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By N. J. Themelis

In the last two decades, the Outokumpu flash smelting process has become the dominant new technology for copper smelting and has? also been applied to the smelting of other metal sulfides. The application of oxygen enrichment and improvements in concentrate burner and furnace design have resulted in ever increasing smelting rates per unit volume of the reaction shaft. This paper examines the. rate phenomena taking place in the reaction shaft of the Outokumpu furnace and compares information obtained from a mathematical model of heat and mass transfer rates to results obtained in pi1ot tests conducted at Pori, Finland, and to actual performance of a number of flash smelters around the world. 2?

Jan 1, 1985

By R. W. McCallum, B. Jensen, K. W. Dennis

"There are substantial challenges in the exploration of magnetic materials in the R-TM-X system (R =rare earth, TM= transition metal, X =stabilizing element) where Xis an element which has high vapor pressure, high reactivity, toxicity, or a refractory nature. This research focuses on discovering new phases with high anisotropy and high magnetization through closed diffusion couples inside high purity Fe crucibles. Either vapor-solid reactions or powder metallurgy techniques are then employed to isolate a stoichiometric sample based on a potentially magnetic phase found in the diffusion couple. For this research, X = F, Ca, Sr, Se, Zn, Bi or Cd, TM= Fe, and R = Nd. New ternary phases have been discovered with WDS and EDS, and magnetic transition temperatures have been measured with a SQUID magnetometer and VSM.IntroductionSince the discovery of the RCo5 compounds in the 1960s, rare earth- transition metal (R-TM) magnets have been the main focus of permanent magnetic research over the last five decades. Iron-based magnetic materials were studied next in attempts to avoid the unstable price of cobalt as well as the high price of Sm, the top performer in the RCos and RzC011 series. This hunt eventually led to the discovery of Nd2Fe14B with a theoretical BHmax of 64 MGOe, nearly double that of the previous samarium based magnets. The next few decades were devoted to enhancing the magnetic properties ofNd2Fe14B by the improvement of processing techniques and the additions of alloying elements. The only complete elemental substitution discovered in this system was R1Fe14C, which did not improve magnetic properties. It is probably safe to say that most ternary R-TM-X systems, where Xis any element that may stabilize a ternary phase, have been investigated if they may be prepared by conventional processes such as arc or induction melting. The present study offers a systematic approach to developing a novel diffusion couple technique in which the volatile, reactive or toxic alloying elements are laser welded inside a high purity Fe crucible. This experimental setup will prevent the oxidation of the rare earth element, as well as contain the volatile X element. As the goal of the research was to find new rare earth permanent magnets, only phases which contained greater than 60 wt% Fe were investigated. 247"

Jan 1, 2012

By Filippos Patsiogiannis

Laboratory size (4.5 kg) low carbon steel melts were deoxidized using Al and FeAl (33% Al), with and without synthetic fluxes, in alumina and zirconia crucibles. The dissolved oxygen, total oxygen, soluble aluminum, insoluble aluminum, silicon and carbon contents in the melt were determined as a function of refining time and temperature. It was observed that the reaction between aluminum and oxygen in solution closely follows thermodynamic equilibrium. Silica present in the alumina crucibles was found to be a source of oxygen for the melt, while this was not the case for zirconia crucibles. Reoxidation of the melt occurred through oxygen pick-up from the atmosphere. The extent of this reoxidation was found to be a function of oxygen content of the bath and the slag cover on the surface of the melt. The effectiveness of calcium-aluminate based fluxes in protecting the melt from the reoxidation and in increasing the rate of removal of inclusions was evaluated.

Jan 1, 1992

By T. Kimura, H. Ohba

"Much effort has been made to reduce the energy requirement in zinc electrowinning. In order to keep energy consumption low, either to make cell voltage low or current .efficiency high is necessary. Decrease of cell voltage practically depends on how to reduce ohmic resistance in the electrolyte and the anode crust. To realize these, new concept was proposed and the pilot plant has been operated. The space between a cathode and an anode is halved by utilizing the frame insulator. With these frames the anodes and cathodes compose of a unit of electrodes, and this unit is handled by newly designed electrode handling machine (E.H.M.). The process includes lifting up electrodes, expanding the space between a cathode and an anode, cleaning them, stripping the deposited zinc and returning the unit to the cell. As a result, cell voltage is kept as low as calculated and predictable energy reduction has been achieved. IntroductionIn the recent trend of a rapid appreciation of the Japanese yen, Akita Zinc Refinery of Mitsubishi Metal Corporation has been confronted by problems of relatively high operating costs. In order to compete with other overseas zinc refineries, it is necessary to reduce the cost of zinc production, especially the cost of electric power which now accounts for .up to 35 % of the entire cost of production. Three fourth of the electric power used at Akita Zinc Refinery is for the electrolysis. Therefore it is extremely important to reduce the cost of electrolysis.There are two possible measures for solving the problem; one is to use more nighttime electricity taking the advantage of its inexpensive power price, and the other is to reduce electric power consumption.As a part of a rationalization plan carried out in 1986, Akita Zinc Refinery increased the number of operating cells. As a result, when nighttime electricity is used, the silicone rectifier has been able to operate at full capacity. Moreover, by new schemes of ""increase of area for electrodeposition by ralslng the liquid level of electrolyte"" and ""increase of the number of electrodes in each cell"", current density could be lowered and as a result, the electric power consumption has been improved. In order to raise nighttime ratio even higher, installation of an additional rectifier and cells would be required."

Jan 1, 1988

By Sridhar Komarneni

"Microwave-hydrothermal processing is a novel technique which combines the conventional hydrothermal processing with microwave field and we previously showed for the first time, that ceramic powders can be rapidly produced by this technique. This review paper deals with the synthesis of unary oxides such as Fe203, Ti02, Zr02, etc., binary oxides such as BaTiO3, SrTiO 3, PbTiO 3, SrZrO 3, KNbO3, etc., and ternary oxides such as NaTi2 (PO4)3 and pyrochlore phases of Pb(Mg1/3Nb2/3)O3, Pb(Zn1/3Nb2/3)O3 etc. and metal powders such as Cu, Ni, etc. below 195°C. This method can be adopted to the synthesis of a large variety of powders by the appropriate control of pH, Eh, temperature/pressure and concentration of chemical species. The main advantages of this method compared to conventional hydrothermal processing are (a) it increases the kinetics of reaction by one to two orders of magnitude, and (b) it can lead to novel phases especially those with layered structures.IntroductionConventional hydrothermal processing is a well-established synthesis technique which has been extensively used in the preparation of fine ceramic powders [1-5], large single crystals [6-8] and massive cement blocks [9]. Technologically important ceramic powders such as BaTiO 3, Al203 etc. made by the hydrothermal process are now commercially available. Although there are numerous methods for materials synthesis, hydrothermal method is truly a low temperature and environmentally benign process. For example, ZrSi04 (Zircon) which is extensively used in ceramic industry can be prepared hydrothermally at 150·C [10] compared to sol-gel or solid-state method [11,12] which require a temperature of about 1000·C. The hydrothermal method is environmentally benign because hydrothermal reactions are carried out in closed systems at low temperatures and the contents can be recovered and recycled after cooling to the ambient conditions. One of the disadvantages with any low temperature processing method is slow kinetics. For this reason we have combined the hydrothermal method with microwaves to enhance kinetics and we named this method as ""Microwave-hydrothermal"" processing [13- 16]. Although the combination of microwave and hydrothermal techniques has been used in the past few years to dissolve all kinds of inorganic (e.g. alumino silicate rocks) and organic materials rapidly for chemical analysis, we were the first to show its potential value for the synthesis of various ceramic powders [13-16]. In this paper, I show that this novel method is applicable to the synthesis of all unary, binary and multinary oxides by the appropriate control of pH, Eh, temperature, pressure and concentration of chemical species. In addition, this method is also found to be useful for the preparation of metal powders."

Jan 1, 1994

By A. Perillo

The process, realized in. the Kivcet furnace, can convert continuously lead concentrates, residues and secondary lead bearing materials into a lead bullion free of sulphur and a discardable slag. The lead recovery can be up to 99%. The long experience of about three years at Portovesme demonstrates the capability of the furnace to smelt a very. high range of lead raws without interruption of the operation. The operating costs are very competitive in comparison to the traditional technology. The work place and environment are clean and new tight regulations for the? hygiene control are met. The Kivcet furnace can be considered as consisting of three parts (reaction shaft, waste gas shaft and electro-furnace) connected with a common hearth. The technical basis of the furnace construction is the application of a number of design elements .which have mostly been used before in designs of industrial furnaces, such as open hearth furnace, refining furnace and other furnaces dealing with liquid meta1s. Refractory wear in the reaction shaft with typical pattern from watercooling soon has been stabilized and since maintained. No deformation of the furnace shell and no leakage of metal or s:l:ag through the bottom is? appeared after three years' operations.

Jan 1, 1990

By M. L. Apel

A conceptual approach to the bioremediation of uranium mill tailings (UMT) is presented., This approach focuses on, biosorption to remediate the. effluent solution and bioleaching remediate the. solid fraction. Comparative biosorption studies were performed with synthetic single metal solutions using a commercially available biopolymer. The maximum rate of metal sorption by calcium alginate was found to be 5.43, 6,39, 6.48, and 9.74 mg dm-3 min-1 for U022*, Ba2+, Cd2+ and Zn2+, respectively. Activation energy (AEa) for barium uptake by calcium alginate beads was determined to be 11.5 kJ, indicating a diffusion controlled reaction mechanism. Thermodynamic values (AG+ AH+ and ASt) of the metal-alginate activated complex, as reported in the literature, were found to be in agreement with those calculated from this research. Results show that this biopolymer can be effectively applied in the removal of select metals prevalent in uranium mill tailing effluents and associated waste streams.

Jan 1, 1991

By P. Tim Johnson

Relentless increases in demand for nickel and vanadium for uses such as steelmaking, catalysts and battery materials, plus the growing financial and environmental costs of their primary extraction, have led to much interest in potential secondary sources of these metals. The presence of such metals in heavy fuel oils, bitumen and related materials offers both opportunities and challenges for potential extraction methods, especially with the growing production and importance of metal-rich fossil fuels around the world. For several decades, Tetronics’ DC plasma smelting technology has been used for the recovery of metals such as nickel and chromium from stainless steel melt dusts and other wastes in compact, environmentally-friendly and efficient plants. This paper explores the suitability of DC plasma smelting as part of a wider flowsheet with feed preparation and aluminothermic reduction techniques for smaller-scale extraction operations based on this important niche secondary source of these key metals.

By Ramana G. Reddy

Thermodynamic modeling and experimental study on impurity capacities and their distribution between mattes or metal and slags in smelting, converting and refining of non-ferrous metals was discussed. A brief review on the recent developments in copper smelting and converting is presented. The analysis showed that, copper smelting capacity increased by a factor of 10 since 60's, smelting rate increased by a factor of more than 5 and process fuel equivalent decreased by a factor of 2. A thermodynamic model for prediction of impurities capacities in slags and their distribution in mattes and slags was developed. The impurities capacities (i.e. sulfur and arsenic) of slags were calculated a priori with no adjustable parameters using the Reddy-Blander model. The capacities predictions were made in a wide range of matte and slag compositions, PSo, and temperatures in conditions pertaining to copper and lead industrial slags. The calculated results for sulfide and arsenate capacities are in good agreement with the available experimental and industrial copper and lead industrial slags data. The sulfide and arsenate capacities in copper slags (fayalite, ferrite and olivine) and lead slags are reviewed. The application of RB model predicted ratios of O2 and S2 partial pressures in industrial copper smelting processes are discussed. Application of this model for the prediction of Sb, Bi and other impurity capacities and their distribution ratios in mattes or metal and slags, in industrial smelting and refining processes is discussed.

Jan 1, 2003

By Xiaojie Gao, Jingshe Li, Chengsong Liu, Haiyan Tang

In order to clarify the reaction between MnO-SiO2 oxides with low FeO content and Fe-Mn-Si alloy, two diffusion couples were produced by the new method using confocal scanning laser microscopy (CSLM). The interface of the alloy and oxide, content of Mn and Si in the alloy near the interface, size distribution and composition of the particles which precipitated in the alloy were observed and analyzed using the electron probe microanalysis (EPMA). Results show that though the FeO content in the oxides decrease to 1% which is lower than the equilibrium with the molten steel at 1873K, the diffusion of oxygen from oxide to alloy still exists during the heat treatment at 1473K and causes shorter Particle Precipitated Zone (PPZ) and Manganese Depleted Zone (MDZ) normally for the reduction of diffusion flux of oxygen.

Jan 1, 2015

By G. Belardi

A study has been conducted to assess a new wet beneficiation treatment for the recovery of the sulphuric-acid-soluble titanium oxide contained in the waste from an Italian TiO2-pigment facility. The waste is produced during treatment of a Ti-enriched slag and contains as main components TiO2 (54%, of which 42% acid-soluble and 12% insoluble), SiO2 (27%) and A1203 (6%). Eighty percent of the material is finer than 50pm. The first step was to ascertain the possibilities offered by size classification, wet gravity separation, froth flotation and wet high-intensity magnetic separation to improve the grade and recovery of Ti02 and reduce the SiO2 content. The next step was to optimize the operating conditions of the various separations and assemble them into a complete flow- sheet. Beneficiation ensures potentially 70% recovery of the TiO2 with a concentrate grade of 80%.

Jan 1, 1998

By S. Neogy, M. Gupta, D. Srivastava, V. Kain, S. Roychowdhury, R. C. Prasad, G. K. Dey

"Austenitic stainless steels are an important material of construction for Boiling Water Reactors (BWR). These stainless steels are amenable to strengthening by strain hardening. Various deformation modes at different test temperatures and strain become active. In the present investigation type 304LN stainless steel was used in the annealed and strain hardened condition. Thin foils were prepared from gauge section for transmission electron microscope (TEM) investigation after tensile testing at room temperature and at 288°C. TEM investigation reveals that twinning is the major mode of deformation for the tests done at room temperature while dislocation cross-slip is the major mode of deformation at higher temperature. Stacking faults were also observed to a limited extent. The extent of twinning was much higher for the tests done using the rolled material. The formation of martensite in the stainless steel due to straining was investigated by the analysis of selected area diffraction patterns.IntroductionAustenitic stainless steels (type 300 series) are an important material of construction in Boiling Water Reactors (BWR). These stainless steels cannot be heat treated but can be strengthened by cold working [1]. Nitrogen alloying of these stainless steels result in high strain hardening rates and higher strength without any loss in toughness [1]. Stress Corrosion Cracking (SCC) in BWR of these types of stainless steels have been attributed to surface strain hardening and strain hardening ofregions adjacent to constrained weldment [2].The test temperature [3, 4], prestrain [5] and nitrogen level [5] has been reported to affect the deformation mechanism during tensile testing. Byun et al. [3] have reported the formation of martensite, dislocations, stacking faults and twinning during tensile deformation, the extent of each depending on the test temperature. Strain localisation has been reported to occur during tensile deformation in irradiated stainless steels [ 6]. The behaviour of rolled material during tensile testing is similar to that of irradiated material to a large extent [3]. Austenitic stainless steels are low stacking fault energy (SFE) materials in which various types of microstructures have been reported to form during tensile deformation and the strain is also highly heterogeneous in nature in these stainless steels which aides SCC in BWR environment to a large extent [7]. During cold working of austenitic stainless steels second order twinning has also been reported [8]. Knowledge about the deformation mechanisms operative in the strain hardened austenitic stainless steels during tensile testing at different temperatures is essential to understand the material deformation behavior and the present study aims at enhancing the existing understanding."

Jan 1, 2011

By Ryosuke O. Suzuki

A new cell concept for calciothermic reduction is proposed in which the titanium dioxide instead of TiCl4 is used as the raw material for reduction, Metallic calcium is needed as the reductant of a thermochemicaily stable oxide, such as TiO2. CaCl2, is selected as the solvent of Ca and simultaneously as the solvent of CaO. The reduction system consists of a single cell where both the reduction reaction and the electrolytic reaction for recovery of reducing agent coexist in the same molten CaCl2 bath. A few mol%Ca dissolves in the melt and gives the media a strong reducing power. Sufficiently deoxidized metallic titanium deposits and forms a slightly sintered granular sponge. Both mechanisms of the halide flux deoxidation and the electrochemical deoxidation work efficiently for these fine precipitates, The reducing agent is in situ recovered by electrolysis of CaO because the molten CaCl2 he a relatively large solubility for CaO Some cell designs and modifications are proposed for industrial applications.

Jan 1, 2003

By Joël P. T. Kapusta, Romeo U. Pagador, Noparut Wachgama, Chumnoom Khuankla

"Thai Copper Industries (TCI) is a custom copper smelter and refinery in Rayong, Thailand, with an annual capacity of 165,000 tons of cathodes. It employs the El Teniente Technology as the primary smelting reactor to produce white metal from copper concentrates. The white metal is further treated in Hoboken Siphon Converters to produce blister copper then refined in anode furnaces before being cast into anodes for electro-refining in the on-site tankhouse.Thai Copper Industries is the first copper smelter to install and successfully operate on a commercial scale with the Air Liquide Shrouded Injection (ALSI™) Technology in the Hokoben converters with sonic injection of oxygen enriched air and nitrogen for cooling of the injector tip areas. Following commissioning and the establishment of operating practices, the performance of the Hoboken converters with ALSI™ Technology produced outstanding results. The unique combination of an El Teniente and Hoboken siphon converters, both of which are bath smelting operations, offers very high blowing and oxygen efficiencies. As a consequence, reverts recycling was accelerated with minimal build up on the mouth, end-plates or even below the siphon that is typical in Hoboken converters.These outstanding results in the Hoboken Siphon Converters with ALSI™ Technology helped the TCI Plant reach a production of about 75% of its capacity within four months despite the fact that the TCI staff is quite young and its converter know-how and experience are not yet fully developed."

Jan 1, 2009

By G. Diáz

The PLACID process applied to the recycling of spent lead-acid batteries is being developed by an European Consortium within the Brite-Euram II programme. The status of the project entitled "Lead Recovery from Lead Oxide Secondaries" is described in this paper. The main laboratory and batch experimental results and the preliminary feasibility study are summarised. The description of the demonstration pilot plant and continuous campaigns programme for 1995 are also included. An interesting global approach is proposed, integrating the Placid process in the existing spent battery recycling pyrometallurgical facilities. This yields important improvements in the overall process. Grids would be easily treated by the conventional pyrometallurgical route, obtaining lead alloys,, while battery pastes, slags and fumes would be fed to the Placid process, obtaining pure electrolytic lead (>99.99 %), ideal for battery paste manufacturing. The implementation of the Placid process into the existing battery recycling pyrometallurgical facilities is analyzed from technical, environmental and economical viewpoints. Greater overall lead recovery, lower operating costs, reduced waste production, environmentally safer residues and much better lead product quality are the key advantages. The authors draw the following final conclusion : Integration of the Placid process with conventional pyrometallurgical treatment is a feasible and very attractive alternative route for spent lead-acid battery recycling.

Jan 1, 1995

By T. Wang, R. G. Reddy

"A new eutectic of LiNO3-NaNO3-KNO3 ternary system was calculated by using thermodynamic modeling and the eutectic temperature was predicted to be 389.15K. The melting point was determined using Differential Scanning Calorimetry (DSC). On repeated measurements, it was found that the melting point of the eutectic composition showed excellent reproducibility with the predicted value. The heat capacity was also measured using DSC and the data as function of temperature were fit to polynomial functions. Subsequently, the thermodynamic properties such as enthalpy, entropy and Gibbs energies of this novel ternary eutectic salt mixture were deduced as function of temperature.IntroductionIn these days, the provision of the large amount of energy required in the peak period relies more and more on the parabolic trough solar power plant and it works by utilizing the thermal transfer fluid. Consequently, the development of inoovative thermal transfer fluid with higher energy storage density is paramount to lower the expense for generating energy [1-4]."

Jan 1, 2013

By P. Rooney

In due course, new smelters will have to be installed in order to meet the increasing worldwide demand for copper. This paper presents the results of a study made for the purpose of identifying the most desirable countries in the world in which to locate a new smelter. Both sociopolitical and economic factors were taken into account. Criteria developed and methods used to assess each possible location are described. The study indicated that the most interesting potential locations are Canada, -Chile, Portugal and the USA for new copper smelting complexes.

Jan 1, 1983

By Frame Ritzert, Dennis Keller, Vijay Vasudevan, David Arenas

"An investigation was conducted to describe topologically close packed (TCP) phase instability as' a function of composition in the advanced ·Ni-base superalloy Rene N6. TCP phases are detrimental to overfill high-temperature performance of Ni-base superalloys because of their brittle nature and because they deplete the Ni-rich matrix of potent solid solution strengthening elements. Thirty-four variations of polycrystalline .Rene N6 determined from a design-of-experiments approach were cast and homogenized at 13 l5°C for 80 hours followed by exposure at 1093°C for 400 hours to promote TCP formation. The alloys had the following composition ranges in atomic percent: cobalt 10.61 to 16.73, Mo 0.32 to 1.34%, W 1.85 to 2.52%, Re 1.80 to 2.11%, Ta 2.36 to 3.02%, Al 11.90 to 14.75%, and Cr 3.57 to 6.23%. Physical and chemical characteristics of all microstructures obtained were described using various analytical techniques. From these observations, a mathematical description of TCP occurrence (s and P phase) was generated for polycrystalline Rene N6.IntroductionNi-base superalloy single crystals represent the state-of-the-art for turbine engine airfoil application as they offer the best balance of properties to allow for the high operating temperatures required: for efficient engine operation.1 Current trends in alloy design take advantage of improved creep rupture strength with the addition .of higher levels of refractory elements. 2 In .particular, the addition of significantly higher levels of Re in third generation superalloys is key for both microstructural stability and creep rupture strength. 3 While the presence of the refractories is thought to provide strength benefits from solid solution hardening, a tendency for alloy instability in the form of topologically-close-packed (TCP) phases or secondary reaction· zone (SRZ) ·phenomena accompanies the high refractory content. 3 The formation of these phases in sufficient amount is detrimental to the overall high temperature performance of Ni-base superalloys because of their brittle nature and because they deplete the Ni-rich matrix of potent solid solution strengthening elements.4 The tendency for a particular composition to form TCP may not be immediately known since the precipitation of TCP phases in Ni-base superalloys is nucleation controlled, thereby requiring long times at elevated temperatures to precipitate. 5 They preferentially nucleate along the octahedral planes of the Ni-base superalloys, usually in areas of refractory metal enrichment at grain boundaries or inside dendrites.5-6 In Rene N6, two closely related TCP phases, a and P, have been observed.2"

Jan 1, 1998

By B. Madelin

Over the last ten years, Minemet Recherche and Metaleurop have used an approach in order to investigate and improve the operation of its Smelting furnace and its lead blast furnaces. This approach gives importance- to three complementary means of investigation : - Probing campains in the industrial furnace (temperature and gas analysis profiles), - Chemical and physical modeling (coke combustion, sinter reduction modes, flows patterns, ?.) , - Staged mass and heat balances or kinetic model. This allows to define the limits of operation of each blast furnace and to predict the influence of operating parameters on the furnace performances. For the zinc Imperial smelting furnace, the probing results show the existence- of both an Isothermal reserve zone at 1015ºc and a chemical equilibrium between ZnO and gas which makes possible the use of a practical model for heat and material balances. In particular, very good prediction on the influences of operating parameters can be made. On the contrary, for lead blast furnaces, the probing results show that the thermal and chemical equilibria are not reached. Consequently, classical models for staged heat and mass balances are not sufficient. The use of the other means allows then to characterize the specific influences of operating parameters on the thermal instabilities of these furnaces and their allowed limits.

Jan 1, 1990

By Eun Duck Park

The gold catalyst supported on iron oxide was prepared from gold dissolved in aqua regia by a deposition-precipitation method and applied to CO oxidation in the absence and presence of hydrogen. Some characterization methods such as X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM), temperature programmed reduction (TPR), temperature programmed oxidation (TPO), and the pulsed CO chemisorption with temperature programmed desorption (TPD) were conducted to explain different catalytic activities of Au/Fe2O3 catalyst pretreated at different conditions. The particle size of gold was about 10 nm for Au/Fe2O3 calcined in air at 373 and 573 K. For complete CO oxidation, the decreasing CO conversion with a reaction time was observed at low temperatures but its initial catalytic activity can be restored by a heat treatment at high temperatures. This catalyst was quite active for the selective CO oxidation in the presence of hydrogen especially at low temperatures. In the presence of hydrogen, the deactivation was significantly diminished.

Jan 1, 2006