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By B. Q. Li, H. C. de Groh, X. Lu

"A fully 3-D, transient finite element model is developed to represent the magnetic damping effects on complex fluid flow, heat transfer and electromagnetic field distributions in a metallic melt. The model development is based on our in-house finite element code for the fluid flow, heat transfer and electromagnetic field calculations. The numerical model is tested against numerical and experimental results for water as reported in literature. Various numerical simulations are carried out for the melt convection and temperature distribution with and without the presence of a transverse magnetic field. Numerical results show that magnetic damping can be effectively applied to stabilize melt flow, reduce turbulence and flow levels in the melt and over a certain threshold value a higher magnetic field resulted in a greater reduction in velocity. Also, for the study of melt flow instability, a long enough running time is needed to ensure the final fluid flow recirculation pattern. Moreover, numerical results suggest that there seems to exist a threshold value of applied magnetic field, above which magnetic damping becomes possible and below which the convection in the melt is actually enhanced.1. INTRODUCTIONThe imposition of a DC magnetic field on a moving, electrically conducting fluid, such as molten metal or semiconductor melt, produces an opposing Lorentz force that results in a reduction of flow velocity in the liquid. This effect has been explored in both the semiconductor and metals industries to control natural convection and/or surface tension induced Marangoni convection as well as thermally induced flow instability during solidification processing of these melts [1-6]. A mathematical model can be of great use in developing both fundamental understanding of the fluid-magnetic field interactions in these magnetically-assisted processing systems and basic guidelines for process design, control and optimization.This paper presents a 3-D mathematical model for magnetically damped fluid flow and heat transfer in a melt cavity, which is useful for interpreting results for unidirectional solidification processes at slow solidification rate, and some preliminary results concerning the magnetic damping effects on the flow instability in the melt. The model development is based on the finite element solution of the Navier-Stokes equations, energy equations and equations for induced electric field. The model is tested against reported results and is then applied to study the fluid flow and thermal distribution in the metallic melt with and without an external magnetic field."

Jan 1, 1999

By Mark Kramer

This paper is limited to treatment of bottom and fly ash waste resulting from WTE and RTE Cogeneration plants, commonly known as trash burners. The body of the paper defines waste generation and conventional treatment schemes. This paper does not identify a best treatment, however, it does offer a general perspective of the treatments to lead the reader to further investigation. Advantages and disadvantages of the ash treatments Is discussed in each treatment section.

Jan 1, 1996

By Hongfa Hu, Stavros A. Argyropoulos

"This paper describes a mathematical model which simulates numerically reaction driven fluid flow phenomena. The driving force of this reaction is an exothermic heat of mixing. In addition, the model predicts the heat and mass transfer phenomena where both heat source and heat sink co-exist in close proximity. The heat source is generated by an exothermic reaction. The heat sink is formed by a moving boundary such as the melting of a solid. This type of phenomena occur quite often in various metal processing operations in which exothermic additions are immersed in liquid metals. The model is based on the SIMPLER algorithm and uses an enthalpy method to predict the fluid flow, temperature, and concentration fields. The results indicate that the exothermic mixing reaction was responsible for an abrupt rise in temperature around the moving boundary. The intensity of this reaction was also found to be responsible for the enhanced convection of fluid and the acceleration of the moving boundary. The modelling results were also verified by experimental work which included velocity and temperature measurements in a low temperature physical model. IntroductionAlloying additions are used extensively in the treatment of liquid metals during metallurgical processes. The alloying additions introduced into liquid metals can be classified into various classes, each of which follows its own route[l]. As a major group, the exothermic additions follow two different steps during their assimilation into liquid metals. In the first step, upon immersion, a metal shell solidifies around such additions, and then melts back. At this point, the second step commences. During this second step, due to the mixing of the addition with a liquid metal, an exothermic reaction occurs, which liberates large amounts of heat, resulting in an enhanced convection in the liquid metal surrounding the addition."

Jan 1, 1994

By Peijia Lin

Wheat straw was chemically modified by alkaline treatment followed by succinylation and sodium carbonate treatment for the use of cadmium and nickel adsorbent. The adsorption efficiency was calculated in different conditions. The experimental parameters were solution pH, adsorbent dosage, contact time and initial metal concentrations. The biosorbent was analysed by FTIR (Fourier- Transform Infrared Spectroscopy) to investigate the changes of surface functional group. The maximum adsorption percentages of cadmium (>99%) and nickel (>98%) were achieved using 5 g/L adsorbent with 50 mg/L initial metal concentrations. The adsorption kinetic study showed that the reaction was pseudo-second order kinetics and the adsorption isotherm was well fit by the Langmuir adsorption model. The dynamic column study indicates that modified adsorbent has a better adsorption capacity towards cadmium than nickel.

Primary sulphidic gold ores in the Archean provinces of Western Australia can be broadly sub-divided into pyritic, pyrite-telluride, arsenical and antimonial types. Pyritic ores contain only native gold, and are essentially not refractory. Arsenical ores almost always carry some invisible gold, and may vary from mildly to highly refractory. Pyrite-telluride ores contain gold-bearing tellurides, and are refractory to varying degrees. Antimonial ores usually contain aurostibite, and may be very difficult to process. A classification scheme for metallurgical processing, based on mineralogy, is proposed for the ores, and implications for processing are discussed.

Jan 1, 1995

By Sui Xue

A process has been developed from laboratory-scale experiments for the aqueous processing of various lead-bearing wastes. The process exploits the limited solubility of lead in sulfate-rich solutions to effectively separate lead from other metals. The lead sulfate is then completely converted to lead carbonate using sodium carbonate and ammonium carbonate. The effectiveness of this conversion was observed to be sensitive to the solution pH and carbonate concentration. The final stage of the process uses low temperature calcination of the lead carbonate to form PbO. Yellow lead oxide (massicot) is readily formed if calcination is conducted at a temperature at or iibove 50G°C, wlule red iead oxide (iitharge) is formed at temperatures near 450°?C. A complete economical analysis of the process will be discussed.

Jan 1, 1996

By S. Katz, V. Stanek, K. L. Moore, E. D. Larsen, D. E. Clark, P. E. King

"Cupola melting is a complex physical and chemical process having a number of nonlinearities which make conventional process control difficult. In addition, sensors for both inputs and outputs of interest to the foundry operator are often difficult or impractical to apply in a production situation. The present work is an effort to control the process using both intelligent and conventional control techniques as appropriate. Neural networks are used as an inverse process model in a cascade, feedforward controller in conjunction with a finite difference model of the cupola. A separate implementation of the neural net serves as a stand-alone visualization tool; it can operate on a laptop computer and is a useful tool for the cupola operator. IntroductionThe goal of the present work is to develop a controller to improve the efficiency of cupola melting. Although cupola melting as a process has a long history, automatic control has been elusive because the process has been poorly understood. The purpose of this four-year program, which has been underway for about six months, is to develop a controller for the cupola process using intelligent and conventional control methods.The Cupola ProcessThe cupola furnace [1,2] is one of the oldest processes for making cast iron, and is still the dominant method. It takes the form of a water-cooled vertical cylinder, as large as 4 m in diameter and 20 m tall. The charge consists of scrap metal, alloying ingredients, limestone, and coke, which serves as fuel; it is composed by weight and fed through doors near the top of the cupola. Air, usually heated and often enriched with oxygen, is blown in near the bottom through tuyeres extending a short distance into the interior of the cupola. As the coke is consumed, the charge drops and melts. A continuous flow of iron emerges from the bottom of the furnace, at rates as high as 100 tons per hour, and. is transferred to casting lines in the foundry. The exhaust gases are drawn from the top of the cupola, where they are processed to meet pollution standards."

Jan 1, 1994

By Shengli Tao, Hongxu Li, Hao Bai, Yu Chen, Daqiang Cang

"China is the world's largest steel producer, in order to give environment load comprehensive analysis of steel and iron industry in china using LCA method, the life cycle inventory was compiled and assessment model based on Gabi software was also established. Environmental impact of two different routes ofBF-BOF and the EAF were analyzed respectively and intercompared. The results show that the modem EAF route is superior to the traditional BFBOF route on almost all the environmental impact indexes, which including acidification potential, eutrification potential, global warming potential, ozone depletion potential, etc. In the whole life cycle ofBF-BOF route in China, the transporting process ranks the biggest contribution part to the overall global warming potential, which can be explained by the fossil fuel burning of transporting vehicles during the long distance from Australia to China as the iron ore used are mainly imported from Australia. Apart from transporting process, Coking, blast furnace and iron mining processes could induce great environmental problems, while for the EAF route, the electricity consumption is considerable, which causing large amount ofC02 emission indirectly. Based on the analysis, several further countermeasures were proposed. Key words: Iron and steel industry, LCA, Gabi software, C02 emissionIntroductionCrude steel of china which reached 101.24 million tons in 1999 ranked the first column in the world since1999, So far has been to keep the world's largest steel output. At the year of2009, China crude steel output of 568 million tons, accounting for 46.6% of the global crude steel production, more than the total sum of crude steel production produced by 20 countries ranked behind. In 2011, China's crude steel production which is expected to be or close to 700 million tons, an increase of 12% than last year, will account for half of the global steel production.The steel industry, however, is intensive resources industry with huge consumptions of energy and water together with mineral resources. Energy consumption of the iron and steel industry has been about 10% of the total energy consumption since 1980. Coal dominants, power next and other energies share least in the energy consumption structure, for example coal accounts for 72.19%, power 23.52% and other total sums less than 5% in the steel energy consumption at year of 2002[2,3]. The consumption of coal discharges much emission of CO2, yet emissions of C02 in China steel industry, secondary only to the power and cement industry, ranked the third, and the coal dominant energy structure and its process have a close relationship. The aim of this research is to target steel production of typical blast furnace-converter (BFBOF) and electric furnace, using GABI software to evaluate and analyze resources and environment influence of LCA, directing at the existing problems in the development of China steel as well as finding the possible way to improve ability of reducing pollution and energy consumption in order to realize the sustainable development of the steel industry [ 4-7]."

Jan 1, 2012

By V. J. Ramirez, A. M. E. Noguez, M. J. Navarrete, B. G. Salas, N. T. Robert

"The close die forging stress in truncated conical cavities is evaluated with dimensional analysis. Five dimensionless groups are proposed from the process variables in order to simplify the forging stress determination. These groups are experimentally related and graphically expressed. This methodology can be used to predict the actual forging stress in industrial close die forgingThe use of the dimensionless groups allow to comprise more cases than the presented here, provided similar geometries and operational conditions.Introduction.Closed die forging is essentially a plastic deformation inside a two piece mold (forging die) with the inverted shape of the actual forging geometry. This plastic deformation will always be the result of a compressive stress. There are theoretical models which include complex calculations for the analytical determination of stresses (1, 2, 3, 4). Results of these calculations are approximate, requiring generally ulterior tests to obtain the true operational conditions(5).In this paper, it is presented a simplified approach to the actual compression stress needed in the forging. A well known tool in engineering: the Buckingham's Pi theorem in conjunction with dimensionless groups and a working piece scale model is used. Dimensional analysis will give the dimensionless terms needed to experiment with a selected scale model geometry to make the stress determination. The results presented demonstrate the reliability of this methodology."

Jan 1, 1997

By Corby G. Anderson

For over a century, the Sunshine Mine in Idaho has been a major producer of silver. An estimated 335,000,000 troy ounces of silver has been mined. This has established the Sunshine Mine as the largest single source of silver in the world. Because the dominant silver containing mineral is tetrahedrite, a copper and antimony sulfide, normal metallurgical treatments to recover the precious metal are not practical. Thus, over the course of the company's history, novel, hydrometallurgical technologies have been developed on-site to handle complex, precious metal containing materials. Recently, the use of Sunshine technology has been extended to the recycle of secondary materials. As well, the use of Sunshine technology by other organizations for treatment of both primary and secondary feedstocks containing precious and base metals is an area of growing interest. This paper will provide an overview of Sunshine hydrometallurgical technologies including the applicability of Sunshine technology to the recycling of precious and base metals.

Jan 1, 1995

By Wang Jia, Chai Li-yuan, Zhang Jin-Long, Peng Bing, Zhang Qiang

"Electrolytic manganese dioxide (EMD) residue was mixed with shale and fly ash as the main materials to make solidification/sintering brick for the utilization of the residue from EMD production. The effects of sintering temperature, sintering time, solid waste content and cooling process on its mechanical properties and toxic elements solidification were investigated according to compressive strength and leaching toxicity. The results showed that the calcined residue had capability of solidifying toxic metals and exhibited perfect strength after treated in the optimal parameters of EMD residue below 50%, temperature at 1000-1100°C, time3-5h, and semi-quenched at 600°C1 InstructionSolid clay-brick holds the leading position among building materials for a very long time in China. The traditional technique of making clay-brick has the drawbacks of backward process, simple facilities and single product. Since Chinese Reform and Opening-up, urban-rural construction and real estate have been booming with the rapidly development of national economy and science technology. The problems of ruining fertile land, environment contamination and high energy consumption in the traditional technique of clay-brick making have not been solved yet. On the other hand, more than 7 billion tons of industrial wastes are accumulated over years which occupies over 6.7 million hectares filed and causes serious environmental problems[1-31. Strategy present in ""The Chinese Agenda of the 21st Century"" required the production of wall materials less energy conservation, land saving and waste recycling.Coal gangue[4-9l, fly ash[I0- 13l, sludge from waste water treatment and tailings of gypsum, pyrite, copper mine, high silicon containing iron, asbestos and ects [l4-lSJ are the solid wastes used for brick making around the world. There are two kinds of process for brick making, high temperature sintering and low temperature steam curing[19•201. Although the technology of two brick making made great progress and got widely application in construction field, no precedent for preparing sintering-bricks with EMD residue as materials occurred in China because of its complicated processing technics and lack of sufficient practical experience to guarantee the bricks' quality.In this study, EMD residue was mixed with shale and fly ash as the main materials to make solidification/sintering brick. The effects of sintering temperature, sintering time, solid waste content and cooling process on its mechanical properties and toxic elements solidification were investigated according to compressive strength and leaching toxicity."

Jan 1, 2011

By C. H. Bucknam

A review of phase analysis methods used to characterize refractory gold ores is presented. Updating of assay methods using database technology, on-line instrument interfacing and response surface modeling is highlighted. The use of assay results to classify ores for metallurgical purposes is demonstrated.

Jan 1, 1987

By Jian Ye

Recycling of aluminum scrap, such as Used Beverage Container (UBC) scrap is steadily increasing. In secondary remelting of such scrap, it is a common practice to use protective molten salt cover. An appropriate salt protects metal from oxidation, promotes coalescence of the suspended metal droplets, and separates clean metal from the oxide contamination. The molten salt also reacts with metal. This causes metal loss and change of resulting metal composition. In this paper, role of molten salt fluxes in melting of UBC scrap is discussed, and selection criteria for molten salt are provided.

Jan 1, 1995

By P. D. Nolan

Smelters operating under pollution control orders have become increasingly dependent upon the reliable operation of sulphuric acid plants and no factor affects the long term reliability of those plants more than efficient gas cleaning. The sources and characteristics of contaminants in smelter of fgases and the conventional approaches to removing these contaminants to accepted levels are discussed. New technology is described which offers advantages of lower capital cost, lower operating cost and reduced space requirements over the conventional approaches. This new technology has been developed by LAB s.a. and is licensed for metallurgical gas applications by Chemetics International Company.

Jan 1, 1983

By Qingchun Yu, Bin Yang, Yong Deng, Heng Xiong, Fei Wang, Minxiu Chen

"Metal aluminum produced by non-electrolysis process received much attention due to its lower energy consumption. In this paper, carbothermic reduction and carbothermic-chlorination of alumina in normal pressure and vacuum were studied. The products were examined by means of XRD, EDS and SEM. During the carbothermic reduction process using carbon reductant in normal pressure, no metal aluminum was found. However, when coal was used as reductant, a mixture containing metallic aluminum, A14C3, and silicon was obtained, but metallic aluminum couldn't be separated from the mixture. During the carbothermic-chlorination process in vacuum, Al404C and Al4C3 were produced by the reaction between alumina and carbon, and Al Ch gas reacted with Al404C and Al4C3 to produce Al Cl gas. Metallic aluminum was produced due to the disproportionation of A!Cl gas and condensed on the collecting plate. Meanwhile, the initial temperature of carbothermic reduction of alumina reduced in vacuum compared with that in normal pressure.IntroductionIndustrial production of primary aluminum is carried out in alumina cell by the so-called Hall- Heroult process, necessitating the use of very high currents of low voltage. The alumina from which metallic aluminum is gained must be chemically pure, otherwise impure metal results. The main drawbacks of the electrolytic production are its very high energy consumption, the release ofperfluorocarbons, and the high specific C02 emissions [1]. During the past years, there were a lot of attempts to produce metallic aluminum by carbothermic reduction of A1203 [2, 3]. Cox [4] determined the vapor pressure over the A1203-C system and performed X-ray diffraction analysis of condensed products. It was demonstrated that an increase in the carbon content in the system leaded to the sequence of transitions: A1203~Al404C~A1zoc~A14C3 ~AI [5]. In any carbothermic reduction process for aluminum, extremely high temperatures (2000 °C ) were required [6]. In spite of considerable effort, the carbothermic reduction of alumina to aluminum remains a formidable technical challenge, due to the high temperatures required, and to the formation of aluminum carbide and oxycarbide byproducts [7]."

Jan 1, 2013

By Yuanbo Zhang, Zhixiong You, Zijian Su, Bingbing Liu, Guanghui Li, Guang Yang, Tao Jiang

Sodium stannate is widely used in the electroplating and tin alloy industry. But the traditional processes for sodium stannate production are characterized by long flowsheet, high production cost and strict requirement for the equipments, etc. In this study, a novel process for sodium stannate preparation from cassiterite concentrate and sodium carbonate via roasting in CO/CO2 mixed gas then followed by leaching was developed. The effects of roasting parameters on the Sn leaching efficiency were conducted. A Sn leaching efficiency of 77.2% was obtained under the optimal conditions. Sodium stannate (Na2SnO3·3H2O) with a purity of 95.8% was produced by the new process, which is better than that specified for the industrial first-grade product.

Jan 1, 2014

By Feng Liu, Bingji Yan, Zhiwen Shi, Hongwei Guo, Jianliang Zhang

During production of a large quantity of steel, slag is produced at the same time. This paper chooses blast furnace slag (BFS) as the main material for the research. The purpose of the research is to explore its optimal physicochemical properties and the use of BFS in building stone field. The paper elaborates the experimentation process of producing glass-ceramics and presents the results. The results show that SiO2 content in BFS and amount of Cr2O3 and Fe2O3 added as nucleating agents have certain effect on the properties of glass-ceramics. The results also show that the exothermic peak temperature of base glass is the lowest when adding 20% SiO2 to the BFS, and 2% Cr2O3 and 3% Fe2O3 as nucleating agents, which makes easy crystallization and optimal properties of the glass-ceramics.

Jan 1, 2015

By Kaixi Jiang, Lan Li, Bang Wei, Haibei Wang, Yaping Feng

"China is currently the world's largest copper producer. In the last five years, 950 kt/y of smelting capacity was commissioned. Currently, about 1200 kt/y smelting capacity is under construction and about 2000 kt/y smelting capacity is under feasibility study. Ausmelt/ISA smelting and flash smelting technologies were commonly adopted in China. After the double-flash-smelter was first adopted in 2004, three new double-flash-smelters are scheduled. Recently, two new copper smelting technologies were developed in China. One is an improved bath side-blown smelting process, and another is the SK.S bottom blowing process. Both technologies have been in practice for over three years and have achieved good technical performance. Approximately 500 kt/y new smelting capacity in China and India will adopt these technologies. Both technologies have the advantages of low investment cost, low energy consumption and high flexibility for complex raw materials. This paper reviews ""green"" copper smelting projects in China and introduces the practices of the two new Chinese smelting technologies.IntroductionPresently, China is the largest copper producer in the world. As far as the smelting of copper is concerned, there are many smelting processes applied in industrial production, such as flash smelting, Noranda smelting, Ausmelt smelting, Isa smelting, the Mitsubishi process, Vanukov smelting, silver copper-smelting, SKS smelting, both side-blown smelting, traditional blast furnace smelting, electric furnace smelting, reverberatery smelting and so on . Except the last three traditional processes that are eliminated because of their failure to meet the requirements for environmental protection, all of the other above-mentioned methods are advanced smelting processes adopted nowadays."

Jan 1, 2012

By Patrice Chartrand, Halvor Dalaker, Philippe Ouzilleau

A size-dependant thermodynamical model for the carbon-hydrogen previously developed by Ouzilleau et al. [1] has been expanded here to include chemisorption of methyl groups. Gibbsenergy minimalisation calculations using FACTSAGE software on this model indicates that hydrogen bonding through methyl groups is energetically favoured as an intermediate between bonding as monoatomic hydrogen to edge hexagons (which is more favourable) and as monoatomic hydrogen to corner hexagons (which is less favourable). The model has also been applied to methane decomposition and oxide reduction using natural gas. A C-H solid solution as a thermodynamic description of the solid carbon phase influences calculations of carbon activity in metastable methane, and gives different results than when using graphite.

Jan 1, 2015

By Filipe de Menezes Torres, Augusto Pereira de Sa, Itavahn Alves da Silva, Eliana Ferreira Rodrigues, Carlos Antonio da Silva, Varadarajan Seshadri

Top slag eye opening which happens as a result of gas injection is a function of the gas flow rate in addition to other factors such as ladle geometry, porous plug location as well as slag properties. Slag eye opening leads to entrapment of atmospheric nitrogen, oxygen by the steel melt affecting adversely the steel quality. In this work aspects of mixing and eye formation in steel making ladles with inert gas injection have been analyzed through physical and mathematical modeling techniques. Influence of ladle, gas flow rate and distribution and slag properties has been assessed. A correlation for estimating eye opening has been developed. Results from PIV measurements and images of eye opening obtained using a camera have been utilized to validate results from CFD simulation.

Jan 1, 2015