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By M. Boussuge, M. -D. Dupuits, A. Piant

This paper summarises a part of the work that has been essentially carried out at the Ecole des Mines de Paris in the framework of an Eureka European programme funded by the French Ministry of Industry, in partnership with Metaleurop and Carborundum (subsidiary of Saint Gobain). It deals with the measurement of different properties (density, thermal linear expansion, elastic modulus, strength) of a SiC-based refractory constituting the trays that are used in the refining columns in the New Jersey zinc distillation process, especially in the boiling section. These parameters have been investigated to check the homogeneity of the asreceived trays as well as to estimate the influence of ageing of the material under operating conditions. With this aim, specimens have been sampled in used trays having more than two years of operation. The as-received trays exhibited a good homogeneity, the strength being slightly lower in the direction in which they are compacted. Despite microstructural changes, most of the properties measured at room temperature are not significantly affected by ageing. High temperature tests involved thermal treated under vacuum to remove metallic zinc before testing at high temperature. An increase in temperature, as well as ageing, induces a decrease in the elastic modulus and strength.

Jan 1, 2000

By Jose Lara

SIDOR has developed a setup model for a roughing mill with edger that optimizes the position of the edger for a better control on the width, optimizes the efficiency of the mill for controlling of the profile of reductions and increments of the speed rolling and improves dimensional performance. This model consider as data entry, the number of passing, incoming and finish thickness and width, hardness and temperature of the material. The setup model is based on the equations of Ekelund for the width spread calculation and estimates of the rolling force. Additionally this model employ a Newton's algorithm for resolving the optimal position of the edger. The preset values calculated by setup model is the horizontal screw position, vertical screw position (edger), threading and rolling speed, some parameters calculated for the correction of ski. In the revamping of the roughing mill of hot rolling of SIDOR, C.A, carried out in January of 2005, it was implemented this setup model and the coefficients and parameters were adjusted for the first 15 days. Starting from there the values of preset, send to roughing mill are calculated by this setup model. The current indicators show an enhancement of 18% in the roughing mill effectiveness and a decrease about 37% in the mill stop by overload in the motors.

Jan 1, 2006

By A. V. Tarasov

The natural resources of lead and zinc are primarily constituted by polymetallic and lead-zinc ores. Beneficiation of these types of ores to produce standard nonmetallic concentrates inevitably results in an increase in the loss of base and precious metals with tailings. An improvement in the grades of lead and zinc concentrates can be achieved by re-cleaner flotation, but it results in production of intermediate products (middlings) to which substantial amounts of lead, zinc, copper and precious metals report. Without an appropriate technology for treating such intermediate products, the recoveries of valuable constituents from lead-zinc ores would remain unsatisfactory. A process has been developed in the Gintsvetmet Institute for processing of polymetallic intermediate products produced at the ore beneficiation plants. This process is based on electrothermic smelting to produce lead bullion containing precious metals, commercial-grade copper-lead matte and high-zinc slags (up to 15-20% Zn) from which zinc can be extracted by slag-fuming or Waelz process. Tests have indicated that the recovery of lead from intermediate products into lead bullion and matte is about 83-85% and 13-14% respectively (the total recovery is 97-98%), while copper recovery into the matte and zinc recovery into the slag is 90-92% and 95-96% respectively. Precious metals (about 96-97%) report into the lead bullion.

Jan 1, 2006

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Huang Rui

The coal asphalt is combusted at different temperature in a heating cabinet with the temperature limit by 1200°C. By comparing the mass of the remainder of each experiment, the completely combusting temperature of asphalt smoke can be determined. Based on the experimental process of asphalt smoke, a discrete mathematical model of the asphalt smoke combustion is set by theoretic analysis. Through computer programming, the dynamic combustion process of asphalt smoke is calculated to simulate the experimental model. The result of experiment shows that coal asphalt can mostly react upon 500°C and the mass of remainder is 49.41% to initial mass of sample in the condition. The computing result shows that the temperature and the concentration of asphalt smoke influence its burning temperature approximating linearity. The consumed quantity of fuel to ignite the asphalt smoke needs be considered with the two factors.

Jan 1, 2006

By R. M. Luna-Sánchez

Electrochemical studies, particularly Evans? diagrams, have been employed in hydrometallurgy to simulate and explain the redox phenomena that take place at mineral and metal surfaces during operations such as leaching and cementation. However, despite their utility, in some cases, the combination of the cathodic and anodic branches, determined separately, does not reproduce the chemical environment present when both processes occur simultaneously on a specific surface. In the present paper, limitations of Evans? diagrams are analyzed through two examples: silver sulfide cyanidation and gold cementation on zinc. In both cases, the surface kinetics are sensitive to the local pH and cyanide levels. When the electrochemical oxidation of silver sulfide or the reduction of gold are performed in the absence of its corresponding redox reaction, the local pH obtained does not simulate the real situation and the combined reaction kinetics may be very different from those determined from the Evans? diagrams.

Jan 1, 2003

By Cam T. Nhan

The potential use of coal fly ash as a construction material has been recognized for many years,. In this work, an admixture of the ash residue is investigated for use as a landfill liner. In particular, its performance as a chemical barrier to the leachate from the municipal solid waste (MSW,) is determined. The test specimens are a water compacted admixture of class F fly ash, low in calcium content, which is blended with lime dust and calcium bentonite. MSW is passed through the compacted fly ash specimens under a gravitational head. The. diffusion of elements in the leachate through this material is monitored as a function of time. The distribution profiles of the retained elements in the compacted admixture provide prediction of the long term performance of the compacted admixture directly affect the leachate diffusion rate, hence, the mobilities of the retained elements.

Jan 1, 1992

By Thomas Niehoff, Dave Stoffel

"Energy in the form of natural gas, oil and electricity is expensive and will continue to be a rare resource in the future. Recycling of metals, instead of primary production, is a logical and crucial step towards energy conservation. Energy consumption can be impacted by using advanced combustion systems for metals recycling. Air-fuel combustion has been the conventional method to melt and recycle metals. Global competitive pressures, “greenhouse” gas emissions, and high energy prices force melt shop operations to optimize energy usage and reduce overall operating costs. Oxy-fuel combustion and process technology can be applied to metal recycling operations to meet these objectives. Linde has converted several hundred furnaces from air-fuel to oxy-fuel technology and has extensive experience in optimizing the use of oxygen in furnaces. Additionally, Linde has the process knowledge necessary to avoid costly start-up issues that can accompany the transition to oxy-fuel technology. This paper will describe the benefits and potential issues for conversion to oxy-fuel.IntroductionThe furnace combustion system is the heart of a fossil fuel fired melting process and must be properly matched to the furnace to work as one cohesive unit. Furnaces vary widely in size, shape and features. Rotary furnaces are barrel-shaped and can be designed for tilting or nontilting operation. In a rotary furnace, the products of combustion create a single or double pass through the furnace prior to exiting. Reverberatory furnaces are box-shaped and can also be designed for tilting or non-tilting operation. Reverberatory furnaces are constructed of single or multiple chambers, with or without metal bath movement, and designed for continuous or batch processing. Different furnaces are used for different feedstock materials and products.Furnace combustion systems also vary in many ways. Combustion systems can be of air-fuel or oxy-fuel based technologies, or a combination of the two, resulting in an air-oxy-fuel system. Each of these types of systems has different combustion characteristics which can produce very different results. Here we will describe specific differences in melting processes and their associated energy requirements."

Jan 1, 2009

By Adam Gesing, Ron Dalton, Richard Wolanski, Larry Berry, Christopher Stewart

As the quantity of aluminum recovered from shredder scrap continues to increase, together with increased content of aluminum in automobiles, so does the economic incentive to further upgrade shredder scrap. This upgrade will be done by sorting and recovering the aluminum by specific usable alloy compositions. The metal recycling industry infrastructure needed to deal with the increased aluminum scrap supply already exists. It is an inverted pyramid structure that in North America comprises: 3000 scrap collection yards, 200 shredders, a dozen sink-float plants and one heavy metal sorting operation. The technology for upgrading aluminum sorted from shredder scrap is already either in industrial use or in the final stages of pilot plant development. However, the current automotive aluminum recycling infrastructure will need to adjust to deal with higher volumes of the metal from aluminum-intensive vehicles that will be appearing in shredder scrap -20 years from now.

Jan 1, 2000

By Andreas Dietrich

Laser off-gas measurement of CO, O2 and temperature has been carried online in EAFs. A visualization screen shows the values of CO and Oxygen and temperature for the entire heat, and includes the status of furnace equipment. The historical data of the heats are stored such that the furnace performance can be evaluated and optimized. A short comparison between laser based and conventional systems has been carried out related to speed, influence of dust, water, pressure, protection for bag house explosions. A high water and/or dust content in the sample does not represent a problem for this type of system. The measurement method works without interruption even under worst conditions such as dirty scrap, carbon injection etc. The installation was developed in conjunction with Marienhuette, Graz. They are 100% scrap based with a tap to tap time of ca. 46 min. Keywords: Laser Measurement, Off Gas, CO, O2, Temperature

Jan 1, 2003

By Bernd Kos

The management of waste materials in the aluminum industry is as important as in other basic industries. Due to the high value of the-by products of the melting process and their toxic properties we took the challenge to develop a process technology to reduce the environmental impact and to help industry to get a better yield of their by products/raw materials. In melting operations metal losses due to oxidation are nearly unavoidable, the amount of such losses, however, can be controlled. Aluminum dross actually is a by product and any shop would like to get rid of it in the most economic way. This by product still contains up to 70% valuable metal! In the present work we describe possibilities to separate metal and residues for further processing. Recycling of metal concentrates, selling of dross and dumping of the residues have been the typical solutions up to now. But there are technologies available which are designed to reduce the waste to a minimum or even avoid it altogether. Such alternatives are processing of the dross into materials which can be reused in other industrial processes in order to avoid any dumping. This can be done by separating the metal and the residues by centrifuging and further use of the residues in the chemical or refractory industry. ECOCENT means economical and ecological recovery of aluminum by centrifuging of hot dross. This process, developed by FOCON Austria, is based on the idea of treating the hot dross as quick as possible in a single operation to avoid exothermic losses, intermediate storage and unnecessary handling as well as to save energy. In the ECOCENT process the hot dross is fed without any fluxing salt additions into a converter where the relevant parameters for separation, like temperature and viscosity, will be adjusted. Further big lumps of dross are ground into smaller pieces in order to improve the later separation of the metal. After homogenizing and adjusting the temperature, the hot dross is poured as quickly as possible into a centrifuge. In the ladle or alternatively the mould of the centrifuge the centrifugal forces are used for the separation of aluminum from aluminum oxide, the major constituents of dross. The separated pure metal can either be discharged liquid or as solidified aluminum ring. The design of the device for the production of liquid or solid metal is almost identical. As soon as the centrifuging is finished the liquid aluminum can be poured back into the furnace or can be used for ingot pouring. After the pouring of the metal the "dry" residues are removed just by turning the ladle. Alternatively the aluminum solidifies in the mould and is discharged as a compact ring. The separation of the residues from the aluminum ring is automatic. Due to the batchwise operation the composition of the metal is the same as in the skimmed furnace of origin. The complete treatment cycle needs about 40 minutes. The recovery rate of aluminum is better than 90% of pure metal. This technology is highly flexible by its nature and can easily accomodate various operational requirements. The consumption of energy is more than 50% lower compared to conventional dross processing as the ECOCENT process is using the inherent energy of the hot dross. These extremely good results are not dependent on the aluminum content of the dross even from very dry dross most of the metal can be recovered. The main advantages compared to conventional dross processing are the high recovery rate, the known analysis of the metal and the immediate reuse of the recovered aluminum. The high recovery rate and the pure metal result in a short amortization period. The compact ECOCENT unit needs a minimum of space since extensive handling can be avoided. The electronically controlled process needs no cooling water and is simple, safe and environmentally sound. The residues are free of fluxing salts, their content of metallic aluminum is low and the environmental problems are thus greatly reduced.

Jan 1, 1995

By Peter Forschner

Classical Mixing Theory is based on applying many fundamental correlations to standard baffled dished bottomed vertical cylindrical vessels with high degrees of symmetry. Horizontal autoclaves operating at elevated temperatures and pressures have been used for more than two decades. All compartments and especially the first and last compartments are asymmetrical. To date no comparison of the effects of the asymmetric geometry on mixing system design and scale-up has been published. The results of investigating solids suspension, mixing time, momentum transfer from the impeller to feed slurry and feed inlet location in the first autoclave compartment are presented as influences on residence time distribution. CFD modeling was developed and verified with the test apparatus.

Jan 1, 2003

By Min Zhu, Yu Ji, An-chao Ren

"After being welded in the weld plant, the 100-meter heavy rails with the specification of 60kg/m are found broken during the straightening process in four planes. Failure analysis is made using the optical microscope and SEM with the result showing that the broken rail contains the imperfection of protrusion which exists at the edge of rail foot, about 1 00mm away from the rail end. When the protrusion is peeled off by deseamer from rail surface, cold scratch is generated which causes the rail to be broken during the subsequent straightening process. By adjusting the roll diameter differences between top and bottom roll of universal finishing mill and the height of pass line, it is possible to maintain the rails flat when leaving the mill. This prevents the upsweep and downsweep phenomena and, thus, the imperfection of protrusion can be eliminated. IntroductionThe development of rail transit worldwide has entered into a new era since the 1960s. The hi-tech rail transit system has gradually gained recognition over the world. In particular, the emergence of new-type passenger trains represented by TGV of France, ICE of Germany and Shinkansen of Japan and heavy haul trains as well, has revealed the charming way and more prosperous future of the modern and hi-tech rail transit system to the people all over the world. It should be pointed out that rail transit system is still the most effective solution to traffic jams among urban cities and in the central cities during the 21 '1 century, especially high-speed railway and subway which take overwhelming advantages over air transport, marine transport and road transport in terms of high speed, high efficiency, safety, comfort, environment protection and high flow. With the trend of increasing speed and heavier load of trains, higher product quality of rails is demanded. The rails for passenger dedicated lines require high cleanness, high accuracy in size, high flatness, high surface quality and large size (100-meter fixed length). The rail quality has direct influence on the operating performance of rail and railway traffic safety. The 100-meter heavy rails with the specification of 60kg/m are broken subject to the straightening process in four planes after being welded in the weld plant. This paper analyzes the reason for rails being broken and provides the theoretical proof for determining the rolling process."

Jan 1, 2013

By Mark E. Schlesinger

A substantial database exists for the thermodynamic properties of many antimonide compounds, but these have rarely been compiled or critically discussed. An abbreviated version of a full?scale review of the thermodynamic properties of binary antimonide compounds is presented, focusing on the choice of experimental techniques.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By L. A. Kazanbayev

The Chelyabinsk Electrolytic Zinc Plant (CEZP) was commissioned in 1935. Over the elapsed years the Plant capacity has been increased from 10 thousand tons of zinc (1935) to 150 thousand tons of zinc (2005). The paper describes the Plant main achievements in production updating for the last 10 years.

Jan 1, 2006

By Kurt Westerlund

Cooling of hot sticky gases with solids in a circulating fluidized bed called FLUXFLOW is described. Fluxflow is used for gas streams from metallurgical reactors, e.g., Isasmelt copper in Australia and TBRC for lead in Sweden. The features and potential of this technology in metallurgy and waste treatment ie described. The FluxfLow la a new, cost efficient high availability solution to treat hot sticky gases that has made new gas handling and heat recovery flow sheets available to the process industry.

Jan 1, 1994

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006