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By C. A. Nogueira, F. Margarido

"A research work has being carried out annmg at evaluating the possibility of treating simultaneously several electrochemical systems of spent batteries using the same process, in order to overcome the high costs and difficulties of selective collection and sorting. Zn-Mn02 systems, representing more than 75% of portable battery market, shall be treated in dedicated processes. The treatment assessment using a single hydrometallurgical process of the other major systems (NiCd, NiMH and Li-ion), having Ni and Co as main metals, was the aim of the research work here reported. Sulfuric acid leaching was demonstrated to be adequate for dissolving more than 90% of the metals of interest contained in batteries. The subsequent separation of metals by solvent extraction, using organophosphorous extractants like DEHPA and Cyanex 272, allowed the production of pure solutions of rare earths, cadmium/manganese, cobalt, nickel and lithium, enabling their further recovering.IntroductionRecycling is the best approach for end-of-life management of spent batteries mainly by environmental reasons but also motivated by resources conservation and, in some cases, by economic profits. Most relevant electrochemical systems of portable cells are Zn-Mn02 (ZMB, alkaline and saline), nickel-cadmium (NiCd), nickel-metal hydride (NiMH) and lithium-ion (LIB). These batteries are collected, sorted and usually treated separately, applying for pyrometallurgical or hydrometallurgical technologies, the former being the most common.Several processes have been developed and some of them industrially applied, as described in some available review papers [l, 2]. In Europe for ZMB systems the oldest processes are Batrec [3] and Citron [4]. Although having differences in details, both are based on pyrometallurgical recovery of zinc by distillation, in metallic or oxide forms, being manganese retained in the slag together with iron. Hydrometallurgical alternatives are also available, like Zincex [5] and Recupyl [ 6] processes, both using sulfuric acid solutions as leachant. The application of the existing technologies to battery recycling, instead of using dedicated processes, is other alternative already tested, being the Waeltz furnace or the Imperial Smelting some examples."

Jan 1, 2012

By Linda C. White

The use of red mud, a waste product of the ?Bayer? process for bauxite refining, was investigated for its arsenic removal effectiveness from aqueous solutions under various conditions. Red mud efficiently removed As(III) between a pH range of 7.6 and 9; and As(V) in the pH range between 5.5 and 6. Pre-washing of the red mud with salt water considerably improved its arsenic adsorption capabilities. With appropriate red mud dosage, the residual arsenic in solution was decreased below the regulated acceptable arsenic limit (0.1 mg/L) from aqueous industrial wastes. The arsenic adsorption followed first-order rate kinetics and fitted the Langmuir isotherm model. Results suggest that red mud is potentially a useful adsorbent for removal of arsenic from contaminated water or industrial waste solutions.

Jan 1, 2003

By S. Seetharaman

A mathematical model has been developed to evaluate the viscosities of melts at high temperatures. The viscous flow in liquid is described by the equation, {n = Aexp(AG*/RT)} based on the absolute reaction rate theory. The Gibbs energy of activation,{ AG* } is considered to be a function of the temperature as well as the composition of the melt. The model has been applied successfully to various metallic and slag systems from unary to quaternary. On the basis of this model, a relationship has been suggested to relate the Gibbs activation energy of viscosity to the Gibbs energy of mixing in binary metallic melts. The viscosities predicted from available thermodynamic data in the case of a number of binary metallic systems using this correlation show satisfactory agreement with the reported experimental values.

Jan 1, 1994

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study reactions of sulfidic nickel particles. The studied materials were three natural nickel concentrates and four synthesised nickel mattes. The variables of the experiments were the gas preheating temperature (500 - 1300°C), the composition of the reaction gas (N2 + 0 - 75 vol-% 02) and the ,particle size of the feed. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect alteration in their morphology, internal composition and structure. General reactivity of the materials was monitored by the extent of sulfur removal. The reaction mechanism of the studied materials was found to depend primarily on the materials composition as well as oxygen content of the reaction gas.

Jan 1, 1998

By Adriana de Aquino Soeiro da Silva, Joao Alves Sampaioa, Luiz Carlos Bertolino, Francisco Manoel Garrido, Marta Eloisa Medeiros

"Brazil has a large agricultural potential and its production success is related to the chemicaland physical soil characteristics. Therefore, the demand in the use of a great quantity offertilizers to compensate the low amount of nutrients in the soil includes about 40% of foodproduction costs. In order to develop economical alternatives to traditional fertilizers, rockswith potential use in agriculture will be studied. In this work the potassium rock, a greensandslate, will be chemically and structurally characterized for the development of a potassiumthermophosphate. This alternative fertilizer will be obtained based on a fusion of a ponderedmixture of potassium, magnesium and phosphate rocks to be applied in the Brazilianagriculture. Preliminary characterization results indicate that the greensand slate presents ahigh percentage of glauconite, quartz and micas.Keywords: Potassium thermophosphate, alternative fertilizers, greensand slate.IntroductionBrazil has a great agricultural potential and its production success is closely related to thesoil's chemical and physical characteristics. However, the country's soils present lownutrients content and high acidity due to weather conditions. Thus, the use of a high amountof fertilizers makes up for the soils' lack of nutrients and accounts for 40% of food productioncosts. Therefore, research on obtaining new alternative fertilizers is a constant worry due tothe increase on food demand [ 1].The lack of raw material for the preparation of NPK fertilizers in Brazil is a concern and theissue of potassium fertilizers a priority. Such a fact is because in 2008 only 608.000 tons ofKCl were produced, corresponding to just 10% of the Brazilian necessity. Thus, the use ofrocks as agricultural nutrients can contribute to reduce the need for industrial fertilizers.This way, the development of a new agricultural raw material originated from a rock thatalready exists in the country's soil is of great importance for the mineral and agriculturalsectors."

Jan 1, 2011

By Robert D. Rogers

The demand for phosphate will continue into the future, because phosphate is currently irreplaceable as a plant nutrient and in many chemical applications. Phosphate is not recycled, so the supply must be replenished through a process of mining and purification. Numerous microbial isolates. obtained from the environment were screened find those which demonstrated the greatest promise of solubilizing PO4 from the ore of interest. Screening was accomplished in a step wise manner an agar plate bioassay, shake flask studies, and semi continuous growth conditions. It was found that with the proper conditions of nutrient supply and solution pH; the bacteria and. fungus used in the semicontinuous process were able to solubilize in excess of 80% of an Idaho rock phosphate ore (RP) within nine days. A significant amount of solubilization occurred within the first six days. There was a 'reasonable correlation between the occurrence of soluble Ca and PO.4 during the processing of the RP thus providing evidence that the RP was being disintegrated by the organisms. In all cases, HPLC analysis of the solutions in which PO4 had been. extracted from RP showed that organic acids, which have been implicated as the mechanism of solubilization, were present.

Jan 1, 1991

By Kirsi M. Riihilahti

The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. The effects of feed matte grade, matte particle size, oxygen-to-matte mass ratio, oxygen content of the process gas and temperature on the particle oxidation rate, quality of conversion, particle size change and particle morphology were determined. The converting quality was highest (~68) with the 58% copper matte at 1100°C. At similar conditions, the 72% copper matte was more likely to produce copper oxides and leave unoxidized particles rather than directly produce sulfur dioxide at 1100°C, resulting in an average converting quality of 55. The quality of conversion was poorest for the 72% matte at 920°C (~45); the sulfur removal was extremely low even with a relatively high degree of oxidation. Fragmentation of the particles was significant in all cases with the 72% matte. A higher O2/matte .ratio and higher temperature, in general, resulted in increased fragmentation while oxygen enrichment had no significant effect. With the 58% matte, particle size was found to increase for the finest fractions rather than to decrease due to particle expansion.

Jan 1, 1998

By Mingchun Lu, Zhe Wang, Mingming Cao, Xiangdong Xing, Shan Ren, Jianliang Zhang, Zhengjian Liu

"The effect of reduction temperature on the vanadium titano-magnetite carbon composite pellets was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the discussion has put emphasis upon the enhanced reduction mechanism of additives containing CaF2 and NaF in this paper. The results showed that the reduction temperature of 1350°C was needed for the generation, mergence and growing up of metallic iron as well as monomer dissociation between metallic iron particles and slag phase in the vanadium titano-magnetite metallization pellets. The iron compound was completely reduced into metal iron, and Fe2Ti04 was mainly transformed into metal iron, (Fe,Mg)Ti205 and FeTi03 at 1350°C. The maximum metallization ratio was only 88.5% at 13500 for 30 min without any additive. However, with the addition of 3.0% CaF2 or NaF, the metallization degree of pellets could reach up to 94.8% and 92.5%, respectively.IntroductionVanadium titano-magnetite which is mainly distributed in the area of Panxi, Chengde and Maanshan in China is a kind of complex iron ore which contains various valuable metal elements such as iron, vanadium, titanium, etc. Among the above areas, Panzhihua (Sichuan Province in China) area possesses the largest deposits of vanadium titano-magnetite and the future reserves are more than 100x108t, and the reserves of Ti existing as Ti02 reach to 8.7x108t which occupy over 91% of the whole nation and ranked No.1 in the world[1]. Lots of researches on the comprehensive utilization of vanadium titano-magnetite have been conducted in the world. And many technological processes have been applied successfully in industrial production. Among these processes, the process of rotary kiln-electric furnace is employed to recover iron and vanadium in South-Africa, while the process of blast furnace-rotary furnace is widely used in Russia and China. Besides, many researchers have made efforts on employing new direct reduction process to realize the effective comprehensive utilization of vanadium titano-magnetite[2-4]. However, the direct reduction process is only researched in laboratory and it has not been used in industry."

Jan 1, 2013

By B. Wasmund, K. Adham, K. O'Keefe, C. Lee

"Metal chlorides (e.g. iron and nickel) can be pyrohydrolysed at elevated temperatures to yield an HCl rich off-gas and a metal oxide product. Typically, the high energy requirement for pyrohydrolysis is provided by the combustion of a hydrocarbon fuel with air. Here, it is demonstrated that the use of oxygen-enriched combustion can result in lower fuel requirements and higher HCl concentrations. In addition, the oxygen enrichment can result in a smaller volume of off-gas and thus, smaller and less expensive process equipment. This new concept can be applied to both the spray roaster (SR) and the fluidized bed reactor (FBR). Similar to the aircombustion case, the oxygen-enriched process can use a direct contact venturi scrubber, to recover energy from the roaster off gas, but at a higher efficiency. The new process also uses an absorption tower for capturing HCl from the roaster off-gas, but generates a stronger HCl solution than is possible with pyrohydrolysis in air.BackgroundIn recent years, the metallurgical industry has become increasingly involved with developing methods for extracting metals, upgrading products or cleaning metallic products by using hydrochloric acid. These applications of chloride metallurgy often result in metal chloride solutions, which should be processed to regenerate HCl for reuse, and to recover the metal value as a product or by-product oxide [2, 3, 4].The pyrohydrolysis of metal chloride solutions has been done in two types of air roasters: spray and fluidized bed. The existing roasters burn a hydrocarbon fuel in air, to provide the required energy for evaporating the feed solution and to provide an elevated temperature for the chloride pyrohydrolysis to occur, according to the following reactions:"

Jan 1, 2011

By Gopalakrishna M. Rao

"Several industrial and government laboratories are of the opinion that solar--cell technology will grow into a billion-dollar industry by the year 2000, especially if oil prices rise again. Of the variety of materials that have been investigated as the major component of photovoltaic systems, silicon appears to have an outstanding advantage. The cost factor is the primary importance in photovoltaic development, since the technology to make silicon cells of acceptable efficiency and life time has existed since the early stage of the space program. Electrometallurgy is one of the low--cost processes for the production of silicon, since it allows direct, single-stage production from some abundant, inexpensive source materials such as silica and fluorosilicates. Among several systems, two are given particular attention, using inorganic baths with Si0 2 or K2SiF6 as the source of silicon respectively. They appear capable of development to commercial production. Conceptual designs of a commercial--scale cell for silicon production at temperatures above its melting point, and of a pilot' plant for plating silicon from an all-fluoride bath are presented. Energy ProspectsThe major changes in the world energy since the first energy crisis in 1970 have impacted on our community. When oil was $40 a barrel in the mid-1970s, we became obsessed with the energy conservation and a search for alternate energies. Even though the crude oil fell below $15 a barrel during the last several years, our energy security fears continue to haunt us. This time it is not the scarcity, but the abundance of foreign oil and the decline in the domestic production.The prospects of energy depends on the demand and supply of energy. These, in turn, depend on future energy prices, which are linked to economic factors, political events, and unforeseen circumstances. Although no one can predict the future with certainty, three energy consumption patterns used by the Ford Foundation are as shown in Fig. 1."

Jan 1, 1988

By K. Fagerlund

Methods for simulation of settler reactions, matte-slag separation and matte settling in copper flash smelting have been examined. The reaction, separation and settling phenomena of slightly oxidized chalcopyrite samples and cuprous sulfide-magnetite mixtures in fayalite type slags were examined at about 1300°C under inert atmosphere. Two methods based on introduction of molten samples of oxidized chalcopyrite concentrates or synthetic matte-magnetite mixtures onto the surface of molten iron silicate slag were tested. In the first method the samples were water quenched and polished specimens were studied and analysed using light optical microscope, scanning electron microscope, energy dispersive spectrometer. In the second method processes taking place after the introduction of samples onto the slag are followed "in situ" using X-ray transmission image monitoring. Great differences were observed in separation and settling behaviour of low and high grade copper mattes produced as a results of interaction of initial samples and slag.

Jan 1, 1997

By Du Sichen, S. Seetharaman, A. Jakobsson

"In the Present paper, the principles of oxygen potential measurements have been discussed along with the design details for oxygen sensors that are used in copper industry. A description of some of commercial probes is presented along with their salient features. The application of these sensors in flash smelting, converter and casting sections of copper production are discussed along with their implications on process optimization.I. IntroductionThe high temperature galvanic cells have come into prominence on account of their numerous applications in both fundamental as well as applied measurements. Since the inception of the oxygen-ion conducting electrolytes like ZrOrCaO·by Kiukkola and Wagner [1], the oxygen concentration cells have been extensively used in laboratories as well as in industries. In metal-production technology, these cells have been used to monitor the oxygen potentials in metallic, slag as well as gas phases and also to control and styr metallurgical processes. The pioneer among the various industrial users of such cells is the copper industry. To-day, high temperature solid electrolyte cells involving oxygen ion conducting electrolytes have become an integral part of copper pyro-refining and continuous casting. In the present paper some of the applications according to the industrial processes are described including the developments that are going on in the European scene."

Jan 1, 1997

By Barry Welch, Kai Grjotheim

"The capital intensive nature of the present process for aluminium smelting, the low productivity per unit reactor, and pressure to reduce the electdcal energy demand have motivated the search for an alternative process. Optional routes include carbo-thennal reduction of alumina (using an alloy phase immediate), chlorination followed by electrolysis of aluminium chloride, and electrolytic decomposition of alumina using inert electrodes. Materials performance and reactor design constraints have been a major limitation for alternatives. However parallel research has led to considerable advances in the process efficiencies and scale of both the Bayer process and the Hall-Heroult cells.Future development of alternatives is dependent on breakthroughs in Materials Science such as the development of stable conducting anodes and stable wettable cathode materials. However if successful it is probable that some spin-offs will be retrofitted to existing cells. Therefore the basic Hall-Heroult technology will continue as the dominant process for at least the next half century.IntroductionThe present Bayer/Hall-Heroult process for production of aluminium is just over 100 years old. Frequently, during the century of its technological development questions have been raised as to whether it is the ideal route for metal production. The questioning was particularly intense in the period between the mid-1950s and the mid-1060s when the limitations of the Hall-Heroult electrolytic stage were evident. Then the cells were only 30 to 35 % efficient with respect to the utilisation of the hydro-electricity (requiring 16 18 kWh/kg, thus making it strongly dependent on cheap electrical energy), while the size of cells being installed were 80 to 130 kA. Hence the process was capital intensive, the productivity per reactor volume low, and the process was labour intensive (requiring about 15 man hours per tonne of aluminium). In addition, the use of pitches for Soderberg anodes and the fluoride electrolyte were creating problems through emission. At that time material science had paid little attention to the manufacture and use of carbonaceous materials or the development of alternatives that were corrosion resistant to cryolite or liquid aluminium. Hence cell lives were short - typically 600 to 1000 days - thus adding to operating costs. Thus the grass over the fence, as foreseen in 1960s vintage crystal balls appeared much greener for alternative processes."

Jan 1, 1988

By Sheng-li Wu, Guo-liang Zhang, Bo Su

One of the major challenges for the Canadian Gen IV Super-Critical Water-cooled Reactor (SCWR) concept is the selection of fuel cladding materials. The Canadian SCWR concept will operate at a core outlet temperature of 625 oC and 25 MPa of pressure with peak cladding temperature reaching as high as 800 oC. Corrosion resistance is an important factor for material selection. Austenitic stainless steels that contain Cr contents greater than 18 wt.% are generally considered to provide adequate corrosion resistance. In this work, the pressure dependence of the corrosion of austenitic stainless steel 310 containing 24 wt% Cr is assessed at 625 C for exposures of 1000 hours to evaluate the suitability of superheated steam as a surrogate for supercritical water at 25 MPa. Transmission Electron Microscopy (TEM) revealed that 310 exposed to different pressure conditions at 625 oC. (i.e., 0.1, 8 and 29 MPa) had generally the same type of the oxide structure, i.e., a Cr-rich oxide with the spinel structure on outer surface adjacent to the water phase. The material exposed at 8 and 29 MPa had a double layer oxide structure, with the outer oxide layer having a much larger grain size, while the samples exposed at 0.1 MPa showed only a single spinel-phase oxide layer. Cr-depleted recrystallized austenite grains were found underneath the spinel phase oxide. The adjacent large-grained austenite substrate had M23C6 carbides in the grain interior. The implications of these results are discussed.

Jan 1, 2015

By H. Y. Sohn

The ignition and combustion of chalcopyrite particles under suspension-smelting conditions, in which the particle-particle interaction is neglected, has been analyzed by considering the intrinsic kinetics of oxidation and heat and mass transfer between the particle and its surroundings. Reasonable agreement has been obtained between the calculated results and experimental results from a laminar-flow furnace reported in the literature. This computation- al procedure has further been applied to flash-smelting conditions. Under suspension-smelting conditions (Sh = Nu = 2), chalcopyrite particles ignite at around 960 K. The effects of various parameters, such as oxygen concentration, particle size, and gas temperature, have also been evaluated. Comparison between calculated results in this work and experimental observations indicates that SO is the important gaseous product that forms at the surface of the particle.

Jan 1, 1993

By A. K. Kyllo

A study has been carried out on the dusts from Hudson Bay Mining and Smelting's Flin Flon copper smelter. The aim of the work was to determine the mechanisms of dust formation and the deportment of the various constituents. The work concentrated on the copper converters, but the electrostatic precipitators and baghouse also clean the reverberatory furnace off gas, so some mixing will have occurred. The dust composition was found to vary with distance from the furnace, and to be made up of three major components: solidified droplets, unreacted flux, and condensed particles. The solidified droplets were formed from material ejected from the converter during blowing, while the flux was blown out of the converters immediately after charging. The condensed particles contained the majority of the lead and zinc, as well as the volatile impurities. There was also a significant soluble content of the dusts, increasing with distance from the furnace. The condensed material may be separated from the remainder by a simple washing and sizing technique.

Jan 1, 1996

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from theUniversity of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

By Eiji Iwamura

"Two types of diamond-like carbon (DLC) films with different microstructures were prepared by unbalanced magnetron sputtering, and the tribological properties of the nanoscaled DLC multilayer coatings consisting of alternating layers of graphitelike and amorphous-like microstructures were examined. The DLC microstructure was characterized by certain features of graphite-like clusters, in that some of them had onion-like structures. The films filled with the clusters were obtained in a condition with an incidence of high influx of energetic electrons, and the other films without apparent cluster structures were formed in a condition with ion bombardment controlled by negative bias voltage applied to substrates. Stacking each film layer-by-layer, the nanoscaled multilayered coatings showed superior tribological properties to individual single-layered films due to the combination of properties induced by the difference of microstructures.IntroductionIn various tribologiql applications, it is necessary for diamond like carbon (DLC) coatings to have adequate adhesion, significant hardness and a concomitant low friction coefficient. A number of deposition techniques and coating structures have been proposed to achieve suitable DLC properties [1-3]. However it is still difficult to obtain a satisfactory level of combination of the properties particularly desirable for engineering applications.In this study, the features of unbalanced magnetron sputtering were demonstrated with the effect of ion and electron bombardment. Two types of microstructures , namely amorphous-like and graphite-like, were prepared by changing the condition of the charged particles bombardment during deposition. Using the difference of properties induced by the microstructures, nanoscaled DLC multilayered structures were examined in an attempt to improve tribological properties."

Jan 1, 2000

By Tiejun Chun, Jian Pan, Deqing Zhu, Zhiyong Ruan

"In this paper, the desulfuration of pyrite cinder pellets was carried out. Phase analysis shows that most sulfur of pyrite cinder exists in the form of elementary sulfur. Most sulfur was removed in preheating stage. 81.25% sulfur was removed and the average SO2 concentration of exhaust gas was 1365ppm when the pellets were preheated at 950oC for 9 min. The final product, assaying 62.42wt%Fe and 0.02wt%S content at 96.88% desulfuration was achieved under the conditions of preheating at 950? for 9 min and roasting at 1200? for 15 min, which can be used as the burden for blast furnace.IntroductionPyrite cinder, as a subsidiary product of sulfuric acid production by roasting of pyrite ores, was solid waste in sulfuric acid enterprises. According to the statistics, the annual production of pyrite cinder is about 15 million tons in China. Besides, there is lots of pyrite cinder deposited for many years [1-3]. The pyrite cinder consumed in the cement and other industries as auxiliary additives only accounts for less 30% of its total discharge and the left is stored in waste pond, occupying much land and polluting environment in China [4-5]. Moreover, pyrite cinder contains iron between 30-63% which can be utilized as a cheap raw material for ironmaking by sintering or pelletizing processes, which can not only prevent pollution but also provide cheap raw materials for ironmaking [6-7]. However, compared to traditional iron ore concentrate, pyrite cinder possesses higher sulfur content."

Jan 1, 2012

By T. L. Baum

External oxidation during in-line heat treatment of TRIP steels can cause problems for the subsequent coating process. This research aims to elucidate the kinetic rates of internal oxidation, external oxidation and decarburization and their interdependence under different gas atmospheres and temperatures. A rolled steel sample chemistry of 0.14 wt.% C, 1.8 wt% Mn, 0.6 wt.% Si and 1 wt.% Al is used as a case study. Thermogravimetric techniques are used to examine the net mass change in a sample during heat treatment and the results show an initial mass decrease and later an increase for particular partial pressures of H2O. SEM-EDS, optical microscopy and glancing-angle x-ray are used to quantify the microstructure. The cross-section of the samples have 4 distinct zones: (i) an external scale, rich in fayalite, (ii) an internally oxidized region with Al, Si and Mn oxides in an Fe matrix, (iii) a decarburized steel region, characterized by large ferrite grains and low carbon content, and (iv) a relatively unaffected steel core with a structure similar to the starting material.

Jan 1, 2006