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By Kalathur S. Narasimhan

Powder metallurgy is a net shape process competing favorably with machining, stamping, forging and castings. The growth of ferrous powder metallurgy over the past four decades reflect the advancements in materials technology, compaction technology, sintering technologies and other related fields. This presentation gives a brief background on how materials technology evolved.

Jan 1, 2006

By Yoshifumi Abe, Akinori Toraiwa

"Nippon Mining & Metals started a new copper anode slime treatment plant that processes slimes in a chloride media. The basic plan of the process was proposed by Mr. James E. Hoffmann and Nippon Mining & Metals modified and advanced to produce precious metals in acceptable qualities for the company. The process has a wet chlorination stage of decopperized slimes, a solvent extraction and a reduction stages of gold, a silver chloride reduction stage and separative reduction stage of its gold extraction raffinate. The new plant of this process started in 1997 and has been operated in good condition.IntroductionThe old anode slime treatment plant of Nippon Mining & Metals, located in it's Hitachi Refinery, processed anode slimes through a combination of pyrometarllurgical processing and electrorefining. There was a need to plan a future of the plant because the maintenance cost increased year by year and a new selenium registration was going to be applied to the plant. Some plans were discussed and the result was that the process proposed by Mr. Hoffmann was superior among them.Nippon Mining & Metals started 'to examine the process and the experimental result showed that the process had an ability to be its new process but further research should be necessary to produce precious metals in acceptable qualities. The final process flow has some modified and additional stages to be suitable for its requirement. Silver processing stage is quite changed. Gold extraction stage has a new step to polish gold loading DBC. Gold extraction raffinate treatment stage is advanced to be able to recover precious metals, selenium and tellurium, separately. Aeration under atmospheric pressure is employed in decopperizing stage.The basic design of the new plant started in 1995 and finished in 1997. The construction of the new plant began in April 1997 and finished in October. The plant has been operating well after the four months test operation."

Jan 1, 2000

By K. Iwami, K. Abe

"Onahama Smelter and Refinery has been operated-since 1965 arid currently produces 243,000 metric tons per year of cathode copper. The Onahama tankhouse consists of conventional-type No.1 and 2 tankhouses with the capacity of 123,000 metric tons per year and No.3 tankhouse with 120,000 metric tons per year, adopting jumbo tank system, using hazelett anode respectively.In October, 1996, for the purpose of improving the - anode verticality, new anode copper body press machine has been installed in No.1, 2 tankhouses; by increasing Walker type anode copper weight by 35kg to 365kg. Consequently, it is possible to raise current density from 191 to 222 A/m2 and the No.1 and 2 tankhouses capacity was increased by 15,000 metric tons per year to 138,000 metric tons per year.At present, the refining capacity is 258,000 metric tons per year in total including No.3 tankhouse.This figure is the largest one in Japan.IntroductionSince the Onaham tankhouse was put into operation in 1965, the cathode copper production has increase with much labor cost saving.The following two cases to increase Walker type anode copper weight by 35kg to 365kg were studied.a) To increase the cathode copper production by raising current density.b) To save the labor cost by prolonging the anode cycle in order to decrease the exchanging time of electrodes.So the electrolytic tests were carried out to confirm· the effect of current efficiency, cathode copper quality and working conditions for space adjustment.As a result, we concluded that it was indispensable to introduce the anode body press machine to keep usual current efficiency and cathode copper quality with same workers, and to be possible to increase cathode copper production.In addition, the high-speed press machine was needed to maintain same working time and which specifications were decided through various investigations. In October 1996, the new anode body press machine made by Kawazoe Machine Works, Ltd. has been installed in No.1 tankhouse."

Jan 1, 2000

By Wilky Desrosin, Alicia E. Ares, Carlos E. Schvezov

"In the present research the horizontal directional solidification Zn-Sn alloys (Zn-4wt. %Sn, Zn- 6wt. %Sn, Zn-10wt.%Sn and Zn-30wt.%Sn) was carried out by extracting heat in two opposite directions. For this purpose, ceramic molds, a muffie, a horizontal furnace with two heat extraction systems at the ends, a measurement, acquisition and recording temperature system, eight K-type thermocouples and an electronic recorder were used. The main parameters involved in the columnar-to-equiaxed transition, CET, were: the moment of start and end of solidification at each position under consideration, cooling rates, the average temperature gradients and critical temperature gradients at the CET, the average speed of liquid and solid interphases left and right, advancing in opposite directions. Also, solidification kinetics was found to be different between horizontal solidification two-way heat extractions, with preliminary results of the vertical unidirectional solidification. In the solidification experiments, the velocity and accelerations of the liquidus and solidus interphases usually occurs at the end solidification zone of the samples.IntroductionSolidification of metal alloys, which starts in the external equiaxed region (chill), results in two basic types of structures in a single solidified alloy sample: columnar and equiaxed. The presence of both structures indicates the occurrence of the colunmar-to-equiaxed transition phenomenon[!].Studying the colunmar-to-equiaxed transition, CET, is of great technological interest for the evaluation and design of the mechanical properties of the solidification products. To this end it is necessary to understand the mechanisms by which it occurs. As found in previous studies [2-5], the CET occurs by competition between columnar and equiaxed growth. Mainly is controlled by the parameters of casting, such as the alloy composition, the density of the present nuclei in the liquid, the cooling capacity of the metal I mold, and the degree of convection in the liquid [7-10]."

Jan 1, 2014

By V. M. Paretsky

Oxygen-flame converting of a solid ground matte containing heavy non-ferrous metals in a wide range of concentrations is one of the perspective trends meeting the demands of modern non-ferrous metallurgy. As. a result, of semicommercial tests on oxygen-flame smelting of nickel matte containing 13,5-17,5% Ni; 0,45-0,65% Co under continuous autogenous conditions a converter matte containing 68 8-75,0% Ni and 0,48-1-,0% Co and ferrite -calcium slag containing 1,4-8,4 Ni and 0,16-0,56 Co were pro¬duced. Nickel recovery in a converter-matte was 76,2%, copper - 58,'2% and cobalt recovery in. a slag was 90%. Slag cleaning in an electric furnace allowed to after-recover nickel and cobalt in an alloy to produce a dumpy slag containing 0,03% Ni and 0,02% Co. The development of modern' ecologically pure energy-saving autogenous technologies of the treatment of sulphide raw materials containing heavy non-ferrous metals makes certain demands of the perfection of a process of converting rich sulphide-metallic intermediate products obtained at autogenous smelting. These-demands were connected first of all with the fact that converting process stages because of process periodicity are more unfavourable from the point of ecology, power intensity and unit stability. Besides, during rich matte treatment the problems connected with heat shortage when using air blast and heat excess-when using top oxygen blast to treat luquid matte a-rise and when enriching air blast by oxygen up to 26% fast erosion of the brickwork of a tuyere zone takes place. The technology of Outokumpu and Kennecott companies-on solid- copper matte converting in a flash smelting furnace using air blast is not universal as its possibilities are limited by certain composition of mattes. Besides, flash smelting to produce highly basic or combined slags requires larger enrichment-of blast by oxygen or extra fuel feed. Naturally a flowsheet with continuous converting of matte of various composition up to white matte production is simple,

Jan 1, 1993

By Xavier Kleber, Aude Lamontagne, Veronique Massardier, Daniele Mari

"The thermoelectric power (TEP) technique was used to determine with high accuracy the strain ageing kinetics in heavily cold drawn pearlitic steel. Because of the very high sensitivity of the TEP to solute atoms, this technique allowed the strain ageing to be followed from the very first moments. The kinetics were followed during isothermal ageings performed between 20°C and 200°C for different strains. In order to avoid any ageing at room temperature, the samples were kept at -80°C immediately after cold drawing. TEP evolution versus strain highlights cementite decomposition occurring during cold drawing. During the ageing, a redistribution of the dissolved carbon atoms in ferrite occurred. The TEP increase with the ageing time was attributed to the departure of carbon atoms from ferrite (segregation to dislocations and/or carbide precipitation). The kinetics were analysed using the Johnson-Mehl-Avrami-Kolmogorov approach which enabled to determine activation energies associated with carbon atoms redistribution.IntroductionHeavily cold drawn pearlitic steel wires are commonly used as structural materials for their high strength and their acceptable ductility. However, several previous studies highlight the microstructural destabilization of pearlite mainly due to cementite decomposition during the drawing process, which induces changes of mechanical properties [1, 2]. This phenomenon was detected by several experimental techniques such as Mossbauer spectroscopy [3, 4, 5], themomagnetic analyses [6, 7], TEM [8, 9, 10] or atom probe tomography [9, 10, 11]. Nevertheless, the mechanism of cementite decomposition is still unclear. Several hypotheses were proposed in the literature. The first hypothesis relies on a strong interaction energy between carbon atoms and dislocations involving higher binding energy than that between carbon atoms and iron atoms in cementite [3]. The second hypothesis is the increase of the free energy of the interface between cementite and ferrite due to the fragmentation of cementite during deformation (Gibbs-Thomson effect) [8]. Some authors even suggest that the dissolution of cementite occur during a post-deformation ageing [12, 13]. It is worth"

Jan 1, 2013

By Monteirom Sergio N., Romulo L. Loiola, Giulio R. Altoe, Noan Simonassi, Frederico M. Margem

"The environmental concern is creating pressure for the substitution of high energy consumption materials for natural and sustainable ones. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as flexibility and toughness. So there is a growing worldwide interest in the use of these fibers. Buriti fiber extracted from buriti palm tree (Mauritia flexuosa), presents some significant characteristic, but until now only few studies on buriti fiber were performed. This work aims to make the analysis of the tensile strength of epoxy composites reinforced with buriti fibers. This analysis was performed in fibers with diameters between 0.1 and 0.4 mm. Those fibers were incorporated into the epoxy matrix with volume fraction from 0 to 30%. The fiber diameters were measured by a profile projector. After fracture the specimens were analyzed by a SEM (scanning electron microscope).IntroductionNatural fibers with high amount of cellulose, also known as lignocellulosic fibers, have been used from primeval times of our civilization. In the last century, synthetic fibers such as nylon, carbon, aramid and glass fibers gained interest owing to superior strength and precise dimensional control. Natural fibers were then replaced by synthetics in many fields such as textiles, sports goods and appliances. In the past decades, however, environmental issues drawn, once again, the attention to lignocellulosic fibers as possible substitute for intensive energy-consuming and long term polluting synthetics, specially the glass fiber(1). In particular, research works have disclosed the potential advantages associated with the use of lignocellulosic fibers as the reinforcing phase in polymer composites(2-3). Among the advantages it is worth mentioning the renewability, recyclability, biodegradability and the fact that natural fibers are neutral with respect to CO2 emissions responsible for global warming. In addition to environmental benefits(l,10) the lignocellulosic fibers present economical advantages, such as worldwide abundance and comparatively low costs as well as some technical properties associated with flexibility and toughness( 4), which contribute to the performance of automobile components fabricated with natural fibers composites(l 1-13)."

Jan 1, 2013

By Anestis Vlyssides, Elli Maria Barampouti, Sofia Mai, ?postolos Vlyssides

"A new anaerobic reactor variation, the UASB/CO2-stripper reactor was conceived. It consisted of a conventional UASB reactor that recirculated the biogas produced. The sludge characteristics of this system were examined when treating high strength wastewater. From the data collected, it was obvious that the UASB/CO2-stripper system can satisfactorily operate at higher loading rates (25 g COD·L-1·d-1). A pronounced effect on the quality of the granular sludge was observed. The VSS/TSS ratio decreased sharply. A considerable decrease in the mean granule diameter was observed, while the specific gravity of the granules increased. The sludge bed porosity increased significantly leading to a considerable expansion of the sludge bed. These changes in the sludge properties led to a gradual shift of the system towards a fluidized bed process as far as its hydraulic characteristics were concerned.IntroductionIn recent years energy considerations and environmental concerns have increased the interest in direct anaerobic treatment of industrial wastes. The anaerobic method of waste treatment offers, under the present circumstances, a number of significant advantages with trivial or more serious drawbacks over other treatment methods. The major obstacle to the application of the process for this specific purpose is perhaps the difficulty of extending it to a stable and simple operational form. A number of reactor configurations has been developed leading to high biomass concentrations, e.g. the contact process, the filter reactor, the UASB reactor, and the fluidized bed systems, but the process stability problem still remains [1].A prime objective in the operation of anaerobic waste treatment process is the maintenance of a proper pH range. Thus, a possible solution to the process stability problem could be obtained by increasing alkalinity in the anaerobic systems. Therefore, the main objective of this paper is to present and evaluate the results of a system (UASB/ CO2-stripper) with increased alkalinity concentrations."

Jan 1, 2008

By Alain Jardy, Valerio De Felice, Jean-Pierre Bellot, Ismael Lis Alves Daoud, Stephane Hans

"Gas-stirring ladle treatment of liquid metal has been pointed out for a long time as the processing stage mainly responsible for the inclusion population of specialty steels. A steel ladle is a complex three-phase reactor, where strongly dispersed inclusions are transported by the turbulent liquid metal / bubbles flow. We have coupled a population balance model with CFD in order to simulate the mechanisms of transport, aggregation, flotation and surface entrapment of inclusions. The simulation results, when applied to an industrial gas-stirring ladle operation, show the efficiency of this modelling approach and allow us to compare the respective roles of these mechanisms on the inclusion removal rate.IntroductionThe reduction of the weight of high performance materials together with the improvement of mechanical properties and the increase of the recycling of used metal are new challenges which emphasize the importance of metal cleanliness. Ladle treatment of specialty steels has long been described as the secondary metallurgical process mainly responsible for the non-metallic inclusion derived from the deoxidation process. The treatment is accomplished by blowing argon through one or more porous plugs for the purposes of desulphurization, minor composition adjustments, and inclusion removal. Gas injection is applied on routine basis to achieve both the stirring of the liquid bath (thermal and chemical homogenization) and the entrapment of the inclusions by the bubbles (flotation). Furthermore, the turbulence produced in bubble swarms enhances the probability of inclusion collisions and makes aggregation the first mechanism for particle removal. The physical processes involved in gas stirred ladles are numerous and complex owing to the three dimensional and multiphase (metal-gas and inclusions) nature of the reactor. Despite these difficulties, the population balance equations can be implemented in CFD code11'21 and combined CFD-PBM (computational fluid dynamics - population balance method) models are investigated for steel ladle processes13'41 and produce very promising results in terms of inclusion removal efficiency."

Jan 1, 2012

By Farouk Tedjar

The growth of miniaturization in one hand and energy density need lead to rapid development of new chemistry for batteries as observed during last decade particularly in secondary systems. However dark side of the progress is always in environment impact and scarcity of resources. In the lithium segment a jump from six electrochemical series (all non rechargeable systems) before 1990 to more than 15 systems including new rechargeable systems has been observe during last decade. Lithium battery chemistry was enriched with new electrolytes, conductive salts and new oxide composition. In the same time, lithium ion battery safety was strongly improved during last period. The progress of these technologies was strongly boosted by the substantial growth of the mobile telephone market in the mid 1990's (+ 1% a month in 2000, and a 71% penetration rate in Europe in 2005 compared to just a few percent in 1996). This market is constantly in search of higher electrochemical performance (mainly energy density in front of increasing miniaturization. Recycling of end of life product could be managed not only in environment aspect, but also under resource conservation and economic aspect of arising technology (mainly on the effect of re-injection recovered materials) The Li-ion segment is a new branch in the cobalt market and impact of LiCoOx will be fitted with the actual increase of the demand for this battery. For this reason all the processes aim to valorize active and packaging material. RECUPYL process project was conducted in this direction to offer a new solution for recycling those lithium systems. The process has been developed at pilot industrial scales using synergy between new equipment (for mechanical pre-treatment step) and existing line at RECUPYL facility (for chemical treatment) and should lead to high valorization rate with a minimum hazardous co-products. The process was also developed in order to be able to recover news cathode materials introduced in electrode like LiFEPO4, LiMxCoyO2 and new anode composition in substitution with former carbon anode.

Jan 1, 2006

By Guillermo Rios, Arbizum Cristina, Joa Viflals, Alba Sunyer

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities are located in Huelva (Spain) and account for the smelting of over one million tpy of concentrates to produce up to 260 ktpy cathodes and 900 ktpy of sulphuric acid. During copper concentrate smelting, the slag coming from the flash furnace and PS converters are treated in an electrical slag cleaning furnace. As a result of the treatment of the off gases from this furnace, approximately 2,000 tpy of a Zn-rich filter cake are produced and are sent to authorized waste managers. This paper describes the characterization of this material and the preliminary results of a new process to recover zinc as a pure zinc hydroxycarbonate while lead is collected as an indium-rich anglesite product. The behavior of impurities (Cd, As, Tl, Sn, Sb, Bi, Cu, Se, Te) in the leaching, solution purification and precipitation steps is also reported.IntroductionThe Atlantic Copper Metallurgical Complex in Huelva (Spain) was commissioned in 1970 with a capacity of 40,000 tpy of copper from concentrate. In 1975, the old blast furnaces were replaced by Outokumpu flash smelting furnace (FSF) technology, and the copper refinery capacity was increased to 108,000 tpy. Between 1994 and 1996, an expansion project was carried out to increase the copper from concentrate and cathodes to 250,000 tpy and 215,000 tpy, respectively. This expansion basically consisted of a new sulphuric acid plant, replacement of the anode furnaces by two 400 t units, redesign of the slag cleaning furnace (SCF), an increase in the electrolytic cells to 1,120 and implementation of ISA permanent cathode technology. Furthermore, a debottlenecking project has led to a capacity of 1,000,000 tpy of fresh concentrate since 1997. Meanwhile between 1995 and 1998, a cathode production rate of 260,000 tpy was reached as a result of a progressive increase in the current density in the refinery."

Jan 1, 2012

By Peter J. Koros

The current wave of interest in this topic is the result of increased use of titaniferous ores or ilmenite in blast furnace burdens for the purpose of repairing hearth damage. The titanium compounds that promote deposition of ?patching? materials in blast furnaces are the cause of downstream problems in the steelmaking shops. Steelmakers historically have objected to significant amounts of titanium in hot metal (>0.10 % Ti) for several reasons: 1) accretions caused by the TiC.TiN needles that float out of the iron as it cools in transit and in transfers make the accompanying slag sticky and crusty, causing problems in desulfurization and increasing time and Fe yield loss at the subsequent raking, 2) defensive measures have been taken in treatment, such as use of argon for carrier gas, but without technical rationale for this approach, 3) difficulty in removal of the ladle slag by the raker, with subsequent sulfur addition to the vessel charge, and 4) transfer into the BOF and/or formation of a very corrosive TiO2 containing acid slag during the early part of the BOF blow which, in addition to causing lining damage, results in loss of sulfur removal capability by the vessel slag. Based on a conceptual analysis of the metal-slag-atmosphere interactions during transfer ladle desulfurization treatment, a mechanism is postulated for the apparent effectiveness of the use of argon in reducing the deleterious effect of titanium and an alternate technique, possibly more effective, is proposed. As probably the use of argon causes increased exposure to atmospheric oxidation of the titanium carbonitrides contained in the ladle slag, the same benefit can be obtained by use of either oxygen or an air blast to oxidize the noxious reaction compounds. Validity of the concept has been demonstrated in a pilot plant setting. These issues, and related effects on testing the hot metal, are examined in detail with reference to the literature and plant and laboratory experience.

Jan 1, 2006

By K. Knuutila

The behaviour of thiourea, animal glue and chloride ions in the electro¬lysis of copper has been investigated by various different electrochemical experiments, i.e. polarization curves with stationary copper electrodes, long-time galvanostatic electrolyses and Hull cell experiments. Polarization curves with stationary copper electrodes show that animal glue has a polarizative effect on the deposition potential. Small thiourea contents affect depolarizatively when high concentrations retard the copper deposition. The microstructures of the deposited copper after the long-time electrolyses show that animal glue favours a basis oriented deposition structure. With thiourea the field orientated structure was evident. It was also observed that the deposited structure depended much on the grain structure of the starter sheet. The chloride ion concentration has a drastic effect on. the crystal size of the deposited copper as it was found out in Hull cell tests. Chloride ions flattened the the crystals and the deposition became smoother when the chloride ions were added. The cathode copper quality is discussed according to the literature. Special attention is paid on the codeposition of thiourea and the origin of sulphur impurities in copper cathodes.

Jan 1, 1987

By Carole Read

Hydrogen is under consideration by several countries for its potential as an energy carrier for transportation applications. In order to compete with vehicles in use today, hydrogen-powered vehicles will require a driving range of greater than 300-miles in order to meet customer needs and expectations. For the overall vehicular light-duty fleet, this dictates that a range of 5 to 13 kg of hydrogen be stored on-board (assuming a fuel cell power plant) within stringent system weight, volume, and cost constraints. Vehicular hydrogen storage thus constitutes a major scientific and technological challenge. To meet this challenge, the U.S. Department of Energy (DOE) initiated a ?National Hydrogen Storage Project? with roughly 40 universities, 15 companies and 10 federal laboratories, actively engaged in hydrogen storage research. Centers of Excellence in metal hydrides, chemical hydrides, and carbon-based materials have been established, as well as independent university and industry projects in the areas of new concepts/materials, hydrogen storage testing, and storage system analysis. Recent technical progress in each of these areas is discussed, as well as collaborative hydrogen storage activities under the recently established International Partnership for the Hydrogen Economy (IPHE).

Jan 1, 2006

By Li Fangi

This paper describes the characteristics and regularities of a process to recover rare earth minerals from Baotou Ore with H-205 collector. H-205 is a kind of hydroxamic acid with amide as a polar group and poly-cycle aromatic hydrocarbon as a non-polar group, having strong ability to capture RE minerals (bastnasite, monazite). When adding a certain dosage of water glass and some other modifying agents, and maintaining pH value between 8.5 and 9.5, RE minerals can be effectively separated from calcium and barium minerals, such as fluorite and barite, etc. Under normal flotation temperature and concentration, when using H-205 to float RE minerals, it needs a bit longer conditioning time (a few minutes longer than that for the conventional collectors). It is also shown that the reagent has the property of resistance to hard water. The laboratory scale and pilot scale tests of the process have been carried out on bulk froth containing RE minerals and fluorite taken from Ore Dressing Plant of Baotou Iron and Steel Company, in both cases, high grade RE concentrates were obtained and the recovery increased remarkably. Therefore, the process has a great practical value.

Jan 1, 1989

By S. Kawamura, H. Inoue, Y. Maeda, H. Ohike

Kosaka smelter is a copper smelter located in Akita Prefecture in the northern part of Japan. It has treated complex sulfide concentrates for a long time. Recently, in addition to metal production from ores, the company has been working on the recycling of metals by using this metallurgical technology. Metals recovered are primarily gold, silver, palladium, copper and lead from copper scraps, electronic board scraps, silver oxide batteries, spent lead acid batteries, semiconductor chips, cellular phones, and automotive emissions catalyst. In particular, electronic board scraps and cellular phones can be valuable raw materials. These electronic scraps are fed into the flash smelting furnace after size reduction in a shredder that was introduced in 1999. Due to the growing demand for personal computers and cellular phones, the amount of electronic board scraps available for recycling increased. At present, these secondary materials are good raw materials for Kosaka smelter since the smelter is already used to dealing with complex raw materials. The recycled metals account for up between 5 and 20 percent of the total production at Kosaka Smelter. In particular, over 90 percent of the palladium in the secondary materials can be recovered.

Jan 1, 2000

By Sergio Neves Monteiro, Nuã Simonassi, Helvio Pessanha Guimarães Santafé Jr.

"Thermoset polymers, like the polyester, become harder with increasing temperature owing to molecular crosslink formation, which is a thermal benefit for composite matrix applications. Natural lignocellulosic fibers, however, have low thermal resistance and tend to degrade with increasing temperature. Therefore, the combination of a lignocellulosic fiber, as reinforcement, with a thermoset polymer, as the matrix, results in a composite material with complex thermal behavior. In the present work, a thermal analysis was conducted on polyester composites with different amounts of coir fibers. Both TGA and DTG curves were analyzed to determine the effect of the coir fiber on the thermal resistance of the composites. It was found that the coir fiber sensibly affects the thermal behavior of the polyester matrix for fiber amounts above 10% in volume. This effect is associated with an increase in thermal degradation.IntroductionIn recent years, there has been an increase application of natural fibers as reinforcement of polymer matrix composites in several industrial sectors, with special participation in automobile components [1-3]. Figure 1 illustrates the different components of a modem BMW sedan that are fabricated with lignocellulosic reinforced polymer composites."

Jan 1, 2012

By R. D. Prengaman

Lead usage in paint, anti-knock gasoline additives, pipes, seals, and solder has declined markedly over the past 30 years. Products utilizing the unique properties of lead and its ability to be recycled have survived and grown. These products include shielding, glass (particularly TV and computer screens), sheet for roofing, stabilizers for PVC, insoluble anodes for metal production, electronic solders and lead acid batteries. With the loss of markets many companies have decreased lead product development efforts. Much of the patent lead materials development is devoted to lead acid batteries. In the past 25 years, the automobile battery has been almost doubled in power and reduced in weight, leading to a nearly three-fold increase in performance. Corrosion-resistant lead alloys and improved battery designs have made battery lead usage more efficient. The same corrosion-resistant battery alloys are utilized to increase the life of electrowinning anodes. The challenge for lead product development is not only to maintain and improve the existing lead products, but also to develop the growing lead acid battery market for telecommunications, uninterruptive power sources, remote area power, hybrid and electric vehicles. Lead

Jan 1, 2000

By A. V. Tarasov

Emission of sulfur-containing gases causes most adverse impact on the natural environment in the process of nonferrous metals production. Under the conditions of Arctic regions, in particular in the region of the Norilsk Mining and Metallurgical Complex (Russia), this problem requires a special approach taking into account potential economic and socioeconomic consequences. By reducing the iron sulfide content of flotation concentrates by using new flotation reagents inhibiting pyrrhotite flotation and by applying advanced process flowsheets for flotation it is possible to increase the nonferrous metals content of flotation concentrates by 5% or more along with a corresponding reduction in SO2 formation during their subsequent pyrometallurgical processing. The ways used to resolve the environmental problems in the Norilsk region in the process of nickel and copper production, are based on the improvement of methods for elemental sulfur recovery from metallurgical off-gas by non-conventional techniques, the sulfur recovery from metallurgical gases by production of liquid sulfur dioxide and the technology for pyrometallurgical treatment of sulfide concentrates without SO2 formation. Another opportunity is the development and commercial introduction of hydrometallurgical technologies for treating copper-nickel sulfide ores.

Jan 1, 2006

By P. G. West-Sells

Recovery of gold from thiosulfate leachates can be accomplished by adsorption of the gold thiosulfate complex by a strong base resin. Two of the most significant impurities that can decrease this gold adsorption are tetrathionate and trithionate, which are produced as oxidation products of thiosulfate during gold leaching. This paper investigates gold adsorption on a strong base resin (Purolite A500C) as a function of the concentration of these impurities. It is shown that concentrations of tetrathionate and trithionate as low as 150 mg/L can decrease gold loading by an order of magnitude, and that of the two ions, tetrathionate has a stronger detrimental effect. The resin and solution gold concentration profiles were successfully fit using a Freundlich isotherm, which further shows the strong effect of tetrathionate. To counteract the decrease in gold adsorption by tetrathionate, a novel process was proposed. Sulfite was added to the solution to oxidize tetrathionate to trithionate, and a nitrogen blanket was added to ensure that no further oxidation of thiosulfate could take place. It is shown that by incorporating this process, gold adsorption was doubled from both synthetic and real gold thiosulfate leachates.

Jan 1, 2003