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By Robert G. Ditchburn

The Mariana arc is an ~1,400-km-long intraoceanic arc that marks the southern extension of the Izu-Bonin arc, and is host to 62 ?volcanic centers? of which at least 27 (21 submarine) are hydrothermally, or volcanically active. A surface ship cruise in early 2003 mapped the distribution of hydrothermal plumes emanating from these centers, followed by remotely operated vehicle (ROV) cruises with ROPOS in 2004 and Jason II in 2006. With the exception of one volcano (East Diamante), none of the vent sites visited by the ROVs were host to sulfide mineralization. Rather, they were characterized by high sulfidation mineral assemblages dominated by native sulfur. The sulfur was seen marking the vicinity of vent sites, or as sulfur ?chimneys? (e.g., NW Eifuku and Nikko), or more spectacularly as ?lakes? of molten sulfur, either occupying the summit crater of the volcano (e.g., Nikko), or perched on the flanks of the volcano, near the summit (e.g., Daikoku). Gas (H2S and CO2) was discharging through the molten sulfur. Evidence for these lakes to have either been substantially ?deeper? in their recent past (e.g., Nikko), or existing at other volcanoes (e.g., Seamount ?X?) is given by remnant ?pillars? of native sulfur that are reminiscent of rock pillars in lava lakes found along mid-ocean ridges.

Jan 1, 2008

By Thomas Fraser

IN a Nation-wide appraisal of coking-coal reserves and of the feasibility of expanding them by upgrading marginal coals, it is natural that the Pittsburgh region of Pennsylvania should be considered first. Here, where the American iron and steel industry started, the Pittsburgh coal bed is of paramount importance. The use of coke in iron blast furnaces is said to have begun with the discovery that good blast-furnace fuel could readily be made by a simple method of coking Pittsburgh coal. To the present time, the prosperity of the steel industry has depended largely on utilization of this great coal reserve and the cheap transportation afforded by the Monongahela River system. OBJECT AND SCOPE OF INVESTIGATION The initial project in the study of upgrading marginal coking coals was laid out in this area, which contains large reserves of Pittsburgh coal contiguous to the Monongahela and its navigable tributaries. Much of the Pittsburgh coal remaining here is known to have a high sulfur content. The problem of reducing the sulfur to meet metallurgical requirements already has received much attention, and it is considered to be one of the most difficult technologic problems in the field of coal washing.

Jan 1, 1950

By M. J. MONEA

Canada's only economic high-swelling bentonite deposit is mined in Wilcox, Saskatchewan, by A vonlea Mineral Industries Limited. The bentonite resulted from devitrified and altered volcanic ash released during the Laramide Orogeny. Volcanic ash was deposited in a pre-Cretaceous basin that was formed by salt solution collapse structures. Sedimentary rocks in the Wilcox area belong to the Snakebite Member of the Upper Cretaceous Bearpaw Formation. Bentonite beds are 61 cm, 46 cm and 30 cm thick; these are separated by 365 cm and 182 cm of shale respectively. Saskatchewan bentonite is used primarily in the oil well industry.

Jan 1, 1984

By E. A. Thiers

The causes of structural changes in the markets for high technology alloying metals are discussed in terms of technological, economic, and financial trends. Recent market imbalances have affected producers in developed and developing countries differently. Possible response strategies for suppliers in the two types of countries are examined that may alleviate future market imbalances.

Jan 1, 1988

By C. O. Fairchild

THE meaning of temperature control can be extended to cover not only the control of temperatures' but also the control of processes through a knowledge of the temperatures involved. In this sense it has a very wide interest. A list of the industries in which temperature control is used in one way or another would cover nearly the entire industrial field. This discussion will be confined to the field of high temperatures. In practically all industries involving operations at high temperatures, pyrometers are used or men are paid for their ability either to estimate temperatures or gage an operation by some physical or chemical change or condition dependent on temperatures. As progress is made in the development of instruments and of methods for measuring temperature, some of these highly skilled artisans are learning the use of a new tool. Many processes have been, in recent years, improved by means of exact measurement thus substituted for estimation, but in a great many industries the pyrometer has had practically no opportunity to demonstrate its usefulness. The perfecting of instruments must be accompanied with a dissemination of the knowledge that new instruments are available and can be economically used. The demand at present, however, is ahead of the supply, and many industries are handicapped by the want of pyrometers. One of the highest paid skilled tradesmen of the present time is the man in the steel rolling mill who knows when proper working temperatures are attained. The metallurgist in his development of steels is continually demanding closer adherence to given temperature ranges in the processes, and the pyrometer is rapidly becoming indispensable. Properties of the finished products are being correlated with working temperatures and so closely that in some cases even the pyrometer is taxed to give the required accuracy. The greatest progress has been made in those industries in which the lower temperatures are used, particularly below 500° C. In this lower range automatic control has been highly developed.

Jan 9, 1919

R. W. NEWCOMB, New York, N. Y. (written discussion*).-0n page 1712, the middle paragraph states that, in industrial equipment, only the single-step method of automatic regulation has been applied. Quite recently, there has been developed an automatic temperature regulator, operating in conjunction with a pyrometer of the thermoelectric type, in which the control is a slow regulation, with a range capable of regulat-ing valves, dampers, rheostats, or any other rotatable member, through one or more complete revolutions. It can control two valves at the same time, with a fixed definite ratio between them. Aside from those conditions in which it is. necessary to control two valves with a definite ratio one to the other, the greatest advantage that this slow, even control will have over those controls that are either all on or all off, will be for use in connection with processes where a large temperature variation is required, extended over a considerable period of time; that is, where the temperature must be regulated along an in-creasing or decreasing time-temperature curve.

Jan 12, 1919

By R. J. Kuczynski

The U.S. Bureau of Mines operated a 2,000-9 (4.4-lb) batch process development unit for recovering platinum-group metals (PGM) from automobile catalysts. Virgin monolith, used pellet and used monolith catalyst samples were tested. Leaching twice with 1-pct sodium cyanide (NaCN) solution at 160' C for 1 h in a pressure vessel dissolved over 95 pct of the PGM from virgin catalysts and over 90 pct from used pellet catalysts. Over 85 pct of the PGM was dissolved from used monolith catalysts when a third leaching step was added. PGM concentrates as metallic powder containing over 99.8 pct of the dissolved PGM and analyzing greater than 70 pct PGM were recovered by heating the pregnant leach solutions from virgin catalysts to 250' C and used catalyst to 275" C for 1 h. The solution after heating contained primarily sodium carbonate from cyanide decomposition and less than 0.2 ppm total cyanide.

Jan 1, 1993

By A. N. Shen

Fe3A1 intermetallics are potential inexpensive candidate for hot applications. In this project, torsion tests on hot-rolled and annealed Fe3A1 (Fe-15.5A1-5.8Cr-1.0Nb¬0.05C) were carried out over the ranges 750-950°C and 0.01~1s-1 . The experimental results showed that when peak stress op>90MPa (LogZ>16s-1 , Z: temperature-compensated strain rate), specimens cracked at randomly low strains. Optical microscopy exhibited original elongated grains and many grain boundary cracks associated with segregation. With op<40MPa (LogZ<16s-&apos;), specimens deformed with low random op but considerably high fracture strains; slowly propagating cracks may explain the reduced flow stress. Optical microscopy showed both elongated grains and equiaxed subgrains with some indications of geometric dynamic recrystallization (gDRX) and of static recrystallization (SRX). Compression tests gave higher stress with little effect of the preexisting cracks. The activation energy Quw of current material in satisfactory torsion and compression tests is about 10% higher than previously published. Fe3A1 has body-centered cubic structure in the experimental range, so it was compared with ferritic stainless steel 434C (Fe- 16.55Cr-0.96Mo-0.21Ni). Constitutive constants and restoration mechanism are compared between these materials. While Fe3A1 is hardly a light metal, it is considerably lighter than most steels. Furthermore, like the other body centered cubic metals (BCC) (a-Fe, ß-Ti, ß-Zr and ß-brass), it exhibits a high degree of dynamic recovery (DRV) like Al alloys, producing easier hot workability than that of austentic stainless steels.

Jan 1, 2007

By Ron Ferris

The Westinghouse Temptifier TM, using heat pump principles, recovers lowgrade waste heat in the 600P to 1600P temperature range and amplifies it to usable levels of up to 2200P. Coefficients of performance (C.P.D.) normally encountered are from 3.0 to 6.0, with capacities from 200,000 to 10 million Btu/hr.

Jan 1, 1979

By C. Zener, H. Nielsen, D. Van Winkle

THE internal friction of metals has been studied frequently at elevated temperatures.1-4 In most cases it rises rapidly with increasing temperature. The notable exceptions are ferromagnetic materials, and lead.2 This paper describes an investigation of the general features of the high-temperature internal friction of 70-30 alpha brass. EXPERIMENTAL METHOD The internal friction of a metal is a measure of the rate at which it dissipates energy of vibration. The measure adopted here, I/Q, is (I/2p) times the specific damping capacity, a measure commonly used by engineers. In the measurements of this investigation, the stress level was kept so low that the observations were independent of the stress. The general method of making such measurements, and of observing the temperature of the specimen during a measurement, has been described elsewhere.5,6 The driver and detector coils were wound with wire insulated with glass thread, in order to withstand the high temperatures used. In previous work electrical eddy currents in the specimen served as the coupling between the mechanical vibration of the specimen and the electrical circuits of the driver and detector. The high values of the internal friction in the present investigation rendered this coupling insufficient. In order to increase this coupling, pole pieces cut from ordinary telephone diaphragms were attached to the specimen. A mixture of French chalk and water glass proved a satisfactory cement. All measurements were made at the fundamental frequency for transverse vibration, which lay between 600 and 900 cycles per second. SPECIMENS The measurements described herein were made upon a single cylindrical rod of brass, kindly furnished by Dr. Cyril Stanley Smith, of the American Brass Co. This rod was the specimen E of the set of alphabrass rods described in an earlier paper.6 Successively larger grain sizes were obtained by annealing at successively higher temperatures. A slice was cut off one end after each set of measurements. Grain counts were made on each slice by W. E. Lindlief, of the American Brass Co. Nine fields were viewed on each piece, located as shown in Fig. I. Results are given in Table I. The grain size is defined in the usual way; namely, Grain size = I/n ½ where n is the mean number of grains per square millimeter. EXPERIMENTAL RESULTS This paper is concerned exclusively with the part of the internal friction that becomes dominant at high temperatures. It is thus desirable to separate this part of the internal friction from the part that is

Jan 1, 1942

By P. Mousset-Jones, G. Danko

Variations of the temperature and steam/moisture content of the air with distance and time are modelled for a single airway. The input for the simulation is an air temperature that varies with time, together with the moisture/steam content that results, for example, from a fire with a given distribution of heat and of fume concentrations at the beginning of the airway. The transport of heat and moisture to the surface of the wallrock is assumed to be simultaneous. Such multiphase convection may result in evaporation from the moist wall close to the fire and recondensation downstream. The modelling of this non-linear effect is a unique feature of the new simulation. A new analytical solution is used to calculate the conduction of transient heat within the rock mantle, which, in the event of a fire, is typically a short-term process. This allows for an arbitrary variation of surface temperature with time - unlike that permitted by the age function solution, which is limited to stepped temperature changes. An iterative numerical scheme that has recently been developed to simulate mine climate is used to calculate the coupled transient heat conduction and multiphase surface heat transport in successive length increments along the airway. To demonstrate the simulation procedure a numerical example is presented in which a fire with a given distribution of heat and fume concentrations with time is located at the beginning of an airway

May 1, 1991

By Jilai Xue, Jun Zhu, Germain Kouma Ndong, Qiaochu Liu, Luxing Feng

"High-temperature oxidation and corrosion behaviors of Ni-Fe-Cr alloy as inert anodes for aluminum electrolysis have been studied in oxygen and molten electrolyte. The oxidation and corrosion scales on the anodes tested were analyzed using XRD and SEM-EDS. The oxidation rate is found to increase with increasing temperature from 700 °C to 950 °C, which can be approximately described by an inverse power rate function. The oxidation scales at 750 °C, 920 °C and 950 °C contain Cr-rich phase along with FeCr204 and (Feo.6Cro4)203. The corrosion extent of Ni-Fe-Cr anodes in electrolyte is dominated by temperature, which can make the scales thickness double from 700 °C to 750 °C or from 920 °C to 950 °C. Cr and Fe in the scales on the anode in electrolysis corrode preferentially into the molten electrolyte, while the nickel oxides could better sustain the corrosive environment in electrolysis. The results can be useful for developing inert anode material for potential application in aluminum electrolysis.IntroductionThe development of an inert anode for aluminum electrolysis has been a long term goal for aluminum industry. The present process for primary aluminum production involves the reduction of alumina with carbon anodes, forming carbon dioxide:"

Jan 1, 2013

By Leszek Hoser

Polycrystalline oxide superconductors that have the perovskite structure, that are oxygen deficient, and that have compositions based. on the so-called. 1-2-3 (YBa2Cu3O7) compound, were investigated.. The materials exhibit a high critical transition to superconductivity at temperatures near 90oK. It was determined that maintaining the oxygen content within the correct range in connection with an appropriate amount of CU ions in the crystal lattice leads to high-critical temperature (Tc:) superconducting properties. High-Tc: superconductors with a critical temperature in the range of 100°K were developed. Further investigations, based. on the theoretical examinations of the origin of superconductivity, have been performed and are discussed..

Jan 1, 1989

By R. J. Zagrocki

Rekindled public concern about lead toxicity has intensified the awareness of lead-bearing materials in contact with the environment and the human population. Lead&apos;s common association with other metals makes the increasingly restrictive lead standards a primary concern for a large number of metal and metal-related industries. In commercial scale demonstration tests with lead-bearing wastes, the HRD Flame Reactor process has a demonstrated ability to separate and recover over 95% of the lead as a recyclable oxide, while rendering the remainder of the material as vitrified, non-leaching, and nonhazardous co-product. Recent Flame Reactor process tests and preliminary cost data for secondary lead soda slag are highlighted.

Jan 1, 1992

By Ruder, W. E.

CONSIDERABLE interest has been shown lately in various types of furnaces for the production of high, temperatures, both for laboratory purposes and for small industrial uses. Dr. J. A. Harker1 described certain modifications of the Arsem graphite resistance helix for high-temperature work at the National Physical Laboratory. Dr. Northrup ,also has developed two interesting forms of high-temperature furnaces. In 1911, Messrs. Winne and Dantsizen2 described two forms, of resistance furnaces using ductile molybdenum or tungsten as resistors. Since the discovery, by this laboratory, of methods for producing these metals in ductile form, their use as resistance elements in the research laboratory of the General Electric Co. has grown to such an extent that they are now almost indispensable. These furnaces are used here for alloy research, annealing, heat-treating, and practically all f the thermal processes requiring temperatures above 900° C. Various types of furnaces have been developed to meet the general needs of laboratory work, and it is the purpose of this paper briefly to describe some of these furnaces. A tubular furnace wound with a metallic resistor is the simplest type to construct, and almost every laboratory has made such furnaces. The only essential difference between a furnace wound with platinum or base metal and one wound with tungsten or molybdenum is that the coils of the latter must be heated in a neutral or reducing atmosphere. It has long been our custom here to build our resistance furnaces with a metallic casing from which the tube could be easily removed for rewinding. The heat-insulating material-usually calcined magnesia, alumina, silica, or silex, depending upon the nature of the resistor-is used in powdered form so that it can he readily removed and replaced. In order to adapt this method to tungsten or molybdenum windings, it

Jan 2, 1918

By M. E. Myers

An experimental program is being carried out to determine the thermodynamic characteristics of zinc solubilization in high-temperature iron and iron-carbon alloys. Two versions of an isopiestic technique are being used, with zinc at a lower temperature being equilibrated with pure iron foils or molten iron-carbon alloys at a higher one. The lower temperature sets the partial pressure of zinc vapor, and thus the activity relative to a given reference state. Initial results show Henrian behavior for dilute zinc solutions in austenite and a molten 4.6% C alloy, with unit-pressure solubilities in pure Fe that closely match the predictions of Wriedt.

Jan 1, 1992

By R. M. Wilhelm

HIGH-TEMPERATURE thermometry,, as treated in this paper, deals with the measurement of temperature in the range 100° to 550° C. The lower limit corresponds to the temperature of boiling water at normal atmospheric pressure, the upper limit is approximately the highest temperature to which mercury in a glass thermometer may be safely subjected.1 In this range., the domains of pyrometry and thermometry overlap somewhat, for high-temperature resistance thermometers and thermocouples generally classed as pyrometers are often used below 550° C. This paper will be confined to high-temperature mercurial thermometers, and indicating and recording thermometers of the vapor pressure, liquid or gas filled, and bimetallic or graphite-metal expansion types, a classification of which is as follows: CLASSIFICATION OF THERMOMETERS GENERAL CLASSIFICATION SUBDIVISIONS Mercury in glass Laboratory- Etched or engraved stems (mercurial) Enclosed scale (Einschlus) Industrial Vapor pressure Indicating and Pressure Liquid filled recording Gas filled Bimetallic Graphite-metal expansion

Jan 9, 1919

A. 0. ASHMAN, Palmerton, Pa. (written discussion?).-Owing to the conflict of the terms thermometry and pyrometry, in numerous cases the entire field of temperature measurements has been divided under these two headings. This confusion is probably clue to the fact that originally a pyrometer was understood to be an instrument for measuring temperatures above the range of a mercury thermometer. In modern practice, however, pyrometers are not only used to measure the temperature over the range of the thermometer, but also to a much

Jan 12, 1919

By M. Manrique, S. A. Pirzada, P. R. Taylor

A thermal plasma-assisted laminar flow reactor was used to evaluate the kinetics of converting alumina to sodium aluminate in flight. Free energy minimization calculations were used to determine experimental conditions. The experimental variables included alumina particle size, alumina/sodium nitrate molar ratio, temperature and residence time. A mathematical model for the conversion was developed and validated. Experimental and mathematical results are presented.

Jan 1, 1998

By J. E. Lawver

On the basis of both laboratory and pilot-scale tests, a newly developed high-tension electrostatic process is technically and economically feasible for the production of iron ore superconcentrates containing 0.02 to 0.20% silica at iron recoveries of 85 to 90%. The process can be used to recover both a superconcentrate and a pellet-grade concentrate, from a feed containing middlings, and the system is not unduly upset from changes in feed structure and composition. The adverse affect of excess quantities of material finer than 30 microns, i.e., above 10% in quantity can be avoided by a desliming step. Finally, because of the cost of drying, the best feed for the process appears to be dry-ground ores as well as spiral, flotation, or magnetic concentrates.

Jan 1, 1970