magnesium but does not comment on the crystallization of iron from a solution supposed to contain none. It is doubtful that dendrite formation from suspended iron would be possible. This suspension theory is the basis of patents4 covering the removal of iron from magnesium by allowing the iron particles to act as nuclei for the formation of primary magnesium crystals which can be separated by segregation. Also covered by patents is the removal of iron by the addition of another metal to form an intermetallic compound with the iron which, because of its increased particle size, is able to settle out of the molten metal. Here, too, quantitative information on the extent of iron solubility in liquid magnesium is of more than theoretical interest. M. Hansen,5 in his critical collection of the data on binary alloys, states that iron is not soluble in liquid magnesium. W. R. D. Jones6 who studied the physical properties of low iron magnesium alloys observed a

Jan 1, 1948

By Roshan B. Bhappu, Raul A. Deju

A method is proposed by which the chemical reactions between water and a silicate bed can be related to equations of flow. First the reaction mechanism is studied both theoretically and experimentally. Once the reaction mechanism is established, the equations of flow are solved, and a solution (under physically reasonable side conditions) is obtained. Experiments to substantiate the solution are also presented. The knowledge of surface reactions at the water-solid interface is of critical importance in extractive metallurgy. This is especially true in regard to the froth-flotation process of mineral concentration and all phases of hydro metallurgical recovery of metals. Similarly, the problem of ground-water contamination is one of growing concern, not only because of the increasing demands on our sources of supply but also because of the increasing necessity to find vehicles of waste disposal. The hydrochemistry of waste waters must be understood to exploit and develop such resources properly. To understand these problems, it is necessary to obtain a better insight into the reactions that take place between water and a solid packed bed. To do this, we will develop here in a theoretical model that predicts the fate of a chemical species in solution as it reacts with a silicate bed through which the liquid percolates. The treatment will be one-dimensional in nature and will not include dispersion. Experiments will also be presented to substantiate the theoretical model, using the silicate minerals listed in Table 1. This paper is preliminary in nature and is part of a larger study of the surface chemistry of the silicate-water interface. Mechanism of Surface Reactions In a previous paper,' the authors discussed the properties of various silicate minerals from a mineralogical standpoint. Now efforts will be made to study the reactions that occur when these minerals are put in contact with water. The reactions occur almost entirely in the surface layer of the mineralsa and are termed sorp-tion reactions. In this study sorption denotes the composite of all physical adsorption and chemical adsorption occurring between the silicate surface and the water in contact with it. A model of sorption as seen from a chemical-bond standpoint is presented below. On the basis of this model, the surface reactions between deionized water and a silicate mineral can be studied. Sorption Model: It is known that as the oxygen-silicon ratio increases from quartz to the olivines, a greater percentage of the oxygen bonding power is available for bonding to cations other than silicon. Hence, with an increasing oxygen-silicon ratio, the oxygen-to-metal bonding increases. Upon the fracturing of a silicate-mineral crystal, the oxygen-metal bond breaks more easily than the stronger oxygen-silicon bond, resulting in a negatively charged surface. Then, if the mineral is immersed in a liquid containing hydrogen ions, the negatively charged surface should tend to be neutralized by hydrogen ions from solution, resulting in a change of the solution pH. Thus, an increase in the degree of sorption of hydrogen ions must occur as the oxygen-silicon ratio in the crystal structure increases. Also in a previous paper,' the authors found that for a given silicate mineral the change of pH with time is given by

Jan 1, 1971

By F. Twyman

PART I.-QUALITATIVE, SPECTRUM ANALYSIS THOSE chemists (they are still greatly in the minority) who use the spectroscope, use it very often, and find it almost indispensable. As a means of detecting minute quantities of the metals it is unrivalled. A metal can be readily distinguished in the presence of any other element, compound, or mixture without the necessity of separation. The qualitative analysis of the metallic constituents of a substance, which, the spectroscope gives so easily, is a sure basis for planning a chemical analysis. As the determination of each element proceeds the purity of precipitates maybe checked as often as desired. If, possessing these advantages; the spectroscope has been neglected in general chemistry, it is not surprising that it was neglected in metallurgical chemistry; for many of the impurities which are of industrial interest, even when they are present in a metal or alloy in small quantities, are not then always easily detected by the examination of their visible spectrum. The history of the development of the art has been given in Bureau of Standards Scientific Paper No. 444.

Jan 1, 1928

By A. E. Dwight

Lattice parameters were determined for eighteen equiatornic alloys of the CsCl-type structure, ten of which were previously un-reported. It was found that fomation of the CsCl-type structure in binary alloys of the transition elements is largely dependent on position of the elements in the periodic table. The relative size of the two elements was not found to be a controlling factor. A recent paper by Beck, Darby, and Arora1 corre-lates the occurrence of CsC1-type ordered structures with the position of the constituent elements in the periodic table for the first long period. It was also suggested that a definite increase in relative bond strength between unlike atoms occurred when, in binary alloys of iron-group elements, the other component is changed from a chromium-group element, to a vanadium-group element, to titanium. A later paper by Philip and Beck2 noted that the lattice contraction increased in the order CrFe, VFe, and TiFe. It was also noted by Philip and Beck2 that the lattice contractions of CsC1-type alloys decreased in the order: TiFe, TiCo, and TiNi, which is an apparent reversal of the contractions expected from the position in the periodic table. It was suggested that the increasing lattice contraction is an indication of increased stability, i.e., greater A-Bbond strength. The present investigation was carried out to determine whether the relation of the position in the periodic table to the formation of the CsC1-type structure was also correct for alloys involving the second and third long-period elements. A systematic search was made for CsC1-type structures among equiatomic alloys and for those found, the lattice contraction was determined. EXPERIMENTAL TECHNIQUE The elements Y, Gd, Ti, Zr, Hf, V, and Cb are designated the A group and the elements Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, and Au are designated the B group. Equiatomic alloys were prepared for 57 AB combinations. The alloys were arc melted in a multicrucible furnace3 in buttons ranging from 5 to 20 g. Chemical analyses were not made, as the charge weights agreed closely with those of the buttons after melting. The alloy buttons were homogenized at 800° to 900°C. Metal log raphic and X-ray specimens were prepared and heat treated at temperatures from 600° to 1200°C. Specimens for X-ray diffraction were usually ground to a powder in an agate mortar; however, needle-shaped solid specimens were used when the alloy was sufficiently ductile to permit their preparation. Diffraction patterns were taken with a Straumanistype Debye-Scherrer camera using filtered Cu or Co radiation. The lattice parameters were obtained in A by plotting the calculated a0 values against the cos29/sin 0 + cos2?/? function and extrapolating linearly to ?= 900. Metallographic control specimens were polished on cloth wheels with diamond paste and etched with various phosphoric and nitric acid reagents. RESULTS The eighteen equiatomic alloys listed in Table I gave evidence of a cubic structure with two atoms in the unit cell, although two of these cubic structures exist only at elevated temperatures and transform to a tetragonal structure on quenching. Nine of these eighteen alloys gave diffraction patterns with super-lattice lines showing that the structure is of the CsC1-type. The lack of superlattice lines in patterns of the other nine alloys may be attributed to the small difference in atomic scattering power of the components. Metallographic study indicates the occurrence of nine narrow single-phase fields at the AB composition. Any or all of these nine may also have a CsC1-type structure. The VFe alloy was found to have a CsCl-type structure by Philip and Beck2 through the use of CrKa radiation (for which the scattering factor of V is anomalously low), whereas the Cu radiation used

Jan 1, 1960

By K. Tangri, M. Chaturvedi

The addition of 0.5 wt pct Cu to Zr-2.5 Cb alloy increases the as -quenched hardness of the hexagonal martensitic a' phase, produced by water-quenching bccß-Zr phase, by about 35 pct. This strengthening has been attributed to the solid -solution hardening of the matrix. On aging ternary martensite, a' phase reverts to equilibrium a and Zr2Cu and ß-Cb precipitate out, mainly at the twin and grain boundaries, causing a secondary hardening of the matrix. COLD-worked Zircaloy-2 pressure tubes have been in use in power reactors for a considerable period of time. The search for a better material led to the development of Zr-2.5 wt pct Cb alloy which in the quench-aged condition develops 50 pct more strength than that of cold-worked Zircaloy-2, however, its corrosion resistance in water and steam in the temperature range of 316" to 400°C, in absence of neutron flux, is inferior to that of zircaloy-2.' Work carried out by Ells et al.1 and Dalgaard2 has shown that the corrosion properties of Zr-2.5 wt pct Cb alloy can be considerably improved by the ternary addition of 0.5 wt pct Cu. This paper is concerned with the effect of 0.5 wt pct Cu on the formation of martensitic a and its aging characteristics in a Zr-2.5 wt pct Cb alloy. MATERIALS AND EXPERIMENTAL TECHNIQUES Zr-2.5 Cb-0.5 Cu (referred to as the ternary alloy) and Zr-2.5 Cb (referred to as the binary alloy) alloys, supplied by the Chalk River Nuclear Laboratories of the AECL were used. The detailed chemical analysis is given in Table I. Cold rolling and swagging with frequent intermediate anneal of 1000°C were used for the initial fabrication of the alloys. All the heat treatments were carried out after the specimens were wrapped in zirconium foils and encapsulated in silica tubes under a vacuum of 5 x 10-6 mm of Hg. For optical metallography and hardness measurements specimens were mechanically and then chemically polished in a 45 pct HNOj, 45 pct HzO, and 10 pct HF solution. Hardness was measured on a Vickers hardness tester using a 10-kg load. For each specimen at least fifteen indentations were made in order to obtain a representative value. The phase identification and structural analysis were carried out using X-rays and electron diffraction techniques. Wires of 1.5 mm diam reduced to 0.12 mm diam by chemical etching were used for making Debye-Scherrer powder patterns using Cu Ka radiation in a 114.6 mm diam camera. Carbon extraction replicas were prepared by etching the specimens, after depositing a layer of carbon on the metallographic specimen, in one part HF and thirty parts ethyl alcohol. Thin films were prepared by electropolishing heat-treated 3/4 by 1/2 by 0.005 in. thick strips using a modified Bollman-Window technique. The 10 pct perchloric acid-90 pct methyl alcohol bath was kept at -50°C and polishing was done at 5 to 10 V. The thinned specimens were washed in ethyl alcohol at -30º to -40°C and dried between filter papers. Replicas and thin films were examined in a Phillips 300 G electron microscope. For resistivity measurements thin strip specimens 0.02 by 0.3 by 10.0 cm long were used. The potential leads were spot welded to the specimens in order to maintain a fixed length for the initial and the final resistivity measurements. The resistivity was measured by a Kelvin bridge in a temperature controlled room. The temperature was maintained at 72º ±1°F and the accuracy of the resistivity measurements was 0.03 µa-cm. RESULTS As-Quenched Structures. In order to produce a homogeneous matrix to study the precipitation reaction the solution-treatments of both the alloys were carried out in the -field region. From the Zr-Cb phase diagram due to Lundin and cox3 ß/a + ß phase boundary for Zr-2.5 wt pct Cb alloy is 820°C. Ells et al.1 have reported this boundary for Zr-2.5 Cb alloy containing 1100 ppm 0 to be at 920°C. Also, the addition of 0.5 wt pct Cu reduces this temperature by 50°C. Therefore, the solution-treatments were carried out at 1000°C to ensure that the alloys were in ß-phase region. The soaking time was 1 hr and the specimens were water-quenched. The as-quenched hardness of the binary alloy was 245 Vpn whereas, that of the ternary alloy was 330 Vpn. The X-ray diffraction studies indicated that the as-quenched structure of both the alloys consists of martensitic hexagonal phase a', with a c/a ratio of 1.591, and some retained ß-Zr. The presence of a' phase was further confirmed by thin film electron microscopy. Electron micrographs of typical ß-quenched structures of the ternary and the binary alloys are shown in Figs. 1 and 2, respectively. Fig. 3 shows the diffraction pattern from an area similar to that shown in Fig. 1. Although, the as-quenched hardness of the ternary alloy is about 35 pct greater than that of the binary alloy, the structure of both the alloys seems to be the same. The matrix of both alloys is heavily twinned and shows very few dislocations. Furthermore, there is no evidence of any precipitation taking place in either of the two specimens during quenching from the solution-treatment temperature. Aging Behavior of Martensitic a'. The aging kinetics of the ternary alloy were followed by resistivity and hardness measurements. The as-quenched values

Jan 1, 1970