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By G. D. Oxx, L. F. Coffin

The concept of using a phase that is liquid at service temperatures as a component of coatings for refractory metals has been described. The liquid, an alloy of gold and silicon, is retained on a molybdemum surface by a capillary system made of molybdenum disilicide. The coating has the advantage of good thermal shock and has a self-henling chracteristic. In order for highly stressed structures to exceed a service temperature of 2000°F, it has become apparent that a development that does not depend on the traditional iron, cobalt, or nickel-base alloy is needed. Alloys of the refractory metals, i.e., molybdenum, tungsten, tantalum. niobium (colum-bium), and rhenium are potentially useful at extremely high temperatures that more conventional alloys would never be expected to achieve. A new alloy of molybdenum has become available that has a 100-hr rupture strength of 35,000 psi at 2200°F.1 As a result of this work, it may be assumed that a material with adequate mechanical properties at 2200?F is now available. Unfortunately, this alloy and all other known alloys of the refractory metals suffer from not being; serviceable in an oxidizing atmosphere for a very long time. In order to permit general use of refractory metals at high temperatures, it is necessary to prevent destructive oxidation by appropriate alloying or by protective coatings. The liquid phase coating reported here is representative of a concept for the protection of metals that permits higher service temperatures and introduces a new group of materials for selection as coatings. Coating Requirements—Service conditions that represent potential applications for refractory metals vary considerably: however, it is possible to consider two conditions that are usually present. The refractory metal1 component must be heated to the service temperature at least once and usually frequently. When a solid coating is used, usually the coating and basis metal do not have the same coefficient of expansion. This difference causes thermal stress in the coating that is aggravated by rapid heating and cooling and eventually causes coating failure. The second consideration is the probability that there will be damage to the coating by some environmental condition. In jet engines, for example, it is expected that large particles, stones, metal parts, and so forth, will strike a bucket at high speed and cut a hole in the coating. In addition to the above considerations, the coating must also have other fundamental properties. Obviously, it must be oxidation resistant. In addi- tion, it must prevent permeation of oxygen and subsequent oxidation of the basis metal at the interface. Also, diffusion of the basis metal to the outside surface and subsequent oxidation there must be prevented. Finally, the coating must not react with the basis metal to form a weak bond at the interface. It should be noted that the coating need not support a load: it must only remain intact. Liquid Phase Coating Design Factors—In the use of a liquid as a principal coating constituent, it would be expected that the two service conditions mentioned above would be satisfied. A liquid would flow under the influence of the thermal strain developed by coating-basis metal expansion mismatch such that failure from this source would not be expected to occur. It is also probable that the ability of a liquid to flow would provide a self-healing effect. Thus, damage caused by particles in the atmosphere would be repaired. A third advantage is evident in that vapor pressure rather than melting point limits the service temperature. This latter advantage permits use of low melting but oxidation resistant metals such as gold or copper that would be quite useless if the solid state was required. A low viscosity liquid alone. however, is a totally unsuitable coating because it will simply flow off a component, particularly under the influence of a high acceleration field. A method of preventing liquid loss must be devised. In this case, it is desired that the liquid have a low viscosity so that it may easily flow into flaws; thus, raising the viscosity is not a satisfactory solution. One other inherent difficulty is caused by the high mobility of atoms in the liquid state as compared to the solid state. Because of this mobility, it would be expected that gases would diffuse more rapidly through a liquid. It is also probable that the solubility of oxygen in the liquid would be comparatively high. These factors would tend toward rapid permeation of oxygen and oxidation of the substrate. It is most reasonable that this problem could be solved by incorporating a solid phase, which is impermeable to gases, as a component of the coating. To overcome the tendency of a liquid to flow easily, it is possible to use surface tension to advantage. If the surface were made up of a large number of capillary tubes of sufficiently small diameter, then surface tension would hold the liquid even against the acceleration of a centrifugal field.

Jan 1, 1961

By C. F. Jenkins, G. V. Smith

Serrated plastic flow in stable austenitic alloys based on Fe/Ni has been shown to be related to the presence of carbon and/or chromium in the systems. Strength peaks and plateaus in the serrated-flow temperature region for a commercial alloy correlate with an increased dislocation content, arising, presumably, from enhanced multiplication as a result of a strong interaction between dislocations and solute atoms. The data generally support a mechanism controlled by migration of vacancies, with the energy for vacancy motion being modified by the presence of chromium. Chromium atom -dislocation interaction is responsible for effects above 500°C, whereas the defect interacting with dislocations between 200" and 500°C is suggested to be a carbon-vacancy Pair. ThE phenomenon of jerky flow, serrated flow, or the Portevin-le Chatelier (P-C) effect in austenitic stainless steels is usually attributed to substitutional at1,2 mospheres1,2 or to precipitates&apos;-4 which form at dislocations during plastic deformation. On the other hand, evidence exists which supports a direct inter-stitial-dislocation interaction mechanism for serrated flow in fcc Ni-C,5,6 Ni-H7-9 and in nickel-austenites containing carbon." The present work consists in a study of serrated plastic flow in stable austenitic al-loys. The effects of carbon and of chromium were investigated separately, and a commercial stainless steel with different levels of interstitial impurity concentration was studied in an attempt to delineate the combined effects of the alloying elements. EXPERIMENTAL TECHNIQUES a) Materials and Fabrication. A commercial AISI 330 stainless steel and several specially prepared aus-tenitic alloys have been studied. The experimental alloys were prepared by arc melting the constituents under purified argon. Analyses of the materials are given in Table I. The commercial alloy was obtained as 5/8 in. bar stock and rolled to 0.092 in. sq, with several intermediate anneals. At this stage some of the material was annealed in Pd-purified hydrogen at 1100°C to establish different levels of interstitial content. All other heat treatments were in vacuum (10-5 torr). The "pure" alloy ingots were swaged to 0.120-in. rod and annealed in Pd-purified hydrogen at 1100°C. The analyses for these conditions are also contained in Table I. Following the above treatment, the final wire sizes Table I. Chemical Analyses of Test Materials Hrin Hydrogen at Cr, Ni, Alloy 1lOO°C wt pct wt pct C, ppm* N, ppm* Type 330 As-received 14.78 33.25 430 300 Type 330 64 14.78 33.25 40 50 Type 330 200 14.78 33.25 27 21 Fe/35 Ni 72 - 35.10 <10 62 Fe/35 Ni 200 35.10 <I0 44 Fe/35 Nil15 Cr 72 14.95 34.94 <I0 61 Fe/35 Ni/15Cr 200 14.95 34.94 <10 45 Fe/35 Ni/C $ 35.OM 380 *Sensitivity: N t 5 ppm Ct10ppm. f Nominal Ni content. % A master NiC alloy was used in preparation of this material; courtesy of D.E. Sonon. were obtained by either swaging or cold drawing. The test results did not vary with these techniques. b) Specimen Preparation. Two sizes of specimen and two gripping systems were used. i) 0.070-in. wire with a chemically milled gage section: 0.75 in. long, 0.060 in. in diam. These were fastened into grips containing tapped grooves. ii) 0.050 in. wire, gage length 1.5 in. Ball bearings were welded to the ends of the wires and the gage length was taken to include all material between the welds. Socket-type grips were used with these specimens. With specimens of type ii), joining was performed in a specially constructed brass jig, under argon, and automatic timing was utilized in the procedure. No adverse effects of welding were noted. Specimens were encapsulated and solution treated for 1 hr at temperatures selected to produce the same average grain size, -50 µ. Annealing twin boundaries as well as normal crystal boundaries were counted. The temperatures used are listed in Table 11. Table 11. Specimen Size. Temperature of Heat Treatment and Resulting Grain Diameters for Test Materials Recrystallization Resulting Material Condition Temperature Grain Sue AISI 330 Not H purified 0.070 120O°C 45 to 55µ in, wire AlSl 330 H , pure, 0.070 in. 1150°C 45to55µ wire Fc/35Nil15Cr Pure, 0.070 in. wire 1000°C 45tossp Fe/Ni Pure. 0.070 in. wire 775°C 45 to 55µ Fe/Ni/C Pure, 0.050 in. wire 850°C 10 to 20p AlSl 330 Not purified, 0.050 1150CC 45to55p in. wire AlSl 330 ti, pure, 0.050 in. 1150°C 45to55p wire

Jan 1, 1970

By Roberto Pimentel de Souza, Helder Zenóbio

VRD started producing pellets in 1969 with one 2-million-t straight grate plant. In the beginning of April 1973, the second unit came on stream with an additional capacity of 3 million t/a of pellets. In January 1977, the third unit started, bringing the annual capacity to 8 million t/a. In the coming year (1978-79), three more units, 3 million t each, are expected to begin production. CVRD&apos;s experience with different binders and additives is described. Over the years several kinds of pellets have been produced to satisfy market requirements. General quality information is given for each.

Jan 1, 1981

By Alfred Weiss

The business world of tomorrow will experience a major change in its data communication systems, with the mineral industry being among those to feel the greatest impact of this change. This development can be expected to occur over the next two decades at a steadily increasing tempo. One major factor prompting this transformation is the fact that technological knowledge is doubling approximately every five years. Moreover, industry is becoming more and more dependent upon the flow and processing of information in its long-range planning, while government requirements and regulations demand increasingly detailed and precise information on plant operations.

Jan 1, 1971

By James M. Henderson, John B. Pfeiffer

The recently completed liquid sulfur dioxide plant at American Smelting and Refining Co.&apos;s Tacoma copper smelter in Washington last April is one step by the firm to meet ambient air quality standards in the vicinities of its three US copper smelters. At a capital cost of $18.5 million, the liquid SO2 plant will work together with an existing sulfuric acid plant to treat all gases generated by the copper converters. Designed to handle up to 45,000 cfm of converter gas utilizing the Dimethylaniline (DMA) process, this plant is expected to recover about 51% of the total smelter input.

Jan 11, 1974

By D. A. Sangrey, D. Marcus, S. A. Miller

A methodology was developed wherein the increase in compressive strength, mineralogical changes, and pore water composition were studied simultaneously as a function of moisturized spent shale curing time. From these results the relationship between the nature of cementation process and the composition of pore water was established. Heavy metals were entrapped in the cementing constituents and the pore water became mainly a solution of alkaline sulfates. The specific data are applicable only to the material studied. But the methodology and general conclusions are useful for evaluating the environmental factors in spent shale disposal and expected leachates composition.

Jan 1, 1986

By G. L. Gates

The comments by George L. Gates are appropriate to the characteristics that we sought to feature in our study and they are appreciated by the authors. In our laboratory deposition tests the smoothness of the surface seemed to be more important than the type of surface. However, we also noted that even where very smooth glass, plastic or polished metal coupons were used, scale deposition still occurred though the rate varied. Much more information is needed, however, and new work to solve the mineral scale deposition problem by mechanical and chemical means is expected to continue.

By Donald Towse

Geothermal energy can substitute for and compete with other fuels, but until now it has been used only in special situations where it costs much less than alternate fuels. Geothermal heat is expected to be developed where it can: (1) compete with alternate fuels, (2) replace scarce fuels, (3) be more environmentally acceptable, or (4) is especially adapted to local needs. Economic problems in development include the often high capital costs of wells and gathering systems and the long lead-times required for electric generating plants. The large investment and long payout times for large industrial uses adversely affect the economics.

Jan 1, 1977

By Walter Riethmeier, Arthur J. Lynch

The future of plant design in mineral processing and extractive metallurgy is discussed in relation to present trends and the future need to build plants that will treat larger tonnages and lower grades of ore. The future equipment and plant design of crushing, grinding, screening, classification, flotation, magnetic concentration, gravity concentration, hydrometallurgy, thickening, filtration, tailings disposal, health, safety, environment, and materials of construction are discussed. Future plants are expected to follow upon present evolutionary trends. The impact of escalation, energy costs, and increased regulation of the industry is foreseen as a major influence on plant design.

Jan 1, 1978

An ore search for commercial titanium-bearing ore deposits is in progress by the Crane Co., manufacturers of valves, because they expect this metal to be important in valve manufacturing in the future. The company will eventually be mining and making titanium sponge. At present they are buying titanium tetrachloride from the Stauffer Chemical Co, at Niagara Falls and making titanium by reaction with magnesium. Production from the Babbitt concentrator of Reserve Mining Co. is scheduled to begin in late 1951 or early 1952. The capacity is to be 300,000 tons of pellets per year made from magnetic taconite concentrates.

Jan 7, 1951

By J. A. Bownocker

THE production of oil in Ohio, in 1924, was characterized by no marked or surprising change. Low prices and the absence of promising territory made the year quiet. As is well known, Ohio has reached a state of "settled production," and the most that can be expected for the ensuing few years is to maintain the output at approximately the present figure 1921 7,335,000 1922 6,781,000 1923 7,085,000 Geographically, the Ohio fields may be divided into three areas, each of which gets its main supply of oil from a different stratigraphic horizon.

Jan 3, 1925

"IRON for iron" may soon be the primary concept of Mexico&apos;s mining industry. If reports that President Adolfo Ruiz Cortines intends to extend federal control over mining are true, Mexico will export iron ore to the U. S. only in return for machinery. Actual exporter will be the Federal Government, with negotiations through the Bank of Mexico. Shipments of iron ore, under this kind of arrangement, can be tightly controlled, assuring that machinery and heavy equipment instead of dollars are the means of payment. Expansion of this policy in the next few years can be expected according to reports.

Jan 6, 1953

By J. A. Bownocker

THE production of oil in Ohio, in 1924, was characterized by no marked or surprising change. Low prices and the absence of promising territory made the year quiet. As is well. known, Ohio has reached a state of "settled production," and the most that can be expected for the ensuing few years is to maintain the output at approximately the present figure 1921 7,335,000 1922 6,781,000 1923 7,085,000 Geographically, the Ohio fields may be divided into three areas, each of which gets its main supply of oil from a different stratigraphic horizon.

Jan 3, 1925

By L. A. Pursell

Environmental constraints can both delay and raise the cost of a major plant addition, often requiring a complete reevaluation of the plant site and the proposed project. In this case history, steps are presented which were followed in applying for environmental permits for a major addition to a lime plant. Methods are described for determining expected emission increases and for selecting the best control technology for each source. The description progresses through pre-application conferences with control agencies, the formal application procedure, computer modeling the air quality impact, and the methods followed in obtaining a favorable determination.

Jan 1, 1983

By José Aloisio Paione, Eudes Prado Lopes

The geophysical exploration carried out by the Brazilian government through the Mineral Resources Development Co. (CPRM) to discover and develop Brazil&apos;s mineral resources is discussed. Particular mention is made of procedures specially adapted for contracting companies specialized in geophysics, CPRM&apos;s activities, statistical data from study programs, as well as the financial investments committed. More than 500 000 km of aerogeophysical surveys have been carried out by CPRM in the last four years, and it is expected that more than 600 000 km will be flown in 1974 and 1975, at an investment of approximately $30 million.

Jan 1, 1977

Aaby, Alton O , (S&apos;47) Univ of Minnesota, Mimeapolis, Minn Aaby, Waldo S , (S?48) Univ of Minnesota, Minneapolis Minn Aalde, Kaare, (S&apos;48) Univ of Nevada, Reno, Nev Aaring, Floyd D , (S&apos;48) Univ of Oklahoma, Nor man, Oka Aaronson, Hubert I , (S&apos;47) Carnegie Inst of Technology, Pittsburgh, Pa Abbott, Peyton Osborn, (S&apos;46) 1502 Westover, Austin 21, Texas Abel, Malcolm D , (S&apos;47) Univ of Texas, Austin, Texas Aberg, Richard S , (S&apos;47) Univ of Minnesota, Minneipolis, Minn Abrahamson, Guy C , (S&apos;43) 420 W Dennis St , Wilmington, Calif Abrahao, Benjamin, (S&apos;46) Escola Politeenica da Unnersidade, de Sin Piulo, Braizil Achter, Meyer R , (S&apos;46) Carnegie Inst of Tech , Pittsburgh, Pa

Jan 1, 1952

By Theodore Simons

I. INTRODUCTION PERMISSION to present this paper at the February, 1915, meeting of the Montana Section of the American Institute of Mining Engineers was liberally granted by W. A. Clark, Jr., President and General Manager of the Timber Butte Milling Co., and by the representative of the Minerals Separation Co. For the many courtesies shown the writer on his visits to the mill and for information supplied, he is indebted to all the officers of these companies, especially to W. N. Rossberg, W. D. Mangam, Hamilton Cooke, Jr., T. M. Owen, T. C. Wilson, R. McGillivary, L. L. Quigley, C. Bartzen and others. The writer takes this opportunity to herewith express to them his appreciation and sincere thanks.

Jan 6, 1915

NEW MEMBERS The following list comprises the names of those persons who became members during the period Apr. 10, 1916 to May 10, 1916. ALLEN, WILLIAM R.... Pres., Boston and Montana Development Co., Butte, Mont. BARKER, EDGAR EARL, Min. Engr. Mine Supt., Chile Exploration Co., Chuquicamata, Chile, S. Amer. BAYLESS, JOHN Z., Met. Engr Alaska Gastineau Min. Co., Thane, Alaska. BLACKWOOD, ARTHUR E., Mgr., Sullivan Machinery Co., 30 Church St., New York, N. Y. BREYER, FRANK G., Chief Testing Dept., The New Jersey Zinc Co., (of Pa.), Palmerton Pa. CARPENTER, JAY A., Mill Supt... . West End Cons. Mining Co., Tonopah, Nev. CORLESS, GEORGE BRADFORD, Geol., Missouri Bureau of Geology and Mines, Joplin, Mo.

Jan 6, 1916

Alder, John W., Student, Mass. Inst. of Tech Cambridge, Mass. &apos;38 Allen, Charles F Mines McFarland, Cal. &apos;34 Anderson, Norman John, Student, South Dakota School of Mines Rapid. City, S. D. &apos;32 Ansel, Gerhard, Student, Mass. Inst. of Tech Cambridge, Mass. &apos;34 Arakelian, Haig Mark, Student, Inst. of Tech Cambridge, Mass. &apos;34 Archer, George K., Student, Colorado School of Mines Golden, Colo. &apos;34 Arnot, Paul H. 608 S. Acacia St., Compton, Cal. &apos;31 Asel, Philip R., Student, Colorado School of Mines Golden, Colo. &apos;32 Augenthaler, Robert L., Student, New Mexico School of Mines Socorro, N. M. &apos;32 Augustine, Robert W. Address Wanted. &apos;32. Austin, Robert B., Student, Univ. of Idaho Moscow, Idaho. &apos;34

Jan 1, 1934

By H. J. Modi, P. L. De Bruyn

In recent years interest has been aroused in flotation rate studies both from a technical and a more practical aspect. With increasing fineness of grind becoming a necessity in treatment of low grade ores, differences in flotation rates of various size ranges will assume importance in the evaluation of overall recovery results. Theoretical analysis of flotation kinetics was initiated by Schuhmann, who sought to define flotation rate of a given mineral and specified size range in terms of certain physical variables of the flotation system. Using as a basis for his analysis the bubble- particle encounter hypothesis previously advanced by Gaudin, Schuhmann writes for the rate of flotation (R,) of particles of average size x, [ ]

Apr 1, 1956