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By Y. Iguchi, T. Narushima, T. Shiozawa, M. Maruyama, R. Arashi

"In situ observation system for thermal oxidation using Raman spectroscopy' was constructed, and oxide films formed on liquid pure Al and Al-Mg alloys (Mg contents = 1 and 4 mass%) were analyzed at room temperature to 1273 K in dry oxygen. In situ Raman spectra of the surface of a liquid Al-:-4mass%Mg indicated the formation of MgO • AlP3 (spinel) as oxidation products, while a -AlP3 and MgO • Alz03 (spinel) were observed on a liquid Al-1mass%Mg alloy. It was suggested that the formation of MgO film affected oxidation behavior of these alloys.IntroductionLiquid aluminum alloys are cast to ingots mainly by the continuous casting process. It is well-.known that surface cracks could be caused by oxide films formed on the surface of melt during continuous casting and defects due to the film. With regard to oxidation behavior of liquid aluminum alloys, many investigations l -s have been carried out from the view point of formation of ceramic metal composites(CMC) which are expected as cutting tools and structural materials 1.2. It is very important for reasonable continuous casting and CMC formation processes to elucidate oxidation behavior of melts.Oxidation behavior of materials generally depends on compositions and properties of oxide films formed on the surface. If in situ observations of oxide films are available during oxidation, evaluation of oxide films and interpretation of oxidation mechanism could be expected. Laser Raman spectroscopy is one of the most appropriate techniques for in situ observation of oxide films under various atmosphere at high temperatures. The authors have discussed the effects of atmospheres and sample compositions on oxide film formation mechanism on Fe-Si alloy6 and SiC-B4C composite7 on basis of an in situ observation by Raman spectroscopy. In spite of many previous studies, systematic and clear explanations have never been gotten on oxidation behavior of liquid aluminum alloys. And no in situ observation has been made except for transmission electron microscopy(TEM) and X-ray diffraction(XRD)."

Jan 1, 1996

By H. Roberts, C. Hassall

The opening years of the new millennium will be characterised by the closure of many lead and zinc mines because of reserve depletion. However, weak commodity prices through the second half of the 1990s have slowed project evaluation and have made it difficult to raise finances for the development of new mines required to replace lost output and to meet increasing demand for metal in the future. Growth of lead and zinc demand will be determined by the pace of global economic activity, especially in the emerging economies. How rapidly demand grows will have a key bearing on the possible shortfall in mine output and the response of prices to the implied tightening of metal supplies early in the new millennium. These issues are the focus of a discussion of the critical lead and zinc supply developments which will unfold post 2000, taking into account project lead times and the role that recycled metal plays in meeting market demand.

Jan 1, 2000

By Mike Dry

While McCabe-Thiele plots are useful for designing single-component solvent extraction systems, not least because of their simplicity, they are less useful for multi-component solvent extraction. This paper presents a relatively simple method, compared to other approaches, for modelling solvent extraction as chemical equilibrium reactions between the various aqueous and organic species. The essence of this approach is how values for the equilibrium constants can be extracted from standard laboratory data. Synergistic solvent extraction of nickel is used to illustrate the method.

By M. R. Jolly, J. -C. Gebelin

"A number of different types of so-called ""filters"" are used in the metal casting industries to impart some cleaning effect and flow control on the liquid metal as it passes through them. The filters range from simple planar meshes through extruded channels to reticulated foam structures and they are manufactured from a range of material going from metals to glass or ceramics. It is most common that software packages used in the industry model the filters by a simple pressure drop associated with some area fraction and permeability parameters.Recent experimental work at the IRC in Birmingham [1] has shown that filters of the same type can behave very differently depending upon the casting process in which they are employed. Modelling filter geometries for a range of different casting processes has indicated that the flow of metal and heat losses through the filters are rather complex and should be considered when using filters in the casting processes. This paper will present a number of cases of different types of filters modelled and different processes and indicate some of the sensitivities of the processes to boundary conditions imposed by the process.IntroductionFilters are commonly used in the foundry industry. The real action of the filters on the liquid metal is not really understood. Some filters are claimed to have a chemical action on the liquid metal or to be able to clean the metal by stopping the impurities or oxides that will result in inclusions in the cast part. However, some recent experiment carried out at the University of Birmingham in investment casting and results available on sand casting [2] have shown that the action of filters may be different in these two processes. As the main difference between these two processes is the mould temperature, the hypothesis of a partial solidification of the metal in the filter occurring in the sand casting process during the primary stage of the filling has been advanced, whereas there is little or no solidification in investment casting. In order to verify this hypothesis, and to reach a better understanding of how filters work, a numerical investigation of the flow and heat transfer in filters in both sand and investment casting has started at the University of Birmingham, in the framework of the FOCAST project. The FOCAST project is an EPSRC project aimed to increase the understanding of the investment casting process. Another issue is the way the simulation packages predict the influence of the filters on the metal flow. The filters are most of the time modelled as porous obstacles characterised by a pressure drop calculated from porosity and some surface ratios or proprietary coefficients. This paper will present the preliminary results of this numerical investigation. First, the different models that have been used are presented, followed by the obtained results. A discussion of these results and their perspectives conclude the paper."

Jan 1, 2001

By Jiling Wang, Xuefeng Liu, Haojian Duan, Lifeng Zhang, Ying Ren, Wen Yang

"In order to study the influence of MgO-C refractory on steel cleanliness and inclusions during steelmaking process, and to understand the reaction mechanism deeply, laboratory deoxidation and equilibrium experiments were respectively performed in MgO crucibles at 1873K. In the former experiment, after Al addition, steel samples were taken at different holding time. In the latter experiment, different slag components and different contents of carbon and aluminum in steel were considered respectively. The inclusion characteristics of each experiment were analyzed. The results showed that with the increasing of holding time after deoxidation by Al, MgO existed in the small inclusions firstly, and then in the large ones such as the clusters. The MgO content in the inclusions increased with the increasing of holding time, indicating that the MgO in crucible could be individually reduced by the aluminum in the molten steel. The reaction could occur within nine minutes.IntroductionNon-metallic inclusions would have positive or negative effect on steel quality depend on the quantity, size and composition of inclusions. Large inclusions are always detrimental. From the point of view of inclusion property, plastic inclusions are required by steel cord, while hard inclusions are preferred by pipeline steel. One of the most important ways to increase the steel quality is reducing the inclusion size and controlling the inclusion composition in steel. Nowadays, MgO based refractory is used as ladle glaze material with more and more frequency, which results in different inclusion characteristics in molten steel, for example, the inevitable generation of MgO contained inclusions during ladle treatment of steel. In other words, the inclusions in this type ladle will influence on the steel cleanliness and the product property. Thus, keeping an eye on the inclusion formation behavior in the steel with MgO-C ladle glaze is important for the steel industry. There have been a few studies in this regard. Li et al[l] studied the reactions between MgO-C refractory, molten slag and metal using a high temperature X-ray radiographic apparatus. They found that the local corrosion was regarded as due to the cyclic dissolution of MgO and graphite in the refractory into slag and metal phase. The gas bubbles formed according to the reaction of (FeO)+C(s)=Fe(l)+CO(g) greatly influenced the corrosion. On an industrial scale, Du[2] found that ladle glaze is a major source of inclusions in the ladle. An experimental study has been performed by Lehmann in order to estimate the importance of the reaction between a MgO-based tundish refractory and an Al-killed steel[3]."

Jan 1, 2014

By C. G. Bastos Andrade, V. F. Justo, F. R. Valenzuela-Diaz, M. G. S. Valenzuela, C. M. Matos, C. Volzone

For industrial use, the smectite clays are usually treated with inorganic acid of high concentration at temperatures under boiling point, which provide the bentonite´s bleaching power. In the present paper, a sample of brown smectite from Paraiba, Brazil, was submitted to treatment under moderate conditions (90°C, reaction times of 1, 6, 12, 18 and 24hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5M, clay/acid solution ratio of 1g/10mL), aiming to reduce impurities, responsible for the color of the clay, without causing significant changes in their structure. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray detector (EDS), stereomicroscopy, Cation Exchange Capacity (CEC), Thermal Analysis (TG/DTA), and X-ray diffraction (XRD). It was observed a bleaching in samples with time of 12h to 18h. With the DRX was possible to monitor the peak intensity of the clay structure and the sample with 12 hours of treatment was not significantly altered its crystalline structure, maintaining the peak clay at d(001). The most pronounced changes in the bleaching occurred within the first 12 hours of acid treatment. Thus, clay can be used in products with high added value.

Jan 1, 2015

By Tsisana Gagnidze

A processing of technogenous wastes, which involve a gold-containing sulphide minerals, is a potential source to supplement the gold reserves. Hence, searching of ecologically safe and economically reasonable methods for processing of gold-containing technogenous wastes is a topical problem. To increase a parameters of gold extraction and to simplify a technology of the processing of above-mentioned wastes of sulphide minerals, an investigations have been carried out in the direction of the use of the method of electrochemical leaching without any preliminary processing of the mineral. It was established experimentally that an introduction of nitrogen containing organic additive into chloride solution favours to reduce a Red/Ox potential of the solution from 0,8÷1,2 V to 0,35÷0,5V, which permits to conduct the process of direct electrochemical leaching at ?soft? oxidation regimes at temperatures 20-300C C without an environmental contamination by molecular chlorine and with a high degree of a gold extraction up to 80-90%.

Jan 1, 2008

By Emilia Visileanu, Eftalea Carpus

"Due to the demographic explosion and development without precedent of the consumer society, the capacity to destroy the ecological balance the entire planet life depends on, acquire new dimensions. In this context new approaches on society development are imposing as well as special responsibilities for stopping and preventing Earth destruction and repairing the damage already done. The zero waste is a call to action that has as an aim the changing of current mentality of human society. ”take, use, throw away”. The zero waste is a policy, a way, an aim and represents a new approach planned for the XXI century that include the resources preservation principles, pollution reducing, increasing of the opportunities to create new work places and providing the highest degree of the.1. INTRODUCTIONThe zero waste is a call to action that has as an aim the changing of current mentality of human society. ”take, use, throw away”. The zero waste is a policy, a way, an aim and represents a new approach planned for the XXI century that include the resources preservation principles, pollution reducing, increasing of the opportunities to create new work places and providing the highest degree of the economy stability.2. ECOLOGICAL CONCEPTSA long-living Romania means:The closing of the production cycles, by waste reusing and recycling; the reducing of the use of fossil fuel; the improving of the material qualities, for extending the economical life of the products made by these materials; the reducing of the transport traffic.In this context, ecology, the star science with the ability to conserving and renewal of the environment is making its way, having the following principles:•,everything is bind by everything – is referring to the importance which the environment has for a great number of allied fields;•,everything leads to somewhere – the principle of the indestructible property of material (in nature, there must not exist wastes);•,nature does it the best – ecology becomes the responsible science with the governing of the strategic laws between man and nature, man takes advantage of the natural resources which he cannot create by himself and nature must feel guarded and not destroyed by this alliance;•,nothing is for free – the polluter pays.The protection of the natural environment means:•, its strong knowledge and that of the interactions between the social economic system and the natural system, the foreseen of the most close and most distant consequences of these interactions;•,the rational usage with maximum economical character of the natural resources not depending on their origin;•,preventing and direct fighting against as well on the degradation of the environment caused by man, as on those produced by natural causes;•,the ability to harmonize immediate interest of the human society on long and permanent term, using the natural factors of the environment."

Jan 1, 2008

By R. E. Molnar

A number of flowsheets have been designed and operated, or are currently being considered, to extract copper from leach solutions having much more copper than the 4 g/L levels typically found in heap leach liquors. Dealing with these solutions has required that the envelope for ?normal? copper solvent extraction be pushed beyond the usually considered limits. Others have published information on flowsheets to recover copper from leach liquors containing over 25 g/L copper. Secondary solvent extraction circuits are often required to attain satisfactory overall recoveries. This paper reviews some of the issues faced in three pilot plant circuits that were operated by SGS Lakefield Research to produce cathode copper from solutions containing 8 to 20 g/L Cu. The primary objective was to maximize copper extraction using one solvent extraction circuit. The role of feed acidity and the disposition of impurities such as iron and chloride are considered. The challenges of running short SX piloting campaigns are discussed.

Jan 1, 2003

By Gui-fang ZHANG, Zhe SHI, Lei GAO

Secondary V-recycling slag, an industrial waste containing high gallium is being dumped continuously, which causes the loss of gallium. Thus, the alkali fusion process was employed to recover gallium from this slag. The effects factors on extraction of gallium such as roasting temperature, roasting time, alkali fusion agent concentration and CaO concentration were investigated in the paper. The experimental results indicated that excessive roasting temperature and roasting time is unfavorable to the recovery rate of gallium. The appropriate roasting temperature and duration are 1000 and 2 hours, respectively; The appropriate proportioning of Na2CO3: NaOH is 2:1 when the concentration of alkali fusion agent weighs 0.4 times the mass of the slag; In order to remove SiO2 from the leaching liquor, CaO should be used as an additive in the roasting process. The appropriate concentration of CaO should weigh 0.2 times the mass of the slag. Employing these optimal alkali fusion conditions in the roasting process, gallium recovery is above 90%

Jan 1, 2015

By C. J. Parradies

During injection into a die, semi-solid metal alloys exhibit a shear-rate, history-dependent flow response. Simulating the injection of a thixotropic material requires that empirically determined boundary conditions and viscosity are specified as a function of both temperature and shear rate history. Experiments were performed using an industrial die casting machine that was instrumented with sensors to measure the pressure and temperature during the injection of a semi-solid aluminum alloy through a tube. This benchmark experiment was used to develop a simulation of the die casting process that could then be applied to more complex die geometries. The results of the experiments were analyzed using the exact, steady state solution for a power law fluid and simulations accounting for slipping at the boundary between the semi-solid metal and the die. Results indicated that the no-slip condition cannot be used to simulate the velocity boundary condition, because the measured pressure is much lower than that predicted by the models. An estimated apparent slip coefficient was introduced to account for the reduced pressure. During some of the experiments, a sudden drop in the measured pressured, prior to decreasing the ram velocity, coincided with observations of segregation in the form of concentric rings visible on the polished surface of cross-sections cut from material remaining in the tube.

Jan 1, 1997

By D. Gregurek

In non-ferrous metal furnaces the installed magnesia-chromite refractory lining is exposed to several stresses, rather complex in their interaction. Therefore, a detailed investigation and understanding of wear mechanisms through “post mortem studies” is an important prerequisite for refractory producer. Additionally, in order to determine the most suitable refractory products and to improve the lining life of refractories, practical corrosion testing with processing slags is performed. For this purpose the test-facilities, such as induction furnace, rotary kiln but also cup test and drip slag test, allow the best possible understanding of chemothermal brick wear on pilot scale. Prior to testing a complete mineralogical investigation, thermo-chemical calculation via FactSageTM of the slag was carried out. Based on such research results, combined with specific process knowledge RHI Magnesita can recommend appropriate brick lining solutions for non-ferrous metal furnaces.

By C. E. Abbey

Cobalt, iron and manganese play various roles in copper electrowinning using lead–calcium–tin alloyed anodes. Cobalt catalyzes electrochemical water decomposition resulting in lower anode potential and reduced corrosion rates. Iron reduces cathodic current efficiency, but is used to reduce higher oxidation states of manganese that oxidize organics in solvent extraction. Manganese also produces anode scale and is generally considered a problematic impurity. The effect of the combined interaction of these three metal ions on the anode potential has not been quantified yet. The current work used a three factor, two level, three replicate central composite design of experiments to analyze the effects and potential interactions among cobalt, iron and manganese. The experiments consisted of chronopotentiometric analysis to assess anode potential after 24 h of operation. Higher [Co], lower [Mn] and either high or low [Fe] yielded lower anode potentials. Two regression models were developed to predict anode potential as a function of [Co], [Fe] and [Mn]. A method to estimate electrical energy consumption for copper electrowinning is also presented.

By T. J. A. Smith

This paper provides an overview of some of the key issues in design of smelter gas handling systems, with particular reference to smelter smelting plants. In both primary smelting and converting, gas handling and treatment systems often represent the major capital cost component. There is also ample evidence that poor system design can be a major cause of smelter down time, lost production and unforeseen high maintenance costs. The paper discusses these issues and offers guidance for improved design.

Jan 1, 1992

By Nagahiro Saito, Takahiro Ishizaki, Mituhito Hirota, Akio Fuwa

"Owing to their extremely high toxicity in the environment, the dioxins have been attracting social, technical and scientific attention in recent years. The authors theoretically had predicted the thermodynamic properties of all the dioxins via quantum chemistry and statistical thermodynamics and elucidated the generation-decomposition behavior of dioxins in the equilibrium calculation· of C-H-0-Cl system. In actual combustion processes, it is said that metallic compounds have much influences on the dioxins behavior. The aim of this study is to reveal the roles of metallic compounds the generation-decomposition behavior of dioxins is revealed from the viewpoints of quantum chemistry. Especially, the catalytic effect of copper has been investigated for the reaction, 2HCl(g)--H2(g}+Cl2(g) and for the etherification reaction from precursors, which is Phenol(g) here, to dioxins. The catalytic role of Cu is shown to have much influence on the generation -decomposition of dioxins.1. IntroductionIt is well known that dioxins are very harmful not only for our health but also for that of our children and grandchildren because they are very stable substance and their reaction rates of decomposition are considerably low. On the other hands, it is not well know how dioxins are generated and decomposed; the generation-decomposition conditions and paths as well as the catalysts to decompose them'1l. The authors believe that the thermodynamic and kinetic study of dioxins is useful to find a solution to these issuers. The authors have been investigating the following problems to reveal the generation-decomposition behavior of dioxins; (a) the prediction of the thermodynamic parameters of dioxins (2), (3), (b) the generation -decomposition behavior of non-chlorinated dioxins by the thermodynamic equilibrium calculations in C-H-O system(4) and (c) the generation-decomposition behavior of dioxins by the thermodynamic equilibrium calculations in C-H-O-CI system(5). Summaries of these thermodynamic researches are as follows.(I) The thermodynamic parameters for dioxins, which had been unknown and/or inaccurate'6 l, could be predicted and are available within the scientific accuracy."

Jan 1, 2000

By W. J. Guay

Scrubbing of simulated copper reverberatory furnace gases containing 1.0 percent sulfur dioxide with the minus 74 ~m fraction of the San Manuel tailings has shown sulfur dioxide removals of almost 100 percent over an effluent pH range of 3.1 to 4.6 and a wide range of liquid to gas ratios with absorptions of 11 to 17 Kg of sulfur dioxide per tonne of minus 74 um slimes. The high reactivity of the tailings slimes with S02 indicates that the reaction rate is not controlled by the slow dissolution of calcium carbonate in sulfurous acid which characterizes scrubbers using ground limestone. The interpretation of these results has been considerably enhanced by wet chemical analysis and emission spectrographic analysis which show that calcium and iron account for about 90 percent of the SO2 absorption with the rest being accounted for by aluminum, magnesium, potassium, and sodium. Mineralogic examination confirms the, chemical and spectrographic analyses showing that the major constituent removed from the slimes is calcium carbonate, with lesser amounts of chlorite and montmorillonite (silicates containing iron, magnesium, aluminum, and calcium) being removed.

Jan 1, 1981

By Takahiro Furuzono

Saganoseki Smelter and Refinery of Pan Pacific Copper Co., Ltd. started treating copper anode slimes using a unique hydrometallurgical process in chloride media in 1997. The process comprises the following stages, decopperizing, wet chlorination, solvent extraction for gold, silver chloride reduction, and separate reduction stages that treat the gold extraction raffinate with sulfur dioxide gas. Precious metals and rare metals in the copper anode slimes are dissolved in an aqueous solution of hydrochloric acid by oxidative leaching, which is termed wet chlorination. Gold is efficiently extracted from the chlorination liquor by dibutyl carbitol in the solvent extraction stage. Gold is reduced by oxalic acid from goldloaded dibutyl carbitol and recovered as gold powder. The gold powder is cast directly into granules or ingots of more than 99.99% purity without electrorefining. Selenium is recovered as a selenium residue by reduction with sulfur dioxide gas and refined through vacuum distillation. The plant was designed to process 132 tonnes of copper anode slimes per month and has a current capacity of 206 tonnes per month due to several enhancements. Compared with the conventional process, the hydrometallurgical process described here provides some advantages, in particular, a higher product quality, shorter gold-retention time, and reduction in environmental load.

"Injection technology has been an important subject from the early days of ladle metallurgy until the present. During the last decade, there have not been many publications in the area of injection technology. It is the author's opinion that with the challenge to find new solutions especially to environmental and energy related problems as well as better understanding of phenomenas from computer modelling, a new era of inventive injection technology developments is at hand. This is illustrated in the article with examples from six different areas where MEFOS is or have recently carried out R&D work related to issues from the injection technology field. IntroductionThe boom in injection technologies came with the introduction of ladle metallurgy treatment during the '70s and '80s. Since then, the theories and principles have been thoroughly laid down by a number of scientists and also published at several early SCANINJECT conferences.Not many new technologies/applications have been presented during the last ten years. This might lead one to believe that everything is known and done. Those, like MEFOS, who are challenged to find technological solutions to a number of environmental problems and energy saving issues in the pyrometallurgical field are, however, continuously faced with the task of developing new injection technologies.Especially, the call for sustainable technologies to solve environmental problems is a challenge for metallurgists all over the world and it will surely induce a revival of injection technologies. So, in order to encourage all injection experts, let us share some new experiences and let us encourage each other's creativity to solve some of the demands of the future society.The following show some examples of technologies under development, or recently tested."

Jan 1, 1996

By S. Abe

Various copper anodes to be electrorefined were subjected to a heat treatment comprising annealing at a temperature in the range of 700 °c to 1,000 °c followed by a slow cooling preferably on the order of about 150 °c, and using these heat treated anodes , a series of dissolution experiments were conducted under conventional electrorefining conditions. The results obtained have indicated that the above annealing/slow cooling process dramatically improves the dissolution activity regardless of the type of anodes. As an example, passivation times of l to 3 minutes in a standard test have been increased to more than 80 minutes by this innovated heat treatment. Other advantages sterning from the improved anodic activity include reduced electrical short circuiting which results in substantial labor effort in the tankhouse, reduced energy requirement, and reduced cost of processing anode slimes because the amount of anode slimes is reduced. In addition, this process gives rise to a dramatic change in the nature of anode slime layer formed in such a way that a comparable final cathode copper product can be achieved even from high-impurity copper starting material.

Jan 1, 1987

By Reimers. Jan H.

Practically all the world's lead is produced by sintering and blast furnace smelting, or the Imperial Smelting Process which is a variant of the blast furnace process. Increased coke and labour costs and strict lead emission limits have, however, made blast furnace smelting undesirable in most countries. A change-over to other lead smelting processes providing better working conditions and lower emissions is, therefore,. expected to occur once economic conditions improve and the necessary capital expenditures can be justified. The need for new lead smelting processes has long been evident and a number of new processes have been proposed 'and advanced to various stages of development. One of the new processes is already proven on commercial scale, while several others are still being tested on pilot plant scale.

Jan 1, 1983