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By Osamu Yamamoto

In antibacterial evaluation of carbon-ceramic composites, we prepared two type composites with emphasis on carbon-ZnO system; one was porous carbon materials containing ZnO nano-particles and another was porous ZnO coated with carbon thin film. Porous carbon samples containing ZnO at highly dispersed state were prepared by carbonizing the resin exchanged by Zn2+ ion. Porous ZnO coated with carbon thin film was obtained by the pyrolysis of poly (vinyl alcohol). Antibacterial activity of these composites obtained was evaluated by measuring the changes in electrical conductivity with bacteria growth. The antibacterial activity on the composites increased with the increase of t he amount of ZnO in composite and decreased with the increase of carbonization temperature. The antibacterial activity for Staphylococcus aureuswas found to be stronger than that for Escherichia coli. No activity of the carbon samples without ZnO was observed. The occurrence of antibacterial activity was supposed to be due to the generation of hydrogen peroxide from ZnO in composite. In the present work, antibacterial activity of carbon-ZnO composites was studied in the details.

Jan 1, 2006

By Kouji Mimura, Masahito Uchikoshi, Minoru Isshiki

"HfO2 is expected to be a gate dielectric used in ULSI alternatives to S1O2. Although the materials used in ULSI are required to be significantly pure, commercial Hf contains > 2 mass% Zr. It is important to establish a process for removing Zr from Hf. In the present study, anion-exchange separation using a multi-column method was employed. The separation tests were carried out at variety of temperatures and flow rates. The decrease in the flow rate of the mobile phase made the elution curves of both Hf(IV) and Zr(IV) broaden contrary to the case of Co(II), Cu(II), or Fe(III). This is caused by the difference in adsorption rate on the anion exchange resin. In addition, more than one column was connected in series in order to enhance the separation. As a result, the content of Zr(IV) was successfully reduced to 1/100 of that relative to the raw material.IntroductionHafnium is one of the most important materials in modem society. The main applications of Hf metal are as a control rod in a nuclear reactors because of its large neutron-capture cross-section and as an additive to various alloys because of its corrosion resistance [1]. In addition to those applications, attention has been recently paid to HfCh as a high-x"" dielectric used in ultra large scale integration, ULSI, as well as ZrCh, AI2O3 and La2C>3, which are expected to be alternatives to conventional S1O2 thin films [2].The materials used in ULSI are required to have a high purity in order to avoid unexpected errors due to impurities. Furthermore, high purity Hf is indispensable for investigating the intrinsic properties of Hf metal. Thus, it is significant to establish the purification process for Hf from both the industrial and academic perspectives."

Jan 1, 2012

By F. Mucciardi

While flash smelting and converting are capturing a greater share of the market, injection through circular injectors will remain with us for the foreseeable future. The use of top lances for injection is a key feature in several processes (e.g. Mitsubishi, Ausmelt). Tuyeres, on the other hand, are incorporated into a number of processes (e.g. Noranda, Peirce-Smith). To date no lances or tuyeres are cooled by an external source. The reagent provides the bulk of the cooling. With limited cooling, it is normal to have substantial wear on the nozzles - especially in the case of lances. To overcome the issue of wear, a new patented injector (lance or tuyere) has been developed by Noranda and McGill University. This novel unit is based on heat pipe technology. It can operate for an extended period of time without wearing. Enhanced lance/tuyere life is achieved by operating the injector at a low enough temperature that promotes the formation of a thin frozen layer on the outer body of the unit. The vaporizing and condensing substance within the unit acts to cool' the high heat flux portions and dissipate the heat to areas of low heat flux outside the vessel. A fairly large number of tests have been conducted with a prototype unit. The tests have shown that the heat pipe lance is a viable unit. In this paper is detailed a test which illustrates how the lance functions when pure oxygen is injected into copper matte. In addition, the findings from a basic study of a heat pipe in high heat flux environments are also presented.

Jan 1, 1999

By F. Patisson

One of the major issues with multiparticle reactors is to handle their multiscale aspect. For modeling, it usually comes to coupling a reactor model (describing the phenomena at the macroscopic scale) with a so-called grain model (simulating the behavior of a single grain or a particle). An interesting approach proposed by H.Y. Sohn (1978) is to use the law of additive reaction times in order to calculate, approximately but analytically, the reaction rate of a particle in the reactor model. Its great advantage, compared to a numerical grain model, is to drastically reduce the computation time, particularly in the case of complex reactor models. This is the approach we retained for modeling the moving bed furnace, a counter-current gas-solid reactor used in the nuclear fuel-making route for producing uranium tetrafluoride from uranium trioxide. The numerical model we developed is 2-dimensional, steady-state and based on the finite volume method. It describes solid and gas flow, convective, conductive and radiative heat transfers, and six chemical reactions involved in the process. The law of additive reaction times is used to calculate analytically the rate of the three principal gas-solid reactions at every discrete point in the reactor. We have demonstrated the validity of this approach by comparing its results with those calculated from a numerical grain model. Also detailed in the paper are the main results of the moving bed furnace model itself and the possibilities of optimizing the process revealed by the calculations.

Jan 1, 2006

By Godwin M. Beene

Large scale mining operations started in Zambia in 1913 and rapidly expanded during the post 1930 period with the opening of several mining and processing plants on the present Zambian Copperbelt. As a consequence of poor tailings dumps design methods at the start of the mines, and in view of stringent Government Legislation pertaining to environment in the recent years, Nkana Mine has developed a unique method of dump construction at its current tailings depository, Tailings Dam 15A. This method has enabled the revegetation of the dump retaining walls while construction is still in progress, a situation which was not possible on the older dumps. Cowdung has proved to be a superior fertilizer for providing plant nutrients on the tailings. The new method of dump walls construction and walls rainwater runoff drainage system has almost eliminated tendency of gully formation which is common on older dumps, as rainfall on the Zambian Copperbelt comes in intense thunderstorms. The decanted water from the dump is discharged to the natural environment in a controlled fashion after ensuring that it meets the Zambian Government Statutory requirements.

Jan 1, 1999

By Patrick R. Taylor

In the search for the development of more "environmentally friendly" and more intensive waste disposal approaches to meet more and more stringent environmental regulations, thermal plasma-based processes are considered one of the most promising alternatives to well- established technologies such as incineration. This paper presents an overview on the research and development status of thermal plasma-based waste remediation technologies. The properties of thermal plasma are described. Due to its unique feature of high-energy intensity and super high temperature, thermal plasma is particularly capable of destroying organic- containing wastes. Its potential and promising application to waste remediation may include: treatment of incinerator ashes; metallurgical dusts (especially, electric arc furnace dust); medical wastes; radioactive wastes; and other Resource Conservation and Recovery Act (RCRA) listed hazardous wastes. Many research institutes and vendors have been involved in the development of thermal plasma-based waste treatment technology encouraged by the cleanup programs supported by the Environmental Protection Agency (EPA), the Department of Energy (DoE) and the Department of Defense (DoD). More recently, thermal plasma-based waste treatment technologies (sometimes called plasma-enhanced pyrolysis) are focused more and more on not only just destroying organic wastes but also on how to practically, and economically recover energy contained in the organic waste materials in addition to the recovery of metals in order to offset the high operating costs.

Jan 1, 2003

By S. Yokoya

With increasing requirement of steel productivity and quality in continuous casting in the conventional casting system using an immersion nozzle, it is very difficult to establish a reasonable molten flow pattern. In order to overcome this difficulty, we propose a new method of imparting swirling motion onto the flow in the immersion nozzle and to control the flow pattern in the mold. Following results have been obtained during the studies. For the case of slab continuous casting mold: High amplitudes of oscillation with a period of 10 to 15 seconds are observed in the outlet flow of the immersion nozzle and meniscus flow in the conventional casting system, while these phenomena are remarkably suppressed using swirling motion in the immersion nozzle, which leads to very calm and uniform flow pattern at the outlets of the immersion nozzle, in the mold and on the meniscus in the mold; For the case of billet continuous casting mold: (1) heat and mass transfer near the meniscus can be remarkably activated compared with a conventional straight type immersion nozzle without swirl, and (2) Quite different mold flow patterns are observed between the divergent and straight immersion nozzles. Heat and mass transport in the mold using the divergent nozzle is much more reasonable compared to that of straight nozzle. The findings, mentioned above, are very useful to control the flow pattern in the slab, and billet continuous casters. Such effectiveness of swirling flow in the SEN on the mold flow has been put into practical use. As a result, remarkable progress on the quality and production of continuous casting products has been observed in practical application.

Jan 1, 2006

By Tapio Ahokainen

Commercial modeling software and increasingly efficient computers enable today computational fluid dynamics (CFD) to be used as a tool for a more comprehensive understanding of the flash smelting and flash converting processes. CFD modeling can be used for design purposes in many technological areas, but some relevant physical and chemical phenomena are still missing in the commercial CFD solver packages. Therefore, Outokumpu has developed several subroutines for solvers to describe analytically the phenomena in the flash smelting environment. CFD sub-models of the copper concentrate and matte combustion, the particle-particle-wall interactions and for more accurate radiation properties of the gas-particle suspension are needed to ensure reliability of numerical simulations on the flash smelting and converting vessels. Several basic combustion phenomena can be modeled with a number of commercial solver packages, but own models for combustion must be included in the case of sulfides as the feed. Mathematical models for copper concentrate and solid matte combustion have been developed during the last decade. They calculate compositions of the particles and temperature, based on extensive experimental research work in laboratory scale furnaces with validated kinetic parameters and temperature measurements of reacting particles. Inside and near the concentrate burner, the standard particle tracking methods do not include the particle-particle interactions and the particle-wall interaction is too much simplified to describe properly the particle collisions with the distribution cone. Therefore, additional models for the particle-particle as well as particle-wall interactions have been written and implemented. For thermal radiation, models for the emissivity of a gas mixture and for calculating the particle absorption and scattering coefficients have been developed and tested. In addition, the advanced radiation model can be used i.e. in the enhanced simulation of off-gas cooling in the heat recovery boiler area of the flash smelter.

Jan 1, 2006

By Adam C. Powell

A new Cahn-Hilliard phase field model of transport-limited electrochemistry describes phase boundary motion due to oxidation and reduction reactions at metal-electrolyte interfaces. Benchmarks demonstrating the accuracy of the method include open circuit voltage and closed circuit current in metallothermic reduction, and linear stability theory in metal electrolysis, including a new stability criterion for reduction of liquid metal from liquid electrolyte. The model is applied here to understanding cathode interface stability in titanium electrolysis e.g. in the SOM process developed with Uday Pal, and to structure evolution in subhalide reduction of titanium dichloride by magnesium developed by Toru Okabe. Potential for application to new fuel cell and battery systems is also discussed.

Jan 1, 2006

By Hee Dong Jang

Crystalline metal oxide nanoparticles such as lithium cobalt oxide (LiCoO2) and indium tin oxide (ITO) were synthesized from sprayed droplets of aqueous precursor solution by flame spray pyrolysis. Complete thermal decomposition of the aerosol precursors was obtained at high flame temperature. Molar concentrations of the precursor solution, and the flow rate of combustion gas such as hydrogen, oxygen and air were varied to control particle size, size distribution and crystal structure. The crystalline nanoparticles synthesized were nearly spherical, and their average primary particle diameters ranged from 11 to 35 nm for LiCoO2 and from 8 to 15 nm for ITO.

Jan 1, 2006

By C. Wieckert

Concentrated solar energy can be used as heat source for the production of metals. One of the most promising respective processes, the solar carbothermic production of Zn from ZnO, is investigated within the European research project SOLZINC, a cooperation of institutes and industries from France, Germany, Israel, Sweden and Switzerland. The solar produced Zn can be used as commodity or as an energy carrier for further processing on demand to electricity in Zn-air fuel cells/batteries or to generate hydrogen by reaction with steam. In both cases the Zn is oxidized to form ZnO, which can be recycled back to the solar plant. In these cyclic processes Zn acts as a means to store and eventually transport solar energy. Second product of the solar process step is a CO-rich offgas, which may e.g. drive a gas engine or may be shifted to hydrogen in a conventional reaction with steam. A pilot plant using 300kW concentrated solar power input has been constructed and operated successfully. 86mass-% of ZnO mixed with 14mass-% of charcoal are reacted to produce Zn and CO at a temperature of about 1200°C, yielding about 50 kg gaseous Zn per hour. Zn-dust with 95% purity is recovered from the offgas system that was designed to produce Zn for Zn-air fuel cells. Based on the results and findings from the pilot plant, a two tons Zn/h solar demonstration plant has been designed conceptually. Cost studies have been performed and scenarios for producing electricity or H2 via these ZnO/Zn-cyclic processes are evaluated.

Jan 1, 2006

By Keith E. Forrester

This paper presents results of bench scale laboratory evaluation of a processes developed by FESI and Brookhaven National Laboratories for the extraction and recovery of Pb and other heavy metals from incinerator ash which was subsequently modified by FESI for the extraction and recovery of Pb from soils excavated from a FESI client scrap yard and battery breaking operation facility. The specific waste matrix presented within the paper is a battery acid contaminated surficial soil at 0" to 12" depth. The extraction method was found to be highly successful on the bench scale in generating a final post-extracted soil matrix which passed TCLP Pb regulatory limits and retained minimal Pb after aggressive extraction application. The paper findings at this time are brief, as a majority of the research results are currently being compiled and additional efforts are underway based upon initial screening findings.

Jan 1, 1995

By Tatsuki Uzawa, Takashi Nagai

The consumption of Nd and Dy is increasing dramatically because of an exceptionally high demand for Nd-Fe-B-(Dy) magnets and a significant amount of the magnets are wasted. It is important to develop a recycle process the elements from the wasted magnets. In this study, Nd and Dy were extracted from the magnets by silver at high temperature. Nd can be extracted more than 70 % by silver. However, Dy is extracted only 25 % in the same experimental condition.

Jan 1, 2014

By KAGAN BENZESIK, Onuralp Yücel, Mehmet Bugdaycı, Ahmet Turan

ZrB2 and B4C are one of the most significant advanced ceramics. They are being used in various industrial areas from space technology to nuclear industry owing to their physical properties such as high melting point, high thermal/electrical conductivity and low density. Present study was conducted in two main stages: Self-propagating high-temperature synthesis (SHS) reactions and leaching. ZrO2, Carbon black, B2O3 were used as starting material to produce ZrB2-B4C powders by SHS. Also Mg powder was used as the reductant. The reaction mixtures (approximately 100 g) were mixed thoroughly 15 minutes in a turbula mixer and charged into Cu crucible and compacted. W (tungsten) wire was placed at the top of copper crucible and the reaction realized by passing current through the wire. After initiation, a highly exothermic reaction became in a self-sustaining mode and propagated throughout the SHS mixture. The samples were characterized by using AAS and X-Ray Diffraction.

Jan 1, 2016

By Junji Shibata

Through-hole copper plating is performed to make a multi-layer printed circuit board. The through hole plating is first carried out by Pd catalyst treatment, followed by copper non-electric plating. The amount of Pd catalyst used in one plant is about 0.25-2 m3/month (8 g/dm3 PdCl2 base) depending on the plant scale, and the cost of the catalyst reaches 17,000¬I35,000 US$/month. In this study, the flow and material balance of a Pd in Pd catalyst treatment process was investigated. About 60% of Pd catalyst adheres on the through-hole and other part of setup, while 25% is released into the washing liquor. Pd in the washing liquor should be collected by a suitable method like a pressure filtration using diatomite. The material balance of Pd in Pd catalyst treatment process and the recovery method of Pd from waste solution containing Pd catalyst was investigated.

Jan 1, 2003

By W. G. Davenport

Chapter 6 examined autotherrnal smelting of pure chalcopyrite concentrate with 50 mass% O2-50 mass% N2 blast. It showed that production of 1500 K products with this blast requires: 181 kg of pure oxygen 337 kg of air per tonne, of concentrate. It also showed that the grade of matte produced with this blast is 58% Cu. This chapter re-examines autotherrnal smelting by asking: (A) WHAT COMPOSITION BLAST (MASS% 02 -MASS% N2), 298 K, WILL AUTOTHERMALL Y PRODUCE 65% Cu MATTE 1500 K FROM PURE CHALCOPYRITE CONCENTRATE? (B) HOW MUCH PURE OXYGEN AND AIR WILL BE NEEDED? These are important questions for flash? smelting because furnace operators usually want to send specific composition matte to converting. This chapter shows how a specified matte can be produced autotherrnally with 298 K oxygen-air blast. Later chapters show how it can be done with hot blast, hydrocarbon combustion, different concentrates etc.

Jan 1, 2001

By J. R. Rendón

Cylinders of commercial aluminium alloy 6063 were homogenized under different conditions. The experimental results indicated that the general mechanical behaviour as related to curves of 0.2% yield strength, ultimate tensile strength and Brunnell hardness versus homogeneizing process is the same in both cases. The mechanical properties as compared to those required by plant specifications, tend to be better with increasing values of % Mg2Si in the alloy, as expected. The electron microscopy investigations revealed that in both homogeneizing processes the resulting microstructure consist of significant spheroidizing of the alpha phase (AlFeSi) and fine-needle type structure of beta phase. The alpha phase was also present in a Chinese type scripture. Furthermore, the slow cooling within the furnace resulted in the nucleation and growth of Mg2Si precipitates generally along the grain boundaries.

Jan 1, 1997

By P. Sergi

A method of characterizing gold ores with respect to processing is proposed. The method includes microscopical examinations to obtain qualitative and quantitative data that relate to processing. The main thrust, however, involves laboratory heavy liquid separation tests, laboratory amalgamation tests, and laboratory cyanidation tests to determine the proportions of gold that can be recovered in a conventional processing operation. Two different Brazilian gold ores: a quartz vein gold ore, and gold in metasediments were tested.

Jan 1, 1989

By Masahiro Sasaki, Wu Kepeng, Chang-Yong. Kang, Kohji Okada, Naohiro Igata, Kazuya Miyahara

"The damping capacity of the Fe-12 mass % Cr-6 to 30 mass % Mn alloys has been investigated. Particularly the effects of microstrucutre composed of the phases of a , a ' , y , and e on the damping capacity have been clarified. Various fraction of these phases were formed depending on the Mn content and cold work degree. The combination of 22 mass % Mn and 50% cold rolling formed the largest volume fraction of e martensite and showed the highest damping capacity. The other phases of a, a' and y had very small effect on the increasing of damping capacity.IntroductionFe-Mn alloys are known to be one of the high damping capacity materials [l-3]. In the present research, the damping capacity of the Fe-12 mass % Cr-6 to 30 mass % Mn alloys, in which 12% Cr is added for the improvement of corrosion resistance of the Fe-Mn alloys, has been investigated. Particularly the effects of microstrucutre composed of various phases of a (bee), a ' (bet martensite), y (fee), and e (hcp martensite) on the damping capacity have been clarified. The results of preliminary research on Fe-Cr-Mn alloys are reported by Igata et al. [4] Various volume fraction of these phases were formed depending on the Mn content and cold work degree. The combination of 22 % Mn and 50% cold rolling formed the largest fraction of e martensite and the measurement indicated clearly that e martensite had the largest effect on the damping capacity. The other phases of a ' y and a I had very small effect on the increasing of damping capacity."

Jan 1, 2000

By Xiangru Chen, Qijie Zhai, Wei Zhang, Haicheng Li, Chao Yang

In this paper, ductile iron material with different content of niobium was prepared by a scientific melting method. Image Analysis Software was used to studied the effect of niobium microalloying on both pearlite content and pearlite lamellar spacing in ductile iron quantitatively. The results showed that the addition of a small amount of niobium could increase the pearlite content and decrease pearlite lamellar spacing of ductile iron effectively.

Jan 1, 2015