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By C. D. Chapman

Current regulations regarding the landfill disposal of asbestos containing wastes are inadequate to ensure there are no ground water or airborne emissions. Accordingly, there is growing recognition that asbestos wastes can only be safely disposed of by using techniques that destroy the hazardous fibres. An innovative high-temperature plasma arc technology (The MAGRAM Process) is being developed for the recovery of magnesium metal from asbestos together with supplementary magnesia containing feedstock. The furnace will operate in. open bath mode with aluminium and/or ferrosilicon being employed as reductant. An important advantage of the process is that magnesium vapour within the furnace will be generated close to atmospheric pressure rather than at reduced pressure under which existing processes operate. Thermodynamic modelling work has been undertaken to define the range of slag composition and furnace temperature under which magnesium production at atmospheric pressure is feasible. The effect of slag chemistry, reductant addition, and temperature on product quality and yield have also been investigated and key aspects have been tested on bench scale. A 300 kW pilot plasma furnace unit has been employed for the treatment of calcined asbestos wastes. Aspects of design and operation of the unit are detailed. Acknowledgement: This work is substantially financially supported by the European Communities under the Industrial and Materials Technologies (Brite EuRam H) Research and Development programme.

Jan 1, 1995

By W. -S. Hwang, R. A. Stoehr, P. Ingerslev

"The flow of molten metal entering complex two-dimensional foundry molds has been modeled using the Simplified Marker and Cell (SMAC) and Solution Algorithm (SOLA) techniques. The molds were for a series of four and three-spoke wheel designs. The computer calculations were compared to physical experiments in which molten cast iron was poured into C02-bonded sand molds. The metal was photographed with a high speed motion picture camera focused through a Pyrex glass window on one face of the mold. To get good agreement between the calculations and the experiments, it was necessary to accurately represent the velocity through the ingate. This was calculated by application of the Bernoulli equation to flow through the feed system. Some difficulties were experienced with mathematical instability, expecially in the three-spoke design with a narrow ingate. This was overcome by using 100% upwind differencing, and over relaxation parameter near 1.0 (i.e. no over relaxation), and variable mesh spacing.IntroductionModeling the flow of molten metal entering molds has the potential for making significant contributions to the design of feed systems. It will supply information to the computer-aided-design systems of the future that will enable the designer to optimize the placement of gates, dimensioning of passages, and designation of casting speeds. Such design criteria have generally been based on application of energy balance (Bernoulli equation) principles to flow in the sprues, runners, and gates. Indeed, this is the easiest way to determine the proper dimensions to give a suitable filling time for a casting of a given size. A number of computer programs, including one by some of the present authors, have integrated such calculations into CAD systems. l Modeling the flow of metal inside the mold cavity requires other techniques that will handle free-surface transient flow. Stoehr and Hwang reported on the application of the Marker-and-Cell (MAC) technique to mold filling problems at the previous conference in this series at Hennicker, N.H. in 1983. 2 Although considerable progress has been made since that time in improving the accuracy, stability, and convenience of these techniques, the shapes to which they were applied remained limited. Also, physical verification of the results of the calculations was limited to water models.The work to be reported in this paper was undertaken with two objectives: (1) to apply these techniques to more complex and realistic shapes, and (2) to verify the results by comparison with flow patterns observed in molten metal poured into actual sand molds."

Jan 1, 1986

By W. B. Carter, A. T. Hunt, G. W. Book

"Combustion Chemical Vapor Deposition (CCVDSM ), an open air, flame assisted CVD process, is under development. The CCVD process produces non-line-of-sight, epitaxial deposition. Materials deposited include YBa2Cu3Ox' Y2BaCuOx, BaTiO3, Y2FesOI2, ZrO2, yttria stabilized ZrO2 (YSZ), partially (yttria) stabilized ZrO2 (PSZ), and amorphous silica. Two modifications of the CCVD process are being studied. Liquid fuel CCVD deposition, involves the combustion of an organic solvent that contains dissolved reagents carrying the desired coating cations. Gaseous fuel CCVD deposition uses a flammable gas as fuel. A non-flammable solution containing dissolved reagents is either aspirated into the flame or mixed with the fuel gas as an aerosol prior to its combustion. Substrates to be coated are held near the flames' ends.IntroductionThin films and coatings can be deposited using a wide variety of techniques including chemical vapor deposition (CVD). CVD is ""a materials synthesis process whereby constituents of the vapor phase react chemically near or on a substrate surface to form a solid product.""lIn conventional CVD processing, gases carrying coating constituents flow into a reaction vessel where deposition occurs onto a heated substrate. The deposition process is often conducted at reduced pressure. Both cold and hot wall reaction chambers are used. Heat can be provided by a resistance furnace, rf induction, or high-intensity radiation lamps. Plasma, microwave, photo, laser, RF, and electron-enhanced CVD processes have been developed. The necessity of using a reaction vessel limits the substrate size and affects coating economics. Although most CVD depositions are performed as batch processes, continuous deposition can be accomplished with the use of appropriate hardware.The chemical vapor deposition of thin, dense oxide films has been accomplished in the open atmosphere with a flame assisted process. The process is called combustion chemical vapor deposition (CCVDSM).2 Two modifications of the CCVD process have been developed. The liquid fuel CCVD process involves the combustion of an organic solvent in which reagents (containing the coating cations) are dissolved. The gaseous fuel CCVD process uses a flammable gas as fuel. In this modification, a non-flammable solution containing dissolved reagents is either aspirated into the flame or mixed with the fuel gas as an aerosol of small droplets prior to its combustion. Substrates to be coated are held near the flames' ends."

Jan 1, 1994

By C. J. Parradies

During injection into a die, semi-solid metal alloys exhibit a shear-rate, history-dependent flow response. Simulating the injection of a thixotropic material requires that empirically determined boundary conditions and viscosity are specified as a function of both temperature and shear rate history. Experiments were performed using an industrial die casting machine that was instrumented with sensors to measure the pressure and temperature during the injection of a semi-solid aluminum alloy through a tube. This benchmark experiment was used to develop a simulation of the die casting process that could then be applied to more complex die geometries. The results of the experiments were analyzed using the exact, steady state solution for a power law fluid and simulations accounting for slipping at the boundary between the semi-solid metal and the die. Results indicated that the no-slip condition cannot be used to simulate the velocity boundary condition, because the measured pressure is much lower than that predicted by the models. An estimated apparent slip coefficient was introduced to account for the reduced pressure. During some of the experiments, a sudden drop in the measured pressured, prior to decreasing the ram velocity, coincided with observations of segregation in the form of concentric rings visible on the polished surface of cross-sections cut from material remaining in the tube.

Jan 1, 1997

By Metehan Erdogan, Orhan Gökçe Göksu, Ishak Karakaya

"An experiment (mixture) design was created to optimize the process parameters of the electrochemical reduction of CaW04 to W in molten CaCl2-NaCl eutectic mixture. Temperature, applied voltage and the length of Kanthal wire winding of the CaW04 pellets were selected as the process parameters that were allowed to vary between the predetermined minimum and maximum values. The rates of the electrochemical reductions were interpreted from the variations of current and total charge vs. time graphs under different conditions. The analysis pointed out that 640°C and 2.81 V resulted in the fastest reduction. Itwas seen that the effect of Kanthal wire winding on the output current was less pronounced when compared to the other two parameters.IntroductionFFC Cambridge Process [1] has been applied to a number of metal oxides in laboratory experiments to produce metals. In nearly all of these studies, the electrolysis temperature was around 900°C, the electrolyte was pure CaCl2 or CaCl2 containing salt solutions and the anode was graphite. However, it was recently shown that the electrochemical reduction process of metal oxides in CaCl2 containing electrolytes at the mentioned high temperatures was not suitable for tungsten production [2], It was reported that as soon as WO3 contacts CaCl2, the following reaction occurs:"

Jan 1, 2012

By W. Drummond

The cooling of smelter gases by air dilution, adiabatic evaporative cooling and indirect heat exchange is discussed with reference to the process, to the subsequent cleaning of the gas. and to the use of the heat extracted from the gas. The method of reducing the effect of acidic sulphide formation on the corrosive properties of the gas and the dust and the development of surface cleaning mechanisms?are discussed. The development of indirect recuperators using air, water or steam cooling, made possible by the control of surface fouling is traced. The application of the modern Waste Heat Boiler to the new sulphide smelting processes is discussed with respect to the natural and forced circulation concepts. Case histories are presented to illustrate mistakes made with respect to designs produced without recourse to sensitivity analysis and without an appreciation of "worst process? conditions".

Jan 1, 1992

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 J. Huot

It has been shown that magnesium-based metal hydrides such as Mg2Ni could be synthesized by high energy mechanical alloying. This process creates a nanocrystalline alloy that has enhanced hydrogen sorption properties due to the high density of defects and grain boundaries. Unfortunately, this process also requires a long synthesis time (up to 100 hours in some cases). In order lo reduce processing time and cost of synthesis, we have investigated the effect of milling at elevated temperature under an inert atmosphere. Milling at high temperature improves interdiffusion of the elements and reduces the number of structural defects such as vacancies, dislocations and internal strain. It was found that by milling elemental powders at 200°C. a complete synthesis of Mg2Ni could be achieved in 8 hours. This synthesis time is roughly an order of magnitude lower than that of the process conducted at room temperature. The hydrogen sorption kinetics and capacity of this material are comparable to Mg2Ni synthesized at room temperature.

Jan 1, 2002

By Cesimiro Fabian

The crystallite size of copper electrodeposits was determined by X-Ray powder diffraction analysis using a General Area Detector Diffraction Solution (GADDS) diffractometer. Crystallite size was calculated for copper thin films which were deposited on a 316 stainless steel rotating cylinder electrode (RCE) in the presence and absence of additive ?A?. The crystallite size was calculated from a corrected full width at half maximum (FWHM) of the [110] peak profile using the Scherrer equation. The test of significant difference on crystallite size was derived using Kruskal-Wallis method. It was found that in the absence of the additive the median crystallite size was 426, which decreased to 364 in the presence of the additive. As the additive degraded, the crystallite size increased to a size similar to that observed in the absence of additive.

Jan 1, 2003

By Roderick Guthrie

Gas injection into liquid steel baths is widely practiced, ever since the early days of Bessemer’s pneumatic steelmaking process. What has not been fully appreciated is the critical role of bubble sizes for delivering higher quality commercial steels than is presently possible. This was first proposed by Prof P. Hayes and his research group. Using a full-scale water model of a typical 4-strand Ladle-Tundish-Mold system, we demonstrate the potential advantages of modifying a typical ladle shroud, to generate microbubbles within the water flowing into the tundish. This is possible by taking advantage of high shear rates and turbulence kinetic energy available in that region. These microbubbles enhanced the removal of “micro-inclusions” (hollow glass microspheres) in the 5–50 micron size range, to the upper surface of the tundish. There, they were absorbed into an overlaying “slag” phase. Accompanying CFD studies confirmed that no microbubbles in the size range generated (500–900 μm), pass through the submerged entry nozzles into the moulds.

By Roger Agnew

Sulphide ores mined by Inco Limited in the Sudbury District contain small quantities of cobalt. During beneficiation, cobalt distribution to various streams is similar to nickel. After smelting, nickel is selectively extracted by carbonyl refining and the cobalt remains in the carbonylation residue. This residue is processed in a specialized hydrometallurgical plant to produce precious metal residues, copper cathodes, and a nickel- cobalt carbonate intermediate product. The nickel-cobalt is shipped to Port Colborne where the cobalt is separated as cobaltic hydroxide and refined to metallic cobalt. This paper deals specifically with the recently constructed Electro Cobalt Refinery. The cobaltic hydroxide is dissolved and residual zinc, copper and nickel are removed by ion exchange and organics by a carbon column. The purified cobalt solution is fed to the electrowinning circuit where cobalt rounds are produced on stainless steel mandrels. In the design and construction of the refinery, special attention was directed to materials of construction both for the process equipment and the physical plant, operating control and flexibility, and the quality of the working environment. The end result is an efficient and clean operation which yields a product of excellent quality.

Jan 1, 1988

By Anette Mueller, Thomas Schnellert, Sérgio C. Angulo

"The use of automatically sorting technique, to separate gypsum components from recycled material of processed construction and demolition waste (C&DW), is motivated by environmental and economical aspects. Only if the gypsum can be separated the aggregates can fulfill the environmental requirements and also the structural characteristics according to the standards. Furthermore, the separation of red brick can also improve the quality of the aggregates.This paper aims at analyzing the separation of gypsum components and red brick by using the color sorting technique. The impacts on the composition and the envelope density of recycled aggregates are described. Depending on the gypsum content the application of two processing stages (rougher-cleaner) can be necessary to produce aggregates with sufficiently low gypsum content. Additionally, the separation of red brick and concrete is successful. So, the color sorting may be a promising technique to upgrade the quality of mixed C&DW aggregates.IntroductionConstruction and demolition waste (C&DW) is a mixture of different materials. Such mixtures can be used only in low grade applications. If the material is used as certified material for road construction or as aggregate in concrete the concrete particles must be separated from the other building materials. This paper aims at analyzing the separation of gypsum components and red brick by optical sorting. The needed stages of sorting for getting a product quality according to the German Standards are deduced.Gypsum is a building material that is increasingly used for interior works in Germany like it is shown in figure 1 [1]. At present the content of gypsum in C&DW is estimated at about 1 %. Assessments on the basis of material streams of gypsum and concrete and their life spans show that higher gypsum contents of about 3 % must be expected in future [2]. Also in other countries the use of gypsum has grown considerably in the last decades. From the characterization of C&DW available in some cities in Brazil, 4 to 15 % of total amount of C&DW that may arrive at the recycling plant to be processed is excessively contaminated by gypsum. In one of these cities, the average content of gypsum in the C&DW before processing was as high as 2.1 % [3]."

Jan 1, 2008

By Daniel Adolfsson, Ryan Robinson, Fenwei Su, Jelena Blagojevic

"Cold bonded briquetting of steel plant by-products has proven to be a viable recycling alternative concerning technology, economy and environment in both the traditional blast furnace route and the direct reduction process. A critical parameter in cold bonded briquettes is the type and amount of binder used during production. The binder material must meet certain quality requirements concerning low and high temperature strength, chemistry and economy. Currently, SSAB Tunnplåt uses ordinary Portland cement (OPC) as binder in their cold bonded briquettes. In order to improve binder quality and possibly decrease OPC dependency, a binder feasibility study has been conducted concerning an internal by-product, ladle slag, as a supplement and/or partial substitute for OPC. Several characterization techniques have been used to study the behaviour of ladle slag, these include: XRD, XRF, SEM, glass content analysis, calorimetric analysis, particle size distribution and thermochemical stability considerations concerning the CaO-Al2O3-SiO2 system.IntroductionRecently, a project was initiated at SSAB Tunnplåt AB, in Sweden, which aimed at reducing the amount of ordinary Portland cement (OPC) as hydraulic binder in cold bonded briquettes by partly replacing it with ladle slag. OPC is traditionally used within civil engineering, and widely accepted as a hydraulic binder in a number of different applications. OPC consists of four major crystalline phases, i.e. C3S, C2S, C3A and C4AF. Tricalcium aluminate as well as the ferrite phase in OPC reacts very quickly with water, for this reason gypsum is added to the clinker in order to retard these reactions. The fact that gypsum is present in the system limits the recycling of briquettes to the BOF, since the presence of gypsum during steelmaking results in a significant amount of sulphur emissions. The latter along with the expense that follows, makes it worthwhile to consider alternatives for OPC as binder in cold bonded briquettes."

Jan 1, 2008

By F. Kassabji

This publication presents the main experimental and theoretical results on the recovery of aluminum scrap (dross and Used Beverage Can) without use of any addition of fluxing salts. Dross and UBC's processing experiments have been conducted in a rotary plasma furnace operating in the transferred and non-transferred mode, using different plasma gases. The investigation involved the treatment of more than 100 kg of dross and other aluminum residues using plasma torches with less than 100 kW power. The experimental work showed that this process is .far more economical and kind to the environment than the conventional route using a salt flux. An equilibrium thermodynamic calculation at elevated temperature makes possible the prediction of by-products at various temperatures for different plasma gases.

Jan 1, 1994

By Amy Nelson

In the electrolytic production of zinc, cobalt is removed from the zinc electrolyte by cementation with zinc dust prior to electrowinning. Although the thermodynamics for this reaction are favourable, kinetic barriers to cobalt reduction render the method almost useless in practice unless activators such as copper and antimony or arsenic are added. There is a large body of work studying the effect of these additives, yet the mechanism by which they act is still poorly understood. Even when the target conditions are met, zinc dust consumption is excessively high: satisfactory operation requires up to 300 times the stoichiometric amount of zinc dust. The objective of this work is three-fold: (1) to examine the effects of activators and elucidate the characteristics that make a good activator; (2) to identify new additives that could lead to a more efficient purification process; and (3) to test the new additives with synthetic and real electrolyte solutions. The present paper gives a status report on this project.

Jan 1, 1998

By Fabio J. Esper, Guillermo R. Martín-Cortés, Francisco R. Valenzuela-Díaz, Cassio P. Carvalho, Giorgio Grotti, Reginaldo B. Santos

"Rejected sands from smelting metallurgical process because contain lead and others heavy metals are a problem to dispose as waste in all the countries. A procedure that is being proposed for it is to incorporate it on common clay bodies in the fabrication of structural ceramic products as bricks, blocks and roof tiles. The main goal of this paper is to present the results obtained with mixtures of sands from smelting metallurgical process with common clay from Jundiaí, São Paulo, Brazil. Preliminary incorporation tests (1,0% in weight) were made with hand formed spherical samples. With the higher compression strength of the spheres after drying and firing (950ºC) experiments on bricks production were made for quality technological test. Seven hundred hallow blocks containing 1,0% waste were produced and presented ceramic properties similar to those without sand incorporation. Introduction In last the fifteen years the LMPSol - Raw Materials & Non-metallic Solids Laboratory – Metallurgic Eng. & Materials Depto. – Polytechnic School - University of São Paulo comes studying the possibilities of incorporate industrials waste materials to the production of bricks and other products of construction aiming at to remove pollution products of the environments and to user the properties of the same ones in the structural ceramics products. Examples are the study of the influence of rejected steel furnace dusts in structural ceramic [1], another example is the main subject of the present paper: use of rejected sand from smelting metallurgical process in the production of bricks an other products of structural ceramics. Antecedents More or less one year ago, specialist and members from the direction board of METALÚRGICA GROFE LTD. Company contacted researchers and professors of the LMPSol – PMT – EPUSP seeking for a solution to their concern with the disposal of rejected sand from smelting metallurgical process."

Jan 1, 2008

By Peter Sylvén, Darwin Morales

Despite being crucial for the smelting process, furnace tapping using oxygen lances has not been considered an operation that brings value. Therefore, these important tools have not seen a significant change in over 100 years. Problems related to the use of oxygen lances include: • Inaccurate tool: causing damages shortening the life of the taphole refractories. • Safety: extended exposure to the operator in an unsafe area of the furnace. • Cost: high oxygen consumption & high lance consumption. • Time consuming and frustrating to connect one lance to another. This paper will suggest a very good solution; new concept thermal lances. We will show how these provide an outstanding performance for a more efficient, faster and cost-effective furnace tapping operation. These new lances are very accurate tools that enable the operator to perform a more controlled operation; resulting in longer taphole life, fewer repairs and less down-time.

Jan 1, 2016

By Jeffrey R. Taylor

The distribution of low concentrations of Cr, Mn, Rh, Co, Ni, Ag and Fe between copper matte and bullion phases has been measured at 1200oC. These results. together with values for nine other elements, have been used to develop a simple model to describe the distributions in terms of known thermodynamic properties?. The Temkin model for ionic melts was assumed to apply to the sulphide species in the Cu-S matte? phase and it is shown that the choice of sulphide species is particularly important for successful representation of the experimental .results?. In general, the lowest sulphlde (minimum sulphur :. metal ratio)? formed by the. metal is most suitable, although Ni, Co, Rh and Pd appear to associate with more sulphur in the melt than suggested by the? composition of their lowest sulphide. A correlation between the composition of the metal sulphide species formed in the ternary system and the? position of the minimum in the free energy of mixing curve in the metal-sulphur binary -system is? proposed.

Jan 1, 1983

By Arthur E. Morris

Process modeling software is used extensively in process engineering, but there is a notable lack of affordable software for educational uses. This paper describes two educationally oriented software programs for thermochemical modeling of processes involving metals, minerals, and ceramic materials. Both programs run as Excel@ spreadsheet files. The first is FREED, a thermodynamic database program containing datafiles for 2500 species. It contains the entire U. S. Bureau of Mines and most of the U. S. Geological Survey database, plus data for scores of other species drawn from various sources. Several modules are available for manipulating and viewing the data. The second program is THERBAL, for making thermodynamic calculations using FREED data. Equilibrium calculations can be made for systems with non-ideal solutions, for a specified set of pressure, temperature, and input amounts of reactants. An optional heat balance is also calculated. The results are displayed as tables or charts in Excel worksheets. Examples of the use of THERBAL will be given for the reforming of natural gas for DRI production, DRI production, and EAF steelmaking. Some observations will be made on its use in the classroom. The development of FREED and THERBAL was initially carried out at the Department of Metallurgical Engineering, University of Missouri - Rolla as part of a project to preserve and enhance the Bureau of Mines database. The current versions were developed privately by the authors.

Jan 1, 2002

By Yuri Bychkov

The Electron Beam Melting is the most efficient technology for metals and alloys refining. For ,secondary metals processing the Electron Beam Skull Melting (EBSM) with the electromagnetic stirnng (EMS) of melt in the crucible was shown to be the most appropriate. The copper produced by EBSM with EMS possesses higher density and electric conductivity in comparison with other refining methods. The details for high power electrical machines were cast of the copper waste refined by EBSM technology.

Jan 1, 1995