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By R. C. Chaturvedi, S. B. Padwal

"Padwal and Chaturvedi have developed the model based on M-K theory, considering Hosford's yield criterion and critical thickness strain criterion"" to predict the sheet metal forming limits under simple (constant) strain ratio paths. This analysis has been extended in this paper to predict the sheet metal forming limits under complex strain paths. The effects of exponent ""a"" in Hosford's yield criterion and strain paths on the forming limits under complex strain paths are studied using this analysis. The predictions of the present analysis are compared, both for simple and complex strain paths, with experimental results of Ishigaki for A.K. steel and also with the predictions of Rao and Chaturvedi's model. The quantitative analysis of the error in predicting the forming limits has also been carried out using a method suggested by the authors earlier.1. INTRODUCTIONThe constant strain ratio condition has been assumed in the theories developed for prediction of forming limit diagrams (FLO). In actual forming operation, this condition is seldom satisfied. Even in the case of simple single stage press formed components, the strain path becomes curved and non-linear. In the case of pressings with complex shapes, or multiple stages of forming, the changes in strain path are more pronounced and even abrupt.Experimental study of the forming limits, under two stage strain paths, by Ishigaki [1], has shown that the forming limits are path dependent. It has been observed that the forming limits lower than that under simple strain paths, may be obtained under certain strain paths (when the first stage strain path is either equibiaxial tension or uniaxial tension, followed by the second stage strain path as plane strain). Rasmussen's work [2J, on the theoretical study of forming limits under curvilinear strains paths, has shown that a large drop in formability can result from very small changes in strain path. Thus if a deformation process gives rise to failures due to plastic instability, the failure is not necessarily due to insufficient formability of the material. In such cases, FLOs based on constant strain ratio path should not be used directly in predicting the success or failure of the forming operation. Thus the knowledge of forming limits under complex strain paths is of great importance to the interpretation of press-shop problems."

Jan 1, 1994

By X. J. Wu

Effects of various factors such as diaphragm materials, composition of electrolytes and current density on copper electrowinning from cupric chloride solutions was investigated. It is found that the crux of this process is to prevent the dissolution of copper by cupric ion and the formation of suspended CuCl precipitate. A process with high difference of copper concentrations between the feed solution and the spent electrolyte was selected. With this process, in which the feed solution contains 90 g/dm3 [Cu"], 3M NaC1, and 10mg/dm3 bone glue, and the spent electrolytes contains 10 g/dm3 [Cul, a very smooth and dense copper cathode can be produced with current efficiency above 93% and energy requirement less than 1.7 kwh/kg Cu at 25°C with N2 sparging. If a slightly higher energy requirement is permitted, smooth and dense copper cathodes can be produced at the current density up to 800 A/m2 with the identical solutions.

Jan 1, 1991

By Jian Li

Corrosion resistance of materials is highly dependent on the microstructure of the specific material. Apart from general corrosion rate measurement using techniques like linear polarization and A.C. impedance, microstructural investigations are frequently needed to identify the root cause of corrosion. Advanced techniques, including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have been well integrated into routine characterization studies. Other microscopy techniques, including electron probe micro-analyzer (EPMA), Auger, X-ray photon spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS), can provide detailed chemistry information on corrosion products. In recent years, focused-ion beam (FIB) microscopes have evolved into an important microstructural characterization instrument. In this study, corrosion of rebar encased in concrete was studied in great detail using advanced microscopy techniques. Corrosion product on the rebar surface was identified as ferrous oxide with relatively large crystal size. The morphology of this passive layer was thoroughly analyzed, and its formation mechanism is proposed.

Jan 1, 2009

By Olli Järvinen

The capacity of the Outokumpu Pori refinery is today about 125 000 mt in 1998. The anode slime amount is about 700-800 mt. The copper is removed with pressure leaching. Selenium roasting is done with the gas roasting. The doré smelting in the furnace is done with the tilting rotating converter with oxy-fuel burner (TROP). Doré anodes are treated in the silver electrolysis. Gold is recovered from the gold mud with the quick hydrochloric acid leaching process. The important point in the leaching is to get into contact the solid copper with the oxygen and liquid. Outokumpu has an efficient agitator for this purpose. The GLS-agitator (GLS=gas, liquid and solid) is powerful for mixing oxygen, liquid and solid together. The current production in Pori plant is 40000 kg of silver, 5000 kg gold, 40000 kg of selenium and one hundred kilograms of platinum-palladium concentrate.

Jan 1, 2000

By Robert W. Bartlett

"Economic and other factors, mostly outside of metallurgy, that strongly influence applied research, development and especially successful commercial adoption of new processes for producing primary metals and other commodity materials are reviewed. These factors, which can be both positive and negative in their influence, are often too lightly regarded in the research planning stage. They include continuing imperatives that have long influenced new process development as well as more recent trends. Both are discussed. Nearly all new materials eventually become commodities--products made to standard specifications with no producer control over price. Success requires being a low cost producer on a world wide basis. Composites and other complex material assemblages are unlikely to escape this fate as they mature.INTRODUCTIONThe adoption of new processes, beginning with research and development, for primary metals and other commodity materials is particularly difficult because each new process must supplant an existing process that is already being used commercially. There are many requirements besides technical innovation and cost superiority that must be met by the new process. Consequently, few innovations make it all the way from the research laboratory to commercial success.This paper discusses some of the factors that influence success in developing new processes for primary metals and commodity materials, based on the authors experience as a research metallurgist and industrial research manager. It begins with some of the factors that are always present and constrain successful process research and development, and proceeds to current trends that are expected to continue long enough to influence processes in the year 2000. Many of these trends are contradictory in their effect on new process development, and the future remains uncertain.The prevailing importance of these trends will vary with the material, process concept and other factors intrinsic to each case. Nevertheless, an awareness of these influences can help to avoid some of the R&D pitfalls and dead ends. Such awareness is deemed to be a necessary condition to avoid failure when commercial adoption of a new process is the goal."

Jan 1, 1988

By Kuiting Wang, Jinshan Liu, Ninglei Sun, Aiguo Dong, Yeda Lu

"Eliminating the environmental threat caused by waste effluent containing magnesium sulfate derived from the process of nickel laterite sulfuric acid leaching and subsequent nickel precipitation is always a focus in the metallurgy field. A new flowsheet whose procedures include vaporization, crystallization, two stages precipitation of magnesium, causticizing treatment of filtrate and ammonia recycle was investigated. Both the details of the flowsheet and its application are described in this article. It is confirmed to be an effective and economical method to prevent the pollution by the waste effluent, simultaneity, a series of magnesium products recovered during the process own good economic returns.IntroductionSulfuric acid leaching is the conventional procedure of extraction valuable metals from ores in hydrometallurgy field. During the process of nickel laterite sulfuric acid leaching, several metals, including Ni, Co, Al Mn, Fe, Mg etc., migrate into the leachate in the form of soluble metal sulfate. After subsequent procedure of purification, precipitation of Ni and Co and neutralization, an enormous stream of waste effluent which contains a concentration of approx. 15-40g/L Mg is exhausted. Such solution containing magnesium sulfate is toxic, which causes diarrhea for both human and animals. On the other hand, large amount of sulfate acid was consumed during the process of leaching by the compound of Mg, which increases cost of a hydro nickel plant.In arid areas, the waste effluent mentioned above is treated via evaporate pond owning large acreage, which needs not only the appropriate meteorologic condition, but occupies much land. In coastal areas, it is directly discharged to the sea, which probably deteriorates ecological system of offshore strip. The most widespread method to treat with the waste effluent is neutralization by lime cream, the residues of which containing magnesium hydroxide and gypsum are transported to residues pool. Neutralization is a simple process, but it never recycles the Mg and sulfate anion into new application, meanwhile, the residues are potential threat to the environment."

Jan 1, 2012

By J. Sjöblom

New copper and nickel processes, flash converting and DON, direct high-grade nickel matte smelting, have been developed in order to replace the conventional and not so environmentally friendly PS-converting process. With a laboratory scale laminar-flow furnace the combustion reactions of sulfidic feed particles can be investigated under simulated flash smelting conditions. In the present study, finely ground and screened feed fractions of a copper matte and a nickel matte were flash oxidized in a laminar-flow furnace. The experiments were carried out using 20, 21 vol% and 75 vol% O2 in nitrogen, at temperatures 1100 and 1300 °C and reaction zone length of 7.5-16 cm. The samples were quenched in a water film after a specified reaction time. The matte particle reactions were stopped after short residence time intervals in order to obtain a better understanding of the reaction mechanisms. Chemical analysis was used to determine oxidation degree, and optical and scanning electron microscope combined with energy dispersive analysis was used for characterization of the reacted particles. On the basis of the experimental results the reactivity of the mattes is discussed and possible reaction and dust formation mechanisms are considered.

Jan 1, 1999

By Jiao Li, WenhuiMa, KuixianWei, YongnianDai, Cong Zhang

The paper studied the diffusion process of nitrogen and characteristic distribution of iron impurities in the bottom of cast crystalline silicon ingot along the direction of crystal growth. According to the dynamics analysis of the decomposition of Si3N4 coating, the diffusion process of nitrogen into multicrystalline silicon ingot during casting process should be divided into three steps. The diffusion length of nitrogen in multicrystalline silicon ingot is 700 μm. The results of EDS analysis indicate that the distribution characteristic of iron in multicrystalline silicon ingot is concerned with the diffusion process of nitrogen in this length. Based on the above research results, the distribution model of iron in casting multicrystalline silicon ingot was established and verified by the experimental results.

Jan 1, 2015

By I. Iwasaki

Flotation characteristics of pyrrhotite by itself and in complex sulfide ores are reviewed with respect to the effects of oxidation, grinding media and other electroactive minerals.

Jan 1, 1988

By Katsunori Okaya, Gjergj Dodbiba, Hiroyuki Ono, Toyohisa Fujita, Seiji Matsuo

"In an attempt to raise the copper grade of Printed Circuit board (PCB) by removing other components, carbonization treatment was investigated. The crushed PCB without surface-mounted parts was carbonized under nitrogen atmosphere. After screening, the char was classified by size into oversized pieces, undersized pieces and powder. The copper foil and glass fiber pieces were liberated and collected in undersized fraction. The liberation of copper foil from the oversized pieces was also investigated. The copper foil was liberated easily from glass fiber by stamping treatment. Liberation rate of copper foil was high at high carbonized temperature. The experimental results indicated that 90% of oversized char was liberated and the copper foil recovery from PCB carbonized at 1073K was 110kg/t. The copper recovery from char powder by flotation was also investigated. 15% of the copper grade and 80 % of the copper recovery were obtained, whereas the removal rate of silicon was 55%.IntroductionWaste Electrical and Electronic Equipments (WEEEs) should be recycled because they have many kinds of valuable materials and most WEEEs include Printed Circuit Boards (PCBs). In Japan, about 30 km2 per year of Printed Circuit board (PCB) has been produced [1], PCBs are normally separated from WEEEs and picked up by hand and sold to non-ferrous metal market because PCBs include high grade of copper and other precious metal such as gold, silver and palladium [2]. However, PCB also has impurities such as silicon, aluminum and calcium which are slag materials in non-ferrous smelting process, and other harmful elements such as lead, bromine and antimony. Low grade PCBs are sold after removal of invaluable parts or sometimes land filled without any treatment"

Jan 1, 2011

By Vladimir Lobanov, Vladimir Skorohodov, Andrew Evdokimov, Ural State Technical University 19, Boris Radionov

"The bulk of raw materials in metallurgy of secondary platinum metals are the wastes such as multilayered ceramic-metal systems, e.g. the spent catalysts of the chemical and petrochemical industry, automobile catalysts, etc. Due high chemical resistance of a ceramic basis the extraction of platinum metals by leaching even at very fine crushing is poor. The study of sorption leaching of platinum and a palladium from the spent automobile catalysts are carried out. The average content of PGM is 0.5%. A few methods of raw materials sampling were compared: 1) direct hydrometallurgical leaching of platinum metals from the fine-grained catalyst and atomic absorption analysis of the obtained solutions; 2) fusion to a metal or sulphidic collector of precious metals with the alloy analysis by direct spectrometry; 3) fusion with dissolution of a precious metals collector and atomic absorption analysis of PGM in solutions. Leaching allows detecting out no more than 90% of a palladium and 80% of platinum. Fusion to a collector gives the best results at the chemical ending. Researches on sorption leaching are executed. Under optimum conditions the extraction of platinum metals to concentrates is comparable with similar indicators of collector fusion.The large part of raw materials in metallurgy of secondary platinum metals are the multilayered or tridimensional ceramic-metal systems, in particular the spent catalysts of the chemical and petrochemical industry, automobile catalysts, ceramic-metal condensers, etc. The content of the sum of PGMs can be from hundreds grams per ton to several percent. For processing of such materials the hydrometallurgical methods of platinum metals leaching by various reagents are used commonly. High chemical resistance of the ceramic basis covering the metal particles causes low recovery even at very fine grinding. Other fundamentally different method of catalysts opening includes dissolution of the ceramic basis in the solutions of hydrofluoric acid and the subsequent recovery of platinum metals from insoluble residue. Application of this method is associated to use of corrosive medias and appropriate equipment. Fusion of the specified materials with collecting of PGM by copper, nickel or lead at the specialized enterprises provides higher extraction in semiproduct. At the same time, complexity and duration of the subsequent extraction of platinum metals concentrates causes high total cost per unit. Thereby this method is economically acceptable only for rather poor raw materials (no more than 0,1%). Undoubtedly, that the raw materials with the high content of PGM are reasonable to process by individual technology. In the present work the processing of some kinds of ceramic-metal raw materials, particularly automobile catalysts (neutralizers) with various collectors at the conditions of a target fusion are investigated."

Jan 1, 2008

By Robert Matusewicz

Ausmelt Technology has been applied to the recycling of spent pot liner (SPL) generated from primary alnminum production. The process is centered on the Ausmelt furnace, in which the SPL is converted under high temperature, oxidizing conditions to an HF containing gas stream and inert slag. fluorine is recovered from the SPL as HF gas and is concentrated and used to manufacture AIF) for recycle to the aluminum smelters. Approximately 87% of the fluorine can be recovered and converted to AIF), with the remainder being effectively tied up in the by product slag. Cost projections show that the recycling process will be competitive with other processes for SPL. The production and recycling of AIF) provides available credit that significantly offsets the operating cost of the facility. Ausmelt Technology for recycling of SPL is currently being marketed in North America by Ausmelt Technology Corporation in Denver, Colorado, and in the rest of the world by Ausmelt Limited of Dandenong, Australia.

Jan 1, 1996

By K. Krishnapisharody

A mathematical model has been developed to predict the interface dynamics and droplet generation of the buoyant phase in a two-fluid system. The model employs the well-known SIMPLE algorithm for obtaining flow fields and the Volume of Fluid (VOF) method, for interface tracking. The implementation of the model in water-oil systems, where the oil layer is placed above a recirculating water bath, is discussed. The evolution of the water-oil interface leading to the formation of oil droplets is computed realistically.

Jan 1, 2008

By M. Jortikka

The smelting process of the old reverberatory furnace including its capacity has been improved over the years in different ways eg. with oxy-fuel burners, parallel reactors with the reverb or with various modifications of the reverb furnace itself. The future reverb modifications with old concepts are difficult or impossible as the increased copper losses in slag call for separate slag treatment and particularly the process modifications do not solve the environmental issues but instead mean unavoidable high capital and operating costs in gas cleaning and sulphur recovery. During the last decades improvement in process performance and increase in capacity of copper flash smelters has been achieved easily by substituting the pre-heated process air by highly oxygen enriched air. The flash furnaces of today, however, are inherently designed to operate with high oxygen enrichment. Further process improvement with a view to production costs and capacity increase as well as to the more stringent environmental requirements is possible with even higher oxygen enrichment. This, apart from the advantages it generates, requires improvements in and careful design of the feed system, concentrate burner, furnace cooling and the off-gas line as well as adaption of the flash converting instead of the conventional Peirce-Smith converters. A logical answer even for the revamping of the reverb smelters in the future is the total replacement of the reverb furnaces with flash smelting together with flash converting. This paper discusses the possibilities for future process improvements of the existing flash smelters taking into account the process concepts, equipment modifications and capital aspects not forgetting the environmental issues. The revamping of the PASAR smelter in Philippines is introduced as an example of a recent success story.

Jan 1, 1994

By L. Katgerman, E. N. Straatsma, Suyitno

"Single-roll strip casting process is studied using computational fluid dynamics which takes into account fluid flow, heat transfer and solidification. The computational model is based on the conservation Jaws of momentum, energy and continuity. Correlation of strip thickness, solidification zone length, and puddle shape on single-roll strip casting of Al-1 %Mn is explored. Feeding pressure and roll speed are investigated. The results show that the··strip thickness slightly increases with pressure, similarly the length of solidification zone. The variations of strip thickness and solidification zone length with roll speed show a sharp decline for strip thickness and slight decline for the length of solidification zone with increasing roll speed. The constraint and free-jet flow have different feature in term of flow field. Severe turbulence is observed on the free-jet flow.IntroductionThe near-net shape casting of strip metals is a demand nowadays. The demand is particularly stimulated by the challenge to become more competitive through enhanced performance. The improvement in the existing processes and new innovative technologies are introduced by the metal industry to gain better product quality, more efficiency in energy consumption, low throughput, yield and operating costs [1-3].There are many advantages that can be obtained by the direct casting of strip. The most prominence is the elimination of hot rolling. Beside that the high rate of heat extraction associated with strip casting offers the possibility of a finer, Jess segregated cast structure. The microstructure will result in the improvement of mechanical properties compared to conventional material, or alternatively the opportunity of using grades of metal outside the normal range for continuous casting.The concept of single-roll strip casting has been difficult to commercialize, because of the complex interactions between fluid flow, solidification, shrinkage, and stress, which lead to serious quality problems. Besides that, the quality and the thickness of the strip are affected by the thermal properties of the strip, roll cooling conditions, roll geometry, and other process parameters. To understand how these parameters affect the strip formation, some researchers have modeled the process [4]."

Jan 1, 2004

By A. V. Tarasov

An environmentally clean and virtually waste-less technology for treatment of domestic solid waste and other toxic chloride-containing materials has been developed and proven on a full scale by the Gintsvetmet Institute in cooperation with some other Russian organizations. The proposed process resolves the acute and globally significant problem of dioxin formation. The purpose of the proposed technology is to ensure such destruction of the structural lattice of toxic compounds that would guarantee irreversible transformation of the resultant substances to prevent formation of dioxins. The preconditions that are required to achieve this purpose are: temperature of >125O0C; an oxidant excess coefficient of >I .05; a certain retention time of the products under these conditions (ADZ s); and thermal instantaneousness of the process involving a transition with no intermediate phase. These conditions were achieved with the experimental development of the Vanyukov furnace design commonly used for sparged smelting processes at non-ferrous metallurgical plants in Russia and Kazakhstan.

Jan 1, 2002

By Batric Pesic

Adsorption of gold on activated carbon from gold bromide solutions was examined as a function of pH, particle size, carbon amount, initial gold bromide concentration, bromine concentration, temperature, and various cations and anions. pH did not have any effect below pH=6. Above pH=6, pH had dramatically negative effect. The adsorption results satisfied a first reaction order model. The reaction rate constant was proportional to the inverse of carbon particle radius. It was also proportional to the amount of carbon, and independent of initial gold concentration. Temperature had a very little effect at pH=l. At pH=8, the activation energy was a function of the extent of a reaction, increasing with the extent of a reaction. Cu, Fe, Ca, Mg, and Na cations and sulfate, chloride and bromide anions did not have any effect on gold adsorption. Bromine had a very negative effect on gold uptake.

Jan 1, 1991

By Xuewei Lv

An intelligent recognition and quantification system for the micrographs iron ore sinter was developed in the current paper. The average distribution parameters in a gray histogram of minerals by a Gaussian gray distribution model were obtained. The feature curves of the gray histogram of two minerals were achieved by combining the two density functions. The feature indexes, such as the number and position of the peaks and the valleys of two minerals in different ratios, were quantified by differentiating the distribution functions. This algorithm is able to extract the feature of the minerals adequately and accurately for recognizing the composition and phases of the minerals intelligently.

Jan 1, 2009

By Jilai Xue, Jun Zhu, Germain Kouma Ndong, Qiaochu Liu, Luxing Feng

"High-temperature oxidation and corrosion behaviors of Ni-Fe-Cr alloy as inert anodes for aluminum electrolysis have been studied in oxygen and molten electrolyte. The oxidation and corrosion scales on the anodes tested were analyzed using XRD and SEM-EDS. The oxidation rate is found to increase with increasing temperature from 700 °C to 950 °C, which can be approximately described by an inverse power rate function. The oxidation scales at 750 °C, 920 °C and 950 °C contain Cr-rich phase along with FeCr204 and (Feo.6Cro4)203. The corrosion extent of Ni-Fe-Cr anodes in electrolyte is dominated by temperature, which can make the scales thickness double from 700 °C to 750 °C or from 920 °C to 950 °C. Cr and Fe in the scales on the anode in electrolysis corrode preferentially into the molten electrolyte, while the nickel oxides could better sustain the corrosive environment in electrolysis. The results can be useful for developing inert anode material for potential application in aluminum electrolysis.IntroductionThe development of an inert anode for aluminum electrolysis has been a long term goal for aluminum industry. The present process for primary aluminum production involves the reduction of alumina with carbon anodes, forming carbon dioxide:"

Jan 1, 2013

By Tomas Astorga

APEC, the Asia Pacific Economic Cooperation is the forum of 21 countries having approximately 56% of the total world income, and over 45% of global trade. In 1997, APEC economies produced 67% of the world copper output, 55% of gold, and over 45% of other base metals. Mining in APEC captures more than 60% of the total mining investment in the world. New and emerging economies are now appearing in the demand scenery, such as China. New trends in the international environmental regulations are posing questions related to the use of copper in different industrial and consumption applications. These may have a strong impact on future trade of copper. New applications are also appearing based in new technology fields. The paper examines the growth potential of the copper market in main consumer ad highly populated economies of APEC, incorporating analysis of various interrelated factors. It also analyses the outlook of the copper supply. Its conclusions point to the need to implement demand outlook models. Finance and economic reforms will open important avenues for trade growth in basic metals, particularly copper. Changes in the consumption patterns of highly populated countries will add to better perspectives of copper demands. The recovery of a fast pace of economic growth in the APEC region will bring new demands for copper, especially as a consequence of high tech applications. More extended policies focused in the need for developing energy efficiency programs and schemes will add to this picture.

Jan 1, 1999