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By G. Gomathi, K. Asokan, K. Subramanian

An electrochemical reactor with anode and cathode chambers separated by a composite perfluoro polymer cation exchange membrane was designed, fabricated and used for the reduction of dissolved carbon dioxide under ambient conditions to formate. The flow reactor enhanced the mass transfer of carbon dioxide compared to the batch reactor. Experiments were conducted using two different perfluoro polymer membranes - Nafion 961. Efficacy of CO2 reduction on various cathode materials (Cd, Pb, Sn and Zn plated stainless steel woven mesh) were determined. Optimum values of flow rate and current density were evaluated for the energy efficient formation of formate in aqueous KHCO3 (pH 7.5-8.5) buffer solutions.

Jan 1, 2008

By Vaughan R. Voller

In many high temperature processes involving liquid melts the common practice is to solidify a fraction of the melt adjacent to the containment wall; a practice that can provide protection of the structural components of the process. The position, shape and transient behavior of these so called "skulls" and/or "ledges" are directly dependent on the thermal process conditions. This paper presents a model of a generic ledge process that can predict the steady shape of a ledge. Two numerical implementations are presented and compared: (1) based on a space grid of continuously deforming finite elements (2) based on a conjugate grid of fixed control volumes and deforming boundary elements.

Jan 1, 1996

By R. P. Rao

In rare earth (RE) based phosphors, high luminous efficiency is possible due to their restricted emission limited to specific narrow bands. In general, these phosphor materials consist of RE ions as activators/sensitizers and/or hosts. Development of various phosphor host matrices such as alkaline earth chlorophosphates, aluminates and silicates activated by Eu(2+) as blue component, borates and phosphates of lanthanides and alkaline earth aluminates doped, with Ce/Bi and Tb as green component and Eu(3+) activated yttrium oxide and vanadate as red component has been described. Luminescent characteristics, color coordinates and suitability of these phosphor materials in high efficiency new generation lamps are presented and discussed.

Jan 1, 1989

By D. G. Schmidt

Tests were conducted on C86200 high-strength yellow brass in order to ascertain the effect of a low level of nickel on the mechanical properties on this alloy. A series of two alloys was studied, one of which had a nickel content of 0.85% and the other with <0.05% nickel. Copper and aluminum content ranged from 62.5% to 64% and 3.2% to 4.6%, respectively. When compared by zinc equivalents, a nickel addition of 0.75% in high-strength yellow brass does not act like copper but raises the tensile strength, 0.5% yield strength and BHN while lowering the elongation.

Jan 1, 1999

By G. Springer

The identification of lost mineral values in mill tailings frequently requires the inspection of hundreds of thousands to millions of particles. The search of these particles can be made automatic by using an electron microprobe. A standard instrument (Cambridge Mark V) was modified by the addition of stepping motors to advance the specimen stage in a controlled manner. The X-ray Signal is monitored continuously by a computer interfaced to the instrument with an analog-to-digital converter. 400,000 particles of a tailings sample can be scanned in about 3 hours. Particles as small as 2 um and containing as little as 3% of a particular element can be detected.

Jan 1, 1982

By A. V. Tarasov, V. M. Paretsky

"The design is based on the thermal processing of the wastes in· the intensively bubbled melt in the Vanyukov furnace at the relatively high temperatures (1350- 1450 °C), In this case: -the secondary wastes are not formed; - the especially toxic substances at the outlet from the furnace are absent. The technology was tested on a large scale (on semicommersial bases). Technical and economical basis show profitability of recovery complex for processing of hard garbage waste (HGW) using this technology: the period of capital, investments refunding for the, recovery, complex construction with process annual capacity of 240 thousands tons of wastes is 1,5-2,5 years,"

Jan 1, 2000

By William A. Fuchs

A study of carbonaceous ore at the Santa Fe mine (Corona Gold Inc.) shows that there is no quantitative relationship between organic carbon content and preg rob, although much of this material preg robs. However, there is a relation between K20 and preg rob. Preg rob generally occurs only in those samples with greater than 2% K20. X-ray diffraction and chemical . studies show that the critical factor is the illite content of mixed (possibly interstratified) illite-smectite. Apparently illite, at a certain threshold, "geo-activates" the carbon. The potential for easily monitoring preg rob using a gamma ray spectrometer is discussed.

Jan 1, 1990

By Shengqin Zhang, Jagannath Pal, Yousef Mohassab, Hong Yong Sohn, Mohamed Elzohiery

The kinetics of magnetite reduction with mixtures of hydrogen and CO of various compositions has been investigated as part of the development of a flash ironmaking process at the University of Utah. This new process bypasses the cokemaking and pelletization or sintering steps required for the blast furnace. The particle kinetics were studied using magnetite concentrate particles of different sizes. Reduction degree of 60% was achieved in a few seconds in at 1350 oC using CO reductant alone and over 90% when H2 + CO gas mixture was used. The effects of reductant partial pressures, temperature, and particle size on the reduction kinetics were studied.

Jan 1, 2016

By Shantaliu S. Shevade, Muhammad M. Rahman

"This paper presents a systematic analysis of fluid flow and heat transfer processes during the magnetic heating of the substrate material. Heat is generated in the substrate material when a magnetic field is imposed due to change in orientation of the molecules. As a result, the substrate temperature rises. The i;tudy considered microchannels with rectangular and square cross section with heat generation in the substrate due to imposed magnetic field. The results computed were for Gadolinium substrate and water as the working fluid. The purpose of this study is to explore the transient heat transfer coefficient when the fluid is circulated through the substrate via microchannels. Equations governing the conservation of mass, momentum, and energy were solved in the fluid region. In the solid region, heat conduction was solved. From the simulation results, plots of Nusselt number and heat transfer coefficient were obtained over the length of the channel. A thorough investigation for velocity and temperature distributions was performed by varying channel aspect ratio, Reynolds number, and heat generation rate in the channel. It was found that the peripheral average heat transfer coefficient and Nusselt number is larger near the entrance and decreases downstream because of the development of the thermal boundary layer. With the increase in Reynolds number, the outlet temperature decreased and the average heat transfer coefficient increased.IntroductionMagnetocaloric effect (MCE) is the heating or cooling of the magnetic materials due to varying magnetic field. The effect was originally discovered by Warburg. Magnetocaloric materials store heat energy in the way the atoms vibrate and in the way electrons spin within each atom. More heat energy increases the vibrations and also makes the spins more random. When a strong magnetic field is applied to a magnetic material, the magnetic moments of its atoms become aligned making the system more ordered. The more ordered material has lower entropy and compensates for the loss by heating up. When the magnetic field is removed, the magnetic moments return to their random directions, entropy increases and the material cools. Gadolinium is a magnetic material that exhibits high temperature rise during adiabatic magnetization around its transition temperature of 295 K. It has been experimentally observed that adiabatic temperature rise increases with magnetic field strength and can be as high 20 K when a magnetic field of IO T is applied. Thus magnetic field, when applied to a microchannel heat exchanger, causes temperature change in the magnetic material. The fluid flowing through the channel gets cooled or heated due to this adiabatic temperature change."

Jan 1, 2004

By William J. Pardee, Michael A. Shaff

"Deeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will accelerate productivity growth and materials science application through the ease with which they can be modified to accept new materials knowledge and sensors. Carbonization of resin matrix carbon fiber composites, specifically, is a violent solid state chemical reaction with large stresses due to gas pressure, matrix shrinkage, and differences in thermal expansion. The matrix strength falls sharply, then rises again during the process. At least two competing reaction paths are important; the first cleaves methylene bonds, reduces toughness, density and stiffness; the second reforms those bonds, ultimately resulting in aromatic ring condensation that increases density, strength, and modulus. Since these reactions have different temperature dependencies, one can expect to shift the process towards the second path by changing the heating rate, but that change must be accomplished without producing macroscopic interlaminar crack growth. To accomplish this, we employ gas sensors to infer matrix chemical state and acoustic emission to identify microstructural changes and to recognize brittle fracture. The latter does not prevent delamination, but is important in testing models for the causes of delamination and in improving the processing cycle. This paper describes a control strategy to accelerate the process while still lowering the risk of failure.IntroductionDeeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will be more easily modified to accept new materials knowledge and sensors, thus accelerating productivity growth. Such a control strategy for carbonization control is described below.Carbon-carbon composites are time consuming and costly to manufacture. Processing methods have been developed empirically and are usually very conservative because the process often fails when any change is made. Apparently minor changes in materials or geometry can produce failures that are difficult to diagnose and correct. We will describe below several essentially unavoidable sources of variability. These are best dealt with by applying materials science to adapt (i.e., closed loop control on materials properties) the process in real time to reduce the effect of unavoidable model idealizations, material variability and environmental noise. The most critical issue in control of the carbonization process control is avoiding catastrophic delamination. The strategy developed below makes use of a priori materials knowledge and real time sensors to accelerate the now very slow process without destroying the material, and without requiring unreasonable resources to determine the statistical properties of the material."

Jan 1, 1988

By J. C. DeSantis

Thin, highly reflective rhodium films with metal compositions greater than 98% (elemental -weight percentage) have been deposited by chemical vapor deposition using Rh(allyl)3 (ally1 = q3-C3H5) in the presence of a hydrogen plasma. Uniform, crystalline films that adhere well to several types of substrates result from depositions at temperatures as low as 150°C. Depositions using H2 (no plasma), or an argon plasma yields material that is amorphous, contains a significant amount (>14%) of residual carbon, and has a dramatically slower growth rate. The composition of these materials does not vary significantly from that of the materials obtained from the in vacuo thermal deposition with Rh(allyl)3.

Jan 1, 1992

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 Yue Tian, Shengqian Wang, Lifeng Zhang

This paper is to discuss the removal of non-metallic inclusions from molten steel using a high frequency magnetic field. In experiments, a certain amount of aluminum was added to the molten steel in a crucible to generate aluminum inclusions. A layer of aluminum clusters were observed close to the wall of the crucible after the electromagnetic (EM) field was imposed. Three dimensional EM field and fluid flow simulation were performed and showed that over 91% inclusions transported to the skin depth (2.31 mm) of the molten steel. The calculation of inclusion removal agreed well with the experimental observation. The separation mechanisms of inclusions from the molten steel by the high frequency EM field were discussed.

Jan 1, 2014

By Shuichiro Okada

Various efforts to reduce energy consumption and smelting cost are made at Tamano Smelter. Production of anode copper has been increased by about 30 % and energy requirement has been decreased about 50 % respectively. Challenges toward more higher goal are being continued. Details about the following are described in this paper. 1 Waste heat recovery Steam recovery at up-take of FSFE Heat recovery from waste gas of anode furnaces 2 Application of tonnage oxygen 3 Application of pulverized carbonaceous fuels to the flash smelting furnace with furnace electrodes ( FSFE ) 4 Application of computer control system to copper smelting 5 Improvement of the fugitive gas collecting system 6 Improvement of the mechanical tuyere puncher for the converter furnace

Jan 1, 1983

By Milan Lj. Stamatovic

The hydrometallurgical recovery of zinc from recycled blast furnace dust from a steel plant (Smederevo Metallurgical Company, Yugoslavia) was investigated. The dust contained 22% Fe, 17% Zn and 0.2% Pb. X-Ray diffractometry showed that the main components were hematite and magnetite, in combination with zinc oxide. Individual particles were generally spherical and ranged in size from 10 to 150 microns; 63% were less than 33 microns in diameter. An effective hydrometallurgical approach proved to be by caustic leaching and electrowinning. Recovery of zinc in the form of zinc powder was over 90%; this material can be used for the cementation of impurities in the conventional hydrometallurgical process for zinc production.

Jan 1, 1994

By Onwukamike, Onyedika G. O, Ogwuegbu M. O. C., K., Onyenehide C

A detailed mineralogical and elemental characterization of a lead (Pb) ore deposit from Ishiagu, Ebonyi State, Nigeria was carried out with XRD, SEM-EDX, and ICP-OES based mappingtechniques. The results show that the most dominant and valuable metal is lead (Pb = 95.02%, mass fraction). The main mineral is galena. Ilmenite and sphalerite occur as minors, which account for 2.71% and 0.80% respectively. Elements like Al, Ca, Mg, Ti, Na, Mn, Si and Sn occurred in trace amounts and are disseminated in the entire ore body.The surface and interrelations of the crystals were examined with x-ray mapping and the result shows the pattern of dissemination of the minerals within the ore body.

Jan 1, 2015

By Sylvain Gouttebroze, Mohammed M'Hamdi

In a previous work, a small scale Bridgman furnace has been used to study silicon bi-grain crystallization at different cooling rate. This work expands the analysis by studying the mechanical interaction between the crucible and ingot during the solidification and cooling. The thermal model is based on a 2D-axisymetric heat-transfer model. The flux histories are then transferred to the ingot-crucible 3D-model. Anisotropic Elastic and Crystal Plasticity model are used to model the silicon deformation. Four different assumptions are applied to model the mechanical contact crucible-ingot and three grain misorientations are considered. The results show the strong impact of the alumina crucible contraction on the stresses and deformations in the silicon ingot.

Jan 1, 2015

By Elsa Agante

Recycling of solid wastes, a common practice nowadays, requires the separation of the different materials in order to increase the products added value. The separation of one plastic from mixtures of different types of plastics is not easy due to their similar physical properties, but different techniques are available, from automatic sorting systems based on optical sensors to techniques adapted from mineral processing, namely gravity, froth flotation and electrostatic processes. In the last decade, many researchers have addressed the separation?s problem of different polymers, like Polyethylene Terephthalate (PET) and Polyvinyl Chloride (PVC), two polymers commonly used in packaging which have similar density. One proposed technique is the classical froth flotation performed in agitated cells. Froth flotation is a versatile and relatively cheap process widely used in mineral separation. It is based on the different behaviour of particles in the presence of an inter-phase air-water, which depends on the materials surfaces properties. Froth flotation can be affected by some variables such as impeller speed and air flow rate. Agitated cells, when used with low density materials, like plastics, can produce overstated turbulence that prevents the adhesion and collection of particles in the froths. In this case, separation is favoured by column flotation smoother hydrodynamics. This paper proposes the separation of PET from PVC by column flotation. The experimental work was carried out in a column of 9cm diameter and 1m high. The effects of some operating conditions, such as depressor and frother concentration, air flow rate and feed grain size on products grade and recovery were evaluated and the best flotation conditions for the separation of these plastics were established.

Jan 1, 2006

By J. Van Boven

The Hoboken plant has continued the program, started in 1973, for monitoring the impact of processes on the environment. Progressive improve¬ments including new installations and equipment have been commissioned resulting in reduced emissions of lead in air. The Hoboken Smelter now fully complies with regulation and observes a yearly mean value of less than 2 micrograms Pb per cubic meter of air in the vicinity of the plant. In addition a new central water-treatment installation permits the discharge of waste water to the River Schelde in accordance with present day regulations. Mention is made of methods used to measure the emissions and immissions at the plant. Results of modifications and new installations recently commissioned are discussed.

Jan 1, 1983

By Seiji Yokoyama

As a series of fundamental study on the gas evaporation method, a levitation-melted aluminum was evaporated in the gas mixture of argon and ammonia to synthesize ultrafine particles of aluminum nitride. When the ammonia partial pressure were more than 2kPa, the formation ratio of aluminum nitride was about 95%. The particles of aluminum nitride were mainly hexagonal. The mean size of the particles of aluminum nitride was about 57 nm, and it was constant without depending on the temperature of the levitated aluminum and the partial pressure pf ammonia. The aluminum nitride was formed by the reaction between ammonia and condensed liquid aluminum particle whose size was relatively small.

Jan 1, 2006