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By Cassandre Nowicki, Louis Gosselin, Carl Duchesne

"Quebec's primary aluminium production industry consumes roughly 39 TWh of electricity per year and is accountable for roughly 7 million tons of CO2 equivalent. By tapping only a small portion of waste heat and integrating it inside the production facility itself, we can significantly reduce GHG emissions and energy consumption. Although the amount of thermal waste can be adequately estimated by applying an energy balance to production processes, this provides very little information on the quality of waste heat and its potential for integration. A measure of exergy is required. Waste heat streams characterized by high exergy content may generally offer valuable incentives for recovery and integration. More generally, exergy values limit integration possibilities. An exergy analysis is provided for the aluminium electrolytic reduction process. This is meant to guide future heat recovery initiatives and energy efficiency measures.IntroductionCanada is one of the world leaders in primary aluminium production and 92% of its aluminium production capacities are located in the province of Quebec. In 2007, production capacity reached 2,786,000 tons in Quebec alone. Since it is estimated that 2.5 equivalent tons ofCO2 are released for each ton of aluminium produced in Canada, Quebec's aluminium production industry is accountable for roughly 7 million tons of CO2 yearly [1, 2]. Furthermore, with an average electricity consumption of 14 MWh per ton, primary aluminium accounts for 39 TWh of electricity per year in Quebec and this energy consumption represents 350 thousand tons ofCO2 equivalent [3, 4]. Natural gas consumption associated with primary aluminium production accounts for less than 1 TWh, but it represents an additional 350 thousand tons of CO2 equivalent [ 4].This work is meant to provide a tool to guide future efforts towards heat recovery and energy efficiency in the primary aluminium industry. Waste heat recovery and thermal integration can cut down both energy consumption costs and GHG emissions. In a primary aluminium production facility, waste heat represents roughly half of the energy input into the Hall-Heroult process. Tapping only a small portion of this energy could reduce natural gas and electricity consumption significantly. In order to evaluate how much of this energy is actually usable, we propose to apply an exergy analysis to individual transformation processes in an aluminium production facility, such that a potential to do work can be assigned to every waste heat flux. The approach will be described in the next section."

Jan 1, 2012

By A. Siegmund, R. D. Prengaman

Lead anodes used in zinc electrowinning generally contain 0.5 - 1.0 % silver to reduce the rate of corrosion over the service life. For good quality zinc, the cathodes must contain less than 10 ppm lead. In order to reduce the lead contamination of the cathode, the lead anode must become coated with a protective layer of Pb02/Mn02. The formation of this layer may take as long as 30 - 60 days, during which time zinc production is substantially reduced and the cathodes are contaminated with lead. To improve the mechanical properties of Pb-Ag-anodes alloying elements such as calcium, strontium, barium and others are added. The production of cast lead-silver or lead-silver-calcium anodes often results in the formation of numerous holes, voids or laps in the anode surface that can initiate localized internal corrosion. Based on the experience as the major supplier of rolled anodes for copper electrowinning, RSR Technologies has developed an improved anode for zinc electrowinning. The anode consists of a rolled Pb- Ag-Ca-alloy with a controlled surface grain structure. It forms an adherent protective oxide coating within 2 - 3 days when placed in an electrowinning cell. The preferred calcium and silver contents of the alloy are 0.03 - 0.08 % and 0.3 - 0.4%, respectively. Rolling sheets significantly reduces the presence of internal porosity or laps. The lack of defects results in long anode life. The rolling also produces a uniform grain structure to which the corrosion product readily adheres, thus significantly reducing the conditioning period.

Jan 1, 2000

By J. Méndez-Nonell

The thermodynamic and chemical properties of SrSO4 and SrS in a gaseous flow of CO and CO2 at high temperature are discussed. The thermodynamic analysis of the system was made using data from the literature. The results obtained from the thermodynamic analysis were experimentally verified using the thermogravimetric technique. The experimental results suggest the formation of a complex compound between SrO and SrSO4. It was also found a change in the chemical mechanism of the process between SrSO4 and CO-CO2 and in the chemical mechanism of the process between SrS and pure CO2.

Jan 1, 1995

By M. Omneya El-Hussaini, M. Galal Abdel Wahab, A. Mohamed Mahdy, M. Fathi El Shahat

"Lead-zinc mineralization is distributed in Egypt along the Red Sea coast between El Qusier and Ras Banas. A representative sample from Um Gheig was collected and ground to -60 mesh for the mineralogical study. It contains hemimorphite (Zn2SiO4.H2O), sphalerite (ZnS), galena (PbS), calcite (CaCO3) and dolomite (CaMg(CO3)2) beside the gangue minerals gypsum (CaSO4.2H2O) and hematite (Fe2O3). Cadmium seems to be incorporated in the crystal structure of the zinc-lead minerals. The chemical analysis of Um-Gheig representative sample revealed that, it contains 16% zinc combined with 0.1% cadmium, 2.3% lead and 0.1% boron beside other elements.Pug and agitation leaching were performed on samples ground to -200 mesh to achieve the maximum dissolution efficiency of cadmium with respect to other elements. Cadmium leaching efficiency reached 90% by using 40% H2SO4 at S/L ratio 1/2 and stirring time 2 hours at 80o C. Cadmium was then separated as yellow precipitate of CdS from the sulfate leach liquor containing 0.9 g/l Cd, 145 g/l Zn, 0.15 g/l B and 0.01 g/l Pb. Separation of cadmium was carried out by direct precipitation using Na2S as well as H2S. The recovery of 94% cadmium free of zinc was achieved.IntroductionLead-zinc ores occur in Egypt in a few localities distributed along the Red Sea coast between El Qusier and Ras Banas. Um-Gheig Pb-Zn ore is a replacement deposit in limestone and calcareous sandstone in the basal series of the Middle Miocene rocks. The reserve of the ore deposits has been estimated by Soviet and German Experts to be about 900,000 Ton, Bishai [1]. As has been mentioned, zinc is a common element and cadmium is comparatively rare in almost zinc minerals. It was estimated that zinc is 200 times as abundant as cadmium. According to Bodas [2] about 2.1% of cadmium was carried by the Zn mineral hemimorphite (15.3% Zn) in Thailand. Also, Onal et al., [3] found that 164 g/t Cd was carried by Pb–Zn ore sample containing 10.17% Pb and 10.98% Zn from Aladag in Turkey. Cadmium metal has gained great importance due to its wide applications in civil and navy purposes as well as in nuclear field. It is characterized by its ability to absorb thermal neutrons during the chain reaction inside the nuclear reactors. It is also used in the manufacture of sheets which directed the chain reactions [4]."

Jan 1, 2008

By Jing Zhan, Gui Li, Wei-feng Li, Li-Hua Jiang, Chuan-fu Zhang, Jian-yang Hwang

Thermodynamics analysis for processing the charge with lead concentrate and lead sulfate-containing materials in bottom blowing smelting furnace was conducted. The results show that the technology of large-scale processing PbSO4- containing materials with PbS concentrate in bottom blowing furnace under the condition of using high-iron slag type, batch heat supplement, high temperature and rich oxygen is thermodynamically feasible. The exploration test and industrial experiment confirm the results. When S content in mixed ore is 16~17% with coke foam content of about 5%, the lead paste amount can be increased up to 40%.

Jan 1, 2015

By Shivendra Sinha

Total pressure oxidation (TPOX) is widely outreached leaching practice for base metals from sulfide minerals, wherein high temperature (T ∼ 200 °C) and oxygen pressure (pO2 ∼ 25 bar) are required. These aggressive conditions intensify the oxygen mass transfer, and therefore facilitate metal dissolution. However, challenging-cum-negative aspects of such practice are energy and material intensive requirements and high oxygen demand. Thus, the present study explores the novel emulsified medium for enhancement of oxygen mass transfer, which assists faster metal dissolution at significantly lower temperature and pressure condition. It is possible to achieve quantitative dissolution (>95%) of Cu, Ni and Co from mixed sulfide minerals at T ∼ 95 °C and pO2 ∼ 2 bar using an emulsion of 2.5% (v/v) n-Hexadecane in dilute sulfuric acid. In addition, n-Hexadecane was found to be inert, stable and immiscible in a pressurized leaching system, thus can be easily separated and recycled in subsequent leaching stages. Thus, this study offers an energy efficient route for low temperature-pressure leaching of sulfides.

By Jafar Safarian

A new kinetic modelling technique has been applied to study the rate of MnO reduction from slags by dissolved carbon in liquid iron. Based on a consideration of the fundamental reaction kinetics, a general differential equation for the slag reduction process has been formulated, which then is solved analytically for certain special cases. By re-writing the solutions in a dimensionless form the poorly known kinetic constants are eliminated, which makes the model both flexible and applicable to a wide range of experimental conditions. For example, changes in process parameters such as temperature, metal composition, slag composition, gas composition can readily be captured along with variations in the crucible geometry. Based on a comparison with a series of experimental reduction curves being reported in the literature, it is concluded that the predictive power of the model is surprisingly good, yielding outputs that are both reliable and physically reasonable. An attractive feature of the model is that it provides an alternative way of calculating the activation energies from experimental reductions curves. For example, it suggests that the activation energy for the reduction of MnO by dissolved carbon in liquid iron is about 90 kJ/mol, which is different from the previously reported activation energies. The model also suggests that the crucible geometry, which affects both slag the volume and the resulting slag/metal interfacial area, has a significant influence on the overall reduction kinetics. This design parameter is a key to further optimisation of the process on an industrial scale.

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2 versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Leonel Contreras

The gas treatment system, MALIGAS (in Spanish MAnejo y Llmpieza de GASes which means handling and cleaning of gas), is part of the Codelco-Chile Potrerillos Smelter decontamination plan; which includes the newly designed system for the cooling and cleaning of the gas generated from a Teniente Converter and four Peirce Smith Converters. The gas generated in the process is captured by water cooled hoods and mixed with air. Then the gas enters a cooling pre-chamber which utilizes a water cooled screen to capture and remove the coarse and semi-fused particles. At this stage; the gas loses a portion of its heat with temperature falling below 608°C which is a necessary condition to avoid damage to the pipes, ducts and other metallic structure of the gas handling system. The gas is further cooled at the Radiation Cooler to a temperature ranging between 315 and 380°C. The gas is conditioned to avoid damage to the electrostatic precipitators that are designed to clean the gas by removing significant amount of dusts from the: gas stream. This gas stream is currently discharged to the stack, however, it will be treated in a sulfuric acid plant that is currently under construction and is scheduled for commissioning during the second half of 1999. The gas handing and cleaning system has been operated without any significant interruptions. Minimal emissions of SO2 and dusts in the work place are noted. The system requires minimum maintenance. The key to the high availability of the system is due to the good, performance of he Radiation Cooler, which efficiently cools the gas before entering the electrostatic precipitators (ESPs). This enables the ESPs to remove the dusts efficiently.

Jan 1, 1999

By Shun Myung Shin, Kang Jeong, Kyoungkeun Yoo, Jin Koo, Dong Hyo Yang, Soo Sohn

"The optimum discharging condition to dismantle the batteries without explosion was investigated to recycle the lithium primary batteries, which could be exploded by heating too much or crushing. The 3 waste lithium primary battery cells were discharged with 500 cm3 of 0.5 kmol·m-3 sulfuric acid. Fe concentration and pH increased rapidly after 3 days at 35? and after 1 day at 50?. Chromium concentration increased by 4 days at 35? and 2 day at 50?and then decreased, and nickel concentration was very low. Because Li concentration increased gradually, Li became dissolved after the dissolution of cover material. When the discharged batteries were shredded, the batteries discharged at 50°C were not exploded and those discharged during 3 days at 35°C were exploded. This result shows that the waste batteries could be stabilized within 1 day at 50°C and 4 days at 35°C. Introduction Lithium has some advantages for battery e.g. it is the lightest metals and also has the highest electrochemical potential at 3.04V[1]. For over thirty years lithium primary batteries became famous for their performance in various applications such as IT, medical, and military[2,3]. They gained a reputation for their long shelf life, constant voltage, wide operating temperature range, and low self-discharge characteristics[3-5]. World primary lithium battery market was expected to grow from $820.6 million in 2003 to $1,1355.3 million in 2010 (http://www.frost.com, Frost & Sullivan)[2-4]. The lithium primary batteries have very various sizes and components. Lithium batteries are made with lithium metal as anode active material and non-aqueous solvent as electrolyte. As cathode active material, various kinds of materials were used such as manganese dioxide (nominal voltage, 3.5V), thionyl chloride (3.6V), and carbon monofluoride (3.0V). In Korea, 50 % of the spent lithium primary batteries must be recycled because spent lithium primary batteries have been listed in EPR (Extended Producer Responsibility) of the enforcement degree of the act on the promotion of saving and recycling of resources. However, the batteries have been landfilled since there is no economic method to recycle the batteries in Korea[2,3]. When the batteries were heated too much, charged, pierced, over discharged, or short-circuited, the batteries explode because lithium reacts violently with water or air and because contents such as lithium, electrolyte, and sulfur become flammable by high temperature[4]. Therefore, it is so difficult to recycle safely the spent lithium primary batteries."

Jan 1, 2008

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Ahmet Geveci

[Generally accepted formula related to sulfur slag-metal distribution ratio is given by the following equation: [ ] According to the above equation it can be deduced that sulfur distribution between slag and metal is governed mainly by metal composition (?s term), slag composition (slag basicity and in turn sulfide capacity), oxygen potential of the system (ao¬¬ term) and temperature(related to equilibrium constant, K). In this study, the results of ladle furnace operations conducted in Erdemir-Iron and Steel Works Co. (Turkey) in relation to sulfur removal, have been given. Typical ladle furnace slag analyses of 4937K quality steel have been presented. Activity coefficient of FetO,?FetO, have been calculated with the relation obtained fromthe literature. Activity calculations have been performed with the program written in Mathcad. The changes in activity of aFetO in the slag phase,, have also been studied in relation to the sulfur removal: The relation between % Decrease aFetO and %DeS (measured)have been investigated for 4937K runs and someother types of steel produced in the Erdemir Plant. Related to ladle operations %desulfurization defined as [(%Sinitial-%Sfinal)/S%initial]*100 values have been presented for different steel qualities.]

Jan 1, 2006

By Dinabandhu Ghosh

The stability diagram of the ternary system Ti-C-O is drawn in the present work for four temperatures, 1473 K, 1573 K, 1673 K and 1873 K, showing the stability fields of TiC, Ti, TiO, Ti2O3 and TiO2. An analysis of the system reveals that it is not possible to produce Ti in a carbon-saturated system; instead, the stable product is TiC. However, Ti can be an equilibrium product in a carbon-unsaturated system at prohibitively low values of pCO and pCO2; for example, at 1873 K, these limiting values are: pCO = 10-6.76 atm and pCO2 = 10-13.36 atm, which, when exceeded, produce TiC and TiO respectively. The magnesiothermic reduction is examined through the stability diagram (log pO2 vs. 1/T) of the system Ti-Mg-O, drawn for a number of pMg values, presenting the pairwise stability fields such as Mg(l) + Ti(s), Mg(v) + Ti(s), MgO(s) + Ti(s), etc. The diagram shows that magnesium reduction of TiO to Ti is possible only at T < 1641 K with pMg = 1 atm and only at T < 1569 K with pMg = 0.5 atm. An experimental scheme for Mg vapor reduction of TiO2 is proposed in which an argon stream is passed over a Mg(liquid) evaporator at temperature T1 (say, 1234 K); the resulting Ar-Mg mixture at 1 atm is subsequently flown over a bed of TiO2 at temperature T2. A thermodynamic analysis establishes that complete reduction to Ti is possible and that the best results are obtained when T1 = T2.

Jan 1, 2006

By Carlos Schvezov, Eliana Agaliotis, Alicia E. Ares, Mario Rosenberger

"The interaction between a solidification front and a spherical particle was modeled and simulated in order to study the phenomenon of ""pushing"". Finite element methods were employed in axisymetric domains. The drag force is calculated from the calculated fluid flow field and the repulsion force is the Lifshitz-Van der Waal force. The thermal field is decoupled from the force field. The model is applied to a metallic matrix containing particles with similar, lower or higher thermal conductivities than the matrix, resulting in planar, convex and concave interface shapes, respectively.The results show that the critical velocities for pushing for concave and convex interfaces are about one order of magnitude larger and one order of magnitude lower than the critical velocity for flat interfaces, respectively. The simulated results were in very good agreement with reported experimental results.IntroductionThe solidification interface of materials containing spherical particles in some cases can push the particle ahead the interface. This phenomenon generally occurs during the solidification of different materials such as, metallic alloys containing native particles, metal matrix composites containing particles or fibers as reinforcements and crystallization of semiconductor, optical, optoelectronic or biological materials. In all cases the interaction strongly determines the distribution of particles and the resulting physical and physic-chemical properties of the resulting material. The phenomenon has been investigated for many years both experimentally and by mathematical modeling [1-21]. The process is complex due to the variety of phenomena involved during pushing. In all cases, the physical problem depends on the properties, nature, and morphology of the interacting media; the particle, melt and solid; and external fields such as gravity, thermal and electromagnetic fields."

Jan 1, 2012

By Shadia J. Ikhmayies

"Nanocrystalline fluorine-doped tin oxide, SnO2:F, thin films were prepared by the spray pyrolysis (SP) technique on glass substrates. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray dispersive spectroscopy EDAX and transmittance measurements. X-ray diffraction patterns revealed the nanocrystalline nature of the films where the grain size was estimated based on the Sherrer formula. SEM micrographs showed that the films are uniform and totally covered with the material and they confirmed the nanocrystalline nature of the films. The absorbance was deduced from the transmittance measurements, and its first derivative was used to estimate the optical bandgap energy. Bandgaps larger than the bandgap of the bulk SnO2iF were obtained, indicating the presence of quantum dots. The hyperbolic band model was used to estimate the radii of the nanocrystallites. A comparison between the results of the different methods was performed.IntroductionTin oxide, SnO2, thin films are n-type semiconducting, transparent materials, which have numerous important applications in optical-electronic device technology. The optical transparency of SnO2, together with its chemical and mechanical stability, makes SnO2 films suitable for many other applications, such as transparent conductive coatings, gas sensors and heteroj unction solar cells [1]. In particular, SnO2 thin films have drawn much interest because of their potential application and integration with microsensor devices. Considerable attention has recently been focused on the development of solid state gas sensors based on thin films with a crystallite size smaller than the Debye length of the material, which show increased gas sensitivity and short response times [2]. In many of these applications, a doped SnO2 film is used as an active layer. Among the various dopants, fluorine is often preferred, because fluorine doping results in films with high transparency and good conductivity [1]."

Jan 1, 2012

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By V. A. Shumsky, I. P. Polyakov, N. M. Ospanov, M. A. Lyamina, N. N. Ushakov

Studies on the kinetics of the competitive processes of PbS volatilization and PbS oxidation, as applied to the heat and mass transfer conditions in the flame of the Kivcet furnace, revealed that the rate-determining factor is the supply of heat. Therefore, low yields of fume in the autogenous flash smelting of lead sulphide feeds are noted despite the high volatility of PbS at 1,300-1,400°C. Dust formation in the autogenous flash smelting of Kivcet-smelters does not exceed 5-7%, of which fumes amount to ~ 80%. Using extra fuel during autogenous smelting involves the mismatch of the sulphide oxidation rate and the release of heat in the flame, and increases the fume yield. This is a major cause of the high dust formation in pilot plant trials. The analysis of dust formation in the Kivcet smelting of oxidized lead feeds in an industrialscale smelter shows an overall increase of dust formation (up to 10% of the feed), with fumes constituting ~ 80% of the dust. A pronounced increase of the zinc component of the fumes is also noted. Lead

Jan 1, 2000

By Nedam Abed

A fundamental study of the sonochemical leaching of chalcopyrite in ferric ion media has been performed to understand and quantify the effects of sonication and other parameters on leaching reactions. The study covers sulfate and chloride media. The main leaching reaction: CuFeS2(s) + 4Fe3+(aq) Cu2+(aq) + 5Fe2+(aq) + 2S(s) (1) was found to be dependent on temperature and initial particle size, but less dependent on ferric ion concentration. Leaching kinetics were not affected by ferrous ion concentration or the amount of chalcopyrite added. Leaching was performed under a variety of sonication and leaching conditions. Reaction stoichiometry was confirmed through detailed wet chemistry analysis and mass balance calculations. The use of ultrasound activation showed a clear improvement in leaching kinetics and amount of copper extracted, sonication having a catalytic-like effect on the leaching reaction. Compared to experiments without sonication, reaction rates were 2-3 times faster at the same temperature, and could be faster by a factor of 20 for the same initial particle size. Regardless of initial particle size, the amount of copper extracted was comparable under sonication, and could be twice that under chemical leaching, implying the avoidance of fine particle grinding. Sonochemical leaching was found to be only temperature dependent, where the best copper extraction was at 75C. Leaching was further enhanced by the use of a grinding aid. The leaching behavior of chalcopyrite particles remained similar with and without ultrasound activation, implying that the known passivation mechanism in the oxidative leaching was not eradicated. Sonication resulted in coarse particle breakage (ultrasonic milling). Sonication did not contribute to particle passivation, as affirmed from different leaching procedures and sonication in aqueous and organic media. Parabolic leaching kinetics were confirmed for leaching experiments.

Jan 1, 2003