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By D. S. Hutton, W. C. Leslie

Thermal etch patterns developed on poly crystalline 3.5 pct Si-Fe by heating in hydrogen or in argon have been examined. The most prominent feature of the etching is the development of striations on grains with (100) planes near the plane of the surface. These striations are probably produced by the resoution of a random, high-energy plane into (100) facets of lower energy. THE thermal etching of iron and iron-base alloys has a long history. The phenomenon was observed by Osmondl more than 70 years ago. The literature on thermal etching between that time and 1951 was reviewed by Olney,2 and a briefer review appeared in 1958. 3 The only articles which have been found dealing with the thermal etching of silicon iron are those of Dunn and Lionetti4 and of Dunn, Daniels, and Bolton,5 and they reported only grain boundary etching. EXPERIMENTAL PROCEDURES A cast 3.5 pet Si-Fe alloy was given a metallo-graphic polish and etch, then placed in flowing purified hydrogen for 6 hr at 2200°F. The same specimen was later repolished and etched to remove the thermal etching. The specimen was then held in flowing purified argon at 2200°F for 72 hr. In both instances the specimen was rapidly cooled by being pulled up quickly into the cold zone of the furnace. All photomicrographs shown are of the surface as removed from the furnace. Oblique illumination was essential for observation of the thermal-etching effects with a light microscope and was used for all the photomicrographs. RESULTS AND DISCUSSION Grain boundary etching, grain boundary movement, and contouring within grains are illustrated in Fig. 1. The contours within a single grain followed behind the advancing grain boundary. To determine the average contour interval, or step height, white light was used in an interference microscope. The steps were of the correct magnitude to separate while light into its spectrum of colors. A green light was focused at the top of a contoured area, shifting to red across the field. By using the difference in the dominant wave length of red and green light,6 and counting the number of steps across the area, it was possible to obtain a value of about 80A for the average step height. Laue back-reflection patterns of four grains with contour lines showed that the grains had a (100) plane slightly inclined to the plane of the surface (± 5 deg). Insofar as this could be determined from their irregular traces, the contour lines within a grain had a common direction, <100> ± 5 deg.

Jan 1, 1961

By John L. Lamont, Walter Crafts

AN investigation has been made of the multiplying factors for some of the more common alloying and deoxidizing elements for use in calculating hardenability of steel according to Grossmann&apos;s method.1 The factors for manganese, silicon, and aluminum that were reported in an earlier communication2 have been confirmed by microscopic determination of the half-martensite structure rather than on the basis of an empirically determined hardness corresponding to a half-martensite structure. Measurement of ideal critical diameter by microscopic examination was found to he necessary for other alloying elements, and multiplying factors for nickel, chromium, molybdenum, zirconium, vanadium, titanium, and boron have been determined. The nature and order of magnitude of the multiplying factors reflect the effect of the alloying elements on the structural character of the steel. Except for nickel and vanadium, the multiplying factors agree fairly well with previously published results. Good correlation between actual and calculated ideal critical diameters has been found in developing the multiplying factors and in checking the results against fairly simple steels. However, some discrepancies have suggested the need for a more thorough study of low-carbon and complex steels. TESTING PROCEDURE The investigation was conducted principally on steels made at the Union Carbide and Carbon Research Laboratories, Inc., in high-frequency induction furnaces using Armco iron and standard alloying materials. However, a few open-hearth steels were used in establishing the effect of nickel, and the hardenability factor for boron was based primarily on open-hearth steels. All bars were normalized prior to the machining of Jominy hardenability specimens. The Jominy test was carried out under conditions standard for the test.3 Austenitizing temperatures judged to-be-appropriate for the composi¬tions of the steels were used., Chemical analysis was determined on a sample taken adjacent to the Jominy specimen. Residual amounts of phosphorus, sulphur, nickel, chromium, molybdenum, and copper were determined on only one heat of each group made with the same materials during the same period. "Acid-soluble" aluminum and zirconium rather than total amounts were determined, as it is considered probable that the acid-soluble amount is more representative of the effective alloy. As tin was present to the extent of only 0.002 per cent, its effect was neglected. The method used to determine boron in the steels shown in Table 9* was developed by Galen Porter, Vincent Napoleon, and Thomas R. Cunningham,of the Union Carbide and Carbon Research Laboratories, Inc., and is. a modification of J. Naftel&apos;s procedure for boron in soils

Jan 1, 1944

By Walter Crafts, John L. Lamont

An investigation has been made of the multiplying factors for some of the more common alloying and deoxidizing elements for use in calculating hardenability of steel according to Grossmann&apos;s method. The factors for manganese, silicon, and aluminum that were reported in an earlier communication2 have been confirmed by microscopic determination of the half-martensite structure rather than on the basis of an empirically determined hardness corresponding to a half-martensite structure. Measurement of ideal critical diameter by microscopic examination was found to be necessary for other alloying elements, and multiplying factors for nickel, chromium, molybdenum, zirconium, vanadium, titanium, and boron have been determined. The nature and order of magnitude of the multiplying factors reflect the effect of the alloying elements on the structural character of the steel. Except for nickel and vanadium, the multiplying factors agree fairly well with previously published results. Good correlation between actual and calculated ideal critical diameters has been found in developing the multiplying factors and in checking the results against fairly simple steels. However, some discrepancies have suggested the need for a more thorough study of low-carbon and complex steels. Testing Procedure The investigation was conducted principally on steels made at the Union Car- bide and Carbon Research Laboratories, Inc., in high-frequency induction furnaces using Armco iron and standard alloying materials. However, a few open-hearth steels were used in establishing the effect of nickel, and the hardenability factor for boron was based primarily on open-hearth steels. All bars were normalized prior to the machining of Jominy hardenability specimens. The Jominy test was carried out under conditions standard for the test.3 Austenitizing temperatures judged to be appropriate for the compositions of the steels were used. Chemical analysis was determined on a sample taken adjacent to the Jominy specimen. Residual amounts of phosphorus, sulphur, nickel, chromium, molybdenum, and copper were determined on only one heat of each group made with the same materials during the same period. "Acid-soluble" aluminum and zirconium rather than total amounts were determined, as it is considered probable that the acid-soluble amount is more representative of the effective alloy. As tin was present to the extent of only 0.002 per cent, its effect was neglected. The method used to determine boron in the steels shown in Table 9* was developed by Galen Porter, Vincent Napoleon, and Thomas R. Cunningham, of the Union Carbide and Carbon Research Laboratories, Inc., and is a modification of J. Naftel&apos;s procedure for boron in soils

Jan 1, 1944

By Helmut Thielsch

During the last three decades a great many arguments have been presented on the subject of "mosaicJ&apos; or "blockJJ structures of metals. Apparently because of insufficient evidence, the "block-structure" theories have never been widely understood among the physical metallurgists in this country, and most investigators among the few that have tried to demonstrate the existence of such an inner strutture Of crystals or grains have failed to recognize also the existence of a lamellar structure. Moreover, little thought has been given to justify the existence of such "lamellar" or "mosaic-block" structures on a theoretical basis. Since properties such as Plasticity; ferro-magnetism, hardness, diffusion, and others may be explained by structural faults in the lattice network of the crystals: the great importance of a more detailed knowledge of the structure within crystals or grains becomes now evident. Because Of the vast extent of the field Of submicroscopic structures, it shall be the purpose Of this paper only to review the more important of the results obtained by other investigators, especially in Germany, where a great deal of attention has been given to mosaic structure during the last three years. The origin of this mosaic patternt and effects of cold reduction and recrystallization will be shown in further studies later on. Imperfections in Crystals The many terms used in the literature to denote structural types of crystals are often not clearly defined. To clear up some of the confusion, the meaning of the more important terms will be given here. ideal, or perfect without any structural imperfections are called "ideal crystals,,or &apos;&apos;Perfect&apos;&apos; crystals,n meaning a Homogeneous interior structure of atoms, ions or molecules, as the case may be. In other words, at every point in the interior of the crystal exactly the same orientation of the crystallographic axes of the coordinate system would exist. The Surface of such a body, if etched with an appropriate etching reagent, would reflect light with perfect uniformity. Crystals of this type are almost nonexistent. Real Crystals.—L&apos;Real crystals"&apos; may contain various types of structural defects, which can be classified into: (I) lineage structure, (2) mosaic-block structure, (3) lamellar structure. The inhomogeneities many,in these groups mean that the orientation of the crystallographic aies will not be the same at every point within the interior of a crystal (or grain of a poly crystalline body). &apos;Perjecl Real Crystals.—The term "perfect real crystals " is generally used to describe crystals with minute structural or thermo-dynamical inhomogeneities. The former

Jan 1, 1946

Rossiter Worthington Raymond, Ph.D., LL. D-1840 to 1918.-Dr. Rossiter W. Raymond, Past President, Honorary Member and Secretary Emeritus, died suddenly of heart failure at his home, 123 Henry&apos;St., Brooklyn, N. Y., on the evening of Tuesday, Dec. 31, 1918. He was one of the founders of the Institute and its second President. A Memorial &apos;Service will be held on Monday afternoon, Feb. 17. James Douglas.- The Institute suffered a second very severe loss by the death of Dr. James Douglas, Honorary Member, Past President (having served as President for two years), and in three separate respects the greatest benefactor of the Institute: first, in raising funds by volun¬tary subscription and his own personal gifts to pay the Institute&apos;s share of the money owed on the land on which the Engineering Societies Build¬ing now stands; second, as original donor to Engineering Societies Library; and third, by his bequest of $100,000 for the maintenance of the library of the American Institute of Mining Engineers. A resolution regarding the death of Dr. Douglas was passed by the Board of Directors and at the meeting of the Institute on Sept. 4, 1918, in Colorado, at which time a memorial service was held in the thea¬ter of the Hotel Broadmoor, attended by about 400 members and guests. A copy of the resolution was prepared and sent to the family. A bronze tablet is now being prepared and will be placed in the Members&apos; Room and unveiled at the February meeting. A biography and portrait of Dr. Douglas was published in the September, 1918, Bulletin. There is also placed in the Engineering Societies Library an oil portrait of Dr. Douglas which had his own approval and was presented by him. American Institute of Metals.--During the Spring of the year, plans were completed with the American Institute of Metals whereby this society became the Institute of Metals Division of the American Insti¬tute of Mining Engineers. This body was a dignified aggregation of metallurgists which had been in existence for about 11 years. A bronze tablet commemorating the American Institute of Metals is now being placed in the Members&apos; Room of the Institute, and during the year 1919 the Bulletin will bear the following title: "Bulletin of the American Institute of Mining Engineers, with which is consolidated the American Institute of Metals." Visits to Local Sections.-During the year President Jennings made visits to six of the Local Sections, on three of which occasions he was accompanied by the First Vice-president and the Secretary. First Vice-president Goodale made five visitations and the Secretary made eight.

Jan 1, 1923

By R. J. Allio, C. H. Randall

An automatic system for the quantitative analysis of microstrulcture has been developed. The method is based upon a statistical model of microstructure and employs phase intercept fractions as fundamental random variables. Structure-sensitive properties can be related explicitly to parameters derived from the distribution of phase intercept fractions in a matevial. THE properties of mechanical dispersions and of multiphase alloys art: intimately related to the amount, distribution, and intrinsic properties of the dispersed material. In many instances, the amount and distribution of the dispersed substances have greater influence on the over-all system properties than do the properties of the dispersed substance-Such properties as average particle size, particle size distribution, homogeneity of dispersion, volume per cent of dispersed phase, and mean free path between dispersed particles thus become critical in any evaluation of the properties of a dispersion. Unfortunately, techniques for evaluating quantitatively the microstructural characteristics of dis~ersions rapidly and accurately have not been available. If necessary, qualitative or semiquantitative devices can be utilized. Some such devices are based merely upon comparison of the specimens in question with arbitrary standards. Other techniques involve superposition of grids and tabulation of particles observed in different portions of the grid. Still other methods based upon lineal analysis entail counting lines or points at random upon the specimen to be examined; the number of intersections of the line with a given phase, the proportion of line or number of points which are covered by given phase are variously recorded. The mathematical basis for most of the techniques of quantitative metallography have been amply reviewed in the literature.&apos;l2 without exctption, however, the standard techniques for quantitative metallography are either imprecise or are exceedingly tedious to apply. For example, tranverse integrating stage for rapid manual areal fraction measurement has been designed by Smith.3 Howerer, as in the case of any device based upon visual eslimation, operator bias may cause appreciable error. Various flying spot devices, on the other hand register particle size distributions in 2-dimensions, from which it is difficult to derive other properties of the dispersion. Thus, e.g., the 3-dimensional distribution cannot be inferred unless certain rather broad assumptions are made concerning the randomness of distribution and geometrical configuration of dispersed phase. Many limitations to the application of quantitative structural analysis can be overcome by the use of the microdensitometer, which is essentially an automated areal analysis device. Data obtained in the form of a distribution of phase intercept values are

Jan 1, 1962

By John L. Lamont, Walter Crafts

An investigation has been made of the multiplying factors for some of the more common alloying and deoxidizing elements for use in calculating hardenability of steel according to Grossmann&apos;s method. The factors for manganese, silicon, and aluminum that were reported in an earlier communication2 have been confirmed by microscopic determination of the half-martensite structure rather than on the basis of an empirically determined hardness corresponding to a half-martensite structure. Measurement of ideal critical diameter by microscopic examination was found to be necessary for other alloying elements, and multiplying factors for nickel, chromium, molybdenum, zirconium, vanadium, titanium, and boron have been determined. The nature and order of magnitude of the multiplying factors reflect the effect of the alloying elements on the structural character of the steel. Except for nickel and vanadium, the multiplying factors agree fairly well with previously published results. Good correlation between actual and calculated ideal critical diameters has been found in developing the multiplying factors and in checking the results against fairly simple steels. However, some discrepancies have suggested the need for a more thorough study of low-carbon and complex steels. Testing Procedure The investigation was conducted principally on steels made at the Union Car- bide and Carbon Research Laboratories, Inc., in high-frequency induction furnaces using Armco iron and standard alloying materials. However, a few open-hearth steels were used in establishing the effect of nickel, and the hardenability factor for boron was based primarily on open-hearth steels. All bars were normalized prior to the machining of Jominy hardenability specimens. The Jominy test was carried out under conditions standard for the test.3 Austenitizing temperatures judged to be appropriate for the compositions of the steels were used. Chemical analysis was determined on a sample taken adjacent to the Jominy specimen. Residual amounts of phosphorus, sulphur, nickel, chromium, molybdenum, and copper were determined on only one heat of each group made with the same materials during the same period. "Acid-soluble" aluminum and zirconium rather than total amounts were determined, as it is considered probable that the acid-soluble amount is more representative of the effective alloy. As tin was present to the extent of only 0.002 per cent, its effect was neglected. The method used to determine boron in the steels shown in Table 9* was developed by Galen Porter, Vincent Napoleon, and Thomas R. Cunningham, of the Union Carbide and Carbon Research Laboratories, Inc., and is a modification of J. Naftel&apos;s procedure for boron in soils

Jan 1, 1944

By R. M. Asimow

The magnetization curves for specimezs containing superparmagnetic particles are considered. It is shown that the curves may differ from a Langezlin function because of particle anisotropy, particle interactions , and the presence of a size distribution of particles. The various causes of particle anisotropy are considered, and magnetization curves for specimens with cubic and uniaxial anisotropy are presented. The magnetization curves depend on the In the particle-size below 100A it is quite difficult to obtain quantitative size and shape information on precipitate particles. All of the available techniques have their limitations; however, quantitative applications of superparmagnetism have not been developed as fully as possible due to a lack of analysis of the complete magnetization curve. With such an analysis it appears possible to obtain from a single magnetization curve of a specimen containing randomly oriented SPM (superparamagnetic) particles a quantitative volume distribution and a description of the particle shape.* sign of the anisotropy energy and in the case of a negative uniaxial anisotropy (prolate spheroids) the resulting curves may differ very considerbly from a Langevin function. A graphical technique is developed whereby it is possible to separate out the effects of the size distribution, the particle interaction, and the particle anisotropy. Thus it is possible to obtain quantitative values for both the particle shape and the size distribution. Langevin function2 I/Is = ctnh(HVIs/k T)-k T/HVIS [ 1 ] where I, is the saturation magnetization, V the particle volume, H the applied field, T the particle temperature, k the Boltzmann constant, and I the magnetization in the direction of the applied field. Such behavior is rarely if ever observed in actual systems. One explanation for this is that the SPM particles do possess a significant anisotropy and thus the magnetic energy associated with the particle depends on the direction of magnetization in a more complicated way than for the isotropic particle of Eq. [I]. In general the magnetic energy E of an isolated SPM particle embedded in a nonmagnetic matrix can be expressed as a sum of several contributions: E = Eh + Ed+Es+Ec [2] where Eh is the external field energy, Ed the energy resulting from the particle demagnetizing factor, E, the magnetostriction energy, and E, the crystalline anisotropy energy. In each term we consider only the part dependent on the orientation of the magnetization vector and the particle axes as the shape of the magnetization curve will be determined by these contributions. Following the same procedure used in deriving the Langevin function,

Jan 1, 1965

Joseph Esrey Johnson, Jr., had already achieved rare distinction as an able metallurgist, clear thinker, brilliant author, and wise consulting engineer to bankers and operators; he had achieved the essentials of a great career when dcath cut short his activities on Apr. 4, 1919, in the forty-ninth year of his age. He belonged to a family of iron blast-furnace men and mine managers. His father, Major J. E. Johnson, after serving with distinction in the Army of the North, identified himself with the iron mines and blast furnace at Longdale, Va., with which he was connected during almost his entire business life. It is significant, that, during those troublous times of reconstruction in the South, he enjoyed always the affection and respect of his neighbors and associates alike. From him his son obtained not only a thorough training in blast-furnace practice and iron mining, but great personal courage and force of character. His mother, who survives both her husband and sons, possesses rare intellectuality, humor and a tenderness and human sympathy which those who were privileged to know well J. E. Johnson, Jr., recognized beneath his exterior of aggressiveness and will power. In a recently published analysis of the qualities which characterize the world&apos;s great men, three traits stand out preeminently; viz., independence, courage, and intellectuality. Each of these characteristics J. E. Johnson, Jr., possessed in extraordinary degree. His early education was obtained under a private tutor at Longdale, and this circumstance probably enhanced a natural tendency to independence of character and individuality which, however, under the control of his unusual power of straight thinking and clear analysis never allowed him to go far astray. It has been said of him that if once he set his mind to a problem, however knotty, he scored a bull&apos;s-eye before the subject was dropped. His manner of attacking a subject involved first mastering the details of the available knowledge; then, putting this acquired information to one side, with an untrammeled mind blazing out a path of his own, so clear, so well-defined, and expressed in such simple terms that he illuminated the whole subject without distorting the original data or discussion. His two books, "Blast-furnace Construction in America" and "The Principles, Operation, and Products of the Blast Furnace, "on the iron blast furnace together form the most comprehensive, the most enlightening, and the most useful treatise on the subject ever produced in any language. But his ability did not end with the mastery and elucidation of principles enunciated by his predecessors; his own

Jan 1, 1920

By Helmut Thielsch

During the last three decades a great many arguments have been presented on the subject of "mosaicJ&apos; or "blockJJ structures of metals. Apparently because of insufficient evidence, the "block-structure" theories have never been widely understood among the physical metallurgists in this country, and most investigators among the few that have tried to demonstrate the existence of such an inner strutture Of crystals or grains have failed to recognize also the existence of a lamellar structure. Moreover, little thought has been given to justify the existence of such "lamellar" or "mosaic-block" structures on a theoretical basis. Since properties such as Plasticity; ferro-magnetism, hardness, diffusion, and others may be explained by structural faults in the lattice network of the crystals: the great importance of a more detailed knowledge of the structure within crystals or grains becomes now evident. Because Of the vast extent of the field Of submicroscopic structures, it shall be the purpose Of this paper only to review the more important of the results obtained by other investigators, especially in Germany, where a great deal of attention has been given to mosaic structure during the last three years. The origin of this mosaic patternt and effects of cold reduction and recrystallization will be shown in further studies later on. Imperfections in Crystals The many terms used in the literature to denote structural types of crystals are often not clearly defined. To clear up some of the confusion, the meaning of the more important terms will be given here. ideal, or perfect without any structural imperfections are called "ideal crystals,,or &apos;&apos;Perfect&apos;&apos; crystals,n meaning a Homogeneous interior structure of atoms, ions or molecules, as the case may be. In other words, at every point in the interior of the crystal exactly the same orientation of the crystallographic axes of the coordinate system would exist. The Surface of such a body, if etched with an appropriate etching reagent, would reflect light with perfect uniformity. Crystals of this type are almost nonexistent. Real Crystals.—L&apos;Real crystals"&apos; may contain various types of structural defects, which can be classified into: (I) lineage structure, (2) mosaic-block structure, (3) lamellar structure. The inhomogeneities many,in these groups mean that the orientation of the crystallographic aies will not be the same at every point within the interior of a crystal (or grain of a poly crystalline body). &apos;Perjecl Real Crystals.—The term "perfect real crystals " is generally used to describe crystals with minute structural or thermo-dynamical inhomogeneities. The former

Jan 1, 1946

By R. S. Shoemaker, F. W. McQuiston

RECOVERY METHODS AS RELATED TO PROPERTIES OF SILVER ORES The earliest metallurgical process for treating silver ores was amalgamation with mercury which was in use in the early 1500&apos;s. Closely following was the development of the Patio process for treating ores at Pachuca, Mexico. Silver often occurs as the native metal and in deposits associated with other metals such as gold, copper, lead and zinc. Principal silver minerals include compounds of sulfur, antimony, arsenic, and copper. Silver chloride, and argentiferous galena are also prime sources. Native silver and the chloride characterize the oxide zone of most deposits. Native silver can be concentrated, amalgamated, or cyanided. Silver chloride rapidly dissolves in cyanide without oxygen. Oxidized silver ores containing the higher oxides of manganese are generally refractory to metallurgical treatment. A refractory compound of manganese and silver is formed, probably a manganite , which is insoluble in cyanide solutions. Argentite is the predominant silver mineral. Other important economic minerals are native silver, argentiferous galena, cerargyrite, pyrargyrite and tetrahedrite. Argentite dissolves slowly, the reaction being reversible requires an excess of cyanide. Argentite with disseminated fine grained gold occurring in quartz veins with minor amounts of chalcopyrite and galena may be cyanided directly after grinding, with high silver and gold recoveries. The flowsheet adapted to this type of ore is the Minas de San Luis, Tayoltita cyanide plant, which treats a high grade argentite silver ore containing gold. It is a standard cyanidation circuit but employs long periods of agitation contact for the high silver sulfide content ore. Lead-zinc base metal semi-oxidized- complex ores in pipes and chimneys are replacement deposits in limestone at El Mochito Mine, Honduras. Mineralization comprises galena, cerussite, anglesite, sphalerite, calamine, and smithsonite. The silver content of about 16 ounces occurs as native silver globs, wire and the mineral argentite. After flotation of lead and zinc concentrates, the tailings are cyanided for gold and silver recovery. The great Huelva pyritic copper deposits of Spain carry a little gold and silver. At Cerro Colorado, these metals were concentrated above the chalcocite zone into the so-labeled Mgossanu. This material with a content of 0.08-0.09 oz Au and 1.50 oz Ag per ton is amenable to cyanidation. See Cerro Colorado flowsheet. In southern Hidalgo, about 60 miles north of Mexico City, are the great silver--gold veins of one of the foremost silver mining districts of the world. Real del Monte, Pachuca. The mineralized area consists of flow rocks and intrusives. The oxidized ores carry pyrites with oxides of iron and manganese and other minerals, silver and gold. The first zone contains

Jan 1, 1975

By R. H. B. Jones

This paper reviews pertinent geology of the Biwabik iron formation, Mesabi Range, Minnesota. This iron formation is divisible into four members. Each member is distinctive and contains marker horizons, which are recog nizable throughout all phases of alteration from lean, fresh rock to high-grade iron ore. Some beds have a larger magnetite content than others. During the process of ore genesis, which is essentially an oxidation process, the magnetite content is lowered. Alteration from iron formation to ore includes both oxidation of iron minerals and silica removal by leaching and these distinct processes progress at variable rates for different locations and structures. Magnetic intensities, of each horizon of the iron formation are dependent chiefly upon its preoxidation magnetite content, upon the subsequent degree of oxidation, upon the character of the enclosing rocks, and on the extent of fracturing, folding, or faulting. The results of a number of magnetic surveys are described and are correlated with results of drill-hole and mine exploration and developmerit. The magnetic anomalies obtained are discussed in relation to phases of formation of ore within the iron formation. General Information One hundred years ago a party of surveyors, applying the principles of geophysical prospecting, discovered iron ore in the state of Michigan in the Lake Superior district. This event was officially reported as follows:&apos; On Sept. 19 (1844) while running the east line of Town 47 North, Range 27 West, they observed by means of the solar compass remarkable variations in the direction of the needle, amounting to 87" from the normal. Ascribing this phenomenon to iron ore, they sought and found it in ledges or outcrops at several points. The solar compass referred to was invented by William A. Burt, deputy surveyor in charge of this party.2 It is used for determining the true meridian by an observation on the sun. Eight years later, on July 7, 1852, the first iron &apos;re, consisting of 6 bbl. of Ore, was shipped from Marquette, Michigan. It was another 40 years before the first or> shipment left the Mesabi Range in Minnesota, in October 1892. It totaled 4245 tons. Fifty years later, 90 years after the original shipment, during 1942 the Lake Superior district shipped 93,495,392 gross tons of iron ore. Production came from Minnesota, Michigan, Wisconsin, and Ontario, Canada. Throughout the 90-Year period it was known that magnetic properties of most of the ore bodies, and of the iron formations in which they occur, affected the compass. This phenomenon, later to be made use of to outline areas of ground favorable for exploration, was at first a

Jan 1, 1949

By James A. Crookston, William D. Fitzpatrick

Committee C-8 of the American Society for Testing and Materials defines "Refractories" as "Material, usually nonmetallic, used to withstand high temperature," and it defines the term "Refractoriness" thus, "In refractories the capability of maintaining the desired degree of chemical and physical identity at high temperatures and in the environment and conditions of use." The ability to withstand high temperatures is critical to classifying a material as a "refractory." However, as the foregoing definition of "refractoriness" implies, the refractory material may be subjected to and is expected to resist not only high temperatures but a variety of other destructive forces incident to its use. These include abrasion, impact, thermal shock, chemical attack, and high level loads at high temperatures. The various industrial applications of refractories represent an infinite variety of combinations and degrees of severity of these destructive forces, including high temperatures. Naturally, such a variety of application conditions leads to a need for a wide variety of refractory products to satisfy those conditions. The number of refractory products available is great enough that some form of classification is necessary to a discussion of refractories. Refractories may be classified in several ways, but the most suitable one is based on their general compositions and to lesser degrees on their physical condition and distinctive properties. The primary types of brick include aluminosilicate brick (fire clay and alumina), basic brick (magnesia and chrome ore, alone and in various combinations), silica brick, insulating brick, and special refractories (carbon, Sic, ZrO,, zircon, borides, and nitrides). Brick are, of course, preformed and are usually heat treated at high temperatures before use, but are in some instances unburned and/or chemically bonded, including the relatively new class of tar-bonded magnesia and/or dolomite brick. In addition to preformed refractories, another broad category includes the so-called specialty refractories, which are usually made in the same types as itemized for brick-bonding mortars and high temperature cements, hydraulic setting castables or refractory concrete, plastic firebrick, and ramming mixes. Refractory grains, such as fire clay and high alumina calcines, dead-burned magnesite and periclase, and dead-burned dolomite are also considered refractory products. Brick are also classified on the basis of physical dimensions, as standard sizes and special shapes. The standard sizes are those which are of definite shape and design and are designated as 9 x 4 ½ x 2 ½ in. and 9 x 4 ½ x 3 in. straights and series. All other brick of non- standard sizes are referred to as special shapes. These come about as a result of a particular need for a given furnace or for a particular application.

Jan 1, 1975

By M. K. Geer, H. F. Yancey

Investigations of the fundamental factors involved in the performance of various coal-cleaning processes have constituted a substantial portion of the research 011 coal cleaning conducted by the Bureau of Mines. These detailed studies of the mechanism of separating coal from impurity in various cleaning devices were undertaken to provide the coal industry with information that is helpful in selecting the type of cleaner most suitable for treating a particular coal. Previous reports describing these investigations have dealt with the wet table,1 the pneumatic table,&apos; and the plunger,3 pulsator.4 and Baum types5 of jigs. The present report compares the performance of three commonly used units treating the same coal—a pneumatic jig, also known as the air-flow. cleaner, a pneumatic table, and a Baum-type jig. Object and Plan The fact that pneumatic coal-cleaning processes are less efficient than wet-washing methods because they are unable to make as sharp a separation between coal and impurity is well recogilized. The literature, however, contains little quantitative in- formation on the relative performances of the two types of cleaners. The object of the present report is to present a detailed comparison of the performances of two pneumatic units and one wet-washing process treating coal from the same bed. Although the information in this report demonstrates that the performance of the pneumatic cleaners is not as good as that of those employing water, it must not be construed as reflecting on the usefullless of such equipment. Performance is often secondary to other factors in the selection of coal-cleaning equipment, and the advantages inherent in pneumatic processes frequently outweigh the limitations imposed by their performance. Specific gravity and particle size are the principal factors that influence the separation of coal from impurity in either pneumatic or wet processes; consequently, the tools available for this investigation were the float-and-sink bath and the screen. Accordingly, the raw coal, clean coal, and refuse samples representing the operation of each type of cleaning unit were first separated into a series of density fractions by means of the float-and-sink bath, and then each density fraction was screened into a series of size fractions. By this procedure the raw coal, clean coal, and refuse were subdivided into components of restricted ranges in density and size. From these data it was possible to determine how the cleaning unit disposed of each component of the raw coal; that is. what proportion of each component is sent to clean coal or rejected as refuse.

Jan 1, 1947

By H. F. Yancey, M. K. Geer

Investigations of the fundamental factors involved in the performance of various coal-cleaning processes have constituted a substantial portion of the research 011 coal cleaning conducted by the Bureau of Mines. These detailed studies of the mechanism of separating coal from impurity in various cleaning devices were undertaken to provide the coal industry with information that is helpful in selecting the type of cleaner most suitable for treating a particular coal. Previous reports describing these investigations have dealt with the wet table,1 the pneumatic table,&apos; and the plunger,3 pulsator.4 and Baum types5 of jigs. The present report compares the performance of three commonly used units treating the same coal—a pneumatic jig, also known as the air-flow. cleaner, a pneumatic table, and a Baum-type jig. Object and Plan The fact that pneumatic coal-cleaning processes are less efficient than wet-washing methods because they are unable to make as sharp a separation between coal and impurity is well recogilized. The literature, however, contains little quantitative in- formation on the relative performances of the two types of cleaners. The object of the present report is to present a detailed comparison of the performances of two pneumatic units and one wet-washing process treating coal from the same bed. Although the information in this report demonstrates that the performance of the pneumatic cleaners is not as good as that of those employing water, it must not be construed as reflecting on the usefullless of such equipment. Performance is often secondary to other factors in the selection of coal-cleaning equipment, and the advantages inherent in pneumatic processes frequently outweigh the limitations imposed by their performance. Specific gravity and particle size are the principal factors that influence the separation of coal from impurity in either pneumatic or wet processes; consequently, the tools available for this investigation were the float-and-sink bath and the screen. Accordingly, the raw coal, clean coal, and refuse samples representing the operation of each type of cleaning unit were first separated into a series of density fractions by means of the float-and-sink bath, and then each density fraction was screened into a series of size fractions. By this procedure the raw coal, clean coal, and refuse were subdivided into components of restricted ranges in density and size. From these data it was possible to determine how the cleaning unit disposed of each component of the raw coal; that is. what proportion of each component is sent to clean coal or rejected as refuse.

Jan 1, 1947

By Walter R. Hibbard, Walter L. Finlay

INTRODUCTION THE key feature of the lattice coherency theory of precipitation hardening1-6 is the forced coherence between matrix and precipitate which elastically strains both lattices and is believed to be the major source of strengthening in precipitation hardening. In systems exhibiting age hardening, the atom movements leading to precipitation are not at all extensive and are such as to require the minimum amount of energy to produce the interface; that is, the new lattice forms in such a way as to be as nearly as possible a continuation of the old with a matched, coherent plane at the interface at least during the initiation of the precipitation. The crystallographic sequence whereby regions of the matrix change to the precipitate lattice usually can be resolved into a set of shearing operations.5,6 Conversely, the perhaps novel speculation is made that solution of a second phase is accompanied by shearing movements which are possibly the reverse of the precipitation shearing movements. A basic premise of the investigation reported in this paper is that precipitation and solution shearing movements constitute structural weaknesses which might cooperate with applied stresses to facilitate plastic deformation. Another basic premise of the investigation is that the application of hydrostatic pressure to a precipitation hardening system will significantly alter the degree of disregistry across the matrix-precipitate interface and thereby significantly affect the course of age hardening. Two binary precipitation hardening systems were investigated: 12 pct zinc in aluminum which undergoes transformations, both precipitation and solution, by a simple crystallographic mechanism; and 4 pct copper in aluminum which undergoes a complex transformation in precipitating and dissolving a second phase. The effects of the application of uniaxial tensile creep stress during elevated temperature aging of both systems and of hydrostatic pressure during the elevated temperature aging of 12 pct aluminum-zinc were then investigated. Previous Investigations Van Wert in 1935,7 studied the effect of hydrostatic pressure on the room temperature age hardening of a few precipitation hardening systems. The latter were rather unfortunately selected since none is known to exhibit any marked volume change on aging and the majority were complex commercial alloys the precipitation mechanisms of which are not known. Jenkins, Bucknall and Jenkinson,8 in 1944, applied tensile creep stresses to a complex coppernickel-silicon alloy at various temperatures. The complexity of the alloy and the industrial objective of the work did not permit an appreciable addition to the theoretical understanding of either deformation or precipitation hardening.

Jan 1, 1948

By R. H. B. Jones

This paper reviews pertinent geology of the Biwabik iron formation, Mesabi Range, Minnesota. This iron formation is divisible into four members. Each member is distinctive and contains marker horizons, which are recog nizable throughout all phases of alteration from lean, fresh rock to high-grade iron ore. Some beds have a larger magnetite content than others. During the process of ore genesis, which is essentially an oxidation process, the magnetite content is lowered. Alteration from iron formation to ore includes both oxidation of iron minerals and silica removal by leaching and these distinct processes progress at variable rates for different locations and structures. Magnetic intensities, of each horizon of the iron formation are dependent chiefly upon its preoxidation magnetite content, upon the subsequent degree of oxidation, upon the character of the enclosing rocks, and on the extent of fracturing, folding, or faulting. The results of a number of magnetic surveys are described and are correlated with results of drill-hole and mine exploration and developmerit. The magnetic anomalies obtained are discussed in relation to phases of formation of ore within the iron formation. General Information One hundred years ago a party of surveyors, applying the principles of geophysical prospecting, discovered iron ore in the state of Michigan in the Lake Superior district. This event was officially reported as follows:&apos; On Sept. 19 (1844) while running the east line of Town 47 North, Range 27 West, they observed by means of the solar compass remarkable variations in the direction of the needle, amounting to 87" from the normal. Ascribing this phenomenon to iron ore, they sought and found it in ledges or outcrops at several points. The solar compass referred to was invented by William A. Burt, deputy surveyor in charge of this party.2 It is used for determining the true meridian by an observation on the sun. Eight years later, on July 7, 1852, the first iron &apos;re, consisting of 6 bbl. of Ore, was shipped from Marquette, Michigan. It was another 40 years before the first or> shipment left the Mesabi Range in Minnesota, in October 1892. It totaled 4245 tons. Fifty years later, 90 years after the original shipment, during 1942 the Lake Superior district shipped 93,495,392 gross tons of iron ore. Production came from Minnesota, Michigan, Wisconsin, and Ontario, Canada. Throughout the 90-Year period it was known that magnetic properties of most of the ore bodies, and of the iron formations in which they occur, affected the compass. This phenomenon, later to be made use of to outline areas of ground favorable for exploration, was at first a

Jan 1, 1949

By W. R. Finlay, W. R. Jr. Hibbard

The key feature of the lattice coherency theory of precipitation hardening1 is the forced coherence between matrix and precipitate which elastically strains both lattices and is believed to be the major source of strengthening in precipitation hardening. In systems exhibiting age hardening, the atom movements leading to precipitation are not at all extensive and are such as to require the minimum amount of energy to produce the interface; that is, the new lattice forms in such a way as to be as nearly as possible a continuation of the old with a matched, coherent plane at the interface at least during the initiation of the precipitation. The crystallographic sequence whereby regions of the matrix change to the precipitate lattice usually can be resolved into a set of shearing operations.6&apos;6 Conversely, the perhaps novel speculation is made that solution of a second phase is accompanied by shearing movements which are possibly the reverse of the precipitation shearing movements. A basic premise of the investigation reported in this paper is that precipitation and solution shearing movements constitute structural weaknesses which might cooperate with applied stresses to facilitate plastic deformation. Another basic premise of the investigation is that the application of hydrostatic pressure to a precipitation hardening system will significantly alter the degree of disregistry across the matrix-precipitate interface and thereby significantly affect the course of age hardening. Two binary precipitation hardening systems were investigated: rz pct zinc in aluminum which undergoes transformations, both precipitation and solution, by a simple crystallographic mechanism; and 4 pet copper in aluminum which undergoes a complex transformation in precipitating and dissolving a second phase. The effects of the application of uniaxial tensile creep stress during elevated temperature aging of both systems and of hydrostatic pressure during the elevated temperature aging of 12 pct aluminum-zinc were then investigated. Previous Investigations Van Wert in 1935,~ studied the effect of hydrostatic pressure on the room temperature age hardening of a few precipitation hardening systems. The latter were rather unfortunately selected since none is known to exhibit any marked volume change on aging and the majority were complex commercial alloys the precipitation mechanisms of which are not known. Jenkins, Bucknall and Jenkins~n,~ in 1944, applied tensile creep stresses to a complex copper. nickel-silicon alloy at various temperatures. The complexity of the alloy and the industrial objective of the work did not permit an appreciable addition to the theoretical understanding of either deformation or precipitation hardening.

Jan 1, 1949

By J. H. Henderson, H. J. Ledbetter, N. B. Gove, J. D. Griffith

INTRODUCTION The results of a series of laboratory flood tests using liquid Iso-butane to displace refined oils from test cores are pre- ented and interpreted on an empirical bask. The study Revealed the similarity of the miscible liquid displacement to that of the immiscible-fluid displacement mechanism. The efficiency of the iso-butane flood decreased markedly as the oil Viscosity increased. but the effect of injection rate on the effectiveness of the primary production stage was negligible over the range investigated. The presence of free-gas saturation prior. to iso-butane breakthrough increased the volume of iso- Butane required to recover a given percentage of the oil present. Injection of liquid i.e.-butane prior to water follicle sculpted in a marked improvement in oil recovery by the water flood. INTRODUCTION The production of petroleum is often enhanced by the injec-1i1)n of extraneous fluids into the reservoir. It has been suggeited that the injection or cycling of a wet gas or a liquefied petroleum gas would he instrumental in increasing the effic.ienr!; of oil recover! to a greater degree than the commonly injected fluids. dry pas and water. Although instances of injection of light liquid hydrocarbons are not unknown, a systrmatic recording of the result is unavailable and superfi- cially, the practice gives the impression of being economicaIIy unsound. For specific types of displacement, analytic: solutions have been advanced which aid in understanding the physical mechanisms involved. However, there is no generalized theoretical concept which permits adequate prediction of displacement efficiency from a knowledge of readily measured reservoir rock and fluid properties. The Buckley-Leverett approach to oil displacement by an immiscible phase is an admirable analysiy of that type of mechanism. Dykstra and Parsons have introduced a useful concept in their evaluation of the role of the mobility ratio and its merit in rationalizing displacement phenomena. Everett, Gooch and Calhoun3 in their report on the effect of viscosity ratio and miscibility have pointed out the lack of a comprehensive theoretical approach and the desirability of investigating the mechanism of miscible-miscible displacement. In lieu of a well-developed theory concerning miscible-111isci1)le displacement and in view of the scarcity of engineering information on actual LPG injection trials, the limited program of laboratory experimentation described below was undertaken. OBJECTIVES The original broad objectives of the program, to study the oil recovery process using LPG as the displacing phase, defined the direction and scope of the laboratory tests. The specific objective. of the experimentation were to evaluate

Jan 1, 1953

By Harry M. Mikami

Refractories are heat-resistant, generally nonmetallic materials used as the linings of furnaces or high temperature vessels in the steel, iron, nonferrous metals, glass, cement, lime, ceramic, chemical, petroleum, paper, and power and heat generation industries. Refractories must have structural strength at high temperatures but also, in many applications, must simultaneously resist chemical-physical corrosion-erosion from stags, metals, granular solids, or gases. Among the major uses are the pyrometallurgical processes for producing iron, steel, copper, aluminum, nickel, lead, zinc, etc. Rotary cement kilns, glass tanks, refineries, utility boilers, chemical and ceramic (including refractories) plants, and a myriad of other smaller scale users employ refractories in the high temperature parts of their operations. Thermal, chemical, and structural conditions under which refractories are used differ widely so there is a great variety of refractories to fill the various needs. Two major classifications are the "basic" and "acid" types. Basic refractories include magnesia and chromite, singly and in combinations, dolomite, and forsterite (olivine). The acid category includes aluminosilicates, alumina, and silica. There are a number of other specialized types such as carbon, graphite, silicon carbide, zircon, and zirconia that have important applications but are used in much smaller amounts than the major categories. Physically, refractories can be divided into bricks and shaped products on the one hand and unshaped or monolithic products (also termed specialties) on the other. There are many further subclassifications and divisions, a discussion of which is beyond the scope of this chapter; see Refs. 2 and 9. Raw materials for the principal basic refractories are magnesia and chrome ore. Magnesia, generally termed magnesite or periclase, is obtained mainly from seawater or saline brines extraction, but substantial amounts are produced from mined magnesite (MgCO3). Dolomite (CaCO3•MgCO3), another important basic refractory, is obtained entirely from mined sources. Acid refractory raw materials are: fire clays, flint clays, kaolin, and other natural clay minerals; aluminosilicate minerals such as kyanite, andalusite, sillimanite, pyrophyllite, bauxitic clays; calcined refractory grade bauxite, alumina from the Bayer process for the alumina group; and quartzitic rocks for silica refractories. The total value of all refractories shipped in the United States in 1974 was $989 million, a record to that date. Of this amount, about 73% represents bricks and shaped products and 27% is in nonshaped or monolithic products which comprise mortars, cements, castables, plastics, and ramming and gunning mixes. Fig. 15.4E.1 shows the rising value of all U.S. refractory shipments in the period 1948-1974. Values of brick and shapes paralleled

Jan 1, 1976