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By Nils Eivind Kamfjord, Mari K. Næss, Halvard Tveit, Edin H. Myrhaug

"As a part of the FUME research programme being done by the Norwegian Ferroalloy Research Association (FFF), the SINTEF Group and NTNU, several measurements towards quantifying the gaseous and solid emissions from the draining of the silicon furnaces for metal have been carried out.Based on the measured size distribution of the formed fume particles and known particle growth theory, an estimate of the growth time for the given particles has been calculated. The formation time for the measured NO amount has also been calculated based on the fume measurements and a thermodynamic model of the furnace gases combusting with air. The two “formation” times are in the same order of magnitude and they are therefore used as parameters in a CFD model, modelling that the formed fume particles are heating up the surrounding air and thereby forming NO according to the Zeldovich mechanism. The measurements show an approximately equal constant NO formation per fume particle. The CFD model shows results in the same order of magnitude, supporting that the particle growth and NO formation happen under near stoichiometric conditions and are controlled by the formation of SiO2 fume.IntroductionNOx is the common notion for the two gases nitric oxide (NO) and nitrogen dioxide (NO2) formed during combustion of fuels. The main sources for human made NOx emissions is on-/offshore transportation industry, power generations based on fossil fuels, agriculture and other industries [1]."

Jan 1, 2012

By Yasuhiro Konishi, Norizoh Saitoh

"We have developed new recycling technologies, based upon an eco-friendly biotechnology, in order to extract precious and rare metals sourced from post-consumer products. Recently we have been focusing on the metal ion-reducing bacteria, Shewanella algae and Shewanella oneidensis, which are able to reduce and deposit the precious metal ions (gold (III), platinum (IV), palladium (II), and rhodium (Ill)) into metal nanoparticles at room temperature within 120 min. When targeting the leachates from printed circuit boards, the Shewanella bacteria were able to allow selective reduction and deposition of gold (III) ions under acidic conditions in the presence of heavy metal ions, proposing a new bio-recovery system for gold. We also found that the Shewanella bacteria can separate and concentrate soluble rare metal ions (dysprosium (III), indium (Ill), and gallium (Ill)) from dilute solutions. Using this biomass adsorbent, the effectiveness of system for the novel recovery of indium from the leachate of used LCD (liquid crystal display) panels has been demonstrated.IntroductionMany high-tech manufacturing industries are highly dependent upon the use of critical raw materials that are the rare metals (e.g. rare earth elements/indium) and precious metals (e.g. gold/platinum group metals). There are now serious global concerns over the short term and long term availability of critical raw materials for high-tech manufacturing. This highlights the paramount importance of sustainable component reuse and material recycling technologies for recovery of critical raw materials. We believe that the most important domestic source of precious metals is through more recycling, and this will require more research and further development for the recycling of precious and rare metals. In general, chemical/thermal recycling is deemed to be the most appropriate means to extract the precious and rare metals from postconsumer products. However, there are issues related to the heavy use of toxic and hazardous chemicals, and the release of toxic emissions.Biological recovery methods provide an attractive alternative strategy and use microorganisms to separate and concentrate soluble precious and rare metals from dilute solutions into microbial cells via biosorption [1-3] and biomineralization [ 4, 5]. Biological systems generally operate at ambient temperature and near-neutral pH. Consequently, microbial recovery of metals would be an environmentally friendly method for recycling precious and rare metals from end-of-use products."

Jan 1, 2014

By V. I. Lakshmanan

Wastes when produced can be reused or recycled prior to disposal. Industries that cause environmental concerns during manufacturing include primary materials and primary metals. Pollution prevention mechanisms to achieve waste reduction require new separation, reclamation, control and process simulation technologies. Substituting recyclables for virgin resources will reduce energy use, water pollution, air pollution, water use and mining wastes. Shrinking landfill space will spur new technologies for waste treatment and recycling. These situations hence offer opportunities for innovative flowsheets with appropriate separation technologies. Development of innovative flowsheets to treat recyclables offer unique opportunities for process/product development, obtain green products and hence market advantage. The paper will illustrate with selected innovative flowsheets to treat recyclables.

Jan 1, 1996

By T. Ueno

Naoshima Smelter & Refinery of Mitsubishi Materials Crop. commissioned a new Mitsubishi continuous copper smelter in May 1991. Process offgas volume of the conventional reverberatory furnace line, one of the previous smelters having been shut down, was very large and thus two acid plants had been operated. It was expected that the offgas volume would be reduced at the new smelter to about a half of the sum of those from previous two 1 smelters and the sulfur dioxide strength would be increased. So various alternatives were studied to minimize the operation cost. And it was decided to utilize both of the plants with minor modifications by diluting the gas either with air or with dilute gases. The acid plants now receive offgases from the new copper smelter, a sintering machine of a lead smelter and a decomposer of waste acid. The paper discusses plant design, operation, improvements and modifications realized in relation with the retrofitting of the copper smelter.

Jan 1, 1992

By Henry L. Ehrlich

This survey compares bioleaching and biobeneficiation by autotrophic bacteria with that by heterotrophic bacteria and fungi Some physiological principles are reviewed. Advantages and disadvantages of autotrophic and heterotrophic leaching are discussed. Principles of anaerobic leaching by autotrophs and heterotrophs are introduced. and the advantages? over aerobic heterotrophic leaching are discussed. Examples of useful organisms in the autotrophic and heterotrophic categories are cited.

Jan 1, 1991

By Balladares V. Eduardo

Most of the arsenic contained in copper concentrates is removed in the gas phase during the smelting and converting processes and, according to recent environmental regulations, it is required to fix it in a solid stable form. In this regards, ferric arsenate has been reported as thermal and aqueous stable compound. Therefore, various alternatives for treating gas containing arsenic were considered in this work. From data obtained at laboratory scale on fixation of arsenic using iron oxide, a new process to treat copper concentrates containing arsenic was evaluated. The effect of temperature, oxygen potential and the sample porosity on the fixation of arsenic contained in a gaseous stream was studied, and the iron oxide converted into ferric arsenate was up to 10%. The obtained results suggest a new alternative for gas treatment with an interesting and attractive technical development. The arsenic was retained as ferric arsenate with thermal and aqueous stability, and it allows a safe disposal keeping the environmental restrictions. The kinetics parameters are used to scale up laboratory results to higher processing rates.

Jan 1, 2005

By E. Oshilna

The Mitsubishi process has many advantages pertaining to economical and environmental matters. These advantages have led to the installations of the Mitsubishi process in constructing new smelters: The Mitsubishi process utilizes highly oxygen enriched blast air and uses a special lime slag in the C?furnace. These characteristics change the . distribution of Impurities from other processes which use P.S. converters, Recently an Increased amount of secondary materials which contain impurities Is being treated at Naoshima Smelter. In order to cope with an Increment of the Impurities load and maintain the cathode quality, many Improvements have been Implemented. This paper discusses the impurities behavior In the Mitsubishi process and describes the measures taken to treat an Increased ?amount of secondary materials:

Jan 1, 1998

By J. L. Watson

The composite nature of titanomagnetites found on the west coast of the north island of New Zealand is an important parameter in the beneficiation of the black beach sands for export to Japan. To investigate this composite nature, borehole and plant samples from the Waipipi Ironsands Ltd property were subjected to a series of separations in heated Clerici solutions at densities varying from 3.2 to 4.6 g/cc. The resulting density fractons were analyzed magnetically and a set of distribution curves for composite grains proposed. In addition the experi¬mental data was plotted to produce titanomagnetite sand 'washability curves" which illustrate the possible problem areas in beneficiation that may arise due to composite titanomagnetite grains. From this data a set of guidelines are suggested for interpreting the curves in terms of ease of gravity concentration. The composite nature or liberation of titanomagnetite grains is shown to favor high and low grade composites with few intermediate compositions being isolated. The relationships between grain size, borehole depth and liberation are examined and related to beneficiation procedures for the black sand deposit.

Jan 1, 1982

The U.S. Bureau of Mines investigated CaF2-assisted H2SO4 leaching to extract Mn from domestic silicate manganese resources. A pyroxmangite ((Mn,Fe)Sio3) ore containing, in pct, 34 Mn, 23 Si, 3 Ca, and 1 Fe was leached at 90° C for 3 h in a solution containing, in g/L, 12 Mn, 140 H2SO4, 130 (NH4)2SO4, and 5 CaFz. Manganese extraction of 92 pct was achieved. Manganese of greater than 99 pct purity was prepared by electrolyzing the purified pregnant solution at a current density of 50 mA/cm2. The current efficiency was 65 pct.

Jan 1, 1991

By K A. Pericieous

"Magnetic fields have many actual applications in the metals processing industry. Externally applied magnetic fields give rise to electromagnetic (Lorentz) forces formed by the cross product JxB, between the induced current density J and the magnetic field density B. When the metal is in liquid form, the Lorentz force generates motion in the fluid which in applications of practical interest becomes turbulent. In modelling terms, the Lorentz force appears as a source in the momentum equations. In addition, the induced current generates heat (Joule heating) in the metal that is in proportion to J2, with a corresponding source of heat in the energy equation. Whether as heat or as a force, these effects represent action at a distance - a most useful attribute when dealing with hot metal. The Lorentz force is used to stir solidifying alloys, pump liquid metal in conduits, dampen the flow in the meniscus of a continuous caster, levitate metal drops, induce artificial gravity conditions in suspensions or contain liquid metal. Elsewhere, the Lorentz force may be a by-product of some other operation, so leading to wave excitation in aluminium electrolysis cells, or altering the shape of the weld pool in arc welding. Joule heating is most commonly used with applied AC fields, to melt metal in induction furnaces.The author and his colleagues have been involved in the modelling of most of these processes in the past decade. Modelling is not however straightforward, since most of the examples mentioned represent genuine multi-physics challenges. There is a strong coupling between the flow field and electromagnetic field. The addition of a dynamically varying metal free surface and the moving solidus front means the flow, heat and electromagnetic fields need to be computed simultaneously. In situations involving metal containment, the metal free surface position is governed by the interplay of gravity, Lorentz force, surface tension and fluid inertia. Since all the interesting effects often happen in thin boundary layers at the surface due to the skin effect, mesh generation and mesh control during the computation become non trivial problems that need to be addressed. This paper presents a review of numerical methods used to model droplet levitation, semi-levitation melting and cold crucible induction melting of metals. The first method is based on spectral collocation techniques and the second is the traditional FV approach. Steps taken to validate the computations and typical transient results are also given."

Jan 1, 2001

By Leon E. Laforest

An early commitment by Kidd Creek Mines Ltd. (formerly Texasgulf Canada) to follow a stringent environmental control programme from the initial stages of design and development of its metallurgical facilities in Timmins, Ontario, has resulted in the on-going attainment of extremely low levels of industrial waste emissions. This paper outlines the monitoring programme initiated and maintained by the company's environmental control section. Comparative results of environmental sampling for the periods before and after the copper smelter start-up are highlighted.

Jan 1, 1983

By Batric Pesic

Dissolution of gold with elemental bromine was studied by using a rotating disc technique. The main parameters studied were: bromine concentration, stirring speed, pH, and temperature. Additionally, effect of copper, iron, and manganese was also examined. A special attention was paid to elucidate the role of cations, primarily Na+, during gold dissolution. It was found that gold dissolution with bromine was characterized with two pH regions. Below pH=7, gold dissolution was independent of pH, and above this value, gold dissolution decreased with pH increase. Gold dissolution rates were proportional with concentration of bromine. Two regions, diffusional and kinetic, were observed with respect to stirring speed. with respect to the role of Na+, and cations in general, they play absolutely no role during gold dissolution with bromine, unless they are in their lower oxidation state and become oxidized by bromine. In that case they have a negative effect because of bromine consumption.

Jan 1, 1991

By David S. Holmes

An overview of existing biological technologies for the recovery of copper and uranium is presented. Engineering and biological challenges and opportunities in these areas. are discussed. New opportunities for the biooxidation of refractory gold ore are described. Techniques for the development of new strains of microorganisms. for commercial metal recovery applications are discussed with special reference to the genetic manipulation for bacterial strain improvement.

Jan 1, 1991

By S. Seetharaman, Du Siehen

"In the processing of molten metals, it is extremely important to monitor continuously the concentration levels of various minor elements. In the production of common metals like copper, iron and aluminium electrochemical sensors involving solid as well as liquid electrolytes are being increasingly used to measure the concentrations of minor elements. The present paper deals with the electrochemical principles underlying these measurements and the possible errors involved. One of the major difficulties in the case of the solid electrolytes is to correct for the consequences of the electronic contribution to the conduction of the electrolyte.The application of the electrochemical sensors for molten metals processing involves designing of these probes to withstand the industrial operating conditions. In this respect, significant achievements have been made with respect to the design of oxygen probes for liquid metals in general and liquid copper in particular. Some of the salient design features are discussed in the paper. The application of auxiliary electrodes for impurities in molten metals like phosphorus in copper and silicon in iron are taken up. The development of oxygen sensors for slags is given special attention. Recent developments in the field of sensor technology, as applied to metals processing are highlighted.1. IntroductionThe rapid technological advancement today require precise control of the process parameters and the impurity levels. Most of the molten metals processing in industrialized countries are often steered by suitable computer models, either phenomenological or simulations based on theoretical principles. These models often require that the process parameters are continuously monitored so that the progress is followed and modified suitably as and when required. It is common practice to measure temperatures by incorporating temperature sensors at the various strategic points of the reactor. In the case of monitoring the composition changes in the various phases, the method of sampling followed by routine chemical analysis involves a time lag as well as uncertainties in sampling and analysis. In this respect, electrochemical sensors have the advantage of generating accurate data when properly applied and increasing attention is being paid in the development of electrochemical sensors for various common species in molten metals processing. In the present paper, the developments in this area over the years are outlined and typical process applications are discussed. A greater emphasis will be laid on sensors based on oxygen conducting electrolytes and their application to the production of common metals like iron and copper."

Jan 1, 1996

By Patricio Ruz, Gabriel Riveros, Carolina Ramirez, Andrzej Warczok, Rober Treimer

"Continuous converting of copper matte produces slag with high cuprous oxide content. The corrosion of chrome-magnesite refractories with slag of high cuprous oxide content is a major problem. Properties of olivine type of slag make the slag very attractive for matte smelting and converting.Analysis of phenomena determining the slag infiltration into the porosity of a refractory and dissolution of refractory components in the slag allowed for better understanding of the mechanisms of refractory destruction.The results of laboratory scale tests of the olivine slag infiltration into open porosity and corrosion showed dominating effects of slag temperature and cuprous oxide content. The optical and X-ray examination of slag samples permitted the definition of the mechanism of formation of new phases and refractory deterioration. 71"

Jan 1, 2009

By Dmitri Nassyrov, In-ho Jung

"All relevant thermodynamic and phase diagram data in the CaO-Fe10-CaF2 system were critically reviewed. One set of model parameters describing the Gibbs energy of all phases has been obtained as a result of critical evaluation of the available data and optimization of the model parameters. The Modified Quasichemical Model was used to describe the interactions in the liquid phase. All calculations were performed using the FactSage thermochemical software.IntroductionSlags contaimng CaF2 are of significant interest to the steelmaking community. Notable examples of slags containing significant amounts of CaF2 include Electro-slag Remelting (ESR) slags [1] and mould flux for continuous casting [2]. The role of these slags is, among other things, to refine steel by absorbing inclusions and dissolved impurities. During slag-steel interaction, some iron from the steel will inevitably get oxidized and form iron oxides which will dissolve into the slag. With this in mind, it is important to understand the interaction between CaF2 and Fe,0 for accurate prediction of slag composition and process optimization. A thermodynamic optimization of the CaO-FetO-CaF2 was thus undertaken."

Jan 1, 2013

By Rubén Alvarado

The markets and environmental protection rules are more and more exacting, both of which have determined that copper smelters should look for technological development and global management to ensure their viability and competitivity in the short and long term. The main facilities of the present and future Smelting-Converting Process at Codelco's Caletones Smelter, is based on Teniente Converter reactors with a high operational availability that have reached concentrate processing capacities near 2,000 tpd. These reactors are in operation in most of the smelters in Chile as well as in Zambia, Peru, Mexico and, in ?the near future, in Thailand. Since 1993, the Smelting-Converting process of the Caletones Smelter of Codelco-Chile has been based on one Reverberatory furnace, two Teniente Converters and four Peirce-Smith Converters. These facilities, together with the operation of two Fluidized Bed Dryers, three Slag Cleaning Furnaces, and two Oxygen Plants have allowed the smelter to reach concentrate smelting capacities and copper productions of 1,215 kt/year and 360 kt/year, respectively. This transitional operating scheme, combining together traditional and advanced technological equipment, needs further modernization to successfully face the modern world challenges, especially with relation to the environmental commitment, production costs and wide satisfaction of customers. For this reason, for the period 1997-2000, a Modernization Plan has been worked out. This plan considers an increase of the present throughput, which will permit a significant increase in productivity, as well as finding a definitive solution for meeting the environmental regulations. Among these projects, we can point out the definitive shut down of the Reverberatory Furnace, which is a contaminating piece of equipment of low energetic efficiency. Additionally, it considers the installation of two new Slag Cleaning Furnaces, one additional Oxygen Plant, and the incorporation of two new Sulphuric Acid Plants with a production capacity of 4,500 T/D, that will recover over 92% of the sulphur content, of process off-gases.

Jan 1, 1998

By Jason Ganley, Yingjia Liu, Adam Dekich, William Tilson, Jeffrey Fergus, Dileep Kumar CJ

"Manganese cobalt spinel oxide coatings have been shown to be effective for preventing chromium volatilization from interconnect alloys, and the associated cathode poisoning, in solid oxide fuel cells. During high temperature exposure a reaction layer consisting of chromium containing spine! forms due to reaction with the chromia scale formed on the alloy. The electrical conductivity of this reaction layer is much lower than that of the coating material and thus can increase the overall area specific resistance (ASR) of the system. The approaches to reducing the ASR are to reduce the thickness and/or increase the electrical conductivity of the reaction layer, which includes both the high-chromium spinel phase and the chromia scale. In this paper the effects of transition metal dopants on the amount and properties of reaction products formed during the reaction of spine! oxide coating materials with chromia are presented.IntroductionThe high cost and difficulties involved with the processing of chromia based ceramic interconnect materials for SOFCs are driving the search for metallic interconnects [1, 2]. The reduction in the operating temperature of SOFC has allowed for the use of high chromium alloy steels for this application [3]. However, the volatilization of chromium from the chromia scale, and the associated poisoning of the cathode, remains a problem which needs to be addressed [ 4]. Though the application of manganese cobalt oxide spine! coatings on the alloy surface substantially reduces chromium poisoning of the cathode [5], the low electrical conductivity of the reaction layer formed between the chromia scale and coating affects the performance of interconnect. Incorporating transition metal ions in the reaction layer could alter the electrical characteristics and improve the performance. Copper and nickel doped manganese oxide spinels are widely used as thermistors due to their high electrical conductivity and negative temperature co-efficient of resistance characteristics [ 6, 7]. Hence doping of copper and nickel in manganese-cobalt spine! oxide composition may improve the electrical characteristics of interaction layer as well and is attempted here."

Jan 1, 2012

By R. G. Reddy

Nickel solubilities in spent pickling solutions (i.e. HF-HNO3-H2O solutions ) were measured as a function of HF and HNO3 acid concentrations. The chemical analysis of the industrial pickling solutions and sludges were made. The stable phases observed in the sludges are FeF3?3H2O, and ( FeCr ) F3?3H2O. Pure Ni, and stainless steel type 316 were used in this study. The results showed that the solubility of Ni increased with increase in concentrations of HF in pickling solution at a fixed concentration of HNO3: An excellent agreement between the experimental solubility data and the theoretical data was obtained. X-ray diffraction analysis showed that the solid solubility product formed is mainly NiF2?4H2O compound.

Jan 1, 1992

By Giulio R. Altoé, Sergio N. Monteiro, Ygor M. Moraes, Rômulo L. Loyola, Frederico M. Margem, Gabriel O. Glória

The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of PALF fibers were evaluated. Composites reinforced with up to 30% in volume of long, continuous and aligned PALF fibers were tested in an Instron machine at room temperature. The fracture was analyzed by SEM. This one revealed a weak fiber/matrix interface, which could be responsible for the performance of some properties. The results showed significant changes in the mechanical properties with the amount of PALF fibers.

Jan 1, 2015