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By Frank T. Sisco

SHORTAGES of metals and minerals and substitution of less critical materials for those in which a virtual famine exists received detailed and frank discussion at a recent conference in Washington called by Robert E. McConnell, director of the Conservation Section, Office of Production Management. Representatives of the large engineering societies in the United States and O.P.M. department heads participated in the discussion. To open the session Mr. McConnell called upon Zay Jeffries, chairman of the O.P.M. Advisory Committee on Metal Conservation and Substitution, to summarize the present situation. Dr. Jeffries touched briefly on the status of metal shortages, which has already received considerable attention in the popular press, and said that much of the present difficulty was caused by the too-hasty substitution-without sufficient con¬sideration of the immediate conse¬quences-of metals having ordinarily a small yearly consumption, for those having a much larger annual consumption. As a result, all the alloying metals used in alloy-steel manufacture have become scarce, with the exception of molybdenum; further¬more, despite a reserve of 11,000 tons of molybdenum in this country and despite a normal consumption of only about 3500 tons and a prospective annual production rate of 21,000 tons by October, a shortage of molybdenum is possible before this war is over.

Jan 1, 1941

By C. E. Berry

Natural stone or manufactured porcelain pebbles are used as the grinding elements in pebble mills and the mills are lined with stone or porcelain blocks. Steel balls usually form the grinding medium in ball mills, and the mills may be lined with steel. Pebble mills are used to avoid contamination by metal of the material being ground, to avoid rapid wear due to corrosion, and for other specialized reasons. Belgian silex (silica) blocks formerly were used widely for lining pebble mills, because of their good resistance to wear, light color, and low cost, but the importation of these blocks was suspended early in the war. The stocks of Belgian silex diminished so rapidly that it was found desirable to compare the properties of a number of domestic substitutes for use in critical operations. Accordingly, a study was made to determine the best substitutes for fine grinding of white pigment and for certain heavy-chemical process work such as the disintegration of phosphate rock in weak phosphoric acid solution. A comprehensive survey of substitute lining materials was not contemplated. It was stipulated at the beginning of the investigation that only materials on the market, available in large quantities, would be tested and that these should be reasonable substitutes from a wear-resistance viewpoint as determined from known physical characteristics. Marble and limestone, for example, could be eliminated immediately. Quartzite, granite and porcelain were selected as likely substitutes for Belgian silex and were subjected to quality tests. Materials Tested 1. Belgian Si1ex.—Sample blocks of a standard grade were taken from crates in which they had been imported. The stone was light gray in color and contained inclusions of small clusters of quartz crystals as well as light colored portions that might be calcite. This was a siliceous rock which appeared to be of igneous origin. 2. Quartzite.—Samples of quartzite were obtained from a quarry in Minnesota. The blocks exhibited a crystalline fracture. The stone was pink in color and composed of fine quartz crystals bound together with a siliceous cement. 3. Granite A was a fine-grained granite quarried in South Carolina. 4. Granite B was coarse-grained granite quarried in South Carolina. 5. Granite C was a coarse-grained granite quarried in North Carolina. 6. Porcelain A.—Sample blocks of the pebble-mill lining material were obtained direct from the manufacturer. It was white in color and of lower specific gravity than the natural materials. It did not have a crystalline structure. 7. Porcelain B.—Sample pebble-mill lining blocks of the porcelain were received direct from the manufacturer. It was white

Jan 1, 1947

By C. E. Berry

Natural stone or manufactured porcelain pebbles are used as the grinding elements in pebble mills and the mills are lined with stone or porcelain blocks. Steel balls usually form the grinding medium in ball mills, and the mills may be lined with steel. Pebble mills are used to avoid contamination by metal of the material being ground, to avoid rapid wear due to corrosion, and for other specialized reasons. Belgian silex (silica) blocks formerly were used widely for lining pebble mills, because of their good resistance to wear, light color, and low cost, but the importation of these blocks was suspended early in the war. The stocks of Belgian silex diminished so rapidly that it was found desirable to compare the properties of a number of domestic substitutes for use in critical operations. Accordingly, a study was made to determine the best substitutes for fine grinding of white pigment and for certain heavy-chemical process work such as the disintegration of phosphate rock in weak phosphoric acid solution. A comprehensive survey of substitute lining materials was not contemplated. It was stipulated at the beginning of the investigation that only materials on the market, available in large quantities, would be tested and that these should be reasonable substitutes from a wear-resistance viewpoint as determined from known physical characteristics. Marble and limestone, for example, could be eliminated immediately. Quartzite, granite and porcelain were selected as likely substitutes for Belgian silex and were subjected to quality tests. Materials Tested 1. Belgian Si1ex.—Sample blocks of a standard grade were taken from crates in which they had been imported. The stone was light gray in color and contained inclusions of small clusters of quartz crystals as well as light colored portions that might be calcite. This was a siliceous rock which appeared to be of igneous origin. 2. Quartzite.—Samples of quartzite were obtained from a quarry in Minnesota. The blocks exhibited a crystalline fracture. The stone was pink in color and composed of fine quartz crystals bound together with a siliceous cement. 3. Granite A was a fine-grained granite quarried in South Carolina. 4. Granite B was coarse-grained granite quarried in South Carolina. 5. Granite C was a coarse-grained granite quarried in North Carolina. 6. Porcelain A.—Sample blocks of the pebble-mill lining material were obtained direct from the manufacturer. It was white in color and of lower specific gravity than the natural materials. It did not have a crystalline structure. 7. Porcelain B.—Sample pebble-mill lining blocks of the porcelain were received direct from the manufacturer. It was white

Jan 1, 1947

By Frank E. Caropreso, William P. Badger

A hydrogen peroxide precipitate process has been adopted by Atlas Minerals for the recovery of uranium oxides from sodium chloride strip solutions. Adoption of the process was based on laboratory and plant tests comparing hydrogen peroxide with other precipitants. Plant operation has demonstrated that the hydrogen peroxide process consistently yields uranium concentrates of high purity and barrens of low uranium content. Increased U3O8 concentration in the product, reduced levels of impurities which incur penalties, and higher product density have produced economic advantages.

Jan 1, 1974

By Herbert Haas

The following notes describe a laboratory for metallurgical chemistry and technical analysis which I built late in 1903, while engaged, as constructing engineer, in erecting a pyrite smelter at the Afterthought mine, Ingot, Shasta county, California. This design partly supplements the paper of Mr. C. H. White, which was presented at the Atlantic City Meeting of the Institute in February, 1904.' The work of a chemist at a busy smelting-plant differs radically from the work of a student, who takes all possible care to have his analysis exact within hundredths of a per cent., and has plenty of time to devote to the operation. The works-chemist, having the shortest time in which to make his determinations, should have a laboratory arranged as conveniently as possible to save time in carrying out his work. By a conveniently-arranged laboratory, I do not mean an elaborately furnished one; but rooms suitably fitted up and supplied with the necessary apparatus to do the work expected from the chemist within the requirements of technical analyses. It is not uncommon at large smelters to have the night ae-sayer prepare 30 or more samples for titration, in time for the

Jan 1, 1905

By Öner Yücel, M. Zeki Dogan, A. Metin Ger

Technical and financial feasibility studies conducted at the Middle East Technical University, in Ankara, Turkey, have revealed that a 400 km long prospective slurry pipeline between Hasançelebi and Iskenderun could efficiently and economically transport iron concentrates, with a size of 55%-325 mesh and of amounts varying between 0.25 and 8.0 million tonslyear. Particularly for annual throughputs above 500,000 tons, favorable results have been obtained regarding the processing of the ore, the applicability, the transport cost, and the foreign ex- change currency savings.

Jan 1, 1980

By R. Roberge, H. Herman

Jan 1, 1969

For the year ending February, 1917 PRESIDENT L. D. RICKETTS,1 NEW YORK, N. Y PAST PRESIDENTS BENJAMIN B. THAYER 1 NEW YORK, N. Y. WILLIAM L. SAUNDERS,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 10, 1916

Discussion of the paper of F. C. LANGENBERG and R. G. WEBBER, presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 291 to 300. HENRY M. HOWE, Bedford Hills, N. Y.-The results here given are of great interest and are welcome as forming another rivet to increase the stability of our present theories of the constitution and properties of steel. The important discovery is that the hysteresis increases with the fineness of the structure, that is to say with the extent of contact between the particles of ferrite and cementite. All of the specimens except No. 4 consist of ferrite and cementite of different degrees of intimacy of admixture. If hysteresis represents something akin to surface friction, which retards the rotation of the ferrite on the application and release of the magnetizing force, then it is only natural that it should increase as it does with the intimacy of admixture, because it is at the surface of contact of a given particle of ferrite with the neighboring particles of cementite that this friction is to be expected, and of course the extent of surface must in¬crease with the intimacy of admixture. The somewhat greater hardness of specimen 4 than of the others may perhaps he referred to the principle discussed in my paper, Why Does Lag Increase with the Temperature from Which Cooling Starts?' The furnace-cooled specimens were cooled so slowly that the influence of the initial temperature of heating is effaced. But in the air-cooled specimens we have the suggestion that the high temperature, 1,000°, from which the cooling of No. 4 started has prevented the completion of the transformation, with the result that the metal is slightly harder than any of the others. The difference is not to be explained by difference in the fineness of structure, because the whole range of fineness from No. 1 to No. 6 is accompanied by no change in hardness, the only change being an appreciable increase of hardness following the air cooling from 1,000°.

Jan 5, 1915

BENEFICIATION AND CONCEN'TRATION; FROTH FLOTATION U.S. 4,069,144 - In the froth flotation beneficiation of phosphate rock using at least an acid flotation step and an amine flotation step, the crude ore is dried either during transport or storage or by air circulation immediately prior to classification, and the dried ore mixed with water and classified prior to flotation The preliminary drying substantially eliminates the usual problems with clay slimes G. C. Johnson and A. E. Schweizer, assigned to Mobil Oil Corp. Jan 17. 1978. 4 pp (209- 11) . Filed 1 1-19-75 (633,535).

Jan 1, 1979

For the year ending February, 1917 PRESIDENT L. D. RICKETTS,1. NEW YORK, N. Y. PAST PRESIDENTS BENJAMIN B. THAYER,1 NEW YORK, N. Y. WILLIAM L. SAUNDERS,2 : NEW YORK, N.Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 . NEW YORK, N.Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK,. N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N.Y.

Jan 1, 1917

By WALTER B. JONES

PIG iron was first produced in Alabama in 1818 from limonite or brown ore and since then much of this ore has come from the so-called mineral district of northern Alabama, especially along the Cretaceous-Paleozoic contact. For many years the Russellville district in Franklin County, where the first blast furnace was erected, produced more than 100,000 tons of brown ore annually. Limonite has been reported at many places in the Coastal Plain region, where the formations are of Mesozoic and Cenozoic age, but these scattered deposits were never considered to be of much commercial importance. However, in the last three years a considerable quantity of this ore has been scraped up and shipped, particularly from the city of Greenville in Butler County.

Jan 1, 1938

By J. H. Scaff, H. C. Theurer, E. E. Schumacher

The microwave region of the radio spectrum was effectively utilized in radar designs during the recent war and it has become of increasing interest in the field of communications. Work in this field has led to an important use for silicon—that of the point contact rectifiers†1 in the frequency converter of microwave (radar or radio) receivers—and has stimulated considerable interest in the electrical properties and preparation of silicon and its alloys. Silicon is an electronic semiconductor. Its conductivity at room temperature results principally from the presence of certain impurities. While for metals an increase in impurity content increases the resistivity, for semiconductors such as silicon the opposite occurs and, in general, the addition of impurities lowers the resistivity. Silicon materials may be classified into one of two groups depending upon the manner in which the impurities contribute to electrical properties. These have been termed for convenience p-type or n-type. P-type silicon develops a very large positive thermal emf against metals, has a Hall coefficient of positive sign and a low resistance direction in point contact rectification with the silicon positive with respect to the point. N-type silicon, on the other hand, develops a negative thermal emf against metals, has a Hall coefficient of negative sign and a low resistance direction in rectification with the silicon negative with respect to the point. Impurities which produce n-type silicon are called donors inasmuch as these elements contribute to electrical conductivity by donating electrons to an unfilled energy band in the silicon. On the other hand, elements which produce p-type silicon are known as acceptors as these impurities contribute to the electrical conductivity by accepting electrons from a filled energy band permitting what is known as conductivity by "holes" in which the sign of the carriers appears to be positive. A general treatment of the mechanism of conduction in semiconductors from the viewpoint of modern band theory has been given recently by Pearson,2 by Becker, Green and Pearson,3 and by Torrey and Whitmer.4 In this investigation boron and aluminum have been found to be acceptors, and phosphorus, arsenic, and antimony to be donors in silicon. Data on the effect of boron and phosphorus on the electrical properties, when present singly and in combination, have been acquired. These data are discussed in the present paper. Raw Materials Used and Methods for Adding Seeond Constituents Silicon from two sources was used in this work and these will be referred to as A and B respectively. Silicon A is a material of high purity supplied by the Electro Metallurgical Co. It is prepared by chemical purification of "commercial" silicon obtained from the arc furnace reduction of SiO2. It contains 99.8 pct silicon, minimum, with small amounts of calcium, iron, aluminum, boron, and phosphorus as the principal impurities. This material was extensively employed in these studies as well as in the commercial preparation of rectifier materials. Silicon B is a material of high purity from the du-Pont Co. It is prepared by a pyrolytic reduction of Sicl4 and is free of analytically detectable amounts of boron and phosphorus. Its use permitted study of the effect of boron and phosphorus individually on the properties. This material contains, however, spec-troscopic traees of a number of metals, some of which affect electrical and rectification properties. Typical analyses for the two grades of silicon are given in Table 1. To make controlled additions of boron to the charge it was necessary to employ a low boron content master alloy since the quantity of boron to be added was usually only a few thousandths of one percent. The alloy containing nominally one percent boron was prepared by melting chemically pure boron with silicon A using the melting techniques for 320 g silicon

Jan 1, 1950

In accordance with the provision of the Constitution, notice is here given to all Members, Associates, and Junior Members, that the clues of the year 1918 will be payable on Jan. 1. 191.8, at the office of the Secretary. The dues for Members and Associates are $12 per year and the sum of 83 additional is asked of those Members and Associates who desire to have the three volumes bound in the Institute's standard half morocco binding. The dues of Junior Members are $5 per year.

Jan 12, 1917

With a mine output as high as 5000 tpd and mill capacity of 7000 tpd, the uranium mining and milling complex owned and operated by Kerr-McGee Nuclear Corp. in the Ambrosia Lake area is the largest in the U.S. and is likely to remain so for some time. Next year, Kerr- McGee expects to have in production another mine in Section 19 of the Ambrosia area-and will begin ore production in 1976 at its new $15-million mine at Church Rock, located northeast of Gallup, N. M., where the company has already completed the shaft work and is in the early stages of project development. Ore from Church Rock will be transported to the company's facilities at Ambrosia Lake for processing. Kerr-McGee's existing eight mines in Ambrosia Lake go to depths of about 800 to 1500 ft to tap the various horizons of uranium-bearing sands in the Westwater Canyon of the Morrison formation.

Jan 8, 1974

By Donald W. Mitchell

MINE operators have a choice of several classifications of mechanical loaders. Within each classification there are many types and makes available. Table I lists loaders on which manufacturing data as to operating characteristics are available. This paper discusses the conditions met in a mine as they affect these characteristics. It is assumed that management will provide satisfactory engineering, supervision, power, maintenance, loader service within a concentration of workings, and a balanced working cycle served by balanced production equipment. These are factors which affect the optimum operational efficiency of a loader. The conditions which determine loader choice are:

Jan 5, 1951

By Walter O. Roberts

A TOTAL eclipse of the sun is a brief, exciting spectacle witnessed by most men but once or twice during a lifetime. But to an astronomer an eclipse of the sun is an event of utmost scientific importance. For then, certain phenomena of the sun normally obscured by the brilliant glare of sunlight become spectacularly visible. For over seventy years prior to 1930 astronomers vainly attempted to discover a means of observing all of these eclipse features of the sun without a natural eclipse. But in 1930, through the genius of the French scientist, Bernard Lyot, astronomers met final success. Dr. Lyot invented a new kind of telescope known as a coronagraph, which made possible photography of all of the eclipse features of the sun. In 1940 Harvard University completed final testing of its Lyot-type coronagraph. the only one in the Western Hemisphere, and shipped it to Climax, where Donald H. Menzel, of Harvard College Observatory, supervised its establishment on the southeastern edge of the mining community of the Climax Molybdenum Co., with whose help and advice the modern residence and telescope dome of the observatory were constructed. Ever since that summer the station has been operated by me, first as a graduate student, and now as a staff member of Harvard College Observatory.

Jan 1, 1946

By A. A. Gustafson

The Freeport Sulphur Co. built a portable crusher in 1944 that solved a problem that none of the crusher manufacturing companies contacted were able to do. Two of these crushers have now been in service for 6 years, giving satisfactory service in handling a million tons per year, and having a capacity of over 2000 long tons per 8-hr shift. These machines reduce ton size blocks of sulphur to 12 in. and also feed the conveyor system at the rate of 350 long tons per hr per machine.

Jan 10, 1950

By A. M. Gaudin, J. G. Morrow

FLOTATION requires the existence of a definite contact angle. This contact angle, the surface tension of the solution, and adsorption at the solid-fluid interface are quantitatively related. Adsorption of dodecylammonium acetate on hematite was measured for a wide range of concentrations of reagent in solution. Similar measurements for quartz have already been made. Contact angle measurements were then made on polished surfaces of hematite and of quartz immersed in aqueous dodecylammonium acetate solutions, and a functional relationship was sought between adsorption density at the mineral-solution interface and the contact angle. Finally, the surface tension of the aqueous amine acetate solutions was measured. These data were combined to give an evaluation of the work of adhesion for the three-phase system. Specular hematite was crushed and then ground dry in a laboratory porcelain mill, with flint pebbles, to pass a 200-mesh screen. The ground product was sized in a Haultain infrasizer, and one of the granular sizes (cone No. 3) was used in all adsorption tests. A hand magnet was used to remove magnetite and abraded iron. Quartz was removed in a Frantz isodynamic magnetic separator. The purified hematite was leached in aqua regia, washed with distilled water until the washings appeared free of electrolyte by conductance measurement, dried in a low-temperature oven, and stored in a pyrex container. The specific surface of the closely sized hematite was determined by the krypton gas adsorption method.' Three measurements gave an average value of 1350 sq cm per g. Chemical analysis showed Fe -69.37 pct, insol = 0.72 pct. The quartz used in the flotation tests had been prepared by Chang" for an earlier investigation. Demineralized distilled water was used for all test solutions. Dissolved salt content was of the order of 0.03 ppm, expressed in terms of sodium chloride, as estimated from conductance measurements. Dodecylammonium acetate was obtained from Armour & CO. in two forms, the unmarked compound and a preparation marked by carbon 14 in the hydrocarbon chain of the aminium ion. Specific activity of the active salt was 0.134 millicurie per g. The important physico-chemical constants for the primary amine salt have been reviewed by de Bruyn. The calculated effect of hydrolysis of amine salt on pH of aqueous solutions and the effect of pH on the distribution ratio of the alkylammonium ion to free amine are of particular interest. All other chemicals used in this investigation were of analytical reagent grade. A column method' was used for adsorption work. Attainment of equilibrium distribution in the adsorption column depends on the solid-solution contact time, hence upon the volume of solution passed. It was assumed that contact time required for equilibrium would be a maximum for the lowest reagent concentrations. On this premise it was demonstrated experimentally that the passage of 500 ml of solution through the mineral bed was adequate. An aliquot (1 to 5 cc) of the solution to be analyzed was transferred to a small pyrex cup and allowed to evaporate to dryness at room temperature; 4 or 5 mg of unmarked amine acetate were added to the dried sample and the cup and its contents were transferred to the combustion system for analysis. Evaporation at room temperature must be emphasized, as even slightly elevated temperatures result in loss of reagent. A laboratory model G Beckman pH meter equipped with a glass electrode was used to measure pH of amine acetate solutions. The technique of internal gas counting of radioactive carbon dioxide in a Geiger-Muller counter was used. Developed originally by Brown and Miller,- his method was adapted to the analysis of carbon-14 marked flotation reagents by Chang, de Bruyn, and Bloecher. nalytica1 method and procedures have been described in detail by Bloecher.' Contact angles were measured by the captive-bubble technique." The mineral specimens were carefully selected to avoid cracks and inclusions of other minerals. All specimens were mounted in plastic and polished to produce a smooth surface. The final polishing and contact-angle measuring

Jan 1, 1955

For the year ending February, 1917 PRESIDENT L. D. RICKETTS,1 NEW YORK, N. Y. PAST PRESIDENTS BENJAMIN B. THAYER,1 NEW YORK, N. Y. WILLIAM L. SAUNDERS,2 NEW YORK, N. Y FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON, NEW YORK, N. Y.

Jan 12, 1916