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By T. Ikeda, M. Maeda, K. Mita

Galvanized steel sheet is the major product for the automobile industry. Therefore, automotive recycling results in zinc-containing scrap that should be remelted in EAFs. Naturally, the EAF dust is a very important source of zinc for zinc recycling processes. The thermodynamic properties of the Fe-Zn intermetallic compounds formed on the surface of galvanized steel sheet should be clarified to make clear the evaporation mechanism of zinc; however, there are few reports on these compounds because of difficulties in their synthesis. There are various intermetallic compounds in the Fe-Zn system. We synthesized them at about 673K. A specimen was examined chemically and X-ray diffraction was applied to ensure the formation of intermetallic compounds. Material containing two phases was placed in a Knudsen type effusion cell and the mass spectrum studied to evaluate the vapor pressure of zinc. The thermodynamic property of intermetallics was then evaluated through measured intensity.

Jan 1, 2000

By L. Z. Villanueva

An investigation and evaluation has been performed to determine the potential utilization of electron beam irradiation technology for sulfur oxides removal from reduced-S02-strength metallurgical gases from copper smelters. These off-gases, though too weak to be converted to usable, concentrated: sulfuric acid by conventional means, are characterized by SO2 content higher than 2,000 ppm and a complex chemical composition, including high oxygen content and its generation occurring in a cyclical, fluctuating pattern. This work was based on information supplied by principal smelter companies in Chile. A laboratory facility with flow rate of 20 Nm3/h and equipped with an electron accelerator of beam energy 8.00 keV, has been used for testing. Influence on SO2 removal efficiency of operational parameters such as gas temperature, water vapor content, ammonia feed ratio and irradiation dose was established. The main conclusion of this work, from experimental laboratory tests as well as engineering studies, is that the Electron Beam Process (EBDS) is a cost-effective, simple and appropriate chemical process means for emission abatement. EBDS can, on a site-specific basis, adequately augment SO2 removal to upgrade overall abatement as required and in an optimal manner.

Jan 1, 1999

By Y. Takasaki

For zinc hydrometallurgical extraction, reducing the electric power consumption of the electrowinning process is an important issue for energy savings. At the Zinc & Lead 2000 symposium, the authors suggested that by using the Pb-0.5%Ag-0.6%Ca alloy, the electrolysis energy can be decreased compared to the conventional Pb-0.9%Ag alloy. In this study, the corrosion behaviors of the Pb-Ag-Ca electrode in a sulfuric-acid electrolyte were investigated. Based on the results Or me Pb-0.5%Ag-0.6%Ca anode after 20 days of electrolysis, the bath voltage and the quantity of anode slime decreased compared to the Pb-I%Ag anode. Subsequently, beta-PbO2 on the electrode surface was detected by XRD and its peaks were sharper than the Pb-1 %Ag anode. Moreover, a dense beta-PbO2 layer on the 0.6%Ca a anode surface was observed. Therefore, it was suggested that the dense beta-PbO2 layer on the anode surface is one of the factors that leads to a lower bath voltage and decreasing quantity of anode slime.

Jan 1, 2003

By Kwan Soo Han

A thermodynamic model for predicting the distribution coefficients has been developed by taking into account the extraction mech-.ism and the chloride complexation when Sm, Eu, Gd, Tb, Dy and Ho for single component systems are extracted from acidic chloride solutions by di-2-ethylhexyl phosphoric acid and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester in kerosene, respectively. The model equation includes two constants, of which one corresponds to the apparent extraction equilibrium constant and the other is due to the variation of the activity coefficients of organic species. These values are determined from a few experimental data by the curve fitting method Then, the distribution coefficients under untried conditions have been predicted from only the initial data by iterative calculations. Bromley's formulation is used to estimate the activity coefficients of aqueous species and the interaction parameters for some rare earth chlorides are reported in terms of molality and molarity using data from Spedding et al. The validity of this method has been confirmed by excellent agreement between the experimental and the predicted distribution coefficients.

Jan 1, 1989

By F. Tanaka

In April 1999, a two-year campaign of the Mitsubishi furnaces was achieved at Naoshima Smelter; the present one is expected to be extended much longer. An overview of basic technology for decreasing refractory wear in the Mitsubishi Process is presented. One of the main features of the process is the use of top blowing lance technology which has a different effect on the furnace refractory than other conventional processes. The refractory wear of concern is hearth wear caused by top blown powder injection, wear of the side wall caused by splashing droplets, and wear of the bath level refractories caused by surface waves of melts in the furnace. These have been systematically investigated for many years. This paper describes the results of various model tests and their application to practical furnace design and operation.

Jan 1, 1999

By Christian Hecker

An Eh-pH electrochemical sensor developed for on-line pH and redox potentials copper sulphide flotation process control was studied. The electrochemical sensor cell includes two metallic platinum electrodes, a metallic antimony electrode and a high impedance reference cell which are polarized with a potentiostat. For pH and redox potential determinations, the Sb and platinum electrode potentials are measured, respectively, against the polarized electrochemical reference system. The behaviour of this electrode configuration has been investigated in a laboratory scale. An electrochemical sensor device has been succesfully installed and checked in El Teninte Colon Concentrator's SAG line feeding the copper flotation rougher circuit.

Jan 1, 1999

By Dengfu Chen, Yunwei Huang, Mujun Long, Kui Lv, Pei Xu, Lin Bai

The surface temperature of continuous casting slab in the secondary cooling zone is a key parameter of production control. However, the accuracy of radiation temperature measurement of high temperature casting slab is greatly affected by the environmental factors, such as water vapor, spray, water film and other participational medias during continuous casting process. In this paper, the radiation characteristics of water vapor and its influences to radiation temperature measurement of continuous casting slab were investigated. Based on the database HITRAN 2004 and the measuring principle of monochrome thermometer & colorimetric thermometer, the measuring errors under different operating infrared spectral wavelength were compared. Results showed that spectral region with wavelength nearby 1.0μm or 1.6μm would be the optimum for high temperature infrared thermometer used under the conditions with moist steam, water spray and water film at the secondary cooling zone in steel continuous casting.

Jan 1, 2016

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 Keith Axler

The high reactivity of plutonium metal presents safety concerns related to material containment during fire scenarios. Plutonium metal is liquid at temperatures achieved under selected fire scenarios. The appearance of liquid plutonium challenges the corrosion resistance of the containment materials. However, by the in situ formation of intermetallic compounds, the plutonium metal can be stabilized as solid and the integrity of the containment vessels preserved. Studies have been conducted to demonstrate candidate materials, including lead, which can be introduced to the liquid-plutonium system and bind the corrosive liquid metal through the formation of intermetallic phases. The results of these investigations will be presented along with a discussion of the experimentally determined phase behavior for the plutonium-lead system.

Jan 1, 1995

At the present time, cyanide is the most widely used reagent to extract gold from its ores and concentrates. However, its use in mining has become the focus of intense attack by various groups throughout the world; as a consequence, a renewed effort has been launched to find suitable alternative lixiviants to recover gold. Chlorination was the most popular process to extract gold, before it was rendered obsolete with the advent of the cyanidation process at the turn of the last century, not least because it required the use of potentially hazardous and costly chlorine to oxidize/complex the gold. The PLASTOL® process, originally designed to recover the platinum group metals (PGM?s) from their ores and concentrates, provides an alternative to cyanide for gold ores. The process generates oxidizing conditions in the autoclave capable of forming the AuIII ion, and gold chloro-complexes result from the addition of small quantities (~5-10 g/L) of sodium chloride to the autoclave. The principles of the PLASTOL® process are briefly described, and several applications of the process to gold concentrates are presented. Various options available to recover gold from PLASTOL® leach solutions are also discussed.

Jan 1, 2003

By Cameron Harris

With the consolidation of the copper industry in the second half of the 20th century resulting in fewer plants treating ever increasing quantities and qualities of feed, the enormous flexibility of the Noranda Process gives it significant advantages over many competing technologies for the production of matte. Toll smelting, recycling, and secondaries treatment will become the cornerstone of profitable operations for all but the lucky few who have large captive mines associated with the smelter. Consequently, the ability to respond to changing market conditions without significant metallurgical or operational upsets will be of considerable commercial advantage. The inherent stability of this bath-smelting process leads to tight matte grade control, while the bath turbulence leads to rapid consumption of feeds with widely varying physical characteristics. Low capital and operating costs combined with a layout suitable for retrofit into existing converter aisles makes it a sensible choice for parts of the world still experiencing the aforementioned consolidation, which is essentially complete in fully developed economies such as the United States of America and the European Union. This paper will discuss features of the Noranda process compared with other technologies and its place in the future global copper production industry, which is set to become increasingly competitive and aggressive.

Jan 1, 2002

By N. J. Rarmrez, C. Perez, J. D. Calderon, L. Lopez

"Among the thermal characterization of any material, one of the variables to know is the coefficient of thermal conductivity because this value can tell how much heat passes through the material and if the material could be used as an isolator. In order to determine this parameter is required some kind of special equipment and controlled conditions which implies high costs in the development of tests. The present paper proposes a design of a low cost measurement system in order to determine this coefficient with the lower possible error. This equipment was thought for companies or labs where they do not have the economic resources or the infrastructure (environmental controlled labs, heat flux transducers, human resources with specialized knowledge) to do this kind of tests.The system is based on ASTM C 518 - 04 [l] and integrated by two plates (one that contains a thermal resistance and which temperature is controlled by a closed loop controller and the other one with a route of water flow). The thermal resistance is actuated by a relay and a supervisor system checks the total time the relay is on in order to determine the effective power applied to the system. The contact faces of the plates contain a group of temperature sensors connected to a data acquisition system that process and record the temperature in each measurement point.With the power applied to the system, the measurement of temperatures and a process of calibration is possible to determine the coefficient of thermal conductivity. IntroductionWithin the thermal characterization of a material of known variables is the coefficient of heat transfer, since this value can know the amount of heat the material is capable of transferring or isolating. To determine this ratio requires specialized equipment and controlled conditions, which implies high costs in the development of a test. This article proposes a design of a low cost machine to allow closer this coefficient with the least possible error. This equipment was done thinking about companies that do not have the infrastructure (laboratories, controlled environment, heat flux sensors, human resources expertise) and financial resources to conduct these tests."

Jan 1, 2011

By Uday Pal

In direct reduction processes for iron and steel making, significant amounts of Fe-C alloy droplets are generated and these remain suspended in relatively low FeO (around 5%) containing slags. Earlier workers have found that when the FeO content in the slag is <5%, the decarburization reaction becomes extremely slow (virtually ceases to occur) even though the alloy droplet contains a significant amount of carbons (2-3%). Understanding this rate controlling kinetic phenomena is crucial to designing an&apos; optimum direct steel making process. We studied decarburization of Fe-C particles by low FeO (<5%) containing CaO-SiO2A12O3 slags and found that by putting both the droplet and the slag in direct contact with an inert electronically conductive member that extends deep inside the slag bulk were able to quickly and completely decarburize the droplets. A detailed description and an explanation of the process will be presented.

Jan 1, 1995

By K. Koike, N. Masuko, Y. Takasaki

At the Zinc & Lead'95 symposium, one of the authors presented several modifications of Pb-Ag-Ca alloy anodes for the zinc electrowinning process, and also, the behavior of some organic additives in the electrolyte. In this study, the mechanical properties of the electrode materials composed by Pb-0.5 wt% Ag-(0~0.8) wt% Ca were studied by the tensile and Vickers hardness methods. Furthermore, experimental research on the influence of rolling and annealing treatments on the electrolytic behavior and mechanical properties of these alloys was carried out. The tensile strengths of the annealed Pb-0.5 wt% Ag-(0.1-0.8) wt% Ca alloys were the same or higher than those of the as-cast Pb-0.9 wt% Ag alloy. The anode potential using the as-cast Pb-0.5 wt% Ag-0.6 wt% Ca alloy decreased compared to the as-cast Pb-0.9 wt% Ag alloy. Moreover, the annealed Pb-0.5 wt% Ag - 0.6 wt% Ca anode after rolling showed a lower anode potential than the as-cast Pb-0.5 wt% Ag - 0.6 wt% Ca anode.

Jan 1, 2000

By Wei-ling Wang, Ryosuke O. Suzuki, Xiang-ning Meng, Miao-yong Zhu

"A finite-element thermal-stress model of continuous casting mold is conducted to predict deformation of copper plates and its change with different cooling structure. The results show that deformation behavior of copper plates is mainly governed by cooling structure and thermal- mechanical conditions, deformation amount is related to structure geometry, and a small deformation mutation occurs in cooper-nickel boundary due to different properties. The maximum deformation of hot surface centricities of wide face locate at 100 mm below meniscus and that of narrow face locate at meniscus and terminal of water slots and significant curvature fluctuations on both sides of copper-nickel boundary. The maximum deformation of centricities is increased up to 0.05 mm with thickness increment 5 mm of copper plates, and maximum deformations are only depressed 0.01 mm and 0.02 mm with increments of 1 mm nickel layer thickness and 2 mm water slot depth respectively.IntroductionIn conventional continuous casting of steel, a large amount of sensible and latent heat of molten steel dissipate in primary cooling zone and make continuous casting mold under enormous heating load giving rise to thermal stress, deformation, high-temperature fatigue and creep not only depress mold life-span, but reduce casting stability [1] Many studies focused more on heat transfer, solidification and shrinkage of solidifying shell to provide inverse proposals for optimizing cooling system and even designing new taper of mold [2,3], but it is generally useless to those of having been manufactured or being put into production. Therefore, mold-related forward problems show necessity to be discussed deeply, and stress and deformation distributions based on special thermal conditions in mold should be analyzed in order to explore suitable cooling structure of mold directly. Samarasekera et al. [4] examined heat flow and distortion of two-dimensional longitudinal sections and investigated effect of cooling water velocity, copper plates thickness and carbon content on formation of rhomboidity and longitudinal comer cracks. O'Connor et al. [5] developed a three-dimensional mathematical model to compute thermo-mechanical state in thin-slab mold and calculated temperature and deformation of mold wall to assess roles of various process parameters on impacting mold life. Thomas et al. [6] predicted temperature, distortion and residual stress in mold and indicated increased distortion requires increased remachining, which reduces mold life and increased residual stress increases the probability of a catastrophic crack failure. Park et al. [7l determined heat-flux profiles in funnel-shaped and parallel thin-slab molds based on an inverse heat conduction model and thermocouple temperature measured in-plant and put them into three- dimensional finite-element thermal-stress model to predict temperature, distortion and residual stress of mold wall. Korie et al. [SJ focused on prediction of temperature, distortion and residual stress in mold and in particular to clarify that mold life is significantly affected by temperature and its rigidity, but little effect by mechanical including clamping force, bolt prestress, friction and ferrostatic pressure. Meng et al. [9l predicted temperature and thermal stress in a slab mold and analyzed effect by cooling system geometry and casting speed quantitatively. In present study, a three-dimensional finite-element thermo-mechanical model with type-switched element is transformed from previous heat-transfer finite-element model [9l, and mold deformation is simulated in order to shed light on thermo-mechanical behavior with special thermal conditions and different mold geometry at high casting speed."

Jan 1, 2013

By W. F. Drinkard

Many in the environmental movement have focused on this element. But, nothing they or anyone does will change the amount of arsenic in the world. This report is on actual commercial plants that we developed and operated to recover or stabilize arsenic values from metallurgical dusts from gold and copper pyro operations and arsenical gold bearing ores. When they were available gold and copper values were recovered. Our experience in arsenic extends over thirty years. My first corporation, Mineral Research & Development Corporation was the first in North America to manufacture the then new CCA (copper-chrome-arsenic) wood preservatives. This class of wood preservatives proved to be so effective that it made wood into an entirely new material of construction. It is not uncommon for wood properly treated with arsenical CCA preservatives to last for thirty; forty, and sixty years. Over a hundred years have been projected in some field tests. Hundreds of thousands of trees have been saved. Millions more trees would have been saved had environmentalists not decided that their arsenic phobia was more important than trees. There are several variations of CCA. The most popular is CCA-C. Its formula is: CrO3 . . . . . . . . . . . . . . . . . . . 47.5% CuO . . . . . . . . . . . . . . . . . . . 18.5% As2O5 . . . . . . . . . . . . . . . . . 34.0% Until recent restrictions were placed on the consumption of arsenical wood preservatives, annual consumption in North America was about 150,000,000 lbs./yr. About 64,500,000 of arsenic as the pentoxide was safely consumed this way. World CCA consumption has been about double the above figures or 300,000,000 lbs. as 100% CCA and 129,000,000 lbs/yr as As2O5. Close to 100% of all the arsenic used in wood preservatives is derived from gold or copper processing. The valence of arsenic required for CCA wood preservatives and many other markets is the same valence that is required for stabilization. The economic challenge is how to get there. We have built and operated eleven plants to oxidize arsenic trioxide to its pentavalent form. Most of these have been classic in that they used a common oxidants such as hydrogen peroxide or nitric acid to achieve this.

Jan 1, 2005

By Manuel Pérez-Tello

A mathematical model to represent the expansion and fragmentation of copper matte particles oxidized under flash converting conditions is presented. The model assumes the particles to be initially nonporous, have a constant mass prior to fragmentation, and travel at a constant velocity throughout the reaction chamber. The model requires the specification of five parameters: the particle expansion rate, a fragmentation diameter factor, a fragmentation size distribution parameter, and the fractions of the finest and the coarsest particles in the feed that undergo fragmentation. The model predictions show good agreement with experimental data collected in a laboratory flash converting furnace over a wide range of experimental conditions. The evolution of the size distribution of the particles along the reactor length was computed, and the model parameters were correlated with the experimental operating variables. Model predictions indicate that particle residence time is an important factor in the generation of dust. The presence of two maxima in the particle density function may be attributed to turbulent conditions prevailing in the furnace, which cause particles to follow very different trajectories within the furnace even if they are injected at the same location.

Jan 1, 2006

By John C. Carpenter

Solvent extraction is used to selectively recover copper from iron containing sulphate solutions. As chloride ions, which form series of complexes with transition metals, are now being used for leaching. Little is known of the effects of these ions, on solvent extraction behavior. It has been shown that commercial extractants of the L1X and Kelex series extract copper from chloride media: (1) at a lower pH than from sulphate solutions, (2) to similar loadings, and (3) except for L1X 63, without transferring chloride to the organic phase. A process for selective extraction of copper from chloride solutions should thus be compatible with standard stripping and electrowinning practice. Of several diluents, differing in aromaticity, kerosene gave enhanced extraction only with L1X reagents. A change in operating temperature had little effect on equilibrium metal distribution. All the extractants examined gave adequate separation of copper from iron. L1X 63 was found to extract chloro-complexes of copper and of iron and thus transfer chloride to the organic solution. Consequently this extractant and its mixtures are not preferred for use with chloride leaching systems.

Jan 1, 1976

By Oleg B. Girin, Yuliya O. Proshenko

"Several approaches to electrolytic synthesis of new types of composite coatings with improved properties were devised using the authors' findings on development of texture, substructure and structural state in metal electrocrystallization. Addressed are texturally composite coatings having improved resistance to wear and corrosion; substructurally composite coatings having improved hardness and corrosion resistance; phase-change constitutionally composite coatings having improved corrosion resistance, reflectance, hardness and resistance to wear; structure-change constitutionally composite coatings having improved electric and magnetic properties; restricted-substructure composite coatings having improved resistance to abrasive-impact wear; and modified-substructure composite coatings having improved strength and plasticity.IntroductionIn recent years, some trends in the formation behavior of crystal texture, crystal substructure and structural state of electroplates were revealed and effects of texture, substructure and structural type on electroplate properties were discovered (1-3). Our interest was in using these findings and effects to develop some ways of synthesizing new types of composite electrolyte coatings having enhanced properties."

Jan 1, 1998

By Maurizio Marezio Bertini

Successful treatment of contaminated sediments was achieved by sparging either 0.5 M NaOH solutions or distilled water with an SO2/O2 gas mixture. Metals such as Cu, Pb, Cr and Cd were successfully removed in a relatively short time. The effect of temperature and pH was investigated. Higher temperatures produced faster and higher recoveries with Pb and Cr more affected to temperature increase than Cu and Cd. The removal of copper, up to 50% percent, was achieved in alkaline solutions through the formation of copper sulfite complexes. The complete removal of metals such as Cu, Pb, Cr and Cd required that part of the treatment be carried out in acidic solutions. A preliminary cost analysis was carried out.

Jan 1, 2003