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By F. Z. Utyashev

The present work considers the essence of fragmentation: on the level of a simple model as a material response to the curvature accumulated by it at large deformations. It is on this basis that the correlation between curvature and fragment sizes is determined. It is shown that at deformation the area of curvature center inevitably changes. It is revealed that a specific value of variation of center surface area, i.e. ^As parameter, is numerically equal to the value of curvature acquired by a material. Minimum sizes of fragments and grains depending on ^As have been estimated, and the dependence of this parameter on strain has been established. Besides, the present paper considers the effects exerted by curvature center geometry, material distortion, directions of deformation and thermal warming up in the localization zones on structure refinement when various techniques are applied.

Jan 1, 2006

By Thomas Prietl

The use of gas stirring systems through the furnace bottom is common for anode and holding furnaces in the copper industry The first implementation of a gas stirring COP KIN® system in a Peirce-Smith converter was performed at the New Boliden smelter, Rönnskar, Sweden. In addition to other benefits, a decrease in process time and a decrease of the oxygen content in the blister copper were observed. To determine the effects of the gas stirring system and the process endpoint, an optical production control ?Semtech OPC system? was used. The light emission of the converter flame as an optical process parameter provides qualitative on-line process information, and is also used for endpoint determination of the slag making process, on-line control of iron content in white metal, quality control of slag etc. The results, benefits and risks of using the COP KIN® and OPC system for a Peirce-Smith converter are reported.

Jan 1, 2005

By Tianjiao Luo

The electroless copper plating process for continuous carbon fiber using CuSO4?5H2O as the main salt and formaldehyde as reducing agent was experimentally studied, including the effects of pH values and concentration of chelating agents, stabilizing agents and reducing agent on the electroless plating process. The surface morphology and the composition of coating were investigated by means of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), and deposited the coating thickness was measured by way of dissolution. The results indicated that the pretreatment of carbon fiber before plating was so important. This pretreatment could prevent the formation of the black cores, furthermore, it could form many active absorption cores with Ag as the center on the carbon fiber surface. Used the optimized parameters in this process, which led to a stable solution for plating, a homogeneous copper coating was conducted with the carbon fiber plated with favorable mechanical performance and high adhesion strength.

Jan 1, 2006

By Yuanbo Zhang, Yingming Chen, Zijian Su, Bingbing Liu, Guanghui Li, Tao Jiang

High calcium type tin, iron-bearing tailing is recognized as one of typically complex iron ore resources in China. A process of magnetizing roasting process followed by magnetic separation was used to utilize the tailings in our previous paper. Under the optimal conditions, qualified magnetic concentrates were obtained and could be used for direct reduced iron production. In this study, the phase transformation of these tailings during the magnetizing roasting process was investigated. And the reaction behavior between calcium oxide and iron oxide was revealed by using XRD, TG-DSC, VSM, etc. The results indicated that calcium ferrite was easily formed under CO–CO2 atmosphere, which has an unfavorable effect on the separation of iron and tin oxides from the tailings.

Mar 1, 2017

By A. Martins, L. Goulart, E. Araujo, R. Batista, A. Costa e Silva

Steel cleanness is of great importance to the performance of almost all steel products. From very clean steel for bearings to long products used in civil construction, processing variables – in special those in steelmaking operations- must be properly balanced to achieve adequate cleanness for the desired performance. With the present complexity of steels as alloy systems, it is not efficient nor appropriate to develop these processes on empirical basis alone. Computational thermodynamics can greatly improve process development to achieve the desired cleanness level at reasonable costs. In this work, examples of these calculations and their applications to real steel processing are presented and discussed. The advantages, limitations and areas in which improvement in these calculations is desired are highlighted and discussed.

Jan 1, 2015

By Dengfu Chen, Huabiao Chen, Yunwei Huang, Mujun Long, Youguang Ma, Lintao Gui

In the current work, a three-dimensional model coupling turbulent flow, heat and solute transport was developed to investigate the solute transport and redistribution in the mold of slab continuous casting where the Reynolds number is very high and the molten steel flows strongly. The conservation equations of momentum, energy and species for a multicomponent system which includes solute element C, Si, Mn, P, S were solved with the commercial software ANSYS Fluent. The parameters used in the model are based on the actual continuous casting. The fluid flow, temperature distribution and solute elements distribution were analyzed. Results showed that negative segregation occurred near the strand surface, and the species concentration reached a peak value at the solidification front during solidification. The segregation degree of solute element S is higher than the other solute elements because of its lower equilibrium partition coefficient. The species concentration in the liquid pool is homogeneous because of the turbulent flow effect.

Jan 1, 2015

By B. Q. Li, S. P. Song

"This paper describes an on-going research on developing coupled boundary element and finite element algorithms for the solution of thermal and electrodynamic problems relating to materials processing. The coupled methods are uniquely suitable for field problems involving composite regions, in which detailed information on field distributions within one particular region is of more interest and yet the solution can be obtained only if the effects of other regions are all considered. Problems of this type include heat transfer in multiple regions and also magnetic induction involving an infinite boundary. The hybrid boundary and finite element formulation, algorithm development and the applications are discussed. Two examples are given to demonstrate the capability and accuracy of the coupled algorithm for heat transfer problems. Various treatments of corner discontinuity are discussed. It is found that the double flux treatment is an ideal choice amongst those tested as it is easy to implement and also gives the most accurate solution. 1. INTRODUCTIONElectrodynamic and transport problems occur frequently in materials processing systems. Accurate solution of these problems is of great importance not only for our fundamental understanding of physical principles governing these phenomena in the processing systems but also for optimization of the existing processes as well as development of new processes. For this purpose, many numerical algorithms have been developed. These computational schemes in general can be classified into three categories, that is, the finite element and finite difference schemes and the boundary element scheme. The former two are domain based numerical algorithms while the latter the boundary-based algorithm.The finite element method, which is based on the variational calculus, is a very useful and yet popular engineering numerical method for boundary value problems defined over irregular boundaries. The use of the method requires the discretization of the entire domain. It can be applied to solve both linear and nonlinear problems, but is particularly powerful for nonlinear problems that involve the field variables defined within the computational domain. On the other hand, the boundary element method, with its root in the Green's function method, is very efficient for linear boundary value problems or nonlinear problems that involve field variables only along the boundaries. The primary advantage of the boundary element method lies in the fact that only the boundaries of the computational domain need to be discretized, and hence the dimension of the problem is reduced by one, compared with the finite element method."

Jan 1, 1994

By A. Patti, S. Reutzel, D. M. Herlach, L. Ratke, I. Egry

Cu-Co shows a metastable miscibility gap in the region of the undercooled melt. Undercooling of the melt below the binodal leads to separation of the melt into a Co-rich LI-phase and a Curich L2-phase. Experimentally, undercooling into the metastable miscibility gap is realised by means of electromagnetic levitation (EML), processing in drop tube (DT) and by melt flux embedding. As undercooling is large in these experiments, the velocity of the solidification front is high and the microstructure is frozen in instantaneously. Samples have been undercooled and solidified in the TEMPUS-facility (container less electromagnetic processing under weightlessness) during parabolic flight under reduced gravity conditions. Microstructures of solidified samples have been analysed and compared to those processed under gravitational conditions. The influence of convection on phase growth is much lower in reduced gravity. The microstructure shows spherical droplets of the minority phase, statistically dispersed in the majority phase.

Jan 1, 2004

By Aichun Zhao, Rui Wang, Yihong Li, Yanping Bao, Yafeng Ji, Jiansheng Liu, Xiao Hu, Qingxue Huang

The slag entrapment under different conditions of 80t blowing argon ladle furnace was investigated by physical simulation. The water was used to simulate liquid steel and liquid paraffin was for slag. The processing of slag entrapment under different blowing structures was analyzed and the critical velocity and critical droplets diameter of describing it was obtained. Based on the experiments, the relationship between the interface flow velocity and the critical blowing rate CBR was deduced. In the real process, it is suggested that the bottom blowing rate is from 40 L/min to 180L/min when the interface tension is 0.12~1.2 N/m during the soft argon blowing.

Jan 1, 2016

By Xiaodi Huang, Matthew Andriese, Zheng Zhang, Jiann-Yang Hwang, Zhiwei Peng

"A simplified finite-difference time-domain (FDTD) algorithm for modeling microwave propagation in magnetic dielectric materials was developed and employed to study the microwave dissipation in magnetite. Heat transfer during microwave heating of magnetite was subsequently investigated by solving heat transfer differential equation using explicit finite-difference (EFD) method. It is observed that temperature of magnetite surface increases rapidly in the first minute due to the rapid strength decays in both electric and magnetic fields within a short distance along the path of microwave dissipation. A temperature peak, initially formed at the surface of the sample slab, migrates inward as heating time extends and microwave power increases.IntroductionAs one of primary materials in iron and steel industry, magnetite exhibits excellent microwave absorption capability, which leads to great energy conservation in microwave assisted steelmaking [1,2]. The fast temperature increase in microwave heating of magnetite can be attributed to both dielectric and magnetic losses [2]. Although much experimental work has confirmed this observation, detailed computational studies for modeling of microwave field dissipation in magnetite at commonly used frequencies, such as 915 MHz, has not been well addressed [1,3].Finite-difference time-domain (FDTD) method is widely used in computational electrodynamics modeling to simulate the dynamics of electromagnetic wave scattering from various media [4,5]. This approach requires modeling algorithm to be formulated with integration of specific characteristics of each medium. An extensive literature survey indicates that current formulations are only suitable for modeling electromagnetic waves propagating in normal dielectric lossy materials [5,6]. Since magnetite is a magnetic dielectric material in which both dielectric and magnetic properties contribute to the heating process under microwave irradiation, a specific algorithm should be developed for the simulation."

Jan 1, 2012

By Yun Soon Han, Joo Hyun Park

Indium (In) solubility in the FeO-SiO2-Al2O3-5%CaO slag was measured under p(O2)=10¯¹¹ atm at 1573 K to clarify the dissolution mechanism of In in FeO-bearing metallurgical slag. The In solubility increased with increasing oxygen partial pressure, whereas it decreased by increasing the activity of basic oxide, viz. FeO. Thus, a dissolution mechanism of In in the FeO-SiO2- Al2O3-5%CaO slag was described by the following equation. In(s)+1/4O2(g)=(In+)+1/2(o2-) The enthalpy change of the In dissolution reaction was negative, indicating that the dissolution reaction was an exothermic reaction. This is consistent with the above reaction mechanism.

Jan 1, 2014

By Shigehito Deki

"A new wet process has been developed for the synthesis of various kinds of oxide thin films on various kinds of substrates, even which have complex surface morphology, from aqueous solution. The process was named as the LPD, Liquid Phase Deposition, method, which has some advantages over the conventional dry processes. This process can be applied to an on-site synthesis of advanced materials in the thin film technology. In this paper, some current topics on the synthesis of the composite thin oxide films by the LPD method, are presented.IntroductionGenerally, metal oxide thin films have been made by different preparative processes such as r.f. sputtering, chemical vapor depositon, CVD, laser ablation and sol-gel method, etc [1-3]. Each method has it own advantages and disadvantage. In some cases, the process is not suitable for the preparation of thin film on substrate with large surface area or complex surface morphology, and makes the deposition apparatus complicated and expenisve. By using Liquid Phase Deposition, LPD, method which overcomes some of those problems, metal oxide or hydroxide thin film can be formed on the substrate with large surface area and complex surface morphology, which are immersed into the aqueous solution only at ambient temperature and under atmosphere without any special equipments and high energy. And also, multicomponent oxide thin films can be formed readily by mixing solutions containing the objective metal ions, because it is performed in the aqueous solution which is typically a homogeneous mixing system. This process utilizes ligand-exchange, hydrolysis, equlibrium reaction of metal-fluoro complex species, MF x (x-2n>-, and F consumptive reaction. In the aqueous solution, MFx<x-2n>-is hydrolyzed with water to release F ions by a ligand exchange equilibrium reaction as following;"

Jan 1, 2000

By G. Coryell, S. Blaskovich

"A computer model has been developed to simulate the flash furnace and converter operations at the ASARCO Hayden Copper Smelter. The focus of the modeling was to optimize the converter operation to eliminate high matte level episodes in the flash furnace. These episodes (reducing feed to the furnace) resulted from the lack of converter operation scheduling. The model provided ""what if?"" scheduling scenarios that led to increased efficiency of the converter and flash furnace operations.This paper discusses alternatives studied to optimize the converter operation and the development of the computer modeling program, including implementation of the project. The discussion details the results of the project including the conversion from batch to a real time converter scheduling process. IntroductionASARCO's Hayden Smelter consists of a fluid bed drying system, an Inco oxygen flash smelting furnace, Peirce Smith converters, two anode furnaces and two casting wheels, gas cleaning plant, 2800 stpd sulfuric acid plant, 650 stpd oxygen plant and 200 gpm water treatment plant. The process flow sheet of the plant is shown in Figure 1.Over the past several years, the Hayden smelter has been involved in productivity improvement and cost reduction programs. This has been necessary to become a low cost copper producer in today's market. Part of the productivity improvement program was the use of process control to streamline the flash furnace and converter operations. Process control, through the use of computers and electronic controllers, has played an increasingly important role in optimizing processes in the Hayden Plant since the startup of the Inco flash furnace in 1983."

Jan 1, 1989

By Svetlana Nikitina

While many question "sustainability" as an intellectual field on the grounds that it is too broad and "undisciplined," we are able to achieve a good balance between breadth of coverage and depth of inquiry in our team-taught seminar "The Grand Challenges: Sustainable Development for the 21st Century" offered to first year students at Worcester Polytechnic Institute. We strike this balance between breadth and depth by a) problematizing key sustainability issues in class discussions; b) by explicitly exploring the lenses of different disciplines (the historical context, the scientific facts, the engineering interventions and the philosophical foundations of unsustainable behaviors); and c) by offering our students opportunities to pursue a targeted project on specific sustainability issues (vertical gardening, metals recycling on college campus) through which they gain depth of understanding as well as practical exposure to all components of the problem, which puts them on the path of seeking effective solutions.

Jan 1, 2010

By J. N. Kondo, M. Hara, T. Smida, N. Ooto, K. Domen

"A porous material composed of two-dimensional anionic sheets of a layered perovskite, KSrNb30 10, was studied as photocatalyst for the production of Hz in the presence of alcohol sacrificial donors. Colloidal single and multi-layered HSr2Nb30 10 sheets were formed by intercalating ietra(n-buthylammonium) cations into the interlayeres of H+-exchanged KSr2Nb30 10 (HSr2Nb30 10), and addition of HN03 solution to the colloidal suspension precipitated the porous materials in which HSrNb30 10 sh~ets rand~mly stuck together. Original HSr2Nb30 10 before exfoliation had a BET surface area of 1 m2 g-1, whereas the surface area of a porous material prepared under optimal conditions exceeded 100 m2 g-1. The porous HSr2Nb30 10 had considerably higher photocatalytic'activitie8 for oxidation of 1-propanol and 1-buthanol than HSr2Nb39io, indicating that in the porous materials many niobate sheets are available for decomposition of these large alcohols.IntroductionQuite a research effort has gone into the design and study of porous materials. Such materials with large surface areas would have applications in highly efficient adsorbents or catalytic reactions.We have been studying photocatalytic reaction by cation-exchangeable layered metal oxides, where alkali metal cations are intercalated into the interlayers of inorganic sheets.[1,2] There are several advantages to using layered compounds rather than bulk powders for photocatalysis. Layered compound is rich in variety, in addition, modifications of them are easily performed by exchanging alkali metal cations in the inter layers for H + or other metal cations. The most important advantage is that some layered compounds have considerably high photocatalytic activities than bulk catalysts because the electrons and holes generated in each thin inorganic sheet readily reach interlayer spaces as reaction sites at the illterlayer spaces. It should be very important for further improvements· of layered photocatalysts to utilize two-dimensional inorganic sheets effectively."

Jan 1, 2000

By David Dreisinger

The cyanidation of copper containing gold ores results in the co-dissolution of copper along with gold. Copper dissolution results in elevated cyanide consumption that may make the treatment of the gold ore uneconomic. Copper-cyanide species in gold mill effluents may increase the environmental toxicity of the gold mill solutions. The objective of this study was to examine the use of solvent extraction to recover the copper cyanide species from gold mill effluents. Solvent extraction with Cognis (formerly Henkel) reagents LIX 79 and LIX 7950 was studied. Excellent extraction of copper and cyanide was achieved using pH control in extraction. Copper and cyanide may be stripped from the reagents using basic eluants. Various routes for copper and cyanide recovery from the strip solution were studied. Excellent results were obtained using electrowinning in both divided (Nation membrane) and undivided cells. Cyanide recovery was obtained by AVR treatment of a bleed stream from electrowinning. Full results of solvent extraction, copper and cyanide recovery are reported.

Jan 1, 1998

By Xiaolong Lin, Jianhui Peng, Zhongping Zhu, Guanghui Li, Zhizhong Li, Zhiwei Peng, Tao Jiang

As the absorbing material composed of sole carbon is difficult to meet the comprehensive requirements of microwave applications, preparation of carbonaceous nanocomposite materials becomes an effective method to increase microwave absorption properties. In this study, a novel nanocomposite composed of Co–Ni ferrite and graphene was synthesized via a simple and rapid microwave hydrotherma method in just a few minutes It was demonstrated that the minimum microwave reflection loss of the composite of 3 mm thickness with a low filling ratio (20 wt%) reached −13.1 dB at 17.2 GHz with an effective absorption bandwidth of 3.1 GHz. The good performance of the composite was believed to be a result of high dielectric loss of graphene associated with a multi-dielectric relaxation process and magnetic loss of the ferrite mainly originated from natural ferromagnetic resonance.

Mar 1, 2018

By Sheng Dai, Yuan Lee, Haiming Xiao, J. P. Young

"There are numerous analytical applications of scatter-emission and/or absorption spectroscopy applied to liquids and solids in the temperature range of 0 to 350°C. In this paper an all-silica fiberoptic probe is described which is useful for spectral analyses from 0 to 1600 K and can be used in harsh chemical environments. The probe has been used for Raman spectral analyses of many molten salt and solid material systems to 1000°C. It has applications for such studies at higher temperature ranges. The instrumentation required along with the demonstrated and proposed applications of the all-silica probe are presented and discussed.IntroductionThere are many kinds of scatter-emission spectroscopies that are of value for analytical measurements. Fluorescence, reflectance, arc or spark emission are descriptors for some of these. Raman scatter spectroscopy is also quite a useful technique for analytical measurements.In Figure 1, we give a simplified explanation of the Raman effect. If one shines monochromatic light into a sample, light may be absorbed, exciting the sample to some virtual state. We know from experience that almost all of the light is re-emitted in the same wavelength range. This is called Rayleigh or Mei scattering and is designated in the figure by the arrows in both examples that point up and down from the same lower energy state. A very small percentage (the order of 10-4%) of the monochromatic light is re-emitted leaving the sample at a vibrationally-excited state. Thus, this light is at a distinctly lower energy compared to the exciting radiation. This is called a Stokes shift and is represented in the left-hand example by an arrow descending to a more energetic vibrational state. If the sample is not at a temperature of absolute zero, some of this vibrationally excited state will be thermally populated. That portion of the sample still absorbs and re-emits exciting radiation as Rayleigh scattered light, but a small percentage of the exciting light is re-emitted as the sample relaxes to the lower vibrational state. The energy of this light is of higher energy and is called an anti-Stokes shift, depicted in the example to the right. Notice that the energy separation of the Stokes or anti-Stokes shifted emission from that of the exciting radiation is the same, and expressed in ~cm-I. The intensity of either shifted emission is a function of the population of the vibrational energy states; therefore, the ratio of the intensity of Stokes to anti-Stokes signal varies with absolute temperature. We will come back to this point later."

Jan 1, 1997

By N. V. . Panishev

The Bakal (South Ural, Russia) deposit of iron ore bearing iron carbonate (siderite) with the capacity of more than 1 billion tones belongs to the MMK. This ore cannot be fully processed via blast furnace technology because of high content of MgO. According to the investigations carried out in the USA and Japan in 1999-2004 the ITmk3 (Ironmaking Technology mark three) RHF technology is a breakthrough in Ironmaking. Four iron ore types (hematite, magnetite, high and low Al2O3/SiO2) were tested. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from iron carbonate bearing ore via the ITmk3 by means of the lab scale testing. Samples of iron ore and carbon reductant were chemically and physically analyzed. Green pellets were processed via a lab tube furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.

Jan 1, 2010

By S. Ajima

The Naoshima Smelter and Refinery is the most important copper operation of Mitsubishi Materials Corporation. There are a Mitsubishi Continuous smelter and a conventional type of copper tankhouse. The continuous smelter with 240,000 mtpy of anode production was commissioned in May 19914 replacing two existing smelters, i.e an original Mitsubishi Process line and a conventional reverberatory furnace line. In July 1992, the copper tankhouae was expanded for the purpose to close the gap of production capacity between the smelter and the tankhouse. The cathode production capacity was increased from 13,800 to 15,800 mtpm. By these plant modifications, the distribution of minor elements was significantly changed and the impurities load is getting on increase reflecting recent shortage of clean copper concentrates supply. The paper discusses the distribution of minor elements and the impurity control strategy at the smelter end the refinery.

Jan 1, 1995