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By Qingcai Liu

The effect of the TiC addition on corrosion resistance of the Al2O3-C refractories in smelting reduction melts has been studied by quasi-station immersion and rotary immersion. The corrosion rate of Al2O3-C refractories is decreased with the TiC addition. The corrosion mechanism of Al2O3-C refractories is oxidization of graphite carbon by the oxides of the melts and the formation of deteriorate layer.

Jan 1, 2006

By Brian Cochran, C. Edward Eckert

"EXECUTIVE SUMMARYINTRODUCTIONThe commercial incentives for using molten aluminum in casting operations are numerous and substantial. Although these incentives apply broadly to both shape castings (foundry) operations and wrought alloy production, the merit of a particular motive is indeed downstream processing sensitive. Melting cost reduction is a universal incentive that impacts on essentially all aluminum products. At a natural gas burner cost of $4.50 per therm, for example, the reverberatory furnace energy cost is at least $0.01 per pound of aluminum melted, exclusive of melt loss, fixed costs, and other expenses. The Aluminum Statistical Review' cited 3.188 million metric tons of secondary aluminum that was recovered by the industry in 1995. This represents a re-melt energy cost of over $70 million. Other incentives to use molten secondary aluminum include throughput enhancement, metal chemistry assurances, environmental considerations, and the avoidance of an in-house scrap processing operation.A traditional disincentive to use molten secondary aluminum is metal quality. If a particular secondary processing operation was successful in achieving and preserving an acceptable metal quality level prior to shipment, the subsequent metal transfer and ladle delivery events would frequently obviate these efforts. For example, a metal superheat on the order of several hundred degrees is required for an unheated transfer ladle to travel 3 to 4 hours to a customer location. The rate of the y-alumina formation reaction approximately doubles for every 120°F increase in temperature, therefore, the effect of excess superheat on melt loss and metal quality is considerable. Linear oxidation reactions, such as magnesia formation in magnesium containing alloys, are influenced to an even greater extent by temperature.The typical quality detractor events are:"

Jan 1, 2000

By Natasa Mitevska

In order to ensure the minimal copper concentration in the reverb furnace slag, the graphical optimization method is used and the optimal slag composition of the reverberatory furnaces No.1 and No.2 in the RTB BOR, Copper Smelter and Refinery (Serbia) is obtained: (Si02) .. 38.0%; (FeO) .. 40.0%; (Fe3O4) = 5.0%; (CaO) = 5.0%; (Al2O3) .. 6.0%. Keywords: Optimization, Reverb Furnace Slag, Graphical Method

Jan 1, 2003

By Dilek Kirgöz, Onuralp Yücel, Murat Alkan

"In this study, Mo containing Fe-based alloys, such as Fe-Ni-Cr-Mo, were synthesized using a mixture of Fe203-NiO-Cr203-Mo03 powders reducing with Al powders by metallothermic process which is a high energy efficient, fast and low-cost production technique for synthesis of cast alloys and advanced ceramics. Detailed thermochemical studies were simulated by using FactSage 6.2 Thermochemical software in order to calculate adiabatic temperature of the reactions and effects of initial molar composition on the final products. In the metallothermic processes, effects of stoichiometric Al addition and addition of the oxide powders (Alz03, Si02, CaO, MgO) on the metal recovery and compositions of final alloys were carried out. Final products were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques.IntroductionSelf Propagating High Temperature Synthesis (SHS) has significant advantages compared to the high technology furnace applications, such as very short processing time, simple operation, low energy requirement and low cost [l, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. [3, 4]. This work aims to establish a scientific and engineering background in the production of some cast Fe based alloys (Fe-Ni-Cr-Mo) which are used as surface coatings, wear-corrosion-oxidation resistive applications via SHS (Self Propagating High Temperature Synthesis) metallurgy which is attractive process technique regarding fast and low-cost production ability of cast alloys."

Jan 1, 2013

By Sebastiaan Peelman

NdFeB permanent magnets are the best available magnets used in many technology applications. However, at their end-of-life (EoL) most of magnets and the contained REEs are lost during the recycling of the bulk metals. The REEs are classified as the most critical raw materials in the European Union, and recycling of REEs from EoL products will reduce their criticality and contribute to the sustainability of REE. Various technological routes have been reported, but most of the methods are effective for highly concentrated magnets or magnet scrap, which is greatly dependent on expensive pre-dismantling processes. This paper presents various innovative metallurgical solutions to the effective REE recovery from current industrial practice for WEEE recycling, including the ferrous scrap from WEEE shredder products and shredder residues from computer hard disk drives. Both hydrometallurgical and combined hydro- and pyrometallurgical REE recovery routes are developed after demagnetization and physical upgrading.

By Finn Olesen, Melina Garcia, Mark William Kennedy

"Furnace resistance is a function of the complex interrelationship between many factors including: operating practice, slag conductivity, temperature, power intensity, and geometry (electrode shape, diameter, spacing, immersion, slag depth, etc.).Accurate prediction of resistance is critical for success of the overall furnace design. The sizing of electrodes, columns, bus-bars, and transformers are all impacted. Estimation of minimum and maximum resistance or maximum operational current, as well as the maximum operating voltage are of fundamental importance.Various mathematical tools have been developed to assist designers with the selection of furnace dimensions and the prediction of resistance. Elkem found the methods of Downing and Urban 1965 and Westly 1975, to be particularly useful.In the current paper, comparisons are drawn between data from spent aluminum pot lining (SPL) demonstration testing at Elkem Bjolvefossen and predictions based on these classical tools and 3D finite element modeling (FEM) with COMSOL.®"

Jan 1, 2012

By Shun Myung Shin, Dong Hyo Yang

Cobalt is recovered from square type of spent lithium ion batteries (LIBs) containing 5~20 % Co, 5~7 % Li, 5~10 % Ni, 15% organic chemicals, and 7% plastics together with Cu, Al, Fe, and Mn. The waste LIB was prepared by physical treatment. After screening, the crushed LIBs were separated to +8 mesh, -8/+16 mesh, and -16 mesh powder. Among these, -16 mesh powder was selected for leaching. The leaching test was investigated at 2 M H2SO4, 6 vol.% H2O2, reaction temperature 60 ?, agitation speed 300 rpm, solid/liquid ratio 50 g/ 500 ml, reaction time 1 h. The leaching efficiency of cobalt was more than 99 % and its concentration was 24.9 g/L. For removing of impurities such as copper, iron, and aluminum in the leaching solution before cobalt solvent extraction, the impurities were eliminated by pH control with alkali solution. For selective extraction of cobalt, the aqueous phase removed impurities was equilibrated with different volumes of 0.4 M Cyanex 272 saponified of 50 %. Extraction efficiency of cobalt was about 80 % at first step. Separation coefficient (ßCo/Li) of cobalt and lithium extractions was 206.5. Over 9.0 % of pure cobalt sulfate solution was obtained after stripping with H2SO4 solution.

Jan 1, 2008

By Jyri Talja, Shaolong Chen, Hannu Mansikkaviita

"For optimum smelting results, proper treatment of the feed is needed to ensure favourable conditions for ignition characteristics, heat balance, mass balance with tolerable impurity levels, and overall process economics. Feed preparation consists of physical treatments before drying (blending), chemical treatments before drying, (roasting, if required), drying itself and physical treatments after drying (fractioning, if required).Effects of fluctuation on mineralogy and moisture should be minimized by blending the concentrates in a bedding plant prior to drying. As an alternative to drying, additional treatments such as roasting for impurity removal may be needed for part of the concentrate.Sustainability, energy efficiency, utilization of waste energy, low gas and dust emissions, product quality, availability and occupational exposure reduction are decisive criteria in drying today. These criteria are best met by the Kumera steam dryer, which has the best energy efficiency, zero CO2 emission, lowest operational and maintenance expenses, and superior availability and product quality.IntroductionFeed preparation plays a crucial role in having a smooth smelting operation and also the overall smelting economics in metal production. Therefore, it is of significant importance for all copper, nickel and lead smelter operations in which sulphide concentrates are fed to the primary smelting furnace. Generally speaking, the higher the metal content in the matte after primary smelting, the more important the feed preparation. This is of particular importance in the direct blister (DB) process for copper production and direct oxygen nickel (DON) for nickel production.Bedding is the first stage in feed preparation. This is very important for the sake of smoothing the mineralogical fluctuation in the feed for better smelting control. Its importance increases as the number of concentrates available for the feed mix decreases."

Jan 1, 2012

By R. Ghisleni, R. E. G. Bohrer, L. Radtke, R. M. C. Santana

"The major source of environmental pollution in urban areas is the transport sector and its impact on human health and the greenhouse is preoccupying. In many works of literature is monitored the pollutants in urban cities, however in specific areas such as universities, they are scarce. Therefore, the aim of this work is to monitorate the gaseous pollutans in a bus terminal at Santa Cruz do Sul University-UNISC and to develop a control framework of the air quality. Six points were selected for monitoring, being one of them inside a bus. The monitoring of CO, HC and CO2 were carried out on arrival and departure of the bus. Preliminary results conducted in a day of spring showed that the most critical condition was during the night shift, where the concentration of CO (200 ppm) was the highest, caused by the vehicles increase, due to the larger number of students.IntroductionThe first major global assessment of climate change science in six years has concluded that changes in the atmosphere, the oceans and glaciers and ice caps show unequivocally that the world is warming. The report released on February 2, 2007, the first of four volumes to be released this year by the IPCC, also confirms that the marked increase in atmospheric concentrations of greenhouse gases is the result of human activities.The transport sector has become by far major source of environmental pollution in urban areas. The continual traffic growth has raised concerns over the impact of traffic emissions on human health and urban environmental quality, and has fuelled the demand for a coherent regulatory framework for the management of traffic, air quality and emission at urban level, as well as at regional and national scales.In Greater Metropolitan São Paulo, Brazil, fossil fuel combustion in the transportation system is a major cause of outdoor air pollution (Miraglia&El Kouri, 2007). In China several studies on gaseous emissions are being conducted by F. Costabile&Alegrini, (2007), developed a study on the pollutants in the city of Beijing suggesting methods for the control of pollution.The results obtained from the estimation of the atmospheric pollutants emitted monthly in Campo Grande/MS, Brazil, by buses and minibuses, which employ diesel, biodiesel or natural gas as fuels showed that the substitution of diesel by biodiesel would diminish the emissions of pollutants (Kozerski&Hess, 2006)."

Jan 1, 2008

By Wanderson Silva Rodrigues, Paulo Adão Marinho dos Santos, José Antonio Silva Souza, Luis Alves Venancio, Emanuel Negrão Macedo

"1 AbstractThe production of alumina from bauxite using the Bayer process generates 0.7 to 2.0 ton of the residue known as red mud per ton of alumina. This material has no large scale current use and is usually stored. This paper shows that it can be used in a suspension with water as a gas effluent cleaner with high efficiency to remove SO2. It can substitute other materials currently used reducing the overall environmental impact and potentially reducing the cost of gas treatment.2 IntroductionThe production of millions of tons per year of alumina around the world generates from 0.7 to 2.0 ton of the residue known as red mud per ton of alumina. The vast majority of the red mud is stored in large sealed lakes. Due to the high reactivity this material is considered dangerous and currently there is no operating process capable of reuse all the material produced at any refinery. These lakes after filled of solid material eventually have the surface revegetated. In any cases they will remain as an environmental passive and need monitoring for decades. The search of industrial processes that combine the cleaning of gas effluents emission and reuse of these residues can contribute to the reduction of the overall impact of the alumina production process.The main objective of this work is to study the efficiency of the red mud as alternative raw material for the control of emissions of SO2 in combustion gases. Usually this is made through alkaline solutions of CaCO3 or NaOH in absorbing equipments like spray towers or packed column. This project main objective is to study the reaction of the SO2 with a suspension of red mud and water in order to obtain the basic parameters to design equipment capable of process this reaction on a pilot scale. With that goal compositions of red mud on spray were processed with flow of gas containing SO2 with concentration similar to the exhaust gases of the combustion process of the refineries."

Jan 1, 2011

By Xiyun Yang

Magnetite was prepared by hydrogen reduction method. For a conversion to cobalt-modified magnetite, magnetite particles were suspended into a solution containing Co2+ and Fe2+ to precipitate a cobalt ferrite layer on the surface. pH value influences the particle composition directly, the desirable CoFe2O4 is obtained when pH value is 12. The coercivity increases with the increase of cobalt content, cobalt efficiency reaches a maximum value at cobalt content of 2.71wt%. With cobalt modification, magnetite particles have similar lattice constant and squareness ratio to that without cobalt modification. TEM and XPS analyses indicate that acicular morphology is retained during the coating process, the epitaxial growth layer consists of CoFe2O4and 0.3Co2O3CoFe2O4 at cobalt content of 2.71wt% and 5.03wt%, respectively.

Jan 1, 2006

By Leonard J. Friedman

The contact process for the production of sulfuric acid has been used commercially since before the turn of the century (1880?s), and rapidly replaced the chamber process after the development of vanadium catalysts in the early 1900's (1910's - 1920's). Plant size has increased from a few tons per week to single train units in excess of 4,000 tons per day. Much of the history of the contact process is in the minds of the few remaining early process pioneers that started in the industry in the 1920's and 1930?s, and in sulfuric acid industry books published in 1921, 1925, 1936, and the last Deucker and West in 1959. Since those not familiar with history are doomed to repeat the failures and mistakes of the past, this paper includes a brief history of the contact process along with the history and development of equipment and materials in each equipment area of the process. The main focus of the paper is to present the development and analysis of equipment and materials in the contact section of the sulfuric acid plant - from the dry tower to stack.

Jan 1, 1999

By Larry M. Southwick

Pneumatic converting (Bessemerizing) of iron revolutionized the steel industry. Bessemerizing of copper (conversion of copper sulfide matte to copper metal) was proposed at almost the same time, but it was slow in being accepted. The differences between iron and copper converting were great and technical problems were substantial. It took 25 years for the process to become viable and another 25 years before a truly economical solution was found. A major economical and productivity problem was the short life for converter refractory linings. The first converters had acid (silica) linings, which were quickly consumed since silica was a flux for the process. Converters had to be relined at least once per day, a laboriously expensive manual process with only the most rudimentary mechanical aids available to assist. The industry was revolutionized almost overnight when finally a viable basic (magnesite) lining was developed. This lasted 100's of days versus less than one, leading to converters that were easier to operate and which handled larger charges. This change occurred after W.H. Peirce and E.A.C. Smith, with support from the Guggenheim interests, successfully operated a basic lined converter in a copper refinery in Baltimore. While Peirce and Smith are generally given credit for the development and explosive acceptance of this idea, a Pittsburgh industrialist, Ralph M. Baggaley, working in an independent smelter in Butte, Montana, successfully built and operated a basic lined converter four years before they did. In fact, the early support for Peirce and Smith likely occurred because Guggenheim's staff were encouraged after thoroughly examining Baggaley on his earlier successes. The questions of technology primacy between Baggaley and Peirce/Smith are ironically similar to those between Wm. Kelly and Bessemer in converting iron to steel. This paper will review what Baggaley (and other early researchers) accomplished, examine why he (or they) did not receive credit equal to Peirce and Smith and explore what his (their) place should be in the development of successful basic linings. More suspects than a Victorian Whodunit.

Jan 1, 1999

By Du Sichen

The present paper presents the modeling of gas-solid reactions in the case of the decomposition of CaCO3, describing the reaction kinetics on the basis of heat-transfer concepts which could be compared with thermogravimetric results. In the case of solid-solid reactions, the present paper describes the model developed for describing solid-solid reactions from dynamic X-ray diffraction technique, developed by the present team. The model has been successful in explaining the formation of spinel from MgO and Al2O3.

Jan 1, 2006

The physico-chemical principles of chloride hydrometallurgy are reviewed to rationalise the complex chemistry in chloride-based processes for metal sulphides in terms of the predicted Eh-log[Cl-] relationships, measured changes in activity of H+, Mz+, Cl- and solubility of Ag(I), Cu(I), Cu(II), Pb(II), Ni(II), Au(III), Sb(III) and Bi(III). These changes reflect the nature of chemical speciation, competing effect of hydration/hydrolysis and chloro-complexation,composite effect of increasing acid and/or salt concentration and decreasing water activity. Rate data for the dissolution of PbS and ZnS in HCl containing Fe(III) or Cu(II) are compared and contrasted to highlight the effect of acid and chloride concentration, water activity, and the nature of oxidant. It is shown that LiCl, NaCl and HCl influence the kinetics of oxidative PbS leaching based on their effect on solubility of PbCl2 co-precipitated with elemental sulphur on the mineral surface. Evidence for the beneficial effect of Cu(II) in sulphide leaching is discussed.

Jan 1, 2003

By Guojun Ma

The entrainment of charge materials, evaporation or volatilization of elements and ejection of slag and metal by spitting or the bursting of gas bubbles are mechanisms whereby stainless steel plant dust are generated from the electric arc furnace and refining converter. TCLP and ASTM D 3987-85 tests on dust that was collected from the baghouse filter system of a South African Stainless Steel plant showed that this dust can be considered hazardous according to South African legislation, due to the high degree of Cr (VI) leachability (~13mg/l for TCLP and ~8mg/l for ASTM vs. regulation threshold of 0.05mg/l in drinking water). The dust is therefore considered to be harmful to both the environment and human health, due to its high solubility in water and carcinogenic properties. It should therefore be treated before being stockpiled or land filled. This paper consequently describes an investigation into the formation of Cr(VI)-containing stainless steel plant dust and the stabilisation thereof in a sintering process, whereby the dust was mixed with a silica-rich clay. It is postulated that Cr(VI) form when the (Mg,Fe,Mn,Cr)3O4spinel phase, CaO, Ca(OH)2 and CaF2 (all of which are present in the dust) react. This reaction was found to take place both at ambient and at high temperatures (1100°C). Stabilization of Cr(VI) in the dust could be achieved at an optimum sintering temperature of 1100°C for a 50mass% dust : 50mass% clay mixture. Chromium emission during the sintering process was found to be low, and within environmental limits.

Jan 1, 2006

By Leszek Hoser

Polycrystalline oxide superconductors that have the perovskite structure, that are oxygen deficient, and that have compositions based. on the so-called. 1-2-3 (YBa2Cu3O7) compound, were investigated.. The materials exhibit a high critical transition to superconductivity at temperatures near 90oK. It was determined that maintaining the oxygen content within the correct range in connection with an appropriate amount of CU ions in the crystal lattice leads to high-critical temperature (Tc:) superconducting properties. High-Tc: superconductors with a critical temperature in the range of 100°K were developed. Further investigations, based. on the theoretical examinations of the origin of superconductivity, have been performed and are discussed..

Jan 1, 1989

By Burkhard Seeger et al.

The oxidation of copper sulfides can be highly accelerated in the presence of nitrous gases (NOx) as reaction catalysts. Sulfur and sulfate are simultaneously produced in this highly exothermic reaction. This process, carried out in sulfuric acid medium, is performed at an approximately normal pressure and at a temperature of around 110 °C, in a closed container, adding either oxygen or air. The oxidation is automatically controlled through a computer. The process covers the following steps: Catalytic oxidation, filtration and crystallisation of the hot concentrated liquid, electrowinning, mother liquor treatment through jarosite formation, recovery of dissolved copper and zinc and regeneration of industrial water, and non-soluble residue treatment with extraction of sulfur and recovery of silver and gold. No combustibles are needed. No air is contaminated, and no waste water is produced. Solid residues are in a stable, non-toxic and non-corrosive state of equilibrium. Risk of accident is low. Investment costs are small compared to those of the comparable pyrometallurgical process, and production costs are competitive.

Jan 1, 1999

By Xiang Ma, Halvor Dalaker, Kai Tang, Stefan Andersson

Silicon carbide (SiC) is one of the most important non-oxide ceramic materials for many industrial applications and is mainly synthesized by carbothermic reduction of silicon oxide by coke above 2200°C. Replacing natural gas (mostly methane, CH4) for coke in SiC synthesis could considerably reduce energy consumption and CO2-emissions owing to higher carbon activity of CH4 at lower temperature. The generally accepted reaction mechanism is that SiC is synthesized through gaseous intermediate silicon monoxide, SiO. In the present study, the reaction mechanism for the SiO and CH4 gaseous mixture has been examined using atomic scale modelling. Molecular dynamics (MD) using a reactive force field (ReaxFF) has been utilized to examine the initial stages of reactions involving a gas mixture of SiO and CH4 and surfaces of SiC. The MD results revealed some interesting SiC formation mechanisms. The reaction energies of the critical intermediate species were also estimated by density functional theory (DFT) calculations and the implications for the force field parameters used in ReaxFF was discussed.

Jan 1, 2015

By Jimsher Aneli

The investigation of some peculiarities of conductivity dependence on filler type and amount in the polymer composites has been conducted. It is established, that conductivity of composites based on phenolformaldehide resin essentially depends on proportion of double fillers: graphite + carbon black, graphite+ andesite, contained in composites. It was shown, that these composites characterized by synergetic effect ? non additive influence of fillers concentration on the conductivity of composites. Some other properties of composites contained binary fillers (effect of temperature and pressure on the conductivity) have been investigated.

Jan 1, 2006