Search Documents

By T. D. Yensen

I. INTRODUCTION IT is safe to say that of all the different materials that go to make up electrical machinery, iron is the most important. Upon its -magnetic and electrical quality depends not only the efficiency of the machine but, to a very large extent, the cost. Aside from the mechanical strength, there are three characteristics of iron that are of importance in this connection, viz., magnetic hysteresis, electrical resistance, and magnetic permeability. In the homopolar machine, where the magnetic flux is unidirectional, permeability is the only important factor, but in all other machines the flux is reversed in one or more parts and causes losses due to hysteresis and eddy currents. The eddy-current loss depends largely upon the electrical resistance of the iron; the higher the resistance the lower the loss, under otherwise identical conditions. These hysteresis and eddy-current losses cause heating of the machine, and as they depend upon the magnetic density in the iron, this density must be regulated so that the heating shall not be excessive. If the hysteresis and eddy-current Josses and the permeability of the magnetic circuit will permit an increase in the magnetic density, or, in other words, a decrease in the amount of iron, this in turn will mean a decrease in the amount of copper needed, with a consequent decrease in the copper loss. It is thus seen that; indirectly as well as directly, the above characteristics have an important bearing on both the efficiency and the cost of electrical machinery. In general, it may be said that iron for electrical machinery should have the following characteristics: (1) low hysteresis loss, (2) high electrical resistance, and (3) high permeability. These are the characteristics that investigators have been striving to attain since electrical machinery first came into use.

Jan 2, 1916

Frank Firmstone was born Aug. 29, 1846, at Glendon Iron Works, near Easton, Pa., the residence of his father, William Firmstone, one of the pioneers of the anthracite-iron business. After preliminary school education at Easton, Pa., he attended the Saunders Military Academy in Philadelphia and subsequently entered the Polytechnic College of Pennsylvania, where he was graduated as Mining Engineer in 1865, at the age of nineteen. In 1865 and 1866, he was employed in railroad surveying. In January, 1867, he became draftsman and in 1869, assistant manager of the Glendon Iron Works, of which his father was manager until his death in 1875, when the son practically succeeded to that position, becoming formally in January, 1877, and remaining until February, 1887, the manager of the works and business agent of the Glendon Iron Company. In February, 1889, he became President of the Cranberry Iron and Coal Company, and held that position until November, 1897. He was a director of the Longdale Iron Company, Longdale, Va., from its organizationin 1870 until its dissolution in 1911. With the termination of this official responsibility, Mr. Firmstone retired from active business, although he continued to maintain an intelligent interest, and to play a helpful part, in the scientific progress of the iron industry, in which he had been a leader.

Jan 1, 1920

By R. B. Walker, R. Palmer, L. C. Bryner

The purpose of this investigation was to further study some of the factors affecting the air oxidation of sulfide minerals. Data obtained from laboratory studies on the effect of temperature, concentration of iron salts, pH, and other catalysts on the biological and nonbiological oxidation of sulfide minerals are presented. The oxidation of copper sulfide minerals and subsequent leaching of the soluble copper has long been a profitable operation. The chief oxidizing agent is oxygen from the air. This reaction is influenced by a number of different factors such as temperature, light, hydrogen ion concentration, oxidizing agents, and various catalysts. Sullivan1 found that copper sulfide minerals are slowly oxidized by the air and that dilute sulfuric acid and iron (111) increased their solubility. At that time it was not known that bacteria were involved in the oxidation of the sulfide minerals. It has been shown that pyrite, molybdenite, free sulfur, and the copper sulfide minerals found in the waste rock dumps in Bingham Canyon, Utah, are largely oxidized by chemosynthetic autotrophic microorganisms found in the leaching streams.2-6 Similar organisms have been isolated in other mining areas7,8 and from the effluents from coal rnines.9 The following are some of the questions that have arisen regarding the mechanisms of the reactions involved in the leaching process. How dependent is the leaching operation upon the biological reactions? How does the temperature effect the biological and non-biological reactions? How does the concentration of iron (II) and (111) effect the rate of oxidation of copper (II) sulfide? Does the iron act as a catalyst? Does activated carbon act as a catalyst on the oxidation of sulfide minerals? What effect does the hydrogen ion concentration (pH) have on the above reactions? The purpose of this paper is to report the results of laboratory studies on these problems. EXPERIMENTAL The apparatus used in this investigation was an air lift percolator described in our earlier work.' The percolator consisted essentially of an air lift which enabled the leaching solution and microorganisms to pass freely through a suspension of mineral (substrate) in Ottawa sand. The air lift served the additional purpose of maintaining an ample concentration of oxygen and carbon dioxide in the nutrient (leaching) solution. (See Fig. 1.) The percolators were so constructed that they could be immersed in liquid constant temperature baths for temperature studies. The thermostats were controlled to +0.5°C. The reactions were all run in the dark. The percolators were charged with one to three g of mineral, dispersed in 100 g of Ottawa sand and 100 ml of nutrient or leaching solution. The sand was purified to remove traces of iron by digesting with concentrated hydrochloric acid and washng with distilled water until free from chloride. After drying, the sand was ready for use. The compressed air supply was regulated to 5 psi and bubbled through an aerator containing distilled water, which was maintained at the same temperature as the bath used. The air was filtered through cotton plugs to maintain sterile conditions. The tops of the

Jan 1, 1968

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who called at Institute headquarters during the period August 1, 1916 to September 10, 1916: C. L. Cantley, New Glasgow, N. S. H. M. La Follette, La Follette, Tenn. D. A. Cowell, Columbus, Ohio. Montrose L. Lee, Montevideo, Uruguay. Alexander Deussen, Houston, Texas. V. H. McNutt, Billings, Mont. Chas. E. Dutton, Goldfield, Nev. J. W. Maller, New York, N. Y. H. S. Emlaw, Grand Haven, Mich. Edwin W. Mills, Tul. Mi Chung, Chosen, J. M. Gillette, Swatsburg, N. Y. Korea. E. Gorilla, San Antonio, Texas. Francis R. Pine, Elizabeth N. J. Bertram Grant, Kingman, Arizona. Frank A. Ray, Columbus, Ohio. Ruger W. Hay, Bisbee, Arizona. John A. Rice, El Paso, Texas. C. F. Hendricks, Cobalt, Ontario. W. E. Rice, Ringwood Manor, N. J. Stanley C. Herold, San Jose, Cal. W. H. Staver, Lynchburg, Va. Lloyd Hoffman, Pottersville, N. J. Ralph H. Sweetser, Easton, Pa. Charles Hunter, London, England. Kirby Thomas, New York, N. Y. G. Jansen, Benkoelen, Sumatra. Henry Traphagen, Union Hill. T. H. Jenks, Oatman, Arizona. M. M. Valerius, Tulsa, Okla. Warren jenny, Chanaral, Chile. Wilfrid B. Wainewright, London, Eng. Walter A. Barrows, Jr., of Brainerd, Minn., has been elected president and general manager of the Thomas Iron Co., Easton, Pa., to succeed Ralph H. Sweetser, whose resignation of several months ago becomes

Jan 10, 1916

By Stewart, J. B.

THE property at which this work was done consists of a large deposit of potash salts occurring in massive beds of rock salt, overlain by 600 ft. of salt-impregnated shales and marls. It is in the Province of Cataluiia, Spain, about 45 miles from the railway station of Mauresa and about a mile south of Suria. In addition to sinking the shaft, the program of construction work laid out by the European owners (not Spaniards) included a single-track narrow-gage railroad from Mauresa to the mine; one large office building and several large shop buildings, all of brick and concrete with steel truss roofs; two extensive benches for the future recovery plant; and a large village of stone dwellings for employees. The pay-roll showed approximately 1200 to 1500 men employed. After two years' operation, ending early in the autumn of 1920, the shaft had been sunk 325 ft. and still had an equal distance to go to reach the potash; all tunnels for the railroad were done and the road-bed $0 per cent completed; only a little more than the foundations were completed for all the large buildings, and the excavations of the benches were about 75 per cent done-while only a fair start had been made upon the employees' village. This was the state of affairs when the European owners decided to offer this property under a one-year option to an American syndicate, providing that they agreed to carry on the entire building program and to sink the shaft as fast as was consistent with the quality of work which they demanded, for they wished the shaft to endure at least 200 years.

Jan 1, 1926

By R. J. Wasilewski

Electrical resistivity variation with temperature was measured on a series of alloys containting up to 33 at. pct of oxygen over the range 77° to1500°K. The resistivity behavior is highly anomalous and itzconsistent with simple metallic conduction. Both composition and temperature-depended resistivity singularities were observed. A few experiments carried out on Ti-N and Zr-O alloys indicate the presence of similar anomalies. These observations, together with the published data on effects of substi-tutional alloying on the resistiuity of titanium, suggest that the anomalies are inhevent in the electron structure of this group oj metals. The existence of two-band conduction, and a significant shift of bands relative to each other with temperature and/or the electron concentration are suggested. CONSIDERABLE advances have been made in recent years in the alloy theory of simple metals. Very little, however, is known about the bonding in transition metals and their alloys.&apos; Titanium, with its relatively few electrons, may be expected to show simpler alloying behavior than the more complex transition elements. Its alloys with the interstitial elements appear particularly attractive in an investigation of bonding characteristics because of a) the simple nature of the solute elements, b) the remarkable similarity between the equiatomic structures Tic, TiN, and TiO, and c) the extensive solid solubility ranges of oxygen and nitrogen in a titanium reported.2,3 The Ti-O system was chosen for the most extensive investigation because of the relative ease of preparation of suitable specimens. Since the main object of the work was to obtain data on the bonding and its changes on alloying, electron-sensitive properties were primarily investigated. The present work describes the investigation on the electrical resistivity-temperature-oxygen content relationships. A few experiments were also carried out at selected compositions in the Ti-N and Zr-O systems. EXPERIMENTAL Materials and Method. Polycrystalline specimens were prepared in the form of hairpin strips some 50 by 5 by 0.15 to 0.50 mm by direct metal-gas reaction. This was carried out by controlled oxidation followed by a homogenizing anneal at a higher temperature. All the test specimens were fully homogenized as judged from the uniform microstructure and microhardness. To avoid preferred orientation, each strip specimen was annealed in the ß range prior to the oxidation, this procedure assuring random orientation in the strip;4 hence any texture resulting from the oxidation reaction itself affected all the specimens to a similar extent. Titanium used was of high purity (66 DPN, 10 Kg load; major impurities 0,-43G ppm, N,-70 ppm, C-25 ppm, Fe-14G ppm). The solute content of the alloys was determined by weighing, after the reaction with a known amount of oxygen. The specimens in which the discrepancy between the volumetric and gravimetric measurements exceeded 2 pct (or 0.2 mg for the low oxygen alloys) were rejected. The mean between the two measurements was then taken as the oxygen content of the alloy. Check analyses showed no measurable nitrogen contamination. All oxygen contents are given in atomic percent. Zr-O alloys were prepared in identical manner from hafnium-free crystal bar metal, cold-rolled to strip 0.25 mm thick. Ti-N alloys required very long reaction times at the maximum temperature available (1250°C). In order, therefore, to detect possible oxygen contamination, duplicate specimens were reacted in every experimental run, and one of these was analyzed both for oxygen (vacuum fusion) and for nitrogen (Kjeldahl). Only the specimens in which the check analysis showed < 1000 ppm O were then used for resistivity investigation. Since only relatively high nitrogen alloys (7.1 at. pct; i.e., 2 wt pct N,) were investigated, this oxygen contamination was considered permissible. Dc resistance was measured by the four-probe method as previously described.= The temperature was determined with a calibrated thermocouple placed in the center of the specimen hairpin. The errors in the specimen resistance values thus obtained were estimated at 1 pct due almost exclusively to the finite thickness of the potential wires and the consequent uncertainty as regards the true resistance length of the specimen. For the calculation of the specific resistance, however, no dimensional measurements could be carried out on most of the

Jan 1, 1962

PRESIDENT AND DIRECTOR JOHN R. SUMAN HOUSTON, TEXAS PAST PRESIDENTS AND DIRECTORS DONALD B. GILLIES CLEVELAND, OHIO H.- G. MOULTON NEW YORK, N.Y. TREASURER AND DIRECTOR KARL -EILERS SEA CLIFF, N. Y. VICE-PRESIDENTS AND DIRECTORS W. B. HENRY HOUSTON, TEXAS HENRY KRUMB NEW YORK, N. Y. ERIE V. DAVELER , NEW YORK N Y W. M PEIRCE PALMERTON, PA. PAUL D. MERICA NEW YORK, N. Y. LEROY SALSICH DULUTH, MINN.

Jan 1, 1941

PRESIDENT AND DIRECTOR R. C. ALLEN . CLEVELAND, OHIO PAST PRESIDENTS AND DIRECTORS H. A. BUEHLER ROLLA, Mo. JOHN M. LOVEJOY NEW YORK, N. Y. VICE-PRESIDENT, TREASURER AND DIRECTOR KARL EILERS NEW YORK, N. Y. VICE-PRESIDENTS AND DIRECTORS HENRY KRUMB NEW YORK, N. Y. PAUL D. MERICA NEW YORK, N. Y. H. G. MOULTON NEW YORK, N. Y. HARVEY S. MUDD Los ANGELES, CALIF. WILFRED SYKES CHICAGO, ILL..

Jan 1, 1937

By Joseph E. Pogue

THERE are two methods employed in the development of oil pools. The older and dominant method is one in which the primary object is the protection of the underground deposit from drainage through competing wells, and considerations of efficiency of extraction and cost of production are subordinated thereto. The newer and less prevalent method is one in which maximum efficiency and minimum cost are the first objectives and developments to these ends may proceed undisturbed by the exigencies of competitive drainage. The second method has developed mainly in pools under single ownership and the term "unit operation" has come to be applied to this procedure. A single ownership, however, is not essential to the method, for unity of operation may be achieved by agreement under split ownership, or even by a concert of enlightened purpose. There are examples of unit operation where neither the ownership nor the management is a unit, but merely where unity of procedure has been attained, as is the case of the Yates pool. .Throughout this paper unit operation is used in its broad sense without implying sole ownership or single management, although unit operation is more conveniently attained where these conditions are present.

Jan 1, 1930

By A. W. Allen

The technological study of the treatment of gold and silver ores has been largely responsible for the phenomenal strides which have marked the progress in this branch of metallurgy during recent years. In no other application of science to industry is system more imperative at every stage; correct formulation of result is only second in importance to efficiency of operation. Progress in method, on the other hand, is mainly due to individua1 initiative aided by the work of technical journals and metallurgical societies. There still remains a field for profitable discussion, and it is my intention to deal with some inconsistencies of expression common to a number of writers on the subject; and also to draw attention to the false impressions created by a statement which may, possibly, be only unintentionally misleading. I also take the opportunity of tracing the source of both metallurgical and economic result; and would question the desirability of the methods usually employed in arriving at a final statement. In the first place, I wish to deal with the question of extraction. This term may mean anything or nothing, and it is often used to mislead. In a report of a mining engineer as to the result of operations subsequent to the remodeling of a treatment plant prominence was given to the statement that the extraction had amounted to 91 per cent. On examination it was found that only a small percentage of the so-called extraction was calculated on actual bullion return, a proportion being figured from the gold left in the zinc boxes, and not recovered. In addition to this, a proportion of the extraction was said to be due to gold in concentrate. As there was no conrcentrating apparatus on the property and as concentration did not form a part of the scheme of treatment the matter was investigated, with the result that the concentrate, of lower gold content that the original ore, was found to be the result of an inegcient pumping system which failed to provide for the whole of the battery product delivered to it. The balance was stacked and, although itself of no marketable value, the gold content was allowed to form a basis of extraction figures. The illustration may be extreme, but it will serve to show to what lengths an engineer may go in the mutilation of the most vital term in metallurgical technology.

Jan 1, 1915

THE first session of this meeting was held Tuesday evening, in the chamber of the Common Council, the President, Mr. David Thomas, in the chair. Mayor Carroll, of Troy, gave a cordial welcome to the Institute, which was responded to, on behalf of the Institute, by the first Vice-President, Mr. R. W. Raymond. The Council reported the names proposed for membership with recommendation for election. The following named gentlemen were duly elected: Anthony, J., . .Williamstown, Pa. Babcock, George, . . .Troy, N. Y. Blake, Theo. A., . . . . . . Sa n Francisco, Cal. Blossom, T. M., . . . . . . New Pork. Boalt, James A., . . .San Francisco, Cal. Bowman, Amos, . . . . San Francisco, Cal. Chester, Prof. A. H., . .Clinton, N. Y. Dewey, C., . Pittsfield, Mass. Dock, Gilliard, . Shamokin, Pa. Emerson, O. D., . .New York. Endres, John J., . .Pittsburgh, Pa. Firmstone, Frank, . Easton, Pa. Fowle, W. B., . Philadelphia, Pa. Frazier, Prof. B. W., . . .Bethlehem, Pa. Gardner, George A., . New Pork. Goodyear, Watson A., . .6an Francisco, C al. Griswold, Chester, . Troy, N. P. Griswold, J. A.,* . . .Troy, N. Y. Hague, J. D., . . .San Francisco, Cal. Hahn, 0. H., . .Eureka, Nev. Harkness, T. C., . . . . . . Wilkes-Barre, Pa Harris, Samuel, . . .Hudson, N . Y. Henry, &. T., . Oxford, N. J. Holley, A. L., . .Brooklyn, N. Y. Howe, H. W., . . .Troy, N. Y. Hunt, Dr. T. Sterry, . Boston, Mass. Jannet, J., . Troy, N. Y. Knapp, John A., . .New Pork. Laughlin, Henry A., . . .Pittsburgh, Pa.

By Robert M. McGeorge, Edward S. Frohling

Most mining engineers and metallurgists who get out of school usually wind up working for a large or medium-sized company and are seldom heard of again. The enterprising few who decide to go into business for themselves soon discover that while they can adequately tackle the various technical problems involved in developing a new ore body, they know little about putting together a feasibility study-and even less about financing their project. If you are in that predicament, you&apos;ll probably tend to view the financing problem as insurmountable, especially when the economy is in a slump, capital is scarce or seemingly non-existent, the equity market is in the doldrums, labor and equipment costs keep going up relentlessly-and, to make things worse, you must operate within the competitive context created by large mining firms that seem to have in abundance all the capital and managerial expertise you feel you lack. If it&apos;s any consolation, many potentially successful properties, whether owned by big companies or small firms like yours, never reach the production stage either because of illogical expenditures made in the early phases of development or because of inefficient management. And inefficient management is a common plague in big and small companies

Jan 9, 1975

By Vincent P. Gi. ccnella

GOLD was discovered in Gold Canyon on May 15, 1849. Following this discovery placer miners worked the gravels in the canyon for-ten years, finally discovering the outcrop of the Comstock lode at Gold Hill in May, 1859, and in Ophir ravine on June 12 of the same year. Before long large quantities of gold and silver, were taken from the lode and one of the West&apos;s most spectacular mining booms drew thousands of fortune seekers to Nevada. After a long period of production activity waned and in late years little mining was done. The recent reopening of the old mines and the discovery of ore in other parts of the vein, and in other veins of the district, has led to a revival of interest in the Comstock. Virginia City, Gold Hill, and Silver City, situated along the great vein system, are enjoying a period of prosperity and a large influx of people.

Jan 1, 1934

YEAR OF ELECTION 1913. FRANK DAWSON ADAMS, Montreal, Canada. 1933. KARL EIKERS New York, N. Y. 1922. FEDERICO GIOLITTI Torino, Italy. 1906. SIR ROBERT A. HADFIELD London, England. 1921. FRANK WILLIAM HARBORD London, England. 1917. HERBERT HOOVER Washington, D. C. 1941. DANIEL COWAN JACKLING San Francisco, Calif. 1939. HENRY KRUMB New York, N. Y. 1921. C. McDERMID London, England. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1935. ROBERT PEELE New York, N. Y. 1938. A.M. PORTEVIN Paris France 1937. JOHN V.W. REYNDERS, New York, N. Y. 1937. GEORGE S. RICE Washington, D. C. 1911. ROBERT H. RICHARDS Cambridge, Mass. 1934. T.A. RICKARD Victoria, B.C., Canada

Jan 1, 1941

By C. A. Schempp

STUDY of the adaptability of Tintic Standard ores to concentration dates back to somewhat before January, 1921, when the chloridizing mill at Harold, Utah, was put into operation. The operation of this mill has been fully covered in the TRANSACTIONS (Vol. 73). The process consisted essentially of a chloridizing roast followed by a percolating leach with a nearly saturated solution of common salt, acidified with sulfuric acid; precipitation of silver on sponge copper, and of copper and lead on tin-plate cuttings. This mill was built to treat the low grade siliceous ores having an average content of

Jan 1, 1933

By Guillermo Mariaca, Jorge Muñoz Reyer

As far as technology is concerned there has been no development in Bolivia during the year 1936, because the country, just emerging from the war with Paraguay, is only beginning to rebuild its economic foundations. Great steps, however, are being taken in order to secure a rapid and sound development of its oil resources, as follows: 1. The new Petroleum Law, which contemplates the problem of proration and conservation of natural resources, prohibiting the wasteful use of gas, and regulating the number of wells, their spacing and the permissible output per well, for each particular pool according to the conditions prevailing therein. 2. The creation of an official entity with the object of developing and exploiting a large petroliferous area. This entity has been called Yacimientos Petroliferos Fiscales Bolivianos (Y.P.F.B.), and the region assigned to it is all the sub-andean zone, which is approximately one hundred miles wide and borders the eastern part of the Oriental Andean range, from Argentine to Peru. It is said that drilling will be started immediately in various localities. At the present time a wide geological survey of part of the area is being made in order to find out which regions offer the best possibilities of commercial development. Y.P.F.B. has been authorized by the Government to draw up contracts with private companies for the exploitation of limited zones. Production The only company that has been producing in the country in 1936 is the Standard Oil Company of Bolivia, and only from two of its fields: Camiri and Sanandita. New wells were not drilled. During the first nine months of the year 12,762,958 liters (80,275 bbl.) was produced, 34,985 bbl. from the Camiri field and 45,290 bbl. from the Sanandita field. Reports for October, November and December are not yet available. The total for the year 1935 was 25,978,737 liters (163,388 bbl.).

Jan 1, 1937

By Werner Joseph, Richard R. Knobler

When the first batch of refined copper ingots was cast at Mantos Blancos in January 1961, eight years of exploration, development and metallurgical pioneering by Mauricio Hochschild & Co. had come to a successful conclusion. This Chilean copper deposit, located in the Atacama Desert 30 miles from Antofagasta, is now producing approximately 20,000 tons of copper per year. The Mantos Blancos deposit has been known since 1912 and various attempts had been made to work the high-grade zones before the present operation was started. The major drawback of the ore to any previous development was its chloride content which varies between 0.4% and 1.5% C1. Although the chloride ruled out the conventional leaching-electrolysis scheme, it did lend itself to the process of precipitating the copper as cuprous chloride.

Jan 1, 1962

TWO American students entered the École des Mines in 1856, Joseph Lesley of Philadelphia and Thomas Egleston of New York. Lesley remained there only one year, but Egleston completed the whole curriculum and received, in 1860, the certificate given to foreign students in lieu of the official appointment and degree awarded French students. Returning home he received, in 1861, an appointment by Secretary Henry of the Smithsonian Institution to sort, label, and arrange the collections of mineralogical and geological specimens which had been brought to Washington by the various government exploring expeditions in the West. Thomas Egleston, born in New York City on Dec. 9, 1832, was the son of Thomas Jefferson Egleston, who came to New York from Massachusetts some time before 1829. The first American ancestor of the family had settled near Dorchester in 1630. T. J. Egleston and Joseph Battell established an iron-merchandizing business* at 166 South St., New York, which prospered exceedingly; so much so that when Thomas J. Egleston died, July. 12, 1861, his estate had a book value of over $500,000. Since an older brother was expected eventually to take over this business, Thomas, who had a liking for science, went to Yale, where he completed the regular four-year course in 1854, and then remained another year for advanced work in chemistry under Silliman. One biographer says he went to Europe, early in 1856, on account of his health. It was the custom at that time for wealthy young men to make a tour of Europe after completing their academic education. Whatever the precise reason, he began scientific work at the Jardin des Plantes in Paris but soon trans-

Jan 1, 1941

H. M. HOWE, Bedford Hills, N. Y.-One wonders, whether it might not be well to check, by a rather simple and direct way, the inferences that would be drawn from this investigation. Suppose we quench, in these various liquids cylinders of steel, selecting material that is not likely to split in hardening, and then examine their cross-sections micro-scopically. If the cylinder is of any size, you will find a series of concentric bands, a very hard band, a softer band, and a hard band-but it seems that here would be a way of checking the inferences from the cooling curves by comparing these waves of hardness obtained in similar speci-mens quenched in different liquids. One would think that there would be great promise in that way. One&apos;s first thought is to quench similar pieces of steel, similarly heated, in different liquids and determine their hardness. I suppose many of us have tried that. We then meet the-difficulty that it is not the most rapid cooling that gives the greatest hardness. There is an intermediate rate of cooling that gives maximum hardness so that you can not by any simple method as that check this cooling method. But it seems possible

Jan 12, 1919

By Lawrence P. Bonicatto

The steel industry&apos;s increased demand for higher grade pellets has caused the pellet producers to investigate methods of upgrading their product and the Hanna Mining Co.&apos;s Groveland plant on the Upper Peninsula of Michigan is no exception. The low grade iron deposit is a complex mixture of magnetite and hematite with chert, quartz, jasper and various iron silicates.1 Beneficiation is by Humphrey spirals and anionic flotation of the iron minerals.2 Flotation of the spiral tailings makes up about 75% of the concentrate, while a minor amount of concentrate (less than 3%) is produced in magnetic circuits. The concentrate is pelletized at the rate of 1.6 million tpy. The initial concentrating facilities were constructed in 1958 and the concentrate was marketed as sinter feed until a pelletizing plant was added early in 1963. Grade improvement soon became a high priority research project, and several methods of concentration were investigated.

Jan 3, 1968