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By Herbert H. Kellogg

IN 1930, Taggart, Taylor and Knoll1found that addition of various electrolytes to suspensions of ground minerals resulted in the stopping or starting of Brownian movement of the suspended particles. On the basis of the many new facts found, they rejected the "classical "[t] theory of Brownian movement and proposed an "ionization" theory. This new theory was further supported in later publications by Taggart.3,4 The acceptance of the ionization theory by men in the field of flotation may be judged by the mention given this theory in Gaudin's "Principles of Mineral Dressing,"5 Wark's "Principles of Flotation,"6 as well as in a recent paper by Fitt, Thomas and Taggart.7 The proponents of the ionization theory have gone further than the mere statement of the new theory. A parallelism between the Brownian movement of mineral particles and their behavior in flotation was reported.1,3,4 Likewise, the correlation between flocculation-dispersion of mineral particles and the Brownian movement of these particles has been investigated.7 Bankoff15 has suggested that "slime-coating" can also be directly correlated with the Brownian movement of the slime particles. In each of the instances mentioned it is the ionization theory of Brownian movement that has been used to "explain" the correlations that were found. The essential conflict between the kinetic theory and the ionization theory can be understood best by a brief description of each. The kinetic theory* proposes that Brownian movement is caused by the impacts of liquid molecules against the solid particles. At any instant of time, the molecular impacts on all sides of the solid particle will not balance, and the particle will receive a push in some direction. According to this theory, all particles suspended in a liquid are in Brownian movement. However, if the particle is very large, the impacts on all sides will very nearly balance and the motion will not be noticeable. Another factor, besides the size of the particle, that affects the magnitude of the Brownian movement is the viscosity of the liquid-the greater the viscosity, the less the displacement of particles by Brownian movement. This theory has been verified experimentally by measurement of the velocity of Brownian movement, and by measurement of the compacting of suspensoid particles under the influence of gravity.2 The originators of the ionization theory found that the addition of various electrolytes to slime pulps caused cessation or commencement of Brownian movement, depending upon the chemical nature of the particle and the electrolyte. The Brownian movement of quartz particles was observed to stop upon the addition of certain electrolytes, where the conditions of the experiment prevented flocculation

Jan 1, 1945

By E. F. Bailey, W. J. Harris

THE temperature of the ferrite to austenite re-action is established frequently by continuous heating experiments. However, equilibrium studies of this reaction have demonstrated that austenite may form at temperatures considerably below those at which the reaction is first observed during continuous heating. Because of this discrepancy, tempering is sometimes performed above the true critical temperature and in these cases austenite forms during tempering. The lowest temperature at which austenite forms and the kinetics of the reaction have been studied by Bain,' Bleakney and Gros-venor,2 and Dube and Cunningham. This austenite can affect the properties either as austenite per se, if it is retained at room temperature, or as a decomposition product if it transforms. The effect of austenite formation during tempering on low temperature impact properties of an 8 1/2 pct nickel steel was reported by Brophy and Miller4 in work published after the present investigation was initiated. They concluded that the improvement in low-temperature notch toughness which followed tempering at certain temperatures could be attributed to the austenite formed during tempering. Kramer et al.5 found anomalous hardness increases and embrittlement after tempering of a low-carbon manganese-nickel steel. They concluded that austenite formed during tempering, and that the decomposition products were responsible for the increase in hardness and the embrittlement. Quan-titative correlations of the microconstituents and mechanical properties were not made by these investigators. The present study was undertaken in order to establish the kinetics of formation of austenite at various temperatures, the characteristics of the decomposition of this austenite, and the relationship between mechanical properties and the phases present. Experimental Procedure A low-carbon manganese-nickel steel was selected because of the sluggishness of its austenite decom-position reactions. The composition of this steel in percent was: C, 0.10; Mn, 3.52; Ni, 2.34; Mo, 0.52; Cr, 0.17; Si, 0.19; V, 0.15; P, 0.019; and S, 0.020. Samples were prepared by forging sections from a large ingot to 3/4 in. bars. Formation and decomposition of austenite were investigated by dilatometric techniques which were checked by X-ray measurements. Dilatometer specimens were hollow cylinders 1 in. long, 1/2 in. diam, with a 1/8 in. central hole. All specimens were aus-tenitized for 1 hr at 1650°F and quenched in water prior to insertion in the dilatometer. Oxidation was prevented by using an inert atmosphere of purified nitrogen. Dilation was measured with a dial gauge which could be read by interpolation to 0.00005 in. Temperature was maintained within ± 3°F by a Brown Electronik Controller. Chromel-alumel thermocouple leads were welded to opposite ends of the specimen with the specimen serving as the hot junction. As a check on temperature uniformity comparison was made of the specimen temperature as measured with the chromel-alumel leads and the temperature of the center of the specimen as measured with a calibrated platinum—platinum-rhodium thermocouple embedded in asbestos in the central hole of the specimen. During heating a 5°F temperature difference was noted below 1000°F, but none above, while in cooling, a 5°F difference was observed from 1300" to 735°F, but none below. Heating rates of 35°F per min and cooling rates of 60°F per min were employed for all dilatometric studies. For transformation studies below room temperature, the dilatometer was allowed to cool to 150°F and then was quenched into liquid nitrogen.

Jan 1, 1951

By Victor De Ysassi

THE iron mines of Spain are located on the mountain ridge forming the boundary between the, Teruel and Guadalajara provinces, called Sierra Menera. They form a property of 25 mines extending over an area of 1,677 hectares (4,140 acres) situated at a height varying from 1,200 m. (3,940 ft.) to 1,500 m. (4,920 ft.) above sea level. The deposit follows the direction north to south; huge masses of ore are being found both on the slopes and at the summit of the Sierra. The ore occurs among quartzites and magnesite limestone, in some places overlaid by quartzite 15 in. (50 ft.) thick; in some others (and this is more general) the ore is overlaid by earth and boulders of quartzite origin,; this layer is about 8 m. (26 ft.) thick. The ore beds occupy the geological horizon of the Superior Trias or Muschelkask, which are here in direct contact with the Silurian quartzites. The lime-stones have been more or less transformed. There is ample evidence to show that these mines were worked in very ancient times-objects and tools employed in mining by the ancient Romans and Arabs are to be found plentifully in old workings which extend down into the deposits. It has been estimated that more than 10,000,000 tons of ore were mined in the old days in this district and carried to the primitive forges in the vicinity where iron of much renown in Spain was extracted. Remains of more than 20 of these forges are found in the neighborhood of Sierra Menera and are usually situated near waterfalls and forests. Much investigation has been carried on for the purpose of determining the quantity of ore to be found in these mines, but no exact calculations can be made at present. When the investigation is completed it will surely be found that the deposit contains a much larger quantity than the 100,000,000 tons indicated by the present workings.

Jan 2, 1916

By J. F Haseman, J. E. Davenport

In the brown rock phosphate fields of Tennessee there are large deposits of phosphate matrix in which quartz is a major constituent of the gangue, and which cannot be beneficiated by the conventional washing process to yield a concentrate of suitable grade for use in the electric furnace. A huge tonnage of high-grade phosphate concentrate is produced in the Florida pebble district from low-grade siliceous feed. However, the characteristics of the low-grade siliceous Tennessee ore are such that flotation under the conditions employed in treating the Florida ore1,2 results in inadequate beneficiation. Investigation of Flotation Methods Flotation has been used in 'Tennessee primarily to produce a concentrate of premium grade by moderate enrichment of a marketable grade of phosphate. 3,4 A secondary use was to increase the recovery of phosphate from the fines (down to approximately 200 mesh) from medium-grade ores with a concomitant moderate increase in over all grade.3,5 It was considered desirable to investigate methods of improving the grade of washed products from low-grade siliceous Tennessee ore when these products were substantially below the requirements for use in the electric furnace. The present paper describes the results of a laboratory-scale study of factors that affect the beneficiation of such siliceous phosphate ore by flotation. The primary objective of the investigation was to ascertain the conditions under which the ore could be made to yield a concentrate suitable for reduction in the electric furnace. It was assumed that a phosphate concentrate for electrothermal reduction should contain at least 26 pct P2O5 and should have a weight ratio of silica to lime of not more than 0.80. Since a concentrate of moderate grade can be used in the electric furnace, and since, as Grissom4 has shown in detail, the ore will not bear the cost of expensive treatment, the study of collectors was limited to the relatively inexpensive fatty acids. A secondary objective was to determine whether a portion of the phosphate could be recovered in a grade suitable for treatment with phosphoric acid to produce 45 pct superphosphate. The ore consisted of variably cemented sand interlayered with clay. The sand layers were composed of grains of quartz, phosphate, and clay embedded in a matrix of clay and phosphate. Some clay was finely disseminated in the phosphate grains. Little massive high-grade phosphate was present. The material used in the flotation tests was a washed sand that had been separated from the ore in a bowl classifier at the TVA phosphate-washing plant. The percentage composition of the sand was as follows: P2O5, 20; SiO2, 40; CaO, 29; Fe2O3, 2; Al2O3, 3; F, 2.3. The particle-

Jan 1, 1948

By J. F. Haseman, J. E. Davenport

In the brown rock phosphate fields of Tennessee there are large deposits of phosphate matrix in which quartz is a major constituent of the gangue, and which cannot be beneficiated by the conventional washing process to yield a concentrate of suitable grade for use in the electric furnace. A huge tonnage of high-grade phosphate concentrate is produced in the Florida pebble district from low-grade siliceous feed. However, the characteristics of the low-grade siliceous Tennessee ore are such that flotation under the conditions employed in treating the Florida ore1,2 results in inadequate beneficiation. Investigation of Flotation Methods Flotation has been used in 'Tennessee primarily to produce a concentrate of premium grade by moderate enrichment of a marketable grade of phosphate. 3,4 A secondary use was to increase the recovery of phosphate from the fines (down to approximately 200 mesh) from medium-grade ores with a concomitant moderate increase in over all grade.3,5 It was considered desirable to investigate methods of improving the grade of washed products from low-grade siliceous Tennessee ore when these products were substantially below the requirements for use in the electric furnace. The present paper describes the results of a laboratory-scale study of factors that affect the beneficiation of such siliceous phosphate ore by flotation. The primary objective of the investigation was to ascertain the conditions under which the ore could be made to yield a concentrate suitable for reduction in the electric furnace. It was assumed that a phosphate concentrate for electrothermal reduction should contain at least 26 pct P2O5 and should have a weight ratio of silica to lime of not more than 0.80. Since a concentrate of moderate grade can be used in the electric furnace, and since, as Grissom4 has shown in detail, the ore will not bear the cost of expensive treatment, the study of collectors was limited to the relatively inexpensive fatty acids. A secondary objective was to determine whether a portion of the phosphate could be recovered in a grade suitable for treatment with phosphoric acid to produce 45 pct superphosphate. The ore consisted of variably cemented sand interlayered with clay. The sand layers were composed of grains of quartz, phosphate, and clay embedded in a matrix of clay and phosphate. Some clay was finely disseminated in the phosphate grains. Little massive high-grade phosphate was present. The material used in the flotation tests was a washed sand that had been separated from the ore in a bowl classifier at the TVA phosphate-washing plant. The percentage composition of the sand was as follows: P2O5, 20; SiO2, 40; CaO, 29; Fe2O3, 2; Al2O3, 3; F, 2.3. The particle-

Jan 1, 1948

By Robert Mehl

PART I. ORIENTATION RELATIONSHIPS IN OXIDE LAYERS Oriented overgrowths and intergrowths among both metallic and nonmetallic substances have been recognized and studied for well over a century. The work of Widmanstätten in 1808 on the geometrical struc-ture in meteorites, a structure known by his name, demonstrated that oriented intergrowths can occur in purely metallic systems. This fact led to much of the early microscopic study of alloys, contributing greatly to the advance of physical metallurgy. The problem has been attacked again in recent years in a comprehensive fashion, with the object of dis-covering what atomic movements may occur during phase changes in alloy systems. Much of this work has appeared in the A.I.M.E. TRANS-ACTIONS in a series of papers published by Mehl and coworkers beginning in 19311. Although many aspects of this general problem remain unsolved, it may be said that the orientation of a new phase forming by precipitation from solid solution or by transformation invariably bears, a unique relationship to the orientation of the phase from which it formed, and that similarity in atomic patterns on atomic planes in the two phases play an important part in determining the orientation relationship. Analogous orientation relationships exist in oriented intergrowths in nonmetallic systems-mineral or inorganic. In 1827 Haidinger2 dis-covered natural intergrowths of hematite and magnetite, and demon-strated that the rough form of the magnetite octahedrons was delineated by small crystals of hematite, of which the basal (00.1) planes lay parallel to the octahedral cleavage planes of the magnetite. The description of this orientation relationship was later completed by von Rath3, who showed that the edge (00-1):(10-1) in hematite lies normal to the [111]

Jan 1, 1937

By Roy W. Moore

The Tom Reed Extension and Big Jim mines of United Eastern Mining Co. are situated in the Oatman district, Mohave County, Ariz., about 28 miles southwest of Kingman, the nearest railway point. Articles descriptive of the mine surface plant, mill construction, and plant operations have been written by Otto Wartenweiler,' the designing engineer; Wheeler 0. North12 when he was assistant general manager for the company, and Earle M. Bagley, mill superintendent.3 The last article covers average costs for the full time the mill was operated. The geology of the mines is described by F. L. Ransome 4 of the United States Geological Survey. Production was started in January, 1917, and the known orebodies were exhausted in May, 1925, showing a life of seven years and five months. On account of the comparatively short life and the fact that stoping operations were confined to two orebodies, little experimenting was done with mining methods. The two orebodies were in what is generally called the Tom Reed-United Eastern vein, which occupies a fault fissure having a normal displacement of several hundred feet. Seven or eight very productive ore shoots were mined along this vein in a distance of 1 1/2 miles, the two worked by the United Eastern being 1 mile apart. The maximum dimensions of the Tom Reed Extension ore shoot were: height, 750 ft.; length, 950 ft.; thickness, 48 ft. The vein structure varied from a solid quartz-calcite filling to a series of parallel stringers separated by andesite. From this body, 511,976 tons of ore were mined. (Fig. 1.) The maximum dimensions of the Big Jim orebody were: height, 450 ft.; length, 850 ft., thickness, 35 ft. Its structure was similar to that of the Tom Reed Extension but larger sections of the vein were made up

Jan 1, 1928

By G. E. Tardiff, A. A. Hendrickson

THE objectives of this communication are to present the solid-solution strengthening data for silver-base zinc single crystals and to evaluate the importance of strength contributions from several mechanisms through the use of this data combined with that for the silver-base aluminum case.' Some features of the yield point behavior of silver-base zinc crystals were previously reported.' Silver-base zinc alloys were prepared by induction melting 99.99 pct Ag with 99.9 pct Zn in high-purity graphite crucibles contained in argon-filled quartz tubes. After the first melting, the ingots were cut into short lengths, redistributed in the molds, and remelted in order to reduce solute-concentration variations. Alloy single crystals were then grown from the melt through the use of a modified Bridgeman technique which consisted of lowering the graphite crystal mold through a hot zone at a rate of 3/8 in. per hr. As in the melting operation, the molds were contained in argon-filled quartz tubes. Gage lengths 2 cm in length were introduced by both spark machining (circular cross sections) and abrading and acid etching (rectangular cross section) followed by electropolishing (a comparison of the critical resolved shear-stress values prepared by the two techniques showed no differences in strength values). The final cross-sectional areas of the crystals were approximately 5 sq mm. Prior to testing, the crystals were annealed at 600°C for 20 hr in argon atmospheres, furnace-cooled, and lightly electropolished. Crystal orientations were determined using the back-reflection method. The tensile testing was done on a Model FM Instron at a strain rate of 1(T4 per sec. Test temperatures of 77", 200°, and 400°K were attained by immersing the specimens in liquid nitrogen, dry ice-acetone mixtures, and silicone oil, respectively. The critical resolved shear-stress (CRSS) values for silver-base zinc crystals as a function of composition and testing temperature are given in Fig. 1. It will be noted that the CRSS for silver-base zinc solid solutions, as in the silver-base aluminum1 case, depends on temperature in a manner typical of fcc solid solutions: at high temperatures (-300°K and above), the CRSS is relatively temperature-independent but becomes strongly dependent on temperature at lower testing temperatures. A reasonable picture of solid-solution strengthening for silver-rich solutions at room temperature based on "direct" strengthening mechanisms3 is as follows. Since silver alloys have low stacking-fault energies, extended dislocations are expected and it is possible that Suzuki locking4 makes the major contribution to the room-temperature solute strengthening. This provides essentially temperature-independent strengthening since thermal motions of the dislocation line are not large enough to aid the dislocation in escaping the solute atmosphere extending over the fault width. An estimate of the

Jan 1, 1964

E. M. Fitchett (Johnstown, Pa.)—The fact stated by the authors that: "In the laboratory, without marked efficiency decreases, the authors have deposited zinc successfully from solutions containing as high as 1 g per liter of germanium," (p. 465, paragraph 3) is most unusual. A similar statement is made in the summary and conclusions: "Germanium alone, within normal operating limits does not cause large efficiency losses." The limits are not defined. These facts are directly contrary to much of the published history on the effect of germanium in zinc electrolysis. A description of the conditions leading to such a successful electrolysis would be of interest to all engaged in the production of electrolytic zinc. It is unfortunate that the authors of this paper did not determine the actual concentration of germanium and cadmium in the solutions which they electrolyzed after a zinc dust purification. This purification will take out a variable amount of these impurities, depending upon the composition of the dust, type of agitation, presence of activating agents, etc. Probably every electrolytic zinc plant in this country has accurate methods, both wet and spectrographic, for determining germanium and cadmium. These specific methods, adopted from the standard analytical literature, are often available to educational institutions for the asking. The headings of Fig. 2 and of the two tables, with their definite concentrations of germanium and cadmium (which are not so definite according to the footnotes) could possibly be somewhat misleading, since the actual amounts of germanium and cadmium present during electrolysis are not known. Even the 1 hr electrolysis time might be too short for a study of this type; 12 or 24 hr tests might be much better. Commercial solutions have been known that gave over 90 pct ampere efficiency during the first hour of electrolysis, but no metal at all after 24 hr.

Jan 1, 1953

By Wilder D. Bancroft

It is eight years since I have been connected actively with metallography, but in this time I have been learning something about colloid chemistry, which may be considered as the chemistry of bubbles, drops, grains, filaments, and films, all things in which at least one dimension is very small or in which the surface is large relatively to the mass. Films, of course, suggest to the metallographist Beilby's amorphous film theory, about which I am going to speak for a while, though probably not in the way you expect. I come to bury Beilby, not to praise him. So far as I can judge from looking over the literature hastily, there are two schools in the United States, those who accept Beilby's theory willingly and those who accept it unwillingly. Hoytl says that: At present there seem to be two schools in metallography, one which has adopted the amorphous-phase theory for the explanation of the effect of cold work, mechanical deformation, etc., and one which is not ready at present to adopt this theory. It seems to me that this theory can at least be used as a convenient means of explaining various facts that are demonstrable in the laboratory but the presence of this amorphous material, through our lack of experimental means, we are unable to prove. That we have failed in this direction should not necessarily hinder us from using a theory as workable as this. Mathewson2 says: I have come reluctantly to believe in the amorphous theory, or some theory admitting a modification of the ordinary crystalline phase so as to permit differential properties with temperature, etc. If Mathewson represents one extreme, with Hoyt perhaps occupying a middle ground, H. M. Howe3 may be cited as one of the enthusiastic supporters of Beilby's amorphous theory. It is, says Howe:

Jan 1, 1923

By Wilder D. Bancroft

It is eight years since I have been connected actively with metallography, but in this time I have been learning something about colloid chemistry, which may be considered as the chemistry of bubbles, drops, grains, filaments, and films, all things in which at least one dimension is very small or in which the surface is large relatively to the mass. Films, of course, suggest to the metallographist Beilby's amorphous film theory, about which I am going to speak for a while, though probably not in the way you expect. I come to bury Beilby, not to praise him. So far as I can judge from looking over the literature hastily, there are two schools in the United States, those who accept Beilby's theory willingly and those who accept it unwillingly. Hoytl says that: At present there seem to be two schools in metallography, one which has adopted the amorphous-phase theory for the explanation of the effect of cold work, mechanical deformation, etc., and one which is not ready at present to adopt this theory. It seems to me that this theory can at least be used as a convenient means of explaining various facts that are demonstrable in the laboratory but the presence of this amorphous material, through our lack of experimental means, we are unable to prove. That we have failed in this direction should not necessarily hinder us from using a theory as workable as this. Mathewson2 says: I have come reluctantly to believe in the amorphous theory, or some theory admitting a modification of the ordinary crystalline phase so as to permit differential properties with temperature, etc. If Mathewson represents one extreme, with Hoyt perhaps occupying a middle ground, H. M. Howe3 may be cited as one of the enthusiastic supporters of Beilby's amorphous theory. It is, says Howe:

Jan 1, 1923

By Sweetser, Ralph A

AT the fall meeting of the Iron and Steel Division, Oct. 4, 1934, in New York, a symposium was held on Slag Control in the Making of Iron and Steel. The chairman was J. H. Nead and the vice chairman, G. B. Waterhouse. The latter presided at both morning and afternoon sessions. The papers and discussions were presented in the order in which they appear on the following pages. To meet space requirements, much of this material has been considerably condensed. CONTENTS Slag Control and the Blast Furnace. By Ralph H. Sweetser. (With dis¬ cussion.) I Slag Control in Rimming Steel. By L. F. Reinartz 5 Slag Control Applied to Low-carbon Steel. By Frank G. Norris 9 Discussion on both papers 11 Slag Control for Basic Open-hearth High-carbon Steel. By W. J. Reagan. (With discussion.) 14 Slag Control for Recarburized Rail Steel. By A. P. Miller and T. S. Washburn. (With discussion.) 18 Slag Control for Alloy Forging Steel. By A. L. Feild. (With discussion.). . . 24 Slag Control for Alloy Forging Steel. By R. C. Good 27 Slag Control in Acid Open-hearth Steel. By Francis B. Foley. (With dis¬cussion.) 29 Slag Control for Basic Electric-furnace Steel. By H. F. Walther. (With discussion.) 31 Physical Testing of Slag. By A. B. Kinzel. . 40 General Discussion 41

Jan 1, 1935

By N. W. Sager, H. W. Mossman

The arrangement and general dimensions of the reverberatory furnaces and waste-heat boilers for the Nos. 2 and 3 smelting units at the McGill plant of the Nevada Consolidated Copper Corporation are shown in Fig. 1. Each of the two reverberatory furnaces has its own set of waste-heat boilers, and before February, 1932, each furnace, when it was in operation, delivered waste-heat gases to its own boilers only. In January, 1933, the idea was suggested of using some of the waste-heat boilers as economizers to operate in conjunction with the waste-heat boilers that were generating steam. The execution of this idea gave rise to the gas-flow scheme depicted in Fig. 1, the advantages of which were obvious, particularly so in view of the fact that for some months prior to the adoption of this scheme the smelting had been confined to No. 2 furnace, with No. 3 furnace and its boilers idle. The waste-heat gases from No. 2 furnace pass through the boilers serving this furnace as steam-generating units, thence through the original exit duct to a point where a bulkhead diverts the gases in a reverse direction through two of the boilers of No. 3 furnace. After the gases have traversed these two boilers, another bulkhead placed in the duct between No. 3 furnace and its boilers causes them to traverse still one more boiler, from which the gas path leads to the stack. In this scheme the last three boilers traversed by the gases, i.e., the boilers behind No. 3 furnace, function as economizers and preheat the feed water for the two steam-generating units directly serving No. 2 furnace. This discussion will give consideration to the results obtained in waste-heat recovery by the scheme shown in Fig. 1, and, further, will compare these results with those obtained before the boilers of No. 3 furnace were set up to act as economizers, but before going into the detail of heat generation, distribution and recovery, will present some additional details of the equipment. All boilers in this waste-heat plant are of the Stirling type. The two behind No. 2 furnace, acting as steam-generating units, of class 13, are 40 tubes wide and rated at 1112 boiler hp., while the three boilers behind No. 3 furnace, acting as economizers, are also of class 13, but 28 tubes

Jan 1, 1934

By Donald A. Dahlstrom

In 1961 it became increasingly more evident that significant technological changes must be made in minerals beneficiation. The status quo in technology in today's competitive markets will not be tolerated. Higher productivity, greater recoveries and newer and better products must be sought and incorporated with lower operating costs. In other words, "when you build a new mill, don't build an old mill." Recommended reading for proof of the vital necessity of new methods and techniques is in the September 1961 issue of MINING ENGINEERING. The article by one of MBD's cherished and true veterans, E. H. Rose, is entitled "Iron Ore: The BIG Picture". Because of new beneficiation methods for iron ores, nearly 47 million tons of plus 60% iron concentrates will be produced and another 40.1 million tons of capacity will be under construction or committed. Thus in a relatively short period, 87 million tons of this high-grade iron concentrate with record low silica will be available. As Mr. Rose also points out, "in gross tons, without allowance for better grade, this is the equivalent of almost exactly two-thirds of all iron ore used for all purposes in the U.S. and Canada in the peak years of 1953 or 1957." Needless to say, improved mineral beneficiation methods have had far more reaching effects than just the production of higher grade iron concentrate.

Jan 2, 1962

By Alexandre Pourcel

The phenomena of liquation in steel or iron ingots of all sizes, but naturally to greatest extent in the heaviest ingots, have been noticed ever since the commencement on a large scale of the Besse mer and open-hearth manufactures; but they have been studied with care during the last few years only. The English and the Ameri cans were the first to publish the results of investigation upon phe nomena of this clam, to which they have given the name of segregation. Historical. Passing by that which has been written concerning the segregation observed in gray pig-iron, of which instances were given by Karsten, we shall confine ourselves here to that which is known of this subject with exclusive reference to ingot steel and iron. Mr. H. M. Howe, of Boston, in his Metallurgy of Steel, the most complete and well-arranged treatise upon steel, gives a resume of observations, with the results of numerous analyses, bearing upon the phenomena of segregation. According to Tchernoff (with whom we discussed this question at length in 1878, in connection with the cast-steel plates of large dimensions designed for the Italian fleet, which we showed him at Terre-Noire), Kalakoutsky called attention in 1866 to the lack of homogeneity in Bessemer ingots, especially when cast in sand. Our own attention had been called to the phenomena of liquation in 1868 by a somewhat surprising fact which appeared in almost every one of a number of steel-rail ingots coming from the works of Messrs. Pierre and Emile Martin at Sireuil, to be rolled at TerreNoire. In the heating or in the first groove of the rolls, a slice of from 6 to 10 centimeters (2.4 to 3.9 inches) separated itself from the head of each ingot. As a general consequence, the section of

Jan 1, 1894

By Robert C. Mackenzie

EXAMINATION by the differential thermal analysis technique of a large number of samples of soil and other clays from various parts of the world has demonstrated that the occurrence of cold-precipitated hydrated ferric oxide (the identification of which in soil clays has previously been reported5) is not confined to any limited locality; e.g., it has been found in varying amounts in clays from Britain, France, South Africa, and Mexico. The conditions necessary for its formation have not yet been elucidated in spite of the number of samples examined, and, since this mineral is so easily prepared in the laboratory, it has been considered that a study of its constitu¬tion and of the conditions under which it could be prepared might. lead to a better understanding of the factors involved. These experiments form the subject of this short paper, and while they do not supply a definite answer to the mode of formation of this mineral in nature, they may, it is hoped, add something to our knowledge in this direction. EXPERIMENTAL WORK Materials Employed The a-Fe2O3.H2O (goethite) and B-Fe2O3.H2O (Weiser and Milligan") were obtained from the Department of Geology, University of Aberdeen, and Rothamsted Experimental Station, respectively. The beta material had been prepared by the method described by Fernelius.1 y-Fe2O3.H2O (lepidocrocite) was prepared at the Macaulay Institute for Soil Research by the method of van Schuylenborgh.6 The method employed for preparation of the cold-precipitated hydrated ferric oxide* was as follows: 1: 1 NH4OH was added (moderately fast with rapid stirring) to a solution of 5 grams FeC13.6H2O in 250 ml distilled water at room temperature (ca. 15°C) until red litmus turned blue, and then 2 to 3 drops in excess. The resultant precipitate was filtered off on a Buchner funnel and washed free from Cl- with distilled water. Previous experiments having shown that drying over P2O5 at room temperature or drying at 105°C in the oven did not significantly affect the thermogram,5 samples were nor-

Jan 1, 1952

By E. L. Tucker

IN THE metallurgy of precious metals, it has been standard practice for years to use cyanogen compounds, so it was but natural that early investigators in the field of flotation should consider these compounds as possible flotation reagents. In Australian Patent 9508, of 1913, alkali cyanides were described as suitable reagents for the separation of heavy sulfide minerals, the reagents being employed either in an alka-line or neutral circuit. In U. S. Patent 1236501, of 1917, to John M. Tibbet, the use of cyanide in conjunction with soda ash or lime is described. One of the claims of this patent reads, "An improvement in the cyanide process for the treatment of ores comprising, mixing the ore with cyanide solution and oil and alkali: emulsifying the oil in the presence of the ore, the alkali and the cyanide solution, floating a portion of the values in the pulp by producing gas bubbles in the mixture-and removing the values floated." More recently, Sheridan and Griswold, in U. S. Patents 1421585 and 1427235, describe a somewhat similar process and have, successfully introduced it in. the mill of the Timber Butte Milling Co. U. S. Patent 1429544, of 1922, to Stevens, describes the use of double cyanides of copper, zinc, and lead. The success of cyanide as a reagent in the differential flotation of lead and zinc sulfides in highly complex ores is proof that these patents have a solid foundation.. Although the technique of their application to particular ores has been worked out in many cases, no one, so far as is known, has attempted to describe the nature of the action of the cyanide or to determine the ideal conditions for its, application. It was the purpose of the present investigation to gather information on these points. Naturally this would have been an exceedingly ambitious.

Jan 8, 1925

By J. T. Mackenzie

Henry Marion Howe, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius. Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: " Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up—by masses of graphite ..." Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in I900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on "The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro-structure of the metallic matrix, Professor Howe pointed out that "such minor structural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

By J. T. Mackenzie

Henry Marion Howe, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius. Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: " Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up—by masses of graphite ..." Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in I900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on "The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro-structure of the metallic matrix, Professor Howe pointed out that "such minor structural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

By J. D. Verhoeven

The effectiue distriblltion coefficient has been Measured in a series of vertical, normal freezing experirtzents with large current densities passing through the solid-liquid interface. The results indicate that the effect of the current on solute redistribution is due to electvotransport in the liquid. The high currents produced extensive mixing in the liquid which was considerably reduced by solidifying in small lubing. Analysis of the convection indicates that it probably vesulls from a horizontal temperature gradient produced by the Joule heating- of the electvic crirver~t. Due to the strong dependence of this convection upon the specimen radius, it is conclnded that only for specit~ens with radii of less than somewhere between 1 and 2 mm wilt electric field freezing be getlerally effec-tire at enhancing the purification of zone-melting experittierats in loe-melting alloys. Experiments on 0.8-mm lubes illustrate some interesting potential applications of this techniqne as a means of solute control on smcrll specimens. In a number of papers published within the last few years'-4 it has been found that passage of large dc currents through the solid-liquid interface of a freezing alloy produces a change in the solute redistribution accompanying the solidification. It had been predicted theoretically by Hucke et al.s and by Pfann and Wagner that such an effect would occur as the result of electrotransport within the liquid boundary layer at the solid-liquid interface. These authors independently derived the following relation between the effective distribution coefficient and the variables of the process: Where k0 is the equilibrium distribution coefficient, V is the mobility of the solute relative to the solvent, E is the electric field intensity, D is the solute diffusion coefficient, R is the rate of interface motion, and 6 is the boundary layer thickness. Both groups of authors show that this equation predicts the possibility of extending the purification ability of zone-melting experiments by the addition of an electric current. However, there are other effects in addition to electro-transport which could be produced by the high dc current and might, perhaps, invalidate the applicability of Eq. [I]. For example, high electric current might affect the interface reaction or perhaps the equilibrium distribution which was assumed to exist at the interface. It was the purpose of this work to determine the applicability of Eq. [I] by systematically investigating a simple system for which all of the necessary parameters were known. It was of particular interest for speculating on the potential usefulness of this technique to determine the maximum practical field intensities obtainable, and the effect of these high fields upon convective mixing in the liquid. The initial work in this study was published in a previous paper3 which will be referred to as I. In that work, a current density of 2000 amps per sq cm was used with specimen diameters of 5 mm. The results gave a qualitative confirmation of Eq. [I.], and also showed that a large amount of convective mixing was produced in the liquid by the current. The present study is an extension of that work to smaller specimen diameters and higher current densities. Two points were overlooked in I and will be emphasized here: a) the value of ko has not been well-established in the Sn-Bi system and b) the observed convection could be due to thermal convection produced from the Joule heating. EVALUATION OF k0 To evaluate Eq. [ I.] it is necessary to know the value of the equilibrium distribution coefficient, k,. Tn I the value of k, was taken as 0.3 from a published phase diagram.7 According to ansen' the best data on the phase boundaries of the Sn-Bi system are those of Davidson.5 The data of Davidson give a k, value ranging from 0.21 to 0.25 for the compositions studied in this work, or an average value of around 0.23. In a recent publication, Rigaud and Tougas'10 determined ko by means of a solidification technique. For an alloy of approximately the same composition as that used in this work they obtained a ko value of 0.39. Hence, there is considerable uncertainty in the value of ko and, consequently, a series of experiments were made to determine k, more accurately.

Jan 1, 1968