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By Du Sichen, S. Seetharaman, Wei Liu

"The viscosities of two-phase mixtures are of great importance in the modelling of the fluid flow in metallurgical processes. For example, in steel making and refining, the intimate mixing of metal droplets in the slag phase requires a consideration of the effective viscosities for the mixture. The present work was aimed at an understanding the phenomena underlying the viscous flow in a two-phase mixture with widely differing viscosities.Emulsions of silicone oils of known viscosities (345mPa.S and 1010mPa.S at 293K) with small amounts of water evenly distributed in the same were prepared by subjecting the mixture to uniform stirring using a magnetic stirrer. The viscosities of these emulsions were measured at constant temperature by rotating cylinder method using Brookfield Digital Rheometer. The uniformity of the preparation of the emulsions was confirmed by the reproducibility of the results. Th7 measured viscosities were generally found to be independent of the torque under the experimental conditions so that the two-phase mixture could be considered as a Newtonian liquid. The variation of viscosities with temperature and the effect of addition of a surface-active substance were also studied in this work.The measured viscosities were found to be· higher than those of both pure water and silicone oil. The experimental viscosities were found to increase with increasing concentration of water. The influence of surface tension on the viscosities was examined by adding surfaceactive agent to the mixtures. The result is discussed and compared with theoretical models developed by Einstein, Taylor and Oldroyd."

Jan 1, 2000

By G. S. Gupta

To predict the iron oxide concentration a mass transfer model has been developed for an Induction Smelting Process (ISP) in which self-fluxed composite pellets (made of iron ore, brown coal and lime) are melted in a single phase induction furnace in conjunction with top blown oxygen. Transient mass balance equation with complex boundary conditions has been worked out by adopting a relatively new approach known as the cell model approach. These equations have been solved numerically using finite difference technique to obtain the iron oxide concentration profile in the ISP. Numerical and experimental results obtained for iron oxide concentration show a reasonable agreement with each other.

Jan 1, 1991

By Alessandro Blasi, Massimo Morgana, Corradino Sposato, Pietro Garzone, Giuseppe Devincenzis

The rare earth elements are essential for a diverse and expanding array of high-technology applications, which constitute an important part of the industrial economy of the 21st century. As a matter of fact, rare earth has been listed in the category of strategic elements in many countries becoming a core business for international research. Experimental tests have been carried out on a bench scale battery of mixer settler composed of 24 stages, each one with a volume of 150 ml. These trials have been performed at room temperature checked by a micro-climatic control system. The battery was setted in two sections: extraction and scrubbing section. Rare earths concentrations were obtained by ICP-OES analysis made on aqueous phase and on the stripped from organic phase. We obtained a complete separation of light rare earth (La, Ce, Pr, Nd) in two sub-groups: La/Ce and Pr/Nd.

Jan 1, 2014

By Semih Perdahcioglu, Arthur E. Morris

"The curricula for the majority of Materials Science and Engineering programs is devoid of all but the most rudimentary coverage of the principles of material and energy balance calculations. As a result, graduated engineers that need to make such calculations are faced with three unpalatable options. First, attempt to learn the subject by attending workshops or short courses sponsored by corporations or industry groups. Second, outsource the needed work to a consulting engineering company. Third, purchase a software package that's capable of simulating a process. Each of these options require a considerable investment of employee time and effort. The first option might be the best if suitable computational software was readily available. We review the recent development of such software, which is entirely based in Excel. The software tools include a thermodynamic database, tools for multiple computations, and a flowsheet simulation program. These tools employ teaching by simulation.IntroductionPracticing engineers often come up with situations where they must learn a technical subject that they didn't cover in their college classes. One possibility is to obtain a couple of texts on the subject, and delve in. Or, they may sign up for an intensive short course where they can get personal instruction and guidance. But the first option requires a lot of study time, and the second option may not provide the specific instruction (or intensity of instruction) required to appropriately master the subject. Here we look at ways of using simulation techniques to learn the methodology for making material and energy balances on industrial processes.Industrial heating processes have undergone many changes over the past dozen years, as vendors have introduced new heating equipment designed to recover the greatest possible amount of heat from the fuel, and to meet stringent environmental challenges for emissions (especially NOx). Even though the recent unprecedented drop in price of natural gas may have altered the urgency for improving a plant's energy efficiency, the need is still there. Until recently, there was a dearth of readily-available software for process engineers to use for simulating a plant's flowsheet. The good news now is the existence of several Excel-based software tools that make the calculational process much easier. [ 1]. Plant engineers may also be interested in a DOEsponsored program[2] which allows plant-wide and ""what-if' analyses of the energy balance."

Jan 1, 2013

By Emil H. Geus

A process has been developed to recover aluminum from dross which does not require the use of salt flux as commonly employed, This results in a salt-free residue which has potential industrial uses or alternatively can be safely land-filled. The dross is first heated by an air-fuel or oxy-fuel burner in a sealable rotary furnace. At a suitable temperature the burner is turned off and the temperature of the dross thereafter controlled by means of an atmosphere of oxidative and inert gases. When the free metal has agglomerated it is first discharged from the furnace, followed by the residues.

Jan 1, 1995

By Xiang-ning Meng, Miao-yong Zhu

"A three-dimensional finite-element heat-transfer model is conducted to predict temperature of hot copper plate in a slab continuous casting mold and the effect of casting speed on temperature difference between copper plate and solidifying shell is simulated in combination with process data. The results show that centre temperature of hot copper surface at casting speed 1.8 m·min-1 and 2.0 m·min-1 are higher than that of 1.6 m·min-1 casting speed 4.7-5.2 °C and 11.2-12.2 °C respectively and temperature is not increased linearly with casting speed. Temperature difference in meniscus between mold and shell is influenced obviously by casting speed and increased 4.0- 6.0 °C with increment of casting speed 0.2 m·min-1• Fluctuation of temperature difference in meniscus is a main reason to deteriorate casting quality as increasing casting speed.IntroductionIn conventional continuous casting of steel, a large amount of sensible and latent heat of molten steel dissipates in primary cooling zone and mold becomes a critical component of caster to govern steel quality, meanwhile, thermal load on mold is increased constantly and environment is also more abominable since high productivity and quality are required and high-effective technologies are applied. So, an in-depth understanding of thermal behavior of mold at high casting speed is essential to design cooling structure and maintain casting stability. Many studies have been carried out to shed light on thermal behavior in mold. Chow et al. [l] applied a mathematical model to heat transfer in billet mold at a high casting speed to give a new taper in order to minimize mold-strand interaction. Thomas et al. [2] researched relation between mold geometry and temperature distribution based on a finite-element heat-transfer model. Lu et al. [3] indicated that slab mold temperature are mainly affected by thickness of copper plate and nickel layer by a heat transfer model. Samarasekera et al. [4, 5] researched temperature of copper plates for both billet and slab molds and effect of a large number of factors ranging from water quality to casting speed. Park and Thomas et al. [6, 7] developed a finite-element thermal-stress model to determine temperature and thermal distortion and stress in both thin and slab molds and O'Connor et al. [8] applied an elastic-plastic-creep finite-element model in a funnel shaped mold to achieve same goals. Cicutti et al. [9] evaluated heat transfer and temperature fluctuation in a slab mold and proposed an expression to predict global heat flux as a function of process parameters and an index to quantify thermal instability. All mentioned above shown that thermal behavior is not only important to casting stability, it is also premise to further understand mechanical behavior in mold."

Jan 1, 2011

By S. Illendula, B. Q. Li, R. A. Mirshams

"An integrated mathematical model is developed to represent the thermomechanical behavior of the materials and microstructure evolution during metal forging. The model development is based on the finite element solution of the thermoviscoplastic deformation of metals coupled with the internal state variable model describing the microstructure evolution involving work hardening, recovery, recrystallization and grain size distribution. The procedures for the integration of the microstructure model into the macro finite element model are described. Computed results for both macro and micro phenomena during metal forging, such thermomechanical deformation such as velocity field and effective strain rate and materials characteristics such as distribution of grain size and recrystallization volume fraction, are presented.1. IntroductionThermomechanical behavior and material microstructural evolution are two critical, interrelated aspects associated with metal workpiece undergoing large plastic deformations such as encountered in forging processes. In much of the modeling work up to date, these two aspects have been addressed separately. Die designs and forging processes are investigated using finite element based thermomechanical models while material dynamics during forging is studied, more often than not, as a separate subject. For many industrial applications, especially those involving novel, light and high strength materials, it is critical to combine these two aspects into a single, integrated model so that materials dynamics and thermomechanical deformation during forging processes can be considered simultaneously [1], thereby providing required information for intelligent process design and optimal process control."

Jan 1, 1998

By Baokuan Li, Fang Wang

"Comparing with the single electrode in electroslag remelting processes, two series-connected electrodes have the advantage of little inductance, lower power consumption and higher melting rate, which was widely used to produce superalloys and specialty steels. Detailed understanding of the electromagnetic field distribution is essential for both improving ingot quality and saving electric energy. In the present work, a 3D finite element model was developed for the magnetic field, electromagnetic force, current density and Joule heating field of electro slag remelting processes (electrode, slag and ingot) with two series-connected electrodes using Maxwell equation, Lorentz law and Joule law. The results show that the maximum current distribute occur at the middle of electrode, due to the interaction of selfinduced and mutual-induced of two series-connected electrode; associated magnetic flux density on the inner side of electrode increase and the outer decrease; The maximum joule heating is at the interface of slag and electrode. The parameter study shows that if the current frequency is greater than 35Hz, the current density in inner electrode tend to linear distribution; with the increasing of original current, The maximum current density near the wall in electrode will increase linearly; with the increasing of electrode innnersion depth and decrease of slag cap thickness and the maximum of the joule heat in slag will increase.IntroductionElectroslag remelting processes(ESR) are widely used to produce superalloys and specialty steels [l-3l_Two pair, four pair or six pair electrodes in electroslag remelting processes is common in casting large scale ingot, which has the advantage of little inductance, lower power consumption and higher melting rate, comparing to singe electrode. They have the same essence with two electrodes in ESR.Compared to the single electrode ofESR, the other electrode is added which can decrease the reactive resistance and power consumption in the two electrodes of ESR. It is a complicated metallurgy process with a series physical and chemistry phenomenon from the molten of steel to the solidification of ingot [4-71_ These physical and chemistry phenomenon originated the effect of alternating current of high intensity. The rule of the alternating current of high intensity which revealed the law of physical and chemistry phenomenon in ESR is the precondition of improving ingot quality and saving electric energy. Jihe Wei and Yongli Ren[S-9lstudied the distribution of electromagnetic field in single electrode ofESR with Maxwell equation and relative electromagnetic theory. It had the limitation that take the electrode and mold as infinite conductivity. A detail analysis of Electromagnetic fields in ESR had been conducted by Patel A D [JO-llJ using general stream-function formulation. It is difficult to extend to three dimensions which could not be used widely. Daniel V [lZJ and Kharicha A [BJ only analysis the current density associated magnetic flux density field and temperature field without the whole irlformation of electromagnetic field. Maopeng Geng [l4J considered the current density and temperature field of the real and fake electrodes in ESR without skin effect. As to the complication of the two electrodes of ESR, it is rarely reported the electromagnetic field and Joule heating field of the two electrodes in ESR. The rule of effect of electromagnetic and modification of numerical simulation should be studied in depth."

Jan 1, 2011

By D. E. Larson

The U. S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By Andrew L. Puwis

Methodologies were presented for computing the thermal gradient associated with single crystal solidification in macroscopic computer modeling. The. heat transfer, and solidification of a shaped investment casting model were simulated using properties from three different alloys. Following the simulation of solidification, the resultant thermal gradients (G) and rates of solidification (R) from representative points were extracted in various ways and compared: It was discovered that alloy properties have a strong influence on the computed thermal gradient and rate of solidification for the three methods investigated. Data also showed that the computed gradient for each model was very different depending on the temperature range used to compute these values.

Jan 1, 1994

By Nourreddine Menad

Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount to 30 percents of the scrap mass. Generally, they are treated with flame retardants such as halogenated ones and they can result in different toxic chemical compounds. These plastics can be used as combustibles in the recovery of copper and precious metals. However, during their combustion, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. The estimated thermodynamic data of several organic compounds resulting from combustion of electric and electronic scrap, have been used in conjunction with the program HSC to calculate the conditions for dioxin and furan formation. The results show that the formation of the dioxins is dependent on the quantities of carbon, hydrogen, chlorine and oxygen reacting in a given system, as well as on parameters such as temperature and pressure.

Jan 1, 1998

By Elliot Schwartz, Julian Szekely

"In this paper we describe an experiment that was recently performed on the IML-2 Space Shuttle mission in which the thermophysical properties of molten metals were measured using electromagnetic levitation. In the planning of these experiments calculations had to be performed to predict the levitation and stirring forces, heating rates, sample deformation, and internal flows within the sample. These predictive calculations were essential for both the planning of the experiments and for the re-planning of experimental runs during the actual Space Shuttle mission.Introduction""Materials Processing in the Computer Age"" involves the use of mathematical modeling to obtain a quantitative understanding of the phenomena that govern materials processing operations. Microgravity, or space shuttle experimentation represents a specific case in point here; the very high cost of the space shuttle flights, the very limited flight opportunities that are available, and the tight resources aboard a shuttle clearly mandate that these experiments be very precisely planned and that all possible opportunities for mathematical modeling be fully exploited.The purpose of this paper is to present the results of calculations performed for the planning of a space shuttle experiment involving electromagnetic levitation and wherever possible present a comparison of the computational predictions with both experimental measurements and asymptotic analyses. Finally we shall seek to discuss the practical implications of both the computational methodologies and the potential experimental findings."

Jan 1, 1994

By S. K. Utimurd, D. C. R. Espinosa, J. A. S. Tenório

"Waste Electrical and Electronic Equipment (WEEE) has become an environmental issue due to technological advance and waste plastic is one of the main polluters. The excessive discard of these plastics result in a difficult to dispose it to landfill and need further separation with technique in order to produce high added value plastics. There are many kinds of plastics in extensive use at the present time and the co=on are the acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS) used in the production of electric appliances. These plastics are difficult to separate because they have similar densities. Flotation of plastics is one possible separation technique and using selective wetting agents. The separation may be possible given close control at particle size and the concentration of the reagent. The process was able to produce a concentrate of HIPS with at least of 93% purity and a concentrate of ABS with 99% purity.IntroductionThe current situation of municipal solid waste (MSW) management especially in emerging economies like Brazil, the growing population and economic activity will result in a significant increase in the generation of waste in the coming decades. It is worthwhile to review and update the sources, amounts and recovery technologies of specific materials from waste, particularly from municipal solid waste (MSW).The growing impact of the current waste management practices stresses the need for a change in how waste is handled. The 2012 survey and the Brazilian Association of Public Cleaning and Special Waste Disposal Companies (ABRELPE) reports the generation of 62 Mt urban MSW in that year, which is an increase of 13% compared to 2011. It has been reported that in Brazil about 90.17% of the generated MSW is currently collected, which indicates an increase in the coverage of collection services compared to 2011 [ l]."

Jan 1, 2014

By K. R. Robilliard

Ausmelt Technology has been developed to process copper concentrates containing significant levels of lead, arsenic and antimony. A process was developed aimed at smelting these concentrate materials to remove the contaminants to fume and produce a clean copper product. The production of clean copper and the potential economic benefits of this process step over the sale of impure concentrates is discussed.

Jan 1, 1995

By Gus Van Weert

The cost of oxygen is a major and common factor in the hydrometallurgical processes developed or proposed tor the oxidation of refractory pyrites. This cost involves charges for the generation and the transfer of the 02 to the mineral slurry. Bio-oxidation faces considerable design demands which require large scale equipment to be resolved. Nitric acid assisted oxidation offers low cost oxygen units; this method of pyrite oxidation deserves a closer look for large scale plants treating pyritic gold ores and concentrates.

Jan 1, 1990

By R Bartlett

Process engineering-science originally developed for percolation leaching of ore in heaps is extended to the decontamination of unsaturated soil, either in situ or after excavation and emplacement as a soil heap on an impervious pad. Phenomena considered include: soil matrix porosity and permeability; percolating solution retention, capillarity and flow; washing sweep efficiency; optimum solution application rates during leaching; soil agglomeration to improve soil permeability and soluble contaminant transport by diffusion in soil agglomerates. Practical aspects briefly discussed include leach pad construction, solution distribution and recovery from the soil, and solution containment.

Jan 1, 1994

By Srinath Viswanathan, Adrian Sabau

"In general, the occurrence of microporosity during metal casting is due to the combined effects of solidification shrinkage and gas precipitation. The governing equations for fluid flow and hydrogen evolution indicate that porosity formation and fluid flow are strongly coupled. However, in most studies on microporosity, it is considered that the porosity formation does not influence the fluid flow in the mushy zone. In this study, a computational methodology is presented for the numerical simulation of interdendritic fluid flow and microporosity evolution. The solution algorithm presented includes a fully coupled, implicit treatment of microporosity and local pressure in the mushy zone. The effects of microporosity evolution due to the local pressure drop in the mushy zone, and pore expansion in casting regions where liquid feeding alone cannot compensate for the solidification shrinkage are also considered. It is shown that neglecting the effect of porosity formation on the pressure in the mushy zone yields higher pressure drops. By its growth, microporosity partially compensates for the solidification shrinkage, reducing the feeding demand. A reduced feeding demand requires less fluid flow to compensate for solidification shrinkage, and results in smaller pressure drops in the mushy zone. Therefore, in order to accurately describe casting defects, comprehensive models of fluid flow, heat transfer, and solidification must include the effect of microporosity as well.IntroductionIn the terminology commonly used by foundrymen, porosity is usually considered to be either ""hydrogen"" or ""shrinkage"" porosity. Hydrogen porosity is the term given to porosity that is generally rounded, isolated, and well distributed. Porosity that is interconnected or clustered, and of an irregular shape corresponding to the shape of the interdendritic region, is usually termed shrinkage. In general, the occurrence of microporosity in aluminum alloys is due to the combined effects of solidification shrinkage and gas precipitation [1]. Continuum models [1, 2- 7] have been used to predict the level of porosity in castings. A number of other studies have also attempted to understand the phenomena of porosity formation and pore growth [8-10] and pore morphology [11].The governing equations for fluid flow and hydrogen evolution indicate that porosity formation and fluid flow are strongly coupled. However, in most studies [4, 9, 10], it is considered that the porosity formation does not influence the fluid flow in the mushy zone. Kubo and Pehlke [3] presented a methodology for the prediction of microporosity distribution in shaped castings by considering the effects of both the hydrogen precipitation during solidification and the pressure drop in the mushy zone. In their approach, the local pressure and porosity were computed in an uncoupled manner based on a ""flux of interdendritic liquid"" criterion, i.e., either pressure or porosity was first computed using the other variable at the previous time step. Their approach has been used with little change in numerous studies [6, 12, 13]. Recently, Kuznetsov and Vafai [14] presented a fully coupled, one-dimensional model for the computation of pressure and porosity. They showed that neglecting the effect of porosity formation on the pressure in the mushy zone yields higher pressure drops and an over-prediction of final porosity. They also showed that the influence of porosity formation on the pressure is larger at lower pressures in the mushy zone."

Jan 1, 2001

By Lv Guozhi, Niu Liping, Liu Yan, Zhao Qiuyue, He Jicheng, Zhang Ting’an, Dou Zhihe

"This paper proposed a new method of Mg and Cl2 circulating for titanium sponge production by direct pyrolysis and thermal reduction process. Effects of pyrolysis temperature, pyrolysis time and partial pressure of oxygen on pyrolysis efficiency were researched, and the crystallite structural transformation of MgO productions at different pyrolysis temperature and time were analyzed by XRD. The experimental results indicates that the pyrolysis temperature and time effects the pyrolysis efficiency obviously, and the reasonable pyrolysis conditions by using MgCl2 in molten state are as follows: the pyrolysis temperature is 1100?, pyrolysis time is 60min and the partial pressure of oxygen is 100%, the pyrolysis efficiency get above 95% at this conditions. The dynamic analysis of molten magnesium chloride pyrolysis reaction shows that, as a chemical reaction process control, the response of the apparent activation energy Ea=70.4 kJ/mol.IntroductionTitanium is a young metal, it is applied in industrial until the Second World War. It is 160 years from the discovery of titanium to the industrial production of ductility titanium by magnesium reduction method in the United States in 1948. As a new kind of metal, titanium and titanium material are better than the traditional metal materials in mechanical properties, heat resistance and thermal conductivity. Titanium is a kind of landmark structure and function material, which is called “space metal”, “Marine metal”, “Intelligent metal” [1-3]. Although the study of new methods of titanium melting get more at present, Kroll method and Hunter method are really applied to industrial production methods for titanium smelting, and Hunter method is already discontinued because of costs at present. The core technology in Kroll method of sponge titanium production process can be ome down to two circulation, namely the cycle of magnesium and chlorine in preparation-process of titanium sponge. In the traditional Kroll method, the cycle is realized through magnesium chloride which is produced by the electrolytic magnesium reduction process in hot molten state. But because investment of equipment for electrolysis method is too high, this method has not been used by most titanium sponge production enterprise in China. At present most titanium sponge production enterprise in China produce titanium sponge by the outsourcing of titanium tetrachloride, but the main disadvantage of this method is that the by-product of magnesium chloride is difficult to deal with."

Jan 1, 2012

By G. Cifuentes

The kinetics of the electrolytic oxidation of cyanide to cyanate on PbO2-coated stainless steel anodes have been studied by both experimental and theoretical means. The anodes were based on 316 steel and performed in a satisfactory fashion. The pH of the studied KCN solutions exhibited a constant value about 11. Values for all the kinetic parameters have been determined and a mechanism for the studied reaction is proposed.

Jan 1, 1999

By K. G. Wang, M. E. Glicksman, P. Crawford

"We formulate the mathematical solution to late-stage multi particle diffusion in finite systems. The transition from finite system behavior to that for an infinite system is established. Large-scale simulations are reported regarding the dynamics of phase coarsening. Even in the case of a small volume fraction (Vv = 10-4), the particle size distribution is broader than that for the well-known Lifshitz-Slyozov limit at zero volume fraction. We also report the first simulation studies of extremely low volume fraction, for which corresponding experiments, as well as other simulations, do not exist at present for comparison. However, in the case of moderate volume fractions (Vv = 0.1), the fiucutations in the volumetric growth rate of particles are extracted from our simulations. These simulations provide additional insight into the statistical nature of diffusion interactions, including multiparticle stochastics during microstructural evolution.IntroductionPredicting microstructure evolution in alloys remains one of the cornerstones of materials science. Phase coarsening is a common process in microstrucural evolution that leads to a decrease in the excess total interfacial energy of the system. The system typically consists of separate and identifiable units, or domains, such as second-phase particles distributed in a matrix. During phase coarsening, larger particles grow at the expense of small particles. Over time, this ""competition"" results in an increase in the average size of the particle population, and in a concomitant decrease in the number of particles.Particle size and microstructure of many cast alloys depend on similar coarsening processes. Indeed, properties of these materials, such as strength, toughness, ductility, and electrical conductivity, depend on the material's average particle size and particle size distribution (PSD). Understanding and controlling microstructures in two-phase systems are clearly of widespread technological importance."

Jan 1, 2001