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By Frank Firmstone

IT is often desirable to obtain one or more accurate horizontal sections of a blast furnace after blowing out. Wishing to do this, last April, in the case of No. 4 furnace at Glendon, which had worn in a very remarkable manner, the method described below was employed, with very good results. A scaffold was fixed in the furnace, and on it was placed a drawing- board, covered with paper, the top of which was made level at exactly the height at which the section was to he taken. (Fig. 8.) The centre of the furnace (which had previously been found, and marked on a plank across the top) was laid off on it by dropping a plumb-bob from above, and a strong needle was driven into the board in the centre. By means of a straight-edge and two plumb- bobs, the line passing through the centres of the front and back arches was also drawn on the board. A pencil was fastened to a light wooden straight-edge at a known

Jan 1, 1875

By Frank Firmstone

It is often desirable to obtain one or more accurate horizontal sections of a blast furnace after blowing out. Wishing to do this, last April, in the case of No. 4 furnace at Glendon, which had worn in a very remarkable manner, the method described below was employed, with very good results. A scaffold was fixed in the furnace, and on it was placed a drawingboard, covered with paper, the top of which was made level at exactly the height at which the section was to he taken. (Fig. 8.) The centre of the furnace (which had previously been found, and marked on a plank across the top) was laid off on it by dropping a plumb-bob from above, and a strong needle was driven into the board in the centre. By means of a straight-edge and two plumbbobs, the line passing through the centres of the front and back arches was also drawn on the board. A pencil was fastened to a light wooden straight-edge at a known

Jan 1, 1879

By Henry Hibbard

Fox the purpose of this paper all steels will be divided into two divisions: effervescing and non-effervescing. This classification must be borne in mind as many statements true of one class are not true of the other. Effervescing steels are those that effervesce in the molds, evolving large volumes of gases, which, in escaping, throw up a spray of molten particles of steel and give the molten metal in the mold a rapid stirring or churning motion until it freezes, or, at least, becomes pasty. This effervescing is intended and proper. The non-effervescing steels, which are more or less completely killed, should not evolve any gas in the molds. Many years ago the writer proposed to call the two classes of steels evolution and solution steels, depending on whether the gases in the molds are evolved or kept in solution, but the present designations seen to be better. In America, at least, effervescing steels are in a class by themselves and include steels made for boiler, tank, and ship plates, steel pipe, soft steel wire, wire nails, soft machinery, and structural steels. These are all low-carbon steels with less than 0.40 per cent. carbon. Low-carbon steels that do not effervesce but are killed are also made; these are put into ingots and castings but they are outside the limits of this paper. Effervescing steel is cast into square or slab molds, either top or bottom poured. Most of the effervescing steel is made in the basic open-hearth furnace, though much is made by the acid Bessemer process and a little is made in the acid open-hearth. It is not made by the crucible or electric-furnace process, in which the volume of gas required cannot be produced in the steel and evolved from it in the mold to give the effervescence desired. Any steel ingot, when teeming is finished, is of a certain size or volume. Leaving out of consideration for the moment the lessening of the over-all dimensions of the ingot through contraction due to loss of heat, the ingot may be placed in one of three classes: It may settle, losing in volume; it may stand, that is, remain constant in volume; it may rise, that is, increase in volume.

Jan 9, 1919

The sessions of the Institute were opened on Tuesday evening, October 26th, at Garrett's Hall, by Mr. Charles A. Otis, Chairman of the Local Committee of Arrangements, who welcomed the Institute to Cleveland, and introduced Col. Charles Whittlesey, who addressed the Institute briefly on the coal deposits of Ohio. Col. Whittlesey described the situation and character of the coalbeds of the State, and gave a short history of the use of raw coal in the manufacture of pig-iron, and spoke of the excellent quality of metal produced. The aid that a body of scientific miners and metallurgists were capable of giving in the development of coal and other mineral resources was dwelt upon, and the hope expressed that the visit of the Institute to Cleveland might be profitable as well to its members as to the citizens of the State. The President, Mr. A. L. Holley, responded to the welcome of Mr. Otis and of Col. Whittlesey, and read an introductory address on Some Pressing Needs in the Iron and Steel Manufacture. The following members and associates, duly proposed and indorsed by the Council, were then elected MEMBERS. Alfred S. Bertolet,.. .. . Youngstown, Ohio. Henry Binnse,. Chicago, Ill. John Birkinbine,.. .. . Philadelphia. Andrew A. Blair,. .. .. Watertown Arsenal, Mass. Ogden Bolton,. .. .. Canton, Ohio. Lloyd Booth,..Youngstown, Ohio. E. Borda,..Philadelphia. N. P. Bowler,.. .. . Cleveland, Ohio. Alexander E. Brown,.... Cleveland, Ohio. C. F. Brush,.. .. .Cleveland, Ohio. S. M. Carpenter,.. .. . Cleveland, Ohio. James Cartwright,.. .. . Youngstown, Ohio. Henry Chisholm,.. .. . Cleveland, Ohio. Wilson B. Chisholm,.. .. . Newburgh, Ohio. W. H. Clarke,.. .. . Millertown, Pa. James E. Clayton,. .. .. Ore Knob, N..C.

By T. G. Digges, C. L. Vold, M. R. Achter

A study was made of the effect of the growth conditions on the perfection of single crystals of niobium (columbium). Dislocation densities, determined by means of double-crystal diffractometer measurements , were not greatly affected by the method of crystal preparation but could be reduced by annealing treatments. However, the size, sharpness, and tilt angles of the substructures, observed with X-ray reflection macrograph, were sensitive to variations in growth procedures as well as to subsequent thermal treatments. Although the dislocation density was the same in both types, there were more low-angle bound-aries in crystals grown by zone melting than in those prepared by strain anneal. Mechanisms to account for these observations are discussed in terms of dislocation movements. A planned study of the structure-sensitive properties of refractory metals required the use of single crystals of a high degree of structural perfection and, for ease of handling, of large cross section. It appeared that the strain-anneal technique could satisfy both of these requirements. First, crystals grown in the solid state have been reported to be more perfect than those obtained from the melt.' Second, the diameters of rods which may be produced by zone melting should have a theoretical limit determined by specific gravity, thermal conductivity, and surface tension, while the diameter of strain-annealed rods is limited only by practical considerations. Previously it was shown that niobium (columbium) single crystals of 1 in. diam2 may be grown by strain anneal, compared to the 0.5 in. maximum diameter achieved by zone melting, as reported for molybdenum by Belk.3 The current research was undertaken to investigate and optimize the effect of various process variables on the perfection of 1/4 and 1/2-in.-diam niobium single crystals grown by strain annealing and to compare their perfection to those grown by zone melting. Characterization of these crystals was more conveniently accomplished by means of X-ray than by metallo-graphic techniques. EXPERIMENTAL PROCEDURE Specimen Preparation. Zone-melted crystals of 1/4 in. diam were produced by the standard electron-beam zone-melting technique. The swaged and cleaned rods were outgassed, in the solid state at a temperature near its melting point, at a rate of 12 in. per hr, and single crystals were grown by making two molten passes at 2 in. per hr. By maintaining a zone length of 4 to % in., very uniform single crystals several inches long were obtained. For the strain-annealed crystals, an induction heater was used, in preference to other types of heating, to take advantage of the good penetration of large sections. A five-turn coil, 1 in. long, operating at 10 kc and powered by a motor generator, was contained in a vacuum chamber. The rod, suspended from the upper end, was raised through the coil for both recrystallization and crystal growth. In preliminary work single crystals of the same material were also grown with single and multiturn coils powered by a 450-kc generator. A vacuum of 2 X 10-6 Torr was maintained at temperatures up to 2400°C. Starting with electron-beam-melted ingots of 21/2 in. diam, the analysis for which is given in Table I, the material was cold-swaged to the desired cross section of 1/4 and 1/2 in. diam and then recrystallized. The rods were then strained in a tensile machine and converted to single crystals by passing through the induction coil. As with zone melting, control of orientation is possible by the use of special procedures. Other investigators, see for example Williamson and smallman,4 have reported that orientation control may be achieved by a bending technique. In the present work the strained rod is partially lowered through the coil to start the growth of the crystal. Then it is removed and bent at a point in the poly crystalline portion. Finally, it is returned to the chamber and growth is continued "around the corner". This procedure has certain limitations. If the bending operation exceeds the critical strain, recrystallization may take place. Also, the amount of bending which can be imparted to the rod is limited by coil geometry, and up to now has been 10 deg. However, by repeating the bending and growing operations it should be possible to attain any desired orientation. In preparation for X-ray examination, single crystals were sectioned and planed by means of the spark-erosion technique. To obtain the maximum reflected intensity, the (110) plane was exposed for examination. They were then etched 3 to 5 min in a mixture of con-

Jan 1, 1967

THE sessions of the Institute were opened on Tuesday evening, October 26th, at Garrett's Hall, by Mr. Charles A. Otis, Chairman of the Local Committee of Arrangements, who welcomed the Institute to Cleveland, and introduced Col. Charles Whittlesey, who ad¬dressed the Institute briefly on the coal deposits of Ohio. Col. Whittlesey described the situation and character of the coal-beds of the State, and gave a short history of the use of raw coal in the manufacture of pig-iron, and spoke of the excellent quality of metal produced. The aid that a body of scientific miners and metal¬lurgists were capable of giving in the development of coal and other mineral resources was dwelt upon, and the hope expressed that the visit of the Institute to Cleveland might be profitable as, well to its members as to the citizens of the State. The President, Mr. A. L. Holley, responded to the welcome of Mr. Otis and of Col. Whittlesey, and read an introductory address on Some Pressing Needs in the Iron and Steel Manufacture. The following members and associates, duly proposed and indorsed by the Council, were then elected MEMBERS. Alfred S. Bertolet, - Youngstown, Ohio. Henry Binnse, - Chicago, Ill. John Birkinbine, - Philadelphia. Andrew A. Blair, - Watertown Arsenal, Mass. Ogden Bolton, - Canton, Ohio. Lloyd Booth, - Youngstown, Ohio. E. Borda, - Philadelphia. N. P. Bowler, - Cleveland, Ohio. Alexander E. Brown, - Cleveland, Ohio. C. F. Brush, - Cleveland, Ohio. S. M. Carpenter, - Cleveland, Ohio. James Cartwright, - Youngstown, Ohio. Henry Chisbolm, - Cleveland, Ohio. Wilson B. Chisbolm, - Newburgh, Ohio. W. H. Clarke, - Millertown, Pa. James E. Clayton, - Ore Knob, N. C.

Jan 1, 1876

By R. Schuhmann Jr., P. J. Ensio

As a first step in a study of the physical chemistry of copper-smelting slags, experimental measurements were made of the oxygen pressure of simple iron-silicate slags in equilibrium with solid iron. The experiments consisted in bubbling CO2-CO mixtures through the slags in iron crucibles and in finding the equilibrium ratios of CO2 to CO. From the data, activities and partial molal heats of solution FeO and SiO2 in the slags were calculated. THE ternary system FeO-Fe,O,-SiO, is the simplest system which can represent adequately the important chemical properties of the slags formed in matte smelting and converting. Accordingly, the experimental study of slags in this system was started as the first step in a general research program on the thermodynamics of copper smelting. A recent paper by one of the authors' outlines this general research program and shows in some detail how information on thermodynamic properties of iron-silicate slags, especially information on oxygen activities, is essential to a full understanding of the chemistry of copper smelting. The FeO-Fe,O,-SiO, system also is the basis of slags produced in other processes, such as acid steelmak-ing processes, and is important in relation to the behavior of silicious refractories. In addition, data on the physicochemical properties of iron-silicate slags should contribute to a general understanding of the nature of slags, since at present such data for all kinds of slags are relatively meager. The principal quantitative information already available on iron-silicate slags consists in Bowen and Schairer's constitution diagram for slags in equilibrium with metallic iron,' Darken and Gurry's complete and precise thermodynamic study of the Fe-0 system,",' and Darken's study of the phase equilibria in the Fe-Si-o system. From the results of this previous work, it was clear that a complete thermodynamic study of ternary iron-silicate melts was a major undertaking which would have to be broken down into parts, including the working out of the ternary equilibrium diagram as well as extensive activity measurements on slags. The experimental measurement of oxygen activity, using CO-CO, and other gas mixtures as yardsticks of oxygen activity, was the basis of Darken and Gurry's study of the Fe-0 system. From the experimental measurements of oxygen activities over a large range of temperatures and compositions, they were able to calculate the activities of other species such as Fe, FeO, Fe,O,, etc., and also the other important thermodynamic properties in the Fe-0 system. At the start of the present investigation, it appeared that the same approach would be fruitful for the study of iron-silicate melts. Also, the experimental measurement of oxygen activities seemed particularly attractive because oxygen activity itself is a quantitative measure of oxidizing or reducing power, which is an important variable in copper-smelting slags. The slag compositions in equilibrium with yFe appeared most suitable for the first investigation of this kind, for the following reasons: 1—Good constitution data2 were available. 2—An iron crucible could be used, thus affording a simple solution to the refractory problem without introducing contarnination. 3—With Fe activity fixed, at unity with respect to a standard state of solid Fe, measurements of 0 activity could be followed by simple calculations of activities of FeO and other Fe-0 complexes and of SiO,. 4—This starting point afforded several possibilities for cross-checking with previous work,

Jan 1, 1952

By David A. Summers, John Corwine, Li-King Chen

The results from fracturing plexiglas beams are combined in eight existing equations to determine the surface energy of the material. The reliability of each equation is tested, and the equation in use to determine fracture toughness is found to be the most exact. This equation is then used in determination of the surface energy of Barre Granite.

Jan 1, 1971

By C. R. Austin

THE investigation described in this paper deals with the development of high-temperature alloys of the Konel series over a considerable period of time at the Research Laboratories of the Westinghouse Electric and Manufacturing Co. The word "Konel" has been coined to designate a class of alloys which are essentially nickel-cobalt-iron with other elements added, usually in small quantities. Most of these alloys contain titanium, usually about 2.5 percent. The main consideration related to strength at high temperatures but the thermionic characteristics of the alloys was also of considerable importance. It is, however, with the mechanical properties at elevated temperatures that we are herein concerned. Much attention has also been devoted to their age-hardening characteristics. There is little need to stress the utilitarian aspect of this subject, as it has been discussed frequently. Alloys exhibiting superior properties at normal or elevated temperatures rapidly find many suitable applications. There may be some question, however, as to what constitutes a "superior alloy, " or an alloy that may have good service possibilities at high temperatures. The problem is complex and various means have been employed to predict the useful life that may be expected of a material. In recent years the "creep limit" has been used as the best means of evaluation. Such tests necessarily are prolonged and hence collection of data is very slow. In a general survey of many alloys therefore the creep test is not desirable and recourse must be had to much shorter time tests in order more rapidly to select alloys which appear to show promise. For this reason the present survey has been made using the high-temperature tensile test and a bend' test developed by Howard Scott.1 In the tensile test the conditions have been standardized for all tests, so that values obtained are at least comparable, one alloy with another, although the absolute values recorded merely indicate the mechanical properties at the given temperature under a definite rate of loading.

Jan 1, 1931

By Robert M. Grogan, Gill Montgomery

Fluorspar, the commercial name for fluorite, is a mineral composed of calcium fluoride, CaF,. Its valuable properties are due to its content of fluorine, and it is the principal commercial source of that element. The name is derived from the Latin word "fluere," to flow, because the mineral has a low melting point and is used in metallurgy as a flux. Cryolite is a sodium aluminum fluoride, Na,AlF,. It is a rare mineral which has been found in commercial quantities in only one place in the world, Greenland. Small amounts of it are shipped from stock in that country, and its place in industry has been taken over almost completely by synthetic cryolite. Because of the relative unimportance of cryolite, discussion of it has been relegated to a short section at the end of this chapter, which is principally concerned with fluorspar. History Fluorspar was used for ornamental purposes by the Greeks and Romans, who fashioned such things as vases, drinking cups, and table tops from it. Various peoples including the Chinese and the American Indians carved ornaments and figurines from large crystals. Its usefulness as a flux was known to Agricola (1564), who wrote about it in 1546. Mining began in England about 1775 and at various places in the United States during the period 1820 to 1840. Production became substantial following the development and widespread adoption of the basic open hearth method of making steel, in which fluorspar is used as a flux. After that, production and usage were stimulated by growth in the steel, aluminum, chemical, and ceramic industries and were accelerated by World Wars I and II. Fluorocarbons entered the picture in 193 1 and the use of anhydrous hydrogen fluoride (HF) as a catalyst in the manufacture of alkylate for high octane fuel blends began in 1942. The development of the froth flotation process in the late 1920s, a differential flotation scheme for separating fluorspar from galena, sphalerite, and common gangue minerals in the 1930s, and the application of heavy-media concentrating methods to the treatment of low grade ores in the 1940s were outstanding technological contributions that enabled increased production of fluorspar concentrates. In recent years the development of pelletizing and briquetting processes for making flotation concentrates into gravel-size particles for use in steel furnaces and the development of more efficient and selective flotation schemes for treating crude ores containing abundant dolomite and barite have been major improvements in the industry.

Jan 1, 1975

By F. A. J. Fitzgerald

In any kind of furnace the question of preventing the loss of heat is important, for no matter how the heat is obtained it costs something; and consequently, other things equal, that furnace is most desirable which uses the greatest percentage of the total heat generated for the particular object in view. In the furnace which uses electricity for the generation of heat the importance of preventing losses of heat is very much greater than in any other. To generate 1,000 kg-cal. requires an expenditure of 1.16 kw-hr., and consequently the cost per calorie is always expensive when electricity is used for heating. In heating any material in a furnace a general rule is that the generation of heat should be as rapid as possible. In any given furnace the heat-losses may be expressed as so many watts, and, therefore, the longer it takes to heat the furnace-charge the greater the losses will be. Suppose that a furnace contains a charge to be heated to 1,500°C. and that the average loss of heat is at the rate of 100 kw., then if the process of heating the charge takes 1 hr. the losses will amount to 100 kw-hr.; but if by using a more rapid generation of energy the charge can be heated in 30 min. the losses will amount to 50 kv-hr. An example from experiments on a certain process may be given to illustrate this point. The problem was simply to heat a furnace-charge to a certain temperature, and experiments were made to determine the effect of increasing the rate of generation of energy and comparing the kilowatt-hours required to heat a given charge. Here are typical results : Rate of Generation Energy Per Kg. of Energy. of product 88 kw. 1.7 kw-hr. 93 kw. 1.6 kw-hr.

Jan 1, 1913

By AIME

TURMOIL has been rampant in the lead producing industry during 1946. The chronic labor shortage was aggravated by various work stoppages in mines, smelters, and refineries, while shortage of materials was widespread. Price uncertainties helped to confuse the situation in many countries and particularly in the United States until the removal of price control in the latter part of the year. At the end of the first year of peace, lead, which had been comparatively plentiful during the war years, was a scarce and high-priced metal throughout the world. It is the hope of the industry that the law of supply and demand, if allowed to operate without interference, will bring about a satisfactory balance between production and consumption. Under these circumstances it is not surprising that there have been few important developments in the metallurgy of lead, though a number of items of general interest to the industry have been reported. An ore body which may prove to be of considerable importance has been discovered at Mpanda, Tanganyika. The scarcity of lead ore is illustrated by the announced reopening of the La Manche lead mine in Newfoundland, idle for 56 years. A new lead producer came into production when Rhodesia Broken Hill started up its new smelter. Lead concentrate of 75 per cent grade is smelted in Scotch hearths and the lead is refined to market grade by the Harris process without desilverizing. Production is about 1000 tons per month. One Australian lead producer, Mount Isa, has returned to lead production after having operated its lead plant for the production of copper during the war. The East Chicago plant of the International Smelting and Refining Co. has been sold to the Eagle-Picher Co.

Jan 1, 1947

By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By L. J. Erck, T. E. Ban

A discussion of laboratory procedures used to determine pellet quality and to simulate handling and firing conditions. Strength-temperature relationships in pelletizing; effect of chemical additives on agglomeration; and crushing, abrasion, and impact resistance of the pelletized products are discussed with respect to five different iron ore concentrates. IN most routine experimental work on products and processes, method:; of operation and product evaluation are established from accurately controlled laboratory tests. With particular emphasis on the pelletization of fine iron ore concentrates, standardized procedures of laboratory production and product testing have been established at Cleveland-Cliffs Iron Co. Research Laboratory at Ishpeming, Mich. A program of this nature was used for investigating the agglomeration characteristics of various iron ore concentrates. The factors which control the process were studied and subsequently controlled for these investigations. Pelletizing as applied to iron ore agglomeration involves the preparation of spheroidal masses from a fine moist concentrate, followed by high-tempera-ture firing to produce a final product. The preparation of moist spherorids is generally designated as balling. This produces the so-called green pellets or balls. After, these have been fired they are called pellets. Balling is accomplished by rolling moist concentrates in a revolving drum until small spheroids form by a snow-balling action. These balls are then heated in a shaft furnace, or a modification of this device, to a temperature high enough to cause agglomeration within the individual balls while they descend countercurrent to hot oxidizing gases. By this process the lour strength balls are converted through various chemical and physical-chemical processes into hard pellets. With correct balling and firing, the pellets are strong, resist abrasive action and handling treatments, and provide a suitable blast furnace and open hearth feed. In 1950 Tigerschiold and Ilmoni developed a working hypothesis to explain the formation and stability of green pellets.' Their work was presented on the basis of geologists' discoveries concerning the soil-water system and C. V. Firth's early postulates of green pellet formation.' Fundamental reactions oc-curing within fired pellets have been described by Cooke and Ban, who showed the microstructure changes caused by different firing temperatures." All these investigators have provided scientific clarifications of agglomeration by the pelletizing process and have opened avenues for greater development. Mineral grain growth and ceramic bond formation are the two basic phenomena imparting coherency to particles within a fired pellet of iron ore. Each of these is established by the transfer of thermal energy to the mineral particles. Grain growth mechanisms are chiefly physical reactions wherein smaller particles consolidate into larger ones, with resulting decrease in surface energy conforming with the second law of thermodynamics. Ceramic bond formation is a chemical reaction usually between basic and acid metallic oxides of the gangue and ore minerals. CaO, MgO, A1203, and FeO of Fe3O4, react in varying proportions with SiO, or Fe2O3, to form a great series of compounds or amorphous solid solutions. These product bond iron mineral particles together by a bridging action or by direct reaction with the surfaces of the particles. The result of the grain growth-ceramic bond formations is a consolidated, coherent compact of gangue and iron minerals formerly held together by much weaker bonds of interstitial water and forces common to dry, unconsolidated particles.4 With respect to iron ore agglomeration, these high temperature bonding reactions have been described by Schwartz, who referred to the bonds in sinters," and by Cooke and Ban, who referred to the bonds in fired pellets." The extent of the bonding phenomena and the consequent strength of fired pellets is governed by

Jan 1, 1954

By Richard B. Greenwalt, John M. Bertram, George E. Aiken

Agglomeration developments in the iron ore industry of North America over the past twenty years are closely related to shifting patterns in commercially acceptable ore grades and even the definition of iron ores. As early as WW II the rich Mesabi hematites were depleted, ending a 50-year era of direct shipping ores that included reserves of an estimated three billion tons. Decreasing ore grades and rising costs began to force the closing of many underground iron mines and processes were being developed to use domestic low-grade iron deposits. This resulted in the rapid development of iron ore beneficiation processes and signaled the coming trend toward concentration, sintering and pelletizing. Yet even today when agglomeration facilities are treating 90 % of the Mesabi Range product much remains to be done in keeping world-wide competitive forces in check and in ensuring the long- term utilization of these expansive ore supplies in an up-until-now captive U.S. market.

Jan 10, 1973

By Thomas M. Drown

The use of bromine as an oxidizing agent, particularly for sul phur, has become very general in analysis, replacing the stronger oxidizing acids. The object of this paper is to describe briefly the experience which we have gained with this reagent in the laboratory of Lafayette College in the oxidation of metallic sulphides. Most of the simple sulphides, as blende, pyrite, etc., when exposed to the combined action of an alkaline hydrate and bromine, and finally to hydrochloric acid, are completely and promptly dissolved. The procedure is as follows: The very finely pulverized mineral is first treated, in a beaker, with a solution of sodium hydrate of a spe cific gravity of 1.25, and heated ; bromine is then cautiously added to supersaturation, and finally hydrochloric acid to acid reaction. If any of the sulphide is not taken up, the same operation may be re peated. It is necessary, however, that the mineral be very finely pulverized. Instead of using the pure bromine, a saturated solu tion of bromine in potassium bromide may be used with equally good effect. The process is advantageously simplified by making a saturated solution of bromine in the concentrated alkali. This is done by pouring bromine into a solution of sodium hydrate, of the above given specific gravity, until no more is taken up, and then adding a little of the sodium hydrate solution until the liquid does not give off free bromine. The procedure with this solution is as follows: The pulverized mineral is moistened with, say, 10 cc. of the solution, and heated, then hydrochloric acid added to just acid reaction. Two more additions of the alkaline solution, in amounts of 20 cc. each, are added at intervals of about ten minutes, each addition being followed by hydrochloric acid. The total amount of the alkaline solution (containing the bromine) used is, therefore, 50 cc., and the amount of hydrochloric acid should not exceed that necessary to make the solu tion acid after each addition of the alkali. The mixture should be kept hot. After the final addition of acid, the contents of the beaker is taken to dryness and heated in an air-bath to 110° to 115°C., to render silica insoluble. The dry mass is then taken up by hydro' chloric acid and water and, after filtration, the sulphuric acid is pre

Jan 1, 1880

By John M. Hartman

An examination as to irregularity of wear around the nose of the Witherbee tuyeres showed a section through the nose near the top as per Fig. 1, and a section only a half-inch beyond as per Fig. 2. The molten iron flowing over the nose of the tuyere had melted off the metal until the water in the tuyere prevented further melting. These tuyeres have a division in the annular water-space (see Fig. 2) to turn the current of water at the top, and the watersupply pipe is carried to within 1 inch of the nose. The constant supply of cold water in the nose of the tuyere kept it well cooled and preserved. But half an inch on the other side of the division the metal had melted off, as is shown by Fig. 1. There was no means of effecting a circulation at this point so long as the water was discharged from the butt of the tuyere. A pipe having been placed on the discharge-side of the division, the same as on the supply-side, in order to secure a circulation of the water at the nose on the discharge-side, it was found that the metal did not burn off. The nose being found to give out at the bottom, a division was placed in the annular water-space at the bottom, terminating 1 inch from the nose. This made a sharp current of circulation in the nose at the bottom, and prevented the burning of the metal there. A positive circulation at the nose, top and bottom, is a necessity with the present fast driving of furnaces, and prolongs the life of the tuyeres. The proper metallic composition of tuyeres is a question constantly agitated. A trial of ordinary yellow-metal* tuyeres was made 12 years ago. They did their work just as well

Jan 1, 1899

By Frank G. Snyder

The Precambrian of Midcontinent United States includes a metamorphic belt of probable Middle Precambrian age, a belt of Keweenawan volcanics and sediments, and widespread igneous activity that extended from Iowa to Texas. Most of the present structural configuration of the Midcontinent was developed by epeirogenic movements during the Paleozoic. The dominant elements are basins and arches. Three major metallogenic provinces occur in the Midcontinent. They include the Missouri Precambrian iron ores, the Lake Superior copper ores, and the Mississippi Valley lead-zincbarite- fluorite deposits. Several large iron deposits, occurring in rhyolite and andesite host rocks, are known. Both discordant massive bodies and replacement- type bodies occur. The iron deposits are believed to have been formed during the period of igneous activity. They are essentially the same age as the volcanics and older than the granites that intrude the volcanics. The Lake Superior copper ores include two established districts, the Keweenawan district and White Pine, and the copper-nickel deposits in the Duluth gabbro. The lead-zinc-barite-fluorite deposits include four major districts, Southeast Missouri, Upper Mississippi Valley, Tri-State, and Illinois-Kentucky, and at least eight minor districts. Ore may occur in stratiform deposits and in veins. The major districts all contain stratiform deposits, but several have produced appreciable quantities of vein ore. Only vein deposits are known in some of the smaller districts. The major features of all districts can be catalogued in terms of host rocks, structural patterns of districts, types of ore-bearing structures, and mineralogical characteristics. From these features, a Mississippi Valley type ore body, in its type area, can be defined.

Jan 1, 1968