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By Tormod Forland

FROM equilibrium measurements on the system NaF-Na 3A l Fo-A 1 2 O 3-Na CO 3-CO 2 with high contents of NaF, Forland, Storegraven, and Urnesl concluded that complexes are formed containing two oxygen, three aluminum, and a less defined number of fluorine per complex. The same number of oxygen atoms per complex was also found by cryoscopic measurements for mixtures high in NaALF 6. In a recent paper by Stokes: some other complex ions, Al2O2F42- and AlOF2-, have been suggested. Here an additional argument in favor of the complex ALO2F. suggested by Forland, Storegraven, and Urnes will be given. When fused Na3AlF6 containing some A12O3, is cooled slowly, the solid phase will consist of the two components as separate phases. The melting point and the heat of fusion of Al2O3 are so high that this component will form the stable solid phase even though in the liquid state the complex may have a high stability. If, however, the fused mixture is quenched, the decomposition of the oxygen-containing complex and the formation of solid Al2O3 does not proceed fast enough, and a solid solution of A12O3 in Na3AlF6 is obtained. Zintel and Morawietz3 obtained cryolite containing 10 pct AL2O3 in this way. The density and the lattice parameters of the A12O3 containing cryolite were also measured, and from this it was concluded that the Al2O3 enters the cryolite lattice as Al3AlO0 groups replacing Na3AlF6 groups. However, the experimental data could as well be explained by assuming that one Na+ ion and two of its neighboring F- ions are replaced by one Al3+ ion and two O2- ions. This may be pictured schematically as: F F F F F F F Al F Na F Al F ,-Na+ + Al8+ F Al 0 A1 0 A1 F F F F —2 F- + 2O2- F F F solid cryolite cryolite-alumina solid solution This means that the complex in the solid solution, derived from X-ray and density measurements, is the same as that which Forland, Storegraven, and Urnes derived from equilibrium measurements in the liquid state. References IT. Forland, H. Storegraven, and S. Urnes: Ztsch. fur anorgan-ische und allgemeine Chemie, 1955, vol. 279, p. 205. 2J. J. Stokes: AIME Trans. To be pubhshed. s E. Zintel and W. Morawietz: Ztsch. pubhshed.fur anorganische und allgemeine Chemie, 1939, vol. 240, p. 145.

Jan 1, 1958

By O. D. Gonzalez, R. A. Oriani

The migration of hydrogen and of deuterium dissolved in a iron and in nickel induced by an applied electrical potential has been measured over a range of temperature. In all cases the intevstitial solute migrates to the cathode. The deduced charges of transport are positive, independent of or slightly dependent on temperature, and markedly larger for the beavier mass. These results are interpreted as showing predominating momenlum transfer between electron holes and the acticated complex of the elementary diffusion act. THE migration of components of a metallic system under the action of an applied electrical potential is called electromigration or electratransport. This phenomenon has been known since 1861 and is becoming of increasing interest to metal scientists because of the opportunity it offers to explore the connections between mass transport and electron transport. Until recently, reliable data have been very scarce because of the difficulties inherent in the measurements. In addition, theoretical understanding has been either nonexistent or rudimentary and at present this situation is only moderately improved. Whereas the prevalent notion had been (and is still widely held) that electromigration directly reflects the state of ionization of a component in its equilibrium state in the metal, it is now becoming clear that the major, if not the sole, factor is the momentum transfer between the charge carriers, themselves in motion because of the applied field, and the metallic components in their activated state. It becomes important therefore to obtain reliable data over a range of temperature on electrornigration in systems where only one component moves, that is, either in pure metals (vacancy motion) or in interstitial solid solutions. Our choice of systems was dictated by our measurements' of the Soret effect in solid solutions of hydrogen and deuterium in iron and nickel. Indeed, the main reason for making measurements on electromigration at all is that we suspected a mechanistic connection between thermal diffusion and electromigration. In our former paper' we proposed that what is common to both phenomena is the momentum transfer between the charge carriers in the metal and the atom as it jumps from one equilibrium position to another. In Soret diffusion, however, there is in addition the dissipation of the energy of the jumping atom via pho-nons. We have since found that similar ideas for this interconnection have been developed by Fiks.2 In the present paper we will discuss in more detail our understanding of the mechanism of electromigration itself, but we turn first to a presentation of the experiments and results. EXPERIMENTS AND RESULTS Let us consider a metallic system in which only one component, m , can diffuse at the temperature in question, and to which are applied simultaneously an electrical potential gradient, grad cp, and a chemical potential gradient, grad p,. One may write3 for the material flux Jm and the electronic charge flux Je by applying the condition, grad = 0, to Eq. [I] and evaluating grad(um/T) for the isothermal case and for activity coefficient independent of composition over the relevant composition range. ere, c is the concentration and D the diffusivity of the mobile component. The experimental technique that we have used to measure Z* for the isotopes of hydrogen individually dissolved in each of two transition metals has been developed from a method used by Wagner and Heller.4 (A somewhat similar method was also used by Herold.5) A wire or thin rod of the metal under study connects two volumes of gaseous hydrogen at identical pressures; hence grad um = 0. A direct current is made to pass through the specimen, serving to maintain the specimen at the desired temperature and also to produce the electromigration of the hydrogen dissolved in the metal in equilibrium with the gaseous hydrogen. Under these conditions, the flux of hydrogen from one volume to the other is given, from Eq. [I] for grad( um/T) =0by

Jan 1, 1968

Natural gas was introduced to the Melbourne reticulation system in April 1969 and since that date sales to industrial consumers in the Gas & Fuel Corporation of Victoria area of supply, have increased by over 50% This increase has occurred despite the fact that the areas in which the new fuel is available have been dependent on the progress of the conversion operation from manufactured gas. The half way mark for conversion was reached in May 1970. The reason for the adoption of natural gas by industrial users is usually the result of objective financial analysis leading to the conclusion that the new fuel will give the lowest overall production cost. Many factors are involved in such an analysis of which the price of the fuel is only one. Amongst other important elements in the cost calculation are:- -ò òò -(1) The effect of fuel on product quality (2) Maintenance and handling costs for alternative fuel. In addition to economic gains for the individual user, the use of natural gas should benefit the whole community through its effect on such things as, air pollution and overseas balance of payments.

Jan 1, 1970

The Bulli and Wongawilli Seams, the two principal sources of coking coal for the Port Kembla steelworks of Australian Iron & Steel Pty. Ltd., vary in rank and in type over the Southern and South Western Coalfields.The Bulli Seam, ranging widely in type, produces coke varying from weak to strong. The Wongawilli Seam, more consistent in type, produces coke of more consistent strength, but considerably less strong than that from the best Bulli Seam coal.Plans of seam variation show the regional trends in rank and type for each seam.The strongest coke is derived from coal containing between 45 and 55 per cent vitrinite, m.m.f. This is obtainable from the Bulli Seam in a zone embracing Bulli and Appin collieries.A satisfactory correlation is achieved between vitrinite content and coke stability and hardness, enabling prediction of coke strength for Southern Coalfield coals.The use of vitrinite reflectance, as an indicator of rank, in addition to type to predict coke strengths is at present hampered by lack of data, particularly in the South Western Coalfield. Nevertheless, data available at present allow the use of both variables and give better correlations with coke strengths than type alone.A spread of comprehensive data across both coalfields will enable advance assessment of cokes produced from coals having known rank and type. Blending to a ranktype specification for optimum coke strengths would allow the best use of the coal reserves of the coalfields.

Jan 1, 1969

By James A. West

Near East region countries continued to supply a large share of the world's energy requirements in 1965. The area accounted for nearly 27 percent of estimated total world crude oil output and for about 60 percent of world exports of this commodity. Also, it was the source of more than 40 percent of the world's petroleum refinery products exports. Although other mineral industry activities remained relatively in? significant in comparison with petroleum, regional production and export of certain metallic and nonmetallic mineral commodities were of world significance. Of these commodities, chief in importance were chromium, copper, mercury, antimony, boron, potash, and phosphate Tack. The Near East region contains the largest and most productive oil resources in the world. Petroleum exploration and development operations during 1965 resulted in crude oil reserve additions of almost 8 billion barrels to increase proved reserves to 219 billion barrels at yearend, an amount equal to nearly 68.5 percent of the world's proved oil reserves. Near East countries' production of crude oil averaged a record 8.337,575 barrels per day in 1965, an increase of nearly 11 percent over that of 1964. On an annual basis, Kuwait continued as the leading oil producer in the Near East; however, Saudi Ayabia was a close second and its rate of production in late 1965 exceeded that of Kuwait. The major oil producing nations and their percentage of total area crude oil output was Kuwait, 26.0; Saudi Arabia 24.3; Iran, 22.3; and Iraq 15.9.

Jan 1, 1967

By J. Th. G. Overbeek, R. Schumann, P. L. De Bruyn

THE technique of concentrating valuable minerals from lean ores by flotation depends upon the creation of a finite contact angle at the three-phase contact, mineral-water-air. If the mineral is completely wetted by the water phase, contact angle zero, there is no tendency for air bubbles to attach themselves to the mineral. However, when the contact angle is finite, the surface free energy of the system, water-air bubble-mineral particle, can be diminished by contact between the bubble and the particle, and if not too heavy the mineral will be levitated in the froth. With a few exceptions, all clean minerals are completely wetted by pure water. Thus the art of flotation consists in adding substances to the water to make a finite contact angle with the mineral to be floated, but to leave the other minerals with a zero contact angle. The contact angle concept and experimental measurements of contact angles have played important roles in flotation research for several decades.1-3 Nevertheless, there remain unanswered some basic questions as to the scientific significance of the contact angle and the nature of the processes by which flotation reagents affect contact angles.

Jan 5, 1954

By C. J. Allen, L. Battiston

"Introduction It has long been recognized by the hot-dip galvanizing industry that the characteristics of the galvanized coating can be influenced significantly by steel and pro cessing variables. Probably the variable of most concern to galvan izers today is steel chemistry. More specifically, the problem is the excessive reactivity of continuously-cast, silicon-bearing steels. In the past, structural steels processed by general galvanizers were in the low-to-medium ca rbon category and contained silicon at either low impurity levels (as with rimmed steels), or less than approximately 0.10% (as with semi-killed steels). The structures of the coatings produced on such steels are characterized by dense, compact layers of delta and zeta iron-zinc alloy phases and a distinct outer layer of eta zinc, which usually imparts a bright shiny appearance to the coating. The presence of silicon in steel, above the so-called semi-killed levels, is known to cause marked stru ctural changes in galvanized coatings. Such coatings are characterized by a relatively thin delta layer, a thick , coarse zeta layer and frequently an absence of the eta layer. The eta phase, comprising zinc which is carried out of the bath during withdrawal of the work, can be consumed by the continuation of the coating reactions until its temperature drops to the solidification point. This results in a dull grey and often mottled surface instead of the usually bright metallic appearance. These galvanized coatings are usually much thicker than coating specifications requ ire and they are usually more brittle and have poor adhesion to the steel. In service, these coatings tend to develop a rust-like discolouration. With the wider use of continuous casting by the steel producers and the associated additions of silicon in this process, the problem is becoming more important and receiving greater attention from the galvanizing industry ."

Jan 1, 1987

By D. Sotiropoulos

In the recent years, the mining sector is looking for specific indices, taking into account economic, environmental and social criteria, in order to meet the sustainable development requirements. In the present study traditional and environmental sustainable indices used in the Agios Dimitrios Power Plant, Northern Greece, are compared to those of ESKOM Company, South Africa, taken as reference. These indices are referred to, a) the solid fuels consumption, such as lignite, and, b) the emissions to the atmosphere, such as SO2, NO2 and dust. Last five years data show a remarkable improvement of all indices in the Agios Dimitrios Power Plant. Although the lignite used in this Power Plant is by far of poorer quality than that used by ESKOM - net calorific value 1272 and 4638 kcal/kg, respectively - dust emissions in both Power Plants are similar (52 and 31 g/kWh, respectively). The SO2 and NO2 emissions are very low in Agios Dimitrios compared to those of South Africa, respectively 1.92 and 7.91, and 1.74 and 3.61 g/kWh. This is mainly due to natural desulfurization (by the lignite?s calcium content) and the low NOx burners.

Jan 1, 2003

By Forsythe DJ, Sun S-S Andrew AS

Paragenetic, fluid inclusion, stable isotope, and 87Sr/86Sr and 143Nd/144Nd isotope studies of the Mt Carbine tungsten deposit in North Queensland provide information on the sources of the mineralising components and record the history of fluid-rock interaction during the hydrothermal process. The ore minerals , wolframite and scheelite , are contained in quartz veins which post-date the major deformations in the Siluro-Devonian Hodgkinson Formation . Mineralisation was immediately preceded by the emplacement of the Mossman Batholith (280 ¦ 7 Ma). Two major stages of mineralisation are present and separated by a brittle fracturing episode . The stable isotope and Sr and Nd isotope data suggest that the ore fluids during stage I and most of stage II mineralisation were a mixture of magmatic water and non-magmatic water (connate or metamorphic) which had experienced a long residence time and had extensively exchanged with the sediments at high temperature. Subsequent mineralisation events were dominated by fluids of meteoric derivation with a short residence time. The data imply that other solutes, such as W, were probably derived in minor part from local country rock sources with the major contribution coming from a magmatic source related to the granite batholith.

Jan 1, 1987

By Oleg I. Platonov

Method of high-temperature reduction of oxygen-bearing sulfurous gas has been developed at Copper Plant (CP) of MMC ?Norilsk Nickel? Trans-Polar Division (PD) with the aim of producing elemental sulfur from Vanyukov furnace? off-gas. Non-explosive reduction technology of oxygen-bearing sulfurous gas by methane utilized at Copper Plant has been designed to separate the processes of gas heating and sulfur dioxide reduction based on different kinetic of the reactions oxygen fixing and SO2 reduction. First, natural gas promptly reacts with oxygen contained in the process gas to heat a gas mixture up to the temperature of sulfur dioxide reduction (1200C). Then isothermal reduction takes place within 1 sec. Combustion chamber (pre-chamber) design developed based on the above principles is presented. Practical experience of the two reduction reactors operation at CP since 1996 proves high efficiency of the developed reduction process. The volume efficiency rises dramatically thanks to the fact that both fuel and reducing agent are fed into the reactor volume in the form of high-speed turbulent jets providing an intensive mixing of the reacting gases. On condition of equal internal volume of the reactors, the developed process offers higher efficiency of reagent interaction resulting in sulfur conversion exceeding 90%, as compared to the equilibrium one.

Jan 1, 2006

By Robert W. Waytulonis

Miners working in underground mines where diesel equipment is used are exposed to exhaust pollutants. These include carbon monoxide (CO), carbon dioxide (CO,), nitric oxide (NO), nitrogen dioxide (NO2), sulfur dioxide (SO2), hundreds of different hydrocarbons (HC) and particulate matter. Evidence from animal inhalation studies and limited epidemiological investigations have led the National Institute for Occupational Safety and Health (NIOSH) to recommend that ‘... whole diesel exhaust be regarded as a potential occupational carcinogen ...’ NIOSH further stated that ‘... the excess cancer risk for workers exposed to diesel exhaust has not yet been quantified, but the probability of developing cancer should be decreased by minimizing exposure…’ The International Agency for Research on Cancer(IARC) reached a similar conclusion, saying that ‘... diesel engine exhaust is probably carcinogenic to humans.’ Before these declarations, there was insufficient evidence concerning the carcinogenicity of diesel exhaust. It was well known, though, that diesel exhaust caused less severe problems, such as headache, eye irritation and unpleasant odors. In 1988, a milestone was reached in the Mine Safety and Health Administration (MSHA) regulatory process. An advisory committee recommended a three-tier approach to regulating diesels used underground-approval of diesel equipment, safety and health. Diesel particulate matter may be specifically regulated. In addition, ambient air quality standards are being proposed that will establish a new standard for CO2 and lower the permissible exposure limits for the NO2, CO, SO2 and formaldehyde emissions that originate from diesels and other sources. Additional safety and emission restrictions are also proposed for diesel engines in coal mines. The goal of the US Bureau of Mines (USBM) diesel engine research program is to minimize the health and safety problems associated with underground diesel equipment use. Part of this program is focused on reducing exhaust emissions from diesel-powered equipment used in underground mines.

Jan 1, 1993

By B. J. Sauer

Misapplication of ac induction motors for mine crusher and mill applications has long been a frustration for the driven equipment supplier and the mine operator. Proper selection of ac induction motors is critical to providing efficient production. This paper focuses on the selection of ac induction motors for gyratory crusher, conecrusher and grinding mill applications. The criteria for motor selection includes: proper enclosure, driven equipment torque requirements, bearing life, temperature rise, starting requirements, ambient temperature, altitude and accessory requirements.

Jan 1, 2002

By MacDonald W. L. F. C. A.

IN accordance with the usual approach to a participation in a panel discussion, this paper is, in some respects, intentionally controversial. I would suggest, how-ever that there is more than a grain of truth in many of the comments made. Before dealing with a particular problem. It is appropriate to set out a few of the more significant objective of an: accounting system: (1) The provision of historical data <•concerning past events, for the information of shareholders, tax authorities, etc. This data can also be used as a tool to predict the future. (2) The provision of a record to safeguard the company's assets and to form the basis of any claim for insurance or other damages. (3) The provision of an accounting framework in making an economic study of a proposed course of future action such as the development of an orebody or the outlay of a substantial sum for new equipment. ( 4) The

Jan 1, 1962

By David H. Carlson

The paper presents background information including data on diesel exhaust pollutants, amounts produced and standards, a desscription of mine characteristics that affect air monitoring techniques and a review of portable measurement techniques and instruments for gas and particulate matter sampling. A general review of the laboratory and field research being conducted at Michigan Technological University in the area of diesel emissions is presented. The facilities involved with this research are also described. These are the Experimental Mine, the diesel dilution tunnel test cell, the Mine Air Monitoring Lab (MAML), the portable instruments and the production mines used.

Jan 1, 1979

By Mike Johnson, Niels Verbaan, David Dreisinger

The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper.

Jan 1, 2014

J. A. MATHEWS, * Syracuse, N. Y. (written discussion?).-The reagent described by Mr. Archer seems to be a selective reagent, useful in one particular field. Nevertheless, the field is one in which it is likely to prove of considerable value, because there is a great deal of alloy steel FIG. 1.-ETCHED 1 HR. IN ARCHER&apos;S FIG. 2.-ETCHED 1 HR. IN ARCHER&apos;S REAGENT. PLOD 60. X 188. REAGENT. IZOD 10. X 188. heat-treated to approximately the properties mentioned in the paper. If it is found, by further tests, to be applicable to a wider range of compositions than merely chrome-nickel steels, for the most part discussed by Mr. Archer, its value will be thereby increased to just the extent to which it can be applied. In view of the fact that certain of these chrome-nickel steels, very similar in physical properties and hardness, show very different results in the Izod or notch test, and in view of the fact that when such differences are noted in the fracture the brittle steels usually

Jan 5, 1919

An investigation into the causes of variable sulphur content in blast furnace metal produced at No. 4 blast furnace at the Port Kembla works of Australian Iron and Steel Pty. Ltd. was carried out. Theprogramme included an extended and detailed experimental study of a great number of the operating variables of the furnace, on a cast-bycast or four-hourly basis, over fourteen days.Possible causes of the variation were found in irregular operation due to sinter variability, and it was also clearly shown that slag conditions were most important in controlling sulphur contents of pigiron. Some decrease in sulphur variability was achieved, arising partly from this investigation, and it is hoped to try magnesia additions to modify slag conditions for better desulphurizing.INTRODUCTIONSulphur in pig iron is a problem common to many blast furnace operators throughout the world, but the direct causes and means of overcoming them are functions of the available raw materials, and are hence more particular to each plant and its operating practice. Sulphur in hot metal influences the steel-making operations, the rolling operations and the quality of the finished steel. The main problem associated with high sulphur in steel is &quot;hot shortness&quot;, which leads to cracking of ingots and billets in rolling, to poor surface finish and to poor welding properties in the finished steel. On the other hand, sulphur is sometimes a desired additive to steel in order to promote free machining properties.Normal means of controlling sulphur A small degree of control of sulphur in steel is available to open hearth operators by alteration of slag volumes and basicity, but any large degree&apos; of sulphur elimination is...

Jan 1, 1961

By D J. McLane, J T. Rathbun, B T. Lusk

The dynamics of explosive detonations are understood, however recreating a real-world, full scale scenario is costly. The use of a shock-tunnel allows testing to be done on a smaller scale, with the simulated effect of a large explosion. Analyzing explosive waveforms using this method can greatly reduce cost in testing blast resistant products, such as anti-terrorism devices, mine safety products, and military equipment. The purpose of this paper is to better the understanding of how the waveform characteristics resulting from an explosive detonated within a shock-tunnel differ from those in an open-air arena test. The variables of comparison between an open-air arena test and those conducted within a shock tunnel are peak pressure, impulse, shock wave velocity, and cross sectional shape of the shock front. Understanding how these variables differ, tests utilizing a shock tunnel can be conducted with a higher degree of accuracy and repeatability.

Jan 1, 2013

Breakwater Resources Ltd is a Canadian base metals producer with Cu-Pb-Zn operations in Canada, Honduras, and Chile. Two of its operations contain economical gold levels which are recovered in both gravity and flotation concentrates. The gold payable terms in zinc concentrate are poor when compared to gold concentrates or copper concentrates and various flow sheets have been evaluated by Breakwater staff to maximise gold reporting in higher value products. The Myra Falls mine in British Columbia recovers coarse gold in the grinding circuit, part of which is upgraded and sold as a gravity-gold concentrate with the balance being directed to the copper concentrate. A sampling survey showed that there was potential gravity-recoverable gold in the copper regrind circuit. Installing a gravity concentrator in the copper regrind circuit increased the gold grade and recovery in the higher revenue copper concentrate and reduced the quantity reporting to the less well paid zinc concentrate. The El Toqui Mine in southern Chile has distinct high-and low-gold orebodies which are campaigned separately through the flotation plant. The high gold zone yields both a gravity concentrate and an unusual gold flotation concentrate. The gravity concentrate undergoes intensive cyanidation and electrowinning on-site to produce dore, while the fl otation concentrate is sold to gold producers. The zinc concentrate contains signifi cant gold values. The paper describes efforts over the past few years to improve gold returns at Breakwater&apos;s operations and highlights the different approaches dictated by the mineralogy of the gold occurrences at these two operations.

Aug 1, 2010

By Tomlinson R. C

The paper will briefly describe planning in the National Coal Board (NCB) and the contribution that operational research makes to it. It will then give details of some of the models in use and will finally consider critically the problems of looking ahead to the next century.

Jan 1, 1977