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By J. L. Hill, M. A. R. Sharif, J. Lin

"A numerical algorithm has been developed to simulate the movement, breakup, and entrapment of the oxide film inclusions encountered during the mold-filling processes of aluminum castings. The flowfield is solved using the well-known Marker and Cell (MAC) method by a time marching process. The Volume of Fluid (VOF) method is used to track the free surface boundaries. A kinematic approach is employed to track the movement and breakup of the oxide films on the free surface or in the bulk liquid metal. The computer program based on the proposed algorithm is able to model the flow behavior and oxide film movement, breakup, and entrapment in mold cavities for aluminum castings.IntroductionMetallographic and fractographic studies of the aluminum castings show tangled networks of oxide films in the castings. These oxide films can form in the furnaces or during the mold filling processes. Green and Campbell [I] concluded that the oxide film defects dominate the strength of aluminum castings. The main cause of oxide film entrapment into the bulk molten metal during the casting processes is the surface turbulence. In film-forming alloys, if the surface breaks, due to a drop, a fountain, or a breaking wave, then the surface film is folded over and incorporated into the bulk liquid. The incorporation of surface films leads to cracks in the casting and other defects that are nucleated by the presence of the folded films, such as porosity and hot tears. Campbell [2] estimated that up to 80% of scrap in light-alloy casting is the result of surface turbulence."

Jan 1, 1999

By H. -Peter Sattler

The laser sorting technique for replacing the handpicking of the non-ferrous metal scrap from auto shredders was first introduced 1990, The process is based on the use of atomic emission spectroscopy induced by lasers to identify the scrap particles and sort them with adequate systems into main fractions of Al-, Zn-and Cu-alloys, stainless steel and lead, In the meantime the handling technique for the scrap, i.e. the singling and sorting technique as well as the analytical detector were further developed for more efficiency and higher reliability, i,e. less maintenance, minor sorting errors etc. These developments were mainly based, on and initiated by operational experiences from the startup phase of a first production plant. Part of the on going research work was the development of an ,aluminium detector which makes it the first time possible to sort mixed aluminium scrap automatically into specific alloy fractions.

Jan 1, 1995

By M. Jortikka

The smelting process of the old reverberatory furnace including its capacity has been improved over the years in different ways eg. with oxy-fuel burners, parallel reactors with the reverb or with various modifications of the reverb furnace itself. The future reverb modifications with old concepts are difficult or impossible as the increased copper losses in slag call for separate slag treatment and particularly the process modifications do not solve the environmental issues but instead mean unavoidable high capital and operating costs in gas cleaning and sulphur recovery. During the last decades improvement in process performance and increase in capacity of copper flash smelters has been achieved easily by substituting the pre-heated process air by highly oxygen enriched air. The flash furnaces of today, however, are inherently designed to operate with high oxygen enrichment. Further process improvement with a view to production costs and capacity increase as well as to the more stringent environmental requirements is possible with even higher oxygen enrichment. This, apart from the advantages it generates, requires improvements in and careful design of the feed system, concentrate burner, furnace cooling and the off-gas line as well as adaption of the flash converting instead of the conventional Peirce-Smith converters. A logical answer even for the revamping of the reverb smelters in the future is the total replacement of the reverb furnaces with flash smelting together with flash converting. This paper discusses the possibilities for future process improvements of the existing flash smelters taking into account the process concepts, equipment modifications and capital aspects not forgetting the environmental issues. The revamping of the PASAR smelter in Philippines is introduced as an example of a recent success story.

Jan 1, 1994

By Carole Read

Hydrogen is under consideration by several countries for its potential as an energy carrier for transportation applications. In order to compete with vehicles in use today, hydrogen-powered vehicles will require a driving range of greater than 300-miles in order to meet customer needs and expectations. For the overall vehicular light-duty fleet, this dictates that a range of 5 to 13 kg of hydrogen be stored on-board (assuming a fuel cell power plant) within stringent system weight, volume, and cost constraints. Vehicular hydrogen storage thus constitutes a major scientific and technological challenge. To meet this challenge, the U.S. Department of Energy (DOE) initiated a ?National Hydrogen Storage Project? with roughly 40 universities, 15 companies and 10 federal laboratories, actively engaged in hydrogen storage research. Centers of Excellence in metal hydrides, chemical hydrides, and carbon-based materials have been established, as well as independent university and industry projects in the areas of new concepts/materials, hydrogen storage testing, and storage system analysis. Recent technical progress in each of these areas is discussed, as well as collaborative hydrogen storage activities under the recently established International Partnership for the Hydrogen Economy (IPHE).

Jan 1, 2006

By Jae-Woo Ahn

Waste acids containing phosphoric, acetic, nitric and hydrofluoric acid were produced during the etching process of liquid crystal display and semiconductor manufacture. In recent years, the attention on the treatment of industrial waste acids has been increased considerably according to the reinforcement of the environmental regulations as well as the implementation of the economic considerations about the waste acids. Fundamental studies on the separation and regeneration of the mixed waste acids were conducted using Cyanex 923, Tri-octyle phosphate and 2-Ethylhexyl alcohol as an extractant by solvent extraction. It is considered that the extraction of liquid crystal display waste acids with Cyanex 923 and Tri-octyle phosphate, semiconductor waste acids with 2-Ethylhexylalcohol is applicable for the separation and recovery of acid. Finally, the acceptable recycling process from the multi-component waste etching acids was proposed.

Jan 1, 2006

By Moto Goto

Today, Pierce-Smith converters, coupled together with various types of smelting units, are used in most of the world's smelters, However, due to the "batch" processing nature, and problems associated with fugitive emissions during the transfer of melt and blowing stages, this arrangement will unlikely be adopted in future smelters. Modern day alternative processes include the Mitsubishi Process, Outokumpu Flash Smelting and Flash Converting Process, the Noranda Process, and the Ausmelt Process, but only the Mitsubishi Process is a "truly continuous" smelting and converting operation, producing a constant flow of blister without tapping, and is economically proven by long term commercial operations. This paper reviews recent advances in modern continuous converting technologies, with a special section devoted to operation of the "first standalone Mitsubishi C-furnace" coupled together with a Noranda Reactor, at Port Kembla Copper Pty, Ltd. in Australia.

Jan 1, 2003

By V. Gornitz

The Orphan mine uranium deposit, Grand Canyon, Arizona, is a cylindrical collapse-breccia pipe, 70 to 150 m in diameter and 500 m deep. Pipe fill was derived from the Supai Group, Hermit Shale, and the Coconino Sandstone. Uraninite, with Cu, Fe, Pb, Zn and Ni-Co sulfides is concentrated along the pipe boundary ring fracture (annular ring) and within the central porous sandstone matrix. There is some suggestion of vertical and lateral zonation of U with respect to Cu. Reduction of ferric oxide cement from red beds and recrystallization of carbonate, with formation of kaolinite preceded major ore deposition. Early Ni sulfides, arsenides and disseminated pyrite were followed by massive pyrite, and botryoidal uraninite, which in turn was suc-ceeded by Cu, Zn and Pb sulfides. A second, later generation of uraninite was closely intergrown with hematite and base metal sulfides. Oxidation of primary minerals may have been associated with Tertiary regional uplift. The paragenetic sequence closely resembles that of other Grand Canyon breccia pipes, except for the extensive development of the distinctive uraninite-hematite association. Mineral assemblages at the Orphan suggest possible mixing of the metal-bearing solution(s) with a more oxidized fluid, containing soluble uranyl complexes. Homogenization temperatures of fluid inclusions in calcite (GO-lIO?C) at the Orphan fall within the lower end of the range observed at other breccia pipes.

Jan 1, 1987

By G. S. Hanumanth

Sedimentation of particles during the liquid metal processing of particulate metal-matrix composites can affect the homogeneity, and thereby the properties, of the cast product. A novel electrical probe has been developed to measure the in-situ volume fraction of ceramic particles in molten metal baths. Using this probe, sedimentation rates for 90 pm silicon carbide particles dispersed in molten aluminum A356 alloy were measured over a wide range of particle volume fraction, 0.05 to 0.3. The sedimentation rate was found to depend strongly on particle volume fraction; the time to clarify a 0.15 m depth increased from approximately 60 to 500 seconds as the volume fraction increased from 0.05 to 0.3. Measured sedimentation rates agree well with the predictions of a sedimentation model based on one-dimensional, two-phase flow theory in which the inter-phase drag function is derived from the momentum equation, utilizing the Richardson-Zaki Equation for sedimentation in aqueous systems. The implications for solidification are discussed.

Jan 1, 1993

By A. Rosenfeld

The feasibility of applying laser induced optical emission spectroscopy to the high speed sorting of mixed alloy aluminum scrap is investigated. The basic spectroscopy for analysing aluminum alloys for the major alloying elements over their full concentration ranges is established. Materials handling issues are also described and the components of an overall sorting system are presented.

Jan 1, 1995

By Patrice Chartrand, Halvor Dalaker, Philippe Ouzilleau

A size-dependant thermodynamical model for the carbon-hydrogen previously developed by Ouzilleau et al. [1] has been expanded here to include chemisorption of methyl groups. Gibbsenergy minimalisation calculations using FACTSAGE software on this model indicates that hydrogen bonding through methyl groups is energetically favoured as an intermediate between bonding as monoatomic hydrogen to edge hexagons (which is more favourable) and as monoatomic hydrogen to corner hexagons (which is less favourable). The model has also been applied to methane decomposition and oxide reduction using natural gas. A C-H solid solution as a thermodynamic description of the solid carbon phase influences calculations of carbon activity in metastable methane, and gives different results than when using graphite.

Jan 1, 2015

By Jose Luis Lopez Mendez

In May 1992, MEXICANA DE CANANEA, S.A. DE C.V. finalized the life of its Reverberatory Furnace which lasted 16 years. This created the need to prepare the Smelter for the next campaign.

Jan 1, 1994

By Michael L. Sorokin

The metallic nickel production by converting of nickel matte is analysed from the thermodynamic point of view using earlier developed thermodynamic models for sulphide, metal and slag phase. Three-suffix Margules equations are used to calculate thermodynamic properties of melts. Potential diagrams of Ni-FeS-OSiO2 system are calculated for various temperatures and Fe to Ni ratios. The diagrams used for consideration about possibilities of the direct one-stage metallic nickel production.

Jan 1, 1995

By Howard K. Worner

"In a rewarding career spanning nearly two thirds of a century, the author has worked at the frontier of such diverse fields as the creep of metals, structure properties and production of novel dental and surgical materials, molten salt electrolysis for titanium production, greatly improving the productivity of large iron blast furnaces and of oxygen steelmaking. While each of these has given great satisfaction, special thrills have derived from the development of new methods for the continuous production or refining of both ferrous and non ferrous metals. A rewarding segment was the evolution of various aspects of WORCRA technology. Unfortunately, several of these inventions have been ""ahead of their time"". Introduction""I am greatly honoured by the convening of this meeting to recognise my contributions to pyrometallurgy. My appreciation is the greater because this is the third Howard Worner Symposium; the first took place in the University of Newcastle in 1988, close to my 75th birthday. It was arranged by the local branch of The Australasian Institute of Mining and Metallurgy with the theme, ""Frontiers in Pyrometallurgy"". The second was organised by the University of Wollongong in conjunction with the Australian Academy of Science and the Australian Academy of Technological Sciences and Engineering; it celebrated my 80th birthday and, at my request, covered a broad range of topics under the heading of ""Recent Advances in Science and Technology"". Now, this very international meeting on ""Injection in Pyrometallurgy"" has been convened by the G K Williams Co-operative Research Centre for Extractive Metallurgy in my alma mater. I am both delighted and honoured that the cosponsors are the TMS (USA) and ISIJ (Japan).Dr Madhu Nilmani consulted me about the field to be covered and I readily concurred because ""injection"" has been of keen interest to me since the beginning of the 1960s when I began my pioneering work on sequential oxygen (or air) injection into flowing streams for both refining of blast furnace hot metal to steel and for the continuous smelting-converting of copper and nickel."

Jan 1, 1996

By Li. Jiarong, Zuojian Liang, Qingyan Xu, Baicheng Liu, Shizhong Liu, Hailong Yuan

Single crystal solidification of turbine blades is a key technology for the production of reliable and high efficiency gas turbines. The solidification process of single crystal investment castings causes a number of problems that have to be solved such as the increase of casting defects and complexity of production process. Computer modeling and simulation is helpful to predict the defects and improve the process design. In the paper, a mathematical model for three dimensional simulation of solidification and single crystal growth of investment castings was developed based on CA, mechanism of crystal growth and basic transfer equations such as heat, mass transfer equations. Many factors including constitutional undercooling, curvature undercooling and anisotropy, which had vital influences on microstructure evolution, were considered in the model. Temperature, crystal growth interface and structure defects of investment castings of single crystal superalloy were investigated at withdrawal rates of 4.5mm/min and 7mm/min. Simulated results showed that microstructure evolution and structure defects were predicted reasonably and calculated results were coincident with experimental ones. The study indicated that three dimensional solidification simulation technique is a powerful tool for understanding the fundamental of solidification and the formation of structure defects in single crystal investment castings and finally for optimizing process design.

Jan 1, 2004

By Kent D. Peaslee

When supersonic oxygen jetting is used in electric furnace steelmaking, the lance jet axis is typically inclined at larger angles to the vertical than is used in basic oxygen steelmaking. The supersonic jet is important not only for refining the steel, but for sustaining the foamy slag in the electric furnace. Physical modeling was carried out using a room temperature, two-dimensional slice apparatus in which mercury represented the metal and water-glycerol the slag. High speed video photography with image analysis was used to study the effects of the angle of inclination on the slag/metal bath. Mathematical modeling using FLUENT provided a method of predicting flow patterns and the trajectories of drops injected at various points in the flowfield. A one-half scale water model of the system, in which lance heights, angles, and flowrates simulated those encountered in steelmaking operations, was used to provide a better understanding of some aspects of the oxygen blowing process in electric furnace steelmaking.

Jan 1, 1994

By Andrew B. Suttie

The lead-acid battery recycling industry was seriously affected during the 1980s by increasing environmental protection costs and poor lead prices. The process is now being repeated in the 1990s causing further difficulties, for recyclers. In Europe, many lead-acid battery recycling plants use rotary furnaces. The Darley Dale smelter, redeveloped between 1984-87, uses only rotary furnaces. A review of options for this plant has been completed and 'concluded in favour of further investment to exploit more fully the benefits of rotary furnace technology.

Jan 1, 1995

By A. D. Zunkel

Increasing amounts of electric arc furnace dust (EAFD) are being generated worldwide as more steel is produced from electric furnace melting of galvanized steel scrap. In most countries, the management of this material is a costly technical, economic, and legal problem for minimill steelmakers. Many technologies and processes are being developed and implemented worldwide to manage this material to recover contained zinc, lead, and iron values and render it nonhazardous. These processes are pyrometallurgical, hydrometallurgical, or hybrid in nature. Some produce zinc oxide, some zinc metal, some lead metal, and some lead cement. Some are successful, some have failed, many are dormant. or abandoned, and others continue to be developed and emerge. This paper updates the current status of 20-30 processes in various stages of commercial application and development used worldwide to manage EAFD and recover its nonferrous, particularly zinc and lead, and ferrous values.

Jan 1, 2000

By Rikiya Kamezawa, Rudiono, Manabu Takeuchi

"Schottky type solar cells based on phthalocyanine (Pc) thin films were fabricated, and their photovoltaic performance was investigated in various ambient atmospheres. Most of cells prepared in this study showed a good rectification and photovoltaic effects in the visible wavelength region. The introduction ofN02 gas into the measuring chamber was confirmed to increase the current both in dark and under light illumination. However, chemical reaction between the Al electrode and N02 formed some oxide and deteriorated the Schottky barrier, resulting in an increase in cell resistivity. SF 6 gas also showed similar effects on the cell performance.IntroductionPhthalocyanine is one of the typical organic semiconductors, which shows high photoconductive sensitivity in the visible to infrared region. Today, several kinds of metal phthalocyanines are used in electrophotographic photoreceptors. In addition, application of phthalocyanines to solar cells have also been trying by many workers [1, 2]. Many efforts have been made for improving performance of phthalocyanine solar cells by modification of device structure [3, 4], doping by dye or pigment [5, 6] and incorporation of metal clusters [7]. It is known that electrical conductivity in phthalocyanine is increased by adsorption ofNO2 [8, 9]. We tried to improve photovoltaic performance ofphthalocyanine solar cell by adsorption ofNO2. This paper describes the influence of N02 adsorption on the photovoltaic behavior of phthalocyanine solar cells."

Jan 1, 2000

By Christopher M. Moore

DK Recycling und Rohelsen GmbH converts 380 000 annual tonnes of iron containing waste materials Into pig Iron. Zinc Is the main reason that these materials are classified as waste. The materials are processed In the conventional way by making sinter which is then smelted in a blast furnace to foundry grade pig iron. The trick lies not in the unit operations which are quite standard but rather In the modifications made to the plant and operating procedures to cope with the much higher levels of tramp elements.

Jan 1, 1995

By H. K. Lin

Pyrite oxidation in chloride solutions was investigated with cyclic voltammetry, ac impedance and potential step techniques. The pyrite oxidation in quiescent electrolytes is irreversible and controlled by diffusion. Depression of the semi-circle in the complex plane plot has been explained mathematically based on the concept of the equivalent circuit. When the semi-circle is depressed, the mathematical formula indicates that the reaction resistance should be obtained from the intersection of the semi-circle with Z-axis instead of the semi- circle diameter. The peak charging current densities at 1.10 and 0.90 V vs. SHE obtained from the equivalent circuit coupled with the ac impedance measurements match the peak current densities obtained with the potential step measurements.

Jan 1, 1997